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Biomedical subjects

G Zhang

Publications and source records attributed to G Zhang.

At least 127 records · Page 7Linked to original sources
PubMed2001

Death following cupric sulfate emesis.

CASE HISTORY: A 25-year-old woman who had ingested about 20 tablets of diazepam 2.5 mg in a suicide attempt was given cupric sulfate 2.5 g in 1750 mL water as an emetic, but died 3 days later. On autopsy, death was attributed to acute hemolysis and acute renal failure due to copper poisoning. Copper concentrations were 5.31 microg/mL in whole blood, 19.0 microg/g in the liver, 8.9 microg/g in the kidney, 1.1 microg/L in the brain, 1.1 microg/g in the gastric wall, 1.5 microg/g in the jejunal wall, 0.3 microg/g in the colon wall, 4.6 microg/g in the gastric contents, and 12.6 microg/g in the intestinal contents (fresh weight). This case and 10 others from the Chinese medical literature provide additional evidence that cupric sulfate is a corrosive poison and contraindicated as an emetic.

Adult↗
PubMed2001

Amphetamine, 3,4-methylenedioxymethamphetamine, lysergic acid diethylamide, and metabolites of the catecholamine neurotransmitters are agonists of a rat trace amine receptor.

The trace amine para-tyramine is structurally and functionally related to the amphetamines and the biogenic amine neurotransmitters. It is currently thought that the biological activities elicited by trace amines such as p-tyramine and the psychostimulant amphetamines are manifestations of their ability to inhibit the clearance of extracellular transmitter and/or stimulate the efflux of transmitter from intracellular stores. Here we report the discovery and pharmacological characterization of a rat G protein-coupled receptor that stimulates the production of cAMP when exposed to the trace amines p-tyramine, beta-phenethylamine, tryptamine, and octopamine. An extensive pharmacological survey revealed that psychostimulant and hallucinogenic amphetamines, numerous ergoline derivatives, adrenergic ligands, and 3-methylated metabolites of the catecholamine neurotransmitters are also good agonists at the rat trace amine receptor 1 (rTAR1). These results suggest that the trace amines and catecholamine metabolites may serve as the endogenous ligands of a novel intercellular signaling system found widely throughout the vertebrate brain and periphery. Furthermore, the discovery that amphetamines, including 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy"), are potent rTAR1 agonists suggests that the effects of these widely used drugs may be mediated in part by this receptor as well as their previously characterized targets, the neurotransmitter transporter proteins.

Amino Acid Sequence↗
PubMed2001

Borna disease virus phosphoprotein binds a neurite outgrowth factor, amphoterin/HMG-1.

The Borna disease virus (BDV) p24 phosphoprotein is an abundant protein in BDV-infected cultured cells and animal brains. Therefore, there is a possibility that binding of the p24 protein to cellular factor(s) induces functional alterations of infected neural cells in the brain. To identify a cellular protein(s) that interacts with BDV p24 protein, we performed far-Western blotting with extracts from various cell lines. Using recombinant p24 protein as a probe, we detected a 30-kDa protein in all cell lines examined. Binding between the 30-kDa and BDV p24 proteins was also demonstrated using BDV p24 affinity and ion-exchange chromatography columns. Microsequence analysis of the purified 30-kDa protein revealed that its N terminus showed complete homology with rat amphoterin protein, which is a neurite outgrowth factor abundant in the brain during development. Mammalian two-hybrid and immunoprecipitation analyses also confirmed that amphoterin is a specific target for the p24 protein in vivo. Furthermore, we showed that infection by BDV, as well as purified p24 protein in the medium, significantly decreased cell process outgrowth of cells grown on laminin, indicating the functional inhibition of amphoterin by interaction with the p24 protein. Immunohistochemical analysis revealed decreased levels of amphoterin protein at the leading edges of BDV-infected cells. Moreover, the expression of the receptor for advanced glycation end products, of which the extracellular moiety is a receptor for amphoterin, was not significantly activated in BDV-infected cells during the process of extension, suggesting that the secretion of amphoterin from the cell surface is inhibited by the binding of the p24 protein. These results suggested that BDV infection may cause direct damage in the developing brain by inhibiting the function of amphoterin due to binding by the p24 phosphoprotein.

Animals↗
PubMed2001

Borna disease virus nucleoprotein requires both nuclear localization and export activities for viral nucleocytoplasmic shuttling.

Nuclear transport of viral nucleic acids is crucial to the life cycle of many viruses. Borna disease virus (BDV) belongs to the order Mononegavirales and replicates its RNA genome in the nucleus. Previous studies have suggested that BDV nucleoprotein (N) and phosphoprotein (P) have important functions in the nuclear import of the viral ribonucleoprotein (RNP) complexes via their nuclear targeting activity. Here, we showed that BDV N has cytoplasmic localization activity, which is mediated by a nuclear export signal (NES) within the sequence. Our analysis using deletion and substitution mutants of N revealed that NES of BDV N consists of a canonical leucine-rich motif and that the nuclear export activity of the protein is mediated through the chromosome region maintenance protein-dependent pathway. Interspecies heterokaryon assay indicated that BDV N shuttles between the nucleus and cytoplasm as a nucleocytoplasmic shuttling protein. Furthermore, interestingly, the NES region overlaps a binding site to the BDV P protein, and nuclear export of a 38-kDa form of BDV N is prevented by coexpression of P. These results suggested that BDV N has two contrary activities, nuclear localization and export activity, and plays a critical role in the nucleocytoplasmic transport of BDV RNP by interaction with other viral proteins.

Amino Acid Sequence↗
PubMed2001

EEG source localization: comparative study of classical and neural network methods.

We address the problem of estimating biopotential sources within the brain, based on EEG signals observed on the scalp. This problem, known as the inverse problem of electrophysiology, has no closed-form solution, and requires iterative techniques such as the Levenberg-Marquardt (LM) algorithm. Considering the nonlinear nature of the inverse problem, and the low signal to noise ratio inherent in EEG signals, a backpropagation neural network (BPN) has been recently proposed as a solution. The technique has not been properly compared with classical techniques such as the LM method, or with more recent neural network techniques such as the Radial Basis Function (RBF) network. In this paper, we provide improved strategies based on BPN and consider RBF networks in solving the inverse problem. We compare the performances of BPN, RBF and a hybrid technique with that of the classical LM method.

Brain↗
PubMed2001

Changes of serum selenium in pregnant women with gestational diabetes mellitus.

Gestational diabetes is one of the most common diseases in pregnancy. In the present work, the possible relationship between serum selenium concentration and gestational diabetes was investigated. Blood samples of 234 pregnant women were collected, including 98 subjects with impaired glucose tolerance (IGT), 46 subjects with gestational diabetes mellitus (GDM), and 90 normal pregnant women (NPW). An additional 17 samples of normal women of fertile age (NW) were collected for comparison. The hydride generation atomic fluorescence spectrometry was used for selenium determination. The mean serum selenium levels obtained for each group were 0.0741 +/- 0.0167 mg/L for NPW, 0.0631 +/- 0.0132 mg/L for IGT, 0.0635 +/- 0.0120 mg/L for GDM, and 0.108 +/- 0.0170 mg/L for NW. Serum selenium levels were significantly lower in pregnant woman with IGT (p < 0.001) and GDM (p < 0.001) than in NPW. Furthermore, an inverse correlation between the serum selenium concentration and the gestational period was also observed. Selenium supplementation during gestation for pregnant women, especially with IGT and GDM, should be considered.

Adult↗
PubMed2001

Specific localization of lysosomal aminopeptidases in type II alveolar epithelial cells of the rat lung.

We previously demonstrated that lysosomal cysteine proteinases, cathepsins B, H, and L were localized in lysosomes of alveolar macrophages and bronchial epithelial cells in the rat lung, while cathepsin H, a typical aminopeptidase, was additionally distributed in lamellar bodies containing surfactant in type II alveolar epithelial cells (ISHII et al., 1991). The present immunohistochemical study further examined the localization of lysosomal aminopeptidases, cathepsin C, and tripeptidyl peptidase I (TPP-I) in the rat lung. Western blotting confirmed the presence of cathepsin C and TPP-I as active forms in the pulmonary tissue, showing 25 kD and 47 kD, respectively. Immunohisto/cytochemical observations demonstrated that positive staining for cathepsin C and TPP-I was more intensely localized in alveolar epithelial regions than in bronchial or bronchiolar epithelial cells. By double immunostaining using confocal laser microscopy, immunoreactivity for cathepsin H was found to be co-localized with that for cathepsin C or TPP-I in both type II cells and macrophages. Moreover, when doubly stained with anti-cathepsin C and ED2, single-positive type II cells could be clearly distinguished from double-positive macrophages in the alveolar region. Immunoelectron microscopy revealed the gold labeling of cathepsin C or TPP-I in multivesicular and composite bodies, and lamellar bodies of Type II cells. These results showing that lysosomal aminopeptidases such as cathepsin H, cathepsin C and TPP-I are localized in lamellar bodies of type II alveolar epithelial cells strongly argue for the participation of lysosomal aminopeptidases in the formation process of surfactant containing specific proteins.

