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Biomedical subjects

M Shen

Publications and source records attributed to M Shen.

At least 127 records · Page 7Linked to original sources
PubMed1994

Construction and expression of high efficiency expressing plasmid of transforming growth factor alpha-Pseudomonas aeruginosa exotoxin fusion protein TGF alpha-PE40.

The XbaI/EcoRI cleaved TGF alpha-PE40 gene from plasmid pXY382 was inserted into the same cloning site of the expression vector pCB604 resulting in the plasmid p2X-TP1. E. coli BL21 (lambda DE3) cells were transformed with the p2X-TP1 and then induced with IPTG. The product expressed was accumulated mainly in the form of inclusion bodies. The expression level was closely related to the cell density, induction temperature and medium but not to the inductor dosage and the induction period within certain range. The expressed amount of the fusion protein TGF alpha-PE40 was about 50 mg/L.

Cloning, Molecular↗
PubMed1993

[Phosphocalcium metabolism in patients with calcified valvular bioprosthesis].

Calcium and gla-protein content are increased in the calcifications of cardiac bioprostheses. Such calcifications are more frequent during growth, pregnancy and renal failure when bone gla-protein levels are elevated. We investigated whether bone gla-protein and other markers of calcium metabolism play a role in bioprostheses calcifications. Forty-seven patients were separated into 2 groups according to the presence (group A, n = 9) or absence (group B, n = 38) of bioprostheses calcifications, as assessed by echo-doppler and surgery. Plasma levels of calcium, phosphorus, magnesium, creatinine and alkaline phosphatases were measured by standard laboratory methods, parathormone and those of bone gla-protein by specific radioimmunoassays. Results (mean +/- SEM) were compared (group A versus group B, P < 0.01) using Student's test and one-factor variance analysis (ANOVA). Age was similar in both group (53 +/- 12.9 vs 50 +/- 12.3 yrs), whereas duration of implant was greater in group A (104 +/- 12.4 vs 66 +/- 6.5 months, P < 0.01). No statistically significant difference was found between group A and B concerning biochemical and/or hormonal markers of calcium metabolism. These negative results merit to be discussed, and further studies will be needed to explore the potential role of circulating bone gla-protein in bioprostheses calcifications.

Aortic Valve↗
PubMed1993

Effects of copper coordinate complexes on the scavenging of reactive oxygen species.

Effects of a 20-membered macrocyclic bicopper complex and dioxotetramine copper complexes with linear or cyclic structure on the scavenging of ROS have been studied by ESR. The results indicated that all three copper coordinate complexes have SOD mimetic activity. The dioxotetramine copper complex with linear or cyclic structure did not have the scavenging effect on .OH produced by H2O2-Fe++ and 1O2 produced by the H2O2-NaOCl system, but the 20-membered macrocyclic bicopper complex was found to be capable of depressing the intensity of the ESR spectrum of the adduct formed from TMP and 1O2 as well as making the spectrum of DMPO-OH adduct splittings. This fact may suggest that there are interactions between the ROS and 20-membered macrocyclic ring in the SOD mimic.

Cells, Cultured↗
PubMed1993

Assay for recombinant and native human intraacrosomal antigen SP-10.

PROBLEM: To develop a method to measure a recombinant sperm protein, SP-10, during scale up and purification for a contraceptive vaccine formulation. METHOD: A quantitative assay method for the human intraacrosomal protein SP-10 was developed utilizing the format of indirect capture enzyme-linked immunosorbent assay (ELISA). A SP-10 specific monoclonal antibody mAb, MHS-10, was used as the capture antibody. Two recognition reagents, a rabbit polyclonal anti-SP-10 antisera (pAb) and a biotin-labeled mAb, MHS-10, were used as the recognition antibodies, respectively. A SP-10 recombinant fusion protein consisting of 125 SP-10 amino acids linked to glutathione transferase was used as a working SP-10 standard. The coefficient of variance for the assay system using the rabbit pAb was in the range of 0.099 to 0.157, and for the assay system using the biotinylated mAb MHS-10 was in the range of 0.081 to 0.084. RESULTS: Employing biotinylated MHS-10 as the recognition antibody, it was found that the native SP-10 molecule had more than one MHS-10 epitope. The concentration of SP-10 in a pool of human sperm extracts was found to be approximately 1% of the total proteins, assayed by both of the recognition antibody systems. CONCLUSIONS: The assay system described is useful to monitor the yield of recombinant SP-10 during scale-up production of the SP-10 vaccine.

Acrosome↗
PubMed1992

Experimental study of the protective effect of intermittent hepatic pedicle clamping in the rat.

