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Biomedical subjects

Y Hosobuchi

Publications and source records attributed to Y Hosobuchi.

At least 55 records · Page 3Linked to original sources
PubMed1983

Studies of nuclear magnetic resonance imaging and regional cerebral glucose metabolism in acute cerebral ischemia: possible mechanism of opiate antagonist therapeutic activity.

Using unilateral carotid artery ligation in the gerbil as a model of cerebral ischemia, both nuclear magnetic resonance (NMR) imaging and a newly developed double-label autoradiographic technique have been employed to investigate the physiologic mechanism of opiate action during cerebral ischemia. While several parameters of the NMR image have been demonstrated to reflect focal cerebral ischemic lesions, neither 2 mg/kg naloxone nor 10 mg/kg morphine sulfate had an effect on any of the parameters of the NMR image at any time point during the 24 hr experiment. While no consistent changes could be measured in the metabolic rate immediately about the ischemic region, results from double-label 2-deoxyglucose autoradiographic studies indicate that there are marked focal increases in metabolic rate in several subcortical nuclei bilaterally following the administration of naloxone. While no significant change was noted in the thalamus or arcuate nucleus, naloxone produced a significant elevation in glucose metabolic rate in the substantia nigra, periaqueductal grey and the red nucleus. The significance of these effects are discussed and a mechanism for the beneficial effect of opiate antagonists on neurologic deficit following ischemic cerebral lesions is proposed.

Animals↗
PubMed1983

Combined electrical stimulation of the periaqueductal gray matter and sensory thalamus.

11 patients with chronic intractable pain of at least 3 years' duration underwent a morphine infusion test, the results of which suggested a syndrome of superimposed somatogenic and neurogenic pain components. They then underwent stereotactic implantation of a dual-channel brain stimulation system with two brain electrodes, one in the left periaqueductal gray matter (PAG) and the other in the sensory thalamus contralateral to the neurogenic pain. Using this system, all patients have obtained excellent simultaneous relief of both pain components (follow-up 12-36 months). The findings support a notion of two separate sensory modulating systems. They indicate that combined electrical stimulation of the PAG and sensory thalamus is a technically feasible and clinically satisfactory modality for the control of pain in humans, and they appear to indicate that better pain control is obtained by continuous, cycled stimulation of the PAG than by the conventional mode of stimulation.

Electric Stimulation Therapy↗
PubMed1982

Reversal of neurological deficits by opiate antagonist naloxone after cerebral ischemia in animals and humans.

Stroke induced by a carotid occlusion in gerbils was reversed by intraperitoneal (i.p.) injection of naloxone (1 mg/kg) for up to 30 min. Placebo-treated stroked gerbils died in 48 hr; 40% of gerbils implanted with 10 mg naloxone pellets survived over 2 weeks without neurologic deficit. Intravenous (i.v.) injection of naloxone produced the same transient reversal of hemiplegia in 2 patients with neurologic deficit from cerebral ischemia. These findings suggest the involvement of endorphins and opiate receptors in the pathophysiology of stroke, and suggest the possible clinical use of opiate antagonists in humans in the acute phase of stroke.

Animals↗
PubMed1981

Stereotactic interstitial irradiation for the treatment of brain tumors.

Eighteen patients harboring untreated, inaccessible, slow-growing tumors or recurrent malignant primary or metastatic brain tumors were treated by the stereotactic implantation of permanent or removable radioactive seeds (192Ir, 198Au, 125I). Seed strength was selected to deliver 10,000-12,000 rad to the tumor's periphery for 192Ir, 9000-12,000 rad for 125I, and 4000-7500 rad for 198Au. Three of six patients implanted with 192Ir seeds had objective responses for 2, 8, and 12 months, and a fourth stabilized for 20 months. Five of 9 patients treated with 198Au were evaluable, three of whom responded for 3, 5, and 20 months. Two patients who received 125I have been evaluated to date and are early failures. Two patients who received 125I have been evaluated to date and are early failures. Because of its higher dose rate 198Au is superior for the faster-growing malignant tumors; but because 125I is easier to shield, 125I seeds with greater activity are being developed for evaluation.

Brachytherapy↗
PubMed1980

The current status of analgesic brain stimulation.

