PubMed Health⌕ Search

Biomedical subjects

H Kitaoka

Publications and source records attributed to H Kitaoka.

At least 19 recordsLinked to original sources
PubMed2001

Endothelin-1 gene variant associates with blood pressure in obese Japanese subjects: the Ohasama Study.

A recent report based on the results of 2 epidemiological studies, the Etude Cas-Temoin de l'Infarctus Myocarde (ECTIM) and the Glasgow Heart Scan Study, revealed that a G/T polymorphism with an amino acid substitution (Lys-->Asn) at codon 198 in exon 5 of the endothelin-1 gene (ET-1) is associated with blood pressure in overweight people. They suggested that G/T polymorphism of ET-1 strongly interacted with body mass index (BMI) in the determination of BP levels. To examine interaction among G/T polymorphism of ET-1, BMI, and BP, we performed an association study in a general Japanese population. Subjects (n=1250) were recruited from Ohasama, a cohort in a rural community of northern Japan. DNA was extracted from buffy coat of participants, and G/T polymorphism of ET-1 was determined by the TaqMan probe polymerase chain reaction method, a powerful tool for semiautomatic genotype determination of a large number of samples. Frequency of T (Asn 198) allele in Japanese (27%) was slightly but significantly higher than in whites (24%). Baseline characteristics (age, BMI, systolic and diastolic BP, and antihypertensive treatment) of all subjects were not significantly different according to the genotype of G/T polymorphism. However, in obese subjects (> or =25 kg/m(2)) diastolic BPs were significantly associated with G/T polymorphism of ET-1. After adjustment for confounding factors, significant association remained; for overweight subjects, diastolic BP level in those with T allele (GT + TT) was 1.8 mm Hg (P=0.04) higher than in those with GG genotype. That similar results were obtained from subjects of different races suggests that the Lys198Asn polymorphism of ET-1 is involved in determination of BP levels in obese subjects.

Asian People↗
PubMed2001

Aldosterone synthase gene (CYP11B2) C-334T polymorphism, ambulatory blood pressure and nocturnal decline in blood pressure in the general Japanese population: the Ohasama Study.

OBJECTIVE: The C-344T polymorphism in the 5'-flanking region of the aldosterone synthase (CYP11B2) gene has been suggested to be associated with hypertension and disturbed circadian blood pressure (BP) rhythm through its effect on aldosterone synthesis. However, previous findings on this topic have been inconsistent. DESIGN: A cross-sectional study. SUBJECTS AND METHODS: We investigated the CYP11B2 C-344T genotype in 802 subjects, aged 40 and over, in a Japanese community, who gave written informed consent and were monitored for 24 h ambulatory BP. RESULTS: The frequencies of the CC, CT, and TT genotypes in these Japanese subjects were 0.14, 0.44, and 0.42, showing a higher frequency of the T allele (0.64) than in Caucasians. Although there was no significant difference in 24 h ambulatory BP levels among the genotypes, the nocturnal decline in BP was significantly greater in the CC homozygous subjects than in other subjects (P = 0.0065 for systolic and P = 0.031 for diastolic decline in nocturnal BP). Detailed analyses demonstrated that this association was significant only in aged (60 years and over) or male subjects. The prevalence of previous cardiovascular disease was significantly less in these subjects with the CC genotype than in those with the TC and TT genotypes, although age, body mass index, male gender, smoking, use of alcohol and antihypertensive medication did not differ among the three genotypes. There was no significant difference among the three genotypes in biochemical and hormonal parameters. CONCLUSION: Although the C-344 T polymorphism of CYP11B2 did not directly influence the level of 24 h BP, the CC genotype was associated with decreased nocturnal BP in elderly or male Japanese. Since prevalence of previous cardiovascular disease was significantly less in homozygous CC subjects, greater nocturnal BP decline in this genotype appears to be beneficial in the circadian BP rhythm.

Aged↗
PubMed2001

Predictive values of automated blood pressure measurement: what can we learn from the Japanese population - the Ohasama study.