The tolerance of the liver to ischaemia during intermittent clamping of the hepatic pedicle was compared with that during a continuous Pringle manoeuvre. Three groups of rats undergoing total durations of clamping of 60, 90 and 120 min were studied. A temporary peroperative portacaval shunt was used to exclude the effects of splanchnic venous stasis and allow independent study of the effects of hepatic ischaemia. In each group, three methods of portal clamping were evaluated: a continuous Pringle manoeuvre (n = 10), a 30-min intermittent clamping (n = 10) and a 15-min intermittent clamping (n = 10). The clamp release time between the periods of liver ischaemia was 5 min. Survival at day 7 and postoperative changes in liver function (transaminase enzymes, bilirubin, bromsulphthalein elimination, liver adenosine 5'-triphosphate levels) were recorded. Intermittent clamping of the pedicle was tolerated significantly better than continuous clamping. This method optimizes the ability of the liver to tolerate extended periods of ischaemia. For a given duration of ischaemia, no additional improvement could be produced by shortening the intermittent clamping period from 30 to 15 min. These data suggest that, when the Pringle manoeuvre is used, it should be applied intermittently rather than continuously.

Animals↗
PubMed1992

Inhibition by germanium oxide of the mutagenicity of cadmium chloride in various genotoxicity assays.

The effects of germanium oxide on the genotoxicity of cadmium chloride were investigated. The incorporation of [3H]thymidine into testicular DNA was inhibited in mice injected ip with 1.35, 1.80 or 2.70 mg cadmium chloride/kg body weight. Germanium oxide (0.05 or 0.1 mg/kg body weight, sc) alone did not affect [3H]thymidine incorporation into testicular DNA but 0.05 mg germanium oxide/kg antagonized the inhibitory effect of 1.35 mg cadmium chloride/kg. However, combinations of the other doses of the two compounds did not show statistically significant antagonistic effects. Cadmium chloride significantly increased the frequencies of micronucleus formation in polychromatic erythrocytes, and of chromosome aberrations in the bone marrow of mice treated with 0.7, 1.4 or 2.7 mg/kg body weight, in a dose-related manner. These effects were inhibited by germanium oxide at doses of 0.1 or 0.5 mg/kg body weight, although germanium oxide alone did not affect micronucleus formation or the chromosome aberration rate. Cadmium chloride produced a dose-related increase in the frequency of sister chromatid exchanges in cultured human lymphocytes at concentrations of 5, 10 or 50 mumol. This effect was also inhibited by germanium oxide (0.05 or 0.1 mumol), although germanium oxide alone had no effect. There was a dose-related increase in the frequency of sperms with abnormal head morphologies from mice treated with 0.6, 1.1 or 2.2 mg cadmium chloride/kg body weight and this too was antagonized by the injection of germanium oxide (0.1 or 0.5 mg/kg body weight). Germanium oxide alone did not affect the frequency of sperm-head abnormalities.

Animals↗
PubMed1992

The inhibitory effects of 21 mimics of superoxide dismutase on luminol-mediated chemiluminescence emitted from PMA-stimulated polymorphonuclear leukocyte.

Four groups comprising 21 superoxide dismutase (SOD) mimics synthesized by us were comparatively studied for their inhibitory effects on luminol-mediated chemiluminescence emitted from phorbol myristate acetate (PMA)-stimulated polymorphonuclear leukocyte (PMNL). Among these groups, 20-membered macrocyclic bicopper(II) complexes and 13-membered macrocyclic dioxotetramine copper(II) complexes exhibited relatively higher activities of scavenging reactive oxygen species (ROS) produced by PMA-stimulated PMNL as compared with polyamine Cu(II)-Zn(II) complexes and copper(II) complexes of bis-shiff-base. Moreover, distinctly different effects of SOD mimics in the biological system have been found even in the same group. It is suggested that the biological effects of some SOD mimics are related to their structures.

Chelating Agents↗
PubMed1992

Analysis of mutations at the neurofibromatosis 1 (NF1) locus.

A panel of 200 unrelated NF1 individuals has been screened for mutations using a panel of specific clones for the entire gene. DNA analysis on conventional Southern blots indicated that (20) 10% of NF1 patients showed aberrant bands. Small lesions involving nucleotide alterations were detected in a further 10 patients; 5 of these alterations have been fully characterised and are the novel mutations in the NF1 gene. A number of mutations were identified in exon 2. Identical mutations in this exon in two unrelated individuals involved an insertion of cytosine into codon 5662 and resulted in an inappropriate stop codon. This mutation also created a new MnlI site. Another novel mutation in exon 2 resulted from the insertion of thymidine at nucleotide 5678, which also created an inappropriate stop codon. We have so far completed the screen of exons 1-9 of the NF1 gene for the identification of mutations and have found no evidence of clustering of such mutations in the gene.

Amino Acid Sequence↗
PubMed1990

A further study on capillary-like bile ductules proliferation in chronic active hepatitis.

64 cases of chronic active hepatitis (CAH) and 84 cases of non-CAH liver diseases were studied with keratin stain. The capillary-like bile ductules (CLBD) were proliferating and their morphology was identical to that with Type V collagen stain reported before. CLBD proliferation were more marked in CAH than in other liver diseases, and it was considered to be one of the characteristics of CAH and could be used for differential diagnosis. The ultrastructure of CLBD was specific in morphology. The HBV-DNA in CLBD shown by the technique of in situ hybridization suggested that HBV might infect the cells of CLBD.

