摘要:

As it is known that chlorpromazine (CPZ) can bind to melanins as well as cause ocular phototoxicity, we investigated the cytotoxic effects of UV-visible irradiation of melanotic and amelanotic retinal pigment epithelial (RPE) cells in the presence of CPZ. At low concentrations (5μg/ml) of CPZ a photosensitization reaction took place which lysed the cell is as measured by the release of51Cr from cells labelled with chromium. At concentrations of CPZ less than 5μg/ml, no significant cell lysis occurred when the cells were incubated at 37°C in the dark. As the concentration of CPZ was increased to 25μg/ml or more, high percentages of cells were lysed. When the melanotic RPE cells were exposed to different concentrations of CPZ and grown in culture, the cell growth (multiplication) diminished drastically with low concentrations (less than 2μg/ml CPZ). Vitamin E decreased the eel 1 lysis both in the dark and upon irradiation. Oxygen radical scavengers such as glutathione, B-carotene, mannitol, D-penicil lamine as well as superoxide dismutase and catalase did not decrease cell lysis. The phototoxic effects of CPZ was found not to be due to stable photoproducts formed during irradiation of CPZ.

ISSN:0271-3683    

DOI:10.3109/02713688809047014

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

Protein distribution patterns were determined in concentric layers removed from 24 bovine lenses ranging in age from about 6 months before birth to 180 months post-natal. It was possible to distinguish alterations in protein synthesis patterns during development and changes due to ageing, i.e., prolonged existence of the proteins. It was found thatα-crystallin represents a constant 50% of the proteins synthesized by the fibre cells throughout life. However, the protein becomes progressively less soluble with increasing age.β-crystallin synthesis increases from 30% of the total proteins during prenatal development to around 40% in post-natal fibre cells. This increase is due to increased production of theβI-crystallin. In old tissues,βH-crystallin is converted to a high molecular weight form (HMWβ)γ-crystallins account for 22% of the proteins synthesized in the earliest prenatal fibre cells. This level decreases rapidly through prenatal development until they represent about 4% of the total at birth.βS-crystallin synthesis commences around this time and in the post-natal fibre cells is essentially the only low molecular weight protein. The possible significance of some of these changes is discussed with regard to the functional requirements of the lens.

ISSN:0271-3683    

DOI:10.3109/02713688809047015

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

The size and shape of native alpha crystallin aggregates extracted at either 4°C (α-crystallin) or 37°C (αm-crystallin), were compared with each other, as well as with aggregates reconstituted from either pureαA orαB subunits using electron microscopy. TheαB aggregates were the most uniform in size (about 9 nm in diameter) and the best stained.αA particles were about the same size as theαB, but the population distribution was broader and some indication of interparticle association was observed.αcparticles exhibited a bimodal distribution, with one peak greater than the reconstituted particles and the other about the same size;αmwas smaller than the reconstituted structures.

ISSN:0271-3683    

DOI:10.3109/02713688809047016

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

A polyclonal antiserum was prepared in rabbits against the structural glycoprotein (S6P) complex previously isolated from a bacterial collagenase digest of bovine corneal stroma (R. Alper, Curr. Eye Res. 2:479, 1983). Direct and indirect enzyme-linked immunosorbent assays indicated that the antiserum was specific for the SGP-complex and did not react with Types I, III and IV collagen, fibronectin, laminin or actin. Immunoblot experiments indicated that the antiserum reacted with all of the components of the SGP-complex as well as with the cell matrix laid down by bovine keratocytes in culture. An attempt was made to isolate individual antibodies from the antiserum by selective elution from immunoblots of the components of the SGP-complex separated by SDS-PAGE. It was found that regardless of the protein band from which the antibody was eluted, every antibody isolated reacted with every protein component of the SGP-complex suggesting that the SGP-complex may have been derived from a single precursor protein and that the observed heterogeneity of the SGP-complex may have been the result of proteolytic breakdown of the protein held together by disulfide bonds. When the anti-SGP antiserum was used to immunoprecipitate14C-prol1ne labeled proteins from the media of bovine keratocytes in culture, the major protein observed had a Mr of about 140,000 daltons, similar to that of GP-140 also known as CL-glycoprotein. These proteins have been shown to represent the tissue form of Type VI collagen. To test the hypothesis that the SGP-complex may be related to the GP-140 (CL-glycoprotein), ELISA and immunoblotting studies were performed comparing the properties of the anti-SGP serum with those of a polyclonal antibody specific for Type VI collagen. The SGP-complex reacted positively by ELISA with the anti-human Type VI collagen antiserum and, conversely, human Type VI collagen gave a positive ELISA reaction with an antiserum against the SGP-complex. The anti-human Type VI collagen antiserum reacted with most of the major components of the SGP-complex on Immunoblots of SDS-PAGE gels. These data indicate that the SGP-complex is related to and probably is derived from the tissue form of Type VI collagen.

