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Biomedical subjects

G Zhang

Publications and source records attributed to G Zhang.

At least 109 records · Page 6Linked to original sources
PubMed2001

Go!Poly: A gene-oriented polymorphism database.

Human genome polymorphisms play a key role in defining the molecular basis of phenotypic differences between individuals in aspects such as disease susceptibility and drug responses. The database requirements for supporting the study of human genetic variation have been well recognized. In order to meet these needs, several generalized databases have been built. However, it is still hard for users to find gene-related variation data from these huge and sophisticated databases. In its role as a gene-oriented directory of polymorphism data, Go!Poly (Gene Oriented Polymorphism Database; http://61.139.84.5/gopoly/) utilizes two new highly curated and non-redundant resources, LocusLink (http://www.ncbi.nlm.nih.gov/LocusLink/) and RefSeq (http://www.ncbi.nlm.nih.gov/LocusLink/refseq.html), as the standard for identifying and positioning nucleotide variations. As a generalized polymorphism database, Go!Poly extracts human gene-linked sequence variations of all common types (SNP, insertion-deletion, simple tandem repeat, and complex nucleotides variations) from various public resources including scientific journals and internet resources, such as HGBASE (http://hgbase.cgr.ki.se) and dbSNP (http://www.ncbi.nlm.nih.gov/SNP/). The polymorphism data are then categorized into different gene loci, and the reference sequences given by LocusLink are used as positioning references. Through close integration with LocusLink, Go!Poly also provides facilitated connections among sequence data, gene name, and related biological information. This feature also makes Go!Poly easy to search and navigate. Future automated annotations and internal consistency checking may also benefit from this. Extensive efforts are being taken to make the polymorphism information generated by the Chinese scientific community available from this resource.

China↗
PubMed2001

Near-infrared photo-excited emission from tissues treated at different temperature levels.

BACKGROUND AND OBJECTIVE: There is a lack of methods to evaluate the extent of thermal treatment of biological tissue. The intensity of the near-infrared (NIR) emission photo-excitation was investigated from tissue undergoing different levels of heat treatment. STUDY DESIGN/MATERIALS AND METHODS: Chicken muscle was heated in an oven at different temperature levels ranging from 40 degrees C until burn-off. The spectral emission intensity from these heat-treated tissues was measured with a CCD camera and the intensity was calculated. RESULTS: The emission intensity increased proportionally with respect to the extent of treatment temperature until burning. Linear relationships between treatment temperature and the emission intensity from tissue samples were found in three temperature ranges: from 40 to 160 degrees C, from 165 to 220 degrees C, and from 225 to 250 degrees C. CONCLUSIONS: The change in tissue damage after heat treatment could be detected by measuring the NIR emission intensity from the thermally damaged tissues.

Animals↗
PubMed2001

In vivo transfection of lamprey brain neurons by gene gun delivery of DNA.

The lamprey has been used extensively in studies of CNS axon regeneration. Progress in determining molecular mechanisms involved in regeneration will require the ability to manipulate expression of target genes or to introduce new genes, but in vivo neuronal transfection has posed difficulties in the mature intact nervous system of vertebrates, including the lamprey. In this paper we report successful transfection of neurons in the brain of living lampreys by means of a hand-held Helios Gene Gun. Particle-mediated ("gene gun") gene transfer has been applied to a variety of cell and tissue types but although it has been used in brain slices and dissociated cultured neurons, to our knowledge it has not been reported as a method for transfection of brain cells in a living animal. Gold particles coated with plasmids containing the gene for the reporter beta-galactosidase were propelled by helium at 150--200 psi toward the exposed floor of the 4th ventricle. Transfected animals were examined by X-gal histochemistry at various recovery times. beta-glactosidase activity was detected as early as 2 days after gene transfer and lasted for at least 6 weeks, the longest time studied. Transgene expression lasted longer in neurons than in glia. The expression product was transported anterogradely into reticulospinal axons and by 6 weeks could be traced into the spinal cord for 8--10 mm caudal to the obex. This raises the possibility of identifying the growth cones of developing or regenerating axons belonging to transfected neurons in functional studies of manipulated genes.

