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Biomedical subjects

G Wei

Publications and source records attributed to G Wei.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Analysis on 16S rDNA sequence of rhizobia isolated from Kummerowla sp].

Based on the previous studies on numerical taxonomy, SDS-PAGE of whole-cell protein and DNA hybridization, the rhizobial strains isolated from Kummerowia sp. in semi-arid area of North-west constituted a new subgroup, the 16S rDNA sequence of representative strain SH714 were tested. The unrooted phylogenetic tree was produced. In this tree, the strain SH714 with Sinorhizobium xinjiangensis, S. fredii, S. meliloti, S. medicae, S. saheli and S. teranga constituted a branch of Sinorhizobium. Within this branch, the similarity valuse of 16S rDNA sequence between strain SH714 and S. xinjiangesis, S. fredii, S. meliloti, S. medicae, S. saheli and S. teranga were 97.4%, 97.5%, 96.8%, 96.7%, 97.2% and 95.6% respectively, the values were more than 95%, this indicated that these known species should belong to the same genus. The values of DNA homology between type strains of these species were less than 70%. Thus, the strain SH714 represented a new rhizobial species, and there were some diversity between SH714 and known rhizobial species in phenotypic feature and composition of protein.

DNA, Bacterial↗
PubMed2001

[Effect of pH on the permeability of timolol maleate across isolated rabbit cornea].

AIM: To study the effect of pH on the transcorneal permeability of timolol maleate (TM). METHODS: The apparent distribution coefficients of TM were determined. The permeability of TM across isolated rabbit cornea was measured using in vitro method at various pH. RESULTS: The partition coefficient and pKa of TM were 63.63 and 9.17 respectively. At neutral pH, the apparent permeation coefficient of TM was 1.43 x 10(-5) cm.s-1. When the pH varied from 6.65 to 9.20, the cumulative amount for timolol transcorneal penetration increased 1.3 times and the lag time decreased more than 19-folds. The calculated permeability coefficients of ionized and un-ionized timolol were 1.29 x 10(-5) cm.s-1 and 4.22 x 10(-5) cm.s-1, respectively. CONCLUSION: Timolol penetrated corneal membrane mainly as free base by intracellular pathway, and corneal epithelium was the rate-limiting barrier.

Animals↗
PubMed2000

sqv-3, -7, and -8, a set of genes affecting morphogenesis in Caenorhabditis elegans, encode enzymes required for glycosaminoglycan biosynthesis.

sqv (squashed vulva) genes comprise a set of eight independent loci in Caenorhabditis elegans required zygotically for the invagination of vulval epithelial cells and maternally for normal oocyte formation and embryogenesis. Sequencing of sqv-3, sqv-7, and sqv-8 suggested a role for the encoded proteins in glycolipid or glycoprotein biosynthesis. Using a combination of in vitro analysis of SQV enzymatic activities, sqv(+)-mediated rescue of vertebrate cell lines, and biochemical characterization of sqv mutants, we show that sqv-3, -7, and -8 all affect the biosynthesis of glycosaminoglycans and therefore compromise the function of one specific class of glycoconjugates, proteoglycans. These findings establish the importance of proteoglycans and their associated glycosaminoglycans in epithelial morphogenesis and patterning during C. elegans development.

Animals↗
PubMed2000

Location of the glucuronosyltransferase domain in the heparan sulfate copolymerase EXT1 by analysis of Chinese hamster ovary cell mutants.

Heparan sulfate formation occurs by the copolymerization of glucuronic acid (GlcA) and N-acetylglucosamine (GlcNAc) residues. Recent studies have shown that these reactions are catalyzed by a copolymerase encoded by EXT1 and EXT2, members of the exostosin family of putative tumor suppressors linked to hereditary multiple exostoses. Previously, we identified a collection of Chinese hamster ovary cell mutants (pgsD) that failed to make heparan sulfate (Lidholt, K., Weinke, J. L., Kiser, C. S., Lugemwa, F. N., Bame, K. J., Cheifetz, S., Massagué, J., Lindahl, U., and Esko, J. D. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 2267-2271). Here, we show that pgsD mutants contain mutations that either alter GlcA transferase activity selectively or that affect both GlcNAc and GlcA transferase activities. Expression of EXT1 corrects the deficiencies in the mutants, whereas EXT2 and the related EXT-like cDNAs do not. Analysis of the EXT1 mutant alleles revealed clustered missense mutations in a domain that included a (D/E)X(D/E) motif thought to bind the nucleotide sugar from studies of other transferases. These findings provide insight into the location of the GlcA transferase subdomain of the enzyme and indicate that loss of the GlcA transferase domain may be sufficient to cause hereditary multiple exostoses.

