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Biomedical subjects

K Kohshi

Publications and source records attributed to K Kohshi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Apparent diffusion coefficient on rat brain and nerves intoxicated with methylmercury.

The effects of methylmercury chloride (MMC) on the degenerative changes in rat brain and cranial nerves were studied. Twelve Wistar rats were divided into two equal groups. The rat model of methylmercury intoxication (MMC group) was made by subcutaneously administering 10 mg mercury/g body weight daily for 7 days. Control group rats were infused with the same amount of normal saline during this period. Magnetic resonance imaging (MRI) measurements were performed before and 14 days after the first MMC administration, using a 4.7-T MR system. No significant focal changes were observed on T1- and T2-weighted MR images regarding the internal structures of the brains of the MMC-intoxicated rats, atrophy of the cerebellum, and dilatation of the arachnoid space around the brain stem of MMC-treated rats, but were demonstrated without edematous change. The apparent diffusion coefficients (ADC) of the cortex, caudate-putamen, and trigeminal nerve were not significantly different between the MMC-treated and control rats. However, the ADC parallel to the optic nerves were significantly increased in the MMC group, in contrast to the unchanged ADC perpendicular to the optic nerves. An electron microscopy study revealed a marked decrease of microtubules and moderate decrease of neurofilaments in the axons of myelinated fibers of optic nerves of the MMC-treated rats. We have thus demonstrated a disturbance in the integrity of microtubules and neurofilaments as a toxic action of MMC in the rat nervous system in vivo, particularly in the optic nerves. The use of ADC values calculated by diffusion-weighted MRI is a promising approach for the evaluation of changes in brains and nerves in methylmercury intoxication research.

Animals↗
PubMed1999

Effects of radiotherapy after hyperbaric oxygenation on malignant gliomas.

The purpose of this non-randomized trial was to evaluate the efficacy of radiotherapy combined with hyperbaric oxygen (HBO) in patients with malignant glioma. Between 1987 and 1997, 29 patients in whom computerized tomography (CT) or magnetic resonance imaging (MRI) scans showed post-operative residual tumours were locally irradiated with nitrosourea-based chemotherapy. Treatments were consecutively combined with HBO at two institutions since 1991 and 1993. Fifteen patients were irradiated daily after HBO, and the periods of time from decompression to irradiation were within 15 and 30 min in 11 and four patients respectively. Fourteen other patients were treated without HBO. Tumour responses were assessed by CT or MRI scans and survival times were compared between the treated groups. In the HBO group, 11 of 15 patients (73%) showed > or = 50% tumour regression. All responders were irradiated within 15 min after decompression. In the non-HBO group, four of 14 patients (29%) showed tumour regression. The median survivals in patients with and without HBO were 24 and 12 months, respectively, and were significantly different (P < 0.05). No serious side-effects were observed in the HBO patients. In conclusion, irradiation after HBO seems to be a useful form of treatment for malignant gliomas, but irradiation should be administered immediately after decompression.

Brain Neoplasms↗
PubMed1999

Treatment of advanced atrioventricular block with beta-adrenergic blockade therapy.

A 26-year old woman, who experienced syncope associated with advanced AV block, was referred for further evaluation. Electrophysiological study showed normal SA and AV node physiology. Syncope associated with advanced AV block on the electrocardiogram was induced by head-up tilt test. Oral propranolol therapy completely prevented the AV block and syncope induced by head-up tilt. The physician should be aware of advanced AV block associated with neurocardiogenic syncope, especially before permanent - pacemaker therapy is considered. The head-up tilt test is a useful diagnostic tool for an etiology of paroxysmal AV block.

Adrenergic beta-Antagonists↗
PubMed1998

Pirmenol hydrochloride-induced QT prolongation and T wave inversion on electrocardiogram during treatment for symptomatic atrial fibrillation.

