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Biomedical subjects

C Wu

Publications and source records attributed to C Wu.

At least 325 records · Page 18Linked to original sources
PubMed1998

The origin DNA-binding and single-stranded DNA-binding domains of simian virus 40 large T antigen are distinct.

Little is known about the ability of simian virus 40 (SV40) T antigen to bind single-stranded DNA. We demonstrate here that a mutant (259-708) missing the first 258 amino acids of T antigen and its origin-binding domain bound single-stranded DNA at close to normal levels, whereas a mutant containing only the first 259 amino acids failed to bind any single-stranded DNA. The 259-708 mutant also assembled into high-molecular-weight oligomers in the presence of single-stranded DNA. Its ATPase activity was stimulated by single-stranded DNA similarly to the wild type (WT). Furthermore, WT T antigen's ability to bind to single-stranded DNA was inhibited by the binding of two monoclonal antibodies that recognize a region after residue 362. These results show that the domain responsible for binding to single-stranded DNA is completely separate from the origin-binding domain.

Adenosine Triphosphatases↗
PubMed1998

Development and characterization of monoclonal antibodies specific to the serotonin 5-HT2A receptor.

Serotonin (5-hydroxytryptamine, 5-HT) mediates many functions of the central and peripheral nervous systems by its interaction with specific neuronal and glial receptors. Fourteen serotonin receptors belonging to seven families have been identified through physiological, pharmacological, and molecular cloning studies. Monoclonal antibodies (MAbs) specific for each of these receptor subtypes are needed to characterize their expression, distribution, and function in embryonic, adult, and pathological tissues. In this article we report the development and characterization of MAbs specific to the serotonin 5-HT2A receptor. To generate MAbs against 5-HT2AR, mice were immunized with the N-terminal domain of the receptor. The antigens were produced as glutathionine S-transferase (GST) fusion proteins in insect cells using a Baculovirus expression system. The hybridomas were initially screened by ELISA against the GST-5-HT2AR recombinant proteins and subsequently against GST control proteins to eliminate clones with unwanted reactivity. They were further tested by Western blotting against recombinant GST-5-HT2AR, rat and human brain lysate, and lysate from cell lines transfected with 5-HT2AR cDNA. One of the MAbs G186-1117, which recognizes a portion of the 5-HT2AR N-terminus, was selected for further characterization. G186-1117 reacted with a band of molecular size 55 kD corresponding to the predicted size of 5-HT2AR in lysates from rat brain and a 5-HT2AR-transfected cell line. Its specificity was further confirmed by adsorption of immunoreactivity with recombinant 5-HT2AR but not with recombinant 5-HT2BR and 5-HT2CR. Rat brain sections and Schwann cell cultures were immunohistochemically labeled with this MAb. G186-1117 showed differential staining in various regions of the rat brain, varying from regions with no staining to regions of intense reactivity. In particular, staining of cell bodies and dendrites of the pyramidal neurons in the cortex was observed, which is in agreement with observations of electrophysiological studies.

Aged↗
PubMed1998

Effects of object affordances on reaching performance in persons with and without cerebrovascular accident.

OBJECTIVE: This study investigated whether affording objects with different levels of functional support would have an impact on reaching performance in patients after cerebrovascular accident (CVA) and in adults who were neurologically intact. Reaching performance was quantitatively analyzed, using several kinematic variables. METHOD: Two groups, 14 participants after CVA and 24 age-matched adults who were neurologically intact, performed a food chopping task under two conditions: enriched affordances and impoverished affordances. Enriched affordances involved reaching forward to a chopper and pushing down on the handle to chop a fresh mushroom. Impoverished affordances involved reaching forward to a simulated chopper (i.e., a chopper covered with cardboard) without anything in it and then pushing the handle down. Reaching movement was measured by a three-dimensional motion analysis system. RESULTS: For the CVA group, the enriched condition of reaching to chop the mushroom resulted in more efficient, direct, smooth, and preplanned movement than the impoverished condition of reaching to push on the chopper handle. The neurologically intact group responded similarly except that the participants' movement was equally smooth, as measured by movement unit, between the two testing conditions. Force generation, as characterized by peak velocity, was similar for both conditions for both groups. CONCLUSION: The finding that enriched affordances had a positive effect on movement kinematics in both CVA and neurologically intact groups suggests that providing natural objects for completing a task and providing functional information on the objects may enhance the functional performance of persons who have had a CVA. These findings should be replicated and extended to confirm the validity of these effects and allow for generalization.

