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C Wang

Publications and source records attributed to C Wang.

At least 1,027 records · Page 57Linked to original sources
PubMed1993

Effect of ICI197067, a kappa-opioid receptor agonist, spinally on A delta and C reflexes and intracerebrally on respiration.

Intrathecal (i.t.) injection of a kappa-opioid receptor agonist, ICI197067, caused a similar dose dependent depression of A delta and C fibre mediated nociceptive reflexes in renal sympathetic nerves due to supramaximal electrical stimulation of tibial nerves in anaesthetized dogs. A total dose of 8 mg i.t. abolished these reflexes. When administered into the 4th ventricle (i.c.v.) in a total dose range from 0.1-2.5 mg ICI197067 caused no respiratory depression; a total dose of 10 mg i.c.v. abolished both phrenic nerve activity and spontaneous respiration. The ED50 ratio of ICI197067 for depression of respiration (i.c.v.) and somatosympathetic reflexes (i.t.) is approximately 1.5:1 compared with 0.3:1 for fentanyl. ICI197067 i.c.v. caused a similar reduction in arterial pressure compare to fentanyl without comparable changes in heart rate. Thus in terms of cardiorespiratory depression and blockade of A delta and C fibre pathways kappa-opioid receptor agonists may be safer and more effective for producing spinal analgesia than mu-opioid receptor agonists.

Animals↗
PubMed1993

Identification of an androgen-induced C3-P4 DNA binding protein in the cytosol of rat ventral prostate.

A DNA binding protein C3-P4 was detected in the rat ventral prostate cytosol by gel retardation assay using a 32P-labeled 31 base pair synthetic oligomers (sequence deduced from the rat prostatic steroid binding protein C3-1 gene promoter -149 to -119) as a probe. The DNA binding activity of C3-P4 DNA binding protein is sequence specific, with preference for single strand and coding strand exclusive. This protein can be detected in many androgen target tissues and controlled well by androgen in the rat ventral prostate, we speculate that this DNA binding protein may function as an accessory factor to androgen receptor (AR) for the regulation of the C3-1 gene expression.

Animals↗
PubMed1993

Hypocalcemia at parturition as a risk factor for left displacement of the abomasum in dairy cows.

Total and ionized serum calcium concentrations were measured in 510 Holstein cows at the time of parturition. Cows that subsequently developed left displacement of the abomasum (LDA) were compared with those that did not. Cows that were hypocalcemic at parturition had a 4.8 times greater risk of developing LDA than did normocalcemic cows. Hypocalcemia was associated with the development of LDA whether ionized serum calcium concentration or total serum calcium concentration was used to determine whether cows were hypo- or normocalcemic. The proportion of cows developing LDA was not significantly different between cows that had clinical signs of hypocalcemia and were treated for parturient paresis and cows that were hypocalcemic, but did not have clinical signs and were not treated.

Abomasum↗
PubMed1993

High-level expression of soluble rat hsc70 in Escherichia coli: purification and characterization of the cloned enzyme.

We have cloned the cDNA of rat hsc70 (clathrin-uncoating ATPase) into a T7 expression system and have expressed this enzyme in Escherichia coli. The recombinant clathrin-uncoating ATPase is in the cytosolic fraction of the bacterium and is soluble. It was purified to homogeneity by DEAE-cellulose and ATP-agarose column chromatography. From 1 litre of bacterial culture (0.3-0.4 g of proteins), 5-20 mg of pure recombinant clathrin-uncoating ATPase was routinely obtained. The cloned enzyme is capable of dissociating clathrin from bovine coated vesicle. Furthermore, it is not methylated on basic amino acid residues and is not blocked at the N-terminus, indicating that these modifications on hsc70 are not essential for uncoating of clathrin. Binding of [alpha-32P]ATP by purified recombinant hsc70 was analysed by Scatchard plot. The results indicate that there one high-affinity binding component with a Kd (dissociation constant) of 0.2-0.3 microM. The peptide-stimulated ATPase activities of recombinant hsc70 at 37 degrees C with respect to S-peptide peptides P3a and GT4 at a concentration of 1.2 mM are 142 +/- 6, 214 +/- 8 and 362 +/- 5 pmol/h per micrograms of hsc70 protein respectively. The EC50 values of hsc70 ATPase for S-peptide, peptides P3a and GT4 are 2, 0.67 and 0.17 mM respectively. On the other hand, the dissociation constants of S-peptide, peptides P3a and GT4 for recombinant hsc70 are 7.6, 13 and 100 microM respectively. Thus peptide GT4 is the only peptide examined for which the binding constant is comparable with the EC50 for stimulation ATPase activity, albeit it has the lowest affinity for hsc70.

