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Biomedical subjects

W Pan

Publications and source records attributed to W Pan.

At least 145 records · Page 8Linked to original sources
PubMed1995

Serological survey of nasopharyngeal carcinoma in 21 cities of south China.

This paper reports the results of serological survey of 318,912 persons for nasopharyngeal carcinoma (NPC) in 21 cities and counties of south China. There were 8,441 persons with positive VCA-IgA antibody (single item positive) of EB virus (EBV), with a rate of 2.65%. In these VCA-IgA positive persons, 287 persons also had positive EA-IgA (double items positive) of EBV. The overall positive rate was 0.09%. 100 cases of NPC were found and 87 of them (87.0%) were in early stage. NPC found in the group with single item positive accounts for 1.19%, but the rate in the group with double items positive was 19.16% (55 cases). In NPC patients with double items positive, 49 cases were in early stage (89.1%). In 100 cases of NPC found, 45 cases appeared with negative EA-IgA, only with positive VCA-IgA, which indicated that for diagnosis of NPC, sensitivity of EA-IgA was lower than that of VCA-IgA, but its specificity was higher. Therefore, both can increase the detecting rate and early diagnosis rate of NPC. The age of people checked varied with different antibody positive rate and NPC detecting rate. The three items showed a positive correlation. The results are compatible with those of the prospective study for NPC in Wuzhou City, Guangxi, China. The method for NPC serological diagnosis can be extended and applied to raise the NPC detecting rate and early diagnosis rate at secondary prevention. And, it is further proved that there is a close relationship between NPC and EBV.

Adult↗
PubMed1994

Glucose-6-phosphatase gene expression and activity are modulated in hemorrhagic shock: evidence for a new heat-sensitive activator.

Decreased hepatic fructose 2,6-bisphosphate levels were observed in the early phase of hemorrhagic shock. The lower sugar bisphosphatae level was a result of increased phosphoenolpyruvate levels and decreased glucose-6-phosphate and fructose-6-phosphate levels. The decreased glucose-6-phosphate levels correlated with increased activity of liver glucose-6-phosphatase and a concomitant 2.5-fold increase in glucose-6-phosphatase mRNA abundance. In addition, protein-free filtrate from hemorrhagic shock rats, but not from control rats, increased glucose-6-phosphatase activity. However, when control and hemorrhagic shock protein-free filtrates were heated, they both increased the glucose-6-phosphatase activity of the respective microsomes to the same extent. It is concluded that the early hyperglycemic phase of hemorrhagic shock is due to enhanced glucose-6-phosphatase gene expression and activity and the generation of a heat sensitive activator of the enzyme.

Animals↗
PubMed1994

Isolation of a cDNA for the catalytic subunit of rat liver glucose-6-phosphatase: regulation of gene expression in FAO hepatoma cells by insulin, dexamethasone and cAMP.

cDNA clones coding for the catalytic subunit of rat liver glucose-6-phosphatase (EC 3.1.3.9) were isolated from a rat liver cDNA library in lambda gt11 phage. The sequence of the cDNA and the amino acid sequence derived from it were greater than 90% identical to the corresponding sequences for the mouse and human forms of liver glucose-6-phosphatase. Northern blot analysis of RNA from FAO hepatoma cells revealed that dexamethasone induced the glucose-6-phosphatase mRNA while insulin suppressed its expression. When both hormones were added together insulin completely suppressed the effect of glucocorticoid. cAMP addition alone decreased the abundance of glucose-6-phosphatase mRNA. The results demonstrate multihormonal regulation of gene expression of hepatic glucose-6-phosphatase and support a dominant role for insulin.

Amino Acid Sequence↗
PubMed1994

Pandas, people and policy.

Panda conservation in China has been plagued by controversy and cultural and political differences. But international cooperation, together with new studies identifying the main threats, offer renewed hope for the species' survival.

Animals↗
PubMed1994

Regulation of the permeability of the gonococcal cell envelope by the mtr system.

The mtrR gene of Neisseria gonorrhoeae controls the level of susceptibility to hydrophobic antibiotics and detergents. The mtrR gene was cloned and shown to encode a putative transcriptional repressor. The mtr region was homologous to the envCD and acrAB regions of Escherichia coli, which are also involved in susceptibility to hydrophobic compounds. A homologous repressor protein was encoded by a previously unrecognized open reading frame within both the envCD and acrAB regions. Deletion of mtrR resulted in increased resistance to antibiotics and detergents: the mtrR mutations in two penicillin-resistant clinical isolates resulted in a change of His-105 to Tyr. We propose that the mtrR repressor allows gonococci to regulate the permeability of its cell envelope in response to environmental signals, so that they can grow in the presence of toxic faecal lipids in the rectum as well as in the genital tract.