ISSN:0271-3683    

DOI:10.3109/02713688809047017

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

Vitamin A has been determined in tear fluid and blood plasma of marginally nourished Thai children before and after supplementation with a single, oral dose of 110 mg retinyl palmitate. After two months a significant rise of tear fluid retinol levels of the supplemented group was observed as compared to the non-supplemented group, while after four months no difference could be found. Determination of vitamin A levels in tear fluid may be useful in clinical eye research, with special regard to xerophthalmia.

ISSN:0271-3683    

DOI:10.3109/02713688809047018

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

The edema response over a 24-hour sleep/wake cycle of ten subjects wearing a rigid gas-permeable (RGP) lens in one eye and a hydrogel lens in the other was evaluated. Lenses that result in equivalent amounts of overnight edema were selected. There was no significant difference in the rates of deswelling during the initial hour. However, at three and five hours after eye opening, the amount of residual edema was greater in the eye wearing the hydrogel lens. We suggest that when an RGP lens provides the same closed-eye level of oxygen as a hydrogel lens, the greater tear exchange of the RGP lens will result in a greater open-eye oxygen supply, leading to less daytime edema. This suggests that the more complete deswelling we observed with RGP lenses can be attributed to a lower stimulus to open-eye swelling.Biomicroscopy, subjective vision, and patient comfort were also rated on waking and ten hours after eye opening. On eye opening there was significantly more back-surface debris (P=0.01) with the RGP lenses. Patients wearing RGPs rated comfort as poorer and vision as better but only the latter attained statistical significance.

ISSN:0271-3683    

DOI:10.3109/02713688809047019

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

The structures of the calf lens crystallin fractionsγ-II,γ-III, andγ-IV have been investigated using the fluorescence quenching method. The three crystallin fractions showed very large differences in the quenching rates of their fluorescent tryptophan residues, for quenching by acrylamide or iodide in pH 7.5 phosphate buffer solutions. The experimentally measured quenching rate constants were kq(II) =3.2×108, kq(IIII) = 9.9×10, and kq(IV) = 1.8×109M−1sec−1. Smaller rate constants were obtained for iodide quenching of the three crystallins, but the values were in approximately the same ratios as the ones found for acrylamide quenching. The conclusion is that the tryptophan residues inγ-II crystallin are 6–10 times less easily quenched than those ofγ-IV crystallin and 3–6 times less easily quenched than those ofγ-III. These conclusions are in accord with those reached by Mandal et. al. based on fluorescence and CD data, who found the following order of Trp hydrophobicities:γ-IIY>γ-III>γ-IV. The significance of these structural differences for lens function and stability remains to be elucidated.

ISSN:0271-3683    

DOI:10.3109/02713688809047020

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

Although the quantity of insoluble lens proteins increases with aging and cataracts, it is unknown whether the quality, such as protein structure, also changes correspondingly. In this study front surface fluorometry was used to study powdered samples of insoluble proteins isolated from young calf and old cow lenses, as well as from young clear and old cataractous human lenses. Tryptophan (Trp) fluorescence shows that there is a difference in protein conformation between young and old bovine samples. The old sample appears to have more open structure. This is demonstrated by a red shift in Trp emission maxima. The water-insoluble fraction shows 3–4 nm shift, while its urea-soluble and urea-insoluble fraction show 1–2nm shift. The unfoldedness found in soluble crystallins is thus retained when they become insoluble. Both young and old human insoluble samples give a long Trp emission wavelength without showing any difference. Another major change that can be measured by fluorescence is the appearance of the 370/440 nm peak in old bovine insoluble powdered samples. Human samples also give this peak, and its position shifts to a longer wavelength in senile lenses.

ISSN:0271-3683    

DOI:10.3109/02713688809047021

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

The involvement of the retina in avian lid suture myopia was investigated by use of formoguanamine (FG), which induces blindness in chicks, characterized by damage to the retinal pigment epithelium and photoreceptor layers. In control chicks reared under a diurnal lighting schedule of 12L/12D, unilateral eyelid suture at 3 days of age induced a typical lid suture myopia response on the operated side (eye enlargement and bulging cornea) by 4 wks. of age. On the other hand, in FG-treated blind chicks also reared under 12L/12D, there was no difference in eye parameters, between sutured and non-sutured eyes. All globe parameters measured were very similar in FG-treated and control non-sutured chicks. Corneal diameter and anterior chamber depth in the eyes of FG-treated chicks were significantly smaller than in non-sutured control eyes.

ISSN:0271-3683    

DOI:10.3109/02713688809047022

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

We examined the effects of several neuroendocrine agents on the intraceliular cyclic AMP level in cultured monkey trabecular meshwork cells. Among the peptide agonists studied, only the vasoactive intestinal peptide elevated the cyclic AMP level. Alpha-melanocyte stimulating hormone, glucagon, and others showed no stimulation. Prostaglandin E1and L-isoproterenol also enhanced the intraceliular cyclic AMP level. Such effects may implicate physiologic roles of these agonists in the trabecular meshwork.

ISSN:0271-3683    

DOI:10.3109/02713688809047023

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor