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Biomedical subjects

S Miyazawa

Publications and source records attributed to S Miyazawa.

At least 91 records · Page 5Linked to original sources
PubMed1985

[Evaluation of regurgitant fraction of aortic regurgitation by means of pulsed Doppler echocardiography as compared with cine angiography].

The regurgitant fraction (RF) of aortic regurgitation (AR) was calculated using pulsed Doppler echocardiography (PDE), and the results were compared with those of aortography. Two-dimensional echocardiography (2DE), PDE and cine angiography were performed for 33 patients, including nine in whom aortic regurgitation (AR) was ruled out by contrast 2DE and 24 in whom AR was confirmed by aortography (AOG). The latter were subdivided into six of Sellers' degree I, seven of degree II, eight of degree III and three of degree IV. Sampling was obtained from the main pulmonary artery, the left ventricular outflow tract, and the mean circulation velocity (f1) was calculated from the power spectrum wave pattern obtained from each source. With the following formula, Qp (pulmonary arterial blood flow), Qs (left ventricular ejection blood flow) and RF [= (Qs--Qp)/Qs] were calculated, and compared with the findings obtained from invasive methods: (formula; see text) (L = vascular diameter; theta = angle of incidence; C = velocity of sound; fo = oscillating frequency; ET = ejection time; HR = heart rate) A correlation of r = 0.81 was found between Qp calculated with PDE and right cardiac output (CO) by the thermodilution method. A correlation of r = 0.66 was observed between Qs and left ventricular ejection volume obtained from left ventriculography using Dodge's method. Comparison of RF using Sellers' classification with AOG revealed that the RF in the group uncomplicated with AR was 0.14 +/- 0.10, and Sellers' degrees I, 0.27 +/- 0.08; II, 0.36 +/- 0.04; III, 0.53 +/- 0.05; and IV, 0.64 +/- 0.06, indicating consistency with severity and RF.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve Insufficiency↗
PubMed1984

Biosynthesis of enzymes of rat-liver mitochondrial beta-oxidation.

The biogenesis of seven enzymes involved in the mitochondrial fatty acid beta-oxidation of rat liver was studied. Hepatic RNA was translated in vitro in a rabbit reticulocyte lysate cell-free system and the translation products were immunoprecipitated, subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and visualized by fluorography. The translation products obtained in vitro of medium-chain and/or long-chain acyl-CoA dehydrogenase (these enzymes were immunochemically cross-reactive), enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and acetoacetyl-CoA thiolase and probably also short-chain acyl-CoA dehydrogenase were larger than the subunits of the corresponding mature enzymes by 2-4.5 kDa, whereas the 3-oxoacyl-CoA thiolase obtained in vitro was approximately the same size as the mature subunit. The free polysome fraction of rat liver was 4.3-9.0-times more active than the membrane-bound polysome fraction in the synthesis of these seven enzymes. The enzyme activities were increased after administration of di(2-ethylhexyl)phthalate; the extent of the increase varied from one enzyme to another. The increase in the cell-free translation activity of total hepatic RNA for these enzymes after administration of the chemical was markedly different among individual enzymes and higher than that in the rates of synthesis of the corresponding enzymes which were determined by the experiment in vivo.

Animals↗
PubMed1984

Molecular cloning of cDNA for rat liver catalase.

For the studies on the induction of peroxisomal enzymes by hypolipidemic agents, we have tried to isolate a cDNA clone for rat liver catalase. A recombinant clone, pMJ501, was isolated, of which cDNA insert specifically hybridized to catalase mRNA in hybridization-selected translation. On RNA blot hybridization, it hybridized to 2.4-kilobases RNA which was increased about 1.5-fold by the administration of di-(2-ethylhexyl)phthalate to the rats. The nucleotide sequence of the cDNA contains a reading frame for 109 amino acid residues which match the reported amino acid sequence of bovine liver catalase at the carboxyl end with 82% homology. It is concluded that pMJ501 contains a cDNA sequence for rat liver catalase.

Amino Acid Sequence↗
PubMed1984

Biosynthesis and intracellular transport of enzymes of peroxisomal beta-oxidation.

Three peroxisomal enzymes of beta-oxidation from rat liver were synthesized in a cell-free protein-synthesizing system derived from a lysate of rabbit reticulocytes. The in vitro products of acyl-CoA oxidase (EC 1.3.99.3) and a bifunctional protein containing enoyl-CoA hydratase (EC 4.2.1.17) and 3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) activities were apparently the same in size and charge as the subunit of the respective mature enzymes; that of 3-ketoacyl-CoA thiolase (EC 2.3.1.16) was about 3,000 Da larger and more basic than its mature subunit. The free polysome fraction of rat liver was 3.1-5.7 times more active than the membrane-bound polysome fraction in the synthesis of the three peroxisomal enzymes; these values were similar to those for cytosolic enzymes and differed from that for serum albumin. In isolated rat hepatocytes, radiolabeled acyl-CoA oxidase and bifunctional protein increased with time with no appreciable change in the subunit size. On the other hand, the labeled putative precursor of 3-ketoacyl-CoA thiolase, as well as the mature form of the enzyme, was detected in the hepatocytes. The radioactivity of the putative precursor reached a plateau in 30 min; that of the mature subunit appeared after a lag time of about 5 min and increased with time up to 90 min. In pulse-chase experiments, the putative precursor disappeared with an apparent half-life of several minutes. When the hepatocytes were fractionated into the cytosolic and the particulate fractions, one half of labeled acyl-CoA oxidase and 60% of the bifunctional protein were recovered in the cytosolic fraction after 10 min of labeling, whereas 70-80% of the labeled enzymes were recovered in the particulate fraction after 40-60 min of labeling. These results indicate that the three enzymes of peroxisomal beta-oxidation are synthesized on free polysomes, released into the cytosol, and then transported into peroxisomes. Our findings also indicate that 3-ketoacyl-CoA thiolase undergoes proteolytic processing during maturation. The temporal sequence of the proteolytic cleavage and intracellular transport of the thiolase remains to be determined.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1984

[Problems in estimating the severity of aortic regurgitation by pulsed Doppler echocardiography: with special reference to its distribution pattern].

