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Biomedical subjects

M Yamazoe

Publications and source records attributed to M Yamazoe.

At least 55 records · Page 3Linked to original sources
PubMed1991

Integration of woodchuck hepatitis virus (WHV) DNA at two chromosomal sites (Vk and gag-like) in a hepatocellular carcinoma.

Integration of woodchuck hepatitis virus (WHV) DNA into the liver DNA of a woodchuck infected by the virus was investigated. Clonal viral integration was not detected three months before the appearance of four hepatocellular carcinomas (HCC). Integration of the viral DNA was detected in all four HCCs, of which one was chosen to determine the structure of the viral integration completely in a single tumor. The integration occurred in two sites. One part contains the viral DNA from the middle of the gene encoding surface antigen to two-thirds of the way through the gene encoding X protein (X) with no structural changes. The coding frame of the truncated X gene continues into the chromosomal sequence to make a possible fusion protein. The integration seems to have occurred by recombination within two direct repeats of the viral genome in one junction and by homologous recombination between viral DNA and chromosomal DNA in the other junction. The viral DNA is integrated into a spacer of the immunoglobulin L-chain Vk (IgVk) region without any chromosomal rearrangement accompanying the integration. The viral DNA at the second site has a complex structural rearrangement: part of the preS gene is duplicated and attached to the terminus of the gene encoding core antigen in a head-to-tail fashion, followed by three small fragments derived from other parts of the viral DNA. The integrated preS gene has its own 5' regulatory element and a coding frame consisting of the truncated preS gene, the other parts of viral DNA and the chromosomal sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
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

[Elevation of 11-dehydro-thromboxane B2 levels in unstable angina].

To evaluate in vivo platelet activation, 11-dehydro-thromboxane B2 levels in plasma and urine were measured in 9 patients with unstable angina and 11 with stable angina using radioimmunoassay modified by the extraction method of Kawano et al. The 2 groups were matched for age, sex, coronary risk factors, medications or atherosclerotic lesions in coronary angiography. Although there was no difference in the plasma level between the 2 groups in the usual state, urinary 11-dehydro-thromboxane B2 amount in unstable angina was significantly increased compared to the stable angina group (865.5 +/- 238.7 vs 535.9 +/- 177.4 pg/mg creatinine (mean +/- SD), p < 0.01). There was no correlation between the 11-dehydro-thromboxane B2 level and the degree of coronary atherosclerosis in either group. The plasma level increased during the attacks in 2 patients with unstable angina. The amount of urinary 6-keto-PGF1 alpha did not differ between the 2 groups. These findings suggest that platelet activation in vivo is more pronounced in unstable angina than in stable angina, and that the measurement of urinary 11-dehydro-thromboxane B2 may be useful for evaluating and treating angina.

Angina Pectoris↗
PubMed1990

Prediction of preserved flow to the infarct area based on admission electrocardiogram in anterior wall acute myocardial infarction.

To determine whether preserved flow to the infarct area could be predicted from the admission electrocardiogram and to define the effect of preserved flow on the late results after reperfusion, 20 anterior myocardial infarction patients who were successfully reperfused were studied. Patients were divided into 3 groups: (1) no-flow group (8 patients), with an occluded infarct-related artery and no easily visible collaterals; (2) intact collateral group (6 patients); and (3) subtotal obstruction group (6 patients). From the admission electrocardiogram, the sum of ST-segment elevation (sigma ST), the sum of R-wave amplitude (sigma R) in leads V1 through V6 and the ratio of these (sigma R/sigma ST) were measured. There was no significant difference in sigma R among the 3 groups. The no-flow group had significantly lower sigma R/sigma ST and higher sigma ST than the intact collateral group or subtotal obstruction group. All patients (6 of 6) with subtotal obstruction and all except 1 patient (5 of 6) with intact collateral showed sigma R/sigma ST greater than 2.5 or sigma ST less than 2.0 mV. All patients (8 of 8) with no flow showed sigma R/sigma ST less than or equal to 2.5 and all except 1 patient with no flow (7 of 8) showed sigma ST greater than or equal to 2.0 mV. The regional wall motion was assessed by the radial method at 4 weeks. The mean percentage systolic shortening in the anterior and apical regions was significantly correlated with sigma R/sigma ST (r = 0.75, p less than 0.001) and sigma ST (r = -0.65, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Possible role of coronary artery spasm in unexplained syncope.

