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Biomedical subjects

J Gao

Publications and source records attributed to J Gao.

At least 379 records · Page 21Linked to original sources
PubMed1996

[Management of pregnant women with abnormal cervical smears. A series of 146 patients].

OBJECTIVES: Evaluation of the value of colposcopy and directed biopsy in the follow-up of pregnant women presenting with abnormal cervical smear. MATERIAL AND METHODS: Retrospective study of 146 patients examined by colposcopy during pregnancy between January 1985 and December 1994. RESULTS: Colposcopy was satisfactory in 86% of patients. Colposcopic impression was concordant with the final diagnosis, overestimated and underestimated in 69%, 18% and 13% of the cases, respectively. Directed biopsies were performed in 115 patients. In one case, bleeding necessitated vaginal packing for 24 hours. Directed biopsy correlated well with the final diagnosis in 87% of low grade CIN and in 90% of high grade CIN. In 4 patients, conisation was performed between 10 and 16 weeks of gestation without subsequent obstetrical complications. CONCLUSION: Colposcopy with directed biopsy is a reliable tool to evaluate abnormal smear during pregnancy.

Adolescent↗
PubMed1996

Preparation, cloning, and high level expression in E. coli of interleukin 2-pseudomonas exotoxin fusion genes.

Using PCR and oligonucleotide-directed mutagenesis, recombinant plasmids which express IL2-PE fusion genes, e.g., IL2-PE40, IL2-PE40 KDEL, IL2-PE66(4Glu), and IL2-PE66(4Glu) KDEL, were constructed and expressed in E. coli at a high level. The fusion proteins were 20-30% of the total soluble bacterial proteins, existing as inclusion bodies in the host cell. In addition, there are single EcoRI, PstI, and SmaI restriction sites at the 5', 3' terminals and the linking region of the fusion genes, respectively, in the constructed expression plasmids so that these vectors could be conveniently converted to other expression vectors containing other cytokines or toxins.

ADP Ribose Transferases↗
PubMed1996

[Establishment of anti-HCV NS5 alpha McAb hybridoma cell lines and its application on clinical immunohistochemical diagnosis].

OBJECTIVE: To prepare hybridoma cell lines which secrete anti-HCV recombinant NS5a protein monoclonal antibodies, and to evaluate their usage in investigating the distribution of HCV NS5a antigen in liver tissue. METHODS: The hybridoma cell lines were raised using the conventional protocols. The immunohistochemistry of paraffin embedded liver tissue was performed to determine the distribution of HCV NS5a antigen as well as NS3 antigen in liver tissue. RESULTS: Four hybridoma cell lines, which secrete monoclonal antibodies against HCV NS5a protein, were raised and named as 8B2, 6F11, 4C6 and 7D9. They had specific reaction with HCV NS5a protein and had no reaction with HCV core and NS3 proteins. Immunohistochemistry results indicated that 54.8% of anti-HCV positive patient's liver specimens were positive and 70.6% of active cirrhosis positive. CONCLUSION: The monoclonal antibodies we prepared here are specific to the recombinant HCV NS5 alpha protein and they can be used in the clinical immunohistochemistry diagnosis.

Animals↗
PubMed1996

[Studies on MDM2 oncogene expression and its effect on pancreatic carcinoma cells].

In order to study the interrelation and interaction between MDM2 oncogene and wild type p53 in human pancreatic cancer, we studied the expression and amplification of MDM2 oncogene and its antagonistic effect on wild type p53 by use of gene recombination, gene transduction and molecular hybridization techniques. The results showed that MDM2 oncogene could be detected in all 5 pancreatic cell lines, but MDM2 mRNA expression varied in the different cell lines. The recombinant vector pCMV-MDM2 was transduced into PC-2/s-wtp53 cell line (a transformed PC-2 pancreatic carcinoma cell line containing wild type p53 gene). The resultant cell line, PC-2/s-wtp53/pCMV-MDM2 showed rapid cell growth, a rate similar to that of the parent cell line PC-2. Our results verify the fact that MDM2 gene can abrogate the cell growth arrest mediated by wild type p53 and the antagonistic function of wild type p53.

