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Biomedical subjects

M Shiba

Publications and source records attributed to M Shiba.

At least 55 records · Page 3Linked to original sources
PubMed1998

Suppressive effect of oestradiol on chemical hepatocarcinogenesis in rats.

AIMS: To examine the effects of oestradiol and testosterone on the early carcinogenic changes expressed in rat liver from the diethylnitrosamine (DEN), 2-acetylaminofluorene (AAF), partial hepatectomy (PH) model of hepatocarcinogenesis. METHODS: Preneoplastic liver lesions were evaluated using immunohistochemical analysis of glutathione-S-transferase placental form (GST-P) expression; oestrogen and androgen receptor levels were measured by radioimmunoassay. RESULTS: Oestradiol administration to non-castrated DEN-AAF-PH treated males resulted in a decrease in the area of GST-P positive foci, while testosterone increased the serum oestradiol level and reduced the area. In males, castration alone and castration with oestradiol replacement significantly reduced the GST-P positive area, and increased the hepatic oestrogen receptor level. In DEN-AAF-PH treated females, castration with testosterone replacement was associated with a significant increase in the GST-P positive area and the hepatic androgen receptor level. CONCLUSION: These findings suggest that exogenous and endogenous oestradiol can suppress chemical hepatocarcinogenesis. It appears that oestrogen receptors may be involved in the inhibition of malignant transformation of preneoplastic liver cells, while androgens and androgen receptors are involved in hepatocarcinogenesis.

2-Acetylaminofluorene↗
PubMed1998

Intracoronary acetylcholine-induced prolongation of monophasic action potential in long QT syndrome.

Two patients with long QT syndrome, who had episodes of syncope, underwent recordings of the monophasic action potential (MAP) from the right ventricle. Intracoronary administration of acetylcholine (ACh) induced prolongation of MAP duration and caused Torsade de Pointes (Tdp) in both patients. In one patient, intravenous atropine administration did not induce any change in MAP duration. In the other patient, ACh was administered after atropine. According to the results of the present study, abnormal regulation of the muscarinic receptor-mediated K-channel may be involved in the mechanism causing prolongation of MAP duration caused by ACh administration.

Acetylcholine↗
PubMed1997

Bradykinin generation in RC-MAP during storage at 4 degrees C and leukocyte removal filtration.

We investigated contact system activation in red cell concentrate in mannitol-adenine-phosphate (MAP) solution (RC-MAP) during storage and leukocyte removal filtration. The contact system activation was assessed in terms of bradykinin (BK) generation. The BK level in the RC-MAP transiently but significantly (p < 0.05) increased at 7 to 14 days of storage. Moreover, the BK level in 21-day-stored RC-MAP was approximately 10 times higher than that in other blood components. The BK level in mannitol-containing MAP solutions, but not that in mannitol-free MAP solution, saline or whole blood, increased during storage. The plasma angiotensin-converting enzyme (ACE) activity decreased significantly only in mannitol-containing MAP solutions. These findings suggest that mannitol plays an essential role in the increase in BK level in RC-MAP. Furthermore, the BK level in RC-MAP increased 10 minutes after the start of filtration through a negatively charged filter, either a BPF-4 or an RN-40, and reached a maximum of 6,000 pg/ml. Hypotensive reactions are rare in RC-MAP transfusion in comparison to their incidence in platelet concentrate (PC) transfusion in spite of the higher BK level in RC-MAP than in PC. Therefore, BK generation in various blood components is not likely to be the main cause of hypotensive reactions. However, the level of BK in RC-MAP is sufficiently high to cause site pain. Further investigation on the clinical significance of a high BK level in blood components is necessary.

Adenine↗
PubMed1997

Mutations in a hydrophilic part of the core gene of hepatitis C virus in patients with hepatocellular carcinoma in China.

We investigated the association between hepatocellular carcinoma (HCC) and the genomic characteristics of the hepatitis C virus (HCV) isolated from residents of the inshore region of the Yangtze River, an area that has one of the highest incidence of HCC in China. We determined the genomic heterogeneity of HCV, and the sequence divergence of the HCV core gene in individuals with chronic hepatitis and HCC. HCV genotype II was predominant among these isolates, which were homologous to other Chinese and Japanese HCV isolates. The rate of nucleotide substitutions in the core gene was significantly greater for isolates from HCC patients than for those from individuals with chronic hepatitis. The nucleotide substitutions were unevenly scattered along the core gene; a cluster of missense mutations was apparent in the region encoding the second hydrophilic domain of the core protein. The rate of occurrence of missense mutations per nucleotide substitution was significantly greater in this clustering variable region (CVR) of the core gene than in the remaining core gene sequence. These observations suggest that mutations in the CVR may be involved in the pathogenesis of chronic HCV infection during hepatocellular carcinogenesis.