Bile Canaliculi↗
PubMed1987

Plasma lipid and lipoprotein concentrations in Chinese males with coronary artery disease, with and without hypertension.

Plasma lipid and lipoprotein concentrations were determined in 125 Chinese males with a medical history and electrocardiographic abnormalities consistent with the diagnosis of coronary artery disease (CAD). All subjects underwent coronary arteriography, and patients were divided into 3 groups based upon the results of the coronary arteriograms: 1) patients with a negative angiogram (CAD-, n = 30), without hypertension; 2) patients with a positive angiogram, without hypertension (CAD+, n = 70); and 3) patients with a positive angiogram, who had hypertension (CAD + HT, n = 25). Mean fasting plasma lipid and lipoprotein concentrations of these 3 groups of patients were compared to values in age and weight-matched groups of normal individuals (n = 80) and untreated patients with hypertension and no evidence of CAD (HT, n = 20). The results indicated that total plasma triglyceride, cholesterol, and LDL-cholesterol levels were significantly higher (P less than 0.001) than normal in patients with CAD+ and CAD + HT, whereas only plasma cholesterol levels were higher than normal in patients with HT. Although patients with CAD- had values intermediate between normal and CAD, the differences were not statistically significant. In addition, the ratio of LDL to HDL-cholesterol was significantly increased (P less than 0.05-0.001) above normal in patients with CAD+, CAD + HT, and HT. As before, the values in patients with CAD- were intermediate. These data document the presence of multiple abnormalities of lipid and lipoprotein concentration in patients with angiographic evidence of CAD, whether or not they were hypertensive. Furthermore, abnormalities in lipid and lipoprotein metabolism were seen in patients with hypertension alone.

Aged↗
PubMed1986

Molecular diversity of HLA-DR4 haplotypes.

Complementary DNA (cDNA) clones encoding beta chains of the DR and DQ regions and alpha chains of the DQ region were isolated and sequenced from four homozygous DR4 cell lines of different HLA-D types: GM3103(Dw4), FS(Dw10), BIN(Dw14), and KT3(Dw15). When compared with each other and with a previously published sequence from a DR4 (Dw13 cell line), the variability of DR beta 1 gene products is generally restricted to the region around amino acid position 70, with an additional polymorphism at position 86. Many of these differences, including an unusual amino acid substitution at position 57 in the Japanese cell line KT3(Dw15), may be due to gene conversion events from the DR beta 2 or DX beta genes. In contrast, DR beta 2 molecules are identical in Dw15, Dw10, and Dw4 cell lines. DQ beta chains isolated from GM3103(Dw4), FS(Dw10), and BIN40(Dw14) are also identical. However, the DQ beta sequence from cell line KT3(Dw15) differs substantially from all other previously reported DQ beta alleles, consistent with its serological designation, DQ "blank." The first domain sequences of DQ alpha chains were identical in all four cell lines. The data suggest that relatively circumscribed amino acid changes in the DR beta 1 molecule are responsible for the HLA-D typing differences between some haplotypes.

Base Sequence↗
PubMed1986

The effect of needle stimulation of acupuncture loci Tienshu (St-25) Chung-Wan (CV-12) on the immune response in sensitized mice against experimental cholera.

The effects of stimulation of acupuncture loci from Tien-Shu (St-25) piercing through Chung-Wan (CV-12) on the Leukocytes and immune response were assessed in mice (that is, the anatomical equivalent of these loci of human acupuncture points). The leukocyte count increased and reached its highest level two hours after needling, then restored to normal level 24 hours later both in normal mice and immunized mice. Statistical analysis showed no significant variation on the lymphocyte/total leukocyte ratio in normal mice or immunized mice before, during and after needling. The effects of acupuncture on the production of anti-Vibrio cholerae in serum of the immunized mice can not be found, but produced positive effects in small intestine both on production of SIgA and antagonism to cholera. Furthermore these enhanced effects were higher by needling after oral (p.o.) boosting than that before oral boosting.

Acupuncture Therapy↗
PubMed1984

Immunosuppressive action of Qinghaosu.

Qinghaosu, isolated and purified from the Chinese herb, Artemisia annua Linn, and identified as a sesquiterpene with a peroxide bridge and lactone structure, is a highly potent and non-toxic new antimalaria drug. This paper reports the immunosuppressive action of its water soluble derivative (hemisuccinate NA, QHS). The remarkable suppression by QHS of the in vitro 3HTdR incorporation by mitogen-stimulated mouse spleen cells and human peripheral lymphocytes, as well as the spontaneous incorporation by mouse thymocytes and blood cells from some leukemia patients is presented and its characteristics are described. The in vivo effect as shown by quantitative PFC is studied and the difference between the present in vitro and in vivo effects is investigated. The possible mechanism of inhibition and discrepancy in effects are discussed.

Animals↗