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Biomedical subjects

Z Yin

Publications and source records attributed to Z Yin.

At least 55 records · Page 3Linked to original sources
PubMed2000

Molecular cloning of a carp Jak3 from activated leukocytes.

Janus kinases (Jaks) are involved in a signalling pathway leading to tyrosine phosphorylation, which is the key step in transducing cytokine signals from the external environment to the nucleus. We report here the molecular cloning of carp Jak3. A partial cDNA of the Jak homologue was initially identified from a cDNA pool obtained by subtracting the cDNAs from Con A-induced carp head kidney leukocytes with those from uninduced carp head kidney leukocytes. The entire coding sequence was assembled by sequencing both strands of cDNA clones amplified by using anchored PCR reaction. The complete cDNA was cloned by specific primers designed against the partial cDNAs and then sequenced to assure accuracy of the complete sequence. Sequence analysis reveals an ORF encoding a protein of 1026 amino acids, with the unique presence of two carboxy-terminal kinase and pseudokinase domains. The cDNA clone shows approximately 52-50%, 50-48.2%, 42-39% and 35-39% amino acid identity with the known Jak3s, Jak2s, Jak1s and Tyk2s, respectively. The sequence of the amino acid residues within the N-terminal JH domains of the carp Jak homologue shows higher similarities with the regions of human Jak3 than with human Jak2. The carp Jak is expressed as a single 4. 5Kb transcript at low levels in the head kidney and the spleen, with the RNA level increasing when leukocytes are activated with con A. The trace transcript was also detected by RT-PCR in the carp liver, muscle and skin, but not in the egg sample. Sequence analysis and pattern of expression suggest that this cDNA represents the carp Jak3 (accession number in GenBank: AF148993).

Amino Acid Sequence↗
PubMed2000

Dominance of IL-12 over IL-4 in gamma delta T cell differentiation leads to default production of IFN-gamma: failure to down-regulate IL-12 receptor beta 2-chain expression.

Gamma delta T cells secrete Th1- and Th2-like cytokines that help mediate innate and acquired immunity. We have addressed the mechanism whereby murine gamma delta T cells acquire the capacity to differentially produce such cytokines. Splenic gamma delta T cells could be polarized into IFN-gamma- or IL-4-secreting cells in vitro; however, in contrast to CD4+ alpha beta T cells, gamma delta T cells predominantly produced IFN-gamma, even in the presence of IL-4, a finding independent of genetic background. Like CD4+ Th1 cells, IFN-gamma-producing cells expressed the IL-12 receptor beta 2-chain after activation in the presence of IL-12; however, unlike Th2 cells, IL-4-primed gamma delta T cells also expressed this receptor, even in the absence of IFN-gamma and despite the presence of the transcription factor GATA-3. IL-12 also induced IL-4-primed gamma delta T cells to proliferate and to translocate Stat3/Stat4, indicating signaling through the IL-12 receptor. These molecular events can account for the predominant production of IFN-gamma by gamma delta T cells in the presence of IL-12, despite the availability of IL-4. Early and predominant production of IFN-gamma by gamma delta T cells likely is critical for the roles that these cells play in protection against intracellular pathogens and in tumor immunity.

Animals↗
PubMed2000

Differential post-transcriptional regulation of yeast mRNAs in response to high and low glucose concentrations.

Glucose regulates yeast gene expression at both transcriptional and post-transcriptional levels. Glucose strongly represses the transcription of the gluconeogenic genes, FBP1 and PCK1, and accelerates the degradation of their mRNAs. Together these mechanisms are responsible for the rapid decrease in gluconeogenic enzyme synthesis when yeast cells switch to glycolytic metabolism. In this study, we show that accelerated gluconeogenic mRNA degradation can be triggered by low concentrations of glucose (<0. 02%). This sets the FBP1 and PCK1 mRNAs apart from other glucose-sensitive mRNAs, such as the Ip mRNA, which only responds to high glucose concentrations (>1%). We also show that accelerated gluconeogenic mRNA degradation is co-ordinated with transcriptional repression by common signalling components that include sugar kinases and Ras-cAMP signalling. Furthermore, the ability of the low glucose signal to trigger accelerated gluconeogenic mRNA degradation depends upon the low glucose sensor, Snf3p, but not on the high glucose sensor, Rgt2p. Also, this response is influenced by reg1 and ume5 mutations, but not by grr1 or rgt1 mutations. Our data suggest that several signalling pathways co-ordinate differential post-transcriptional and transcriptional responses in yeast, depending upon the amount of glucose available in the medium.