Base Sequence↗
PubMed1997

Proliferative effect of postapheresis platelet donor plasma on a megakaryoblastic leukemia cell line.

Platelet donors sometimes show an increased platelet count following apheresis. We analyzed the effect of plasma obtained from such donors, along with thrombopoietin (Tpo), for growth and differentiation-inducing activity on a megakaryoblastic leukemia cell line, Meg-J. Colony formation was stimulated by donor plasma for Meg-J cells in a dose-dependent manner, and the time course of the sampling peaked 1 day after apheresis. Neither the donor plasma nor Tpo induced morphological differentiation. Donor plasma from any sampling time decreased CD41 and CD42b expression by more than 10%, and more than a 10% decrease of CD41 was induced by Tpo. The measurement of plasma Tpo showed no statistically significant increase after platelet donation. Our data suggest that, following apheresis, donor plasma contains factor(s) that: (a) stimulate growth rather than induce differentiation of a megakaryoblastic cell line; (b) are present in increased levels after apheresis; and (c) are different from Tpo.

Blood Donors↗
PubMed1997

Discrepant drug action of disopyramide on ECG abnormalities and induction of ventricular arrhythmias in a patient with Brugada syndrome.

An electrophysiologic study was attempted in a patient who experienced cardiac arrest. Programmed electrical stimulation from the right ventricle, without the use of any drugs, induced ventricular fibrillation (VF) twice. Disopyramide prevented the induction of ventricular arrhythmia by rendering VF to a nonsustained polymorphic ventricular tachycardia when administered at 300 mg/day, and noninducible at 400 mg/day. However, ST-segment elevation and the rSr' pattern in leads V(1-3) characteristic of Brugada syndrome became exaggerated by disopyramide. Disopyramide exerted discrepant action on the electrocardiographic (ECG) abnormalities and induction of VF in this patient, suggesting the efficacy of antiarrhythmic drugs assessed by an electrophysiologic study may be unrelated to ECG abnormalities in cases of Brugada syndrome.

Adult↗
PubMed1997

Activation of the contact system by filtration of platelet concentrates with a negatively charged white cell-removal filter and measurement of venous blood bradykinin level in patients who received filtered platelets.

BACKGROUND: Several recent reports have described hypotensive transfusion reactions in patients receiving platelet concentrates (PCs) filtered through white cell-reduction filters. It is well known that a negatively charged surface activates the contact system, consisting of factor XII, prekallikrein, and high-molecular-weight kininogen. STUDY DESIGN AND METHODS: To clarify the mechanisms of these hypotensive reactions, the possibility that white cell-reduction filtration activates the contact system was examined. Venous blood plasma bradykinin levels were also measured in patients receiving PC transfusions through filters. RESULTS: None of the measured values were changed by filtration through a positively charged filter. However, filtration through a negatively charged filter resulted in a decrease in the amounts of prekallikrein and an increase in the amount of bradykinin generated, which indicated the activation of the contact system. The bradykinin level was inversely related to the activity of angiotensin-converting enzyme (ACE) in the PCs and was elevated by addition of an ACE inhibitor. Although the venous blood plasma bradykinin level did not change in two patients with a normal ACE activity during PC transfusion through the negatively charged filter, two patients who had decreased ACE activity, showed a significant increase in bradykinin during the transfusion. CONCLUSION: These results suggest that the generation of a large amount of bradykinin by filtration of PCs through a negatively charged filter might cause hypotensive reactions in patients with decreased ACE activity. The clinical significance of bradykinin generation requires further study.

Aged↗
PubMed1997

[Renal cell carcinoma in acquired cystic disease of kidney (ACDK) manifested by spontaneous renal rupture: a case report].

We report a case of renal cell carcinoma in acquired cystic disease of the kidney (ACDK) presenting with a spontaneous renal rupture. A 41-year-old man on chronic hemodialysis for 16 years was referred to our hospital with sudden left back pain. On arrival, the patient was in a state of hemorrhagic shock but his general condition improved by conservative therapy. Computed tomography demonstrated a left renal rupture as well as bilateral ACDK. Although there was no definite evidence of a renal tumor, a left radical nephrectomy was performed one week later. The resected kidney contained a yellowish-brown tumor of 5.5 x 5.0 x 4.5 cm in size. Pathological examination revealed renal cell carcinoma, cystic type, clear cell subtype, pT2pN0M0. He has been free of recurrence for 3 months.

Adult↗
PubMed1997

[Super selective bronchial artery embolization using metallic coils in the management of hemoptysis].

