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Biomedical subjects

T Omae

Publications and source records attributed to T Omae.

At least 469 records · Page 26Linked to original sources
PubMedDate not supplied

Blood concentration and urinary excretion of captopril (SQ 14,225) in patients with chronic renal failure.

Blood concentration and urinary excretion of captopril following 50 mg oral administration were determined by high-performance liquid chromatography in normal subjects and patients with chronic renal failure. In normal subjects, the maximum blood concentration of the free form of captopril was obtained within 1 hour and was not detectable after 6 hours; 41% of administered captopril was excreted into the urine as free form and metabolites within 2 hours, and 58% within 6 hours. In chronic renal failure patients with an average serum creatinine of 5.1 mg/dl, the absorption constant (Ka), maximum concentration (Cmax), and area under the blood concentration curve (AUC) were not significantly different from those in the normal subjects, but the elimination constant (Ke) and biological half-life (T1/2) showed a significant delay in the disappearance of captopril from the blood (p less than 0.01 respectively). The cumulative amount of urinary excretion of either free-form captopril or its' metabolites was significantly decreased at 2, 4, and 6 hours in chronic renal failure patients (p less than 0.01 or less, respectively). Impairment of kidney function is suggested to be an important factor in the promotion of blood retention of captopril.

Adult↗
PubMedDate not supplied

Influence of sex on cerebral ischemia following bilateral carotid occlusion in spontaneously hypertensive rats: a metabolic study.

Cerebral lactate, pyruvate and adenosine triphosphate (ATP), and acid-base balance were measured in male and female spontaneously hypertensive rats (SHR) before, and 1, 3 and 5 hours after bilateral carotid occlusion. In male SHR, cerebral lactate and the lactate/pyruvate (L/P) ratio progressively increased after occlusion, while cerebral ATP decreased. In female SHR, an increase in lactate and the L/P ratio was less marked than in male SHR. Cerebral ATP remained unchanged 5 hours after occlusion. These data suggest that bilateral carotid artery occlusion may cause more pronounced ischemic changes in the brain in male SHR than in female SHR, resulting in a greater increase in lactate with a concomitant decrease in ATP in male SHR. Results suggest that female SHR are more resistant to cerebral ischemia following bilateral carotid occlusion than male SHR. Blood pressure and gonads in the susceptibility to cerebral ischemia are discussed.

Adenosine Triphosphate↗
PubMedDate not supplied

Brain metabolism following bilateral carotid occlusion in 2 different models of experimental hypertensive rats.

Brain metabolites and arterial acid-base measurements were made one hr after bilateral carotid artery occlusion in 2 different models of hypertensive rats. Animals used included renovascular hypertensive rats (RHR) with an altered renin-angiotensin system and desoxycorticosterone hypertensive rats (DHR) with low plasma renin activity (PRA). The mean value for supratentorial lactate of 7.41 mM/kg in RHR was significantly higher than in DHR (3.90 MM/kg) or in control normotensive rats (3.10 - 2.56 mM/kg). Concomitantly, the lactate/pyruvate ratio tended to increase and ATP to decrease in RHR only. In these same rats (RHR) infratentorial lactate was also increased. The results suggest that bilateral carotid occlusion leads to anaerobic metabolism of the brain in RHR but not in DHR, suggesting that the renin-angiotensin system may play some role in the susceptibility to cerebral ischemia following carotid occlusion in the hypertensive rats.

Adenosine Triphosphate↗
PubMedDate not supplied

Experimental cerebral ischemia in spontaneously hypertensive rats (SHR): Importance of degree of hypertension.

To study the relationship between the degree of hypertension and experimentally-induced cerebral ischemia, brain metabolites, including lactate, pyruvate and adenosine triphosphate (ATP) were determined one hour after bilateral carotid occlusion in 119 spontaneously hypertensive rats (SHR) with a variety of mean arterial pressures (MAP). Of these, 36 SHR were given antihypertensive agents for 10 weeks to reduce blood pressure prior to the experiment. There was a significant linear correlation between MAP before and either supratentorial lactate (r = 0.482, p less than 0.001) or the lactate/pyruvate ratio (r = 0.388, p less than 0.001) in the brain after carotid occlusion. An inverse correlation was observed between supratentorial lactate and either ATP (r = -0.627, p less than 0.001) or arterial PCO2 (r = -0.477, p less than 0.001) after carotid occlusion. The changes suggest that the animals with a higher MAP had a greater increase in ischemic metabolites with a decrease in ATP and a more pronounced hypocapnia after carotid occlusion. This hypocapnia is believed to be due to hyperventilation induced by cerebral ischemia. It is concluded that hypertensive rats are more susceptible to cerebral ischemia and the susceptibility is related to the degree of hypertension. By long-term lowering of the blood pressure prior to carotid occlusion, the ischemic changes are lessened in this experimental model.

