Search PubMed⌕ Search

Biomedical subjects

T Yabe

Publications and source records attributed to T Yabe.

At least 73 records · Page 4Linked to original sources
PubMed1998

Human lymphocytes obtained from decidual tissue express killer activatory receptors as well as killer inhibitory receptors: analysis using a single strand conformation polymorphism method.

PROBLEM: The objective was to clarify whether lymphocytes in decidual tissue express only killer inhibitory receptors (KIRs) or both KIRs and killer activatory receptors (KARs). METHOD OF STUDY: A polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis method, using cDNA as a template, was applied to detect as many natural killer receptors (NKRs) expressed on natural killer (NK) cells as possible and to distinguish between KIRs and KARs. Using this method, we analyzed NKRs on lymphocytes in decidual tissue and maternal peripheral blood mononuclear cells (PBMCs) (n = 10) from the same individuals. RESULTS: More than 20 SSCP bands were detected for NKRs on both the lymphocytes in decidual tissue and the maternal PBMCs. The SSCP band patterns were different for each individual. KARs mRNA was detected in lymphocytes in decidual tissue according to the SSCP analysis results. CONCLUSION: Lymphocytes in decidual tissue express not only KIRs but also KARs; this finding suggests their roles in placentation and the maintenance of pregnancy.

Abortion, Induced↗
PubMed1998

[Blood pressure and diastolic function in the elderly].

To evaluate the relation between blood pressure and diastolic function in the elderly, 28 apparently healthy volunteers underwent blood pressure measurements, echocardiographic examinations, and radionuclide angiography acquired in list mode. Casual blood pressure did not correlate with diastolic indices measured either by echocardiography or by a radionuclide method, except for peak filling rate during atrial contraction assessed by radionuclide angiography (r = 0.39, p < 0.05). Ambulatory blood pressure monitoring revealed significant correlations between peak filling rate during atrial contraction assessed by radionuclide angiography and blood pressure measured over 24 hours, while awake and during sleep. The time to peak filling rate and the velocity of early diastolic filling were found to correlate with blood pressure, but the best correlation was between blood pressure during sleep and peak filling rate during atrial contraction (r = 0.53, p < 0.005). These results show a direct relation between blood pressure and diastolic function in the elderly, which is stronger during sleep than during wakefulness.

Aged↗
PubMed1998

[Assessment of exercise-induced silent myocardial ischemia by dipyridamole thallium imaging: (1). Its significance in stable angina pectoris].

To assess the clinical significance of silent myocardial ischemia (SMI) in the elderly, 113 patients with stable angina who showed ischemic ST depression during treadmill stress testing were studied by dipyrimadole thallium imaging and coronary arteriography. They were divided into two groups: 44 patients with silent ST depressions and 69 patients with painful ST depressions. The groups were compared for scintigraphic and coronary arteriographic features as well as prognosis. There was a significantly greater proportion of older patients (> or = 65 years) in the group with SMI (64%) than in the group with painful ischemia (38%) (p < 0.01), although there was no difference in the mean ages of the two groups. The prevalence of multivessel coronary stenosis was not significantly different between the two groups (45% in the SMI group and 61% in the group with painful ischemia). Treadmill stress testing showed no differences in exercise duration, maximal heart rate, maximal systolic blood pressure, or maximal ST depression between the two groups. Dipyrimadamole thallium imaging revealed similar results in the site of reversible defects (RD), i.e. 76% in the anterior area and 24% in the inferior area in patients with SMI, and 83% in the anterior area and 17% in the inferior area in patients with painful ischemia. However, the size of RD was significantly smaller in patients with SMI, i.e. 14.6 +/- 6.1 segments in patients with SMI and 18.7 +/- 8.3 segments in patients with painful ischemia (p < 0.05). Although a significantly higher proportion of patients with painful ischemia (48%) underwent PTCA or CABG as their initial therapy as compared to those with SMI (16%), there was no significant difference in the cardiac event rate between the two groups initially treated medically. Among patients with stable angina, those with SMI may have a smaller amount of ischemic myocardium and may be older in a greater proportion than those with painful ischemia. Dipyrimadole thallium imaging is useful in the assessment of SMI in the elderly.

