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C Qin

Publications and source records attributed to C Qin.

50 records · Page 3Linked to original sources
PubMed1996

A comparison of antioxidant enzyme activities in organ-cultured rhesus monkey lenses following peroxide challenge.

PURPOSE: To analyze the activities of catalase, glutathione peroxidase and superoxide dismutase, three enzymes involved in the detoxification of reactive oxygen species in organ-cultured Rhesus monkey lenses. METHODS: Lenses freshly obtained from Rhesus monkeys were incubated at 37 degrees C for 2 h and assessed for lens integrity. Lenses were then oxidatively stressed by exposure to a bolus of hydrogen peroxide. The three enzyme activities were assayed 2, 4 and 24 h after exposure to the peroxide challenge. RESULTS: Freshly dissected lenses placed in organ culture exhibited a 20% decrease in catalase activity within 2 h. During the course of a 24 h incubation, catalase activity continued to decrease to a level 58% below that of freshly dissected monkey lenses. In contrast, the activity levels of both glutathione peroxidase and superoxide dismutase increased dramatically within the first 2 h of organ culture, with superoxide dismutase being most affected. Although glutathione peroxidase activity declined with incubation time, its level at the end of 24 h was still 36% greater than that of the fresh lenses. Superoxide dismutase activity remained elevated throughout the 24 h incubation period. The addition of a bolus of 0.25mM H2O2 to monkey lenses in culture had no effect on catalase activity. Two h after the peroxide insult, glutathione peroxidase activity decreased in comparison to control levels while the activity of superoxide dismutase increased by 43%. After 24 h, superoxide dismutase activity returned to values equivalent to the controls. In lenses challenged with 0.50mM H2O2, catalase and glutathione peroxidase activities decreased at 2 h, while superoxide dismutase activity increased 67% above control levels. At subsequent timepoints, catalase activity increased and reached control levels. In contrast, glutathione peroxidase activity continued to decrease with time eventually reaching fresh lens levels. Superoxide dismutase activity levels remained elevated and were equivalent to control values at 24 h. CONCLUSIONS: The data indicate that placement of monkey lenses into an organ culture system represents an environmental change sufficient to cause a response in antioxidant enzyme levels. The addition of H2O2 to this environment caused only superoxide dismutase to be stimulated above control lens levels.

Animals↗
PubMed1995

Calcium cataract: a model for optical anisotropy fluctuations.

Young rat lenses were incubated in organ culture media enriched with 20 mM calcium. Lenses in the calcium rich medium developed cataracts and were characterized by the absence of vimentin in the urea soluble protein fractions. Sections from the same lenses were studied by polarized light scattering. The I+/Iparallel scattering intensity ratios were higher from the lenses in calcium-rich media than from the control lenses. This indicated an increase in the optical anisotropy fluctuations during cataractogenesis. The turbidity that developed due to these fluctuations was caused partly by the disappearance of vimentin and which in turn caused the enhancement of birefringence of the lens.

Animals↗
PubMed1995

Effect of smoke condensate on the physiological integrity and morphology of organ cultured rat lenses.

Smoke, either from cigarette smoking or from burning of organic fuels, has been proposed to be a major environmental risk factor for a variety of human diseases. Recently, smoke was implicated in cataract, an eye lens opacification which is a major cause of blindness. We have undertaken a study to investigate the effect of wood smoke condensate on the physiological integrity and morphology of organ cultured lenses. Lenses in organ culture are metabolically active and have functional defense systems, thus they provide an appropriate model for studying effects of smoke condensate. Our present study indicates that metabolites of wood smoke condensate accumulate in the lens. The ability of the lenses to accumulate rubidium-86 (mimic of potassium) and choline from the medium is compromised by exposure to smoke condensate. Rubidium efflux studies suggest that the damage is primarily at the uptake level and does not involve an overall increase in membrane permeability. Protein leakage experiments corroborate this suggestion. Histological data show distinct morphological changes such as hyperplasia, hypertrophy and multilayering of epithelial cells.

Animals↗
PubMed1994

Residual EDTA bound by lens crystallins accounts for their reported resistance to copper-catalyzed oxidative damage.

It was recently reported that the structural proteins of the lens, the crystallins, possess unusual resistance to oxidative damage from a copper-catalyzed Fenton system. Data presented here demonstrate that this phenomenon is specific to copper-catalyzed systems and is not observed when iron is the metal catalyst. Further investigation has revealed that the apparent resistance to copper-catalyzed oxidation results from the presence of residual EDTA associated with the proteins. EDTA chelates the copper, inactivating it as a redox catalyst. This binding of EDTA to crystallins (or other proteins) occurs when the proteins present in EDTA-containing buffers are dialyzed directly against deionized water. Partial characterization of the association between EDTA and proteins is presented and its potential significance as a confounding factor in studies of the effects of metal-catalyzed oxidation on proteins is discussed.

