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N Buyukmihci

Publications and source records attributed to N Buyukmihci.

At least 19 recordsLinked to original sources
PubMed1985

Asymmetry of retinal lesions in experimental scrapie after intracerebral inoculation of hamsters.

Hamsters injected into the right cerebral hemisphere with the scrapie agent developed retinal lesions to a greater extent in the contralateral than in the ipsilateral eye. This asymmetry was evident during the incubation period as well as during the clinical encephalopathy. The results explain much of the variation in the degree of retinal disease seen earlier at specific times after inoculation. Moreover, they strengthen the hypothesis that scrapie spreads via neurons.

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PubMed1985

Retinal degeneration in experimental scrapie after intraperitoneal or subcutaneous inoculation of hamsters.

Hamsters injected intraperitoneally or subcutaneously with the scrapie agent developed photoreceptor degeneration. The degree of degeneration did not correlate well with infectivity titers of retinal tissue or stage of clinical encephalopathy, and was not as great as seen in intracerebrally injected animals. We conclude that retinal degeneration is universal in hamsters experimentally inoculated with the scrapie agent regardless of the route of inoculation.

Animals↗
PubMed1983

Neural pathogenesis of experimental scrapie after intraocular inoculation of hamsters.

Hamsters were inoculated intravitreally with the scrapie agent. All animals developed scrapie and retinal degeneration typical of scrapie. The retinal degeneration was greater in the inoculated eyes than in the uninoculated eyes. Replication of the scrapie agent was rapid in the inoculated eye. Infectivity then spread slowly down the ipsilateral optic nerve to the brain. The replication in the brain paralleled that in the retina of the uninoculated eye. The results support a neural spread of scrapie.

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PubMed1983

Cyclic nucleotides in hamster retina.

The concentrations of cyclic 3':5'-adenosine monophosphate (cyclic AMP) and cyclic 3':5'-guanosine monophosphate (cyclic GMP) were determined in white light- and dim red light-adapted golden Syrian hamster retinas. Retinas from animals in dim red light had cyclic AMP concentrations of 9.29 +/- 2.94 pmol/mg of protein and cyclic GMP concentrations of 110.62 +/- 32.98 pmol/mg of protein. After white light adaptation, retinal cyclic AMP and cyclic GMP concentrations were reduced to 74% and 45% of the previous values, respectively. In another experiment with white light-adapted animals, the sex or method of immobilization of the animals (cervical dislocation vs sodium pentobarbital) had no significant effect on cyclic nucleotide values.

Animals↗
PubMed1982

Photoreceptor degeneration in a family of cats.

Blindness developed at an early age in 2 generations of cats. Findings included abnormal pupillary responses to light, tapetal hyperreflectivity, retinal vascular attenuation, and virtually extinct electroretinograms. Histologic and ultrastructural abnormalities were found only in photoreceptors. There were poor inner and outer segment development and reduction in visual cell nuclei, with concomitant narrowing of the outer plexiform layer early in the postnatal period. Eventually, there was complete loss of the photoreceptor layer. The clinical and microscopic findings suggested this retinal disease may be a heritable rod-cone dysplasia.

Animals↗
PubMed1982

Retinal degeneration during clinical scrapie encephalopathy in hamsters.

Weanling hamsters were inoculated intracerebrally with brain suspensions from normal or scrapie-infected hamsters. A third group of uninoculated animal was fed cuprizone. Histologic and electron microscopic examination of the neural retinas and retinal pigment epithelium was done. At 50 days postinoculation, when scrapie-infected animals began to show clinical signs of encephalopathy, there was a variable degree of photoreceptor degeneration. By the time animals were moribund, at 74 days postinoculation, photoreceptor degeneration was severe, as demonstrated by loss of most outer and inner segments and cell bodies. The outer plexiform, inner nuclear, and inner plexiform layers were reduced in thickness. Some retinal pigment epithelial cells contained lipoidal inclusions. The neural retinas and retinal pigment epithelium of noninfected and cuprizone-treated animals were normal. We have previously shown that the scrapie agent accumulates in the retina; that together with our present work, we conclude that the scrapie agent is the cause of photoreceptor degeneration in experimentally inoculated hamsters.

