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Biomedical subjects

I Shimoyama

Publications and source records attributed to I Shimoyama.

At least 37 records · Page 2Linked to original sources
PubMed1995

Eclampsia-like seizures and electroencephalographic changes in pregnant rabbits with endothelin-1 injections.

To examine the possible role of endothelin and vasospasm in eclamptic seizures, we studied and analyzed the electroencephalograms (EEG) of endothelin-1 (ET-1)-treated pregnant, nonpregnant and sham control (dextrose-treated) rabbits. After multiple intravenous bolus injections of ET-1 (500 pmol/kg) or 5% dextrose in the rabbits, we recorded EEG directly from the brain cortex and analyzed by Fast Fourier Transform (FFT). Water content was measured in the brain of all groups (n = 7). Repeated seizures occurred in all of the pregnant and 2 of the nonpregnant rabbits by variable doses of ET-1. FFT analysis showed remarkable changes in frequency and power arrays characterized by mild to severe form of dysrhythmia, high-voltage spikes, high-voltage fast and slow waves after ET-1 injections. Water content was increased in brain mass in ET-1-treated rabbits (p = 0.001) suggesting an ET-1-induced edema. Histologically we confirmed that ET-1 caused ischemic changes in brain tissues. However, ET-1 induced more pronounced changes in behavior, EEG, brain edema or ischemia in pregnant than in nonpregnant groups. The injections of exogenous ET-1 into the brain substances were strongly suggested by immunohistochemical study with polyclonal antiendothelin antibody in brain tissue sections. Therefore, we assume that endothelin along with other vasoactive substances causes acute cerebral vasospasm and ischemia inducing EEG changes leading to ultimate clinical convulsions in eclampsia.

Animals↗
PubMed1994

Correlations between platelet aggregation, fibrinolysis, peripheral and central serotonergic measures in subhuman primates.

We have studied the relationships between whole blood and plasma serotonin (5-hydroxytryptamine, 5-HT), its major metabolite 5-hydroxyindoleacetic acid (5-HIAA) and serum lipids, platelet aggregation in the whole blood and in the platelet-rich plasma (PRP), and some fibrinolytic parameters in monkeys. Plasma 5-HT was found to be positively related to 5-HT- and ADP-induced platelet aggregation, tissue plasminogen activator (tPA) activity, serum cholesterol and LDL-cholesterol, whereas 5-HT in cerebrospinal fluid correlated inversely with serum cholesterol. Plasminogen activator inhibitor (PAI) activity was positively related to LDL. Euglobulin clot lysis time was related to both tPA and PAI activities. The significance of these findings and the possible role of 5-HT in atherogenesis and hemostasis are discussed.

Animals↗
PubMed1994

Subarachnoidal abscess associated with bacterial meningitis in infants--two case reports.

Two infants, an 11-month-old boy and a 7-month-old girl, presented with subarachnoidal abscess associated with severe bacterial meningitis refractory to intensive managements with antibiotics. Computed tomography (CT) revealed bifrontal extracerebral low-density areas and remarkably enhanced surfaces of the bilateral frontal lobes postcontrast. Surgical exploration disclosed thick pus accumulation in the subarachnoid space which required curettage. The boy developed appropriately for his age, but the girl showed severe psychomotor retardation because of additional complications such as subdural fluid collection and hydrocephalus associated with the subarachnoidal abscess. Appropriate early neurosurgical management of subarachnoidal abscess is essential for satisfactory psychomotor development. Postcontrast CT should be performed to detect the subarachnoidal abscess as early as possible, and extensive craniotomy to remove the subarachnoidal pus accumulation performed to preserve psychomotor development.

Brain Abscess↗
PubMed1993

Correlation between serotonergic measures in cerebrospinal fluid and blood of subhuman primate.

The relationship between the concentration of serotonin (5-hydroxytryptamine; 5-HT), its precursor; tryptophan (Trp) and the main metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF) and blood of monkey have been studied. 5-HT, Trp and 5-HIAA underwent circadian changes in both CSF and blood. Significant correlations were found between 5-HT, 5-HIAA and Trp in CSF and blood. The significance of these findings and their relationship to the use of peripheral serotonergic system as a functional model of the central nervous system are discussed.

Animals↗
PubMed1993

Therapeutic effect of a new immunosuppressant, FK-506, on vasospasm after subarachnoid hemorrhage.

