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Biomedical subjects

M Sakurai

Publications and source records attributed to M Sakurai.

At least 937 records · Page 52Linked to original sources
PubMed1982

Climbing fibre induced depression of both mossy fibre responsiveness and glutamate sensitivity of cerebellar Purkinje cells.

1. In high decerebrate rabbits, cells were sampled extracellularly from the rostral flocculus. Purkinje cells were identified by their characteristic responses to stimulation of the contralateral inferior olive. Identification of basket cells was based on the absence of olivary responses and also on their location in the molecular layer adjacent to identified Purkinje cells. Mass field potentials in the flocculus were also studied.2. Single pulse stimulation of a vestibular nerve, either ipsilateral or contralateral, at a rate of 2/sec excited Purkinje cells with a latency of 3-6 msec. This early excitation represents activation through vestibular mossy fibres, granule cells and their axons (parallel fibres). Similar early excitation also occurred in putative basket cells.3. Conjunctive stimulation of a vestibular nerve at 20/sec and the inferior olive at 4/sec, for 25 sec per trial, effectively depressed the early excitation of Purkinje cells by that nerve, without an associated change in spontaneous discharge. The depression recovered in about ten minutes. This recovery was followed by the onset of a slow depression lasting for an hour.4. Conjunctive vestibular-olivary stimulation produced no such depression in the following responses: early excitation in Purkinje cells induced from the vestibular nerve not involved in the conjunctive stimulation; early excitation in putative basket cells from either vestibular nerve; inhibition or rebound facilitation in Purkinje cells following the early excitation; vestibular-evoked field potentials in the granular layer and white matter of the flocculus. These observations lead to the conclusion that the depression occurs specifically at parallel fibre-Purkinje cell synapses involved in conjunctive stimulation.5. Ionophoretic application of glutamate to Purkinje cells in conjunction with 4/sec olivary stimulation depressed the glutamate sensitivity of Purkinje cells; aspartate sensitivity was depressed to a much lesser degree. The depression diminished in about 10 min, but this recovery was succeeded by a slow depression lasting for an hour. The depression was seen only when glutamate sensitivity was relatively high, suggesting that the micro-electrode was impinging onto Purkinje cell dendrites. These observations suggest that subsynaptic chemosensitivity of Purkinje cells to the putative neurotransmitter of parallel fibres is involved in the depression observed after conjunctive stimulation of a vestibular nerve and the inferior olive.6. The present results are consistent with the Marr-Albus assumption concerning plasticity of cerebellar neuronal networks.

Action Potentials↗
PubMed1982

Potentiation of toxicity and positive inotropic effect of ouabain by furosemide in guinea pig heart.

The present study was undertaken to elucidate the potentiation by furosemide of toxicity and positive inotropic effect of ouabain in guinea pigs. Arrhythmogenic responses to ouabain as well as the lowering of its lethal dose were potentiated by pretreatment with furosemide in guinea pigs. The potentiation of ouabain toxicity after furosemide administration was inhibited by pretreatment with potassium sparing diuretic, prorenoate. Furosemide-induced potentiations of contractile force and arrhythmogenic effect of ouabain were also observed in isolated guinea pig papillary muscle. However after pretreatment with furosemide, ouabain produced arrhythmias without any significant changes in either left ventricular or subcellular fractions binding of 3H-ouabain in guinea pigs. These findings suggest that furosemide-induced potentiation of ouabain toxicity is at least in part associated with the decreased intracellular potassium content of guinea pig heart. It was also demonstrated that the positive inotropic action induced by subtoxic dose of ouabain was potentiated by furosemide in guinea pig papillary muscle preparation.

Animals↗
PubMed1982

Delineation of unruptured cerebral aneurysms by computerized angiotomography.

Unruptured aneurysms were diagnosed in 15 of 86 patients with cerebral aneurysms during 2 years beginning in April, 1979. One patient with severe head injury was excluded from the series. Fifteen aneurysms in the other 14 patients were first detected by computerized angiotomography. Six aneurysms were located in the middle cerebral artery, three in the upper half of the basilar artery, two in the anterior communicating artery, two in the posterior cerebral artery, and two at the internal carotid-posterior communicating artery junction (both in the same patient). Three were smaller than 5 mm, eight were between 6 and 10 mm, and four were larger than 10 mm. The noncontrast computerized tomography (CT) findings associated with 15 aneurysms were as follows: five showed defects in the basal cistern of Sylvian fissure, four were calcified or high-density masses, and in the six instances there was no evidence of an aneurysm. Unruptured aneurysms may be suggested by a well demarcated, round, isodense mass which forms a defect in the basal cistern of Sylvian fissure on a plain CT image, and are highly and homogeneously enhanced by computerized angiotomography. A carotid artery blood iodine level of 15 mg/ml is required to obtain clear images. The authors conclude that computerized angiotomography is useful in the delineation of unruptured aneurysms.

Adult↗
PubMed1982

Distribution of HBs antigen in livers revealed by orcein staining.