Amino Acid Sequence↗
PubMed1994

Expression and immunogenicity of tripeptide repeat region on P190 of Plasmodium falciparum.

A DNA fragment, designated as P190TR, encoding amino acid residues of the tripeptide region of the P190 antigen was amplified by polymerase chain reaction from genomic DNA of FCC1/HN Plasmodium falciparum isolated from Hainan Province, China. Upon comparison with the nucleotide sequences of MAD20 allele, it was found that there were five bases substitution in the P190TR which cause amino acid changes. The DNA fragment sequenced were ligated to BamHI and XbaI-digested pGEX-2T vector. Competent E. coli JM109 (DE3) were transformed with either parental or recombinant pGEX-2T for expression. Analysis of soluble cellular proteins revealed the high level expression of GST-P190TR as fusion proteins. Affinity purification of the fusion protein under nondenaturing condition resulted in the removal of almost all other E. coli proteins. The purified P190TR protein was highly immunogenic in rabbits. The antibodies against the recombinant protein recognized the malaria parasite with the titers at 1:320 measured by IFA and antisera from malarial patients reacted with the expressed protein in Western Blot.

Amino Acid Sequence↗
PubMed1994

The difference in EEG theta waves between concentrative and non-concentrative qigong states--a power spectrum and topographic mapping study.

The differences in EEG theta waves between concentrative and non-concentrative Qigong states were studied by means of power spectrum analysis and EEG mapping. The adult subjects included 20 practitioners of concentrative Qigong, 30 practitioners of non-concentrative Qigong and 23 control subjects. The results showed frontal mid-line theta rhythm was related to concentrative Qigong state. As the theta rhythm has been suggested to be one of the normal EEG patterns occurring in mental concentration, it is concluded that the theta rhythm is an indicator of mental concentration during Qigong state. This finding clarifies the implication of the theta rhythms appearing in Qigong and other meditation.

Adult↗
PubMed1993

Effect of diltiazem on altered glucose regulation during endotoxic shock.

Endotoxic shock is associated with profound metabolic alterations including hypoglycemia and hyperlactiacidemia. We studied hepatic glucose production and the role of diltiazem in affecting these metabolic alterations in a rat model of endotoxic shock. Fasted rats were intravenously injected with saline, endotoxin (20 mg/kg), endotoxin (20 mg/kg) plus diltiazem (1.2 mg/kg), or saline plus diltiazem. Five hours after the injections, the rats were anesthetized and blood samples were obtained for plasma glucose and lactate. The livers of all rats were then perfused in situ with an oxygenated 37 degrees C glucose-free Hanks' balanced salt solution at a rate of 30 ml/min via the portal vein and effluent was collected from the inferior vena cava. After 30 min equilibration, 5 mM lactate was added to the perfusate as a gluconeogenic substrate. Endotoxic groups exhibited hypoglycemia (64.5 +/- 12.7 mg/dl) and hyperlacticacidemia (4.3 +/- 0.63 mM). Diltiazem administration improved the hypoglycemia (96.9 +/- 9.1 mg/dl) and attenuated the hyperlacticacidemia (2.2 +/- 0.7 mM) in the endotoxic group. Gluconeogenic stimulation with lactate was demonstrated in both the control (18.1 +/- 2.3 vs 12.8 +/- 1.86 microns/g/hr, P < .05) and endotoxic (16.6 +/- 2.3 vs 9.8 +/- 1.1, P < .05) groups. However, stimulation in the endotoxic groups was significantly less compared with control. Gluconeogenic stimulation in the endotoxic group was unaffected after diltiazem administration. These data suggest that diltiazem treatment in endotoxic shock improves hypoglycemia and attenuates hyperlacticacidemia. These metabolic alterations are not associated with an improvement in substrate-specific stimulation of gluconeogenesis.

Animals↗
PubMed1993

[The pain components of somatosensory evoked potentials induced by median nerve stimulation P200-N300].

The pain components of somatosensory evoked potentials (SEPs) of induced by median nerve stimulation were studied with the way of blocking bloodstream of arm in 12 normal adults. The SEPs following the painful stimuli (0.1 msec. square wave pulse) of the right wrist were recorded from the left parietal (C3') and frontal (F3) scalp with earlobe reference electrode. The pressure of 40 mmHg above the arterial pressure was given to the right upper arm by sphygmomanometer. The result showed that the P200-N300 components (latency 234 +/- 13 msec. and 308 +/- 23 msec.) of the SEPs persisted and the others disappeared when tactile sensation disappeared but pain existed. The morphology of P200-N300 from F3 was same to that from C3'. It suggested the P200-N300 were the pain potentials of median nerve SEPs.