We hypothesized that the immunological reaction against extravasated blood might play a role in the development of vasospasm after subarachnoid hemorrhage. Under the hypothesis, we had reported significant therapeutic efficacy of cyclosporin A on vasospasm in canine models. We here investigated the efficacy of a new, potent immunosuppressant, FK-506, on vasospasm in animal models. Dogs were randomly classified into sham operated, subarachnoid hemorrhage treated-1 group, (FK-506, 0.3 mg/kg-d, intramuscular injection), and treated-2 group (FK-506, 0.15 mg/kg-d, intramuscular injection). Levels of the third factor of complement (C3) and the activity of serum complement inducing 50% hemolysis of sheep erythrocytes (CH50) in serum were also determined. In the treated groups, the levels of FK-506 in serum were monitored. As for C3 and CH50, there were no statistically significant differences among the groups and there were no changes between Day 1 and Day 7 in any group. Angiographical diameters of a basilar artery on Days 1 and 7 were measured with a computed image analyzer, and the extent of vasospasm was compared among the groups. Statistically significant differences between the sham-operated group and the other three groups were noted. However, under sufficient levels of FK-506 in serum, the extent of vasospasm in either treated group was the same as that in the subarachnoid hemorrhage group. These results indicate a significant discrepancy in the therapeutic mechanism for vasospasm between cyclosporin A and FK-506. They have common aspects in the immunosuppressive mechanism. However, in T-cell suppression, the different mechanism in situ between the two drugs is also postulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Patient's comprehension of the medical informations presented before the invasive procedures.

The requirement of an informed consent has become a major issue even in the rural area of Japan. Particular interests were focussed on understanding of the information and the effect of pre-existing anxiety on that understanding. Nineteen neurological patients who were going to have either surgeries or invasive diagnostic procedures, agreed to cooperate with the study. Results of the study revealed the followings; (1) comprehension of medical disclosure varied widely from one patient to another, (2) assistance from co-medical staff (a registered nurse in the study) could not facilitate greater comprehension, and (3) the more anxious patients comprehended more. It seemed to remain a question as to how much adults of sound mind actually comprehended it even when the medical disclosure was presented fully and in a simple style.

Adult↗
PubMed1992

Verbal versus non-verbal visual evoked potentials: Kanji versus line drawings.

Cortical areas related to perception of verbal and non-verbal stimuli were studied using VEPs. Kanji characters, line drawings (LD), or a blank were displayed. Verbal VEPs were obtained by subtracting the blank-VEPs from the Kanji-VEPs, and non-verbal VEPs by subtracting the blank-VEPs from the LD-VEPs. Both the verbal and non-verbal VEPs showed a negative peak (100-300 msec) focally over bilateral occipital, posterior temporal and parietal areas, and a positive peak diffusely over frontal halves. Differences between the non-verbal from the verbal VEPs showed an initial peak (100-200 msec) focally over bilateral occipital and posterior temporal areas, followed by a peak (200-300 msec) focally over bilateral posterior temporal areas. The frontal areas diffusely showed peaks at 100-200, 200-300 and 300-400 msec. Left-right asymmetries of both the verbal and non-verbal VEPs showed peaks between 100 and 300 msec over posterior temporal, parietal, and occipital areas. Left-right asymmetries of the subtraction to the non-verbal from the verbal VEPs showed a peak (100 msec) over occipital and parietal areas, and a broader peak over posterior temporal area (100-200 msec). Bilateral occipital, posterior temporal, and parietal areas are focally activated by the two perceptions (100-300 msec), while frontal areas are activated diffusely. Further, different processes may be focally involved between the hemispheres over occipital (100-200 msec) and posterior temporal (100-200 and 200-300 msec) regions. Initial left-right asymmetries of the subtracted VEP between the two perception would occur over occipital and parietal areas (100 msec) and last for 200 msec over posterior temporal area.

Acoustic Stimulation↗
PubMed1992

Relation between protein kinase C and calmodulin systems in cerebrovascular contraction: investigation of the pathogenesis of vasospasm after subarachnoid hemorrhage.