We used the orcein staining method to study the homogeneity of the distribution of HBsAG in complete frontal liver sections from 115 cases with hepatoma, cirrhosis and other liver diseases. The distribution of orcein-positive hepatocytes was usually uniform in non-cancerous liver. In 86% of orcein-positive cases the pattern was homogeneous.

Carcinoma, Hepatocellular↗
PubMed1982

[Rhabdomyosarcoma of the urinary bladder: complete remission induced by vinblastine, cis-platinum, and bleomycin].

Combination therapy consisting of vincristine, actinomycin-D, and cyclophosphamide with or without adriamycin is the most common chemotherapy for rhabdomyosarcoma in childhood. But the effective chemotherapy for rhabdomyosarcoma resistant to these four drugs has not been established. We report a case with rhabdomyosarcoma, which was resistant to these four drugs but responded completely to three drug combination chemotherapy consisting of vinblastine, cis-platinum, and bleomycin (VPB therapy). A 11-months-old boy was referred to us because of giant abdominal tumor. Postoperative diagnosis was Group III embryonal rhabdomyosarcoma of the urinary bladder. Partial resection was followed by vincristine, actinomycin-D, cyclophosphamide, and adriamycin, but his residual tumor was growing. Then VPB therapy was administered and the first course of the chemotherapy reduced the size of tumor. After three courses of VPB therapy the second-look operation was performed. At operation no residual tumor was found and a complete remission was confirmed. During the course of VPB therapy no severe adverse effect was detectable.

Bleomycin↗
PubMed1982

[Pharmacokinetics and clinical evaluation of ceftizoxime (author's transl)].

Pharmacokinetics of ceftizoxime (CZX), a new cephalosporin antibiotic, was investigated in 9 children with normal renal and hepatic function. In addition, the clinical effect of CZX was evaluated in 26 pediatric patients with various infections. In 4 of the 9 children with normal renal and hepatic function, intravenous bolus injection of CZX in a dose of 20 mg/kg yielded a mean peak serum level of 36.5 micrograms/ml at 1/2 hour after infusion, and mean serum levels of 12.5 micrograms/ml at 2 hours and 6.0 micrograms/ml at 4 hours after infusion. The biological half-lives of CZX were estimated to be 1.25--2.55 hours. In another child, serum levels of CZX at 1/2, 2 and 4 hours after intravenous bolus injection in a dose of 10 mg/kg were 19.60, 5.96 and 2.06 micrograms/ml, respectively. The clear difference in dose response between 20 mg/kg and 10 mg/kg reflected the doubled dose levels. In the remaining 4 children, drip infusion of CZX in a dose of 20 mg/kg (1 child 17 mg/kg) over 0.5--1.5 hours yielded peak serum levels at the end of infusion. The biological half-lives of CZX were estimated to be 0.95--1.50 hours. About 80% of CZX was excreted in the urine within 6 hours after infusion in the 4 children tested. Twenty-six pediatric patients with various infections were treated with CZX intravenous doses of 20 mg/kg to 118 mg/kg b.i.d.--q.i.d. for 3--14 days. Of the 12 patients with acute bronchitis and pneumonia, 5 showed excellent response, 6 good and 1 fair response. Of the 5 patients with urinary tract infection, 4 showed excellent response and 1 good response. One patient each with colitis, tonsillitis and facial cellulitis, pharyngitis showed excellent response and 1 patient each with purulent thyroiditis and gluteal abscess showed good response. The single patients with sepsis showed excellent response. One patient each with pyothorax, purulent arthritis and cerebral abscess showed poor response. Overall effectiveness rate was 84.6%. although 22 of all 26 patients treated had serious underlying diseases such as APL, AML. A mild increase in GOT and GPT was observed in 1 patient during treatment with CZX, and the values returned to normal after discontinuation of the drug. These results suggest that ceftizoxime is 1 of the most important antibiotics for treating a wide range of infections in children as well as in adults.

Adolescent↗
PubMed1982

Correlation of karyotype with clinical features in acute lymphoblastic leukemia.

We studied the clinical and karyotypic features of 50 patients with acute lymphoblastic leukemia, including 33 American and 17 Japanese patients, at two institutions. Clonal chromosome abnormalities were found in 39 of the 50 patients (78%) at diagnosis. Eleven patients had diploidy (N patients). Among the 39 aneuploid patients, 17 had pseudodiploidy (A1 patients), eight had hyperdiploidy with 47 to 49 chromosomes (A2 patients), nine had hyperdiploidy with 50 to 59 chromosomes (A3 patients), and five had other chromosome abnormalities. Of 14 patients whose chromosomes were also studied at relapse, eight had karyotypic progression, five had abnormalities identical or similar to those observed at diagnosis, and one had a change of karyotype from diploidy to aneuploidy. The median age and the median WBC of A1 patients were higher than those of any other group of patients, although one-third of the patients had WBC below 20 x 10(3)/microliters, and they often had leukemic cells of T-cell or B-cell lineage. The A2 patients were relatively old and tended to have higher WBC. The N patients were relatively young and tended to have low WBC, although these tendencies were not as marked as those in A3 patients. The A3 patients had longer survival times than the A1 (p = 0.003) or A2 (p = 0.002) patients. Also, N patients had longer survival times than A1 (p = 0.03) or A2 (p = 0.05) patients. The difference in survival times between A3 and N patients was not significant. Our study demonstrated that the karyotype is correlated with survival and with other recognized prognostic factors. However, in some A1 and A2 patients, the karyotype was a more reliable factor in indicating a poor prognosis than was the WBC or age.