Acetylglucosamine↗
PubMed2000

Prognostic impact of INK4A deletion in Ewing sarcoma.

BACKGROUND: The primary genetic alteration in > 95% of Ewing sarcomas (ES) is a specific fusion of EWS with FLI1 or ERG. Secondary genetic alterations possibly involved in progression of ES are not well understood. A recent study found loss of the negative cell cycle regulator gene INK4A in 8 of 27 ES samples (30%). To confirm these findings and evaluate their prognostic significance, the authors studied INK4A deletion in 41 ES samples from 39 patients. METHODS: Using Southern blot analysis with an INK4A p16 cDNA probe, the intensity of the INK4A bands in ES DNA samples was normalized to that of a control probe and compared with nondeleted control DNA; > 50% signal reduction was scored as evidence of deletion. All ES tumor DNA samples previously were confirmed to have EWS rearrangements on the same Southern blots, using a cDNA probe spanning the EWS breakpoint region. RESULTS: Tumors from 7 patients (18%) showed INK4A deletion independent of disease stage (localized or metastatic) or sample source (primary tumor or metastasis). INK4A was a strong negative factor for disease specific survival in univariate analysis (P = 0.001) and in multivariate analysis including stage (relative risk = 6; P = 0.001). CONCLUSIONS: INK4A deletions appear to be the most frequent secondary molecular genetic alteration found to date in ES. Their possible clinical usefulness in identifying a subset of ES patients with poor prognosis merits systematic prospective analysis. [See related article on pages 783-92.]

Adult↗
PubMed2000

Disruption of gastrulation and heparan sulfate biosynthesis in EXT1-deficient mice.

Mutations in the EXT1 gene are responsible for human hereditary multiple exostosis type 1. The Drosophila EXT1 homologue, tout-velu, regulates Hedgehog diffusion and signaling, which play an important role in tissue patterning during both invertebrate and vertebrate development. The EXT1 protein is also required for the biosynthesis of heparan sulfate glycosaminoglycans that bind Hedgehog. In this study, we generated EXT1-deficient mice by gene targeting. EXT1 homozygous mutants fail to gastrulate and generally lack organized mesoderm and extraembryonic tissues, resulting in smaller embryos compared to normal littermates. RT-PCR analysis of markers for visceral endoderm and mesoderm development indicates the delayed and abnormal development of both of these tissues. Immunohistochemical staining revealed a visceral endoderm pattern of Indian hedgehog (Ihh) in wild-type E6.5 embryos. However, in both EXT1-deficient embryos and wild-type embryos treated with heparitinase I, Ihh failed to associate with the cells. The effect of the EXT1 deletion on heparan sulfate formation was tested by HPLC and cellular glycosyltransferase activity assays. Heparan sulfate synthesis was abolished in EXT1 -/- ES cells and decreased to less than 50% in +/- cell lines. These results indicate that EXT1 is essential for both gastrulation and heparan sulfate biosynthesis in early embryonic development.

Animals↗
PubMed2000

Dynamic expression of glial cell line-derived neurotrophic factor after cerebral ischemia.

The aim of this study was to understand the possible involvement of glial cell line-derived neurotrophic factor (GDNF) in rat brain ischemic injury by examining the expression and the cellular location of GDNF with molecular biological and morphological techniques. Expression of GDNF mRNA and protein was first increased as early as 2h after ischemia-reperfusion in peri-infarct cerebral cortex and striatum; it then declined, and showed a second increase at 72 h. Double staining confirmed that the earlier peak of GDNF expression was of neuronal origin and the later peak of glial origin. Considering the neurotrophic characteristics of GDNF, our findings suggest that elevated endogenous GDNF expression may have important roles in protection of ischemic injured neuronal cells.

Animals↗
PubMed2000

Microdialysis sampling coupled to HPLC for transdermal delivery study of ondansetron hydrochloride in rats.

