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Biomedical subjects

A Ebihara

Publications and source records attributed to A Ebihara.

At least 19 recordsLinked to original sources
PubMed2006

Influence of phase transformation on the torsional and bending properties of nickel-titanium rotary endodontic instruments.

AIM: To investigate the relationship between the functional properties and the phase transformation of nickel-titanium endodontic instruments. METHODOLOGY: Five types of rotary nickel-titanium endodontic instruments with a 0.30 mm diameter tip (EndoWave, HERO 642, K3, ProFile.06, and ProTaper) were selected to investigate torsional and bending properties, and phase transformation behaviour. A torsional test was performed according to ISO publication 3630-1, and maximum torque and angular deflection at fracture were measured. Bending load of the instruments was measured in a cantilever-bending test at 37 degrees C with the maximum deflection of 4.0 mm. A stainless steel K-file was used for reference. Phase transformation behaviour was measured by differential scanning calorimetry (DSC). From the DSC curve, transformation temperatures were calculated. Data were analysed by anova and the Tukey-Kramer's test. RESULTS: The maximum torsional torque values of HERO, K3 and ProTaper were significantly higher (P < 0.05) than those of EndoWave, ProFile and K-file. The K-files had the lowest torque value. Angular deflection at fracture was significantly higher (P < 0.05) for K-files than that for any nickel-titanium instrument. The bending load values of HERO and K3 were significantly higher (P < 0.05) than those of EndoWave, ProFile, ProTaper and K-file. The K-files had the lowest load value, although residual deflection remained. The transformation temperatures of HERO and K3 were significantly lower (P < 0.05) than those of EndoWave, ProFile and ProTaper. CONCLUSIONS: The functional properties of nickel-titanium endodontic instruments, especially their flexible bending load level, were closely related to the transformation behaviour of the alloys.

Calorimetry, Differential Scanning↗
PubMed2005

Garrè's osteomyelitis managed by root canal treatment of a mandibular second molar: incorporation of computed tomography with 3D reconstruction in the diagnosis and monitoring of the disease.

AIM: To report the healing of Garrè's osteomyelitis involving a mandibular second molar following root canal treatment. SUMMARY: To describe the endodontic management of Garrè's osteomyelitis involving a mandibular second molar. In this case, computed tomography (CT) was used to evaluate the status of the periapical lesion. Five years after root canal treatment, the tooth and supporting tissues appeared healthy both clinically and radiographically and were functioning well. KEY LEARNING POINTS: Garrè's osteomyelitis of an adult can be managed by root canal treatment. Computed tomography could be used for diagnosis and treatment planning in endodontics.

Adult↗
PubMed2002

Er:YAG laser modification of root canal dentine: influence of pulse duration, repetitive irradiation and water spray.

The aim of this study was to determine the effects of varying parameters of Er:YAG laser irradiation with and without water spray cooling on root canal dentine in vitro. After horizontally removing tooth crowns from extracted human teeth, roots were axially sectioned into thin slices, exposing the root canal surface. An Er:YAG laser delivered 10-30 J/cm(2) into a 0.4-mm diameter laser spot on the root canal surface. Single pulses of different lengths (80-280 micro s) were applied with and without water spray cooling/irrigation, and sequences of three pulses at a repetition rate of 30 Hz were applied at selected pulse parameters. The irradiated samples were investigated using both confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). At most irradiation conditions, the root canal dentine surface was ablated. Three-dimensional images from CLSM revealed that the cavity walls were not smooth. Depths of the cavities revealed significant differences between the cavities. No debris was observed at the surface of cavities at any irradiation condition. Strong melting and recrystallisation, or unusually flat surfaces with open dentinal tubules were obtained with sequences of three pulses without water cooling. CLSM is an effective tool for investigation of laser effects on root canal dentine. By varying the irradiation conditions, the Er:YAG laser can induce different modifications of root canal surface, which may be very interesting for root canal preparation.