Aminopeptidases↗
PubMed2001

Signal transduction in electrically stimulated bone cells.

BACKGROUND: Electrical stimulation is used to treat nonunions and to augment spinal fusions. We studied the biochemical pathways that are activated in signal transduction when various types of electrical stimulation are applied to bone cells. METHODS: Cultured MC3T3-E1 bone cells were exposed to capacitive coupling, inductive coupling, or combined electromagnetic fields at appropriate field strengths for thirty minutes and for two, six, and twenty-four hours. The DNA content of each dish was determined. Other cultures of MC3T3-E1 bone cells were exposed to capacitive coupling, inductive coupling, or combined electromagnetic fields for two hours in the presence of various inhibitors of signal transduction, with or without electrical stimulation, and the DNA content of each dish was determined. RESULTS: All three signals produced a significant increase in DNA content per dish compared with that in the controls at all time-points (p < 0.05), but only exposure to capacitive coupling resulted in a significant, ever-increasing DNA production at each time-period beyond thirty minutes. The use of specific metabolic inhibitors indicated that, with capacitive coupling, signal transduction was by means of influx of Ca(2+) through voltage-gated calcium channels leading to an increase in cytosolic Ca(2+) (blocked by verapamil), cytoskeletal calmodulin (blocked by W-7), and prostaglandin E2 (blocked by indomethacin). With inductive coupling and combined electromagnetic fields, signal transduction was by means of intracellular release of Ca(2+) leading to an increase in cytosolic Ca(2+) (blocked by TMB-8) and an increase in activated cytoskeletal calmodulin (blocked by W-7). CONCLUSIONS: The initial events in signal transduction were found to be different when capacitive coupling was compared with inductive coupling and with combined electromagnetic fields; the initial event with capacitive coupling is Ca(2+) ion translocation through cell-membrane voltage-gated calcium channels, whereas the initial event with inductive coupling and with combined electromagnetic fields is the release of Ca(2+) from intracellular stores. The final pathway, however, is the same for all three signals-that is, there is an increase in cytosolic Ca(2+) and an increase in activated cytoskeletal calmodulin.

Animals↗
PubMed2001

[Mutation characteristic of STK].

OBJECTIVE: To identify the mutation characteristic of STK(11) gene in Chinese with Peutz-Jeghers syndrome(PJS) and establish the base of the gene diagnosis of PJS. METHODS: STK(11) germline mutation was analysed by DNA sequencing in 18 unrelation patients with PJS. RESULTS: Six novel mutations of STK (11) gene were detected in six unrelation patients. These mutations will lead to production of truncated protein. CONCLUSION: STK (11) gene mutation accounts for one third of the Chinese with PJS. The content of mutation includes single base substitution or deletion and one or two bases insertion. The mutations were widely found in different regions of the whole coding sequence, and 2/3 of those concentr ate in exon 1. Mutation frequency is 66.7% in the family suffering PJS in two or more generations, and 16.7% in the disseminated cases.

AMP-Activated Protein Kinase Kinases↗
PubMed2001

mRNA and protein expression of Fas associated death domain protein in apoptosic hepatocyte induced by tumor necrosis factor-alpha.

OBJECTIVE: To study the expression of protein and mRNA of Fas associated death domain protein (FADD) in the apoptosic hepatocyte induced by D-galactosamine (GalN) and TNF-alpha. METHODS: Fulminant hepatic failure (FHF) was induced by injection of GalN into sensitized BALB/c mice by TNF-alpha. Hepatocyte apoptosis was examined by electric microscopy, in site end labeling (ISEL) and DNA electrophoresis on 1.5% agarose gel. The expression of protein and mRNA of FADD were detected by immunohistochemistry and PT-PCR. RESULTS: GalN/TNF-alpha may induce hepatocyte apoptosis, necrosis and liver failure. The expression of protein and mRNA of FADD were positively correlative with the apoptosic hepatocytes. CONCLUSION: TNF-alpha induces hepatocyte apoptosis by up regulation expression of FADD protein.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Investigation on the rheological properties of hepatocellular carcinoma cells and their relevance to cytoskeleton structure.