BACKGROUND: Measurements of ambulatory blood pressure (ABP) and of home blood pressure (HBP) as an adjunct to casual/clinic blood pressure (CBP) measurements are currently widely used for the diagnosis and treatment of hypertension. We have monitored a rural cohort of people from the population of Ohasama, Japan, with respect to their prognosis and have previously reported that ABP and HBP are superior to CBP for the prediction of cardiovascular mortality. One reason that CBP is a poor predictor of prognosis is that it incorporates several biases, including the white-coat effect. METHODS AND RESULTS: We examined the prognostic significance of white-coat hypertension for mortality and found that the relative hazard for the overall mortality of patients with white-coat hypertension was significantly lower than that for true hypertension. Short-term blood pressure variability has recently attracted attention as a cause of target-organ damage and cardiovascular complications. Our results confirmed that short-term blood pressure variability (as measured every 30 min) was independently associated with cardiovascular mortality. In addition, research has recently focused on isolated systolic hypertension and pulse pressure as independent risk factors for poor cardiovascular prognosis. The Ohasama study also clearly demonstrated that isolated systolic hypertension and increased pulse pressure, as assessed by HBP, were associated with an increase in the risk of cardiovascular mortality. Circadian blood pressure variation is characterized by a diurnal elevation and a nocturnal decline in blood pressure. We therefore compared morbidity from stroke between dippers (subjects who show an ordinal nocturnal dipping of blood pressure) and non-dippers (those with a diminished nocturnal dipping or nocturnal elevation of blood pressure [inverted dippers]) in the Ohasama study. The incidence of stroke increased with an increased length of observation in dippers using antihypertensive medication but not in non-dippers using antihypertensive medication. In contrast, the relative hazard for mortality increased in non-dippers and inverted dippers. These results suggest a cause-and-effect relationship for both dippers and non-dippers. CONCLUSION: The Ohasama study showed that the level and variability of hypertension as assessed by ABP and HBP are independent predictors of cardiovascular mortality. It also demonstrated an independent association between the prognosis of hypertension and each component of ABP and HBP, indicating the prognostic significance of these blood pressure measurements.

Bias↗
PubMed2001

The mechanism of reaction of ebselen with superoxide in aprotic solvents as examined by cyclic voltammetry and ESR.

The mechanism of the redox reaction of ebselen with superoxide was investigated using both ESR and electrochemical techniques. The reaction with superoxide in aprotic solvents was followed by means of cyclic voltammetry and ESR spin-trapping. A decrease in the oxidation current due to superoxide as a result of the addition of ebselen was clearly observed in the cyclic voltammograms. Ebselen reduced the ESR signal intensity of 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-superoxide in a dose-dependent manner. The formation of an amidyl radical in this redox reaction was confirmed by rapid mixing continuous-flow ESR. The selenonate form and the seleninate form of ebselen were identified as the final products of the reaction of ebselen with superoxide. The following mechanism for this redox reaction can be proposed: First, ebselen reacts with superoxide and is converted to an ebselen anion radical; second, the ebselen anion radical reacts with superoxide and is converted to the amidyl radical. Hydrogen abstraction by the amidyl radical occurs and gives both a seleninate form and a selenonate form.

Antioxidants↗
PubMed2001

Antioxidative properties of probucol estimated by the reactivity with superoxide and by electrochemical oxidation.

The reaction of probucol with superoxide (O2(*-)) was investigated in acetonitrile using both electron spin resonance (ESR) and electrochemical techniques. The formation of phenoxyl radical was observed during the reaction of probucol with O2(*-) by ESR spectroscopy. The reaction of probucol with O2(*-) in acetonitrile was followed by cyclic voltammetry. With the addition of probucol, the oxidation peak current of O2(*-) decreased concentration dependently. This suggests that probucol reacts with O2(*-), that is, probucol scavenges O2(*-) in acetonitrile. 2,6-Di-tert-butyl-p-benzoquinone was identified as the major product of the reaction of probucol with O2(*-) in acetonitrile. Electrochemical oxidation of probucol was also performed. Probucol gives an irreversible oxidation peak at ca. +1.4 V vs. the saturated calomel electrode in the cyclic voltammogram. Controlled-potential electrolysis was carried out at +1.2 V in a divided cell. 2,6-Di-tert-butyl-p-benzoquinone, 4,4'-dithiobis(2,6-di-tert-butylphenol), and 4,4'-trithiobis(2,6-di-tert-butylphenol) were identified as the products of anodic oxidation. These redox properties of probucol may correlate with the physiological activities.

