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Biomedical subjects

X H Zhang

Publications and source records attributed to X H Zhang.

At least 19 recordsLinked to original sources
PubMed2006

The effects of different immunosuppressants on chronic allograft nephropathy by affecting the transforming growth factor-beta and Smads signal pathways.

OBJECTIVE: This study investigated the effects of various immunosuppressants on chronic allograft nephropathy (CAN) by affecting transforming growth factor-beta (TGF-beta) and Smads signal pathway. METHODS: Vascular smooth muscle cells (VMSC) from rat aorta were incubated for 6 or 12 hours with various immunosuppressants. Cyclosporine (CsA) (3 microg/mL), FK506 (1 microg/mL), mycophenolate mofetil (MMF) (0.3 microg/mL), rapamycine (Rapa) (10 microg/mL), CsA (1 microg/mL/MMF 0.3 microg/mL). We used the Sprague-Dawley Wistar rat accelerated kidney sclerosis model. Before transplantation, the kidney was preserved 1 hour in 0 degrees C to 4 degrees C heparin sodium chloride solution to reinforce the cold ischemia injury. The rats were divided into eight groups (each group n = 8): group A, pseudo-OP; group B, isotransplantation; group C, CsA 6 mg/kg . d; group D, FK506 0.15 mg/kg . d; group E, MMF 20 mg/kg . d; group F, Rapa 0.8 mg/kg. d; group G, CsA 3 mg/kg . d + MMF 20 mg/kg . d. The serum creatinine levels and pathological changes, according to the Banff scheme, were observed at 2, 4, 6, 8 and 12 weeks posttransplantation. Immunohistochemistry and quantitative fluorescence polymerase chain reactions were used to end localize and quantitate the expression of TGF-beta1 and Smad 2, 3, 7 in VMSC and in the transplanted kidney. RESULTS: CsA and FK506 stimulated gene expression and protein production of TGF-beta1, smad2, and smad3, but inhibited expression of smad7 both in VSMC and in the transplanted kidney. In contrast, MMF and Rapa down-regulated gene expression and protein production of TGF-beta1, smad2, 3 while up-regulating expression of smad7. There was no significant difference between the CsA group and the FK506 group, as well as the MMF group and the Rapa group. The group treated with CsA + MMF was similar to the MMF and the Rapa groups. CONCLUSION: Our study suggested that various immunosuppressants affected differentially TGF-beta1 and Smads signal pathways in rat VSMC and kidney grafts. CsA and FK506 can cause CAN, owing to up-regulated expression of smad2 and smad3, and down-regulation of smad7 expression. MMF and Rapa can prevent the CAN progression, because of down-regulation of the expression of smad2 and smad3, with increased smad7 production.

Animals↗
PubMed2005

Ultrafast and large third-order nonlinear optical properties of CdS nanocrystals in polymeric film.

We report the ultrafast and large third-order nonlinear optical properties of CdS nanocrystals (NCs) embedded in a polymeric film. The CdS NCs of 2 nm radius are synthesized by an ion-exchange method and highly concentrated in the two layers near the surfaces of the polymeric film. The two-photon absorption coefficient and the optical Kerr coefficient are measured with laser pulses of 250 fs duration at 800 nm wavelength. The one-photon and two-photon figures of merit are determined to be 3.1 and 1.3, respectively, at irradiance of 2 GW/cm(2). The observed nonlinearities have a recovery time of approximately 1 ps. The two-photon-generated free carrier effects have also been observed and discussed. These results demonstrate that CdS NCs embedded in polymeric film are a promising candidate for optical switching applications.

Journal Article↗
PubMed2005

Identification, localization and functional in vitro and in vivo activity of oxytocin receptor in the rat penis.

