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Biomedical subjects

M Sumida

Publications and source records attributed to M Sumida.

At least 145 records · Page 8Linked to original sources
PubMed1981

Clinico-pathological study of acute non-A, non-B post-transfusion hepatitis: histological features of liver biopsies in acute phase.

A follow-up study of acute non-A, non-B post-transfusion hepatitis with a mean follow-up period of 30 months was carried out in 24 patients in whom liver biopsy was done within 3 months of onset. Of the 24, 13 patients (54%) developed chronic biochemical liver disease with elevated serum aminotransferases for more than 6 months, and in 11 the elevated liver enzymes were normalized within 6 months. Although there were no statistically significant differences in the mean peak values of liver enzymes, length of incubation period and number of transfusions between the chronic and resolved groups, the former tended to have a slow rise and multiple peaks of serum liver enzymes. Analysis of the liver biopsies made in the acute phase revealed that limiting plate erosion, hepatocellular degeneration, and poor regenerative activities were indicative of subsequent transition to chronicity. Multiple biopsies were taken in five patients who were followed for an average of 29 months, and the subsequent histological diagnosis was chronic persistent hepatitis in two, chronic active hepatitis in two and cirrhosis in one.

Acute Disease↗
PubMed1979

Angiographic evaluation of the abnormal endoscopic pancreatogram.

Out of 1,269 pancreatograms, 122 were abnormal. Angiography was performed in these patients. Fifty-five were found to have pancreatic carcinoma. In the remaining 67 patients a false positive angiographic diagnosis of either chronic pancreatitis or pancreatic cancer was made in 11%. In one patient a hemangioma was diagnosed as a pancreatic cyst. The remaining 58 patients all had normal pancreatic angiograms in spite of gross ductal abnormality on endoscopic retrograde cholangiopancreatography (ERCP). All these patients were followed for an average of 19 months and showed no clinical evidence of pancreatic disease. It is suggested that angiography should be considered a complementary examination to ERCP and is particularly useful to exclude carcinoma when the pancreatogram is abnormal.

Adult↗
PubMed1978

Transient kinetics of Ca2+ transport of sarcoplasmic reticulum. A comparison of cardiac and skeletal muscle.

Current evidence supports similar functions and mechanisms for cardiac sarcoplasmic reticulum (CSR) as for skeletal sarcoplasmic reticulum (SSR). It is thought that the slower relaxation rate of cardiac muscle compared to fast skeletal muscle reflects the lower ATPase activity and calcium transport of CSR. Possible quantitative differences is phosphorylation, dephosphorylation, and calcium transport of the isolated preparations are studied using a quench-flow apparatus. The results show that both CSR and SSR bind calcium tightly in the absence of ATP, and coupling of E approximately P formation and calcium transport occurs in the transient phase of ATP hydrolysis. The rate of phosphorylation (t-1/2 - 10 ms) of sarcoplasmic reticulum (SR) preloaded with calcium is the same for cardiac and skeletal preparations. However, the rates of dissociation of extra vesicular calcium (10 s-1 versus 15 s-1), phosphorylation of calcium-free SR, and dephosphorylation of E approximately P (8 s-1 versus 12 s-1) are lower for CSR than for SSR. By computer simulation, the apparent rate constants associated with the reduced rates of phosphorylation of calcium-free SR were: 12 s-1 for CSR and 63 s-1 for SSR in the presence of high Mg2+. The difference in the rates may be partly responsible for the lower levels of ATPase and calcium transport activity with characterize cardiac muscle preparations.

Animals↗
PubMed1976

Reaction mechanism of the Ca(2)+-dependent ATPase of sarcoplasmic reticulum from skeletal muscle. XI. Re-evaluation of the transition of ATPase activity during the initial phase.

We previously reported (J. Biochem. 70,95--123 (1971) that the time course of Pi liberation in the reaction of Ca2+, Mg2+--dependent ATPase [EC 3.6.1.3.] of fragmented sarcoplasmic reticulum (SR) consists of a lag phase, a burst phase, and a steady phase. We also showed that the rate constant, kd, of decomposition of the phosphorylated intermediate (E approximately P) decreases during the initial phase, and suggested that the burst phase is due to transition of the kd value. Recently, Froehlich and Taylor (J. Biol. Chem. 250, 2013--2021 (1975)) claimed that the Pi burst is caused by the formation of an acid-labile intermediate containing phosphate (E.P) formed by rapid hydrolysis of E approximately P. In the present study, the transition of the kd value during the initial phase was measured precisely, and the results showed that the burst phase is due to a transition in the kd value, not to the existence of E-P. The main results obtained were as follows: 1. After the SR had been phosphorylated with [gamma-32P]ATP in the presence of Mg2+ and Ca2+ ions, further phosphorylated was stopped by the addition of EGTA. The concentration of E approximately 32P then decreased exponentially with time. 2. The first-order rate constants, kd, of decomposition of E aproximately 32P after adding EGTA decreased with increase in the interval, t, between the start of E approximately 32P formation and the time of adding EGTA...

Adenosine Triphosphatases↗
PubMed1975

Direct association of messenger RNA with microsomal membranes in human diploid fibroblasts.

Messenger RNA (mRNA) of membrane-bound polysomes in a membrane fraction of WI-38 cells remains associated with the microsomal membranes even after ribosomes and their nascent polypeptide chains are removed by using puromycin in a high salt buffer or by disassembling the ribosomes in a medium of high ionic strength lacking magnesium. mRNA either was specifically labeled in the presence of actinomycin D, or it was recognized by virtue of its affinity for oligo-dT. Poly A segments in bound mRNAs have an electrophoretic mobility in acrylamide gels which is characteristic of cytoplasmic mRNAs and corresponds to 150-200 adenyl residues. Extensive RNase treatment did not lead to release of the poly A segments of membrane-associated mRNA molecules either from an intact membrane fraction or from a membrane fraction previously stripped of ribosomes. On the other hand, RNase treatment led to the release and digestion of the nonpoly A segments of the mRNA molecules, indicating that the site of attachment of mRNA to the ER membranes is located near or at the 3' end of the molecule which contains the poly A. A direct association of mRNAs and endoplasmic reticulum membranes is considered in a modelto explain the assembly of bound polysomes and protein synthesis in a membrane-associated apparatus.

Adenosine Monophosphate↗
PubMed1975

Inhibition of Ca2+ uptake into fragmented sarcoplasmic reticulum by antibodies against purified Ca2+, Mg2+-dependent ATPase.

Rabbit antiserum was prepared against a partially purified Ca2+, Mg2+-dependent ATPase [EC 3.6.1.3] of the SR isolated from chicken skeletal muscle. The gamma-globulin fraction of antiserum contained antibodies which combined with the purified ATPase and the SR vesicles. Binding of the antibodies strongly inhibited active transport of Ca2+ ions into the SR, but not passive leakage of Ca2+ ions from the SR. The antibodies scarcely affected the ATPase activity.

Adenosine Triphosphatases↗