Coronary spasm provocation by intracoronary methylergonovine was performed in 14 patients (8 men and 6 women, mean age 56 +/- 6 years) with syncope that remained unexplained despite neurologic and noninvasive cardiac evaluations. Electrophysiologic testing was also performed in 6 of 14 patients. No patient had structural heart disease or significant fixed stenosis of greater than or equal to 75% in the coronary arteries. Six patients had no history of chest pain even when they developed syncope. Serious arrhythmia was documented in 2 patients, cardiac standstill in 1 and complete atrioventricular block in the other. Coronary spasm was induced in 9 patients using the methylergonovine provocation test. Multivessel spasms were found in 3 patients. Coronary spasm was induced in the artery supplying the inferior wall in 7 of 9 patients with positive results. In 4 of 9 patients who had a positive result, there was no prior history of chest pain. In 1 patient, whose electrocardiogram was recorded during syncope, cardiac standstill was documented and cardiac standstill and syncope also occurred during the provocation test. Monomorphic ventricular tachycardia was not induced by the electrophysiologic study. These results suggest that coronary spasm is involved in unexplained syncope.

Cardiac Pacing, Artificial↗
PubMed1990

Synthesis of human gamma-glutamyl transpeptidase (GGT) during the fetal development of liver.

We have determined expression of human GGT gene encoding gamma-glutamyl transpeptidase (GGT) during fetal development of liver using the Northern-blot analysis with a cloned human GGT cDNA and immunohistochemistry with a monoclonal antibody. GGT mRNA could be detected as early as the 12th week of gestation. It then increased gradually to a peak of approx. threefold the amount at week 12, at week 40, just before birth. The size of the mRNA in the fetal liver was 2.7 kb and mRNA of the same size was detected both in the human fetal kidney and human hepatocellular carcinoma as well as normal adult liver. Immunohistochemical analyses show that GGT increased as the fetal liver developed in parallel with the increase in mRNA. Histochemically, GGT was shown to be located in the wall of bile canaliculi when synthesis was low in early development, but to be distributed, in addition, all over the cell membrane of the fetal hepatocytes when synthesis was high at the later stage of development.

Blotting, Northern↗
PubMed1990

Clinical characteristics and possible role of coronary artery spasm in syncope and/or aborted sudden death.

We investigated the clinical and pathophysiologic characteristics in patients with vasospastic angina who developed syncope and/or experienced aborted sudden death (SD). Vasospastic angina was diagnosed using the methylergonovine test. Syncope was found in 32 (10.4%) patients among 309 who were admitted to our institute in a one-year period. The most frequent cause of syncope was ventricular tachycardia which was found in 10 (31.2%) of the 32 patients. The next important cause of syncope was vasospastic angina which was found in 7 patients (21.8%). Among the 7 patients with vasospastic angina who experienced one or more syncopal episodes, there were 3 patients with aborted SD, 3 with syncope and one with shock. Cardiovascular collapse was observed in 4. Interior wall ischemia was found in 5 and anterior wall ischemia in 2 during the methylergonovine test. None of the 7 patients had significant coronary stenosis. Two patients had no prodromal symptom such as chest pain. Our results suggest that coronary artery spasm may be one of the most frequent cardiovascular diseases that causes syncope which is not always accompanied by a prodromal symptom. Therefore, coronary spasm should be distinguished in patients with unexplained syncope or aborted SD.

Coronary Angiography↗
PubMed1990

Catheter-type defibrillation electrode using glassy carbon: results of electrode implantation.

The implantable defibrillator, developed by Dr Michel Mirowski, is a remarkable electric therapeutic device which has been in clinical use since 1980 in the treatment of life-threatening arrhythmia. However, as the present life span of this device is only 3 years, research is being carried on to extend the lifetime with improved stimulation methods, circuits and electrodes. In particular, the electrode system which is inserted into the right ventricle has more than 50 times the electrode area of a pacing electrode and is prone to degradation. What is needed is biocompatibility and electrical stability, similar to that of cardiac pacemaker electrodes, which can be used for more than 10 years. For this purpose, we focused on a conductive ceramic as a new material for the defibrillation electrode instead of the previously-used metal. We selected glassy carbon as our electrode material and tested the surface condition through acute and chronic animal experiments. No clots formed around the electrodes after a 3-month implantation, nor were there surface disorders after the defibrillation stimulations. We concluded that glassy carbon is a promising material for future defibrillation electrodes.

