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Biomedical subjects

H Higashi

Publications and source records attributed to H Higashi.

At least 271 records · Page 15Linked to original sources
PubMed1980

Sister chromatid exchanges in lymphocytes of cancer patients receiving mitomycin C treatment.

Peripheral lymphocytes from cancer patients receiving mitomycin C treatment were examined for cytogenetic effects. The treatment consisted of i.v. injections of mitomycin C at a dose of 4 mg given twice a week for 2 weeks. The lymphocytes were cultured in vitro for 72 hr with phytohemagglutinin and 5-bromodeoxyuridine, and then sister chromatid exchanges were scored. Before treatment with mitomycin C, the frequencies of sister chromatid exchanges in lymphocytes of cancer patients were similar to those of healthy controls. After the first and second treatments in vivo with mitomycin C, the frequencies of sister chromatid exchnages increased with time, reached a peak in about 24 hr, and then returned to the pretreatment level in about 48 hr, in contrast to the case of in vitro exposure to mitomycin C. After the third and fourth injections, however, the frequency increased further and did not return to the original level. The significance of the specific kinetics of change in the sister chromatid exchnage frequency after in vivo treatments is discussed in relation to cancer chemotherapy.

Adult↗
PubMed1978

Characterization and ionic basis of GABA-induced depolarizations recorded in vitro from cat primary afferent neurones.

1. Responses of single cells in the isolated cat spinal ganglion to GABA applied by superfusion or by iontophoresis were recorded using intracellular micro-electrodes. 2. Of the twelve structurally related compounds investigated, GABA was the most effective in its ability to produce a depolarization of the cell membrane. 3. Studies determining concentration-response relationships indicate that two to three molecules of GABA are required to combine with the GABA receptor for activation. 4. Bicuculline and picrotoxin, each act in a non-competitive manner to antagonize the GABA-induced membrane current. 5. The equilibrium potential for iontophoretically induced GABA depolarizations (EGABA) was found to be -23.5 plus or minys 6.1 mV. EGABA was independent upon [cl-]o, but independent of [Na+]o, [K+], or [Ca2+]o. 6. Intracellular injection of twenty antions (Br-, I-, NO2-, NO3-, ClO4-, SCN-, Bf4-, HS-, OCN-, ClO3-, BrO3-, F-, HCO2-, HSO3-, HCO3-, CH3CO2-, SO42-, C6H5O73-) indicated that the activated GABA receptor membrane was permeable to those anions whose hydrated diameter is no larger than that of ClO-3. 7. Restoration of the GABA depolarization to its control level after augmentation by Cl- injection had a mean time constant of 27.8 plus or minus 2.6 min. Picrotoxin did not alter this value. 8. When foreign anions were exchanged for Cl- in the perfusion solution, the ten anaions smaller or equal to ClO3-, decreased the GABA depolarization by 50-90% and increased its time course 1.5-2.0 x control. The only exception having a small radius was Br- which augmented the amplitude 10-30%. 9. The ten anions larger than ClO3- produced a biphasic effect, i.e. an initial augmentation followed by a marked (up to 100%) depression of the response. Experiments with CH3COO-, CH3SO4-, or HOCH2CH2SO3-, indicated that this depression was non-competitive.

Aminobutyrates↗
PubMed1978

[A case of giant aneurysm at the posterior cerebral artery (author's transl)].

Giant aneurysm of the posterior cerebral artery was very rare. The authors could seek only 6 cases in published literature. We experienced one case of the giant aneurysm at the posterior cerebral artery. The case was 25 years old female. She occasionaly complained of headache and nausea for 4 years before administration. Cerebral angiogram revealed a giant aneurysm of the right posterior cerebral artery with slightly dilated ventricle. CT scan revealed a ring shape high density area and its high density area enhanced by Conray infusion. A clipping of posterior cerebral artery at the just proximal point of the aneurysmal neck was done, because adhesion of the aneurysm to the brain stem was very tight and the aneurysmal neck was very broad. After the operation, giant aneurysm was not seen on both angiogram and CT scan. Patient did not complain of headache any more and any defect of the visual field.

Adult↗
PubMed1977

[A case of medullary thyroid carcinoma with ectopic ACTH syndrome (author's transl)].

A 53-year-old male with Cushing's syndrome due to ectopic ACTH production from medullary carcinoma of the thyroid was reported. The clinical course and results of detailed endocrinological studies and immunohistochemical findings about the cancer tissue were described. An abnormally high concentration of calcitonin, ACTH and beta-MSH in both plasma and cancer tissue (thyroid, lymph nodes and liver) were documented by radioimmunoassay. Urinary 17-OHCS was as high as 38.4 mg/day and showed no supression following dexamethasone 8 mg/day administration. ORAL METYRAPONE (3 G/DAY) CAUSED NO RESPONSE IN URINARY 17-OHCS. Parallel increments in plasma calcitonin, ACTH and beta-MSH were observed following calcium and gastrin loading. Total thyroidectomy with modified radical neck dissection caused minimal changes of plasma levels of calcitonin, ACTH and beta-MSH and no improvement in the clinical manifestations of Cushing's syndrome. An aortogram revealed metastatic tumors in the liver. A second operation, total adrenalectomy, resulted in an improvement of the clinical and laboratory findings such as hypokalemia, high blood pressure, muscle atrophy and moon face. Immunofluorescent study showed different distribution patterns in calcitonin- and ACTH-positive cells in the primary focus but similar patterns in the liver metastasis.

Adrenalectomy↗
PubMed1976

Intracellular distribution of (14C)bleomycin and the cytokinetic effects of bleomycin in the mouse tumor.

The differential effects (BLM) on cycling and noncycling cells were investigated with a mouse ascites tumor in vivo. An i.p. injection of 37.0 or 111.1 mug BLM per g caused a decrease in tumor cell number but an increase in percentage of tumor cells in mitosis. There are no significant differences between the percentage labeled mitoses at various times after pulse labeling by tritiated thymidine of BLM-treated tumor cells and by that of an untreated control, except that the height of the second peak was significantly lower in the treated cells. Hence BLM may be cell cycle nonspecific, and the BLM-induced decrease in cell number, i.p., may stimulate some nondividing cells to reenter the division cycle. However, the fact that percentage of cells in mitosis versus time after the administration of BLM showed two peaks indicates the possibility that another cause of the increase in mitotic figures might be a relative increase of cycling cells due to higher sensitivity of noncycling cells to the agent. Autoradiographic studies on the intracellular distribution of [14C]BLM revealed the following. (a) There were few necrotic cells in mitosis that incorporated much [14C]BLM into the cytoplasm at each time point and the mitotic figures gradually increased with time after i.p. injection of the isotope, while necrotic cells other than in mitosis, most of which were heavily labeled, increased in number with time. These findings seem to be related to the possibility that cycling cells may be less sensitive to BLM. The mode of intracellular distribution of [14C]BLM in mitotic cells changed with time and appeared to reflect the drug susceptibility depending on the cell cycle phase when labeled.

Animals↗