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Biomedical subjects

G Qian

Publications and source records attributed to G Qian.

At least 19 recordsLinked to original sources
PubMed1999

Computing minimum description length for robust linear regression model selection.

A minimum description length (MDL) and stochastic complexity approach for model selection in robust linear regression is studied in this paper. Computational aspects and implementation of this approach to practical problems are the focuses of the study. Particularly, we provide both algorithms and a package of S language programs for computing the stochastic complexity and proceeding with the associated model selection. A simulation study is then presented for illustration and comparing the MDL approach with the commonly used AIC and BIC methods. Finally, an application is given to a physiological study of triathlon athletes.

Algorithms↗
PubMed1997

[Culture and characterization of rat lung microvascular endothelial cells].

Cultures of rat lung microvascular endothelial cells (RLMECs) were obtained from perepheral lung tissue. The lung tissue was cut into small pieces and cultured with RPMI-1640 containing 20% bovine calf serum, 90 micrograms/ml heparin, 4 mmol/L L-glutamine, 100 mu/ml penicillin and 100 micrograms/ml streptomycin. Erythrocytes and leukocytes left the tissue first, followed by RLMECs. Fibroblasts and other cells grew after 72 hours of culture. After 60 hours of culture, the lung tissue was discarded. RLMECs in flask showed regular cobblestone morphology and positive for binding of the lectin Bandeiraea simplicifolia I and indirect immunofluoresence staining with factor VIII antiserum.

Animals↗
PubMed1997

[The application of computer imaging simulation in nose augmentation].

By measurement and analysis, the postoperative image was simulated in standard facial image of the saddle nose using computer imaging and the software developed by us. When the simulated image is accepted by both the surgeon and the patient, the computer gives data to instruct the operation. The authors described how to obtain the standard facial image and how to reduce error. The computer imaging simulation makes the cosmetic operation accurate, quantitative and imaged, and its applications will be broadened.

Adult↗
PubMed1997

[Quantitative determination of dracorhodin in Daemonorops draco B1. and traditional Chinese medicines containing Daemonorops draco B1. by HPLC].

A reversed phase high performance liquid chromatographic mertod for the determination of Dracorhodin in Daemonorops draco B1. and Traditional Chinese Medicines containing Daemonorops draco B1. has been developed so as to set the quality standard for Sichuan Jinyao. The result showed that the components of Dracorhodin were separated by ODS column, with MeOH-0.05 mol/L NaH2PO4 (51:50) (pH = 3.10-3.15, adjusted with H2PO4) acting as the mobile phase. The other high retentive components were eluted by methanol; thus the analytical time was reduced. The method is simple and accurate.

Benzopyrans↗
PubMed1996

Neutralization of SIVmac239/17E in lymphocyte cultures involves virus strain-specific linear and conformational epitopes encoded by different regions of the env gene including the "V3" domain.

SIVmac251 and its closely related derivatives SIVmac239 and SIVmac239/17E vary greatly in their susceptibility to neutralization with homologous and heterologous antisera. Whereas SIVmac251 induces homologous neutralizing antibodies, the antibodies induced by SIVmac239 rarely neutralize infectivity of this virus in lymphocyte cultures. In contrast, SIVmac239/17E is remarkably susceptible to neutralization with homologous and heterologous antisera induced by other strains of SIVmac. In this study, we studied the molecular basis for the neutralization of SIVmac239/17E. Using chimeric viruses in which different regions of the env gene of both SIVmac239 and SIVmac239/17E were inserted into a background of either of the parental genomes, we showed that the newly acquired neutralization properties of SIVmac239/17E were attributable to amino acid substitutions between the V2 and V4 regions of gp 120. Site-directed mutagenesis of the env gene in this region showed that the arginine substitutions at positions 334 and/or 340 within the "V3" domain were fundamental to virus neutralization but other substitutions in the V2-V4 region added to the ease of its neutralization since it became neutralizable with much higher dilutions of serum. The molecular determinants for neutralization of this virus are distinct from those reported as responsible for neutralization of SIVmac251 and both are distinct from SIVmac239.

Animals↗
PubMed1996

The chemical modification of E. coli L-asparaginase by N,O-carboxymethyl chitosan.

E. coli L-asparaginase was modified with N,O-carboxymethyl chitosan in the presence of normal product L-aspartic acid, which protected the active site of the enzyme. The modified enzyme remained high catalytic activity, showed greater stability against trypsin and alpha-chymotrypsin, but lost its activity more rapidly at high temperature (> 45 degrees C) than did the native enzyme. When tested in vivo, the plasma half-life of the modified enzyme (t1/2 = 40 hr) was over 33 times longer than that of the native enzyme (t1/2 = 1.6 hr). The results showed that the modified L-asparaginase may be much more useful than did the native enzyme for clinical treatments of tumors.

