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Biomedical subjects

J H Meng

Publications and source records attributed to J H Meng.

4 recordsLinked to original sources
PubMed2002

A new enzyme immunoassay for the detection of antibody to hepatitis E virus.

BACKGROUND AND AIM: The purpose of the present study was to develop enzyme immunoassay (EIA) for the detection of IgG anti-hepatitis E virus (HEV) activity using two new recombinant proteins as antigenic targets, and to evaluate these EIA with the aid of statistical methods. METHODS: Two proteins, a mosaic protein and pB166 containing region 452-617 aa of the ORF2 of the HEV Burma strain, were used to develop the new HEV EIA. This EIA was evaluated using several panels of serum specimens obtained from: (i) acutely HEV-infected patients; (ii) patients with non-A, non-C hepatitis; (iii) normal blood donors (NBD) from non-endemic countries; and (iv) experimentally infected chimpanzees. RESULTS: A new HEV EIA was developed using two new recombinant proteins. This assay was able to detect anti-HEV activity in all specimens from acutely HEV-infected patients. When NBD were tested, more than 15% of specimens were found to be IgG anti-HEV positive. All NBD anti-HEV-positive specimens were tested with overlapping synthetic peptides spanning the entire HEV ORF2-encoded protein. More than 90% of the anti-HEV-positive NBD specimens immunoreacted with an average of 15 synthetic peptides derived from different regions of the HEV ORF2 protein. These data suggest that the HEV EIA is at least 90% specific in detecting remote HEV infections. CONCLUSION: The new HEV EIA developed in the present study is a highly specific diagnostic assay for the detection of anti-HEV activity in serum specimens obtained from different epidemiologic settings.

Hepatitis Antibodies↗
PubMed2001

[Contrastive study of two methods("programmed temperature vaporization with back flushing" and "head space") for light hydrocarbon analysis].

Light hydrocarbon analytical method of "PTV with Back Flushing" presented here is characterized as follows: a) with "PTV" inlets temperature programmed; b) with gas line system of "Back Flushing"; c) with direct injection of oil samples. After oil sample injection, "Back Flushing" is on when light hydrocarbon components enter into analytical chromatographic column. At the same time, the temperature of inlet increases. The high temperature and "Back Flushing" blow the heavy components in the oil samples out of the analytical system. Besides, the analytical method of "Head Space" was established. Both "PTV with Back Flushing" and "Head Space" have the advantages of long column life and short analysis time. The resolution for lighter components < C9 meets the criterion of ASTM D5134-98, with the good repeatability. Ten oil samples from 6 oil areas were analysed by using the two methods. The relative deviations between the two analytical results represented by 19 geochemistry parameters were about +/- (1%-25%). The reasons for the deviation are discussed. It is pointed out that in geochemistry study it is not acceptable to combine the data obtained from two analytical methods. The analytical results obtained by injecting crude oil directly into injector are more reliable. The results obtained in "Head Space" analytical method should be calibrated when used in geochemistry study.

English Abstract↗
PubMed2000

Novel dual repressor elements for neuronal cell-specific transcription of the rat 5-HT1A receptor gene.

The level of expression of the 5-HT1A receptor in the raphe and limbic systems is implicated in the etiology and treatment of major depression and anxiety disorders. The rat 5-HT1A receptor gene is regulated by a proximal TATA-driven promoter and by upstream repressors that inhibit gene expression. Deletion of a 71-base pair (bp) segment between -1590/-1519 bp of the 5-HT1A receptor gene induced over 10-fold enhancement of transcriptional activity in both 5-HT1A receptor-expressing (RN46A raphe and SN48 septal) cells and receptor-negative (L6 myoblast and C6 glioma) cells. A 31-bp segment of the repressor was protected from DNase I digestion by RN46A or L6 nuclear extracts. Within the 31-bp segment, a single protein complex was present in receptor-expressing cells that bound a novel 14-bp DNA element; in receptor-negative cells, an additional complex bound an adjacent 12-bp sequence. In receptor-positive but not receptor-negative cells, mutation of the 14-bp element to eliminate protein binding abrogated repression to nearly the same extent as deletion of the -1590/-1519 bp segment. Additional mutation of both 14-bp and 12-bp elements abolished protein binding and repressor activity in receptor-negative cells. Thus a single protein-DNA complex at the 14-bp element represses the 5-HT1A receptor gene in 5-HT1A receptor-positive neuronal cells, whereas adjacent DNA elements provide a dual repression mechanism in 5-HT1A receptor-negative cells.

Animals↗