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Biomedical subjects

Z Guo

Publications and source records attributed to Z Guo.

At least 145 records · Page 8Linked to original sources
PubMed2000

Response of Xenopus Cds1 in cell-free extracts to DNA templates with double-stranded ends.

Although homologues of the yeast checkpoint kinases Cds1 and Chk1 have been identified in various systems, the respective roles of these kinases in the responses to damaged and/or unreplicated DNA in vertebrates have not been delineated precisely. Likewise, it is largely unknown how damaged DNA and unreplicated DNA trigger the pathways that contain these effector kinases. We report that Xenopus Cds1 (Xcds1) is phosphorylated and activated by the presence of some simple DNA molecules with double-stranded ends in cell-free Xenopus egg extracts. Xcds1 is not affected by aphidicolin, an agent that induces DNA replication blocks. In contrast, Xenopus Chk1 (Xchk1) responds to DNA replication blocks but not to the presence of double-stranded DNA ends. Immunodepletion of Xcds1 (and/or Xchk1) from egg extracts did not attenuate the cell cycle delay induced by double-stranded DNA ends. These results imply that the cell cycle delay triggered by double-stranded DNA ends either does not involve Xcds1 or uses a factor(s) that can act redundantly with Xcds1.

Amino Acid Sequence↗
PubMed2000

Mild cognitive impairment in the population and physical health: data on 1,435 individuals aged 75 to 95.

BACKGROUND: The physical health correlates of mild cognitive impairment (MCI) in the older individual are poorly known. The aim of this study was to investigate the relationship between physical health and MCI with population data. METHODS: Subjects were 1,435 nondemented 75- to 95-year-old subjects. MCI was defined as scoring one standard deviation below age- and education-specific means on the Mini-Mental State Examination. MCI was consistently associated with indicators of poorer health in logistic regression models with adjustment for potential confounders. RESULTS: The adjusted odds ratios for those with two, three, four, or more somatic symptoms compared with those with one or no symptoms were 1.3 (95% confidence intervals 1.0 to 1.9) and 2.1 (1.2 to 4.5; p for trend =.004); for those with poor self-rated health the odds ratio was 1.9 (1.4 to 2.6); for those with one, two, or more chronic diseases compared with those with no chronic diseases, the odds ratios were 1.3 (0.9 to 1.9) and 3.0 (1.2 to 7.6; p for trend =.02); and for those dying during the 3-year follow-up period the odds ratio was 1.5 (1.1 to 2.2). CONCLUSIONS: MCI is associated with poor physical health, leading to the hypothesis of a causal relationship between physical diseases and MCI in older populations.

Aged↗
PubMed2000

ALS-linked Cu/Zn-SOD mutation impairs cerebral synaptic glucose and glutamate transport and exacerbates ischemic brain injury.

Although degeneration of lower motor neurons is the most striking abnormality in amyotrophic lateral sclerosis (ALS), more subtle alterations may occur in the brain. Mutations in copper/zinc superoxide dismutase (Cu/Zn-SOD) are responsible for some cases of inherited ALS, and expression of mutant Cu/Zn-SOD in transgenic mice results in progressive motor neuron loss and a clinical phenotype similar to that of ALS patients. It is now reported that Cu/Zn-SOD mutant mice exhibit increased vulnerability to focal ischemic brain injury after transient occlusion of the middle cerebral artery. Levels of glucose and glutamate transport in cerebral cortex synaptic terminals were markedly decreased, and levels of membrane lipid peroxidation were increased in Cu/Zn-SOD mutant mice compared to nontransgenic mice. These findings demonstrate that mutant Cu/Zn-SOD may endanger brain neurons by a mechanism involving impairment of glucose and glutamate transporters. Moreover, our data demonstrate a direct adverse effect of the mutant enzyme on synaptic function.

Amyotrophic Lateral Sclerosis↗
PubMed2000

4,5-Diazafluoren-9-ol.

The title compound, C(11)H(8)N(2)O, has two crystallographically independent molecules in the crystal. Each molecule is basically planar except for the O atom. The two N atoms in the molecule show different behaviour as hydrogen-bonding acceptors. One of them is involved in intermolecular O-H.N hydrogen bonds which stabilize the crystal packing.

Journal Article↗
PubMed2000

Integration of modeling and acoustic microscopy measurements for thin films

A model for measuring the V(z) curve by line-focus acoustic microscopy contains the reflectance function of the specimen as a principal component. In this paper the reflectance function has been analyzed for multilayered thin films on a substrate for both fast-on-slow and slow-on-fast systems. The phase velocities of modes of surface acoustic wave propagation and their associated mode reflection coefficients can be obtained from the reflectance function. This information can be used together with estimates of the elastic constants to determine suitable frequency ranges for measuring the V(z) curve. Minimization of the difference between phase velocities obtained from measured and calculated V(z) curves is used to determine the elastic constants. Results are presented for TiN films on M2 high-speed steel substrates.

Journal Article↗
PubMed2000

The role of nuclear cap binding protein Cbc1p of yeast in mRNA termination and degradation.

The cyc1-512 mutation in Saccharomyces cerevisiae causes a 90% reduction in the level of iso-1-cytochrome c because of the lack of a proper 3'-end-forming signal, resulting in low levels of eight aberrantly long cyc1-512 mRNAs which differ in length at their 3' termini. cyc1-512 can be suppressed by deletion of either of the nonessential genes CBC1 and CBC2, which encode the CBP80 and CBP20 subunits of the nuclear cap binding complex, respectively, or by deletion of the nonessential gene UPF1, which encodes a major component of the mRNA surveillance complex. The upf1-Delta deletion suppressed the cyc1-512 defect by diminishing degradation of the longer subset of cyc1-512 mRNAs, suggesting that downstream elements or structures occurred in the extended 3' region, similar to the downstream elements exposed by transcripts bearing premature nonsense mutations. On the other hand, suppression of cyc1-512 defects by cbc1-Delta occurred by two different mechanisms. The levels of the shorter cyc1-512 transcripts were enhanced in the cbc1-Delta mutants by promoting 3'-end formation at otherwise-weak sites, whereas the levels of the longer cyc1-512 transcripts, as well as of all mRNAs, were slightly enhanced by diminishing degradation. Furthermore, cbc1-Delta greatly suppressed the degradation of mRNAs and other phenotypes of a rat7-1 strain which is defective in mRNA export. We suggest that Cbc1p defines a novel degradation pathway that acts on mRNAs partially retained in nuclei.

Fungal Proteins↗
PubMed2000

Changes in cardiovascular risk factors in different socioeconomic groups: seven year trends in a Chinese urban population.

STUDY OBJECTIVE: To analyse trends in socioeconomic differences in cardiovascular disease risk factors among an urban Chinese population using educational attainment as the socioeconomic indicator. DESIGN: Population surveys with randomly selected independent samples were carried out in 1989 and in 1996. Educational attainment, blood pressure, body mass index, cigarette smoking and lack of leisure time physical activity were determined. SETTING: Urban areas of the city of Tianjin, China. PARTICIPANTS: A total of 14 275 respondents aged 25-64 years. MAIN RESULTS: Diastolic blood pressure increased and the proportion of people without leisure time physical activity decreased in both sexes during the study period. The prevalence of smoking and the number of cigarettes smoked daily increased significantly among men. Smoking decreased in the least educated men and increased in those who had studied at least to college level. Body mass index decreased across all educational strata in women, but blood pressure increased in women with at least college level education. CONCLUSIONS: These data reveal a different picture in trends in the association of education and cardiovascular risk factors from those depicted in developed countries. This highlights the need for an effective intervention programme in the study population.

Adult↗
PubMed2000

Leg free fatty acid kinetics during exercise in men and women.

We previously reported that epinephrine stimulates leg free fatty acid (FFA) release in men but not in women. The present studies were conducted to determine whether the same is true during exercise. Six men and six women bicycled for 90 min at 45% of peak O(2) consumption, during which time systemic and leg FFA kinetics ([9, 10-(3)H]palmitate) were measured. The catecholamine and hormonal responses to exercise were not different in men and women. The baseline systemic and leg palmitate release was 94 +/- 15 vs. 114 +/- 5 micromol/min and 16 +/- 2 and 20 +/- 3 micromol/min, respectively, in men and women [P = nonsignificant (NS)]. Systemic and leg palmitate release increased (both P < 0.001) to 251 +/- 18 vs. 212 +/- 16 micromol/min and 73 +/- 19 vs. 80 +/- 12 micromol/min in men and women, respectively, during the last 30 min of exercise (P = NS, men vs. women). We conclude that the systemic and leg adipose tissue lipolytic response to exercise is not different in nonobese men and women.

Adult↗
PubMed2000

Kinetics of intramuscular triglyceride fatty acids in exercising humans.

