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Biomedical subjects

G Wei

Publications and source records attributed to G Wei.

At least 91 records · Page 5Linked to original sources
PubMed1996

[Studies on microcystin contents in different drinking water in highly endemic area of liver cancer].

In order to study the pollution with microcystin (MC), a potent liver promoter, in drinking water in highly endemic area of liver cancer, cyanobacteria and its product MC were detected in drinking water in Haimen, Jiangsu Province during 1992 to 1993. Oscillatoria was identified as the most common species of cyanobacteria in pond-ditch and river water in Haimen, Jiangsu Province, which can produce MC. MC was detected in two of 65 water samples with high performance liquid chromatography, liquid chromatography and mass spectrography. In addition, studies were conducted in 989 samples collected from drinking water in Haimen, Jiangsu Province and more sensitive ELISA was used to detect their MC contents. Results showed proportions of samples with positive MC (greater than 50 pg/ml) were 17.3%, 31.9%, 4.3% and 0 for pond-ditch, river, shallow and deep well water, respectively, with average contents of 101, 160, 68 and 0 pg/ml, respectively. Proportions of positive MC samples and average MC contents for pond-ditch water were significantly greater than those in shallow and deep well water. It suggests studies on relationship between MC and liver cancer should be conducted further.

Carcinogens↗
PubMed1996

[A comparative study of cervical and thoracic anastomoses after esophagectomy for esophageal carcinoma].

From April 1979 to December 1984, esophagectomy was performed in 552 cases of esophageal cancer of which 108 received cervical anastomosis and 444 intrathoracic anastomosis. The total postoperative complications and operative mortality rates of the two groups were very close. Leakage was significantly more frequent after cervical anastomosis, but mortality due to leakage was less frequent than that in thoracic anastomosis. The 1-, 3-, 5-, 10-year survival rates of cervical anastomosis were apparently higher than those of intrathoracic anastomosis, but the differences were not statistically significant. The 5-year survival rates of patients with the same TNM stage failed to demonstrate any significant difference between the two groups. The quality of life among the groups was satisfactory. There was no deterioration of the quality of life in cervical anastomosis. It caused less gastroesophageal reflux than did intrathoracic anastomosis. We hold that esophagectomy with cervical anastomosis and extensive lymphadenectomy is a better treatment of choice for carcinoma of the esophagus.

Adult↗
PubMed1996

[Intellectual status of patents cerebral cysticercosis].

OBJECTIVE: To study the intellectual status of patients with cerebral cysticercosis with dementia evaluation scale. METHODS: The intellectual status of 112 patients with cerebral cysticercosis was studied with Hasagawa dementia evaluation scale and that of 30 patients with event related potential of P 300. RESULTS: In the patientsl, 50.9% suffered from mental dysfunction. Among them 11.6% had severe abnormality, 13.4% moderate, and 25.9% mild. Hypertension, epileptic attack and improper medication may cause intellectual dysfunction. CONCLUSIONS: Protection of mental function should be considered when chosing the treatment for better recovery of the patients. Hypertension, epileptic attack and improper medication may cause intellectual dysfunction.

Brain Diseases↗
PubMed1995

Comparison of the pharmacokinetics of two nicotine transdermal systems: nicoderm and habitrol.

This randomized, crossover study compared the nicotine and cotinine pharmacokinetic parameters and plasma concentration profiles of two different nicotine transdermal products: Nicoderm (Alza, Palo Alto, CA; and Marion Merrell Dow, Kansas City, MO) and Habitrol (Basel Pharmaceuticals, Summit, NJ). The two treatments were randomly assigned to each of 24 male smokers and worn for 24 hours each day for 5 days, with a 6-day washout between treatments. Plasma nicotine and cotinine concentrations were measured on day 1 and day 5 of each treatment. Mean delivered dose differed significantly between products, and the two products were not bioequivalent. The Nicoderm system provided higher mean plasma nicotine concentrations, particularly during the first 8 hours after system application. The mean steady state Cmax, AUC, and degree of fluctuation (DF) values were significantly greater for the Nicoderm system than for Habitrol. The mean nicotine tmax value for the Nicoderm system was significantly shorter (P < .001) than that for Habitrol (2.7 versus 8.6 hours). Steady state cotinine AUC values and plasma concentrations were significantly lower for Habitrol than for the Nicoderm system. The incidence of adverse events was similar for both products.

Administration, Cutaneous↗
PubMed1995

Schistosoma mansoni hexokinase: cDNA cloning and immunogenicity studies.

DNA encoding a Schistosoma mansoni hexokinase (SHEX) was amplified from cDNA by the polymerase chain reaction using opposing oligonucleotide primers designed to hybridize with two short segments of hexokinase coding sequences that are well-conserved through evolution. The resulting DNA fragment was then used as a probe to identify a full-length hexokinase cDNA clone. SHEX cDNA encodes a 50-kDa protein that is approximately 46% homologous to rat hexokinase, 40% to rat glucokinase, and 34% to yeast hexokinase A. SHEX coding DNA was expressed within Escherichia coli cells and the 50-kDa recombinant product (rSHEX) was partially purified. Mice repeatedly immunized with rSHEX produced antibodies which recognize rSHEX but this offered no significant protection against subsequent cercarial challenge. On Western blots, rSHEX is weakly recognized by antisera against rat brain hexokinase but not by sera from three strains of mice experimentally infected with S. mansoni parasites or from numerous human schistosomiasis patients. Thus, unlike other reported S. mansoni glycolytic enzymes, hexokinase appears to be poorly immunogenic during schistosome infection and of limited potential as a vaccine candidate.

