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Biomedical subjects

T Zhu

Publications and source records attributed to T Zhu.

At least 55 records · Page 3Linked to original sources
PubMed2001

Apolipoprotein E polymorphism in the early onset of coronary heart disease.

OBJECTIVE: To assess the relationship between apolipoprotein E (apoE) polymorphism and the early onset of coronary heart disease (CHD) and the effect of apoE on lipids and lipoproteins in healthy Chinese subjects. METHODS: Sixty-eight patients with CHD younger than 55 years (CHD1), 136 patients with CHD older than 65 years (CHD2), and 136 healthy subjects were enrolled, and their plasma levels of triglyceride (TG), total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) were determined. The apoE genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: apoE 3/4 genotype and E4 allele frequency in the CHD1 group were higher than those in the CHD2 group and healthy subjects, while no differences were found between CHD2 and healthy subjects. Meanwhile, the plasma levels of TC and low density lipoprotein cholesterol (LDL-C) were higher in the CHD2 group than in both CHD1 group and healthy subjects. Each apoE isoprotein has variable TC and LDL-C levels that is E2 (E2/2 + E2/3) < E3(E3/3) < E4(E4/4 + E3/4). CONCLUSION: apoE is one of the genetic factors that affect TC and LDL-C levels, and apoE 4 has a very close relation to CHD, suggesting that apoE 4 is an independent genetic factor of the early onset of CHD.

Adult↗
PubMed2001

[Geostrophic deviation analysis of regional effects of protective forest system in reducing windspeed in north Liaoning plain].

East Asian synoptic charts and ground wind data in April and May of four counties of north Liaoning plain were selected to calculate the regional effects of protective forest system in reducing windspeed by geostrophic deviation method. The results show that the protection effects increased with increasing forestration area. Different protection effects of protective forest appeared at different daytime, with the greatest at 14:00 and smallest at 2:00, and the average windspeed reduced 13.3%. The characteristics of the geostrophic deviation method was also discussed.

China↗
PubMed2001

The effect of electro-acupuncture on motor function recovery in patients with acute cerebral infarction: a randomly controlled trial.

UNLABELLED: The aim of this study is to investigate the effect of electro-acupuncture treatment in acute phase of cerebral infarction on the motor functions. In this randomly controlled trial, 86 patients were allocated to two groups, the experimental group given clinical and electro-acupuncture treatments for a period of 4 weeks, and the control group given clinical treatment plus active and/or passive functional exercise. The result showed that the level of impairment and disability in both groups were improvement according to the Chinese Stroke Scale, Brunnstrom-Fugl-Meyer score, and Barthel Index throughout the study and 3 months after. The motor functions and the activities of daily living (ADL) were improved significantly in the electro-acupuncture group as compared with the control group (P < 0.05). Also, the results showed greater reduction of neurological deficit in the electro-acupuncture group than in the control group. CONCLUSION: Early acupuncture treatment for acute stroke patients may improve motor functions, and consequently the activities of daily living.

Acupuncture Therapy↗
PubMed2001

[Studies on transference of hydrogenase genes of Rhizobium arachis].

The hydrogen-uptake genes were transferred into wild Rhizobium arachis Ra strains (Hup-, Nif+, Apr) by triparental mating using pRK2013 as help plasmid. A transconjugant R. arachis Rz34-2(Hup+, Nif+, Apr, Tcr) which expressed high activities of hydrogenase and nitrogenase under free-living and symbiotic state was screened. Peanut inoculation test with recipient R. arachis Ra34, transcojugant Rz34-2 and control strain R. arachis L8-3 (Hup+, Nif+) was carried out respectively. The results showed that, compare to treatment without inoculation, inoculation with R. arachis Ra34 and R. arachis L8-3, the dry weight of leaf inoculated with transconjuant Rz34-2 increased 6.2%, 7.6% and 6.3% respectively; the N-content of seed increased 8.8%, 10.0% and 6.0%; the output increased 18.8%, 10.5% and 10.7%. This suggested that legume plants inoculated with Rhizobium strains (Hup+) were more efficient to accumulate N and to increase its output.

Arachis↗
PubMed2001

[Neuronavigation-assisted resection of gliomas near eloquent regions].

OBJECTIVE: To evaluate the effect of the neuronavigation system in operation of gliomas near eloquent regions. METHOD: The brain LAB VV2 navigation system was used in 11 patients with gliomas near eloquent regions. The value of this system for glioma resection was assessed, and the accuracy and notice for application were discussed. RESULTS: The mean registration error was (1.5 +/- 0.7) mm in the patients. Total lesion removal was achieved in 9 patients (81.8%). The clinical status of all patients improved, and their functions of motor were not significantly affected. No complications were attributed to the use of this system. CONCLUSION: The neuronavigation system is reliable and accurate in surgical treatment of gliomas near eloquent regions. It increases the fraction of radical in glioma resection without injury to the critical functions.

