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Biomedical subjects

H Shigeta

Publications and source records attributed to H Shigeta.

At least 19 recordsLinked to original sources
PubMed1992

Dorsal internal carotid artery aneurysms with special reference to angiographic presentation and surgical management.

Aneurysms arising from the dorsal wall of the internal carotid artery are rare. The authors surgically treated twenty dorsal internal carotid artery aneurysms. Pre-operative angiographic findings were reviewed and classified into three types. Eleven aneurysms projecting superiorly on the lateral angiogram were found to be adherent to the base of the frontal lobe by the pterional approach. Five aneurysms which had been superimposed with the internal carotid artery on the lateral angiogram were found adhered to the medial surface of the temporal lobe. Four aneurysms not seen on the angiogram had no adhesion. Two aneurysms, which had not been seen on the initial angiograms, were visualized on the angiograms taken during the period of vasospasm. This type of aneurysms can be the source of a subarachnoid haemorrhage of unknown origin and requires repeated examinations. Premature rupture occurred intra-operatively in five cases and postoperative bleeding was encountered in two. Clipping technique is discussed from the viewpoint of preventing intra- and postoperative rupture.

Adult↗
PubMed1991

Development of a high-resolution digital tomosynthesis system and its clinical application.

Conventional tomography has been criticized for its low contrast caused by scattered radiation and tomographic blur. The authors developed a digital tomosynthesis system as a substitute for conventional tomography. With the image processor in the system, two types of postprocessing can be performed to improve the quality of synthesized tomograms. One-dimensional spatial frequency filtering effectively reduces linear tomographic blur and enhances image information when an appropriate filter is used. Correction of structure mottle helps enhance the image clarity. The system allows reconstruction of tomograms at any desired depth and performance of tomosynthetic angiography and dual-energy subtraction. The system solves some of the problems associated with plain tomography and dual-energy subtraction and provides diagnostic clinical images.

Humans↗
PubMed1991

Effect of media conditioned by concanavalin A activated spleen cells on pancreatic islet cells.

The effect of media conditioned by concanavalin A-activated spleen cells (C-sup) on insulin release and its islet cell cytotoxicity were studied. In a functional study, C-sup significantly inhibited both basal insulin release and glucose-stimulated insulin release. Morphologically, C-sup had a destructive effect on isolated islets after 72 h incubation. Islet cell cytotoxicity was shown by lactate dehydrogenase (LDH) release assay after 5 days incubation with C-sup in a dose-dependent manner. These results suggest that acceleration of the onset of diabetes in young diabetes prone (DP) Bio-Breeding/Worcester (BB/W) rats following the injection of C-sup may depend on the suppressive and cytotoxic effects of C-sup on pancreatic islet cells.

Animals↗
PubMed1990

Dietary treatment ameliorates overt diabetes and decreased insulin secretion to glucose, induced by overeating in impaired glucose tolerant mice.

Overt diabetes (NIDDM) was induced by overeating in neonatally streptozocin (60 mg/kg.BW) treated impaired glucose tolerant mice. We imposed a food restriction and a high fiber diet to evaluate the effects of dietary treatment in this NIDDM model mouse. Furthermore, insulin secretion after the dietary treatment was studied using the perfused pancreas technique. One group of IGT mice (SZ) was maintained on ordinary mouse chow during 6 to 14 weeks of age. The others received a cookie and chocolate mashed diet (C.C. diet) to induce overt diabetes during 6 to 10 weeks of age. Thereafter, the mice with induced overt diabetes were divided according to their diet treatment. The C.C. diet was continued in one group (SZC) for 4 weeks, and the others were divided into a food restriction group (SZR: 4 g/mouse/day of ordinary mouse chow, for 4 weeks) and a high fiber diet group (SZF: 20% W/W of cellulose in ordinary mouse chow, for 8 weeks). The mean caloric intake/mouse/day in SZC, SZR and SZF were 140, 80 and 98% of that in SZ, respectively. Amelioration of hyperglycemia and impaired glucose tolerance was noted in SZR and SZF. A better glycemic control was obtained in SZF with keeping a normal growth rate. On the pancreas perfusion, the insulin secretion to 30 mM glucose was improved in SZR and SZF. Furthermore, the incremental first phase peak insulin release to 30 mM glucose in SZF was significantly greater than that in SZC (SZF, 10.5 +/- 1.0 vs. SZC, 4.5 +/- 1.9 microU/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Overt diabetes induced by overeating in neonatally STZ-treated impaired glucose tolerant mice: long-term follow up study.