Adult↗
PubMed1998

[A canonical correlation analysis on the traffic conditions and the road injury in China in 1996].

In order to expound the impact of traffic condition to road injury, the relations of road injury with motorization, road situation e and highway capacity were studied, using Canonical Correlation analysis method. Results showed that the Canonical Correlation Coefficient A(0.9486) was representing the direct correlation of the motorization with the injury and death rates, referring the higher the motorization, the greater the death and injury rates. The Canonical Correlation Coefficient B(0.9220) indicated the direct correlation between the highway capacity and the frequency of road injury, as well as the larger the highway capacity, the more frequency of road injury occurrance. The Canonical Correlation Coefficient C(0.6446) revealed the relations between levels of road situation and the accident rates per 10,000 vehicles. Results showed that the higher the quality of roadway, the lower was the accident rate. In view of this, traffic condition was closely related to road injury. Thus, the frequency of accident, death rate and injury rate could be reduced through improving the road quality and traffic conditions. Relations between two sets of random variables, the ties of the canonical variables and the original variables could all be well analysed with Canonical Correlation analysis. Canonical Correlation is useful to analyse two sets of random variables in epidemiological studies since it provides a great amount of information to be applied and operated widely and easily.

Accidents, Traffic↗
PubMed1998

[Identification and determination of Shenbaiye].

This study was amied at the method of identifying and determining Shenbaiye so that a ground can be provided for the quality requirements. Three Chinese materia medica (Radix Sophorae flavescentis, I; Cortex Phellodendri, II; Rhizoma Atractylodis, III) of Shenbaiye were identified by means of TLC successfully. The method in detail and the chromatogram were presented. The determination of I in Shenbiaye was carried out by solid phase cleaned-up and separated through neutral alumine column (10 x 1 cm i.d.) eluting with chloroform. This eluent was extracted with sulphuric acid (0.01 mol/L) and the excess of acids was titrated with sodium hydroxide (0.02 mol/L) using the methyl red as an indicator. The total alkaloid content of I was calculated as matrine of I in Shenbaiye. This method was established with a precision of 1.10% (n = 5) and the recoveries of 97.59 +/- 1.28% (n = 8). The results of determination of samples were reported.

Alkaloids↗
PubMed1998

[Cloning and sequencing of E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus].

OBJECTIVE: To clone E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus into mammalian expression vector and analyze its primary nucleotide structure. METHODS: Reverse transcription nested-PCR methods were employed for amplification E2/NS1 gene which was cloned into mammalian expression vector pcDNA3 by directed clone. Sequence of inserted gene was analyzed by Sanger's method. RESULTS: E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus was cloned into eukaroytic expression vector effectively. Sequence of E2/NS1 showed 88.37% identity in nucleotide and 89.29% in putative amino acid to that of a Japanese genotype III isolate of hepatitis C virus. Nevertheless it showed 70.69% and 75.55% identity to that of a Chinese genotype II isolate of hepatitis C virus. CONCLUSION: E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus was successfully cloned into mammalian expression vector by technique of DNA recombination. Sequence analysis showed that E2/NS1 gene has good homology intra-genotype and poor homology intergenotype of hepatitis C virus. Research of primary nucleotide structure of different genotype hepatitis C virus might be helpful for the development of vaccine against the virus.

Amino Acid Sequence↗
PubMed1998

Comparison between homologies of E2/NS1 gene from genotype III Chinese isolates of hepatitis C virus and that from reported isolates.

OBJECTIVES: To sequence E2/NS1 gene from genotype III Chinese isolates of hepatitis C virus (HCV) and analyze homology corresponding to the region of the reported isolates. METHODS: E2/NS1 gene derived from genotype III Chinese isolates of HCV was amplified by reverse transcripase-polymerase chain reaction (RT-PCR) and cloned into vector pcDNA3. Dideoxy chain termination methods were used to sequence E2/NS1 gene. RESULTS: E2/NS1 gene derived from genotype III Chinese isolates of HCV was cloned for the first time and named HC-W14. Identity of HC-W14 in nucleotide and putative amino acid to those of genotype III Japanese isolates of HCV were 88.37% and 89.29% respectively. Homology to that of non-type III isolates was relatively low. CONCLUSIONS: High variation existed in E2/NS1 region between genotype III and II Chinese isolates of hepatitis C virus. The variability of E2/NS1 gene should be taken into account in the development of vaccine against HCV in China.

