Search PubMed⌕ Search

Biomedical subjects

C Wu

Publications and source records attributed to C Wu.

At least 37 records · Page 2Linked to original sources
PubMed2005

Interleukin-16 in tuberculous and malignant pleural effusions.

The aim of this study was to explore the presence of interleukin (IL)-16 in pleural effusions, the correlation between IL-16 levels and cytological parameters, as well as the chemoattractant activity of IL-16 on CD4+ T-lymphocytes. Total nucleated cell and differential counts, and IL-16 concentrations in the pleural effusion from 32 patients with tuberculous pleurisy and 30 patients with lung cancer were determined. Three-colour flow cytometry was performed to determine T-lymphocyte subsets in cell pellets of pleural effusion. The chemoattractant activity of IL-16 for CD4+ T-lymphocytes was also analysed. The levels of IL-16 were significantly higher in tuberculous than in malignant effusions. However, IL-16 levels could not be used for diagnostic purposes due to significant overlap between the two groups. Positive correlations were found between the IL-16 levels and CD4+ T-cells, and pleural fluid was chemotactic for CD4+ T-cells in vitro. Intrapleural administration of IL-16 to patients produced a marked progressive influx of CD4+ T-cells into the pleural space. Compared with malignant pleural effusion, interleukin-16 appeared to be increased in tuberculous pleural effusion. Interleukin-16 levels were positively related to the numbers of CD4+ T-cells, and interleukin-16 could directly induce CD4+ T-cell infiltration into the pleural space.

Adult↗
PubMed2004

Purinergic regulation of guinea pig suburothelial myofibroblasts.

The Ca(2+)-regulating and electrophysiological properties of guinea-pig suburothelial myofibroblasts have been measured in order to investigate their potential role in the sensation of bladder fullness, due to their strategic position between the urothelium and afferent fibres. Previous work has shown that stretch of the bladder wall releases ATP. Cells that stain positively for vimentin were isolated. About 45% of cells (median membrane capacitance 13.3 pF) exhibited spontaneous depolarizations to about -25 mV with a physiological Cl(-) gradient (frequency 2.6 +/- 1.5 min(-1), duration 14.5 +/- 2.2 s, n= 15). Under voltage-clamp spontaneous inward currents (frequency 1.5 +/- 0.2 min(-1), duration 14.5 +/- 7.0 s, n= 18) were recorded, with a similar reversal potential. The spontaneous currents were preceded by intracellular Ca(2+) transients with a magnitude that was independent of membrane potential. All cells tested responded to ATP by generating an intracellular Ca(2+) transient, followed by inward currents; the currents had a similar reversal potential and slope conductance to their spontaneous counterparts. ATP-generated transients were mimicked by UTP and ADP but not by alpha,beta-methylene-ATP (1-10 microm) or CTP (30 microm), indicating that ATP acts via a P2Y receptor. Transients were partially attenuated by 1 mm suramin but PPADS (80 microm) had no effect. These data indicate that ATP acts via a P2Y receptor, but responses were resistant to the P2Y(1) antagonist MRS2179. ATP-generated transients were abolished by intracellular perfusion with heparin and TMB-8 indicating that IP(3) was the intracellular second messenger. The reversal potentials of the spontaneous and ATP-generated currents were shifted by about +45 mV by a 12-fold reduction of the extracellular [Cl(-)] and the currents were greatly attenuated by 1 mm DIDS. No transients were generated on exposure to the muscarinic agonist carbachol. We propose that these cells may play a regulatory step in the sensation of bladder fullness by responding to ATP. The precise mechanism whereby they couple urothelial ATP release to afferent excitation is the next step to be elucidated.

Animals↗
PubMed2004

Ca2+ currents in smooth muscle cells isolated from human prostate.