Adenosine Triphosphate↗
PubMedDate not supplied

Decreasing trend in incidence and mortality from stroke in Hisayama residents, Japan.

The incidence and mortality from stroke during the period 1961 to 1976, among 1,621 subjects aged 40 and over at entry, in Hisayama community, Kyushu Island, Japan, were analyzed. A major age-related decline in the incidence of cerebral infarction occurred in both sexes. The average annual incidence of cerebral infarction also fell continuously in both sexes throughout the whole observation period. The 5-year annual mortality rate from cerebral hemorrhage also showed a decrease in men, but fluctuated in women. The 5-year mortality from cerebral infarction slightly increased in both sexes.

Adult↗
PubMedDate not supplied

Effects of arterial hypotension on brain metabolism in normotensive and spontaneously hypertensive rats.

The effects of graded systemic hypotension induced by the combination of bleeding and trimethaphan camsylate infusion on brain metabolism were studied in normotensive rats (NTR) and spontaneously hypertensive rats (SHR). Metabolites such as lactate, pyruvate and adenosine triphosphate (ATP) of the brain frozen in situ were measured at the end of 1 hour of hypotension. In SHR, either cerebral lactate or the lactate/pyruvate (L/P) ratio increased rapidly and progressively with a concomitant decrease in ATP, when mean arterial blood pressure (MAP) fell below about 50 mm Hg. In NTR, on the other hand, the metabolites changed little until MAP fell to about 40 mm Hg. Metabolic derangements of the brain during profound hypotension were more marked and severe in SHR than in NTR. These results suggest that the SHR is more vulnerable to severe hypotension than NTR, probably due to hemodynamic difference of the cerebral circulation between the 2 groups. The increased cerebral vascular resistance and upward shift of cerebral autoregulation in hypertension might be responsible for this vulnerability.

Adenosine Triphosphate↗
PubMedDate not supplied

Changes in local cerebral blood flow following bilateral carotid occlusion in spontaneously hypertensive and normotensive rats.

Local blood flow in the cortex and thalamus was measured by the hydrogen clearance method in spontaneously hypertensive rats (SHR) and normotensive rats (NTR) before and after bilateral carotid occlusion. There were no differences in the resting blood flow values between SHR and NTR. Following carotid occlusion cortical blood flow in SHR was markedly reduced to 17% of the resting level at 1 h and, further, to less than 10% at 3--5 h period, while in NTR it decreased only to 36--38% during 5 h occlusion. Thalamic blood flow in SHR was decreased to 39% at 1 hr and to below 20% at 3--5 h, while in NTR it remained approximately 40% of the resting level during 5 h occlusion. The blood flow reduction in either cortex or thalamus after carotid occlusion was much greater in SHR than in NTR. This difference was highly significant. The increased cerebral vascular resistance caused by persistent hypertension may play an important role in a greater reduction of blood flow in SHR after carotid occlusion. Relation of the blood flow reduction to the brain metabolism is discussed.

Animals↗
PubMedDate not supplied

Effects of hyperventilation on cerebral blood flow and brain tissue metabolism in normotensive and spontaneously hypertensive rats.

Cerebral vascular carbon dioxide (CO2) reactivities were compared in normotensive (NTR) and hypertensive (SHR) rats. Cerebral blood flow (CBF) in cortex and thalamus were evaluated before and during one hour of hyperventilation. After one hour of hyperventilation brain lactate, pyruvate, and ATP concentrations were also determined. Significant and similar reductions of CBF due to hyperventilation induce hypocapnia were found in both NTR and SHR groups. In contrast the percent increase in cerebrovascular resistance (CVR) per unit decrease in paCO2 was significant, indicating that hypocapnia induced vasoconstriction is greater in NTR than in SHR groups. During hyperventilation the average value for lactate in the NTR group was 3.98 mM/kg. In contrast it was 3.15 mM/kg in the SHR group, a significant difference (p less than 0.05). When paCO2 fell below 15 mm Hg the cerebral lactate increased strikingly in the NTR group and cortical CVR was reduced suggesting that an accumulation of the ischemic metabolites caused dilatation of the constricted cerebral vessels. In contrast the SHR group disclosed no such changes. The increase CVR characteristic of SHR appeared to diminish the cerebral vasoconstrictive response to hypocapnia. As a result ischemic metabolites in the brain do not increase in this group to the degree that they do in NTR.

Adenosine Triphosphate↗
PubMedDate not supplied

Disruption of blood-brain barrier following bilateral carotid artery occlusion in spontaneously hypertensive rats. A quantitative study.

