Biomedical subjects

Jie Zhang

Publications and source records attributed to Jie Zhang.

At least 73 records · Page 4Linked to original sources

PubMed2006

Effect of solids concentration distribution on the flue gas desulfurization process.

A dry flue gas desulfurization (FGD) process at 600-800 degrees C was studied in a pilot-scale circulating fluidized bed (CFB) experimental facility. Various fresh sorbent distribution types and internal structures were modeled numerically to investigate their effect on the gas-solid flow and sulfate reaction characteristics. Experimental results show that, after the fresh sorbent supply was stopped, the desulfurization efficiency declined rapidly even though the sorbent recirculation was maintained. Therefore, the fresh sorbent is the main contributor to the desulfurization process and the primary effect of the recirculated sorbent was to evenly distribute the fresh sorbent and to prolong the sorbent particle residence time. The numerical results demonstrate thatthe desulfurization efficiency varied greatly for the various fresh sorbent bottom injection methods. The desulfurization efficiency of the bottom-even injection method was 1.5 times that of the bottom two-sided injection method. Internal structures effectively improved the fresh sorbent solids concentration distribution and the desulfurization efficiency. Optimized internal structures increased the desulfurization efficiency of the bottom two-sided injection method by 46%, so that it was very close to that of the bottom-even injection method with only a 4.6% difference.

Adsorption↗

PubMed2006

Synthesis and structure of CpMo(CO)(dppe)H and its oxidation by Ph3C+.

The reaction of CpMo(CO)(dppe)Cl (dppe = Ph2PCH2CH2PPh2) with Na+[AlH2(OCH2CH2OCH3)2]- gives the molybdenum hydride complex CpMo(CO)(dppe)H, the structure of which was determined by X-ray crystallography. Electrochemical oxidation of CpMo(CO)(dppe)H in CH3CN is quasi-reversible, with the peak potential at -0.15 V (vs Fc/Fc+). The reaction of CpMo(CO)(dppe)H with 1 equiv of Ph3C+BF4- in CD3CN gives [CpMo(CO)(dppe)(NCCD3)]+ as the organometallic product, along with dihydrogen and Gomberg's dimer (which is formed by dimerization of Ph3C.). The proposed mechanism involves one-electron oxidation of CpMo(CO)(dppe)H by Ph3C+ to give the radical-cation complex [CpMo(CO)(dppe)H].+. Proton transfer from [CpMo(CO)(dppe)H].+ to CpMo(CO)(dppe)H, loss of dihydrogen from [CpMo(CO)(dppe)(H)2]+, and oxidation of Cp(CO)(dppe)Mo. by Ph3C+ lead to the observed products. In the presence of an amine base, the stoichiometry changes, with 2 equiv of Ph3C+ being required for each 1 equiv of CpMo(CO)(dppe)H because of deprotonation of [CpMo(CO)(dppe)H].+ by the amine. Protonation of CpMo(CO)(dppe)H by HOTf provides the dihydride complex [CpMo(CO)(dppe)(H)2]+OTf-, which loses dihydrogen to generate CpMo(CO)(dppe)(OTf).

Journal Article↗

PubMed2006

Characterization of Bacillus thuringiensis strain Bt185 toxic to the Asian cockchafer: Holotrichia parallela.

A new Bacillus thuringiensis strain, Bt185, was isolated from HeBei soil samples in China. Observations after transmission electron microscopy found that the strain produced spherical parasporal inclusions similar to that of the B. thuringiensis subsp. japonensis Buibui strain, which showed toxicity to both Anomala corpulenta and Popillia japonica. The plasmid profile seen on an agarose gel revealed that Bt185 contained six large bands of 191 kb, 161 kb, 104 kb, 84 kb, 56 kb, and 37 kb. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed one major band with an estimated molecular mass of 130 kDa. Polymerase chain reaction-restriction fragment length polymorphism results showed that a novel cry8-type gene sequence was found in the Bt185 strain. When we screened for this novel gene sequence, an additional novel cry8-type gene was isolated, having a partial sequence of 2340 bp and encoding a protein of 780 amino acids. Bioassay results showed that Bt185 had no toxicity against several Coleopteran and Lepidopteran pests. However, Bt185 exhibited toxicity against larvae of the Asian cockchafer, Holotrichia parallela. This is the first report of the occurrence of a Bacillus strain that has insecticidal activity against Holotrichia parallela larvae.

