Biomedical subjects

T Omae

Publications and source records attributed to T Omae.

480 records · Page 27Linked to original sources

PubMedDate not supplied

Cerebrospinal fluid and arterial lactate, pyruvate and acid-base balance in patients with intracranial hemorrhages.

Lactate and pyruvate concentrations and acid-base balance in cerebrospinal fluid (CSF) and arterial blood were determined in patients with intracranial hemorrhages (28 subarachnoid hemorrhages and 15 intracerebral hemorrhages). A greater increase in CSF lactate and lactate-pyruvate ratio (L/P ratio) was observed in patients with impairment of consciousness, focal neurological deficits, poor prognosis, or CSF pressures higher than 300 mm H2O. A combination of CSF lactate greater than 2.5 mM per liter, L/P ration above 20, bicarbonate less than 20.4 mEq per liter, pH below 7.276, or arterial PCO2 below 31.5 mm Hg seems to indicate poor prognosis from intracranial hemorrhage. The mechanism of hyperventilation in acute cerebrovascular diseases and of CSF pH regulation in acid-base disturbances was also discussed.

Acid-Base Imbalance↗

PubMedDate not supplied

Lactate and pyruvate concentrations, and acid-base balance of cerebrospinal fluid in experimentally induced intracerebral and subarachnoid hemorrhage in dogs.

The effect of blood injected into either subarachnoid space or subcortical brain tissue upon lactate and pyruvate concentrations as well as acid-base balance of cerebrospinal fluid (CSF) was studied in the anesthetized dog. CSF lactate and lactate/pyruvate ratio (L/P ratio) increased progressively following the intracranial injection of blood and reached the maximum level at six hours after injection. These changes were significantly greater in animals with intracerebral hematoma than in those with subarachnoid hemorrhage (SAH). An increase in CSF lactate and L/P ratio in hemorrhagic CSF seems to be caused by two different factors. Shed blood cells per se produce lactate and pyruvate, and blood in the subarachnoid space and intracerebral hematomas cause secondary changes in brain tissue metabolism by a probable reduction of cerebral blood flow. Therefore, an increase in CSF lactate with a concomitant rise in CSF L/P ratio is a useful indicator for brain tissue hypoxia, even when CSF is hemorrhagic. The association of an increase in CSF lactate to a disproportionate decrease in CSF HCO-3 was also observed in these animals.

Acid-Base Imbalance↗

PubMedDate not supplied

Cerebral infarction following bilateral carotid artery ligation in normotensive and spontaneously hypertensive rats: a pathological study.

A pathological examination was performed on normotensive rats (NTR) and spontaneously hypertensive rats (SHR) following bilateral common carotid artery ligation. After ligation, diffuse and extensive cerebral infarcts in the carotid artery territory occurred frequently in SHR, while NTR occasionally had well-circumscribed small infarcts. The posterior communicating arteries, which are the major anastomotic channels connecting the carotid and vertebrobasilar systems, did not show any anomalies and were well developed in SHR and NTR. Vascular changes secondary to hypertension, such as fibrinoid necrosis or thickening of the wall, were not observed in SHR. Because of the paucity of structural difference of the blood vessels, the more diffuse and extensive cerebral infarcts in SHR after carotid occlusion were attributed to the hemodynamic difference rather than the morphological difference between the two groups. The results of the present experiment suggest that hypertension per se, i.e., hemodynamic factors, may be operative for the development of cerebral infarction.

Animals↗

PubMedDate not supplied

Prognosis of occlusive cerbrovascular diseases in normotensive and hypertensive subjects.

Comparison of the clinical features, especially prognosis, in cerebral infarction was made between nine normotensive subjects and 16 hypertensive patients with an 80% stenosis or occlusion of the intracranial or extracranial arteries. Our own criteria for evaluating hypertension were employed on the basis of the following items: a past history of hypertension, blood pressure levels on admission and during hospitalization, degree of retinopathy, and ECG changes. In 17 of 25 cases, brain circulation was measured by the intravenous RISA technique. Abnormalities of the EEG and reduction of cranial blood flow were greater, and an early prognosis for neurological deficits in the first two months after the onset of stroke was poorer in the hypertensive group than inthe normotensive group. These results are contradictory to the observations of others.

Adult↗

PubMedDate not supplied

Effect of carotid artery ligation on regional cerebral blood flow in normotensive and spontaneously hypertensive rats.

Regional cerebral blood flow (rCBF) was measured in normotensive rate (NTR) and spontaneously hypertensive rats (SHR), in a lightly anesthetized state and with control of PaCO2 by artificial ventilation. Without carotid artery ligation, NTR and SHR showed almost identical rCBF values and distribution, despite significantly elevated levels of blood pressure in SHR. Bilateral carotid artery ligation, however, caused much more pronounced decreases of rCBF (ischemia) in SHR than NTR, in regions supplied by the carotid artery. The reduction of rCBF in SHR was rather homogenous and symmetrical. Mechanisms causing the differences between NTR and SHR are discussed.

