摘要:

Corneas and tendons dissected from 17-day-old chick embryos were labeled with [35s]methionine in the presence of 0.3 mMα.α'-dipyridyl. The unhydroxylated,35s-labeled proαchains andαchains were isolated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The proαandαchains were then subjected to peptide-map analysis by proteolytic digestion with trypsin andα-chymotrypsin, papain or proteinase K. The peptide-maps derived from cornea and tendon proα1(I) chains are identical. Similar results were obtained from cornea and tendonα1(I) chains. There were differences in the peptide maps derived from cornea and tendon proα2(I) chains. However, no difference was observed inα2(I) chains. These results suggest that cornea and tendon proα1(I) chains are probably identical in primary structures, whereas the cornea proα2(I) chain may be different from the tendon proα2(I) chain within pepsin sensitive regions of the procollagen molecule. The reason for difference in the peptide-maps of proα2(I) chains remain unknown. One of the possible explanations is the variation of posttranslational modification within the propeptides of the proα2(I) chain. However, this hypothesis needs to be further investigated. Nevertheless, the finding that the peptide-maps ofα2(I) chains from tendons and corneas are identical fail to support the two genes hypothesis for proα2(I) chains.

ISSN:0271-3683    

DOI:10.3109/02713688508999972

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Recent reports suggest that forskolin can produce ocular hypotension in laboratory animals and man by enhancing formation of cyclic AMP. This proposed mechanism of action implies that forskolin lowers intraocular pressure (IOP) by activating adenylate cyclase at some postjunctional site. Intra-arterial (i.a.) injections of forskolin (10, 33, 100&333µg) into the cat nictitating membrane (CNM) preparation produced dose-related inhibition of contractions elicited by electrical stimulation of pre-and postganglionic sympathetic neurons. Interestingly, contractions elicited by i.a. norepinephrine were inhibited less than neuronally mediated contractions. Topically applied forskolin (0.5 mg) to the eyes of unilaterally sympathectomized (SX) rabbits and normal rabbits elicited ocular hypotension in the innervated eyes only. Forskolin (0.5 mg, topically) suppressed the rise in IOP induced by water loading in normal rabbits but was significantly less effective in SX rabbits. These results suggest that forskolin lowered IOP in rabbits and suppressed contraction of the electrically-stimulated CNM, in part, by inhibiting sympathetic neuronal function.

ISSN:0271-3683    

DOI:10.3109/02713688508999973

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

The present study demonstrated that less than three days of exposure to low levels of normally cycled ambient illumination are sufficient to cause death to photoreceptor cells in adult pigmented and albino rat. Cyclic light levels as low as 133 and 320 lux were found to destroy photoreceptor cells. A single mydriatic treatment with atropine immediately preceding the three-day exposure was sufficient to permit the effect in pigmented rats. No mydriasis was required for albino rats. When pigmented rats were reared in either 3 lux or 100 lux, it was found that these different light histories did not significantly affect the rats' subsequent susceptibility, during mydriasis, to retinal damage by cyclic illumination.

ISSN:0271-3683    

DOI:10.3109/02713688508999974

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Ahighly sensitive solid phase radioimmunoassay (RIA) was adapted for determination of herpes simplex virus (HSV) specific IgA antibodies in lacrimal fluids. The RIA procedure was applied to examine HSV IgA antibodies in serial samples of lacrimal fluid and in sera from 14 patients with herpes keratitis. HSV-specific IgA antibodies were detected in the lacrimal fluid of the affected eye in 12 of the 14 patients. HSV IgA antibodies were also detected in the lacrimal fluid of the unaffected eye of 7 of these patients in titers lower than those found in the corresponding affected eye. Evidence for local HSV antibody production in lacrimal fluid in herpes keratitis was supported by examination for antibodies to the unrelated measles antigen. Detection of lacrimal fluid HSV IgA antibodies might be a useful adjunct in rapid diagnosis of herpes keratitis. The advantage of characterizing the local immune response as well as viral expression in the affected vs. the unaffected eye in the same individual as a model for understanding the factors leading to subclinical vs. clinical manifestations of recurrent ocular herpes virus infections will be discussed.