We recently found that the oxytocin receptor (OTR) is expressed in the human and rabbit corpus cavernosum and mediates contractility in vitro. The present study extended our investigations to the rat, and explored whether OTR regulates penile detumescence in vivo. Real-time RT-PCR quantitatively characterized the distribution of OTR mRNA in the male genital tract. Specific transcripts for OTR were expressed in all the tissues investigated. Penile expression of OTR was comparable to that observed in testis and prostate. Western blot analysis detected a single band of the expected molecular mass for OTR in all tissues examined, including rat penis. Expression of OTR protein in rat penile extracts was further confirmed by binding studies, using the OTR selective radiolabeled ligand 125I-OTA (K(d) = 17 +/- 6.5 pM, B(max)=15.7 +/- 5 fmoles/mg protein). OTR was immunolocalized to the endothelial and smooth muscle compartments of cavernous spaces and blood vessels. In rat corpus cavernosum strips, oxytocin (OT) and an OTR selective agonist ([Thr4,Gly7]OT) induced identical increases in tension, while different vasopressin agonists were less active. In vivo, OT intra-cavernous injection (ICI) dose-dependently inhibited intracavernous pressure (ICP) increase elicited by either electrical stimulation of the cavernous nerve or ICI of papaverine with similar IC(50)s (117.7 +/- 37 mU). The OTR antagonist, atosiban, counteracted the contractile effect of OT both in vitro and in vivo. Atosiban alone significantly increased ICP at lower stimulation frequencies (2 Hz = P<0.001 and 4 Hz = P<0.05 vs control), but not at the maximal frequency (16 Hz). Our data showed that OTR is present in the rat penis and mediates contractility both in vitro and in vivo, therefore suggesting a role for OT in maintaining penile detumescence.

Animals↗
PubMed2004

T-helper and T-cytotoxic cell subsets monitoring during active cytomegalovirus infection in liver transplantation.

OBJECTIVE: The objectives of this study was to analyze the peripheral blood T-lymphocyte subsets of the Th1-related versus Th2-related cytokines of CD4+ cells, and the Tc1 versus Tc2 cytokines of CD8+ cells liver transplant recipients with versus without active cytomegalovirus (CMV) infection. METHODS: Isolated peripheral blood mononuclear cells (PBMC) were stimulated using PMA/Ionomycin/Monensin. Interleukin (IL)-4 and interferon gamma (IFN-gamma) production by CD4+ and CD8+T cells were determined using fluorescence-activated cell sorter (FACS) analysis. RESULTS: The ratios of CD4/CD8 were significantly lower among active CMV-infected patients. The levels of Th2 and Tc2 cytokines (IL-4) were similar between CMV-infected and uninfected patients. However, the levels of Th1-type and Tc1-type cytokines (IFN-r) were significantly lower among active CMV-infected patients. CONCLUSIONS: Low levels of Th1-type cytokines seem to correlate with active CMV infection in liver transplant recipients.

Antigens, CD↗
PubMed2004

Control of nutrients after discharge to lakes through wastewater.

Control of nutrients as nitrogen and phosphorus after discharge into lakes is necessary since it is difficult and costly to control within wastewater plants currently in China. This paper studied the cycling of phosphorus and nitrogen with water and sediments from two lakes in China. It is found that oxygen plays a critical role in regulating phosphorus and nitrogen cycling within water and sediments. Three different oxygenation methods including aeration, calcium peroxide and hydrogen peroxide were studied to control phosphorus and nitrogen in overlying water. In anoxic conditions, the P concentration in water increased from an average 14 microg/L to 115.2 microg/L for Xili Lake, and from an average 24 microg/L to 1,000 microg/L for Jinchun Lake. The concentration of ammonia increased under anoxic conditions, while the concentration of nitrate increased under oxic conditions. In anoxic conditions, the nitrate concentration decreased probably through denitrification. Both N and P accumulation processes can be controlled under the three treatments. The phosphorus removal efficiency from the water body was in the order of CaO2 addition > aeration > H2O2 addition, while controlling effectiveness for ammonia was in the order of aeration > CaO2 addition > H2O2 addition.

Ammonia↗
PubMed2003

Variation of microcystins in a lake for water supply.

A site investigation was conducted to correlate the relationships between microcystins (MC) concentration and algal growth in Dianchi Lake in China. Laboratory experiments were undertaken to test the effects of sediment adsorption, photoirradiation and biodegradation on microcystins removal. Bioaccumulation of microcystins was also determined using silver carp fish. It was observed that MC concentrations varied in accordance with algae growth in Dianchi Lake. The results obtained in the laboratory demonstrated that the removal of MC with fresh sediments was less than 10%, photoirradiation removed more than 75% MC within two hours, and the biodegradation needed much longer time to produce substantial degradation of MC. The results suggest that bioaccumulation of microcystins in fish was not significant in Dianchi Lake.

Animals↗
PubMed2003

Fluctuation of microcystins in water plant.