Aged↗
PubMed1998

[Assessment of exercise-induced silent myocardial ischemia by dipyridamole thallium imaging. (2). Its significance in Q wave myocardial infarction].

The clinical significance of silent myocardial ischemia (SMI) in the elderly was assessed in 91 patients with Q wave infarction who showed ischemic ST depression during treadmill stress testing, as well as reversible defect (RD) during dipyridamole thallium imaging. They were divided into two groups (47 patients with silent ST depression and 44 patients with painful ST depression) and compared for scintigraphic and coronary arteriographic features, and prognosis. There was no significant difference in age, gender and site of infarction between the two groups. The prevalence of single and double vessel coronary stenosis was higher in patients with SMI (66%) than in those with painful ischemia (p < 0.05). The results of treadmill stress testing showed a longer exercise duration (4.7 +/- 1.7 vs. 4.1 +/- 1.8 min) and higher maximal heart rate (138 +/- 15/vs. 126 +/- 20/min) in patients with SMI than in those with painful ischemia (p < 0.01). Dipyridamole thallium imaging revealed a larger infact (18.8 +/- 9.1 vs. 14.6 +/- 10.2 segments) in patients with SMI than in those with painful ischemia (p < 0.05). The prevalence of RD in the area of infarction was also higher in patients with SMI (74%) than in those with painful ischemia (45%) (p < 0.05). Although a higher proportion of the patients with painful ischemia (42%) underwent CABG or PTCA as their initial therapy, compared with those with SMI (25%) (ns), there was no difference in the cardiac event rate between the two groups who were initially treated medically. Dipyridamole thallium imaging is useful in the assessment of SMI in elderly patients with Q wave myocardial infarction. Those with SMI may have a larger infarct and a higher prevalence of ischemia localized within the infarction than those with painful ischemia.

Aged↗
PubMed1998

[Diagnosis of myocardial ischemia and viability by 31P nuclear magnetic resonance spectroscopy].

To demonstrate the usefulness of in vivo 31P nuclear magnetic resonance spectroscopy (MRS) in the diagnosis of ischemic heart disease, major findings from three clinical cardiac MRS investigations performed at our institute are summarized. The first study investigated whether 31P MRS with handgrip exercise testing could detect myocardial ischemia demonstrated by exercise 201Tl scintigraphy. Contrary to findings in normal subjects or patients with fixed thallium defects, the ratio of phosphocreatine (PCr) to ATP decreased significantly during exercise in patients with reversible thallium defects. In the second study, PCr and ATP content was measured by 31P MRS and compared in human myocardium with reversible ischemia or scar diagnosed by exercise thallium scintigraphy. Although the PCr content decreased in patients with either reversible or fixed thallium defects, the ATP content decreased only in the latter group. In the third study, postischemic myocardium with chronic mechanical dysfunction that exhibits recovery after revascularization in left ventriculography was metabolically characterized using quantitative cardiac 31P MRS. Postischemic myocardium with reversible mechanical dysfunction demonstrated reduced PCr but normal ATP content. These results suggest that 31P MRS is a clinically important method both for the detection of myocardial ischemia and in the evaluation of myocardial viability.

Adult↗
PubMed1997

Osteopontin involvement in integrin-mediated cell signaling and regulation of expression of alkaline phosphatase during early differentiation of UMR cells.

To clarify the function of osteopontin in osteoblast differentiation, we have examined the signal transduction pathway in an osteoblastic cell line (UMR106-6) bound to osteopontin, fibronectin, vitronectin and collagen type I surfaces. This was done by investigating the production and autophosphorylation of focal adhesion kinase (FAK) and the expression of alkaline phosphatase (ALP) at the transcription level. Results suggest that osteopontin was not only responsible for the autophosphorylation of FAK but regulated the expression of ALP, which was strongly correlated with FAK activity. These results suggest that osteopontin might act as a trigger in the early differentiation of osteoblasts.