Amino Acid Sequence↗
PubMed1995

Generation and reactions of the disulphide radical anion derived from metallothionein: a pulse radiolytic study.

OH-radicals were generated by pulse radiolysis of aqueous solutions of rabbit (Zn,Cd)-metallothionein (MT). They react with MT mainly by forming a thiyl radical with a rate constant of 1.7 x 10(12) dm3 mol-1 s-1. The thiyl radical reacts rapidly but reversibly with a thiolate function to form RSSR.-: RS + RS- reversible RSSR.-. The kinetics of the formation and decay of this radical anion have been studied pulse radiolytically by monitoring the evolution of the optical absorption of RSSR.- at 450 nm. This process is mostly intermolecular, i.e. bimolecular in MT. In the absence of O2, RSSR.- decays bimolecularly: RSSR.(-)+RS.-->RSSR + RS-. In the presence of O2, RS. may be scavenged by O2 and thus the yield of RSSR.- decreases: RS.+O2 reversible RSOO.. Under these conditions RSSR.- decays by first-order kinetics: RSSR.(-)+O2-->RSSR + O2.-. The rate constants of these reactions have been determined at room temperature: k4 = 1.8 x 10(9) dm3 mol-1 s-1, k5 = 7 x 10(4) s-1, k10 = 9.2 x 10(8) dm3 mol-1 s-1, and k18 about 3 x 10(7) dm3 mol-1 s-1. From the dependence of the maximal absorbance at 450 nm on the thiolate concentration in the absence of oxygen, epsilon (RSSR.-) = 9 x 10(3) dm3 mol-1 cm-1 and the stability constant (K4/5) of 2.3 x 10(4) dm3 ml-1 was determined. K4/5 is in good agreement with that determined kinetically, k4/k5 = 2.6 x 10(4) dm3 mol-1. The stability constant K15/16 of the thiylperoxyl radical, RSOO., was determined to be 5.5 x 10(3) dm3 mol-1.

Animals↗
PubMed1995

Double-C-peptide human proinsulin.

A fusion gene encoding double-C-peptide human proinsulin was constructed by insertion of a DNA fragment encoding human C-peptide into the 5'-terminal C-peptide coding sequence of a synthetic human proinsulin gene with correct reading frame and over-expressed in E. coli. The purified double-C-peptide human proinsulin shows decreased activity in receptor binding and insulin immune assays as compared with human proinsulin. Disulphide bond reconstitution studies demonstrate that there is not much more influence of the protein concentration on the yield of refolded double-C-peptide human proinsulin. The double-C-peptide human proinsulin shows a 1.86-fold human C-peptide immune activity as compared with that of human proinsulin and gives a good yield of the molecule with correct disulphide bonds in reconstitution studies strongly suggesting the existence of very flexible conformation of the C-peptide.

Amino Acid Sequence↗
PubMed1995

Formation of inclusion bodies may be the key factor for the stability of expressed products in E. coli.

Des-B30 single-chain insulin gene was constructed from chemically synthesized DNA encoding human proinsulin by oligo-nucleotide induced deletion, cloned into the expression plasmid pBV220, and expressed in E. coli with a level of around 5%. The expressed product was in the form of inclusion bodies. After downstream processing, 45 mg of des-B30 single-chain insulin with a purity of up to 90% was obtained from 1 liter of high density fermentation medium. It is suggested that the fusion protein model to increase the stability of small proteins seems inadequate to some extent, the formation of inclusion bodies may be the key factor for the stability of some expressed products, large or small, in the cytoplasm of E. coli cells.

Base Sequence↗
PubMed1994

Two N-acetylglucosaminyltransferases catalyze the biosynthesis of heparan sulfate.

We report that two N-acetylglucosaminyltransferases catalyze the biosynthesis of heparan sulfate in Chinese hamster ovary cells. The first enzyme initiates heparan sulfate biosynthesis and can be measured by the transfer of GlcNAc from UDP-GlcNAc to GlcUA beta 1-3Gal beta 1-O-naphthalenemethanol. The second enzyme catalyzes the polymerization of heparan sulfate and can be measured by the transfer of GlcNAc from UDP-GlcNAc to the nonreducing terminal GlcUA present in oligosaccharide fragments prepared from the Escherichia coli K5 capsular polysaccharide, N-acetylheparosan. Kinetic characterization of the initiating GlcNAc-transferase (alpha-GlcNAc-TI) indicates an apparent Km for UDP-GlcNAc of 36 +/- 4 microM. The apparent Km for UDP-GlcNAc of the polymerizing GlcNAc-transferase (alpha-GlcNAc-TII) is 230 +/- 30 microM. Both enzymes have broad pH optima and require a divalent cation for activity. alpha-GlcNAc-TI can use both Mn2+ and Ca2+, while alpha-GlcNAc-TII will use only Mn2+. Chinese hamster ovary cells deficient in the synthesis of heparan sulfate and lacking alpha-GlcNAc-TII activity and S49 Thy 1-a lymphoma cells deficient in alpha GlcNAc addition to phosphatidylinositol have wild-type alpha-GlcNAc-TI activity. Thus, distinct alpha-GlcNAc-transferases catalyze the initiation and polymerization of heparan sulfate.

Animals↗