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Biomedical subjects

H Ebata

Publications and source records attributed to H Ebata.

At least 19 recordsLinked to original sources
PubMed2003

A new method of superficial peroneal nerve conduction studies.

Herein, we report a new method for obtaining sensory nerve conduction velocities (SCVs) in the distal segment of the superficial peroneal nerve (SPN). Twenty lower extremities from 10 normal subjects (mean age: 33.4 years) were evaluated. The recording electrodes were placed on the dorsal surfaces of the ankle and foot. We stimulated the SPNs on the anterior edge of subjects' fibulas, and evoked sensory nerve action potentials (SNAPs) antidromically. SCVs were calculated based upon the distances and the latencies. The mean SCV was 41.3 +/- 4.3 m/s in the distal segment, which was slower than in the proximal segment (51.7 +/- 3.9 m/s). We were able to stimulate only the SPN with certainty. In conclusion, the described technique should be of clinical value in diagnosing peripheral neuropathy.

Action Potentials↗
PubMed2000

Lipase-catalyzed transformation of poly(epsilon-caprolactone) into cyclic dicaprolactone.

The enzymatic degradation and polymerization using an enzyme were carried out with respect to the establishment of a sustainable chemical recycling system for poly(epsilon-caprolactone) (PCL) which is a typical biodegradable synthetic plastic. The enzymatic transformation of PCL having an Mn of 110,000 using Candida antarctica lipase (lipase CA) in water-containing toluene at 40 degrees C afforded the corresponding cyclic dicaprolactone (DCL, 1,8-dioxacyclotetradecane-2,9-dione) in a yield of up to 97%. Thus the obtained DCL readily polymerized again using both the fresh and recovered lipase CAs.

Candida↗
PubMed1997

Diurnal blood pressure rhythm in hypertensives with parental history of stroke.

To investigate whether the lack of nocturnal decline of blood pressure (nondipper) is a primary cause of stroke or a secondary abnormality due to stoke, we examined the relation between the blood pressure variation and parental history of stroke in 110 hypertensive patients. In nondippers (n = 54), the frequency of positive parental history of stroke was significantly higher than in dippers (n = 56) (53.7% v 33.9%, chi2 = 4.37, P = .0366). We observed a significant increase in the incidence of positive parental history of stroke in nondippers, suggesting that some genetic factors may regulate blood pressure profiles before stroke develops.

Aged↗
PubMed1997

Angiotensin converting enzyme gene polymorphism in essential hypertension based on ambulatory blood pressure monitoring.

The association of the angiotensin converting enzyme (ACE) gene polymorphism with essential hypertension is still controversial. We studied its polymorphism in 41 patients with hypertension based on ambulatory blood pressure (ABP) and 34 subjects with normal blood pressure. The ACE genotype was not significantly different between hypertensive and normotensive subjects. Casual blood pressure levels, 24 h, and daytime and nighttime ABP levels did not differ among the ACE genotype in patients with hypertension. In conclusion, the ACE genotype is not associated with essential hypertension based on ABP monitoring.

Alleles↗
PubMed1997

Thyroid hormone stimulates Na(+)-Ca2+ exchanger expression in rat cardiac myocytes.

We investigated whether thyroid hormone directly affects Na(+)-Ca2+ exchanger expression in cardiac myocytes. Cultured neonatal rat cardiocytes were prepared from 1-day-old Sprague-Dawley rats. Intracellular Na+ concentration ([Na+]i) in cardiocytes was measured by using the Na(+)-sensitive dye sodium-binding benzofran isophthalate (SBFI). Na(+)-Ca2+ exchanger messenger RNA (mRNA) and protein expression were assayed by Northern and Western blotting, respectively. Triiodothyronine (T3; 10(-8) M) showed no effect on [Na+]i in cardiocytes, whereas ouabain (100 microM) caused a significant increase in [Na+]i from 11.3 +/- 5.0 to 21.8 +/- 5.0 mM. Exposure of cardiocytes to ouabain caused a rapid increase in Na(+)-Ca2+ exchanger mRNA accumulation, with a maximal twofold elevation at 12 h. The ouabain-induced Na(+)-Ca2+ exchanger mRNA accumulation was still observed in the Ca(2+)-free culture medium. On the other hand, exposure of cardiocytes to T3 induced a gradual increase in Na+ exchanger mRNA accumulation, with a maximal threefold increase at 24 h. Even in Na(+)-free medium, T3 still induced a twofold increase in Na(+)-Ca2+ exchanger mRNA accumulation in cardiocytes. Exposure of cardiocytes to T3 for 24-48 h also caused a marked increase in Na(+)-Ca2+ exchanger protein accumulation. In conclusion, thyroid hormone directly increases cardiac Na(+)-Ca2+ exchanger expression, independent of alterations in Na+ mobilization. These findings suggest also that thyroid hormone and Na+ regulate Na(+)-Ca2+ exchanger gene expression through distinct molecular regulatory pathways.

