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Biomedical subjects

N Yoshimoto

Publications and source records attributed to N Yoshimoto.

At least 19 recordsLinked to original sources
PubMed2006

Protective effect against 17beta-estradiol on neuronal apoptosis in hippocampus tissue following transient ischemia/recirculation in mongolian gerbils via down-regulation of tissue transglutaminase activity.

We analyzed the protective effect of 17beta-estradiol (17beta-ED) injection against delayed neuronal death in the hippocampus tissue of the brain in Mongolian gerbils after transient ischemia/recirculation treatment, especially in relation with bcl-2 gene expression and enzymatic activity changes of caspase-3 and tissue transglutaminase (tTGase). Daily intraperitoneal injection of 17beta-ED to the animal after the ischemia stimulated the expression of an apoptosis suppressor gene, bcl-2, in the hippocampal tissue for a week. The gradually increasing apoptotic enzyme activity of caspase-3 and increased number of TUNEL positive fragmented neuronal nuclei caused by ischemic attack in the gerbil brain were clearly suppressed by 17beta-ED administration. The reduced activity and enzyme protein of tTGase, a neurodegenerative marker of apoptosis in the hippocampus after ischemia, were also restored to nearly normal levels by 17beta-ED injection. These results suggest that daily 17beta-ED administration to the gerbil after transient ischemic insult with progressing neuronal deteriorative changes in hippocampus tissue can effectively prevent apoptotic changes through a molecular cascade involving gene expression regulation.

Animals↗
PubMed2006

Clinical application of carbon fibre reinforced plastic leg orthosis for polio survivors and its advantages and disadvantages.

A prospective study was carried out on the clinical application and features of a carbon fibre reinforced plastic leg orthosis (carbon orthosis) for polio survivors. The subjects comprised 9 polio survivors, and 11 carbon knee-ankle-foot orthoses (KAFOs) were prescribed, fabricated, and checked out at the authors' post-polio clinic. Walking was classified based on the functional ambulatory category, and the features of walking with a carbon orthosis were self-evaluated by using a visual analogue scale. The period from modelling a cast to completion was 55 +/- 25 days; the weight of a carbon KAFO was 27.8% lighter than that of the ordinary KAFO; the standard carbon KAFO was 50% more expensive than the ordinary KAFO. The carbon KAFO remained undamaged for at least 2 years. It improved the scores in the functional ambulation categories, but there was no difference between walking with an ordinary and with a carbon KAFO. The self-evaluation of walking with a carbon KAFO revealed that the subjects using a carbon KAFO were satisfied with their carbon KAFO. The carbon KAFO is lightweight, durable, slim and smart, and is positively indicated for polio survivors.

Braces↗
PubMed2004

Control of carrier density by self-assembled monolayers in organic field-effect transistors.

Organic thin-film transistors are attracting a great deal of attention due to the relatively high field-effect mobility in several organic materials. In these organic semiconductors, however, researchers have not established a reliable method of doping at a very low density level, although this has been crucial for the technological development of inorganic semiconductors. In the field-effect device structures, the conduction channel exists at the interface between organic thin films and SiO(2) gate insulators. Here, we discuss a new technique that enables us to control the charge density in the channel by using organosilane self-assembled monolayers (SAMs) on SiO(2) gate insulators. SAMs with fluorine and amino groups have been shown to accumulate holes and electrons, respectively, in the transistor channel: these properties are understood in terms of the effects of electric dipoles of the SAMs molecules, and weak charge transfer between organic films and SAMs.

Computer Simulation↗
PubMed2003

Diaphragmatic hernia resulting from injury during microwave-assisted laparoscopic hepatectomy.