Alkaline Phosphatase↗
PubMed1997

Japanese population does not manifest significant association between low NK activity and HLA-B(C) locus homozygosity.

It was reported previously that natural killer (NK) activity is controlled by the HLA-B(C) region and that individuals homozygous for HLA-B(C) or homozygous for the NKB complementation groups, which are mapped to the HLA-B(C) region, have fewer circulating NK cells and lower NK activity than do individuals heterozygous for these alleles. Those studies had used subjects in the United States. In the present study, we investigated the NK activity, NK subpopulation, and HLA types of 65 healthy Japanese individuals in Japan, most of whom have a quite different HLA-B(C) type than did subjects in the earlier study. Among 13 individuals having low NK activity, only two were HLA-B(C) homozygous and the rest were heterozygous. No obvious relation between low NK activity and specific HLA-B(C) allele was found. Seven of the nine HLA-B(C) homozygotes had medium or high NK activity. No significant differences were detected in either the NK activity or in the NK subset frequencies (circulating NK cell number) between HLA-B(C) homozygous and heterozygous individuals. These results indicate that HLA-B(C) homozygosity does not always induce low NK activity and that other factors also may influence NK activities.

Adult↗
PubMed1997

Cloning of the Candida albicans homolog of Saccharomyces cerevisiae GSC1/FKS1 and its involvement in beta-1,3-glucan synthesis.

Saccharomyces cerevisiae GSC1 (also called FKS1) and GSC2 (also called FKS2) have been identified as the genes for putative catalytic subunits of beta-1,3-glucan synthase. We have cloned three Candida albicans genes, GSC1, GSL1, and GSL2, that have significant sequence homologies with S. cerevisiae GSC1/FKS1, GSC2/FKS2, and the recently identified FKSA of Aspergillus nidulans at both nucleotide and amino acid levels. Like S. cerevisiae Gsc/Fks proteins, none of the predicted products of C. albicans GSC1, GSL1, or GSL2 displayed obvious signal sequences at their N-terminal ends, but each product possessed 10 to 16 potential transmembrane helices with a relatively long cytoplasmic domain in the middle of the protein. Northern blotting demonstrated that C. albicans GSC1 and GSL1 but not GSL2 mRNAs were expressed in the growing yeast-phase cells. Three copies of GSC1 were found in the diploid genome of C. albicans CAI4. Although we could not establish the null mutation of C. albicans GSC1, disruption of two of the three GSC1 alleles decreased both GSC1 mRNA and cell wall beta-glucan levels by about 50%. The purified C. albicans beta-1,3-glucan synthase was a 210-kDa protein as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and all sequences determined with peptides obtained by lysyl endopeptidase digestion of the 210-kDa protein were found in the deduced amino acid sequence of C. albicans Gsc1p. Furthermore, the monoclonal antibody raised against the purified beta-1,3-glucan synthase specifically reacted with the 210-kDa protein and could immunoprecipitate beta-1,3-glucan synthase activity. These results demonstrate that C. albicans GSC1 is the gene for a subunit of beta-1,3-glucan synthase.

Amino Acid Sequence↗
PubMed1997

Isolation of the Candida albicans homologs of Saccharomyces cerevisiae KRE6 and SKN1: expression and physiological function.