This study was undertaken to investigate the distribution and variation of microcystins (MC) from a water resource to a water plant in China including long distance transportation, ClO2 preoxidation, coagulation/precipitation, filtration, and disinfection. Advanced treatment methods including ozonation and granular activated carbon (GAC) adsorption were tested to remove microcystins from drinking water. The results indicated that, when containing high level of algae in raw water, preoxidation at 2 mg/L of ClO2 was not enough to stop algae growth in long distance transportation. In the water plant studied, both coagulation and filtration caused significant increase instead of removal of microcystins in drinking water. Chlorine disinfection removed part of microcystins. However, both ozonation and GAC adsorption were able to remove microcystins completely, thereby improving the quality of drinking water in terms of microcystins.

China↗
PubMed2001

[Study on the fusion expression of FBXO30: a novel member of F-box protein family].

OBJECTIVE: The cDNA sequence of the coding region of FBXO30 (F-box only protein 30), which is a novel member of F-box protein family, was cloned into the mammalian expression vector pEGFP-C2 by non-directional cloning method and introduced into the NIH 3T3 cells by liposome transfection. Observation under the fluorescent microscopy after transfection showed that EGFP (enhanced green fluorescent protein)/FBXO30 was expressed and existed mainly in the cytoplasm. At the same time, the cDNA sequence of the coding region of FBXO30 was cloned into prokaryotic expression vector pGEX-4T-2 by directional cloning strategy. The GST (glutathione S-transferase)/FBXO30 fusion protein was expressed under the induction of IPTG (isopropylthio-beta-D-galactoside) in E. coli. A new band (approximately 65.5 kD) was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Purification of the GST-fused FBXO30 was carried out by affinity chromatography with glutathione sepharose 4B. The fusion expression of FBXO30 indicates that: FBXO30 protein is a cytoplasmic soluble protein, and the stable fusion expression of FBXO30 in the prokaryotic expression system can provide a base for the preparation of the specific antibody of FBXO30 and further functional study of FBXO30.

3T3 Cells↗
PubMed2001

Laparoscopic treatment of severe acute pancreatitis.

BACKGROUND: The appropriate surgical treatment for severe acute pancreatitis has been disputed for a long time. Herein we describe our experience with the laparoscopic treatment of this disease. METHODS: Ten patients, seven male and three female, with an average age of 55 years were diagnosed with severe acute pancreatitis. All cases but one were found to be without biliary stones by ultrasonic and CT scans. Laparoscopic exploration, irrigation, drainage, and decompression of the pancreas were performed. Further treatment, including gastric decompression, irrigation via the drainage tubes, antibiotics, somatostatin, and parenteral nutrition, was continued in all patients following the laparoscopic procedures. RESULTS: Nine patients recovered successfully; one died from adult respiratory distress syndrome (ARDS) soon after the operation. The hospital stay was 10-30 days. CONCLUSIONS: The laparoscopic era offers new hope for the treatment of severe acute pancreatitis. The technique can be used to determine the pathologic extent of the disease, to irrigate and drain the abdominal cavity, and to decompress the pancreas. Almost every surgical procedure for acute pancreatitis can be performed laparoscopically.

Acute Disease↗
PubMed2001

Extracellular matrix production of lens epithelial cells.

PURPOSE: To examine extracellular matrix (ECM) production of lens epithelial cells (LECs) and their regulation by cytokines. SETTING: Research Laboratory, International Intraocular Implant Training Center, Tianjin Medical University, People's Republic of China. METHODS: Bovine LECs were cultured with or without tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta2 (TGF-beta2). Immunohistochemistry and in situ hybridization were used to detect the expression of ECM. The slides were quantified by computer analysis. RESULTS: Laminin expression was increased by both TNF-alpha and TGF-beta2. The expression of type IV collagen at the mRNA level was upregulated by TNF-alpha and TGF-beta2. Its protein expression was promoted by only TNF-alpha. CONCLUSIONS: Type IV collagen and laminin are the main components of the lens capsule. Their production of LECs could be increased by cytokines derived from the aqueous humor or LECs. This may lead to ECM deposition and capsule fibrosis during the development of posterior capsule opacification.

Animals↗
PubMed2001

Estimation of atmospheric mixing heights using data from airport meteorological stations.

In this study, ground and sounding meteorological data at the Beijing Airport during 1991 to 1995 were used for estimating the local atmospheric mixing heights. Three methods were compared for this purpose, including the dry adiabatic method, the Nozaki model, and a modified Nozaki model. The modification of the Nozaki model included joint frequencies for wind-velocity and stability based on the complexities of local meteorological conditions. The estimated values from the three methods were verified through the data measured by the Beijing Meteorological Center. The results indicated that the dry adiabatic method has the best performance. The modified Nozaki model was better than the commonly used. This study is a new attempt in utilizing airport meteorological data to estimate atmospheric mixing heights.