ISSN:0271-3683    

DOI:10.3109/02713688508999975

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

The objectives of this study were to investigate the cause of the great difference in the concentration of phospholipids between the cortex and nucleus of the ocular lens and to further investigate the mechanism of cataract induction by the sterol synthesis-inhibitor U18666A. The nucleus of the young rat lens was found to contain less than one-third the concentration (µg/mg lens region, dry wt) of total phospholipid present in the cortex. The sterol to phospholipid molar ratio in the nucleus was more than double that in the cortex. Phosphatidylcholine plus phosphatidyl-ethanolamine were the principal phospholipids in both the lens cortex and nucleus. The activity of phospholipase A2(PLA2), an enzyme important for turnover of cellular phospholipids, was measured in the total water-insoluble fraction from whole lenses and from isolated lens regions by the release of 1-14C-linoleic acid from the number two position of a synthetic phosphatidylcholine. The cortex was found to possess about 75% of the total PLA2activity in the lens. Most of the remaining activity was in the nucleus. The low concentration of phospholipid in the lens nucleus could be due to breakdown of phosphoglycerides by PLA2in the cortex as equatorial fiber cells shift toward the nucleus with aging.The cataract induced in rats by the sterol synthesis inhibitor U18666A was found to involve a major loss of total sterol from the lens cortex and almost total substitution of desmosterol for the cholesterol remaining in this region. By comparison, nuclear sterols were little affected by drug treatment and cataract development. Also, U18666A produced no major changes in the concentration or composition of phospholipids in the lens or in the activity of PLA2. The selective loss of sterol from the cortex could help to explain our recent finding that gap junctions, cholesterol rich membrane components, were completely lost from the plasma membrane of cortical fiber cells in cataractous rat lenses.

ISSN:0271-3683    

DOI:10.3109/02713688508999976

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Detailed measurements have been made of the pre-retinal partial pressure of oxygen (PO2) in the cat eye to determine the effect of the local geometry of the retinal circulation on vitreal PO2values. Measurements were made with oxygen sensitive microlectrodes for two ventilation conditions: air and 100% O2breathing. PO2gradients, which may extend as far as 800µm from the internal limiting membrane, have been shown to exist in the vicinity of retinal arteries. Close to a retinal vein there is either a very shallow PO2gradient or none at all. Coarse vitreal PO2profiles which were measured out to the“mid vitreous”show that the gradients are very shallow to within 1 mm of the retina. The close agreement between“mid vitreous”PO2and retinal venous PO2implies that the retinal venous PO2sets the PO2value of the main bulk of the vitreous. Absolute PO2values indicate that the retinal arterial walls offer easy diffusion for oxygen, and that at 100% O2breathing almost all the oxygen offloaded from the retinal circulation is from dissolved oxygen. Alterations in the physiological condition of the eye such as those due to changes in the ventilation gas, blood pressure or intraocular pressure may cause relative movement between the microelectrode and the retina. This movement can lead to apparent changes in vitreal PO2when it occurs in a region in which substantial PO2gradients exist.

ISSN:0271-3683    

DOI:10.3109/02713688508999977

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Amphotericin B, 5-flucytosine (5-FC), and ketoconazole levels were estimated in vitreous and aqueous samples taken from four patients undergoing therapeutic vitrectomy for fungal endophthalmitis. The levels of amphotericin B in the vitreous of three patients were low (.04–.17µg/ml). However, 5-FC was present in a concentration of 22.2µg/ml in one patient. In another case the aqueous level of ketoconazole was 0.35µg/ml. The vitreous in the same patient contained 0.71µg/ml of the drug.

ISSN:0271-3683    

DOI:10.3109/02713688508999978

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Detergents were administered intra-arterially to isolated arterially perfused eyes of rabbits and cats. Tween 80, Triton X-100, digitonin and sodium dodecyl sulphate (SDS) constricted uveal vessels and raised intraocular pressure (IOP) except for SDS which lowered IOP. Digitonin, a type B detergent was more active than three other detergents of type A. None of the four detergents did affect pupil size. After preconstriction with epinephrine low concentrations of nonionic detergents dilated uveal vessels but the fall in IOP by epinephrine was not affected; higher doses raised IOP. After preconstriction by eserine + Ach there were no effects of detergents on uveal flow and IOP. Mepacrine decreased the ocular effects of detergents suggesting that at least part of the effects from detergents is due to liberation of phospholipids.

ISSN:0271-3683    

DOI:10.3109/02713688508999979

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Na+-K+ATPase activity was measured in the capsule-epithelium and decapsulated frog and bovine lens. The decapsulated lens contained approximately 20% of the whole lens activity in the frog and 30% in the bovine. These values were measured from the aqueous homogenate of the entire decapsulated lens, an approach which may have underestimated the activity by diluting the ouabain-sensitive component in the preparation. Subsequent determinations were done on separate portions of superficial (2 to 3 mm) anterior-equatorial, and posterior bovine cortex. The activities per gram of tissue were enriched with respect to the values for the entire decapsulated bovine lens. These activities were further enriched by a sucrose density gradient centrifugation. The anterior-equatorial cortical segment contained 1.6 times the activity found in the capsule-epithelium. The posterior cortex had a much smaller but statistically significant level of Na+-K+ATPase. It is unlikely that the observed asymmetry of the anterior-equatorial segment with the posterior cortex is exclusively due to epithelial contamination for the result would require the adherence of 62% of the epithelium. Scanning electron micrographs of 6 decapsulated bovine lenses indicated an average contamination of about 9%. This asymmetry may have a physiological role in assisting the pump mechanism of the epithelium.

ISSN:0271-3683    

DOI:10.3109/02713688508999980

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

The survival time of perfused endothelium is doubled in presence of the free radical scavengers superoxide dismutase and catalase.

ISSN:0271-3683    

DOI:10.3109/02713688508999981

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor