Morphologic characteristics of retinal degeneration induced by a single systemic administration of N-methyl-N-nitrosourea (MNU) in mice was investigated. The aim was to characterize the MNU-induced retinal lesions in mice and compare them with human retinitis pigmentosa. A dose of 60 mg/kg body weight MNU, injected intraperitoneally into male and female C57BL mice, evoked progressive retinal degeneration in all treated mice, while control mice remained normal. An early change was photoreceptor apoptosis followed by infiltration of macrophages and swelling of the pigment epithelial cells with phagosomal inclusions for apoptotic photoreceptor cell removal. Loss of the majority of photoreceptor cells occurred within a week. Then, Feulgen-positive corpuscles, indicative of an aggregation of degenerative photoreceptor elements, vitread the outer limiting membrane were surrounded by Müller cell processes, and the duplication of the pigment epithelial cells sclerad the outer limiting membrane were seen 2 and 3 weeks after the treatment. Finally, the Feulgen-positive corpuscles disappeared and Müller cell processes were in direct contact with the continuous lining of the single layer of pigment epithelial cells. As in retinitis pigmentosa in humans, the primary event was loss of photoreceptor cells by apoptosis, but the migration of the pigment epithelial cells within the retina was not seen in the present model.
Although primary Sjogren's syndrome (pSS) is an autoimmune exocrinopathy, the involvement of liver has been reported. Because no study focusing on autoimmune hepatitis (AIH) in pSS has been published, the purpose of the present study was to perform a clinical and histological examination of the liver, focusing on AIH, in 17 pSS patients. The patients had liver enzyme abnormalities without hepatitis virus infection. In all cases, biopsied livers were examined, and in 10 cases biopsied labial salivary glands were also examined histologically. Based on the authors' diagnostic criteria for AIH in pSS, the liver diseases consisted of AIH (eight cases, 47%), primary biliary cirrhosis (PBC; six cases, 35%), non-specified chronic hepatitis (two cases, 12%) and acute hepatitis (one case, 6%). Lymphoplasmacytic infiltrate, with predominancy of CD3(+) T cells, was noted in both the liver and salivary glands in the patients with AIH. The patients with AIH with severe interface hepatitis had a good response to immunosuppressive therapy. The comparison of liver histology between the PBC with pSS group and the PBC without pSS group showed that the incidence of lymphoid non-suppurative cholangitis was higher in PBC with pSS. In conclusion, the present study offers new information on the relatively common occurrence, diagnostic criteria and treatment effects of AIH in pSS.
The immunohistochemical features of 24 retinoblastoma specimens from 22 patients, 15 with unilateral and 7 with bilateral disease, were examined by the labelled streptavidin biotin (LSAB) method and compared with those of specimens from the remaining morphologically normal retina. In the normal retina, S-100 protein, glial fibrillary acidic protein (GFAP) and vimentin were detected in astrocytes and/or Müller cells. Neurofilament protein was seen in axons of the ganglion cells, synaptophysin was present in both plexiform layers, bcl-2 oncoprotein was seen in ganglion cells and bipolar cells, and neuron-specific enolase (NSE) was detected in ganglion cells, bipolar cells and photoreceptor cells and in their cell processes. While retinoblastoma (Rb) protein expression was noted in ganglion cells, bipolar cells, and some photoreceptor cells, p53 protein was not expressed at all. In all retinoblastomas, strong NSE expression and weak bcl-2 expression was observed in almost all tumour cells and synaptophysin was localized in rosette-forming cells, while tumour cells were devoid of S-100, GFAP, vimentin and neurofilament protein. These findings support the view that retinoblastomas are composed of neuron-committed cells. In addition, no Rb protein expression was detected in retinoblastomas, whereas p53 expression was found in 18 cases (75%).
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