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Biomedical subjects

W Huang

Publications and source records attributed to W Huang.

At least 487 records · Page 27Linked to original sources
PubMed1996

Determination of methadone and its N-demethylation metabolites in biological specimens by GC-PICI-MS.

Methadone is often invoked for detoxification and maintenance of the opioid addict. We have developed and validated a sensitive and specific method for the analysis of methadone and its metabolites, 2-ethylidene-1,5-dimethyl-3, 3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenylpyrroline (EMDP), in human plasma, urine, and liver microsomes. This assay uses a solid-phase extraction. Separation and analysis of the analytes are performed by capillary gas chromatography-positive ion chemical ionization-mass spectrometry. The protonated molecules (MH+) are monitored at m/z 264 and 267 for EMDP-d0 and -d3, m/z 278 and 281 for EDDP-d0 and -d3, and m/z 310 and 313 for methadone-d0 and -d3. The recovery of methadone and its metabolites exceeded 85% in the different matrices analyzed. Linear standard curves in plasma and in urine were obtained over the concentration range of 10-600 ng/mL (coefficients of determination: methadone, > or = 0.995; EMDP, > or = 0.994; and EDDP, > or = 0.996). With plasma and urine fortified at 25, 100, and 300 ng/mL, the assay was precise (intra-assay coefficients of variation [CVs], 2-12%; interassay CVs, 1-15%) and accurate (intra-assay percent of target, 85-107; interassay percent of target, 88-105) for all three analytes. Stability studies indicated that methadone and its metabolites are stable at room temperature in plasma and in urine for at least 1 week and in liver microsomes for at least 24 h. This method has now been shown to be useful for quantitation of methadone, EDDP, and EMDP in human urine and plasma and is also useful for quantitation of the amount of EDDP produced in human liver microsomes incubated with methadone. It provides an accurate and precise analytical tool for further studies on the metabolism of methadone.

Ammonia↗
PubMed1996

Microsurgical replantation of the avulsed scalp: report of 20 cases.

Our 4-year experience with 20 patients who had suffered avulsion of 75 percent or more of the scalp is reviewed. All patients underwent replantation using microsurgical technique with 100 percent survival in 16, partial survival in 3, and failure in only 1 case. The emergency management and indications for replantation are demonstrated. The roles of sufficient preoperative preparation, generous debridement of damaged vessels, interpositional vein grafts, and the shortening of operative time in contributing to this success are emphasized. We developed a new surgical procedure called simultaneous vein grafts on donor and recipient sites in an effort to use less time in the anastomosis of interpositional vein grafts. Furthermore, we anastomosed the extra artery of the scalp to the vein on the recipient head when no suitable vein could be found. Intraoperative repair of the scalp sensory nerve and no postoperative use of any vasodilator or anticoagulant are discussed.

Adolescent↗
PubMed1996

Comparison of five selective media for identifying fecal carriage of vancomycin-resistant enterococci.

There is no uniformly accepted method for detecting colonization with vancomycin-resistant enterococci (VRE). The sensitivities of five culture methods were determined for patients known to harbor VRE. Of 189 inpatients, 101 were found to harbor VRE by at least one method. Three methods detected fewer than half of the cultures. Campylobacter agar identified 70% of patients. Enterococcosel broth (containing vancomycin and aztreonam) identified 88% and may be preferred over other media for routine surveillance.

Anti-Bacterial Agents↗
PubMed1996

mRNA export correlates with activation of transcription in human subgroup C adenovirus-infected cells.

