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Biomedical subjects

Hai Wang

Publications and source records attributed to Hai Wang.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of PCDD/Fs and heavy metals from MSW incineration plant in Harbin.

The characterization of PCDD/Fs and heavy metals in the flue gas and fly ash of Harbin municipal solid waste (MSW) incineration plant, located in the northeast of China, was investigated in this study. The MSW was treated in a twin internal fluidized (TIF) bed incinerator. The results indicate that the emission of PCDD/Fs into the environment is 0.02 ng I-TEQ/m3 and the level of PCDD/Fs in the fabric filter fly ash is 0.7982 ng I-TEQ/g. The leachability levels of Pb, Cd and Hg in the fly ash are below the limits of environmental protection standard in China. However, the contents of Cu, Zn, and Hg are high in the fly ash. This suggests that the fly ash is a hazardous waste that requires special treatment and disposal. The practice of more than four years of operation shows that the TIF bed incinerator is very suitable and practical for China.

Air Pollutants↗
PubMed2006

Multi-dark-state resonances in cold multi-Zeeman-sublevel atoms.

We present our experimental and theoretical studies of multi-dark-state resonances (MDSRs) generated in a unique cold rubidium atomic system with only one coupling laser beam. Such MDSRs are caused by different transition strengths of the strong coupling beam connecting different Zeeman sublevels. Controlling the transparency windows in such an electromagnetically induced transparency system can have potential applications in multiwavelength optical communication and quantum information processing.

Journal Article↗
PubMed2006

Spiral turbulence developed through the formation of superimposed target waves in an oscillatory reaction-diffusion medium.

An approach leading to the development of spiral turbulence is reported here in an oscillatory reaction-diffusion medium, which is through the spontaneous formation of targetlike waves near the core of a spiral wave. The newly formed target wave emerges with its own characteristic frequency and propagates on top of the original spiral wave, which eventually leads to the breakup of the spiral at a location far from the spiral center. The radius of the surviving spiral segment decreases rapidly with the bifurcation control parameter. Calculation of power spectra suggests that the meandering of the spiral tip is responsible for the onset of the superimposed target and the phase desynchronization of the superimposed target waves.

Journal Article↗
PubMed2006

A new ATP-sensitive potassium channel opener protects endothelial function in cultured aortic endothelial cells.

OBJECTIVE: Endothelial dysfunction is an early risk factor for cardiovascular disease and hypertension. Mechanisms that participate in endothelial dysfunction include reduced nitric oxide (NO) generation and increased endothelin-1 (ET-1) generation. Endothelial ATP-sensitive potassium (K(ATP)) channels are responsible for maintaining the resting potential of endothelial cells and modulating the release of vasoactive compounds. We hypothesized that activation of endothelial K(ATP) channels might result in the protection against endothelial dysfunction. METHODS: Using cultured bovine or rat aortic endothelial cells, we examined the effects of a new K(ATP) channels opener, iptakalim, on the secretion of vasoactive substances. We also investigated its effects on the expression of adhesion molecules in metabolically disturbed cultured endothelial cells. RESULTS: In cultured aortic endothelial cells, iptakalim caused a concentration-dependent inhibition of ET-1 release and synthesis that correlated with reduced levels of mRNA for ET-1 and endothelin-converting enzyme. These effects of iptakalim were significantly inhibited by pretreatment with glibenclamide (a K(ATP) channel blocker) for 1 h. Similarly, iptakalim enhanced the release of NO in a concentration-dependent manner and increased basal levels of free intracellular calcium. Iptakalim at the concentrations of 100 and 1000 microM increased the activities of NO synthase (NOS) significantly. After the activity of NOS was blocked by L-N(omega)-nitro-arginine methyl ester (L-NAME), the inhibition of iptakalim on ET-1 release was abolished. In endothelial cell models of metabolic disturbance induced by low-density lipoprotein, homocysteine, or hyperglycemia, treatment with iptakalim could inhibit the overexpression of monocyte chemoattractant protein-1 (MCP-1), Intercellular adhesive molecule-1 (ICAM-1), and vascular cell adhesive molecule-1 (VCAM-1) mRNA. CONCLUSION: Iptakalim is a promising drug that could protect against endothelial dysfunction through activating K(ATP) channels in endothelial cells.

ATP-Binding Cassette Transporters↗
PubMed2006

Immune responses in mice to arecoline mediated by lymphocyte muscarinic acetylcholine receptor.

