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Biomedical subjects

K Satoh

Publications and source records attributed to K Satoh.

At least 1,261 records · Page 70Linked to original sources
PubMed1976

Isozyme patterns of glycogen phosphorylase in rat tissues and transplantable hepatomas.

Isozyme patterns of glycogen phosphorylase in the Morris and Yoshida hepatomas were compared electrophoretically and immunochemically with those in rat tissues during development. A 3rd phosphorylase isozyme, observed previously in hepatomas and fetal tissues by isoelectric focusing and by immunochemical titration, was also separated by polyacrylamide disc gel electrophoresis. It was observed commonly in various rat hepatomas, together with variable activities of the liver type, depending on the degree of differentiation. This isozyme is nearly the sole type in placenta and early embryo, and in liver and skeletal muscle it is replaced during fetal development with the organ-specific liver and muscle type. In adult rat brain the fetal type is retained at low levels, together with the muscle type. In kidney, spleen, testis, uterus, lung, and stomach, the fetal type is present together with the liver type. This isozyme in hepatomas and adult brain is identical with the fetal-type, as determined by Ouchterlony double diffusion and activity inhibition tests. Thus, it is considered to be a prototype whose appearance in hepatomas is one of many known examples of fetal protein expression in cancer. In some poorly differentiated hepatomas, the liver-type isozyme migrated slightly more slowly in polyacrylamide gel but could not be distinguished from the liver isozyme immunochemically.

Animals↗
PubMed1972

Prostaglandins and their effects on human placental adenyl cyclase.

Prostaglandins increased adenyl cyclase activity in human term placental homogenates in a dose-dependent manner during 10-min incubation periods. The potency of the prostaglandins examined was demonstrated to be in the ascending order, prostaglandin F(1alpha) < A(2), F(2alpha), B(2) < A(1) < E(2) < E(1). Although no specific trophic or regulating factors for placental function have been described as yet, it is possible that prostaglandins which are synthesized in decidual tissue could play such a physiological role.

Adenylyl Cyclases↗
PubMed1969

Oligonucleotide studies. Optical rotatory dispersion of five homodinucleotides.

1. The optical rotatory dispersion (ORD) of five homodinucleotides, ApAp(3'), CpCp(3'), GpGp(3'), IpIp(3') and UpUp(3') (where A, C, G, I and U represent adenosine, cytidine, guanosine, inosine and uridine respectively, and p to the left of a nucleoside symbol indicates a 5'-phosphate and to the right it indicates a 3'-phosphate), were measured as a function of pH, ionic strength and Mg(2+) concentration. 2. The ORD titrations of ApAp(3') and CpCp(3'), which were made by measuring the ORD curves at closely spaced pH intervals, exhibit a maximum at approx. pH5.0 and 5.7 for ApAp(3') and CpCp(3') respectively in the profile of the magnitude of the first Cotton effect versus pH. The results indicate that the conformational rigidity of these dinucleotides depends on the ionization state of a 3'-terminal phosphate group. 3. ApAp(3') was shown to exist as an approximately 1:1 equilibrium mixture of the two major ionic species represented by Ap((-1))Ap((-1)) and Ap((-1))Ap((-2)) at pH6.16, whereas at pH7.5 it exists exclusively as a form of Ap((-1))Ap((-2)). 4. To ascertain the effects of the presence of a terminal phosphate group and of the ionization of the secondary phosphate on the conformation of adenylate dimer, we measured the ORD of ApA, ApAp(3')CH(3) and ApAp(2'). The rotatory power of the first Cotton effect in the above series of dinucleotides decreased at 20 degrees in the order ApA> ApAp(3')CH(3) approximately ApAp(3')((-1))> ApAp(2') at pH7> ApAp(3') at pH7. 5. The pH-rotation profiles were also obtained for ApAp(2'), CpCp(2') and UpUp(3'), but no corresponding maximum was observed. Although simple nearest-neighbour calculations based on the ORD data of IpIp(3') and 5'-IMP account for the observed ORD spectrum of polyinosinic acid at low salt concentration, there were large discrepancies between calculated and experimental results of the polyguanylic acid ORD even at low ionic strength. 6. The extent to which the amplitude of the Cotton effects of IpIp(3') increases with salt concentration, especially by the addition of Mg(2+), was much greater than that observed for ApAp(3'). The implication of such salt effects on the ORD is considered.

Adenine Nucleotides↗
PubMed1969

Ion-exchangechrmtography of a dinucleotide preparation from controlled alkaline hydrolysis of ribonucleic acids.

With the aim of preparing the 16 possible ribodinucleotides derived from the four principal ribonucleotides, we made a kinetic study to determine the optimum conditions for a partial alkaline hydrolysis of RNA. Satisfactory results were obtained when the hydrolysis of RNA (1g.) in 0.2m-sodium hydroxide (100ml.) at 37 degrees was ceased approx. 10min. after the start of the reaction. The relative yields of the monomer, dimer and trimer fractions were approx. 41:30:15 in E(260) units, indicating that the reaction conditions were reasonably close to those required from kinetic considerations. The partial alkaline hydrolysate was chromatographed on a column of DEAE-Sephadex A-25 in the presence of 7m-urea. The dinucleotide fraction thus obtained was subjected to a subsequent chromatography on Dowex 1 (X2) under acidic conditions to separate the mixture according to base composition and base sequence. The results were satisfactory, and most of the 32 dinucleotides [i.e. 16 XpYp(3') plus 16 XpYp(2')] were fractionated by this single chromatographic procedure. The present method should be useful for further study of oligonucleotides as a time-saving method for the simultaneous preparation of a variety of dinucleotides. Further, examination of the present chromatographic pattern has provided several empirical criteria useful for the identification of oligonucleotides other than dimers appearing in the elution profile of Dowex 1 (X2) column chromatography under similar conditions.

Chromatography↗