摘要:

This paper describes initial results of experiments with a prolonged normothermic arterial perfusion of isolated bovine eyes. The eyes were perfused using oxygenated serum-free MEM. With respect to utilization of oxygen and use of glucose, viability could be proven for 5 days. After addition of some essential serum substitutes, viability could be extended to 9 days, moreover, doubled glucose utilization and decreasing LDH activity could also be measured. To prolonge and improve viability, much attention should be paid to oxygenation and composition of the perfusate.

ISSN:0271-3683    

DOI:10.3109/02713689308999453

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

We investigated the possibility that cultured corneal endothelial cells express receptors that are coupled to the phosphoinositide cycle/intracellular Ca2+signaling pathway. Agonist-stimulated changes in intracellular calcium ([Ca2+]i) in single bovine and human corneal endothelial cells (BCEC and HCEC, respectively) derived from confluent cultures were measured by microspectrofluorimetry using the Ca2+-sensitive probe, fura-2. Total inositol phosphates accumulated during a 30 min incubation in the presence or absence of agonists was determined in Li+containing medium with cells pre-labelled for 48 hrs with 10μCi/ml3H-myoinositol. Histamine (HA), ADP and ATP induced a rapid increase in [Ca2+]i. Subsequently, [Ca2+]idecreased to either a stable, agonist-dependent sustained elevation, or fell back to baseline to begin oscillatory fluctuations. The initial rise in [Ca2+]iwas insensitive to removal of extracellular calcium (Ca2+○), whereas the stable elevations in [Ca2+]iand the [Ca2+]ioscillations required Ca2+0. In contrast, bradykinin (BK) and endothelin-1 (ET-1) elicited an initial rise in [Ca2+]ithat returned to prestimulatory levels within 2 min despite the continued presence of agonist. The Ca2+-mobilizing agonists carbachol, phenylephrine, adenosine and substance P were all ineffective in elevating [Ca2+]i. Histamine-induced Ca2+mobilization was inhibited by the Hi-receptor antagonist triprolidine, but triprolidine had no effect on either BK or ATP stimulation of Ca2+mobilization. In BCEC, 100μM HA significantly increased total inositol phosphate accumulation (18.8-fold over unstimulated controls) and was 90% inhibited by 0.5μM triprolidine. BK and ATP also significantly increased formation of inositol phosphates in BCEC. These results indicate that the signal transduction pathway involving PI turnover and Ca2+mobilization is expressed in BCEC and HCEC cultures and is activated by HA, BK, ATP, ADP and ET-1.

ISSN:0271-3683    

DOI:10.3109/02713689308999454

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Loteprednol etabonate (LE) is a new corticosteroid based on the“soft drug”concept. Contact lens-associated giant papillary conjunctivitis (GPC) was studied as a model for the anti-inflammatory effect of LE. Patients with bilateral GPC were enrolled in a multicenter, randomized, double-masked, placebo-controlled, parallel group comparison of loteprednol etabonate 0.5% ophthalmic suspension and the LE vehicle (placebo). Patients were instructed to instill 1 drop of the test medication into each eye 4 times daily for 4 weeks, and follow-up examinations occurred on Days 2 or 3, 7, 14, 21, and 28 of masked therapy. Of 113 patients enrolled, 110 patients (LE=55; placebo=55) completed the study as planned. Patients receiving LE demonstrated significant reduction in the primary ocular signs of GPC (papillae, p<0.001) and were rated better in the Investigator's Global Assessment (p=0.017). LE did not elevate intraocular pressure during the study, and ratings for bulbar conjunctival injection and the Patient Opinion Assessment demonstrated statistical trends that favored treatment with LE. LE was well tolerated and was clinically effective for the treatment of GPC.