Adolescent↗
PubMed2000

Orchestrated transcription of key pathways in Arabidopsis by the circadian clock.

Like most organisms, plants have endogenous biological clocks that coordinate internal events with the external environment. We used high-density oligonucleotide microarrays to examine gene expression in Arabidopsis and found that 6% of the more than 8000 genes on the array exhibited circadian changes in steady-state messenger RNA levels. Clusters of circadian-regulated genes were found in pathways involved in plant responses to light and other key metabolic pathways. Computational analysis of cycling genes allowed the identification of a highly conserved promoter motif that we found to be required for circadian control of gene expression. Our study presents a comprehensive view of the temporal compartmentalization of physiological pathways by the circadian clock in a eukaryote.

Arabidopsis↗
PubMed2000

Immunization with recombinant canarypox vectors expressing membrane-anchored glycoprotein 120 followed by glycoprotein 160 boosting fails to generate antibodies that neutralize R5 primary isolates of human immunodeficiency virus type 1.

Antibodies generated by candidate HIV-1 vaccines in a phase I clinical trial were assessed for neutralizing activity with a panel of eight well-characterized, genetically diverse clade B primary isolates having an R5 phenotype. The vaccines consisted of one of three different recombinant canarypox vectors expressing membrane-anchored HIV-1(MN)gp120 (ALVAC vCP205, vCP1433, and vCP1452) followed by boosting with a soluble gp160 hybrid consisting of MNgp120 and the majority of gp41 from strain IIIB. Serum samples from a subset of volunteers in each arm of the trial, containing moderate to high titers of neutralizing antibodies to HIV-1 MN, were analyzed. Competition assays with peptides revealed that the majority of neutralizing activity was specific for the MN-V3 loop. Despite MN-specific neutralization titers that sometimes exceeded 1:500, no neutralization of primary isolates was detected and, in some cases, mild infection enhancement was observed. In addition, little or no neutralization of the HIV-1 IIIB heterologous T cell line-adapted strain of virus was detected. These results reinforce the notion that monovalent HIV-1 ENV is a poor immunogen for generating cross-reactive neutralizing antibodies.

AIDS Vaccines↗
PubMed2000

Negative regulation of the serine/threonine kinase B-Raf by Akt.

B-Raf contains multiple Akt consensus sites located within its amino-terminal regulatory domain. One site, Ser(364), is conserved with c-Raf but two additional sites, Ser(428) and Thr(439), are unique to B-Raf. We have investigated the role of both the conserved and unique phosphorylation sites in the regulation of B-Raf activity in vitro and in vivo. We show that phosphorylation of B-Raf by Akt occurs at multiple residues within its amino-terminal regulatory domain, at both the conserved and unique phosphorylation sites. The alteration of the serine residues within the Akt consensus sites to alanines results in a progressive increase in enzymatic activity in vitro and in vivo. Furthermore, expression of Akt inhibits epidermal growth factor-induced B-Raf activity and inhibition of Akt with LY294002 up-regulates B-Raf activity, suggesting that Akt negatively regulates B-Raf in vivo. Our results demonstrate that B-Raf activity can be negatively regulated by Akt through phosphorylation in the amino-terminal regulatory domain of B-Raf. This cross-talk between the B-Raf and Akt serine/threonine kinases is likely to play an important role in modulating the signaling specificity of the Ras/Raf pathway and in promoting biological outcome.

Amino Acid Sequence↗
PubMed2000

CrkII participation in the cellular effects of growth hormone and insulin-like growth factor-1. Phosphatidylinositol-3 kinase dependent and independent effects.

We have examined the role of CrkII in the cellular response to both human growth hormone (hGH) and human insulin-like growth factor-1 (hIGF-1). We have demonstrated that overexpression of the adaptor molecule enhances both basal phosphatidylinositol 3-kinase (PI 3-kinase) activity and also dramatically enhances the ability of both hormones to stimulate PI 3-kinase activity in the cell. Many of the effects of CrkII overexpression on hGH- and hIGF-1-stimulated cellular function can then be attributed to CrkII enhancement of PI 3-kinase stimulation by these hormones. Thus, CrkII-enhanced PI 3-kinase activity is used to enhance actin filament reorganization in response to both hGH and hIGF-1, to enhance stress activated protein kinase (SAPK) activity in response to hGH, and to diminish STAT5-mediated transcription in response to hGH. It is apparent, however, that CrkII also regulates cellular function independent of its ability to stimulate PI 3-kinase activity. This is evidenced by the ability of CrkII, in a PI 3-kinase-independent manner, to diminish the activation of p44/42 mitogen-activated protein kinase in response to both hGH and hIGF-1 and to inhibit the activation of SAPK by hIGF-1. Therefore, despite the common use of CrkII to activate PI 3-kinase, CrkII also allows hGH or hIGF-1 to selectively switch the activation of SAPK. Thus, common utilization of CrkII by hGH and hIGF-1 allows the execution of common cellular effects of these hormones, concomitant with the retention of hormonal specificity.

