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Biomedical subjects

I Hamada

Publications and source records attributed to I Hamada.

At least 19 recordsLinked to original sources
PubMed2001

Relationship between lesion location and the outcome of pallidotomy for Parkinson's disease.

The relationships between lesion location and clinical outcome following posteroventral pallidotomy for Parkinson's disease were studied. Forty-four patients were operated forty-six times and studied with neurological and psychological examinations before and after pallidotomy. Lesion location was confirmed using films with a coagulation electrode which were X-rayed during the operation. Changes of intelligence were observed in the patients with anteromedial lesions. Wearing-off phenomenon in four patients and dopa-induced dyskinesia in three patients were not improved following pallidotomy in twenty patients with severe wearing-off and dyskinesia. Lesions in the patients with no improvement of wearing off were located more lateral and those in the patients with sustained severe dyskinesia were located more dorsal in the internal part of the globus pallidus. It may be concluded that clinical outcome is related to lesion location.

Antiparkinson Agents↗
PubMed2001

Organization of inputs from cingulate motor areas to basal ganglia in macaque monkey.

The cingulate motor areas reside within regions lining the cingulate sulcus and are divided into rostral and caudal parts. Recent studies suggest that the rostral and caudal cingulate motor areas participate in distinct aspects of motor function: the former plays a role in higher-order cognitive control of movements, whereas the latter is more directly involved in their execution. Here, we investigated the organization of cingulate motor areas inputs to the basal ganglia in the macaque monkey. Identified forelimb representations of the rostral and caudal cingulate motor areas were injected with different anterograde tracers and the distribution patterns of labelled terminals were analysed in the striatum and the subthalamic nucleus. Corticostriatal inputs from the rostral and caudal cingulate motor areas were located within the rostral striatum, with the highest density in the striatal cell bridges and the ventrolateral portions of the putamen, respectively. There was no substantial overlap between these input zones. Similarly, a certain segregation of input zones from the rostral and caudal cingulate motor areas occurred along the mediolateral axis of the subthalamic nucleus. It has also been revealed that corticostriatal and corticosubthalamic input zones from the rostral cingulate motor area considerably overlapped those from the presupplementary motor area, while the input zones from the caudal cingulate motor area displayed a large overlap with those from the primary motor cortex. The present results indicate that a parallel design underlies motor information processing in the cortico-basal ganglia loop derived from the rostral and caudal cingulate motor areas.

Action Potentials↗
PubMed2001

[Anesthetic management in a patient with Simpson-Golabi-Behmel syndrome].

We report the anesthetic management of a 4-yr-old boy with Simpson-Golabi-Behmel syndrome. This syndrome is an X-linked condition characterized by pre- and postnatal overgrowth with visceral and skeletal anomalies. Affected males have a distinctive facial appearance with wide nasal bridge, anteverted nostrils, wide-open mouth, enlarged tongue, and large protruding maxilla and jaw. Although it had been speculated preoperatively that airway management would be complicated by the macroglossia, there was no difficulty in endotracheal intubation in the present patient. Preparations for difficult airway management should be made by the anesthesiologist before induction of anesthesia.

Abnormalities, Multiple↗
PubMed2000

A cortical motor region that represents the cutaneous back muscles in the macaque monkey.

A cortical motor region that represented the cutaneous muscles on the back was identified on the medial wall of the frontal lobe in the macaque monkey. In this region, neurons responded to somatosensory stimuli such as light touch or squeezing of the back skin, and intracortical microstimulation elicited contraction of the back skin. Such a region was located primarily on the dorsal bank of the cingulate sulcus, corresponding to the dorsal cingulate motor area.

Animals↗
PubMed2000

Excitatory cortical inputs to pallidal neurons via the subthalamic nucleus in the monkey.

