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Biomedical subjects

E Yamada

Publications and source records attributed to E Yamada.

At least 181 records · Page 10Linked to original sources
PubMed1981

A freeze-fracture study of the aggregation state of Ca2+,Mg2+-ATPase of sarcoplasmic reticulum in reconstituted vesicles at low and high temperature.

Since it was possible for Ca2+,Mg2+-ATPase of sarcoplasmic reticulum (SR) to change its aggregation state in the membrane depending on temperature, and since the change could be the cause of the break in the Arrhenius plot of Ca2+,Mg2+-ATPase activity, the aggregation state of Ca2+,Mg2+-ATPase at 0 degrees C in the membrane was compared with that at 35 degrees C by freeze-fracture electron microscopy. These temperatures are below and above the break in the Arrhenius plot (about 18 degrees C), respectively. Two kinds of samples were used; fragmented SR vesicles and egg PC-ATPase vesicles, a reconstituted preparation from purified Ca2+,Mg2+-ATPase and egg yolk phosphatidylcholine (egg PC). For both the appearance of particles in the fracture faces of the samples fixed at 0 degrees C was similar to that at 35 degrees C, and phase separation between protein and lipid was not observed even at 0 degrees C. The size of the particles was measured and histograms of the sizes at 0 degrees C and 35 degrees C were made. The histogram at 0 degrees C was similar to that at 35 degrees C with a peak at 7.1 nm, which is 1-2 nm smaller than the value reported so far. The number of the particles per unit area of the membrane was also counted. The value at 0 degrees C was similar to that at 35 degrees C. These results indicate that Ca2+,Mg2+-ATPase of SR exists in the same aggregation state (estimated as oligomer based on the values obtained in this experiment) between 0 degrees C and 35 degrees C. Based on the results of this study we think that the break in the Arrhenius plot of Ca2+,Mg2+-ATPase activity in SR is not caused by the change in the aggregation state of Ca2+,Mg2+-ATPase.

Animals↗
PubMed1981

Molecular heterogeneity of hepatitis B virus e antigen in liver and serum.

Hepatitis B virus e antigen (HBeAg) derived from liver at autopsy or from the serum of asymptomatic carriers has been characterized. The liver-derived HBeAg consisted of two different molecules, one with a mol. wt. of 30 000 (monomer) and the other with a mol. wt. of 90 000 (trimer), in a ratio of 3:1. Both were free of IgG. The serum-derived HBeAgs were heterogeneous with mol. wt. of 30 000, 90 000, 240 000, 400 000 and 540 000. Among them, the so-called IgG-free HBeAgs consisted almost exclusively of the 30 000 and 90 000 molecular species, in a ratio of 1:9. The serum HBeAg of mol. wt. 90 000 was further differentiated into two molecular species, one trimer and the other associated with albumin. The large mol. wt. HBeAgs (240 000, 400 000 and 540 000) were associated with IgG in ratios of one molecule of HBeAg to one, two or three molecules of IgG respectively. The complete dissociation of the IgG molecule was not achieved by 5 M-urea treatment of such HBeAgs, suggesting that it was bound in an immune complex. A hypothetical model is proposed which describes the heterogeneity of the HBeAgs derived from both the liver and serum, and containing HBeAgs either in a free form or associated with serum IgG.

Antigens, Heterophile↗
PubMed1981

Two siblings, including a fetus, with Tay-Sachs disease.

This report consists of a morphological study on two siblings of Tay-Sachs disease. One is a girl of 3 years of age and the other is a 23-week fetus. In the first case, the nerve cells in the cerebral cortex showed histochemically abnormal accumulation of glycolipids and electron microscopically numerous membranous cytoplasmic bodies characteristic to gangliosidosis. In the fetal case, the nerve cells in the brain stem were well differentiated and here abnormal inclusions were found by histochemical study. The cortical neurons were immature in structure and inclusions were not demonstrated by histochemical study. In electron microscopic study, the cortical neurons also showed a small number of intracytoplasmic inclusions which contained electron dense granules and/or membranous structures. Causes of the differences in amount of abnormal lipid accumulation in the brain stem and the cerebral cortex were discussed.

Brain Stem↗
PubMed1981

Histochemical study on 5'-nucleotidase in the cerebrovascular system in stroke-prone spontaneously hypertensive rats.