3T3 Cells↗
PubMed2000

Janus kinase 2-dependent activation of p38 mitogen-activated protein kinase by growth hormone. Resultant transcriptional activation of ATF-2 and CHOP, cytoskeletal re-organization and mitogenesis.

We demonstrate here that p38 mitogen-activated protein (MAP) kinase is activated in response to cellular stimulation by human GH (hGH) in Chinese hamster ovary cells stably transfected with GH receptor cDNA. This activation requires the proline-rich box 1 region of the GH receptor required for JAK2 association and is prevented by pretreatment of cells with the JAK2-specific inhibitor AG490. ATF-2 is both phosphorylated and transcriptionally activated by hGH, and its transcriptional activation also requires the proline-rich box 1 region of the GH receptor. Expression of wild type JAK2 can further enhance hGH-induced ATF-2-, CHOP-, and Elk-1-mediated transcriptional activation, whereas pretreatment with AG490 is inhibitory. Use of either specific pharmacological inhibitors or transient transfection of cells with p38alpha MAP kinase cDNA or a dominant negative variant demonstrated that hGH-stimulated transcriptional activation of ATF-2 and CHOP, but not Elk-1, is regulated by p38 MAP kinase. Both the p38 MAP kinase and p44/42 MAP kinase are critical for hGH-stimulated mitogenesis, whereas only p38 MAP kinase is required for hGH-induced actin cytoskeletal re-organization. p38 MAP kinase is therefore an important regulator in coordinating the pleiotropic effects of GH.

Activating Transcription Factor 2↗
PubMed2000

Induction of Ro/SSA antigen expression on keratinocyte cell membrane by heat shock and phorbol 12-myristate 13-acetate as well as estradiol and ultraviolet B.

Skin is one of the main target organs in lupus erythematosus and in some circumstances, skin lesions precede systemic manifestations. Previous studies have demonstrated that Ro/SSA antigen antibody might be involved in the pathogenesis of lupus erythematosus. The present study was performed to investigate the factors regulating expression of Ro/SSA antigens on the cell surface of keratinocytes. Cultured normal human keratinocytes were treated with 50-200 mJ/cm(2) of ultraviolet B (UVB) irradiation, 10(-9) to 10(-5) mol/l of 17beta-estradiol, 5-10 microg/l of phorbol 12-myristate 13-acetate (PMA), and 42 and 45 degrees C heat shock, respectively. The Ro/SSA antigen expressions were determined by indirect immunofluorescence. The results showed that keratinocytes receiving UVB irradiation expressed Ro/SSA antigen on cell membranes in a dose-dependent fashion. 17beta-estradiol treatment also induced Ro/SSA antigen expression dose-dependently. Keratinocyte expression of Ro/SSA antigens was also induced by heat shock stimulation. The 45 degrees C heat shock showed a stronger effect than 42 degrees C heat shock. Keratinocytes incubated for 24 h after heat shock had more antigen-expressing cells than those incubated for 6 h after heat shock. PMA at 5 and 10 microg/l also strongly induced Ro/SSA antigen expression. These results suggest that Ro/SSA antigen expression can be regulated by many factors and that protein kinase C signal transduction pathway might be involved in this process.

Autoantigens↗
PubMed2000

Growth hormone, insulin-like growth factor I and the CNS: localization, function and mechanism of action.

The growth hormone (GH) receptor and binding protein are synthesized in the CNS and are regulated differentially to their hepatic counterparts. GH is also synthesized in the CNS and is regulated differentially to its hypophyseal counterpart. Insulin-like growth factor I (IGF-I) is synthesized in the CNS and in the early postnatal period is regulated by peripherally secreted GH. Both GH and IGF-I alter the size and morphology of the CNS during development and affect differentiated cell function in the CNS, with consequent modulation of cognitive function. Differential utilization of the same signal transduction molecules indicates that GH and IGF-I possess distinct overlapping roles in CNS function.

Animals↗
PubMed2000

Differential recognition of ACE inhibitors in Xenopus laevis oocytes expressing rat PEPT1 and PEPT2.