Animals↗

PubMed2006

Dopamine transporter genotype influences the physiological response to medication in ADHD.

Attention deficit hyperactivity disorder (ADHD) is a complex, multifactorial disorder characterized by physical hyperactivity and behavioural disinhibition. Short interval cortical inhibition (SICI), measured in motor cortex with transcranial magnetic stimulation, is reduced in ADHD and correlates with symptom severity. However, ADHD medication-induced changes in SICI vary widely among normal individuals and have not been well studied in children with ADHD. Therefore, we undertook this study to measure and compare effects of two ADHD medications, methylphenidate (MPH), a psychostimulant, and atomoxetine (ATX), a selective norepinephrine reuptake inhibitor, on SICI in children with ADHD. In addition, we wished to determine whether a genetic variation in the dopamine transporter (DAT1), a site of action of MPH, could influence the effects of MPH or ATX on SICI. We performed a randomized, double-blind, single-dose, crossover study comparing 0.5 mg/kg MPH with 1.0 mg/kg ATX in 16 children with ADHD, aged 8-17. Seven were homozygotes and 9 heterozygotes for the DAT1 variable number of tandem repeats 10-repeat allele. Medication and genotype effects on SICI were estimated with repeated measures, mixed model regression. We found that MPH and ATX had similar effects on SICI. However, medication effects differed significantly by DAT1 genotype [F(2,13) = 13.04, P = 0.0008]. Both MPH and ATX increased SICI in heterozygotes but not in 10-repeat homozygotes. In conclusion, MPH and ATX have similar effects on SICI in children with ADHD. A genetic variation in DAT1, previously linked to ADHD risk and MPH behavioural responses, influences the neurophysiological effects of both MPH and ATX.

Adolescent↗

PubMed2006

The protective effect of vitamin E against oxidative damage caused by formaldehyde in the testes of adult rats.

AIM: To investigate the effect of formaldehyde (FA) on testes and the protective effect of vitamin E (VE) against oxidative damage by FA in the testes of adult rats. METHODS: Thirty rats were randomly divided into three groups: (1) control; (2) FA treatment group (FAt); and (3) FAt + VE group. FAt and FAt + VE groups were exposed to FA by inhalation at a concentration of 10 mg/m(3) for 2 weeks. In addition, FAt + VE group were orally administered VE during the 2-week FA treatment. After the treatment, the histopathological and biochemical changes in testes, as well as the quantity and quality of sperm, were observed. RESULTS: The testicular weight, the quantity and quality of sperm, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione (GSH) were significantly decreased whereas the level of malondialdehyde (MDA) was significantly increased in testes of rats in FAt group compared with those in the control group. VE treatment restored these parameters in FAt + VE group. In addition, microscopy with hematoxylin-eosin (HE) staining showed that seminiferous tubules atrophied, seminiferous epithelial cells disintegrated and shed in rats in FAt group and VE treatment significantly improved the testicular structure in FAt + VE group. CONCLUSION: FA destroys the testicular structure and function in adult rats by inducing oxidative stress, and this damage could be partially reversed by VE.

Animals↗

PubMed2006

Expression and genomic status of EGFR and ErbB-2 in alveolar and embryonal rhabdomyosarcoma.