Adenocarcinoma↗
PubMed1996

[Dynamic changes of endothelin in sera of rats at early burn stage and its effects on endothelial cell permeability in vitro].

The dynamic changes of endothelin in sera of early burnt rats and the effects of endothelin-1 on the permeability of vascular endothelial cells were investigated. In the early phase of 30% (II degree) total body surface area (TBSA) burn rat model, we measured the concentration of endothelins in plasma, the water contents in main organs and the permeability of endothelial monolayer cultured on micropore membrane to Hank's solution or 5 g/L albumin Hank's solution. Endothelin concentration in burnt rat sera was firstly increased dramatically, showing a peak at 6 hours postburn, and then remained significantly higher than the basic level (P < 0.01). The changes of endothelin were correlated with the alteration in water contents in main organs after burn. Moreover, if the cultured endothelial cells were exposed to 0, 1, 10, 100 nmol/L endothelin 1 for 60 min, it was found that the filtration volume (Jv) and the filtration coefficient (Kf) of endothelial monolayer were significantly enhanced as determined by either Hank's or albumin (5 g/L) perfusion, while the osmotic reflection coefficient (sigma) (to protein) decreased in a dose-dependent pattern. The present results suggest that the postburn elevated endothelin may not only mediate the blood flow distribution via potent vasoconstriction, but also directly increase the vascular permeability. The mechanism(s) of the latter event needs to be further clarified.

Animals↗
PubMed1995

Mechanisms of proton-induced stimulation of CGRP release from rat antrum.

Mechanisms of acid-evoked CGRP release from gastric afferent nerves were investigated in rat antral mucosal/submucosal tissues. Low pH (pH 4.0, 5.0 and 6.0) stimulated antral CGRP release significantly and dose-dependently from rat antral fragments. Removal of extracellular calcium from the incubation medium resulted in significant inhibition (59%, P < 0.001) of acid (pH 4.0)-stimulated CGRP release. Conotoxin (1 x 10(-7) M), the selective blocker of N-type calcium channels, also significantly inhibited proton (pH 4.0)-induced CGRP release to values that were 74% below net stimulated levels. Neither nifedipine (1 x 10(-6) M), the L-type Ca(2+)-channel antagonist, nor indomethacin (1 x 10(-5) M), inhibitor of prostaglandin synthesis, altered acid-induced CGRP release. In contrast, ruthenium red (1 x 10(-5) M), capsaicin antagonist, almost completely prevented acid (pH 4.0)-stimulated CGRP release. Capsazepine (1 x 10(-4) M), a specific capsaicin receptor antagonist, also completely abolished acid-induced CGRP release. In conclusion, the results of these studies indicate that hydrogen ions are capable of evoking CGRP release from peripheral sensory neurons in rat antral mucosal/submucosal tissues. Proton-evoked CGRP release requires extracellular calcium and involves N-type calcium channels. Furthermore, acid appears to exert a capsaicin-like effect to evoke sensory neuropeptide release that is sensitive to capsazepine and ruthenium red. These data suggest that proton-induced antral CGRP release represents a direct action of hydrogen ions on mucosal/submucosal sensory dendritic nerve endings to effect local release of neuropeptide.

Animals↗
PubMed1995

Using capillary electrophoresis to follow the acetylation of the amino groups of insulin and to estimate their basicities.