Cell wall beta-glucan in a pathogenic fungus, Candida albicans, is highly branched with beta-1,3 and beta-1,6 linkages. We have isolated the C. albicans cDNAs for KRE6 and SKN1, the genes required for beta-1,6-glucan synthesis in Saccharomyces cerevisiae. The results of Northern blot analysis revealed that C. albicans KRE6 was expressed at a higher level than SKN1 in the yeast phase, while SKN1 expression was strongly induced upon induction of hyphal formation. In addition, the C. albicans KRE6 and SKN1 mRNAs but not the actin mRNA were shortened during the yeast-hypha transition. Unlike S. cerevisiae, more than 50% of cell wall glucan was beta-1,6 linked in C. albicans. Neither beta-1,3-glucan nor beta-1,6-glucan was affected by the homozygous C. albicans skn1 delta null mutation. Although we never succeeded in generating the homozygous C. albicans kre6 delta null mutant, the hemizygous kre6 delta mutation decreased the KRE6 mRNA level by about 60% and also caused a more than 80% reduction of beta-1,6-glucan without affecting beta-1,3-glucan. The physiological function of KRE6 was further examined by studying gene regulation in C. albicans. When KRE6 transcription was suppressed by using the HEX1 promoter, C. albicans cells exhibited the partial defect in cell separation and increased susceptibility to Calcofluor White. These results demonstrate that KRE6 plays important roles in beta-1,6-glucan synthesis and budding in C. albicans.

Amino Acid Sequence↗
PubMed1997

Recognition of osteopontin by rat bone marrow derived osteoblastic primary cells.

To study the role of osteopontin, we did cell adhesion and ALP assays of rat bone marrow osteoblastic cells (RBMO) on collagen Type I and osteopontin surfaces. The RBMO proved to adhere much more strongly to the osteopontin and to have higher ALP activity on the osteopontin, which suggests that pre-osteoblasts differentiate into osteoblasts that form bone by recognizing osteopontins.

Alkaline Phosphatase↗
PubMed1997

Atherosclerotic aortic plaque detected by transesophageal echocardiography: its significance and limitation as a marker for coronary artery disease in the elderly.

OBJECTIVES: To elucidate whether atherosclerotic aortic plaque detected by transesophageal echocardiography can be a clinically useful marker for coronary artery disease in the elderly. BACKGROUND: Atherosclerotic aortic plaque detected by transesophageal echocardiography has been reported to be a marker for coronary artery disease. Its significance may be important particularly in the elderly population, although to our knowledge, there are no data yet available. METHODS: We performed transesophageal echocardiography on 84 patients who had previously undergone coronary arteriography. The criteria used to diagnose atherosclerotic plaque on transesophageal echocardiography were the presence of focally or linearly increased echodensity of the aortic intima with lumen irregularity and thickening or ulceration. RESULTS: Significant coronary artery disease (> or = 50% stenosis) was detected in at least one major coronary artery in 27 of the 84 patients. Aortic plaques were detected by transesophageal echocardiography in 25 of the 27 patients (93%) with coronary artery disease and in 30 of 57 patients (53%) without coronary disease (p<0.001). Among 24 patients 70 years or older, aortic plaques were present in 13 of 14 (93%) patients with coronary artery disease and 9 of 10 patients (90%) without coronary disease. Among 60 patients younger than 70 years, aortic plaques were present in 12 of 13 patients (92%) with coronary artery disease and 21 of 47 patients (45%) without coronary disease (p<0.01). The independent association between coronary artery disease and the presence of aortic plaque, age, gender, and other coronary risk factors was examined by multiple logistic regression analysis. In patients 70 years or older, the presence of aortic plaque failed to be a predictor of significant coronary artery disease, although it was indeed a strong predictor of coronary artery disease in patients younger than 70 years (p<0.05). CONCLUSIONS: In elderly patients, atherosclerotic aortic plaque detected by transesophageal echocardiography is not useful in predicting significant coronary artery disease. It is useful only in a relatively younger population.

Adult↗
PubMed1997

[Mechanism of silent myocardial ischemia in elderly patients with coronary artery disease--assessment by dipyridamole thallium scintigraphy].