Animals↗
PubMed1996

Structure and function of the band 3 Cl-/HCO3- transporter in chronic respiratory failure patients.

OBJECTIVE: To study red blood cell (RBC) membrane band 3 protein structure and anion transport function in cor pulmonale patients with respiratory failure. PATIENTS AND METHODS: Blood samples were obtained from 80 cases of cor pulmonale and 37 normal subjects (control group). The patients were divided into type I respiratory failure (Group I, n = 40) and type II respiratory failure (Group II, n = 40). The anion permeability of the erythrocyte membrane (Pcl), PO2 and PCO2 in 12 of the patients with type II respiratory failure were observed in acute stage (AS), chronic stage (CS) and recovery stage (RS). Membrane protein was analyzed by polyacrylamide electrophoresis in SDS. 55-KDa membrane domain was fractionated on 10% NaDodSO4 polyacrylamide gel column and purified further with a sephadax G-25 column. The composition of amino acids was analyzed on a Beckman 6300 Gold system amino acid analyzer. The Pcl was determined by the hypoisotonic hemolysis method. RESULTS: The relative content of band 3 protein erythrocytic membrane, anion permeability coefficient of the erythrocyte membrane and plasma chloride in the patients with cor pulmonale with type II respiratory failure were significantly lower than those in the patients with type I respiratory failure and the control. The number of residues in the anion transport domain of the trypsin fragment of 55,000 daltons of band 3 protein showed no significant difference among the three groups. CONCLUSIONS: The structure of anion transport sites remains intact and so the reduction of the anion transport function of band 3 protein in patients with cor pulmonale with type II respiratory failure may be due to the decrease of the relative content of band 3 protein, the decrease of extraerythrocytic chloride and hypoxia.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1995

[Determination of the content of icariine in four Chinese patent medicines containing Epimedium brevicornum Maxim].

A new HPLC method has been developed for analysis of Icariine in four Chinese patent medicines. The symmetric peak of Icariine and good resolution were gotten, when ODS was used as analytical column (30 degrees C) MeOH-KH2PO4 (pH = 2.7, adjusted with H3PO4) (57:43) as a mobile phase; the detective wavelength was 268 nm. The contents of Icariine in Bushen-qiangshen-wan, Guiling-ji, Zhuang-gu-guanjie-wan and Qianliening-chongji were 0.105, 0.0995, 0.0566 and 0.313% respectively.

Chromatography, High Pressure Liquid↗
PubMed1995

Changes of gastric acid secretion and somatostatin after Roux-en-Y cholangiojejunostomy.

The authors studied the changes of gastric acid secretion and determined the levels of somatostatin (SS) and gastrin (Gn) in blood, gastric juice and pyloric antrum in 28 patients Roux-en-Y with cholangiojejunostomy (CJR-Y). Gastric acid hypersecretion was identified, and the level of SS was found dropped while the content of Gn increased in these specimens. It was considered that the reduction of SS synthesis and secretion might have a key effect on the mechanism of secondary gastric acid hypersecretion in patients after CJR-Y.

Adult↗
PubMed1995

[A study on erythrocyte membrane band 3 protein anion transport function in chronic respiratory failure patients].

The changes of the structure, content and anion transport function as well as the blood gases and electrolytes inside and outside the erythrocytes were investigated in 3 groups of subjects: type I respiratory failure patients (group 1, n = 40); type II respiratory failure patients (group 2, n = 40) and controls (group 3, n = 37). The results showed that (1) anion transport function impairment of erythrocyte membrane band 3 protein and HCO3-/Cl- exchange restrain may be the reasons that aggravate CO2 retention and respiratory acidosis in cor pulmonale patients with type II respiratory failure. (2) band 3 protein anion transport function impairment in patients of cor pulmonale with type II respiratory failure is reversible. Therefore, it was necessary to supply oxygen to cor pulmonale patients with hypoxemia in time, which may contribute to the recovery of anion transport function.

Aged↗
PubMed1995

[Iatrogenic bile duct injuries during the process of laparoscopic cholecystectomy].

Twelve patients with iatrogenic bile duct injuries occurred during laparoscopic cholecystectomy (LC) were treated from June 1992 to May 1994. All the patients underwent re-operation and were cured. The causes and characteristics of the injuries were: (1) perforation of the common hepatic or common bile duct caused by dissecting hook (3 cases); (2) necrosis and perforation of the common hepatic duct due to diathermic injury (1 case); (3) clamping of the common hepatic duct by Ti clip (1 case); (4) secondary high bile duct stricture following a failed end-to-end anastomosis or hepatico-cholangio-jejunostomy of the amputated common hepatic duct (5 cases); (5) delayed high bile duct stricture (2 cases). It is emphasized that the severity of bile duct injuries by LC be should not overlooked, and more experience in this field be accumulated to avoid this serious complication.

