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S Homma

Publications and source records attributed to S Homma.

At least 181 records · Page 10Linked to original sources
PubMed1994

Dipole tracing of monkey somatosensory evoked potentials.

Current source generators (dipoles) of somatosensory evoked potentials (SEPs) in response to electrical stimulation of the median nerve in anesthetized monkeys were localized by the dipole tracing method (DT) which can approximate surface potential distributions to an equivalent dipole. The locations and latencies of dipoles estimated by DT were confirmed by recording multiple unit activities from the parietal cortices of the same monkeys investigated by DT. Loci of generators for each SEP component were: P10 and N10, area 3b; P12, areas 1 and 2; P18, area 5. The results indicate that DT could trace the successive movement of generators of SEPs from the primary somatosensory area to area 5, which has been suggested in neuroanatomical studies to be part of the hierarchical sequence of somatosensory processes.

Animals↗
PubMed1994

Incidence of pulmonary vein complications after lung transplantation: a prospective transesophageal echocardiographic study.

OBJECTIVES: This study attempted to document the incidence of pulmonary vein complications and their potential relation to clinical outcome in patients after lung transplantation. BACKGROUND: Several case reports have documented the presence of pulmonary venous thrombosis causing graft failure in patients after lung transplantation. Because the presentation of these complications mimics that of other postoperative problems, the true incidence of pulmonary vein abnormalities remains unclear. Transesophageal echocardiography is ideally suited to examine the pulmonary veins in the postoperative setting. METHODS: Twenty-one consecutive patients undergoing lung transplantation at our institution underwent transesophageal echocardiography within 32 days of transplantation (mean [+/- SD] 6.5 +/- 7.8 days). Special attention was placed on visualizing the pulmonary veins. RESULTS: Six (29%) of the 21 patients were noted to have abnormalities of the pulmonary veins in the vicinity of the anastomotic site. After follow-up of 30 days, 4 of these patients (67%) had significant cardiovascular morbidity, and 2 died, compared with 1 (7%) of 15 patients with normal pulmonary veins (p = 0.03). The degree of obstruction of the pulmonary vein appeared to correlate with short-term outcome. CONCLUSIONS: Abnormalities of the pulmonary veins are common after lung transplantation and are easily identified by transesophageal echocardiography. Occlusive thrombi appear to be detrimental to short-term outcome.

Adult↗
PubMed1994

Left atrial appendage function and thrombus formation in atrial fibrillation-flutter: a transesophageal echocardiographic study.

OBJECTIVES: The purpose of this study was to investigate left atrial appendage size, function and thrombus prevalence in patients with atrial "fibrillation-flutter." BACKGROUND: Thrombus formation and peripheral embolization in atrial fibrillation are related to left atrial appendage dysfunction. Embolization occurs less frequently in atrial flutter. It is not known whether the atrial appendage in fibrillation-flutter, which has an intermediate appearance on the surface electrocardiogram (ECG), has distinct characteristics that could affect thrombus formation. METHODS: Sixty-one patients with atrial tachyarrhythmias underwent transesophageal echocardiographic examination of the left atrial appendage. Appendage area, peak emptying velocity and the presence of thrombus and spontaneous echo contrast were determined. The results for 14 patients with fibrillation-flutter (based on ECG fibrillatory wave characteristics) were compared with those for 30 patients with atrial fibrillation and 17 patients with atrial flutter. RESULTS: Both fibrillation-flutter and atrial fibrillation were associated with chaotic appendage flow patterns with similarly low peak emptying velocities (18 +/- 8 and 17 +/- 10 cm/s, mean +/- 1 SD, respectively). Atrial flutter was associated with a regular pattern of appendage contraction and a significantly higher peak emptying velocity (42 +/- 18 cm/s, p < 0.0001). Mean appendage area was similar for fibrillation-flutter and fibrillation (6.3 +/- 2.2 and 6.7 +/- 2.1 cm2, respectively) but was significantly smaller for atrial flutter (5.3 +/- 1.4 cm2, p < 0.05). The prevalence of left atrial appendage thrombus was similar for fibrillation-flutter and atrial fibrillation (40% and 29%, respectively), whereas no patient with atrial flutter had a thrombus (p < 0.05). Similarly, the presence of spontaneous echo contrast was higher for fibrillation-flutter (50%) and atrial fibrillation (40%) than for atrial flutter (6%, p < 0.05). CONCLUSIONS: Left atrial appendage size and function in atrial fibrillation-flutter are indistinguishable from those of typical atrial fibrillation, and the frequency of thrombus and spontaneous echo contrast is similarly high. This is in contrast to atrial flutter, which is characterized by a smaller, more contractile left atrial appendage and a lower frequency of thrombus and spontaneous echo contrast.

Aged↗
PubMed1994

Effects of high-dose intracoronary irradiation on vasomotor function and smooth muscle histopathology.

