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Biomedical subjects

C Wang

Publications and source records attributed to C Wang.

At least 577 records · Page 32Linked to original sources
PubMed1999

[Analysis of the vestiges of farm chemicals for Panax notoginseng].

The vestiges of farm chemicals in Panax notoginseng plants and medicinal materials from main production areas in Wenshan District was analyzed in this study. The result showed that the samples from the places contained hexachloro-cyclohexane and DDT. And the vestiges of hexachloro-cyclohexane was about 0.016-0.101 mg/kg, that of DDT was about 0.15-0.143 mg/kg. The content of Cu, Zn, Pb, Cd was lower than national standard of P. R. C.

China↗
PubMed1999

[Molecular epidemiology of respiratory syncytial virus infection in infants].

OBJECTIVE: To search for the molecular epidemiology of respiratory syncytial virus (RSV) infection in infants. METHODS: The randomly amplified polymorphism DNA (RAPD) technology was used to study 96 RSV strains isolated and identified from the patients in Changchun State Hospital of Pediatrics during 1992-1994 and 1 reference strain of M type. RESULTS: All strains were typable, four RAPD patterns were observed, different diseases have different types. 87.14% of the patients' RSV strains had the same RAPD pattern(R1). CONCLUSION: RAPD method is a rapid, easy and high resolution technique, with which we can know on the molecular level the microbial infection state. There was epidemic of R1 type infection during the period surveyed.

Bronchiolitis, Viral↗
PubMed1999

[Changes in nasal airway resistance before and after endoscopic sinus surgery].

OBJECTIVE: To study the influence of endoscopic sinus surgery(ESS) on nasal airway resistance (NAR) and to analyze the relationship between NAR and nasal airflow sensation. METHODS: The NAR and nasal airflow sensation were measured with anterior rhinomanometry and visual analogous scale test (VAS) in 42 patients (50 sides) before and after the ESS. RESULTS: NAR decreased significantly after the operation. The change rates in NAR before and after the decongestion were (55.71 +/- 13.90)% and (24.32 +/- 8.73)%, respectively, and there was a significant difference (P < 0.05). The pathological increase in NAR correlated well with subjective sensation of the patients (P < 0.05). CONCLUSION: The improvement of nasal functions by ESS is not due to the alteration of the anatomic structure of the nasal cavity, but to the amelioration of mucosal edema. The rhinomanometry can be used as a useful clinical tool in determining nasal patency.

Adolescent↗
PubMed1999

[Microbeam nuclear reaction analysis and its application to individual fluid inclusions].

The principles and analytical technique of nuclear analysis of scanning microprobe (micro-NRA) was introduced. It is a useful tool for nondestructive light elements analysis which can not be detected by micro-PIXE. Using 19F (p, alphagamma)16O reaction at 872 keV resonance energy, the fluorine concentration in trapped fluid inclusions of mantle derived olived-evidence from Cenozoic basaltic rocks in Eastern-China was determined.

English Abstract↗
PubMed1999

[Study on the determination of iodine by ICP-AES].

A method for the determination of iodine in iodo-calcium pieces by ICP-AES was studied. I- was turned to I2 by HClO4 and H2O2. The detection limit of iodine is 1 ng/mL. The sample was dissolved with water and was directly determined without seperating the precipitate in the bottom of volume flask. It was found that the precipitate attracted with I2 and the quantity of attracting would increase with delay time.

Dietary Supplements↗
PubMed1999

[Assay of diclofenac sodium and codeine phosphate in tablet by multiwavelength K-factor spectrophotometry].

Assay of diclofenac sodium and codeine phosphate in tablet is reported in this paper. The calibration curves were linear over the range of 11.18-25.40 microg/mL of diclofenac sodium and over the range of 6.785-15.42 microg/mL of codeine phosphate. The average recoveries and relative standard deviations of diclofenac sodium and codeine phosphate were 100.1%, 0.36% and 100.7%, 0.80%, respectively. The method is simple and rapid, and the results are satisfactory.

Codeine↗
PubMed1999

[Determination of the content of aminopyrine in antongding injection by orthogonal function spectrophotometry].

Determination of the content of aminopyrine in the antongding injection by orthogonal function spectrophotometry was reported in this paper. The six wavelengths for the determination are 257, 261, 265, 269, 273 and 277 nm. The concentration of aminopyrine in the range of 5-25 microg x mL(-1) is in a good linear relation to P2, and the regression equation is P2 = + 0.018 - 0.032 9c, r = 0.999 9. The average recovery and relative standard deviation are 100.3% and 0.40%, respectively. On the basis of the data observed it is concluded that this method shows no obvious difference as compared with Hebei province pharmacy regulation.