Antioxidants↗
PubMed2001

Hypertrophic cardiomyopathy in the elderly: significance of atrial fibrillation.

BACKGROUND AND OBJECTIVES: Atrial fibrillation (Af) is an important prognostic indicator for clinical deterioration in patients with hypertrophic cardiomyopathy (HCM), particularly in elderly patients, but its significance may vary from unselected to selected populations. This study investigated the risk of Af as a prognostic factor in long-term mortality and morbidity in Japanese patients with HCM at our institution. METHODS: All fatal and non-fatal cardiovascular events were estimated in 91 patients with HCM (mean age 51 +/- 14 years, 62 men) and follow up continued for 6.7 +/- 4.8 years. RESULTS: Either chronic or paroxysmal Af documented by standard electrocardiography (ECG) or ambulatory ECG monitoring at diagnosis and during follow-up were included with other clinical features in the survival analysis. Af was documented in 22 patients (24%). They were older than those without Af (57 +/- 10 vs 48 +/- 14 years, p < 0.005) and had larger left atrial dimensions (43 +/- 6 vs 36 +/- 5 mm, p < 0.01). Cardiovascular events occurred in 12 patients with Af (embolic events in five, heart failure in four, and sudden death in three), and in four patients without Af (embolic event in one, and sudden death in three). Death occurred in 10 patients (seven with Af and three without Af); sudden death in six patients (three with Af and three without Af) and four patients died of cerebrovascular embolism (four with Af and none without Af). Cox's regression analysis showed the occurrence of Af was the most useful predictor of cardiovascular death in patients with HCM. The event-free rate was significantly worse in patients with Af than in those without Af (p < 0.0001). CONCLUSIONS: Af is an important prognostic feature in patients with HCM, which occurs in older patients and in those with left atrial dilation.

Aged↗
PubMed2000

Effect of angiotensin-converting enzyme inhibitor (enalapril or imidapril) on ventilation during exercise in patients with chronic heart failure secondary to idiopathic dilated cardiomyopathy.

Eighteen patients with heart failure were studied to clarify whether angiotensin-converting enzyme inhibitor treatment improves excess ventilation during exercise. Treatment with angiotensin-converting enzyme inhibitors had a beneficial effect on excess ventilation during exercise, without significant improvement in exercise capacity in patients with moderate congestive heart failure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

A three-dimensional model of the human pulmonary acinus.

A three-dimensional (3-D) model of the human pulmonary acinus, a gas exchange unit, is constructed with a labyrinthine algorithm generating branching ducts that fill a given space completely. Branching down to the third respiratory bronchioles is generated with the proposed algorithm. A subacinus, a region supplied by the last respiratory bronchiole, is approximated to be a set of cubic cells with a side dimension of 0.5 mm. The labyrinthine algorithm is used to determine a pathway through all cells only once, except at branching points with the smallest path lengths. In choosing each step of a pathway, random variables are used. Resulting labyrinths have equal mean path lengths and equal surface areas of inner walls. An alveolus can be generated by attaching alveolar septa, 0.25 mm long and 0.1 mm wide, to the inner walls. Total alveolar surface area and numbers of alveolar ducts, alveolar sacs, and alveoli in our 3-D acinar model are in good accordance with those reported in the literature.

Algorithms↗
PubMed2000

Efficacy of cholesterol-lowering treatment in Japanese elderly patients with coronary artery disease and normal cholesterol level using 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor.

