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Biomedical subjects

M Amagasa

Publications and source records attributed to M Amagasa.

At least 19 recordsLinked to original sources

High risk of Helicobacter pylori infection in young Japanese dentists.

BACKGROUND AND AIM: The route of person-to-person transmission of Helicobacter pylori may be either fecal-oral or oral-oral, because the bacterium is found in both dental plaque and feces. We assessed the prevalence of H. pylori seropositivity, which reflects present or past infection, in Japanese dentists exposed occupationally to dental plaque. METHODS: We examined the sera of 60 dentists (34 who were 20-29 years or older, and 26 who were over 30 years of age) and 60 age-matched controls by using quantitative ELISA for antibodies of the immunoglobulin G class to H. pylori. RESULTS: The proportion of dentists seropositive for H. pylori (42 of 60, 70%) was higher than in controls (23 of 60, 38%). The odds ratio for H. pylori seropositivity (3.8; 95% CI, 1.76-8.02) was high in the dentists. When dentists were classified in terms of the length of their practice, the odds ratio for seropositivity (10.4; 95% CI, 3.26-32.85) was high in the dentists practising for fewer than 4 years. The proportion of dentists in their 20s who were seropositive was greater than that in the group of age-matched controls. CONCLUSION: Japanese young dentists are at a high risk for H. pylori infection, with the oral-oral transmission route being possibly the most common.

Adult↗

Pilocytic astrocytoma arising from an area of nodular heterotopia located in the white matter of the temporal lobe: case report.

A 16-year-old girl suffering from intractable temporal lobe epilepsy presented with a pilocytic astrocytoma, which occurred in an area of nodular heterotopia located in the white matter of the temporal lobe. The pilocytic astrocytoma appeared to be covered by an area of gliosis, which contained numerous Rosenthal fibers, while in the lesion the pilocytic astrocytoma occupied a small area. The gliosis eventually became a tumor-like lesion. The white matter around the mass was composed of gliosis with nodular heterotopia. Temporal developmental malformation, which was a basic lesion of the patient, might therefore be a precursor lesion of pilocytic astrocytomas.

Adolescent↗

Lhermitte-Duclos disease associated with Cowden disease.

We encountered a patient with Lhermitte-Duclos disease accompanied by Cowden disease, the second reported in Japan. The histological findings are described in detail. It is important to suspect Cowden disease in patients with Lhermitte-Duclos disease. Although Cowden disease is little known, making the diagnosis is very important, because cancer frequently occurs in the patient's family and genetic counseling is necessary.

Cerebellar Neoplasms↗

Spinal malignant lymphoma appearing after radiation and chemotherapy of a pineal region tumor.

The occurrence of malignant lymphoma in the pineal region is very rare. We experienced a case of pineal region tumor that was treated by radiation and chemotherapy. After 1 year, the tumor metastasized to the cauda equina and was operated on. The diagnosis was malignant lymphoma. Although the incidence of intracranial malignant lymphoma is known to be on the increase recently, malignant lymphoma should be considered in the differential diagnosis of pineal region tumors.

Adolescent↗

[A case of frontal lobe epilepsy presenting with recurrent speech arrest].

We report a 55-year-old right-handed man with frontal lobe epilepsy manifesting recurrent speech arrest. He was known to have hypertension, hypertriglyceridemia, and gout. In the three days prior to admission, he had episodes of sudden inability to talk. These episodes lasted 10 to 30 seconds and recurred ten to twenty times a day. On admission, speech comprehension and other mental functions were normal, as were findings on neurologic examination. During the period of speech arrest, he understood spoken commands, and there was no abnormal motor activity or paresis. The episodes of speech arrest were thought to be short aphasic periods due to transient ischemic attacks in the left carotid territory. Computed tomography and magnetic resonance imaging demonstrated a small calcified lesion in the upper medial portion of the left frontal lobe. Left internal carotid angiography demonstrated no abnormal findings. After neuroradiological examination finished, he suddenly raised his right hand and followed it with his gaze and a right head turn. The EEG seizure pattern in which 20-25 Hz activity began in the left fronto-central region and spread rapidly to the right fronto-central region, which after about 8 seconds was replaced by 12-14 Hz flattening rhythmic polyspikes was detected 9 times within 60 minutes. It is most unusual for supplementary motor area seizure to present pure paroxysmal speech arrest without accompanying paroxysmal motor activity. As in our case, epileptic arrest of speech may be confused with a transient ischemic attack of the dominant hemisphere.

Electroencephalography↗

Effects of calcium and calcium antagonists against deprivation of glucose and oxygen in guinea pig hippocampal slices.