Base Sequence↗
PubMed2000

Behavioral and cognitive correlates of exercise self-schemata.

The purpose of this study was to examine the relationship of exercise self-schemata to both cognitive and behavioral concomitants including exercise self-efficacy, attitudes toward fitness, self-perceptions of fitness, and self-report of exercise behavior. Participants were 161 undergraduate students who subsequently were categorized into groups defined by the authors as "exercise schematics," "nonexercise schematics," "aschematics," and unclassified. Results indicated that exercise schematics reported greater total caloric expenditure, higher frequency of exercise behavior in the past as well as future expectations to exercise, greater self-perceptions of physical fitness, and more favorable attitudes toward fitness than either nonexercise schematics or aschematics. Furthermore, exercise schematics expressed higher levels of exercise self-efficacy than did nonexercise schematics. The results clearly support earlier findings concerning exercise self-schemata and exercise behavior and further indicate that schematics also differ from others in important cognitive-motivational determinants of exercise such as self-efficacy and perceptions of physical fitness. Future research should define the role of exercise self-schemata both theoretically and practically in order to enrich our understanding of and facilitate the enhancement of exercise adherence.

Adult↗
PubMed2000

Examination of the psychometric properties of the perceived motivational climate in sport questionnaire-2 in a sample of female athletes.

We undertook two studies to determine the validity and reliability of the revised Perceived Motivational Climate in Sport Questionnaire (PMCSQ-2). In Study 1, 201 female athletes (mean age 16.4 years) were administered the initial version of the PMCSQ-2 and a measure of reported tension and pressure experienced in sport. Exploratory principal component analysis suggested that the PMCSQ-2 contained two higher-order scales (Task-Involving and Ego-Involving climates), each with three subscales (Task: Cooperative Learning, Effort/ Improvement, Important Role; Ego: Intra-Team Member Rivalry, Unequal Recognition, Punishment for Mistakes). In Study 2, 385 female volleyball players (mean age 15.2 years) completed the PMCSQ-2, the Intrinsic Motivation Inventory and a measure of Team Satisfaction. Confirmatory factor analysis was applied to six competing models. The oblique six-factor model and oblique hierarchical model provided comparable fit to the data. Acceptable fit was reached based on model respecification. Across Studies 1 and 2, internal consistency was found to be acceptable for the higher-order scales and subscales (with the exception of the Intra-Team Member Rivalry subscale). We found evidence for the concurrent validity of the instrument.

Adolescent↗
PubMed2000

Characterizing rice lesion mimic mutants and identifying a mutant with broad-spectrum resistance to rice blast and bacterial blight.

Many plant mutants develop spontaneous lesions that resemble disease symptoms in the absence of pathogen attack. In several pathosystems, lesion mimic mutations have been shown to be involved in programmed cell death, which in some instances leads to enhanced disease resistance to multiple pathogens. We investigated the relationship between spontaneous cell death and disease resistance in rice with nine mutants with a range of lesion mimic phenotypes. All nine mutations are controlled by recessive genes and some of these mutants have stunted growth and other abnormal characteristics. The lesion mimics that appeared on the leaves of these mutants were caused by cell death as measured by trypan blue staining. Activation of six defense-related genes was observed in most of the mutants when the mimic lesions developed. Four mutants exhibited significant enhanced resistance to rice blast. One of the mutants, spl11, confers non-race-specific resistance not only to blast but also to bacterial blight. The level of resistance in the spl11 mutant to the two pathogens correlates with the defense-related gene expression and lesion development on the leaves. The results suggest that some lesion mimic mutations in rice may be involved in disease resistance, and cloning of these genes may provide a clue to developing broad-spectrum resistance to diverse pathogens.

Bacteria↗
PubMed2000

Response to methotrexate in early rheumatoid arthritis is associated with a decrease of T cell derived tumour necrosis factor alpha, increase of interleukin 10, and predicted by the initial concentration of interleukin 4.