The transdermal delivery of ondansetron hydrochloride (ON) solution in propylene glycol (PG) with a widely used penetration enhancer, oleic acid (OA), was studied in rats by a microdialysis sampling technique. Dialysate samples collected from the probe were directly injected into the HPLC system without any pre-treatment and no interference occurred in the blank sample. A good linearity between the standard concentrations and peak areas within the calibration range was achieved. In vivo recovery (32.52 +/- 1.8%) of the probe was assessed with the retrodialysis method, which was used to calculate the ON concentration in the dermis. Oleic acid at the concentrations of 2% and 5% (w/v) increased the steady-state delivery rate from 0.001 to 0.030 and 0.058 microg/h, respectively. OA proved to be an effective enhancer for transdermal delivery of ON in rats.

Administration, Cutaneous↗
PubMed2000

Breast self-examination in women in two primary care settings: an evaluation of the impact of insurance status.

Breast cancer is one of the most common cancers diagnosed among women in the United States. Screening tools available for breast cancer detection include breast self-examination (BSE), clinical breast examination, and mammography. Various studies have indicated that women may inconsistently perform BSE. This investigation evaluated the potential impact of insurance status on BSE. Women with health insurance receiving primary healthcare at a health maintenance organization (HMO) and women without health insurance receiving primary healthcare at a free clinic completed anonymous questionnaires that obtained information about the frequency of BSE performance, whether instruction was given about performing BSE, age at learning BSE, and confidence in performing BSE. One hundred fifty-five (82%) of 200 questionnaires at the HMO and 92 (92%) of 100 questionnaires at the free clinic were completed. Thirty-five percent of women (32% at the HMO, 39% at the free clinic) reported performing BSE. There were no significant differences in the rate of monthly BSE, receiving instruction about performing BSE, age at learning BSE, or confidence in performing BSE in women at the HMO and free clinic. Insurance status did not affect BSE. However, further study is needed to evaluate factors that potentially influence performance of BSE and could encourage compliance with BSE recommendations.

Adolescent↗
PubMed2000

ets-2 is a target for an akt (Protein kinase B)/jun N-terminal kinase signaling pathway in macrophages of motheaten-viable mutant mice.

The transcription factor ets-2 was phosphorylated at residue threonine 72 in a colony-stimulating factor 1 (CSF-1)- and mitogen-activated protein kinase-independent manner in macrophages isolated from motheaten-viable (me-v) mice. The CSF-1 and ets-2 target genes coding for Bcl-x, urokinase plasminogen activator, and scavenger receptor were also expressed at high levels independent of CSF-1 addition to me-v cells. Akt (protein kinase B) was constitutively active in me-v macrophages, and an Akt immunoprecipitate catalyzed phosphorylation of ets-2 at threonine 72. The p54 isoform of c-jun N-terminal kinase-stress-activated kinase (JNK- SAPK) coimmunoprecipitated with Akt from me-v macrophages, and treatment of me-v cells with the specific phosphatidylinositol 3-kinase inhibitor LY294002 decreased cell survival, Akt and JNK kinase activities, ets-2 phosphorylation, and Bcl-x mRNA expression. Therefore, ets-2 is a target for phosphatidylinositol 3-kinase-Akt-JNK action, and the JNK p54 isoform is an ets-2 kinase in macrophages. Constitutive ets-2 activity may contribute to the pathology of me-v mice by increasing expression of genes like the Bcl-x gene that promote macrophage survival.

Animals↗
PubMed2000

Stem cell plasticity in mammals and transdetermination in Drosophila: common themes?