Amino Acid Sequence↗
PubMed1998

Effects of beta-amyloid peptide on transient outward potassium current of acutely dissociated hippocampal neurons in CA1 sector in rats.

OBJECTIVE: To explore the mechanism of beta-amyloid peptide (beta-AP) in Alzheimer's disease at ionic channel level. METHODS: Hippocampal CA1 neurons of 7-21 days' rats were acutely dissociated and the effects of beta-AP on transient outward potassium current were observed by a whole-cell recording patch clamp technique. RESULTS: beta-AP can significantly block transient potassium current in dose-dependent, time-dependent and partly voltage-dependent manners. CONCLUSION: beta-AP may decrease the membrane conductance of K+ channels in hippocampal neurons, playing an important role in the pathophysiological mechanism of Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed1998

[The distribution of substance P in the lungs of asthmatic guinea-pigs and the influence of dexamethasone on the distribution].

OBJECTIVE: To investigate the distribution of substance P(SP) in the lungs of asthmatic guinea pigs and the effects of dexamethasone on its distribution. METHODS: Guinea pigs were divided into 3 groups: asthma group, dexamethasone-treated group and control group. Rabbit serum against SP, immunohistochemical ABC method and glucose-DAB-nickel technique for staining and computer image analysis were used in this study. RESULTS: There was distribution of SP-IR positive fibres in airways in asthma group than the other two groups. The positive fibres, emerged like a string of beads, were present as large fibre bundles in the smooth muscle layer and basement membrane. Additionally, in the asthma group SP-IR positive fibres were detected on the walls of respiratory bronchioles and alveolar ducts in contrast to the other groups. There was no difference in distribution and morphological characteristic between the control group and the dexamethasone-treated group. CONCLUSION: Repeated antigen challenges, which cause the allergic inflammation of airways, may result in the growth of SP-containing nerve fibres in the airway and synthesis of SP in neurons. These may be involved in the persistence and exacerbation of airway inflammation in asthma. Dexamethasone can reverse the distribution of SP-IR positive fibres to the normal status in airway walls of asthma guinea pigs.

Animals↗
PubMed1998

[Experimental study on inhibitory effect of ganlu xiaodu Dan on coxackie virus in vitro].

OBJECTIVE: To observe the Coxackie virus inhibitory effect of Ganlu Xiaodu Dan (GLXDD), including complete recipe, incomplete recipe and supplemented recipe of it. METHODS: Using tissue culture technique, the maximal non-toxic concentration of drug on cultured cells, the influence of drug on proliferation of virus in cultured cells and the virus inhibitory effect in different time of action were observed. RESULTS: The maximal non-toxic concentration of GLXDD was 1:40 (25 g/L), no matter whether the recipe was complete, incomplete or supplementary. CLXDD in that concentration could inhibit significantly the proliferation of Coxackie virus B2, B3 and B4 strains, the inhibition index being over 2 and the output of these strains treated with complete recipe of GLXDD was lower significantly than that of the control group (P < 0.05). CONCLUSION: GLXDD, including its complete recipe, incomplete recipe and supplementary recipe, could inhibit the replication of Coxackie virus in cultured cells.

Antiviral Agents↗
PubMed1998

[An experimental study on curative effect of Chinese medicine qing yi tang in acute necrotizing pancreatitis].

OBJECTIVE: To observe the curative effect of the traditional Chinese medicine (TCM) Qing Yi Tang (QYT) in acute necrotizing pancreatitis (ANP). METHODS: Twenty three dogs were randomly divided into 3 groups. In control group (n = 7), animals underwent laparotomy only. In ANP group (n = 8), acute necrotizing pancreatitis was induced by injection of 0.5 ml/kg 5% sodium taurocholate with 300 u/kg trypsin into the pancreatic duct. While in TCM group (n = 8) were fed everyday with QYT after onset of ANP. All animals were sacrified 7 days later and organs were gathered and cultured. Mucosal and luminal floras of the intestine were analysed. Pancreas and ileal mucosa were examined histologically and ultra-microscopically, the levels of lipopolysaccharide (LPS) and amylase in blood were determined. RESULTS: In TCM groups, histologic and ultra-structural damages in pancreas and ileal mucosa were much milder as compared with those of ANP group. In ANP group, there was a significant increase of E. coli and bacterocoids, and a significant decrease of bifidobacteria, lactobacilli and enterococci in the intestinal mucosa, while in TCM groups, these changes were alleviated significantly (P < 0.05 or P < 0.01). As compared with ANP group, the bacterial translocation (BT) rate was reduced from 100% to 50%, and the counts of translocated bacteria were decreased 10-40 times, the levels of LPS and amylase reduced 2 to 3 times. CONCLUSION: TCM recipe QYT showed their protective effects on gut barrier function by alleviating the damage of intestinal mucosa and microecologic disturbance following acute pancreatitis. As a result, the chances of BT and enterogenic infection declined. These preparation might be promising in the prophylaxis and treatment of infection complicating ANP.