Alcohol Dehydrogenase↗
PubMed1994

The integrity of mammalian lenses in organ culture.

A method to quantitate protein leakage was developed to assess the integrity of mammalian lenses in organ culture. Protein leakage into the culture medium was found to be a strong indicator of lens integrity. Rat lens incubation medium that contained more than 14 micrograms protein per lens after 1 hr was indicative of lens damage. Damaged lenses almost always exhibited lens opacities within 24 hr. However, on occasion, a lens predicted by this method to be damaged would maintain clarity at the 24 hr timepoint. In these instances, damage was confirmed by the inability of the lens to accumulate [3H]choline and 86RbCl from the medium at levels equivalent to undamaged lenses. When the protein concentration of the incubation medium was greater than 14 micrograms per lens, there was a concomitant impairment of lens transport function. This indicates that quantitation of protein leakage is a better predictive measure of lens viability than is lens clarity. Rat lenses were oxidatively stressed by exposure to a bolus of hydrogen peroxide (final concentration, 1 mM). Within 24 hr, the lenses exhibited cortical opacities and the protein concentration of the medium was significantly increased over the controls. Western and slot blot analyses of the media revealed the presence of lens crystallins. beta B2-crystallin was the major component leaking from damaged lenses. The incubation media from control lenses exhibited no protein leakage. Comparative studies with Rhesus monkey lenses yielded similar data.

Animals↗
PubMed1994

Histogenesis and possible mechanism of chondroid changes in mixed tumour of the skin: immunohistochemical evaluation of bone morphogenetic protein, glycosaminoglycans, keratin, vimentin and neuronal markers.

The distribution of immunoreactivity of bone morphogenetic protein (BMP), the glycosaminoglycans chondroitin 4-sulphate (C4SPG), chondroitin 6-sulphate (C6SPG), dermatan sulphate (DSPG) and keratan sulphate proteoglycans (KSPG), cytokeratin (K8.12), vimentin, glial fibrillary acidic protein (GFAP), actin, desmin, S-100 protein and neuron-specific enolase (NSE) in mixed tumour of the skin was investigated using immunohistochemical methods using monoclonal (MoAb) and polyclonal antibodies (PoAb). A strong BMP immunoreactivity was found characteristically in outer tumour cells of tubuloductal structures and modified myoepithelial cells. Modified myoepithelial cells and chondroidally changed cells showed positive immunoreactivity for C4SPG, C6SPG and DSPG; and KSPG was more pronounced in the modified myoepithelial cells. Vimentin, S-100 protein, GFAP and NSE, but not actin and desmin, were distribute in the outer tumour cells and modified myoepithelial cells in chondroidally changed tissue. Two factors show that chondrogenesis in mixed tumour of the skin is associated with the modified myoepithelial cells through the activity of BMP and biosynthesis of glycosaminoglycans as matrix substance. First, outer or basal tumour cells in mixed tumour of the skin is characterized by the presence of positive immunoreactivity for BMP, KSPG, vimentin, cytokeratin K8.12, S-100 protein, GFAP and NSE, and second, there is a matrix of chondroidally changed tissue containing the reaction products of C4SPG, C6SPG, DSPF and KSPG.

Actins↗
PubMed1994

Comparison of proliferating cell nuclear antigen index in benign and malignant salivary pleomorphic adenoma.

The expression of proliferating cell nuclear antigen (PCNA) was studied in benign and malignant pleomorphic adenomas by using monoclonal antibody to PCNA. Carcinoma in pleomorphic adenoma (n = 8), cell-rich variant (n = 6) and typical pleomorphic adenoma (n = 6) were selected in this study. The PCNA index in carcinoma in pleomorphic adenoma showed a higher index of nuclear staining (mean 22.9%, S.D. 6.2) than in typical pleomorphic adenoma (mean 6.9%, S.D. 3.4) or a cell-rich variant of pleomorphic adenoma (mean 8.8%, S.D. 3.3). A significant difference in PCNA index was found between benign and malignant pleomorphic adenoma (P < 0.05). The present study suggests that PCNA index significantly differs between pleomorphic adenoma and carcinoma in pleomorphic adenoma, but in the prediction of malignant transformation potential it should be combined with routine histopathological examination.

Adenoma, Pleomorphic↗
PubMed1994

Biomaterials with permanent hydrophilic surfaces and low protein adsorption properties.

