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Biomedical subjects

H Urata

Publications and source records attributed to H Urata.

At least 19 recordsLinked to original sources
PubMed1996

Angiotensin-converting enzyme and heart chymase gene polymorphisms in hypertrophic cardiomyopathy.

We examined the insertion/deletion polymorphism in the angiotensin-converting enzyme gene and identified polymorphisms in the heart chymase gene to test the hypothesis that these angiotensin II-producing enzymes are associated with a monogenic cardiac disease (50 patients and 50 control subjects) as a model of cardiac hypertrophy. We found that the angiotensin-converting enzyme DD genotype was present more often in patients than in control subjects and identified a possible interaction with 1 of the chymase polymorphisms.

Adult↗
PubMed1996

Elimination of fat emulsion particles from plasma during glucose infusion.

To determine the optimal rate of infusion of a fat emulsion (long-chain triglycerides; LCTs) for parenteral nutrition, the rate of elimination of triglycerides from plasma was measured on two occasions in three healthy subjects, once while receiving LCTs alone (study I) and once while receiving a combined infusion of glucose and LCTs (study 2). In study 1 a hypertriglyceridaemic clamp was set up by raising the concentration of triglycerides to 2 mmol l(-1) (60-min priming infusion at 0.2 g LCTs per kg body-weight per h) and maintaining this value for 300 min. In study 2 a constant infusion of glucose at a rate of 0.32 g per kg body-weight per h was given throughout the 420-min test, and the hypertriglyceridaemic clamp was set up after 70 min. The infusion of glucose induced a progressive increase in the mean(s.d.) concentration of insulin from 4.3(0.4) microU ml(-1) to a plateau value of 11.0(0.2) microU ml(-1) which was sustained during the last 310 min of the study. During the steady state of the hypertriglyceridaemic clamp, the concentration of triglycerides (2.16(0.17) versus 2.12(0.20) mmol l(-1), P = 0.26), as well as the mean(s.d.) rates of infusion of LCTs (0.12(0.08) versus 0.12(0.04) per kg body-weight per h, P = 0.38), did not differ between studies 1 and 2. Thus, an infusion of glucose (and the associated physiological increase in the concentration of insulin) at doses commonly used in parenteral nutrition does not influence the rate of elimination of triglycerides from plasma in normal subjects.

Adult↗
PubMed1996

Chymase-dependent angiotensin II forming systems in humans.

Recent studies have provided evidence that human cardiovascular tissues contain components of the renin angiotensin system: angiotensinogen, renin, angiotensin I converting enzyme (ACE), chymase, and angiotensin (Ang) II receptors. It is likely that locally produced Ang II plays an important role in cardiovascular homeostasis in autocrine and paracrine fashions and may also be involved in remodeling of the heart and vasculature in pathological conditions. In addition to ACE, a cardiac Ang II-forming serine proteinase (human heart chymase) has been identified in the left ventricle of the human heart. The different cellular and regional distribution of ACE and heart chymase in the heart as well as in blood vessels implies distinct pathophysiological roles of these two Ang II-forming enzymes. Several reports indicate that both ACE dependent and ACE independent Ang II formation appears to take place in hypoxic or ischemic heart or blood vessel in vivo and seems to be involved in their pathological changes. However, chymase dependent Ang II formation, chymostatin sensitive but aprotinin insensitive, does not explain all of ACE independent Ang II formation. Therefore, it has become quite important to clarify the detailed mechanisms of the tissue Ang II formation in humans and their contribution to the pathophysiological changes in cardiovascular diseases.

Angiotensin II↗
PubMed1996

Elimination rate of fat emulsion particles from plasma in Japanese subjects as determined by a triglyceride clamp technique.

