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Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 919 records · Page 51Linked to original sources
PubMed1991

[The identification of ephedrine and its analogues in urine by gas chromatography].

A sensitive and reliable method of analysis for ephedrine and its analogues was established by using GC and GC-MS. The columns used for both GC and GC-MS were HP-5, and the carrier gas was helium. NPD was used as the detector for GC. The urine sample was extracted with ether and submitted to GC. If positive, it was then submitted to GC-MS to identify its structure. The detection limits for ephedrine and its analogues are lower than 200 ng/ml urine. The recoveries are above 80%.

Chromatography, Gas↗
PubMed1991

A study on the mutagenicity of 102 raw pharmaceuticals used in Chinese traditional medicine.

The mutagenic potential of traditional Chinese drugs was studied. After extraction with boiling water and frozen vacuum drying, preparations from 102 raw drugs were tested with the Ames test, and the micronucleus and chromosomal aberration assays in mice in vivo. Astragalus mongholicus Bunge (+S9), Sophora japonica L. (+/- S9) and Eucommia ulmoides Oliv. (+/- S9) were found to significantly induce His+ revertants in Salmonella typhimurium TA98 and/or TA100. Besides these 3, 10 other extracts were positive in the chromosomal aberration and micronucleus assays in mice. They are Datura metal L., Artemisia capillaris Thunb., Carthamus tinctorius L., Forsythia suspensa Thumb., Rehmannia glutinosa f. Hueichingensis (fermented), Paeonia suffruticosa Andr., Platycodon grandiflorum Jacq. DC., Cinnamomum mairei Levl., Notopterygium incisium Ting., and Sophora flavescens Ait. The relevance of these findings is discussed.

Animals↗
PubMed1990

Two mechanisms of inhibition by prostaglandin E2 of hormone-dependent cell cAMP in the rat collecting tubule.

The effect of exogenous prostaglandin E2 (PGE2) on hormone-dependent adenosine 3',5'-cyclic monophosphate (cAMP) accumulation was investigated by microradioimmunoassay in collecting tubules microdissected from the cortex (CCT) or outer medulla (MCT) of the rat kidney. Two phosphodiesterase inhibitors were used: either a xanthine derivative (isobutyl-methylxanthine (IBMX, 1 mM] active on all forms of phosphodiesterase or Ro 20-1724 (50 microM) active on the phosphodiesterase type III. A prostaglandin synthesis inhibitor was added to all media. In the presence of IBMX, 0.3 microM PGE2 inhibited by 39.1% the response induced in the CCT by the beta-adrenergic agonist isoproterenol (1 microM). Under the same experimental conditions, arginine vasopressin (AVP)-stimulated cAMP accumulation in CCT or MCT was not affected by PGE2. In the presence of Ro 20-1724, 0.3 microM PGE2 did not modify the response to 1 nM AVP in CCT but inhibited this response in MCT samples (mean inhibition: 52.7%). The inhibition by PGE2 was dose dependent with a maximum at 0.3 microM, observed for all concentrations of AVP tested (from 50 pM to 1 nM) and did not affect the concentration of AVP inducing half-maximal cAMP accumulation. In a second experimental series performed in the presence of adenosine deaminase, an A1-adenosine agonist [theta)-N6-(R-phenylisopropyl)adenosine (PIA, 0.1 microM] also decreased the response to 1 nM AVP in the MCT. The addition of an A1-adenosine antagonist relieved the effect of PIA but did not modify the inhibition observed with PGE2. Thus PGE2 decreased the synthesis of cAMP in beta-adrenergic sensitive cells in rat CCT and might affect the catabolism of AVP-dependent cAMP level rather than its synthesis in rat MCT.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Evidence for a close link between the thyroid hormone transport system and the aromatic amino acid transport system T in erythrocytes.

The transport of [125I]triiodothyronine ([125I]T3) and [3H]tryptophan ([3H]Trp) by washed rat erythrocytes was studied at 25 degrees C in the presence of leucine in order to block the neutral amino acid transport system L. Eadie-Hofstee plots of initial velocity data gave the following values of Km (micromolar) and Vmax (nanomole/min/10(8) cells): 0.122 +/- 0.007 and 0.140 +/- 0.021 for T3, and 558 +/- 28 and 17.4 +/- 2.3 for Trp (n = 5). The Trp transport system in rat erythrocytes is similar to the human erythrocyte aromatic amino acid-specific system T described by Rosenberg et al. (Rosenberg, R., Young, J. D., and Ellory, J. C. (1980) Biochim. Biophys. Acta 598, 375-384). Unlabeled aromatic amino acids (e.g. Trp, phenylalanine, tyrosine) competitively inhibited [125I]T3 uptake and unlabeled iodothyronine analogues (e.g. T3, D-T3, thyroxine, thyronine) competitively inhibited [3H]Trp uptake. The inhibition constants of these competitors measured with each labeled substrate were highly correlated. N-Ethylmaleimide irreversibly inhibited T3 and Trp transport and each substrate protected the transport system of the other from inactivation by N-ethylmaleimide. The Vmax of T3 and Trp transport by human erythrocytes were 500 and 120 times lower, respectively, than those of rat erythrocytes (0.30 and 126 pmol/min/10(8) cells, respectively). The T3 and Trp transport activities of sheep erythrocytes were undetectable. These results indicate that T3 and Trp either share a common multi-specific transport system or are transported by closely linked systems which interact in the erythrocyte membrane.