Adenosine Triphosphatases↗
PubMed1993

Characterization of two allelic variants of a human pregnancy-specific glycoprotein gene.

The pregnancy-specific glycoproteins (PSGs) of the human placenta are a group of proteins that together with the carcinoembryonic antigens comprise a subfamily within the immunoglobulin superfamily. To study the control of PSG expression, we isolated and characterized PSG genes and identified cis-acting DNA elements in the 5'-flanking gene regions essential for PSG expression. Two overlapping PSG cosmid clones, which contain two allelic variants of a PSG gene (PSG12 and PSG12 psi), were isolated from an unamplified library made from a single individual. Cosmid 1 contains exons 1 (5'/L) and 2 (L/N) of the PSG12 gene located downstream of a previously identified PSG1-I gene. Cosmid 6 contains a portion of the PSG1-I gene lacking exons 1 and 2 upstream of a complete PSG12 psi transcription unit. Sequence comparison indicates that exons 5'/L and L/N in PSG12 and PSG12 psi are 99% identical, except that the L/N exon in the PSG12 psi gene contains a stop codon. Both PSG12 and PSG12 psi transcripts were detected in the human placenta, indicating that both genes are actively transcribed. However, the PSG12 psi gene may represent an allelic pseudogene variant of the PSG12 gene, because all identified PSGs contain a functional N-domain. Primer extension analysis showed that the PSG12 gene starts at a cluster of sites located at -106 to -104 base pairs with respect to the translation start site. In transient transfection assays using a chloramphenicol acetyltransferase reporter gene, we demonstrated that the -835 to -34 DNA region upstream of the translation start site of PSG12 or PSG12 psi contained both positive and negative elements that control PSG expression. Deletion analysis showed that nucleotides -172 to -34 in the PSG12 gene could function as a promoter. Gel retardation analysis showed that protein factors in human placental cell extract formed four complexes (I, II, IIa, and III) with the PSG12(-172/-34) DNA. Site-directed mutagenesis that prevents protein factor binding to the PSG12 promoter resulted in a marked reduction in transcription activation, locating the core enhancers at nucleotides -148 to -141 and -60 to -55. Mutagenesis studies also showed that the ACAGC repeats at nucleotides -84 to -68 in the PSG12 5'-flanking are essential for expression of the PSG12 gene in human placental cells.

Alleles↗
PubMed1993

Interferon alpha induces protein kinase C-epsilon (PKC-epsilon) gene expression and a 4.7-kb PKC-epsilon-related transcript.

Protein kinases play key roles in the induction by human interferon alpha (IFN-alpha) of specific gene expression and biological activity in various human cell lines. We now report that IFN-alpha increased the 7-kb transcript for the epsilon isotype of protein kinase C (PKC-epsilon) and the cellular content of PKC-epsilon 24 and 48 hr after IFN-alpha addition (a 2-fold and 6-fold increase, respectively). Furthermore, IFN-alpha markedly induced a 4.7-kb transcript that hybridized to a PKC-epsilon-specific, but not to a PKC-eta-specific, cDNA probe. The induction of the 4.7-kb PKC-epsilon-related mRNA by IFN-alpha had the following properties reported for the classical IFN-alpha-stimulated genes: rapid kinetics of induction, high maintained levels in IFN-alpha-sensitive but not in IFN-alpha-resistant cell lines, protein synthesis-independent induction, and high sensitivity to inhibitors of protein tyrosine kinase activity. These results show that the regulation of gene expression by IFN-alpha include not only the classical IFN-alpha-stimulated genes but also the coordinated regulation of two PKC-epsilon-related transcripts that appeared to be highly relevant to the biological actions of IFN-alpha.