Adult↗
PubMed1993

Alterations in renal gluconeogenesis and blood flow during hemorrhagic shock.

The role of renal gluconeogenesis following hemorrhagic shock was studied. Hemorrhagic shock was induced in fasted, anesthesized rats by reduction of blood pressure to 40 mm Hg for either 30 or 150 min. Plasma samples were obtained for plasma glucose determination, and right renal arterial blood flow was determined with the help of an ultrasonic transit time blood flowmeter in hemorrhagic shock and control rats. The kidney was perfused via the renal artery with 37 degrees C oxygenated, glucose-free Krebs-Henseleit solution in the presence of 100 microM phloridzin to inhibit the cellular reuptake of glucose. Renal glucose production was determined by measuring glucose in both renal vein effluent and urine. After 30 min of equilibration, 5 mM lactate and 0.5 mM pyruvate were added to the perfusate as a gluconeogenic substrate, and effluent samples were collected after 5, 10, and 15 min. Moderate hyperglycemia was observed in vivo following 30 min of hemorrhagic shock, and significant hypoglycemia (P < .05) was observed following 150 min of hemorrhagic shock. Renal arterial flow was significantly decreased at 30 min (P < .05) and 150 min (P < .05) of hemorrhagic shock. Renal glucose production with and without substrate after 30 min of hemorrhagic shock was similar compared to control. Renal glucose production after 150 min of hemorrhagic shock was significantly decreased (P < .05) compared to control.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Overexpression of the c-erbB-2/neu-encoded p185 protein in primary lung cancer.

The c-erbB-2/neu gene encodes a transmembrane protein of 185 kDa (p185) with tyrosine kinase activity and extensive sequence homology to epidermal growth factor receptor. Amplification and overexpression of the c-erbB-2/neu gene has been shown in certain human tumors and is postulated to be important in human carcinogenesis. High levels of expression of the c-erbB-2/neu gene have been reported in non-small-cell lung cancer (NSCLC) cell lines and primary tumors from the United States. Since geographical and cultural factors may contribute to the development of certain types of cancer, we examined p185 examined p185 expression in 120 tumors from Chinese patients with lung cancers of different cell types and used immunohistochemical staining to determine the extent and general significance of p185 expression in human primary lung cancer. Our results demonstrate that 58.8% of the NSCLCs expressed p185 and that expression of p185 was observed only in NSCLC and not in small-cell lung cancers. Thirty-three of 41 adenocarcinomas and 24 of 55 squamous cell carcinomas among the NSCLCs examined were found to express p185 at levels different from those of normal lung. For the squamous cell carcinomas, p185 expression was correlated with lymph node metastasis (P less than 0.01), but for the adenocarcinomas, it was not (P greater than 0.05). In addition, expression of p185 in NSCLC was significantly more frequent in patients in advanced clinical stages. Our findings indicate that p185 expression is a frequent event and a general phenomenon in NSCLC and is correlated with poor clinical prognostic indicators, suggesting that expression of p185 may be of potential prognostic importance in NSCLC.

Adenocarcinoma↗
PubMed1992

Altered cellular calcium regulation and hepatic glucose production during hemorrhagic shock.

The relationship between intracellular Ca2+ and glucose production in the liver during early and late states of hemorrhagic shock was studied. Rats were anesthetized with intraperitoneal sodium pentobarbital and both femoral arteries and one femoral vein were cannulated. Rats were divided into two groups. One group was subjected to hemorrhagic shock by rapid withdrawal of blood to a mean arterial pressure of 40 mm Hg and maintained in shock for either 30 or 150 min. Rats in the control group were observed for the same time period. Hepatic glucose production was evaluated in both groups by a nonrecirculating liver perfusion model with and without lactate as a substrate. Intracellular free Ca2+ in hepatocytes was measured using the Ca2+ selective indicator Fura-2, under basal and epinephrine-stimulated conditions. Hyperglycemia and hyperlacticacidemia were observed in vivo at 30 min of hemorrhagic shock, whereas hypoglycemia and hyperlacticacidemia were observed at 150 min of shock. Hepatic glucose production in isolated perfused livers was significantly depressed at 30 min in animals subjected to shock (P less than 0.05). Lactate-induced glucose production was significantly attenuated at 30 and 150 min (P less than 0.05). Basal Ca2+, in isolated hepatocytes, at 30 and 150 min of hemorrhagic shock was significantly (P less than 0.05) higher than in controls. The hemorrhagic shock rat hepatocytes failed to evaluate intracellular free Ca2+ upon stimulation with 10(-5) M epinephrine. These results demonstrate that hemorrhagic shock is associated with an increase in hepatocyte intracellular Ca2+ concentration along with attenuation of hormone-mediated mobilization of calcium and substrate specific stimulation of hepatic glucose production.