OBJECTIVE: This study was performed to assess whether there is any change in the T cell cytokine pattern in early rheumatoid arthritis (RA) patients treated with methotrexate (MTX) and whether the lymphocytic cytokine pattern correlates with disease activity. METHODS: Eight patients with RA (disease duration < six months) were studied serially before, after three, and after six to nine months of treatment with MTX for the cytokines tumour necrosis factor alpha (TNFalpha), interferon gamma (IFNgamma), interleukin 4 (IL4) and interleukin 10 (IL10) by intracellular staining of T cells derived from peripheral blood. Response to treatment was assessed by the modified disease activitiy score. RESULTS: The clincial response was accompanied by a significant decrease of TNFalpha positive CD4(+) T cells from a median of 8.53% (interquartile range 5.83-10.91%) before treatment to 6.17% (2.15-6.81%) after six to nine months of treatment (p=0.021). Inversely, IL10 positive T cells increased from a median of 0.65% (interquartile range 0.6-0.93%) to a median of 1. 3% (1.22%-1.58%) after six to nine months of treatment (p=0.009). No significant change in the percentage of INFgamma positive T cells and a small decrease of IL4 positive T cells during treatment were observed. The percentage of IL4 positive CD4(+) T cells before treatment correlated with disease activity after six to nine months (r= -0.7066; p=0.05). CONCLUSIONS: During treatment of RA with MTX the percentage of TNFalpha producing T cells decreases whereas that of IL10 producing T cells increases. This may affect macrophage activation and, therefore, may represent a regulatory mechanism relevant to disease remission. Furthermore, the percentage of IL4 positive CD4(+) T cells at disease onset may be a useful prognostic marker.

Antirheumatic Agents↗
PubMed2000

[Molecular cytogenetics study in a case with unbalanced chromosome translocation].

OBJECTIVE: To analyze the chromosome structural aberration in a case of unbalanced chromosome translocation by fluorescence in situ hybridization technique. METHODS: The 1,18 whole chromosome specific painting probe were used to confirm chromosome abnormality suggested by high resolution G-banding examination. RESULTS: An unbalanced translocation t(1;18)(q42;q22) was detected in the patient, which caused partial trisomy of 1q42-qter and partial monosomy of 18q22-qter. CONCLUSION: The identified translocation suggested a potential site for congenital heart disease.

Heart Defects, Congenital↗
PubMed2000

Acute oxygen supplementation restores markers of hepatocyte energy status and hypoxia in cirrhotic rats.

The oxygen limitation hypothesis states that hepatocyte hypoxia is the mechanism determining metabolic restriction in the cirrhotic liver. Therefore we studied markers of hepatocyte energy state and cellular hypoxia in livers of normal and cirrhotic rats before and after oxygen supplementation. Rats with carbon tetrachloride-induced cirrhosis and procedural control rats were exposed to either room air or a hyperoxic gas mixture for 1 h immediately before freeze clamping and perchloric acid extraction of liver tissue. Extracts were assessed by (31)P NMR and enzymatic assays. Livers from cirrhotic rats breathing room air showed a reduced ratio of ATP/ADP, an increased ratio of inorganic phosphate/ATP, and a trend toward an increased ratio of lactate/pyruvate compared with procedural control livers (ATP/ADP 1.73 +/- 0.35 versus 2.68 +/- 0.61, P <.05; P(i)/ATP 2.74 +/- 0.48 versus 1.56 +/- 0.26, P <.05; lactate/pyruvate 29.3 +/- 6.4 versus 22.5 +/- 7.4, P =.18). After supplementation with oxygen for 1 h, these ratios in cirrhotic livers approached control values. A variety of other metabolic markers affected by cirrhosis showed variable trends toward normal in response to oxygen supplementation, whereas minor trends toward an increase in ATP levels in control animals suggest the possibility of marginal oxygen limitation in normal livers. The data are consistent with the hypothesis that hepatocytes in cirrhotic livers have normal metabolic capacity but are constrained by a deficit in oxygen supply. Interventions aimed at increasing oxygen supply to the liver may have both short- and long-term therapeutic value in the management of cirrhosis.

Animals↗
PubMed2000

[Expression and characterization of HIV-1 Gag p17-p24 protein].