Pirmenol hydrochloride is a new orally effective, long-acting antiarrhythmic agent currently used in patients with supraventricular and ventricular tachyarrhythmias. We report on a 56-year-old female who exhibited drug refractory paroxysmal atrial fibrillation, in which marked prolongation of the QT interval and T wave inversion on electrocardiogram was demonstrated reproducibly shortly after the administration of oral pirmenol therapy. The plasma concentration of pirmenol was at a subtherapeutic level and the lymphocyte stimulation test was positive in this patient. Thus, an immunological mechanism might be involved in the mechanism of pirmenol-induced QT prolongation and T wave inversion on the electrocardiogram.

Anti-Arrhythmia Agents↗
PubMed1998

Moyamoya disease of adult onset brain stem haemorrhage associated with bilateral occlusion of the vertebral arteries--case report.

An unusual and first case of moyamoya disease of adult onset brain stem haemorrhage associated with occlusion of both vertebral arteries is reported. A 30-year-old man suddenly suffered from dyspnea, dysphagia, and left-sided hemisensory disturbance. Computed tomography and magnetic resonance imaging revealed a fresh haematoma in the left medulla oblongata and various-sized old infarcts in both parietal lobes. Cerebral angiograms disclosed occlusion of the bilateral internal carotid arteries on both sides at their intracranial portion, accompanied with the developed basal moyamoya vessels. The right vertebral artery occluded at its V2-V3 segment, in which the posterior inferior cerebellar artery was opacified via the posterior spinal artery, and the basilar artery was filled from the anterior spinal artery. The left vertebral artery was also occluded at the craniovertebral junction (V4) with collateral flow. Only one case of moyamoya disease associated with bilateral occlusion of the vertebral artery has been reported previously, and a haemorrhage into the medulla oblongata in moyamoya disease has never been described.

Adult↗
PubMed1998

Possible involvement of cerebral hypoperfusion as trigger of neurally-mediated vasovagal syncope.

It is well known that some patients with neurally mediated syncope have a feeling of aura before the onset of syncope. A case is reported in which cerebral dysfunction recorded by EEG was present before the onset of a vasovagal reaction. The vasovagal reaction, bradycardia and/or asystole, was preceded by abnormal EEG findings when the patient complained of feeling a headache, photophobia, and nausea. These findings suggest that cerebral hypoperfusion, such as with cerebral vasospasms, before the onset of bradycardia might be involved in the mechanism of neurally mediated syncope in patients with an aura.

Administration, Oral↗
PubMed1998

Multiple cerebral infarction in Japanese breath-hold divers: two case reports.

We report on two Japanese breath-hold divers (ama) who developed neurological disturbances following more than 3 hours of consecutive dives to 15-25 meters of seawater. Their magnetic resonance images of the brain showed multiple cerebral infarcts which were consistent with their neurological symptoms. The cerebral lesions seem to have been caused by repetitive breath-hold dives for extended periods of time. Immediate recompression is required when neurological symptoms develop after such dives.

Adult↗
PubMed1997

Exercise-induced neurally mediated syncope.

We describe a 16-year-old female referred for evaluation of syncope associated with competitive long distance running. She had experienced 4 episodes of syncope during competitive long distance racing. The syncope associated with marked bradycardia and asystole was demonstrated by head-up tilt testing without isoproterenol infusion. Oral propranolol therapy failed to prevent the syncope. Oral disopyramide therapy, however, prevented the syncope induced by both head-up tilt testing and competitive long distance racing. Caution should be urged in evaluating athletes with syncope, especially in the pediatric age group, because the cause of the syncope may result from life-threatening disorders such as cardiomyopathy, long QT syndrome, or exercise-induced arrhythmias. The head-up tilt test is an important diagnostic tool for the evaluation of exercise-associated syncope.

Adolescent↗
PubMed1997

Brain pH responses to acetazolamide and hypercapnia in cats.

The involvement of increased brain tissue CO2 tension in acetazolamide-induced brain acidosis was investigated by comparing the brain pH response to acetazolamide with that to hypercapnia. CO2 and pH sensors were placed bilaterally into cerebral white matter to 15 mm depth in cats. Group 1 cats (n = 9) breathed spontaneously, and in situ brain tissue PCO2, and pH (PbCO2 and pHb) were measured after intravenous acetazolamide administration (20 mg/kg). Group 2 cats (n = 9) were paralyzed and ventilated mechanically, and the changes of pHb were investigated by adjusting the ventilation to maintain the same Pbco2 values as in the acetazolamide-treated group. PbCO2 changes were not significantly different between the two groups. However, pHb responses were quite different: the fall in pHb was progressive in Group 1 but transient in Group 2. Brain acidosis after acetazolamide administration is not due to the rise in brain tissue CO2 tension.

Acetazolamide↗
PubMed1996

Radiotherapy after hyperbaric oxygenation for malignant gliomas: a pilot study.

The results of radiotherapy combined with hyperbaric oxygen in 9 patients with malignant glioma were compared with those of radiotherapy without hyperbaric O2 in 12 patients. This is the first report of a pilot study of irradiation immediately after exposure to hyperbaric O2 in humans. All patients receiving this treatment showed more than 50% regression of the tumor, and in 4 of them, the tumors disappeared completely. Only 4 out of 12 patients without hyperbaric O2 showed decreases in tumor size, and all 12 patients died within 36 months. So far, this new regimen seems to be a useful form of radiotherapy for malignant gliomas.

Adolescent↗
PubMed1994

In situ arterial and brain tissue PCO2 responses to acetazolamide in cats.

We have studied how in situ arterial (PaCO2) and brain tissue PCO2 (PbCO2) responses to acetazolamide (AZ) are affected by respiratory patterns. Sixteen cats were anesthetized with ketamine. Group 1 cats (n = 7) breathed air spontaneously. Group 2 cats (n = 6) were paralyzed and ventilated mechanically to maintain PaCO2 at 37 +/- 1 Torr before AZ administration; the respiratory rate and depth did not change during the course of measurements. Two CO2 sensors to measure in situ PaCO2 and PbCO2 continuously were used. One was placed through a burr hole into the cerebral white matter 15 mm in depth, and another was inserted into the femoral artery. After intravenous administration of AZ (20 mg/kg), PaCO2 decreased, after a significant transient rise, and then returned gradually to the baseline in group 1, but it increased gradually and reached a new steady state in group 2. PbCO2 and the PbCO2-PaCO2 gradient increased remarkably in the two groups immediately after administration. We conclude that AZ resulted in a large increase in both PbCO2 and the PbCO2-PaCO2 gradient and that there are two distinct in situ PaCO2 responses to AZ in spontaneously breathing vs. mechanically ventilated animals. The mechanisms for these observations are discussed.

Acetazolamide↗
PubMed1993

Hyperbaric oxygen therapy adjunctive to mild hypertensive hypervolemia for symptomatic vasospasm.

The efficacy of hyperbaric oxygen (HBO) therapy was evaluated retrospectively in 43 patients who developed symptomatic vasospasm following acute aneurysm surgery. HBO therapy was given as an adjunct to mild hypertensive hypervolemia in 24 patients. Before HBO therapy, 17 patients had no infarct (Group 1), and seven had infarcts (Group 2) caused by vasospasm. A further 19 patients received mild hypertensive hypervolemia alone (Group 3). Cerebral infarcts developed in four Group 1 and 12 Group 3 patients. A good outcome 1 month after surgery was achieved by 13 Group 1 (76%), one Group 2, and seven Group 3 patients (37%). Fifteen of the 24 patients who received HBO therapy responded to HBO exposure, and 12 responding patients (80%) had a good outcome. During HBO exposure, electroencephalographic improvements were all accompanied by neurological improvements. There were no complications related to HBO therapy. HBO therapy adjunctive to mild hypertensive hypervolemia is helpful in preventing cerebral infarction associated with symptomatic vasospasm.

Adult↗
PubMed1992

[Gliosarcoma associated with von Recklinghausen's disease: a case report].