To investigate the mechanisms by which viral mRNA species are distinguished from their cellular counterparts for export to the cytoplasm during the late phase of subgroup C adenovirus infection, we have examined the metabolism of several cellular and viral mRNAs in human cells productively infected by adenovirus type 5 (Ad5). Several cellular mRNAs that were refractory to, or could escape from, adenovirus-induced inhibition of export of mRNA from the nucleus have been identified. This group includes Hsp70 mRNAs synthesized upon heat shock of Ad5-infected 293 or HeLa cells during the late phase of infection. However, successful export in Ad5-infected cells is not a specific response to heat shock, for beta-tubulin and interferon-inducible mRNAs were also refractory to virus-induced export inhibition. The export of these cellular mRNAs, like that of viral late mRNAs, required the E1B 55-kDa protein. Export to the cytoplasm during the late phase of Ad5 infection of several cellular mRNAs, including members of the Hsp70 family whose export was inhibited under some, but not other, conditions, indicates that viral mRNA species cannot be selectively exported by virtue of specific sequence or structural features. Cellular and viral late mRNAs that can be exported from the nucleus to the cytoplasm were expressed from genes whose transcription was induced or activated during the late phase of Ad5 infection. Consistent with the possibility that successful export is governed by transcriptional activation in the late phase of adenovirus infection, newly synthesized viral early E1A mRNA was subject to export inhibition during the late phase of infection.

Adenovirus E1B Proteins↗
PubMed1996

Role of leukocyte beta 2-integrin in PAF-induced shock and intestinal injury.

Leukocyte adhesion and diapedesis, critical steps in the inflammatory process, depend on the expression of integrin CD11b/CD18. In this study, we examined the preventive effect of monoclonal antibodies (MAb) against CD11b (1B6), CD11a, or CD18 (CL26) on platelet-activating factor (PAF)-induced bowel injury. Young male Sprague-Dawley rats were anesthetized and injected with either of two doses of PAF (2.5 or 3 micrograms/kg iv) to induce transient hypotension and irreversible shock. Some rats wee also injected intravenously with 1B6 (anti-CD11b), anti-CD11a, CL26 (anti-CD18), or combined anti-CD11a and 1B6, 30 min before PAF. Animals receiving a low dose of PAF developed mild hypotension, hemoconcentration, increased intestinal myeloperoxidase, and bowel injury after 1 h. These effects were completely prevented by pretreatment with 1B6. A high dose of PAF induced irreversible shock and gross intestinal necrosis. Both CL26 and 1B6 were partially effective in attenuating PAF-induced bowel injury. Addition of anti-CD11a to 1B6 in the treatment further ameliorated the systemic adverse effects of PAF and intestinal injury. However, focal minor injury still developed. Anti-CD11a alone, fucoidin, or anti-P-selectin was ineffective. Rats depleted of neutrophils were also largely protected from the adverse effects of PAF at high doses, although minor intestinal injury often persisted. We conclude that leukocyte beta 2-integrins play an important role in PAF-induced hypotension, leukopenia, hemoconcentration, and intestinal necrosis, and that CD11b/CD18 is the main adhesion molecule involved in the pathogenesis of injury. However, CD11/CD18- and neutrophil-independent pathways exist for mediating PAF-induced bowel injury, although their role is probably a minor one.

Animals↗
PubMed1996

Dehydration natriuresis in male rats is mediated by oxytocin.

In a previous study in rats we demonstrated the existence of osmoregulatory natriuretic mechanisms distinct from the natriuretic mechanisms that are dependent on volume stimulation. At the same time, we found that oxytocin (OT) receptors were important mediators of natriuresis induced by hypernatremia but not of that induced by isotonic volume expansion. In the present study, the role of OT in dehydration natriuresis was examined in conscious rats. Dehydration for 24 h caused hypernatremia (from 142.1 +/- 0.4 to 147.7 +/- 0.7 mmol/l) and natriuresis accompanied by an approximately 30% spontaneous reduction of food intake. In conjunction with renal retention of water caused by an increase in circulating vasopressin, the natriuresis and probably the reduction of food intake can help to counteract the rise in body fluid osmolality. This natriuresis could not be fully explained by the reduction in plasma aldosterone. Plasma OT concentration had increased from 15.5 +/- 1.2 to 23.8 +/- 2.0 pg/ml at the end of 24 h of dehydration. Intravenous infusion of a selective OT-receptor antagonist [Mpa1,D-Tyr(Et)2, Thr4, Orn8]-OT using osmotic minipumps prevented dehydration natriuresis. It is concluded that in a dehydration-induced hypernatremic state OT is released, inducing natriuresis and facilitating sodium homeostasis. This mechanism is activated by Na osmoreceptors, but is not primarily dependent on the volume status.

