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Y Sakamaki

Publications and source records attributed to Y Sakamaki.

28 records · Page 2Linked to original sources
PubMed1988

Histopathological studies of experimental marine toxin poisoning. II. The acute effects of maitotoxin on the stomach, heart and lymphoid tissues in mice and rats.

Maitotoxin, one of the causative agents of ciguatera isolated from marine dinoflagellate, Gambierdiscus toxicus, induced severe pathomorphological changes in the stomach, heart and lymphoid tissues in mice and rats. Multiple erosions were observed in gastric mucosa accompanied by a marked increase in total calcium content 24 hr after i.p. injection of 200 or 400 ng/kg of maitotoxin. In contrast, there was no close temporal association between the accumulation of calcium and the morphological appearance of dead cells in the heart and thymus. Within 30 min of administration of 200 or 400 ng/kg of maitotoxin, a marked swelling was seen in the endothelial lining cells of blood capillaries between cardiac muscle fibers, followed by the cell death of the fibers. Injection of maitotoxin at a dose of 200 ng/kg or higher also resulted in necrosis of lymphocytes in the cortex of the thymus at 4 hr and in the medulla at 8 hr.

Animals↗
PubMed1988

[Emergency embolectomy in embolic occlusion of the middle cerebral artery].

UNLABELLED: The natural course of embolic occlusion of the middle cerebral artery (MCA) has many variations, which include the frequent appearance of hemorrhagic infarction. There are also fatal cases among which severe ischemic edema is found. There haven's been many cases reported of MCA embolectomy in the acute stage, and findings concerning them have been very complicated and hard to analyze. Nevertheless there certainly exist cases where remarkable improvement of neurological signs is shown soon after the procedure. Five cases of emergency embolectomy have been undergone in our hospital in the past 2 years. The results were better than results obtained in cases where embolectomy was not performed. Three male and two female cases are the objectives, whose average age was 61 +/- 6 years (ranging from 54 to 67 years). The left side of the MC was involved in three cases and the right in two, and all cases had past history of heart diseases which may have been the embolic source. Each case had undergone CT scan soon after admission to make sure not to be the other type of intracranial lesion. Cerebral angiography was performed next, to discover the site of the occlusion and the degree of collateral circulation. Emergency embolectomy was performed as soon as possible in every case. The functional outcome was estimated from the ADL three months later using the international fifth degree grading. RESULTS: The period from onset to recanalization ranges between 4.5 to 11 hours (average 6.9 +/- 2.5 hours). Good MC recanalization was demonstrated in each case angiographically within a week after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Relationship among activation of the Na+/H+ antiporter, ornithine decarboxylase induction, and DNA synthesis.

The relationship among activation of the Na+/H+ antiporter, ornithine decarboxylase, and DNA synthesis was examined with bovine small lymphocytes stimulated by concanavalin A (Con A). The Na+/H+ antiport activity was activated immediately after addition of concanavalin A; the maximum was reached 1 h after Con A addition and the activation continued at least 6 h. With increasing concanavalin A concentrations, the activities of the Na+/H+ antiporter, ornithine decarboxylase, and DNA synthesis increased in a parallel manner. In the presence of HCO3- in the medium, the internal alkalinization of lymphocytes was not induced by Con A. Ornithine decarboxylase and DNA synthetic activities were not inhibited by 5-(N-ethyl-N-isopropyl) amiloride (EIPA), a specific inhibitor of the Na+/H+ antiporter. In contrast, in the absence of HCO3- in the medium, the internal pH was alkalinized approximately 0.06 pH units by Con A. EIPA did inhibit the alkalinization of the internal pH or DNA synthesis significantly. Ornithine decarboxylase activity was not inhibited by EIPA. These results indicate that the activation of a Na+/H+ antiporter is not a trigger for cell proliferation, but its activation is important probably through the maintenance of the internal pH optimum, especially in HCO3(-)-free medium.

Animals↗
PubMed1985

[Acute spontaneous subdural hematoma associated with multiple aneurysms--a case report].

A case of acute spontaneous subdural hematoma associated with three aneurysms is reported. On March 12, 1984, a 47-year-old woman experienced the sudden onset of severe headache over the bilateral frontal region and vomiting. Three hours later, she was transferred to our hospital by ambulance car because of continuous headache and vomiting. She had no history of head trauma. She had been medicated hypertension for five years. On admission she suffered from headache and nausea. But there was no clinical sign in physical and neurological examinations. The meningeal irritation was not present, but lumbar puncture showed slightly pinky CSF with normal pressure. A plain computed tomographic scan showed a thin high density mass in the left temporal extra-axial region and the slight deviation of the midline structures to the right. Left carotid arteriogram showed an avascular region over the left cerebral convexity, an aneurysm of the left A2-A3 junction and a questionable aneurysm of the bifurcation of left middle cerebral artery. Right carotid arteriogram showed an aneurysm of the bifurcation of right middle cerebral artery. We diagnosed this case as an acute subdural hematoma by CT scan and arteriogram. We were perplexed preoperatively whether this bleeding was spontaneous or secondary to the rupture of aneurysm, and we could not deny the possibility of a ruptured aneurysm. On March 15, 1984, three days after onset, operation was performed. At operation, a small subdural hematoma was removed, and the underlying cortex was normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMedDate not supplied

The age-related difference in bone changes in rats induced by recombinant human granulocyte colony-stimulating factor.

We examined the bone changes in recombinant granulocyte colon-stimulating factor (rhG-CSF)-treated young and young adult rats in order to investigate the effect of age-related conditions of bone growth on the bone changes induced by rhG-CSF. Recombinant human G-CSF (100 and 1,000 micrograms/kg/day) was given to rats by daily intravenous injection for 28 days starting at the age of either 6 or 14 wk, and the hindlimb bones were evaluated histopathologically. In the young rats, bone lesions were observed in the 100- and 1,000-micrograms/k groups. In the young adult rats, lesions were found only in the 1,000-micrograms/kg group. The lesions involved accelerated osteoclastic bone resorption and osteogenesis due to intramembranous ossification and there was no age-related difference in these histopathological findings. However, both the incidence of bone involvement and the severity of lesions were greater in the young rats than in the dose-matched young adult rats. The results suggest that the higher dose of rhG-CSF may intrinsically induce bone lesions of a particular histopathological nature in rats regardless of their age, and the action of rhG-CSF on bone may be stronger in young growing rats than in young adults.

Age Factors↗
PubMedDate not supplied

A case of pseudotumor cerebri following glucocorticoid therapy in which warfarin prevented recurrence.

A patient with nephrotic syndrome developed pseudotumor cerebri following glucocorticoid therapy. Diagnosis of pseudotumor cerebri was based on satisfaction of four criteria proposed by Ahlskog and O'Neill. The symptoms of pseudotumor cerebri disappeared within 10 days. After a three-week interval of remission, relapse occurred. Glycerol and urokinase produced rapid resolution of the symptoms and warfarin prevented further recurrence of pseudotumor cerebri for one year. These results suggest that the pathogenesis of pseudotumor cerebri might be associated with the hypercoagulable state which was induced by glucocorticoid therapy and nephrotic syndrome.

Adult↗