@article{goralska_fleisher_mcgahan_2017, title={Vitreous Humor Changes Expression of Iron-Handling Proteins in Lens Epithelial Cells}, volume={58}, ISSN={["1552-5783"]}, DOI={10.1167/iovs.16-20610}, abstractNote={Purpose In humans, vitrectomy is associated with development of nuclear cataracts. Iron catalyzes free radical formation causing oxidative damage, which is implicated in cataract formation. This study was designed to determine if vitreous humor, which can initiate differentiation of lens epithelial cells, would have an effect on iron-handling proteins. Methods Cultured canine lens epithelial cells were treated with collected canine vitreous humor. Lysates of treated and control cells were separated by SDS-PAGE. Ferritin H- and L-chains, transferrin receptor 1, and aquaporin 0 were immunodetected and quantitated with specific antibodies. Morphologic changes in treated cells were assessed. Results Treatment of lens epithelial cells with a 33% (vol/vol) solution of vitreous humor changed the morphology of lens cells and induced expression of aquaporin 0, a marker of fiber cell differentiation that was undetectable in control cells. Treatment did not modify the size of iron-handling proteins but significantly increased content of ferritin from 2.9- to 8.8-fold over control and decreased levels of transferrin receptor by 37% to 59%. Conclusions Vitreous humor may significantly limit iron uptake by transferrin/transferrin receptor pathway, and by increasing ferritin levels could profoundly increase the iron-storage capacity of ferritin in lens cells. Vitreous humor may play a significant protective role against iron-catalyzed oxidative damage of lens epithelial cells and therefore in the formation of cataracts.}, number={2}, journal={INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE}, author={Goralska, Malgorzata and Fleisher, Lloyd N. and McGahan, M. Christine}, year={2017}, month={Feb} }
 @article{mowat_hash_mzyk_harned_nagar_mcgahan_2016, title={Evaluation of the proliferative capacity of canine retinal pigment epithelial cells harvested from different regions of the fundus}, volume={57}, number={12}, journal={Investigative Ophthalmology and Visual Science}, author={Mowat, F. M. and Hash, J. and Mzyk, P. and Harned, J. and Nagar, S. and McGahan, M. C.}, year={2016} }
 @article{mzyk_mcgahan_2016, title={Hypoxia alters the expression, movement, and secretion of APP in retinal pigmented epithelial (RPE) cells}, volume={57}, number={12}, journal={Investigative Ophthalmology and Visual Science}, author={Mzyk, P. and McGahan, M. C.}, year={2016} }
 @article{harned_nagar_mcgahan_2014, title={Hypoxia controls iron metabolism and glutamate secretion in retinal pigmented epithelial cells}, volume={1840}, ISSN={["1872-8006"]}, DOI={10.1016/j.bbagen.2014.06.012}, abstractNote={Blood-barrier systems are essential in controlling iron levels in organs such as the brain and eye, both of which experience hypoxia in pathological conditions. While hypoxia's effects on numerous iron regulatory and storage proteins have been studied, little is known about how hypoxia affects iron metabolism. Iron also controls glutamate production and secretion; therefore the effects of hypoxia on iron metabolism and glutamate secretion were studied in polarized retinal pigmented epithelial (RPE) cells. Primary canine RPE were cultured in Millicells to create polarized cell cultures. Iron uptake and efflux were measured in hypoxic and normoxic conditions. RPE were loaded with 59Fe-transferrin. Glutamate concentrations in the cell conditioned media were also measured. Hypoxia induced a large increase in iron efflux from RPE in the basolateral direction. Glutamate secretion occurred mainly in the basolateral direction which is away from the retina and out of the eye in vivo. Glutamate secretion was doubled under hypoxic conditions. Hypoxia is known to induce oxidative damage. The current results show that iron, a key catalyst of free radical generation, is removed from RPE under hypoxic conditions which may help protect RPE from oxidative stress. Results obtained here indicate the importance of using polarized tight junctional cells as more physiologically relevant models for blood-barrier-like systems. While the effects of hypoxia on iron efflux and glutamate secretion may be protective for RPE cells and retina, increased glutamate secretion in the brain could cause some of the damaging neurological effects seen in stroke.}, number={10}, journal={BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS}, author={Harned, Jill and Nagar, Steven and McGahan, M. Christine}, year={2014}, month={Oct}, pages={3138–3144} }
 @article{goralska_fleisher_mcgahan_2014, title={Hypoxia induced changes in expression of proteins involved in iron uptake and storage in cultured lens epithelial cells}, volume={125}, ISSN={["1096-0007"]}, DOI={10.1016/j.exer.2014.05.010}, abstractNote={Hypoxia inducible factor (HIF) regulates expression of over 60 genes by binding to hypoxia response elements (HRE) located upstream of the transcriptional start sites. Many genes encoding proteins involved in iron transport and homeostasis are regulated by HIF. Expression of iron handling proteins can also be translationally regulated by binding of iron regulatory protein (IRP) to iron responsive elements (IREs) on the mRNA of ferritin chains and transferrin receptor (TfR). Lens epithelial cells (LEC) function in a low oxygen environment. This increases the risk of iron catalyzed formation of reactive oxygen species (ROS) and oxidative cell damage. We examined changes in expression of ferritin (iron storage protein) and Tf/TfR1 (iron uptake proteins) in LEC cultured under hypoxic conditions. Ferritin consists of 24 subunits of two types, heavy (H-chain) and light (L-chain) assembled in a cell specific ratio. Real-time PCR showed that 24 h exposure to hypoxia lowered transcription of both ferritin chains by over 50% when compared with normoxic LEC. However it increased the level of ferritin chain proteins (20% average). We previously found that 6 h exposure of LEC to hypoxia increased the concentration of cytosolic iron which would stimulate translation of ferritin chains. This elevated ferritin concentration increased the iron storage capacity of LEC. Hypoxic LEC labeled with 59FeTf incorporated 70% more iron into ferritin after 6 h as compared to normoxic LEC. Exposure of LEC to hypoxia for 24 h reduced the concentration of TfR1 in cell lysates. As a result, hypoxic LEC internalized less Tf at this later time point. Incorporation of 59Fe into ferritin of hypoxic LEC after 24 h did not differ from that of normoxic LEC due to lower 59FeTf uptake. This study showed that hypoxia acutely increased iron storage capacity and lowered iron uptake due to changes in expression of iron handling proteins. These changes may better protect LEC against oxidative stress by limiting iron-catalyzed ROS formation in the low oxygen environment in which the lens resides.}, journal={EXPERIMENTAL EYE RESEARCH}, author={Goralska, Malgorzata and Fleisher, Lloyd N. and McGahan, M. Christine}, year={2014}, month={Aug}, pages={135–141} }
 @article{lall_harned_mcgahan_2013, title={Hydrogen peroxide and extracellular signal-related kinase 1/2 pathway regulate ferritin levels in retinal pigmented and lens epithelial cells}, volume={19}, journal={Molecular Vision}, author={Lall, M. M. and Harned, J. and McGahan, M. C.}, year={2013}, pages={2106–2112} }
 @article{harned_ferrell_nagar_goralska_fleisher_mcgahan_2012, title={Ceruloplasmin alters intracellular iron regulated proteins and pathways: Ferritin, transferrin receptor, glutamate and hypoxia-inducible factor-1α}, volume={97}, ISSN={0014-4835}, url={http://dx.doi.org/10.1016/j.exer.2012.02.001}, DOI={10.1016/j.exer.2012.02.001}, abstractNote={Ceruloplasmin (Cp) is a ferroxidase important to the regulation of both systemic and intracellular iron levels. Cp has a critical role in iron metabolism in the brain and retina as shown in patients with aceruloplasminemia and in Cp−/−hep−/y mice where iron accumulates and neural and retinal degeneration ensue. We have previously shown that cultured lens epithelial cells (LEC) secrete Cp. The purpose of the current study was to determine if cultured retinal pigmented epithelial cells (RPE) also secrete Cp. In addition, the effects of exogenously added Cp on iron regulated proteins and pathways, ferritin, transferrin receptor, glutamate secretion and levels of hypoxia-inducible factor-1α in the nucleus were determined. Like LEC, RPE secrete Cp. Cp was found diffusely distributed within both cultured LEC and RPE, but the cell membranes had more intense staining. Exogenously added Cp caused an increase in ferritin levels in both cell types and increased secretion of glutamate. The Cp-induced increase in glutamate secretion was inhibited by both the aconitase inhibitor oxalomalic acid as well as iron chelators. As predicted by the canonical view of the iron regulatory protein (IRP) as the predominant controller of cellular iron status these results indicate that there is an increase in available iron (called the labile iron pool (LIP)) in the cytoplasm. However, both transferrin receptor (TfR) and nuclear levels of HIF-1α were increased and these results point to a decrease in available iron. Such confounding results have been found in other systems and indicate that there is a much more complex regulation of intracellularly available iron (LIP) and its downstream effects on cell metabolism. Importantly, the Cp increased production and secretion of the neurotransmitter, glutamate, is a substantive finding of clinical relevance because of the neural and retinal degeneration found in aceruloplasminemia patients. This finding and Cp-induced nuclear translocation of the hypoxia-inducible factor-1 (HIF1) subunit HIF-1α adds novel information to the list of critical pathways impacted by Cp.}, number={1}, journal={Experimental Eye Research}, publisher={Elsevier BV}, author={Harned, J. and Ferrell, J. and Nagar, S. and Goralska, M. and Fleisher, L.N. and McGahan, M.C.}, year={2012}, month={Apr}, pages={90–97} }
 @article{harned_ferrell_lall_fleisher_nagar_goralska_mcgahan_2010, title={Altered Ferritin Subunit Composition: Change in Iron Metabolism in Lens Epithelial Cells and Downstream Effects on Glutathione Levels and VEGF Secretion}, volume={51}, ISSN={["1552-5783"]}, DOI={10.1167/iovs.09-3861}, abstractNote={PURPOSE
The iron storage protein ferritin is necessary for the safe storage of iron and for protection against the production of iron-catalyzed oxidative damage. Ferritin is composed of 24 subunits of two types: heavy (H) and light (L). The ratio of these subunits is tissue specific, and alteration of this ratio can have profound effects on iron storage and availability. In the present study, siRNA for each of the chains was used to alter the ferritin H:L chain ratio and to determine the effect of these changes on ferritin synthesis, iron metabolism, and downstream effects on iron-responsive pathways in canine lens epithelial cells.


METHODS
Primary cultures of canine lens epithelial cells were used. The cells were transfected with custom-made siRNA for canine ferritin H- and L-chains. De novo ferritin synthesis was determined by labeling newly synthesized ferritin chains with 35S-methionine, immunoprecipitation, and separation by SDS-PAGE. Iron uptake into cells and incorporation into ferritin was measured by incubating the cells with 59Fe-labeled transferrin. Western blot analysis was used to determine the presence of transferrin receptor, and ELISA was used to determine total ferritin concentration. Ferritin localization in the cells was determined by immunofluorescence labeling. VEGF, glutathione secretion levels, and cystine uptake were measured.


RESULTS
FHsiRNA decreased ferritin H-chain synthesis, but doubled ferritin L-chain synthesis. FLsiRNA decreased both ferritin H- and L-chain synthesis. The degradation of ferritin H-chain was blocked by both siRNAs, whereas only FHsiRNA blocked the degradation of ferritin L-chain, which caused significant accumulation of ferritin L-chain in the cells. This excess ferritin L-chain was found in inclusion bodies, some of which were co-localized with lysosomes. Iron storage in ferritin was greatly reduced by FHsiRNA, resulting in increased iron availability, as noted by a decrease in transferrin receptor levels and iron uptake from transferrin. Increased iron availability also increased cystine uptake and glutathione concentration and decreased nuclear translocation of hypoxia-inducible factor 1-alpha and vascular endothelial growth factor (VEGF) accumulation in the cell-conditioned medium.


CONCLUSIONS
Most of the effects of altering the ferritin H:L ratio with the specific siRNAs were due to changes in the availability of iron in a labile pool. They caused significant changes in iron uptake and storage, the rate of ferritin synthesis and degradation, the secretion of VEGF, and the levels of glutathione in cultured lens epithelial cells. These profound effects clearly demonstrate that maintenance of a specific H:L ratio is part of a basic cellular homeostatic mechanism.}, number={9}, journal={INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE}, author={Harned, Jill and Ferrell, Jenny and Lall, Marilyn M. and Fleisher, Lloyd N. and Nagar, Steven and Goralska, Malgorzata and McGahan, M. Christine}, year={2010}, month={Sep}, pages={4437–4446} }
 @article{goralska_nagar_colitz_fleisher_mcgahan_2009, title={Changes in Ferritin H- and L-Chains in Canine Lenses with Age-Related Nuclear Cataract}, volume={50}, ISSN={["0146-0404"]}, DOI={10.1167/iovs.08-2230}, abstractNote={PURPOSE
To determine potential differences in the characteristics of the iron storage protein ferritin and its heavy (H) and light (L) subunits in fiber cells from cataractous and noncataractous lenses of older dogs.


METHODS
Lens fiber cell homogenates were analyzed by SDS-PAGE, and ferritin chains were immunodetected with ferritin chain-specific antibodies. Ferritin concentration was measured by ELISA. Immunohistochemistry was used to localize ferritin chains in lens sections.


RESULTS
The concentration of assembled ferritin was comparable in noncataractous and cataractous lenses of similarly aged dogs. The ferritin L-chain detected in both lens types was modified and was approximately 11 kDa larger (30 kDa) than standard L-chain (19 kDa) purified from canine liver. The H-chain identified in cataractous fiber cells (29 kDa) differed from the 21-kDa standard canine H-chain and from the 12-kDa modified H-chain present in fiber cells of noncataractous lenses. Histologic analysis revealed that the H-chain was distributed differently throughout cataractous lenses compared with noncataractous lenses. There was also a difference in subunit makeup of assembled ferritin between the two lens types. Ferritin from cataractous lenses contained more H-chain and bound 11-fold more iron than ferritin from noncataractous lenses.