A 31-year-old woman underwent microwave-assisted laparoscopic hepatectomy of the left lateral segment for focal nodular hyperplasia on January 14, 1998. On September 9, 1998, she felt continuous left abdominal pain and was admitted to our hospital for further examination. An upper gastrointestinal series showed converging folds of the greater curvature of the upper third of the stomach and craniad displacement of this portion. Thoracic magnetic resonance imaging showed herniation of the stomach into the pleural cavity. The patient was referred to our department, where she underwent surgery for a diaphragmatic hernia. The fundus of the stomach had escaped into the left pleural cavity through a defect in the diaphragm near where laparoscopic hepatectomy had been performed. The stomach was returned to the peritoneal cavity and the defect sutured. The patients postoperative course was uneventful. Although diaphragmatic hernia after laparoscopic surgery is a rare complication, with the performance of more advanced laparoscopic procedures and the use of higher-technology tissue-destruction/hemostatic devices such as the microwave coagulator, more caution should be observed to prevent injury to adjacent organs such as the diaphragm.

Abdominal Pain↗
PubMed2001

Mechanisms of hydrogen peroxide-induced relaxation in rabbit mesenteric small artery.

The effects of hydrogen peroxide were studied on isolated rabbit mesenteric small artery; rabbit superior mesenteric artery and mouse aorta were also studied as reference tissues. For mesenteric small artery, hydrogen peroxide (1 to 100 microM) relaxed a norepinephrine-stimulated artery in a concentration-dependent manner. The relaxation was not significantly affected by removal of the endothelium and was less pronounced in arteries contracted with high-KCl solution plus norepinephrine than in those contracted with norepinephrine alone. The relaxation response to hydrogen peroxide was increased by isobutylmethylxanthine and zaprinast, inhibited by diclofenac, methylene blue and dithiothreitol and unaffected by atropine, tetraethylammonium, superoxide dismutase, deferoxamine, dimethyl sulfoxide or the Rp stereoisomer of adenosine cyclic monophosphothioate. Hydrogen peroxide shifted concentration-contractile response curves for norepinephrine to the right and downwards. Norepinephrine and caffeine elicited a transient, phasic contraction of the mesenteric small artery exposed for 0.5, 1 and 2 min to a Ca2+-free solution. Hydrogen peroxide inhibited the norepinephrine-induced contraction, and to a lesser extent the caffeine-induced contraction, and verapamil did not alter the contraction to norepinephrine. These pharmacological properties of hydrogen peroxide were similar to those of 8-bromo cGMP; 8-bromo cGMP inhibited more potently the norepinephrine-induced than the KCl-induced contraction and the contraction elicited by norepinephrine in Ca2+-free solution. The present results suggest that hydrogen peroxide induces endothelium-independent relaxation of the rabbit mesenteric small artery precontracted with norepinephrine. The effects of hydrogen peroxide may be at least in part mediated by cGMP and cyclooxygenase products in the vascular smooth muscles now used.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2001

Nicorandil, a potent cardioprotective agent, reduces QT dispersion during coronary angioplasty.

BACKGROUND: Previous studies have found that ST-segment elevation and QT dispersion are smaller in second coronary occlusions than in first occlusions, a trend that suggests ischemic preconditioning. It has not been established whether nicorandil reduces ST-segment elevation and QT dispersion during coronary angioplasty. METHODS AND RESULTS: Thirty patients with stable angina undergoing coronary angioplasty in the proximal left anterior descending artery were randomly assigned to one of two groups, receiving either 5 mg oral nicorandil 3 times daily (n = 15) or placebo (n = 15). In the control patients, the total ST-segment elevation decreased from 14 +/- 3 mm during the first inflation to 7 +/- 2 mm during the second inflation (P < .01). In contrast, in the nicorandil-treated patients, the total ST-segment elevation during the second inflation was roughly equivalent to that during the first inflation (8 +/- 3 mm vs 8 +/- 3 mm, P = not significant). After the first reperfusion, a significantly smaller increase in QT dispersion was observed in the nicorandil-treated patients than in the control patients (43 +/- 15 ms vs 54 +/- 15 ms, P < .001). However, after the second reperfusion, QT dispersion was similar for the two groups (32 +/- 15 ms vs 34 +/- 13 ms, P = not significant). CONCLUSIONS: Nicorandil may precondition the myocardium and may prevent the occurrence of ventricular arrhythmias after coronary reperfusion by suppressing the increase in QT dispersion.

