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Biomedical subjects

H Meng

Publications and source records attributed to H Meng.

At least 73 records · Page 4Linked to original sources
PubMed1998

Apoptosis induced by X-rays and chemical agents in murine fibroblastic cell lines with a defect in repair of DNA double-strand breaks.

PURPOSE: To investigate apoptosis in murine fibroblasts that are deficient in DNA double-stand breaks (dsb) repair. MATERIALS AND METHODS: BALB/c 3T3 cells and cells from a severe combined immunodeficient (scid) mouse were exposed to X-rays, UV light, bleomycin, etoposide or cisplatin. After exposure, the rate of apoptosis was assayed by propidium iodide staining based on characteristic morphological change. RESULTS: The scid cells, defective in dsb repair, were extremely sensitive to apoptosis induced by X-rays and bleomycin compared with BALB/c 3T3 cells. The scid cells were slightly sensitive to apoptosis induced by etoposide, an agent producing protein-associated dsb, and to apoptosis induced by agents not causing dsb. CONCLUSIONS: These studies show that sensitivity of cells to apoptosis induced by X-rays or bleomycin is enhanced by the scid mutation and that apoptosis induced by etoposide, which causes protein-associated dsb, is not greatly affected. There may be different processes involved in the induction of apoptosis by X-rays or bleomycin and etoposide.

3T3 Cells↗
PubMed1998

Increased angiotensin II type 1 receptor expression in hypercholesterolemic atherosclerosis in rabbits.

Angiotensin II (Ang II) promotes vascular smooth muscle growth and may be involved in the initiation and progression of atherosclerosis. To examine whether Ang II receptor expression in vascular tissues is altered in atherosclerosis, male New Zealand White rabbits were fed a high-cholesterol diet (1% cholesterol + 4% coconut oil mixed with regular chow; hypercholesterolemic group, n=12) or regular chow (control group, n=8) for 10 weeks. At the end of this period, the serum cholesterol level in the rabbits fed the high-cholesterol diet was higher than that in the control group (3616 +/- 144 versus 30 +/- 1 mg/dL, P<0.001). There was no atherosclerosis in the aortas of the control group, whereas 51 +/- 6% of the aorta was covered with atherosclerosis in the hypercholesterolemic group. Total Ang II receptor expression in the atherosclerotic aortic tissues was increased 5-fold in the hypercholesterolemic rabbits (292 +/- 28 versus 51 +/- 32 fmol/mg tissue, mean +/- SE, P<0.001), and the increased Ang II receptor expression was entirely due to enhanced Ang II type 1 (AT1) receptor expression (289 +/- 38 versus 38 +/- 18 fmol/mg, P<0.001), as Ang II type 2 receptor expression was unaltered (7 +/- 5 versus 3 +/- 2 fmol/mg, P=NS). AT1 receptors were localized primarily in the media and to some extent in the intima of the atherosclerotic aorta, as determined by immunohistochemistry with specific monoclonal and polyclonal AT1 receptor antibodies. Increased synthesis of AT1 receptor mRNA in atherosclerotic tissues was confirmed by reverse transcription-polymerase chain reaction. To evaluate the functional significance of increased AT1 receptor expression, the constrictor response of aortic rings to Ang II was examined and found to be markedly enhanced in atherosclerotic aortic rings (P<0.01 versus control aortic rings). The endothelium-dependent relaxation of aortic rings from hypercholesterolemic rabbits was markedly attenuated (P<0.001). This study shows that hypercholesterolemia in rabbits results in atherosclerosis, loss of endothelium-dependent relaxation, and increased Ang II receptor (entirely AT1 receptor) expression in aortic tissues, which may result in altered vasoreactivity.

Acetylcholine↗
PubMed1998

[Genetic polymorphisms of the D19S400 locus in Chinese Zhuang, Bai, Tibetan, Mongolian populations].