The present study was designed to clarify the relationship of cerebral blood flow (CBF) to blood-brain barrier (BBB) in the ischemic brains with or without recirculation, which were produced by clipping of both common carotid arteries in spontaneously hypertensive rats. CBF was measured by the hydrogen clearance method and BBB function was evaluated by the permeability of 131I-albumin and Evans blue dye. Cortical CBF was reduced from 48.8 +/- 9.5 to 4.0 +/- 1.2 ml/100 gm/min during 1 hr ischemia and further to 2.6 +/- 0.3 ml/100 gm/min during 3 hrs ischemia, while thalamic CBF was reduced much less from 50.0 +/- 3.6 to 17.9 +/- 6.5 ml/100 gm/min and to 17.5 +/- 11.0 ml/100 gm/min, respectively. There was no increase in permeability to protein tracers observed in such 1 hr or 3 hrs ischemic brain. Both cortical and thalamic CBF were markedly increased 2.5 to 6 fold of resting values at 5 min after recirculation in the 1 hr ischemic brain. In the 3 hrs ischemic brain, however, both CBF were only slightly increased but never restored to the resting level even at 30 min after recirculation. In such reperfused brains, exudation to Evans blue dye was observed in none of 16 animals with 1 hr ischemia, but in 18 of 23 with 3 hrs ischemia. Disruption of BBB was twice more frequent in the cortex (77.8%) than in either thalamus (33.3%) or hippocampus (33.3%). Permeability index of 131I-albumin (brain albumin/blood albumin) was significantly higher in the ischemic areas stained with blue dye (2.07 +/- 0.45%) than in non-ischemic control brain (0.10 +/- 0.01%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Cerebrovascular diseases and their underlying vascular lesions in Hisayama, Japan--a pathological study of autopsy cases.

Frequency of cerebrovascular diseases (CVD) and their underlying vascular lesions were analyzed in 724 autopsy cases, aged 40 years and over, in the community of Hisayama, Japan during the period 1961 to 1981. Cerebral infarction (CI) was more frequently found at autopsy than cerebral hemorrhage (CH) with a ratio of infarction and hemorrhage of 4.4. Small CI occupied 75.7% of the cases with CI. The cases with any type of CVD showed more severe atherosclerosis of the major cerebral arteries than did those without CI or CH. Cerebral atherosclerosis of those with large and medium CI was the greatest, and with decreasing severity in those with small CI and with CH sequentially. Fibrinoid necrosis of the intracerebral small arteries was frequently found in cases with hypertension and particularly associated with CH. The decline in frequency of CH was confirmed; however, changes in frequency of CI were not evident. Fibrinoid necrosis was also reduced, although the severity of cerebral atherosclerosis showed no definite change. The decline of CH seemed to be ascribed to the reduction of fibrinoid necrosis of the intracerebral small arteries.

Adult↗
PubMedDate not supplied

Nationwide co-operative study of intracranial aneurysm surgery in Japan.

A cooperative study was made of 4750 intracranial aneurysm cases collected from 133 neurosurgical clinics in Japan by letter inquiry for the period of 2 years from January 1974 to December 1975. Among them, 4124 cases (87%) had a single aneurysm, and 626 cases (13%) had multiple ones. Direct radical surgery was done in 78% of all cases, carotid ligation in 2% and non-surgical treatment in 17%. Direct surgery in a mortality rate of 15% for ruptured aneurysm cases and 7% for nonruptured cases. Radical surgery within 24 hours after rupture had a mortality of 51%, while those within 1 week and 2 weeks were 39% and 30% respectively; grade I or II patients, however, showed much better surgical results even in early operations. The neurosurgical clinics included in this study were spread throughout most of Japan. Micro-surgical technic was already in use of aneurysm surgery at the time of this study in Japan.

Adolescent↗
PubMedDate not supplied

Effects of hematocrit on brain metabolism in experimentally induced cerebral ischemia in spontaneously hypertensive rats (SHR).

Brain tissue lactate, pyruvate, and adenosine triphosphate (ATP) were measured 60 min after bilateral carotid ligation in spontaneously hypertensive rats, of which hematocrit (HCT) was varied by exchanging with isovolemic homologous red cells, plasma or whole blood. Supratentorial lactate of the ischemic brain was increased more in high HCT (greater than or equal to 50%) and less in low HCT (30-39%) compared with normal HCT (40-49%). In very low HCT (less than 30%), however, lactate was increased to further extent compared with any other group of HCT (ANOVA p less than 0.0001). Lactate/pyruvate (L/P) ratio of the ischemic brain showed similar changes, namely U-shaped correlation to HCT. In contrast, supratentorial ATP was decreased more markedly in very low HCT, followed by high and normal HCT, and minimally decreased in low HCT, demonstrating an inverse U-shaped relationship to HCT. Mean arterial pressure and arterial acid-base parameters in ischemic animals did not differ among HCT groups. There were no HCT-related changes of brain metabolites in non-ischemic control rats. These findings indicate that cerebral ischemia following carotid ligation is more severe in high HCT but less in low HCT, probably due to hemodynamic effects of HCT changes. When HCT is reduced to below 30%, however, insufficient oxygen supply to the brain or anemic hypoxia may superimpose on ischemia, resulting in more markedly impairment of brain metabolism. The role of HCT as a cause of cerebral ischemia and its severity is discussed.