Benzoquinones↗
PubMed1993

Results of cardiopulmonary resuscitation. Failure to predict survival in two community hospitals.

BACKGROUND: The use of closed chest cardiopulmonary resuscitation (CPR) has, since its initial description in 1960, expanded greatly. Recently, much energy has focused on identifying patients' probabilities of responding to CPR. The goal of this study was to determine the current rate of successful CPR in two community teaching hospitals and to identify patient characteristics associated with the likelihood of successful resuscitation. METHODS: A retrospective review of the medical records of all patients receiving CPR during 1988 and 1989 in two university-affiliated teaching hospitals. This review identified 300 patients who experienced in-hospital cardiopulmonary arrest during the study period. RESULTS: Survival of CPR and survival to hospital discharge were 53.9% and 23.3% in the combined populations. Likelihood of survival of CPR was increased when the initial rhythm was ventricular tachycardia or ventricular fibrillation and when the duration of CPR was less than 30 minutes. Survival to hospital discharge was associated with shorter duration of CPR. Combinations of variables did not allow improved prediction of resuscitation results but did aid in predicting survival to hospital discharge. Combinations of variables that were associated with survival in one hospital were not transferable to the other institution. CONCLUSION: Other than the length of resuscitation, easily accessible clinical variables provided limited predictive information about CPR results.

Aged↗
PubMed1993

Genomic organization and expression of the rat TRPM-2 (clusterin) gene, a gene implicated in apoptosis.

We describe the genomic structure of the rat TRPM-2 gene. This gene is induced de novo during the regression of the prostate and other hormone-dependent tissues after hormone ablation and plays an important role in apoptosis, or active cell death. TRPM-2 is a single copy gene, organized into nine exons, ranging in size from 47 base pairs (exon I) to 412 base pairs (exon IV), spanning a region of 13,750 base pairs. Comparison with sequences registered in the data bases shows that it has extensive homology to SGP-2, a gene that is expressed constitutively in the testis, although the sequences diverge dramatically in the 5'-untranslated region of the mRNA (coded for by exon I in TRPM-2), raising the possibility of alternative exon I usage in SGP-2. Primer extension, S1 nuclease protection, and extensive polymerase chain reaction analysis suggest that the TRPM-2 transcript from the prostate and the SGP-2 transcript from the testis are in fact identical and only contain the exon I sequence identified in the TRPM-2 genomic clone. Analysis of the promoter region of the TRPM-2 gene demonstrates that the putative control region contains several potential regulatory elements that may regulate the complex tissue-specific control of a gene which must be constitutively expressed in some tissues but repressed in others until induced during active cell death.

Amino Acid Sequence↗
PubMed1993

Insuring Latinos against the costs of illness.

OBJECTIVE: To examine the determinants of health insurance coverage for Latinos in the United States and how different targeted strategies for health care reform differentially affect the country's major ethnic groups, focusing on the implications for the Latino population. DESIGN: Data from the 1980 and 1990 Current Population Surveys were used to compare the insurance status of nonelderly (< 65 years) Latinos with the Anglo (non-Hispanic white), black, and Asian and other populations by estimating the attributable fraction for selected covariates. The effects of health care reform strategies on the coverage of the major ethnic groups were simulated from these data. MAIN OUTCOME MEASURES: Percentage uninsured, percentage insured by Medicaid, and attributable fraction for covariates. RESULTS: Latinos have the worst health insurance coverage of any ethnic group in the country. Approximately 39% of Latinos are uninsured compared with 13.8% for the Anglo and 24% for the black population. Providing coverage to all the poor could reduce the uninsured rate for Anglos by about 23%, whereas the reduction among Latinos could be about 37% and among blacks about 42%. Similar reductions could be achieved by covering all workers and their minor dependents. Regardless of the approach to reform, however, Latinos would remain with high absolute rates of uninsured. CONCLUSIONS: Differences in Medicaid eligibility, labor force characteristics, and family composition between Latinos and other ethnic groups suggest that policy initiatives may affect Latinos differently. Targeted strategies, such as employer mandates, "pay-or-play" programs, or Medicaid expansions, can improve coverage, but many Latinos could still remain uninsured.