A significant component of restenosis after coronary angioplasty is due to medial proliferation. Targeted ablation of the proliferating cells by ionizing radiation may prevent restenosis. We delivered high-dose intracoronary gamma-irradiation in porcine coronary arteries and assessed vasomotor function acutely and at 32 days, with pathological analysis at 32 days. Changes in luminal area were assessed by intravascular ultrasound. Irradiated segments acutely displayed vasoconstriction to acetylcholine, with loss of smooth muscle response to nitroglycerin. Restudy revealed restoration of normal vasodilatory response to acetylcholine but persistent loss of response to nitroglycerin. Histopathology at 32 days revealed minor neointima formation without luminal compromise and diffuse fibrosis of the smooth muscle layer. The surrounding myocardium was normal. Focal medial fibrosis without significant endothelial or myocardial damage can be achieved via this technique; intracoronary irradiation, therefore, may be an effective way of impairing the restenosis process.

Animals↗
PubMed1994

Characteristics of patent foramen ovale associated with cryptogenic stroke. A biplane transesophageal echocardiographic study.

BACKGROUND AND PURPOSE: Patent foramen ovale is associated with ischemic stroke in patients without a clearly identifiable etiology for stroke (cryptogenic stroke). Paradoxical embolization is thought to be a potential mechanism. However, patent foramen ovale is also found in patients with known cause of stroke. Therefore, using contrast transesophageal echocardiography, we characterized the patent foramen ovale in cryptogenic stroke patients to assess morphological factors that may contribute to paradoxical embolization. METHODS: Contrast transesophageal echocardiographic studies of 74 consecutive patients referred for ischemic stroke were reviewed. Twenty-three patients with patent foramen ovale were identified. These patients were classified as having strokes of determined origin or cryptogenic strokes according to criteria developed for the Stroke Data Bank of the National Institute of Neurological Disorders and Stroke. Separation of septum primum from secundum and the number of microbubbles appearing in left atrium were then quantitated. These parameters were compared between patients with cryptogenic stroke and those with known cause of stroke. RESULTS: The patent foramen ovale dimension was significantly larger in patients with cryptogenic stroke compared with patients with an identifiable cause of stroke (2.1 +/- 1.7 mm versus 0.57 +/- 0.78 mm [mean +/- SD]; P < .01). The number of microbubbles was also greater in patients with cryptogenic stroke compared with patients with an identifiable cause of stroke (13.9 +/- 10.7 versus 1.6 +/- 0.8 [mean +/- SD]; P < .0005). CONCLUSIONS: Patients with cryptogenic stroke have larger patent foramen ovale with more extensive right-to-left interatrial shunting than patients with stroke of determined cause. Transesophageal echocardiographically identifiable characteristics of patent foramen ovale may be important in defining the clinical significance of individual patent foramina.

Adult↗
PubMed1994

Cardiac injury associated with neurogenic pulmonary edema following subarachnoid hemorrhage.

OBJECTIVE: To describe the clinical features of cardiac injury associated with neurogenic pulmonary edema (NPE) in patients with acute subarachnoid hemorrhage (SAH). BACKGROUND: NPE is generally viewed as a form of noncardiogenic pulmonary edema related to massive sympathetic discharge. METHODS: Case series. RESULTS: We found echocardiographic evidence of reduced global and segmental left ventricular (LV) systolic function in five women (mean age, 44; range, 36 to 57) with SAH and NPE. None had a history of heart disease. Four patients were Hunt/Hess grade III and one was grade IV. All five patients experienced (1) sudden hypotension (systolic blood pressure < 110 mm Hg) following initially elevated blood pressures, (2) transient lactic acidosis, (3) borderline (2 to 4%) creatine kinase MB elevations, and (4) varied acute (< 24 hours) electrocardiographic changes followed by widespread and persistent T wave inversions. Pulmonary artery wedge pressures were normal in 3/3 patients at the onset of pulmonary edema but reached high levels (> 16 mm Hg) in all four patients studied beyond this period. Reduced cardiac output and LV stroke volume were identified in three patients; the fourth patient demonstrated normal values on high doses of intravenous pressors. Cerebral infarction due to vasospasm occurred in four patients and resulted in two deaths. Follow-up echocardiography performed 2 to 6 weeks after SAH revealed normal LV function in all three survivors. CONCLUSIONS: A reversible form of cardiac injury may occur in patients with NPE following SAH and is associated with characteristic clinical findings. Impaired LV hemodynamic performance in this setting may contribute to cardiovascular instability, pulmonary edema formation, and complications from cerebral ischemia.

Adult↗
PubMed1994

Visualization of renal microcirculation in isolated Munich-Wistar rat kidneys: effects of endothelin-1 on renal hemodynamic activity.

The aim of the present study was to visualize the superficial glomeruli of the Munich-Wistar (MW) rat and to characterize the responses of the renal microvasculature to endothelin-1 (ET-1). We first examined the distribution of superficial glomeruli of the MW rat compared to that in a control strain (Wistar rat). Secondly, we examined the effects of ET-1 on the renal microcirculation of the MW rat. The right kidney was perfused with a Krebs-Ringer solution containing fluorescein isothiocyanate dextran (FITC-dextran) and was visualized under an epi-illuminated fluorescence microscope system. Changes in perfusion pressure and diameter of the microvessels accompanying the administration of ET-1 (10 fmole-300 pmole) were measured. The number of superficial glomeruli was greater in the MW rat than in the Wistar rat. ET-1 had long-lasting and dose-dependent pressor effects. Perfusion pressure showed a 3.5-fold increase compared with the control, and the afferent arterioles showed greater dose-dependent vasoconstriction than the efferent arterioles. These findings suggest that the MW rat is a useful animal model for the study of renal microcirculation and that the renal microcirculation is extremely sensitive to ET-1.