The elimination rate of emulsion triglyceride (TG) from plasma was investigated in Japanese subjects by a plasma TG clamp technique. Two different studies were performed. In Study 1, a lipid emulsion (20% long-chain triglyceride emulsion: LCT) was infused into a healthy research associate to achieve a certain concentration of TG in the plasma. Thereafter, the infusion rate was adjusted to maintain the chosen concentrations of TG in plasma (namely, 4-5 mmol/L, 3-4 mmol/L, and approximately 2 mmol/L) over a period of 160 min by measuring plasma TG concentrations at 10-min intervals. Concentrations of TG in plasma were clamped within 2.13 +/- 0.13 mmol/L by an infusion rate of 0.10 g.kg-1.h-1, within 3.34 +/- 0.20 mmol/L by an infusion rate of 0.14 g.kg-1.h-1, and within 4.46 +/- 0.22 mmol/L by an infusion rate of 0.11 g.kg-1.h-1. The mean rate of infusion of emulsified TG that had maintained the steady concentrations of TG in plasma was limited to the very narrow range of 0.12 +/- 0.02 g of TG.kg-1.h-1 regardless of the chosen concentration of TG in plasma. Concentrations of nonesterified fatty acids (NEFA) also remained at a fixed level of 1.378 +/- 0.103 mEq/L regardless of the chosen concentration of TG in the plasma. Study 2 was undertaken to determine whether plasma TG concentration reached a plateau during a period when emulsion TG was infused into three different subjects at a rate of 0.12 g.kg-1.h-1. The plasma TG concentrations were steady at a level of 2.04 +/- 0.32 mmol/L, and the plasma NEFA concentrations remained at a fixed level of 1.33 +/- 0.13 mEq/L, over a period of 160 min after 50-min priming infusion. These results indicate that the plasma TG elimination rate was limited to the narrow range of 0.12 +/- 0.02 g.kg-1.h-1 when the fat emulsion was infused into Japanese subjects in a steady state. However, the plasma TG elimination rate in Japanese subjects appeared to be lower than that of Europeans. This may be due to a difference in lipoprotein lipase activity caused by different dietary habits, namely, a lower fat intake.

Adult↗
PubMed1996

Angiotensin I converting enzyme and chymase in cardiovascular tissues.

Recent studies have provided evidence that the human cardiovascular tissues contain components of the renin-angiotensin system: angiotensinogen, renin, angiotensin I converting enzyme (ACE), chymase and angiotensin II (Ang II) receptors. In addition to ACE, a cardiac Ang II forming serine proteinase, human heart chymase, has been identified in the human left ventricle. Unlike rat heart, only a minor (approximately 11%) component of Ang II forming activity in the human left ventricle was due to ACE, since the majority (approximately 80%) of activity was due to chymase. Human heart chymase has been purified to homogeneity and characterized. Recently, the cDNA and gene for this enzyme have been cloned. Biochemical characterization revealed that heart chymase is the most efficient and specific Ang II forming enzyme described thus far. The different cellular and regional distribution of ACE and heart chymase in the heart as well as in blood vessels implies distinct pathophysiological roles for these two Ang II forming enzymes. Several reports indicate that ACE-independent Ang II formation appears to take place in hypoxic or ischemic heart or blood vessel in vivo and to be involved in vascular remodeling after balloon injury. Therefore, it is very important to clarify the detailed mechanisms of the tissue Ang II formation in humans and its contribution to the pathophysiological changes in cardiovascular disease. In this review, we review the pathophysiological roles of the two main Ang II forming enzymes, ACE and chymase, in cardiovascular homeostasis.

Animals↗
PubMed1996

Angiotensin-converting enzyme-independent pathways of angiotensin II formation in human tissues and cardiovascular diseases.

The tissue renin-angiotensin system plays an integral role in the homeostasis of blood pressure and in the pathogenesis of cardiovascular remodeling. These effects are primarily mediated through the paracrine and autocrine actions of locally produced angiotensin II (A II). It is generally accepted that the conversion of angiotension I to A II is mainly due to angiotensin-converting enzyme (ACE). However, there are several in vitro and in vivo reports of ACE-independent synthesis of A II in hypoxic and ischemic heart and blood vessels, which may also contribute to cardiovascular pathology. The differential cellular and regional expression of ACE and chymase in the human heart and blood vessels suggests distinct pathophysiologic roles for these two A II-forming enzymes. The study of different pathways involved in tissue A II formation, including that of ACE- and chymase-independent enzymes, will clarify their respective contribution to the pathophysiologic changes in cardiovascular diseases, and help in planning a more comprehensive clinical strategy. This report reviews the properties of human heart chymase, an A II-forming serine proteinase, and compares it with those of ACE.

Angiotensin II↗
PubMed1995

An intestinal fistula in a 3-year-old child caused by the ingestion of magnets: report of a case.

We describe herein the case of a 3-year-old child in whom a jejunoileal fistula was caused by the ingestion of magnets. This case report demonstrates that if more than one magnet is found as a foreign body in the intestine, they should not be left untreated even if there are no sharp edges and, it seems they could be evacuated spontaneously. This recommendation is made because the magnets will attract each other and hold the intestinal walls between them, causing necrosis and resulting in intestinal perforation or a fistula.

Child, Preschool↗
PubMed1995

Mechanisms of angiotensin II formation in humans.