Adolescent↗
PubMed1993

Characterization of glucose transport system in Drosophila Kc cells.

We have characterized the glucose transport system in the Kc cells of Drosophila melanogaster. The transporter is stereospecific and can be inhibited by both cytochalasin B and phloretin, with ki values of 4 microM and 30 microM for cytochalasin B and phloretin, respectively. Moreover, phlordzin does not affect uptake of glucose by Kc cells. Thus, on the basis of inhibitor studies, it appears that this insect cell line contains glucose transporters similar to those of the mammalian cells. However, probes prepared from rat transporter cDNAs showed no cross-hybridization with Drosophila RNA under moderately stringent conditions. Sugar selectively has also been investigated by competition assay. The km values for D-glucose, 2-deoxy-D-glucose, D-fructose and D-galactose are 2 mM, 6 mM, 17 mM and 16 mM, respectively. The results indicate that this transporter prefers D-glucose and that it does not discriminate between D-galactose and D-fructose.

Animals↗
PubMed1993

Aspartyl residue 10 is essential for ATPase activity of rat hsc70.

Three mutants of rat hsc70 were constructed, overexpressed in Escherichia coli, purified, and characterized. First, site-directed mutation was utilized to substitute Asn for Asp-10. The recombinant protein, hsc70(D10N), loses not only its peptide-stimulated ATPase activity but also its basal ATPase activity. The measured dissociation constants of ATP (0.3 microM) and S-peptide (5 microM) for hsc70(D10N), however, are virtually identical to those of hsc70. The intrinsic fluorescence spectra of hsc70(D10N) also remain largely unchanged. Therefore, the overall structure of the hsc70 protein is most likely intact after mutation. Second, the entire C-terminal peptide-binding domain was deleted and the resultant mutant contains only the N-terminal ATPase domain of hsc70. This recombinant protein, Nt-hsc70, is a peptide-independent ATPase. The ATPase activity at 37 degrees C of the Nt-hsc70, 270 pmol/h/micrograms of protein, is comparable to that of maximally peptide-activated hsc70. Third, the Asp-10 of Nt-hsc70 was replaced by Asn. Despite that this mutant, Nt-hsc70(D10N), is capable of binding ATP and it loses the capability to hydrolyze ATP. Taken together, these results indicate that aspartyl residue 10 of hsc70 is essential for ATP hydrolysis. Purified hsc70 and its mutants autophosphorylate in vitro at a substoichiometric level. On average, less than 1% of the hsc70 and Nt-hsc70 proteins are phosphorylated. Although the amount of phosphate incorporated into hsc70(D10N) and Nt-hsc70(D10) is reduced, a significant level of phosphorylation can still be achieved in these two site-directed mutants. Hence, autophosphorylation of hsc70 and its mutants is not correlated with their ability to hydrolyze ATP.

Adenosine Triphosphatases↗
PubMed1993

Cardiorespiratory effects of conventional and high frequency ventilation in rabbits with bilateral pneumothoraces and surfactant depleted lungs.

We compared high frequency ventilation (HFV) to conventional mechanical ventilation (CMV) under normoxic and normocapnic condition in surfactant depleted rabbits with bilateral pneumothoraces. We hypothesized that lower airway pressures would be required with HFV under these conditions. We applied CMV and HFV in 8 anaesthetized rabbits with a prototype ventilator at frequencies of 30, 100, 200, and 300 cycles/min. A positive end-expiratory pressure (PEEP) just below the pressure sufficient to open the air leak from the pneumothoraces was applied at all frequencies. Airway pressures, gas exchange, heart rate, and mean arterial pressure were recorded. Peak airway pressure decreased significantly from 2.50 to 2.10 kPa when the frequency of ventilation was increased from 30 to 300 cycles/min. There were no significant changes in mean airway pressure, PaO2, arterial pH, heart rate, and mean arterial pressure when HFV was compared to CMV. In conclusion, during HFV peak airway pressures measured at the mouth were decreased. Our ability to maintain adequate gas exchange in the face of ongoing pulmonary air leaks may reflect lower alveolar pressures.