Air Movements↗
PubMed2001

An improved method of hydrogen production as electron donor for anaerobic bioremediation.

This paper investigated an improved electrochemical approach that is able to provide hydrogen for anaerobic bioremediation of chloroethenes in subsurface. Hydrogen is the ultimate electron donor of biodechlorination processes. In experiments, iron wire was used as electrodes, an anaerobic bacteria enrichment collected from a site contaminated with chloroethenes as test microbes, perchloroethylene (PCE) as model chloroethene. Experiments were conducted by switching the polarities of electrodes periodically and supplying electrical power in an intermittent way. The results showed that an electrochemical bioreactor that was switched 1 time/10 min and operated only 8 h a day was able to produce more hydrogen than that operated 24h a day at 0.4V without polarity switching, stimulating microbial growth more effectively. The intermittent operation also resulted in periodical release of overpotentials that built up on electrode surfaces, thus prevented charged ions and particles from attaching on electrodes. The hydrogen produced was available for microbial growth and PCE dechlorination. It is suggested that the improved electrochemical process developed in this study has significant implications to anaerobic bioremediation.

Bacteria, Anaerobic↗
PubMed2001

Gender may affect the action of garlic oil on plasma cholesterol and glucose levels of normal subjects.

Early trials of garlic preparations on blood lipids mainly supported a lipid-lowering effect, whereas later well-designed garlic tablet trials were mainly entirely null. However, enteric simulation tests suggest that this discordance may result from ineffective delivery of bioactive agents from the brands of garlic powder (GP) and cyclodextrin-bound garlic oil (GO) tablets tested in some recent negative trials. In contrast, enteric simulation tests show that the preformed bioactive agents present in "traditional" gelatin capsules of GO are efficiently released, although such capsules have rarely been investigated in lipid-lowering trials. It was hypothesized that gelatin capsules of GO given to normal subjects would improve specified coronary heart disease risk factors. Effects of a GP preparation were also investigated. Subjects (n = 51; men and women, mean age 27 y) were randomly assigned to receive either 8.2 mg/d of GO (allyl sulfides) or placebo for 11 wk. Another 27 subjects received garlic powder (GP) of similar biopotential (7.8 mg allicin/d). Outcome measures were 95% confidence intervals (CI) between GO and placebo groups for differences between baseline and subsequent sample times. Men and women combined showed no significant differences save for an improved total antioxidant capacity at 6 wk (P = 0.01). Hence, no benefit from GO after 11 wk is one plausible conclusion. However, there were significant differences in effect of GO between men and women for HDL cholesterol (HDL-C) (P = 0.004) and total cholesterol (TC)/HDL-C (P = 0.003). Women showed favorable effects in terms of CHD risk factors (i.e., increases in HDL-C and reductions in TC/HDL-C), whereas men had small adverse effects. There was a significant difference in the GO effect for glucose (P = 0.006), with a reduction seen for men and an increase for women. The gender effects were unexpected and such analyses were not planned in advance. Confirmation of these findings with larger numbers of subjects would have importance for the use of garlic against CHD and for the design of future garlic studies.

Adult↗
PubMed2001

Effect of mycophenolate mofetil on nitric oxide production and inducible nitric oxide synthase gene expression during renal ischaemia-reperfusion injury.

BACKGROUND: Recent animal data suggest that inducible nitric oxide synthase (iNOS) derived nitric oxide (NO) plays an important role in the pathogenesis of renal ischaemia-reperfusion injury (IRI) and that inhibition of iNOS ameliorates IRI. Mycophenolate mofetil (MMF), a lymphocyte selective anti-proliferative agent, has been shown to inhibit NO production in vitro. The aim of this study is to evaluate the effect of MMF on NO production and iNOS gene expression in vivo during renal IRI. METHODS: Renal IRI was induced by clamping the left renal pedicle of male BALB/c mice for 30 min, followed by 15 min of reperfusion. The mice received placebo or MMF at 40, 80 or 120 mg/kg/day by oral gavage for 5 days before the operation. Sham-operated mice served as the operation control. The amount of NO produced and the level of iNOS gene expression in the kidney tissue during IRI was assessed by spin trapping electron paramagnetic resonance (EPR) spectroscopy and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) respectively. RESULTS: In the sham-operated kidneys, only low levels of NO and iNOS mRNA were detected. In mice with renal IRI, the amount of NO detected was significantly increased, which was reduced in a dose dependent fashion by pre-treatment with MMF. Pre-treatment with MMF also substantially reduced iNOS gene expression in the kidney tissue. CONCLUSIONS: We conclude that pre-treatment with MMF inhibits the production of NO and the induction of iNOS gene expression in the kidney during IRI. These results suggest that MMF might have the potential to ameliorate renal IRI.

