Biomedical subjects

Q Y Chen

Publications and source records attributed to Q Y Chen.

At least 37 records · Page 2Linked to original sources

PubMed1994

Autoantigenic properties of native and denatured glutamic acid decarboxylase: evidence for a conformational epitope.

The frequency of antibodies to GAD (anti-GAD) in insulin-dependent diabetes mellitus (IDDM) varies greatly according to the type of assay employed. We therefore examined the immunoassay characteristics of diabetic sera using GAD purified from porcine brain and shown to contain both isoforms. Sera from 38 patients with IDDM, including 1 patient with both stiff-man syndrome (SMS) and IDDM, were studied for anti-GAD by radioimmunoprecipitation (RIP), Western blotting, and dot-blotting. The sera were selected according to reactivity in the RIP assay. There was a good correlation between potency of the RIP reaction at the screening dilution of 1:2 and the endpoint dilution in the assay which ranged from 1:2 to 1:30,000 for IDDM sera, and 1:300,000 for the SMS serum. Of the 38 sera positive for anti-GAD by RIP, only 6 had antibodies detectable by Western blotting, and all gave an RIP titer of at least 1:250. The low frequency of antibodies by Western blotting was explicable by denaturation of the antigen. Thus, using a dot-blotting assay in which reactivity to untreated "native" GAD was compared with reactivity to GAD after denaturation by reduction with 2-mercaptoethanol and boiling, 20 of the 38 IDDM sera reacted unequivocally with the native GAD compared with only 2 that reacted with denatured GAD after reduction and boiling. The sera were tested for their capacity to inhibit the catalytic activity of GAD, but only the high-titer serum from the patient with SMS did so. Our study further validates the RIP assay for anti-GAD and establishes that anti-GAD exists in IDDM over a wide range of titers that correlate with other assay characteristics, and also indicates that the conformational autoantibody epitope on GAD is susceptible to alteration under denaturing conditions.

Adolescent↗

PubMed1993

The insecticide buprofezin induces morphological transformation and kinetochore-positive micronuclei in cultured Syrian hamster embryo cells in the absence of detectable DNA damage.

The insecticide buprofezin was examined for its genotoxicity in cultured Syrian hamster embryo cells in order to better understand the mechanisms underlying the genotoxicity of the compound in mammalian cells. Exposure to buprofezin concentrations of 12.5-100 microM did not significantly affect the colony-forming ability of the cells, but did result in increased frequencies of morphologically transformed colonies. Treatment with buprofezin did not cause a detectable induction of DNA repair synthesis, an indicator of DNA damage, but significantly increased the frequency of micronuclei. Immunostaining of the cells with antikinetochore antibody (CREST antibody) showed that essentially all of the buprofezin-induced micronuclei were kinetochore-positive. The results suggest that morphological transformation of Syrian hamster embryo cells by buprofezin results from an interaction of the compound or a metabolite of it with the mitotic apparatus rather than from DNA damage.

Animals↗

PubMed1993

Antibody to two forms of dihydrolipoamide acetyltransferase (PDC-E2) in primary biliary cirrhosis.

Dihydrolipoamide acetyltransferase, the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2), is the major autoantigen in primary biliary cirrhosis. By immunoblotting with sera from patients with primary biliary cirrhosis, we observed a double band, of molecular weight 70 and 74 kD for PDC-E2, when a preparation of bovine heart mitochondria was not boiled prior to electrophoresis. This double band could also be detected using antisera raised in rats or rabbits against intact PDC or PDC-E2, but not in antisera raised against a synthetic decamer representing the lipoic acid binding sequence of PDC-E2; the latter reacted only with the 74 kD component. Antibody eluted from either the 70 or 74 kD component reacted with both 70 and 74 kD components. By ELISA, sera from patients with primary biliary cirrhosis reacted more strongly with a non-boiled than a boiled PDC-E2, whereas immune animal sera reacted equally with both preparations. Thus, according to whether preparations of PDC are boiled or not, two conformationally alternative forms of the PDC-E2 protein can be revealed by immunoblotting. The two forms in non-boiled preparations migrate at molecular weights corresponding to 70 and 74 kD.

Acetyltransferases↗

PubMed1993

Antibodies to glutamic acid decarboxylase in Australian children with insulin-dependent diabetes mellitus and their first-degree relatives.