How the motor-related cortical areas modulate the activity of the output nuclei of the basal ganglia is an important issue for understanding the mechanisms of motor control by the basal ganglia. In the present study, by using awake monkeys, the polysynaptic effects of electrical stimulation in the forelimb regions of the primary motor and primary somatosensory cortices on the activity of globus pallidus (GP) neurons, especially mediated by the subthalamic nucleus (STN), have been characterized. Cortical stimulation induced an early, short-latency excitation followed by an inhibition and a late excitation in neurons of both the external and internal segments of the GP. It also induced an early, short-latency excitation followed by a late excitation and an inhibition in STN neurons. The early excitation in STN neurons preceded that in GP neurons. Blockade of STN neuronal activity by muscimol (GABA(A) receptor agonist) injection resulted in abolishment of both the early and late excitations evoked in GP neurons by cortical stimulation. At the same time, the spontaneous discharge rate of GP neurons decreased, pauses between the groups of spikes of GP neurons became prominent, and the firing pattern became regular. Injection of (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) [N-methyl-D-aspartate (NMDA) receptor antagonist], but not 1,2,3, 4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide disodium [NBQX (non-NMDA receptor antagonist)], into the STN attenuated the early and late excitations in GP neurons, suggesting that cortico-subthalamic transmission is mediated mainly by NMDA receptors. Interference with the pallido-subthalamic transmission by bicuculline (GABA(A) receptor antagonist) injection into the STN made the inhibition distinct without affecting the early excitation. The present results indicate that the cortico-subthalamo-pallidal pathway conveys powerful excitatory effects from the motor-related cortical areas to the GP with shorter conduction time than the effects conveyed through the striatum.

Animals↗
PubMed1998

A modified microsyringe for extracellular recording of neuronal activity.

We describe a modified Hamilton microsyringe that allows extracellular recording of neuronal activity and subsequent injections. It is assembled with a Hamilton removable needle and a syringe for injection, a Teflon-coated tungsten wire for recording, and polyimide tubing as a sheath. The device is inexpensive and easy to handle in anatomical and physiological experiments in awake monkeys.

Animals↗
PubMed1995

Myolipoma of the round ligament: report of a case with a review of the English literature.

Tumours consisting of a mixture of mature adipose and smooth muscle tissues, including those designated lipoleiomyomas, fibrolipoleiomyomas and myolipomas, are exceedingly rare, but most often occur in the uterine corpus. We describe here a case of such a tumour arising in the right round ligament of a 44-year-old woman. The tumour, which measured approximately 20x15x10 cm, was well encapsulated and did not involve the intrapelvic organs. Intricate mixtures of adult adipose tissue and bland smooth muscle exhibited no cellular atypia or nuclear mitotic figures, and there was little vascular proliferation. We diagnosed the lesion as a myolipoma of soft tissue with dual differentiation, and have found only 13 cases of this tumour including our own in the English literature. The present tumour is the first reported in the round ligament. Although this tumour is rare, its recognition is important for the avoidance of erroneous diagnoses.

Adult↗
PubMed1993

Detection of Epstein-Barr virus DNA in cardiac and aortic tissues from chronic, active Epstein-Barr virus infection associated with Kawasaki disease-like coronary artery aneurysms.

We describe three patients with chronic, active Epstein-Barr virus infection associated with Kawasaki disease-like coronary artery aneurysms. The Epstein-Barr virus genome was detected in three cardiac tissue samples and one aortic tissue sample examined by means of the polymerase chain reaction. These findings suggest that chronic Epstein-Barr virus infection may play a pathogenic role in the development of coronary artery aneurysms.

Antibodies, Viral↗
PubMed1992

Excitotoxic acid lesions of the primate subthalamic nucleus result in transient dyskinesias of the contralateral limbs.

1. To examine the role of the subthalamic nucleus (STN) in the pathogenesis of dyskinesias, the STN was experimentally lesioned with fiber-sparing excitotoxins in two awake monkeys. 2. A combined recording-injection device was used to locate and lesion the STN accurately under physiological guidance. A small amount (1 microliters) of ibotenic acid (10 micrograms/microliters) or kainic acid (1 micrograms/microliters) was injected into each of four to seven target sites in the STN. Postmortem histology confirmed that lesions were confined to the STN, and the volume of each lesion at each site was 4-11% of the total volume of the nucleus. 3. Approximately 20 min after the end of each injection, the frequency of movements increased in the distal portions of the upper and lower limbs contralateral to the injection site. Severe dyskinesias, involving the proximal joints to a greater degree than the distal, developed in the contralateral limbs after 60-80 min and lasted < or = 4 h. The pattern of involvement and time course were similar after each lesion. In the days after the lesioning, only rare dyskinesias were observed in the contralateral hands and feet, typically occurring when the animals were stimulated. 4. Despite the severe dyskinesias, there was no obvious effect on voluntary movements such as grooming or reaching. 5. These results suggest that reduction of STN activity plays a role in the production of dyskinesias.

Animals↗
PubMed1992

Excitotoxic acid lesions of the primate subthalamic nucleus result in reduced pallidal neuronal activity during active holding.