Capillary electrophoresis (CE) is an analytical method that is useful for investigating processes that modify the charge of proteins. This paper explores the ability of CE to rationalize charges and electrophoretic mobilities of a simple protein--insulin and its acylated derivatives--as a function of pH. Insulin is a peptide hormone (MW = 5700) that has two alpha-amino groups (G alpha and F alpha) and one epsilon-amino group (K epsilon). Treatment of insulin with acetic anhydride affords seven derivatives that differ in the sites of acetylation of the three amino groups. Analysis of the pH dependence of the electrophoretic mobilities of these derivatives gives pKa values for the two N-terminal ammonium groups: pKa (G alpha) = 8.4; pKa (F alpha) = 7.1. Values of the total charge of insulin estimated from electrophoretic mobility differ from those estimated from values of pKa for its ionizable groups by less than 0.5 unit for both bovine and human insulins over the range of pH from 5.5 to 9.5. Analysis of the concentration dependence of the electrophoretic mobility of insulin yields a lower limit for the association constant for dimerization of insulin of KD > or = 6 x 10(3) M-1 (25 mM tris and 192 mM Gly, pH 8.4). Studies of electrophoretic mobility as a function of pH and extent of acetylation of amino groups rationalize the charge of insulin in detail. The sensitivity of CE to charge permits the quantitative study of electrostatic properties of proteins in solution. Insulin is a useful small-protein model with which to investigate phenomena in electrophoresis.

Acetylation↗
PubMed1995

Increasing binding constants of ligands to carbonic anhydrase by using "greasy tails".

Two series of para-substituted benzenesulfonamides have been examined as inhibitors for bovine carbonic anhydrase II (CAII, EC 4.2.1.1). Both series have hydrophobic alkyl group R connected by amide linkages to the aromatic ring (H2NO2SC6H4-CH2NHCOR1 and H2NO2SC6H4-CONR2R3). The free energy of partitioning (delta Gp) of these ligands between water and octanol had similar, linear correlations with the molecular surface areas of the hydrophobic groups R; delta Gp was only relatively weakly influenced by the linkage to the benzenesulfonamide and the detailed structure of the group R. Binding of these ligands to CAII was more complicated. For compounds having the structure H2NO2SC6H4-L-R, the dependence of the free energy of binding to CAII on the surface area of the hydrocarbon (fluorocarbon) group R for different -L-R was (d delta Gb/dA, kcal/(mol.100 Angstrum 2): -CH2NHCORH, -0.71 +/- 0.03; -CH2NHCORF, -0.72 +/- 0.07; -CONHCH2RH, -2.5 +/- 0.1; and -CONHCH2RF, -2.7 +/- 0.3. The available data permit several conclusions: (i) details (linear, branched, cyclic) of the structure of the group RH are relatively unimportant in determining binding constants (although cyclic structures may bind slightly more strongly than acyclic ligands with the same carbon number); (ii) for a given class of compounds, binding constants of hydrocarbons and fluorocarbons having the same surface area are very similar; and (iii) the nature of the linker L influences the sensitivity of binding to the surface area of the group R, presumably by its influences in positioning the group in the binding pocket of the enzyme. Fluorocarbons seem to be more hydrophobic than hydrocarbons of the same carbon number because they have larger areas of hydrophobic surface; the hydrophobicity of hydrocarbon and fluorocarbon surfaces are similar, after correction for differences in area.

Animals↗
PubMed1995

An enzyme-linked immunosorbent assay to identify inhibitors of activation of platelet integrin alpha IIb beta 3.

