Biomedical subjects
Publications and source records attributed to M Shen.
HLA-A, B and DR antigens were studied in Mainland Chinese diabetes mellitus patients and controls (31 Type I DM, 50 Type II DM, 105 controls). HLA-DR3 and HLA-A9 were increased in Type I diabetics only. An increase in HLA-DR4 was noted in Type I diabetics, but the increase was not statistically significant in this small series.
The rate of release of an aqueous solution of pilocarpine hydrochloride sequestered in hydrogel-type materials can be reduced by plasma treatment of the polymer surface. Two plasma techniques were used. The first involves exposure of the hydrogel to the effects of a glow discharge sustained in argon, a process known as CASING. (Crosslinking by Active Species of Inert Gases). The second technique involves the deposition of a thin film by plasma polymerization of organic gases. The gases used in this study were ethane, ethylene and tetrafluoroethylene. Hydrogels were prepared by photopolymerization of 2-hydroxymethyl methacrylate (HEMA), and copolymerization of HEMA with methyl acrylate. The CASING treatment was found to be least effective. The most successful method was the plasma polymerization of tetrafluoroethylene, which yielded an order of magnitude reduction in the flux rate of pilocarpine with a film thickness of 0.25micronm. Polymerization conditions bringing about a crack-resistant film were critical in obtaining the best results.
An investigation was performed to determine the effectiveness of thin plasma-polymerized films and CASING for controlling the flux of progesterone through poly-(dimethyl siloxane) membranes. It was concluded that up to 40-fold reductions in flux could be achieved with plasma-polymerized films. The principal factors affecting the extent of flux reduction were the nature of the monomer used (ethylene, ethane and tetrafluoroethylene), the film thickness, and the deposition conditions. CASING (Crosslinking by Activated Species of Inert Gases) of the poly-(dimethyl siloxane) membrane surface also proved effective in reducing the flux of progesterone through it.
We have designed synthetic peptides corresponding to two different regions of the genome of foot-and-mouth disease virus (FMDV) that are effective as (a) a vaccine or (b) a diagnostic reagent which differentiates convalescent from vaccinated animals, respectively. The peptide vaccine is based on a sequence from the prominent G-H loop of VP1, one of the four capsid proteins. The sequence was optimized by the inclusion of a cyclic constraint and adjoining sequences, and broader immunogenicity was obtained by the incorporation of consensus residues at hypervariable positions. The peptide also included a promiscuous T-helper epitope for effective immunogenicity in outbred populations of large animals.The diagnostic reagent, a peptide based on non-structural (NS) protein 3B, is used in immuno-assays for the detection of antibodies. Antibodies to this NS protein are present in the sera of infected animals but not in the sera of vaccinated animals. The VP1 peptide can be used in complementary immuno-assays for confirmation of NS test results and to monitor for vaccination. This system for differential diagnosis is important to establish the disease-free status of a country.
BACKGROUND: Impaired coronary flow reserve (CFR) has been observed in remote nonischemic regions in patients after myocardial infarction. The mechanism for this impairment in remote nonischemic CFR remains undefined. This study evaluates the effect of progressive regional ischemic dysfunction on function in remote nonischemic regions, and the effect of the extent of dysfunction on remote nonischemic coronary flow and CFR. METHODS: In an anesthetized open-chest canine model (n = 7) of acute progressive distal and proximal left anterior descending (LAD) coronary artery occlusion, regional myocardial thickening fraction and coronary flow and CFR were measured with Doppler probes. CFR was assessed by an intracoronary injection of 36 microg of adenosine. Changes in thickening fraction and CFR were evaluated for isovolumic, ejection, and diastolic phases. Changes in resting regional flow were also assessed using radiolabeled microspheres. The extent of the ischemic area was defined as regions of myocardium with endocardial microsphere blood flow less than 0.3 mL/min/g. RESULTS: The ischemic area increased from 12% +/- 1% of left ventricle with distal occlusion to 30% +/- 2% of left ventricle with proximal occlusion (P < .001). The LAD thickening fraction decreased significantly from baseline (18% +/- 1%) to distal (-8% +/- 1%,) and proximal (-4% +/- 1%) occlusion (P < .001 for distal and proximal vs baseline). Isovolumic bulging in the LAD region was associated with a progressive increase in thickening fraction in the remote nonischemic left circumflex (LCX) artery region (baseline 12% +/- 1%; distal occlusion 15% +/- 2%, P = .014 vs baseline; proximal occlusion 17% +/- 2%, P = .02 vs baseline). Most of the increase in remote thickening fraction occurred during the isovolumic phase. There was no significant change in resting flow in remote nonischemic LCX regions or global hemodynamic parameters. However, there was a progressive decrease in remote nonischemic CFR (baseline 2.44 +/- 0.3), distal occlusion (2.19 +/- 0.31; P = .055 vs baseline), and proximal occlusion (1.79 +/- 0.22; P = 0.004 vs baseline, and P = .012 vs distal occlusion). A progressive decrease in CFR was noted in each phase of the cardiac cycle. CONCLUSION: In a canine model of acute progressive distal and proximal coronary occlusion, we observed a progressive decrease in CFR in remote nonischemic regions concurrent with an increase in the extent of ischemia. The decrease in remote nonischemic CFR was associated with ischemia-induced isovolumic bulging, which placed the remote regions at a mechanical disadvantage. These observations suggest a potential mechanical etiology for the observed impairment in remote CFR. Alterations in remote nonischemic CFR during acute ischemia may have important clinical implications for perfusion scintigraphy.
A retrospective study was performed on 500 consecutive gastric biopsies obtained from patients with a diagnosis of gastritis and gastric carcinoma. Overall, Helicobacter pylori was detected in 336 cases (67.2%); it was seen in 82.4% of patients with duodenal ulcer, 80.1% of patients with gastric ulcer, 76.1% of patients with chronic atrophic gastritis, 60.3% of patients with chronic superficial gastritis, and 32.1% of patients with gastric carcinoma. The gastric epithelium colonized by Helicobacter pylori showed characteristic changes including loss of the apical mucous portion of individual cells, dropout of epithelial cells, and erosions. There is a strong suggestion that the inflammation associated with Helicobacter pylori infection plays a role in the pathogenesis of gastric carcinoma.
Widespread hypomethylation of DNA and regional hypermethylation, including tumor suppressor regions, have been demonstrated in several human cancers. Since a highly heterogeneous array of genetic anomalies have been associated with breast cancer, we examined several chromosomal hot spots for abnormal methylation patterns. Low-levels of increased methylation of HRAS (11p15) were observed between normal and tumor breast tissue samples from 8 patients. No noticeable variation in methylation was observed with DNA probes from chromosomes 11p15, 1p36, 17q22, 17p13.3 and 3p21 for the 7 ductal breast carcinoma patients, though some variability was observed for a patient with atypical medullary carcinoma. Additionally, the methylation pattern of the estrogen-receptor gene (6q24-27), whose protein product is increased in numerous breast cancers, also did not change. Therefore, as opposed to other cancer types, widespread hypomethylation and regional hypermethylation do not appear to be involved in the early stages of breast cancer and does not account for the molecular heterogeneity of the disease. Proposed alternative mechanisms for the diversity of genetic alterations associated with breast cancer are discussed.