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Biomedical subjects

S Hirose

Publications and source records attributed to S Hirose.

At least 829 records · Page 46Linked to original sources
PubMed1981

Possible mechanism of inhibition by polyamines of lipid peroxidation in rat liver microsomes.

The rate of malondialdehyde formation in rat liver microsomes decreased as concentration of spermine added to the reaction mixture was increased. Inhibitory effect on lipid peroxidation was observed even when spermine was added at 15 min after the onset of reaction. Microsomal lipid peroxidation was markedly increased when extracted lipids were added to the reaction mixture. It was, moreover, found that in the presence of exogeneous microsomal lipids, spermine inhibition was weakened. The character of spermine inhibition with respect to the amounts of exogeneous and endogeneous lipids was shown to be competitive. From these results, it was suggested that spermine interaction with microsomal lipids may be responsible for the inhibition of lipid peroxidation.

Animals↗
PubMed1980

Effects of macrocyclic polyamines and polymethylenediamines on reactions influenced by polyamines.

The effects of macrocyclic polyamines and polymethylenediamines on various reactions influenced by polyamines have been studied. Among the amines tested, 2,3,4,3- and 3,3,3,4-cyclic polyamines, NH2(CH2)6NH2 and NH2(CH2)8NH2 had some ability to stimulate polyphenylalanine synthesis, globin synthesis and rat liver isoleucyl-tRNA formation. The degree of stimulation was at most 40% of that obtained by polyamines. In the degradation of poly(C) by bovine pancreatic RNAase A, all tested amines stimulated the degradation. In the NADPH-dependent lipid peroxidation of rat liver microsomes, the degree of inhibition by 2,3,2,3- or 2,3,3,3-cyclic polyamine was greater than that by spermine. The hydrolysis of ATP by an oligomycin-sensitive ATPase was inhibited by 2,3,4,3- and 3,3,3,4-cyclic polyamines, NH2(CH2)10HN2 and spermine at somewhat comparable levels. None of the macrocyclic polyamines or polymethylenediamines stimulated the growth of a polyamine-requiring mutant of Escherichia coli. Possible explanations for the differences in the effects of amines on the various reactions are discussed.

Adenosine Triphosphatases↗
PubMed1980

A microsomal endoribonuclease from rat liver.

An endoribonuclease has been purified about 320-fold from the microsomes of rat liver. The enzyme had an apparent molecular weight of 54 000-58 000 and produced oligonucleotides, each consisting of 3-7 nucleotides from poly(A) and poly(U). No mononucleotide was obtained by the enzymatic hydrolysis of poly(A) and poly(U) under standard coditions. The relative rates of breakdown of synthetic polynucleotides by the enzyme under standard conditions were in the order poly(U) = poly(A) > poly(C). Divalent cations (Mg2+ or Mn2+) was required for the enzymatic activity, but monovalent cations (Na+, K+ or NH4+) inhibited the enzyme. The breakdown of poly(C) and poly(U) by the enzyme was inhibited by spermine, but that of poly(A) was not influenced by spermine. The enzyme was inhibited by p-chloromercuribenzoate and poly(G), but not by rat-liver ribonuclease-inhibitor and anti-RNase A serum.

Animals↗
PubMed1980

Renin and prorenin in hog brain: ubiquitous distribution and high concentration in the pituitary and pineal.

With the objective of clarifying the nature of renin-like activity in the brain, we have devised methods to distinguish true renin from acid protease. These methods were used to determine the regional distribution of true renin in hog brain. The pineal was found to be the richest source of renin followed by the adenohypophysis and choroid plexus. The hypothalamus, cerebellum and amygdala contained moderately high concentrations of renin. Renin concentration in the neurohypophysis was negligible. Many regions contained activatable prorenin. The molecular weight and the pH-dependence of the brain renin were identical to these same properties of renal and plasma renins. Based upon its specific affinity to concanavalin A, brain renin was judged to be a glycoprotein. The electrofocusing pattern of renin from different regions of the brain differed from that of plasma and kidney renins, a discrepancy which could be interpreted as evidence for the endogenous synthesis of renin in the brain.

Angiotensin I↗
PubMed1980

Clinical experiences with left gastric vena caval shunt in patients with esophageal varices.

Left gastric vena caval shunt (Inokuchi) was performed in four patients with liver cirrhosis; electively in two and prophylactically in two cases. The overall results have been satisfactory in terms of the effect on esophageal varices and postoperative complications. This procedure appeared to be superior to distal splenorenal shunt or other direct surgical procedures in several aspects. Since left gastric vena caval shunt does not require particularly elaborate surgical techniques and can be performed safely even in patients with considerably impaired hepatic function, it can be recommended as an ideal surgical procedure to be performed in elective and prophylactic surgical candidates.

Adult↗
PubMed1980

Indirect hyperbilirubinemia in HBV carriers.

Indirect hyperbilirubinemia without any other abnormalities of liver function tests was seen in 14.3% in HBV carriers and 1.2% in controls in the previous study. In order to clarify the mechanism of hyperbilirubinemia in HBV carriers, 33 HBV carriers with normal liver functions regardless of hyperbilirubinemia and with no past history of acute hepatitis were investigated clinically. Most of HBV carriers with indirect hyperbilirubinemia revealed any other abnormalities of liver functions during the over 2 years observation. Histological examinations of 4 HBV carriers with hyperbilirubinemia presented no evidence of obvious hepatitis. There was no significant correlation between bilirubin, ICG and/or BSP clearance in HBV carriers with hyperbilirubinemia. The above mentioned facts suggest that indirect hyperbilirubinemia in HBV carriers was not caused by organic changes of hepatocytes but might be the results of, at least in part, its functional disturbances. Family studies of HBV carriers with hyperbilirubinemia suggested that some but not all the HBV carriers with indirect hyperbilirubinemia might not have a genetic background in common with patients with Gilbert's syndrome. The persistent infection of HBV in hepatocytes might play an important role of metabolic derangement of bilirubin and make a constitutional defect of bilirubin metabolism manifest.

Bilirubin↗
PubMed1980

Renin precursor and its activation mechanism in hog kidney.

1. A completely inactive renin was isolated from hog kidney extract by affinity chromatography on pepstatin-aminohexyl-Sepharose and on an Affi-Gel Blue column. 2. This inactive renin had a molecular weight of 43 000 +/- 1500 as determined by gel filtration on Ultrogel AcA 44. Upon activation with trypsin, its molecular weight fell to 41 000 +/- 1400. 3. The inactive renin lacked the ability to bind renin-binding substance whereas trypsin-activated renin was able to bind the renin-binding protein and to form high-molecular-weight renin. 4. Chymotrypsin as well as trypsin could activate the inactive renin although less effectively. 5. The active renins generated from the inactive renin by the action of different proteolytic enzymes differed in their net charge, reflecting the specificities of the proteases used; the isoelectric points of the native, the trypsin-activated and the chymotrypsin-activated forms of renin occurred at pH 5.3, 5.1 and 4.8 respectively.

Animals↗
PubMed1980

Renin in rat and mouse brain: immunohistochemical identification and localization.

1. Localization of renin in rat and mouse brain was determined by immunohistochemical methods with specific anti-renin antibodies. 2. Renin-containing neuronal cells were found in the medulla oblongata, cerebellar nuclei and hypothalamus. Purkinje cells contained renin. 3. Glia-like cells contained renin. Some of them are closely associated with vascular walls and these vascular walls were renin positive. 4. The pineal gland, adenohypophysis and choroid plexus contained renin. 5. The extensive distribution of renin suggests functions other than those which have been associated with the hypothalamus.

Animals↗