To provide evidence to support the calcium hypothesis of cerebral ischemia, we examined the effects of extracellular calcium and calcium antagonists (verapamil, flunarizine, nicardipine) on in vitro 'ischemia' using guinea pig hippocampal slices. As a model of in vivo ischemia we used a state of both glucose and oxygen deprivation. Recovery of dentate antidromic field response and histological changes were used as indices of cell damage. After 10 min of deprivation in standard Krebs-Ringer solution, the field potentials exhibited minimum recovery and dentate neurons were severely damaged. Damaged neurons had pyknotic nuclei and swollen cytoplasms. Drugs were added and the calcium concentration was changed during 30 min of pre-deprivation and during deprivation. In the first experiment we demonstrated that pre-treated calcium antagonists protect the dentate granule cells against glucose and oxygen deprivation. The order of the protective potency was flunarizine greater than verapamil much greater than nicardipine. In the second experiment we also showed that neuronal damage caused by deprivation is dependent on the extracellular concentration of calcium. Our data show that extracellular calcium is partially responsible for 'ischemic' neuronal injury in the hippocampal slice. Both low calcium and voltage-gated calcium channel blockers can preserve an antidromic population spike. Conversely, high calcium in the bath can worsen the damage caused by in vitro 'ischemia' to hippocampal slices.

Action Potentials↗

Actions of brain-protecting substances against both oxygen and glucose deprivation in the guinea pig hippocampal neurons studied in vitro.

A study was made of the protective effects of several drugs (mannitol, phenytoin, vitamin E and dexamethasone) on the electrical activities of guinea pig hippocampal neurons in vitro when they were treated with a bathing medium deprived of both oxygen and glucose. Using guinea pig hippocampal slices, antidromic field potentials in the granular cell layer of the dentate gyrus were recorded stimulating mossy fibers. A model of ischemia in vivo in the slices was achieved by removing both oxygen and glucose from the perfusing medium. In standard medium, after 10 min of both oxygen and glucose deprivation, the field potentials exhibited minimum recovery with an amplitude of 6% of the control after 60 min. The protective effect of the drugs was evaluated by recovery of the field potential amplitude of the 60 min post-deprivation response and histological examination of the brain slice tissue. Drugs were added during 30 min of pre-deprivation and during deprivation. In this experiment we demonstrated that (1) phenytoin and vitamin E clearly showed protective action against neuronal damage caused by both oxygen and glucose deprivation in guinea pig hippocampal slices, (2) combined application of these drugs was more effective, and (3) mannitol showed no protective action in vitro. It was also demonstrated that (4) the dentate antidromic field response can be a useful index of cell death.

Action Potentials↗

[A case of intramedullary spinal cavitation after minor trauma].

A case of surgically treated intramedullary spinal cavity which appeared 1 year after a minor injury was presented. A 15 year-old boy developed nuchalgia and muscle weakness of his right arm and leg. On admission, he had right hemiparesis and sensory disturbances in the right C6-C8 and left T1-S5 dermatomes. Metrizamide-CT scan and MRI disclosed an intramedullary spinal cavity between C4-C5 vertebral levels. A myelotomy and a biopsy of the cavity wall were carried out in order to communicate the cavity with the subarachnoid space, and to make a definite diagnosis. The microscopic examination of a biopsy specimen revealed no tumor findings but inflammation. Taking into account the location of the cavity, a site corresponding with the site of a previous trauma, the authors finally diagnosed the cavity as intramedullary spinal cavitation after minor trauma. His symptoms improved remarkably after the operation.

Adolescent↗

Posttraumatic dissecting aneurysm of the anterior cerebral artery: case report.

A case of cerebral infarction in the territory of the anterior cerebral artery after a minor head injury is reported. It is possible that direct or mechanical damage by the edge of the falx or stretching and shearing of the anterior cerebral artery after an acute shift of the corpus callosum caused the localized lesion of the left anterior cerebral artery. We think that this mechanical injury caused a dissecting aneurysm or a cerebral arterial dissection, which was diagnosed by sequential angiographic changes.

Adult↗

[Protective effect of various agents against ischemic neuronal damage in guinea pig hippocampal neurons studied in vitro].

A study was made of protective effect of several drugs (mannitol, phenytoin, vitamin E and dexamethasone) against the deprivation of both glucose and oxygen from the bathing medium on electrical activities of guinea-pig hippocampal neurons in vitro. Using guinea-pig hippocampal slice, we recorded antidromic field potentials in the granular cell layer of the dentate gyrus with stimulating mossy fibers. "Ischemia" of a slice was achieved by substracting both glucose and oxygen from the perfusing medium. In standard medium, after 10 minutes of ischemia, field potentials had minimum recovery with an amplitude of 5% of control after 60 minutes in the standard medium. Mannitol treatment had no protective effect, but phenytoin, vitamin E and dexamethasone had clear dose-dependent effect. The protective effect was evaluated by recovery of field potential amplitude of the 60 minutes postischemic response and histological examination of the brain slice tissue. The degree of the histological damage was correlated with recovery of field potential. In this experiment we have demonstrated that phenytoin and vitamin E obviously have the protective action against ischemic neuronal damage in the guinea-pig hippocampal slice and the combined application of these drugs were more effective.

Animals↗

[Post-traumatic occlusion of the anterior cerebral artery].