Animals↗
PubMed2001

A randomized trial of the effects of garlic oil upon coronary heart disease risk factors in trained male runners.

Most trials of bulb garlic and garlic powder tablets indicate reduced coronary heart disease (CHD) risk in elevated-risk subjects. Most persons taking garlic supplements lack overt risk of CHD. However, no trials have tested steam-distilled garlic oil (GO) capsules with healthy subjects. The objectives of the present randomized, double-blind, placebo-controlled study were to determine whether GO capsules reduce CHD risk in trained male runners. Twenty-seven volunteers (mean age, 28.8 years) completed the study. Each took 12.3 mg/day GO (or placebo) capsules for 16 weeks. Main outcome measures were 95% confidence intervals (CIs) between GO and placebo groups for differences in changes of blood pressure (BP), plasma lipids, total antioxidant status (TAS), low-density lipoprotein (LDL) composition and blood clotting factors. Principal results as mean differences (95% CI) between GO and placebo are: pulse, 2.9 beats/min (-0.8 to 6.7), P = 0.12; systolic BP, -4.5 mmHg (-10.8 to 1.9), P = 0.16; plasma total cholesterol, 0.01 mmol/l (-0.34 to 0.37), P = 0.95; plasma triglycerides, -0.20 mmol/l (-0.43 to 0.03), P = 0.09; plasma TAS, 45 micromol Trolox equivalent/l (-35 to 124), P = 0.26; LDL density, 0.0019 g/ml (-0.0005 to 0.0043), P = 0.12; LDL triglycerides/protein, -0.078 mg/mg (-0.149 to -0.007), P = 0.03; LDL cholesterol/protein, -0.24 mg/mg (-0.69 to 0.22), P = 0.3; LDL TAS/triglycerides, 29 nmol/mg (11, 68), P = 0.15; prothrombin time, 0.99 s (-0.36 to 2.35), P = 0.14; partial thromboplastin time, 3.0 s (-1.0 to 7.1), P = 0.13. Results were null statistically. Trends with GO were mostly towards lower CHD risk, and a larger study (approximately 150 subjects) is required to test their validity.

Adolescent↗
PubMed2001

Targeting a nuclear anthranilate synthase alpha-subunit gene to the tobacco plastid genome results in enhanced tryptophan biosynthesis. Return of a gene to its pre-endosymbiotic origin.

Anthranilate synthase (AS), the control enzyme of the tryptophan (Trp) biosynthetic pathway, is encoded by nuclear genes, but is transported into the plastids. A tobacco (Nicotiana tabacum) cDNA (ASA2) encoding a feedback-insensitive tobacco AS alpha-subunit was transformed into two different sites of the tobacco plastid genome through site-specific insertion to obtain transplastomic plants with normal phenotype and fertility. A high and uniform level of ASA2 mRNA was observed in the transplastomic plants but not in the wild type. Although the plants with the transgene insertion at ndhF-trnL only expressed one size of the ASA2 mRNA, the plants with the transgene incorporated into the region between accD and open reading frame (ORF) 184 exhibited two species of mRNA, apparently due to readthrough. The transplastomic plants exhibited a higher level of AS alpha-subunit protein and AS enzyme activity that was less sensitive to Trp-feedback inhibition, leading to greatly increased free Trp levels in leaves and total Trp levels in seeds. Resistance to an AS inhibitor, 5-methyl-Trp, was found during seed germination and in suspension cultures of the transplastomic plants. The resistance to the selection agent spectinomycin and to 5-methyl-Trp was transmitted maternally. These results demonstrate the feasibility of modifying the biosynthetic pathways of important metabolites through transformation of the plastid genome by relocating a native gene from the nucleus to the plastid genome. Very high and uniform levels of gene expression can be observed in different lines, probably due to the identical insertion sites, in contrast to nuclear transformation where random insertions occur.

Anthranilate Synthase↗