CONCLUSIONS
There are significant differences in the characteristics of ferritin H-chain and its distribution in canine cataractous lenses compared with noncataractous lenses. The higher content of H-chain in assembled ferritin allows this molecule to sequester more iron. In addition, the accumulation of H-chain in deeper fiber layers of the lens may be part of a defense mechanism by which the cataractous lens limits iron-catalyzed oxidative damage.}, number={1}, journal={INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE}, author={Goralska, Malgorzata and Nagar, Steven and Colitz, Carmen M. H. and Fleisher, Lloyd N. and McGahan, M. Christine}, year={2009}, month={Jan}, pages={305–310} }
 @article{goralska_nagar_fleisher_mcgahan_2009, title={Distribution of ferritin chains in canine lenses with and without age-related nuclear cataracts}, volume={15}, number={256-59}, journal={Molecular Vision}, author={Goralska, M. and Nagar, S. and Fleisher, L. N. and McGahan, M. C.}, year={2009}, pages={2404–2410} }
 @article{goralska_ferrell_harned_lall_nagar_fleisher_mcgahan_2009, title={Iron metabolism in the eye: A review}, volume={88}, ISSN={0014-4835}, url={http://dx.doi.org/10.1016/j.exer.2008.10.026}, DOI={10.1016/j.exer.2008.10.026}, abstractNote={This review article covers all aspects of iron metabolism, which include studies of iron levels within the eye and the processes used to maintain normal levels of iron in ocular tissues. In addition, the involvement of iron in ocular pathology is explored. In each section there is a short introduction to a specific metabolic process responsible for iron homeostasis, which for the most part has been studied in non-ocular tissues. This is followed by a summary of our current knowledge of the process in ocular tissues.}, number={2}, journal={Experimental Eye Research}, publisher={Elsevier BV}, author={Goralska, M. and Ferrell, J. and Harned, J. and Lall, M. and Nagar, S. and Fleisher, L.N. and McGahan, M.C.}, year={2009}, month={Feb}, pages={204–215} }
 @article{lall_ferrell_nagar_fleisher_mcgahan_2008, title={Iron regulates L-cystine uptake and glutathione levels in lens epithelial and retinal pigment epithelial cells by its effect on cytosolic aconitase}, volume={49}, ISSN={["1552-5783"]}, DOI={10.1167/iovs.07-1041}, abstractNote={PURPOSE
The authors previously published the novel finding that iron regulates L-glutamate synthesis and accumulation in the cell-conditioned medium (CCM) by increasing cytosolic aconitase activity in cultured lens epithelial cells (LECs), retinal pigment epithelial (RPE) cells, and neurons. The present study was designed to determine whether iron-induced L-glutamate accumulation in the CCM regulates L-cystine uptake and glutathione (GSH) levels through the aconitase pathway in LECs and RPE cells.


METHODS
The presence of xCT, the light chain of X(c)(-), a glutamate/cystine antiporter, was analyzed by RT-PCR, immunoblotting, and immunocytochemistry. Uptake of L-[(35)S]cystine and L-[(3)H]glutamate was measured in the presence or absence of transporter inhibitors. L-cystine uptake and intracellular GSH concentration were measured in the presence or absence of iron-saturated transferrin, the iron chelator dipyridyl (DP), or oxalomalic acid (OMA), an aconitase inhibitor.


RESULTS
LECs and RPE cells express xCT, as evidenced by RT-PCR analysis and immunoblotting. xCT was localized by immunocytochemistry. The authors found that the iron-induced increase in L-glutamate availability increased L-cystine uptake, with subsequent increases in GSH levels. In addition, L-glutamate production, L-cystine uptake, and GSH concentration were inhibited by OMA and DP, indicating a central role for iron-regulated aconitase activity in GSH synthesis in LECs and RPE cells.


CONCLUSIONS
These results demonstrate for the first time that iron regulates L-cystine uptake and the downstream production of GSH in two mammalian cell types. It is possible that the increase in intracellular antioxidant concentration induced by iron serves as a protective mechanism against the well-established capacity of iron to induce oxidative damage.}, number={1}, journal={INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE}, author={Lall, Marilyn M. and Ferrell, Jenny and Nagar, Steve and Fleisher, Lloyd N. and McGahan, M. Christine}, year={2008}, month={Jan}, pages={310–319} }
 @article{goralska_fleisher_mcgahan_2007, title={Ferritin H- and L-chains in fiber cell canine and human lenses of different ages}, volume={48}, ISSN={["1552-5783"]}, DOI={10.1167/iovs.07-0130}, abstractNote={PURPOSE
This study was designed to elucidate potential age-related changes in the concentration, structure, and assembly pattern of ferritin chains in lens fiber cells.


METHODS
Canine and human lens fiber cell homogenate proteins were separated by one-dimensional and two-dimensional SDS-PAGE. Ferritin chains were immunodetected and quantitated with ferritin chain-specific antibodies. Total ferritin concentration was measured by ELISA. Binding of iron was determined in vitro with (59)Fe.


RESULTS
Ferritin H- and L-chains in canine and human fiber cells of healthy lenses were extensively modified. The H-chain in both species was truncated, and its concentration increased with age. Canine L-chain was approximately 11 kDa larger than standard canine L-chain, whereas human L-chain was of the proper size. Two-dimensional separation revealed age-related polymorphism of human and canine lens fiber cell L-chains and human H-chains. Normal size ferritin chains were not identified in canine fiber cells, but a small amount of fully assembled ferritin was detected, and its concentration decreased with age.


CONCLUSIONS
Such significantly altered ferritin chains are not likely to form functional ferritin capable of storing iron. Therefore, lens fiber cells, particularly from older lenses, may have limited ability to protect themselves against iron-catalyzed oxidative damage.}, number={9}, journal={INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE}, author={Goralska, Malgorzata and Fleisher, Lloyd N. and McGahan, M. Christine}, year={2007}, month={Sep}, pages={3968–3975} }
 @article{harned_fleisher_mcgahan_2006, title={Lens epithelial cells synthesize and secrete ceruloplasmin: Effects of ceruloplasmin and transferrin on iron efflux and intracellular iron dynamics}, volume={83}, ISSN={["0014-4835"]}, DOI={10.1016/j.exer.2006.01.018}, abstractNote={Although an essential nutrient, iron can catalyze damaging free radical reactions. Therefore elaborate mechanisms have evolved to carefully regulate iron metabolism. Ceruloplasmin, a protein with ferroxidase activity, and transferrin, an iron binding protein have important roles in maintaining iron homeostasis in cells. Since oxidative damage is a hallmark of cataractogenesis, it is essential to determine iron's role in lenticular physiology and pathology. In the current study of lens epithelial cells, the effects of ceruloplasmin and transferrin on intracellular distribution and efflux of iron were determined. Both ceruloplasmin and transferrin increased iron efflux from these cells and their effects were additive. Ceruloplasmin had significant effects on extracellular iron distribution only in cases of iron overload. Surprisingly, both transferrin and ceruloplasmin had significant effects on intracellular iron distribution. Under physiological conditions, ceruloplasmin increased iron incorporation into the storage protein, ferritin. Under conditions of iron overload, it decreased iron incorporation into ferritin, which is consistent with increased efflux of iron. Measurements of an intracellular chelatable iron pool indicated that both transferrin and ceruloplasmin increased the size of this pool at 24 h, but these increases had different downstream effects. Finally, lens epithelial cells made and secreted transferrin and ceruloplasmin. These results indicate an important role for these proteins in iron metabolism in the lens.}, number={4}, journal={EXPERIMENTAL EYE RESEARCH}, author={Harned, J. and Fleisher, L. N. and McGahan, M. C.}, year={2006}, month={Oct}, pages={721–727} }
 @article{goralska_nagar_fleisher_mcgahan_2005, title={Differential degradation of ferritin H- and L-chains: Accumulation of L-chain-rich ferritin in lens epithelial cells}, volume={46}, ISSN={["0146-0404"]}, DOI={10.1167/iovs.05-0358}, abstractNote={PURPOSE
The storage of iron by ferritin is determined by tissue-specific composition of its 24 subunits, which are designated as either heavy (H) or light (L). For a better understanding of how lens epithelial cells regulate their ferritin subunit makeup, the degradation pattern of each subunit type was analyzed. In addition, age-related changes in ferritin concentration and subunit makeup were determined.


METHODS
Ferritin turnover in primary cultures of canine lens epithelial cells was determined by metabolic labeling with [(35)S]-methionine. Transient transfection with vectors containing coding sequences for either H- or L-chains were used to modify ferritin subunit makeup. Ferritin concentration was measured by ELISA. Immunodetection and fluorescence immunocytochemistry were used to study age-related changes in ferritin chain concentration.


RESULTS
Inhibition of the proteasomal protein degradation pathway by clastolactacystin-beta-lactone had no effect on ferritin degradation, whereas inhibition of lysosomal degradation markedly increased ferritin levels, confirming that this system is involved in ferritin turnover. H-chain ferritin degraded at a faster rate than the L-chain. L-chain-rich ferritin in L-chain-transfected cells formed inclusion bodies that were localized to the cytosol. Similar inclusion bodies were found in older lens cells kept in cell culture for more than 8 days.


