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Biomedical subjects

L L Yang

Publications and source records attributed to L L Yang.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Determination of tetramethylpyrazine and borneol in human plasma by GC-MSD].

A GC-MSD method for the determination of tetramethylpyrazine (TMP) and borneol in plasma is described. TMP and borneol were extracted with hexane-dichloromethane (10:1, V/V). Camphor was used as the internal standard. The average recoveries of TMP and borneol were 87.38% and 97.32% with relative standard deviation 1.90% to 6.21%, respectively. The method was successfully used to determine plasma borneol concentration following sublingual administration of 20 pills of Suxiao Jiuxin Wan to healthy volunteers (n = 10). The pharmacokinetic parameters have been listed in this paper.

Adult↗
PubMed1993

[Determination of pseudoephedrine in human plasma by gas chromatography with a mass selective detector (GC-MSD)].

A specific and sensitive method has been established for the analysis of pseudoephedrine (PE) in human plasma by gas chromatography with a mass selective detector (GC-MSD). PE and ephedrine (E, internal standard) reacted with trifluoroacetic anhydride (TFAA) and the derivatives were separated by a HP-5 capillary column. PE-TFA and E-TFA were quantitatively measured by selected ion monitoring (m/z = 154). The detection limits for E and PE were 1 ng/ml plasma. The recoveries were about 99%.

Delayed-Action Preparations↗
PubMed1993

[The influence of Chinese traditional medicine on the production and activity of interleukin 1 (IL-1)].

Interleukin 1 (IL-1) is a cytokine closely related to the pathogenesis of inflammation and chronic destructive changes in rheumatoid arthritis (RA). Analysis of the effect of antirheumatic drugs on IL-1 production and activity is of great importance in exploring the therapeutic mechanism of RA. The purpose of the present study was to investigate the effect of Chinese herbs (10 prescription and 15 single drugs), which was often used in the treatment of RA, on the production and activity of IL-1. The production of IL-1 was tested through human monocytes stimulated with zymosan and measured by ELISA method; the activity of IL-1 was measured by its effect on the proliferation of murine thymocytes. The results showed that Tripterygium Wilfordii Hook, Tripterygil Hyhoglauci Tetrandrine significantly inhibited both of IL-1 production and IL-1 activity; while Aconiti Tuber, Ephedrae Herba, Atractyloidis Rhizoma, Atractyloidis Lanceae Rhizoma, Ledebouiellae Radix slightly inhibited IL-1 activity but not affecting IL-1 production. The ten prescriptions had no inhibitory effect on both of IL-1 production and IL-1 activity.

Animals↗
PubMed1992

Simultaneous measurement of serotonin, catecholamines and their metabolites in cat and human plasma by in vitro microdialysis-microbore high-performance liquid chromatography with amperometric detection.

A method for the simultaneous measurement of norepinephrine, epinephrine, dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, serotonin and 5-hydroxyindole-3-acetic acid in cat and human plasma by in vitro microdialysis-microbore high-performance liquid chromatography with electrochemical detection is described. The detection limit (signal-to-noise ratio = 3) is about 0.05-0.1 pg per injection. The volume of plasma samples required is very small (< 200 microliters), hence there is minimal blood loss in repeated blood sampling, especially in experiments using small animals. Within 15 min, a fast isocratic separation of these analytes by using a microbore reversed-phase ODS column is achieved, hence over 90 analyses can be performed in a single working day. As microdialysis per se is not destructive to plasma samples, the remaining plasma sample and perfusate can be repeatedly analysed for other substances. This simple, efficient and sensitive method can therefore be used as a routine clinical and basic research technique in the investigation of blood biogenic amines and their metabolites.

Animals↗
PubMed1992

Genetic toxicology of acrylic acid.

Acrylic acid was tested for gene mutations in the in vitro CHO/HGPRT assay, for chromosome aberrations in CHO cells in culture, and for potential to induce unscheduled DNA synthesis in rat hepatocytes in culture. In vivo assays performed included the Drosophila sex-linked recessive lethal assay by both the feeding and injection routes, the in vivo cytogenetic assay in rat bone marrow cells after both a 1-day and 5-day oral dosing regimen, and a dominant lethal assay in mice by both an acute and 5-day dosing regimen. All results were negative (non-mutagenic) except for the in vitro chromosome aberration assay. This latter result is consistent with the previously reported possible clastogenic activity suggested by the results of the mouse lymphoma L5178Y TK locus assay in which a predominance of small-colony mutants was observed (Moore et al., Environmental and Molecular Mutagenesis 1988, 11, 49-63). The rapid clearance of acrylic acid in animals and the weight of evidence of genetic toxicity testing, including negative in vivo data in both somatic and germ cells, indicate a lack of genetic toxicity of acrylic acid in vivo.