Acid-Base Equilibrium↗
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Cerebral blood flow and tissue metabolism in experimental cerebral ischemia of spontaneously hypertensive rats with hyper-, normo-, and hypoglycemia.

The present study was designed to clarify the effect of blood glucose level on cerebral blood flow and metabolism during and after acute cerebral ischemia induced by bilateral carotid ligation (BCL) in spontaneously hypertensive rats (SHR). Blood glucose levels were varied by intraperitoneal infusion of 50% of glucose (hyperglycemia), insulin with hypertonic saline (hypoglycemia) or hypertonic saline (normoglycemia). Cerebral blood flow (CBF) in the parietal cortex and thalamus was measured by hydrogen clearance technique, and the supratentorial metabolites of the brain frozen in situ were determined by the enzymatic method. In non-ischemic animals, blood glucose levels had no influence on the supratentorial lactate, pyruvate or adenosine triphosphate (ATP) concentrations. In ischemic animals, however, cortical CBF was reduced to less than 1% of the resting value at 3 hours after BCL. However, there were no substantial differences of CBF during and after ischemia among 3 glycemic groups. Cerebral lactate in the ischemic brain greatly increased in hyperglycemia (34.97 +/- 1.29 mmol/kg), moderately in normoglycemia (23.43 +/- 3.13 mmol/kg) and less in hypoglycemia (7.20 +/- 1.54 mmol/kg). In contrast, cerebral ATP decreased in hyperglycemia (0.93 +/- 0.19 mmol/kg) as much as it did in normoglycemia (1.04 +/- 0.25 mmol/kg), while ATP reduction was much greater in hypoglycemia (0.45 +/- 0.05 mmol/kg). At 1-hour recirculation after 3-hour ischemia, ATP tended to increase in all groups of animals, indicating the recovery of energy metabolism. Such metabolic recovery after recirculation was good in hypo- and normoglycemia, and was also evident in hyperglycemia. Our results suggest that hyperglycemia is not necessarily an unfavorable condition in acute incomplete cerebral ischemia.

Adenosine Triphosphate↗
PubMedDate not supplied

Hematocrit as a risk factor of cerebral infarction: long-term prospective population survey in a Japanese rural community.

To elucidate the relation of hematocrit (Hct) to the incidence of cerebral infarction, a prospective follow-up study of 16 years (1965-81) was performed in a general population sample of 1220 Hisayama residents aged 44 and over, of both sexes. Most of the subjects who died during the follow-up period were autopsied, the rate being 89.0%. Hct decreased with advancing age in men, but not in women. The average value for Hct was significantly lower in women than in men. According to the mean value +/- 1 SD of Hct, the subjects were grouped into 3, in each sex as follows: low (less than 35%), normal (35-45%) and high (greater than or equal to 45%) for men, and, low (less than 30%), normal (30-40%) and high (greater than or equal to 40%) for women. During the follow-up period, cerebral infarction occurred in 117 patients. The cumulative incidence of cerebral infarction in the low Hct group for men was the lowest, even after adjustments for age and blood pressure. Conversely, the incidence in the low Hct group of women was significantly higher than that in the normal Hct group and was consistently increased with time during 2-5 years of the follow-up. After the 6th year or later, however, the incidence was gradually but significantly increased in the high Hct group, compared with the normal Hct group. Since Hct levels were related with other variables such as serum total cholesterol, serum total protein, Quetelet index and prevalence of hypertension in both sexes, heavy alcohol consumption in men, and glucose intolerance in women, such variables were taken into account using Cox's proportional hazards regression model.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Transient cerebral ischemic attacks in a Japanese community, Hisayama, Japan.

During a 20-year follow-up of 1,621 men and women aged 40 and over in Hisayama, Japan, 18 were found to have suffered transient cerebral ischemic attacks (TIAs) determined by clinical symptoms based on criteria proposed by the US Joint Committee for Stroke Facilities. The average annual incidence rate for the first TIA was 0.56 per 1,000 residents. Age and high blood pressure were strong determinants of TIAs for men. Nine of the 18 cases with TIAs (50%) subsequently developed cerebral infarction, an incidence significantly higher than that in the 1,603 subjects without TIAs (10.9%). Lacunar infarcts were most commonly found on pathologic examination of patients with TIAs who had had a subsequent stroke.

Age Factors↗