CONCLUSIONS
Steady degradation of H-chain ferritin contributed to the maintenance of a constant level of this chain within the lens epithelial cells. In contrast, slower turnover of the L-chain resulted in accumulation of L-chain-enriched ferritin associated with cytoplasmic inclusion bodies. These L-chain-containing inclusion bodies were found in the cytosol of cells overexpressing L-ferritin chain and in nontransfected cells maintained in culture for 8 to 35 days. Overexpression of the L-chain has been associated with the formation of premature cataracts in humans with hereditary hyperferritinemia cataract syndrome. The formation of inclusion bodies in older lens epithelial cells, as demonstrated in the current investigation, is intriguing and could point to possible involvement of cytoplasmic L-chain-enriched ferritin aggregates in the formation of age-related cataract.}, number={10}, journal={INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE}, author={Goralska, M and Nagar, S and Fleisher, LN and McGahan, MC}, year={2005}, month={Oct}, pages={3521–3529} }
 @article{mcgahan_harned_mukunnemkeril_goralska_fleisher_ferrell_2005, title={Iron alters glutamate secretion by regulating cytosolic aconitase activity}, volume={288}, ISSN={["1522-1563"]}, DOI={10.1152/ajpcell.00444.2004}, abstractNote={Glutamate has many important physiological functions, including its role as a neurotransmitter in the retina and the central nervous system. We have made the novel observations that retinal pigment epithelial cells underlying and intimately interacting with the retina secrete glutamate and that this secretion is significantly affected by iron. In addition, iron increased secretion of glutamate in cultured lens and neuronal cells, indicating that this may be a common mechanism for the regulation of glutamate production in many cell types. The activity of the iron-dependent enzyme cytosolic aconitase (c-aconitase) is increased by iron. The conversion of citrate to isocitrate by c-aconitase is the first step in a three-step process leading to glutamate formation. In the present study, iron increased c-aconitase activity, and this increase was associated with an increase in glutamate secretion. Inhibition of c-aconitase by oxalomalate decreased glutamate secretion and completely inhibited the iron-induced increase in glutamate secretion. Derangements in both glutamate secretion and iron metabolism have been noted in neurological diseases and retinal degeneration. Our results are the first to provide a functional link between these two physiologically important substances by demonstrating a significant role for iron in the regulation of glutamate production and secretion in mammalian cells resulting from iron regulation of aconitase activity. Glutamatergic systems are found in many nonneuronal tissues. We provide the first evidence that, in addition to secreting glutamate, retinal pigment epithelial cells express the vesicular glutamate transporter VGLUT1 and that regulated vesicular release of glutamate from these cells can be inhibited by riluzole.}, number={5}, journal={AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY}, author={McGahan, MC and Harned, J and Mukunnemkeril, M and Goralska, M and Fleisher, L and Ferrell, JB}, year={2005}, month={May}, pages={C1117–C1124} }
 @article{goralska_dackor_holley_mcgahan_2003, title={Alpha lipoic acid changes iron uptake and storage in lens epithelial cells}, volume={76}, ISSN={["0014-4835"]}, DOI={10.1016/S0014-4835(02)00307-X}, abstractNote={Alpha lipoic acid (LA) is a cofactor in mitochondrial dehydrogenase complexes. Previous studies have shown that when administered exogenously LA has antioxidant properties, which include free radical scavenging, metal chelation and regeneration of other antioxidants. The cells convert LA into dihydroplipoic acid (DHLA), which in the presence of iron can act as a prooxidant. In vitro DHLA reduces Fe+3 to Fe+2 and removes iron from ferritin, increasing the risk of Fe catalyzed free radical formation. In the present study we examined the in vivo effects of lipoic acid treatment on Fe metabolism in cultured lens epithelial cells, and found that LA decreases Fe uptake from transferrin, increases Fe deposition into ferritin and increases the concentration of this protein. When administered together with ascorbic acid, lipoic acid changes the characteristic heavy to light chain ratio of ferritin makeup. The decreased Fe uptake and increased storage diminishes the size of the cytosolic highly reactive Fe pool (LIP). These changes are associated with increased cell resistance to H2O2 challenge. Therefore, LA may reduce the risk of Fe induced oxidative damage and also might be useful as a treatment of Fe overload.}, number={2}, journal={EXPERIMENTAL EYE RESEARCH}, author={Goralska, M and Dackor, R and Holley, B and McGahan, MC}, year={2003}, month={Feb}, pages={241–248} }
 @article{goralska_holley_mcgahan_2003, title={Identification of a mechanism by which lens epithelial cells limit accumulation of overexpressed ferritin H-chain}, volume={278}, ISSN={["0021-9258"]}, DOI={10.1074/jbc.M305827200}, abstractNote={The primary cultures of canine lens epithelial cells were transiently transfected with cDNAs for dog ferritin H- or L-chains in order to study differential expression of these chains. By using chain-specific antibodies, we determined that at 48 h after transfection overexpression of L-chain was much higher (9-fold over control) than that of H-chain (1.7-fold). We discovered that differentially transfected cells secrete overexpressed chains as homopolymeric ferritin into the media. Forty-eight hours after transfection accumulation of H-ferritin in the media was much higher (3-fold) than that of L-ferritin. This resulted in lowering of the concentration of H-chain in the cytosol. Co-transfection of cells with both H- and L-chain cDNAs increased the intracellular levels of H-chain and eliminated secretion of H-ferritin to the media. We concluded that lens epithelial cells differentially regulate concentration of both ferritin chains in the cytosol. The overexpressed L-chain accumulated in the cytosol as predominantly homopolymeric L-ferritin. This is in contrast to H-chain, which is removed to the media unless there is an L-chain available to form heteropolymeric ferritin. These data indicate that the inability of cells to more strictly control cytosolic levels of L-chain may augment its accumulation in lenses of humans with hereditary hyperferritinemia cataract syndrome, which is caused by overexpression of L-chain due to mutation in the regulatory element in the untranslated region of the mRNA of the chain.}, number={44}, journal={JOURNAL OF BIOLOGICAL CHEMISTRY}, author={Goralska, M and Holley, BL and McGahan, MC}, year={2003}, month={Oct}, pages={42920–42926} }
 @article{harned_grimes_mcgahan_2003, title={The effect of UVB irradiation on ferritin subunit synthesis, ferritin assembly and Fe metabolism in cultured canine lens epithelial cells}, volume={77}, ISSN={["0031-8655"]}, DOI={10.1562/0031-8655(2003)077<0440:TEOUIO>2.0.CO;2}, abstractNote={Abstract Ferritin is a multimeric protein consisting of heavy and light chains assembled in different tissue-specific ratios, which can protect cells from oxidative stress by storing reactive iron (Fe). Because the lens is constantly exposed to UV irradiation, we studied its effects on ferritin synthesis and Fe metabolism in cultured lens epithelial cells with and without ascorbic acid (Asc). UVB caused a large increase in accumulation of newly synthesized ferritin chains; this increase was additive to that induced by Asc. In contrast to the Asc-induced increase in Fe storage, Fe storage in ferritin was unaltered by UVB. Although UVB increased accumulation of newly synthesized ferritin chains, total ferritin levels were unaltered. In contrast, Asc, which induced a quantitatively similar increase in accumulation of newly synthesized ferritin chains, doubled the total amount of ferritin. Because UVB did not change Fe storage in ferritin or the size of the labile Fe pool, it was hypothesized and then determined that these newly synthesized chains did not assemble into functional holoferritin. Numerous studies detail the effects of various treatments on de novo ferritin synthesis; however, this study provides a cautionary note regarding the conclusions of such studies in the absence of data indicating assembly of functional ferritin molecules.}, number={4}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, author={Harned, J and Grimes, AM and McGahan, MC}, year={2003}, month={Apr}, pages={440–445} }
 @article{goralska_holley_mcgahan_2003, title={The effect of UVB irradiation on ferritin subunit synthesis, ferritin assembly and Fe metabolism in cultured canine lens epithelial cells}, volume={278}, journal={The Journal of Biological Chemistry}, author={Goralska, M. and Holley, B.L. and McGahan, M.C.}, year={2003}, pages={42920–42926} }
 @article{goralska_holley_mcgahan_2001, title={Overexpression of H- and L-ferritin subunits in lens epithelial cells: Fe metabolism and cellular response to UVB irradiation}, volume={42}, number={8}, journal={Investigative Ophthalmology and Visual Science}, author={Goralska, M. and Holley, B. L. and McGahan, M. C.}, year={2001}, pages={1721–1727} }
 @article{davidson_morgan_mcgahan_2000, title={Effect of surgical technique on in vitro posterior capsule opacification}, volume={26}, ISSN={["0886-3350"]}, DOI={10.1016/S0886-3350(99)00451-4}, abstractNote={To compare the effect of different cataract extraction surgical techniques on residual lens epithelial cell (LEC) density and cell regrowth rates using an in vitro model of posterior capsule opacification (PCO).Comparative Ophthalmology Research Laboratories, North Carolina State University, Raleigh, North Carolina, USA.Lens capsule explants were prepared from freshly enucleated canine globes after extracapsular cataract extraction (ECCE), phacoemulsification, or phacoemulsification followed by capsule vacuuming. Initial cell density on the capsule and cell proliferation were determined by phase contrast microscopy. The effects of the surgical technique on time to confluent growth of the cells across the posterior lens capsule were determined.Residual cell density on the remaining anterior capsule immediately after lens removal was 31.6% +/- 19.3%, 16.1% +/- 8.9%, and 7.7% +/- 5.7% in the ECCE, phacoemulsification, and phacoemulsification/capsule-vacuuming groups, respectively. Time to confluence (range 5.0 to 6.3 days) was not significantly different among the 3 groups when the lens capsules were cultured in serum-supplemented media. The confluence rate was significantly longer (by approximately 5 to 7 days) in the phacoemulsification/capsule-vacuuming group than in the other 2 groups when the capsules were cultured in serum-free media.Phacoemulsification with and without anterior and equatorial capsular vacuuming led to less initial LEC density in the capsular bag than ECCE. However, because cell proliferation rates among the 3 groups were only marginally affected, near 100% removal of LEC at the time of cataract extraction may be necessary to prevent PCO.}, number={10}, journal={JOURNAL OF CATARACT AND REFRACTIVE SURGERY}, author={Davidson, MG and Morgan, DK and McGahan, MC}, year={2000}, month={Oct}, pages={1550–1554} }
 @article{davidson_wormstone_morgan_malakof_allen_mcgahan_2000, title={Ex vivo canine lens capsular sac explants}, volume={238}, ISSN={["0721-832X"]}, DOI={10.1007/s004170000158}, abstractNote={[[{:Label=>"BACKGROUND", :NlmCategory=>"BACKGROUND"}, "Lens capsular sac explants from human cadaver eyes were used to investigate posterior capsular opacification (PCO). The purpose of this study was to characterize a similar model using canine tissue and to determine whether transferrin (Tf), transforming growth factor beta-2 (TGF-beta2), and insulin-like growth factor-1 (IGF-1) are secreted by lens epithelial cells (LEC) of these ex vivo sacs."], [{:Label=>"METHODS", :NlmCategory=>"METHODS"}, "The lens from canine eyes was removed by extracapsular cataract extraction, the lens sac dissected free, pinned to a petri dish, and cultured in either serum-supplemented or serum-free medium. Morphologic characteristics and growth rate to confluence on the posterior capsule were studied by phase-contrast microscopy. Vimentin, alpha smooth muscle actin, and panTGF-beta expression by LEC were determined by immunohistochemistry. Tf, TGF-beta2, and IGF-1 levels were measured by ELISA in the supernatant of sacs cultured in serum-free medium."], [{:Label=>"RESULTS", :NlmCategory=>"RESULTS"}, "The mean time to confluence of LEC onto the posterior capsule was 5.4+/-1.1 days (n=22) and 14.7+/-3.7 days (n=14) for sacs in serum-supplemented and serum-free medium, respectively. Following development of confluence, explants displayed opacification and light scatter from cellular proliferation and capsular contraction. Confluent LEC expressed vimentin, alpha smooth muscle actin, and TGF-beta2, and both Tf and TGF-beta2 were secreted into the culture supernatant."], [{:Label=>"CONCLUSION", :NlmCategory=>"CONCLUSIONS"}, "Canine lens sac explants have characteristics virtually identical to those of human origin, and appear to be a useful alternative tissue source for this model when human cadaver eyes are unavailable. Tf and TGFbeta-2, but not IGF-1, are secreted by LEC in explanted lens sacs and may influence the proliferation and metaplasia of LEC during the development of PCO."]]}, number={8}, journal={GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY}, author={Davidson, MG and Wormstone, M and Morgan, D and Malakof, R and Allen, J and McGahan, MC}, year={2000}, month={Aug}, pages={708–714} }
 @article{colitz_malarkey_dykstra_mcgahan_davidson_2000, title={Histologic and immunohistochemical characterization of lens capsular plaques in dogs with cataracts}, volume={61}, ISSN={["0002-9645"]}, DOI={10.2460/ajvr.2000.61.139}, abstractNote={Abstract}, number={2}, journal={AMERICAN JOURNAL OF VETERINARY RESEARCH}, author={Colitz, CMH and Malarkey, D and Dykstra, MJ and McGahan, MC and Davidson, MG}, year={2000}, month={Feb}, pages={139–143} }
 @article{fleisher_mcgahan_ferrell_2000, title={Rabbit pigmented ciliary epithelium produces interleukin-6 in response to inflammatory cytokines}, volume={70}, ISSN={["0014-4835"]}, DOI={10.1006/exer.1999.0787}, abstractNote={Interleukin-6 is a multifunctional cytokine that is found in high concentrations in intraocular fluids during the uveitic response. Although monocytic cells are a major source of interleukin-6, resident intraocular cells may also contribute to its accumulation in intraocular fluids during uveitis. The purpose of this study was to determine whether interleukin-6 is produced by pigmented ciliary epithelial cells and whether agents known to stimulate interleukin-6 production, such as interleukin-1beta, tumor necrosis factor-alpha, bacterial endotoxin, and stimulators of the adenylyl cyclase/adenosine 3',5'-cyclic monophosphate system, increase interleukin-6 production by these cells. Primary and first-passage cultures of nontransformed rabbit pigmented ciliary epithelial cells were incubated with the test agents for varying periods of time in serum-free medium and interleukin-6 levels in the cell-conditioned medium were measured by bioassay.Little, if any interleukin-6 was released from pigmented ciliary epithelial cells incubated for up to 18 hr in serum-free medium. Interleukin-1betastimulated interleukin-6 release in a time- and concentration-dependent manner. Tumor necrosis factor-alpha, although ineffective alone, increased interleukin-1beta-induced interleukin-6 release in a concentration-dependent manner when co-incubated with interleukin-1betafor 18 hr. However, tumor necrosis factor-alphadid not enhance interleukin-1beta-induced interleukin-6 release if co-incubated with interleukin-1betafor a shorter time (6 hr). A 6 hr exposure to bacterial endotoxin did not stimulate interleukin-6 release from pigmented ciliary epithelial cells. Co-incubation of pigmented ciliary epithelial cells with interleukin-1betaand agents that stimulate the adenyl cyclase/adenosine 3',5'-cyclic monophosphate system through cell surface G-protein transduced receptors, i.e. isoproterenol, vasoactive intestinal peptide or prostaglandin E(2), significantly enhanced the ability of interleukin-1betato stimulate interleukin-6 release. However, neither the adenyl cyclase activator, forskolin or the adenosine 3', 5'-cyclic monophosphate-mimetic, dibutyryl 3',5'-cyclic monophosphate enhanced interleukin-1beta-induced release of interleukin-6. These results indicate that the pigmented ciliary epithelium is one potential source of interleukin-6 and may contribute to the elevation in intraocular fluid interleukin-6 levels observed during various intraocular inflammatory episodes. Although agents that activate the adenyl cyclase/adenosine 3', 5'-cyclic monophosphate system through cell surface G-protein transduced receptors increased interleukin-1beta-induced release of interleukin-6, the ineffectiveness of forskolin and dibutryl 3', 5'-cyclic monophosphate suggest that simply increasing intracellular 3',5'-cyclic monophosphate is not sufficient to augment interleukin-1beta-induced release of interleukin-6. The significance of interleukin-6 in the intraocular inflammatory response is discussed in terms of its proposed role in an endogenous antiinflammatory system acting through induction of interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, acute-phase proteins and corticosteroids.}, number={3}, journal={EXPERIMENTAL EYE RESEARCH}, author={Fleisher, LN and McGahan, MC and Ferrell, JB}, year={2000}, month={Mar}, pages={271–279} }