Animals↗
PubMed1996

A case of renovascular hypertension associated with neurofibromatosis.

We report a case of renovascular hypertension associated with neurofibromatosis complicated by moderate proteinuria. A 16-year-old female was admitted to Kensei General Hospital with a complaint of headache and a blood pressure of 230/120 mm Hg. She was referred to us for further evaluation of the hypertension. On examination, cafe-au-lait spots were seen over her extremities and flank, and a bruit was heard in the right upper abdomen. The urinary protein excretion was 2.1 g/day. The plasma renin activity (PRA) and plasma aldosterone concentration were high, but the levels of catecholamines were normal. The renogram was asymmetric and on venous sampling, the PRA in the right renal vein was 58.3 ng/ml/h and that in the left was 22.1 ng/ml/h. CT scan detected an approximately 10-mm mass in the proximal right renal artery. Arteriography disclosed severe stenosis in the right renal artery and the superior mesenteric artery. Therefore, we concluded that her hypertension resulted from stenosis of the right renal artery due to neurofibromatosis. Accordingly, she underwent an operation to reconstruct that artery. After the operation, her blood pressure and PRA normalized without administration of any anti-hypertensive drug and urinary protein disappeared.

Adolescent↗
PubMed1996

Angiotensin-converting enzyme gene polymorphism in hypertensive individuals with parental history of stroke.

BACKGROUND AND PURPOSE: It has been suggested that the insertion (I)/deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) gene is an independent risk factor for coronary artery disease, but its relation to stroke has not yet been proven. We investigated an association of ACE gene polymorphism with parental history of stroke (PHS) in patients with hypertension. METHODS: We studied 70 hypertensive patients (ambulatory blood pressure > 140/90 mm Hg; age, 59 +/- 11 years) with (n = 27) or without (n = 43) PHS, defined as either one or both parents having had a stroke before 60 years of age. The ACE genotype was analyzed by polymerase chain reaction. RESULTS: Casual blood pressure and mean ambulatory blood pressure levels were not significantly different between patients with and without PHS. The incidence of left ventricular hypertrophy also did not differ significantly between the two groups. However, the frequency of the D allele was significantly higher in patients with PHS (0.72) than in patients without PHS (0.52) (chi 2 = 5.472, P = .019). The frequency of the DD genotype of the ACE gene was also significantly higher in patients with than in those without PHS (DD, 63.0%; ID, 18.5%; II, 18.5% versus DD, 32.6%; ID, 39.5%; II, 27.9%; chi 2 = 6.395, P = .041). CONCLUSIONS: The DD genotype of the ACE gene is associated with PHS in patients with hypertension, which is independent of blood pressure levels or presence of cardiac hypertrophy.

Aged↗
PubMed1996

Prediction of hemodynamic conditions by noninvasive arterial tonometry in mitral stenosis.

To predict the hemodynamic conditions in patients with mitral stenosis (MS), continuous blood pressure responses were monitored noninvasively at the bedside by arterial tonometry during the Valsalva maneuver in 18 MS patients aged 54.2 +/- 9.1 (40 approximately 77) years (6 men, 12 women). Two indices during the Valsalva maneuver (blood pressure decline value at phase III (BPdec) and subsequent blood pressure overshoot value at phase IV (BPov)) were compared with hemodynamic data obtained by the cardiac catheterization method, and the correlations between the changes in these parameters were examined. In these 18 patients, BPdec showed a significant negative correlation with the mean diastolic pressure gradient between the left atrium and left ventricle and showed a significant negative correlation with pulmonary capillary wedge pressure (PCWP) (r = - 0.62, p < 0.01, r = - 0.53, p < 0.05, respectively). Mitral valve area (MVA) showed a significant positive correlation with BPdec (r = + 0.63, p < 0.01). Similarly, BPov showed a significant positive correlation with cardiac output (CO), cardiac index (CI) and MVA (r = + 0.60, p < 0.01, r = + 0.64, p < 0.01, r = + 0.65, p < 0.01, respectively). Thus, continuous monitoring of blood pressure by arterial tonometry during the Valsalva maneuver is useful for predicting the hemodynamic conditions in patients with MS.

