摘要:

Specimens of a cornea, conjunctiva and iris were removed at the time of penetrating keratoplasty in a case of nephropathic cystinosis. Immunohistochemical studies revealed the presence of class II antigens on the stromal keratocytes of the cornea and the vascular endothelial cells, pericytes and fibroblasts of the conjunctiva. In addition, there were thinning and focal breaks in Bowman's membrane. Both of these findings may have contributed to the severe photophobia and blepharospasm seen in patients with longstanding cystinosis.

ISSN:0271-3683    

DOI:10.3109/02713688709025222

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Little information is available on drug metabolizing enzymes in ocular tissues. We investigated the presence of various cytochrome P450 isozymes by measuring different drug metabolizing enzymes, i.e., aryl hydrocarbon hydroxylase, 7 ethoxycoumarin-o-deethylase and benzphetamine demethylase activities in ciliary body, corneal epithelium and endothelium, retina and retinal pigment epithelium. Our results demonstrate that the ciliary body and the retinal pigment epithelium possess the highest activities of cytochrome P450-dependent monooxygenases in the eye. The highest activity of drug metabolizing enzymes is accompanied by high activity of NADPH cytochrome P450 (C) reductase, an integral component of this enzyme system. Heme oxygenase, a key enzyme for the regulation of heme availability to hemoproteins such as cytochrome P450 also demonstrate high activity in these two ocular tissues. Although the corneal epithelium has a lower activity of drug metabolizing enzymes, it possesses the highest activity of cytochrome P450 species capable of metabolizing arachidonic acid to biologically active compounds, whereas the other ocular tissues possess cyclooxygenase as the main microsomal enzyme that metabolizes arachidonic acid. Whether the observed catalytic activities of drug metabolizing enzymes seen in ocular tissues are associated with major or minor forms of cytochrome P450 is not yet know. However, the specialized location of cytochrome P450 isozymes in ocular tissues suggests a physiological function related to activation of endogenous compounds such as arachidonic acid, in addition to detoxification of drugs.

ISSN:0271-3683    

DOI:10.3109/02713688709025223

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Psychophysical spectral sensitivities were obtained from aphakic human subjects in the photopic range. The foveal spectrum has a primary peak near 550 nm and a secondary peak about 0.7 log units lower around 380 nm. Off fovea, beyond most of the macular pigment, the curve is quite broad. While the peak is in the green, the gradual drop-off to 330 nm varies over only half a log unit. The two curves were compared in order to obtain an estimate of the macular pigments' spectrum. The macular pigments' curve has peaks at 460 and 490 nm as expected. It is broad and extends into the UV. These data suggest that the ocular media, including the macular pigments, have a profound effect on the spectral sensitivity.

ISSN:0271-3683    

DOI:10.3109/02713688709025224

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Recent work suggests that chemically and structurally distinct domains of the Interphotoreceptor matrix (“cone matrix sheaths”) surround cone photoreceptor outer segments and ellipsoids. This specific regional ization of at least some molecular constituents of the Interphotoreceptor matrix may establish a unique cone-associated microenvironment. Previous histochemical and biochemical investigations have shown that a variety of g lycosaminoglycans are components of the Interphotoreceptor matrix and that the structural Integrity of cone sheaths is slightly disrupted by glycosaminoglycan-degrading enzymes. In order to pursue the possibility that specific glycosaminoglycan species establish cone matrix sheath domains, monoclonal antibodies directed against various unsaturated glycosaminoglycans have been screened on sections of primate retina. The results of these studies identify condoling 6-sulfate glycosaminogiycan as a specific component of primate cone matrix sheaths.

ISSN:0271-3683    

DOI:10.3109/02713688709025225

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor