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Biomedical subjects

S Morimoto

Publications and source records attributed to S Morimoto.

At least 307 records · Page 17Linked to original sources
PubMed1993

Phosphoramidon-sensitive endothelin converting enzyme in cultured vascular smooth muscle cells converts big endothelin-3 to endothelin-3.

Incubation of big endothelin-3 (big ET-3, 1-41) with the membrane fraction obtained from cultured vascular smooth muscle cells (VSMCs) resulted in time-dependent increases in immunoreactive-ET (IR-ET), which were suppressed by phosphoramidon. Analysis of the incubation mixture by reverse-phase high performance liquid chromatography (RP-HPLC) confirmed that the IR-ET was due to the mature ET-3 (1-21). ET-1 (1-21) generated during incubation of big ET-1 (1-39) with the membrane fraction was markedly suppressed by the addition of big ET-3 into the incubation mixture. When the cultured VSMCs were incubated with big ET-3, a conversion to the mature ET-3 was observed. This ET-3 generation from exogenously applied big ET-3 was also suppressed by phosphoramidon. We conclude that the phosphoramidon-sensitive ET converting enzyme in VSMCs converts big ET-1 and big ET-3 to their mature form.

Animals↗
PubMed1993

Biodegradable poly(DL-lactic acid) formulations in a calcitonin delivery system.

A synthetic analogue of eel calcitonin, [Asu1, 7]-ECT, was incorporated into biodegradable poly(DL-lactic acids) with number-average molecular weights (Mn) of 1400-4400 by the melt-pressing technique. The in vitro release of drug from a parabolically degradable poly(DL-lactic acid) with Mn = 1400 showed an initial burst release and completed the release in 3 d from the start of the test. The drug release from a Mn = 4400 polymer with an S-type degradation pattern was kept at 14 +/- 5 units/d for an experimental period of 24 d.

Amino Acid Sequence↗
PubMed1993

Cannabis, 21. Biotransformation of cannabinol to its glycosides by in vitro plant tissue.

A marijuana compound, cannabinol [1], was converted to two metabolites using in vitro tissue of Pinellia ternata. The structures of the metabolites were determined to be cannabinol-O-beta-D-glucopyranoside [2] and 9'-hydroxycannabinol-O-beta-D-glucopyranoside [3] by 1H nmr and 13C nmr. From the time course experiments, 1 was absorbed rapidly in the tissues and glycosylated. Hydroxylation at the pentyl group occurred, and its metabolite was secreted in the medium.

Biotransformation↗
PubMed1993

Tissue kallikrein in the rat pineal gland: an immunocytochemical study.

Tissue kallikrein in the rat pineal gland was immunocytochemically investigated with the aid of specific antiserum against rat urinary kallikrein. We also compared the tissue kallikrein immunoreactivity of the pineal gland with that of the submandibular gland and kidney, which have been well established as tissue kallikrein-synthesizing organs. The cytoplasm of pinealocytes from both the superficial and the deep portion of the gland exhibited specific immunolabeling for tissue kallikrein, but the immunoreaction was weaker than that observed in exocrine organs. Two types of tissue kallikrein-immunoreactive pinealocytes were distinguished; the first predominant type displayed moderate immunostaining, whereas a small number of cells, the second type, were so intensely labeled that their cytoplasmic processes were clearly outlined. The results of the present study suggest the existence of different types of pinealocytes and a potential physiological role of tissue kallikrein in the rat pineal gland.

Animals↗
PubMed1993

Pulsed Doppler echocardiographic assessment of portal venous flow patterns in patients after the Fontan operation.