This study has investigated the effect of a long period of overeating on the glycemic control and pancreatic beta-cell function in neonatally streptozocin treated impaired glucose tolerant mice. Neonatally streptozocin (60 mg/kg) treated male ICR mice with 150-200 mg/dl of fed blood glucose levels were divided into two groups at 6 weeks of age. One group was maintained on a cafeteria diet (SZC) and the other on ordinary mouse chow (SZ) until 30 weeks of age. Normal male ICR mice were divided into a cafeteria diet group (CC) and an ordinary chow group (Cont). SZC and CC consumed 134-124% of the caloric intake in SZ and Cont throughout the study. Marked elevation of the fed blood glucose level was observed and the glucose tolerance was progressively impaired in SZC. On pancreas perfusion at 30 weeks of age, insulin secretion to 30 mM glucose in SZC was significantly decreased compared with that in SZ. That in CC was slightly decreased compared with that in Cont. The pancreatic insulin concentration in SZC was significantly less than that in SZ. We conclude that chronic hyperglycemia, induced by the long period of overeating, accelerated the selective loss of beta-cell sensitivity to glucose. Even in normal mice that did not have marked hyperglycemia, insulin secretion to glucose was suppressed, probably by chronic stimulation of the beta-cell due to the long period of dietary excess.

Animals↗
PubMed1988

Trochlear nerve meningioma in von Recklinghausen's disease.

A trochlear nerve meningioma in a patient with von Recklinghausen's disease is reported. The tumour appeared to have originated from the trochlear nerve itself, having no connection either with the neurinomas present in the adjacent regions, or with the tentorium. Histological examinations revealed that the tumour was a meningotheliomatous meningioma and the trochlear nerve fibres were placed in the periphery of the tumours. It was noteworthy that diplopia was not detected either before or after the resection of the trochlear nerve with the tumour.

Adult↗
PubMed1988

[Two-dimensional and Doppler echocardiographic findings of a sudden death case due to multiple pulmonary thromboses].

This is a case report presenting interesting findings on two-dimensional and Doppler echocardiograms due to multiple pulmonary thromboses. A 67-year-old woman had a history of surgery for colon polyps in August, 1986. After surgery, she suffered from tachycardia and dyspnea, and was admitted to our hospital because of a loss of consciousness. Sinus tachycardia, complete right bundle branch block and T-wave inversion in leads III, aVF and V1-4 were observed on her electrocardiogram. Cardiomegaly was noted on her chest radiograph. On the third hospital day, echocardiography was performed. On two-dimensional echocardiography, marked right ventricular dilatation with hypokinesis of the wall, and a flattened interventricular septum were observed on the short-axis view, and M-mode echocardiograms showed disappearance of the E wave and delay of the opening of the tricuspid valve, resulting in a monophasic triangular pattern. Doppler echocardiography showed the tricuspid valve flow to be delayed, mainly observed during atrial systole. These findings indicate decreased right ventricular compliance. The patient died on the 6th hospital day, and multiple new and old thrombi were found in the pulmonary artery at autopsy.

Aged↗
PubMed1988

[Traumatic subarachnoid hemorrhage--clinical study of 16 cases].