Animals↗

PubMedDate not supplied

Long-term prognosis for cerebral infarction in relation to brain circulation--a 7-year follow up study.

Seventy-seven patients with cerebral infarction have been re-examined every year and followed for 7 years. Thirty-one patients had normal cranial blood flow (BF) and the remaining 46 had subnormal cranial BF, determined by the intravenous RISA method at the time of the original attack. During a 7-year follow up, 7 patients (22.6%) of the normal cranial BF group died; 3 of stroke and the remaining 4 from other causes, while 24 patients (52.2%) of the subnormal cranial BF group died; 13 of stroke and the remaining 11 of various diseases. The cumulative survival rate was consistently lower in the subnormal cranial BF group than the normal one. This difference reached statistical significance at 5 and 7 years of follow up. However, stroke recurrence did not differ significantly between the 2 groups. This suggests that a decreased cranial BF is an indicator of a poor long-term prognosis.

Cerebrovascular Circulation↗

PubMedDate not supplied

Effects of acute hypertension on brain metabolism in normotensive, renovascular hypertensive and spontaneously hypertensive rats.

Effects of angiotensin-induced acute hypertension on cerebral metabolism were studied in normotensive (NTR), spontaneously hypertensive (SHR) and experimental renovascular hypertensive rats (RHR). Lactate, pyruvate and adenosine triphosphate (ATP) concentrations in the brain frozen in situ at 18--20 min after angiotensin infusion, which raised mean arterial pressure (MAP) by 28--62% of control, were determined by enzymatic methods. Supratentorial lactate was significantly increased to 135% of control in RHR, its increase being correlated with the degree of hypertension, wherease it remained unchanged in NTR or SHR. Furthermore, RHR showed a tendency toward increase in lactate/pyruvate ratio with a decrease in ATP despite no change of arterial acid-base balance measured simultaneously before and after acute induced hypertension. From the present study, it is postulated that some renal factor seems to contribute ischemic metabolic changes in RHR following acute hypertension. The possible effect of renin on the vascular permeability is discussed as the pathogenesis of hypertensive encephalopathy.

Acute Disease↗

PubMedDate not supplied

Effect of nafamostat mesilate on bradykinin generation during low-density lipoprotein apheresis using a dextran sulfate cellulose column.

The dextran sulfate (DS) cellulose column usually used for low-density lipoprotein (LDL) apheresis, is an activator of the contact phase of intrinsic coagulation pathway. Hageman factor (factor XII), high-molecular-weight kininogen (HMWK) and prekallikrein (PK) form a complex on the surface of this activator, and bradykinin is released from HMWK by the action of kallikrein converted from PK. Heparin, a frequently used anticoagulant, has no effect on this process, whereas a protease inhibitor, nafamostat mesilate (FUT-175) is thought to inhibit the process. Five patients with severe hypercholesterolemia were treated with LDL apheresis using heparin or FUT-175, each on a different day. During treatment with heparin, factor XII, HMWK, and PK were markedly decreased by passing through the DS column. A distinct generation of bradykinin was observed by passing through the DS column, which led to an increase of blood bradykinin levels from 12.5 +/- 5.3(Mean +/- SEM) pg/ml to 127.3 +/- 67.1 pg/ml after 1000 ml plasma treatment. FUT-175 almost completely suppressed this bradykinin generation. Because bradykinin generated during LDL apheresis seems to have some vasodilative effect, FUT-175 might be preferred in cases with unstable hemodynamics, although this presumption remains to be demonstrated.

Adult↗

PubMedDate not supplied

Imaging of the basal cerebral arteries and measurement of blood velocity in adults by using transcranial real-time color flow Doppler sonography.

We report an attempt to obtain images of the basal cerebral arteries and to measure the quantitative flow velocity in these arteries from outside the skull via the color Doppler imaging method. In 25 healthy volunteers, 22-41 years old, the transducer was positioned just superior to the zygomatic arch and anterior to the external ear canal. The absolute flow velocity was calculated by dividing the measured velocity by the cosine of the incident angle. The middle cerebral artery was readily identified in all subjects, but the anterior cerebral artery was seen in only 7/50, and the posterior cerebral artery in 27/50. The corrected mean velocity of the horizontal middle cerebral artery was 86 +/- 17 cm/sec at an average incident angle of 49 degrees. However, it was difficult to calculate the absolute flow velocity in the anterior and posterior cerebral arteries because the length of those arteries delineated was too short to read the incident angle. The reproducibility of the mean blood velocity in the middle cerebral artery was tested by two examiners on two different occasions, and showed a linear regression with a correlation coefficient of 0.93 (p less than .001) when the correction with the incident angle was made. Transcranial real-time color-flow Doppler imaging permits more accurate noninvasive quantification of cerebral hemodynamic consequences than previous methods do.