UNLABELLED: A pulse ([(14)C]palmitate)-chase ([(3)H]palmitate) approach was used to study intramuscular triglyceride (imTG) fatty acid and plasma free fatty acid (FFA) kinetics during exercise at approximately 45% peak O(2) consumption in 12 adults. Vastus lateralis muscle was biopsied before and after 90 min of bicycle exercise; (3)H(2)O production, breath (14)CO(2) excretion and lipid oxidation (indirect calorimetry) rates were measured during exercise. RESULTS: during exercise, 8.2+/-1.2 and 8.4+/-0.7 micromol x kg(-1) x min(-1) of imTG fatty acids and plasma FFA, respectively, were oxidized according to isotopic measurements. The sum of these two values was not different (P = 0.6) from lipid oxidation by indirect calorimetry (15.4 +/-1.6 micromol x kg(-1) x min(-1)); the isotopic and indirect calorimetry values were correlated (r = 0.79, P<0.005). During exercise, imTG turnover rate was 0.32+/-0.07%/min (6.0+/-2.0 micromol of imTG x kg wet muscle(-1) x min(-1)) and plasma FFA were incorporated into imTG at a rate of 0.7+/-0.1 micromol x kg wet muscle(-1) x min(-1). The imTG pool size did not change during exercise. This pulse-chase, dual tracer appears to be a reasonable approach to measure oxidation and synthesis kinetics of imTG.

Adult↗
PubMed2000

Incidence of dementia in relation to stroke and the apolipoprotein E epsilon4 allele in the very old. Findings from a population-based longitudinal study.

BACKGROUND AND PURPOSE: Both stroke and the apolipoprotein E (APOE) epsilon4 allele increase the risk of dementia. However, the interaction between stroke and APOE on dementia is still unclear. We addressed this topic by using a longitudinal design. METHODS: We followed up a community cohort of 1301 subjects aged >/=75 years, who did not have dementia at baseline. Among them, 92 subjects had a history of stroke (from 3 months to 16 years before baseline interview). After the 3-year follow-up, 224 dementia cases had been diagnosed. During the period of follow-up, 91 subjects had a first occurrence of stroke (incident stroke). The APOE genotype was known for 985 subjects. Cox proportional hazards regression models were constructed to estimate the risk for dementia in terms of relative risks (RRs) for stroke and the APOE epsilon4 allele, with adjustment for age, sex, education, systolic blood pressure, antihypertensive medication use, and heart disease. RESULTS: In the entire study population, RRs for dementia related to history of stroke and incident stroke were 1.7 (95% CI, 1.1 to 2.6) and 2.4 (95% CI, 1.6 to 3.5), respectively, after adjustment for all potential confounders. Subjects with stroke that occurred within 3 years before baseline had RR of 2.4 (95% CI, 1.4 to 4.2), whereas those with stroke occurring >3 years before baseline had RR of dementia of 1.1 (95% CI, 0.6 to 2.3). Among those with APOE information, individuals with only history of stroke (that occurred within 3 years before baseline) had RR of 3.1 (95% CI, 1.4 to 6.6), individuals with only the APOE epsilon4 allele had RR of 1.7 (95% CI, 1.1 to 2.5), and individuals with both factors had RR of 5.3 (95% CI, 2.1 to 13.4). The corresponding figures when incident stroke was examined instead of history of stroke were 2.3 (95% CI, 1.3 to 4.1), 1.7 (95% CI, 1.1 to 2.4), and 4.6 (95% CI, 2.0 to 10.6), respectively. The RR of interaction term for history of stroke and APOE epsilon4 was 1.1 (95% CI, 0.3 to 3.8; P=0.8). The corresponding figure was 1.2 (95% CI, 0.4 to 4.4; P=0.7) for incident stroke and APOE epsilon4. Furthermore, the RRs of dementia without any stroke and dementia with stroke in relation to APOE epsilon4 were 1.6 (95% CI, 1.1 to 2.3) and 1.2 (95% CI, 0.6 to 2.4), respectively. In addition, the APOE epsilon4 allele was not significantly related to the occurrence of stroke (RR=0.8; 95% CI, 0.5 to 1.5). CONCLUSIONS: A relatively fresh stroke is a risk factor for dementia. APOE epsilon4 increases the risk of dementia without stroke but not dementia with stroke. Our data do not support a multiplicative effect of stroke and the APOE epsilon4 allele on the risk of dementia. However, both factors seem to have an additive effect on the risk of dementia. The APOE epsilon4 allele does not increase the risk of stroke in this Swedish elderly population.