Four Chinese populations have been studied by the polymerase chain reaction (PCR) for obtaining the data on genetic polymorphisms of D19S400 locus in four populations in China and for evaluating its use in forensic practice. EDTA-blood samples were collected from 356 unrelated individuals in Nanning (Zhuang), Dali (Bai), Lasa (Tibetan); Hailaer (Mongolian), DNA samples were extracted by Phenol/Chloroform method. The PCR products were analyzed by PAG vertical electrophoresis. Nine alleles and 42 genotypes were found at D19S400 locus in these four populations. The heterozygosity was between 0.75 and 0.89 and the discriminating power between 0.9274 and 0.9625. Significant difference was observed in the distribution of allele frequencies among the four Chinese populations. According to the results obtained in this study, D19S400 locus is a useful marker for individual indentification, paternity testing and for genetics study.

Alleles↗
PubMed1998

[Prevalence of subgingival microbiota in Chinese using checkerboard DNA-DNA hybridization].

OBJECTIVE: To evaluate the prevalence of subgingival taxa of periodontal healthy persons and rapidly progressive periodontitis (RPP) patients using checkerboard DNA-DNA hybridization and to find the main pathogens in RPP. METHODS: Eighty four subgingival plaque DNA samples taken from 5 healthy subjects (H) and 6 RPP patients were hybridizated with 37 bacterial probes. RESULTS: The detection frequences of 6 bacteria (E. corrodens, et al.) were greater than 90%. Suspected periodontal pathogens, e.g. A. actinomycetemcomitans seratype b, T. denticola, F. nucleatum as nucleatum, B. forsythus, P. nigrescens, W. succinogenes, C. rectus, P. micros, S. intermedius and P. gingivalis were significantly more frequently found in RPP group than in H group. The mean counts of these pathogens were significantly more elevated in RPP group than in H group. CONCLUSION: It is suggested that periodontal destruction occurrence requires the pathogens in sufficient number at the site, RPP may be resulted from several pathogens.

Adult↗
PubMed1998

[Electrophoresis of proteins in gingival crevicular fluid of patients with adult periodontitis before and after treatment].

OBJECTIVE: To analyze the overall gingival crevicular fluid (GCF) protein profiles from adult periodontitis (AP) both before and one month after conventional periodontal treatment in expectation to find reliable specific protein markers in GCF for healthy and disease. METHODS: GCF samples were collected using filter paper strips from 56 sites of 12 AP patients. The proteins of GCF were examined via sodium dodecyle sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed by the Image Master Electrophoresis Evaluation System. RESULTS: After periodontal treatment, the mean number of protein bands and the abundance and percentage of non-serum derived low molecular weight proteins (12,000, 10,000) decreased significantly (P < 0.001 and < 0.05 respectively). The percentage of non-serum derived 38,000 protein increased and correlated negatively with pocket depth and the volume of GCF before treatment. CONCLUSION: 1. the elevation of the 12,000 and 10,000 proteins are associated with the periodontal inflammation; 2. the elevation of 38,000 protein is associated with recovery.

Adult↗
PubMed1998

[Electrophoretic analysis of protein composition in gingival crevicular fluid].

OBJECTIVE: To seek the protein composition related to periodontal diseases. METHODS: 86 gingival crevicular fluid (GCF) samples were collected by rinsing the sulgingival sulci from subjects with healthy gingiva (20), gingivitis (24) and periodontitis (42). The protein composition were examined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) on a Phast System. The gels were scanned and analyzed using Phast Image with computer. RESULTS: In inflammatory condition, the serum derived proteins with MW 82,000, 77,000, 17,000 occurred more frequently than in healthy gingiva, and the occurrence and abundance of non-serum derived proteins with MW 41,000, 21,000, 12,000 were also increased in inflammatory condition compared with healthy gingiva. CONCLUSION: The high levels of proteins with MW 82,000, 41,000, 21,000, 12,000 are close related to the periodontal inflammatory status.

Adult↗
PubMed1998

[The adolescent psychiatry department: organization and initial experiences].

As in most parts of Switzerland, there was a lack of possibility to hospitalise adolescents in specialised psychiatric wards. In 1993, after a long preparatory period, it became possible to admit the first patient to the newly established adolescent psychiatric department at Basel, a subunit of the university hospital. The department is conceived as an open ward, where patients are being cared for by an interdisciplinary team of psychiatric nurses and paedagogics, besides many other professionals. Milieutherapeutic techniques, psychotherapy and pharmacotherapy are practised side by side. The conceptional ideas, gradual building of the ward and the experience of the first three years clinical experiences are summarised in this article.

