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Biomedical subjects

K Meguro

Publications and source records attributed to K Meguro.

At least 163 records · Page 9Linked to original sources
PubMed1989

[Pulmonary embolism as a complication in neurosurgical patients].

The overall incidence of pulmonary embolism (PE) among neurosurgical in-patients, whose ages ranged from 23 to 80, was 0.7%. Our report here is based on five cases of patients with PE. Four of these five patients were over 50 years of age. They had been admitted because of such reasons as brain tumor, spinal cord injury, intracerebral hematoma, and venous sinus thrombosis. Deep vein thrombosis (DVT) was seen in four but none were diagnosed before they had developed PE. Decreased level of consciousness and prolonged bed rest appeared to be common risk factors for PE. Mean duration between admission and onset of PE was 31 days. Although non-specific, tachycardia, tachypnea and hypoxemia were the most common signs and symptoms. As a definitive diagnostic procedure, pulmonary angiography was performed in most of cases. One patient required surgical embolectomy and others were treated with anticoagulation or fibrinolytic agents. In order to prevent recurrent thromboembolic phenomena, ligation of the inferior vena cava was a useful mode of treatment when anticoagulation was not indicated. And this approach seemed to be valid in most neurosurgical patients. We conclude that PE and DVT were not uncommon complications among Japanese neurosurgical patients and they can be treated successfully in collaboration with a cardiovascular surgeon if the diagnosis can be made correctly.

Adult↗
PubMed1988

The effect of sevoflurane on somatically induced sympathetic reflexes.

The effects of various inspiratory concentrations of sevoflurane anesthetics on the sympathetic reflex responses evoked in the left inferior cardiac nerve branch following an electrical stimulation to the ipsilateral superficial peroneal nerve were investigated in cats. At a 2.0% inspiratory concentration of sevoflurane, two components of the somato-sympathetic reflexes with two different latencies were recorded. The early component was due to an activation of myelinated A afferent fibers (referred to as the A-reflex), while the late component was due to an activation of unmyelinated C afferent fibers (referred to as the C-reflex). The increase in the concentration of sevoflurane from 2.0% to 3.0% resulted in about 50% attenuation of both the A- and C-reflexes. A further increase in the concentration of sevoflurane to 4.0% resulted in further suppression of both reflexes.

Journal Article↗
PubMed1988

Contribution of cholinergic vasodilators on the increase in cerebral cortical blood flow responses to the intravenous administration of thyrotropin releasing hormone in anesthetized rats.

The effect of an intravenous administration of thyrotropin-releasing hormone (TRH) on the regional cerebral blood flow in the sensory cortex was studied in halothane-anesthetized adult Wistar rats. The regional cerebral blood flow was continuously monitored with the laser Doppler flowmetry. The cerebral blood flow increased dose-dependently following the administration of 3 x 10(2) and 3 x 10(3) microns/kg TRH. The systemic blood pressure also increased simultaneously. After maintaining the systemic blood pressure at a constant level via a pressure reservoir system, the TRH-induced increases in the cerebral blood flow continued to be observed. In atropinized animals, the blood pressure increased as high as that indicated in non-atropinized animals following TRH administration, but the responses of the cerebral blood flow in the latter were much attenuated. It was suggested that the cholinergic vasodilative system contributed to the TRH-induced increase in cerebral blood flow.

Animals↗
PubMed1988

Selective potentiation of 5-methyl-2-(1-methylcyclohexyl)-4-oxazoleacetic acid (AD-4610) on glucose-induced insulin secretion.

In the perfused pancreas from normal SD rats, AD-4610 (0.01-0.1 mM) potentiated biphasic insulin secretion induced by 7.5 mM of glucose. The concentration-response curve of insulin secretion to glucose was shifted leftwards with AD-4610 (0.1 mM) without altering either the threshold concentration of glucose to induce insulin secretion or the maximal insulin response to glucose, indicating increased sensitivity of the pancreatic B-cells to glucose. On the other hand, AD-4610 was 10-fold less effective in altering insulin secretion induced by arginine and glyceraldehyde. The effect of AD-4610 on insulin secretion and glucose metabolism was compared with that of tolbutamide in vivo. AD-4610 (100 mg/kg) potentiated insulin secretion induced by an intravenous glucose load, and also accelerated glucose metabolism without altering basal insulin secretion in normal rats. On the other hand, tolbutamide (20 mg/kg) increased basal insulin secretion, but slightly decreased glucose-induced insulin secretion. In yellow KK mice with hyperglycemia, AD-4610 (10-100 mg/kg) had a dose-dependent hypoglycemic action, but tolbutamide did not. Thus, AD-4610 stimulated insulin secretion in a glucose-dependent fashion and enhanced glucose metabolism in vivo. These results suggest that AD-4610 selectively potentiates glucose-induced insulin secretion by increasing the sensitivity of pancreatic B-cells to glucose and may be useful for treating human NIDDM through a different mechanism than that of tolbutamide.

Animals↗
PubMed1987

Acute brain swelling during evacuation of subdural hematoma caused by delayed contralateral extradural hematoma: report of two cases.