Aged↗
PubMed2000

Comparison of two kinds of methods to determine the titer of recombinant retrovirus containing beta-globin gene based on G418 selection.

Four recombinant retrovirus (RV) vectors containing human beta-globin gene and regulatory elements were constructed. To determine the titers of recombinant RV from corresponding producer cell lines, we compared two kinds of method (the simple and the conventional) based on G418 resistance, which is conferred by neo gene of RV vector. The results demonstrated that the simple method shortened the selection period to 3 d instead of 10-12 d with the conventional method and reduced the amount of work; importantly, the titers determined by the simple method were not different significantly from those measured by the conventional method. It can be concluded that the simple method can be used to determine the titers of recombinant RV containing not only cDNA but also genomic DNA with introns and complex regulatory elements instead of the conventional method.

3T3 Cells↗
PubMed2000

The effect of zhu yu hua tan tang on intracranial pressure in case of acute cerebral hemorrhage.

The therapeutic effect of Zhu Yu Hua Tan Tang ([symbol: see text] Decoction for removing blood stasis and resolving phlegm) plus general and modern treatment on acute cerebral hemorrhage in 44 cases, and the pressure-lowering effect of Zhu Yu Hua Tan Tang and mannitol in 20 cases of acute cerebral hemorrhage in the basilar region, and in rabbits with experimental encephaledema induced by injection of olive oil into the common carotid artery were observed in this study. The results showed that Zhu Yu Hua Tan Tang plus general treatment can better improved the conscious state of the patients than western medicine, and it can make the intracranial pressure drop clinically by 40.44%. The intracranial pressure-lowering effect of Zhu Yu Hua Tan Tang, though slow, is smooth and long-lasting without any rebound phenomenon, as compared to those of mannitol. Similar results were found in animal experiments, but the intracranial pressure-lowering amplitude of Zhu Yu Hua Tan Tang was stronger than that of mannitol. The difference between the clinical and experimental results needs to be further studied.

Aged↗
PubMed2000

Study on polymorphism of MICA exon 5 microsatellite in Shanghai Han population.

OBJECTIVE: To investigate the polymorphism distribution of MICA gene exon 5 microsatellite in Shanghai Han population and study the relationship of MICA gene and its closely linked gene HLA B. METHODS: The microsatellite polymorphism of MICA exon 5 in 175 unrelated healthy individuals were investigated using PCR-heteroduplex analysis. RESULTS: (1)There are 5 alleles of the microsatellite polymorphism in exon 5 of the MICA gene in Shanghai Han population, the gene frequency of MICA*A5 is the highest(39.14%), the next is MICA*A5.1(22.29%). (2)There is strong linkage disequilibrium between the HLA-B and MICA STR loci, e.g. MICA*A5 and HLA-B15, MICA*A4 and HLA-B27. CONCLUSION: The polymorphism distribution of MICA gene and the linkage disequilibrium between MICA and HLA-B have deviations in different ethnic groups.

China↗
PubMed2000

Associations between socioeconomic status and cardiovascular risk factors in an urban population in China.

INTRODUCTION: In developed countries socioeconomic status has been proven to be an important factor in the progression of cardiovascular disease. The present article reports the results of a cross-sectional assessment to investigate the association between socioeconomic status and cardiovascular risk factors in a Chinese urban population. METHODS: In 1996, a behavioural risk factor survey was carried out in Tianjin, the third largest city in China. A sample of 4000 people aged 15-69 years, stratified by sex and 10-year age groups, was drawn randomly from urban areas of the city. The present study covers respondents aged 25-69 years (1615 men and 1592 women). Four socioeconomic indicators (education, occupation, income, and marital status), blood pressure, body mass index, and cigarette smoking were determined in the survey. RESULTS: Educational level seemed to be the most important measure of the four socioeconomic indicators in relation to the cardiovascular risk factors in the study population. People with lower socioeconomic status had higher levels of cardiovascular risk factors. The association between socioeconomic status and cardiovascular risk factors was more consistent among women than men. DISCUSSION: Our findings do not seem to differ from those observed in developed countries.

Adolescent↗
PubMed2000

[The multimedia molecular biological image processing system].

With the use of computer image processing technology and molecular biological technology, we have developed a new multimedia molecular biological information processing system to detect the characteristic parameter of molecular biological electrophoresis image. The system can determine the macromolecules densities and molecular weight of the DNA amplified fragment or restriction endonuclease hydrolytic fragment protein and other macromolecules. The clinical use and biological application indicate that the system is useful to gene diagnosis and molecular biological researches.

Computational Biology↗