The protein kinase C (PKC) and calmodulin systems each play a role in vascular contraction. However, the correlation of these two systems in producing contraction has been unclear. To clarify the pathophysiology of vasospasm after subarachnoid hemorrhage, the authors demonstrated tonic contraction of the cerebral artery in a study of isometric tension, and investigated the correlation of the PKC and calmodulin systems in producing the contraction. To develop better management for vasospasm, they also examined the effect of calmodulin antagonists on tonic contraction. The development of isometric tension in canine basilar arteries was measured, with the following results: 1) tonic contraction was dependent on the PKC system, but initiation of the contraction by the calmodulin system was necessary for the subsequent PKC-dependent tonic contraction; 2) specific calmodulin antagonists like chlorpromazine and pimozide partially inhibited the tonic contraction associated with PKC activation; 3) another calmodulin antagonist, trifluoperazine, inhibited the PKC system as well. On the basis of these results, the authors conclude that the PKC system plays a role in the development of vasospasm. In the early phase of contraction, the calmodulin system contributes to the subsequent fully-activated, PKC-induced tonic contraction. To manage vasospasm, a specific calmodulin antagonist would therefore not be sufficient. Suppression of both the calmodulin and PKC systems with trifluoperazine in the earliest stage of vasospasm is recommended.

Animals↗
PubMed1991

Post-irradiation vasculopathy of intracranial major arteries in children--report of two cases.

We report two rare cases of post-irradiation vasculopathy of intracranial major arteries in children. A 13-year-old girl suffered from transient right hemiparesis 1 year after irradiation for suprasellar germinoma. Left carotid angiograms revealed marked stenoses of the intracranial internal carotid, middle cerebral, and anterior cerebral arteries, which were previously normal, and moyamoya vessels. A 2.5-year-old girl underwent internal irradiation with 198Au colloid for cystic craniopharyngioma. At the age of 10 years, she suddenly became unconscious after vomiting. Computed tomographic scans showed a right frontal intracerebral hematoma. Right carotid angiograms disclosed complete obstruction of the intracranial internal carotid, middle cerebral, and anterior cerebral arteries and moyamoya vessels, previously not present. The danger of radiation therapy causing occlusive vasculopathy in small and major cerebral arteries in children is emphasized. To prevent permanent ischemic neurological deficits, vasculopathy should be treated either medically or surgically as early as possible.

Adolescent↗
PubMed1991

Cerebellar ganglioglioma--case report.

A 14-year-old boy presented with cerebellar ganglioglioma manifesting as severe headache and confusion. Computed tomographic scans showed a huge, partly enhanced cystic cerebellar tumor. The tumor was totally removed. Histological examination disclosed glial cells and mature ganglion cells. The latter were identified by Nissl's staining and immunostaining for neurofilaments. Ganglion cells were present in the cerebellum and the surrounding subarachnoid space. This heterotopic growth of ganglion cells enabled a firm diagnosis of cerebellar ganglioglioma.

Adolescent↗
PubMed1990

The finger-tapping test. A quantitative analysis.

A quantitative analysis of the so-called finger-tapping test was performed on 111 normal subjects. Quantitative analysis was also performed on 17 patients with cerebellar diseases, 14 with parkinsonism, and 14 with hemiparesis. All analyses were performed in a simple fashion using an 8-bit microcomputer fed through an electrocardiographic apparatus. The results in normal subjects were as follows: (1) tapping frequency lowered with advancing age; (2) men tapped faster than women; and (3) tapping with the dominant finger was faster than tapping with the nondominant finger in normal subjects. Tapping frequency can distinguish patients with motor dysfunctions of cerebellar, basal ganglia, and cerebral origins from normal subjects. Only the time-sequential histograms of tapping intervals could distinguish the motor dysfunctions studied.

Adult↗
PubMed1990

Effect of pinealectomy on cortically kindled rats.

Cortical kindling in pinealectomized rats was studied to observe the effect of pinealectomy on local afterdischarge thresholds and seizure development. Although the local afterdischarge thresholds were not affected by pinealectomy, the kindling process itself was hastened. These results suggest that the anticonvulsive function of the pineal body is due not to a decrease in local afterdischarge thresholds, but to retardation of secondary generalization.

Animals↗
PubMed1990

Lipoma in the cerebellopontine angle--case report.

The authors report a case of a cerebellopontine (CP) angle lipoma with a very unusual histological appearance. The 38-year-old male patient suffered vertigo, left tinnitus, and left hearing disturbance. Computed tomography and magnetic resonance imaging showed a nonenhanced low-density area and a high-intensity region in the left CP angle, respectively. The tumor, which was only partially removed because of its tight adhesion to the VIIIth nerve and brainstem, consisted of mature lipocytes and contained a piece of cartilage, which is highly unusual.

Adult↗
PubMed1990

[Angiographic findings of vertebral dissecting aneurysm. Report of two cases and review of literature].