OBJECTIVE: To assess the effect of the condition of the right heart after the Fontan operation on portal venous flow, and to determine whether the characteristics of portal venous flow were different when there was an atriopulmonary connection with atrial septal closure rather than an atriopulmonary or total cavopulmonary connection with intra-atrial routing. PATIENTS AND METHODS: After the Fontan operation six patients with an atriopulmonary connection (group 1), three patients with an atriosubpulmonary connection (group 2), four patients with intra-atrial routing and an atriopulmonary connection (group 3), and five patients with a total cavopulmonary connection (group 4) were studied by pulsed Doppler echocardiography. The flow signals were recorded for the pulmonary artery, hepatic vein, and intrahepatic portal vein in each patient. Postoperative cardiac catheterisation was performed in 16 of the 18 patients. The Doppler findings were compared with those of 14 controls. RESULTS: The portal flow was pulsatile in 13 patients and constant in five patients. Reversed flow was shown at or just after the QRS wave after hepatic venous regurgitation in two group 1 patients. The flow signal was interrupted in two group 1 patients and two group 2 patients. Decrease in velocity of flow was recorded in two group 1 patients, one group 2 patients, three group 3 patients, and one group 4 patient. Portal flow was constant in one group 3 patient and four group 4 patients. The pulsatility ratio ranged from -0.46 to 0.49 (mean (SD), 0.03 (0.32)) in the patients from group 1 and 2, from 0.41 to 0.76 (0.54 (0.15)) in group 3, and from 0.70 to 0.80 (0.75 (0.04)) in group 4. The ratio in the controls ranged from 0.29 to 0.83 (0.61 (0.13)). The ratio was significantly lower in groups 1 and 2 than in group 3 (p < 0.01), group 4 (p < 0.01), or the controls (p < 0.005). There was no significant difference in the ratio between group 3 and group 4 and no correlation between the pulsatility ratio and the cardiac index (r = 0.26), mean right atrial pressure (r = 0.25), or pulmonary vascular resistance (r = 0.17). CONCLUSION: The larger hepatic venous regurgitation caused by atrial contraction in patients with an atriopulmonary connection correlated with the higher portal pulsatility and a total cavopulmonary connection reduced portal pulsatility.

Atrial Function, Right↗
PubMed1993

Captopril inhibits endothelin-1 secretion from endothelial cells through bradykinin.

Incubation with captopril, an angiotensin I converting enzyme inhibitor, for 24 hours at concentrations up to 10(-7) M inhibited endothelin-1 secretion by endothelial cells. This inhibition of endothelin-1 secretion was reversed by coincubation with 3 x 10(-3) M NG-nitro-L-arginine, an inhibitor of nitric oxide synthesis. Furthermore, captopril enhanced the production of nitric oxide in endothelial cells, suggesting that enhancement of nitric oxide production participates in captopril-induced inhibition of endothelin-1 secretion. Moreover, in the presence of 10(-6) M D-Arg,[Hyp3,Thi5,8,D-Phe7]-bradykinin, a bradykinin B2 receptor antagonist, captopril did not inhibit but rather stimulated endothelin-1 secretion, whereas bradykinin inhibited endothelin-1 secretion, and this inhibition by bradykinin was reversed by coincubation with NG-nitro-L-arginine. In addition, enhancement of nitric oxide production induced by either captopril or bradykinin was inhibited by D-Arg,[Hyp3,Thi5,8,D-Phe7]-bradykinin. Although 10(-6) M des-Arg9-[Leu8]-bradykinin, a bradykinin B1 receptor antagonist, did not affect nitric oxide production by bradykinin, it enhanced the inhibition of endothelin-1 secretion by bradykinin. Furthermore, 10(-7) M des-Arg9-bradykinin, a bradykinin B1 receptor agonist, stimulated endothelin-1 secretion by endothelial cells. These findings suggest that angiotensin I converting enzyme inhibitor inhibits endothelin-1 secretion by the accumulation of endogenous bradykinin in endothelial cells and that the inhibition of endothelin-1 secretion by bradykinin is mediated via B2 receptors.

Arginine↗
PubMed1993

Fragmentation of internal elastic lamina and spread of smooth muscle cell proliferation induced by percutaneous transluminal coronary angioplasty.

We investigated smooth muscle cell proliferation associated with restenosis after percutaneous transluminal coronary angioplasty (PTCA) in 8 arteries with fragmented internal elastic lamina obtained at autopsy in 7 patients who died between 2 months to 2 years 11 months after coronary angioplasty. The internal elastic lamina fragmentation, measured longitudinally along the blood vessels, measured 6.6 +/- 6.9 mm. Smooth muscle cell proliferation was concentrated around the fragmented internal elastic lamina, extending longitudinally even to unfragmented areas. The proliferation of smooth muscle cells extended for 1.8 +/- 2.2 mm in the proximal portion of the fragmentation, and for 2.0 +/- 2.9 mm in the distal portion. The possibility of new stenoses resulting from smooth muscle cell proliferation at sites adjacent to those subjected to PTCA should be borne in mind when PTCA of the proximal segments of the left anterior descending coronary artery is contemplated.