To evaluate the clinical significance of silent myocardial ischemia in elderly patients with coronary artery disease, 147 patients (aged 65 years and older) underwent coronary angiography and dipyridamole thallium scintigraphy. Seventy-four patients (44 men, 30 women) who showed reversible defects (RD) and ischemic ST depression during scintigraphy were divided into two groups: 13 with silent RD (18%, 12 men, 1 woman), and 61 with painful RD (82%, 32 men, 29 women). Most patients with silent RD were men. The prevalence of myocardial infarction was similar in patients with silent RD (62%) and in patients with painful RD (49%). The prevalence of multivessel disease was also similar in the two groups: 85% in patients with silent RD and 82% in patients with painful RD. Among 38 patients with infarction, 8 had silent RD and 30 had painful RD. The prevalence of RD in the area of infarction was greater in patients with silent RD (63%) than in patients with painful RD (47%), but the difference was not statistically significant. The prevalence of extensive infarction (fixed defects) was greater in patients with silent RD (75%) than in patients with painful RD (30%, p < 0.05). Among 36 patients without infarction, there was no scintigraphic parameter which showed significant difference. Bypass grafting and angioplasty were initially performed in 23% of the patients with silent RD and in 36% of the patients with painful RD (ns). When the two groups were treated medically during the follow-up period of 29 +/- 22 months, the incidences of cardiac events were similar: 10% in patients with silent RD and 13% in patients with painful RD. The prevalence of silent RD is not high in elderly patients with significant coronary artery disease. Compared with the patients with painful RD, those with silent RD were more likely to have an old and extensive myocardial infarction, and they tended to have RD in the area of the infarct.

Aged↗
PubMed1997

[Prognosis for medically treated elderly patients with coronary artery disease: analysis by the Cox model].

The prognostic importance of age among well-known prognostic factors such as extent of coronary artery lesions, cardiac function, and myocardial ischemia was evaluated in 147 elderly patients with coronary artery disease aged 65 years or older who underwent dipyridamole perfusion scintigraphy and coronary angiography. After excluding 32 patients who initially underwent percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG), 115 patients who were initially treated medically were analysed by the Cox model for cardiac events during a mean follow-up period of 29 +/- 22 months. Among the 114 patients who were available for follow-up, nine patients (7.9%) had cardiac events, including five cardiac deaths and four non-fatal cardiac events (requiring PTCA or CABG). When the 114 patients were divided into three age-groups; 53 patients aged 65-69 years, 42 aged 70-74 years and 19 aged 75 years or older, the incidence of cardiac death was highest in those aged 75 years or older. Univariate analysis showed that age of 70 years or older (hazards ratio 15.15, p = 0.004), scintigraphic diffuse slow washout (hazards ratio 8.77, p = 0.002), and triple-vessel or left main trunk disease (hazards ratio 6.36, p = 0.05) were important prognostic factors. Multivariate analysis showed that scintigraphic diffuse slow washout (hazards ratio 6.33, p = 0.05), and triple-vessel or left main trunk disease (hazards ratio 11.94, p = 0.05) were statistically significant as independent prognostic factors. However, when age of 70 years or older was included in the analysis, it showed higher hazards ratio (21.21, p = 0.03) than that of scintigraphic diffuse slow washout (7.36) or triple-vessel or left main trunk disease (5.30). Age of 70 years or older may be a significant prognostic factor in elderly patients with coronary artery disease which has an equivalent importance to the extent of coronary lesions.

Aged↗
PubMed1997

[Clinical efficacy of three-dimensional chemical shift imaging (3D-CSI)--a study of 3D-CSI in the human heart and its clinical perspectives for the future].

The main purpose of this study was to investigate whether in vivo 31P three-dimensional chemical shift imaging(3D-CSI) of the human heart could serve as a useful tool for evaluating myocardial metabolism. We performed slice-selective 3D-CSI employing nuclear magnetic resonance(NMR) imaging with slice selection in one dimension and phase encoding in two dimensions. 31P NMR images of phosphocreatine (PCr) and ATP were superimposed on a corresponding 1H image of the heart. Our study revealed that while accurate in vivo 31P 3D-CSI measurement of the human heart is difficult to achieve it is not impossible, although various additional techniques for improving signal to noise ratio are indicated.

Adenosine Triphosphate↗