Biomedical subjects

Wei Zhang

Publications and source records attributed to Wei Zhang.

At least 235 records · Page 13Linked to original sources

PubMed2006

Chromosomal abnormality and Y chromosome microdeletion in Chinese patients with azoospermia or severe oligozoospermia.

Chromosomal abnormality and Y chromosome microdeletion are regarded as two frequent genetic causes associated with spermatogenic failure in Caucasian population. To investigate the distribution of the two genetic defects in Chinese patients with azoospermia or severe oligozoospermia, karyotype analysis by G-banding was carried out in 358 idiopathic infertile men, including 256 patients with azoospermia and 102 patients with severe oligozoospermia, and screening of AZF region microdeletion of Y chromosome by multiplex PCR was performed in those patients without detectable chromosomal abnormality and 100 fertile controls. Of 358 patients, 39(10.9%) were found to have chromosomal abnormalities in which Klinefelter's syndrome (47, XXY) was the most common chromosomal aberration. The incidence of sex chromosomal abnormality in patients with azoospermia was significantly higher than that in patients with severe oligozoospermia (12.1% vs 1%). Among the rest of the 319 patients with normal karyotype, 46 (14.4%) were found to have microdeletions in AZF region. The prevalence rates of AZF microdeletion was 15% and 13.1% in patients with azoospermia and severe oligozoospermia respectively. The microdeletion in AZFc was the most frequent deletion and all the microdeletions in AZFa were found in azoospermic patients. No microdeletion in AZF region was detected in fertile controls. In conclusion, chromosomal abnormality and AZF region microdeletion of Y chromosome might account for about 25% of Chinese infertile patients with azoospermia or severe oligozoospermia, suggesting the two abnormalities are important genetic etiology of spermatogenic failure in Chinese population and it is essential to screen them during diagnosis of male infertility before in vitro assisted fertilization by introcytoplasmic sperm injection.

Adult↗

PubMed2006

Screening and applying wheat microsatellite markers to trace individual Haynaldia villosa chromosomes.

Wheat (Triticum aestivum L.) microsatellite markers were screened for detecting Haynaldia villosa L. chromosomes introduced into wheat background. Two hundred and seventy six primer pairs mapped on 7 homeologous groups of wheat were used to amplify the gDNA of T. aestivum and H. villosa. The results showed that 148 of 276 microsatellite primers amplified polymorphic bands between common wheat cv. Chinese Spring and H. villosa. Primers wmc49 (1BS), wmc25 (2BS), gdm36 (3DS), gdm145 (4AL), wmc233 (5DS), wmc256 (6AL) and gwm344 (7BL) produced a specific polymorphic DNA fragment on chromosome 1V to 7V of H. villosa, respectively. In addition, gwm469 (6DS) detected a specific band on 2V; gdm107 (2DS) amplified a specific band on 6V. These microsatellite markers were effective in identifying individual H. villosa chromosomes in other T. aestivum-H. villosa chromosome addition, substitution and translocation lines involved in different H. villosa accessions and wheat backgrounds. Therefore, these chromosome-specific microsatellite markers could be used as molecular markers for detection of chromosomes of H. villosa in common wheat.

Agropyron↗

PubMed2006

[Effect of homogeneity on cell growth and anthocyanin biosynthesis in suspension cultures of Vitis vinifera].

The instability of secondary metabolite production is a ubiquitous problem in plant cell culture. To understand the instability, the investigation of anthocyanin accumulation in suspension cultures of Vitis vinifera, as a model system, has been initiated in our laboratory. Suspension culture of a relatively homogeneous cell line E of V. vinifera, was established by long-term cell line selection by anthocyanin content differentiation. The aggregate size of E was smaller than that of other cell lines obtained by routine screening method. The variation coefficients of anthocyanin content in suspension cultures of E were 8.7% in long-term subcultures and 5% in repeated flasks, respectively. The effects of elicitor, precursor feeding and light irridiation on biomass and anthocyanin accumulation in suspension cultures of E had been investigated and the results showed that all the variation coefficients were lower than 12% and this indicated the importance of homogeneity on stable production in plant cell culture. With the combination treatment of 30micromol/L phenylalanine and 218micromol/L methyl jasmonate in the dark in suspension cultures of E, the anthocyanin content and production in suspension culture of E was 5.89-fold and 4.30-fold of the controls, respectively, and all the variation coefficients of biomass and anthocyanin accumulation were lower than those of the controls in 5 successive subcultures.