Stem cells have been identified in a number of mammalian tissues (e.g. bone marrow, muscle, gut, skin, and neural tissues). Until recently, it was generally believed that the differentiation potential of a mammalian somatic stem cell is restricted to one tissue only, as in the case of hematopoietic stem cells differentiating into hematopoietic cells. In this sense, somatic stem cells are limited in their differentiation potential. Several lines of evidence now challenge the idea of unilateral development. New reports show mammalian somatic stem cells can, in the course of regeneration, repopulate heterologous cell systems and therefore possess a surprisingly broad spectrum of differentiation potential. Thus, mammalian stem cells are apparently capable of fate changes between stem cell systems, although the mechanisms leading to such changes are unclear. Mechanistic models for fate changes have been proposed in Drosophila, specifically for transdetermination of imaginal discs. Imaginal discs of the larva are the primordia of the adult exoskeleton and appendages, for example, legs, and antennae. Transplantation experiments of imaginal discs have shown that discs are determined for their disc identity. Transdetermination in Drosophila refers to cases when, after regenerative cell divisions, imaginal disc cells change from one state of determination to another, initiating a pathway of differentiation leading to structures other than those corresponding to the initial state or determination; for example, an antennal imaginal disc transdetermines to a leg imaginal disc. A fate change is thus possible in both mammalian somatic stem cells and Drosophila imaginal discs following transplantation and subsequent proliferation. Here we summarize and compare observations made in such cases of stem cell and imaginal disc differentiation.

Animals↗
PubMed2000

JC virus binds to primary human glial cells, tonsillar stromal cells, and B-lymphocytes, but not to T lymphocytes.

The human polyomavirus, JCV, is the etiological agent of the fatal central nervous system demyelinating disease, progressive multifocal leukoencephalopathy (PML). In PML patients, JC Virus (JCV) can be detected in glial cells in the central nervous system (CNS); in B-lymphocytes in the peripheral blood, bone marrow, spleen, and tonsil; and in tonsillar stromal cells. In vitro, JCV infects glial cells, tonsillar stromal cells, and to a limited extent B-lymphocytes. The presence or absence of as yet unidentified cell type specific transcription factors contributes to the restricted tropism of JCV for these cell types. However, several studies indicate that cell surface receptors may also contribute to the limited host range of JCV. To examine this latter possibility we measured the binding of purified JCV virions to primary cultures of glial cells, tonsillar stromal cells, peripheral blood lymphocytes, and to several established cell lines. Our results demonstrate that JCV binds to primary glial cells, stromal cells, and B cells, but does not bind to primary T cells. In contrast, JCV bound to all cell lines tested, including the Namalwa B cell line and the Jurkat T cell line. These data are novel and demonstrate that JCV selectively interacts with cells in vivo that are known to be susceptible to infection. This selectivity appears to be lost when one examines virus binding to a variety of human, monkey, or mouse tumor cell lines. We next examined the susceptibility of primary peripheral blood lymphocytes and the Namalwa B cell line to infection with JCV. Our results demonstrate that the majority of infectious JCV virions remain cell surface associated and do not efficiently establish infection of B cells. This may explain the in vivo observation that JCV DNA is frequently detected in association with lymphocytes by PCR but that JCV mRNA is rarely detected in association with lymphocytes by reverse transcriptase PCR. These results also confirm previous data regarding the association of JCV with human B cells in vivo and support the hypothesis that B cells may be involved in trafficking of JCV to the CNS.

3T3 Cells↗
PubMed2000

Regulation of glial cell line-derived neurotrophic factor expression by electroacupuncture after transient focal cerebral ischemia.

The present study was designed to investigate whether electroacupuncture (EA) is able to regulate glial cell line-derived neurotrophic factor (GDNF) expression following transient middle cerebral artery occlusion (MCAO) using reverse transcriptase polymerase chain reaction and immunohistochemistry in rats. The results indicate that after 2 h MCAO, GDNF mRNA and immunoreactivity profoundly increased in peri-infarct cerebral cortex, with peaks at 2 h after reperfusion, then declined dramatically at 12 and 24 h after reperfusion. Although EA given immediatelly after MCAO couldn't elevate the peaks of GDNF expression, it obviously raised the GDNF mRNA and immunoreactivity levels at 12 h after reperfusion, delayed the declining trends of GDNF mRNA and immunoreactivity levels. These results suggest that EA could upregulate GDNF expression after ischemic insult, elongating the duration of upregulated GDNF expression. This may be one of the mechanisms of EA anti-ischemic injury by augmenting endogenous protective mechanism.

Animals↗
PubMed2000

Myocardial postischemic injury is reduced by polyADPripose polymerase-1 gene disruption.