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PubMed1982

Ocular lesions of blastomycosis in the dog.

Twenty-one dogs with ocular disease and blastomycosis were studied clinically. The most common ocular lesion was uveitis. Other findings included retinal separation, panophthalmitis, and glaucoma. The results of the study indicated that when uveitis is found in dogs in central United States, east of the Mississippi River, blastomycosis should be a diagnostic consideration. When the uveitis was associated with lung, lymph node, skin, bone, or testicular lesions, the likelihood of blastomycosis was greater.

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PubMed1982

Photoreceptor degeneration preceding clinical scrapie encephalopathy in hamsters.

Hamsters experimentally inoculated with scrapie had histologic and ultrastructural changes in their retinas before clinical signs of central nervous system disease became evident at 50 days postinoculation. The retinal changes were limited to the photoreceptors and began with degenerative changes in the inner segments as early as 8 days postinoculation. As the inner segment lesions became more prominent, associated degenerative changes within outer segments were seen (38 days postinoculation). An influx of macrophages was associated with increasing degenerative changes; these cells engulfed cellular debris did not appear to contribute directly to the degenerative process. Retinas having the greatest damage to the inner segment area also had moderate reduction in outer nuclear layer density and outer segment length, and in numbers of outer segments. All of the retinal changes described occurred almost exclusively in the central to mid-region of retina with relative sparing of peripheral retina.

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PubMed1982

Histology and fine structure of the hamster retinal pigment epithelium.

The retinal pigment epithelium of normal adult golden Syrian hamsters was examined by light and electron microscopy, using conventional and enzyme histochemical techniques. Hamster retinal pigment epithelium was composed of a single layer of cuboidal cells that had marked infolding of the basal cell wall and numerous microvillous processes extending from the apical surface. Melanin content varied within each specimen and there appeared to be incomplete or aberrant development of many melanin granules. Many incompletely melanized granules showed acid phosphate activity. There were the usual cell organelles, and Golgi complexes. Large phagosomes increased in number in the morning hours. Autophagic vacuoles and small lipid droplets were commonly seen. Occasional basal bodies, cilia, and root filaments were found. In two specimens, a curious intranuclear paracrystalline structure was observed.

Animals↗
PubMed1982

Pathogenesis of progressive rod-cone degeneration in miniature poodles.

Visual cell pathologic changes and outer segment renewal were investigated in miniature poodles with progressive rod-cone degeneration. Early in this disease, visual cells in the posterior pole and equatorial regions show outer segment lamellar disorientation and vesicular profiles. Visual cells are normal in the periphery. Outer segment renewal determined after intravitreal injection of 3H-leucine was abnormally slower in affected animals than in controls. This renewal abnormality was similar in structurally normal and diseased photoreceptors, suggesting that the renewal defect is the earliest recognizable abnormality in the disease. The pigment epithelium was normal; the presence and density of pigment did not appear to affect the extent and severity of the disease or modify the abnormal renewal rate. As the disease progressed, photoreceptor outer segments were lost, and the remaining diminutive photoreceptors accumulated label in the inner segment and perinuclear zones. Sodium dodecyl sulfate gel electrophoresis of crude rod outer segment preparations showed no differences in opsin synthesis between normal and affected retinas early in the disease, but opsin synthesis decreased in the late stage of the disease.

Animals↗
PubMed1981

Canine blastomycosis: a review of 47 clinical cases.

In a limited retrospective survey, canine blastomycosis was found to be a disease affecting predominantly young, male dogs of the larger breeds. Clinical signs usually related to weight loss and to respiratory and ocular problems. The agar-gel immunodiffusion test was helpful in establishing a diagnosis. The diagnosis was confirmed by microscopic evaluation of aspiration or excision biopsies. Of 22 dogs treated with amphotericin B, 18 were clinically normal 6 months after initiation of therapy.

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