A rare case with cerebral infarction in the region of the anterior cerebral artery after minor head injury is reported. A 44-year-old male sustained a blow in the occipital area and became unconscious for a moment when he was driving a car and was involved in a rear-end collision. There being no significant signs, he drove home. About 30 minutes after the traffic accident, he felt weakness in the right limbs and speech difficulty and immediately visited our clinic. The patient was alert, but right hemiparesis and mild motor aphasia were present. There was no apparent evidence of head injury. A plain skull roentgenogram revealed no fracture. Computed tomography two hours after the trauma was normal. A left carotid angiogram showed an evident dilatation of A2 and the proximal portion of A3 of the anterior cerebral artery, tapering off to an occlusion of the callosomarginal artery in the arterial phase, delayed filling of the anterior cerebral artery in the capillary phase, and pooling of the callosomarginal artery in the venous phase. Three days later, computed tomography showed a low density area on the medial surface of the left frontal lobe. The symptoms of the patient improved with conservative treatment. Sequential changes in angiographic findings were observed. One month after admission, severe irregularity and stenosis of the pericallosal artery and revascularization of the callosomarginal artery was noted. By this time most of his symptoms had disappeared. Two months after admission, stenosis of the pericallosal artery increased. Three months after admission the stenosis improved slightly. The patient was discharged with no neurological deficit. Seven months after the initial trauma, a left carotid angiogram showed further regression of the stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

[An electrocardiographic abnormality called torsade de pointes in a patient of subarachnoid hemorrhage].

We report the findings in a patient in whom torsade de pointes atypical ventricular tachycardia occurred as a complication of subarachnoid hemorrhage. The patient was a 54-year-old female and she was admitted to our hospital to treat gastric ulcer on October 8, 1985. The electrocardiogram on admission showed mild left ventricular hypertrophy. She complained of severe headache and nausea in hospital on November 10 and she was transferred to our department. Her consciousness was clear. Computed tomography revealed a subarachnoid hemorrhage and left carotid angiogram showed a left middle cerebral artery aneurysm. Laboratory findings of blood and a chest roentgenogram were normal, but the electrocardiogram revealed a prominent prolongation of the QT interval and generalized giant negative T waves. The aneurysm was clipped on November 11, but a torsade de pointes atypical ventricular tachycardia occurred after clipping of the aneurysm during the surgery. Several anti-arrhythmic agents were not effective but phenytoin suppressed the arrhythmia. Postoperative course was almost uneventful. Since she had mild right hemiparesis, she continued the rehabilitation in our department. Five months later her electrocardiographic findings became normal. Prolongation of the QT interval and the giant negative T wave are typical electrocardiographic abnormalities in patients of subarachnoid hemorrhage, causing a predisposition to torsade de pointes ventricular tachycardia. The arrhythmia should be kept in mind as a complication in a viewpoint of the management of subarachnoid hemorrhage in the acute stage.

Electrocardiography↗

[Three cases of an intracranial wooden foreign body].

Three cases of intracranial wooden foreign body are reported discussing the diagnostic and therapeutic problems. First case is a 50-year-old man. After drinking, he drove a bike and fell to the ground. On admission the wooden foreign body could not been detected in appearance. CT scan showed low density area similar to air in bilateral anterior horn of lateral ventricle. The patient was treated for traumatic pneumocephalus at first. Later, it proved that he was stabbed with a foreign body penetrating into the contralateral frontal lobe through the left nasal cavity. It was extracted by endonasal approach by otolaryngologist, fortunately without trouble. The foreign body was a branch of tree. The second case is an 18-year-old man. He was driving a car, and suffered injury. He was stabbed with a wooden stake penetrating into his left eye. Immediately, bifrontal craniotomy was performed and the stake was withdrawn carefully. Moreover bone fragments were removed. The third case is a 61-year-old man. When he cut the timber by chain saw, a piece of wood hit and stabbed his right eye directly. Immediately right front temporal craniotomy was performed. The piece of wood was withdrawn from the right eye, and pieces of glass, wood and bone fragments were evacuated. It is difficult to confirm intracranial foreign body accurately by means of only plain skull film and usual CT scans. It is necessary to utilize various function of CT scanner. For example, it is useful to know CT values or select measure mode with window width and level or make reconstruction image to sagittal or coronal section, and so on.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

[Pseudoaneurysm of the cortical artery associated with chronic subdural hematoma--a consideration on traumatic middle cerebral artery aneurysm].

A 62-year-old man was admitted to our hospital, since chronic subdural hematoma was showed after he complained of mild headache and nausea. Two years ago he had head trauma at the left parietal region after drinking. On admission there was no paresis and mild choked disc is detected. Computed tomography with contrast enhancement showed abnormal enhancement and left chronic subdural hematoma. Cerebral angiography showed an aneurysm of the angular artery. Operation was done and the aneurysm was trapped. Aneurysmal wall was histologically a pseudoaneurysm. Post-operative result was good. We considered the relationship between the cortical pseudoaneurysm and chronic subdural hematoma. We reviewed the traumatic middle cerebral artery aneurysm in the literature, 56 cases.

Chronic Disease↗