Various organs, including the heart and blood vessels, apparently contain tissue renin-angiotensin systems. Through autocrine and paracrine activity, locally produced angiotensin II (Ang II) may well play an important role in cardiovascular homeostasis; in pathological conditions. Ang II may also contribute to the remodelling of the heart and vasculature. In addition to angiotensin converting enzyme (ACE), a cardiac Ang II forming serine proteinase (human heart chymase) has been identified in the left ventricle of the human heart. The different cellular and regional distributions of ACE and chymase in the heart as well as in the blood vessels suggest distinct pathophysiological roles for these two Ang II forming enzymes. Several reports indicate that both ACE-dependent and ACE-independent Ang II formation appear to occur in hypoxic or ischaemic hearts or blood vessels in vivo and seem to be involved in the pathological changes seen in these organs. However, chymase-dependent Ang II formation--which is chymostatin sensitive but aprotinin insensitive--does not explain all ACE-independent Ang II formation. Therefore, it is important to elucidate the mechanisms of tissue Ang II formation in humans and their contribution to the pathophysiological changes in cardiovascular disease.

Angiotensin II↗
PubMed1995

Activation of renal dopamine system by physical exercise.

Physical exercise is one of the life-style modifications used for lowering blood pressure. Except for diminished norepinephrine spill over, the mechanism by which physical exercise exerts its effects was not known. Based on our preliminary finding that the reduction of blood pressure was inversely correlated to the baseline plasma renin activity, we have consequently revealed that mild exercise reduces plasma volume and hence the cardiac index. In order to elucidate the mechanism, we have investigated all possible parameters relevant to plasma volume regulation. Among them, urinary free dopamine and urinary active kallikrein increased in the early stages (weeks 2-4) while atrio-natriuretic factor (week 4) and endogeneous ouabain-like substance (EOLS) consequently (weeks 7-10) decreased. Serum taurine increased and plasma norepinephrine decreased in the late stages. The conclusion reached is that mild exercise seems to first activate the renal dopamine and kallikrein systems and second trigger other mechanism, such as an increase in taurine and decreases in EOLS and norepinephrine.

Adult↗
PubMed1995

[Body density assessment utilizing skinfold thickness and age in Japanese women].

A study was conducted to investigate the validity of skinfold-based prediction equations for body density (g/ml) by Nagamine and Suzuki (1964), and to formulate more convenient and more useful equations for predicting body density from skinfold and age in women. Subjects of the study were 512 healthy women aged 18-66 years in or near Nagasaki City. The dependent variable in the multiple regression equation, body density, was determined by hydrostatic weighing. Independent variables included eight skinfolds, the sum of two skinfolds (triceps, subscapular), the sum of three skinfolds (triceps, subscapular, and abdominal), age, and body surface area. Skinfolds were measured with an Eiken-model skinfold caliper. Age (mean 30.1, range 18-66 yrs.), weight (mean 52.6, range 38.0-83.3 kg), height (mean 157.0, range 142.0-172.0 cm), and body density, (mean 1.04125, range 0.98806-1.08650 g/ml) were also recorded. Percent body fat was calculated using the formula by Brozek et al. and ranged from 6.4% to 48.3%. Multiple correlation coefficients (MR) and standard error (SE) of 10 regression equations (A-J) for predicting body density in women were compared. The best-fitting and the most convenient prediction equation for body density was equation-E. The regression equation developed for predicting body density was: body density = 1.07931-0.00059 x sum of three skinfolds(mm)-0.00015 x age (MR = 0.77 and SE = 0.0089). The equation was cross-validated on a different sample of 46 women. The correlation coefficient between predicted and hydrostatically determined body density was 0.813 (p < 0.001). Equation-E (Tahara's equation) appears to be useful in body density analysis particularly when the subjects are Japanese women, aged 18-50 yrs, with percent body fat 17 to 34%.

Adolescent↗
PubMed1995

[Body density assessment utilizing skinfold thickness and age in Japanese men].