Antibodies to glutamic acid decarboxylase (GAD), previously known as the 64-kD pancreatic islet cell autoantigen, are an important serologic marker of insulin-dependent diabetes mellitus (IDDM). Antibodies to GAD (anti-GAD) were examined in sera from Australian children with newly diagnosed IDDM (within 1 mo of diagnosis), IDDM of longer duration (mean +/- SD, 4.8 +/- 3.3 y), and in first-degree relatives, using a radioimmuno-precipitation assay with purified porcine brain GAD as antigen. Antibodies to islet cell cytoplasmic antigens (ICAb) were tested concurrently. The frequency of anti-GAD was not significantly different in children with newly diagnosed IDDM (31 of 42, 74%) and with IDDM of longer duration (14 of 21, 67%), whereas ICAb were present more frequently in children with newly diagnosed IDDM (64%) than in those with longer duration IDDM (14%). In all, 90% of children with newly diagnosed IDDM had either anti-GAD or ICAb, whereas only 48% had both. For the 77 first-degree relatives, the frequency of anti-GAD was 2% (one of 44) in parents and 6% (two of 33) in siblings; ICAb were not detected in any of these relatives. The presence of anti-GAD in the majority of children with IDDM, irrespective of the duration of their disease, represents a useful diagnostic marker for IDDM, and should be of value in ascertaining individuals at risk for developing IDDM.

Adolescent↗

PubMed1993

Morphological, phenotypic and functional characteristics of a pure population of CD56+ CD16- CD3- large granular lymphocytes generated from human duodenal mucosa.

Interleukin-2 (IL-2)-dependent large granular lymphocytes (LGL) with a distinctive surface phenotype were generated from histologically normal duodenal biopsy tissues. Immunoperoxidase staining of the mucosa with an anti-CD56 monoclonal antibody revealed LGL localized in the lamina propria rather than in the epithelium. Light and electron microscopy demonstrated azurophilic and electron-dense cytoplasmic granules. Flow cytometry analysis revealed that these cells express CD45, CD56, CD2, CD7, CD11a, CD18, CD69 and the intermediate affinity (p70) IL-2 receptor (IL-2R) but not CD57, CD16, CD3, CD4, CD5, CD8, CD45RA, CD25, or the high affinity p55 IL-2R. The LGL proliferated when cultured in the presence of human rIL-2 but not in the presence of human rIL-4. Functional studies demonstrated that the LGL had strong cytotoxicity against natural killer (NK) target cells, K562, but not NK-resistant targets such as Colo 205, Melanoma and Epstein-Barr virus (EBV)-transformed B-cell lines. The LGL expressed genes for IL-5, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumour necrosis factor-alpha (TNF-alpha) and the corresponding cytokines were detected in culture supernatant. These results provide evidence for an important role of gut mucosal LGL in the induction and regulation of inflammation and immunity in the gut.

Adult↗

PubMed1993

[The use of domestic silicone oil in the treatment of complicated retinal detachment].

Vitrectomy and domestic silicone oil were used in the treatment of 42 eyes with complicated retinal detachment, and the retina was reattached in 34 cases or a rate of 80%, which dropped to 54% in 4-24 months postoperative. Among 7 eyes with successful retinal attachment and silicone oil removal, 1 eye developed recurrent retinal detachment. The therapeutic effect of silicone oil and operative complications were discussed. Removal of intravitreal silicone oil 3-6 months after injection was necessary to avoid adverse consequences. The study indicated that pars plana vitrectomy with silicone oil injection was an effective procedure in the management of complicated retinal detachment.

Eye Diseases↗

PubMed1993

Effect of Panax notoginseng saponins on increased proliferation of cultured aortic smooth muscle cells stimulated by hypercholesterolemic serum.

Panax notoginseng saponins (PNS) was extracted from a Chinese herb medicine. After preparation of cultured aortic smooth muscle cell (SMC) from primary aortic explants, the cytotoxicity of hypercholesterolemic serum (HCS) for cultured cells was determined by trypan blue exclusion test, and [3H]thymidine incorporation and cell numbers were counted at the same time. The results showed that HCS (0.5 mg cholesterol.ml-1) increased the incorporation of [3H]thymidine into cultured cells (3722 +/- 440 vs 1655 +/- 288 dpm/microgram cell proteins, P < 0.01), stimulated the proliferation of SMC [(6.5 +/- 1.5) x 10(5) vs (4.3 +/- 1.2) x 10(5) cells/plate, P < 0.01], and that high concentration HCS (final cholesterol concentration 2 mg.ml-1) was cytotoxic to the cultured cells. PNS (100 and 400 micrograms.ml-1) decreased the incorporation of [3H]thymidine into SMC in culture with or without HCS (1292 +/- 260 and 982 +/- 314 or 4111 +/- 886 and 2361 +/- 751 dpm/microgram cell protein), and inhibited the proliferation of the cultured cells [(3.3 +/- 0.7) x 10(5) and (2.9 +/- 0.7) x 10(5) or (4.7 +/- 1.4) x 10(5) and (4.1 +/- 1.2) x 10(5) cells/plate). We conclude that PNS can inhibit the proliferation of aortic SMC stimulated by HCS. These results also suggest that HCS may play an atherogenic role in the arterial wall and that PNS may prevent atherosclerosis and inhibit progression of the atherosclerotic lesions by interfering with the proliferation of arterial SMC.