Animals↗
PubMed1998

[The pathogenesis of infection complicated by acute necrotizing pancreatitis: an experimental study].

OBJECTIVE: To observe the injury of gut barrier function and intestinal bacterial translocation following acute necrotizing pancreatitis (ANP), and to investigate the pathogenesis of infection complicated by ANP. METHOD: Fifteen dogs were colonized with a strain of E. coli JM109 bearing ampicillin-resistant plasmid PUC18, then divided into two groups: control group (n = 7) and ANP group (n = 8). Acute necrotizing pancreatitis was induced by injection of sodium taurocholate and trypsin into the pancreatic duct. RESULT: In the ANP group, as compared with the control group, serum amylase level increased significantly, the lactulose/mannitol ratio was 2-12 times higher, blood and ileum diamine oxidase activity decreased significantly. E. coli population in intestinal mucosal flora increased, while bifidobacterium and lactobacillus reduced significantly. Bifidobacterium/E. coli ratio was reversed. Morphological study revealed areas of hemorrhage and necrosis in the pancreas and shedding of ileal villi. In the control group, blood cultures were negative, and no organism was found in organs except for mesenteric lymph nodes in two dogs. In the ANP group, blood and organ cultures were positive in all dogs and JM109 could be found uniformly too. CONCLUSION: ANP impaired the gut barrier function, which led to bacterial translocation from the gut to the pancreas and other organs, serving as a primary source of infection secondary to ANP.

Animals↗
PubMed1998

[Morphometrical study on inhibitory effect of vitamin B6 and banana-stem extract on calcium crystallization].

OBJECTIVE: To search for the anticrystallization mechanism by vitamin B(6) and banana stem extract. METHOD: Thirty-six male China-1 mice were divided into 4 groups: normal, crystallization, vitamin B(6) and banana-stem extract groups. Calcium oxalate crystallization was induced by 1% glycol and 1% ammonium chloride in the last 3 groups. Vitamin B(6) was then given to the 3rd group and banana stem extract to the 4th group for 3 weeks. At the end of 3 weeks, all the mice were sacrificed and the kidneys were taken for morphometrical studies using image analysis system and assayed for calcium oxalate. RESULT: Morphometrical area density and numerical density of crystallization was significantly less in the vitamin B(6) group and the banana-stem extract group as compared with the crystallization group, being the least in the banana-stem extract group. Oxalate in renal tissue was also significantly reduced. Both vitamin B(6) and banana stem extract had no effect on renal tissue calcium. CONCLUSION: Vitamin B(6) and banana-stem extract may be useful agents in the treatment of patients with hyperocaluric urolithiasis.

Animals↗
PubMed1998

[Application of dot immunogold filtration assay for diagnosis of Schistosomiasis japonica].

AIM: To quest for a simple and convenient assay for the diagnosis of schistosomiasis. METHODS: Three monoclonal antibodies against different epitopes of antigens of S. japonicum were used to develop a dot immunogold filtration assay for detection of schistosomal antigen-antibody reaction on the membrane during the filtration process. The results could be read with the naked eye within a few minutes. RESULTS: The sensitivity of the SEA assay was 16 ng/ml. In 69 serum samples from patients with chronic schistosomiasis, the positive rate and specificity of this assay were 60.8% and 95.2%, respectively. Dot-ELISA was used in detecting 137 serum samples from patients with chronic schistosomiasis, the positive rate and specificity were 54.7% and 94.6%, respectively. When sandwich-ELISA was used in detecting 118 serum samples from patients with chronic schistosomiasis, the positive rate and specificity were 61.9% and 95.7%, respectively. CONCLUSION: The sensitivity and specificity of DIFA were similar to those of ELISA, but DIFA required less time and no special equipment.

Enzyme-Linked Immunosorbent Assay↗
PubMed1998

Cytotoxic strains of Pseudomonas aeruginosa can damage the intact corneal surface in vitro.