The affinity of integrin alpha IIb beta 3 for adhesive ligands is tightly regulated by the platelet such that fibrinogen binding is observed only after platelet activation. Ligand binding is necessary for platelet aggregation, which contributes to vascular occlusion in pathological states. Therefore, we have developed an ELISA assay to screen for compounds that inhibit alpha IIb beta 3 activation. Washed platelets were incubated in microtitre wells with potential inhibitory compounds and stimulated with an agonist to activate alpha IIb beta 3. After the addition of biotin-PAC1, a fibrinogen-mimetic monoclonal antibody, the activation state of alpha IIb beta 3 was measured by sedimenting the platelets and quantitating the residual biotin-PAC1 in the cell-free supernatant in a streptavidin-based ELISA. This assay detected (1) specific PAC1 binding to activated platelets in response to a variety of agonists, and (2) dose-dependent inhibition of PAC1 binding by function-blocking anti-alpha IIb beta 3 monoclonal antibodies, by the tetrapeptide, RGDS, and by an alpha IIb beta 3-selective RGD peptidomimetic. Furthermore, the assay detected inhibition of PAC1 binding by intracellular inhibitors of platelet activation, including bisindolylmaleimide, a selective protein kinase C antagonist, and wortmannin, an inhibitor of phosphatidylinositol 3-kinase. These studies demonstrate that this integrin activation ELISA can detect pharmacological blockade of platelet alpha IIb beta 3 by extracellular and intracellular inhibitors. Its use may facilitate the search for clinically useful anti-platelet drugs.

Blood Platelets↗
PubMed1995

Cloning and characterization of a mouse gene with homology to the human von Hippel-Lindau disease tumor suppressor gene: implications for the potential organization of the human von Hippel-Lindau disease gene.

The human von Hippel-Lindau disease (VHL) gene has recently been identified and, based on the nucleotide sequence of a partial cDNA clone, has been predicted to encode a novel protein with as yet unknown functions [F. Latif et al., Science (Washington DC), 260: 1317-1320, 1993]. The length of the encoded protein and the characteristics of the cellular expressed protein are as yet unclear. Here we report the cloning and characterization of a mouse gene (mVHLh1) that is widely expressed in different mouse tissues and shares high homology with the human VHL gene. It predicts a protein 181 residues long (and/or 162 amino acids, considering a potential alternative start codon), which across a core region of approximately 140 residues displays a high degree of sequence identity (98%) to the predicted human VHL protein. High stringency DNA and RNA hybridization experiments and protein expression analyses indicate that this gene is the most highly VHL-related mouse gene, suggesting that it represents the mouse VHL gene homologue rather than a related gene sharing a conserved functional domain. These findings provide new insights into the potential organization of the VHL gene and nature of its encoded protein.

Amino Acid Sequence↗
PubMed1995

Skeletal muscle glucose transport and metabolism are enhanced in transgenic mice overexpressing the Glut4 glucose transporter.

Skeletal muscle glucose transport and metabolism were studied in a line of transgenic mice overexpressing the human Glut4 facilitative glucose transporter. Skeletal muscle Glut4 protein levels were increased 2-4-fold in transgenic animals relative to their nontransgenic litter mates. Glut4 overexpression increased total transport activity (measured with 1 mM 2-deoxy-D-glucose) in the isolated extensor digitorum brevis muscle in the presence of insulin; this increase was due to 1) an increase in basal glucose transport (0.8 +/- 0.1 versus 0.5 +/- 0.1 mumol.ml-1.20 min-1 in transgenic and control mice, respectively) and 2) an increase in insulin-stimulated transport (1.5 +/- 0.1 versus 0.8 +/- 0.1 mumol.ml-1.20 min-1 above basal transport in transgenic and control mice, respectively). Glut4 overexpression also increased glucose transport stimulated by muscle contractions. In addition, glycolysis and glucose incorporation into glycogen were enhanced in muscle isolated from transgenic mice compared to controls. These data demonstrate that Glut4 overexpression in skeletal muscle increases insulin- and contraction-stimulated glucose transport activity and glucose metabolism. These findings are consistent with the role of Glut4 as the primary mediator of transport stimulated by insulin or contractions.

3-Hydroxybutyric Acid↗
PubMed1995

Synovial reaction and concentrations of proteoglycan fragments in joint fluid after intraarticular knee injuries.