There is evidence that lymphocytes possess all the components of the cholinergic system independent of neuronal innervations. Thus, potential therapeutic applications of drugs targeting the neuronal cholinergic system might have side effects on the immune system. This study investigated whether arecoline could affect immunological functions in mice and explored the mechanism of the effect of arecoline on the immune system. To investigate this, arecoline at the dose of 2mg/kg was administered subcutaneously in BALB/c mice for 4 weeks to evaluate changes in immunological function both in vivo and in vitro. Several indices were used to assess immunological activation, including the spleen index, serum hemolysin levels, interleukin (IL)-2 and splenocyte proliferation. Our results showed a significant reduction in treated animals with respect to the control group in the following tests: the spleen index (86%), hemolysin against sheep red blood cells (68%), IL-2 production (73%), and splenocyte proliferation induced by concanavalin A or lipopolysaccharide (76% and 74%, respectively). The muscarinic receptor antagonist atropine (1mg/kg) reversed the inhibition of the four immune-related parameters mentioned above. Chronic atropine alone did not significantly affect the immune response. To our knowledge, this is the first study to demonstrate that arecoline interferes with the immune system by targeting the muscarinic acetylcholine receptors of the non-neuronal cholinergic system.

Animals↗
PubMed2006

A new approach to determining gas-particle reaction probabilities and application to the heterogeneous reaction of deliquesced sodium chloride particles with gas-phase hydroxyl radicals.

The reaction kinetics for gaseous hydroxyl radicals (OH) with deliquesced sodium chloride particles (NaCl(aq)) were investigated using a novel experimental approach. The technique utilizes the exposure of substrate-deposited aerosol particles to reactive gases followed by chemical analysis of the particles using computer-controlled scanning electron microscopy with energy-dispersive analysis of X-rays (CCSEM/EDX) capability. Experiments were performed at room temperature and atmospheric pressure with deliquesced NaCl particles in the micron size range at 70-80% RH and with OH concentrations in the range of 1 to 7 x 10(9) cm(-3). The apparent, pseudo first-order rate constant for the reaction was determined from measurements of changes in the chloride concentration of individual particles upon reaction with OH as a function of the particle loading on the substrate. Quantitative treatment of the data using a model that incorporates both diffusion and reaction kinetics yields a lower limit to the net reaction probability of gamma(net) > or = 0.1, with an overall uncertainty of a factor of 2.

Journal Article↗
PubMed2006

Iptakalim modulates ATP-sensitive K(+) channels in dopamine neurons from rat substantia nigra pars compacta.

Iptakalim, a novel cardiovascular ATP-sensitive K(+) (K(ATP)) channel opener, exerts neuroprotective effects on dopaminergic (DA) neurons against metabolic stress-induced neurotoxicity, but the mechanisms are largely unknown. Here, we examined the effects of iptakalim on functional K(ATP) channels in the plasma membrane (pm) and mitochondrial membrane using patch-clamp and fluorescence-imaging techniques. In identified DA neurons acutely dissociated from rat substantia nigra pars compacta (SNc), both the mitochondrial metabolic inhibitor rotenone and the sulfonylurea receptor subtype (SUR) 1-selective K(ATP) channel opener (KCO) diazoxide induced neuronal hyperpolarization and abolished action potential firing, but the SUR2B-selective KCO cromakalim exerted little effect, suggesting that functional K(ATP) channels in rat SNc DA neurons are mainly composed of SUR1. Immunocytochemical staining showed a SUR1-rather than a SUR2B-positive reaction in most dissociated DA neurons. At concentrations between 3 and 300 microM, iptakalim failed to hyperpolarize DA neurons; however, 300 microM iptakalim increased neuronal firing. In addition, iptakalim restored DA neuronal firing during rotenone-induced hyperpolarization and suppressed rotenone-induced outward current, suggesting that high concentrations of iptakalim close neuronal K(ATP) channels. Furthermore, in human embryonic kidney 293 cells, iptakalim (300-500 microM) closed diazoxide-induced Kir6.2/SUR1 K(ATP) channels, which were heterologously expressed. In rhodamine-123-preloaded DA neurons, iptakalim neither depolarized mitochondrial membrane nor prevented rotenone-induced mitochondrial depolarization. These data indicate that iptakalim is not a K(ATP) channel opener in rat SNc DA neurons; instead, iptakalim is a pm-K(ATP) channel closer at high concentrations. These effects of iptakalim stimulate further pharmacological investigation and the development of possible therapeutic applications.