Animals↗
PubMed1990

A study on an enhancer-like element in Escherichia coli.

An enhancer-like element of 1.0kb (JM103-M) from E. coli JM103 chromosome was isolated using an enhancer-probing vector. The JM103-M fragment was shown to stimulate the nearby CAT or beta-galactosidase gene expression in E. coli in both directions at a stimulation rate of 3-6. The same fragment was also demonstrated to have promoter function when a promoter-probing vector was tested. Results obtained from sequencing data showed that a sequence TGACTAA homologous to the AP-1 binding DNA motif of SV40 and two GC boxes were present.

Base Sequence↗
PubMed1988

Desensitization of adenosine A2 receptors in the striatum of the rat following chronic treatment with diazepam.

Following prolonged treatment (7 days) with diazepam (10 mg/kg/day, using ALZET mini-osmotic pumps) in rats, the function of adenosine receptors was assessed in specific structures of the brain, using both agonist ligand binding and adenylate cyclase assays. Binding to A1 receptors was quantified using [3H]N6-[(R)-1-methyl-2-phenylethyl] adenosine, a selective ligand at A1 receptors. Differences in the binding of this ligand and that of [3H]5'-N-ethylcarboxamide adenosine, which binds to both A1 and A2 subtypes of receptors with similar affinities, were used to quantify A2 receptors. Treatment with diazepam failed to alter the binding of [3H]N6-[(R)-1-methyl-2-phenylethyl] adenosine in all areas of the brain studied. However, the binding of A2 receptors and A2 receptor-mediated stimulation of adenylate-cyclase were significantly attenuated in striatal membranes from diazepam-treated rats. Thus, the present study indicated that functional adenosine A2 receptors were desensitized after prolonged treatment with diazepam, since decreased agonist binding to A2 receptors paralleled an attenuation in the stimulation by adenosine of the activity of adenylate cyclase, an effect mediated by the A2 receptor. These results further indicate that the changes in adenosine A2 receptors correlated with significant short-lasting alterations in the sleep-wake cycle during the withdrawal of diazepam. The alterations in sleep-wakefulness did not correlate with the effect of diazepam on benzodiazepine receptors since no changes were observed in the binding of benzodiazepine receptors.

Adenylyl Cyclases↗
PubMed1985

Lysosome-associated membrane proteins: characterization of LAMP-1 of macrophage P388 and mouse embryo 3T3 cultured cells.

Lysosome-associated membrane protein (LAMP)-1, a major glycoprotein of mouse embryo 3T3 cells and specifically associated with the lysosomal membrane, has been identified in P388 macrophage cells and compared with the homologous glycoprotein of NIH 3T3 cells. Immunofluorescence microscopy with anit-LAMP-1 monoclonal antibodies shows that the antigen was distributed throughout P388 cells including the ruffled edges or pseudopodia, identical to the pattern of acridine orange accumulation. LAMP-1 was purified from P388 cells by affinity chromatography with 1D4B monoclonal antibody, yielding a homogeneous glycoprotein comprising 0.1% of the total detergent-extracted cell protein. The apparent mass of P388 LAMP-1 was 130,000 to 150,000 compared to the 3T3 glycoprotein of 105,000 to 115,000. Analysis of tryptic peptides indicated that the two purified glycoproteins were highly homologous. Protein synthesis was analyzed in a variety of cell lines by pulse-chase labeling with [35S]methionine; in every case, LAMP-1 was synthesized as a precursor of apparent Mr 92,000, and then converted to heterogeneous mature forms differing in average Mr from 110,000 to 140,000. The basis for these apparent differences in mass was examined by studies of the biosynthesis and oligosaccharide composition of the glycoprotein. Core polypeptides of 45,000 Da were obtained from both HaNIH and P388 cells by treating immunoprecipitates of [35S]methionine pulse-labeled molecules with endoglycosidase H. Cells treated with monensin contained heterogeneous molecules of 80,000 to 85,000 Da. Isoelectric heterogeneity of mature LAMP-1 was markedly reduced by treatment with neuraminidase whereas there was little effect on the apparent molecular weight of the molecules or the differences between the various cell lines. beta-D-Xyloside inhibition of glycosaminoglycan synthesis had little effect on the apparent mass of LAMP-1.

Animals↗