Animals↗
PubMed2001

Specific recognition of protein carboxy-terminal sequences by natural IgM antibodies in normal serum.

Our previous study indicated that normal serum contains complement-fixing natural IgM antibodies reacting with a large variety of randomly generated protein carboxy-termini. Here we show that the "carboxy-terminal" IgM (C-IgM) antibodies specifically react with short peptide sequences located immediately at the protein carboxy-terminus. The specificity of C-IgM-peptide interactions is tentatively defined by three to four amino acid residues. All carboxy-terminal peptides in a large peptide library apparently react with C-IgM antibodies. Immobilized synthetic peptides also react with C-IgM antibodies. No interaction of C-IgM antibodies with internal peptide sequences has been observed. C-IgM antibodies are present in germ-free and in athymic adult rats and are absent in newborn rats. The natural ubiquity of protein carboxy-termini in biological structures suggests that C-IgM could play an important role in antigen clearance and presentation to the immune system. From a practical viewpoint, the recognition of carboxy-terminal peptides by complement-fixing C-IgM antibodies has profound implications for the use of peptide- and protein-derivatized delivery vehicles and artificial materials.

Animals↗
PubMed2001

Study on the preparation of recombinant human HSP70 and its presenting-antigen function.

The preparation of recombinant human HSP70 and its presenting-antigen function were investigated. Cultured in glucose-free M9ZB medium and induced with IPTG and lactose at a final concentration of 0.02 mmol/L and 5 mmol/L respectively, the engineered bacteria carrying expression vector of human HSP70 gene expressed rHSP70 at an efficiency fo 60%. After the purification with DEAE ion-exchange chromatography, HSP70 with a purity of higher than 90% was obtained. The purified product could bind tumor-antigen peptide in vitro, and the binding was identified by native PAGE containing 5% glycerol. HSP70-peptide complex could activate lymphocytes to produce specific cytotoxicity to tumor cells, suggesting that the recombinant human HSP70 could be used as an antigen-presenting reagent in tumor therapy.

Animals↗
PubMed2001

Construction and expression of eukaryotic expressing vector pCH510 of polypeptide CH50 and its chemotaxis and antitumor function by in vivo transfection.

To construct an eukaryotic expressing vector that expresses CH50, a recombinant Cell I-Hep II bifunctional-domain polypeptide of human fibronectin, and to investigate the chemotaxis to immune cells and the inhibitory effect on the growth of tumor by the expression of the plasmid in vivo, the plasmid was constructed by DNA recombination. Gene transfection was performed in vitro and in vivo. The expressed product was identified by Western blot. The chemotaxis after gene transfection in vivo was observed by histotomy and staining of muscle tissues. The inhibition of gene transfection on solid tumor was observed in mice. The results showed that plasmid pCH510 was constructed by the recombination of the 5'-terminal noncoding region and signal peptide coding region of human fibronectin cDNA and cDNA fragment coding CH50 polypeptide with a 3'-terminal noncoding region of human FN cDNA, and the insertion of the recombinated fragment into plasmid pcDNA3. 1. After transfection with plasmid pCH510, NIH3T3 cells could produce CH50 polypeptide. The transfection of plasmid pCH510 by the injection in muscle of mouse could produce the effects of chemotaxis on immune cells and the inhibition on the growth of solid tumor. It is concluded that plasmid pCH510 can express in cells and in vivo in mouse. The expression of the plasmid in vivo has a chemotactic effect on immune cells and can inhibit the growth of solid tumor.