Dental Pulp Cavity↗
PubMed2001

Renal damage and salt-dependent hypertension in aged transgenic mice overexpressing endothelin-1.

The recent development of endothelin-1 (ET-1) antagonists and their potential use in the treatment of human disease raises questions as to the role of ET-1 in the pathophysiology of such cardiovascular ailments as hypertension, heart failure, renal failure and atherosclerosis. It is still unclear, for example, whether activation of an endogenous ET-1 system is itself the primary cause of any of these ailments. In that context, the phenotypic manifestations of chronic ET-1 overproduction may provide clues about the tissues and systems affected by ET-1. We therefore established two lines of transgenic mice overexpressing the ET-1 gene under the direction of its own promoter. These mice exhibited low body weight, diminished fur density and two- to fourfold increases in the ET-1 levels measured in plasma, heart, kidney and aorta. There were no apparent histological abnormalities in the visceral organs of young (8 weeks old) transgenic mice, nor was their blood pressure elevated. In aged (12 months old) transgenic mice, however, renal manifestations, including prominent interstitial fibrosis, renal cysts, glomerulosclerosis and narrowing of arterioles, were detected. These pathological changes were accompanied by decreased creatinine clearance, elevated urinary protein excretion and salt-dependent hypertension. It thus appears that mild, chronic overproduction of ET-1 does not primarily cause hypertension but triggers damaging changes in the kidney which lead to the susceptibility to salt-induced hypertension.

Aging↗
PubMed2001

Vascular abnormalities and elevated blood pressure in mice lacking adrenomedullin gene.

BACKGROUND: Adrenomedullin (AM) is a vasodilating peptide involved in the regulation of circulatory homeostasis and in the pathophysiology of certain cardiovascular diseases. Levels of AM are markedly increased in the fetoplacental circulation during pregnancy, although its function there remains unknown. To clarify the physiological functions of AM, we chose a gene-targeting strategy in mice. METHODS AND RESULTS: Targeted null mutation of the AM gene is lethal in utero: the mortality rate among AM(-/-) embryos was >80% at E13.5. The most apparent abnormality in surviving AM(-/-) embryos at E13.5 to E14.0 was severe hemorrhage, readily observable under the skin and in visceral organs. Hemorrhage was not detectable at E12.5 to E13.0, although the yolk sac lacked well-developed vessels. Electron microscopic examination showed endothelial cells to be partially detached from the basement structure at E12.5 in vitelline vessels and hepatic capillaries, which allowed efflux of protoerythrocytes through the disrupted barrier. The basement membrane was not clearly recognizable in the aorta and cervical artery, and the endothelial cells stood out from the wall of the lumen, only partially adhering to the basement structure. AM(+/-) mice survived to adulthood but exhibited elevated blood pressures with diminished nitric oxide production. CONCLUSIONS: AM is indispensable for the vascular morphogenesis during embryonic development and for postnatal regulation of blood pressure by stimulating nitric oxide production.

Adrenomedullin↗
PubMed2001

Effect of fluvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on nitric oxide-induced hydroxyl radical generation in the rat heart.

We examined the effect of fluvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on the production of hydroxyl radical (*OH) generation via nitric oxide synthase (NOS) activation by an in vivo microdialysis technique. The microdialysis probe was implanted in the left ventricular myocardium of anesthetized rats and tissue was perfused with Ringer's solution through the microdialysis probe at a rate of 1 microl/min. Sodium salicylate in Ringer's solution (0.5 nmol/microl/min) was infused directly through a microdialysis probe to detect the generation of *OH. Induction of [K(+)](o) (70 mM) or tyramine (1 mM), significantly increased the formation of *OH trapped as 2,3-dihydroxybenzoic acid (DHBA). The application of N(G)-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, significantly decreased the K(+) depolarization-induced *OH formation, but the effect of tyramine significantly increased the level of 2,3-DHBA. When fluvastatin (100 microM), an inhibitor of low-density lipoprotein (LDL) oxidation, was administered to L-NAME-pretreated animals, both KCl and tyramine failed to increase the level of 2,3-DHBA formation. The effect of fluvastatin may be unrelated to K(+) depolarization-induced *OH generation. To examine the effect of fluvastatin on ischemic/reperfused rat myocardium, the heart was subjected to myocardial ischemia for 15 min by occlusion of the left anterior descending coronary artery (LAD). When the heart was reperfused, a marked elevation of the level of 2,3-DHBA was observed. However, in the presence of fluvastatin (100 microM), the elevation of 2,3-DHBA was not observed in ischemia/reperfused rat heart. Fluvastatin, orally at a dose of 3 mg/kg/day for 4 weeks, significantly blunted the rise of serum creatine phosphokinase and improved the electrocardiogram 2 h after coronary occlusion. These results suggest that fluvastatin is associated with a cardioprotective effect due to the suppression of noradrenaline-induced *OH generation by inhibiting LDL oxidation in the heart.