BACKGROUND: PolyADPribose polymerase (PARP) is activated by DNA strand breaks to catalyze the addition of ADPribose groups to nuclear proteins, especially PARP-1. Excessive polyADPribosylation leads to cell death through depletion of NAD+ and ATP. MATERIALS AND METHODS: In vivo PARP activation in heart tissue slices was assayed through conversion of [33P]NAD+ into polyADPribose (PAR) following ischemia-reperfusion (I/R) and also monitored by immunohistochemical staining for PAR. Cardiac contractility, nitric oxide (NO), reactive oxygen species (ROS), NAD+ and ATP levels were examined in wild type (WT) and in PARP-1 gene-deleted (PARP-1(-/-)) isolated, perfused mouse hearts. Myocardial infarct size was assessed following coronary artery occlusion in rats treated with PARP inhibitors. RESULTS: Ischemia-reperfusion (I/R) augmented formation of nitric oxide, oxygen free radicals and PARP activity. I/R induced decreases in cardiac contractility and NAD+ levels were attenuated in PARP-1(-/-) mouse hearts. PARP inhibitors reduced myocardial infarct size in rats. Residual polyADPribosylation in PARP-1(-/-) hearts may reflect alternative forms of PARP. CONCLUSIONS: PolyADPribosylation from PARP-1 and other sources of enzymatic PAR synthesis is associated with cardiac damage following myocardial ischemia. PARP inhibitors may have therapeutic utility in myocardial disease.

Adenosine Triphosphate↗
PubMed2000

[Distribution patterns of shoots, flowers and seeds in Ginkgo biloba canopy and their relationships].

The distribution patterns of shoots, flowers and seeds in the canopy of 14 years old engrafted Ginkgo biloba and their relationships were investigated with stratification method. The result shows that long shoots, short shoots, bearing-shoots and flowers uniformly distributed in the central section of canopy. From the top to the bottom, the average age and the divaricating angle of long shoots increase 51.3% of the seeds distributed in 180-320 cm layer from the ground. The number of shoots, flowers and seeds in different canopy layers was closely correlated.

Ginkgo biloba↗
PubMed2000

[GC-MS analysis of volatile componments in root of Ficus hitra].

The volatile components in root of Ficus hitra Vahl were analyzed by GC-MS, the results suggested that the main volatile components in root of Ficus hitra Vahl were Hexadecanoic acid, Oleic acid, Linolic acid and Ethyl Acetate; its ether extract contains Isopsoralen and Bergapten. Coumarins should be one of the effective sections in root of Ficus hitra Vahl.

Coumarins↗
PubMed2000

[Hyperconjugation, characteristic infrared absorption of methylsulfones and crystal structures of selected aromaticsulfones].

A branched absorption peak with medium intensity at (970 +/- 20) cm-1 appears only in the infrared spectra of methylsulfones. The below mentioned aromaticsulfones are chosen to reveal the specificity. Crystal and molecular parameters of CH3CONH-C6H4-SO2R(R = -CH3, -CH2CH2OH)-CH2CONH2, are determined by application of single crystal diffraction of X-ray through Nicolet R3M/E diffracometer. The existence of hyperconjugation and its natures in group -SO2CH3, confirmed by further analyses on the parameters, result in the specificity of IR absorption of the group, which is proved characteristic and can be used to identify methylsulfones. The first part describes the detection results, ascertains their crystal and molecular structures, and shows that the aromaticsulfone exists as cross linking multi-molecules when R = -CH2CONH2 or as double molecules when R = -CH2CH2OH because of H bonds. The second part covers analyses on their molecular structures. The analyses demonstrate the hyperconjugation between sigma S-C and pi S-C in group -SO2CH3. The sigma C-H hyperconjugate with pi S-O. The strength of hyperconjugated bond C-H decreases and its length tends longer. Due to the effect, the bond S-C is not a pure single bond sigma, but one which possesses a certain degree of a double bond. Its IR wave number, between those of sigma S-C and pi S-C, attributes to the medium branched peak at (970 +/- 20) cm-1. The peak branch reflects two groups of the most stable hyperconjugating conformational isomers. The hyperconjugation is weakened by the substitution of one non H group for one H atom in -SO2CH3 and if the non H group does not conjugate with pi S-O, the absorption at (970 +/- 20) cm-1 disappears as a characteristic peak. The intensity of absorption at (970 +/- 20) cm-1 conforms to the intensity of hyperconjugation between pi S-O and its adjacent sigma C-H. The third part introduces syntheses of the products, crystal preparations and their detections through X-ray diffraction.

English Abstract↗