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Biomedical subjects

H Takezawa

Publications and source records attributed to H Takezawa.

At least 19 recordsLinked to original sources
PubMed1995

Effects of suprachiasmatic lesions on circadian rhythms of blood pressure, heart rate and locomotor activity in the rat.

To determine whether the circadian rhythms in blood pressure (BP), heart rate (HR) and locomotor activity are controlled by an internal biological clock located in the suprachiasmatic nucleus (SCN), we continuously measured these parameters in SCN-lesioned rats using a newly developed implantable radiotelemetry device and a computerized data collecting system. Although SCN-lesioned rats showed a weak but significant 24-h periodicity in BP and HR under light-dark (LD) cycles, BP, HR and locomotor activity became completely aperiodic under constant dark (DD) conditions. The amount of locomotor activity was significantly reduced in SCN-lesioned rats compared to that in intact rats. BP tended to be higher in SCN-lesioned rats, but the differences were significant only in the comparison of systolic blood pressure (SBP) under LD and DD (p < 0.05) and of mean blood pressure (MBP) under LD (p < 0.05). HR in SCN-lesioned rats was significantly lower under LD (p < 0.05), but not under DD. The standard deviation and the variation coefficient of MBP, as indices of short-term variability of this parameter, were significantly larger in SCN-lesioned rats than in intact rats, while those of HR and locomotor activity did not differ significantly between SCN-lesioned and intact rats. These results indicate that the SCN is important not only for generating circadian rhythms of BP, HR and locomotor activity, but also for buffering the short-term variability of BP in rats.

Animals↗
PubMed1992

Immunologic characteristics of cytokines in otitis media with effusion.

Levels of cytokines, interleukin (IL)-1 alpha, IL-1 beta, tumor necrosis factor (TNF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were investigated in samples of the middle ear effusions (MEEs) from 144 ears with otitis media with effusion (OME) by enzyme-linked immunosorbent assay, followed by cytologic analysis. Middle ear effusions of the acute purulent type contained a significantly higher concentration of cytokines compared with normal control sera (p < .001). Cytokines were observed at lower levels in MEE in adults than in children. Tests of children at the chronic stage of MEE showed higher levels of TNF than IL-1 and GM-CSF. Meanwhile, IL-1 beta showed significantly higher concentrations in acute purulent types than in serous and mucoid types (p < .01). In cytologic analysis, the mean level of IL-1 beta was significantly higher in the neutrophil-rich group than in other groups (p < .05). Cytokines possess several biologic properties, some of which are associated not only with acute otitis media but also with chronic otitis media. This study showed that cytokines, especially IL-1 beta, contribute to infiltration into the middle ear by inflammatory cells. This implies that the persistent presence of cytokines in MEE could be a factor in prolonged OME.

Acute Disease↗
PubMed1990

Effects of nifedipine on left ventricular diastolic function in patients with asymptomatic or minimally symptomatic hypertrophic cardiomyopathy.

We investigated the effects of nifedipine on left ventricular diastolic function in 17 asymptomatic or minimally symptomatic patients with hypertrophic cardiomyopathy by simultaneously measuring left ventricular pressure and volume with a catheter-tipped manometer and biplane cineangiography. Studies were performed before and 20 minutes after sublingual administration of nifedipine (20 mg). Heart rates were held constant (79 +/- 12 beats/min, mean +/- SD) by right atrial pacing. Left ventricular volumes and instantaneous rates of left ventricular volume were derived from frame-by-frame (20-msec) analyses of left ventricular biplane angiograms. Left ventricular peak systolic pressure (from 122 +/- 21 to 108 +/- 13 mm Hg, p less than 0.01 vs. control) and mean aortic pressure (from 96 +/- 15 to 87 +/- 11 mm Hg, p less than 0.01) decreased significantly with nifedipine. With afterload reduction, left ventricular ejection fraction (from 0.69 +/- 0.12 to 0.74 +/- 0.08, p less than 0.01) and cardiac output (from 6.4 +/- 2.0 to 7.2 +/- 2.2 l/mm, p less than 0.05) increased significantly. However, there was a slight but significant increase in left ventricular end-diastolic pressure (from 15 +/- 8 to 18 +/- 8 mm Hg, p less than 0.05). Nifedipine did not improve left ventricular relaxation as assessed by the time constants of isovolumic pressure decay (t1/2, from 39.8 +/- 6.6 to 39.4 +/- 7.7 msec, NS; t1/e, from 53.8 +/- 9.0 to 54.4 +/- 10.7 msec, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1989

Carcinoid tumour of the middle ear.