 @article{goralska_holley_mcgahan_2000, title={The effects of Tempol on ferritin synthesis and Fe metabolism in lens epithelial cells}, volume={1497}, ISSN={["0167-4889"]}, DOI={10.1016/S0167-4889(00)00038-0}, abstractNote={The nitroxide, Tempol, can protect tissue from oxidative damage by removing superoxide and by oxidizing Fe(II) to Fe(III), thus decreasing formation of the hydroxyl radical. However, long-term exposure to Tempol can damage cells. The oxidation of Fe could have profound effects on Fe metabolism in cells, yet this has not been previously studied. In the present investigation, the effects of Tempol on the synthesis of the Fe storage protein, ferritin, and its ability to store Fe were studied in cultured lens epithelial cells (LEC). In addition, the effects of short- and long-term Tempol treatment on the resistance of LEC to oxidative stress were determined. Tempol had a clear dose-dependent inhibitory effect on ferritin synthesis noted at 6 h. By 20 h, ferritin synthesis returned toward normal levels. However, Fe incorporation into ferritin was decreased by almost 90% by the highest dose of Tempol, even at the 20-h time point. The decrease in Fe incorporation into ferritin was accompanied by a significant increase in the LMW pool of Fe. After short-term (4 h) treatment with Tempol, LEC were protected against the toxic effects of tertiary butyl hydroperoxide. However, after longer term treatment (20 h), Tempol itself had a toxic effect and did not afford protection. Indeed, at the higher doses, Tempol significantly reduced the ability of the cells to withstand oxidative stress. The redistribution of Fe within the cell after 20 h of Tempol treatment appears to render the cells more vulnerable to oxidative stress. The deleterious effects of Tempol on LEC are likely due to its effects on Fe metabolism, perhaps by reducing the availability of Fe for incorporation into ferritin and Fe-dependent enzymes as well as enlarging a low molecular weight pool of Fe which may be capable of catalyzing damaging free radical reactions.}, number={1}, journal={BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH}, author={Goralska, M and Holley, B and McGahan, MC}, year={2000}, month={Jun}, pages={51–60} }
 @article{colitz_davidson_mcgahan_1999, title={Telomerase activity in lens epithelial cells of normal and cataractous lenses}, volume={69}, ISSN={["0014-4835"]}, DOI={10.1006/exer.1999.0739}, abstractNote={Telomerase is a ribonucleoprotein responsible for maintaining telomere length, preventing chromosomal degradation and recombination, and repairing DNA strand breaks. These activities are believed to be important in preventing cell senescence. Telomerase activity is normally found in germinal, neoplastic and stem cells, but not any ocular tissue studied to date. The epithelium of the crystalline lens is comprised of a population of cells with diverse mitotic potential including the germinative epithelium which contains cells with the potential for unlimited replicative capacity, equatorial cells which terminally differentiate into lens fibers, and the central epithelium which are considered to be quiescent and nonreplicative under normal circumstances. We speculated that the germinative region of lens epithelial cells might have telomerase activity, and that dysregulation of its activity might be associated with cataractogenesis. We investigated these hypotheses in lens capsule specimens from normal and cataractous dogs and from cultures of canine lens epithelial cells using standard assays for telomerase activity and telomere length. Telomerase activity was found in normal canine lens epithelial cells in the central, germinative and equatorial regions of the anterior lens capsule at equivalent levels. Similar findings were made in feline and murine lens epithelial cells, indicating that the presence of telomerase activity in the lens was not species specific. Lens fiber cells, corneal epithelium and endothelium and nonpigmented ciliary epithelium were telomerase negative. Telomerase activity and telomere lengths were significantly greater in lens epithelia from cataractous lenses when compared with normal lenses. Since telomerase activity is associated with an immortal phenotype, the presence of telomerase activity in the lens epithelial cells may function to prevent conversion to senescence. It was, therefore, difficult to explain why these cells cannot be passaged more than four times in culture. We found that telomerase activity and telomere lengths gradually decreased with increased passages until telomerase activity was no longer present at passage two. Consistent with these findings, there were no senescent cells present on the lens capsule when the lens was initially dissected for culture, but an increasing number of cells were senescent with each passage, correlating well with the loss of telomerase activity. Telomerase activity is likely important in the germinative epithelium to maintain its proliferative potential and prevent cell senescence. Telomerase may function in the quiescent, central lens to maintain telomeres damaged by oxidative stress and ultraviolet light exposure, thereby preventing accelerated loss of these elements which triggers cell senescence. It remains to be determined if the increase in telomerase activity in lens epithelial cells from cataractous lenses is a primary dysregulation that may have a role in the development of the cataract, or is secondary to cataract formation.}, number={6}, journal={EXPERIMENTAL EYE RESEARCH}, author={Colitz, CMH and Davidson, MG and McGahan, MC}, year={1999}, month={Dec}, pages={641–649} }
 @article{steingold_sharp_mcgahan_hughes_dunn_page_1998, title={Characterization of canine MDR1 mRNA: Its abundance in drug resistant cell lines and in vivo}, volume={18}, number={1A}, journal={Anticancer Research}, author={Steingold, S. F. and Sharp, N. J. and McGahan, M. C. and Hughes, C. S. and Dunn, S. E. and Page, R. L.}, year={1998}, pages={393–400} }
 @article{goralska_harned_fleisher_mcgahan_1998, title={The effect of ascorbic acid and ferric ammonium citrate on iron uptake and storage in lens epithelial cells}, volume={66}, ISSN={["0014-4835"]}, DOI={10.1006/exer.1997.0466}, abstractNote={Ferritin is the major intracellular iron storage protein which has been shown to protect cells against oxidative damage. Recent reports that an inherited abnormality in human ferritin synthesis is associated with early bilateral cataracts underscore the importance of understanding ferritin synthesis and iron storage in lens epithelial cells. We previously demonstrated that ascorbic acid greatly increases de novo synthesis of ferritin in lens epithelial cells. The objectives of the present study were to determine: (1) the effects of ascorbic acid and ferric ammonium citrate on iron uptake by canine lens epithelial cells from iron bound to transferrin and from ferric chloride and (2) the incorporation of this element into ferritin. Iron uptake by lens epithelial cells from 59ferric chloride was 20 times higher than from 59iron-transferrin and iron deposition into ferritin was 8-fold higher when 59ferric chloride was the source. Ascorbic acid had a stimulatory effect on iron uptake from transferrin and on incorporation of this element into ferritin. The ascorbic acid-induced increase of iron uptake required de novo protein synthesis but not specifically de novo ferritin biosynthesis. Although ferritin is not directly involved in iron uptake, the level of ferritin protein could control the pool of intracellular iron. The present results indicate that iron homeostasis in lens epithelial cells is affected mainly by changes in apoferritin synthesis, which is greatly stimulated by ascorbic acid, rather than by altering the rate of protein degradation, which is very slow in these cells under all circumstances. Ferric ammonium citrate activates iron uptake from transferrin in a wide range of cell lines by generation of free radicals. Ferric ammonium citrate also increased iron uptake from Tf in lens epithelial cells. Ferric ammonium citrate treated cells incorporated 5 times more iron and deposited 2 times more iron into ferritin than control cells. Increased incorporation of iron into ferritin was due to ferric ammonium citrate-induced stimulation of de novo ferritin synthesis rather than an increased rate of iron deposition into pre-existing ferritin. Ferric ammonium citrate had a different effect on iron uptake from ferric chloride; total iron uptake was not significantly increased while deposition into ferritin was significantly decreased. These results demonstrate that iron homeostasis in lens epithelial cells is regulated by ascorbic acid and by changes in the rate of de novo ferritin synthesis. In addition, the differences in iron uptake from transferrin and ferric chloride and its subsequent incorporation into ferritin suggests that the mechanisms by which iron is incorporated into ferritin are source dependent.}, number={6}, journal={EXPERIMENTAL EYE RESEARCH}, author={Goralska, M and Harned, J and Fleisher, LN and McGahan, MC}, year={1998}, month={Jun}, pages={687–697} }
 @article{allen_davidson_nasisse_fleisher_mcgahan_1998, title={The lens influences aqueous humor levels of transforming growth factor-beta 2}, volume={236}, ISSN={["0721-832X"]}, DOI={10.1007/s004170050083}, abstractNote={[[{:Label=>"BACKGROUND", :NlmCategory=>"BACKGROUND"}, "Transforming growth factor-beta 2 (TGF-beta 2) is a pluripotent cytokine which has been suggested to play a number of roles in ocular physiologic and pathologic states. Intraocular fluid (i.o.f.) levels of TGF-beta 2 are quite high. Although the sources of ocular TGF-beta are not completely defined, the retinal pigment epithelium, the epithelium of the ciliary body and trabecular meshwork cells all secrete it. In this study we utilized canine lens and rabbit ciliary pigmented epithelial cell cultures to quantitate the in vitro secretion of TGF-beta 2. In addition, the effects of aphakia or the presence of cataractous lenses on IOF TGF-beta 2 levels were determined."], [{:Label=>"METHODS", :NlmCategory=>"METHODS"}, "Lens and ciliary body epithelial cell culture supernatants and aqueous humors were assayed for total TGF-beta 2 levels by ELISA and bioassay."], [{:Label=>"RESULTS", :NlmCategory=>"RESULTS"}, "TGF-beta 2 accumulated in the media bathing lens epithelial cell cultures (0.7 +/- 0.03 ng/ml at day 2) and ciliary pigmented epithelial cell cultures (0.8 +/- 0.06 ng/ml at day 2) in a time-dependent manner. Surprisingly, aqueous humor from aphakic rabbit eyes contained significantly higher levels of TGF-beta 2 than their contralateral phakic controls. Furthermore, aqueous humor from canine eyes with cataracts also contained significantly higher levels of TGF-beta 2 than normal eyes."], [{:Label=>"CONCLUSIONS", :NlmCategory=>"CONCLUSIONS"}, "These results suggest that the lens secretes TGF-beta 2 and that the presence and status of the lens may influence IOF TGF-beta 2 levels."]]}, number={4}, journal={GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY}, author={Allen, JB and Davidson, MG and Nasisse, MP and Fleisher, LN and McGahan, MC}, year={1998}, month={Apr}, pages={305–311} }
 @article{davidson_harned_grimes_duncan_wormstone_mcgahan_1998, title={Transferrin in after-cataract and as a survival factor for lens epithelium}, volume={66}, ISSN={["1096-0007"]}, DOI={10.1006/exer.1997.0413}, abstractNote={The Fe-transport protein, transferrin (Tf), is synthesized and secreted by whole lenses and cultured lens epithelial cells. Because of Tf's central role in cell growth and proliferation, its participation in lens cell proliferation following cataract extraction was explored using a rabbit model of after-cataract. Varying amounts of the central anterior lens capsule were removed (0, 35, or 80%) following extraction of the lens. The Tf content of and secretion by after-cataract lens capsular sacs containing regenerated lens tissue was determined ex vivo at 0, 3, 5, 7 and 9 weeks post-surgery. In all cases Tf content of and secretion by the lens sacs was higher than that of their contralateral controls (whole lenses). Tf secretion was up to 5-fold higher and metabolic labeling studies indicated secretion of newly synthesized Tf. The sacs contained up to 10 times the concentration of Tf as the control lenses. Human lens after-cataract capsular bags also secreted Tf. The function of Tf as a survival factor was tested on cultured lens epithelial cells. Cells cultured in serum-free medium had a survival rate of only 20-34% if the medium was changed each day. If the medium was never changed during this period, the survival rate was 43-52%, suggesting secretion of essential growth factors by these cells. Addition of 200 microg ml-1 Tf to the medium during each daily change increased survival to levels attained when the medium was not changed. Addition of Tf antibodies to the culture medium during each daily change decreased cell survival to 14%. Apparently Tf acts as a survival factor for lens epithelia and its synthesis is up-regulated in after-cataract lens sacs. These factors suggest that Tf may play an important role in the pathogenesis of lens epithelial cell proliferation and after-cataract formation following cataract surgery.}, number={2}, journal={EXPERIMENTAL EYE RESEARCH}, author={Davidson, MG and Harned, J and Grimes, AM and Duncan, G and Wormstone, IM and McGahan, MC}, year={1998}, month={Feb}, pages={207–215} }
 @article{goralska_harned_grimes_fleisher_mcgahan_1997, title={Mechanisms by which ascorbic acid increases ferritin levels in cultured lens epithelial cells}, volume={64}, ISSN={["1096-0007"]}, DOI={10.1006/exer.1996.0227}, abstractNote={A previous study demonstrated that ascorbic acid increased the concentration of the iron storage protein, ferritin. In cultured lens epithelial cells. The current study was designed to determine the mechanism by which ascorbic acid exerts this effect. Ascorbic acid increased both ferritin mRNA levels (by about 30%) and translation of ferritin (de novo synthesis was increased up to 15-fold) within 6 hr. Cycloheximide completely abolished the ability of ascorbic acid to increase ferritin levels, whereas actinomycin D only decreased it by about 30%. Therefore, the ascorbic-acid induced increase in ferritin concentration is due mainly to an increase in ferritin synthesis at the translational levels. This is a novel role for ascorbic acid. Addition of iron with ascorbic acid further increased de novo synthesis of ferritin, but this additive effect was only noted at a later time point (20 hr). Factors which decrease ferritin mRNA translation, such as the reducing agent dithiothreitol or the iron chelator desferrioxamine, reduced the ascorbic acid effect on de novo ferritin synthesis. The effects of ascorbic acid on ferritin mRNA levels may be mediated by its oxidation product, H2O2, since, like ascorbic acid, H2O2 increased ferritin mRNA levels by 30%. However, in contrast to the ascorbic acid-induced increase in translation of ferritin, H2O2 substantially decreased de novo ferritin synthesis. This effect of H2O2 could have physiological significance in eyes where concentrations of H2O2 in the aqueous humor are elevated. High levels of H2O2 could decrease the concentration of ferritin within the lens. Since ferritin sequesters iron and has been shown to decrease oxidative damage by limiting the availability of iron to catalyse free radical reactions, H2O2-induced reduction in ferritin concentration in the lens could have deleterious effects. The ability of ascorbic acid to increase ferritin concentration in lens epithelial cells could provide an additional protective mechanism for this antioxidant vitamin. The importance of ferritin to normal lens functioning is underscored by the recent finding that humans with a dominantly inherited abnormality in ferritin synthesis exhibit early bilateral cataracts.}, number={3}, journal={EXPERIMENTAL EYE RESEARCH}, author={Goralska, M and Harned, J and Grimes, AM and Fleisher, LN and McGahan, MC}, year={1997}, month={Mar}, pages={413–421} }
 @inbook{allen_mcgahan_fleisher_jaffe_privalle_1997, title={Nitric oxide in ocular inflammation}, DOI={10.1007/978-1-4615-5937-5_16}, booktitle={Advances in ocular toxicology}, publisher={New York: Plenum Press}, author={Allen, J. B. and McGahan, M. C. and Fleisher, L. N. and Jaffe, G. J. and Privalle, C. T.}, year={1997}, pages={121–131} }
 @article{mcgahan_grimes_fleisher_1996, title={Hemoglobin exacerbates the ocular inflammatory response to endotoxin}, volume={234}, ISSN={["0721-832X"]}, DOI={10.1007/BF00185299}, number={10}, journal={GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY}, author={McGahan, MC and Grimes, AM and Fleisher, LN}, year={1996}, month={Oct}, pages={643–647} }