Adolescent↗
PubMed1982

[Experience with high-dose methotrexate therapy for malignant solid tumors].

Thirteen patients with malignant solid tumors, mainly osteogenic sarcomas, were treated by high-dose MTX therapy, 50-400 mg/kg, in a total of 72 cycles. It has been proved that this therapy was relatively safe provided careful clinical surveillance were assured. Of 8 patients with osteogenic sarcomas, 6 had no metastatic lesions on the chest X-rays before this therapy: three were alive without any evidence of disease for 18-25 months after high-dose MTX therapy. In some cases of other malignant solid tumors, particularly intracranial tumors, clinical efficacy was observed. Dose-time relationships, etc. should further be studied for more therapeutic efficacies of high-dose MTX therapy.

Adolescent↗
PubMed1982

[A case report of traumatic intracerebral pneumocephalus with interesting CT cisternographic findings (author's transl)].

A 19-year-old boy suffered from headache and intermittent CSF rhinorrhea, was admitted to Matsuyama Shimin Hospital on June 1, 1979. Two months prior to admission he had had a frontal head injury with confusion and the right nasal bleeding. Plain skully x-ray films and biplane (axial & coronal) CT revealed intracerebral pneumocephalus in the right frontal lobe with depressed basal skull fracture into the right ethmoid sinus. Clinical conservative courses of intermittent CSF rhinorrhea, headache and vomiting were related to the changes of the air shadow on plain skull films. Preoperative metrizamide CT Cisternography was done on July 5. Sequential CT cisternograms demonstrated ventricular reflux at 1 hr and partial obstruction of the basal cistern and supratentorial subarachnoid space at 3 hr, which attributed to the mass effect of the air cysts. They also demonstrated an interesting finding, the accumulation of metrizamide into the intracerebral air cyst at 3 hr, suggesting transependymal penetration of contrast medium. At 24 hr, the air cyst decreased in size and the metrizamide disappeared. CT cisternograms 8 months after the surgery showed no evidence of air cyst but remained a low dense porencephalic cyst. Ventricular reflux was seen at 3 and 6 hr but there was no accumulation of metrizamide into the cyst at any hr. Filling patterns of the basal cistern and supratentorial subarachnoid space returned normal except the defect in the anterior interhemispheric cistern. Transependymal penetration of metrizamide in this case can be explained by the mechanism of pressure gradient between the ventricle and the air cyst. Thus the postoperative CT cisternograms showed no penetration because of the absence of pressure gradient, whereas the ventricular reflux and the same ependymal septum still remained. No mention has been made about the CSF flow dynamics in intracerebral pneumocephalus and their relation to the CSF rhinorrhea in previous literature. Intermittent CSF rhinorrhea of this case will attribute to the CSF accumulated in the air cyst as mentioned above.

Adult↗
PubMed1982

[An interesting case of the traumatic middle meningeal arteriovenous fistula].

The authors reported an interesting case of the traumatic middle meningeal arteriovenous fistula which was caused by the minor head injury on the opposite side complicated with a subarachnoid hematoma, and was completely cured 35 days after head injury without any surgical intervention. A 75-year-old woman fell down after unconsciousness fit and hit her right head, then visited Matsuyama Shimin Hospital complaining of nausea, vomiting and severe left temporalgia. Neurologically, no other abnormalities were found. On plain skull roentogenograms, a linear fracture was noted on the right temporal bone, but not on the left side. A subarachnoid hematoma localized in the left Sylvian fissure was identified on plain computed tomograms. Left carotid angiograms revealed the middle meningeal arteriovenous fistula at the left middle fossa, which showed an characteristic drainages, i.e. mainly draining to the pterygoid venous plexus and the superior sagittal sinus, partially to the cavernous sinus. She was admitted to our ward and was treated only conservatively. Thirty-five days after head injury, her complaints improved remarkably and left carotid angiograms, performed on the next day, disclosed complete disappearance of the previous fistula, and suggested the point of fistula clearly. Documenting the computed tomogram and the angiograms of our case, possible mechanism of fistula formation and its spontaneous cure was discussed. The middle meningeal arteriovenous fistula was formed by the interaction between the direct or indirect influence of head injury and anatomical, histological and pathological factors of meningeal vessels themselves. Spontaneous cure of the fistula resulted from thrombosis at the point of fistula. In our case, irregularity of the wall of anterior middle meningeal artery on the repeated angiograms supported this view.

Aged↗