Aminopyrine↗
PubMed1998

Point mutation in the MITF gene causing Waardenburg syndrome type II in a three-generation Indian family.

Waardenburg syndrome (WS) is an autosomal-dominant neural crest cell disorder phenotypically characterized by hearing impairment and disturbance of pigmentation. A presence of dystopia canthorum is indicative of WS type 1, caused by loss of function mutation in the PAX3 gene. In contrast, type 2 WS (WS2) is characterized by normally placed medial canthi and is genetically heterogeneous; mutations in MITF (microphthalmia associated transcription factor) associated with WS2 have been identified in some but not all affected families. Here, we report on a three-generation Indian family with a point mutation in the MITF gene causing WS2. This mutation, initially reported in a Northern European family, creates a stop codon in exon 7 and is predicted to result in a truncated protein lacking the HLH-Zip or Zip structure necessary for normal interaction with its target DNA motif. Comparison of the phenotype between the two families demonstrates a significant difference in pigmentary disturbance of the eye. This family, with the first documented case of two unrelated WS2 families harboring identical mutations, provides additional evidence for the importance of genetic background on the clinical phenotype.

Base Sequence↗
PubMed1998

A convenient method of aligning large DNA molecules on bare mica surfaces for atomic force microscopy.

Large DNA molecules remain difficult to be imaged by atomic force microscopy (AFM) because of the tendency of aggregation. A method is described to align long DNA fibers in a single direction on unmodified mica to facilitate AFM studies. The clear background, minimal overstretching, high reproducibility and convenience of this aligning procedure make it useful for physical mapping of genome regions and the studies of DNA-protein complexes.

Aluminum Silicates↗
PubMed1998

Substrate binding induces depolymerization of the C-terminal peptide binding domain of murine GRP78/BiP.

To investigate the role of each domain in BiP/GRP78 function, we have used a full-length recombinant BiP engineered to contain two enterokinase sites; one site is located after an N-terminal FLAG epitope, and a second site has been inserted at the junction between the N- and C-terminal domains (FLAG-BiP.ent). FLAG-BiP.ent oligomerizes into multiple species that interconvert with each other in a slow, concentration- and temperature-dependent equilibrium. Binding of ATP or AMP-PNP (adenosine 5'-(beta, gamma-imino)triphosphate), but not ADP, or of a peptidic substrate induces depolymerization of FLAG-BiP.ent and stabilization of monomeric species. Enterokinase cleavage of monomeric, nucleotide-free BiP.ent results in the physical dissociation of the 44-kDa N-terminal ATPase fragment (N44.ent) from the 30-kDa C-terminal substrate binding domain (C30.ent). Upon dissociation, the freed C-terminal substrate binding domain readily undergoes self-association while N44.ent remains monomeric. Enterokinase cleavage performed in the presence of a synthetic peptide prevents oligomerization of the freed C30.ent domain. Addition of ATP during enterokinase cleavage has no effect on C30.ent oligomerization. Our data clearly indicate that binding of a specific peptide onto the C-terminal domain, or ATP onto the N-terminal domain, induces internal conformational change(s) within the C30 domain that result(s) in BiP depolymerization.

Adenosine Triphosphate↗
PubMed1998

Thermodynamic analysis of the binding of the polyglutamate chain of 5-formyltetrahydropteroylpolyglutamates to serine hydroxymethyltransferase.

The thermodynamic parameters for the binding of 5-formyltetrahydrofolate (5-CHO-H4PteGlun) and its polyglutamate forms to rabbit liver cytosolic serine hydroxymethyltransferase (SHMT) were determined by a combination of isothermal titration calorimetry and spectrophotometry. Binding of 5-CHO-H4PteGlun to SHMT exhibits both positive enthalpy and entropy, showing that binding is entropically driven. 5-CHO-H4PteGlu5 has a 300-fold increased affinity for SHMT compared to 5-CHO-H4PteGlu. This increase in affinity is due primarily to a decrease in the positive enthalpy with little change in entropy. A variety of anions inhibit the binding of 5-CHO-H4PteGlu5 with Ki values in the 10-20 mM range. Anions are ineffective inhibitors of 5-CHO-H4PteGlu binding to SHMT, showing that anions compete for the polyglutamate binding site. There was little difference in the Ki values for a series of dicarboxylic acids as inhibitors of 5-CHO-H4PteGlu5, suggesting that spacing of the negative charges may not be important in determining their effectiveness as inhibitors. Both the mono- and pentaglutamate derivatives of 5-CHO-H4PteGlun were cross-linked to SHMT by a carbodiimide reaction to Lys-450 which resides in a stretch of Lys, His, and Arg residues.

