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Biomedical subjects

S Gu

Publications and source records attributed to S Gu.

100 records · Page 6Linked to original sources
PubMed1992

[A study of genetic polymorphism of isozymes in natural populations of Drosophila virilis in east China].

A study of genetic variation at Est-alpha, Est-beta, A my, Acph and alpha-Gpdh loci in local samples of Hefei, Wuhu, Jiujiang, Nanchang, Changzhou, Fuzhou and Quanzhou Drosophila virilis population is presented. The employment of standard techniques of polyacrylamide electrophoresis and agarose electrophoresis reveals that the former three loci are highly polymorphic in all these populations. According to the allelic frequency of the 5 loci, a genetic distance between the above-mentioned populations was calculated. Along with the results obtained by Mr He Chaozheng from Hongze, Nanjing, Hangzhou and Ningbo populations, a dendrogram was made. It was found that Quanzhou and Fuzhou populations differed from the others in allelic frequencies and genetic distances which suggests that this difference is related to the extent of geographic isolation among them.

Animals↗
PubMed1991

Digital angiographic impulse response analysis of regional myocardial perfusion. Estimation of coronary flow, flow reserve, and distribution volume by compartmental transit time measurement in a canine model.

A system impulse response function that describes the kinetics of radiographic contrast material transit through the coronary circulation was calculated from 175 selective digital angiograms of normal and stenotic arteries in 10 dogs during rest and hyperemia. The goal of the study was to determine if the flow and distribution volume characteristics of the epicardial coronary arteries and the myocardial microcirculation could be stimulated by specific mathematical compartments of a lagged normal density model impulse response function in which the flow/distribution volume ratio is the inverse of the mean transit time. The arterial compartment mean transit time correlated with flow (r = 0.75); however, the correlation was significantly improved in individual dogs (r = 0.83 +/- 0.13; p less than 0.005) and was highly dependent on the length of the conduit vessel. The microcirculation compartment mean transit time was distributed as two populations with respect to flow. There was a linear correlation during hyperemia (r = 0.87) and a nonlinear relation during rest, which was characteristic of an autoregulating system. Resting values of microcirculation compartment mean transit time correlated with coronary flow reserve (r = 0.84) and differed significantly between vessels that were normal and those with subcritical stenosis, critical stenosis, or total occlusion (p less than 0.01 for all comparisons). The estimated microcirculation compartment distribution volume increased from a minimum of 4.0 +/- 1.5 ml/100 g myocardium in normal vessels with resting flow to 11.2 +/- 3.5 ml/100 g during hyperemia. These data suggest that the model compartments functionally describe the physiological behavior of their anatomic analogues and permit the quantification of microcirculatory autoregulation from a single measurement at rest without provoking hyperemia.

Algorithms↗
PubMed1991

Effect of low-molecular-weight heparin on recombinant tissue plasminogen activator-induced thrombolysis in canine pulmonary embolism.

We employed a canine model of pulmonary embolism induced by radioactive blood clots to determine if low-molecular-weight heparin augments recombinant tissue plasminogen activator (rtPA)-induced thrombolysis. Following embolization, dogs were randomized: group 1 dogs received heparin; group 2 dogs received low-molecular-weight heparin; group 3 dogs received 1.5 mg/kg of rtPA over 45 minutes; group 4 dogs received rtPA 3 mg/kg over 45 minutes; and group 5 dogs received 1.5 mg/kg of rtPA plus low-molecular-weight heparin. Over three hours, little thrombolysis occurred in groups 1 and 2. In contrast, significant thrombolysis occurred in groups 3 to 5, 46 percent, 49 percent, and 46 percent, respectively (all p less than 0.01 compared with groups 1 and 2). We conclude that there is an upper limit to the dose-thrombolytic rate relationship with rtPA, and that low-molecular-weight heparin does not augment rtPA-induced thrombolysis.

Animals↗
PubMedDate not supplied

Sex, marital status, and psychological distress in later life: a comparative analysis.

Some investigators maintain that while married men experience less distress than married women, the opposite may be true for those who are not married. In this instance, women are thought to report fewer symptoms of distress than men. The purpose of this study is to examine the relationships among gender, marital status, psychological distress and alcohol use in five culturally-diverse groups of older adults: U.S. whites, U.S. blacks, Japanese, Taiwanese and elderly people in the People's Republic of China. We find little evidence of the pattern described above. Instead, the data suggest that being single is equally detrimental for older men and women regardless of the cultural setting.

Journal Article↗
PubMedDate not supplied

Premeiotic clusters of mutation and the cost of natural selection.

Haldane stated that there is a cost of natural selection for new beneficial alleles to be substituted over time. Most of this cost, which leads to "genetic deaths," is in the early generations of the substitution process when the new allele is low in frequency. It depends on the initial frequency and dominance value, but not the selection coefficient, of the advantageous allele. There have been numerous suggestions on how to reduce the cost for preexisting genetic variation that goes from disadvantageous, or neutral, to advantageous with a change in the environment. However, the cost of natural selection for new alleles that arise by mutation is assumed to be high, based on the assumption that new mutant alleles arise in natural populations as single events [1/(2N) of the total alleles]. However, not all mutant alleles arise as single events. Premeiotic mutations occur frequently in individuals (germinal mosaics), giving rise to multiple copies of identical mutant alleles called a "cluster" (C) with an initial allele frequency of C/(2N) instead of 1/(2N). These clusters of new mutant alleles reduce the cost of natural selection in direct proportion to the relative size of the cluster. Hence new advantageous alleles that arise by mutation have the greatest chance of going to fixation if they occur in large clusters in small populations.

Computer Simulation↗
PubMedDate not supplied

[Identification of a novel human MAST4 gene, a new member of the microtubule associated serine-threonine kinase family].

Human protein kinases make up a large superfamily of homologous proteins, which are related by virtue of their kinase domains (also known as catalytic domains). Here we report the cloning and characterization of a novel human MAST4 (microtubule associated serine/threonine kinase family member 4) gene, which locates on human chromosome 5q13. The MAST4 cDNA is 7587 base pairs in length and encodes a putative protein of 2435 amino acids which contains a serine/threonine kinase domain and a PDZ domain. MAST4 protein has 64%, 63%, 59% and 39% identical aminoacid residues with MAST1, MAST2, MAST3 and MASTL respectively. RT-PCR analysis revealed relatively high expression level of MAST4 in most normal human tissues, with an exception of in testis, small intestine, colon and peripheral blood leukocyte.

Amino Acid Sequence↗
PubMedDate not supplied

Digital subtraction angiography in the diagnosis of congenital heart diseases: analysis of 60 cases.

Ninety-one IVDSA and/or IADSA examinations with 192 injections were performed in 60 patients with congenital heart disease (CHD), including 31 anatomic anomalies. Axial projection was used in 23 patients. Analysis of the results of this series showed that accurate diagnosis by DSA confirmed by cardiac surgery together with definite diagnosis by DSA were obtained in 54 cases (90%). Two cases of nondiagnosis by DSA resulted from a suboptimal DSA method; four cases of partially accurate or mistaken diagnosis determined by cardiac surgery occurred because the axial view was not used and/or the anomalies were too small to be visualized by DSA. To increase the diagnostic accuracy of DSA in CHD, an optimal method of DSA must be selected according to the position of the anomaly and the hemodynamic data, and the axial view should be used to visualize the anomaly clearly in complex cases. In addition, DSA may fail to define a mild anomaly because of its lower spatial resolution.

Adolescent↗