Acrylates↗
PubMed1992

Study of the activities of Chinese herb Viscum alniformosanae Part II: The components of conditioned medium produced by Viscum alniformosanae-stimulated mononuclear cells.

The human promyelocytic cell line HL-60 can be induced to monocytoid terminal differentiation by several conditioned media produced by lectin-stimulated mononuclear cells. We reported previously that a 572-conditioned medium (CM) secreted from viscum alniformosanae-stimulated mononuclear cells also had the capacity of inducing HL-60 leukemic cells into mature monocytes. In the present study, we showed that 572-CM did not contain IFN-r, TNF, IL-1 and IL-2 as determined by using ELISA tests. This CM was unable to induce granulocyte-macrophage colony formation. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was used to detect the components of this CM. After running the acrylamide gels, a wide band protein, in the 65-80 kd range was obtained and it was different from those of other mitogens.

Cell Differentiation↗
PubMed1992

[Studies on the analytical method of a new anti-arrhythmic guan-fu base A in rabbit plasma].

Guan-fu base A, a new antiarrhythmic alkaloid with a structure of C20-diterpenoid, was first isolated from the tuber of Aconitum coreanum (Levl.) Raipaics in China in 1966. An analytical method of GC-ECD has been established in this paper for the determination of its concentration in rabbit plasma in order to study its pharmacokinetics in preclinical pharmacology. Guan-fu base A and the internal standard alprenolol (ALP) was found to react rapidly and quantitatively with trifluoroacetic anhydride (TFAA) to produce derivatives GFA-TFAA and ALP-TFAA which were identified by GC-MSD. An optimal GC-ECD system for the separation and determination of the derivatives following the sample preparation was established. There was a wide linear range of the method from 10-2 x 10(4) ng/ml (r = 0.9984). The average recovery of Guan-fu base A from the spiked plasma was 97.52%. The coefficient of variation of between-day and within-day were less than 9% and 7%, respectively. The method was used to determine Guan-fu base A in the plasma of 15 rabbits following intravenous administration of 3 dosages of 0.4, 2 and 10 mg per kg of body weight.

Alkaloids↗
PubMed1991

CMP-N-acetylneuraminic acid synthetase of Escherichia coli: high level expression, purification and use in the enzymatic synthesis of CMP-N-acetylneuraminic acid and CMP-neuraminic acid derivatives.

The gene encoding CMP-N-acetylneuraminic acid (CMP-NeuAc) synthetase (EC 2.7.7.43) in Escherichia coli serotype O7 K1 was isolated and overexpressed in E.coli W3110. Maximum expression of 8-10% of the soluble E.coli protein was achieved by placing the gene with an engineered 5'-terminus and Shine-Dalgarno sequence into a pKK223 vector derivative behind the tac promoter. The overexpressed synthetase was purified to greater than 95% homogeneity in a single step by chromatography on high titre Orange A Matrex dye resin. Enzyme purified by this method was used directly for the synthesis of CMP-NeuAc and derivatives. The enzymatic synthesis of CMP-NeuAc was carried out on a multigram scale using equimolar CTP and N-acetylneuraminic acid as substrates. The resultant CMP-NeuAc, isolated as its disodium salt by ethanol precipitation, was prepared in an overall yield of 94% and was judged to be greater than 95% pure by 1H NMR analysis. N-Carbomethoxyneuraminic acid and N-carbobenzyloxyneuraminic acid were also found to be substrates of the enzyme; 5-azidoneuraminic acid was not a substrate of the enzyme. N-Carbomethoxyneuraminic acid was coupled to CMP at a rate similar to that observed with NeuAc, whereas N-carbobenzyloxyneuraminic acid was coupled greater than 100-fold more slowly. The high level of expression achieved with the E.coli synthetase, together with the high degree of purity readily obtainable from crude cell extracts, make the recombinant bacterial enzyme the preferred catalyst for the enzymatic synthesis of CMP-N-acetylneuraminic acid.

Amino Acid Sequence↗
PubMed1991

Study of the activity of differentiation-induction in a Chinese herb-viscum alniformosanae. Part 1: In vitro induction of differentiation in HL-60 leukemic cell line by conditioned medium secreted from viscum alniformosanae-stimulated mononuclear cells.