Low protein adsorbing polymer films have been prepared with which to fabricate intravenous containers, designed for compatibility with low concentrations of protein drugs. The material is economically manufactured utilizing physical melt blending of water-soluble surface-modifying polymers (PEO, PEOX, PVA, and PNVP) with a base polymer (EVA, PP, PETG, PMMA, SB, and nylon). Permanency of the hydrophilic surfaces so generated was confirmed by surface contact angle experiments and total organic carbon leachables analysis of the aqueous contacting solutions. Binding of IgG, albumin and insulin was studied. A sixfold reduction of protein adsorption was obtained by adding 5% PVA13K to EVA, for IgG at a bulk concentration of 2.5 ppm. Surface bound protein measured by micro-BCA colorimetry, agreed with the solution protein lost, as determined by the Fluoraldehyde procedure. Imaging of the protein exposed plastic surfaces by silver enhanced protein conjugated gold staining agreed with the quantitative assay determinations.

Adsorption↗
PubMed1994

Destructive processes of salivary gland parenchyma and development of epimyoepithelial islands assessed by immunohistochemistry.

Thirteen salivary gland lesions showing destructive features and development of epimyoepithelial islands were studied using a panel of monoclonal antibodies to B cell (Dako, CD20 L26), T cell (UCHL1), macrophage histiocyte MH cell (Dako, MAC387), cytokeratin PKK1, KL1, K8.12, actin, vimentin and Von Willebrand factor (v WF). B cells were distributed closely in some limited areas and T cells were scattered throughout the lesion. MH cells were located particularly in the periductal tissue as well as in ducts and acini. Actin staining was positive in myoepithelium around acini but was negative or weak around degenerative acini. Endothelial cells of blood vessels stained strongly with v WF. Cytokeratin KL1 and K8.12 were positive in duct cells of the unaffected area while in the degenerative region they were negative or weak. K8.12 was positive in epimyoepithelial islands, indicating that the epimyoepithelial cells in lymphoepithelial lesions may originate from duct basal cells.

Adult↗
PubMed1993

Immunoreactivity of proliferating cell nuclear antigen in salivary gland tumours: an assessment of growth potential.

Immunoreactivity of proliferating cell nuclear antigen (PCNA) was assessed to evaluate growth potential in surgically resected tissue specimens from 70 cases of benign and malignant salivary gland tumours. Three stage streptavidin-biotin immunoperoxidase immunostaining using monoclonal antibody to PCNA showed a heterogeneity of PCNA index and distribution. In normal salivary gland specimens, PCNA was demonstrated in the nuclei of few ductal and acinar cells. In pleomorphic adenoma a multiple nodular growth pattern was observed with positive immunoreactivity restricted to the nuclei of tubulo-ductal structures. Warthin's tumour had positive nuclei in the outer cuboidal cells of epithelial component and germinal centres of lymphoid tissue. Myoepithelioma and acinic cell carcinoma showed slightly differing values and a statistically significant difference in the value of the index was observed in tumour cell aggregates of the cribiform type of adenoid cystic carcinoma and the solid undifferentiated type and between low/intermediate and high-grade mucoepidermoid tumours. PCNA is a useful marker of tumour cell proliferation; the index correlates with the grade of malignancy in salivary gland tumours.

Carcinoma, Squamous Cell↗
PubMed1988

Immunohistochemical localization of glutamine transaminase K, a rat kidney cysteine conjugate beta-lyase, and the relationship to the segment specificity of cysteine conjugate nephrotoxicity.

Rat kidney glutamine transaminase K is a major rat kidney cysteine conjugate beta-lyase and is a key enzyme in the nephrotoxicity of some cysteine conjugates. However, it has not been demonstrated that the beta-lyase is present in the target cells. Furthermore, although all segments of the proximal tubule are affected by high doses of nephrotoxic cysteine conjugates, the S3 segment is the most sensitive. Because heterogeneous distribution of the beta-lyase could account for the enhanced sensitivity, antibody raised against rat kidney cysteine conjugate beta-lyase has been prepared and used to investigate the distribution of the enzyme in kidney and other tissues. The data show that the enzyme is highest in rat kidney, consistent with enzyme activity data. By immunohistochemical staining, no enzyme is present in the glomeruli or distal tubular elements of the kidney. The enzyme is present only in the target cells, the renal proximal tubular epithelium. However, the distribution of the beta-lyase within the proximal tubule is not consistent with the hypothesis that a higher concentration of the enzyme in the S3 segment accounts for the greater sensitivity of S3 to nephrotoxic cysteine conjugates compared to S1 and S2. Several alternative hypotheses are discussed.

Acetylcysteine↗