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Biomedical subjects

S Yang

Publications and source records attributed to S Yang.

At least 451 records · Page 25Linked to original sources
PubMed1996

[Rapid detection of Salmonella with MUCAP reagent].

The 4-methylumbelliferyl-caprylate (MUCAP) was applied for the identification of Salmonella, it's specification, sensitity, and availability were reported. 65 strains of standard Salmonella, 48 strains of Salmonella isolated from foods growing on plates of HE, DHL, SS and MaConkey agar have been tested with MUCAP. All of them were identified as MUCAP positive; whereas, among the non-Salmonella tested only Pseudamonas spp., Aeromonas hydrophilia and Plesiomonas shigelloides were shown as positive, but they could be differentiated easily with Salmonella by means of oxidase test. The unspecific reaction of Serratia marcescens could be eliminated by using the plate medium which has been added of 1% sucrose. Both the sensitivity and specificity of the method were up to 97% more, and the operating of the method was very facility and to be done within few minutes.

Hymecromone↗
PubMed1996

Increased connexin-43 and gap junctional communication correlate with altered phenotypic characteristics of cells overexpressing the receptor for hyaluronic acid-mediated motility.

Gap junctional intercellular communication (GJIC) and connexin expression are often altered during cell migration, growth, and transformation, each of which is accompanied by cytoskeletal reorganization. Recently, transfection of fibroblast cells with various isoforms of the receptor for hyaluronic acid-mediated motility (RHAMM) was shown to have profound and differential effects on motility, growth, and cell contact behavior as well as on elements of the actin-containing cytoskeleton. These cells thus provide an ideal system in which to investigate parameters implicated in regulation of GJIC as well as expression of connexin-43 (Cx43) in fibroblasts. We used 10T1/2 fibroblast cell lines transfected with RHAMM isoforms or a dominant negative mutated form of RHAMM that blocks the function of endogenous RHAMM. Increased RHAMM expression in the various cell lines was correlated with increased Cx43 and GJIC. These changes were accompanied by a loss of contact inhibition and decreased focal adhesions in all, and elevated motility of most but not all, cell lines tested. RHAMM-induced transformation also resulted in elevated GJIC and Cx43 levels. Reversion to normal growth, motility, and focal adhesion density following transfection of H-ras-transformed fibroblasts with the mutant form of RHAMM was associated with decreases in both Cx43 expression and GJIC. Transfection of 10T1/2 fibroblasts with RHAMM II (exons 5-14) produced altered contact behavior and increased both Cx43 and GJIC but had no effect on motility. All cells expressing high levels of RHAMM, regardless of the isoform, exhibited a lower density of focal adhesions, which corresponds to a reduced organizational state of the cytoskeleton. These results indicate that regulation of GJIC most strongly correlates with altered focal adhesion and cytoskeleton organization that can lead to various secondary responses, including motility, growth, and transformation, and suggest that RHAMM regulates GJIC and Cx43 expression possibly through its actions on focal adhesions and the associated cytoskeleton.

Animals↗
PubMed1996

Protease activity associated with excystation of Cryptosporidium parvum oocysts.

A Cryptosporidium parvum homogenate (CPH), prepared from partially excysted oocysts, was examined for proteolytic activity capable of hydrolyzing azocasein. Protease activity, measured at pH 7.0, was not detected in fresh oocysts but increased progressively with incubation at 37 C. Activity peaked after 60 min incubation but progressively decreased with extended incubation intervals. Cryptosporidial protease activity was significantly inhibited (P < 0.01) by the serine protease inhibitors phenylmethylsulfonyl fluoride (PMSF), diisopropyl fluorophosphate (DIFP), aprotinin, alpha-1-antitrypsin (AAT), and the cysteine protease inhibitor L-trans-epoxysuccinyl-leucylamido-(4-guanidino)-butane (E-64). No single inhibitor completely blocked CPH-associated protease activity; however, the combination of PMSF and E-64 inhibited > 95% of the azocasein hydrolysis measured in untreated control samples. The same group of inhibitors was further evaluated for their ability to inhibit excystation of C. parvum oocysts. PMSF, DIFP, aprotinin, and AAT significantly inhibited (P < 0.05) oocyst excystation at 15-, 30-, and 60-min incubation intervals; E-64 had no significant inhibitory effect on excystation. The results of this study demonstrate proteolytic activity during peak periods of excystation. Further, cryptosporidial protease activity was sensitive to both serine and cysteine protease inhibitors, but only serine protease inhibitors significantly inhibited oocyst excystation. These findings provide preliminary evidence of cryptosporidial proteases of both serine and cysteine protease classes and suggest that serine protease(s) are functionally associated with excystation.