In patients with pathology to cruciate ligaments, menisci and cartilage and in some patients with symptomatic knees without gross intraarticular changes, proteoglycan fragment concentrations in joint fluid and inflammatory reaction of the synovium were related to the cartilage condition. There was a weak positive correlation between increased concentrations of proteoglycan fragments in joint fluid and the degree of cartilage degeneration, indicating higher concentrations in knees with more advanced cartilage destruction, but there was no correlation to the synovial reaction at histological inspection. However, in most knees the synovial tissue was infiltrated by inflammatory cells. Symptomatic knees free from gross intraarticular pathology showed similar synovial changes and concentrations of proteoglycan fragments in joint fluid as knees with intraarticular pathology and obvious cartilage degeneration. The complex process of proteoglycan synthesis, release, degradation, and clearance from joint fluid apparently caused the weak or absent correlations between this 'marker' protein and the degree of synovitis and arthrosis stage.

Adolescent↗
PubMed1995

Proton microprobe assessment of the distribution of fluoride in the enamel and dentine of developing central incisors of sheep and changes induced by daily fluoride supplements.

Ten sheep were given 0.5 mg fluoride (F) and 10 sheep 0.2 mg F/kg body wt orally for periods of 1-6 months while 8 sheep received no additional F. One incisor from each sheep was sectioned longitudinally in the midline and, using the proton microprobe, multiple scans for calcium and F were made across the enamel and dentine. F was determined by proton-induced gamma-ray emission and calcium by X-ray emission. Tooth length and hence the stage of ameloblast activity for each of the 28 teeth at the start of the experiment was determined using a tetracycline marker. In addition, the stage of enamel development of the eight control teeth (no dietary F) at the time of their extraction was assessed from their macroscopic appearance. Continuous changes in F levels occurred in both enamel and dentine throughout tooth development and also in the mature enamel and associated dentine after ameloblast regression. All scans for all stages of tooth development and all F treatments showed a high F concentration at the enamel surface. Early in the secretory phase, a wide-based F peak occupied the entire width of the enamel with a similar F peak in the dentine. In the control teeth, no consistent increase in F concentration occurred at the enamel surface during later development. When F supplements were started early in the maturation phase an increase in F concentration only at the enamel surface was recorded. When F supplements were also given during the secretory phase, higher F concentrations were recorded not only at the enamel surface but also for the inner enamel and dentine plateau. These findings, based on a small number of sheep, indicate that further research is needed to clarify the method and control of F uptake and to determine the changes in these processes during the different stages of tooth development.

Amelogenesis↗
PubMed1995

Calcitonin gene-related peptide modulates acid-mediated regulation of somatostatin and gastrin release from rat antrum.

BACKGROUND & AIMS: Acid has been shown to stimulate calcitonin gene-related peptide (CGRP) release from peripheral sensory afferent nerve endings in the stomach. The aim of this study was to determine whether endogenous CGRP was involved, by a neurocrine mechanism, in acid-mediated stimulation of somatostatin and inhibition of gastrin release. METHODS: A two-compartment sleeve of antral mucosal/submucosal tissue was perfused to determine sensory nerve and endocrine cell responses to luminal acid. CGRP receptor antagonist, CGRP8-37, was used to inhibit the actions of endogenously released CGRP. RESULTS: Perfusion of the antral sleeve lumen with media of increasing hydrogen ion concentration caused pH-dependent increases in CGRP and somatostatin release and decrease in gastrin release. CGRP8-37 inhibited significantly basal somatostatin (-36%) and stimulated basal gastrin (+65%) release (P < 0.02). Furthermore, CGRP8-37 administration prevented luminal acid-mediated inhibition of gastrin release and stimulation of somatostatin release. These results indicate that CGRP8-37 prevented acid-mediated feedback inhibition of gastrin release and acid-induced feedforward somatostatin release. CONCLUSION: These results suggest that CGRP plays an important role in the response of antral D and G cells to luminal acid and that local effector action of endogenous CGRP participates in regulation of antral regulatory peptide secretion.

Analysis of Variance↗