 @article{fleisher_mcgahan_ferrell_pagan_1996, title={Interleukin-1 beta increases prostaglandin E(2)-stimulated adenosine 3',5'-cyclic monophosphate production in rabbit pigmented ciliary epithelium}, volume={63}, ISSN={["0014-4835"]}, DOI={10.1006/exer.1996.0095}, abstractNote={This study was designed to determine the effects of interleukin-1 on basal and prostaglandin E2-stimulated adenosine 3',5'-cyclic monophosphate production by primary and first passage cultures of non-transformed rabbit pigmented and non-pigmented ciliary epithelial cells. Confluent cultures of rabbit pigmented and non-pigmented ciliary epithelial cells were incubated for varying periods of time in serum-free medium with or without interleukin-1 beta, tumor necrosis factor-alpha, bacterial lipopolysaccharide, transforming growth factor-beta 2, cycloheximide, indomethacin and combinations of these agents. Cells were then preincubated for 10 min with serum-free medium plus the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (for basal adenosine 3',5'-cyclic monophosphate production) or serum-free medium containing several concentrations of prostaglandin E2 and 3-isobutyl-1-methylxanthine. In certain experiments isoproterenol, vasoactive intestinal peptide, or forskolin was substituted for prostaglandin E2. Adenosine 3',5'-cyclic monophosphate was then extracted into ice-cold absolute ethanol and measured by radioimmunoassay. Prostaglandin E2 stimulated adenosine 3',5'-cyclic monophosphate production in pigmented and non-pigmented ciliary epithelial cells in a dose-dependent manner. Incubation with interleukin-1 beta (150 U ml-1) increased prostaglandin E2-stimulated, but not basal adenosine 3',5'-cyclic monophosphate production in pigmented ciliary epithelial cells. This interleukin-1 beta-induced enhancement of prostaglandin E2-stimulated adenosine 3',5'-cyclic monophosphate production, called the interleukin-1 effect, was not seen with non-pigmented ciliary epithelial cells. The interleukin-1 effect was dependent upon interleukin-1 beta concentration, time and de novo protein synthesis. The interleukin 1 effect could not be reproduced by replacing interleukin-1 beta with tumor necrosis factor-alpha or bacterial lipopolysaccharide and was specific for prostaglandin E2, since interleukin-1 beta did not enhance isoproterenol-, vasoactive intestinal peptide-, or forskolin-induced adenosine 3',5'-cyclic monophosphate production. Chronic exposure to prostaglandin E2 (during the 3 hr incubation period), with or without interleukin-1 beta in the incubation medium, reduced subsequent prostaglandin E2-stimulated adenosine 3',5'-cyclic monophosphate production. Inhibition of de novo prostaglandin synthesis with indomethacin increased the interleukin-1 effect. The interleukin-1 effect was inhibited by the immunosuppressive cytokine, transforming growth factor-beta 2, in a dose-dependent manner. This is the first report of prostaglandin E2-induced stimulation of adenosine 3',5'-cyclic monophosphate production by pigmented ciliary epithelial cells and of the unique ability of interleukin-1 to increase this effect. The results are consistent with interleukin-1-induced upregulation of prostaglandin E receptors. Since transforming growth factor-beta 2 inhibited this interleukin-1 effect, this immunosuppressive cytokine may exert negative feedback and thus regulate the physiological consequences of the interleukin-1 effect.}, number={1}, journal={EXPERIMENTAL EYE RESEARCH}, author={Fleisher, LN and McGahan, MC and Ferrell, JB and Pagan, I}, year={1996}, month={Jul}, pages={91–104} }
 @article{allen_mcgahan_ogawa_sellon_clark_fleisher_1996, title={Intravitreal transforming growth factor-beta 2 decreases cellular infiltration in endotoxin-induced ocular inflammation in rabbits}, volume={15}, ISSN={["0271-3683"]}, DOI={10.3109/02713689609017616}, abstractNote={Transforming growth factor-beta (TGF-beta), a multifunctional cytokine which has been identified in normal and inflamed ocular fluids, may play a role in the evolution of inflammatory ocular lesions. In this study we utilized a rabbit model of LPS-induced uveitis to determine if exogenous TGF-beta 2 could alter its course. Recombinant TGF-beta 2 (1-2000 ng), LPS (10 or 20 ng), or TGF-beta 2 (100 ng) plus LPS (10 ng) were injected intravitreally in one eye of a New Zealand white rabbit and the contralateral eye served as a paired control which received an equal volume of vehicle. The uveitic response was assessed by biomicroscopic examination of the anterior uvea and analysis of protein and cells in the aqueous humor. Ocular tissues were processed for histologic, immunohistochemical and in situ hybridization analyses. Rabbits injected with doses of TGF-beta 2 > or = 500 ng developed a mild uveitic response, compared to LPS alone, accompanied by expression of IL-1 beta mRNA and protein in the anterior uvea. Interestingly, rabbits coinjected with LPS (10 ng) and a nonuveitic dose (100 ng) of TGF-beta 2 exhibited a similar increase in ocular vascular permeability, but a decrease in inflammatory cell infiltration into the anterior uvea and aqueous humor (1185 +/- 117 versus 2465 +/- 176; p < 0.05). No evidence of inflammation was observed in eyes injected with 100 ng TGF-beta 2 alone. Similar to other models of inflammation, TGF-beta may interrupt the cascade of events leading to ocular inflammation, thereby suggesting therapeutic potential.}, number={1}, journal={CURRENT EYE RESEARCH}, author={Allen, JB and McGahan, MC and Ogawa, Y and Sellon, DC and Clark, BD and Fleisher, LN}, year={1996}, month={Jan}, pages={95–103} }
 @article{allen_mcgahan_ferrell_adler_fleisher_1996, title={Nitric oxide synthase inhibitors exert differential time-dependent effects on LPS-induced uveitis}, volume={62}, ISSN={["0014-4835"]}, DOI={10.1006/exer.1996.0003}, abstractNote={Nitric oxide (NO) is a highly reactive radical which plays an integral role in physiological and pathophysiological processes. NO is produced endogenously in small amounts by a constitutive NO synthase (cNOS) as a regulator of vascular tone and neurotransmission. NO can also be produced in large amounts by an inducible NOS (iNOS) in response to endotoxin and cytokines, and has been reported to be a mediator of lipopolysaccharide (LPS)-induced uveitis in rats. The purpose of the present study was to investigate the effects of NOS inhibitors with different NOS isoform specificities in the rabbit model of endotoxin-induced ocular inflammation. LPS and/or inhibitors of NOS. NG-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AG), were injected intravitreally and the eyes observed by slit lamp for 24 hr. Coinjection of LPS with L-NAME inhibited anterior inflammation in rabbits. Iridal hyperemia (IH) and aqueous flare (AF) were completely abolished in eight out of nine rabbits in a dose-dependent manner. In addition, total cell counts were significantly suppressed (7393 +/- 697 vs. 325 +/- 188, P < 0.05) and aqueous protein levels were reduced to near control levels (25 +/- 0.75 vs. 1.72 +/- 0.36, P < 0.05). Similar suppression was seen with AG (cell counts = 351 +/- 246 and proteins = 3.1 +/- 1.2). Administration of L-NAME 0.5 hr after LPS injection suppressed inflammation to a lesser extent than coinjection. In contrast, administration of L-NAME 6 hr after LPS injection was not inhibitory, and in fact significantly increased cellular infiltration. However, AG given 6 hr after LPS had a remarkably different effect, since it significantly decreased both protein extravasation and cellular infiltration into the aqueous humor. In fact, our results suggest that cNOS may play a greater role in the earlier stages of this developing inflammatory response. These results extend others' observations that NO is a key mediator in uveitis, that induction of iNOS plays a critical role in experimental uveitis, and suggest that NO has a complex role in the ocular inflammatory process. Inhibitors of NOS can abort the LPS-induced inflammatory response if administered early enough, but could potentially exacerbate an established inflammatory episode.}, number={1}, journal={EXPERIMENTAL EYE RESEARCH}, author={Allen, JB and McGahan, MC and Ferrell, JB and Adler, KB and Fleisher, LN}, year={1996}, month={Jan}, pages={21–28} }
 @article{fleisher_ferrell_mcgahan_1995, title={INFLAMMATION-INDUCED CHANGES IN ADENOSINE 3',5'-CYCLIC-MONOPHOSPHATE PRODUCTION BY CILIARY EPITHELIAL-CELL BILAYERS}, volume={60}, ISSN={["0014-4835"]}, DOI={10.1016/S0014-4835(95)80007-7}, abstractNote={Despite extensive evidence implicating the cytokines interleukin-1 (IL-1) and tumor necrosis factor-α (TNFα) in the intraocular inflammatory response, little is known about their effects on signal transduction in anterior uveal tissue. Since these cytokines have been shown to alter the adenylyl cyclase system in nonocular tissues, we tested the hypothesis that IL-1β and TNFα affect the anterior uvea by altering production of the intracellular second messenger adenosine 3′,5′-cyclic monophosphate (cAMP) in ciliary epithelial bilayers. This was accomplished by measuring the levels of cAMP in bilayers ex vivo, following intraocular inflammation induced by intravitreal injection of IL-1β, TNFα or bacterial endotoxin, and in vitro, following exposure to IL-1β, TNFα or bacterial endotoxin. Although cAMP production was enhanced in bilayers from IL-1β-, TNFα- or endotoxin-inflamed eyes, ex vivo, exposure of normal bilayers to IL-1β (15 U ml−1), TNFα (20 U ml−1), or a low concentration of endotoxin (0·01 μg ml−1) for 4 hr, in vitro, had no effect on cAMP production. The inability of IL-1β, TNFα, or the low concentration of endotoxin to increase cAMP production by bilayers, in vitro, suggests that the enhanced cAMP production observed with inflamed bilayers, ex vivo, was not due to a direct action of these inflammatory agonists on the ciliary epithelial bilayer. Although direct exposure to cytokines or endotoxin did not change cAMP production, treatment with IL-1β, TNFα, or a higher concentration of endotoxin (1 μg ml−1) did affect signal transduction mechanisms. For example, exposure to IL-1β, TNFα, or a higher concentration of endotoxin rendered normal bilayers unresponsive to isoproterenol. A similar absence of response to isoproterenol was also seen with bilayers from TNFα-inflamed eyes. This insensitivity to β-receptor stimulation is apparently a consequence of receptor downregulation or functional uncoupling of the receptor from the transducing G protein, since in each case of isoproterenol insensitivity, bilayers exhibited forskolin responses indistinguishable from the appropriate control tissues. Since cAMP production by the epithelial cell bilayer was increased in three different models of intraocular inflammation, augmented production of this second messenger is likely to occur during uveitis of diverse etiology. Enhanced cAMP production by inflamed epithelial bilayers may contribute to some general aspect of the uveitic response such as altered intraocular pressure or possibly serve to enhance efflux of fluid from swollen anterior uveal tissue.}, number={2}, journal={EXPERIMENTAL EYE RESEARCH}, author={FLEISHER, LN and FERRELL, JB and MCGAHAN, MC}, year={1995}, month={Feb}, pages={165–171} }
 @article{mcgahan_grimes_nasisse_fleisher_1995, title={IRON UPTAKE BY CULTURED LENS EPITHELIAL-CELLS}, volume={233}, ISSN={["0721-832X"]}, DOI={10.1007/BF00200484}, abstractNote={[[{:Label=>"BACKGROUND", :NlmCategory=>"BACKGROUND"}, "Transferrin and Fe concentrations increase in the intraocular fluids in pathological conditions and the lens accumulates Fe during ocular inflammation. Tissues take up Fe from transferrin by two mechanisms, receptor-medicated endocytosis of diferric transferrin and a process occurring at the cell membrane which may be mediated by an oxido-reductase. However, Fe metabolism, transport and storage have not been previously investigated in the lens. This study was designed to characterize the uptake of Fe from transferrin by lens epithelial cells in culture."], [{:Label=>"METHODS", :NlmCategory=>"METHODS"}, "Primary, secondary and tertiary cultures of canine lens epithelial cells and cultures obtained from cataractous lenses were studied. Uptake of 59Fe from transferrin by these cultured cells was measured. Transferrin receptor populations were determined in receptor-binding assays."], [{:Label=>"RESULTS", :NlmCategory=>"RESULTS"}, "There was a distinct relationship between the amount of Fe-transferrin added and the amount of Fe taken up, which was linear for the primary cultures but significantly reduced for the secondary, tertiary and cataract cultures (252 +/- 21, 169 +/- 14, 153 +/- 14 and 96 +/- 2 ng Fe/mg protein, respectively). Transferring receptor expression in lens cell cultures was reduced 10-fold within 2 days of addition of serum to cells grown in low-Fe, serum-free medium for 1 week."], [{:Label=>"CONCLUSIONS", :NlmCategory=>"CONCLUSIONS"}, "The reduction of Fe uptake by the subcultured and cataract cell lines probably reflects a decrease in transferrin receptor expression and in the activity of an alternative pathway for Fe transferrin uptake occurring over time. This reduced Fe uptake may result from long-term exposure to relatively high Fe concentration in the media. A reduction in the expression of the transferrin receptor after incubation with high concentrations of Fe supports this conclusion."]]}, number={6}, journal={GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY}, author={MCGAHAN, MC and GRIMES, AM and NASISSE, MP and FLEISHER, LN}, year={1995}, month={Jun}, pages={354–359} }
 @article{fleisher_ferrell_mcgahan_1995, title={MEDIATORS OF THE OCULAR INFLAMMATORY RESPONSE TO INTERLEUKIN-1-BETA PLUS TUMOR-NECROSIS-FACTOR-ALPHA}, volume={233}, ISSN={["0721-832X"]}, DOI={10.1007/BF00241479}, abstractNote={[[{:Label=>"BACKGROUND", :NlmCategory=>"BACKGROUND"}, "Intravitreal injection of marginally inflammatory doses of interleukin-1 beta and tumor necrosis factor-alpha (IL-1 beta/TNF alpha) has been shown to produce intraocular inflammation distinctly different from that induced by higher intravitreal doses of either IL-1 or TNF alpha. Since cyclooxygenase inhibitors and platelet-activating factor (PAF)-receptor antagonists can reduce IL-1- or TNF alpha-induced uveitis, the present investigation was undertaken to determine whether cyclooxygenase metabolites of arachidonic acid and PAF are important mediators of IL-1 beta/TNF alpha-induced uveitis."], [{:Label=>"METHODS", :NlmCategory=>"METHODS"}, "The cyclooxygenase inhibitor indomethacin and two structurally dissimilar PAF-receptor antagonists, SRI 63-441 and WEB 2086, were used to investigate the importance of cyclooxygenase metabolites and PAF in IL-1 beta/TNF alpha-induced uveitis."], [{:Label=>"RESULTS", :NlmCategory=>"RESULTS"}, "Based upon the effectiveness of indomethacin, the anterior uveitis induced by IL-1 beta/TNF alpha could be divided into two phases; a primary phase dependent upon generation of cyclooxygenase metabolites (the first 24 h) and a secondary phase largely independent of cyclooxygenase metabolite production (24-48 h). Posterior uveitis was also apparent at 48 h and was reduced by indomethacin. SRI 63-441 reduced the anterior uveitis at 24 h and to a lesser extent at 48 h; it also reduced the posterior uveitis at 48 h. However, although WEB 2086 was as effective as SRI 63-441 in reducing PAF-induced platelet aggregation, ex vivo, it did not significantly reduce IL-1 beta/TNF alpha-induced uveitis."], [{:Label=>"CONCLUSIONS", :NlmCategory=>"CONCLUSIONS"}, "Although the findings do not support an important role for PAF in TNF alpha/IL-1 beta-induced uveitis, it cannot be ruled out that more intensive treatment with a specific and long-acting PAF-receptor antagonist might yield more positive results."]]}, number={2}, journal={GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY}, author={FLEISHER, L and FERRELL, J and MCGAHAN, C}, year={1995}, month={Feb}, pages={94–100} }
 @article{mcgahan_harned_goralska_sherry_fleisher_1995, title={TRANSFERRIN SECRETION BY LENS EPITHELIAL-CELLS IN CULTURE}, volume={60}, ISSN={["0014-4835"]}, DOI={10.1016/S0014-4835(05)80008-9}, abstractNote={Transferrin (Tf), the plasma iron transport protein which supports cell proliferation and differentiation and has bacteriostatic, antioxidant and anti-inflammatory activity, has been found in relatively high concentrations in the intraocular fluids. Intraocular synthesis of Tf has recently been demonstrated, although the intraocular tissue(s) responsible have not been identified. We designed this study to determine whether certain ocular tissues can make and secrete transferrin. Transferrin content of aqueous and vitreous humors and whole lenses was determined by ELISA. Transferrin secretion by cultured epithelia from lens and ciliary body was also measured. In addition, Northern blots of RNA from cultured lens epithelial cells, ciliary body pigmented and non-pigmented epithelial cells, and from whole iris, ciliary body and retina were probed with riboprobes for Tf mRNA and 18S rRNA. Transferrin made up 23% and 16% of total canine aqueous and vitreous protein. All ocular tissues and cultured cells tested contained mRNA for Tf, however Tf was secreted into the bathing medium from lens epithelial cell cultures, but not from either the pigmented or non-pigmented epithelial cells of the ciliary body Cycloheximide inhibited secretion of Tf from the lens epithelial cells. Lenses from inflamed eyes contained higher levels of Tf than their contralateral controls. This is the first experimental demonstration that an intraocular tissue can make and secrete Tf. Transferrin secretion by the lens may contribute significantly to the IOF content of this important intraocular protein.}, number={6}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC and HARNED, J and GORALSKA, M and SHERRY, B and FLEISHER, LN}, year={1995}, month={Jun}, pages={667–673} }
 @article{echelman_nasisse_shields_mcgahan_fleisher_1994, title={INFLUENCE OF EXPOSURE TIME ON INFLAMMATORY RESPONSE TO NEODYMIUM - YAG CYCLOPHOTOCOAGULATION IN RABBITS}, volume={112}, ISSN={["1538-3601"]}, DOI={10.1001/archopht.1994.01090190125032}, abstractNote={OBJECTIVE
To evaluate the influence of duration of exposure on the inflammatory response to transscleral neodymium:YAG cyclophotocoagulation.