Animals↗
PubMed1990

The triiodothyronine carrier of rat erythrocytes: asymmetry and mechanisms of trans-inhibition.

The kinetic properties of the carrier-mediated transport of 3,5,3'-triiodo-L-thyronine (T3) in washed rat erythrocytes were investigated (1) by studying the effects of trans unlabelled T3 on influx and efflux of labelled substrate and (2) by testing some predictions of the theory of Lieb and Stein [1974) Biochim. Biophys. Acta 373, 165-177). The carrier was trans-inhibited by T3 on both sides of the membrane. Under zero-trans conditions, the carrier displayed asymmetrical properties, the Michaelis constant and the maximal velocity being more than 6-times higher for influx than for efflux. Under equilibrium-exchange conditions, the Michaelis constant was lower than the zero-trans values, as expected when trans-inhibition occurs. This kinetic behaviour is consistent with a carrier which is accessible to T3 simultaneously from both sides of the erythrocyte membrane.

Animals↗
PubMed1990

Mechanism of testicular atrophy induced by di-n-butyl phthalate in rats. Part 2. The effects on some testicular enzymes.

A single oral dose of di-n-butyl phthalate (DBP) to male rats caused histologically a sloughing of the germ cells at 6 h. On Days 1 and 2 more severe sloughing was seen, followed by atrophy and the dissociation of the germ cells from the Sertoli cells and the spermatogonia. Biochemically, there was elevation of gamma-glutamyl transferase, a decrease in sorbitol levels at 3 h and a decrease in the activity of aldose reductase at 6 h, in the testes of treated rats. This was followed by decreases in fructose levels and increases in the activity of lactate dehydrogenase (LDH) and in lactate levels at 12 h, and decreases in the activities of sorbitol dehydrogenase and succinate dehydrogenase on Day 2. LDH isoenzymes 4 and 5 increased at 6 h prior to the increase in lactate levels. Increases in the levels of inositol and the activities of alkaline phosphatase and lactate dehydrogenase were also observed. Thus, these data suggest that DBP-induced testicular toxicity is caused by a shortage of energy fuels from glucose metabolism or by an anoxia.

Animals↗
PubMed1990

Mechanisms of testicular atrophy induced by di-n-butyl phthalate in rats. Part 3. Changes in the activity of some enzymes in the Sertoli and germ cells, and in the levels of metal ions.

A single oral dose of di-n-butyl phthalate (DBP) to male rats caused a sloughing of the germ cells at 6 h, with more severe sloughing at 24 and 48 h. DBP is metabolized to mono-n-butyl phthalate (MBP), which is transported through the blood-tubular barrier into the seminiferous lumen. MBP is incorporated into the lumen at a maximum rate between 1 and 3 h after dosing with DBP. MBP caused decreases in the activities of succinate dehydrogenase in the Sertoli cells and sorbitol dehydrogenase in the germ cells, an increase in the activity of lactate dehydrogenase (LDH) in the germ cells and in the seminiferous lumen and a decrease in testicular iron levels.

Aldehyde Reductase↗
PubMed1990

Isolation of a highly enriched plasma membrane fraction of Trypanosoma brucei by free-flow electrophoresis.

A procedure is described whereby a highly enriched plasma membrane fraction was isolated from Trypanosoma brucei by the technique of preparative free-flow electrophoresis. The purity of the plasma membrane fraction was monitored by electron microscopy and by marker enzymology, and is compared to those obtained by previous methods. Proteins associated with plasma membrane fraction were analyzed by SDS-PAGE and phase separated in Triton X-114.

Animals↗
PubMed1990

Paraben preservatives but not succinylcholine are cerebral vasodilators in vitro.