Anthocyanins↗

PubMed2006

[Impact of subculture cycles and inoculum sizes on suspension cultures of Vitis vinifera].

The commercial application of plant cell cultures is often hindered by the instability of secondary metabolite biosynthesis, where the metabolite yield fluctuates and decline dramatically over subcultures. This study proposed that such instability is due to the fluctuations of culture variables. To validate this hypothesis, the effects of the fluctuations of two culture variables (subculture cycle and inoculum size) on the biomass, anthocyanin biosynthesig, intracellular carbon, nitrogen and phosphate during continuous 10 subculture cycles were investigated. The subculture cycle was fluctuated for 12h in a 7 day cycle (6.5, 7 and 7.5 d), and the inoculum size was fluctuated by 20% on basis of 2.00 g (1.60, 2.00 and 2.40 g). It was found that all the measured culture parameters fluctuated over the 10 subculture cycles. The fluctuation in terms of inoculum sizes had a greater effect on the stability of anthocyanin biosynthesis in suspension cultures of V. vinifera. Among all the subculture conditions investigated, 7d-subculture cycle and 1.60 g-inoculum size was the best one to hold the relatively stable anthocyanin production. The anthocyanin yield presented a negative correlation with intracellular sucrose content or intracellular total phosphate content.

Anthocyanins↗

PubMed2006

Recent advances in the understanding and treatment of anxiety disorders. Resilience: determinants, measurement, and treatment responsiveness.

In human terms, resilience is an ability to cope with stress and varies with context, time, age, gender, and cultural origin. Resilience shifts the focus of psychological investigation onto increasing the positive rather than reducing the negative. Inquiry into resilience has evolved from descriptions of resilient qualities, to discovery of the process to attain resilience, to uncovering the motivation to reintegrate in a resilient manner. Much of the research on resilience has focused on children in settings such as family violence, extreme poverty, war, and natural disasters. A coherent pattern of characteristics associated with successful adaptation has emerged. Salient characteristics include commitment, dynamism, humor in the face of adversity, patience, optimism, faith, and altruism. As such, resilience may represent an important target of treatment in anxiety, depression, and stress reactions. Resilience can be quantified, but available measures need to be validated transculturally. There exist many possible determinants of resilience, including neurobiologic, genetic, temperament, and environmental influences. Resilience is modifiable on individual and cultural levels. Posttraumatic stress disorder is an example of a serious disorder associated with impaired stress coping that can improve with treatment.

Adaptation, Psychological↗

PubMed2006

Temperature-activated interfacial friction damping in carbon nanotube polymer composites.

Effect of temperature on interfacial sliding in single-walled carbon nanotube polycarbonate composites is investigated experimentally. We show that interfacial slip at the tube-polymer interfaces can be activated at relatively low dynamic strain levels ( approximately 0.35%) by raising temperature to approximately 90 degrees C. We attribute this to increased mobility of the polymer chain backbones at elevated temperatures and thermal relaxation of the radial compressive stresses at the tube-polymer interfaces. These results show the potential of polymer nanocomposites as high-temperature damping materials for vibration and acoustic suppression in a variety of dynamic systems.

Motion↗

PubMed2006

Thermooptical properties of gold nanoparticles embedded in ice: characterization of heat generation and melting.