Animals↗

PubMed1992

Antibodies to glutamic acid decarboxylase discriminate major types of diabetes mellitus.

Insulin-dependent diabetes mellitus (IDDM) is marked by circulating antibodies to a 64,000-M(r) islet cell antigen identified as glutamic acid decarboxylase (GAD). We describe a radioimmunoprecipitation assay with GAD isolated from pig brain. The sera tested were from 80 patients with IDDM including 26 with disease of recent onset and 54 with disease of longer duration (3-42 yr), 20 with non-insulin-dependent diabetes mellitus (NIDDM), and 55 nondiabetic subjects. Conventional assays for islet cell cytoplasmic antibodies were performed concurrently. The level of antibody in serum was expressed in units based on percentage reactivity of a standard reference serum. The frequency of antibody to GAD in IDDM was 69% in short-duration cases and 59% in long-duration cases. The latter was substantially higher than the frequency of islet cell cytoplasmic antibody. Antibodies to GAD were elevated (means +/- 3 SD) in 5% NIDDM cases and in none of the nondiabetic subjects. A simple laboratory test with a defined autoantigen has substantial implications for population screening and early diagnosis of IDDM and for better understanding of its pathogenesis.

Adolescent↗

PubMed1992

[Stable and efficient expression of human interleukin-6 cDNA in mammalian cells after gene transfer].

Following reverse transcription and PCR amplification, the human interleukin-6 (IL-6) cDNA was cloned from total RNA of activated human tonsillar mononuclear cells. Southern blot showed the presence of specific band, and its DNA sequence demonstrated that the fragment was 650 bp in length, spanning the complete coding region and part of 5' and 3'-untranslated regions. The human IL-6 sequence seemed to be well conserved. One nucleotide change at 429 position was observed, but this change did not affect the amino acid composition. After inserting the cloned cDNA into retroviral vector XM-6, the recombinant was packaged in PA317 cells and the amphotropic virus titer reached 5 x 10(5) CFU/ml. Human IL-6 was expressed in mammalian cell line SP2/0 cells, after being infected by the constructed retrovirus. The G418 resistant SP2/0 cells secreted IL-6. Its supernatant was able to maintain in vitro growth of the IL-6 dependent T1165 cell line. Northern blot analysis of the transfected SP2/0 cells showed significantly elevated IL-6 message, being consistent with the result of T 1165 bioassay. The expression was stable during the 12 month period of observation. The hybridoma cells, formed after fusion of the transfected SP2/0 cells and lymphocytes, exhibited accelerated growth.

Animals↗

PubMed1990

A new efficient synthetic method for 2- and 4-hydroxy-17 alpha-ethynylestradiol.

The reaction of ethyl magnesium bromide and 17 alpha-ethynylestradiol with formaldehyde in the presence of triethyl phosphate or hexamethylphosphoramide gave the 2- and 4-formyl-17 alpha-ethynylestradiol in high yield. Treatment of the formyl derivatives with an alkaline solution of hydrogen peroxide in tetrahydrofuran afforded the corresponding catechols in almost quantitative yield. This new synthetic method was far superior to other methods, especially concerning simplicity, selectivity, and high yields.

Estradiol↗

PubMed1990

[An approach to the mode of case findings of pulmonary tuberculosis in countryside].

Through basic health care network, the mode of symptomatic case finding was adopted to discover, treat and supervise pulmonary tuberculosis patients in countryside. The results showed that its outstanding advantages were high detection rate (13.2%), high proportion of initial treated cases (98.2%), high curative effect and low expenses. The detection rate of smear-positive patients (48.5%) was much higher than that of other case finding modes (P less than 0.05). Sputum conversion was seen in all smear positive cases. They were cured after regular treatment.

Diagnostic Services↗

PubMed1989

Inositol phospholipids activate plasma membrane ATPase in plants.

Phosphatidylinositol-4-monophosphate and phosphatidylinositol-4,5-bisphosphate increased the activity of the vanadate-sensitive ATPase associated with plasma membranes isolated from both sunflower hypocotyls and carrot suspension culture cells. The response was not due to the metabolism of the polyphosphoinositides since diacylglycerol, inositol-1,4-bisphosphate, inositol-1,4,5-trisphosphate, glycerophosphoinositol monophosphate and glycerophosphoinositol bisphosphate had no effect. These data suggest that activation of the inositol phospholipid kinases could be a critical step in signal transduction in plants.

1-Phosphatidylinositol 4-Kinase↗

PubMed1988