METHODS
Transscleral cyclophotocoagulation was performed with a contact, Nd:YAG, continuous-wave laser on one eye of 48 Dutch belted rabbits, 10 W and 0.2 second used in half and 1 W and 2 seconds in the other half. One third of each group was evaluated on the operative day and the other thirds on postoperative days 3 and 10. Tissue reaction was inspected grossly and by light microscopy, and inflammatory responses were measured by aqueous leukocyte and erythrocyte counts, aqueous and vitreous protein levels, aqueous prostaglandin levels, and iris and ciliary body myeloperoxidase activity.


RESULTS
The shorter-duration protocol was associated with more ciliary epithelial disruption and significantly greater inflammatory responses by one or more of the measures at all times.


CONCLUSION
When energy is constant, a shorter duration of exposure with transscleral Nd:YAG cyclophotocoagulation in rabbits is associated with greater tissue disruption and inflammation.}, number={7}, journal={ARCHIVES OF OPHTHALMOLOGY}, author={ECHELMAN, DA and NASISSE, MP and SHIELDS, MB and MCGAHAN, MC and FLEISHER, LN}, year={1994}, month={Jul}, pages={977–981} }
 @article{mcgahan_harned_grimes_fleisher_1994, title={REGULATION OF FERRITIN LEVELS IN CULTURED LENS EPITHELIAL-CELLS}, volume={59}, ISSN={["0014-4835"]}, DOI={10.1006/exer.1994.1140}, abstractNote={In most eukaryotic cells, synthesis of the iron storage protein, ferritin is regulated by iron levels and redox conditions. Proper iron storage is important to protect against damaging iron-catalysed free radical reactions. Although iron-catalysed reactions are believed to contribute to oxidative damage and cataractogenesis, little is known about iron storage in the lens. In this study, ferritin concentration was measured in cultured canine lens epithelial cells. Baseline ferritin concentration ranged from 76-163 ng (mg protein)-1; cells cultured in low-iron media had significantly lower ferritin levels than cells cultured in iron-supplemented media. Addition of a large excess of iron as hemin resulted in an eight-fold increase in ferritin concentration. The iron chelator, Desferal, significantly decreased ferritin concentration. The reducing agent dithiothreitol decreased the hemin-induced increase in ferritin levels, but not baseline levels. In contrast, ascorbic acid induced a large increase in ferritin content. Other studies have shown that induction of ferritin synthesis can protect against oxidative damage. Regulation of ferritin levels may represent a mechanism by which the lens epithelium is protected from oxidative damage. In vivo, epithelial cells are normally exposed to much lower iron concentrations than the cultured lens epithelial cells in this study. However, in pathological circumstances, the iron content and redox state of the aqueous humor is dramatically altered and may affect the steady state levels of ferritin within the lens. This remains to be determined.}, number={5}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC and HARNED, J and GRIMES, AM and FLEISHER, LN}, year={1994}, month={Nov}, pages={551–555} }
 @misc{mcgahan_grimes_fleisher_1994, title={TRANSFERRIN INHIBITS THE OCULAR INFLAMMATORY RESPONSE}, volume={58}, ISSN={["0014-4835"]}, DOI={10.1006/exer.1994.1044}, abstractNote={Iron is essential for retinal function but contributes to oxidative stress-mediated degeneration. Iron retinal homeostasis is highly regulated and transferrin (Tf), a potent iron chelator, is endogenously secreted by retinal cells. In this study, therapeutic potential of a local Tf delivery was evaluated in animal models of retinal degeneration.After intravitreal injection, Tf spread rapidly within the retina and accumulated in photoreceptors and retinal pigment epithelium, before reaching the blood circulation. Tf injected in the vitreous prior and, to a lesser extent, after light-induced retinal degeneration, efficiently protected the retina histology and function. We found an association between Tf treatment and the modulation of iron homeostasis resulting in a decrease of iron content and oxidative stress marker. The immunomodulation function of Tf could be seen through a reduction in macrophage/microglial activation as well as modulated inflammation responses. In a mouse model of hemochromatosis, Tf had the capacity to clear abnormal iron accumulation from retinas. And in the slow P23H rat model of retinal degeneration, a sustained release of Tf in the vitreous via non-viral gene therapy efficently slowed-down the photoreceptors death and preserved their function.These results clearly demonstrate the synergistic neuroprotective roles of Tf against retinal degeneration and allow identify Tf as an innovative and not toxic therapy for retinal diseases associated with oxidative stress.}, number={4}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC and GRIMES, AM and FLEISHER, LN}, year={1994}, month={Apr}, pages={509–511} }
 @article{mcgahan_fleisher_1992, title={CELLULAR-RESPONSE TO INTRAVITREAL INJECTION OF ENDOTOXIN AND XANTHINE-OXIDASE IN RABBITS}, volume={230}, ISSN={["0721-832X"]}, DOI={10.1007/BF00175935}, abstractNote={In the present study, the ocular inflammatory response to intravitreally injected endotoxin and xanthine oxidase was studied and the cellular response of the anterior and posterior segments was contrasted. There was a clear dose response relationship to both compounds in aqueous humor protein concentration and aqueous and vitreous humor white cell number. Xanthine oxidase and low doses of endotoxin (0.25 and 1.0 ng) produce a mainly mononuclear response in the anterior segment. Higher doses of endotoxin (10 and 100 ng) produced a predominantly neutrophilic response. Cellular infiltration into the posterior segment differed qualitatively and quantitatively from the anterior segment in response to the same stimuli. Myeloperoxidase (MPO) activity (a marker for neutrophils) of the iris-ciliary body was increased only in those eyes with a large neutrophilic response and thus is not recommended for use as a definitive index of the ocular inflammatory response, but may be a useful adjunct for such studies.}, number={5}, journal={GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY}, author={MCGAHAN, MC and FLEISHER, LN}, year={1992}, month={Aug}, pages={463–467} }
 @article{mcgahan_1992, title={DOES THE LENS SERVE AS A SINK FOR IRON DURING OCULAR INFLAMMATION}, volume={54}, ISSN={["0014-4835"]}, DOI={10.1016/0014-4835(92)90131-B}, abstractNote={Twenty-four hours after induction of ocular inflammation by intravitreal injection of endotoxin (10 ng), the intraocular fluid (IOF, aqueous and vitreous humors) concentration of iron (Fe) increased. This was presumably due to entry of the plasma Fe-binding protein, transferrin, into the IOFs through disrupted blood ocular barriers. After 1 day of inflammation the Fe concentration in lenses from the inflamed eye was 60% greater than that measured in contralateral control lenses. By day 15, lens Fe concentration had returned to levels of the contralateral control lenses. There was a distinct relationship between the dose of endotoxin used and the amount of Fe accumulated by the lens. The Fe concentration in lenses from eyes injected with 100 ng endotoxin was 0·376±0·027 μg g−1 wet weight compared to 0·214±0·014 μg g−1 in lenses from eyes injected with 0·25 ng endotoxin. In a previous study, copper (Cu) concentration in the IOFs was elevated to the same extent as Fe in response to intravitreal injection of endotoxin. However, in the present study, lenticular Cu concentration was unaltered at the highest (100 ng) dose of endotoxin. Since the increase in lens uptake was selective for Fe, there may be a specific Fe uptake mechanism in this ocular tissue. The physiological reasons for and possible pathological consequences of such a process are discussed.}, number={4}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC}, year={1992}, month={Apr}, pages={525–530} }
 @article{ferrell_fleisher_smith_mcgahan_1992, title={Effects of copper loading and depletion on rabbit superoxide dismutase activity}, volume={9}, journal={Trace Elements in Medicine}, author={Ferrell, J. B. and Fleisher, L. N. and Smith, M. G. and McGahan, M. C.}, year={1992}, pages={55–58} }
 @article{fleisher_ferrell_mcgahan_1992, title={Synergistic uveitic effects of tumor necrosis factor-alpha and interleukin-1 beta}, volume={33}, journal={Investigative Ophthalmology and Visual Science}, author={Fleisher, L. N. and Ferrell, J. B. and McGahan, M. C.}, year={1992}, pages={2120–2127} }
 @article{mcgahan_fleisher_grimes_1991, title={EFFECTS OF COPPER DEPLETION AND D-PENICILLAMINE TREATMENT ON THE OCULAR INFLAMMATORY RESPONSE}, volume={34}, ISSN={["0065-4299"]}, DOI={10.1007/bf01988736}, abstractNote={Rabbits placed on a copper (Cu)-deficient diet for four weeks had lower plasma Cu concentration, ferroxidase activity, and antioxidant activity than rabbits fed an identical Cu-adequate basal diet. Inflamed aqueous humor from rabbits on the Cu deficient diet also had less Cu, ferroxidase and antioxidant activity than inflamed aqueous humor from control rabbits. These differences mirrored changes in plasma levels. Furthermore, there was an increase in cellular infiltration into the aqueous humor of Cu-deficient rabbits. It is hypothesized that in Cu-deficient rabbits there is an increase in free radical production and formation of chemotactic substances in the eye due to the decreased aqueous humor concentration of the endogenous antioxidant, ceruloplasmin. It is therefore likely that ceruloplasmin plays a protective role in the intraocular inflammatory response.}, number={3-4}, journal={AGENTS AND ACTIONS}, author={MCGAHAN, MC and FLEISHER, LN and GRIMES, AM}, year={1991}, month={Nov}, pages={405–409} }
 @article{fleisher_ferrell_mcgahan_1991, title={Lipid mediators of TNF- induced uveitis}, volume={32}, journal={Investigative Ophthalmology and Visual Science}, author={Fleisher, L. N. and Ferrell, J. B. and McGahan, M. C.}, year={1991}, pages={2393–2399} }
 @article{mcgahan_grimes_1991, title={SELENIUM CONCENTRATION IN OCULAR-TISSUES AND FLUIDS}, volume={23}, ISSN={["0030-3747"]}, DOI={10.1159/000267087}, abstractNote={A simple, precise method for the analysis of selenium (Se) in ocular fluids and tissues using electrothermal atomic absorption spectroscopy is presented. Se concentrations ranged from 0.23 to 0.41 microgram/g wet weight in the cornea, iris, lens, and retina. The Se concentration in aqueous humor was 0.008 microgram/ml, thus much lower than that of plasma (0.21 microgram/ml). The concentration of protein in aqueous humor is about 1.0% of plasma. Since in plasma, Se is entirely bound to proteins, it is likely that the difference in Se concentration between plasma and aqueous humor reflects the relative distribution of protein between these fluids.}, number={1}, journal={OPHTHALMIC RESEARCH}, author={MCGAHAN, MC and GRIMES, AM}, year={1991}, pages={45–50} }
 @article{mcgahan_1990, title={COPPER AND ASPIRIN TREATMENT INCREASE THE ANTIOXIDANT ACTIVITY OF PLASMA}, volume={31}, ISSN={["0065-4299"]}, DOI={10.1007/bf02003222}, abstractNote={Copper (Cu) complexes of a number of compounds have increased anti-inflammatory efficacy over the native compound. In the present study, Cu and acetylsalicylic acid (ASA) were administered to rabbits over a one week period. At the end of this time, ocular inflammation was induced by intravitreal injection of endotoxin. ASA caused a slight reduction in the inflammatory response at 24 hours, but this response was not further decreased when Cu was added to the treatment regimen. However, there was a gradual and significant increase in antioxidant activity in the plasma of animals in the combined treatment group which could not be accounted for by a Cu-ASA complex, an increase in the concentration of known plasma protein antioxidants (ceruloplasmin and transferrin) or an increase in superoxide dismutase activity. The compound(s) responsible for this increased activity has a molecular weight greater than 10,000 Da. A large increase in plasma antioxidant activity may have a protective effect in other models of inflammation and provide a mechanism for the proven increase in anti-inflammatory efficacy of Cu-chelates of many compounds.}, number={1-2}, journal={AGENTS AND ACTIONS}, author={MCGAHAN, MC}, year={1990}, month={Aug}, pages={59–64} }
 @article{fleisher_ferrell_mcgahan_1990, title={OCULAR INFLAMMATORY EFFECTS OF INTRAVITREALLY INJECTED TUMOR NECROSIS FACTOR-ALPHA AND ENDOTOXIN}, volume={14}, ISSN={["0360-3997"]}, DOI={10.1007/BF00915816}, number={3}, journal={INFLAMMATION}, author={FLEISHER, LN and FERRELL, JB and MCGAHAN, MC}, year={1990}, month={Jun}, pages={325–335} }
 @article{mcgahan_fleisher_grimes_1989, title={CLINICAL SIGNS OF ACUTE OCULAR INFLAMMATORY RESPONSE TO ENDOTOXIN ARE NOT ALTERED BY INCREASING ANTIOXIDANT POTENCY OF INTRAOCULAR FLUIDS}, volume={13}, ISSN={["0360-3997"]}, DOI={10.1007/BF00914923}, abstractNote={Plasma antioxidant activity is due in large part to the ferroxidase activity of the copper (Cu) transport protein, ceruloplasmin. Implantation of osmotic pumps containing copper into rabbits resulted in a doubling of Cu concentration, ferroxidase activity, and antioxidant activity in plasma. Blood-ocular barriers essentially prevent the entry of large molecules such as proteins from plasma into the intraocular fluid compartments. However, during ocular inflammation, when these barriers are disrupted, plasma proteins can enter. Twenty-four hours after the induction of ocular inflammation by intraocular injection of endotoxin, the Cu concentration and antioxidant activity of intraocular fluids from the Cu pump animals was twice that of control groups, reflecting the differences in plasma levels. This is the first direct demonstration that alterations in plasma levels of ceruloplasmin can influence the antioxidant potency of the extracellular fluids. Increased intraocular fluid antioxidant activity did not affect the acute anterior segment response to endotoxin. However, it is possible that the time course and resolution of the response is altered by changes in extracellular fluid antioxidant activity. This possibility is currently under investigation.}, number={4}, journal={INFLAMMATION}, author={MCGAHAN, MC and FLEISHER, LN and GRIMES, AM}, year={1989}, month={Aug}, pages={393–400} }
 @article{fleisher_ferrell_olson_mcgahan_1989, title={DIMETHYLTHIOUREA INHIBITS THE INFLAMMATORY RESPONSE TO INTRAVITREALLY-INJECTED ENDOTOXIN}, volume={48}, ISSN={["0014-4835"]}, DOI={10.1016/0014-4835(89)90038-9}, abstractNote={Dimethylthiourea, a potent scavenger of toxic oxygen metabolites such as the hydroxyl radical, hypochlorous acid, and hydrogen peroxide, was tested for its ability to inhibit an experimentally induced inflammatory response. Inflammation was induced in one eye of male New Zealand white rabbits by intravitreal injection of 10 ng Escherichia coli endotoxin; the contralateral eye received an equal volume of pyrogen-free saline vehicle. Dimethylthiourea was administered intraperitoneally to these animals at 0, 300, 450 and 600 mg kg−1. At 24 h post-endotoxin injection, all vehicle-injected eyes appeared normal with the exception of a small, but significant increase in aqueous humor protein concentration in the 600 mg kg−1 dimethylthiourea group. In endotoxin-injected eyes, treatment with dimethylthiourea, especially at the highest dose, significantly reduced iridal hyperemia, aqueous humor cell number and protein and prostaglandin-E concentrations, and the ex vivo release of prostaglandin-E from the lens. The ability of dimethylthiourea to significantly inhibit the inflammatory response to intravitreally-injected endotoxin suggests that toxic oxygen metabolites may play an important role in the initiation and/or propagation of this form of acute anterior uveitis. Furthermore, the data are consistent with an important interaction between toxic oxygen and arachidonic acid metabolites.}, number={4}, journal={EXPERIMENTAL EYE RESEARCH}, author={FLEISHER, LN and FERRELL, JB and OLSON, NC and MCGAHAN, MC}, year={1989}, month={Apr}, pages={561–567} }