Adult↗

PubMedDate not supplied

Human mesor-hypertensive chronorisk.

Twelve endocrine variables in blood from a small number of clinically healthy adult women were sampled systematically around the clock and the seasons. Pattern discrimination methods singled out certain hormone values in certain seasons as classifiers for a high vs low risk of developing diseases associated with a high blood pressure. Further evidence in support of such classifiers is obtained on data from adolescent, menstrually cycling young adults and post-menopausal women, here analyzed as pool of series, with the scope of the data from any one age group greatly extended by a resampling procedure, namely, by bootstrapping. This mathematical approach was carried out on data series around the clock and seasons on several hormones as well as systolic and diastolic blood pressure. Classifier roles were strongly supported for plasma aldosterone and thyroid stimulating hormone, originally by an analysis of variance and, in the case of aldosterone, by circannual cosinor analysis and by numerical resampling. Circannual bootstrapping, a procedure recommended for broad routine use as a safeguard for hypothesis testing, was also done for plasma cortisol, dehydro-epi-androsterone sulfate and prolactin, variables for which (parametric) analyses of variance and cosinors did not reveal any difference between groups at high and low cardiovascular risk. In these instances, bootstrapping results are tentative and await further analyses. Results show the ability of circannual bootstrapping to detect outliers. Identification of classifiers provides cost-effective endocrine checks complementing the targeted automatic monitoring of blood pressure. Circannual indices for risk evaluation are, however, costly in several ways since it takes at least a year and quite a few samples to estimate them reliably. Accordingly, we also extended the scope of previous results by the application of an added procedure for circadian bootstrapping. With circadian as well as circannual bootstrapping, we here illustrate a major potential component of a system of chrono-engineering for health maintenance. This system should start with focus on the newborn. The results on adults here analyzed are likely to be more prominent in the neonate, to the extent that they are genetic in origin, yet amenable to modification by the extra-uterine environment.

Adolescent↗

PubMedDate not supplied

Aminoglutethimide effect on circadian rhythms in urinary variables in a patient with idiopathic hyperaldosteronism.

Aminoglutethimide (AG: 750 mg/day) was administered to a patient with idiopathic hyperaldosteronism (IHA) and circadian rhythms in urinary excretion of sodium (UNaV), potassium (UKV), aldosterone (AER) and 17-OHCS were analyzed by the single cosinor method. Urine was collected every 4h for 24h on the day before and on the 1st, 3rd and 7th day of AG administration, and above variables in each sample were determined. Circadian rhythms of 14 patients with primary aldosteronism (PA) who served as controls were also analyzed. In the present case, circadian acrophases in UNaV and AER studied before AG administration occurred at 22(19) and 07(05), respectively. They were similar to those of preoperative PA-patients. Circadian acrophase in UNaV occurred earlier with AG administration and on the 7th day it was at 14(05), a value similar to that of postoperative PA-patients. Circadian mesor in AER decreased remarkably from 4.1 to 0.6 micrograms/4h with AG administration, as did circadian mesor in UKV, whereas circadian mesor and acrophase in 17-OHCS did not change. Thus, the circadian characteristics in urinary variables in the present IHA-case were pathophysiologically similar to those of PA.

17-Hydroxycorticosteroids↗

PubMedDate not supplied

Cerebral autoregulation in young spontaneously hypertensive rats. Effect of sympathetic denervation.

Autoregulation of cerebral blood flow was studied with the hydrogen clearance method during development of hypertension in young spontaneously hypertensive rats. To examine the influence of sympathetic nerves on autoregulatory range, the unilateral superior cervical ganglion was removed 2 hours or 2 or 5 weeks before the study. Wall-to-lumen ratio of cerebral arteries was determined with freeze substitution technique. Basal blood pressures were 87 +/- 1 mm Hg (mean +/- SEM) at 4 weeks of age, 105 +/- 2 at 6 weeks, and 126 +/- 3 at 9 weeks, although resting cerebral blood flow was unchanged. Initially, cerebral blood flow remained relatively constant when the blood pressure was raised by intravenous infusion of phenylephrine. The upper limits of cerebral blood flow autoregulation in these groups were 110 +/- 4 mm Hg, 126 +/- 7, and 159 +/- 6 respectively. Acute ganglionectomy significantly lowered the upper limits (p less than 0.05), but chronic denervation did not affect the autoregulatory range. The wall-to-lumen ratios of cerebral arteries were 0.136 +/- 0.007 at 4 weeks and 0.130 +/- 0.005 at 9 weeks. These differences were not significant, nor did sympathetic denervation alter the ratio. These results indicate that (1) the upward shift of the autoregulation is closely related to a rise in the basal blood pressure, (2) acute interruption of sympathetic nerves modulates the autoregulatory range, and (3) adaptation of cerebral blood flow autoregulation to early developmental hypertension may be attributed to factors other than vascular smooth muscle hypertrophy.

Animals↗