We investigate the system of optically excited gold NPs in an ice matrix aiming to understand heat generation and melting processes at the nanoscale level. Along with the traditional fluorescence method, we introduce thermooptical spectroscopy based on phase transformation of a matrix. With this, we can not only measure optical response but also thermal response, that is, heat generation. After several recrystallization cycles, the nanoparticles are embedded into the ice film where the optical and thermal properties of the nanoparticles are probed. Spatial fluorescence mapping shows the locations of Au nanoparticles, whereas the time-resolved Raman signal of ice reveals the melting process. From the time-dependent Raman signals, we determine the critical light intensities at which the laser beam is able to melt ice around the nanoparticles. The melting intensity depends strongly on temperature and position. The position-dependence is especially strong and reflects a mesoscopic character of heat generation. We think that it comes from the fact that nanoparticles form small complexes of different geometry and each complex has a unique thermal response. Theoretical calculations and experimental data are combined to make a quantitative measure of the amount of heat generated by optically excited Au nanoparticles and agglomerates. The information obtained in this study can be used to design nanoscale heaters and actuators.

Gold↗

PubMed2006

Air cushion press for excellent uniformity, high yield, and fast nanoimprint across a 100 mm field.

Imprint pressure uniformity is crucial to the pattern uniformity and yield of nanoimprint lithography (NIL) and, hence, its applications. We studied a novel imprint method, air cushion press (ACP), in which the mold and substrate are pressed against each other by gas pressure rather than solid plates, and compared it with a common method, solid parallel-plate press (SPP). We found that (a) under normal imprinting conditions the measured pressure distribution across a 100-mm-diameter single imprint field in ACP is nearly an order of magnitude more uniform; (b) ACP is immune to any dust and topology variations on the backside of the mold or substrate; (c) when a dust particle is between the mold and substrate, ACP reduces the damage area by orders of magnitude; (d) ACP causes much less mold damage because of significantly less lateral shift between the mold and substrate; and (e) ACP has much smaller thermal mass and therefore significantly faster speed for thermal imprinting.

Air Pressure↗

PubMed2006

Antioxidant N-acetylcysteine restores systemic nitric oxide availability and corrects depressions in arterial blood pressure and heart rate in diabetic rats.

Increased oxidative stress and reduced nitric oxide (NO) bioactivity are key features of diabetes mellitus that eventually result in cardiovascular abnormalities. We assessed whether N-acetylcysteine (NAC), an antioxidant and glutathione precursor, could prevent the hyperglycaemia induced increase in oxidative stress, restore NO availability and prevent depression of arterial blood pressure and heart rate in vivo in experimental diabetes. Control (C) and streptozotocin-induced diabetic (D) rats were treated or not treated with NAC in drinking water for 8 weeks, initiated 1 week after induction of diabetes. At termination, plasma levels of free 15-F2t-isoprostane, a specific marker of oxygen free radical induced lipid peroxidation, was increased while the plasma total antioxidant concentration was decreased in untreated diabetic rats as compared to control rats (P<0.05). This was accompanied by a significant reduction of plasma levels of nitrate and nitrite, stable metabolites of NO, (P<0.05, D vs. C) and a reduced endothelial NO synthase protein expression in the heart and in aortic and mesenteric artery tissues. Systolic, diastolic and mean arterial blood pressures (SBP, DBP and MAP) and heart rate (HR) were reduced in diabetic rats (P<0.05 vs. C) and NAC normalised the changes that occurred in the diabetic rats. The protective effects may be attributable to restoration of NO bioavailability in the circulation.

Acetylcysteine↗

PubMed2006

Characterization of frequently deleted 6q locus in prostate cancer.

