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Biomedical subjects

H Iwasa

Publications and source records attributed to H Iwasa.

At least 55 records · Page 3Linked to original sources
PubMed1994

[A case of venous angioma complicated by unruptured aneurysm with TIA as the initial manifestation].

Venous angioma is a relatively rare vascular malformation of the brain. It is usually asymptomatic and may be an incidental finding at autopsy or on cerebral angiography. We report a very rare case in which TIA-like attack occurred as the initial manifestation. A 59-year-old woman was hospitalized because of a TIA-like attack about 5 months after left putaminal bleeding. Detailed examination allowed us to make a diagnosis of subcortical venous angioma of the left parietal lobe and multiple cerebral aneurysms. The cerebral aneurysms were treated surgically. Since the angioma was localized in an eloquent area, radiotherapy was chosen first. Angioma giving rise to TIAs is very rare. The ischemia may have been caused by transient venous thrombosis or a steal phenomenon due to a decrease in blood circulation in the left cerebrum caused by the putaminal bleeding.

Brain Neoplasms↗
PubMed1991

Kindling-induced changes of [3H]GTP binding in the cerebral cortical membrane.

Specific [3H]GTP binding to the cerebral cortical membrane was examined in amygdaloid kindled rats. Membrane fractions of the cerebral cortex obtained from kindled rats and sham operated control were incubated with [3H]GTP and the data were analyzed by Scatchard plots. There were no differences in the Bmax and Kd values in basal (without any agonists) binding between kindled and control membranes. In the presence of isoprenaline, beta-agonist, Bmax values increased in the control, but did not increase in the kindled group. The kindling-induced abolishment of isoprenaline effect on Bmax of GTP binding persisted at least two weeks. Specific GTP binding activity of control membrane increased in the presence of carbachol, muscarinic agonist. A carbachol-induced increase in specific GTP binding activity also disappeared in the kindled group. These results suggest that a functional imbalance among various types of GTP binding proteins (Gs, Gi or Go) might be related to the acquisition of the epileptogenesis in the kindling model of epilepsy.

Amygdala↗
PubMed1991

Melatonin secretion in normal pressure hydrocephalus after cerebral aneurysm rupture--investigation before and after ventriculoperitoneal shunt.

Melatonin (MLT) secretion was examined in six normal pressure hydrocephalus (NPH) patients before and after ventriculoperitoneal (VP) shunt surgery. Ten healthy subjects were used as controls. Venous blood samples were taken daily at 2 p.m., 8 p.m., 2 a.m., and 8 a.m. Radioimmunoassay of MLT used a new specific antiserum and separation method achieving low cross-reactivity and high-efficiency MLT separation. Plasma levels in the control group at 2 p.m. and 2 a.m. were significantly different, showing diurnal rhythm (DR). The patients' MLT levels before VP shunt were significantly lower than control levels and the DR was absent. Postoperatively, the values were significantly different from preoperative values only at 2 a.m., but the DR reappeared. Thus, in NPH, VP shunt surgery improved the melatonin DR, probably through normalization of the dilated third ventricle.

Adolescent↗
PubMed1991

[Hyperkinésie volitionnelle following head injury].

A 13-year-old girl was struck by a car while riding her bicycle. She was comatose on her arrival at the hospital. Neurological examination revealed no focal sign except for right oculo-motor palsy. She became alert 15 days after the head injury when she first experienced a coarse tremor-like movement on the right arm. Neurological examination showed persistent oculo-motor palsy on the right side, decreased sensation of pain and touch on the left. There was no pyramidal deficit. Her gait and speech were normal and joint sensation was intact. A coarse tremor of the right arm was induced by volitional movements especially such as maintaining the arm in certain posture. It was not present at rest. Trajectory of finger-to-nose test was fairly well. However, the tremor became worse when the patient kept her finger near the target. Occasionally myoclonic-jerk and movement oppositionniste were mixed. Superficial EMG recordings of the tremor revealed 4 c/s rhythmic reciprocal grouping discharges, alternating flexor and extensor muscles. From these features, the abnormal movement should better be called tremor type of hyperkinésie volitionnelle (HV). The HV subsided spontaneously 4 months later. MRI of T2-weighted image showed high-intensity areas corresponding anatomically to the caudal part of right red nucleus and the right superior cerebellar peduncle just before its decussation. It is widely believed that lesions in cerebellar outflow pathway (i.e. dentate, red nucleus and thalamus) can cause HV.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1990

Protective effect of vitamin E on fetal distress induced by ischemia of the uteroplacental system in pregnant rats.