Animals↗
PubMed1989

A case of atrial septal defect combined with hypertension and left ventricular hypertrophy. Left ventricular failure induced by balloon occlusion and the effect of nifedipine.

A 46 year old woman with hypertension and left ventricular hypertrophy accompanied by an atrial septal defect is reported. Hemodynamic changes induced by balloon occlusion and concomitant nifedipine were studied. Left ventricular failure appeared after balloon closure of the defect. Nifedipine decreased the increment in left ventricular end-diastolic pressure induced by balloon occlusion. After the reduction of systemic vascular resistance, the ratio of intracardiac shunt flow was still larger. Surgical closure of the defect was performed and the postoperative course was good with the use of vasodilators.

Blood Pressure↗
PubMed1989

Recanalization of experimental thrombotic arterial occlusion by radiofrequency thermal angioplasty: an angioscopic observation.

The efficacy of radiofrequency (RF) angioplasty for recanalization of arterial thrombosis was assessed angioscopically in five dogs. A thrombus was induced by balloon injury of the left femoral artery. Within two hr, thrombi led to total occlusion of the artery in three dogs, subtotal occlusion in one, and about 70% obstruction in one. A metal-tipped catheter, with a tip size of 2.0 mm x 5.7 mm, was advanced into the thrombus and RF at 13.56 MHz was delivered repeatedly with gradually increased energies. The arterial lumina were recanalized or enlarged in all dogs. The thrombus surface had a shaggy appearance, and were dark (charring), or mixed dark and white in color. There were relatively large variations in the energies required; 140 J in one, 200 J in two and 250 J in two. The present results suggest that thrombotic arterial occlusion, such as acute occlusion complicating balloon angioplasty, can be treated with RF thermal angioplasty. Angioscopy provided detailed information about thrombus surfaces. The variations in required energies indicate the inability to control the thermal effect by energy settings alone. A more sophisticated method such as measurement of tip temperature will be able to overcome this difficulty.

Angioplasty, Balloon↗
PubMed1988

The primary structure of human gamma-glutamyl transpeptidase.

A cDNA hybridizable to that of rat gamma-glutamyl transpeptidase (GGT) was cloned from a cDNA library of human fetal liver. The insert of the cDNA clone contained 1866 bp consisting of an open reading frame (ORF) of 1709 bp (569 amino acids (aa), N-terminal portion truncated) and a 135-bp 3'-untranslated region followed by a polyadenylated tail. In parallel, amino acid sequences of N-terminal portions of heavy and light chains of a purified human GGT were determined. Two stretches of amino acid sequences identical to the N-terminal sequences of heavy and light chains were found in the ORF. We therefore concluded that the clone is a cDNA for human GGT. From the amino acid sequence deduced from cDNA, the heavy and the light chains of the purified enzyme are estimated to be composed of 351 aa (Mr 38,336) and of 189 aa (Mr 20,000), respectively. The heavy chain is preceded by a signal peptide of at least 29 aa presumed to be cleaved by bromelain treatment. Six putative N-glycosylation sites are present in the heavy subunit region and one in the light subunit region. Primary structure and hydrophobicity profile are closely similar to those of rat GGT.

Amino Acid Sequence↗
PubMed1988

Monoclonal antibodies to O4 antigen of Vibrio parahaemolyticus.

Four monoclonal antibodies were prepared against O4 antigen of Vibrio parahaemolyticus. All the antibodies were shown to be specific for O4 antigen by agglutination with heat-killed O-cells of the organism and precipitation with LPS preparations. The inhibition experiments of the precipitations with various sugars and oligosaccharides suggested that the combining sites of these hybridoma antibodies were directed to an antigenic determinant structure containing----3 and----6 linked D-glucose, D-galactose, and N-acetyl-D-galactosamine.

Agglutination↗
PubMed1988

Syncope in aortic stenosis during continuous electrocardiographic monitoring--a case report.