Animals↗
PubMed1996

[A human bone marrow cell line (B3HM) inducing leukemia in mouse].

Human bone marrow mononuclear cells were cultured on a layer of stromal cells derived from bone marrow of a patient with esophageal cancer. After five-week cultivation, the mononuclear cells could grow independently of stromal cells in liquid culture and had been passaged over 50 generations with a doubling time of 48 hours. The cell line thus established is called B3HM. The growth of B3HM appeared anchorage independent in semi-solid culture and produced 423 +/- 87.7 colonies per 5 X 10(4) cells. Immunofluorescence analysis showed that the cells were CD19+, CD20+, CD13+, CD15+, with both B cell and granulocyte surface markers. The cells or cell homogenate could induce leukemia when inoculated in nude mice and "615" inbred mice. The induced mouse leukemia was transplantable and L3T4 positive in more than 80% of the leukemic cells. The pathogenesis of the induced mouse leukemia is worthy of further investigation.

Aged↗
PubMed1996

[Preparation of huichun zhibao oral liquid (HZOL)].

The formulation, preparing method, quality standards, pharmacodynamic experinents and toxicological experiments of HZOL are described. The content of icariin, which is and effective component of epimedium herb as well as one of the main ingredients in HZOL, was successfully determined through HPLC, with an average recovery of 98.98% and RSD = 1.53%.

Animals↗
PubMed1996

Overexpression of c-myc gene without gene amplification in human hepatocellular carcinoma.

OBJECTIVE: To clarify the relationship between c-myc gene amplification and expression in human hepatocellular carcinoma (HCC) tissue. METHODS: Levels of amplification, transcription and P62 myc expression of c-myc gene in tumor tissues and corresponding non-tumor tissues were systematically studied using Dot blot hybridization, in situ hybridization and immunohistochemical technique, respectively. The 14 pairs of specimens were resected from patients with HCC. RESULTS: The amplification of c-myc gene was not found in tumor and non-tumor tissues. Overexpression of c-myc mRNA transcription was detected in 11 tumor tissues and 10 non-tumor tissues. The positive rate of P62 myc was 85.7% (12/14) in tumor tissues and 92.9% (13/14) in non-tumor tissues, respectively. A close correlation was noticed between c-myc mRNA and P62 myc expression. The results suggested that c-myc gene overexpression was not related to its amplification. CONCLUSIONS: The overexpression of c-myc mRNA and gene product without amplification may be characteristic in HCC.

Carcinoma, Hepatocellular↗
PubMed1996

[A preliminary study on the hormonal causes of seasonal change in miniature endplate potentials at the neuromuscular junctions of the toad].

The hormonal causes of seasonal change in amplitudes of miniature endplate potentials (MEPP) in the adult toad (Bufo bufo gargarizans) were studied with intracellular recordings of MEPP at the neuromuscular junction of sartorius muscle fiber in vitro by adding L-thyroxine sodium and estrone to the bath medium during spring and autumn respectively. The results showed that L-thyroxine sodium (50 mumol/ L) could not change the amplitude of MEPP, regardless of spring or autumn, but estrone (100 mumol/L) could cause a clear increase in MEPP amplitude in both seasons. From these results it was presumed that thyroxine might be less related to the seasonal changes in MEPP amplitude whereas the seasonal fluctuations of gonadal hormones in the body might play a role.

Animals↗
PubMed1996

[Seasonal variation and circannual rhythm of miniature end-plate potentials recorded from the neuromuscular junctions of the adult toad (Bufo bufo gargarizans)].