3T3 Cells↗
PubMed2001

Industrial scale production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

Large scale production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] by Aeromonas hydrophila 4AK4 was examined in a 20,000 l fermentor. Cells were first grown using glucose as a carbon source, and polyhydroxyalkanoate (PHA) biosynthesis was triggered by the addition of lauric acid under conditions of limited nitrogen or phosphorus. When cells first grown in a medium containing 50 g glucose l(-1) were further cultivated after the addition of 50 g lauric acid l(-1) under phosphorus limitation, a final cell concentration, PHA concentration and PHA content of 50 g l(-1), 25 g l(-1), and 50 wt%, respectively, were obtained in 46 h, equivalent to PHA productivity of 0.54 g l(-1)t h(-1). The copolymer produced was found to be a random copolymer, and the 3HHx fraction was 11 mol%.

3-Hydroxybutyric Acid↗
PubMed2001

Identification of six novel MYH9 mutations and genotype-phenotype relationships in autosomal dominant macrothrombocytopenia with leukocyte inclusions.

The autosomal dominant macrothrombocytopenia with leukocyte inclusions, May-Hegglin anomaly (MHA), Sebastian syndrome (SBS), and Fechtner syndrome (FTNS), are rare platelet disorders characterized by a triad of giant platelets, thrombocytopenia, and characteristic Döhle body-like leukocyte inclusions. The locus for these disorders was previously mapped on chromosome 22q12.3-q13.2 and the disease gene was recently identified as MYH9, the gene encoding the nonmuscle myosin heavy chain-A. To elucidate the spectrum of MYH9 mutations responsible for the disorders and to investigate genotypephenotype correlation, we examined MYH9 mutations in an additional 11 families and 3 sporadic patients with the disorders from Japan. Korea, and China. All 14 patients had heterozygous MYH9 mutations, including three known mutations and six novel mutations (three missense and three deletion mutations). Two cases had Alport manifestations including deafness, nephritis, and cataracts and had R1165C and E1841K mutations, respectively. However, taken together with three previous reports, including ours, the data do not show clear phenotype-genotype relationships. Thus, MHA, SBS, and FTNS appear to represent a class of allelic disorders with variable phenotypic diversity.

Asia↗
PubMed2001

Enforced expression of the GATA-3 transcription factor affects cell fate decisions in hematopoiesis.

OBJECTIVE: Three GATA family transcription factors are involved in various aspects of hematopoiesis. Their lineage-restricted expression correlates well with their function in selective lineage commitment and differentiation. We focused on the role of GATA-3 to determine whether an intrinsic variation among different GATA proteins, in addition to the distinct expression pattern, determines lineage specification. MATERIALS AND METHODS: Using a retroviral vector, we introduced the GATA-3 gene into primary murine hematopoietic stem cells (HSC) and examined their development in in vitro suspension culture and colony-forming assays as well as in vivo competitive repopulation studies. RESULTS: Although GATA-3 expression normally is restricted to lymphoid precursor and committed T cells, overexpression of GATA-3 in HSC results in cessation of cell expansion followed by selective induction of megakaryocytic and erythroid differentiation and inhibition of myeloid and lymphoid precursor development in liquid suspension culture and in vitro colony-forming assays. Competitive repopulation studies show that transplanted GATA-3-expressing HSC/progenitor cells give one wave of erythrocyte development but fail to expand in the bone marrow or to reconstitute other lineages. CONCLUSIONS: The selective megakaryocytic/erythroid differentiation in HSC with enforced GATA-3 expression suggests a functional redundancy among GATA proteins and indicates that the specific lineage fate determination by individual GATA proteins is largely regulated at the level of expression in a lineage and developmental-stage restricted fashion, whereas the identity of the GATA factor may not be as important.

Animals↗
PubMed2001

[Africa or Asia, which is the evolutionary origin of human schistosomes?].