A very rare case of gliosarcoma with von Recklinghausen's disease is presented. A 51-year-old man was admitted to our hospital in March 1990, because of a 2-month history of personality change and left hemiparesis. Multiple neurofibroma over his whole body with many café au lait spots had been present since early childhood. His mother, brothers and children also had café au lait spots. Neurological examination on admission revealed memory disturbance, left homonymous hemianopsia and left hemiparesis. CT scan showed a large lobular lesion in the right temporoparietal region. The medial hypodense part was sharply demarcated by a ring-like enhancement, while the lateral isodense part was homogeneously enhanced. MRI showed a sharply demarcated high intensity lesion with Gd-EDTA enhancement corresponding to the enhanced area on CT. Faint staining on angiography revealed that the blood supply to the tumor was predominantly dural. At surgery, the tumor was solid and highly vascular, and adhered tightly to the dura. The superficial part of the tumor was well demarcated from the brain tissue, but the demarcation was obscure in the deeper part. Histological findings showed two clearly defined neoplastic components: a gliomatous component that was stained for GFAP, and a sarcomatous component that had spindle-shaped nuclei and eosinophilic fibers. The patient underwent radiotherapy after surgery, but the tumor soon recurred. A second operation was performed, but the tumor had infiltrated into the scalp and he died 10 months after the first operation. This combination is very rare and has not been reported previously.

Brain Neoplasms↗
PubMed1991

Post-operative paraplegia with spinal myoclonus possibly caused by epidural anaesthesia: case report.

We report a patient who developed paraplegia following percutaneous nephrolithotresis of the left kidney under epidural anaesthesia. The cause of the paraplegia was unknown, but occlusion of the anterior spinal artery or central arteries and arachnoiditis, possibly due to the epidural anaesthesia, may have taken part in the onset and progression of the paralysis. The patient had spinal myoclonus corresponding to the spinal levels where myelomalacia was found by magnetic resonance (MR) imaging.

Anesthesia, Epidural↗
PubMed1991

Intracranial pressure responses during hyperbaric oxygen therapy.

The responses of intracranial pressure (ICP) to hyperbaric oxygen (HBO) therapy and arterial gas pressures were investigated. ICP was measured through a ventricular or spinal drainage catheter in patients with brain tumor or cerebrovascular disease. Changes in ICP, heart rate (HR), arterial blood pressure (ABP), and transcutaneous partial pressure of carbon dioxide (PtcCO2) or oxygen (PtcO2) were recorded continuously during air or 100% O2 breathing at 1 and 2.5 atmospheres absolute (ATA). HR and PtcCO2 decreased and mean ABP was unchanged during HBO inhalation. ICP was reduced at the beginning and tended to increase gradually during HBO inhalation. The change from air to O2 without altering respiratory frequency and volume caused a gradual increase of ICP and PtcCO2 with a transient ICP reduction in an artificially respirated patient. Intentionally reduced respiration to maintain PtcCO2 at the value at 2.5 ATA with air caused the ICP to return to near the value at 2.5 ATA with air even during HBO inhalation. These findings suggest that reduced ICP is initially due to direct cerebral vasoconstriction caused by hyperoxia and is maintained mainly by induced hypocapnia during HBO inhalation. Care is required when giving HBO therapy to patients with a high ICP and/or who are respirated artificially.

Adult↗
PubMed1990

Human auditory brain stem response during induced hyperthermia.

A continuous monitoring of auditory brain stem response (ABR) and esophageal (Tes) and rectal temperatures (Tre) were recorded in male undergraduate subjects to investigate a relationship between the interpeak latencies (IPLs) and core temperature. The average change of Tes (36.8-39.5 degrees C) was achieved by immersing the subjects in a temperature-controlled water bath (30-42 degrees C). The IPLs became shorter with the rise in body temperature and were correlated with both Tes and Tre. The average slopes for IPL(I-III) and IPL(I-V) were significantly higher than those for IPL(III-V). The present study of humans indicated that changes of IPL(I-III) and IPL(I-V) were 0.11 and 0.16 ms, respectively, per 1 degree C change in core temperature during induced hyperthermia.

Adult↗