ATP-Binding Cassette Transporters↗
PubMed2006

Carbon nanotubes with small and tunable diameters from poly(ferrocenylsilane)-block-polysiloxane diblock copolymers.

Iron-containing nanostructures produced from various self-assembled poly(ferrocenylsilane)-block-polysiloxane thin films are catalytically active for the initiation and growth of high density, small diameter carbon nanotubes (CNTs). Moreover, the tube diameter and density can be tuned by adjusting the chain lengths of the block copolymer. Iron-containing nanostructures from poly(ferrocenylmethylethylsilane)-b-poly(methylvinylsiloxane) polymer with 25 repeat units of an iron-containing segment and 265 repeat units of a non-iron-containing segment are able to produce CNTs with diameters around or less than 1 nm. Lithographically selective growth of CNTs across a large surface area has been demonstrated using this polymer system. Under the same growth condition, it has been found that the yield of defect-free CNTs varies with the size of the catalytically active nanostructures, which are dictated by the chain lengths of the two blocks. This result indicates that, for a specific-sized catalyst nanocluster, a unique set of growth conditions is required for synthesizing high yield, defect-free CNTs. This finding further addresses the importance of using uniform-sized catalyst-containing nanostructures for consistently achieving high-yield and high-quality CNTs with a minimum number of defects and amount of amorphous carbon.

Journal Article↗
PubMed2006

Tandem-repeated Zebrafish zp3 genes possess oocyte-specific promoters and are insensitive to estrogen induction.

Zona pellucida (Zp) proteins are glycoproteins in fish chorion and are encoded by multiple gene families, including zp1, zp2, zp3, and potentially other zp genes. Expression of zp genes in teleosts is either in the liver under the induction of estrogen or in the ovaries. In the present study, we isolated and characterized a zebrafish zp3 genomic clone and found three tandem-repeated zp3 genes with high sequence identities. We estimated that there were 10-15 zp2 and 17-21 zp3 genes in a haploid genome. We also found some variant zp2 and zp3 subfamilies, and each subfamily may have multiple members. These zp2 and zp3 genes are distributed in several different chromosomes. Ontogenetic expression of zp2 and zp3 mRNAs was first detected at 3 wk postfertilization, which was about 5 wk earlier than initial vtg1 expression, indicating that ovary development was earlier than vitellogenesis. Both zp2 and zp3 mRNAs were expressed specifically in early-growing oocytes and are insensitive to estrogen induction. Because zp3 genes are organized in tandem repeats, to investigate whether an individual zp3 promoter is capable of driving oocyte-specific expression, green fluorescence protein (gfp)-transgenic zebrafish were developed by using a 3.8-kb zp3 5' upstream region, and we found that the gfp reporter gene was faithfully expressed in developing oocytes in zp3:gfp transgenic females. Thus, the new transgenic line not only provided a convenient living marker for monitoring female gonad development, but also demonstrated that a single zp3 gene promoter is sufficient for oocyte-specific transcription.

Amino Acid Sequence↗
PubMed2006

Effects of additives on the rheological properties and injectability of a calcium phosphate bone substitute material.

An injectable calcium phosphate bone substitute material has been prepared by mixing amorphous calcium phosphate (ACP) and dicalcium phosphate dihydrate (DCPD) for use in noninvasive surgery, and the influence of additives, such as disodium hydrogen phosphate, polyethylene glycol (PEG), glycerin, and citric acid, on the rheological properties and injectability of the ACP + DCPD cement system have been studied in this work. Novel approach of thixotropy measurement has been used to characterize the stability of the pastes. The results show that the injectability and the setting time can be augmented by the addition of disodium phosphate solution to the paste but reduced by the addition of PEG 200, glycerin, or citric acid to the paste. This study suggests that the injectability and the setting time of the ACP + DCPD bone substitute material can be balanced, and the injectable calcium phosphate bone substitute material with satisfied fluidity and injectability for clinical operation can be prepared by optimizing the additives and their concentrations, according to different clinical requirements.

Biocompatible Materials↗
PubMed2006

Organchlorinated pesticides in surface sediments of Meiliang Bay in Taihu Lake, China.