BACKGROUND: The objective of the investigation was to demonstrate the presence of voltage-dependent Ca2+ current in human prostate smooth muscle cells and to determine their biophysical characteristics. METHODS: Prostate smooth muscle cells were isolated from biopsy samples of human prostates obtained from prostatectomy specimens or TURP chips. Electrophysiological recordings were made under current- or voltage-clamp using patch-type electrodes. RESULTS: The average resting potential of prostate myocytes was 63 +/- 11 mV and action potentials (APs) could be elicited when K+ currents were blocked. With K-filled electrodes inward current was followed by a large outward component. When K+ currents were blocked a large Ca2+-sensitive inward current was measured. The inward current could be divided into two components, a fraction blocked by 30 microM verapamil and another by 20 microM NiCl2. CONCLUSIONS: Based on the sensitivity to antagonists and holding potential both L-type and T-type Ca2+ channels were identified in human prostate smooth muscle.

Biopsy↗
PubMed2004

Determination of hesperetin, cinnamic acid and nicotinic acid in propolis with micellar electrokinetic capillary chromatography.

Micellar electrokinetic capillary chromatography (MEKC) has been used to determine hesperetin, cinnamic acid and nicotinic acid in propolis. After systematically study the effect of buffer concentration and pH, micellar concentration, organic modifier, applied voltage and injection time, the analytical conditions were optimized. Under the optimized conditions, the three analytes could be well separated in 20 min. A good linearity between the peak current and the concentration was found in the range of 0.02-0.60 mg/ml, 0.05-1.20 mg/ml and 0.10-1.40 mg/ml with correlation coefficients of 0.9989, 0.9995 and 0.9990 for hesperetin, cinnamic acid and nicotinic acid, respectively. The detection limits were 0.006 mg/ml (hesperetin), 0.017 mg/ml (cinnamic acid) and 0.036 mg/ml (nicotinic acid). The validity of the method was verified by analyzing the three analytes in propolis oral liquids.

Anti-Infective Agents↗
PubMed2004

Osteoblast-like cell adhesion to bone sialoprotein peptides.

A number of studies have suggested that biomimetic peptides can be used in the design of a new generation of prosthetic implants to promote the successful biointegration of the implant materials. In the current study, the in vitro bioactivities of several peptides representing RGD (Arg-Gly-Asp)-containing sequences of bone sialoprotein (BSP) toward an osteoblast-like cell line (MC3T3-E1) were examined to provide insight into the molecular basis of BSP's interaction with bone cells. BSP residues 283-288, 281-290, 278-293 and 278-302 were coated on polystyrene surfaces in 96-well non-tissue (untreated) culture plates, and their osteoblast adhesive properties compared to intact BSP and fibronectin as positive controls. BSP peptides 278-302 and 278-293 were found to be the most potent in their adhesive activity, increasing the number of adherent cells to 350% of control levels at an added concentration of 1 microM. Since these two peptides were equivalent in potency, it is suggested that the region 294-302 beyond the RGD domain is not necessary for cell binding. In comparison, peptides 283-288 and 281-290 were only active at concentrations greater than 200 microM. 50-70% of the peptide-stimulated adhesion was inhibited by the pretreatment of cell suspensions with solution phase RGD, suggesting that a portion of the peptides' adhesive effects was specific and integrin-mediated, although other non-RGD flanking regions were probably also involved in the mechanism of adhesion. Importantly, a modified BSP peptide, in which an aspartic acid residue at position 288 of the RGD sequence was replaced by a glutamic acid residue to form RGE, was completely inactive as a cell adhesion stimulus at concentrations up to 200 microM. Thus, despite the potential role of non-RGD flanking regions, an intact RGD tripeptide was essential for all of the adhesive activity of the BSP peptides.

Amino Acid Sequence↗
PubMed2004

Further evidence for paternal inheritance of mitochondrial DNA in the sheep (Ovis aries).

The mitochondrial DNA of 172 sheep from 48 families were typed by using PCR-RFLP, direct amplification of the repeated sequence domain and sequencing analysis. The mitochondrial DNA from three lambs in two half-sib families were found to show paternal inheritance. Our findings provide direct evidence of paternal inheritance of mitochondria DNA in sheep. A total of 12 highly polymorphic microsatellite markers, which mapped on different chromosomes, were employed to type the sheep population to confirm family relationships. Possible mechanisms of paternal inheritance are discussed.

Animals↗
PubMed2004

Recent advances in detrusor muscle function.