Adult↗
PubMed1995

Differential effects of an alpha 1-blocker (doxazosin) on diurnal blood pressure variation in dipper and non-dipper type hypertension.

A study was conducted to determine whether sympathetic nerve activity, one of the main regulators of blood pressure, is involved in high blood pressure in the night-time and morning. Twenty-seven untreated hypertensive subjects, in whom hypertension was diagnosed by ambulatory blood pressure (ABP) measurement, who showed a 24 h systolic ABP value over 140 mmHg and/or 24 h diastolic ABP over 90 mmHg were recruited. They also showed a night-time systolic ABP value of over 130 mmHg and/or a night-time diastolic ABP of over 80 mmHg. They were divided into two groups: "dippers (D)" whose night-time ambulatory blood pressure fell by more than 10% of the day-time blood pressure, and "non-dippers (ND)" in whom this phenomenon was absent. We examined the effect of a long-acting alpha 1-blocker (doxazosin) on diurnal blood pressure variation in these subjects with essential hypertension. Baseline casual blood pressure and 24 h systolic ABP were not significantly different between the two groups. However, both night-time and morning ABP in ND were higher than those in D. Administration of doxazosin (mean 73 +/- 13 (SE) d) significantly decreased casual blood pressure, and 24 h, day-time, night-time and morning systolic ABP in the whole cohort. When subjects were divided into D and ND, the day-time and morning systolic ABP decreased significantly after doxazosin treatment in both groups, whereas the night-time systolic ABP decreased significantly only in ND but not in D. These results suggest that sympathetic nerve activity involved in elevating blood pressure during the night may differ between D and ND.

Adrenergic alpha-Antagonists↗
PubMed1994

Altered levels of erythrocyte calcium-binding proteins in essential hypertensives with genetic predisposition: correlation with ambulatory blood pressure.

OBJECTIVE: To examine whether changes in calcium-binding proteins, one of the components of the calcium ion handling mechanism, occur in humans with essential hypertension. DESIGN: We measured the levels of cytosolic calcium-binding proteins purified from human erythrocytes using a felodipine fluorescence assay, and examined the correlation between this parameter and the ambulatory blood pressure (ABP). We divided 127 subjects into four age-matched groups according to their mean ABP levels and whether they had a family history of both hypertension and stroke [group A hypertensives with a positive family history (n = 30), group B hypertensives with no family history (n = 31), group C normotensives with a family history (n = 31) and group D normotensives with no family history (n = 35) of hypertension and stroke]. RESULTS: The erythrocyte cytosolic level of calcium-binding proteins in group A was significantly lower than that in group B, as was that in group C compared with group D. There was no significant correlation between the erythrocyte level of calcium-binding proteins and casual blood pressure values in any group. However, in group A significant negative correlations between the erythrocyte level of calcium-binding proteins and systolic and mean ABP were observed (r = -0.34, P < 0.05 and r = -0.39, P < 0.05, respectively). No significant correlations between the ABP and erythrocyte levels of calcium-binding proteins were observed in the other groups. When each group was subdivided according to sex, there were significant negative correlations between the erythrocyte level of calcium-binding proteins and the systolic and mean ABP in the males of groups A and C, but no correlations were found in any of the female subgroups or the males of groups B and D. Reducing the blood pressure by antihypertensive drug therapy did not affect the erythrocyte calcium-binding proteins level in 13 patients from groups A and B. Analysis using anion-exchange fast-performance liquid chromatography on a Mono-Q column and sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed that the calcium-binding proteins in human erythrocytes, the levels of which were low in group A, formed a single protein band with a molecular weight of 17,000, which was assumed to be a calmodulin. CONCLUSIONS: These results suggest that there are subgroups of hypertensive patients with low erythrocyte cytosolic levels of calcium-binding proteins, which are genetically determined. Furthermore, our data suggest that the erythrocyte level of calcium-binding proteins and ABP in male subjects with hypertension and normotensives with a genetic predisposition are correlated strongly, whereas no such correlation was observed in any female subgroup. This indicates that the regulatory mechanism or mechanisms involved in the control of blood pressure in men and women may be different.

Aging↗
PubMed1993

Alterations in cytosolic calcium-binding proteins that increase felodipine fluorescence in spontaneously hypertensive rats.