This paper reviews the author's nine years of experience in analgesic brain stimulation. During this time, of 22 patients with pain of peripheral origin who were treated with periaqueductal gray (PAG), stimulation 16 achieved successful control of pain. Of 40 patients who presented with deafferentation pain, 16 were able to control their dysesthesia by brain stimulation of the subcortical somatosensory region alone; follow-up was over a long period. The mechanism of deafferentation pain is poorly understood and the effectiveness of subcortical somatosensory electrical stimulation to relieve such pain is based on empirical observation. The analgesia produced by PAG stimulation appears to be mediated by the release of beta-endorphin from the anterior hypothalamus. The released beta-endorphin binds to the opiate receptors in the PAG and activates the descending pain-inhibitory pathway. However, the repetitive stimulation of this serotonergic system produces tolerance to its analgesic effect, due to a decreased rate of serotonin turnover. Loading of the serotonin precursor by dietary supplementation of the essential amino acid L-tryptophan reverses this tolerance.

Analgesia↗
PubMed1980

Brain stem auditory evoked response and brain stem compression.

For the study of brain stem auditory evoked response (BAER) changes due to acutely expanding mass lesions, posterior fossa balloon catheters were inflated slowly in anesthetized cats while supratentorial and infratentorial intracranial pressure and vital signs were monitored. Reliable changes in BAER occurred before the Cushing response and were reversible by balloon deflation. Because BAER changes precede the agonal changes of the Cushing response, serial BAER recording in patients with known or suspected posterior fossa masses may be useful in the management of these lesions.

Animals↗
PubMed1980

Interstitial brachytherapy of primary brain tumors. Preliminary report.

Ten patients harboring inaccessible, slow-growing or recurrent malignant primary brain tumors were treated by the stereotaxic implantation of a radionuclide seed -- iridium-192 (192Ir) or gold-198 (198Au) -- either permanent or removable. The strength for 192Ir seeds was selected to deliver 10,000 to 12,000 rads to the periphery of the tumor, and that for 198Au seeds to deliver 4000 to 7500 rads. Three of the six patients treated with 192Ir showed objective responses lasting 8, 11, and 12 months, respectively; and one patient's disease stabilized for 18 months. Three of the four treated with 198Au showed responses lasting 5 months, 6 months, and 2 years, respectively. Because of the higher dose-rate attainable with 198Au, removable implants of this material are more effective against the faster-growing malignant tumors. Another radionuclide, iodine-125 (125I), is now being tested against brain tumors. The radioactivity of 125I is high; but because its gamma emission is less energetic by a factor of 10 than that of 198Au or 192Ir, its radiation field is concentrated within a radius of 2.5 cm or less. This low-energy gamma emission also makes it easier to protect medical personnel and the patients' families against the nuclide when 125I is used.

Adult↗
PubMed1979

Stimulation of human periaqueductal gray for pain relief increases immunoreactive beta-endorphin in ventricular fluid.

Immunoreactive beta-endorphin was measured in the ventricular fluid of six patients with chronic pain. Stimulation of the periaqueductal gray matter in three patients with pain of peripheral origin resulted in significant increases (50 to 300 percent) in the concentration of ventricular immunoreactive beta-endorphin. In three other patients suffering deafferentation dysesthesia, stimulation of the posterior limb of the internal capsule did not alter the concentration of this peptide. These results provide evidence of the release of human immunoreactive beta-endorphin in vivo and suggest that naloxone-reversible pain relief achieved by stimulation of the periaqueductal gray matter may be in part mediated by the activation of beta-endorphin-rich diencephalic areas.

Aged↗
PubMed1979

Direct surgical treatment of giant intracranial aneurysms.

The author has operated on 40 patients with giant intracranial aneurysms, using various surgical approaches. Giant aneurysms predominated in females (3:1) and were most common in the age group 30 to 60 years. Patients presented with subarachnoid hemorrhage (17), visual disturbance (18), chronic headache (14), transient or progressive hemispheric deficit (6), seizure (2), dementia (2), and cerebrospinal fluid rhinorrhea (1). Giant aneurysms were located at the carotid artery (25), the basovertebral artery (8), the anterior communicating artery (5), and the middle cerebral artery (2). Eight of 40 patients had one or more other aneurysms and/or associated arteriovenous malformations. Aneurysms were treated with intramural thrombosis (21), neck occlusion (7), trapping (10), proximal parent artery ligation (1), and aneurysmorrhaphy (1). After as much as 8 years of follow-up, 32 patients (80%) showed complete or marked improvement in signs and symptoms; two patients (5%) had a poor recovery. There were six surgical mortalities (15%). Giant aneurysms can be treated with respectable results if the surgeon selects the technique best suited to the particular aneurysm. In general, neck occlusion, trapping, and aneurysmorrhaphy are best for giant aneurysms of the anterior circulation, and intramural thrombosis is best for those of the posterior circulation. Extra- and intracranial vascular anastomotic techniques are also of value. For success, a flexible approach is essential.

Adult↗