A study was conducted to investigate the validity of skinfold-based prediction equations for body density (g/ml) by Nagamine and Suzuki (1964), and to formulate more convenient and more useful equations for predicting body density from skinfold and age in men. Subjects of the study were 257 healthy men aged 19-60 years in or near Nagasaki City. The regression equation for the dependent variable, body density, was determined by hydrostatic weighing. Independent variables included eight skinfolds, the sum of two skinfolds (triceps, subscapular), the sum of three skinfolds (triceps, subscapular, and abdominal), age, and body surface area. Skinfolds were measured with an Eiken-model skinfold caliper. Age (mean 33.1, range 19-60 yrs.), weight (mean 65.3, range 46.6-107.7 kg), height (mean 168.8, range 152.3-185.4 cm), and body density (mean 1.05874, range 1.00860-1.09020 g/ml) were also recorded. Percent body fat was calculated using the formula by Brozek et al. and ranged from 6.1% to 38.9%. Multiple correlation coefficients (MR) and standard error (SE) of 10 regression equations (A-J) for predicting body density in men were obtained. The best-fitting and the most convenient prediction equation for body density was equation-E.: body density = 1.09556-0.00062 x sum of three skinfolds (mm)-0.00028 x age (MR = 0.815 and SE = 0.0087 g/ml). The equation was cross-validated on a different sample of 45 men. The correlation coefficient between predicted and hydrostatically determined body density was 0.781 (p < 0.001). Equation-E (Tahara's equation) appears to be useful in body density analysis particularly when the subjects are Japanese men, aged 18-50 yrs, with percent body fat 10 to 30%.

Adult↗
PubMed1995

[Hydrostatic weighing, skinfold thickness, body mass index relationships in high school girls].

A study was conducted to evaluate body composition by hydrostatic weighing, skinfold thickness, and body mass index (BMI) in 102 senior high school girls, aged 15 to 18 in Nagasaki City. Body density measured by the underwater weighing method, was used to determine the fat weight (Fat) and lean body mass (LBM. or fat free weight: FFW) utilizing the formulas by Brozek et al. The results were as follows; 1. Mean values of body density were 1.04428 in the first grade girls, 1.04182 in the second grade, and 1.04185 in the third grade. 2. Mean values of percentage body fat (%Fat) were 23.5% in the first grade, 24.5% in the second and 24.5% in the third. 3. Percentage body fat (%Fat), lean body mass (LBM) and LBM/Height were not significantly with different advance of grade from the first to the third. 4. The correlation coefficients between percent body fat and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.78, 0.79, and 0.80 respectively and were all statistically significant (p < 0.001). 5. The correlation coefficients between BMI and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.74, 0.74, and 0.74 respectively and were all statistically significant (p < 0.001). 6. Mean values of BMI, Rohrer index and waist-hip ratio (WHR) in all subjects (n = 102) were 20.3, 128.2 and 0.72 respectively.

Adolescent↗
PubMed1994

Tissue angiotensin II system in the human heart.

Several intervention studies with angiotensin I converting enzyme (ACE) inhibitors have demonstrated a remarkable improvement in the treatment of patients with primary hypertension and congestive heart failure. Since ACE inhibitor therapy in patients with congestive heart failure not only improves systemic haemodynamics but also provides a better prognosis, the cardiac renin-angiotensin system is apparently one of the major targets of ACE inhibitor therapy. Recent studies provided evidence that the human heart contains high affinity Ang II (Ang II) receptors with both subtype population and ACE. In addition to ACE, a novel cardiac Ang II forming enzyme (human chymase) has been identified in human hearts. Unlike in the rat heart, the minor (10%) component of Ang II-forming activity in the left ventricle is due to ACE, whereas the major (80%) component is due to human chymase. This novel cardiac serine proteinase has been purified from the human left ventricle and characterized, and recently, the cDNA and the gene for this enzyme have been cloned. Biochemical characterization revealed that human chymase is the most efficient and specific Ang II-forming enzyme described thus far, but the cellular and regional distribution of the two Ang II-forming enzymes seems to be different. ACE is mainly localized in endothelial cells and fibroblasts and the expression level is higher in atria than ventricles, whereas chymase is synthesized and stored in secretory granules of mast cells, endothelial cells, and mesenchymal cells, and after its secretion localized in the interstitial region of the myocardium and its expression is higher in ventricles than atria. These results imply distinct roles of these two Ang II-forming enzymes in cardiac Ang II formation and in the physiological function of the human heart. Since localization of cardiac renin and angiotensinogen were also identified in human heart, it is important to understand the detailed mechanisms of the tissue Ang II formation and its contribution to the pathophysiological changes in cardiovascular diseases.

Angiotensin II↗
PubMed1994

Conserved and novel structural characteristics of enantiomorphic Leu-enkephalin. X-ray crystal analysis of Leu-enkephalin enantiomer, L-Tyr-Gly-Gly-L-Phe-L-Leu and D-Tyr-Gly-Gly-D-Phe-D-Leu.