The origin and the evolution of Schistosomatidae species, due to their medical importance (responsible of the second most important human parasitosis after malaria), arouse a great interest. A combination of phylogenetic studies using several molecular markers has provided support for the traditional grouping and evolutionary inferences derived from morphological and biological data. The genus Schistosoma, which comprises all species parasitizing Man, is generally split into four evolutionary lineages (mansoni, haematobium, indicum and japonicum lineages). The group of African schistosomes (including mansoni and haematobium lineages) appears very divergent from the japonicum lineage. Recent phylogenetic studies using partial 28S rDNA sequencing and including Orientobilharzia turkestanicum from Iran, an Asian parasite of livestock, found, unexpectedly, that this species nested among Schistosoma species, thus rendering the latter paraphyletic, and suggested an Asian origin for the Schistosoma genus. The present work re-examines the question of the geographical origin of human schistosomes by analysing a new genomic marker (ITS2) as well as by including the use of O. turkestanicum originating from northeastern China. Our results are in agreement with previous work using 28S, in demonstrating that Schistosoma is not monophyletic. However, O. turkestanicum, whatever the method of analysis used (distance or parsimony), was grouped with members of the japonicum group to the exclusion of African Schistosoma species. Then, our data argue strongly for the need for further phylogenetic study including new taxa and new genomic sequences before definitely concluding either an Asian or African origin for the genus Schistosoma.

Africa↗
PubMed2001

Synthesis of galactosyl compounds for targeted gene delivery.

Cell-specific DNA delivery offers a great potential for targeted gene therapy. Toward this end, we have synthesized a series of compounds carrying galactose residues as a targeting ligand for asialoglycoprotein receptors of hepatocytes and primary amine groups as a functional domain for DNA binding. Biological activity of these galactosyl compounds in DNA delivery was evaluated in HepG2 and BL-6 cells and compared with respect to the number of galactose residues as well as primary amine groups in each molecule. Transfection experiments using a firefly luciferase gene as a reporter revealed that compounds with multivalent binding properties were more active in DNA delivery. An optimal transfection activity in HepG2 cells requires seven primary amine groups and a minimum of two galactose residues in each molecule. The transfection activity of compounds carrying multi-galactose residues can be inhibited by asialofetuin, a natural substrate for asialoglycoprotein receptors of hepatocytes, suggesting that gene transfer by these galactosyl compounds is asialoglycoprotein receptor-mediated. These results provide direct evidence in support of our new strategy for the use of small and synthetic compounds for cell specific and targeted gene delivery.

Animals↗
PubMed2001

Formation of novel polymeric nanoparticles.

We have found that not only block copolymers but also ionomers can self-assemble in a selective solvent to form surfactant-free nanoparticles. The self-assembly can be induced by chemical reaction, polymer-polymer complexation, and microphase inversion in addition to the temperature. A recently developed microwave method for the preparation of uniform surfactant-free polymeric nanoparticles is also reviewed. Our results have revealed that for a given dispersion, the particle surface area occupied per stabilizer (surfactant, polymer chains, and ionic groups) is close to a constant.

Microspheres↗
PubMed2001

Volatiles from Ficus hispida and their attractiveness to fig wasps.

Volatile compositions of receptive (ready to be pollinated), postpollinated, and postparasitized figs. and leaves of Ficus hispida were analyzed. Differences among them were examined, and the specificity of fig wasp attractiveness was investigated. Linalool was the major constituent of steam-distilled oil of either male or female receptive figs, while dibutyl phthalate was the major compound of the oils of postparasitized and postpollinated figs. In petroleum ether extracts, palmitic oil, and 9,12-octadecadienoic acid were the main constituents of male and female receptive figs, while hexadecanoic acid ethyl ester was the major compound of postparasitized and postpollinated figs. In dichloromethane extracts, linalool was the major constituent of male and female receptive figs, 1-hydroxylinalool was the major component of male postparasitized figs, and 1-hydroxylinalool and benzyl alcohol were the major constituents of female postpollinated figs. Bioassays with sticky traps showed that Ceratosolen solmsimarchal was attracted to dichloromethane extracts of male and female receptive figs and to petroleum ether extracts of female receptive figs, but was not attracted to dichloromethane and petroleum ether extracts of male postparasitized and female postpollinated figs. Figs were attractive to pollinating wasps only at the receptive stage. The volatile constituents of receptive figs were different from those of postpollinated or postparasitized figs. From a receptive to a postpollinated state, figs changed in their volatile composition. Some compounds disappeared or decreased in amount. These include linalool, linalool oxide, alpha-terpeneol, and 2,6-dimethyl-1,7-octadiene-3,6-diol, which may act as the attractants of the wasps. Others increased in amount, or several additional chemicals appeared. These include dibutyl phthalate, 1-hydroxylinalool, and benzyl alcohol, which may be repellents of the wasps. That dichloromethane extracts of male and female receptive figs showed similar activities in attracting fig wasps indicates that receptive figs of both sexes are similarly attractive to fig wasps, which is further supported by their similar volatile composition. Leaf extract was not attractive to the wasps.