A conditioned medium(CM), designated as 572-CMF-, was a Chinese herb viscum alniformosanae (V.A.) stimulated mononuclear cells. This CM has the capacity to induce the promyelocytic cell line HL-60 to differentiate into morphologically and functionally mature monocytoid cells. However, our results on the effect of a combination of 572 conditioned medium and IFN-r, TNF and IL-2 were neither synergistic nor additive. Further investigation of the nature of this conditioned medium remains to be performed.

Cell Differentiation↗
PubMed1990

Genotoxicity evaluation of lithium hypochlorite.

Lithium hypochlorite (LiOCl), the pool and spa sanitizer/algicide, was evaluated for genotoxicity in a battery of studies designed to evaluate potential mutagenicity, DNA damage and chromosome aberrations. LiOCl was not mutagenic in the Ames test when tested in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, TA1538 or in the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) mutation assay in Chinese hamster ovary (CHO) cells without metabolic activation. LiOCl did not induce DNA damage in the unscheduled DNA synthesis assay using rat primary hepatocytes. Effects on metaphase chromosomes were evaluated in vitro in CHO cells at 12 and 18 h exposure without S9 and at 12 and 22 h following a 2 h exposure with S9. LiOCl induced a statistically significant increase in chromosome aberrations at the high dose only at both harvest times without S9 and at the late harvest time with S9. There were significant increases in chromosome aberrations at the low dose, low-mid and high doses, but not at the high mid-dose at the early harvest time with S9. However, LiOCl did not increase chromosome aberrations when tested orally in rats at maximally tolerated doses. Bone marrow cells, collected 6, 24 and 48 h after a single oral dose of LiOCl to rats (100, 500, 1000 mg/kg in males; 50, 250, 500 mg/kg in females) showed no increase in the incidence of aberrations. In general, the weight of the evidence indicates that LiOCl is not genotoxic.

Animals↗
PubMed1990

Beta-amyloid protein increases the vulnerability of cultured cortical neurons to excitotoxic damage.

Glutamate neurotoxicity may be an underlying pathological mechanism contributing to neuronal cell loss in a variety of conditions including Alzheimer's disease (AD). In this study, we examined whether the beta-amyloid protein found in the neuritic plaques of AD alters the susceptibility of neurons to excitotoxic damage. While mature cortical neurons exposed to beta-amyloid protein for 2-4 days did not appear to be damaged, their vulnerability to low-intensity exposure to glutamate, N-methyl-D-aspartate, and kainate increased, suggesting that this mechanism may contribute to the neurodegeneration seen in AD.

Alzheimer Disease↗
PubMed1990

Antimotility effects of Chinese herbal medicines on human sperm.

Caesalpinia sappan extract from a study of screened Chinese herbal medicines was found to be a potent agent for the inactivation of human sperm in vitro. Exposure of sperm from healthy donors to this agent showed remarkably reduced sperm motility. The antimotility effect of Caesalpinia sappan is concentration-dependent and about 2.5 mg/ml is required to reduce motility to 50% the control medium (EC50). This result suggests that this traditional Chinese herbal medicine possesses an antimotility effect on human sperm in vitro and has the potential of becoming in the future a new and acceptable male oral contraceptive.

Contraceptive Agents, Male↗
PubMed1988

Evaluation of two in vitro assays to screen for potential developmental toxicants.

To evaluate two in vitro assays for their ability to detect known developmental toxicants and nontoxicants, a series of 44 coded compounds were assayed by two independent laboratories using standardized protocols. The two test systems were (1) the human embryonic palatal mesenchymal cell growth inhibition assay and (2) the mouse ovarian tumor cell attachment inhibition assay. After all compounds were tested, they were decoded and ranked according to the minimum IC50 value (the millimolar concentration of compound which inhibits growth or attachment by 50% compared to the solvent control) from either test. The in vitro test result concordance with established in vivo animal and human test results was examined over a wide range of concentration levels (above which the in vitro results were called positive and below which they were considered negative). A positive response from either test was defined as a positive in vitro response. Concordance was defined as the number of correct responses divided by the number of chemicals tested. At the 1 mM level, the concordance of data from the combined in vitro assays with the in vivo data was 66% in one laboratory and 58% in the other. The maximum agreement between the combined in vitro and in vivo data was reached at the 20 mM level, where there was a 73 and 74% concordance of results in the two laboratories. At that level there was a 16 and 10% incidence of false negative results, and a 54 and 77% incidence of false positive results. A portion of these false negative compounds may require metabolic activation. The use of either assay alone was not as accurate as using a positive result from either test. Agreement of the in vitro data at the 10 mM level with available human data was 71 and 75% for each laboratory. The data indicate that the two assays are complimentary and as such the combination of these assays could be useful as a preliminary screen to establish priorities for in vivo developmental toxicity testing.

Animals↗