1. To gain a better understanding of the pathophysiology of hemiballismus in primates, and to test directly the hypothesis that the subthalamopallidal projection is excitatory, we studied the effects of lesions of the subthalamic nucleus (STN) on neuronal activity in the globus pallidus (GP) of monkeys during performance of a motor behavioral task. 2. Animals were trained to position and hold a manipulandum to which torque pulses were applied, producing elbow flexion and extension. The activity of neurons in the external (GPe) and internal (GPi) segments of GP was recorded in two monkeys during task performance before and after STN lesions. The STN was lesioned by the fiber-sparing neurotoxins ibotenic acid and/or kainic acid. 3. After lesioning, the firing rate of neurons in both segments of GP, which was measured during the period of holding before torque application, was significantly decreased in both animals. The mean of discharge rates of GPi neurons decreased (P < 0.001) from 69.8 (n = 169, SD = 21.6) to 47.4 spikes/s (n = 180, SD = 22.6) after lesioning. The mean of discharge rates of GPe neurons decreased from 63.6 spikes/s (n = 218, SD = 25.1) before lesions to 41.0 spikes/s (n = 208, SD = 18.1) after lesioning. 4. These results provide further evidence that STN gives rise to a major excitatory input to both segments of the GP and support the hypothesis that dyskinesias result from decreased GPi output.

Animals↗
PubMed1992

[Acute pulmonary edema in five patients undergoing sevoflurane anesthesia].

Four adults and a child undergoing surgery with sevoflurane anesthesia developed acute pulmonary edema immediately after anesthesia. Prior to development of pulmonary edema all patients exhibited severe arterial hypertension and tachycardia. Their episodes of circulatory changes were, we believed, caused by the local injection of epinephrine for hemostasis in 2 patients (9 y.o. child, 45 y.o. man) and the intrusion of painful surgical stimuli in one patient (67 y.o. man). Circulatory changes in these three patients were treated by increasing the inspired sevoflurane concentration. We, however, speculate that the increase in inspired sevoflurane decreased the cardiac output and that the resulting increase in pulmonary wedge and capillary pressures was caused by an abrupt increase of arterial blood pressure, followed by a rapid increase in afterload due to cardiac suppression from the high concentration of sevoflurane. In 2 patients (74 y.o. man, 61 y.o. woman) arterial hypertension occurred during endotracheal extubation after sevoflurane anesthesia. Because of fast uptake and elimination of sevoflurane due to a low blood/gas partition coefficient, a fast awakening in the latter 2 patients, may be responsible for the abrupt increase in arterial blood pressure. In conclusion, it should be noted that pulmonary edema may be involved when severe circulatory changes occur in a patient undergoing sevoflurane anesthesia.

Acute Disease↗
PubMed1991

Penta X syndrome: a case report with review of the literature.

We describe a 6 month-old girl with a 49, XX-XXX chromosome constitution. The patient had a characteristic round face, a low hairline, hypertelorism, epicanthus, a long philtrum, high-arched palate, short and webbed neck, small hands and feet, clinodactyly of the fifth fingers, overlapping toes, and separation between the first and the second toes. She also had atrial septal defect and patent ductus arteriosus complicated by myocarditis which exacerbated the course of her congestive heart failure. Psychomotor development was retarded with opisthotonoid posture, axial hypotonia, and with a borderline abnormal EEG. A densitometric, transmission analysis on X-linked polymorphic DNA-fragments of the Southern blots of the patient and the parents, using P20/MspI and pERT87-1/XmnI as probe/enzyme combinations, showed that the pentasomy X had resulted from 3 successive nondisjunctions at maternal meiosis. Clinical manifestations among 22 previously reported penta X syndrome patients are also reviewed.

Abnormalities, Multiple↗
PubMed1991

Parental origin and mechanism of formation of polysomy X: an XXXXX case and four XXXXY cases determined with RFLPs.

The parental origin and mechanism of formation of polysomy X were studied in five cases (one case of 49,XXXXX; four cases of 49,XXXXY), using various X-linked restriction fragment length polymorphisms as genetic markers. Segregation and densitometric analyses on the polymorphic DNA fragments revealed that, in all five cases, the additional X chromosomes are of maternal origin and the mechanism of formation is most probably a result of three non-disjunctions during maternal meiotic divisions: once at the first meiosis and simultaneously twice at the second meiosis. The identical origin and the identical mechanism of formation among the five cases are unlikely to be coincidental and suggest a common cause in the mothers of the five cases.

Abnormalities, Multiple↗
PubMed1990

Activity of identified wrist-related pallidal neurons during step and ramp wrist movements in the monkey.