 @article{mcgahan_grimes_fleisher_1989, title={Ferroxidase activity increases dramatically in the aqueous humor during the ocular inflammatory response}, volume={21}, DOI={10.1159/000266811}, abstractNote={Ferroxidase activity was increased in the aqueous humor from inflamed eyes compared to their uninflamed contralateral controls 24 h after intravitreal injection of 10 ng of endotoxin. Changes in ferroxidase activity and copper concentration paralleled each other indicating that the plasma copper transport protein ceruloplasmin (plasma ferroxidase) entered the inflamed aqueous humor from plasma through disrupted blood ocular barriers. The presence of ferroxidase activity would facilitate the removal of potentially damaging, free radical generating Fe+2. Therefore, plasma proteins may perform important protective functions in the inflamed intraocular fluids.}, journal={Ophthalmic Research}, author={McGahan, M. C. and Grimes, A. M. and Fleisher, L. N.}, year={1989}, pages={221–225} }
 @article{mcgahan_fleisher_1988, title={Inflammation-induced changes in the concentration of iron and total-iron-binding capacity in the intraocular fluids of rabbits}, volume={226}, DOI={10.1007/BF02172712}, abstractNote={Changes in iron (Fe) concentration and total-iron-binding capacity (TIBC) of the intraocular fluids were measured during endotoxin-induced ocular inflammation in rabbits over a 3-week time course. In the aqueous humor, both Fe and TIBC increased to peak levels 24 h after intravitreal injection of endotoxin (10 ng) and gradually decreased to baseline levels by 3 weeks. In the uninflamed eye, the TIBC of the aqueous was only 23% saturated. During inflammation the TIBC became more highly saturated over time, reaching 50% at 3 weeks. In the vitreous humor the picture was more complicated due to the presence of slight hemorrhage. Noncellular Fe and TIBC increased to peak levels by 7 days, while TIBC approached 100% saturation. Both returned to baseline by 21 days. The influx of the partially saturated plasma protein transferrin through disrupted blood-ocular barriers most likely accounts for the increased TIBC in the inflamed eye and could provide some protection against the potentially harmful effects of Fe arising from tissue necrosis and hemolysis subsequent to hemorrhage. Under conditions of the model of inflammation studied here, the TIBC was not exceeded at any time during the 3 weeks. However, with more severe and long-lasting inflammation or when there is greater hemorrhage, the TIBC could be exceeded. This could lead to greater, and perhaps irreversible, damage to ocular tissues.}, journal={Graefes Archive for Clinical and Experimental Ophthalmology}, author={McGahan, M. C. and Fleisher, L. N.}, year={1988}, pages={27–30} }
 @article{matthews_mcgahan_1987, title={CYSTEINE - AN EFFECTIVE MATRIX MODIFIER FOR DETERMINATION OF GOLD IN BIOLOGICAL SAMPLES BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROPHOTOMETRY}, volume={42}, ISSN={["0584-8547"]}, DOI={10.1016/0584-8547(87)80101-5}, abstractNote={A method was developed for determination of gold in body fluids and tissues using electrothermal atomic absorption spectrophotometry with Zeeman effect background correction. There was excellent recovery of gold added to undiluted blood plasma. However, there was generally poor recovery of gold added to the intraocular fluids and tissue digests. Addition of plasma proteins and amino acids as matrix modifiers increased both the absorbance signal of the standard and the recovery of gold added to intraocular fluids and tissue digests. Cysteine (20 mgml) was found to be the most effective matrix modifier in all cases. This signal increasing effect may be limited to gold since neither protein nor amino acids were effective in increasing absorbance signals of other elements, including Fe, Pb and Cu.}, number={7}, journal={SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY}, author={MATTHEWS, DO and MCGAHAN, MC}, year={1987}, pages={909–913} }
 @article{mcgahan_tyczkowska_1987, title={THE DETERMINATION OF PLATINUM IN BIOLOGICAL-MATERIALS BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROSCOPY}, volume={42}, ISSN={["0584-8547"]}, DOI={10.1016/0584-8547(87)80122-2}, abstractNote={Methods for determination of platinum in body tissues and fluids by electrothermal atomic absorption spectroscopy are described. Serum and urine could be analyzed without pretreatment or dilution. Wet and dry ashing techniques for tissue digestion were compared. Dry ashing tissues in a furnace resulted in significant and unexplained losses of analyte, whereas there was complete recovery of platinum added to the tissues when the tissues were wet ashed. The wet ashing technique is fast and convenient and requires minimal sample treatment.}, number={5}, journal={SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY}, author={MCGAHAN, MC and TYCZKOWSKA, K}, year={1987}, pages={665–668} }
 @article{mcgahan_fleisher_1986, title={A MICROMETHOD FOR THE DETERMINATION OF IRON AND TOTAL IRON-BINDING-CAPACITY IN INTRAOCULAR FLUIDS AND PLASMA USING ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROSCOPY}, volume={156}, ISSN={["0003-2697"]}, DOI={10.1016/0003-2697(86)90271-X}, abstractNote={A new micromethod (requiring only 30 microliters of sample) for the determination of iron (Fe) concentration and total iron-binding capacity (TIBC) in intraocular fluids (IOFs; aqueous and vitreous humors) and plasma has been developed using electrothermal atomic absorption spectrophotometry. Values for Fe concentration in the IOFs were similar between species and were generally higher in the vitreous (0.031-0.060 mg/liter) than aqueous (0.014-0.038 mg/liter) humors obtained from the same eye. Plasma Fe concentration and TIBC fell within established limits for all species studied. The iron binding capacity of the aqueous and vitreous humors from the same species is similar. While the TIBC of the aqueous humor is saturated to the same extent as plasma, vitreous TIBC is more highly saturated in all species. Using this method considerably less species variation in IOF Fe concentration was found as compared to previous studies. Some possible methodological reasons for this difference are discussed.}, number={2}, journal={ANALYTICAL BIOCHEMISTRY}, author={MCGAHAN, MC and FLEISHER, LN}, year={1986}, month={Aug}, pages={397–402} }
 @article{mcgahan_fleisher_1986, title={ANTIOXIDANT ACTIVITY OF AQUEOUS AND VITREOUS-HUMOR FROM THE INFLAMED RABBIT EYE}, volume={5}, ISSN={["0271-3683"]}, DOI={10.3109/02713688609015131}, abstractNote={The effects of aqueous and vitreous humors and plasma on the rate of auto-oxidation of a rabbit brain homogenate were measured. Both aqueous and vitreous humors from normal eyes increased, while plasma decreased the rate of oxidation in the homogenate. During endotoxin-induced ocular inflammation the copper (Cu) and iron (Fe) concentrations of both the aqueous and vitreous humors increased, most likely due to the influx of their plasma binding proteins, ceruloplasmin (Cu) and transferrin (Fe). As both proteins are known to be antioxidants, it was not surprising to find that the aqueous and vitreous humor from the inflamed eyes had significant antioxidant activity. This antioxidant activity correlated well with the concentrations of Cu and Fe in aqueous humor and Cu but not Fe in the vitreous humor throughout the time course of the inflammatory response. Thus, entry of plasma proteins through disrupted blood ocular barriers may function in protecting ocular tissues against the increased oxidation which occurs during inflammation.}, number={9}, journal={CURRENT EYE RESEARCH}, author={MCGAHAN, MC and FLEISHER, LN}, year={1986}, month={Sep}, pages={641–645} }
 @article{cook_mcgahan_1986, title={COPPER CONCENTRATION IN CORNEA, IRIS, NORMAL, AND CATARACTOUS LENSES AND INTRAOCULAR FLUIDS OF VERTEBRATES}, volume={5}, ISSN={["0271-3683"]}, DOI={10.3109/02713688608995168}, abstractNote={A method using electrothermal atomic absorption spectroscopy was developed for the determination of copper (Cu) concentration in the cornea, iris, and lens of a variety of species, including dog, cat, rabbit, horse, and toad. Previously described methods were used to determine Cu in aqueous and vitreous humor. There was little difference between copper levels in the same tissue or fluid across the species. However, there were age and pathology-related changes in Cu concentration of the aqueous humor, cornea, and lens. In the groups of older dogs, the Cu concentration of the aqueous humor and cornea is significantly lower than the two younger groups. In both the dog and rabbit, lenses from young animals have the lowest copper concentration which increases and then finally decreases with age. Canine hypermature cataracts have a significantly higher copper concentration than control dogs of all age groups. There was no correlation between Cu concentration in the intraocular fluids and the cataractous lenses taken from the same eye. The role such an increase in lenticular Cu concentration may play in cataractogenesis needs to be explored.}, number={1}, journal={CURRENT EYE RESEARCH}, author={COOK, CS and MCGAHAN, MC}, year={1986}, month={Jan}, pages={69–76} }
 @article{mcgahan_matthews_bentley_1986, title={Effects of melittin on a model renal epithelium, the toad urinary bladder}, volume={855}, DOI={10.1016/0005-2736(86)90189-6}, abstractNote={The bee venom melittin, 10(-6) M, on the mucosal (urinary) side of the toad urinary bladder (in vitro), markedly decreased transepithelial potential difference, short-circuit current (Isc, sodium-dependent) and resistance. However, these effects were not seen when the toxin was placed on the opposite (serosal) side of the membrane preparation. The electrical effects were accompanied by a large increase in the transepithelial permeability to 22Na. The response was not changed by meclofenamic acid (which blocks formation of prostaglandins) but it was inhibited by La3+. In the presence of amiloride, which usually inhibits active Na transport and Isc, melittin, on the mucosal side, increased the Isc. The action of melittin appears to involve an interaction with anionic sites, which mediate its effects. Such sites appear to be present on the apical plasma membranes of the toad bladder epithelial cells, but they are not as abundant or they are inaccessible on the basal plasma membrane.}, journal={Biochimica et Biophysica Acta}, author={McGahan, M. C. and Matthews, D. O. and Bentley, P. J.}, year={1986}, pages={63–67} }
 @article{mcgahan_bito_myers_1986, title={THE PATHOPHYSIOLOGY OF THE OCULAR MICROENVIRONMENT .2. COPPER-INDUCED OCULAR INFLAMMATION AND HYPOTONY}, volume={42}, ISSN={["0014-4835"]}, DOI={10.1016/0014-4835(86)90049-7}, abstractNote={The ocular effects of intravitreally injected copper sulfate solutions were studied in New Zealand white rabbits. These injections resulted in uveitis characterized by prolonged ocular hypotony, increased protein concentrations and decreased ascorbic acid concentrations in both the vitreous and aqueous humors, and an apparent decrease in the transport function of the anterior uvea. The extent and the duration of these effects were dose-dependent. The lower doses used, 3 or 6 micrograms of Cu as CuSO4 per eye, produced reversible inflammation. The highest dose, 30 micrograms of Cu per eye, also produced some signs of ocular chalcosis: hemorrhage, vitreous liquefaction, prolonged hypotony and local iridial ischemia. Six hours after the intravitreal injection of 6 micrograms of Cu as CuSO4 per eye, the Cu concentration in the vitreous humor increased to approximately 100 times that in the vitreous of control eyes, and began to decline only 3 days later, with a half-time of approximately 8 days. The Cu concentration in the anterior chamber of these eyes never exceeded 1 ppm and returned close to control values within 3 days. Based on these findings, factors that affect ocular trace-metal distribution and kinetics are discussed, as are reasons for the apparent difficulty in diagnosing the presence of Cu-containing intraocular foreign bodies on the basis of the Cu concentration of the aqueous humor.}, number={6}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC and BITO, LZ and MYERS, BM}, year={1986}, month={Jun}, pages={595–605} }
 @article{fleisher_mcgahan_1986, title={TIME COURSE FOR PROSTAGLANDIN SYNTHESIS BY RABBIT LENS DURING ENDOTOXIN-INDUCED OCULAR INFLAMMATION}, volume={5}, ISSN={["0271-3683"]}, DOI={10.3109/02713688609015129}, abstractNote={Three hours to 14 days following the intravitreal injection of 10 ng of E. coli endotoxin into the vitreal chamber of one eye of the New Zealand white rabbit, ocular inflammation was evaluated by clinical and biochemical criteria and prostaglandins were measured in the intraocular fluids and in the incubation medium of the intact lens. Increased synthesis of PGE2 was detected for lenses from inflamed eyes beginning at 18 h post-endotoxin injection. Lenticular PGE2 synthesis remained above control levels for the duration of the time course. Lenses also exhibited increased PGF2 alpha synthesis, which began at 18 h and returned to control levels by day 7. At the times of peak production, aqueous humor PGE2 concentration correlated with lenticular PGE2 synthesis and with aqueous humor leukocyte number. No correlations were found for lenticular PGE2 vs. cell number, or vitreous humor PGE2 vs. aqueous humor PGE2. These results suggest that during ocular inflammation, aqueous humor PGE2 may be derived, at least in part, from the lens and leukocytes.}, number={9}, journal={CURRENT EYE RESEARCH}, author={FLEISHER, LN and MCGAHAN, MC}, year={1986}, month={Sep}, pages={629–634} }
 @article{mcgahan_1985, title={ASCORBIC-ACID LEVELS IN AQUEOUS AND VITREOUS HUMORS OF THE RABBIT - EFFECTS OF INFLAMMATION AND CERULOPLASMIN}, volume={41}, ISSN={["0014-4835"]}, DOI={10.1016/S0014-4835(85)80019-1}, abstractNote={A HPLC method for determination of ascorbic acid and dehydroascorbic acid in plasma and aqueous and vitreous humors of rabbits is described. Values for total ascorbic acid concentration found in this study are in agreement with those of previous investigators. Endotoxin-induced ocular inflammation caused a decrease in the concentration of ascorbic acid in the aqueous humor and an increase in the vitreous humor. The additional lack of correlation between levels of ascorbic acid in normal aqueous and vitreous humors from the same uninflamed eye indicates that the aqueous humor is not the source of vitreal ascorbic acid. The copper concentration of the aqueous humor is increased during ocular inflammation, most likely due to the influx of ceruloplasmin from plasma when the blood-aqueous barrier is disrupted. Ceruloplasmin caused a decrease in the amount of ascorbic acid in the aqueous humor in vitro and the vitreous humor in vivo. The presence of ceruloplasmin in the aqueous humor during inflammation thus may contribute to the decreased concentration of ascorbic acid in this fluid.}, number={3}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC}, year={1985}, pages={291–298} }