Contractile activation of detrusor smooth muscle is initiated by the release of transmitters from motor nerves. Acetylcholine is a ubiquitous transmitter, as also is adenosine triphosphate (ATP) in many animal bladders and in people from several patient groups with pathological bladder function. In recent years there has been progress in explaining several cellular mechanisms that link transmitter release to contraction and these will be considered. The lifetime of ATP in the neuromuscular junction is finite and broken down ultimately to adenosine, which can exert modulatory control of contractile activation. Adenosine depresses nerve-mediated contractions and two sites of action have been proposed: an action on the motor nerves via A receptors to depress further transmitter release and a less well-defined depressant effect on the detrusor muscle. The Ca2+ ions that activate the contractile proteins are derived from intracellular stores, which releases their content via IP receptor activation and Ca2+-induced Ca2+ release. Filling of the stores in the rest interval is mediated via transmembrane flux of Ca2+through Ca2+ channels. Activation of the channels is regulated by the level of the intracellular [Ca2+], via activation and inactivation of Ca2+-sensitive K channels. Thus, Ca2+ store filling is regulated by intracellular [Ca2+] via a negative feedback process. The presence and physiological function of spontaneous contractions in detrusor remain contentious and little is known about their origin. One possibility is that they originate from random Ca2+ sparks, i.e. localized transient increases of [Ca2+] that may eventually progress to generate a cellular Ca2+ transient. Observations by confocal microscopy have revealed the presence of such sparks, especially near the cell membrane, and thus provide a cellular basis for spontaneous contractions. Finally, the questions arises as to whether detrusor smooth muscle is a functional syncitium. The demonstration of small gap junctions by electron microscopy and the demonstration of the gap junction protein connexin45 indicate that the muscle mass may indeed be functionally connected. The implications regarding the spread of excitation are discussed.

Animals↗
PubMed2004

An investigation into techniques for cleaning mold-contaminated home contents.

This study examined the efficacy of the following treatments to reduce selected fungal spore and mycotoxin levels on materials commonly found in home contents: (1) gamma irradiation at a 10-13 kiloGray exposure, (2) a detergent/bleach wash, and (3) a steam cleaning technique. A minimum of six replicates were performed per treatment. Paper, cloth, wood, and carpet were inoculated with either fungal spores (Stachybotrys chartarum, Aspergillus niger, Penicillium chrysogenum, or Chaetomium globosum) at 240,000 spores/2.54 cm2 of material or with the mycotoxins roridin A, T-2, and verrucarin A at 10 microg per 2.54 cm2 of material. Treatments were evaluated with an agar plating technique for fungal spores and a yeast toxicity culture assay for mycotoxins. Results showed that gamma irradiation inactivated fungal spores, but the treatment was not successful in inactivating mycotoxins. The washing technique completely inactivated or removed spores on all materials except for C. globosum, which was reduced on all items except paper (p < 0.05). Washing inactivated all mycotoxins on paper and cloth but not on carpet or untreated wood (p < 0.001). The steam cleaning treatment did not completely eliminate any fungal spores; however, it reduced P. chrysogenum numbers on all materials, C. globosum was reduced on wood and carpet, and S. chartarum was reduced on wood (p < 0.05). Steam cleaning was unsuccessful in inactivating any of the tested mycotoxins. These results show that the bleach/detergent washing technique was more effective overall in reducing spore and mycotoxin levels than gamma irradiation or steam cleaning. However, the other examined techniques were successful in varying degrees.

Chlorine↗
PubMed2004

Electrical characteristics of suburothelial cells isolated from the human bladder.

PURPOSE: We measured the membrane electrical characteristics as well as the response to adenosine triphosphate of cells isolated from the suburothelial layer of the bladder. MATERIALS AND METHODS: Suburothelial cells were isolated from biopsy samples of human bladder by collagenase disruption. Electrophysiological measurements were done under current and voltage clamp to record membrane potential and ionic currents using patch pipettes with a K+ based filling solution. Intracellular [Ca2+] was measured with Fura-2. RESULTS: Cells were different from epithelial cells by their spindle-shaped appearance with projections at either end. The cells stained for vimentin but epithelial and smooth muscle cells did not. The cells had small membrane capacitance (27 +/- 16 pF) and a specific membrane resistance of 90 +/- 48 x 10(9) Omega cm2. Average membrane potential was -63 +/- 14 mV but cells showed spontaneous spikes or random fluctuations of membrane potential. A small net inward current was superimposed by a larger outward current. Inward current was attenuated by the removal of extracellular Ca. Outward current showed large spontaneous fluctuations and was greatly decreased by 30 mM tetraethyl ammonium chloride. Adenosine triphosphate (30 to 100 microM) elicited an inward current of about 50 pA and large intracellular Ca2+ transients. CONCLUSIONS: These cells are electrically active which, in conjunction with the previous observation of connexin 43 labeling, suggests that they could act as an electrical network. A quantitative model of voltage distribution in such a network after the generation of inward current suggests that individual cells could not act as pacemakers, but rather a group of simultaneously activated cells could exert a peripheral excitatory effect that would amplify the magnitude of the original response. The implications of this in terms of bladder sensation are discussed.

Adenosine Triphosphate↗
PubMed2004

In vitro and in vivo investigation of a novel monoclonal antibody to plasma cells (W5 mAb).

Natural antibodies (Abs), predominantly anti-Gal alpha 1-3Gal (Gal) Abs, in non-human primates and human beings present a major hurdle to successful pig-to-primate xenotransplantation. Attempts to inhibit anti-Gal Ab production in naïve baboons using non-specific immunosuppressive or B cell-specific reagents have failed. A new rat monoclonal antibody (W5 mAb) has been generated, which binds to all B cells, including memory cells, and to the majority of plasma cells, but not to T cells. It has been tested in vitro and in vivo. By immunoprecipitation, W5 mAb bound a human leukocyte antigen class II (HLA-DR) determinant. Sorting splenic or bone marrow W5+ cells resulted in a highly enriched anti-Gal Ab and total immunoglobulin (Ig)-secretory population. In vivo studies in baboons demonstrated that W5 mAb was safe but, despite the concomitant administration of an anti-CD154 mAb to inhibit sensitization, anti-rat Abs were detected within 10 days and inhibited the effect of the W5 mAb. High levels of W5 mAb were able to completely deplete B cells in the blood, but not in lymphoid tissues. Enzyme-linked spot-forming assay (ELISPOT) demonstrated that only 50 to 60% of secreting cells (SC) were depleted in the bone marrow. No reduction in the serum levels of anti-Gal Ab was observed. W5 mAb did not cause complete inhibition of anti-Gal Ab production, probably as a result of its inability to completely deplete B and plasma cells from all lymphoid compartments.

Animals↗
PubMed2004

Peptide deformylase inhibitors as antibacterial agents: identification of VRC3375, a proline-3-alkylsuccinyl hydroxamate derivative, by using an integrated combinatorial and medicinal chemistry approach.

Peptide deformylase (PDF), a metallohydrolase essential for bacterial growth, is an attractive target for use in the discovery of novel antibiotics. Focused chelator-based chemical libraries were constructed and screened for inhibition of enzymatic activity, inhibition of Staphylococcus aureus growth, and cytotoxicity. Positive compounds were selected based on the results of all three assays. VRC3375 [N-hydroxy-3-R-butyl-3-(2-S-(tert-butoxycarbonyl)-pyrrolidin-1-ylcarbonyl)propionamide] was identified as having the most favorable properties through an integrated combinatorial and medicinal chemistry effort. This compound is a potent PDF inhibitor with a K(i) of 0.24 nM against the Escherichia coli Ni(2+) enzyme, possesses activity against gram-positive and gram-negative bacterial pathogens, and has a low cytotoxicity. Mechanistic experiments demonstrate that the compound inhibits bacterial growth through PDF inhibition. Pharmacokinetic studies of this drug in mice indicate that VRC3375 is orally bioavailable and rapidly distributed among various tissues. VRC3375 has in vivo activity against S. aureus in a murine septicemia model, with 50% effective doses of 32, 17, and 21 mg/kg of body weight after dosing by intravenous (i.v.), subcutaneous (s.c.), and oral (p.o.) administration, respectively. In murine single-dose toxicity studies, no adverse effects were observed after dosing with more than 400 mg of VRC3375 per kg by i.v., p.o., or s.c. administration. The in vivo efficacy and low toxicity of VRC3375 suggest the potential for developing this class of compounds to be used in future antibacterial drugs.