ISSN:0271-3683    

DOI:10.3109/02713689308999455

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The level of expression of the genes for hexokinase, aldose reductase and sorbitol dehydrogenase was investigated in lenses of mice and rats. These genes represent two separate but interrelated pathways for the metabolism of glucose in the cell. It is hypothesized that the extent of expression of the hexokinase gene may play an important role in the regulation of the levels of glucose in the lens. It is known that if there occurs a build up of intracellular glucose, such as in diabetes mellitus, activation of the aldose reductase/sorbitol dehydrogenase pathway may lead to various diabetic complications, including a lessening of lens clarity. We have therefore determined the levels of expression of the genes for these three enzymes in the lens of both mice and rats. Mice are known to be more resistant than rats to the development of lens opacification during hyperglycemia. By Northern blot hybridization analysis, and by quantitation of the resulting hexokinase, aldose reductase and sorbitol dehydrogenase mRNA hybrids, we found that in the mouse lens the expression of the hexokinase gene exceeded that of the aldose reductase gene by a factor of three, while in the rat it only approached about 1/4 that of the aldose reductase gene. The extent of expression of the SDH gene, however, was equal between the mouse and rat lenses. These results were calculated relative to the level of expression of theαA-crystallin gene in those two types of lenses, in order to account for the generally higher genetic expression found in the rat relative to the mouse lens due to its higher content of DNA, henceforth larger mass. The presence of high levels of hexokinase mRNAs relative to aldose reductase mRNAs in the lens would be expected to favor metabolism of glucose via the glycolytic pathway rather than the sorbitol pathway, leading to retardation of development of sugar cataracts in the mouse lens; while the opposite is true for the rat lens.

ISSN:0271-3683    

DOI:10.3109/02713689308999456

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Two glutathioneS-transferase (GST) isozymes, GST-rl1 and GST-rl2, were purified from rabbit lenses and their properties were compared with those of other animals. GST-rl1 and GST-rl2 are dimeric enzymes whose subunit sizes are 24,000 and 21,500, respectively. The substrate specificities and inhibitor sensitivities of GST-rl1 and GST-rl2 are different from each other and from those of the isozymes from other animals. GST-rl1 immunologically crossreacted with the antibody against classμGST (rat GST Yb1-Yb1), and GST-rl2 crossreacted with the antibody against classπGST (rat GST Yp-Yp). N-Terminal amino acid sequences of GST-rl1 and GST-rl2 have great homology with other classμand classπenzymes, and thus indicate that they belong to classμand classπ, respectively. ClassπGST-rl2 is inactivated by 1,2-naphthoquinone, an oxidized metabolite of naphthalene, but classμGST-rl1 is insensitive to it. These results are similar to those of classπpig lens GST and classμbovine lens GST. Thus, the expression pattern of GST isozymes in lens varies with animal species, and may relate to their variation in sensitivity to oxidative stress.

ISSN:0271-3683    

DOI:10.3109/02713689308999457

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The purpose of these experiments was to examine the relationship between oxidation cataract and proteolysis in cultured rat lens. Hydrogen peroxide cataract showed insolubilization of protein, loss of 31 kDaβB1-crystallin polypeptide, decreases in soluble calpain, and increases in insoluble calpain. This suggested that calpain may be activated in hydrogen peroxide treated lenses, sinceβBl is a known calpain substrate, and calpain undergoes autolysis and degradation when activated. Furthermore, the cysteine protease inhibitor E64 was partially effective in preventing development of H2O2-cataract. E64 also prevented the loss of the 31 kDaβBl-crystallin polypeptide and decreased the loss of calpain in the lens. These results suggested that development of hydrogen peroxide induced cataract in rat lenses was associated with activation of calpain.