The clinical benefit of cholesterol-lowering treatment is unknown in the Japanese elderly in whom the prevalence of morbidity and mortality related to coronary artery disease are known to be low. To evaluate the efficacy of cholesterol-lowering treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor in Japanese elderly patients with documented coronary artery disease, 121 patients with serum cholesterol > or = 150 mg/dl prospectively received HMG-CoA reductase inhibitor, and 271 patients undergoing cholesterol-lowering treatment based on dietary therapy alone served as historical controls. The 143 elderly patients age > or = 65 years in the 2 groups had similar baseline serum total cholesterol level (201 +/- 30 vs 202 +/- 31 mg/dl), age (71 +/- 4 vs 70 +/- 4 years), proportion of men (37/53 vs 64/90), number of diseased vessels (1.7 +/- 0.9 vs 1.5 +/- 1.0), and incidences of other classical coronary risk factors, including hypertension, diabetes mellitus, smoking, obesity and family history of coronary artery disease. In all 392 patients, similar trends were observed, including serum total cholesterol level (208 +/- 33 vs 201 +/- 34 mg/dl). With HMG-CoA reductase inhibitors, serum total cholesterol level was reduced by 14% in the elderly subjects and by 13% in all patients. During the follow-up of approximately 3 years, cardiac events occurred in 5 patients (one elderly) in the treatment group and 38 patients (12 elderly) in the control group. Kaplan-Meier survival estimates revealed a higher event-free survival rate with HMG-CoA reductase inhibitors in the elderly subjects (98% vs 85%, p < 0.05) and in all patients (94% vs 86%, p < 0.05). Cox proportional hazard modeling also demonstrated a significant reduction in risk for cardiac events with drug therapy (relative risk 0.32, p < 0.05), in addition to the number of diseased vessels (relative risk 1.8, p < 0.01). In contrast, no additional risk was observed with advancing age. Cholesterol-lowering treatment with HMG-CoA reductase inhibitors is effective to improve the prognosis of Japanese elderly patients, including those with normal serum cholesterol level.

Anticholesteremic Agents↗
PubMed1999

Pulmonary diffusing capacity, serum angiotensin-converting enzyme activity and the angiotensin-converting enzyme gene in Japanese non-insulin-dependent diabetes mellitus patients.

We investigated the independent change in pulmonary diffusing capacity (DLCO) as one manifestation of pulmonary microangiopathy and to analyze the correlation between DLCO and serum ACE. We also examined the association between DLCO and the ACE genes. We examined pulmonary functions, especially %DLCO/VA (DLCO corrected by alveolar volume, percent predicted) in 54 NIDDM patients and 34 age-matched normal control subjects. Subjects were subdivided according to the degree of retinopathy. Serum ACE level was assayed by a colorimetric method in 54 patients and an insertion/deletion polymorphism in the ACE gene was amplified using the polymerase chain reaction in 52 of the 54 patients. There was a significant reduction of %DLCO/VA (percent predicted P < 0.05) in diabetic patients. In the proliferative retinopathy (PDR) group. %DLCO/VA was significantly (P < 0.05) lower than in the no diabetic retinopathy (NDR) and simple diabetic retinopathy (SDR) groups. Although the levels of serum ACE were within normal ranges in all diabetic groups, %DLCO/VA was negatively correlated with serum ACE values (r = 0.49, P < 0.0002, y = -1.4x + 109.3). Differences among DD, ID and II type of the ACE gene, with respect to the incidence of abnormal values of each clinical parameter, were not significant. DLCO was significantly reduced in patients with PDR and the serum ACE was significantly related to impaired DLCO. Our study suggests the existence of microangiopathic involvement of pulmonary vessels in NIDDM patients.

Colorimetry↗
PubMed1999

Scores of coronary calcification determined by electron beam computed tomography are closely related to the extent of diabetes-specific complications.