OBJECTIVE: To investigate the relevance of the rheological properties, i.e., viscoelasticities and adhesion to basement membrane components coated surface, of both hepatocytes and hepatocellular carcinoma (HCC) cells to the cytoskeleton structure. METHODS: Micropipette aspiration technique was adopted to measure viscoelastic coefficients and adhesion forces to 2 microg/ml collagen IV/1.25 microg/ml laminin coated surface of the cells. Two kinds of cytoskeleton perturbing agents, colchicine and cytochalasin D, were used to treat both HCC cells and hepatocytes and the effects of these treatments on cell viscoelastic coefficients and cell adhesion forces were investigated. RESULTS: Upon treatment of cells with colchicine in a concentration range of 1 to 60 mg/L, the elastic coefficients, especially the first elastic coefficient K1, and adhesion forces of hepatocytes generally tended to increase or increased significantly while, in contrast, viscoelastic coefficients and adhesion forces of HCC cells decreased obviously. Upon treatment of cells with cytochalasin D in a concentration range of 0.25-5.00 mg/L, viscoelastic coefficients of both hepatocytes and HCC cells decreased uniformly, with a larger magnitude for the decrease in elastic coefficients and adhesion forces of HCC cells than for those of hepatocytes. Adhesion forces of hepatocytes and HCC cells onto collagen IV/laminin coated surface varied similarly as viscoelastic coefficients under the action of the cytoskeleton perturbing agents. A significant positive correlation existed between changes of HCC cell adhesion forces on collagen IV/laminin coated surfaces and those of cell elastic coefficients (P<0.01). CONCLUSIONS: The effects of cochicine and cytochalasin D on rheological properties of HCC cells differed significantly either in ways or extents from those on rheological properties of hepatocytes. These results might reflect the difference in the state of cytoskeleton structure and function among these two kinds of cells.

Carcinoma, Hepatocellular↗
PubMed2001

[Expression of tumor suppressor genes p16, p21 and p53 in a pair of lung adenocarcinoma cell lines with different metastasis potentials: Anip973 and AGZY83-a].

OBJECTIVE: In order to investigate the suppression effect of tumor suppressor genes in lung adenocarcinoma. METHODS: p16 and p21 expression vectors were transfected into a pair of lung adenocarcinoma cell lines with different metastasis potentials: Anip973(high metastasis potential)and AGZY83-a (low metastasis potential). In the mean time, AGZY83-a, Anip973, AGZY83-ap16 and Anip973p16 were infected with recombinant adenovirus encoding wild- type p53 gene. The suppression effects of these genes were evaluated by cell growth curve, MTT, cloning efficiency assay, flow cytometric analysis and TUNEL technique. RESULTS: Overexpression of p16 gene in Anip973 and AGZY83-a could only lengthen the G(1) phase while increased expression of p21 in both of the cell lines was associated with significant lengthening of G(1) phase, decreased proliferation potential and decreased cloning efficiency. High efficient expression of wild-type p53 gene in AGZY83-a, Anip973, Anip973p16 and AGZY83-ap16 inhibited the growth of these four kinds of lung cancer cells and killed the cells in the end. Apoptosis was detected in all the four kinds of cells. The suppression effect of p53 gene was higher in Anip973 and Anip973p16 than in AGZY83-a and AGZY83-ap16 while co-expression of p53 and p16 in this pair of cell lines inhibited the cells more efficiently as compared with the expression of p53 gene. CONCLUSION: Increased expression of p21 gene suppressed the lung adenocarcinoma cells by G(1) arrest and the co-transfection of tumor suppressor genes p16 and p53 into the lung adenocarcinoma cell line proved more effective in lung cancer gene therapy.

Adenocarcinoma↗
PubMed2001

[Application of chromosome painting technique to analysis of structural aberration of human chromosomes].