1. The activity of globus pallidus (GP) neurons (n = 1,117) was studied in two monkeys to reexamine the relation of neuronal activity to movement type (slow vs. fast) while they performed both a visually guided step and ramp wrist tracking task. To select neurons specifically related to wrist movements, we employed both a somatosensory examination of individual body parts and a statistical analysis of the strength of temporal coupling of neuronal discharges to active wrist movement. 2. Neuronal responses to somatosensory stimulation were studied in 1,000 high-frequency GP neurons, of which 686 exhibited clear responses to manipulation of body parts. Of the latter, 336 responded to passive manipulation of forelimb joints and 58 selectively to passive flexion or extension of the wrist. 3. In the external segment of GP (GPe), most neurons responding to passive wrist movement were found to be clustered in four to five adjacent, closely positioned (separated by 200 microns) tracks in single coronal planes. The clusters were irregular in shape with a maximal width of 800-1,000 microns. Separate clusters of neurons responsive to passive wrist movement were identified in planes 3 mm apart in one monkey and in planes 500 microns apart in the other. Multiple clusters of neurons were also found for neurons responsive to joints other than the wrist. These findings suggest a more discrete and complex representation of individual joints in the primate GP than previously conceived. 4. During the performance of the wrist flexion and extension task, 92 neurons showed clear and consistent changes in activity. For these neurons we measured, with a statistical method on a trial-by-trial basis, the strength of temporal coupling between the onset of active wrist movement and the onset of change in neuronal discharge rate. Fifteen neurons showed changes in activity time-locked to the onset of active wrist movement. 5. Twelve pallidal neurons were classified as "wrist-related" based on their movement-locked changes in discharge during task performance and their clear responses to passive wrist joint rotation on examination. All of these neurons exhibited statistically significant modulation of their discharge rate during both fast (peak velocity 97-205 degrees/s) and slow (peak velocity 20-62 degrees/s) wrist movements in the task. The amplitudes of modulation were larger during fast wrist movement than slow movement. These results suggest that the basal ganglia motor circuit plays a similar, rather than an exclusive, role in the control of slow and fast limb movements.

Animals↗
PubMed1989

Chronic Epstein-Barr virus infections associated with coronary aneurysms.

We recently reported virological studies in a patient with chronic active Epstein-Barr virus (EBV) infection in which T-lymphocytes were infected, and coronary aneurysms were detected by echocardiography. We report here the clinical features of this patient and suggest that EBV may cause coronary aneurysms and that an echocardiographic study should be performed in patients with chronic active EBV infection.

Aneurysm↗
PubMed1984

Effects of stimulation of corpus callosum on precentral neuron activity in the awake monkey.

The effects of stimulation of the corpus callosum (CC) on precentral neurons were studied in monkeys performing motor tasks with either forelimb. Of a total of 246 precentral neurons that were tested with CC stimulation, 70 were orthodromically and 12 were antidromically activated. The percentages of neurons orthodromically activated by CC stimulation were the same in pyramidal tract neurons (PTNs) (31%) and non-PTNs (31%). The mean latency of neuronal activation by CC stimulation was similar in PTNs and non-PTNs. Precentral neurons were divided into two groups with respect to muscular contractions evoked by intracortical stimulation: neurons related to finger, wrist, and elbow movements (distal group) and those related to shoulder or axial movements (proximal group). The percentages of neurons orthodromically activated by CC stimulation were similar in both groups; 25% in distal and 29% in proximal groups. However, the mean latency of orthodromic CC activation was significantly shorter for the proximal than for the distal group. Precentral neurons were classified into three groups; neurons related to finger and/or wrist movement tasks (F-W group), those related to arm movement tasks in addition to finger and/or wrist tasks (F, W + A group), and those related to arm movements only (A group). The percentages of neurons orthodromically activated by CC stimulation were similar in the three groups. The mean latencies of neuronal activities were a little longer in the F-W group than in the A group or the F, W + A group. Precentral neurons were classified into three groups in relation to ipsilateral or contralateral forelimb movements: neurons related to ipsilateral movements (ipsi neurons, n = 13), those related to ipsilateral as well as contralateral movements (bilat neurons, n = 50) and those related to contralateral movements (contra neurons, n = 136). The percentages of neurons orthodromically activated by CC stimulation were 15 (2/13, ipsi neurons), 24.0 (12/50, bilat neurons), and 25.0% (34/136, contra neurons), respectively. The mean latencies of neuronal activation were compared between two groups; one group was composed of ipsi and bilat neurons, and the other group was of contra neurons. The mean latency was a little shorter for the ipsi + bilat group than for the contra group.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