The concentration level of organochlorine pesticides (OCPs) in sediments from Taihu Lake, China was investigated to evaluate the potential ecological risk. A total of 48 surface sediment samples were collected in Taihu Lake. Meiliang Bay in Taihu Lake was selected due to its importance as a drinking water source for nearby cities. Results show that the concentrations of various pesticides in sediments were in the range of 0.1-107.3 ng/g for HCH, 3.5-50.5 ng/g for endosulfan sulfate, 2.7-23.0 ng/g for endosulfan II and 0.3-59.3 ng/g for DDT. Among the OCPs, HCHs and DDTs were the most dominant contamnants in the sediments. Cyclodiene compounds were also the main pesticides in Taihu lake besides HCH and DDT. Among the cyclodiene compounds, heptachlor and endosulfan sulfate prevailed in most of the sediments. Moreover, the frequencies of detection for the metabolites of PAHs were higher than those of parent compounds, depicting that the sediments have been contaminated historically. The results obtained in this study shown that there still exist a variety of OCPs residues in Taihu Lake and Meiliang Bay.

China↗
PubMed2006

The technical development of crystals and oscillators in China and their market situation.

In recent years the manufacture of and demand for crystals and oscillators in China have been increasing quickly because of the development of industries, communications, science, transportation, and electronic techniques. This paper introduces the manufacture, research, and characteristics of the technical development of crystals and oscillators in the last ten years in China. To meet the demand from industry, science, and other markets, the number of companies that produce and research crystals and oscillators has increased from several to more than 300 in the last 20 years. Manufacturing technology and equipment have also improved. For marketing and technical reasons, more than 75% of the companies manufacture mainly 49 micro, 49 micros, and microm crystals. Now more and more companies plan to build production lines to make cold-weld crystals and other precision crystals, and at least two companies have already built their production lines. Most of the precision crystals are AT-cut but some are SC-cut. Integrated TCXOs and DTCXOs have been made by different companies, and the frequency-temperature stability of them is from +/- 2 ppm to +/- 0.5 ppm in a wide temperature range. Specifications of some OCXOs are almost the same as those of foreign OCXOs. The main design techniques in China are experimental. However, in recent years, specially designed software has been developed for oscillator design, and advanced instrumentation and equipment are used. The market situation for crystals and oscillators has increased.

Journal Article↗
PubMed2006

Protective effects of iptakalim, a novel ATP-sensitive potassium channel opener, on global cerebral ischemia-evoked insult in gerbils.

AIM: To investigate the protective role of iptakalim, a novel ATP sensitive potassium channel opener, on global cerebral ischemia-evoked insult in gerbils and glutamate-induced PC12 cell injury. METHODS: Global cerebral ischemia was induced by occluding the bilateral common carotid arteries in gerbils for 5 min. The open field maze and T-maze were employed to investigate the experimental therapeutic value of iptakalim on ischemic brain insult (n=8). The pyramidal cells in the hippocampal CA1 regions were counted to assess the protective effects of iptakalim. Glutamate released from the gerbil hippocampus and PC12 cells were determined by HPLC. Intracellular calcium was measured by Fluo-3 AM with A Bio-Rad Radiance 2100TM confocal system in conjunction with a Nikon TE300 microscope. Astrocyte glutamate uptake measurements were determined by liquid scintillation counting. RESULTS: Iptakalim (0.5-4.0 mg/kg per day, ip) could reduce the high locomotor activity evoked by ischemia and improve global cerebral ischemia-induced working memory impairments. Histological studies revealed that iptakalim could increase the survival neuron in the hippocampus CA1 zone in a dose-dependent manner. Moreover, iptakalim could reverse ischemia-evoked increases of glutamate in the hippocampus of gerbils. In an in vitro study, iptakalim protected PC12 cells against glutamate-induced excitotoxicity, reduced the [Ca(2+)](i) increases, and enhanced the glutamate uptake activity of primary cultured astrocytes. CONCLUSIONS: Iptakalim plays a key role in preventing global cerebral ischemia-evoked insults in gerbils and glutamate-induced PC12 cell injury by anti-excitotoxicity. Iptakalim might be a promising novel candidate for the prevention and/or treatment of stroke.

Amino Acids↗
PubMed2006

The differential expression of SPARC in esophageal squamous cell carcinoma.