The long arm of chromosome 6 is frequently deleted in diverse human neoplasms. Our previous study showed a minimum deletion region between markers D6S1056 and D6S300 on chromosome 6q in primary prostate cancer (CaP). In this study, we further refined a 200-kb minimal region of deletion (6qTSG1) centered around D6S1013 marker. The 6qTSG1 transcripts contained complex multiple splicing variants with low or absent expression in CaP cells. None of the transcripts identified contained open reading frames that code for a protein in the NCBI database. The expression of 6qTSG transcripts revealed interesting hormonal regulation relevant to CaP biology. Expression of 6q TSG transcript was induced in LNCaP cells that were cultured in charcoal-stripped serum medium suggesting an upregulation of 6qTSG transcript by androgen ablation and cell growth inhibition/apoptosis. Induction of 6qTSG1 expression in response to androgen ablation was abrogated in androgen-independent derivatives of LNCaP cells. In summary, we have defined a candidate CaP suppressor locus on chromosome 6q16.1, and deletions of this locus are frequently associated with prostate tumorigenesis. In the light of emerging role of noncoding RNAs in cancer biology including CaP, future investigations of 6qTSG11 locus is warranted.

Apoptosis↗

PubMed2006

Preparation of tissue-specific monoclonal antibodies using purified endothelial membrane proteins from biotinylated pulmonary vasculature of rhesus monkey.

In the present study, we perfused the rhesus lung vascular bed in situ with sulfo-NHS-LC-Biotin to biotinylate its luminal surface membrane proteins. After homogenization, dialysis, and affinity chromatography, biotinylated endothelial membrane proteins were successfully isolated and characterized as enriched endothelial membrane proteins with no contamination of intracellular proteins. When they were used as immunogens to develop monoclonal antibodies (MAbs), three MAbs--TX111, TX112, and TX113--were obtained. Among them, TX111 was demonstrated to specifically bind to rhesus lung tissue by Western blotting and enzymelinked immunosorbent assay (ELISA)--that is, positively stained capillary endothelium of rhesus lung. The molecular weight of the corresponding antigen for TX111 was approximately 70 kDa under reducing conditions. TX111 also reacted with human lung homogenate, but not with rat lung homogenate. These results suggest that (1) the biotinylation method is applicable for isolating endothelial proteins in situ from large animals; (2) anti-human protein MAbs are likely to be obtained using monkey proteins; and (3) TX111 is potentially useful for pulmonary vascular targeting.

Animals↗

PubMed2006

A novel gene of beta chain of the IFN-gamma receptor of Huiyang chicken: cloning, distribution, and CD assay.

The beta chain of the interferon-gamma receptor (IFNGR-2) plays a critical role in signal transmission to the nucleus by IFN-gamma. Here, we cloned the full-length cDNA of IFNGR-2 of Huiyang chicken using RACE. mRNA transcripts of IFNGR-2 were detected in peripheral blood leukocytes (PBL) and various organs using Northern blot analysis. The extracellular region of IFNGR-2 (IFNGR-2EC) was expressed in Pichia pastoris, and its secondary structure was investigated by circular dichroism (CD). The Huiyang chicken IFNGR-2 gene is 2221 bp with a polyA+ tail, and it encodes 334 amino acids sharing 30%-33% identity with that of rat, mouse, and human IFNGR-2. IFNGR-2 is localized on chromosome 1 of chicken in tandem with IFNAR-1, interleukin- 10 receptor (IL-10R-2), and IFNAR-2. IFNGR-2 was highly expressed in PBL, muscle, spleen, thymus, and cecal tonsil, whereas its expression in cardiac muscle, cloacal bursa, liver, and kidney was comparatively low. Recombinant protein of IFNGR-2EC expressed in P. pastoris formed the secondary structure including 19.8% alpha-helix, 29.6% beta-sheet, 19.7% turn, and 30.9% random. The data show that Huiyang chicken IFNGR-2 shares properties of the IFN receptor family in gene structure and distribution in multiple tissues and PBL. CD analysis indicated that the recombinant protein of IFNGR-2EC resembles the known structure of human IFN receptors.

Animals↗

PubMed2006

Genistein decreases food intake, body weight, and fat pad weight and causes adipose tissue apoptosis in ovariectomized female mice.