Aldosterone↗
PubMed1996

Morphometry of the human pulmonary vasculature.

The morphometric data on the branching pattern and vascular geometry of the human pulmonary arterial and venous trees are presented. Arterial and venous casts were prepared by the silicone elastomer casting method. Three recent innovations are used to describe the vascular geometry: the diameter-defined Strahler ordering model is used to assign branching orders, the connectivity matrix is used to describe the connection of blood vessels from one order to another, and a distinction between vessel segments and vessel elements is used to express the series-parallel feature of the pulmonary vessels. A total of 15 orders of arteries were found between the main pulmonary artery and the capillaries in the left lung and a total of 15 orders of veins between the capillaries and the left atrium in the right lung. The elemental and segmental data are presented. The morphometric data are then used to compute the total cross-sectional areas, blood volumes, and fractal dimensions in the pulmonary arterial and venous trees.

Adult↗
PubMed1996

Although DR3-DQB1*0201 may be associated with multiple component diseases of the autoimmune polyglandular syndromes, the human leukocyte antigen DR4-DQB1*0302 haplotype is implicated only in beta-cell autoimmunity.

Human leukocyte antigen (HLA)-DRB1 and -DQB1 alleles were analyzed using a PCR-based sequence-specific priming technique in 16 patients with autoimmune polyglandular syndrome type I (APS-I), 31 patients with APS-II, and 110 patients with component diseases of APS-II, including 9 patients with isolated Addison's disease, 43 patients with Hashimoto's thyroiditis, 22 patients with Graves' disease, and 36 patients with vitiligo. No significant associations was observed between HLA and APS-I patients in our data set, nor was sharing of HLA haplotypes by sibling pairs affected by APS I significantly different from the random expectation. Thus, HLA-DRB1 and -DQB1 genes are probably not involved in APS-I. To delineate the associations between HLA-DRB1, DQB1, and APS-II, we analyzed APS-II patients with or without beta-cell autoimmunity [i.e. insulin-dependent diabetes (IDD) and/or islet cell or glutamic acid decarboxylase autoantibodies]. Our results suggest that the association between DR4-DQB1*0302 and APS-II was entirely due to the presence of pancreatic beta-cell autoimmunity, since this haplotype was otherwise not significantly associated with APS-II or with any other of its component diseases. In contrast, the DR3-DQB1*0201 haplotype was associated not only with IDD, but also with APS-II in the absence of pancreatic beta-cell autoimmunity, as were several its component diseases, including isolated Addison's disease, Graves' disease, and Hashimoto's thyroiditis. Interestingly, the frequency of DQB1*0602, a dominantly protective allele against IDD, was not significantly decreased in the APS-II patients with IDD or beta-cell autoimmunity, albeit the patient numbers were small. This phenomenon may suggest that the development of autoimmunity to nonpancreatic endocrine glands may predispose autoimmunity to the pancreatic beta-cells and involve genes other than those of the MHC.

Adolescent↗
PubMed1996

[Human reliability in manned spaceflight].

Human error may threaten the security in manned spaceflight, this paper discusses the importance of the role played by man and human reliability in spaceflight safety, and analyses the reduction of human reliability by errors. The causes of the errors are also analysed in respect to reduction of risk of astronaut selection, strengthening of training, provision of medical monitoring and supplies, as well as prevention of errors from management factors. Measures to raise human reliability are proposed

Accidents, Aviation↗
PubMed1996

Rapid detection of common Chinese glucose-6-phosphate dehydrogenase (G6PD) mutations by denaturing gradient gel electrophoresis (DGGE).

