PubMed Health⌕ Search

Biomedical subjects

A Ogawa

Publications and source records attributed to A Ogawa.

At least 19 recordsLinked to original sources
PubMed1992

Cerebral blood flow and oxygen metabolism in infants with hydrocephalus.

In this study, regional cerebral blood flow (rCBF) and the cerebral metabolic rate of oxygen (rCMRO2) were measured using positron emission tomography (PET) with oxygen-15 radiopharmaceuticals to clarify the pathophysiology of ventriculomegaly in the developing brain. Four hydrocephalic infants without severe neurological deficit were studied. Hypoperfusion was observed in the frontal, parietal, and visual association cortices which surrounded dilated anterior or posterior horns of the lateral ventricle. Lower rCMRO2 values than adult rates were observed in all cases. In the infants with markedly enlarged anterior or posterior horns, the surrounding cortices showed relatively lower rCMRO2 values with the fall of rCBF. Postoperative studies were performed in two infants. rCMRO2 increased in every region after ventriculoperitoneal shunting, but little change was observed in rCBF. These results indicate that metabolic deterioration occurs in the developing brain with hydrocephalus.

Blood Volume↗
PubMed1992

Congenital cerebral venous dysgenesis. Decreased cerebral blood flow in deep cerebral regions revealed by SPECT.

This report describes a rare case of primary cerebral venous dysgenesis in a 3-year-old child with development retardation. Angiography resulted in nonvisualization not only of deep cerebral veins but also of superficial cerebral veins. In computed tomography and in magnetic resonance imaging the collateral venous circulation appeared as a strange configuration in the pineal region. Single photon emission computed tomography using N-isopropyl-p-[I-123]-iodoamphetamine revealed decreased regional cerebral blood flow in the basal ganglia and thalamus, but cerebral infarction was not detected in the area. These features indicate that in this case, dysgenesis of deep cerebral veins, which probably occurred during prenatal life, had caused hypoperfusion in the deep cerebral regions.

Carotid Arteries↗
PubMed1992

Repositioning of the tortuous vertebrobasilar artery for trigeminal neuralgia: a technical note.

A patient with trigeminal neuralgia caused by a tortuous vertebrobasilar artery is reported. To obtain safe and certain neurovascular decompression of the trigeminal nerve, the tortuous vertebrobasilar artery was repositioned by pulling it toward the dura mater of the clivus using a synthetic vascular slip. The authors describe the technique of repositioning of the tortuous vertebrobasilar artery and its usefulness.

Basilar Artery↗
PubMed1992

Gastrocystoplasty in dogs: an ulcerating effect of acid urine.

Six dogs underwent bladder augmentation using an isolated flap of the body of the stomach after a supratrigonal cystectomy. Each dog was followed for six months with periodic determinations of urine pH, blood chemistry, cystometry and cystography. Postoperatively, urine pH decreased markedly after a meal in most dogs. No persistent hypergastrinemia was found. Autopsy showed that histological erosions developed in the bladder remnant in five dogs, and an ulcer in the bladder remnant in one dog. These results indicate that when an isolated, vagally denervated gastric segment is incorporated into the bladder, acid secretion from the segment may ulcerate the bladder.

Anastomosis, Surgical↗
PubMed1992

Peripartum changes in antibody producing capability of lymphocytes from dairy cows.

B-lymphocyte populations and the in vitro antibody producing activity of lymphocytes were measured to evaluate the lymphocyte function of periparturient dairy cows. Changes in B-lymphocyte populations were not significantly different in cows during this period. Significantly decreased numbers of plaque-forming cells were observed in lymphocytes from cows at parturition and 3 days after parturition compared to those in lymphocytes obtained 14 days after parturition.

Animals↗
PubMed1992

Effects of sulpiride and oxypertine on the dopaminergic system in the rat striatum.

We have examined the effects of sulpiride, oxypertine and haloperidol on the behavioral and biochemical dopamine receptor function in the rat striatum. Although acute treatment with haloperidol or oxypertine induced catalepsy, tolerance to catalepsy developed following chronic treatment with haloperidol but not with oxypertine. Rats treated with acute or chronic sulpiride did not show signs of catalepsy. Intracerebroventricular administration of sulpiride, however, induced catalepsy and tolerance developed after chronic treatment. After chronic treatment with either of these three drugs, dopamine D2 receptors were up-regulated in the striatum. While acute administration of haloperidol, sulpiride or oxypertine increased the concentration of homovanillic acid in the striatum, the rate of increases was attenuated following chronic treatment with haloperidol or sulpiride, but not with oxypertine. While acute administration of sulpiride or oxypertine decreased dopamine, the decrease was attenuated following repeated administration of sulpiride but not of oxypertine. These results suggest that the unique pharmacological profile of oxypertine may be related to its therapeutic effect of activating apathetic patients, and that both sulpiride and oxypertine may cause tardive dyskinesia, as haloperidol does.