PURPOSE: Although the corneal epithelial cell layer is believed to serve as a barrier against most types of bacteria, certain strains of P. aeruginosa have been shown to kill corneal epithelial cells in primary cultures. The aim of this study was to test whether these strains could damage epithelia on uninjured whole corneas. METHODS: Five-week-old Sprague-Dawley rats were sacrificed and their eyes were placed in organ culture. The corneal surface of each eye was incubated with 8 microL of media alone or a bacterial suspension containing 8 x 10(6) cfu of one of 12 cytotoxic and noncytotoxic strains of P. aeruginosa for 3 hours at 35 degrees C. Trypan blue was then added to visualize surface epithelial cell injury. A masked observer examined each cornea under a dissecting microscope and assigned a score of between 1 and 3 to describe the extent of injury. RESULTS: Cytotoxic P. aeruginosa injured the surface epithelium. The extent of injury induced by the various strains correlated with previously published in vitro measures of cytotoxic capacity toward cultured corneal epithelial cells. Cytotoxicity required at least 2 hours of bacterial contact and was dependent upon ExsA, a transcriptional activator of several genes in P. aeruginosa, including the gene encoding exoenzyme S. CONCLUSIONS: Cytotoxic P. aeruginosa strains can damage epithelia on an uninjured corneal surface providing there is prolonged bacterial contact. Stagnation of cytotoxic bacteria against the corneal surface may contribute to the pathogenesis of infection associated with the use of soft contact lenses.

Animals↗
PubMed1998

Evaluation of the in vivo biodistribution of yttrium-labeled isomers of CHX-DTPA-conjugated monoclonal antibodies.

UNLABELLED: We evaluated the in vivo stability and biodistribution of four isomers (CHX-A', CHA-A", CHX-B' and CHX-B") of 2-(p-isothiocyanatobenzyl)-cyclohexyl-diethylenetriaminepentaaceti c acid (CHX-DTPA), a recently developed backbone-substituted derivative of DTPA. METHODS: The ligands were conjugated to monoclonal antibody B3, a murine IgG1 kappa, and labeled with 88Y at 55.5-66.6 MBq/mg (1.5-1.8 mCi/mg). Nontumor-bearing nude mice were injected intravenously with 55.5-66.6 kBq (1.5-1.8 microCi) of 88Y-labeled B3 conjugates and with 125I-labeled B3 as an internal control. The mice were then killed at 6, 24, 48, 96 and 168 hr postinjection. RESULTS: At 168 hr, the concentration of 88Y in processed bone of either CHX-A' [4.6% injected dose (ID)/g] or CHX-A" (4.0%ID/g) was less than that of either the CHX-B' (21.9%ID/g) or B" (12.1%ID/g) ligands. The two ligands CHX-B" and CHX-B' were not acceptable for yttrium labeling of antibody because of their high and progressive bone accumulation. The accumulation of 88Y in bone of CHX-B' was five times greater than that of CHX-A' at 168 hr. The CHX-A" cleared from the circulation slightly faster than CHX-A' without releasing the yttrium and showed the lowest uptake by bone of any of the four isomers. The accumulation in the other normal organs was similar for all four isomers of 88Y-CHX-B3 conjugates. CONCLUSION: Although the CHX-B" and CHX-B' were not acceptable for labeling with yttrium, the CHX-A' and CHX-A" were suitable, indicating that differences in stereochemistry can greatly influence stability of radionuclide in the chelate.

Animals↗
PubMed1997

The phosphorylation site for Ste20p-like protein kinases is essential for the function of myosin-I in yeast.

The budding yeast Saccharomyces cerevisiae has two functionally redundant myosin-I isoforms encoded by the MYO3 and MYO5 genes. The function shared by these myosin proteins is required for proper yeast budding. Serine residue 357 in the head domain of Myo3p, conserved among myosin-I proteins including yeast Myo5p, was identified as a unique phosphorylation site for the serine/threonine protein kinase Ste20p and its closely related isoform Cla4p. These protein kinases share a function that is also essential for budding. Replacement of serine 357 with alanine disrupted the in vivo function of Myo3p, whereas this function was maintained by changing the serine residue to aspartate. This mutant version failed to compensate the growth defect of cells which lack both Ste20p and Cla4p, suggesting that myosin-I is not the only essential target of these protein kinases. Our results suggest that phosphorylation of the head domain by Ste20p-like protein kinases plays an essential role in the function of myosin-I in yeast cells.

Acanthamoeba↗