Animals↗
PubMed2001

Clinical validation of new pacing-sensing configurations for atrial automatic capture verification in pacemakers.

INTRODUCTION: This study evaluated an atrial automatic capture verification scheme based on atrial evoked response (AER). Atrial pacing was between Atip and Can (Atip-Can) using different coupling capacitances (CCs). Independent pairs of sensing electrodes between Aring and Vtip (Aring-Vtip) or between Aring and a separate indifferent electrode (Aring-Indiff) were used to reduce pacing-induced afterpotentials. METHODS AND RESULTS: A custom-made external pacing system was used to perform automatic step-up and step-down pacing (0.1 to 7.1 V at 0.5 msec, step size of 0.1 V) using different CCs (2 or 15 microF). Intracardiac signals from Aring-Indiff and Aring-Vtip were independently recorded and analyzed both in real time and off-line to detect AER. Every paced beat also was visually inspected and compared with surface ECG to verify the captures. With the intracardiac signals properly filtered, AER detection was based on the signal within a window of 12 to 65 msec after the stimulus. Data from 27 patients (4 chronic and 23 acute implantations; age 65.6+/-13.9 years) were analyzed. Bipolar atrial lead measurements using a standard pacing system analyzer were as follows (mean +/- SD): impedance 695+/-227 ohms, P wave amplitude 4.2+/-2.3 mV, slew rate 1.1+/-0.9 V/sec, and pacing threshold at 0.5 msec 1.0+/-0.5 V. The results with CC = 2 microF showed that of 9,500 atrial paced beats, correct capture verification rates were 99.8% (Aring-Indiff) and 99.4% (Aring-Vtip). Similar results were achieved with CC = 15 microF (99.7% and 99.5%, respectively). CONCLUSION: AER can be reliably detected using independent pacing (Atip-Can) and sensing (Aring-Vtip or Aring-Indiff) electrodes. Therefore, atrial automatic capture verification by AER detection is feasible.

Adult↗
PubMed2001

Electro-acupuncture attenuates behavioral hyperalgesia and selectively reduces spinal Fos protein expression in rats with persistent inflammation.

This study examined the effect of electro-acupuncture (EA) on persistent inflammatory hyperalgesia in a rat model. Inflammation and hyperalgesia were induced by injecting complete Freund's adjuvant (CFA) into one hindpaw of the rat. Hyperalgesia was determined by a decrease in paw withdrawal latencies (PWL) to a noxious thermal stimulus. EA was applied bilaterally at the acupuncture point Huantiao (G30) at the rat's hindlimbs. EA-treated rats (n = 11) had significantly longer PWLs as compared with placebo control rats (n = 7) in the inflamed paw at 2.5 hours and 5 days after injection of CFA (P <.05) and longer PWLs as compared to sham control rats (n = 9) at 2.5 hours (P >.05). Paw edema was significantly reduced in EA-treated rats versus placebo controls at 24 hours after inflammation (P <.01). Inflammation-induced spinal Fos expression in the medial half of laminae I-II in EA-treated rats versus placebo rats (n = 5 per group) was significantly reduced (P <.01). These data showed that EA delayed the onset and facilitated the recovery of inflammatory hyperalgesia and suppressed the inflammation-induced spinal Fos expression in neurons (laminae I-II) involved in receiving noxious stimulation. This rat model of persistent pain and inflammation seems to be an ideal animal model for studying the effect of acupuncture.

Journal Article↗