ISSN:0271-3683    

DOI:10.3109/02713689308999458

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

In vivo and in vitro studies were performed to determine: (a) if human uveal melanoma cells expressed GD2 and GD3 gangliosides; (b) if anti-GD2 monoclonal antibodies would inhibit the propensity of human uveal melanoma cells to localize in the liver following intravenous injection; and (c) if anti-GD2 monoclonal antibody would reduce the spontaneous metastasis of primary intraocular melanomas in nude mice. The results showed that all three of the human uveal melanoma cell lines tested expressed GD2 and GD3 gangliosides in vitro and in vivo. The human uveal melanoma cell lines preferentially localized in the liver and entered the hepatic parenchyma following spontaneous metastasis from the eyes of nude mice. In vivo administration of anti-GD2 monoclonal antibody produced a sharp reduction in the number of uveal melanoma cells that disseminated to the liver following either intravenous injection or by spontaneous metastasis from primary intraocular melanomas. Collectively, the results demonstrate that uveal melanoma cells display a propensity to localize in the liver after entering the bloodstream; however, this localization can be significantly inhibited by in vivo administration of antiganglioside antibodies. The expression of GD2 and GD3 surface gangliosides on uveal melanomas and the capacity of anti-ganglioside antibodies to inhibit metastasis formation in mouse models of ocular and cutaneous melanomas raise the possibility of implementing anti-ganglioside antibodies as potential therapeutic agents for the management of uveal melanoma.

ISSN:0271-3683    

DOI:10.3109/02713689308999459

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

During phacoemulsification cavitation bubbles are formed. These bubbles are believed to be one source of damage to corneal endothelium seen after phacoemulsification. Free radicals are induced whenever cavitation bubbles implode. The aim of this study was to confirm the initiation of free radicals by phacoemulsification and to correlate the power of ultrasound in the phacoemulsification process to the amount of free radicals formed, using bothin vitroandin vivotechniques.The formation of free radicals was determined by adding luminol to a buffer and measuring the chemoluminescenscein vitroand in rabbit eyes (Lumacounter™2080 or a single-photon-counting apparatus) during phacoemulsification. The data obtained show that free radicals are formed during phacoemulsification and that the amount of free radicals correlates with the power of ultrasound. Furthermore, the radical formation could be inhibited by the radical scavengers SOD, Healon®and Healon®GV. These results were achieved bothin vitroin the test tube andin vivoin rabbit eyes. By showing that the addition of SOD to the irrigation buffer during phacoemulsification decreases the corneal endothelial cell damage, we show that free radicals could have a role in postoperative complications seen clinically.

ISSN:0271-3683    

DOI:10.3109/02713689308999460

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

In the RCS rat there is a progressive degeneration of the photoreceptors which starts at two to three weeks after birth. We have demonstrated that there is prolonged survival of photoreceptors on the flanks of argon laser lesions made at post-natal day 23, just as degeneration begins. The cells in the outer nuclear layer retained a relatively normal appearance on the flanks of the lesions for the first two weeks and there was a very low percentage of pyknotic cells. By one month some cell loss occurred but much less than in non-irradiated regions where very few cells remained. At two months after lesion there were still elevated numbers on the flanks but only 2–3 rows of cells remained. The prolonged survival correlated with disruption to the pigment epithelial layer, increased migration of phagocytic cells into the outer segment/debris layer and a reduction in thickness of the debris layer at late stages. The mechanisms of this effect are unknown however laser lesions provide a well controlled and reproducible situation in which to study these mechanisms.

ISSN:0271-3683    

DOI:10.3109/02713689308999461

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Using isozyme-specific anti-peptide antisera against peptides from theα-,β-,γ-,δ-,σ-, andϵ-isoforms of brain protein kinase C (PKC), we have identified proteins in bovine lens epithelial cells, in culture, that were reactive with these antisera. Western blots of lens epithelial cell homogenates showed that PKC-αántisera reacted with a major protein, and PKC-γantisera reacted with a minor protein. When the lens epithelial cells were cultured in media supplemented with 40 mM galactose, to model the conditions of sugar cataracts, a decrease in PKC-γ, but not in PKC-αwas observed. These were normalized if the cells were cultured in 40 mM galactose media supplemented with an inhibitor of aldose reductase, Tolrestat (10μM). These results suggest that changes in PKC isoforms occur in the galactosemic diabetic state.

ISSN:0271-3683    

DOI:10.3109/02713689308999462

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor