摘要:

Sonication of bovineα-crystallin increases its molecular mass from around 770 kDa to in excess of 2,300 kDa. Exposure to 2M urea or 0.1 M glycine pH 7, did not affect the size of the sonicated protein, indicating that it did not consist of dimers and higher polymers of the original molecule. Sonication of a mixture ofα-crystallins labelled on the A chain sulphydryl group with either an aminonaphthalene or a fluorescein chromophore, generated a product exhibiting substantial energy transfer. The average distance between the probes was calculated to be 5nm. These observations suggest that sonication has generated a new quaternary structure, incorporating subunits from two or more differentα-crystallin molecules.No significant differences were observed in the microenvironments of tryptophan residues although those in the sonicated protein could be more easily exposed by controlled denaturation with urea. A small decrease was observed in the quenchability of a fluorescent probe attached to the sulphydryl group and a small increase in the uptake of an hydrophobic probe. These data suggest that sonication may have altered the conformation of the subunits at, or near the surface of the protein.

ISSN:0271-3683    

DOI:10.3109/02713689109001738

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

Acute anterior uveitis in response to the administration of systemic gram-negative endotoxin was studied in humans. The blood-aqueous barrier was evaluated in eight normal human subjects at 8 or 24 hours after systemic administration of purified gram-negative endotoxin. No significant changes in the blood-aqueous barrier were found, as evaluated by permeability to fluorescein, number of aqueous cells, flare, or intraocular pressure, despite profound endotoxin-induced cardiac, pulmonary, and circulatory effects. Gram-negative endotoxin does not appear to affect the human blood-aqueous barrier in doses that can safely be given to humans.

ISSN:0271-3683    

DOI:10.3109/02713689109001739

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

Proton nuclear magnetic resonance (nmr) spectra of rabbit ocular tissue homogenates (corneal epithelium, conjunctiva and iris ciliary body) and aqueous humor have been recorded for the first time by incorporation of a spin-spin relaxation reagent and use of the CPMG pulse sequence. A number of endogenous species such as lactate, glucose, alanine and valine have been observed in these ocular homogenates and significant differences have been noted in the distribution of these small molecules in the ocular tissues studied. This technique has been used to study the hydrolysis of acetylcholine by ocular esterases in the iris ciliary body.

ISSN:0271-3683    

DOI:10.3109/02713689109001740

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

Albino rats were given intraperitoneal desferrioxamine before exposure to intense fluorescent light. Morphometric and morphologic studies of the retina indicated that there was better preservation of photoreceptor nuclei and fewer subretinal macrophages in rats treated with desferrioxamine than in the control rats. The results of the study imply that iron and hydroxyl radicals may be important mediators in photic retinal injury.

ISSN:0271-3683    

DOI:10.3109/02713689109001741

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

The physiology and anatomy of the cornea of the New Zealand white rabbit were studied from birth to young adulthood (3 months). The main objective of the study was to follow the ontogeny of the corneal endothelium and correlate its maturation with the establishment of stromal transparency. With maturity, central corneal thickness increases as do corneal diameter and surface area. Endothelial morphology undergoes marked changes including an increase in cell hexagonality and cell surface area, along with a decrease in cell density and coefficient of variation of cell area. Corneal hydration decreases from a high value at birth to the adult level by 20 days after birth, the time of the onset of stromal transparency. By transmission electron microscopy, corneas of newborn rabbits exhibit an endothelium of irregular cell height with some overlap at the bases of adjacent cells. Apical junctions are incomplete in the neonates. With time the endothelium thins and cells becomes more regular in height, overlap of adjacent cells diminishes, and apical junctions develop. Des-cemet's membrane is thin in newborns and thickens and becomes more homogenous in appearance with maturation. The abundance of Na/K ATPase pump sites per endothelial cell, as determined by H-ouabain binding, increases progressively with age even after the establishment of corneal transparency at 20 days. Scatchard and LIGAND analyses of3H-ouabain binding data indicate that there is a progressive increase in Bmaxwith no change in the KDfrom 7 days to 3 months.

ISSN:0271-3683    

DOI:10.3109/02713689109001742

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

The aqueous and vitreous humors are normally avascular and may be sites of altered inflammatory responses. Inhibitors of endothelial cell and lymphocyte growth as well as of angiogenesis have been isolated from vitreous and an inhibitor of lymphocyte mitogenesis has been found in aqueous. Data are presented here indicating that aqueous humor also inhibits endothelial cell growth. In addition, neutralizing antibodies against TGFK block the effects of materials isolated from these tissues on endothelial cell and lymphocyte growth. Similar data were obtained from aorta, another normally avascular site. These observations suggest that the avascularity and altered inflammatory responses in these sites may be regulated in part by TGFK.

ISSN:0271-3683    

DOI:10.3109/02713689109001743

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

In chicks, the application of optical devices that blur vision results in eye enlargement and ametropia. The research presented here investigated changes in intraocular pressure (IOP), specifically intravitreal pressure, that occur with eye enlargement induced by this means. Plastic goggles (domes) were glued over one eye in 25 domestic chicks. Plastic rings were glued around one eye in 25 control chicks to control for the mechanical effects of the treatment but which left their vision undisturbed. Following two weeks of treatment, domes and rings were removed and IOP was measured. Mean IOP of the domed eyes was 1.14 mm Hg lower than that of control eyes, a difference that was not statistically significant. The eyes of an additional group of 20 chicks that experienced similar treatments were refracted; these refractions revealed that the dome-treated eyes had a mean refractive state that was 7.98 D myopic relative to the ring controls, which was statistically significant. The results indicate that IOP does not change significantly in chicks with experimental eye enlargement induced by retinal-image degradation.

ISSN:0271-3683    

DOI:10.3109/02713689109001744

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

The development of an onchocercal chorioretinopathy from the first detectable signs to a full blown oncho fundus is not fully understood. We investigated the intraocular humoral immune response against Onchocerca volvulus, human S-antigen, IRBP and crude retinal extract (using an ELISA) by examining paired aqueous humour and serum samples obtained from onchocerciasis patients (without [n = 10] and with ocular symptoms [n = 8]) and endemic controls [n = 14] from Sierra Leone (West Africa).A local intraocular anti-retinal IgG antibody production could not be demonstrated in onchocerciasis patients, whether they had ocular symptoms or not. A significantly higher level of 0. volvulus antibodies and IgG was measured in the aqueous of onchocerciasis patients with ocular involvement, as compared to patients without ocular symptoms (Mann-Whitney ranksum test; p<0.001 and p<0.02 respectively).Since lnterleukin-6 (IL-6) plays an essential role in the differentation of B cells into immunoglobulin producing plasma cells, we therefore measured this cytokine in paired aqueous and serum samples. Elevated IL-6 levels were found in the aqueous of two out of eight onchocerciasis patients tested.In view of these findings it seems improbable that retinal autoimmunity is a major factor in the pathogenesis of onchocercal chorioretinopathy. The high intraocular levels of antibodies against the parasite suggest a direct involvement of the parasite in the pathogenesis of onchocercal chorioretinopathy.

ISSN:0271-3683    

DOI:10.3109/02713689109001745

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

The effect of UV-B radiation on the crystalline lens was examined by subjecting bovine lenses in culture to varying low exposures at 300 nm. Lens optical quality was monitored on a long-term basis (to 1000 hrs.) with an automated scanning laser system that recorded both change in relative scatter and focal length across each lens. Data were collected for 20 lens positions at each scan. Radiant exposure levels consisted of 0.5, 0.25, 0.125, 0.06 and 0.03 Jem−2. Twenty irradiated lenses were compared to twelve untreated controls.All of the irradiated lenses showed changes in scatter and focal length relative to the controls. Most (about 75%) of the treated lenses showed significant increases in scatter (200–400%) and focal length (10-20%) at 40 to 60 hours after exposure. A similar time frame for lens damage was noted by visual inspection. Exposure to UV-B at the above doses did not affect culture longevity.

ISSN:0271-3683    

DOI:10.3109/02713689109001746

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor