Biomedical subjects

Jing Wang

Publications and source records attributed to Jing Wang.

At least 217 records · Page 12Linked to original sources

PubMed2005

Thermally-actuated, phase change flow control for microfluidic systems.

An easy to implement, thermally-actuated, noninvasive method for flow control in microfluidic devices is described. This technique takes advantage of the phase change of the working liquid itself-the freezing and melting of a portion of a liquid slug-to noninvasively close and open flow passages (referred to as a phase change valve). The valve was designed for use in a miniature diagnostic system for detecting pathogens in oral fluids at the point of care. The paper describes the modeling, construction, and characteristics of the valve. The experimental results favorably agree with theoretical predictions. In addition, the paper demonstrates the use of the phase change valves for flow control, sample metering and distribution into multiple analysis paths, sealing of a polymerase chain reaction (PCR) chamber, and sample introduction into and withdrawal from a closed loop. The phase change valve is electronically addressable, does not require any moving parts, introduces only minimal dead volume, is leakage and contamination free, and is biocompatible.

Microfluidic Analytical Techniques↗

PubMed2005

Towards the rational design of MRI contrast agents: a practical approach to the synthesis of gadolinium complexes that exhibit optimal water exchange.

The gadolinium(iii) complex of S-SSSS-NO(2)BnDOTMA exhibits water exchange kinetics that are optimal for use in high relaxivity or targeted contrast agents. However, the synthesis of this ligand is hampered by the steric encumbrance imparted upon the cyclen ring by the nitrobenzyl substituent. A relatively simple modification has been used to enable the synthesis of larger quantities of a bifunctional ligand that retains similar fast water exchange properties. The gadolinium complex of S-SSS-NO(2)BnDO3MA-1A is shown to retain the rapid water exchange kinetics characteristic of a twisted square antiprismatic (TSAP) coordination geometry (tau(M)= 6 +/- 0.4 ns).

Alkylating Agents↗

PubMed2005

Human and mouse mast cells use the tetraspanin CD9 as an alternate interleukin-16 receptor.

Interleukin-16 (IL-16) induces the chemotaxis and activation of mast cells (MCs) and other cell types. While it has been concluded that CD4 is the primary IL-16 receptor on T cells, at least one other IL-16 receptor exists. We now show that the IL-16-responsive human MC line HMC-1 lacks CD4, and that the IL-16-mediated chemotactic and Ca2+ mobilization responses of this cell can be blocked by anti-CD9 monoclonal antibodies (mAbs) but not by mAbs directed against CD4 or other tetraspanins. Anti-CD9 mAbs also inhibited the IL-16-mediated activation of nontransformed human cord blood-derived MCs and mouse bone marrow-derived MCs by 50% to 60%. The chemotactic response of HMC-1 cells to IL-16, as well as the binding of the cytokine to the cell's plasma membrane, was inhibited by CD9-specific antisense oligonucleotides. CD9 is therefore essential for the IL-16-mediated chemotaxis and activation of the HMC-1 cell line. In support of this conclusion, IL-16 bound to CD9-expressing CHO cell transfectants. The ability of wortmannin and xestopongin C to inhibit the IL-16-mediated chemotactic response of these cells suggests that the cytokine activates a phosphatidylinositol 3-kinase (PI3K)/inositol trisphosphate-dependent signaling pathway in MCs. This is the first report of a tetraspanin that plays a prominent role in a cytokine-mediated chemotactic response of human MCs.

Animals↗

PubMed2005

Distinct patterns of emergence and fading of K103N and Y181C in women with subtype A vs. D after single-dose nevirapine: HIVNET 012.

BACKGROUND: The HIVNET 012 trial in Uganda demonstrated that single-dose nevirapine (NVP) can prevent HIV-1 mother-to-child transmission. NVP resistance (NVPR) mutations were detected in 25% of women 6 to 8 weeks after NVP, with a higher rate of NVPR in women with subtype D than A. This study examined emergence and fading of specific NVPR mutations in women with these subtypes. METHODS: Plasma HIV-1 was analyzed with the ViroSeq genotyping system (Celera Diagnostics, Alameda, CA). Genotypes were obtained from paired samples collected 7 days and 6 to 8 weeks after NVP from 140 women, 83 with subtype A and 57 with subtype D. RESULTS: The rate of NVPR was similar in women with subtype A vs. D at 7 days but was higher in subtype D than A at 6 to 8 weeks. The higher rate of NVPR in subtype D was explained by at least 2 factors: Y181C faded from detection at a greater rate in women with subtype A (odds ratio = 3.06; 95% CI, 1.04, 8.90) and K103N accumulated at a greater rate in women with subtype D (odds ratio = 1.74; 95% CI, 0.62, 4.87). CONCLUSIONS: HIV-1 subtype influences selection and fading of HIV-1 variants with specific drug resistance mutations after antiretroviral drug exposure.

Anti-HIV Agents↗

PubMed2005

Sulphonylurea receptors differently modulate ICC pacemaker Ca2+ activity and smooth muscle contractility.

Appropriate gastrointestinal motility is essential to properly control the body energy level. Intracellular Ca2+ ([Ca2+]i) oscillations in interstitial cells of Cajal (ICCs; identified with c-Kit immunoreactivity) are considered to be the primary mechanism for the pacemaker activity in gastrointestinal motility. In the present study, RT-PCR examinations revealed predominant expression of the type 1 isoform of sulphonylurea receptors (SUR1) in ICCs of the mouse ileum, but expression of SUR2 was predominant in smooth muscle. In cell clusters prepared from the same tissue, smooth muscle contractility and pacemaker [Ca2+]i activity in ICCs were found to be differentially modulated by K(ATP) channel openers and sulphonylurea compounds, in accordance with the expression of SUR isoforms. 1 microM cromakalim nearly fully suppressed the mechanical activity in smooth muscle, whereas ICC pacemaker [Ca2+]i oscillations persisted. Greater concentrations (approximately 10 microM) of cromakalim attenuated pacemaker [Ca2+]i oscillations. This effect was not reversed by changing the reversal potential of K+, but was prevented by glibenclamide. Diazoxide at 30 muM terminated ICC pacemaker [Ca2+]i oscillations, but again treatment with high extracellular K+ did not restore them. These results suggest that SUR can modulate pacemaker [Ca2+]i oscillations via voltage-independent mechanism(s), and also that intestinal pacemaking and glucose control are closely associated with SUR.

ATP-Binding Cassette Transporters↗

PubMed2005

Involvement of midgastric transverse band in gastric emptying delay of functional dyspepsia.

BACKGROUND: Midgastric transverse band (MTB) was first observed over 100 years ago, after that many researchers worked on the subject postulated its physiologic role and the role in gastrointestinal diseases, but its function remains unclear. With progress of imaging methods, the nature of MTB is unveiling. In this study we investigated the effect of MTB on the gastric emptying delay in functional dyspepsia (FD) and explored the mechanism. METHODS: A total of 60 patients with FD and 65 age- and sex-matched healthy people who served as controls were studied. With (99m)Tc-DTPA labeled semi-solid fat-parched flour served as test meal, gastric emptying was examined in all subjects by using single photon emission computed tomography. Test meal was designated as general (60 g fat-parched flour) or large (80 g fat-parched flour) meal. Stomach was divided into proximal and distal parts by MTB. Half gastric emptying time, areas of different gastric parts, intragastric food distribution and MTB width were tested with in given times. RESULTS: Patients with FD showed a delayed gastric emptying and increased intragastric residue. Global and regional gastric emptying velocity was decreased. The areas of distal stomach and MTB were significantly greater in the FD patients than in the controls. Throughout the whole test period a distal stomach-dominated food distribution was shown. Those who took a large meal had longer half gastric emptying time and greater MTB area than those who took a general meal. CONCLUSIONS: Gastric emptying delay is related to enlarged MTB area. Some dyspeptic symptoms may be induced by abnormal distribution and increased retention of food in distal stomach. MTB, being like atria-ventricular valve that controls blood flow in heart, regulates transport, distribution, and emptying of food in the stomach.

Adult↗

PubMed2005

Mechanisms of ethyl(hydroxyethyl) cellulose-solid interaction: influence of hydrophobic modification.

Hydroxyethyl cellulose and its hydrophobically modified derivatives are widely used in many industrial areas such as pharmaceuticals, cosmetics, textiles, paint and mineral industries. However, the interaction mechanisms of these biopolymers and solids have not been established. In this work, the interaction mechanism and conformation of hydrophobically modified ethyl(hydroxyethyl) cellulose (C(14)-EHEC) have been investigated using spectroscopic, AFM and allied techniques. Comparison was made with corresponding unmodified analogue in order to investigate the effects of the hydrophobic modification. Electrokinetic studies showed that polysaccharides adsorption decreased the negative zeta potential of talc but did not reverse the charge. EHEC adsorption on talc was not found to be affected significantly by changes in solution conditions such as pH and ionic strength, ruling out electrostatic force as the controlling factor. However, HM-EHEC adsorption was found to increase markedly with increase in ionic strength from 0.1 to 1 suggesting a role for the hydrophobic force in this adsorption process. Fluorescence spectroscopic studies conducted to investigate the role of hydrophobic bonding using pyrene probe showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Urea, a hydrogen bond breaker, reduced the adsorption of HM-EHEC on talc markedly. In FTIR study, the changes in the infrared bands, associated with the CO stretch coupled to the CC stretch and OH deformation, were significant and therefore support strong hydrogen bonding of HM-EHEC on the solid surface. Moreover, Langmuir modeling of the adsorption isotherms suggests hydrogen bonding to be a major force for the adsorption of EHEC and C(14)-EHEC on solid since the adsorption free energies of these polymers were close to that for hydrogen bond formation. All of the above results suggest that the main driving force for EHEC adsorption on talc is hydrogen bonding rather than electrostatic interaction or hydrophobic force. For hydrophobically modified C(14)-EHEC, hydrophobic force plays a synergetic role in adsorption along with hydrogen bonding. From computer modeling and AFM imaging, it is proposed that C(0)-EHEC and C(14)-EHEC adsorb flat on talc with ethylene oxide side chains and hydrophobic groups protruding out from the surface into bulk water phase.

Journal Article↗

PubMed2005

Blocking effect and crystal structure of natrin toxin, a cysteine-rich secretory protein from Naja atra venom that targets the BKCa channel.

Cysteine-rich secretory proteins (CRISPs) are widespread in snake venoms. Some members of these CRISPs recently have been found to block L-type Ca(2+) channels or cyclic nucleotide-gated ion (CNG) channels. Here, natrin purified from Naja atra venom, a member of the CRISP family, can induce a further contractile response in the endothelium-denuded thoracic aorta of mouse which has been contracted by a high-K(+) solution. Further experiments show it can block the high-conductance calcium-activated potassium (BK(Ca)) channel in a concentration-dependent manner with an IC(50) of 34.4 nM and a Hill coefficient of 1.02, which suggests that only a single natrin molecule is required to bind an ion channel to block BK(Ca) current. The crystal structure of natrin displaying two domains in tandem shows its cysteine-rich domain (CRD) has relatively independent flexibility, especially for the C-terminal long loop (loop I) of CRD to participate in the interface of two domains. On the basis of previous studies of CNG channel and L-Ca(2+) channel blockers, and the sequence and structural comparison of natrin and stecrisp, the deviation of the vital loop I of CRD is suggested to contribute to different effects of some CRISPs in protein-protein interaction.

Amino Acid Sequence↗

PubMed2005

Comparison doses of secondary neutron with the heavy ions in a 75-Mev/n heavy ion beam.

The angular distributions for neutrons of energy >6 MeV that are induced by 75 MeV/n 12C6+ and 16O8+ ions were measured with the activation method of Al threshold detectors at the radiobiological terminal of HIRFL. The data were obtained by a high-purity Ge(HpGe) detector. The results show that the neutron angular distributions produced by heavy ion beams are strongly peaked in the forward direction and decreased exponentially with angles in experimental area. The experimental conditions for these measurements were similar to those for biological experiments, so the results should be representative of neutrons produced by heavy ions during the biological experiments and tumour therapy. Comparing with the neutron doses produced by the heavy ion beam, the heavy ion dose is the main factor in biological effects and tumour therapy response, so the contribution of neutron dose can be neglected.

Carbon↗

PubMed2005

A local mechanism mediates NAD-dependent protection of axon degeneration.

Axon degeneration occurs frequently in neurodegenerative diseases and peripheral neuropathies. Important insight into the mechanisms of axon degeneration arose from findings that the degeneration of transected axons is delayed in Wallerian degeneration slow (Wlds) mice with the overexpression of a fusion protein with the nicotinamide adenine dinucleotide (NAD) synthetic enzyme, nicotinamide mononucleotide adenylyltransferase (Nmnat1). Although both Wld(s) and Nmnat1 themselves are functional in preventing axon degeneration in neuronal cultures, the underlying mechanism for Nmnat1- and NAD-mediated axon protection remains largely unclear. We demonstrate that NAD levels decrease in degenerating axons and that preventing this axonal NAD decline efficiently protects axons from degeneration. In support of a local protective mechanism, we show that the degeneration of axonal segments that have been separated from their soma could be prevented by the exogenous application of NAD or its precursor nicotinamide. Furthermore, we provide evidence that such Nmnat1/NAD-mediated protection is primarily mediated by their effects on local bioenergetics. Together, our results suggest a novel molecular pathway for axon degeneration.

Adenosine Triphosphate↗

PubMed2005

Hydrogen-bonding interactions in the binding of loop 1 of fasciculin 2 to Torpedo californica acetylcholinesterase: a density functional theory study.

In the present study, the interactions of model complexes at the interface between loop1 of fasciculin 2 (Fas2) and acetylcholinesterase (AChE) are theoretically explored. Three interaction models based upon the crystal structure of the complex of Fas2 with AChE from Torpedo californica (PDB code ) were fully optimized at the B3LYP/6-311G(d,p) level of theory. The atoms-in-molecules (AIM) approach was employed to characterize the corresponding noncovalent hydrogen bonds through the densities and the Laplacians of electron densities at the bond critical points. The total interaction energy of loop 1 (Fas2) with AChE is predicted to be -99.4 kcal/mol. It is concluded that the Fas2 residue Thr8, which contributes more than half of the total binding energy, plays the most important role among the three binding sites. The energy decomposition results through the Kitaura-Morokuma scheme suggest that the electrostatic term is the major component of the entire interaction energy. The positive cooperativity effect revealed in the Thr8(F)-related models was confirmed through the geometry characteristics, AIM results, and the energy decomposition analysis.

Acetylcholinesterase↗

PubMed2005

Impact of different ablation strategies on the delayed cure after trans-catheter ablation for treating patients with atrial fibrillation.

BACKGROUND: Delayed cure had been observed in recurrent cases after index ablation of atrial fibrillation (AF), however, its mechanism and incidence have not been elucidated in detail. This study aims to investigate the impact of different ablation strategies on the incidence of delayed cure and its possible mechanisms after trans-catheter ablation of AF. METHODS: One hundred and fifty-one consecutive cases with highly symptomatic, drug refractory AF were included in this study [M/F = 109/42, mean age (56.0 +/- 11.2) (18 - 79) years]. Segmental pulmonary vein ablation (SPVA) was performed in 83 patients with the guidance of circular mapping catheter (SPVA Group), circumferential PV linear ablation (CPVA) was carried out in the rest 68 cases under the guidance of 3 dimensional mapping system in conjunction with circular mapping catheter (CPVA Group). Delayed cure was defined as that early recurrence of atrial tachyarrhythmias (AF, atrial tachycardia, or atrial flutter) after ablation procedure was no longer observed during subsequent follow-up, and stable sinus rhythm was maintained > or = 2 months. RESULTS: Early recurrence of atrial tachyarrhythmias was detected in 41 cases from SPVA group and 23 cases from CPVA group, and delayed cure occurred in 21.9% (9/41) of the cases from SPVA group and 47.8% (11/23) of the cases from CPVA group, more delayed cure in later group was observed (P < 0.05). Meanwhile, patients in SPVA group took a longer time to achieve a delayed cure [(27.0 +/- 18.0) days vs (14.0 +/- 8.1) days, P < 0.05], and presented more recurrent episodes [(3.50 +/- 1.08) times a week vs (2.42 +/- 1.11) times a week, P < 0.05]. However, recurrent episodes after index ablation were markedly decreased in cases with delayed cure from both groups (P < 0.05). CONCLUSIONS: Despite of an early recurrence of atrial tachyarrhythmias after index ablation of AF, delayed cure occurs in a significant number of patients undergoing either SPVA or CPVA. However, different ablation strategies place different impact on the delayed cure, more delayed cure is obtained with CPVA approach, and the delayed cure occurs earlier with this approach; the average recurrent episodes before delayed cure are also less frequently detected in CPVA group compared with those in SPVA group.

Adolescent↗

PubMed2005

GABAergic neurons express mu-opioid receptors in the ventrolateral orbital cortex of the rat.

Behavioral studies have indicated that GABAergic modulation is involved in the opioid-induced antinociception in the ventrolateral orbital cortex (VLO). The aim of the current study was to examine whether the GABAergic neurons in the rat VLO expressed mu-opioid receptor subtype 1 (MOR1). This study employed immunofluorescence histochemical double-staining technique and showed that a considerable amount of GABA- and MOR1-like immunoreactive neurons existed in layers II-VI in the VLO. Of these GABA-like immunoreactive neurons, 92.0% of them showed MOR1-like immunoreactivities. Similarly, 80.2% of MOR1-like immuoreactive neurons also exhibited GABA-like immunoreactivities. These results provide morphological evidence that opioid-induced antinociception in the VLO might be due to an inhibitory effect by opioid via MOR1 on GABAergic neurons, resulting in disinhibition of VLO projection neurons and leading to activation of the VLO-PAG brainstem descending pain control system to depress the nociceptive inputs at the spinal cord level.

Animals↗

PubMed2005

Contribution of the lymphotoxin beta receptor to liver regeneration.

The liver has an enormous capacity to regenerate in response to insults, but the cellular events and molecules involved in liver regeneration are not well defined. In this study, we report that ligands expressed on the surface of lymphocytes have a substantial effect on liver homeostasis. We demonstrate that a T cell-restricted ligand, homologous to lymphotoxin, exhibits inducible expression, competes with herpesvirus glycoprotein D for herpesvirus entry mediator on T cells (LIGHT), signaling through the lymphotoxin receptor (LTbetaR) expressed on mature hepatocytes induces massive hepatomegaly. Using genetic targeting and a receptor fusion protein, we further show that mice deficient in LTbetaR signaling have a severe defect in their ability to survive partial hepatectomy with marked liver damage and failure to initiate DNA synthesis after partial hepatectomy. We further show that mice deficient in a LTbetaR ligand, LTalpha, also show decreased ability to survive partial hepatectomy with similar levels of liver damage and decreased DNA synthesis. Therefore, our study has revealed an unexpected role of lymphocyte-restricted ligands and defined a new pathway in supporting liver regeneration.

Animals↗

PubMed2005

Development of competitive direct ELISA for gossypol analysis.

Anti-gossypol monoclonal antibody was purified from cell culturing supernatant by ammonium sulfate precipitation and Protein A AffinityPak. The antigen (i.e., gossypol) was labeled with horseradish peroxidase through Schiff-base formation. Both the purified antibody and the enzyme-labeled gossypol were employed to develop a competitive direct enzyme-linked immunosorbent assay (cdELISA) for gossypol analysis. I50 value, the concentration of gossypol causing 50% inhibition of the maximum ELISA signal in the competitive standard curve, was 0.067 microg/mL, whereas the detection limit for gossypol was 0.005 microg/mL. We also observed a good correlation (R2= 0.96, P < 0.05) between the cdELISA method and the AOCS official method for "free" gossypol (extractable gossypol and gossypol derivatives by 70% acetone) analysis of cottonseed meals. This indicates that the newly developed cdELISA could be a valuable and feasible alternative for determination of "free" gossypol, especially when the available sample is limited with relatively low gossypol concentration.

Antibodies, Monoclonal↗

PubMed2005

Neuroprotective effect of riluzole in acute noise-induced hearing loss.

Riluzole has been reported to protect against the deleterious effect of cerebral ischemia by blocking glutamatergic neurotransmission. Here, we investigated whether acoustic trauma-induced cochlear excitotoxicity could be attenuated by riluzole. Cumulative intracochlear perfusion of riluzole completely abolished single-nerve fiber activity in the guinea pig cochlea and the compound action potential of the auditory nerve. Guinea pigs treated with riluzole (100 microM) showed significantly less hearing threshold shift than untreated guinea pigs, and presented no sign of dendritic damage in the cochlea observable by electron microscopy. When coapplied with glutamate, riluzole did not prevent glutamate-induced swelling of auditory nerve dendrites, suggesting that the protective effect of riluzole was mediated principally by inhibition of glutamate release from sensory inner hair cells.

Acoustic Stimulation↗

PubMed2005

Quorum quenching enzyme activity is widely conserved in the sera of mammalian species.

Acyl-homoserine lactone (AHL) quorum sensing signals play a key role in synchronizing virulence gene expression in Pseudomonas aeruginosa, which could cause fatal bloodstream infections. We showed that AHL inactivation activity, albeit with variable efficiency, was conserved in the serum samples of all the 6 tested mammalian animals. High-performance liquid chromatography and mass spectrometry analyses revealed that mammalian sera had a lactonase-like enzyme(s), which hydrolyzed the lactone ring of AHL to produce acyl homoserine, with enzyme properties reminiscent of paraoxonases (PONs). We further showed that the animal cell lines expressing three mouse PON genes, respectively, displayed strong AHL degradation activities.

4-Butyrolactone↗

PubMed2005

Inhibition effect of Chinese herbal medicine on transcription of hepatitis C virus structural gene in vitro.

AIM: To investigate the inhibitory effect of Chinese herbal medicine on the transcription of hepatitis C virus (HCV) structural gene in Hela D cells. METHODS: Hela cell line was transfected with recombinant pBK-CMV-HCV containing HCV structural gene by Lipofectamine. RT-nested-PCR and Western blot assay were used to testify the HCV gene expression in Hela cells. The Hela cells expressing HCV structural protein were named Hela D cells. Prescriptions of Xiao chaihu Decoction (XCHD), Fufang Huangqi (FFHQ) and Bingganling (BGL) were respectively added to Hela D cells in various concentrations. Semi-quantitative RT-nested-PCR product analysis was performed according to the fluorescent density between HCV DNA band and GAPDH DNA band in gel electrophoresis after screened. RESULTS: Recombinant pBK-CMV-HCV could correctly express the HCV structural gene in Hela D cells. After co-culture of Hela D cells with three prescriptional different concentrations for 48 h respectively, the transcription of HCV gene decreased with increasing of the concentration of each prescription. The lightness ratio of HCV product bands to GAPDH product bands was 0.24, 0.10 and 0.12 in Hela D cells incubated with 0.1 g/mL of XCHD, FFHQ and BGL respectively and the lightness ratio HCV product bands to GAPDH product bands was 0.75, 0.67 and 0.61 respectively in the control cells. CONCLUSION: The prescriptions of XCHD, FFHQ and BGL partly inhibit the transcription of HCV structural gene in Hela D cells.

Base Sequence↗