Carcinoid tumours belong to the rarer neoplasms of the middle ear. In 1980, Murphy et al. described the first case of a carcinoid tumour of the middle ear. Only five cases could be traced in the literature. The light and electron microscope features of a primary atypical carcinoid tumour of the middle ear are presented and compared with those described in the literature. Primary carcinoid of the middle ear appears to be derived from the epithelial lining of the middle ear. Distant metastases have not been reported. The duration and nature of the symptoms are of little diagnostic value. An atypical carcinoid tumour in the left ear of a 33-year-old woman is described.

Adult↗
PubMed1989

[Coronary angiography in patients with U wave inversion during coronary artery spasm].

During ergonovine-induced vasospastic angina, U wave inversion without significant ST segment deviation on the precordial electrocardiograms was documented in four patients. Coronary angiography revealed incomplete spastic obstruction of the left anterior descending artery without delayed filling and runoff in three patients. In the remaining patient, the proximal left anterior descending artery was totally occluded and there were well-developed collaterals from the non-spastic artery. Thus, ergonovine-induced U wave inversion was related to the presence of coronary vasospasm, and angiography demonstrated less severe myocardial ischemia in such patients than in cases with ST segment elevation or depression, which is usually associated with subtotal or total obstruction of a major coronary artery without adequate collaterals. In their clinical courses, two patients had episodes of angina with ST segment elevations or depressions. It was suggested that vasospastic angina with U wave inversion alone is one aspect of a continuous spectrum of vasospastic myocardial ischemia.

Adult↗
PubMed1988

Elevation of bone conduction threshold in children with middle ear effusion.

A retrospective study of children having otitis media with effusion revealed fluctuations in bone conduction thresholds as well as in air conduction thresholds. Previous investigations in this area presented both low- and high-tone bone conduction hearing loss which were reversible. We conducted a detailed study including complete otologic, audiologic and tympanometric evaluation of 27 (41 ears) children who had fluctuating bone conduction hearing loss. From these audiologic examinations, 3 types of bone conduction hearing loss could be classified: high-tone, low-tone and flat-type bone conduction hearing loss. We observed the shift of bone conduction thresholds in children after removal of middle-ear fluids by the appropriate medical management.

Audiometry↗
PubMed1988

[Graft patency and myocardial viability after aorto-coronary bypass surgery evaluated by exercise 201T1 myocardial SPECT].

To evaluate graft patency and myocardial viability after aorto-coronary (AC) bypass surgery, 58 patients (29 with old myocardial infarction and 29 with effort angina) underwent symptom-limited exercise 201T1 myocardial SPECT using a bicycle ergometer before and after surgery. The results were as follows: 1. The overall angiographic graft patency was 87% (97 of 112 grafts). 2. According to the stress SPECT images, graft patencies were 98% for areas with postoperative improvement by 201T1 uptakes, 79% for areas with unchanged patterns, and 53% for areas with worsened patterns. In spite of patent grafts, among cases with worsened 201T1 uptakes the etiologies included perioperative infarction, anastomotic strictures, and poor run-off distal to the anastomoses. 3. Following patency of grafts, postoperative normalized perfusion patterns were observed in 69% (27 of 39 segments) of segments with persistent preoperative low uptakes and 25% (4 of 16 segments) of segments with persistent preoperative defects. Thus, exercise 201T1 myocardial SPECT proved a useful diagnostic means of assessing graft patency and effectiveness. However, after AC bypass surgery, 25% of the regions which had persistent defects before surgery exhibited normal perfusion patterns. These findings suggest that persistent defects may represent hypoperfusion of viable myocardium, and that we should carefully diagnose myocardial scars.

Adult↗
PubMed1987

Swallow syncope after aneurysmectomy of the thoracic aorta.

A case of swallow syncope is presented and 30 previously reported cases from the literature in English are reviewed. A 67-year-old male developed syncope on swallowing 3 months after the resection of an aneurysm of the descending thoracic aorta. Electrocardiographic monitoring during eating demonstrated sinus bradycardia and sinus arrest with loss of consciousness. Neither Valsalva's maneuver nor carotid massage could produce bradycardia or syncope. Intravenous administration of edrophonium produced sinus bradycardia and the drinking of water by the patient after edrophonium administration brought about sinus bradycardia and sinus arrest with loss of consciousness. Sinoatrial node and atrioventricular node functions, evaluated by an atropine test, overdrive suppression test, and His bundle electrocardiogram were normal. No pathological changes were observed following a barium swallow. The patient was treated with a permanent pacemaker.

