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Biomedical subjects

M S Chen

Publications and source records attributed to M S Chen.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Screening of antibodies to human T-cell leukemia virus type I (HTLV-I) in sera of blood donors and comparison of different methods].

Nine hundred and sixty five serum samples of blood donors from the blood bank of Veterans General Hospital Taipei were screened for antibodies to human T-cell leukemia virus type I (HTLV-I) by different methods. Adult T-cell Leukemia cell lines MT-1, MT-2, KH-2 and MT-2 stimulated by phorbol 12-myristate 13-acetate (PMA) were used as target cells in immunofluorescence microscopy (IF) examination with positive rates as 0.20% (2/965), 0.62% (6/965), 0.20% (2/965) and 0.51 (5/965) respectively. In addition to these, enzyme-linked immunosorbent assay (ELISA) gave a 2.59% (25/965) positive rate and particle agglutination (PA) test revealed a positive rate of 0.93% (9/965). The samples positive in IF were also positive in PA and those positive in PA were found positive in ELISA without exceptions. The 25 ELISA positive samples as well as 75 samples randomly chosen from the ELISA negative ones received Western blot (WB) analysis as a confirmation test. Only 3 of these 100 were considered positive in WB, giving a final positive rate of 0.31%, (3/965), and all of them were originally positive in both PA and ELISA. Particle agglutination test as the screening test and Western blot analysis as the confirming one were suggested to be a routine procedure for detecting anti-HTLV-I antibodies in blood banks through detailed comparison and discussion.

Adult↗
PubMed1988

Proposed definition of a smokeless tobacco user based on "potential" nicotine consumption.

This study examined and operationally defined "light," "moderate," and "heavy" users of smokeless tobacco according to the potential amounts of nicotine consumed per week from chewing tobacco and/or snuff products. Fifty adult male smokeless tobacco users ranging in ages from 18-85 were tested to determine nicotine content of smokeless tobacco products consumed. The smokeless tobacco products were blindly analyzed by gas chromatography to determine nicotine content. Mean nicotine yield per week was calculated by multiplying the number of cans and/or pouches used per week and placed on a normal probability distribution. The mean nicotine yielded 238 mg/wk and the categories emerged as "light" less than or equal to 87 mg/wk, "moderate" 88-388 mg/wk and "heavy" users greater than or equal to 389 mg/wk. Differences regarding type of user (light, moderate, heavy) were crossed tabbed with educational levels, years of smokeless tobacco use, age the habit was initiated, perception of harm and whether habit forming, and reason for using smokeless tobacco.

Adolescent↗
PubMed1988

Kinetics and inhibition of reverse transcriptase from human and simian immunodeficiency viruses.

Reverse transcriptase from the simian immunodeficiency virus (SIV) was found to have kinetic behavior similar to that of enzyme from the human immunodeficiency virus (HIV). Michaelis constants for the substrates TTP and dGTP and inhibition constants for the inhibitors 3'-azido-3'-deoxythymidine 5'-triphosphate, 2',3'-dideoxythymidine 5'-triphosphate, and 2'-3'-dideoxyguanosine 5'-triphosphate were obtained for SIV reverse transcriptase and were found to be similar to the corresponding values for HIV reverse transcriptase. Thus, the interaction of SIV reverse transcriptase with nucleotide analogs appears to be indistinguishable from that of the HIV enzyme, suggesting that SIV/simian acquired immunodeficiency syndrome (SAIDS) is a potentially good model of AIDS.

Deoxyguanine Nucleotides↗
PubMed1988

Screening for smokeless tobacco-associated lesions: recommendations for the dental practitioner.

The increasing use of smokeless tobacco and the accumulating list of associated health hazards including cancer and cardiovascular effects should be of concern to the dentist. This study documents both concern from patients' perceptions and clinical examinations of their smokeless tobacco-associated lesions. Implications for the dentists' practice among adolescents and young adults are discussed.

Adolescent↗
PubMed1987

Synthesis and antiviral activity of various 3'-azido, 3'-amino, 2',3'-unsaturated, and 2',3'-dideoxy analogues of pyrimidine deoxyribonucleosides against retroviruses.

Various 3'-azido, 3'-amino, 2',3'-unsaturated, 2',3'-dideoxy, and 5-substituted analogues of pyrimidine deoxyribonucleosides have been prepared and tested against Moloney-murine leukemia virus (M-MULV), a mammalian T-lymphotropic retrovirus in vitro. Among these compounds, the 3'-azido analogues of thymidine, 2'-deoxy-5-bromouridine, and 2'-deoxy-5-iodouridine, the 2',3'-unsaturated analogue of thymidine and and 2'-deoxycytidine, and 2',3'-dideoxycytidine were found to be most active, with ED50 values of 0.02, 1.5, 3.0, 2.5, 3.7, and 4.0 microM, respectively. These active compounds were nontoxic to the host SC-1 cells up to 100 microM concentration. The 3'-azido analogues of thymidine and 2'-deoxy-5-bromouridine were also tested in vitro against HTLV-III/LAV/AAV ("AIDS" virus) and found to be significantly active, with ED50 values of 0.23 and 2.3 microM, respectively. The structure-activity relationships are discussed.

Antiviral Agents↗
PubMed1987

1-(2-Deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-ethyluracil. A highly selective antiherpes simplex agent.

The protected nucleoside 1-(2-deoxy-2-fluoro-3,5-di-O-benzoyl-beta-D-arabinofuranosyl)-5-ethylura cil (10) was prepared by condensation of 3,5-dibenzoyl-2-deoxy-2-fluoro-alpha-D-arabinofuranosyl bromide (9) with 2,4-bis-O-(trimethylsilyl)-5-ethyluracil (8). The ratio in this coupling reaction has been raised to 17:1 in favor of the desired beta-anomer. Deprotection by aminolysis gave 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-ethyluracil (FEAU, 1) in 67% isolated yield from the bromo sugar 9. In vitro data show that FEAU has activity against herpes simplex virus types 1 and 2 comparable to that of 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-methyluracil (FMAU, 2), 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouracil (FIAU, 3), and acyclovir (ACV, 12). The cellular toxicity of FEAU was found to be much lower than that of the other nucleoside analogues. Biochemical experiments indicate that FEAU has similar affinity toward thymidine kinases encoded by HSV 1 and 2 and a much lower affinity for cellular thymidine kinase than thymidine. The in vivo antiviral effects of FEAU, FMAU, FIAU, and ACV were evaluated against herpes infection in a systemic mouse encephalitis model and a cutaneous guinea pig model. While FEAU showed activity comparable to that of ACV in the systemic infection model, it was superior in the cutaneous herpes infection model.

Acyclovir↗