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Biomedical subjects

M Morikawa

Publications and source records attributed to M Morikawa.

At least 253 records · Page 14Linked to original sources
PubMed1986

Sensitivity of preadipose 3T3 cells to growth hormone.

Cultured preadipose 3T3 cells are able to undergo a process of differentiation through which they are converted into adipose cells. Growth hormone induces this conversion in resting cultures but not in growing cultures. It was of interest to determine the period of cell sensitivity to the hormone and the timing of the induction of glycerophosphate dehydrogenase, a key enzyme in lipogenesis. It was found that 3T3-F442A cells became highly sensitive to rat growth hormone at confluence but that high sensitivity remained for only 3 days; thereafter, the responsiveness to the rat growth hormone declined rapidly. Refeeding of the cells with fresh medium did not lead to the recovery of the hormone sensitivity, indicating that the decrease in sensitivity was not due to exhaustion of medium components but that it seemed to be a specific property of F442A cells. As glycerophosphate dehydrogenase activity was detected at nearly the same time as its mRNA was measurable, it is likely that the mRNA is translated immediately after its synthesis.

Adipose Tissue↗
PubMed1986

Recurrent paroxysmal hypotension and bradycardia in a patient with pharynx tumor metastasis to the cervical lymph nodes.

In a 64-year-old male, recurrent syncope, hypotension and bradycardia developed repeatedly. The systolic blood pressure fell and could not be measured by auscultation method and the heart rate decreased to under 20 bpm. He recovered from unconsciousness in several minutes. No precipitating cause was apparent for such episodes. Physical examination revealed swollen lymph nodes in the upper cervical regions. Carotid sinus massage caused a fall of systolic blood pressure by 40 mmHg and the P-P interval lengthened to 1.96 sec. The otolaryngeal examination showed neoplasma in the pharynx. He received irradiation therapy on the primary lesion and the bilateral metastatic lesions. After irradiation (4,000 rad), the paroxysmal hypotension and bradycardia disappeared concomitantly with the reduction in size of the metastatic tumor. Hypersensitivity to carotid sinus massage, however, remained unchanged. In this case, the metastatic tumor around the carotid sinus seemed to be related to the syncope and the hemodynamic collapse.

Bradycardia↗
PubMed1986

Late sustained ventricular tachycardia after complete repair of tetralogy of Fallot--a case report.

A female patient had recurrent sustained ventricular tachycardia (VT) as a late sequela after complete repair of tetralogy of Fallot, and the clinically documented VT could be induced and terminated in a reproducible manner by programmed stimulation. VT was accompanied by fragmented electrical activities when the electrode was positioned at the outflow tract of the right ventricle where myotomy was added on the previous scar. The electrophysiological study revealed that the mechanism of VT was re-entry and that the focus of VT was located at the right ventricular outflow tract.

Adult↗
PubMed1986

Long-term postoperative status of tetralogy of Fallot.

From 1965 to 1984, 279 patients with tetralogy of Fallot underwent corrective surgery at Niigata University Hospital, and 228 patients were closely followed postoperatively. Late deaths occurred in 12 cases (5.3%), and overall event-free rate at 20 years postoperatively was 76.9%. The most common events were heart failure due to residual cardiac anomaly and symptomatic ventricular arrhythmias. Treadmill test by Ellestad protocol was performed on 74 postoperative patients, 49% of whom could not complete the protocol. These patients had higher RVEDP and lower RVEF than completing patients. Holter ECG was done on 48 long-term postoperative patients, 48% of whom showed complex ventricular arrhythmias. The age at operation was older and postoperative elapsed time was longer in patients with complex ventricular arrhythmias. Although most postoperative TF patients are able to enjoy a normal social life, the treadmill test and Holter ECG revealed that many patients had latent RV dysfunction and complex ventricular arrhythmias with or without significant symptoms. Since the number of symptomatic patients increases after 15 years postoperatively, a regular check-up with cautious observation is important for the patients' care.

Arrhythmias, Cardiac↗
PubMed1986

Sex difference in the effect of aspirin on intracellular Ca2+ mobilization and thromboxane A2 production in rat platelets.

The intracellular Ca2+ mobilization in thrombin-stimulated platelets was greater in male rats than in female rats. Thromboxane (TX) B2 production in male platelets was greater than that in female platelets. Aspirin suppressed Ca2+ mobilization in rat platelets, but the inhibitory effect of aspirin was more efficient in males than that in females. Aspirin inhibited TXB2 production, and this inhibitory effect of aspirin was stronger in male platelets than in female platelets. Castration decreased Ca2+ mobilization and TXB2 production and weakened the effect of aspirin on them. It is suggested that the sex difference in the antiplatelet effect of aspirin results from the difference in the inhibition of Ca2+ mobilization via the inhibition of TXA2 production in thrombin-stimulated rat platelets.

Animals↗
PubMed1986

Comparison of the inhibitory effects of aspirin and ticlopidine on platelet aggregation and Ca2+ mobilization in rat platelets.

To study the cause of the sex difference in the inhibitory effects of aspirin on platelet functions, we compared the effects of aspirin and ticlopidine in rat platelets. Aspirin showed the sex difference in the effects on the collagen-induced platelet aggregation and the malondialdehyde (MDA) production, but ticlopidine showed no sex difference in the effects on those. The C-AMP level in male rat platelets was the same as that in female rat platelets. Ticlopidine increased the C-AMP level in rat platelets, but aspirin did not. Aspirin suppressed the intracellular Ca2+ mobilization in male rat platelets more strongly than in female rat platelets. Ticlopidine suppressed the Ca2+ mobilization in both sexes equivalently. The above results suggest that the sex difference in the inhibitory effects of aspirin on rat platelet functions comes from the sex difference in the thromboxane (TX) production in rat platelets.

Animals↗