The authors report two cases of vertebral dissecting aneurysm. The first case, a 49-year-old female, developed severe headache and computed tomography scan showed subarachnoid hemorrhage (SAH), but 4-vessel cerebral angiography failed to show an aneurysm. The second angiograms obtained 2 weeks later showed possible aneurysmal dilatation on the right vertebral artery. The third angiograms, 2.5 months after SAH, disclosed a right vertebral fusiform aneurysm on the arterial phase and it was diagnosed as a dissecting aneurysm since the contrast medium remained until the very late venous phase. The previous angiograms were reviewed using the subtraction technique, which revealed retention of the contrast medium. The second case, a 42-year-old female, suffered from SAH. Left vertebral angiography revealed a fusiform aneurysmal tapered narrowing just distal to the aneurysm, which was a typical "pearl and string sign." The subtraction film of the venous phase also showed retention of the contrast medium in the aneurysmal portion. These findings accurately diagnosed dissecting aneurysm of the vertebral artery. Since the classical true diagnostic "double lumen sign" was rarely observed in the angiograms, it was not easy to diagnose dissecting aneurysm of the vertebral artery. The authors emphasize the angiographic findings of retention of the contrast medium in the venous phase as a "true diagnostic sign" for correct diagnosis of dissecting aneurysm.

Aortic Dissection↗
PubMed1990

Line-drawing test across ages.

A line-drawing test was standardized for normal subjects to examine effects of normal aging. For this purpose, the results of the test for 168 normal volunteers were quantified using a digitizer and a microcomputer across ages from 9 to 78 yr. Three sets of parallel vertical lines were presented to every subject, the distances between the parallel vertical lines (5, 10, and 15 cm) differed in the three sets. A subject drew an horizontal line starting exactly on the left vertical line and stopped exactly on the right one, and the computer could detect minute inaccuracy at the start and at the stop, which inaccuracy was expressed in mm. In this study, effects of four parameters were evaluated, i.e., ages, sex, distances from the paired vertical lines, and order of trials; all were nonsignificant. The normal range of the deviations was within 2.1 mm (average + 2 SD).

Adolescent↗
PubMed1989

[Unilateral nerve deafness due to rupture of a right vertebral artery aneurysm. Case report].

A 49-year-old female with no history of hearing disturbance developed sudden onset of headache and was admitted with no neurological deficits other than mild nuchal rigidity. Computed tomography (CT) showed subarachnoid hemorrhage. Four-vessel cerebral angiography disclosed no aneurysm. A second angiogram obtained on the 14th day showed vasospasm of the bilateral posterior cerebral arteries and right anterior inferior cerebellar artery, but still failed to demonstrate an aneurysm. Following the second angiography, she developed mild disturbance of consciousness and cerebellar ataxia of the right limbs, and repeat CT showed an infarct in the right cerebellar hemisphere. When she regained consciousness a few days later, she was completely deaf on the right side. The third angiography revealed a right vertebral artery dissecting aneurysm. Following clipping of the proximal portion of the right vertebral artery, she did well and was discharged, although right cerebellar ataxia and deafness persisted. Neuro-otological evaluation, including pure-tone audiography, auditory brainstem responses, electrocochleography, and caloric testing, indicated that her deafness resulted from ischemia in the territory of the right internal auditory artery due to vasospasm.

Deafness↗
PubMed1989

[Intra-operative monitoring with ABR during neurovascular decompression for VIIth and VIIIth cranial nerves: a warning sign for surgeons].

Auditory brain stem responses (ABR) were monitored during 18 cases of neurovascular decompression (12 with hemifacial spasm, and 6 with tinnitus, vertigo and/or hearing disturbance). As criteria for warning the surgeon, we adopted such changes as disappearance or marked decrease in amplitude of wave V. ABR changes were classified into 3 types as follows. Type 1 (7 cases): prolongation of latencies without wave form changes, Type 2 (5 cases): temporary disappearance of the waves after wave II, Type 3 (6 cases): temporary loss of all waves. In all cases except in one of the 2, with technical failure, all the waves reappeared within 5 minutes after releasing the retraction and irrigating the cerebellopontine cistern with warm normal saline solution. No patient had severe post-operative hearing deficit, but type 3 patients showed hearing disturbance of statistically significant magnitude (-8.33 +/- 3.16 dB). In type 1 patients, the mean prolongation of wave V latency during operation reached 1.27 +/- 0.44 msec, but the mean hearing loss after operation was only 3.57 +/- 4.4 dB. We believe that as soon as the waves disappear, one should immediately release the retraction and irrigate cisterns with warm normal saline solution, and wait until the waves reappear. Prolongation of latencies alone does not indicate postoperative hearing disturbances, and even if the waves disappear their prompt recovery suggests that hearing will be preserved after operation.

Adult↗