Algorithms↗
PubMed2004

Evaluation of various inclusion rates of organic zinc either as polysaccharide or proteinate complex on the growth performance, plasma, and excretion of nursery pigs.

Three experiments were conducted to evaluate the effects of feeding dietary concentrations of organic Zn as a Zn-polysaccharide (Quali Tech Inc., Chaska, MN) or as a Zn-proteinate (Alltech Inc., Nicholasville, KY) on growth performance, plasma concentrations, and excretion in nursery pigs compared with pigs fed 2,000 ppm inorganic Zn as ZnO. Experiments 1 and 2 were growth experiments, and Exp. 3 was a balance experiment, and they used 306, 98, and 20 crossbred pigs, respectively. Initially, pigs averaged 17 d of age and 5.2 kg BW in Exp. 1 and 2, and 31 d of age and 11.2 kg BW in Exp. 3. The basal diets for Exp. 1, 2, and 3 contained 165 ppm supplemental Zn as ZnSO4 (as-fed basis), which was supplied from the premix. In Exp. 1, the Phase 1 (d 1 to 14) basal diet was supplemented with 0, 125, 250, 375, or 500 ppm Zn as Zn-polysaccharide (as-fed basis) or 2,000 ppm Zn as ZnO (as-fed basis). All pigs were then fed the same Phase 2 (d 15 to 28) and Phase 3 (d 29 to 42) diets. In Exp. 2, both the Phase 1 and 2 basal diets were supplemented with 0, 50, 100, 200, 400, or 800 ppm Zn as Zn-proteinate (as-fed basis) or 2,000 ppm Zn as ZnO (as-fed basis). For the 28-d Exp. 3, the Phase 2 basal diet was supplemented with 0, 200, or 400 ppm Zn as Zn-proteinate, or 2,000 ppm Zn as ZnO (as-fed basis). All diets were fed in meal form. In Exp. 1, 2, and 3, pigs were bled on d 14, 28, or 27, respectively, to determine plasma Zn and Cu concentrations. For all three experiments, there were no overall treatment differences in ADG, ADFI, or G:F (P = 0.15, 0.22, and 0.45, respectively). However, during wk 1 of Exp. 1, pigs fed 2,000 ppm Zn as ZnO had greater (P < or = 0.05) ADG and G:F than pigs fed the basal diet. In all experiments, pigs fed a diet containing 2,000 ppm Zn as ZnO had higher plasma Zn concentrations (P < 0.10) than pigs fed the basal diet. In Exp. 1 and 3, pigs fed 2,000 ppm Zn as ZnO had higher fecal Zn concentrations (P < 0.01) than pigs fed the other dietary Zn treatments. In conclusion, organic Zn either as a polysaccharide or a proteinate had no effect on growth performance at lower inclusion rates; however, feeding lower concentrations of organic Zn greatly decreased the amount of Zn excreted.

Animal Feed↗
PubMed2003

Alpha-substituted hydroxamic acids as novel bacterial deformylase inhibitor-based antibacterial agents.

We report the synthesis and biological activity of analogues of VRC3375 (N-hydroxy-3-R-butyl-3-[(2-S-(tert-butoxycarbonyl)-pyrrolidin-1-ylcarbonyl]propionamide), an orally active peptide deformylase inhibitor. This study explores the structure-activity relationship of various chelator groups, alpha substituents, P(2)' and P(3)' substituents in order to achieve optimal antibacterial activity with minimal toxicity liability.

Amidohydrolases↗
PubMed2003

Isolation and characterization of rice mutants compromised in Xa21-mediated resistance to X. oryzae pv. oryzae.