OBJECTIVE: To clarify the role of calcium-binding proteins (CaBP) in hypertension. DESIGN: CaBP from several organs of spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) rats were purified and their characteristics compared between the two strains. The CaBP were purified by applying the soluble cytosolic fractions from mesenteric vessels, heart, kidney and brain of 4- and 10-week-old SHR and WKY rats to a phenyl-Sepharose column. Felodipine binding to the purified CaBP was then measured. RESULTS: The fluorescence intensity of felodipine increased in a calcium-dependent manner when it bound to CaBP. The pK 0.5 Ca2+ values derived from the calcium ion-felodipine fluorescence curves for each CaBP preparation from organs of the two strains were similar, indicating that the calcium sensitivities of the CaBP to the felodipine binding process are similar in SHR and WKY rats. In 10-week-old SHR the mean levels of felodipine-bound CaBP in heart, brain and kidney were significantly altered compared with those in WKY rats. No such alterations were observed in heart, kidney and brain from 4-week-old SHR and WKY rats. Conversely, the mean levels of felodipine-bound CaBP in mesenteric vessels from 4- and 10-week-old SHR were reduced significantly compared with those of age-matched WKY rats. CONCLUSIONS: These results suggest that the levels of cytosolic felodipine-bound CaBP from heart, kidney and brain are altered in response to elevated blood pressure, and that reduced levels of felodipine-bound CaBP in the mesenteric vessels of SHR might be a primary characteristic of this rat strain.

Animals↗
PubMed1992

Hepatic support by hepatocyte transplantation in congenitally metabolic diseased rats.

Nagase analbuminemic rats (NAR), which lack albumin synthesis in the liver, underwent intrasplenic hepatocyte transplantation (HCTx), and the long-term effects were studied using functional and morphological examinations. Hepatocytes were isolated from congenic F344 rats with collagenase infusion, and 1 x 10(7) cells were injected into the spleen of 3-month-old NAR (n = 10). Serum albumin increased with time, reaching 53.9 mg/dl 14 months after HCTx, which was equivalent to 2.1% (maximum 4%) of serum albumin in normal rats. On the other hand, untreated NAR showed persistently low serum albumin levels (0.99 +/- 0.23 mg/dl at 10 months). According to immunostaining with anti-rat albumin antibody at 16 months after HCTx, hepatocyte grafts occupied 27-41% of the spleen area and weighed 120-420 mg, which was equivalent to 0.8-2.9% of a whole liver. Our study demonstrated that grafted hepatocytes can grow in the spleen with the ability to synthesize albumin. HCTx in NAR is a new experimental system to monitor the function and survival of grafted heptocytes without sacrificing the animals by measuring serum albumin levels. Certain manipulations to facilitate the growth of grafted hepatocytes are necessary to achieve sufficient hepatic support in HCTx.

Animals↗
PubMed1992

Enhanced spontaneous calcium efflux and decrease of calcium-dependent calcium release from the isolated perfused heart of spontaneously hypertensive rats.

OBJECTIVE: The aim of this study was to clarify the further details of calcium handling in hypertension. DESIGN: By preserving the physiological environment of cell membrane, whole hearts were used for comparison of calcium flux between spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. METHODS: Hearts from SHR and WKY rats were perfused with Krebs-Henseleit solution under constant flow and the effluent collected. RESULTS: After labelling of the heart with 45Ca2+ (100 mumol/l), 45Ca2+ binding was found to be saturated, and washing with calcium-free perfusion solution showed two exponential curves for calcium dissociation, indicating a fast (alpha-) and slow (beta-) phase. The half-lives of the beta-phase for both 4- and 8-week-old SHR were significantly shorter than those for age-matched WKY. Also in this phase, infusion of non-radioactive Ca2+ caused a transient dose-dependent release of 45Ca2+. A significant reduction in the amount of 45Ca2+ release induced by 2 mmol/l Ca2+ was observed in both 4- and 8-week-old SHR compared with age-matched WKY rats. Infusion of lanthanum, caffeine, ionomycin (calcium ionophore) and treatment of the hearts with ethyleneglycol-bis-(beta-aminoethylether)-N,N,N,',N'-tetraac etic acid did not alter 45Ca2+ release by non-radioactive Ca2+. From these observations, 45Ca2+ is presumably released from the intracellular calcium pool, and not from extracellular binding sites or sarcoplasmic reticulum. CONCLUSIONS: These findings suggest that an abnormal calcium-handling defect (enhanced calcium efflux and reduction of membrane-bound Ca2+) exists under physiological conditions before and after the onset of hypertension, and that this may be a primary characteristic of SHR.