Adolescent↗
PubMed1997

Human mast cells stimulate vascular tube formation. Tryptase is a novel, potent angiogenic factor.

The presence of mast cells near capillary sprouting sites suggests an association between mast cells and angiogenesis. However, the role of mast cells in blood vessel development remains to be defined. In an attempt to elucidate this relationship, we investigated the effect of human mast cells (HMC-1) and their products on human dermal microvascular endothelial cell (HDMEC) tube formation. Coculture of HMC-1 with HDMEC led to a dose-response increase in the network area of vascular tube growth. Moreover, the extent of neovascularization was enhanced greatly when HMC-1 were degranulated in the presence of HDMEC. Further examination using antagonists to various mast cell products revealed a blunted response (73-88% decrease) in the area of vascular tube formation if specific inhibitors of tryptase were present. Tryptase (3 microg/ml) directly added to HDMEC caused a significant augmentation of capillary growth, which was suppressed by specific tryptase inhibitors. Tryptase also directly induced cell proliferation of HDMEC in a dose-dependent fashion (2 pM-2 nM). Our results suggest that mast cells act at sites of new vessel formation by secreting tryptase, which then functions as a potent and previously unrecognized angiogenic factor.

Angiogenesis Inducing Agents↗
PubMed1997

[Effect of cyclosporin A on intracellular accumulation and efflux of drug in K562/DOX cells].

OBJECTIVE: To explore measures to overcome multidrug resistance of tumor cells. METHODS: The effects of cyclosporin A (CsA) on drug sensitivity, intracellular drug accumulation and drug efflux in multidrug-resistant human leukemic cell line K562/DOX were studied by MTT colorimetric assay and spectrofluorimetry. RESULTS: CsA enhanced the cytotoxicity of doxorubicin (DOX) to K562/DOX, and when CsA > or = 2microg/ml the sensitivity of K562/DOX to DOX increased significantly. The efflux of DOX markedly decreased when K562/DOX cells were incubated with 2microg/ml CsA, while CsA had no effect on efflux of DOX in K562 cells. CONCLUSION: CsA could markedly decrease the efflux and enhance the intracellular accumulation of DOX in K562/DOX cells.

Cyclosporine↗
PubMed1997

[Clinical and experimental study on jinshui liujun decoction in treating chronic bronchitis].

OBJECTIVE: To assess the effect of Jinshui Liujun decoction (JSL) in treating chronic bronchitis. METHODS: The effect of JSL on expelling the phlegm and strengthening the body resistance were observed. RESULTS: JSL was proved to be efficacious in improving immune function of the body and pulmonary ventilatory function (P < 0.01). JSL could not only increase the secretion of rats' trachea mucosa and dilute sputum, but also increase the motion speed of the pigeons' trachea cilia, thus facilitate the removal of sputum. Compared with the normal saline control group, both animal experiments displayed significant statistical difference (P < 0.01), but without significant difference when compared the JSL group with the positive drug Juhong Tanke Ye control group. CONCLUSION: JSL has the effect of resolving phlegm as well as improving human immunological and pulmonary ventilatory functions.

Aged↗
PubMed1996

Characterization and site-directed mutagenesis of aspen lignin-specific O-methyltransferase expressed in Escherichia coli.

Aspen lignin-specific caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase (EC 1.2.1.68) was expressed in an active form in Escherichia coli using pET-23 vector. Two steps were used to purify (Phenyl Sepharose and S-adenosylhomocysteine-agarose chromatographies) enzyme to homogeneity. O-Methyl-transferase has a subunit of 40 kDa and native gradient gel electrophoresis indicated the active form is a dimer. Substrate specificity was investigated using over 20 phenolic compounds, which defined the nature of the substrate binding site and required substrate characteristics such as a hydroxyl group para to the side chain. Enzyme accommodates large substrates well if the side chain contains the trans-double bond found in lignin precursors. Kinetically S-adenosyl-L-methionine must bind before phenolic substrate; however, S-adenosyl-L-homocysteine and phenolic substrate or product can form stable complexes complicating the kinetic mechanism. The role of thiol side chain(s) in the catalytic mechanism was investigated since the enzyme is inhibited by p-chloromercuribenzoate. Of nine cysteine residues in the enzyme's sequence, only cysteine residues at positions 276 and 283 are invariant among higher plant O-methyltransferases of this class. These residues were replaced by serine and alanine, singly and in combination, using site-directed mutagenesis. All combinations of cysteine replacements at positions 276 and 283 yielded enzyme virtually as active as wild-type and all were still sensitive to thiol inhibition. We concluded that thiol(s) were not important in the catalytic mechanism of this class of O-methyltransferases and sensitivity to the large thiol inhibitor was probably due to reaction of cysteine thiol(s) near the surface which sterically hindered the active site.