Secreted protein, acidic and rich in cysteine (SPARC) is a matricellular protein that modulates cell adhesion and growth. The aim of this study was to assess the prevalence of SPARC mRNA and protein expression in esophageal squamous cell carcinoma (ESCC) and to investigate the role of SPARC in proliferation and metastasis of ESCC. The differential expression of SPARC between esophageal squamous cell carcinoma and its corresponding normal esophageal mucosa was analyzed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry, as well as Western blotting. The expression of SPARC in ESCC was significantly higher than that in the corresponding normal esophageal mucosa as shown by semi-quantitative RT-PCR, immunohistochemistry and Western blotting. Meanwhile, SPARC protein was also significantly up-regulated in ESCC compared with the corresponding normal esophageal mucosa. SPARC protein was located in the cytoplasm and nuclei of ESCC cells. The results of Western blotting showed that out of 18 paired samples, SPARC was up-regulated in 13 cases, no significant differences were found for the other 5 cases. These findings revealed that SPARC was up-regulated in ESCC and was closely associated with ESCC metastasis. This study provides new insights into nuclei location of SPARC.

Blotting, Western↗
PubMed2006

[Synthesis and bioactivity of substituted alpha-aminobenzylphosphonate].

AIM: To search for some substituted alpha-amino phosphonates as leading compounds with the vasodilator effects. METHODS: Target compounds were prepared from benzyl aldehyde, piperazine and diethyl phosphite using alcohol as solvent via Mannich-type reaction. In isolated rat aorta and in isolated guinea pig ileum, the vasodilator effects of compounds were investigated and evaluated whether they activated muscarine receptor. RESULTS: Seven compounds of substituted alpha-amino phosphonates have been synthesized and identified by IR, 1H NMR and elemental analysis. Three of them, compound 2a, 2b and 2c have vasodilator activity and do not activate M receptor. CONCLUSION: Two (2b and 2c) of them were found to have the notable vasodilator effect, and the rates of relaxing are (67 +/- 21) % and (82 +/- 18)%, separately. But they did not activate M receptors on ileum.

Animals↗
PubMed2006

[A novel anti-DNA antibody modified coronary stent for site-specific plasmid DNA delivery].

OBJECTIVE: To explore the feasibility of using an endovascular metal stent as a highly efficient and site-specific gene delivery system. METHODS: Stents were formulated with a collagen coating. Anti-DNA monoclonal antibodies were covalently bound to the collagen surface by a cross linking reagent of N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). Binding capacity and stability of antibody and plasmid DNA on stents were quantified by radioactive labeling. The gene transduction efficiency was evaluated in cell culture and in rabbits. RESULTS: The amount of antibodies binding on collagen matrix through SPDP reaction was 15 times higher than that of through physical absorption (P < 0.005). The binding stability of plasmid was significantly better than the control groups (P < 0.01). There was no harmful effect on cell growth with the anti-DNA antibody modified stents. The stents retrieved from cell culture after 72 hours of incubation in A10 cells showed numerous transducted cells only infiltrating the surface coating indicating a highly localized and efficient gene delivery pattern. Results of in vivo gene transfer by this modified stent revealed (2.8 +/- 0.7)% of total cells transduction and the higher transduction location was neointimal layer (about 7%). No distal spread of vector was detectable in the anti-DNA antibody modified stent implantation animals. CONCLUSIONS: Anti-DNA antibody modified stents represent a novel highly efficient and site-specific gene delivery system which can deliver various kinds of plasmid vectors. The release of plasmid DNA tethered on the stents could be controlled in some conditions. This novel system provided a novel platform for cardiovascular site-specific gene therapy.

Animals↗
PubMed2006

[Determination of residues of three stilbene drugs in animal tissues using gas chromatography-mass spectrometry].

A method has been developed to determine residual stilbenes such as diethylstilbestrol (DES), dienestrol (DIS) and hexestrol (HS) in animal tissues using solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). The procedures for extraction, cleanup on an LC-Si solid phase extraction cartridge and derivatization of stilbenes were established and optimized. The analytes were detected by mass spectrometer with electron impact source in selected ion monitoring mode (EI/SIM), and quantified with an external standard calibration curve method. Linear calibration curves were obtained in the concentration ranges from 5 to 500 microg/L for HS and from 10 to 1000 microg/L for DES and DIS (the correlation coefficients were above 0.99). Recoveries of the stilbenes were 73.0%-86.5%, and the relative standard deviations were between 1.0% and 7.2%. The limits of detection were 0.30 microg/kg for cis-DES, 0.10 microg/kg for trans-DES and HS and 0.15 microg/kg for DIS in pork and swine liver.

Animals↗