Animals↗
PubMed1992

Invasion of Streptococcus mutans, Streptococcus intermedius and Propionibacterium acnes into the teeth of gnotobiotic rats.

Germ-free rats, fed a modified cariogenic diet 2000 with a reduced sucrose content of 25%, were inoculated with a strain of Streptococcus mutans, Streptococcus intermedius or Propionibacterium acnes, respectively. After 100 days on the diet, the rats were sacrificed. Microscopic examination of stained decalcified tooth sections revealed marked destruction of the outer zones of the dentin infected with S. mutans. The destruction was closely associated with the formation of glucan-mediated large aggregates of S. mutans. The aggregates, however, were rarely formed in the deep zones of the infected dentin. Inoculation with S. intermedius and P. acnes had little effect on the microscopic outline of the decalcified tooth sections. However, the staining behavior of the sections with Mallory's method, Alcian blue-PAS and silver was like that of the tooth sections infected with S. mutans, even in the central and inner zones of the dentin. The histochemical alterations of the deep zones of the dentin induced by the three infected bacteria appeared to be due to their proteolytic rather than to their acidogenic activities.

Animals↗
PubMed1992

Construction of a continent catheterizable urinary valve from a gastric segment in dogs.

We constructed a continent, catheterizable urinary valve from a gastric segment in 7 dogs. A vascularized gastric segment was isolated from the greater curvature and was tubularized. A cuff was made at the distal end of the tube. The gastric tube was anastomosed to the dome of the bladder with intussusception of the cuff portion into the bladder cavity. The valve provided continence over a wide range of bladder pressure. However, an ulcer of the bladder developed where the gastric mucosa of the cuff faced the bladder mucosa in 5 dogs, with a resultant intraperitoneal perforation in 2 dogs. The development of the bladder ulcer may be a serious complication of an anastomosis of an isolated gastric segment to the bladder.

Animals↗
PubMed1992

Microscopic structure of renal dysplasia in a man with ectopic ureter opening into the seminal tract.

Histologically, we examined a dysplastic kidney obtained from a patient with an ectopic ureter opening into the seminal tract. The dysplastic kidney did not have any normal renal tissue or typical primitive ducts but epididymis- and prostate-like ducts. The last ducts contained degenerating spermatozoa in the lumen. The presence of epididymis- and prostate-like ducts is considered to be characteristic of dysplastic kidneys in this anomaly.

Adult↗
PubMed1992

Roles of insulin resistance and beta-cell dysfunction in dexamethasone-induced diabetes.

The roles of insulin resistance and beta-cell dysfunction in glucocorticoid-induced diabetes were determined in Wistar and Zucker (fa/fa) rats. All Wistar rats treated with 5 mg/kg per d of dexamethasone for 24 d exhibited increased beta-cell mass and basal and arginine-stimulated insulin secretion, indicating insulin resistance, but only 16% became diabetic. The insulin response to 20 mM glucose was normal in the perfused pancreas of all normoglycemic dexamethasone-treated rats but absent in every diabetic rat. Immunostainable high Km beta-cell transporter, GLUT-2, was present in approximately 100% of beta-cells of normoglycemic rats, but in only 25% of beta cells of diabetic rats. GLUT-2 mRNA was not reduced. All Zucker (fa/fa) rats treated with 0.2-0.4 mg/kg per d of dexamethasone for 24 d became diabetic and glucose-stimulated insulin secretion was absent in all. High Km glucose transport in islets was 50% below nondiabetic controls. Only 25% of beta cells of diabetic rats were GLUT-2-positive compared with approximately 100% in controls. Total pancreatic GLUT-2 mRNA was increased twofold suggesting a posttranscriptional abnormality. We conclude that dexamethasone induces insulin resistance, whether or not it induces hyperglycemia. Whenever hyperglycemia is present, GLUT-2-positive beta cells are reduced, high Km glucose transport into beta cells is attenuated and the insulin response to glucose is absent.