Aged↗
PubMed1987

Myocardial ultrastructure in Kearns-Sayre syndrome.

Myocardial ultrastructural changes are described in a twenty-five-year-old female with typical Kearns-Sayre syndrome. The electrocardiogram revealed complete atrioventricular block with an occasional torsades de pointes type of ventricular tachycardia. His bundle recording demonstrated HV block with normal AH interval. An endomyocardial biopsy showed "ragged-red fibers" by the modified Gomori trichrome stain, and on electron microscopy there were increased numbers of morphologically abnormal mitochondria: ie, gian mitochondria, a whorled pattern of the cristae, and electron-dense substances, and paracrystalline inclusions in the mitochondria. The patient has been well since pacemaker implantation, but she may develop a clinically overt cardiomyopathy due to progression of myocardial involvement.

Adult↗
PubMed1987

Vasospastic angina in thyrotoxicosis--case reports.

We encountered 2 patients with thyrotoxicosis accompanied at its onset by progressive angina. The ST segment was elevated in one patient and depressed in the other patient during the spontaneous attacks. Coronary arteriographic findings were normal during control, and spasm was induced by ergonovine. No patients had chest pain even without antianginal medication after successful treatment of thyrotoxicosis. The coronary artery may become sensitive to spasm during thyroid hormone excess even in cases without significant coronary artery disease and previous chest pain.

Adult↗
PubMed1987

Incidence and clinical course of right ventricular infarction: assessment with radionuclide ventriculography.

The incidence and prognosis of right ventricular infarction were studied by radionuclide ventriculography (RNV) in 50 consecutive cases of acute myocardial infarction. RNV was performed within thirty-six hours of symptoms and one month after onset. Right ventricular infarction was absent in all 25 patients with anterior infarction. It was found in 15 of the 25 patients with inferior infarction, accompanied by a marked reduction in right ventricular ejection fraction (28 +/- 8%), but was notably alleviated one month later with normalization of right ventricular ejection fraction (39 +/- 7%) and wall motion. These phenomena seem to be specific in right ventricular infarction.

Adult↗
PubMed1987

Estimation of ventricular source parameters and its load matching state in vivo.

Ventriculo-arterial coupling states were estimated by calculating left ventricular hydromotive pressure (Ps), source impedance (Zs) and input impedance (Zl) in 24 mongrel dogs with Fourier transforms of ventricular pressure and aortic flow immediately before and after instantaneous changes of arterial load. Calculated Ps (Psc) were compared with measured left ventricular isovolumic pressures (Psm) in various inotropic and loading states. Psc waveforms coinciding closely with those of Psm were obtained by cutting off higher frequencies within the fifth to tenth harmonics prior to the inverse Fourier transformation. The regression equation was Psc = 1.08 Psm +0.68 (r = 0.978). In control conditions, the ratio of Zs (0) / Zl (0) (function of frequency, 0 = zero Hz) was close to the ratio of ejection phase to one whole cardiac cycle, and the ratio of peak Psm to left ventricular ejection pressure was 1.85 +/- 0.25 SD. These results imply the presence of a ventriculo-arterial load matching state in control conditions.

Animals↗
PubMed1987

Cardiac tamponade in rheumatoid arthritis. Successful treatment with intrapericardial steroid administration.

Cardiac tamponade complicated by classic rheumatoid arthritis was markedly alleviated by pericardiocentesis and intrapericardial administration of steroid. For the following 2 years, no recurrence of cardiac tamponade or constrictive pericarditis was observed. According to the literature, only one other patient with cardiac tamponade complicating rheumatoid arthritis (RA) had been successfully treated patient by intrapericardial steroid administration.

Adult↗
PubMed1987

Myocardial infarction in Graves' disease without coronary artery disease.

A 45-year-old female without coronary risk factors showed a 20 kg decrease in body weight, hyperhydrosis, palpitations and dyspnea on exertion for 2 months, and nocturnal dyspnea for 1 month before admission. She did not notice chest pain indicative myocardial infarction or fever suggestive myocarditis. Graves' disease was confirmed by exophthalmos and elevated titers of T3 and T4 thyroid hormones. Cardiac catheterization studies demonstrated no significant coronary artery disease but showed akinesis of the anteroseptal and apical walls which suggested myocardial infarction. Thyroid hormone may directly influence myocardial oxygen supply and demand and, by some unknown mechanism, cause a critical imbalance in coronary circulation resulting in myocardial infarction.

Coronary Disease↗