A female patient with severe aortic stenosis had suffered from repeated syncope. Transaortic valve pressure gradient at cardiac catheterization was 117 mmHg. Continuous electrocardiographic monitoring was done after admission. During syncope, the electrocardiogram showed bradycardia with the lowest heart rate 44 beats per minute, while arterial pulses were not palpable. Rather than arrhythmia, other mechanisms, such as an inhibitory reflex from left ventricular receptors, should be postulated as the cause of syncope in patients with severe aortic stenosis.

Aged↗
PubMed1988

[Perspectives in familial hypercholesterolemia: with particular reference to associated ischemic heart disease].

Seventy heterozygous patients with familial hypercholesterolemia (FH), aged 3 to 91 years (37 men and 33 women), from 38 different families were studied to ascertain their clinical profiles including the pattern of distribution of total cholesterol (TC), Achilles tendon thickness (ATT), and a sex difference in age at the onset of ischemic heart disease (IHD). Eighteen family members who died of IHD were included in this study. The TC level was 332.2 +/- 95.0 mg/dl (mean +/- SD), and the ATT was 12.0 +/- 2.7 mm. IHD was observed in 20 men and 8 women, with an incidence in men 2.5 times higher than that in women. The mean age at the onset of IHD in men was in the sixth decade, one decade younger than in women. IHD was even observed in patients with TC levels of nearly 230 mg/dl. One of the 18 family members was considered a homozygote of the disease by autopsy findings. Twelve of the remaining members died suddenly, and another five had fatal myocardial infarction. We conclude that, (1) IHD is frequently associated with FH, even though TC levels are 230-300 mg/dl, (2) complications of IHD peak earlier in men (sixth decade) than in women (seventh decade) and (3) relatively large numbers of family members died suddenly, especially men.

Achilles Tendon↗
PubMed1987

Response of the left ventricle in idiopathic dilated cardiomyopathy to postextrasystolic potentiation.

The effectiveness of postextrasystolic potentiation (PESP) was assessed to detect residual function of the left ventricle in seven patients with idiopathic dilated cardiomyopathy (IDC). The postextrasystolic changes in the aortic pressure pulse, global left ventricular function, and quantitative regional left ventricular wall motion were investigated. PESP caused an increase in the peak systolic aortic pressure (116 +/- 17 to 130 +/- 25 mm Hg, p less than 0.01), a decrease in the peak diastolic aortic pressure (74 +/- 12 to 61 +/- 11 mm Hg, p less than 0.001), a decrease in preejection period/left ventricular ejection time (PEP/LVET) ratio (0.637 +/- 0.136 to 0.457 +/- 0.097, p less than 0.001), and an increase in the global left ventricular ejection fraction (LVEF) (0.26 +/- 0.09 to 0.40 +/- 0.12, p less than 0.01). Postextrasystolic changes in LVEF were inversely related to changes in PEP/LVET (r = -0.76, p less than 0.05). The postextrasystolic patterns of the regional wall motion of the left ventricle were different in each patient. The results of this study suggest that residual left ventricular function can be detected in patients with IDC by their response to PESP.

Adult↗
PubMed1987

Isolation and characterization of forespores from Bacillus megaterium.

A procedure for isolation of intact forespores from sporulating Bacillus megaterium cells was developed. The cells were digested with lysozyme and made to release free forespores from the protoplasts by disruption of the cytoplasmic membrane with sonication in phosphate buffer containing 10% glycerol. The suitability of the procedure was confirmed by recovery of dipicolinic acid in the isolated forespores and an electron microscopic observation. The fine structure of the forespores prepared at 6 hr (t6) after initiation of sporulation was similar to that of mature spores, except that the cortex layer and primordial cell wall were thinner and the core was larger. The density, determined by density gradient centrifugation, of the forespores isolated at t6, t10, t12, and mature spores was estimated to be 1.2783, 1.2875, 1.2861, and 1.2858, respectively. The isolated forespores at t6 and t8 were extremely heat labile (D80 of 9.5 and 21.5 min, respectively) relative to mature spores (D80 of 277.8 min). These forespores were also less resistant to organic solvents. Germination of the forespores as well as mature spores was induced by KNO3, D-glucose, and L-leucine. Forespores at t6 were more sensitive to KNO3-induced germination than those at t10, t12, and mature spores when measured by reduction in the optical density of cell suspension.

Bacillus megaterium↗