Animals↗
PubMed1992

Intracerebral schwannoma: case report.

A case of intraparenchymal schwannoma is presented. The neuroradiological findings of reported intraparenchymal schwannomas, including the case reported here, are discussed. The specific tumor characteristics are emphasized. This report appears to be the only documentation as a result of magnetic resonance imaging of this specific tumor.

Adolescent↗
PubMed1992

Intraorbital ophthalmic artery aneurysm: case report.

A rare case is presented of a nonruptured aneurysm of the intraorbital ophthalmic artery in which successful resection of the aneurysm resulted in improvement of preoperative progressive signs caused by the mass effect of the aneurysm. The surgical management of this rare entity is discussed with special attention given to the collateral circulation of the ophthalmic artery from the external carotid artery.

Aneurysm↗
PubMed1992

Coordinate regulation of amylin and insulin expression in response to hypoglycemia and fasting.

Amylin is a 37-amino acid peptide synthesized in the pancreatic beta-cell and cosecreted with insulin. In situ hybridization of nondiabetic rat pancreas shows that insulin and amylin RNA are both localized within the islet of Langerhans in a similar distribution. After 12 days of insulin-induced hypoglycemia (mean blood glucose 3.0 +/- 0.4 mM [54 +/- 8 mg/dl]), both insulin and amylin RNA fell greater than 95%. However, maintenance of euglycemia by simultaneous infusion of glucose with insulin did not suppress insulin or amylin RNA. Fasting suppressed amylin and insulin secretion from the isolated, perfused pancreas 70 and 58%, respectively, and with refeeding, secretion rates recovered to fed levels. Despite these changes in the rates of secretion, the relative ratio of amylin to insulin was not significantly different in fed, fasted, or refed rats. The molar ratio of insulin to amylin was estimated to be 100:2.3-2.6. Both insulin and amylin RNA was suppressed approximately 50% in response to fasting. Thus, although the absolute amounts of insulin and amylin change substantially under the conditions tested, the relative amounts of these peptides do not change.

Amyloid↗
PubMed1992

Aneurysms arising from the proximal (A1) segment of the anterior cerebral artery. A study of 38 cases.

This study reviews aneurysms of the proximal segment (A1) of the anterior cerebral artery in 38 patients (23 men and 15 women) and their surgical, angiographic, and clinical management. Thirty-seven aneurysms were saccular and one was fusiform. The incidence of A1 aneurysms among a total of 4295 aneurysm cases treated was 0.88%. Multiple aneurysms occurred in 17 patients (44.7%) of the 38 cases; in 10 (58.8%), there was bleeding from the A1 aneurysm. The aneurysms were classified into five categories according to the mode of origin of the aneurysm in relation to the A1 segment: in 21 cases, aneurysms originated from the junction of the A1 segment and a perforating artery; in eight, from the A1 segment directly; in six, from the proximal end of the A1 fenestration; and in two, from the junction of the A1 segment and the cortical branch. One patient had a fusiform aneurysm. Computerized tomography (CT) of these aneurysms revealed bleeding extending to the septum pellucidum similar to that of anterior communicating artery aneurysms. When performing radical surgery it is very important to recognize the characteristics of A1 aneurysms, including multiplicity, a high incidence of vascular anomalies (especially A1 fenestration), and their similarity to anterior communicating artery aneurysms on CT.

Adult↗
PubMed1992

Cerebral blood flow and metabolism following superficial temporal artery to superior cerebellar artery bypass for vertebrobasilar occlusive disease.

In order to clarify the effectiveness of extracranial-intracranial bypass operations in patients with vertebrobasilar occlusive disease, the authors used positron emission tomography to investigate the cerebral blood flow (CBF) and metabolism of eight patients undergoing superficial temporal artery (STA)-superior cerebellar artery (SCA) bypass procedures. In the preoperative studies, CBF in the region of the posterior fossa was low and the oxygen extraction fraction (OEF) was high, the so-called "misery perfusion syndrome." Such changes were evident in both the posterior circulation and the anterior circulation regions. Postoperatively, there was a significant increase in CBF, a significant decrease in the OEF not only in the region of posterior circulation but also over the entire brain, and a disappearance of the uncoupling between CBF and oxygen metabolism. The STA-SCA bypass procedure is effective in improving CBF and metabolism in patients with vertebrobasilar occlusive disease.

Arterial Occlusive Diseases↗