PURPOSE: To examine the mechanism of inhibition of glycylsarcosine (GlySar) transport by quinapril and enalapril, and whether or not angiotensin converting enzyme (ACE) inhibitors are transported by PEPT2 as well as by PEPT1. METHODS: Xenopus laevis oocytes were cRNA-injected with rat PEPT1 or PEPT2 and the transport kinetics of radiolabeled GlySar were studied in the absence and presence of quinapril and enalapril. The two-microelectrode voltage-clamp technique was also performed to probe the electrogenic uptake of captopril, quinapril and enalapril. RESULTS: Kinetic analyses demonstrated that quinapril inhibited the uptake of GlySar in a noncompetitive manner in Xenopus oocytes injected with PEPT1 or PEPT2 (Ki = 0.8 or 0.4 mM, respectively). In contrast, a competitive interaction was observed between GlySar and enalapril (Ki = 10.8 mM for PEPT1 or 4.3 mM for PEPT2). Most significantly, captopril and enalapril, but not quinapril, induced inwardly-directed currents in both PEPT1- and PEPT2-expressed oocytes. CONCLUSIONS: These results are unique in providing direct evidence for the substrate recognition and transport of some ACE inhibitors by the high- and low-affinity oligopeptide transporters. Our findings point to differences between PEPT1 and PEPT2 in their affinity to, rather than in their specificity for, ACE inhibitors.

Algorithms↗
PubMed2000

Engineering herbicide-resistant maize using chimeric RNA/DNA oligonucleotides.

Maize plants resistant to imidazolinone herbicides were engineered through targeted modification of endogenous genes using chimeric RNA/DNA oligonucleotides. A precise single-point mutation was introduced into genes encoding acetohydroxyacid synthase (AHAS), at a position known to confer imidazolinone resistance. Phenotypically normal plants from the converted events (C0) were regenerated from resistant calli and grown to maturity. Herbicide leaf painting confirmed the resistance phenotype in C0 plants and demonstrated the anticipated segregation pattern in C1 progeny. DNA cloning and sequencing of the targeted region in resistant calli and derived C0 and C1 plants confirmed the expected mutation. These results demonstrate that oligonucleotide-mediated gene manipulation can be applied to crop improvement. This approach does not involve genomic integration of transgenes. Since the new trait is obtained through modifying a gene within its normal chromosomal context, position effects, transgene silencing, or other concerns that arise as part of developing transgenic events are avoided.

Acetolactate Synthase↗
PubMed2000

Preliminary study on the cleavage of fusion protein GST-CMIV with palladium(II) complex.

A novel method for post-treatment of gene-engineered proteins is reported. A coden of Cys-His unit is introduced into the N-terminal of cecropin CMIV by using PCR. The gene is expressed in E. coli fused with GST. After purification, the fusion protein is cleaved by [Pd(en)(H2O)2]2+ at the His-Arg bond and the cecropin CMIV with antibacterial activity is obtained. The preliminary results held some promise of success for application of the palladium(II) complex as cleavage agent for the production of peptide drugs from gene-engineering fusion proteins.

Anti-Bacterial Agents↗
PubMed2000

Essential functions of protein tyrosine phosphatases PTP2 and PTP3 and RIM11 tyrosine phosphorylation in Saccharomyces cerevisiae meiosis and sporulation.

Tyrosine phosphorylation plays a central role in eukaryotic signal transduction. In yeast, MAP kinase pathways are regulated by tyrosine phosphorylation, and it has been speculated that other biochemical processes may also be regulated by tyrosine phosphorylation. Previous genetic and biochemical studies demonstrate that protein tyrosine phosphatases (PTPases) negatively regulate yeast MAP kinases. Here we report that deletion of PTP2 and PTP3 results in a sporulation defect, suggesting that tyrosine phosphorylation is involved in regulation of meiosis and sporulation. Deletion of PTP2 and PTP3 blocks cells at an early stage of sporulation before premeiotic DNA synthesis and induction of meiotic-specific genes. We observed that tyrosine phosphorylation of several proteins, including 52-, 43-, and 42-kDa proteins, was changed in ptp2Deltaptp3Delta homozygous deletion cells under sporulation conditions. The 42-kDa tyrosine-phosphorylated protein was identified as Mck1, which is a member of the GSK3 family of protein kinases and previously known to be phosphorylated on tyrosine. Mutation of MCK1 decreases sporulation efficiency, whereas mutation of RIM11, another GSK3 member, specifically abolishes sporulation; therefore, we investigated regulation of Rim11 by Tyr phosphorylation during sporulation. We demonstrated that Rim11 is phosphorylated on Tyr-199, and the Tyr phosphorylation is essential for its in vivo function, although Rim11 appears not to be directly regulated by Ptp2 and Ptp3. Biochemical characterizations indicate that tyrosine phosphorylation of Rim11 is essential for the activity of Rim11 to phosphorylate substrates. Our data demonstrate important roles of protein tyrosine phosphorylation in meiosis and sporulation

DNA, Fungal↗