Animals↗
PubMed2001

Profiles of patients who control the doses of their antihypertensive drugs by self-monitoring of home blood pressure.

The present study profiled patients who control doses of antihypertensive drugs by themselves based on self-monitoring of their blood pressure (self-controllers). A total of 1,028 consecutive outpatients who were taking antihypertensive drugs and who were attending the cardiovascular outpatient clinic of our institute responded to a questionnaire in 1998. They were asked how often they measured their blood pressure, how often they missed taking their medication, and whether or not they had a chance to adjust the doses of antihypertensive drugs by themselves based on self-monitored blood pressure. The frequency of self-controlling of antihypertensive drugs was also examined in 918 patients on antihypertensive drugs in 1997. In 1997, 23 of 918 patients (2.5%) were self-controllers, and 26 of 1,028 patients (2.5%) were self-controllers in 1998. The frequency of home blood-pressure measurement was significantly greater in self-controllers than in the remaining patients (non self-controllers) (p<0.01). The prevalence of proteinuria was significantly less in the former than in the latter. Prior to the start of antihypertensive drugs, blood pressure was significantly lower for the self-controllers (154.4+/-3.8/96.4+/-1.4 mmHg) than for the non self-controllers (169.3+/-0.7/101.7+/-0.4 mmHg) (p<0.001). Clinically measured blood pressures did not differ significantly between the self-controllers and non self-controllers. Thus, about 2.5% of patients on antihypertensive drugs controlled their drug doses by themselves based on self-monitoring of their blood pressure. These patients were characterized by having a milder form of hypertension and by more frequent home blood-pressure measurement than non self-controllers.

Aged↗
PubMed2001

[An autopsied case of marked cardiac hypertrophy due to multifactorial heart disease in an 85 year-old man who had been socially active].

An autopsied 85-year-old man had suffered from a mild form of diabetes mellitus since the age of 67 and had experienced the first episode of heart failure with arapid ventricular rate of atrial fibrillation at the age of 72. He had remained socially active until he died suddenly of ventricular fibrillation, although he had complications of aortic regurgitation at the age of 76 and later mitral regurgitation at the age of 80. Chest roentgenograms showed gradual increase in the cardiothoratic ratio which reached 68.1% at the final stage. Autopsy revealedmarked left ventricular hypertrophy with a heart weight of 580 g, degeneration ofaortic valves, thickening of mitralvalve cusps and moderate coronary atherosclerosis without ischemic myocardial lesions. There were no specific lesions suggestive of primary cardiomyopathies on microscopic observations and the lesions of both aortic and mitral valves were not significant enough to explain the clinical findings of aortic and mitral regurgitation. Because the pathological examination failed to identify a single disease which was responsible for the marked cardiachypertrophy, we eventually reached the conclusion that the cardiac hypertrophy developed based on a multifactorial heart disease.

Activities of Daily Living↗
PubMed2000

Evidence for association between paraoxonase gene polymorphisms and atherosclerotic diseases.