The effect of dietary vitamin E on the fetal ischemic distress induced by clamping the uterotubal vessels of pregnant rats was studied. The fetal heart rate was measured by the pulsed doppler technique as an index of fetal distress induced by ischemia. On reperfusion after clamping the vessels for 9 min, the decreased fetal heart rate was restored to normal rapidly and completely in the E-supplemented group, but slowly and incompletely in the E-deficient and control groups. On reperfusion after ischemia, the amounts of lipid peroxides, measured as thiobarbituric acid (TBA)-reactive substances, were greatly increased in the fetal brain and liver and in the placenta of in the E-deficient and control groups, but not in the E-supplemented group. The vitamin E concentrations in fetal tissues were less than 10% of those in the maternal tissues. Significant differences were found in the vitamin E concentrations in the maternal serum and liver in the three groups of rats given diet containing different amounts of vitamin E for 2 weeks. No significant differences were found between the vitamin E-deficient and control groups in the levels of vitamin E in the fetal brain and liver and the placenta, but these levels were significantly lower than those in the E-supplemented group.

Animals↗
PubMed1990

Right hand agraphia and left hand apraxia following callosal damage in a right-hander.

A right-handed Japanese man showed agraphia more marked with the right hand, apraxia confined to the left hand, and right ear extinction on dichotic listening, following damage to the anterior two-thirds of the corpus callosum, the rostral and lower parts of the right medial frontal lobe and a small portion of the left medial frontal lobe. The symptoms were attributed to hemispheric disconnection, on the assumption that the right hemisphere was dominant for language and the left for limb praxis. This case provides good evidence for dissociated lateralization of language and limb praxis in some right-handed individuals. The study of writing performance suggested the following hypotheses: (1) motor engrams for limb praxis and writing may be dissociated, and (2) motor engrams for writing Kana (phonogram) and Kanji (ideogram) letters are represented on both hemispheres, although the hemisphere nondominant for language seems unable to combine graphemes into a correct meaningful sequence.

Agraphia↗
PubMed1990

Diagonistic dyspraxia: case report and movement-related potentials.

We report unusual motor behavior of the left hand dissociated from conscious volition in a 51-year-old right-handed man. This patient had sustained damage to the anterior two-thirds of the corpus callosum, the rostral and lower parts of the right medial frontal lobe, and a small portion of the left medial frontal lobe. He subsequently showed 4 types of abnormal motor behavior in the left hand that were triggered by voluntary activities of the right hand: symmetric or antagonistic left hand movements; irrelevant movements of the left hand to the right hand; and a tendency to close the fingers of the left hand into a fist. Recordings of movement-related potentials revealed a marked attenuation of the Bereitschaftspotential (BP) over the right hemisphere observed only when the patient initiated voluntary activity with the right hand. Since the BP is believed to represent a cerebral cortical activity preparatory for voluntary movement, we infer that the level of dysfunction in this patient is at the motor preparatory level caused by a disconnection of the right hemisphere from the left.

Cerebral Hemorrhage↗
PubMed1990

[Melatonin secretion in intracranial tumor].

UNLABELLED: The secretion of melatonin (MLT) was examined in 6 ICT patients, 2 men and 4 women, who showed marked midline shift of CT scan findings with intracranial hypertension signs (headache, nausea, vomiting). Their ages ranged from 22 to 40 years. The controls, 6 healthy men and 4 healthy women (follicular stage) were aged from 18 to 35. With the subject recumbent, blood was drawn at 14, 20, 02 and 08 hour (Lights out, 9 pm; sunrise, 6 am). After separation of plasma by centrifugation, MLT was extracted by SEP-PAK C18 cartridge and determined by radioimmunoassay (RIA). ( METHOD: The extracted MLT, the antiserum and the 3H-MLT were incubated overnight at 4 degrees C, the antibody-combined and free 3H-MLT were separated using ammonium sulfate, and the radioactivity of the precipitate containing combined 3H-MLT was measured by liquid scintillation.) Plasma MLT concentrations of controls were 42.5 +/- 7.0 (Mean +/- SEM) pg/ml at 14 hr, 50.9 +/- 8.2 pg/ml at 20 hr, 165.1 +/- 22.7 pg/ml at 02 hr, and 49.1 +/- 5.4 pg/ml at 08 hr. The value of 14 hr. significantly differed from 02 hr, (P less than 0.01) showing a diurnal rhythm. The patients' MLT levels (pg/ml) were 19.8 +/- 6.2 at 14 hr, 15.9 +/- 5.2 at 20 hr, 52.0 +/- 17.2 at 02 hr, and 20.3 +/- 3.5 at 08 hr. These values were significantly lower than in controls (P less than 0.01) except at 14 hr. (P less than 0.05), showing no diurnal rhythm except 2 cases. In conclusion, in ICT with midline shift of CT scan melatonin secretion was inhibited and diurnal rhythm disappeared in four cases (67%).

Adolescent↗
PubMed1990

[Effect of dietary level of vitamin E on protection of fetus against ischemic distress induced by clamping the uterotubal vessels of pregnant rats].