Three hundred and eighty three cases with head injury were admitted to our hospital during period from March 1985 to October 1986. Among these cases, 16 (4.2%) had subarachnoid hemorrhage as revealed on computerized tomography (CT) scan; other CT findings included epidural hematoma, subdural hematoma and/or cerebral contusion. Traumatic subarachnoid hemorrhage was most frequently found in the ambient and/or sylvian fissure. This suggests that head blow tended to product shear strain at the brainstem and in the direction from temporal tip to frontal base. Furthermore tentorial edge and sphenoid ridge may have played an important role in producing subarachnoid hemorrhage. Of the 6 cases with the hemorrhage localized in the unilateral cisterns, 5 cases had the hemorrhage in the cisterns opposite to the blow site. This suggests that shear strain was produced more strongly at the opposite side to the blow site. The cases with subarachnoid hemorrhage in the prepontine and/or interpeduncular cistern had severe brainstem damage and their prognosis was very poor, while those with the hemorrhage localized in the ambient cistern, quadrigeminal cistern and/or sylvian fissure without other findings had good prognosis.

Adolescent↗
PubMed1987

Somatostatin suppresses plasma aldosterone concentration in a case of Bartter's syndrome.

The study was conducted to examine the effect of somatostatin on activated renin-angiotensin-aldosterone system in a case of Bartter's syndrome. After 60 minutes of 500 micrograms of somatostatin infusion, the plasma aldosterone concentration was reduced from the basal level of 250 pg/ml to 140 pg/ml, whereas plasma renin activity remained at the basal level. This result suggests that somatostatin may specifically inhibit aldosterone secretion in Bartter's syndrome and the agent can be applied to a treatment of this syndrome.

Adrenocorticotropic Hormone↗
PubMed1986

[Right and left coronary arteries-right atrial fistulas diagnosed by Doppler echocardiography: a case report].

An interesting case of right and left coronary arteries-right atrial fistulas diagnosed by Doppler echocardiography was presented. A 59-year-old woman was referred for evaluation of her continuous murmur. A thrill was palpable at the left sternal border in the third intercostal space. The proximal portions of the dilated right and left coronary arteries and distal portions of the tortuous and converging fistulas of both coronary arteries were imaged by two-dimensional echocardiography. Bidirectional continuous turbulent Doppler signals were detected in the proximal portions of the dilated right and left coronary arteries, in the distal portions of the fistulas around the crux and in the right atrium. These findings facilitated our diagnosis of right and left coronary arteries-right atrial fistulas. The flow velocity at the ostium of the right coronary artery was highest and nearly the same as the flow velocity (about 2 m/s) obtained by continuous wave Doppler from the maximum point of the thrill. The maximum pressure difference was considered located at this portion. Selective coronary angiography confirmed the right coronary artery and left main trunk-left circumflex coronary artery to be large, elongated and tortuous. These fistulas were communicating with the right atrium. This case demonstrates the usefulness of Doppler echocardiography in the noninvasive diagnosis of coronary arteriovenous fistula.

Arteriovenous Malformations↗
PubMed1985

Effects of aspartame on diabetic rats and diabetic patients.

The effects of aspartame (L-aspartyl-L-phenylalanine methyl ester) on plasma glucose and insulin levels were investigated in diabetic rats and patients with non-insulin-dependent diabetes mellitus. The oral administration of 0.45 mg aspartame per 100g body weight, which is equivalent to 150 mg of glucose in sweetness, to streptozotocin-induced diabetic rats had no effect on the plasma glucose or insulin levels. Also, 225 mg oral aspartame loading, which is equivalent to 75 g of glucose in sweetness, to patients with non-insulin-dependent diabetes mellitus did not increase plasma glucose or insulin levels, although 75 g of oral glucose loading increased plasma glucose and insulin levels in diabetic patients as expected. Aspartame ingestion for three days at a dose of 24-48 mg per day and the intake of snacks flavored with 240 mg of aspartame also did not increase fasting plasma glucose levels. These results suggest that acute administration of aspartame has no influence on plasma glucose or insulin levels in diabetic rats and patients with non-insulin-dependent diabetes mellitus.

Adult↗