Paraoxonase 1 (PON1) is proposed to have an anti-atherogenic action. Two polymorphisms at the PON1 (M/L55 and Q/R192) have been shown to be associated with coronary artery disease (CAD). This conclusion is not drawn universally, however, and specific ethnic characteristics may be important determinants in this association. Recently two homologues of PON1 - PON2 and PON3 - were identified and Sanghera et al. demonstrated C/S311 polymorphism at PON2 was associated with the risk of CAD. Within that context, we investigated the association between the aforementioned three polymorphisms and CAD and ischemic stroke in a Japanese population. The study population included 431 control subjects, 210 CAD patients, and 235 ischemic stroke patients. Genotype distributions and allele frequencies of M/L55 and C/S311 were similar among the control and patient groups, whereas the R192 allele frequency was significantly higher (P<0.001) in CAD (75%) and ischemic stroke (76%) patients than in control subjects (65%). When confounding influences of other risk factors were controlled for by multivariate analysis, R192 remained an independent risk determinant (additive model: OR (95% CI), P value CAD: 2.01 (1.45-2.79), 0.0001; ischemic stroke: 1.84 (1.34-2.52), 0.0002 (three genotypes into calculation)). Taken together, our data indicate that the Q/R192 is principally associated with both CAD and ischemic stroke in Japanese.

Aged↗
PubMed2000

Fluvastatin, a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, resists hydroxyl radical generation in the rat myocardium.

The aim of this study was to determine whether fluvastatin, an inhibitor of low-density lipoprotein (LDL) oxidation, can resist Cu (II)-induced hydroxyl radical generation (*OH) in the extracellular fluid of rat myocardium. Rats were anaesthetized and sodium salicylate in Ringer's solution (0.5 nmol microL(-1) min(-1)) was infused through a microdialysis probe to detect the generation of *OH as reflected by the non-enzymatic formation of 2,3-dihydroxybenzoic acid (2,3-DHBA) in the myocardium. When Cu (II) (0, 10, 25 or 50 microM) was administered to 1 mM tyramine-pretreated rats, a marked elevation in the levels of 2,3-DHBA was found, indicating a positive linear correlation between Cu (II) and the increase in *OH formation trapped as 2,3-DHBA in the dialysate (r2 = 0.977). In the presence of fluvastatin (100 microM), a marked decrease in the levels of 2,3-DHBA was found. Corresponding experiments performed with iron (II) (0, 10, 25 or 50 microM), showed a marked elevation in the levels of 2,3-DHBA, indicating a positive linear correlation between iron (II) and the increase in *OH formation trapped as 2,3-DHBA in the dialysate (r2 = 0.986). However, in the presence of fluvastatin (100 microM) a small decrease in the level of 2,3-DHBA was found. The results show that iron (II) against LDL oxidation may be insensitive compared with Cu (II). Cu (II)-induced *OH formation may be reduced by inhibiting LDL with fluvastatin.

Animals↗
PubMed2000

Relationship between home blood pressure measurement and medication compliance and name recognition of antihypertensive drugs.

This study examined the relationship of home blood pressure measurement to medication compliance and name recognition of antihypertensive drugs in outpatients with hypertension. A total of 1,452 consecutive outpatients (842 males, 610 females; mean age 65+/-11 yr) seeking care at our institute answered questions at our cardiovascular outpatient clinic such as whether they had a sphygmomanometer at home, how often they measured their blood pressure at home, and how often they missed taking their medication. Among a total of 777 patients on antihypertensive drugs who had a sphygmomanometer at home, 16 of the 242 patients (6.5%) who measured their home blood pressure every day occasionally missed taking their medication, whereas this number was 22 for the 216 patients (10.1%) who measured their home blood pressure several times a week, 16 for the 146 patients (11.0%) who measured their home blood pressure several times a month, and 25 for the 173 patients (14.5%) who never measured their home blood pressure (p< 0.01 between patients who measured their home blood pressure every day and those who did not measure their home blood pressure). Among a total of 271 patients taking one or two antihypertensive drugs, the number of patients who could name their antihypertensive drugs was 47 of the 86 patients (55%) who measured their home blood pressure every day, 43 of the 78 patients (55%) who measured their home blood pressure several times a week, 24 of the 41 patients (58%) who measured their home blood pressure several times a month, and 22 of the 66 patients (33%) who never measured their home blood pressure (p< 0.02). In conclusion, medication compliance and antihypertensive drug name recognition were better in patients who measured their home blood pressure than in patients who did not measure their home blood pressure. From these results, we conclude that physicians should recommend home blood pressure measurement to patients being treated with antihypertensive drugs, because there is a possibility that home blood pressure measurement might improve medication compliance.