The biological and immunological characteristics of HIV-1 core protein p17-24 expressed by recombinant vaccinia viruses were studied. The results of indirect immunofluorescence assay (I-IFA), Western blot and dot ELISA showed that the two recombinants could express the p24 gag and p17-24 gag fusion proteins in infected cell lines respectively. The electromicroscope observation revealed that the expressed proteins could also assemble into virus-like particles. The recombinant vaccinia viruses can also stimulate mice for the formation of anti HIV-1 Gag p24 antibody. When infected with the recombinant viruses, the chromosome DNA ladder caused by the apoptosis of the BHK cell was observed.

Animals↗
PubMed2000

[The development and application of a minitype multifunctional bio-impactor].

This study was aimed to develop a device that can be used for gas percussion, rigid impact, cell injury and simple estimation of the condition of injury. The device has been developed with the use of aerodynamical principle, measuring technique for feeble signal, and integration of machine-electricity. The gas percussion, rigid impact, and cell injury can be produced by altering impact tip. It was examined in the experimental researches of eye, brain, lung and cell injury; the parameters of causing injury could be controlled and on-line tested by the computer. The neurological states of pre- and post-injury were evaluated with the device. The results of animal experiments showed that mild, moderate and severe injury models were produced by gas pressure respectively. The pressure was 400, 600, 700 kPa for rats brain gas percussion injury, 600, 800, 1000 kPa for rabbits' retinal contusion, 300, 450, 600 kPa for rats' lung rigid impact injury, and 100, 150, 200 kPa for cultured cells' injury. In conclusion, the device is simple and easy to use for making controllable injury models, in which different parts and levels of injuries on different minitype animals can be reproduced.

Animals↗
PubMed2000

[Spectroscopy performances of Yb3+ doped YAG crystal].

The absorption and emission properties of Yb:YAG with different Yb3+ doped concentration have been studied systematically. The emission cross section has been evaluated using the absorption cross section and principle of reciprocity, which was consistent with previous reports. The absorption spectra of Yb2+ and color center were observed in as-grown Yb:YAG boules, which are removed by annealing the boules in oxygen at 1,300 degrees C for 24 h. The photon excited and X-ray excited optical luminescence of Yb:YAG were first discussed. The results indicated that Yb:YAG crystal was favourable for high-power diode-pumping.

Chemical Phenomena↗
PubMed1999

Limiting the location of a putative human prostate cancer tumor suppressor gene at chromosome 13q14.3.

We studied loss of heterozygosity (LOH) on human chromosome 13q in prostate cancer specimens to determine the location of a putative tumor suppressor gene (TSG) and to correlate these losses with the clinicopathological stage of the disease. Overall 13 (21%) of 61 specimens analysed had an allele loss on the long arm of chromosome 13. The most frequent (37%) LOH among the informative cases with allele losses was detected at the D13S284 locus on chromosome 13q14. 3. A portion of the DNA segment that spans this locus and is flanked by the microsatellite loci D13S153 and D13S163 was lost in 85% of the specimens with allele losses and was designated as a LOH cluster region (LCR). The LCR spans more than 6 Mbp of DNA. The results suggest that a TSG relevant for the development of prostate cancer is located telomeric to the RB locus. There was a significant correlation (P=0.0024) between chromosome 13q LOH and advanced metastatic disease, suggesting that loss of 13q14.3 region is associated with prostate cancer progression. However, further research must be conducted to establish the identity and function of this putative TSG.

Chromosome Mapping↗
PubMed1999

Role of redox potential and reactive oxygen species in stress signaling.

Stress-activated signaling cascades are affected by altered redox potential. Key contributors to altered redox potential are reactive oxygen species (ROS) which are formed, in most cases, by exogenous genotoxic agents including irradiation, inflammatory cytokines and chemical carcinogens. ROS and altered redox potential can be considered as the primary intracellular changes which regulate protein kinases, thereby serving as an important cellular component linking external stimuli with signal transduction in stress response. The mechanisms, which underlie the ROS-mediated response, involve direct alteration of kinases and transcription factors, and indirect modulation of cysteine-rich redox-sensitive proteins exemplified by thioredoxin and glutathione S-transferase. This review summarizes the current understanding of the mechanisms contributing to ROS-related changes in key stress activated signaling cascades.

Animals↗