 @article{fleisher_mcgahan_1985, title={ENDOTOXIN-INDUCED OCULAR INFLAMMATION INCREASES PROSTAGLANDIN-E2 SYNTHESIS BY RABBIT LENS}, volume={40}, ISSN={["0014-4835"]}, DOI={10.1016/0014-4835(85)90140-X}, abstractNote={Twenty-four hours after the intravitreal injection of 0·1–100 ng of Escherichia coli endotoxin into one eye of the New Zealand white rabbit, lenses from the inflamed eyes synthesized significantly more prostaglandin E2 (PGE2) than their contralateral, control lenses at all doses of endotoxin greater than 0·1 ng. PGE2 elevations were also seen in the aqueous and vitreous humors from inflamed eyes. Lenses did not synthesize 6-keto-PGF1α (a stable metabolite of PGI2). Incubation of untreated lenses with 1 μg ml−1 of endotoxin for 24 h did not increase PGE2 production. These results indicate that rabbit lens can synthesize PGE2, that this synthesis is significantly increased 24 hr after the intravitreal infusion of E. coli endotoxin, and that this increased PGE2 synthesis is most likely not due to a direct action of endotoxin on the lens.}, number={5}, journal={EXPERIMENTAL EYE RESEARCH}, author={FLEISHER, LN and MCGAHAN, MC}, year={1985}, pages={711–719} }
 @article{mcgahan_hazard_bentley_1985, title={Melittin-induced changes in Na and Cl movements across toad's skin and cornea (in vitro) of the toad, Bufo marinus}, DOI={10.1016/0742-8413(85)90165-3}, abstractNote={1. Melittin, from bee venom, increases short-circuit current (Isc) across the skin and cornea of toads. 2. In skin this reflects a rise in the influx of Na and is inhibited by meclofenamic acid (inhibits prostaglandin synthetase). 3. In corneas with melittin on the inside the rise in Isc is inhibited by bumetanide (inhibits Cl transport) and meclofenamic acid. 4. Melittin on the tear side of the cornea causes a biphasic change in Isc, and a rise in all undirectional fluxes of Na and Cl. 5. This effect was not changed by bumetanide or meclofenamic acid. 6. Melittin apparently has two types of effects, one mediated by prostaglandins while the other is more direct.}, journal={Comparative Biochemistry and Physiology}, author={McGahan, M. C. and Hazard, R. L. and Bentley, P. J.}, year={1985}, pages={291–296} }
 @article{mcgahan_chin_bentley_1983, title={CALCIUM-METABOLISM OF THE RABBIT LENS}, volume={36}, ISSN={["0014-4835"]}, DOI={10.1016/0014-4835(83)90089-1}, abstractNote={The Ca concentration in the rabbit lens is less than that in its bathing aqueous and vitreous humors. This Ca is not distributed evenly in the tissue; it has a higher concentration in the outer peripheral than the inner parts of the organ. About 60% of the total lenticular Ca is present in a layer extending about 0.5 mm down from the outer surface (25% of the total tissue in the lens). When incubated in a solution containing 45Ca about 40% of the lenticular Ca readily exchanges with the isotope in 3 hr; no further change occurred over the next 21 hr. This exchange appeared to occur across either the anterior or posterior side of the lens. The accumulated 45Ca was found to be present in a surface layer about 1 mm deep. The remaining 60% of the lenticular Ca was difficult to displace. Incubation for 5 hr in a Ca-free solution containing EDTA or following freezing and thawing resulted in a loss of only an additional 20% of tissue Ca. The remaining 'immobilizable' Ca (40%) was present in both the nuclear and peripheral zones of the lens. When the Ca concentration of the external medium is raised, lens Ca rises also, and when the external concentration is reduced the tissue level declines. In the presence of metabolic inhibitors (iodoacetate plus cyanide) lenticular Ca rises. This effect is slow; little change was seen in 5 hr. Ca accumulation in the lens was enhanced by the Ca ionophore A23187 but an effect was not detectable in 5 hr. Incubation in Na-free media or ouabain did not influence Ca accumulation suggesting that a Ca-Na exchange is not involved in regulation. Quercetin and orthovanadate, which can inhibit Ca-activated ATPase in some tissues were without effect on lens calcium. The phenothiazine trifluoperazine (TFP), however, enhanced accumulation of Ca. Efflux of accumulated 45Ca from the lens was rapid; 60% in 10 min and 90% in 3 hr. Lanthanum reduced the latter to 60% loss. Efflux of Ca from the lens was unchanged, under experimental conditions, by metabolic inhibitors, by EGTA, verapamil, TFP and vanadate.}, number={1}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC and CHIN, B and BENTLEY, PJ}, year={1983}, pages={57–66} }
 @article{mcgahan_bito_1983, title={DETERMINATION OF COPPER CONCENTRATION IN BLOOD-PLASMA AND IN OCULAR AND CEREBROSPINAL FLUIDS USING GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROSCOPY}, volume={135}, ISSN={["0003-2697"]}, DOI={10.1016/0003-2697(83)90749-2}, abstractNote={Published values for the concentration of Cu in cerebrospinal and intraocular fluids cover a very wide range (0.016 to 1.0 μg/ml) and include values which are several times higher than those which would be consistent with normal physiology. An atomic absorption spectrophotometer equipped with a graphite furnace was used to measure the Cu concentration in these fluids and in blood plasma of toads, rabbits, and cats. Under standard conditions, these fluids yielded high background absorbance and only fractional recovery of added Cu. Parameters were therefore established which eliminated both the high background and the matrix interference and allowed the determination of Cu in 10-μl aliquots of diluted blood plasma and undiluted cerebrospinal and ocular fluid samples. Under these conditions the Cumeasured in the ocular (0.011 to 0.032 μg/ml) and cerebrospinal fluids (0.033 to 0.050 μg/ml) of these three species was lower than most previously reported values and only a small fraction (1–3%) of the concentration of Cu in the plasma of the same animals (0.85 to 1.22 μg/ml).}, number={1}, journal={ANALYTICAL BIOCHEMISTRY}, author={MCGAHAN, MC and BITO, LZ}, year={1983}, pages={186–192} }
 @article{mcgahan_chin_bentley_1983, title={SOME OBSERVATIONS ON THE MAGNESIUM-METABOLISM OF THE RABBIT LENS}, volume={36}, ISSN={["0014-4835"]}, DOI={10.1016/0014-4835(83)90090-8}, abstractNote={The (Mg) concentration in the rabbit lens is about 3.25 mmol/kg wet wt or 4.7 mM. This level is much greater than that in the bathing aqueous and vitreous humors. The Mg concentration in the peripheral part of this tissue is about four times greater than that in the inner 'nuclear' regions. Exchanges of Mg between the lens and its bathing fluids are very slow; under control conditions the lens appears to be virtually impermeable to Mg. Exposure to metabolic inhibitors, depolarizing concentrations of potassium, ouabain or replacement of Na with Li had little effect on the Mg content of the lens. Incubation of lenses in solutions containing EDTA or following freezing and thawing suggested that much of the Mg is present in a bound form. The ionophore A-23187 increased the permeability of the lens to Mg. Adjustment of the external Mg level in the presence of A-23187 indicated that the internal 'free' Mg concentration was about 3 mM. This result suggests that about 35% of the lenticular magnesium is bound.}, number={1}, journal={EXPERIMENTAL EYE RESEARCH}, author={MCGAHAN, MC and CHIN, B and BENTLEY, PJ}, year={1983}, pages={67–73} }
 @article{mcgahan_bito_1983, title={THE PATHO-PHYSIOLOGY OF THE OCULAR MICROENVIRONMENT .1. PRELIMINARY-REPORT ON THE POSSIBLE INVOLVEMENT OF COPPER IN OCULAR INFLAMMATION}, volume={2}, ISSN={["0271-3683"]}, DOI={10.3109/02713688209020026}, abstractNote={The concentration of copper [( Cu]) in the extracellular fluid compartments of rabbit eyes was found to increase approximately 30-fold during experimental uveitis, generally paralleling increases in [protein]. However, during the recovery phase the decrease in [Cu] lags behind the decrease in [protein] in some rabbits, suggesting the presence of abnormally high levels of non-protein-associated Cu. Intravitreal injection of CuSO4 (6 micrograms of Cu/eye) causes an inflammatory response and evidence of tissue damage. A better understanding of trace element metabolism is clearly required to further elucidate the mechanism of ocular inflammation and associated tissue damage.}, number={12}, journal={CURRENT EYE RESEARCH}, author={MCGAHAN, MC and BITO, LZ}, year={1983}, pages={883–885} }
 @article{bentley_mcgahan_1982, title={A PHARMACOLOGICAL ANALYSIS OF CHLORIDE TRANSPORT ACROSS THE AMPHIBIAN CORNEA}, volume={325}, ISSN={["0022-3751"]}, DOI={10.1113/jphysiol.1982.sp014163}, abstractNote={1. Active Cl, but not Na, transport across the toad cornea was inhibited by mepacrine, which is a phospholipase A2 inhibitor; trifluoperazine, which blocks the action of calmodulin; and meclofenamic acid, which inhibits synthesis of prostaglandins. Bumetanide and DIDS (4,4'‐diisothiocyano‐2,2'‐stilbene disulphonic acid) have previously been shown to inhibit this Cl transport. The interactions of these antagonists with several agonists that increase Cl transport were studied. 2. The effects of adrenaline, prostaglandin E2, dibutyryl cyclic AMP (DBcAMP) and the Ca ionophore A23187 were inhibited by mepacrine, trifluoperazine and bumetanide. 3. The inhibitory effects of high concentrations of DIDS, however, could be overcome by all of the agonists except DBcAMP. 4. Meclofenamic acid only blocked the effects of A23187. 5. A model is proposed to account for the observed actions and interactions of the various antagonists and agonists on Cl transport. This involves possible roles for Ca, calmodulin and phospholipase A2.}, number={APR}, journal={JOURNAL OF PHYSIOLOGY-LONDON}, author={BENTLEY, PJ and MCGAHAN, MC}, year={1982}, pages={481–492} }
 @article{mcgahan_bentley_1982, title={STIMULATION OF TRANS-EPITHELIAL SODIUM AND CHLORIDE TRANSPORT BY ASCORBIC-ACID - INDUCTION OF NA+ CHANNELS IS INHIBITED BY AMILORIDE}, volume={689}, ISSN={["0006-3002"]}, DOI={10.1016/0005-2736(82)90273-5}, abstractNote={Ascorbic acid increases the short circuit current (Isc) across the amphibian cornea when it is present at either surface of this epithelium. These effects were additive. The effect was greater when it was on the tear side. The response returned to baseline levels when the ascorbic acid was washed from the bathing media. The effect of ascorbic acid on Isc when it was on the aqueous humor side of the cornea could be blocked by bumetanide but that due to the vitamin's presence on the tear side was unchanged. The ascorbic acid could enter the tissue and crossed the cornea at similar rates in either direction. When the cornea was bathed by a Cl−-free solution or exposed to bumetanide, the rise in Isc observed with ascorbic acid on the tear side was equivalent to an increased Na+ flux from the tear to the aqueous humor side. In normal (Cl− present) Conway solution the rise in the Isc seen with ascorbic acid on the aqueous humor side was equal to an increased flux of Cl− from the aqueous to the tear surface. However, when ascorbic acid was present on the opposite, tear, side the increased Isc reflected a rise in both Cl− and Na+ transport, aqueous-to-tear side, and tear-to-aqueous side, respectively. Thiol reagents (tear side), including reduced glutathione (10−5 M), blocked the effect of ascorbic acid (10−3 M) providing they were added to the bathing solution prior to the vitamin. However, they had no effect once the response had been established. The effect of the reduced glutathione appeared to be of a non-competitive nature. Oxidized glutatione (10−4 M) (and cystamine) blocked the effect of ascorbic acid (10−3 M) when present on the tear side prior to the vitamin. However, they also increased the rate of decline of the response when added subsequently to the ascorbic acid. Amiloride (as low as 5·10−9 M), on the tear side but not the aqueous humor side, prevented the response to ascorbic acid but could not reverse it, once it was established. The possible nature of the effect of ascorbic acid is discussed in relation to its pharmacological interactions with thiol and disulfide reagents and amiloride.}, number={2}, journal={BIOCHIMICA ET BIOPHYSICA ACTA}, author={MCGAHAN, MC and BENTLEY, PJ}, year={1982}, pages={385–392} }
 @article{mcgahan_1981, title={ALPHA-AMINOISOBUTYRIC-ACID EFFLUX FROM THE CORNEA OF THE TOAD, BUFO-MARINUS}, volume={315}, ISSN={["0022-3751"]}, DOI={10.1113/jphysiol.1981.sp013746}, abstractNote={1. Amino acids move into and out of the amphibian cornea across its inner aqueous, side only. Most alpha‐aminoisobutyric acid (AIB) accumulation takes place in the corneal epithelium; the endothelium and stroma do not limit exchanges with these cells. The apical, or tear, surface of the epithelium is an impermeable barrier to the transport of amino acids. There are several sites or mechanisms by which AIB enters and leaves the cornea. 2. The entry of AIB is not Na‐dependent; however, the exit site is very sensitive to changes in internal Na concentration. Any factor, such as ouabain or metabolic inhibitors, that increases internal Na, markedly stimulates AIB efflux. 3. Site are also present for the exchange of internal for external amino acids, and this process is Na‐dependent. There was no measurable movement of Na into or out of the cells with these amino acids. Exchange efflux was more specific than uptake, since both alanine and leucine inhibit AIB uptake, but only alanine stimulates AIB efflux. 4. Although the largest amount of AIB accumulated by the cornea was present in the epithelium, evidence is presented that the endothelium and stromal keratocytes may also concentrate and retain amino acids.}, number={JUN}, journal={JOURNAL OF PHYSIOLOGY-LONDON}, author={MCGAHAN, MC}, year={1981}, pages={253–266} }
 @article{mcgahan_bentley_1981, title={Alpha-aminoisobutyric acid transport in the amphibian crystalline lens}, volume={34}, journal={Journal of Physiology (London)}, author={McGahan, M. C. and Bentley, P. J.}, year={1981}, pages={49–56} }
 @article{mcgahan_bentley_1981, title={INHIBITION OF ALPHA-AMINOISOBUTYRIC-ACID UPTAKE BY DIISOTHIOCYANOSTILBENEDISULPHONIC ACID IN THE AMPHIBIAN CORNEA}, volume={643}, ISSN={["0006-3002"]}, DOI={10.1016/0005-2736(81)90240-6}, abstractNote={α-Aminoisobutyric acid accumulation of the toad's (Bufo marinus) cornea and lens is inhibited by 4,4′-diisothiocyano-2,2′-stilbenedisulfonic acid. This effect is seen at pH 8.4; at pH 7.4 a small increase in aminoisobutyric acid uptake was observed. Efflux of aminoisobutyric acid is unchanged by diisothiocyanostilbenedisulphonic acid at either pH. The inhibitory effect of diisothiocyanostilbenedisulphonic acid on aminoisobutyric acid accumulation appears to reflect a direct action on membrane mechanisms that mediate its influx.}, number={1}, journal={BIOCHIMICA ET BIOPHYSICA ACTA}, author={MCGAHAN, MC and BENTLEY, PJ}, year={1981}, pages={261–264} }
 @article{bentley_mcgahan_1980, title={INHIBITORY-ACTION OF DIDS ON CHLORIDE TRANSPORT ACROSS THE AMPHIBIAN CORNEA}, volume={304}, ISSN={["0022-3751"]}, DOI={10.1113/jphysiol.1980.sp013340}, abstractNote={1. DIDS (4,4'‐diisothiocyano‐2,2'‐stilbene disulphonic acid) reduced the CI Isc across the toad's (Bufo marinus) cornea. It acted on either the aqueous or tear side and these effects were additive. 2. The reduction in the Isc was equivalent to the decline in the undirectional flux of Cl from the aqueous to the tear side. The Cl flux from tear to aqueous was not changed. 3. DIDS did not change transmural Na transport. 4. The action of the diuretic bumetanide, which also inhibits Cl transport was additive to that of DIDS when both compounds were present on the aqueous though not when they were on the tear side of the cornea. 5. The results are consistent with the role of a Cl‐/anion exchange mechanism in active Cl transport across the cornea. 6. A hypothesis regarding the interactions and site of action of bumetanide in relation to that of DIDS, and the Cl transport process, is proposed.}, number={JUL}, journal={JOURNAL OF PHYSIOLOGY-LONDON}, author={BENTLEY, PJ and MCGAHAN, MC}, year={1980}, pages={519–527} }
 @article{mcgahan_yorio_bentley_1977, title={The mode of action of bumetanide: inhibition of chloride transport across the amphibian cornea}, volume={203}, journal={Journal of Pharmacology and Experimental Therapeutics}, author={McGahan, M. C. and Yorio, T. and Bentley, P. J.}, year={1977}, pages={97–102} }