The crystal of the Leu-enkephalin racemate (L-Tyr-Gly-Gly-L-Phe-L-Leu and D-Tyr-Gly-Gly-D-Phe-D-Leu) was obtained as a centrosymmetric space group. Crystal data: C28H37N5O7 x 1.5H2O, Mw = 582.6, triclinic, space group P1, a = 11.176(3), b = 16.115(3), c = 10.204(4) A, alpha = 92.41(3), beta = 104.86(2), gamma = 85.35(2)degrees, V = 1770(1)A3, Z = 2; F(000) = 640, mu(CuK alpha) = 6.50 cm-1, D chi = 1.081 g cm-3. The structure was determined by X-ray diffraction. The conformation of the Leu-enkephalin racemate was classified into the extended form which has been often observed in natural enkephalin. The symmetry-related molecules were connected by hydrogen bonds and arranged in an antiparallel fashion. The molecular packing showed a sheet structure similar to that of natural enkephalin.

Amino Acid Sequence↗
PubMed1994

[Sex differences in interrelationships between percent body fat (%fat) and waist-to-hip ratio (WHR) in healthy male and female adults].

The purpose of the present study was to investigate sexual differences in relationships among percent body fat (%Fat), waist-to-hip ratio (WHR), waist-to-stature ratio (WSR), abdominal circumference to stature ratio (ASR), body mass index (BMI) and skinfold thicknesses in healthy male and female adults. Subjects were 64 males and 65 females, aged 22-60. Body density was measured by under water weighing and by skinfold anthropometry. Mean %Fat was 15.6% in males and 23.9% in females. Mean WHR was 0.83 in males and 0.72 in females. The correlation between %Fat and WHR was not significant in females (r = -0.104) but was significant in males (r = 0.631, p < 0.001). Highly significant correlations were obtained among %Fat, WSR, ASR, BMI, and sum of eight skinfolds in both sexes.

Adipose Tissue↗
PubMed1994

Widespread tissue distribution of human chymase.

OBJECTIVE: Human chymase is a potent and specific angiotensin (Ang) II-forming serine proteinase. Although the histological localization of heart chymase indicated that this enzyme contributes to extracellular Ang II formation, the systemic distribution and the level of expression of chymase in various human tissues have not been clarified. This information is needed to elucidate the human tissue Ang II system. METHODS: Levels of immunoreactivity and enzymatic activity in various human tissues were evaluated respectively by Western blot analysis and by an enzymatic assay for Ang II-forming activity from Ang I. RESULTS: High levels of chymase-like immunoreactivity were found in alimentary tract tissue, uterus and tonsil; moderate levels were found in both cardiac ventricles, lung, adenoid and liver; low levels were found in the cardiac atria, coronary artery, aorta and skin; and almost undetectable levels were found in the spleen and kidney. High levels of chymase-like enzymatic activity were detected in skin, oesophagus, stomach and uterus; moderate levels were found in both cardiac ventricles, lung, colon, tonsil, adenoid and renal cortex; and low levels were found in the cardiac atria, coronary artery, aorta, spleen, renal medulla and liver. CONCLUSIONS: Our studies have revealed heterogeneous and widespread tissue distribution of human chymase throughout the human body and indicate that chymase probably has a significant influence not only in the heart but also in other tissues.

Angiotensin I↗
PubMed1993

Dipeptide processing activates recombinant human prochymase.

Human chymase (h-chymase) is a serine protease that efficiently converts angiotensin I to II. Its structure and homology to other serine proteases suggest that it is synthesized as a zymogen, and is processed to the active form by cleavage of a 19-residue signal peptide and of a dipeptide pro-segment. To evaluate maturational processing of this enzyme, the proteins encoded by three h-chymase cDNA constructs (wild-type, lacking the pro- or lacking the prepro-segment) were characterized after expression in COS-1 cells. These recombinant proteins were not catalytically active. Purification and NH2-terminal sequence analysis of the protein expressed from the wild-type construct revealed processing to the proenzyme. Prochymase activation was achieved by incubation with a B-cell lymphoma homogenate, which apparently contains a heterologous processing enzyme sensitive to thiol protease inhibitors. NH2-terminal sequence analysis of the activated h-chymase revealed cleavage of the pro-segment, and its biochemical characteristics were identical to those of native h-chymase purified from the myocardium. These findings indicate that processing of the dipeptide pro-segment is necessary and sufficient for activation of human chymase. Such processing is probably also required for the activation of related serine proteases, e.g., cathepsin G, which have homologous dipeptide pro-segments.

Amino Acid Sequence↗