Both epidermal growth factor receptor (EGFR) and ErbB-2 play an important role in cancer biology and constitute promising molecular targets of therapy. EGFR and ErbB-2 expression has been observed in rhabdomyosarcoma cell lines but not analyzed systematically in rhabdomyosarcoma tumors. Tissue microarray sections representing 66 rhabdomyosarcoma tumors (34 embryonal rhabdomyosarcoma, 32 alveolar rhabdomyosarcoma) were surveyed by immunohistochemistry using antibodies specific for EGFR and ErbB-2. Immunostains were assessed for intensity (0: no immunostaining; 1: weak; 2: moderate; 3: strong) and percentage of at least 500 neoplastic cells exhibiting membranous or membranous and cytoplasmic immunostaining. EGFR and ErbB-2 expression was considered positive if the product of intensity and percentage was greater than 10. Patients had a median age of 5.7 years (range 8 months-19.1 years), and of 65/66 patients, 38 were males and 27 were females. Expression of ErbB-2 was identified in 22/66 (33%) cases and tended to be more frequent in the alveolar subtype (13/32, 41%, vs 9/34, 26%, P=0.30). Expression of EGFR was identified in 31/66 (47%) cases and correlated with the embryonal subtype (26/34, 76%, vs 5/32, 16%, P<0.0001) independent of stage, age, and gender. Coexpression of EGFR and ErbB-2 was identified in eight tumors, of which six were embryonal rhabdomyosarcoma. None of the cases exhibited EGFR or ErbB-2 gene amplification, as assessed using fluorescence in situ hybridization. Furthermore, analysis of 11 additional rhabdomyosarcoma tumors (six alveolar; five embryonal) revealed no evidence of mutations in EGFR exons 18, 19, 20, and 21. In summary, expression of EGFR and/or ErbB-2 is detected in a sizeable subset of rhabdomyosarcoma tumors without evidence of EGFR or ErbB-2 amplification or mutations in the EGFR tyrosine kinase domain. Notably, expression of EGFR correlates with the embryonal subtype, which is also more likely to coexpress EGFR and ErbB-2.

Adolescent↗

PubMed2006

Comparison of the epidemiology and co-morbidities of heart failure in the pediatric and adult populations: a retrospective, cross-sectional study.

BACKGROUND: Heart failure is a clinical syndrome that is associated with a significant number of interventional procedures and has received a large amount of scrutiny in the adult literature; however, the epidemiology in children is less well described. METHODS: We analyzed two large, commercially available inpatient datasets collected in 1997 by the Agency for Healthcare Research and Quality: the Kids' Inpatient Database and the National Inpatient Study, accounting for 50% of the U.S. pediatric discharges and 20% of the U.S. adult discharges in 1997. RESULTS: The database contained 5,610 children and 732,752 adults with a diagnosis of HF. When compared with the adult sample, the pediatric sample showed a higher proportion with cardiac procedures (61.4% vs. 0.28%, p < 0.01), a higher prevalence of congenital heart disease (61% versus 0.3%, p < 0.01), a higher percentage of male patients (50% pediatric vs. 44% adult, p < 0.01), and a lower percentage of white patients (40.9% vs. 65.6%, p < 0.01). Children had a significantly different spectrum of co-morbidities compared with adults. There was no difference in mortality rate between children and adults (7.5% vs. 7.9%, p = NS). CONCLUSION: There are significant differences in the epidemiological profile of children and adults with heart failure. Children suffer from different types of co-morbidities and require different procedures in the hospital setting. As such, children with heart failure who are hospitalized may require significantly different facilities, management and therapeutic intervention than adults with similar symptoms.

Adolescent↗

PubMed2006

Comparison of the results for three automated immunoassay systems in determining serum HBV markers.

BACKGROUND: Automated immunoassay analyzers are used to identify hepatitis B virus (HBV) serum markers. In regions with high prevalence of HBV, it is imperative to compare test results from different immunoassay analyzers. METHODS: Samples from 496 subjects were collected and HBV markers were determined (double-blind, parallel manner) using Abbott AxSYM, Roche Modular Analytics E170, and Abbott Architect i2000). RESULTS: Concurrence between AxSYM and E170 was 97.78% for HBsAg, 91.13% for anti-HBs, 98.79% for anti-HBc, 98.39% for HBeAg, and 88.91% for anti-HBe. Positive rates of anti-HBs and anti-HBe from AxSYM were lower than E170 (P<0.01). Concurrence between AxSYM and Architect i2000 was 98.79% for HBsAg, 91.33% for anti-HBs, 95.97% for anti-HBc, 98.39% for HBeAg, and 95.77% for anti-HBe. Positive anti-HBs rates from AxSYM were lower than Architect i2000 (P<0.01). Concurrence between E170 and Architect i2000 was 97.38% for HBsAg, 94.15% for anti-HBs, 95.56% for anti-HBc, 99.60% for HBeAg, and 88.10% for anti-HBe. Positive anti-HBe rates using Architect i2000 were lower than E170 (P<0.01). Overall, the greatest differences were observed in samples with low-level serum HBV markers. CONCLUSION: Significant discrepancies were observed among results for the 3 automated immunoassay analyzers, especially for low-level anti-HBs and anti-HBe results.