Genistein, an isoflavone in soybean products, has estrogenic activity and is used as a natural substitute for estrogen replacement therapy in postmenopausal women. Genistein was also shown to decrease fat pad weight in female mice. The primary objective of this study was to determine the effect of genistein on adipose tissue apoptosis in vitro and in vivo. 3T3-L1 preadipocytes and mature adipocytes were treated with 0, 1, 10, 100, and 400 micromol/L genistein and then assayed for apoptosis, whereas only mature adipocytes were assayed for viability. Mature adipocytes treated with genistein demonstrated a dose-related increase in apoptosis. Ovariectomized female mice (9 mo old) were given 0, 150, or 1,500 mg/kg genistein in the semipurified phytoestrogen-free casein-based diet for 3 wk (n=10). After mice were killed, body composition was determined by dual-energy X-ray absorptiometry analysis, and parametrial (PM), inguinal (ING), and retroperitoneal (RP) fat pads were weighed and assayed for apoptosis (% DNA fragmentation). Genistein (1500 mg/kg) reduced food intake (FI) by 14% (P<0.01) and body weight (BW) by 9% (P<0.01). Body composition was not significantly affected, but PM and ING weights were decreased 22% (P<0.05) and 19% (P<0.07), respectively, by 1,500 mg/kg genistein. Apoptosis in ING fat was increased 290% (P<0.05) by 1,500 mg/kg genistein. These findings show that oral genistein treatment can reduce BW, mobilize body fat, and induce apoptosis of adipose tissue in ovariectomized female mice. Thus, genistein may be useful in treating or preventing increased adiposity after menopause.

Adipose Tissue↗

PubMed2006

Reactive microgliosis participates in MPP+-induced dopaminergic neurodegeneration: role of 67 kDa laminin receptor.

It has been reported that extracellular matrix (ECM) molecules regulate monocyte activation by binding with a 67 kDa nonintegrin laminin receptor (LR). As microgliosis is a pivotal factor in propelling the progress of chronic neurodegeneration in the brain, we hypothesized that LR may regulate the microgliosis and subsequent neurotoxicity. Using 1-methyl-4-phenylpyridinium (MPP+) -treated C57 mice primary mesencephalic neuron-glia cultures as an in vitro Parkinson's disease (PD) model, we observed that MPP+ treatment increased LR expression only in the mixed neuron-glia but not in microglia-enriched or microglia-depleted cultures, indicating that MPP+-induced increase of LR expression is associated with neuron-microglia interaction. Using confocal microscopic examination, we found that LR was localized in the microglia, which were F4/80 positive. Treatment with the antibody (Ab) against LR (LR-Ab) or YIGSR, a synthetic pentapeptide inhibitor for LR, significantly attenuated the MPP+-increased F4/80 immunoreactivity (24 h) and dopaminergic (DA) neurotoxicity. LR-Ab also attenuated MPP+-increased microglial phagocytotic activity (48 h) and the superoxide production (4 days). Further study demonstrated that exogenous laminin (1-10 microg/ml) treatment induced microglial activation and DA neurotoxicity, in a dose-dependent manner, which was partially attenuated by the LR-Ab. We concluded that by regulating cell-ECM interaction, LR plays important roles in mediating microgliosis and subsequent DA neurotoxicity. Laminin is a potential ligand for activating this LR receptor. This study also suggests that laminin/LR is a potential target for developing new therapeutic drugs against neurodegenerative disorders such as PD.

1-Methyl-4-phenylpyridinium↗

PubMed2006

3-Hydroxymorphinan, a metabolite of dextromethorphan, protects nigrostriatal pathway against MPTP-elicited damage both in vivo and in vitro.