The seasonal variations and circannual rhythm of miniature end-plate potentials (MEPP) recorded from the sartorius neuromuscular junctions (NMJ) of 66 female and 62 male adult toads (Bufo bufo gargarizans) were studied with intracellular microelectrode recording techniques of electrophysiology. The results revealed that the mean amplitude of MEPP in each month of a year showed clear seasonal variation with a nadir in September and October and a zenith in March and April. This seasonal variation in MEPP amplitude was proved to be a circannual rhythm by single cosinor analysis and zero amplitude test, and the three parameters of the rhythm, i.e. mesor, amplitude and acrophase were 0.29 +/- 0.05 mV, 0.25 mV and -97.17 degrees in female toad and 0.19 +/- 0.02 mV, 0.16 mV and -92.01 degrees in male toad, respectively; the circannual rhythm in female toad was more distinct than that in male. Neither seasonal variation nor circannual rhythm was statistically significant in the changes of frequency of MEPP, regardless of toad sexuality.

Animals↗
PubMed1996

[A measurement of cytoplasmic estradiol and progesterone receptors in endometrium of patients with habitual abortion].

Estradiol and progesterone receptors in the endometrium of eight patients with habitual abortion in proliferative and secretory phases were measured by DCC. The serum estradiol (E2) and progesterone (P) were detected by radioimmunoassay, and the endometrium was histologically studied. The results showed that the level of serum E2 was normal in the proliferative and secretory phases. In 5/8 patients, the serum P level was below 11 ng/ml. The estradiol receptor of patients was not different from that of normal women in the proliferative and secretory phases, but the progesterone receptor was significantly lower than that of normal women in the proliferative and secretory phases. These suggest that the lower level of progesterone and progesterone receptor in the endometrium may be one of the causes of habitual abortion.

Abortion, Habitual↗
PubMed1996

[A cohort study on the relationship between standardized mortality of pulmonary heart disease and smoking].

We explored the relationship between the standardized mortality of pulmonary heart disease (PHD) and smoking at Shifang county through a five-year follow-up study of 29,498 farmers over 35 years old. The death ratio of PHD was 30.35%, which stood first in all causes of death. The mortality of PHD for cigar/cigarette smokers regardless of sex was not significantly different from that for nonsmokers (P > 0.05). The RR was 1 or so. The analysis of data stratified by age showed that the specific mortality increased with age in spite of some inequalities smoking; the RR of PHD for cigar/cigarette smokers in all age groups were 1 or so revealing no significant differences (P > 0.05). However, the standardized mortality of PHD increased with the accumulated amount of smoking. The relationship between the mortality of PHD and short-term smoking with small dose was not significant (P > 0.05), but when the accumulated amount reached certain level, i.e. the smoker consumed cigar more than 270 kg or consumed cigarette more than 20,000 packs, the relationship between the behavior of cigar/cigarette smoking and the mortality of PHD became apparent. The RRs were 1.40-3.94 and the ARs 171-1610 per 100,000 person years (P < 0.05-0.01).

Adult↗
PubMed1996

[Quantitative study of magnoflorine in Epimedium koreanum Nakai].

The content of magnoflorine in different parts of Epimedium koreanum was determined by using HPLC. The results showed that magnoflorine existed in every part of the plant and the highest content was found in the rhizoma. A new index and a reliable method are correspondingly provided for the quality control of E. koreanum.

Aporphines↗
PubMed1995

The influence of energy sources on the proteolysis of a recombinant staphylococcal protein A in Escherichia coli.

The kinetics of proteolysis of a recombinant staphylococcal protein A in Escherichia coli were studied by a Western-blotting-based method. The proteolysis constants obtained from this method are very close to those obtained from the traditional radioactive pulse-chase technique. Protein A was selectively degraded to a great extent, while host proteins were quite stable after heat induction of protein A expression. The proteolysis of protein A was much faster in the presence of energy sources compared to when cells were starved of energy. The degradation rate constants are 2.8 h-1 in the presence of 10 g/l glucose and about 0.4 h-1 in the absence of any external carbon source. The supplementation of glucose to the medium at 0-100 mg/l caused a gradual increase of proteolysis of protein A, but the proteolysis was saturated when the concentration of glucose exceeded 200 mg/l at a cell concentration of about 0.36 g/l. The respiration inhibitor sodium azide completely inhibited the degradation of protein A in glucose-free salt medium but had almost no effect in the presence of glucose. Therefore, the proteolysis process is energy dependent but the energy supply rate obtained by fermentation of glucose is enough to meet this requirement. The proteolysis rate increased with the temperature in the interval 5-45 degrees C but was then reduced due to damage of the proteolysis system by high temperature. At 60 degrees C, the proteolysis ceased completely within 30 min.

Culture Media↗