Adolescent↗

PubMed2006

Development and application of microporous hollow fiber protected liquid-phase microextraction via gaseous diffusion to the determination of phenols in water.

A new organic solvent-free microextraction technique termed liquid-gas-liquid microextraction (LGLME) was developed. In this technique, a small amount (6 microl) of aqueous acceptor solution (0.5M NaOH) is introduced into the channel of a 2.65 cm polypropylene hollow fiber. The hollow fiber is then immersed in an aqueous sample donor solution. The aqueous acceptor phase in the channel of the hollow fiber is separated from the sample solution by the hydrophobic microporous hollow fiber wall with air inside its pores. The analytes (phenols) passed through the microporous hollow fiber membrane by gas diffusion and were then trapped by the basic acceptor solution. After extraction, the acceptor solution was withdrawn into a microsyringe and injected into a capillary electrophoresis sample vial for subsequent analysis. Limits of detection of between 0.5 and 10 microg/l for eight phenols could be achieved. The relative standard deviations (n=6) of this technique between 2.7 and 7.6%. The technique also provides good enrichment factors for all the eight analytes.

Chromatography, Gas↗

PubMed2006

Homeodomain-mediated beta-catenin-dependent switching events dictate cell-lineage determination.

While the biological roles of canonical Wnt/beta-catenin signaling in development and disease are well documented, understanding the molecular logic underlying the functionally distinct nuclear transcriptional programs mediating the diverse functions of beta-catenin remains a major challenge. Here, we report an unexpected strategy for beta-catenin-dependent regulation of cell-lineage determination based on interactions between beta-catenin and a specific homeodomain factor, Prop1, rather than Lef/Tcfs. beta-catenin acts as a binary switch to simultaneously activate expression of the critical lineage-determining transcription factor, Pit1, and to repress the gene encoding the lineage-inhibiting transcription factor, Hesx1, acting via TLE/Reptin/HDAC1 corepressor complexes. The strategy of functionally distinct actions of a homeodomain factor in response to Wnt signaling is suggested to be prototypic of a widely used mechanism for generating diverse cell types from pluripotent precursor cells in response to common signaling pathways during organogenesis.

Animals↗

PubMed2006

Application of power spectra patterns in Fourier transform square wave voltammetry to evaluate electrode kinetics of surface-confined proteins.

This paper describes an application of Fourier transform (FT) voltammetry that provides a quantitative evaluation of the electron-transfer kinetics of protein molecules attached to electrode surfaces. The potential waveform applied in these experiments consists of a large-amplitude square wave of frequency f superimposed onto the traditional triangular voltage used in dc cyclic voltammetry. The resultant current-time response, when Fourier transformed into the frequency domain, provides patterns of data at the even harmonic frequencies that arise from nonlinearity in the Faradaic response. These even harmonic contributions are ideally suited for kinetic evaluation of electron-transfer processes because they are highly selective to quasi-reversible behavior (insensitive to reversible or irreversible processes) and almost devoid of background charging current. Inverse FT methods can then be used to provide the wave shapes of the dc as well as the ac voltammetric components and other characteristics employed to detect the level of nonideality present relative to theoretical models based upon noninteracting surface-confined molecules. The new form of data evaluation has been applied to the electron-transfer properties of a typical biological electron carrier, the blue copper protein azurin, immobilized on polycrystalline gold electrodes modified with self-assembled monolayers of different length alkanethiols. Details of the electrode kinetics (rates of electron transfer, dispersion, and charge-transfer coefficients) as a function of alkanethiol, apparent surface coverage, and capacitance are all deduced from the square wave (FT-inverse FT) protocol, and the implications of these findings are considered.

Azurin↗

PubMed2006

Mechanistic analysis of the electrocatalytic properties of dissolved alpha and beta isomers of [SiW12O40]4- and solid [Ru(bipy)3]2[alpha-SiW12O40] on the reduction of nitrite in acidic aqueous media.