Angina Pectoris↗
PubMed2001

[Management and treatment of osteoporotic patients at gynecological clinic base].

The importance of diagnosis and management of osteoporosis at out-patient based gynecological clinic was mentioned. For the diagnosis of osteoporosis, assessment of spinal bone mineral density by DEXA system is necessary. This data is useful for the evaluation of treatment and the management of the patient motivation. Hormone replacement therapy is effective for postmenopausal osteoporosis, but in Japan patient acceptance of HRT is still low, and thus gynecologists are required of more effort to get an informed consent of HRT from the patient. As there is a large social demand of improving the quality of life of postmenopausal women, clinic based education of HRT to the postmenopausal women is also necessary for an easy acceptance of HRT in future.

English Abstract↗
PubMed2000

QT dispersion in patients with Takayasu arteritis.

This study was designed to test the hypothesis that myocardial involvement exists in patients with Takayasu arteritis and is associated with increased QT dispersion, which is a marker of repolarization inhomogeneity. Twenty-one consecutive patients with Takayasu arteritis and no significant coronary artery disease were included. Twelve-lead electrocardiogram and exercise-induced thallium-201 myocardial scintigraphy were performed in all patients. Ten of 21 patients (48%) had abnormal findings on scintigraphy. Patients were divided into two groups by the presence (group P, n = 10) or absence (group N, n = 11) of exercise-induced thallium-201 myocardial scintigraphic perfusion abnormalities, including permanent defects in three, reversible defects in four, and slow washout in three. The QT dispersion at rest was significantly greater in group P than that in group N (54 +/- 12 vs 40 +/- 8 msec, p < 0.005). The QTc dispersion at rest was also significantly greater in group P than in group N (59 +/- 15 vs 43 +/- 11 msec, p < 0.01). In patients with Takayasu arteritis, myocardial involvement suggested by exercise-induced thallium-201 myocardial scintigraphic perfusion abnormalities is not rare, even when no significant coronary stenosis is present on angiography. Increased baseline QT dispersion was associated with scintigraphic abnormalities and may be a useful marker of myocardial involvement in patients with Takayasu arteritis.

Adult↗
PubMed1999

Nicorandil, a potassium channel opener, abolished torsades de pointes in a patient with complete atrioventricular block.

TdP is a serious complication of AV block. We report a case of complete AV block with QT prolongation who had bouts of TdP resistant to lidocaine and isoproterenol. Temporary pacing could not be performed, because insertion of a pacing lead triggered TdP that deteriorated into ventricular fibrillation. Nicorandil, a potassium channel opener, shortened the QT interval and abolished TdP. This may suggest that potassium channel opening drugs are clinically effective against TdP associated with bradycardia-dependent QT prolongation.

Aged↗
PubMed1999

New method of estimating myocardial infarct size using technetium-99m pyrophosphate and thallium-201 dual single photon emission computed tomography imaging.

A new method was devised to estimate infarct size using dual single photon emission computed tomography with thallium-201 and technetium-99m pyrophosphate. Designating the ratio of infarct area to whole myocardial volume as %MI, the correlation of %MI with other markers of left ventricular dysfunction was examined: peak creatine kinase, ejection fraction and left ventricular asynergy. As %MI correlated well with these markers, it is considered that %MI will be useful for estimating infarct size and predicting the severity of left ventricular dysfunction in the early stage of acute myocardial infarction.

Adult↗
PubMed1998

Alteration of enzymatic activities implicating neuronal degeneration in the spinal cord of the motor neuron degeneration mouse during postnatal development.