Hemoptysis is one of the most important clinical problems of cardiopulmonary disease with high mortality rate. Its management is routinely performed with Bronchial Artery Embolization (BAE). However, it was reported that BAE had some disadvantages such as spinal injury and recurrent bleeding. In order to prevent spinal injury, we tried the super selective bronchial artery embolization (ss-BAE). This technique is especially available in the occlusion of the bronchial artery forming the common trunk with the spinal artery. Besides, BAE, considered to be only a palliative treatment, might cause recanalization due to reabsorption of the occlusive agent. So we used metallic coils to prevent this drawback. The ss-BAE with metallic coils was performed in 2 cases who had refractory hemoptysis against conservative therapy. Hemoptysis disappeared in both cases. The ss-BAE with metallic coils was shown to be safer and more effective than ordinary BAE.

Aged↗
PubMed1996

Clinical evaluation of serum amlodipine level in patients with angina pectoris.

Serum amlodipine levels were determined in 18 patients with vasospastic angina. Patients were divided into two groups: Group A (n = 9) received amlodipine 5 mg by single daily administration, and Group B (n = 9) received 10 mg given by single daily administration for the first 3 days, then 5 mg from the 4th day on. The serum amlodipine concentration in Group A took 7 days to reach a steady state of around 8 ng/ml. The level in Group B was 8.9 ng/ml at 3 days. From these results, the optimal dosage of amlodipine in the treatment of angina pectoris is 10 mg for the initial 3 days followed by 5 mg thereafter.

Aged↗
PubMed1996

Electrophysiological findings in idiopathic recurrent ventricular fibrillation: special reference to mode of induction, drug testing, and long-term outcomes.

Electrophysiological studies can be useful in the presence of idiopathic ventricular fibrillation (VF) and may be used when selecting antiarrhythmic drugs. However, the yield, the mode, and the long-term reproducibility of the induction of VF have not yet been fully elucidated. Eight patients with idiopathic VF underwent electrophysiological study. The mean age (+/- SD) was 45 +/- 17 years. Six were males and two were females. Diagnosis was done by exclusion. VF was induced in 6 (75%) of 8 patients using double extra stimuli at coupling intervals of 233 +/- 39 and 191 +/- 20 ms for the first and second extra stimuli, respectively. Of note, VF was induced by stimulation exclusively at the origin of the premature ventricular beat, which was the first complex of VF in two patients. In another patient, VF was initiated by two premature stimuli and also by a pause produced by rapid pacing. The inducibility of VF was reproduced 9-18 months after the first induction in all of the four patients studied. When the ability of antiarrhythmic drugs to suppress VF inducibility was confirmed, no recurrence was observed during the follow-up period of 40-160 months, but a recurrence of VF was observed in one of two nonresponders. In one patient, amiodarone administration failed in preventing VF induction 9 months after initiation of therapy, and reassessment of long-term drug-efficacy might be indicated in some patients. In conclusion, idiopathic VF was highly inducible (75%) with double extra stimuli. In this study, it was induced from a specific site (2/8) or by a pause (1/8). Induction of VF seemed to be reproduced 9-18 months after the first study. The outcome was considered favorable when the inducibility of VF was suppressed by antiarrhythmic drugs.

Adolescent↗
PubMed1996

Action of antiarrhythmic agents on the area of slow conduction in ventricular tachycardia.

The most common mechanism of monomorphic sustained ventricular tachycardia (VT) is reentry with an excitable gap, but the electrophysiological properties and response to antiarrhythmic agents in the area of slow conduction are not yet fully known. The conduction time through the area of slow conduction may show a frequency-dependent delay in some VT but in others, constant conduction time was observed as the paced cycle length was decreased while VT was entrained. VT with a so-called decremental property could be terminated more often with rapid pacing with less risk of acceleration of the VT rate. When the excitable gap was estimated by the width of the zone of entrainment: defined as the difference between the cycle length of VT and the longest VT-interrupting paced cycle length during transient entrainment, there was no difference in the width of the zone of entrainment between the responders (VT induction was prevented with drugs) and the non-responders (VT remained inducible). The cycle length of VT was not a predictor of drug-efficacy. However, when the drug-effect was assessed at the intermediate doses, VT of those with a significantly narrowed width of the zone of entrainment were subsequently suppressed when the same drug was added. In conclusion, the electrophysiological properties of the area is diverse and it might affect pacing-induced terminability. Whether an antiarrhythmic agent is able to prevent VT-induction or not can not be predicted from the basal electrophysiologic parameters, but a significant narrowing of the width of the zone of entrainment, and hence the excitable gap, can be a hallmark for drug-efficacy.