Voltammetric studies on the reduction of alpha and beta isomers of the Keggin polyoxometalate anion [SiW12O40]4- reveal a series of electrochemically reversible processes in acidic aqueous media. In the presence of NO2-, catalytic current is detected in the potential region of the [SiW12O40]4-/5- process. Electronic spectroscopy and simulation of voltammetric data undertaken at variable [NO2-] and [H+] allow the following mechanism to be postulated, [SiW12O40]4- + e- <-->[SiW12O40]5-, H+ + HNO2 <--> NO+ + H2O, NO+ + [SiW12O40]5- --> NO + [SiW12O40]4-. The second-order rate constant for the rate-determining step is faster for the alpha isomer than for the beta one. This may be attributed to the different reversible potentials of -0.144 V (alpha isomer) and -0.036 V vs Ag/AgCl (beta isomer) and, hence, smaller driving force for an assumed outer sphere electron-transfer reaction in the case of beta isomer. A stable, water-insoluble, thin-film [Ru(bipy)3]2[alpha-SiW12O40] chemically modified electrode was generated electrochemically via ion-exchange of [Ru(bipy)3]2+ with Bu4N+ in the [Bu4N]4[alpha-SiW12O40] solid. The first reduction process with this modified electrode gives rise to the reaction [Ru(bipy)3]2[alpha-SiW12O40](solid) + H+(soln) + e- <--> H[Ru(bipy)3]2[alpha-SiW12O40](solid). The need to transfer a proton from the solution to the solid phase for charge neutralization purposes introduces a hydrogen-ion concentration dependence into this reaction, which is not found in the solution-phase study. Nevertheless, the voltammetric catalytic activity with respect to nitrite reduction is retained with the chemically modified electrode. However, nitrite catalysis with the [Ru(bipy)3]2[alpha-SiW12O40]-modified electrode is now independent of concentration of H+, rather than exhibiting a first-order dependence, and full mechanistic details for this process are unknown.

Journal Article↗

PubMed2006

Single-point velocity statistics of forced and decaying two-dimensional turbulence.

The single-point (SP) velocity statistics are investigated in forced and decaying two-dimensional turbulence in a flowing soap film. It is shown that the probability distribution functions (PDF) in both cases deviate from a Gaussian distribution, which is normally anticipated in turbulent fluid flows. In the forced turbulence case, the tail of the SP velocity PDF decays faster than Gaussian (termed the sub-Gaussian) and can be correlated with the forcing statistics on small scales. In the decaying-turbulence case, the SP velocity PDF evolves from a sub-Gaussian to a super-Gaussian behavior as a function of time. However, in all times, the locally averaged vorticity remains normally distributed. While our forced turbulence data may be explained by a recent theory proposed by Falkovich et al., the decaying-turbulence data remain unexplained.

Journal Article↗

PubMed2006

Blockade of experimental atopic dermatitis via topical NF-kappaB decoy oligonucleotide.

Atopic dermatitis (AD) is a common chronic skin inflammatory disease. Long-term use of topical corticosteroids in skin inflammation poses risks of systemic and local side effects. The NF-kappaB transcription factor family plays a central role in the progression and maintenance of AD. This study explores the possibility of using topical NF-kappaB Decoy as a novel therapeutic alternative for targeting Th1/Th2-driven skin inflammation in experimental AD. A high-affinity, topical NF-kappaB Decoy developed for human efficacy demonstrates: (i) efficient NF-kappaB Decoy penetration in pig skin, (ii) NF-kappaB Decoy nuclear localization in keratinocytes and key immune cells, and (iii) potent "steroid-like" efficacy in a chronic dust-mite antigen skin inflammation treatment model. NF-kappaB Decoy exerts its anti-inflammatory action through the effective inhibition of essential regulators of inflammation and by induction of apoptosis of key immune cells. Unlike betamethasone valerate (BMV), long-term NF-kappaB Decoy treatment does not induce skin atrophy. Moreover, topical NF-kappaB Decoy, in contrast to BMV, restores compromised stratum corneum integrity and barrier function. Steroid withdrawal causes rapid rebound of inflammation, while the NF-kappaB Decoy therapeutic benefit was maintained for weeks. Thus, topical NF-kappaB Decoy provides a novel mechanism of reducing chronic skin inflammation with improved skin homeostasis and minimal side effects.

Administration, Topical↗

PubMed2006

Nicotine attenuates beta-amyloid-induced neurotoxicity by regulating metal homeostasis.