Animals↗
PubMed1993

Orientational constraints as three-dimensional structural constraints from chemical shift anisotropy: the polypeptide backbone of gramicidin A in a lipid bilayer.

Chemical shifts observed from samples that are uniformly aligned with respect to the magnetic field can be used as very high-resolution structural constraints. This constraint takes the form of an orientational constraint rather than the more familiar distance constraint. The accuracy of these constraints is dependent upon the quality of the tensor characterization. Both tensor element magnitudes and tensor orientations with respect to the molecular frame need to be considered. Here these constraints have been used to evaluate models for the channel conformation of gramicidin A. Of the three models used, the one experimentally derived model of gramicidin in sodium dodecyl sulfate micelles fits the data least well.

Amino Acid Sequence↗
PubMed1993

Effect of cadmium on bone calcium and 45Ca in nonpregnant mice on a calcium-deficient diet: evidence of direct effect of cadmium on bone.

To clarify the mechanism of the effect of Cd on bone, virgin female mice with 45Ca prelabeled skeletons (15 microCi/mouse) were exposed to a Ca-deficient diet (0.002%) containing 0, 5, or 25 ppm Cd or 25 ppm Pb for 32 days. During the first 72 hr, the 0 ppm controls showed a 2.5-fold decrease in fecal 45Ca excretion (decreased bone resorption), a 12-fold decrease in total fecal stable Ca, a 5-fold decrease in endogenous fecal Ca excretion, and a significant elevation in both serum 45Ca (108%) and specific activity (92%) due to the Ca-deficient diet. In contrast, Cd immediately and significantly increased fecal 45Ca excretion (55%), total fecal stable Ca (13%), endogenous fecal Ca excretion (32%), as well as serum 45Ca (15%) and specific activity (17%) (25 ppm Cd vs 0 ppm), supporting the hypothesis of an early, direct effect of Cd on bone. Overall, during 32 days, Cd at 25 ppm induced a 60% increase in fecal 45Ca excretion compared to 0 ppm controls, providing a sensitive measure of the Cd-induced increase in bone resorption. In contrast, the effect of Cd was too small to cause a statistically significant 45Ca loss from the right femur and lumbar vertebrae, but a significant 45Ca loss (up to -13%) was seen for the remaining skeleton (25 ppm vs 0 ppm group). In addition, Cd at 25 ppm induced small but statistically significant decreases in ash weight (-12%), ash weight to dry weight (-5%), Ca/dry (-7%), and Ca/ash (-2%) in the right femur and significant decreases in ash/dry (-7%) and Ca/dry (-12%) in the lumbar vertebrae compared with the controls. Our present study supports the hypothesis that Cd at 25 ppm had a significant direct effect on bone, with no effect at 5 ppm Cd or 25 ppm Pb, and no appearance of the extreme demineralization characteristic of Itai-Itai disease, although mice were exposed to a Ca-deficient diet for 32 days. Our results from this and earlier studies support the view that chronic Cd exposure along with nutritional deficiency contributed to the pathogenesis of Itai-Itai disease among multiparous, postmenopausal women in Japan.

Animals↗
PubMed1993

The disappearance of an hsc70 species in mung bean seed during germination: purification and characterization of the protein.

We have purified a 73 kDa protein from the cytosolic fraction of mung bean seeds. It comprises 0.5-1% of the total protein in seeds. This purified protein is a bona fide hsc70 on the basis of several lines of evidence. First, antibodies against bovine brain hsc70 cross-react with the purified 73 kDa protein. Second, the purified protein comigrates on two-dimensional gels with one of the heat-inducible hsc70s in mung bean seedlings. Third, similar to other hsc70 species, the purified 73 kDa protein has a high affinity for ATP. Finally, the hydrolysis of ATP by the purified protein can be stimulated by peptides; ATPase activity increases from 40 nmol/h to 165 nmol/h per mg of protein. The purified mung bean hsc70 autophosphorylates at a substoichiometric level. Moreover, the amount of this hsc70 species diminishes while new species of hsc70s appear after germination, suggesting that the expression of hsc70 in mung bean is subject to developmental regulation.

Adenosine Triphosphatases↗