The effect of dietary vitamin E on the fetal ischemic distress induced by clamping the uterotubal vessels of pregnant rats was studied. The fetal heart rate was measured by the pulsed doppler technique as an index of fetal distress induced by ischemia. On reperfusion after clamping the vessels for 9 min., the decreased fetal heart rate was restored to normal rapidly and completely in the E-supplemented group, but slowly and incompletely in the E-deficient and control groups. On reperfusion after ischemia, the amounts of lipid peroxides, measured as thiobarbituric acid (TBA)-reactive substances, were greatly increased in the fetal brain and liver and in the placenta in the E-deficient and control groups, but not in the E-supplemented group. The vitamin E concentrations in fetal tissues were less than 10% of those in the maternal tissues. But a diet containing a large amount of vitamin E induced significantly increased concentrations of vitamin E in fetal brain and liver. These results suggest that vitamin E may have a protective effect on fetal distress by decreasing lipid peroxides.

Animals↗
PubMed1989

Local cerebral glucose utilization in the postictal phase of amygdaloid kindled rats.

Local cerebral glucose utilization was measured by means of the quantitative autoradiographic 2-[14C]deoxyglucose method during the postictal phase of various seizure stages of amygdaloid kindling in conscious rats. The partially kindled animals exhibited a partial seizure such as chewing and/or head nodding, and the fully kindled animals, a generalized tonic-clonic convulsion. The control animals were implanted with an electrode, but not electrically stimulated. Cerebral glucose utilization of the fully kindled animals was deeply depressed in the postictal phase as compared to the control, and that of the partially kindled animals was moderately decreased. The side-to-side differences of cerebral glucose utilization were observed only in the partially kindled group in which glucose utilization was more depressed on the side of stimulation. Among the structures with depressed glucose utilization, only one structure, the interpeduncular nucleus, showed a relative increase in glucose utilization during the postictal phase of the kindled groups. As the postictal phase has been considered as a period of inhibition, these results may indicate that the neural networks linking the interpeduncular nucleus play an active role in the mechanisms of termination of a seizure and postictal refractoriness.

Amygdala↗
PubMed1988

["One-knot" microvascular anastomosis using glutide as an external splint--experimental arterio-arterial anastomosis in rats].

Experimental microvascular anastomosis using a glutide copolymer (lactide: glycolide = 80: 20) as an external splint was undertaken in rats between the left and the right carotid arteries. Both arteries were dissected free over a 1-cm length, the left carotid artery was transected at the cranial end, and the right carotid artery was cut at the caudal end. The left carotid artery was then introduced into a glutide pipe-splint. The arterial wall was turned back 180 degrees over the edge of the splint. The reflected part of the artery and the glutide were covered with the freed-up right carotid artery. One stitch was made around the two arteries and the glutide in a manner similar to that of binding a barrel with steel wire. The "One-knot anastomosis" was then complete. We call this type of anastomosis "antegrade anastomosis". If, on the other hand, the right carotid artery is introduced into the pipe, turned back at the edge of the glutide, covered with the left carotid artery and secured with one stitch, the technique is known as "retrograde anastomosis". The patency rates of the resulting vessels were as follows: antegrade anastomosis, 83% (15/18); and retrograde anastomosis, 92% (23/25); so that the average patency rate was 88% (38/43). We measured the anastomosing time that is the time between the transection of one of the two arteries and the completion of the anastomosis. The average anastomosing time was 21 minutes for antegrade anastomosis and 14 minutes for retrograde anastomosis. But the 'pure anastomosing time' (the time taken to connect the two already prepared arteries) was 2-3 minutes. We believe that one-knot anastomosis technique for future clinical application is promising.

Anastomosis, Surgical↗
PubMed1987

One-knot microvascular anastomosis. An experimental study in rats.

Experimental microvascular anastomosis using a glutide copolymer (lactide:glycolide, 80:20) as an external splint was undertaken in 33 rats between the carotid artery and the jugular vein. Both vessels were dissected free over a 1-cm length and cut at the cranial end of the dissected part. The carotid artery was then introduced into a glutide pipe-splint. The arterial wall was turned 180 degrees over the edge of the splint. This reflected artery wall and the glutide were covered by the freed-up jugular vein. One stitch was made around the vein, the artery, and the glutide in a manner similar to binding steel wire over a barrel. Thus, the "one-knot anastomosis" was completed. The patency rate at the anastomosed site was 100%, confirmed by angiography in 30 rats and by direct surgery in three. The time required to produce the anastomosis was between 5 and 7 minutes. Light microscopic observation showed that there was no obstruction by thrombus formation at 1 and 5 weeks after the anastomotic surgery. This technique may be clinically applicable for extracranial-intracranial bypass surgery, reconstruction of venous sinuses, and other vascular procedures.

Animals↗