Amino Acid Sequence↗
PubMed1998

A second magnesium ion is critical for ATP binding in the kinase domain of the oncoprotein v-Fps.

The activity of the kinase domain of the oncoprotein v-Fps was found to be sensitive to the concentration of magnesium ions. Plots of initial velocity versus free magnesium concentration are hyperbolic and do not extrapolate to the origin at stoichiometric ATP-Mg, indicating that there are two sites for metal chelation on the enzyme and the second is nonessential for catalysis. The second metal is strongly activating and increases the reaction rate constant almost 20-fold from 0.5 to 8.3 s-1 using 0.2 mM ATP-Mg and 1 mM peptide, EAEIYEAIE. This increase in rate is due to a large increase in the apparent affinity of ATP-Mg at high magnesium concentrations. At 0.5 and 10 mM free Mg2+, KATP-Mg is 3.6 and 0.22 mM, respectively. Extrapolation of the observed affinity of ATP-Mg to zero and infinite free metal indicates that KATP-Mg is greater than 8 mM in the absence of the second metal and 0.1 mM in the presence of the second metal, a minimum 80-fold enhancement. By comparison, free levels of the divalent ion do not influence maximum turnover (kcat) and have only a 2-fold effect on the Km for the peptide substrate between 0.5 and 20 mM free Mg2+. Viscosometric studies indicate that free Mg2+ does not influence the rates of phosphoryl transfer or net product release above 0.5 mM but does affect directly the dissociation constant for ATP-Mg. The Kd for ATP-Mg in the absence and presence of the second metal ion is >32 and 0.4 mM, respectively. At high magnesium concentrations, ATP-Mg and the peptide substrate bind independently, while at lower concentrations (0.5 mM), there is significant negative binding synergism suggesting that the second metal may help to reduce charge repulsion between ATP-Mg and the peptide. The data indicate that the first metal is sufficient for phosphoryl transfer. While the second metal could have some influence on phosphoryl transfer or product binding, it is a potent activator that functions minimally by controlling ATP-Mg binding.

Adenosine Triphosphate↗
PubMed1998

The C-truncated delta-opioid receptor underwent agonist-dependent activation and desensitization.

The agonist-dependent activation and desensitization of a recombinant analog of delta-opioid receptor lacking the carboxyl-terminal (C-terminal) 31 residue peptide segment were discussed. The cDNA of the C-truncated delta-opioid receptor was created by polymerase chain reaction (PCR), stably expressed in Chinese hamster ovary cells and characterized by binding assay and function assay. Agonist [D-Pen2, D-Pen5]-enkephalin (DPDPE) stimulated the specific [35S]GTPgammaS binding to membrane fragments of cells expressing the C-truncated and the wild-type delta-opioid receptors in different levels dose-dependently. EC50 values of DPDPE on truncated and wild-types in stimulation were very similar. Agonist-dependent desensitization, which could be blocked by protein kinase inhibitor staurosporine (Stau), was observed after pretreating truncated receptors with 1 microM DPDPE for 10 min, the same as wild-types. The results reveal that the C-terminal of the delta-opioid receptor is not involved in controlling the G-protein activation and phosphorylation-related functional desensitization.

Animals↗
PubMed1998

Neutralizing antibodies administered before, but not after, virulent SHIV prevent infection in macaques.

By subcutaneous inoculation of SHIV(KU-2) in the hands of macaques, we developed a model of human immunodeficiency virus type-1 (HIV-1) occupational infection due to needle-stick injury and used the model to determine whether neutralizing serum to SHIV administered before or after virus inoculation could either prevent or abort infection, respectively. Six rhesus macaques were given 15 ml/kg pooled anti-SHIV plasma and challenged 24 hr later with approximately 300 animal infectious doses of SHIV(KU-2), subcutaneously. Three of the six macaques completely resisted infection with SHIV(KU-2). A fourth animal failed to yield infectious virus, but DNA extracted from its peripheral blood mononuclear cells (PBMC) and lymph nodes had viral sequences. Partial resistance was noted in the other two animals because virus recovery was delayed compared with the control animals. In contrast, six of six macaques given the same dose of anti-SHIV plasma 18 hr after exposure to virus became infected, as did two of two macaques given anti-SHIV plasma only 2 hr after exposure to virus. Our results suggest that neutralizing antibodies may have a prophylactic but not a therapeutic role in HIV-1 infections.