Nicotine reduces beta-amyloidosis and has a beneficial effect against Alzheimer's disease (AD), but the underlying mechanism is not clear. The abnormal interactions of beta-amyloid (Abeta) with metal ions such as copper and zinc are implicated in the process of Abeta deposition in AD brains. In the present study, we investigated the effect of nicotine on metal homeostasis in the hippocampus and cortex of APP(V717I) (London mutant form of APP) transgenic mice. A significant reduction in the metal contents of copper and zinc in senile plaques and neuropil is observed after nicotine treatment. The densities of copper and zinc distributions in a subfield of the hippocampus CA1 region are also reduced after nicotine treatment. We further studied the mechanism of nicotine-mediated effect on metal homeostasis by using SH-SY5Y cells overexpressing the Swedish mutant form of human APP (APPsw). Nicotine treatment decreases the intracellular copper concentration and attenuates Abeta-mediated neurotoxicity facilitated by the addition of copper, and these effects are independent of the activation of nicotinic acetylcholine-receptor. These data suggest that the effect of nicotine on reducing beta-amyloidosis is partly mediated by regulating metal homeostasis.

Amyloid beta-Peptides↗

PubMed2006

Application of liquid-phase microextraction and on-column derivatization combined with gas chromatography-mass spectrometry to the determination of carbamate pesticides.

A method has been established for the determination of five carbamate pesticides in water samples using liquid-phase microextraction (LPME) followed by on-column derivatization and gas chromatography-mass spectrometric (GC-MS) determination. Trimethylphenylammonium hydroxide (TMPAH) and trimethylsulfonium hydroxide (TMSH) were used as derivatization reagent for extracts prior to GC-MS analysis as carbamate pesticides are thermally labile compounds. Parameters that affect the extraction efficiency (selection of organic solvent and extraction time) and derivatization efficiency (choice of derivatization reagent and concentration of derivatization reagent) were investigated. The proposed method provided good enrichment factors up to 224, with reproducibility ranging from 4.86 to 7.81%, and good linearity from 1 to 400 microg/L. The limits of detection (LODs) ranged between 0.2 and 0.8 microg/L (S/N = 3) using GC-MS with selective ion monitoring. This method was applied to the determination of carbamate pesticides in tap water and waste water.

Carbamates↗

PubMed2006

Two novel luminescent lanthanide sulfate-carboxylates with an unusual 2-D bamboo-raft-like structure based on the linkages of left- and right-handed helical tubes involving in situ decarboxylation.

Two novel 2-D bamboo-raft-like lanthanide luminescent materials [Ln(Himc)(SO4)(H2O)] (Ln = Dy, Eu; H2imc = 4-imidazolecarboxylic acid), constructed from alternate left- and right-handed helical tubes, were synthesized and characterized; interestingly, H2imc came from the in situ decarboxylation of the 4,5-imidazoledicarboxylic acid (H3imdc) in the hydrothermal reactions.

Journal Article↗

PubMed2006

Cilostazol protects diabetic rats from vascular inflammation via nuclear factor-kappa B-dependent down-regulation of vascular cell adhesion molecule-1 expression.

Vascular cell adhesion molecule (VCAM)-1 plays a critical role in the initiation and development of vascular inflammation and selective inhibition of adhesion molecules expressed by endothelial cells may present a new therapeutic strategy for the treatment of vascular complications associated with diabetes mellitus. Increasing evidence indicates that cilostazol, a cAMP phosphodiesterase inhibitor, reduces VCAM-1 expression on endothelial cells. In this study, we have tested the effect of cilostazol on the development of vascular inflammation in rats with streptozotocin-induced diabetes and determined the mechanism by which cilostazol prevents diabetes-induced vascular inflammation in the aorta. Diabetic rats were treated with different dose of cilostazol (27 or 9 mg/kg/day) for 8 weeks, and aortae were removed for the evaluation of vascular inflammation. The VCAM-1 protein expression and VCAM-1 mRNA transcripts were analyzed by immunohistochemical staining and in situ hybridization assay, respectively. Our results demonstrated that cilostazol treatment prevents the overexpression of VCAM-1 and protects diabetic rats from vascular inflammation. More importantly, our mechanistic studies suggested that cilostazol controls the VCAM-1 overexpression via inhibiting the activation of nuclear factor-kappaB.

Animals↗