We describe here the use of denaturing gradient gel electrophoresis (DGGE) to detect the most common Chinese glucose-6-phosphate dehydrogenase (G6PD) variants, which are the single point mutations: G-->T at nt 1376, G-->A at 1388 both in exon 12 and A-->G at nt 95 in exon 02. In each case, the mutant allele resolves well from the normal allele(s). The distinct heteroduplex bands are characteristic of a particular genotype suggesting that this feature is very useful for identifying all heterozygous carriers for this and other X-linked diseases. When the analysis is extended to other exons, DGGE scans the gene and coupled with direct sequencing, it leads to the identification of new G6PD variation(s). With this approach, we identified a mutation in exon 9 which had not been reported in Hong Kong. Since DGGE can rapidly screen many unknown samples in one gel, this approach could be used to diagnose these G6PD mutations and to identify the at-risk for counselling.

Alleles↗
PubMed1996

YAC cloning and identification of rice (Oriza sativa L.) genomic DNA.

Construction of the genomic library by using yeast artificial chromosomes (YAC) has been an approach to a map-based gene cloning strategy. We have obtained more than 2000 YAC clones for the construction of a rice (Oriza sativa L.) genomic library through a procedure that could be summarized as follows: a fractionate by the pulsed-field gel electrophoresis (PFGE), the rice nucleic high molecular weight (HMW) DNA which is partially digested with EcoRI, and recovered fragments larger than 200 kb; ligate the fragments to the EcoRI digested YAC vector pairs pJS97 and pJS98; transform competent spheroplasts prepared from yeast strain YPH252; and select transformants directly on Ura-Trp-double selective media. Southern hybridization results indicated that the sizes of inserts were in the range of 200-820 kb.

Chromosomes, Artificial, Yeast↗
PubMed1996

[16S rRNA gene PCR-SSCP analysis of the reference strains from 15 serovars (14 serogroups) of pathogenic leptospires in China].

The DNAs of reference strains from 15 serovars (14 serogroups) of pathogenic leptospires in China were amplified with 16S rRNA gene primers, and then single-strand conformation polymorphism (SSCP) of the products were analyzed in 12.5% nondenaturing mini polyacrylamide gel (containing 5% glycerol) combining with silver-staining. All products showed two bands on electrophoresis at different parameters of voltage or current and concentration of gel. It proved that serovar lai, serovar canicola, serovar pyrogenes, serovar autumnalis, serovar australis, serovar pomona, serovar linhai, serovar hebdomadis, serovar haemolytica, serovar wolffi and serovar paidjan have the identical pattern (Leptospira interrogans), while serovar javanica, serovar ballum, serovar tarassovi and serovar manhao I belong to another pattern (L. borgpetersenii). The result was consistent with the classification of genetic species by Yasuda et al (1987) and Ramadass et al (1992).

China↗
PubMed1996

[Monoclonal antibodies to human progesterone receptors: production, indentification and clinical application].

A peptide with 15 amino acid of human progesterone receptor (PR) was synthesized and used as antigen. Five hybridoma cells were obtained by cloning technique. In tests to hybridoma cell H4, the site specificity of the antibody to PR was found. The antibody reacted specifically with PR, but did not cross-react with ER, AR, or GR. Five women who used clomiphene citrate (CC) 100mg/d x 5 days were involved in a study of serum pregesterone (P) and endometrial histology in early luteal phase. There was no difference in serum P level in two groups. Three cases in CC group showed abnormal secretory endometrium. PR concentration in the nuclei of glandular cells of endometrium in CC group was significantly lower than that in the control group. In women with abnormal secretory endometrium, PR concentration in the nuclei of glandular cells was lower than that in women with normal endometrial histology. CC can influence endometrial histology by changing-PR concentration in the nuclei of glandular cells. The endometrium can not respond to the stimulus of P at normal levels and thus results in luteal phase defect.

Animals↗