We investigated the neuroprotective property of analogs of dextromethorphan (DM) in lipopolysaccharide (LPS) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models to identify neuroprotective drugs for Parkinson's disease (PD). In vivo studies showed that daily injections with DM analogs protected dopamine (DA) neurons in substantia nigra pars compacta and restored DA levels in striatum using two different models for PD. Of the five analogs studied, 3-hydroxymorphinan (3-HM), a metabolite of DM, was the most potent, and restored DA neuronal loss and DA depletion up to 90% of the controls. Behavioral studies showed an excellent correlation between potency for preventing toxin-induced decrease in motor activities and neuroprotective effects among the DM analogs studied, of which 3-HM was the most potent in attenuating behavioral damage. In vitro studies revealed two glia-dependent mechanisms for the neuroprotection by 3-HM. First, astroglia mediated the 3-HM-induced neurotrophic effect by increasing the gene expression of neurotrophic factors, which was associated with the increased acetylation of histone H3. Second, microglia participated in 3-HM-mediated neuroprotection by reducing MPTP-elicited reactive microgliosis as evidenced by the decreased production of reactive oxygen species. In summary, we show the potent neuroprotection by 3-HM in LPS and MPTP PD models investigated. With its high efficacy and low toxicity, 3-HM may be a novel therapy for PD.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed2006

Bupropion treatment of olanzapine-associated weight gain: an open-label, prospective trial.

OBJECTIVE: To examine the effectiveness of bupropion in reducing bodyweight gained during treatment with olanzapine. METHODS: Eight subjects, who received olanzapine for an average duration of 26 months and had gained an average of 13.3 kg bodyweight, participated in a 24-week study in which they received open-label bupropion 150-300 mg/d while continuing olanzapine. The subjects were also provided low-key nutritional counseling. Change in bodyweight was the primary outcome of interest. Changes in fasting blood glucose and lipids were also examined in addition to changes in body composition and bone mineral density. RESULTS: Seven subjects completed the full 24-week study treatment. In the intent-to-treat sample, mean [SE] bodyweight decreased significantly over time (99.6 [5.9] kg to 96.2 [5.8] kg; F = 4.0; P < 0.001); average weight change for the eight subjects was -3.4 kg. Four of eight subjects lost > or =3% bodyweight. There was a significant reduction in total cholesterol. Weight loss did not have a negative effect on bone mineral density. Side effects were generally mild. CONCLUSION: Bupropion combined with a low-key dietary intervention appeared to be beneficial in reducing olanzapine-associated weight gain in some subjects in this open-label study.

Adult↗

PubMed2006

Modafinil for atypical depression: effects of open-label and double-blind discontinuation treatment.

Atypical depression, with features of hypersomnia, hyperphagia, anergia, and rejection sensitivity, is a common presentation of major depressive disorder. There are few available effective therapies for this disorder. We test modafinil, a novel wake-promoting agent, as monotherapy for atypical depression in a double-blind, placebo-controlled, relapse prevention trial after open-label treatment. We found that modafinil significantly improved atypical depression symptoms during 12 weeks of open-label treatment (mean +/- SD Hamilton Depression Scale (29-item version) score changed from 34 +/- 8.2 at baseline to 9.7 +/- 9.3, P < 0.0001), and that benefits were maintained alike in both the continuation and placebo arms during the double-blind treatment phase (P = 0.92). Modafinil was well tolerated and the drug was associated with significant weight loss compared with placebo (P = 0.01).

Adult↗

PubMed2006

Actinoalloteichus hymeniacidonis sp. nov., an actinomycete isolated from the marine sponge Hymeniacidon perleve.

A polyphasic study was undertaken to establish the taxonomic status of a Gram-positive, aerobic actinomycete, strain HPA177(T), isolated from a marine sponge, Hymeniacidon perleve. The organism formed branching, non-fragmenting vegetative hyphae and produced black pigment. Chemotaxonomic characteristics were consistent with its assignment to the genus Actinoalloteichus. Analysis of the 16S rRNA gene sequence showed that strain HPA177(T) formed a robust clade with type strains of the genus Actinoalloteichus, but was distinct from them. A number of phenotypic characteristics also readily distinguished strain HPA177(T) from species of the genus Actinoalloteichus with validly published names. On the basis of the above data, it is proposed that strain HPA177(T) represents a novel species, Actinoalloteichus hymeniacidonis sp. nov. The type strain of Actinoalloteichus hymeniacidonis is HPA177(T) (=CGMCC 4.2500(T)=JCM 13436(T)).

Actinomycetales↗