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Biomedical subjects

A Shibata

Publications and source records attributed to A Shibata.

At least 325 records · Page 18Linked to original sources
PubMed1991

Anesthetic-protein interaction: effects of volatile anesthetics on the secondary structure of poly(L-lysine).

Effects of volatile anesthetics (chloroform, halothane, and enflurane) on the secondary structure of poly(L-lysine) were analyzed by circular dichroism (CD). The relative proportions among alpha-helix, beta-sheet, and random-coil conformations were calculated by the curve-fitting method on the CD data. Volatile anesthetics partially transformed alpha-helix to beta-sheet but not to random-coil under the present experimental condition. When expressed by the anesthetic partial pressures in the gas phase in equilibrium with the solution, the values that partially transformed alpha to beta conformation by 10% were 1.1 x 10(-2), 4.7 x 10(-2), and 7.9 x 10(-2) atm for chloroform, halothane, and enflurane, respectively. The order of potency is in reasonable agreement with the order of the anesthetic potencies of the agents. The alpha-to-beta transition was completely reversible when anesthetics were purged by nitrogen gas. Volatile anesthetics disrupted the hydrogen bonds of alpha-helix backbones and rearranged them to form the beta-sheet conformation. The beta-sheet conformation is stabilized mainly by the hydrophobic interaction among methylene side groups of poly(L-lysine). Volatile anesthetics promoted the transition by enhancing the hydrophobic interaction among side-chains and by rearranging the hydrogen bonds in the peptide backbone.

Chloroform↗
PubMed1991

Serum erythropoietic inhibitors in patients with pure red cell aplasia.

Inhibitory mechanisms of erythropoiesis in 20 patients with pure red cell aplasia (PRCA) were investigated using the technique of in vitro hematopoiesis and an assay for human parvovirus. Complement-dependent serum inhibitors against late erythroid progenitors (CFU-E) were demonstrated in seven of 19 patients examined, and complement-dependent inhibitors against early erythroid progenitors (BFU-E) were demonstrated in three of these seven patients. Nonspecific and complement-independent inhibitors against CFU-E were thought to be associated with the etiology of PRCA in one patient. Human parvovirus-mediated erythropoietic suppression was demonstrated in a patient with complete remission of acute lymphoblastic leukemia complicated with marrow erythroid aplasia, whose serum showed a perfect inhibition against erythroid progenitor cells. T-cell-mediated erythroid suppression was not demonstrated in the patients examined. These findings reveal that erythroid aplasia is associated with complement-dependent serum erythropoietic inhibitor in some patients (36.8% in the present study) with PRCA, but it is difficult to identify the mechanism of erythroid aplasia in more than half of the patients with PRCA. In addition, our present study discovered the presence of parvovirus-mediated marrow pure red cell aplasia in one adult patient with acute lymphoblastic leukemia.

Adult↗
PubMed1991

Successful treatment of chronic idiopathic neutropenia using recombinant granulocyte colony-stimulating factor.

A patient with chronic idiopathic neutropenia, who had been suffering from repeated infections, was successfully treated with recombinant granulocyte stimulating factor (rhG-CSF). Subcutaneous injection of 30 micrograms/m2 rhG-CSF every two days was sufficient to maintain the neutrophil count at approximately 1,000/microliter. The patient has lived without any evidence of infection for the last 10 months using that treatment. There were no side effect caused by rhG-CSF and antibodies against G-CSF were not detected in the patient's plasma.

Granulocyte Colony-Stimulating Factor↗
PubMed1991

Effect of direct intracoronary administration of methylergonovine in patients with and without variant angina.

The effects of intracoronary administration of methylergonovine were studied in 21 patients with variant angina and 22 patients with atypical chest pain and in others without angina pectoris (control group). Methylergonovine was administered continuously at a rate of 10 micrograms/min up to 50 micrograms. In all patients with variant angina, coronary spasm was provoked at a mean dose of 28 +/- 13 micrograms (mean +/- SD). In the control group neither ischemic ST change nor localized spasm occurred. The basal tone of the right coronary artery was significantly lower than that of the left coronary artery. The percentage of vasoconstriction of the right coronary artery was significantly higher than that of the left coronary artery. These results suggest that spasm provocation tests, which use an intracoronary injection of a relatively low dose of methylergonovine, have a high sensitivity in variant angina and the vasoreactivity of the right coronary artery may be greater than that of the other coronary arteries.

Adult↗
PubMed1991

Low-energy catheter electrical ablation for sustained ventricular tachycardia.

Catheter electrical ablation using a relatively low level of energy--40 to 100 joules--was attempted in 12 consecutive patients with drug-refractory sustained ventricular tachycardia (VT). They had 19 monomorphic VTs, and ischemic heart disease was found as the underlying heart disease in one, nonischemic heart disease was found in nine, and no structural heart disease was seen in two patients. Electrical discharge was delivered at the site of the earliest endocardial activation in 17 VTs, and at the slow conduction area in two VTs. Among 19 VTs in 12 patients, 12 VTs (63%) in seven patients (58%) were successfully ablated and became noninducible during electrophysiologic study. There were no major complications, but transient atrioventricular block occurred in one patient and transient friction rub occurred in another. Delivered electrical energy and the time interval between the local electrogram and the surface QRS did not correlate with the clinical outcome of the procedure. However, "excellent" pace-mapped QRS morphology was obtained from the site of earliest activation or from the slow conduction area in 9 of 12 VTs in the successful cases but in only one of seven VTs in the unsuccessful cases. Low-energy catheter electrical ablation seems to be a satisfactory therapeutic procedure compared with the conventional method that uses an energy level of 200 joules or higher.

Adult↗
PubMed1991

Gene transfer into human leukemia cell lines by electroporation: experience with exponentially decaying and square wave pulse.

The efficiency of gene transfer into human leukemia cell lines by electroporation was investigated. For both transient expression (beta-galactosidase gene) and stable transformation (neomycin resistance gene), the transfer efficiency into leukemia cell lines using a square wave pulse was superior to that using an exponentially decaying wave. The transfer rate of pMoZtk (containing beta-galactosidase gene) into K562 by electroporation using a square wave was approximately 5%, compared with 1% by an exponentially decaying pulse. Whereas the transfer rate of pMAM-neo into K562 by electroporation using an exponentially decaying pulse was less than 10(-5), a square wave generated much more efficient introduction rate of nearly 10(-3). In the other leukemia cell lines also, some square wave yields were better than exponential yields and all square wave yields were at least as good as the exponential yields.

Blotting, Southern↗
PubMed1991

Experimental giant cell myocarditis induced by cardiac myosin immunization.

To identify a cardiac protein that could cause a serious autoimmune myocarditis, membranous proteins and myosin as antigens were investigated. In mice immunized with membranous proteins, the lesions induced were limited on the histological level. On the other hand, in Lewis rats immunized with cardiac myosin, serious myocarditis was induced. Every rat showed evidence of heart failure which was fatal in a few. Histology disclosed extensive cell infiltrates and myocardial necrosis. Among those lesions, giant cells were present. This myocarditis could be also transferred adoptively by lectin-activated spleen cells, T-lymphocytes, but not by IgG fraction. Thus, cardiac myosin can induce autoimmune giant cell myocarditis in Lewis rats.

Animals↗
PubMed1991

Abnormal granulopoiesis of leukemic cells with basophil/mast cell features. Cytochemical and ultrastructural observations.

We have carried out cytochemical and ultrastructural examination of human leukemic cells showing basophil/mast cell features derived from patients with acute myelogenous leukemia or basophilic crisis in chronic myelogenous leukemia. Leukemic cells in each case initially showed metachromasia with toluidine blue and various degrees of positivity for astra blue. Other cytochemical results showed considerable variety among cases. The number of granules increased in short-term culture in every case. Ultrastructurally, small membrane-bound granules with or without myelinoid bodies or glycogen particles were present in immature blasts, followed by production of other granule types. In some cases, leukemic cells before and after liquid culture contained the typical basophil granules with or without myelinoid bodies, but the matrix was more loose than normal. Granules showing whorl or scroll matrix profiles, which were typical for mast cells, were present in two cases. In one case, immature leukemic cells contained theta granules, and some mature forms after short-term culture contained typical basophil/mast cell granules as well as theta granules. Leukemic cells occasionally contained multivesicular granules predominantly. These results indicate that leukemic cells with basophil/mast cell features show a heterogeneous configuration and contain abnormal granules differing from normal ones. This abnormal granulopoiesis may be attributable to the results of leukemic events and may be a hallmark for recognition of leukemic basophils/mast cells.

Adolescent↗
PubMed1991

Entrainment of ventricular tachycardia in arrhythmogenic right ventricular tachycardia.

In two patients with arrhythmogenic right ventricular dysplasia (ARVD), sustained ventricular tachycardia (VT) was induced by programmed stimulations during serial drug testings. One patient had five and the other had two VT morphologies, and the sites of origin were determined by endocardial catheter mappings. When overdrive pacing was performed, constant fusion in the QRS complex was observed in the two patients. Constant fusion of a different degree was also observed at different paced cycle lengths. Both patients had dilated right ventricles and wall-motion abnormality, and the diagnosis of ARVD was further confirmed by the specimen resected at the site of origin of VT. Therefore, VT in ARVD can be entrained and reentry is the most likely mechanism of such VT.

Adult↗
PubMed1991

Experimental study about removal of the implanted tined polyurethane ventricular lead by radiofrequency waves through the lead.

Polyurethane pacemaker leads are widely used nowadays. However, only a few studies have been done to investigate the fixation mechanism of polyurethane leads. To elucidate how pacemaker leads are fixed at the early phase after implantation, polyurethane-insulated tined ventricular leads were implanted in seven mongrel dogs. One to 4 months later, tips of the leads were anchored among the trabeculae and the distal part of the leads were encapsulated by whitish fibrous tissue. It was found that not organized thrombi, but cell reaction with various stages of inflammatory cells was responsible for forming the fibrous tissue. We attempted to remove the lead by delivering radiofrequency wave through the lead. However, no lead could be removed.

Animals↗
PubMed1991

Characteristics of giant cells and factors related to the formation of giant cells in myocarditis.

Giant cell myocarditis is a serious and frequently fatal inflammatory heart disease of which the etiology remains unknown. In the present study, we investigated the origin of multinucleated giant cells in myocarditis with the use of an experimental model. We also examined the factors relating to the formation of giant cells in myocarditis. Severe myocarditis characterized by the appearance of multinucleated giant cells was induced in Lewis rats by immunization with cardiac myosin in complete Freund's adjuvant. Two types of giant cells, foreign body giant cell-like and myocytelike, were observed in this myocarditis. Immunohistochemical studies revealed that both types of multinucleated giant cells were stained with OX42 and ED1 (macrophage markers) and were not stained with anti-desmin antibody and HHF35 (markers for muscle fibers). Therefore, it is likely that multinucleated giant cells in this myocarditis are derived from macrophages. During the course of the disease, the appearance of multinucleated giant cells was restricted to a period corresponding with the fulminant phase of inflammation. When the severity of the disease was modulated by immunization with various doses of the antigen, multinucleated giant cells appeared only in severe myocarditis after inoculation of a large dose of the antigen. Administration of immunoadjuvants also affected the formation of giant cells. Most of the rats injected with cardiac myosin in complete Freund's adjuvant developed giant cell myocarditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Changes in alpha 1- and beta 1-adrenergic receptors and calcium ion binding sites in the fetal myocardium of spontaneously hypertensive rats (SHR).

The present study examined changes in [3H]prazosin, [125I]iodocyanopindolol and [3H]nitrendipine binding to alpha 1- and beta 1-adrenergic receptors and Ca2+ binding sites of cardiac muscle isolated from fetal Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR), using the radioligand binding assay method. The catecholamine concentration in the cardiac muscle of both groups was also determined. The Bmax values in beta 1-adrenoceptors and Ca2+ binding sites in SHR cardiac muscle were lower than those of WKY, but values for SHR alpha 1-adrenoceptors were higher than those of WKY. The Kd values of beta 1-adrenoceptors in cardiac muscles of SHRs were also lower than those of WKY. On the other hand, there were no differences between the catecholamine concentrations in fetal SHR and WKY cardiac muscles. Thus, significant differences in both alpha 1- and beta 1-adrenoceptors and Ca2+ binding sites were already present in fetal SHR hearts, thus suggesting that the changes in fetal hearts of SHRs may be caused by genetic defects in the mother rats at early age.

Animals↗
PubMed1991

Proarrhythmic effects of antiarrhythmic drugs assessed by electrophysiologic study in recurrent sustained ventricular tachycardia.

Proarrhythmic responses were evaluated in repeated electrophysiologic studies (EPS) in 27 patients with inducible ventricular tachycardia (VT). Class Ia drugs were administered to 23, Ib to 6, Ic to 4, III to 5 and IV to 9 patients. The mean age was 53 years, and 18 patients had structural heart diseases. Pleomorphism was observed in 11 patients. In 4 patients (15%), the VT cycle length (CL) shortened by 50 ms or more in EPS during the administration of antiarrhythmic drugs. VT was inducible by a less aggressive induction mode than the control study in 9 patients (33%). In 4 patients (15%), the induced VT changed to the incessant form, and the other 2 patients (7%) required DC shocks due to hemodynamic deterioration. Patients with pleomorphic VT and/or structural heart diseases seemed to develop proarrhythmia more frequently. In total, some proarrhythmic response was observed in 13 (48%) of the 27 patients. Therefore, it should be kept in mind that proarrhythmic effects are frequently observed during antiarrhythmic therapy in patients with sustained VT. The action of the drugs on the slow conduction zone may vary, which may provide a basis for the development of proarrhythmia.

Anti-Arrhythmia Agents↗
PubMed1991

Aortitis syndrome, coronary artery ectasia, and mid-ventricular obstruction.

A 46-year-old Japanese woman, who had been diagnosed as having aortitis syndrome 4 years earlier, was admitted to our hospital in May 1989. The diagnosis of aortitis syndrome was confirmed by intravenous digital subtraction angiography which showed stenotic lesions in each subclavian artery, the left common carotid artery, and the descending aorta. Coronary arteriography revealed diffuse and prominent dilatation of entire coronary artery segments. Moreover, a left ventriculogram showed complete obstruction of the mid-ventricle during systole. Thus, we diagnosed this case as aortitis syndrome complicated by coronary artery ectasia and mid-ventricular obstruction. The causal relations of these findings are discussed.

Adult↗
PubMed1991

Effects of lidocaine on ischemic myocardial metabolism assessed by 31P-NMR in the isolated perfused rat heart.

Using an isolated perfused rat heart preparation, the protective effects of lidocaine and diltiazem on ischemic derangements of myocardial energy metabolism were studied with 31P-nuclear magnetic resonance spectroscopy. The hearts were perfused with a solution containing lidocaine (4.27 x 10(-5), 12.80 x 10(-5) M) or diltiazem (2.22 x 10(-7), 2.22 x 10(-6) M) for 15 min prior to the induction of global ischemia. The decrease in myocardial oxygen consumption rate, assessed as the product of heart rate and left ventricular systolic pressure (HR x LVP), was greater in diltiazem-treated than in lidocaine-treated hearts. Diltiazem and lidocaine significantly retarded the fall in myocardial pH during ischemia and improved ATP recovery after reperfusion. There was a good correlation between suppression of HR x LVP observed before induction of ischemia and decreased drop in pH during the early phase of ischemia in the diltiazem-treated groups (r = -0.78, p less than 0.01), but not in the lidocaine-treated groups. These results indicate that the beneficial effects of diltiazem on the ischemic myocardium are due primarily to the cardio-depressant effects. The beneficial effects of lidocaine cannot, however, be explained solely on the basis of the depression of oxygen consumption.

Animals↗
PubMed1991

Hypereosinophilic syndrome associated with obliterative left ventricular chamber and systemic obliterative arteriosclerosis.

An extremely rare case of hypereosinophilic syndrome is reported. The patient had congestive heart failure due to left ventricular obliteration by a giant thrombus in the apex. Arteriosclerosis obliterans resulted in serious lower extremity gangrene. Combination therapy with a corticosteroid and hydroxyurea caused a marked reduction in eosinophil count, and heart failure recovered in stages. Although the patient was discharged, he returned to our hospital 3 months later with acute myeloblastic leukemia and subsequently died of respiratory failure with pneumonia.

Arteriosclerosis Obliterans↗
PubMed1991

Reproducibility of reports of past history, smoking, drinking and dietary habits obtained by a personal interview for a case-control study on liver cirrhosis and hepatocellular carcinoma.

The reproducibility of responses on life style measurements observed during a personal interview was assessed by a test-retest method. Fifty-one apparently healthy male subjects were interviewed twice, mostly within a 10 week interval. Responses on past history, smoking and drinking habits yielded relatively high intraclass correlation coefficients between the two interviews, as compared to the responses on dietary habits for the previous 1 to 2 years, which varied depending on the food items.

Adult↗