Two patients experienced severe brain swelling during the evacuation of acute subdural hematomas. Postoperative computed tomographic (CT) scans revealed delayed extradural hematomas on the sides opposite the subdural hematomas. Extradural bleeding occurred in the area of the fractured skull. One patient improved neurologically after evacuation of the extradural hematoma, and the other was not operated because he was moribund. Drilling exploratory burr holes in the fractured area may have been a better strategy than awaiting a postoperative CT scan. The reduction of intracranial pressure after the removal of subdural hematoma was postulated to be the most important factor contributing to the formation of the extradural hematoma.

Acute Disease↗
PubMed1986

The antiobesity action of (S)-(+)-1-(4-chlorophenylthiomethyl)-N-methylethylamine fumarate (AO-124).

The antiobesity effects of (S)-(+)-1-(4-chlorophenylthiomethyl)-N-methylethylamine fumarate (AO-124) were examined in rats and dogs. AO-124 suppressed food intake dose dependently in normal, Zucker fatty and VMH-obese rats, and beagle dogs. Its anorectic activity was not altered by pretreatment with methysergide, a serotonin receptor blocker. AO-124 also reduced the hyperphagia induced by 2-deoxy-D-glucose but not that induced by insulin, noradrenaline or muscimol, suggesting that the anoretic mechanism of AO-124 may be implicated in a glucostatic regulatory system of feeding. In addition, AO-124 decreased insulin secretion in response to an oral, but not an intravenous, glucose load. Such a suppression in insulin secretion may be explained by slow absorption of glucose from the intestine: AO-124 delayed the gastric emptying time of glucose and inhibited the active transport of glucose as observed in the everted small intestine. Two week administration of AO-124 to Zucker fatty rats resulted in a significant reduction of plasma insulin levels, body weight gain, and body lipid without exerting any changes in body protein. These findings indicate that AO-124 may be useful as an antibesity agent on the basis of its unique mechanisms of action.

Animals↗
PubMed1986

[Cerebral venous thrombosis associated with the use of oral contraceptives].

The entity of cerebrovascular diseases associated with the use of oral contraceptives is well known but quite rare in Japan in contrast to Western countries. We recently encountered a 38 years old female with cerebral venous thrombosis considered to be caused by oral contraception. This patient took oral contraceptives for 17 days following therapeutic abortion, and was transferred to our hospital because of disturbed consciousness. CT scans disclosed a right temporo-occipital subcortical hemorrhagic infarction and bilateral thalamic infarction. Cerebral angiograms showed non-filling of cortical veins in the same area. The internal cerebral vein, vein of Galen and right transverse sinus were not visualized either. The hematoma and necrotic tissue were removed to avoid farther neurological deterioration. The brain was swollen and hyperemic, and thrombosed cortical veins were clearly recognized at operation. Twelve cases, including ours, of cerebrovascular diseases associated with oral contraception were reported up to now in Japan, and only 3 of them were diagnosed objectively as venous or sinus thrombosis. The average age of these 12 cases was 34 years old and many of them experienced abortion or therapeutic abortion. There was no relationship between the dose of estrogen and the onset of cerebrovascular diseases. We believe that the onset of this pathological state is based on gynecological hypercoagulable state, and the oral contraception may play a role of a trigger. Oral contraception should be contraindicated in patients with gynecological hypercoagulable state, hypertension and/or smoking habit.

Adult↗
PubMed1985

Traumatic aneurysm of the posterior inferior cerebellar artery caused by fracture of the clivus.

The authors present a case of traumatic aneurysm of the posterior inferior cerebellar artery produced by fracture of the clivus. Varieties of clival fractures reported in the literature are reviewed. Associated basilar or carotid arterial lesions have been reported, but traumatic aneurysm, so far as we are aware, has not. The authors emphasize the importance of a high index of suspicion of undetected traumatic intracranial aneurysm when an unusual amount of subarachnoid hemorrhage is noted on the initial computed tomographic scan, particularly if associated with displaced basal skull fracture.

Arteries↗
PubMed1984

The University of Toronto head injury treatment study: a prospective, randomized comparison of pentobarbital and mannitol.

Fifty-nine patients were treated in a prospective, randomized comparison of pentobarbital and mannitol for the control of intracranial hypertension resulting from head injury. Patients with elevated intracranial pressure (ICP) after evacuation of intracranial hematomas were randomized to one of two treatment groups; mannitol initially or pentobarbital initially, followed by the second drug as required by further elevation of ICP. Similarly, patients with raised ICP but without hematomas requiring evacuation were randomly assigned to two treatment groups in an identical paradigm. Those with ICP elevation and no hematoma treated with pentobarbital as initial therapy had a 77% mortality compared to a 41% mortality for those with mannitol as initial treatment. Patients with evacuated hematomas had mortalities of 40% and 43% (no significant difference) for pentobarbital and mannitol respectively. In both no-hematoma and hematoma streams pentobarbital was less effective than mannitol for control of raised ICP. Multivariable statistical analysis indicates that pentobarbital coma is not better than mannitol for the treatment of intracranial hypertension and may be harmful in no-hematoma patients with intracranial hypertension after head injury.

Adult↗