Aging↗
PubMed1992

[A study of progression in hepatocarcinogenesis using cell transplantation system].

It is important to distinguish a precancerous lesion and hepatocellular carcinoma (HCC) with diploidy or aneuploidy nuclear DNA pattern, not only in clinical cases but also in experimental carcinogenesis models. Using liver perfusion technique, we detected early HCC from persistent hyperplastic nodules (HN) which were induced in Wistar rats by intermittent 5-6 months administration of 2-acetylaminofluorene. This investigation was undertaken to assess both promotive and progressive effects of liver regeneration following partial hepatectomy (PH). Results are as follows: 1) Isolated hepatocytes of precancerous HN, which were transplanted into the spleen, didn't develop to HCC by 2 months after 70% PH of host liver. 2) Diced tissues of HCC, which were transplanted into the liver via portal vein, grew many metastasis in 10/10 by 7 weeks after PH, while 5/19 in control. 3) Nuclear DNA patterns of early HN-late HCC in rat liver were diploidy at the rate of more than 90% each. But it changed to aneuploidy, when inoculation of HCC for one month was repeated 7 times in the spleen.

Animals↗
PubMed1991

Reduced calcium sensitivity of dihydropyridine binding to calcium channels in spontaneously hypertensive rats.

To explore the role of calcium channels in hypertension, dihydropyridine ([3H]PN200-110) binding to heart, brain, and skeletal muscle microsomes of 4-, 8- and 15-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats was measured. At a constant Ca2+ ion concentration (pCa 3.0), maximal binding (Bmax) of dihydropyridine binding to heart and brain microsomes was significantly enhanced in 8- and 15-week-old SHR compared with WKY rats (p less than 0.01), whereas this phenomenon was not observed in 4-week-old SHR and WKY rats. Bmax and dissociation constant (Kd) values for skeletal muscle microsomes from SHR showed no difference compared with WKY rats irrespective of age. Dihydropyridine binding to heart microsomes, brain microsomes, and solubilized skeletal muscle microsomes exhibited strong calcium dependence. The Ca2(+)-dependent dihydropyridine binding curves for heart showed a Hill slope, and pK 0.5 values for 15-week-old SHR and WKY rats were 0.70 +/- 0.12 and 4.66 +/- 0.12 versus 0.72 +/- 0.12 and 5.66 +/- 0.08 (n = 4, mean +/- SD), respectively, indicating that 15-week-old SHR require 10-fold higher calcium concentration than WKY rats to promote dihydropyridine binding. The pK 0.5 values of calcium for brain and solubilized skeletal muscle calcium channels in 15-week-old SHR were also significantly lower than in WKY rats. This difference first became apparent in SHR and WKY rats as early as 4 and 8 weeks after birth. These results suggest that enhancement of calcium channel density might occur in the heart and brain of SHR in response to elevated blood pressure and that reduced calcium sensitivity of dihydropyridine binding to calcium channels might be a primary characteristic of this rat strain.

Animals↗
PubMed1991

Augmented Na,K-ATPase gene expression in spontaneously hypertensive rat hearts.

Abnormalities in cardiovascular Na,K-ATPase ion-transport function and regulation may play an important role in the pathogenesis of hypertension. However, it is not known whether these abnormalities are secondary to the effects of hypertension, such as increased pressure, or reflect an intrinsic abnormality in Na,K-ATPase gene expression and regulation. A genetic model of hypertension was used to address this issue. Na,K-ATPase alpha subunit gene expression in hearts was compared between spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Pre-hypertensive, 4-week old SHR hearts exhibited an approximately 4 fold elevation in alpha 1 and 8 fold elevation in alpha 2 mRNA levels compared with age-matched WKY hearts. These SHR mRNA levels remained almost equivalent throughout the development of hypertension at 8 and 16 weeks of age. WKY alpha 1 and alpha 2 mRNA levels exhibited a progressive increase during the same time period. The neonatal alpha 3 mRNA isoform was detected only in pre-hypertensive (4-week) SHR hearts. We conclude that cardiac Na,K-ATPase alpha subunit gene expression is significantly altered in SHR even before the onset of hypertension. These findings suggest that an abnormality in cardiac Na,K-ATPase gene expression constitutes an early, if not primary, event in spontaneous hypertension.

Animals↗