The rice gene, Xa21, confers resistance to diverse races of Xanthomonas oryzae pv. oryzae (Xoo) and encodes a receptor-like kinase with leucine-rich repeats in the extra-cellular domain. To identify genes essential for the function of the Xa21 gene, 4,500 IRBB21 ( Xa21 isogenic line in IR24 background) mutants, induced by diepoxybutane and fast neutrons, were screened against Philippine race six (PR6) Xoo for a change from resistance to susceptibility. From two greenhouse screens, 23 mutants were identified that had changed from resistant to fully (6) or partially (17) susceptible to PR6. All fully susceptible mutants carried rearrangements at the Xa21 locus as detected by PCR and Southern hybridization. For the partially susceptible mutants, no changes were detected at the Xa21 locus based on Southern and PCR analyses. However, two of these mutants were confirmed via genetic analysis to have mutations at the Xa21 locus. Partially susceptible mutants exhibited variation in level of susceptibility to different Xoo strains, suggesting that they may carry different mutations required for the Xa21-mediated resistance. The mutants identified in this study provide useful materials for dissecting the Xa21-mediated resistance pathway in rice.

Blotting, Southern↗
PubMed2003

Neurotransmission and viscoelasticity in the ovine fetal bladder after in utero bladder outflow obstruction.

Fetal bladder outflow obstruction, predominantly caused by posterior urethral valves, results in significant urinary tract pathology; these lesions are the commonest cause of end-stage renal failure in children, and up to 50% continue to suffer from persistent postnatal bladder dysfunction. To investigate the physiological development of the fetal bladder and the response to urinary flow impairment, we performed partial urethral obstruction and complete urachal ligation in the midgestation fetal sheep for 30 days. By electrical and pharmacological stimulation of bladder strips, we found that muscarinic, purinergic, and nitrergic mechanisms exist in the developing fetal bladder at this gestation. After bladder outflow obstruction, the fetal bladder became hypocontractile, producing less force after nerve-mediated and muscarinic stimulation with suggested denervation, and also exhibited greater atropine resistance. Furthermore, fetal bladder urothelium exerted a negative inotropic effect, partly nitric oxide mediated, that was not present after obstruction. Increased compliance, reduced elasticity, and viscoelasticity were observed in the obstructed fetal bladder, but the proportion of work performed by the elastic component (a physical parameter of extracellular matrix) remained the same. In addition to denervation, hypocontractility may result from a reduction in the elastic modulus that may prevent any extramuscular components from sustaining force produced by detrusor smooth muscle.

Adenosine↗
PubMed2003

Role of the T-type Ca2+ current on the contractile performance of guinea pig detrusor smooth muscle.

AIMS: The importance of the T-type Ca(2+) current in determining detrusor contractile function was investigated by using guinea pig muscle in vitro. METHODS: NiCl(2) (200 microM) was used to block selectively the T-type Ca(2+) current, and 20 microM verapamil was used to block the L-type Ca(2+) current in this tissue. The selectivity of these agents at such concentrations has been previously demonstrated. RESULTS: In normal extracellular solution (4 mM KCl) 200 microM NiCl(2) and 20 microM verapamil reduced electrically stimulated contractions by 17 +/- 6% and 65 +/- 10%, respectively. At high concentrations of the two agents, the contraction was completely abolished by NiCl(2) but by only 74 +/- 18% in the case of verapamil; this finding suggests that NiCl(2) has additional negative inotropic actions at higher concentrations. Carbachol and KCl contractures were attenuated to a similar extent to that of electrically stimulated contractions by NiCl(2) and verapamil, which suggests that they act on the muscle rather than the motor nerve. The dependence of the membrane potential on the relative ability of NiCl(2) and verapamil to attenuate the contraction was tested by varying the extracellular [KCl], [KCl](o). Varying [KCl](o) between 2 and 10 mM depolarised detrusor myocytes from (-65.1 +/- 4.7 mV to -42.7 +/- 4.0 mV (a slope of 32 mV per 10-fold change of [KCl](o)). In low [KCl](o),blockade by NiCl(2) was more effective and that of verapamil less effective; at high [KCl](o), the reverse potency was recorded. CONCLUSIONS: The data are consistent with the hypothesis that Ca(2+) influx through both T-type and L-type Ca(2+) channels determines the contractile status of detrusor smooth muscle and that T-type channel activity is more important at membrane potentials near the resting level. A significant role for T-type channel activity in the resting state was evident in that spontaneous contractions were attenuated to a greater extent than evoked contractions.

Animals↗