Aged↗
PubMed1995

[The effect of furosemide and valium on band 3 protein anion transport function in chronic respiratory failure patients].

In order to explore the effect of drugs on band 3 protein anion transport function and its clinical significance, several common drugs such as furosemide, hydrochlorothiazide, etc, were tested. The results demonstrated that furosemide, hydrochlorothiazide and valium could inhibit rapidly and reversibly the anion transport function of band 3 protein and led to HCO-3/Cl- exchange restriction. The mechanism of action of the drugs was thought to be an interaction between drugs and the two sites of band 3 protein anion transport system. The reason that pulmonary encephalopathy was induced by diuretics and sedatives may be related to the inhibition of anion transport by the drugs and reduced CO2 elimination. It was necessary to be careful in using these drugs in patients with impaired lung function, especially the patients of cor pulmonale with type II respiratory failure.

Aged↗
PubMed1994

trans-activation of the HIV promoter by a cDNA and its genomic clones of human herpesvirus-6.

Human herpesvirus 6 (HHV-6) is a lymphotropic herpesvirus, and in vitro, it can productively infect human CD4+ T cells as HIV-1. Co-infection of T cells by HIV-1 and HHV-6 can lead to both activation of the HIV-1 promoter and acceleration of the cytopathic effects. An HHV-6 (GS) cDNA clone, pCD41, encoding for a 41-kDa nuclear protein was identified and characterized previously (Chang and Balachandran, J. Virol. 65, 2884-2894 and 7085, 1991). Sequence analyses show that this protein has significant homology with the human cytomegalovirus UL44 gene coding for the ICP36 family of early-late-class phosphoprotein. Using this cDNA as the probe, a 3.8-kb EcoRI genomic fragment encoding the HHV-6(GS)P41 was cloned and designated as pGD41. When cotransfected with the HIV LTR CAT into CV-1 cells, both the pCD41 and pGD41 clones trans-activated the HIV LTR. Sequence analyses of pCD41 indicate that there are two potential open reading frames (ORFs), A and B, which are homologous to the ORFs found in the genomic clone pGD41. Deletion constructs of the pCD41 clone demonstrated that ORF-A was critical for the HIV LTR activation. Deletion analyses of the pCD41 ORF-A and the use of promoter constructs further mapped an internal functional promoter within the pCD41 sequence that can direct the synthesis of the trans-activating protein. By using HIV LTR deletion mutants, the NF-kappa B binding sites were found to be critical for response to the pCD41 trans-activation.

Amino Acid Sequence↗
PubMed1993

Identification and characterization of glycoprotein gH of human herpesvirus-6.

Sequence analysis of an 8-kb BamHI-G DNA fragment from human herpesvirus-6 variant A strain GS (HHV-6A(GS)) has identified a gene encoding a glycoprotein homologous to glycoprotein gH of other herpesviruses and this gene was designated as HHV-6 gH (Josephs et al., J. Virol. 65, 5597). The open reading frame (ORF) of HHV-6A(GS) gH gene was amplified by polymerase chain reaction and was expressed as a trpE fusion protein in bacteria. Stable fusion protein was made only with constructs containing amino acids 15 to 469 of the ORF and this fusion protein was used to raise rabbit antisera. In the in vitro transcription-translation analysis of the gH gene, addition of microsomal membranes resulted in the processing of an unprocessed precursor to a polypeptide product of about 108 K. These in vitro-synthesized precursor and product forms were immunoprecipitated by the rabbit antibodies against the gH fusion protein. Rabbit anti-gH antibodies neutralized the infectivity of both HHV-6 variant A strain GS and variant B strain Z-29, and immunoprecipitation reactions identified a virion envelope-associated 102 K polypeptide as the glycoprotein gH of HHV-6 variants A and B. In addition to the 102 K glycoprotein, nonglycosylated polypeptides of about 58 and 164 K with different partial peptide maps were also consistently coimmunoprecipitated from [35S]methionine-labeled HHV-6A(GS)-infected cells, but not from HHV-6B(Z-29)-infected cells. The similarity in the molecular weights of glycoprotein gH among the two strains belonging to the two variant groups of HHV-6 and neutralization of infectivity of both groups by rabbit antibodies against HHV-6A(GS) gH suggests conserved functions of glycoprotein gH among the two variant groups of HHV-6.

Antibodies, Viral↗