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Biomedical subjects

X Tan

Publications and source records attributed to X Tan.

151 records · Page 9Linked to original sources
PubMed1992

Association of mycoplasma with HIV-1 and HTLV-I in human T lymphocytes.

Recent findings from a number of investigators suggest associations between mycoplasma and HIV or AIDS. We used a quantitative morphometric technique to analyze electron micrographs of human T lymphocytes that were infected with both mycoplasma and/or HIV-1. We observed that lymphocytes which were associated with HIV-1 were much more likely to be associated with mycoplasma than cells that were not (p < .001). Similarly, cells with associated HTLV-I were more likely to be associated with mycoplasma than cells which were not associated with mycoplasma (p < .0001). In addition, mycoplasma and virus were observed in the same region in 90% of cases. These observations suggest that adherence of mycoplasma to lymphocytes that are chronically infected with human retrovirus may trigger viral release.

Cell Line↗
PubMed1992

Chinese medical school exit objectives: a multi-institutional survey of teacher opinion.

This paper describes a collaborative survey of Chinese medical school teacher opinion concerning clinical behaviours and skills that Chinese students should be expected to demonstrate prior to graduation from medical school. Selected teachers from four Chinese medical schools indicated whether each of 77 objectives was: essential for every student to know or demonstrate prior to graduation; useful but not essential; or not applicable to their educational programmes. Results show teachers' expectations regarding some of the behaviours and skills Chinese medical school teachers consider to be important for students to learn. Forty-nine per cent of the exit objectives were regarded as essential by 75% or more of the teachers. The most essential objectives involved performing clinical procedures, collaborating and communicating with health care professionals, conducting organ system examinations, formulating hypotheses and defining problems. Other essential objectives were concerned with communicating with patients and their families, maintaining currency within the discipline, and recognition, evaluation and triage of patients with life-threatening or chronic conditions. Exit objectives related to health promotion and risk assessment were regarded as useful but not essential at the undergraduate level. Implications for Chinese medical education are discussed.

China↗
PubMed1992

An efficient screen for peroxisome-deficient mutants of Pichia pastoris.

We describe a rapid and efficient screen for peroxisome-deficient (per) mutants in the yeast Pichia pastoris. The screen relies on the unusual ability of P. pastoris to grow on two carbon sources, methanol and oleic acid, both of which absolutely require peroxisomes to be metabolized. A collection of 280 methanol utilization-defective (Mut-) P. pastoris mutants was isolated, organized into 46 complementation groups, and tested for those that were also oleate-utilization defective (Out-) but still capable of growth on ethanol and glucose. Mutants in 10 groups met this phenotypic description, and 8 of these were observed by electron microscopy to be peroxisome deficient (Per-). In each per mutant, Mut-, Out-, and Per- phenotypes were tightly linked and therefore were most likely due to a mutation at a single locus. Subcellular fractionation experiments indicated that the peroxisomal marker enzyme catalase was mislocalized to the cytosol in both methanol- and oleate-induced cultures of the mutants. In contrast, alcohol oxidase, a peroxisomal methanol utilization pathway enzyme, was virtually absent from per mutant cells. The relative ease of per mutant isolation in P. pastoris, in conjunction with well-developed procedures for its molecular and genetic manipulation, makes this organism an attractive system for studies on peroxisome biogenesis.

Acyl-CoA Oxidase↗
PubMed1991

[Chemical constituents of Morinda officinalis How].

This paper reports the identification of four compounds isolated from the cortex of Morinda officinalis growing in Guangdong Province. These compounds are beta-sitosterol (I), 2-methyl-anthraquinone(II), rubiadin-1-methyl ether(III) and 24-ethylcholesterol(VI). Compounds II and VI are isolated from Morinda Genus for the first time.

Anthraquinones↗
PubMedDate not supplied

Independence of sleep EEG responses to GABAergic hypnotics: biological implications.

GABAergic hypnotics are known to depress non-rapid eye movement delta and rapid eye movements and to stimulate non-rapid eye movement sigma (spindles) and beta EEG. This study addressed the question of whether the magnitudes of these effects are significantly correlated. Data were from a study in 16 normal subjects whose sleep was recorded for five nights under placebo and for three nights each under zolpidem (10 mg), triazolam (0.25 mg) and temazepam (30 mg). EEG was analyzed with both period-amplitude and power spectral (FFT) analysis. The magnitudes of the EEG and eye movement density responses were not significantly correlated for any of the three drugs. It is therefore unlikely that sleep responses to GABAergic drugs can be explained by the common cellular action (increased chloride conductance) of these drugs. We suggest that the sleep EEG responses are manifestations of complex (but consistent) interactions of excitation and inhibition in large brain systems although certain aspects of these responses (e.g. the different time courses of delta vs sigma and eye movement responses) may reflect molecular adaptations. A separate observation in this study was the strong traitlike characteristics of the sleep variables studied. These variables were highly correlated across nights of baseline sleep; in addition, individual differences in baseline sleep were significantly retained on the third night of temazepam administration.

Adult↗
PubMedDate not supplied

Recombinant methioninase infusion reduces the biochemical endpoint of serum methionine with minimal toxicity in high-stage cancer patients.

The tumor-specific increased minimal requirement for methionine has been shown to be a highly promising therapeutic target. To attack this target we have previously cloned the methioninase gene from Pseudomonas putida and produced recombinant methioninase (rMETase). A pilot Phase I clinical trial has been carried out to determine rMETase toxicity, rMETase pharmacokinetics, and serum MET-depletion in cancer patients. Patients with advanced breast cancer, lung cancer, renal cancer and lymphoma were given a single rMETase treatment at doses ranging from 5,000 to 20,000 units by i.v. infusion over 6-24 hours. No clinical toxicity was observed in any patient after rMETase treatment. rMETase levels reached 0.1 to 0.4 units per ml of serum in the patients which correspond to therapeutic levels in vitro. The lowest serum methionine levels in rMETase-treated patients were 0.1% of the pre-treatment levels corresponding to approximately 0.1 microM, which also correlates to therapeutic levels in vitro. The results of the rMETase pilot Phase I clinical trial therefore indicate that i.v. infusion of rMETase is safe and effectively depletes its biochemical target of serum methionine suggesting potential efficacy in future clinical trials.

Antimetabolites, Antineoplastic↗