Since the increase in intracranial pressure produced by succinylcholine is temporally associated with intravenous administration, we investigated in vitro a possible direct cerebrovascular effect of this nicotinic drug. Isometric responses were recorded from dog and guinea pig basilar artery rings suspended in modified Krebs' solution at 37 degrees C. After precontracting with a voltage (KCl)- or a receptor (5-hydroxytryptamine)-mediated agonist, cumulative concentration-relaxation curves were established for: pure succinylcholine; Quelicin from multidose vials containing 20 mg/ml succinylcholine, 1.8 mg/ml methylparaben, and 0.2 mg/ml propylparaben; Anectine from single-dose vials containing 20 mg/ml succinylcholine; multidose Anectine containing 20 mg/ml succinylcholine and 1.0 mg/ml methylparaben; and methylparaben and propylparaben alone. When required, the endothelium of dog artery was removed by gentle mechanical rubbing and the response to the drugs reevaluated. Both Quelicin and multidose Anectine produced statistically significant (P less than 0.05) relaxation; Quelicin was the more potent of the two. Methylparaben and propylparaben produced relaxation in an additive manner and completely accounted for the relaxation produced by Quelicin and multidose Anectine. The vascular relaxation was found to be independent of the presence of a functional endothelium. Consistent with a nicotinic induced contraction, pure succinylcholine maintained vessel tone. It is concluded that the pharmaceutically ubiquitous preservatives methylparaben and propylparaben but not pure succinylcholine have vasoactive properties in vitro.

Animals↗
PubMed1990

Synthesis of functional mRNA in mammalian cells by bacteriophage T3 RNA polymerase.

We found that the 5' nontranslated leader sequence from encephalomyocarditis virus (EMCV) allowed transcripts that were synthesized by the T3 RNA polymerase in mammalian cells to be translated in a cap-independent fashion. Stable mouse cell lines that carry the T3 RNA polymerase gene expressed the chloramphenicol acetyltransferase (CAT) gene under the control of a phage promoter when the CAT gene was fused to the EMCV leader and introduced into the cells by transient DNA uptake. The level of gene expression in such cells was similar to or greater than that observed with a conventional transient expression vector that is dependent on transcription by the host RNA polymerase II. Expression of the EMCV-CAT fusion gene was stimulated by cotransfection of the cells with a gene that encodes the poliovirus protease 2A protein (which inhibits cap-dependent translation), demonstrating that the EMCV-CAT fusion gene was expressed in a cap-independent fashion. Introduction of both the T3 RNA polymerase gene and the EMCV-CAT fusion gene into a variety of cultured mammalian cell lines (HeLa, BSC40, Ltk-, NIH 3T3, and C127) demonstrated that the T3-EMCV expression system functions in a broad range of cell types.

Animals↗
PubMed1990

[Low birth weight infant and its risk factors].

A case-control study on low birth weight was conducted in Qiaokou District, Wuhan City in 1987. 162 low birth weight infants were included with 324 controls. The controls were matched by stratified birth weights (2500-2999g, 3000-3999g). The results showed that beside incomplete pregnancy, severe edema-proteinuria-hypertension syndrome (OR 5.26, 8.18), insufficient prenatal care (OR 5.90, 10.04), heavy physical work during third pregnancy trimester (OR 2.84, 6.43), undernutrition (OR 3.40, 18.50) and cigarette smoking (OR 1.41, 5.50) are risk factors to low birth weight. These relationships became more evident when the low birth weight infants were compared with the higher birth weight infants of Control Group 2. This suggests that treating pregnant complications and strengthening prenatal care must be done to reduce the birth rate of low birth weight infants.

Female↗
PubMed1990

[Study on metabolism of phenmetrazine-like drugs and their metabolites].

We have studied the metabolism of phenmetrazine, phendimetrazine and morazone, and their metabolites in urine. A sensitive, specific method using GC/NPD was applied to the determination of the rate of excretion of the drugs quantitatively, diphenylamina being used as the internal standard. The ether extract was derivatized with TFAA reagent, the metabolites and their TFA derivatives were identified by GC/NPD and GC/MSD methods. Norephedrine, cathine, ephedrine and pseudoephedrine in small amount were identified.

Analgesics, Opioid↗
PubMed1990

[Investigation on resources of the Chinese drug beimu in Gansu Province].

Based on a resources investigation and taxonomic research on the medicinal plants of Fritillaria from Gansu Province. Nine species one variety and one cultivation variety have been reported. Records and distribution of the species, together with a key for the species and a key for the powdered drug have been furnished as well.

China↗
PubMed1990

[Enkephelinase inhibitors acetorphan and SCH34826 potentiate the analgesic effect of low frequency electroacupuncture in rats].

Influence of two novel enkephelinase inhibitors, Acetorphan and SCH34826, on the effect of electroacupuncture analgesia (EAA) has been observed in rats. Administered Acetorphan (2.0-4.0 mg/kg, i.p.) or SCH34826 (30-100 mg/kg, p.o.) potentiated and prolonged the effect of 2 Hz EAA significantly in the nonresponder in which an evident analgesic effect can not be induced by 2 Hz electroacupuncture. This means that che non-responder of 2 Hz EAA can be converted into the responder with these two drugs. The non-responder of 100 Hz EAA, however, can not be changed into the responder with Acetorphan. These results again support our previous reports that enkephelin plays an important role in low frequency EAA. Meanwhile, this suggests us a probable route for potentiating acupuncture analgesia in clinical practice.

Acupuncture Analgesia↗