Amino Acid Sequence↗
PubMed1996

The association of cardiac dystrophin with myofibrils/Z-disc regions in cardiac muscle suggests a novel role in the contractile apparatus.

Dystrophin serves a variety of roles at the cell membrane through its associations, and defects in the dystrophin gene can give rise to muscular dystrophy and genetic cardiomyopathy. We investigated localization of cardiac dystrophin to determine potential intracellular sites of association. Subcellular fractionation revealed that while the majority of dystrophin was associated with the sarcolemma, about 35% of the 427-kDa form of dystrophin was present in the myofibrils. The dystrophin homolog utrophin was detectable only in the sarcolemmal membrane and was absent from the myofibrils as were other sarcolemmal glycoproteins such as adhalin and the sodium-calcium exchanger. Extraction of myofibrils with KC1 and detergents could not solubilize dystrophin. Dystrophin could only be dissociated from the myofibrillar protein complex in 5 M urea followed by sucrose density gradient centrifugation where it co-fractionated with one of two distinctly sedimenting peaks of actin. Immunoelectron microscopy of intracellular regions of cardiac muscle revealed a selective labeling of Z-discs by hystrophin antibodies. In the genetically determined cardiomyopathic hamster, strain CHF 147, the time course of development of cardiac insufficiency correlated with an overall 75% loss of myofibrillar dystrophin. These findings collectively show that a significant pool of the 427-kDa form of cardiac dystrophin was specifically associated with the contractile apparatus at the Z-discs, and its loss correlated with progression to cardiac insufficiency in genetic cardiomyopathy. The loss of distinct cellular pools of dystrophin may contribute to the tissue-specific pathophysiology in muscular dystrophy.

Amino Acid Sequence↗
PubMed1996

Oxygen tension profiles in isolated hamster retractor muscle at different temperatures.

Oxygen tension (P0(2)) profiles within unperfused hamster retractor muscles were obtained at 25, 30, and 37 degrees by using sharpened, recessed oxygen microelectrodes. The microelectrode was driven vertically into freshly excised muscle lying on a flat, impermeable boundary inside a diffusion chamber. Intramuscular P0(2) profiles were measured as a function of electrode depth in 10-mu m steps during both inward and outward penetrations when the upper surface of the muscles was exposed to humidified gases containing 10, 21, 50, and 100% 0(2). The ratio of the 0(2) consumption (M) to the 0(2) permeability (K, Krogh diffusion coefficient = D alpha, diffusion coefficient-solubility product) was estimated by curve-fitting the experimental steady-state distribution of 0(2) through muscles to the analytic solution of the diffusion equation assuming that M obeys zero-order kinetics and K is constant, uniform, and independent of P0(2). The ratios of M/K were independent of temperature and were found to be independent of surface P0(2) and muscle thickness. The average value of M/K was 3.9 +/- 0.45 (SE; n = 30) x 10(5) mm Hg/cm(2), which is consistent with that estimated from previous measurements of M and D using different non-steady-state techniques (Bentley et aL, 1993). These results are consistent with other in vitro 0(2) consumption measurements (Sullivan and Pittman, 1984) and do not provide evidence for nonclassical respiratory activity in resting mammalian skeletal muscle.

Animals↗
PubMed1996

Detection of hepatitis E virus RNA in stools and serum by reverse transcription-PCR.

Stools and sera collected during an experimental hepatitis E virus (HEV) infection in monkeys and collected from humans with acute HEV infections during epidemic and sporadic cases were analyzed by reverse transcription-PCR. Two methods for RNA purification were compared. Proteinase K digestion and phenolchloroform extraction were more efficient than guanidinium isothiocyanate extraction in improving the sensitivity and specificity for the detection of HEV genomes.

Animals↗