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Biomedical subjects

S Ren

Publications and source records attributed to S Ren.

98 records · Page 6Linked to original sources
PubMed1992

A study of the effect of magnetized water on enzyme activities by potentiometric enzyme electrode method.

A very promising glutamate decarboxylase electrode, which has linear response range of 5.6 x 10(-5)-1.2 x 10(-2) mol/L. Nernstian slope of 50 mV/decade, detection limit of 3.2 x 10(-5) mol/L and response time less than 3 min, has been designed to observe and evaluate quantitatively the effect of magnetized water on enzyme activities by potentiometric enzyme electrode method. It was found that the activity of glutamate decarboxylase can increase by 30% in magnetized water. The mechanism of increased enzyme activity was discussed in the present paper. Such a new finding will probably lead to some new explanations for the physiological and biological mechanism of the effect of magnetized water on living organisms, thus providing a new approach to the study of the effect of magnetized water.

Electrodes↗
PubMed1991

Identification of male-factor semen samples prior to insemination and in vitro fertilization.

Semen analyses carried out as part of the clinical in vitro fertilization or intrauterine insemination protocols provide important information that determine the type of clinical treatment of the male partner and the sperm processing method. It is postulated that the sperm of male-factor patients cannot survive hypoosmotic stress conditions because of defective sperm membrane function. To test this, 0.1 ml of semen from each of 102 patients was placed in 1.0 ml of 150 mosmol/liter eosin citrate fructose solution and incubated for 30 min at 37 degrees C. The percentage viability of the sperm cells was then determined. The results indicated that patients with two or more abnormal semen parameters had a significantly lower percentage viability while in the hypoosmotic solution (40.6 +/- 4.7%), in contrast to non-male-factor patients (69.0 +/- 1.6%). Donor sperm (N = 32) serving as controls (73.3 +/- 2.1%) had a viability in hypoosmotic solution similar to that of non-male-factor patients. The data suggest that sperm of male-factor patients are less able to survive the hypoosmotic stress conditions as shown by the percentage viability in hypoosmotic solution and emphasize the importance of using less stressful sperm processing methods for in vitro fertilization or insemination in these patients.

Cell Membrane↗
PubMed1990

[Role of a virus in hemorrhagic pancreatitis and the therapeutic effect of rhubarb].

The living measles vaccine was injected into both of the main pancreatic duct and the ear vein of the rabbits in the model group. The serum amylase was significantly higher than that of the control saline group (P less than 0.001 after 24h; P less than 0.05 after 48h). The aggregation function of platelets were increased after 24h(P less than 0.01, P less than 0.01) and 48h (P less than 0.01, P less than 0.05) as compared with both two control groups. The blood stasis and hemorrhage of pancreases were observed in the model group. In the treatment group with Rhubarb the increase of serum amylase was much less marked than the control (P less than 0.001 after 24h, P less than 0.05 after 48h). The platelet aggregation reactivity was inhibited (P less than 0.01 after 24h, P less than 0.05 after 48h). The blood stasis and hemorrhage of pancreases were less evident. The results suggested that: (1) the virus may be one of pathogenetic factor of the hemorrhagic pancreatitis; (2) the rhubarb was effective in the treatment of hemorrhagic pancreatitis under our experimental conditions.

Acute Disease↗
PubMedDate not supplied

Resonant field emission through amorphous diamond thin films (a model study).

A model for field emission through an amorphous diamond thin film with defects is constructed. Theoretical study shows that the emission is enhanced by attractive defects which would make the resonant emission observable for films with thickness of about 10nm. The emitted current density in typical parameters is calculated as functions of thickness, field strength and defect density. The energy distribution of emitted electrons is attained.

Journal Article↗
PubMedDate not supplied

Hirulog-like peptide reduces balloon catheter injury induced neointima formation in rat carotid artery without increase in bleeding tendency.