This study was aimed at investigating the degree of calcification of coronary arteries in type II diabetes mellitus for the purpose of examining as risk factors for coronary disease as well as parameters of diabetic complications. One hundred and three patients with type II diabetes were studied by the newly developed noninvasive technology of electron beam computed tomography, in which the degree of calcification was expressed as coronary calcification scores. The mean +/- SE value of coronary calcification scores were 247.5 +/- 48.1, which were significantly greater than the control patients without diabetes (148.9 +/- 48.3, p<0.05). In the diabetics, the coronary calcification scores had a significant (p < 0.01) correlation with patient age and duration of diabetes. The scores also had a significant (p<0.05) difference between patients who did and did not smoke cigarettes, and between patients with and without hypertension. The scores were significantly (p < 0.01) different between patients with and without hypertension. The scores were significantly (p < 0.01) different between presence and absence of diabetes-specific complications including retinopathy, neuropathy, and nephropathy. In a subgroup of patients without any signs of coronary disease, the scores showed a significant (p<0.01) difference between presence and absence of diabetes-specific complications, but no significant difference with smoking or hypertension. These data suggest that the extent of coronary calcifications and the development of ischemic heart disease seem to be closely related to the association of diabetic complications. Use of electron beam computed tomography seems to be useful in obtaining the information to predict future development of diabetic-specific complications.

Age Factors↗
PubMed1999

Low dose dobutamine stress echocardiography predicts the improvement of left ventricular systolic function in dilated cardiomyopathy.

OBJECTIVE: To determine whether dobutamine stress echocardiography can predict the improvement of left ventricular systolic function in patients with dilated cardiomyopathy (DCM). METHODS: Myocardial contractile reserve, as assessed by dobutamine stress echocardiography, was determined in 18 patients with DCM (mean (SD) age 53 (13) years, left ventricular ejection fraction (LVEF) 28 (10)%) and compared with changes in LVEF during a follow up period of 15 (8) months. The LVEF and regional left ventricular wall motion score (0, normal to 4, dyskinesis) of 12 segments in short axis and four chamber views were analysed before and after dobutamine infusion (5-20 microg/kg/min). RESULTS: During a follow up period of 15 (8) months, a significant improvement in LVEF (> 20%) was found in seven patients but not in the remaining 11. Baseline haemodynamic findings were similar in both groups. Patients with an improvement in follow up LVEF showed a greater change in wall motion score from baseline during dobutamine infusion than patients with no improvement (at rest, 1.7 (0.4) v 1.9 (0.2), NS; dobutamine 10 microg/kg/min, 0.6 (0.4) v 1.2 (0.4), p < 0.05). The percentage change in LVEF during dobutamine infusion was also significantly greater in patients who showed improvement than in those who did not. The change in LVEF during the follow up period (follow up LVEF/baseline LVEF) correlated well with the change in LVEF during dobutamine stress (LVEF at rest/LVEF at dobutamine 10 microg/kg/min; r = 0.74, p < 0.001). CONCLUSIONS: Changes in left ventricular systolic performance during low dose dobutamine stress echocardiography are a useful marker to predict the outcome of left ventricular systolic function in patients with DCM.

Adult↗
PubMed1999

A three-dimensional model of the human airway tree.

A three-dimensional (3D) model of the human airway tree is proposed using a deterministic algorithm that can generate a branching duct system in an organ. The algorithm is based on two principles: 1) the amount of fluid delivery through a branch is proportional to the volume of the region it supplies; and 2) the terminal branches are arranged homogeneously within the organ. These principles define the basic process of branching: generation of the dimensions and directionality of two daughter branches is governed by the properties of the parent branch and the region the parent supplies. The algorithm is composed of nine basic rules and four complementary rules. When the contour of an organ and the position of the trunk are specified, branches are successively generated by the algorithm. Applied to the human lung, the algorithm generates an airway tree that consists of approximately 54,000 branches. Its morphometric characteristics are in good agreement with those reported in the literature. The algorithm and the 3D airway model are useful for studying the structure-function relationship in the lung.

Algorithms↗