Aged↗
PubMed2000

Distinct increase in hematocrit associated with paroxysm of atrial fibrillation.

In a previous study we found that hemoconcentration, which was identified by an increase in hematocrit, occured during a paroxysm of atrial fibrillation. In the present study we investigated the changes in hematocrit from sinus rhythm to paroxysm in 10 patients who had multiple paroxysms of atrial fibrillation in order to assess the ranges of the changes in hematocrit among the paroxysms. In these patients hematocrit was measured simultaneously with electrocardiographic recording during 3 or more paroxysms and sinus rhythm just before each paroxysm. The changes in hematocrit varied among the paroxysms. The maximum increase in hematocrit in each patient ranged from 3.5 to 8.0 points with an average of 5.1 points. Such a distinct increase in hematocrit which abruptly develops with a paroxysm of atrial fibrillation may be a potential risk for thrombus formation.

Aged↗
PubMed2000

Transient mitral regurgitation following vagal stimulation-induced ventricular arrhythmia in rabbits: a color Doppler echocardiographic study.

BACKGROUND AND AIM OF THE STUDY: Cervical vagal stimulation in rabbits frequently causes systolic murmur with bigeminy due to premature ventricular contractions. The bigeminy disappears in a few minutes, but the systolic murmur persists for a few days. Peculiar lesions of the mitral valves, mitral annulus and papillary muscles, and an increase in left atrial weight, frequently develop in a week. In this study, color Doppler echocardiography was used to examine whether the systolic murmur was due to mitral regurgitation. METHODS: Echocardiographic monitoring was carried out in anesthetized rabbits restrained in the supine position. RESULTS: Doppler echocardiography and phonocardiography showed systolic murmur at 6 h, three days, and at one, two, three and four weeks after vagal stimulation. At 6 h after stimulation, phonocardiography showed systolic click and late systolic murmur; Doppler echocardiography showed marked mitral regurgitation. The systolic murmur and mitral regurgitation were attenuated and the papillary muscle was swollen three days after vagal stimulation. Following stimulation, mitral regurgitation disappeared within one week, and papillary muscle swelling improved after three weeks. CONCLUSION: Doppler echocardiography confirmed that systolic murmur caused by vagal stimulation in rabbits was due to mitral regurgitation.

Animals↗
PubMed1999

Rationale for time-qualified reference standards for 24-hour blood pressure values and their circadian rhythms in Japanese normotensive adults: a study by the Ambulatory Blood Pressure Monitoring Research Group.

The aim of this study was to demonstrate that blood pressure (BP) has to be standardized according to its circadian variability, including the properties shown in its circadian rhythm. The BP time-qualified standards were derived from a sample of 644 clinically healthy normotensive Japanese subjects (320 males, 324 females; age range, 18-93 years), stratified by age-group and gender, who underwent noninvasive ambulatory monitoring according to a fixed protocol. The monitored data series shows that BP exhibits a within-day variability at any age of life in both males and females. Additionally, the monitored data series shows that BP exhibits a significant circadian rhythm at any age of life in both males and females. The age- and sex-related reference limits for the BP within-day variability constitute the time-qualified standards against which both the casual and monitored BP measurements can be compared in order to detect whether or not they are compatible with normotension. The reference limits for the BP circadian rhythm represent the rhythmometric standards against which the BP oscillatory curve can be compared in order to detect whether or not they are compatible with a physiological circadian rhythm.

Adolescent↗