Oxidative stress is suggested as a significant causative factor for pathogenesis of neuronal degeneration on spinal cord of human ALS. We measured some enzymic activities implicating neuronal degeneration process, such as cytochrome c oxidase (CO), superoxide dismutase (SOD), and transglutaminase (TG) in spinal cord of an animal model of ALS, motor neuron degeneration (Mnd) mouse, a mutant that exhibits progressive degeneration of lower spinal neurons during developmental growth, and compared them with age-matched control C57BL/6 mice. CO activity in Mnd spinal cord decreased during early postnatal period, while SOD activity reduced in later stage. In Mnd tissue, TG activity in lumbar cord was increasing during early stage, but tended to decline in later period gradually. These biochemical alterations became evident prior to the appearance of clinical motor dysfunction which were observed in later stages of development in Mnd spinal cord.

Aging↗
PubMed1998

Class IC antiarrhythmic drugs, flecainide and pilsicainide, produce ST segment elevation simulating inferior myocardial ischemia.

Flecainide and pilsicainide, Class IC antiarrhythmic drugs with slow kinetics, were administered to a 64-year-old man experiencing ventricular tachycardia. Both drugs suppressed the arrhythmia, but caused ST segment elevation in leads II, III, and aVF. No evidence of ischemic heart disease was detected. Withdrawal of the drugs eliminated the ST change. Because these drugs frequently are used to treat tachyarrhythmias in patients who may present with chest pain, this rare ECG manifestation of Class IC drugs should be recognized to avoid misdiagnosis of acute inferior myocardial infarction.

Anti-Arrhythmia Agents↗
PubMed1998

Coronary artery-pulmonary artery fistula originating from three major coronary branches associated with exertional chest pain and tachycardia-dependent left bundle branch block.

A 49-year-old male was admitted to our hospital because of chest pain. The pain occurred simultaneously with tachycardia-dependent left bundle branch block (LBBB) during exercise-stress and atropine-stress electrocardiogram (ECG) and on 24-h ambulatory ECG monitoring. Myocardial perfusion and metabolic scintigraphy with Tl-201 and I-123 BMIPP, respectively, showed no evidence of ischemia. Coronary arteriography revealed no atherosclerotic lesions, but did show a fistula between three major coronary arteries and the main pulmonary artery. The left-to-right shunt was undetectably small. Administration of diltiazem and metoprolol suppressed LBBB by attenuating the heart rate response to exercise, and reduced the chest pain. Therefore we presume that the exertional chest pain was not caused by myocardial ischemia but by the tachycardia-dependent LBBB. Coronary artery-pulmonary artery fistula is the most common type of coronary artery fistulae found incidentally in adulthood. Involvement of three major coronary branches is, however, rare. The case is discussed with a review of the literature.

Bundle-Branch Block↗
PubMed1998

[Nocturnal sudden death].

Sudden death is natural death which is rapid and unexpected. Various epidemiological surveys indicate that the incidence of sudden death in Japan is about 100,000 annually, of which 60-70% are due to cardiovascular causes. One third of the victims die while sleeping in the night. Several disorders which may cause nocturnal sudden death, including "Pokkuri disease", are reviewed.

Adult↗
PubMed1996

[Arrhythmias with normal heart rate].

Arrhythmias with ventricular rate between 60-100/min are discussed. Premature ventricular complex is considered to be a risk factor for sudden cardiac death and sustained ventricular tachycardia under some particular conditions, especially after myocardial infarction. To improve the prognosis of patients with ventricular arrhythmias, many trial were performed. Ventricular arrhythmia hypothesis was based on the thought that the patients' prognosis would be improved by suppression of ventricular arrhythmias with antiarrhythmic agents. However, CAST study showed unexpected results. Recently, some investigators suggest that antiectopic action and antifibrillatory action are different and empiric therapy with amiodarone is reported. Other arrhythmias with normal heart rate are considered to have little risk for survival. Then antiarrhythmic therapy should be based on quality of life.

Amiodarone↗