Anti-Arrhythmia Agents↗
PubMed1996

[Malignant mediastinal schwannoma associated with von Recklinghausen's disease--a resected case].

A case of malignant mediastinal schwannoma associated with von Recklinghausen's disease is reported. A 44-year-old woman was admitted to Chiba University Hospital because of an abnormal shadow on chest X-ray film. CT scan showed a cystic tumor in upper mediastinum and then tumor extirpation was performed. This cystic tumor was related to the sympathetic trunk and 60 x 35 x 33 mm in diameter. Its cut surface showed a thick irregular capsule and multilocular. Microscopic examination disclosed malignant cells with mitosis associated with neurofibroma. An immunohistochemical staining of these malignant cells with anti S-100 protein showed positive reaction. From these findings this tumor was diagnosed as malignant schwannoma. There is no evidence of recurrence two year after the operation. This is the first case of malignant schwannoma with cystic formation in Japan.

Adult↗
PubMed1995

Spatial orientation of the reentrant circuit of idiopathic left ventricular tachycardia.

In 6 patients with idiopathic left ventricular VT, the spatial orientation of the reentrant circuit was estimated from the results of transient entrainment of VT with rapid pacing at different sites. The entrance to the area of slow conduction was located toward the outflow tract, whereas the exist was located at the apicoposterior area of the left interventricular septum.

Adult↗
PubMed1995

A case of primary Hodgkin's disease of the stomach.

A case of primary Hodgkin's disease, a lymphocyte-predominant entity, occurring in the stomach is described. The patient was a 37-year-old man who complained of general fatigue. Endoscopic biopsy revealed gastric malignant lymphoma. Subtotal gastrectomy and postoperative chemotherapy following a modified CHOP regimen were performed. The patient has been free of recurrence during a follow-up period of 15 months. The preoperative diagnosis of gastric Hodgkin's disease is difficult. Thus far, of 100 cases of gastric Hodgkin's disease reported in Japan, only 3 were diagnosed correctly preoperatively. We also misdiagnosed our case, as B cell type malignant lymphoma, preoperatively. The final diagnosis of Hodgkin's disease of the stomach was made on the basis of histopathological and immunohistochemical examinations. Hodgkin's disease of the stomach is rare, and there are histologically similar diseases; Ki-1 lymphoma, adult T cell lymphoma, malignant histiocytosis, and infectious monocytosis. Careful diagnosis is essential thus for Hodgkin's disease of the stomach.

Adult↗
PubMed1995

Effect of nafamostat mesilate on bradykinin generation and hemodynamics during LDL apheresis.

Dextran-sulfate (DS) cellulose used for low-density lipoprotein (LDL) apheresis seems to be a weak activator of the contact phase of the intrinsic coagulation pathway because the surface of this substance has negative charges. Heparin, a commonly used anticoagulant, has no effect on this process whereas the process is inhibited by a newly developed anticoagulant, nafamostat mesilate (NM). The effects on bradykinin generation were compared between heparin and NM. Five patients with severe hypercholesterolemia were treated with LDL apheresis using either heparin or NM on a different day. During apheresis with heparin, factor XII, high molecular weight kininogen, and prekallikrein were markedly decreased by passing through the DS column. A distinct generation of bradykinin was observed by passing plasma through the DS column, and this led to the rise of bradykinin levels from 12 +/- 5 (mean +/- SE) to 72 +/- 14 pg/ml after treatment of 1,000 ml of plasma. NM suppressed almost completely the rise of bradykinin levels. Although blood pressure was apt to decrease during apheresis with heparin, there was no significant difference in blood pressure between heparin and NM. Since an angiotensin-converting enzyme inhibitor may lead to a marked rise in blood levels of bradykinin by suppressing its degradation, the use of NM is recommended for apheresis in patients taking this drug.

Adolescent↗
PubMed1995

Different apheresis methods in the treatment of hypercholesterolemia in primary biliary cirrhosis: a case report.

The two different modes of low-density lipoprotein (LDL) apheresis, cascade filtration (CF) and dextran-sulfate cellulose (DSC) adsorption, were compared for efficiency of cholesterol removal in a patient with severe hypercholesterolemia due to primary biliary cirrhosis (PBC). Decrement in the total cholesterol level by the DSC method was less than that by the CF method. Apolipoprotein B was decreased to almost null by both modules whereas the decrease in albumin was much greater in the second filter of the CF method than in the DSC column. Lipoprotein X which constituted the major portion of serum cholesterol in PBC became negative by passing plasma through the second filter. The CF method was preferred to the DSC method for removal of lipoprotein X, but albumin substitution was mandatory to prevent the decrease of serum albumin in the CF method.

Adult↗