OBJECTIVE: This study was aimed at using chromosome painting technique to detect translocation, especially microtranslocations, on chromosomes in comparison with G-banding analysis. METHODS: Chromosome painting technique was applied to analysis of metaphase chromosomes of patients for detecting translocations with biotin-labeled chromosomes X, Y, 14q, 10 specific probes. RESULTS: Fluorescence in situ hybridization FISH signals were shown clearly in slides even in specimen stored at room temperature for 10 years and at -80 centigrade degree. Translocations were located precisely. CONCLUSION: Microtranslocations, which are hard to analyze by G-banding, can be detected exactly using chromosome painting technique with G-band karyotype on metaphase chromosome.

Adult↗
PubMed2001

[Vertical distribution characteristics of organochlorinated pesticides in sediment core from Macao estuary, Pearl River delta].

This work presents the analysis result of concentration for organochlorinated pesticides in a sedimentary core sample. Pesticides were quantified by GC/ECD with the internal standard material. The core dated by 210Pb methods. The vertical distribution of pesticides concentration with the depth was discussed. The results showed the concentration of BHCs and DDTs in the core ranged from 0.48 ng/g to 26.28 ng/g and 1.92-39.13 ng/g respectively. The distributing characteristics of organochlorinated pesticides in the core varied with the water fluxes of Pearl River. Organochlorinated pesticides may come from the residue of agricultural soils. Concentration of DDTs was above the effects range-low value for marine and estuarine sediments.

Geologic Sediments↗
PubMed2001

[Experimental studies on muscle fatigue of human limb motion with FNS].

The basic characteristic of the functional neuromuscular stimulation signals suitable to body is preliminarily determined after the fatigue performance of the biceps, and the physiological reaction to stimulation is investigated using many continuous stimulation signal patterns. The flexion motion of the elbow joint (right hand) of a healthy man was taken as our research objective. The surface electrodes were connected to the biceps and a micro angle sensor was mounted on the elbow joint (right hand). The curves of angular displacement for the elbow joint motion were obtained by using functional neuromuscular stimulation (FNS) limbs motion measurement instruments. The results demonstrate that the biceps are characterized by the non-linear and time-variant no matter what the stimulation patterns are, that continuous slow stimulation signals can reduce the muscle fatigue of the biceps, and that the stimulation frequencies ranging from 30 Hz to 50 Hz are applicable to the neuromuscular system.

Adult↗
PubMed2001

A growth factor mixture that significantly enhances angiogenesis in vivo.

Studies of therapeutic angiogenesis have generally focused on single growth factor strategies. However, multiple factors participate in angiogenesis. We evaluated the angiogenic potential of a growth factor mixture (GFm) derived from bovine bone. The major components of GFm (SDS-polyacrylamide gel electrophoresis, mass spectrometry, and Western blot) include transforming growth factor-beta1-3, bone morphogenic protein-2-7, and fibroblast growth factor-1. GFm was first shown to induce an angiogenic response in chorioallantoic membranes. Next, myocardial ischemia was induced in 21 dogs (ameroid) that were randomized 3 weeks later to received GFm 1 mg/ml (I), GFm 10 mg/ml (II), or placebo (P) (with investigators blinded to conditions) injected in and adjacent to ischemic myocardium. Dogs were assessed 6 weeks later using quantitative and semiquantitative measures. There were GFm concentration-dependent improvements in distal left anterior descending artery (LAD) opacification by angiography (P: 0.4 +/- 0.2, I: 1.1 +/- 0.14, II: 1.6 +/- 0.3, angiographic score p = 0.014). Histologically, there was also concentration-dependent vascular growth response of relatively large vessels (P: 0.21 +/- 0.15, I: 1.00 +/- 0.22, II: 1.71 +/- 0.18, vascular growth score p = 0.001). Resting myocardial blood flow (colored microspheres) was not significantly impaired in any group. However, maximum blood flow (adenosine) was reduced in ischemic territories and did not improve in GFm-treated hearts. GFm, a multiple growth factor mixture, is a potent angiogenic agent that stimulates large vessel growth. Although blood flow did not improve during maximal vasodilatory stress, large intramyocardial collateral vessels developed and angiographic visualization of the occluded distal LAD improved significantly. The use of multiple growth factors may be an effective strategy for therapeutic angiogenesis provided a more effective delivery strategy is devised that can achieve improved maximum blood flow potential.

Animals↗