Vascular restenosis is one of the major concerns for the management of coronary artery disease using therapeutic vascular procedures. Treatments with thrombin-specific inhibitors, hirudin or hirulog-1, reduced ischemic events in coronary artery disease patients. Early started and prolonged infusions of these thrombin inhibitors partially prevented balloon catheter injury induced restenosis or neointima formation in experimental animal models, but increased the bleeding tendency. Hirulog-like peptide (HLP) was rationally designed to enhance the inhibition of the binding of thrombin to its receptor with less interruption of coagulation activity in comparison to hirulog-1. A single infusion of HLP for 4 h started 0.5 h before balloon catheter injury reduced neointima formation by 36% in rat carotid artery compared to vehicle controls. Tail bleeding time and activated partial thromboplastin time during HLP infusion were not significantly different from vehicle controls, but were significantly shorter than during heparin or hirulog-1 infusion. HLP treatment attenuated the expression of platelet-derived growth factor in the neointima of injured arteries. HLP also inhibited thrombin-induced thymidine incorporation in cultured baboon aortic smooth muscle cells. The findings suggest that HLP may substantially inhibit balloon catheter injury induced neointima formation without noticeable increase in bleeding tendency in rats. The inhibition by HLP of the expression of platelet-derived growth factor and of the smooth muscle cell proliferation in the vascular wall potentially contributes to the preventive effect of the new thrombin inhibitor on injury-induced neointima formation in the vascular wall.

Angioplasty, Balloon↗
PubMedDate not supplied

G proteins and phospholipase C mediate thrombin-induced generation of plasminogen activator inhibitor-1 from vascular smooth muscle cells.

The present study investigated transcellular signalling mechanism involved in thrombin-induced production of plasminogen activator inhibitor-1 (PAI-1) in cultured vascular baboon aortic smooth muscle cells (BASMC). Treatments with thrombin dose-dependently increased the steady state levels of PAI-1 mRNA and the generation of PAI-1 antigen from BASMC. Thrombin receptor-activating peptide mimicked the effect of thrombin on the generation of PAI-1. Sodium fluoride (1 mM) stimulated PAI-1 generation from BASMC. Pertussis toxin dose-dependently suppressed thrombin-induced increase of PAI-1 generation. Treatment with 5 mM neomycin, 10 microM U73122 or 1 microM calphostin C blocked thrombin-induced PAI-1 generation. Phorbol myristate acetate at 10 nM for 3 h strongly stimulated the generation of PAI-1 from BASMC. Forskolin (100 microM) or 8-bromo-cAMP (100 microM) suppressed thrombin-induced PAI-1 generation. The responses of quiescent BASMC to thrombin or the inhibitors on PAI-1 generation were comparable to that of growing cells. The results of the present study suggest that pertussis toxin-sensitive G proteins and a phospholipase C are involved in thrombin-induced generation of PAI-1 in BASMC, which may transmit signals from occupied thrombin receptor to protein kinase C and thereby increase the generation of PAI-1. Elevated levels of intracellular cAMP may negatively regulate the generation of PAI-1 from vascular SMC.

Animals↗
PubMedDate not supplied

Inhibition of tumor cell growth by Schiff bases of hydroxysemicarbazide.

The inhibitory activities of Schiff bases of hydroxysemicarbazide (HSC) against eight human and murine tumor cell lines and one non-cancer cell line were studied using MTS/PES microculture tetrazolium and methylene blue assays. Compounds 1 (1-[9-(10-methylanthryl)methylene]-4-HSC), 2 (1-[2-hydroxy-3,5-dibromobenzylidene]-4-HSC) and 3 (1-[2,3,4-trihydroxybenzylidene]-4-HSC), which have been shown to be active against murine leukemia L1210 cells in our laboratories, inhibited human leukemia CCRF-CEM cells with similar IC50s ranging from 2.7 to 7.0 microM. Of the compounds tested against attached tumor cell lines (B16, CHO, HT29, ZR75) at 50 microM concentration, compound 1 showed the strongest inhibition, followed by 4 (1-[2-(5-nitrothienyl)methylene]-4-HSC), 2 and 5 (1-[2-hydroxy-3,5-diiodobenzylidene]-4-HSC) with more than 50% inhibition. The IC50s of compound 1 were found to range from 2.7 to 12 microM against the attached tumor cell lines examined. As compared with hydroxyurea, compound 1 had more favorable selectivity against tumor cells. Further more, compound 1 was found to have IC50s of 2.8 and 6.5 microM against hydroxyurea-resistant and gemcitabine-resistant KB cells, respectively, but had no cross-resistance with hydroxyurea and gemcitabine (two known ribonucleotide reductase inhibitors acting at different sites of the same enzyme). In conclusion, several Schiff bases of HSC showed inhibition of tumor cell growth at micromolar concentration and had no cross-resistance with hydroxyurea-resistant KB cells.

3T3 Cells↗