Aged↗
PubMed1993

Avascular necrosis of the femoral head. Natural history and magnetic resonance imaging.

We studied the prognostic value of MRI in 32 radiographically normal, asymptomatic hips in 25 patients at risk of osteonecrosis from glucocorticoids or alcoholism. The early findings were band-like hypointense zones on spin-echo images. No operations were performed. Life-table survival curves showed that femoral heads in which the hypointense zone traversed the middle portion of the head were most at risk of subsequent segmental collapse.

Adolescent↗
PubMed1993

Polylactide screws in acetabular osteotomy. 28 dysplastic hips followed for 1 year.

Absorbable polylactide screws were used for internal fixation of rotational acetabular osteotomy (RAO) in 28 dysplastic hips. No cast was used and the patients were allowed to walk with partial weight bearing 1 month after surgery. Clinical and radiographic results were evaluated after 14 (6-24) months. Union occurred in all cases within 4 months without displacement of the osteotomy. No foreign-body inflammatory reaction on radiographs was observed, nor were there any local reactions, such as redness or swelling. Polylactide screws seem to provide sufficient strength for the internal fixation of RAO. Further observation is necessary to identify any late foreign body reaction.

Acetabulum↗
PubMed1993

Chemical modification of erythromycins. IX. Selective methylation at the C-6 hydroxyl group of erythromycin A oxime derivatives and preparation of clarithromycin.

Although erythromycin A contains five hydroxyl groups, regioselective methylation at the C-6 hydroxyl group was achieved to the extent of 90% when a 9-O-substituted erythromycin A 9-oxime was employed as substrate. The methylation and its selectivity are dependent on an O-protecting group at the 9-oxime, solvent, base, and methylating reagent. In particular, the use of a polar aprotic solvent is indispensable for the methylation. Among the 9-oxime derivatives, 2'-O,3'-N-bis(benzyloxycarbonyl)-N-demethylerythromycin A 9-[O-(2-chlorobenzyl)oxime] was the most important intermediate for the synthesis of clarithromycin (6-O-methylerythromycin A).

Clarithromycin↗
PubMed1993

Effects of beraprost sodium, a stable analogue of prostacyclin, on hyperplasia, hypertrophy and glycosaminoglycan synthesis of rat aortic smooth muscle cells.

The effects of beraprost sodium, a stable analogue of prostacyclin, on the syntheses of DNA, protein and glycosaminoglycans (GAG) of cultured vascular smooth muscle cells (SMC) were studied. SMC were isolated from the thoracic aorta of male Wistar rats. The syntheses of DNA, protein and GAG of SMC were determined by incorporations of [3H]thymidine, [3H]leucine and [35S]sulfuric acid, respectively. Insulin at a concentration of 10(-6) M stimulated DNA synthesis 4 fold compared to control. Beraprost sodium suppressed the insulin-stimulated DNA synthesis dose-dependently at concentrations greater than 10(-7) M and suppressed it by 68% at 10(-5) M. Platelet derived growth factor (PDGF) at a concentration of 20 ng/ml stimulated DNA synthesis 6 fold compared to control. Beraprost sodium suppressed the PDGF-stimulated DNA synthesis dose-dependently at concentrations greater than 10(-7) M and suppressed it by 51% at 10(-5) M. Beraprost sodium suppressed GAG synthesis dose-dependently at concentrations greater than 10(-7) M and suppressed it by 49% at 10(-5) M. However, beraprost sodium at concentrations up to 10(-5) M did not affect protein synthesis. These results indicate that beraprost sodium suppressed the proliferation and GAG synthesis of SMC but did not affect hypertrophy. Beraprost sodium may be a potent antiarteriosclerotic agent through suppression of hyperplasia of SMC and modification of matrix protein.

Animals↗
PubMed1993

Plasma lipids and coronary atherosclerosis in Japanese men.