Analysis of Variance↗
PubMed1994

Clinico-radiological findings of neuro-Behçet's syndrome.

We examined 21 cases of Neuro-Behçet's syndrome in detail, and present here their clinicoradiological characteristics. Clinically, signs of pyramidal tract and meningeal irritation were frequently observed. In contrast to previous reports, our study demonstrated a near equal frequency in the occurrence of focal cerebral lesions and that of focal brain stem lesions. Notably, our results showed that the atrophy of both the cerebrum and the brain stem was often observed, indicating the presence of continuous disease activity in the central nervous system (CNS). In accordance with the high frequency of meningeal irritation signs, all of our cases exhibited pleocytosis in the cerebrospinal fluid (CSF). These results indicated the possibility that chemical mediators secreted from infiltrating cells in the CSF may somehow inflict damage to the CNS in Neuro-Behçet's syndrome.

Adult↗
PubMed1994

Development of the motor activity of the rat gastrointestinal tract by in vitro measurement.

To clarify the postnatal developmental changes of the motor activity of the gastrointestinal tract, the frequency and amplitude of spontaneous intraluminal pressure of the isolated stomach, duodenum, jejunum, and ileum of the 1- to 5-week-old rat and adult (over 12 weeks old) were examined in vitro. The spectral frequencies of the spontaneous motor activity of 1- to 2-week-old rat were significantly lower than those of the adult. They became similar to the values of the adult at 3-4 weeks after birth. The amplitudes of spontaneous motor activity of 1- to 3-week-old rats were significantly smaller than those of adults. They became similar to the values of adults at 4 weeks after birth. Body weight, stomach wet weight and the length of the total intestine increased gradually and they were still below the values of the adult even at 5 weeks after birth. The stomach was filled with just milk until the end of 2 weeks. However, by the end of 3-4 weeks, milk and solid food were found in the stomach. By the end of 5 weeks, just solid food was seen in the stomach. Therefore, the motor activity of the gastrointestinal tract at birth seems immature and gradually develops postnatally. It seems to be mature by the end of 3-4 weeks after birth. Interestingly, the time of the pacemaker or motor maturity of the gastrointestinal tract according to spontaneous frequency or pacemaker activity and amplitude seemed almost consistent with the weaning time.

Age Factors↗
PubMed1994

[Direct mail investigation of the social and physical background of centenarians in Tokyo metropolitan area].

This study was designed for the purpose of investigating the factors for longevity in the Tokyo metropolitan area. At first, we examined the social and physical background of centenarians by direct mail in 1992. A total of 398 questionnaires (from 81 males and 308 females) were returned. There was a significant gender difference in mobility, with 38% of males and 10% of females being able to take a walk. However 19% of male centenarians and 28% of female ones were bedridden. Hypertension, respiratory disease and heart disease were found in 22%, 16%, 16%, without any significant gender differences. On the contrary, there were more female centenarians with past histories of bone fracture (34%) than male (10%). This discrepancy suggest that bone fracture may be one of the factors causing the gender differences in mobility. Those who had a high level of education were more frequent in centenarians (27% of males and 8% of females) than in the general population of their contemporaries in Japan (less than 2%). The average age at death of the centenarians' parents was 69.6 +/- 15.7 y/o for their father and 71.2 +/- 17.2 y/o for their mother. These ages were significantly higher than the average life-span in the last decade of the 19th century, according to the First Life Tables in Japan. The possibility is suggested that longevity was inherited in these centenarians' families.

Aged↗
PubMed1994

[Marfan syndrome].

Explore the source record for details and available documents.

Diagnosis, Differential↗
PubMed1993

Blood pressure and heart rate relationships during cervical sympathetic and vagus nerve stimulation in streptozotocin diabetic rats.

Linear regressions were calculated between blood pressure and heart rate changes during the stimulation of peripheral cut end of cervical sympathetic and vagus nerve in the streptozotocin diabetic rats (65 mg/kg) and age-matched controls. Slopes of blood pressure (mmHg, abscissa)-heart rate (beat/minute, ordinate) relationships of diabetic rats (9.87 +/- 1.46, mean +/- S.E.M., n = 8) were significantly steeper (P < 0.05) than those of age-matched controls (5.12 +/- 0.63, n = 7). In the control rats, blood pressure and heart rate were rather equally changed during autonomic nerve stimulation. In contrast, in the diabetic rats, heart rate was markedly changed but blood pressure was little changed during the electrical stimulation of the cervical autonomic nerves. Chronotropic effect was exaggerated but inotropic one was disturbed in the heart of streptozotocin diabetic rat when cervical sympathetic nerve was stimulated.

Animals↗