Animals↗
PubMed1998

Failure of SIVmac to be neutralized in macrophage cultures is unique to SIVmac and not observed with neutralization of SHIV or HIV-1.

Except during acutely lethal infection, macaques infected with SIVmac251 produce antibodies that neutralize the virus in CEMx174 cells, macaque PBMC and macrophage cultures. In a previous report, we had shown that whereas neutralization of the SIVmac251 was complete in lymphocyte cultures, "protected" macrophages had actually become latently infected, and remained viral DNA-positive, but the infection was nonproductive as long as antibodies were maintained in the medium. Removal of the antibodies as long as 1 week later, resulted in resurgence of virus replication. In the present study, we compared neutralization of SIVmac239 with that of neutralization of SHIV and HIV-1, and sought to determine whether the failure to prevent infection in macrophages was also typical of neutralization of SHIV and HIV-1 in macaque and human macrophage cultures, respectively. The results showed that similar to SIVmac251, neutralizing antibodies did not block SIVmac239 infection in macaque macrophages, although they blocked infection of the virus in T cells. The data from neutralization of SHIV using anti-SHIV antibodies and for neutralization of HIV-1 (89.6 and Bal) using anti-HIV IgG in both T cells and macrophages, however, can be summarized with a single statement: neutralization of SHIV and HIV-1 was complete in all of the cultures, with no evidence of establishment of latent infection in or resurgence of virus replication after antibodies were removed from macrophage cultures. The non-neutralizability of SIVmac (251 and 239) in macrophages is therefore unique to the SIVmac and not relevant to neutralization of HIV-1.

Animals↗
PubMed1998

Retinoblastoma, a tumor suppressor, is a coactivator for the androgen receptor in human prostate cancer DU145 cells.

The retinoblastoma protein may function as a tumor suppressor by controlling the progression of the normal cell cycle. Inactivation of Rb has been regarded as an important event in prostate carcinogenesis. However, the detailed mechanism of how Rb is linked to androgen-androgen receptor (A-AR), the major factor in promotion of prostate tumor growth, remains unclear. Using GST-Rb pull down assay and mammalian two-hybrid system, we report here that Rb can bind specifically to AR in an androgen-independent manner. Transient transfection assay demonstrates that cotransfection of AR and Rb can further induce AR transcriptional activity 4-fold in the presence of 1 nM dihydrotestosterone in DU145 cells. Interestingly, cotransfection of Rb and ARA70, the first identified AR coactivator, with AR can additively induce AR transcriptional activity 13-fold (from 5-fold to 64-fold). In conclusion, our discovery that Rb can function as a coactivator to induce AR transcriptional activity in prostate cells may represent the first data to link a negative growth regulatory protein function in a positive manner, by inducing the transcriptional activity of AR.

Cell Cycle↗
PubMed1998

The observation of the local ordering characteristics of spermidine-condensed DNA: atomic force microscopy and polarizing microscopy studies.

Condensation of DNA by multivalent cations can provide useful insights into the physical factors governing the folding and packaging of DNA in vivo. In this work, local ordered structures of spermidine-DNA complexes prepared from different DNA concentrations have been examined by using atomic force microscopy (AFM) and polarizing microscopy (PM). Two types (I and II) of DNA condensates, significantly different in sizes, were observed. It was found that for extremely dilute solutions (DNA concentrations around 1 ng/microl or below), the DNA molecules would collapse into toroidal structures with a volume equivalent to a single lambda-DNA (type I). In relatively dilute solutions (DNA concentrations between 1 and 10 ng/microll), a significantly larger structure of multimolecular toroids (circular and elliptical, type II) were formed, which were constructed by many fine particles. Measurements show that the average diameter of these fine particles was similar to the outer diameter of the monomolecular toroids observed in extremely dilute solutions, and the thickness of the multimolecular toroids had a distribution of multi-layers with height increments of 11 nm, indicating that the multimolecular toroidal structures have lamellar characteristics. Moreover, by enriching the DNA-spermidine complexes in very diluted solution, branch-like structures constructed by subunits were observed by using AFM. The analysis of the pellets in polarizing microscopy reveals a liquid-crystal-like pattern. These observations suggest that DNA-spermidine condensation could have multiple stages, which are very sensitive to the DNA and spermidine concentrations.

Bacteriophage lambda↗