5'-Nucleotidase activity in the cerebrovascular system in stroke-prone spontaneously hypertensive rats was histochemically investigated. In the hypertensive rats, an enhancement of 5'-nucleotidase activity was observed already in the early stage of hypertension and the enzyme activity increased with advancing age. The enzyme activity appeared earlier and stronger in the larger arteries in the basal portion than the pial arteries in the convexity of the brain and arterioles in the brain parenchyma. The activity in the arterial walls proved to be particularly strong in the thickened parts showing cellular hyperplasia, mainly at the branching portions. The reaction products localized along the plasma membrane, and also in the cytoplasma in some parts where the activity was strong. Relationship between the increased 5'-nucleotidase activity and aging of the cells composing the cerebrovasculature resulted from an accelerated or repeated cell proliferation was discussed.

5'-Nucleotidase↗
PubMed1980

A non-histone chromatin protein that is a specific phosphate acceptor of nuclear cAMP-independent protein kinase from mouse spleen cells.

A non-histone chromatin protein (NHCP), which is specifically phosphorylated by a nuclear cAMP-independent protein kinase from mouse spleen cells in vitro, has been purified from calf thymus chromatin. SDS-polyacrylamide gel electrophoresis shows that the molecular weight of the purified NHCP (single peptide) is 13,000. This peptide consists of 14 amino acid residues and has high serine content (17.9%). However, no methionine, proline, or half-cysteine have been detected. The NHCP is a basic protein (isoelectric point, approximately 9.0), although it has high acidic amino acid content (26.2%). This protein serves as the most effective phosphate acceptor for the kinase in vitro when compared with other chromatin proteins such as histones; the Km value of the kinase for the NHCP is 3.65 x 10(-6) M, whereas that for histone H2a (Mr = 14,000) is 1.08 x 10(-5) M. The present finding that the NHCP phosphorylation by the kinase in vitro is remarkably stimulated by double-stranded DNA but inhibited by whole histone or histone H2a suggests that the phosphorylation may be controlled by both double-stranded DNA and histone H2a.

Amino Acids↗
PubMed1980

Prevalence of Williams e1 antigen in comparison with e2 antigen in hepatitis B antigen carriers and patients in hemodialysis unit.

The prevalence of both e1 and e2 antigens in 1,158 sera of asymptomatic HBsAg carriers, carriers in hemodialysis units, and HBsAg-negative blood donors was examined. The detection rate of e1 antigen was as high as 80% in asymptomatic carriers, 95% in hemodialysis patients, and even 13.1% in HBsAg-negative donors. All of the e1 antigen-positive specimens in such HBsAg-negative sera were found to have both or either anti-HBs and anti-HBc, suggesting the past history of Hepatitis B virus (HBV) infection of the donors. In the HBsAg-positive serum, the detection rate of e2 antigen (17%) was lower than that of e1 (80%), and all sera having e2 antigen were positive for e1 antigen. The titers of HBsAg, HBcAg, and anti-HBc in e2 antigen-positive sera were higher than that of sera detecting only e1 antigen. The appearance of e1 antigen and e2 antigen in the course of post-transfusion hepatitis B was studied with five cases. Retrospective study showed that three of them each received one unit of HBsAg-positive blood, and the other two received HBsAg-negative blood but with high-titered anti-HBc. In four cases out of five, in which e2 antigen was detected during the course of infection, the initial detection of e2 antigen occurred at or just before the elevation of liver enzyme levels. On the other hand, e1 antigen was detected relatively early after transfusion, and the time of onset. Moreover, the detection period of e1 antigen persisted longer, even after the disappearance of HBsAg antigenemia. These two separate studies suggest that not only e2 antigen but also e1 antigen are associated with the infection of HBV, but they are distinct from each other; the e2 antigen may have the properties of a signal of the viral activity in the patient as suggested by many others, but e1 antigen does not seem to bear such diagnostic values.

Adult↗
PubMed1980

Mouse spleen cell nuclear protein kinases and the stimulating effect of dsDNA on NHP phosphorylation by cyclic AMP-independent protein kinase in vitro.

cAMP-dependent (designated as enzyme I, about 68,000 daltons) and cAMP-independent protein kinase (designated as enzyme II, about 45,000 daltons) have been partially purified from the nuclei of mouse spleen cells. Both kinases phosphorylated calf thymus histones as well as non-histone proteins (NHP) and required Mg2+ (8 mM) or Mn2+ (2 mM) for maximal activity. NEM (0.5 mM), which is an inhibitor of SH-enzymes, inhibited the histone phosphorylating activity of enzyme II by more than 90%, whereas it inhibited the activity of enzyme I by less than 10%. Moreover, the activity of enzyme II was more sensitive to high temperature than that of enzyme I. Non-histone protein (CM-III protein) served as a more effective substrate for enzyme II than histones; the Km value for CM-III protein was 34.4 micrograms/ml whereas that for histone H2a (14,300 daltons) was 155 micrograms/ml (1.08 x 10(-5) M). CM-III protein phosphorylation by enzyme II in vitro was greatly stimulated by the addition of dsDNA, but not by single-stranded DNA or bacterial ribosomal RNA. However, the phosphorylation of CM-III protein by enzyme I was less than 50% of that of histones, and there was no stimulatory effect. SDS-gel electrophoresis showed that two distinct NHPs (about 13,000 and 19,000 daltons) prepared from calf thymus chromatin were preferentially phosphorylated by enzyme II in vitro in the presence of dsDNA. This finding suggests that these two NHPs may be specific phosphate acceptors of cAMP-independent protein kinase (enzyme II) in the nuclei of mouse spleen cells.

Animals↗
PubMed1980

Antigenic conversion from HBcAg to HBeAg by degradation of hepatitis B core particles.

Highly purified and homogenous hepatitis B core particles were obtained from an autopsy liver. The core particles consisted mainly of an electrophoretically single major polypeptide with a molecular weight of 20,000 daltons. When antigenic conversion from hepatitis B core antigen (HBcAg) to hepatitis B e antigen was achieved by treating these core particles by sonication or by passing them through an anti-HBc IgG-conjugated Sepharose 4B column, no appreciable changes were found in the above protein composition. The same antigenic conversion was also achieved by centrifugation of core particles in CsCl, which revealed the process of morphological disintegration accompanied by antigenic conversion. These observations may support the hypothesis that HBcAg resides on a protein conformation which consists of a polypeptide sharing HBe antigenicity.

Chromatography, Affinity↗
PubMed1980

Cytochemical investigation on acid phosphatase activity in cerebral arteries in spontaneously hypertensive rats.

Acid phosphatase activity in the cerebral arterial system in spontaneously hypertensive rats (SHR) was cytochemically investigated. In the endothelial and medial smooth muscle cells, endoplasmic reticulums and Golgi complex revealed an intense acid phosphatase activity and primary lysosomes containing the high enzyme activity were found to be augmented in number. The enzyme activity was demonstrated in the vacuolated secondary lysosomes and in the intercellular spaces of the arterial walls. Lytic changes of the arterial mural cells and vessel matrix due to lysosomal enzymes were also evident. Causes of the lysosomal enzyme induction and roles of the enzyme in the developmental mechanism of hypertensive cerebrovascular changes in the SHR brain are discussed.

Acid Phosphatase↗
PubMed1979

Physicochemical heterogeneity of hepatitis B e antigen detected in asymptomatic carriers and carriers in a hemodialysis unit.

Physicochemical studies of hepatitis B e antigen (HBeAg) revealed a clear cut difference between e1 and e2 antigen. The e1 antigen was found to have a MW of Ca 150,000 and a pI of 6.4-7.2, whereas both the MW and pI of the e2 antigen were heterogeneous depending upon the source of serum. Sera obtained from asymptomatic carriers were characterized by low titers of HBs antigen, HBc antigen and DNA polymerase and contained e2 antigen of larger molecular weight (200,000-300,000) with a narrow distribution range and a pI of 4.8 to 5.2 (type 1). On the other hand, the sera from patients in a hemodialysis unit who were HBs antigen carriers and had high titers of HBs antigen, HBc antigen and DNA polymerase contained e2 antigen of heterogeneous distribution in MW (from 300,000 to 70,000) and pI (type 2 and 3). The e2 antigen obtained from the higher MW type 3 serum had lower isoelectric points (pI 4.5 to 5.2) as was the case with e2 antigen obtained from asymptomatic carriers whereas relatively wide range of isoelectric points (pI 5.1 to 8.2) was found with the lower molecular weight e2 antigen.

Carrier State↗
PubMed1979

Acid phosphatase activity of the brain in SHR-- the first report of enzyme histochemical studies of spontaneously hypertensive rat brain.

Changes in acid phosphatase activity in the cerebrovascular system and brain parenchyma in SHR were investigated histochemically. An increased activity of the enzyme was demonstrated in the SHR endothelial and medial smooth muscle cells of the cerebral arterial system as compared to the control. The pericytes of intraparenchymal blood vessels also showed an intensified enzyme activity. The enzyme activity increased with advancing age. In SHR brain parenchyma, the enzyme activity was decreased in the cortical nerve cells. Glial cells with the enzyme activity were increased in number and showed an intensified activity. Causative factors of changes in acid phosphatase activity in SHR cerebral arteries and parenchyma were discussed.

Acid Phosphatase↗