Asians have lower plasma levels of cholesterol than Americans and Europeans, and few studies on lipids as predictors of coronary artery disease in Asians have been performed. Therefore, we analyzed the plasma lipids, lipoproteins and apolipoproteins in Japanese men with angiographically documented coronary artery disease (CAD). Plasma levels of lipids, lipoproteins and apolipoproteins from patients without CAD (33 males with no significant coronary artery stenosis) and patients with CAD (58 males with significant coronary artery stenosis) were compared. In addition, the relationship between plasma lipids and the severity of coronary artery stenosis was determined using a multivariate analysis. For Japanese men, plasma levels of cholesterol and triglycerides do not discriminate between patients with and without CAD. However, low density lipoprotein (LDL) and apoprotein A-1 are good predictors of coronary artery disease in Japanese men. The plasma levels of lipoproteins and apolipoproteins are good predictors of coronary artery disease in populations with a low fat intake and with normocholesteremia and normotriglycemia.

Apolipoproteins↗
PubMed1993

[Rupture of asymptomatic mycotic aneurysm after valve replacement in infective endocarditis].

Mycotic cerebral aneurysms (MCA) are one of the most serious complications of infective endocarditis. The rupture of MCA in patients under anticoagulant therapy following valve replacement carries high mortality. We encountered this serious complication in a patient who had no neurologic symptoms. A 12-year-old girl was scheduled for mitral valve replacement (MVR) 5 weeks after antibiotic therapy for infective endocarditis caused by Staphylococcus aureus. Before the surgery, she did not have any neurologic symptoms or abnormal findings in CT scanning examination. The surgery to remove her mitral valve with bacterial vegetations and replace it with an artificial valve proceeded smoothly and she appeared to begin an uneventful postoperative recovery. However, she suddenly began to complain of severe headache and became unconscious on the fifth days after MVR. A CT scan showed cerebral herniation due to a major subdural hematoma. A ruptured MCA was detected in the orbito-frontal artery and clipped in an emergency operation. She was transferred to the intensive care unit and given continuous infusion of barbiturate to prevent increase of her intracranial pressure. CT scanning and arteriography 10 days after the MCA clipping, revealed a new subdural hematoma and MCA just proximal to the previous clip. It is important to bear in mind that patients with infective endocarditis can have mycotic cerebral aneurysms without any clinical neurologic symptoms.

Adolescent↗
PubMed1993

[Effective regimen for eradication of Helicobacter pylori].

There is now substantial evidence that Helicobacter pylori (H. pylori) is both a frequent cause of chronic gastritis and an important factor in the recurrence of duodenal ulcer. However, to achieve the eradication of H. pylori is very difficult and although a number of treatment regimens suppress this organism, the stomach usually becomes recolonized shortly after the cessation of treatment. Many reports have shown that polytherapy is more effective than monotherapy. And so, the best results have been achieved with triple therapy using combination of bismuth, metronidazole, or tinidazole, and amoxicillin or tetracycline. The factor influencing effectiveness of triple therapy is compliance with the prescribed medications. And so, short term triple therapy is highly effective and well tolerated.

Anti-Bacterial Agents↗
PubMed1993

Mechanism of gravity-dependent atelectasis. Analysis by nonradioactive xenon-enhanced dynamic computed tomography.

RATIONALE AND OBJECTIVES: The physiologic mechanism of gravity-dependent atelectasis (GDA), a common finding identified during anesthesia, is not well understood. The purpose of this study was to determine whether an inherent reduction in alveolar volume or a reduction in alveolar ventilation is the more important causative factor for the development of GDA in an experimental animal model. METHODS: After uniform reduction of lung volume in ten rabbits by artificially induced pneumoperitoneum, dynamic inhalation computed tomography (CT) was performed using 50% nonradioactive xenon in oxygen. Time-CT attenuation value curves were fitted to an exponential function, CT value = a - b x e(-kt), and K value, which is proportional to the alveolar ventilation/alveolar volume ratio, was calculated by regression analysis. RESULTS: Gravity-dependent atelectasis occurred only in 5 of 10 rabbits. In this group, K values in the dorsal regions increased before the appearance of GDA. No significant change in K values in the ventral regions was observed. CONCLUSION: One mechanism of GDA may be a preferential reduction in alveolar volume without small airway collapse rather than alveolar volume loss secondary to decreased ventilation.

Animals↗