We categorized the findings of aortic regurgitation (AR) by aortography (AOG) into the following four types, and compared them with the corresponding findings obtained by pulsed Doppler echocardiography (PDE) in 30 patients, and assessed the ability of PDE to observe the distribution of an aortic regurgitant flow. Type 1: A wide regurgitant jet distributed within the entire left ventricle (5 cases). Type 2: A narrow regurgitant jet passing through the center of the left ventricular outflow tract (9 cases). Type 3: A regurgitant jet with the shift of its direction to the either side (10 cases). Type 4: A regurgitant jet which is localized below the aortic valve (6 cases). AOG findings in 40% of Type 1 cases, 78% of Type 2, 80% of Type 3 and 67% of Type 4 were well consistent with those of PDE (an average of 70%). Therefore, we could predict the distribution of AR by PDE, although a correlation between both methods was not complete. The reasons of the inconsistence of these two methods were discussed. PDE is an possible method for evaluating the severity of AR.

Aortic Valve Insufficiency↗
PubMed1983

Purification and properties of carnitine acetyltransferase from rat liver.

Carnitine acetyltransferase was purified from rat liver after induction of the enzyme by feeding with di(2-ethylhexyl)phthalate. Two enzyme sources were used: the mitochondrial fraction and the homogenate of the liver. The purification procedure was essentially the same for the two enzyme sources. The enzyme purified from the mitochondrial fraction consisted of two different polypeptides with molecular weights of 36,500 and 27,000, whereas that from the homogenate consisted of one polypeptide with a molecular weight of 67,500. Amino acid compositions and peptide maps of the limited proteolytic products of the two enzyme preparations were nearly the same. Their antibodies were cross-reactive. Catalytic properties of the two preparations were nearly the same: the specific enzyme activities, double reciprocal plots of initial velocity study, substrate specificities for acylcarnitines having various carbon chain lengths, apparent Michaelis constants for substrates. On electrophoresis of the immunoprecipitate obtained after incubation of the mitochondrial extract, the two immunoreactive polypeptides with molecular weights of 36,500 and 27,000 were found. But only one polypeptide, with molecular weight of 67,500, was detected when the protease inhibitors were added to the mitochondrial extract. It was concluded that the enzyme in the mitochondrial fraction was a monomeric form but was converted into a dimeric form by proteolytic modification after the disruption of mitochondria. The preparation from the post-mitochondrial fraction, which had a lower specific activity, contained two polypeptides whose molecular weights were 69,000 and 67,500. They could not be separated from each other throughout the purification. The peptide maps of the products of the limited proteolysis were very similar.

Acetyltransferases↗
PubMed1983

Biosynthesis and turnover of carnitine acetyltransferase in rat liver.

Male Wistar rats were fed on a diet with and without di(2-ethylhexyl)phthalate (DEHP) for 2 weeks. Carnitine acetyltransferase in the liver was increased about 100-fold by administration of DEHP. The results of in vivo experiments showed that the incorporation of L-[4,5-3H]leucine into the enzyme was 12-fold higher and the half-life of the labeled enzyme was elongated by a factor 4.6. The results of in vitro translation experiments with total hepatic RNA in a rabbit reticulocytelysate system and the results concerning the synthesis of the enzyme in isolated hepatocytes indicate that the translatable mRNA for the enzyme was increased upon administration of DEHP and that the enzyme is synthesized as a precursor (Mw = 69,000) larger than the mature enzyme (Mw = 67,500). RNA in the free polysomes directed the synthesis of the enzyme precursor five times more actively than RNA in membrane-bound polysomes.

Acetyltransferases↗
PubMed1983

Purification and properties of carnitine octanoyltransferase and carnitine palmitoyltransferase from rat liver.

The activities of carnitine octanoyltransferase (COT) and carnitine palmitoyltransferase (CPT) in rat liver were markedly increased by administration of di(2-ethyl-hexyl)phthalate. COT and CPT were purified from the enzyme-induced rat liver. COT was a 66,000-dalton polypeptide. The molecular weight of native CPT was 280,000--320,000 daltons, and the enzyme consisted of 69,200-dalton polypeptides. CAT, COT, and CPT were immunologically different. COT exhibited activity with all of the substrates tested (acyl-CoA's and acylcarnitines of saturated fatty acids having carbon chain lengths of C2--C20), though maximum activity was observed with hexanoyl derivatives. CPT exhibited catalytic activity with medium- and long-chain acyl derivatives. 2-Bromo-palmitoyl-CoA inactivated COT but not CPT. Malonyl-CoA inhibited CPT but not COT. CPT was confined to mitochondria, whereas COT was found in peroxisomes and the soluble compartment but not in mitochondria.

Acyltransferases↗
PubMed1983

Biosynthesis of carnitine octanoyltransferase and carnitine palmitoyltransferase.

Male Wistar rats were fed a diet with or without di(2-ethylhexyl)phthalate (DEHP) for 2 weeks. Carnitine octanoyltransferase (COT) in the liver was increased 23.5-fold in rats given DEHP. It was found by in vivo experiments using L-[4,5-3H]leucine and the immunoprecipitation technique that the rate of synthesis of COT was 14.1-fold higher and that of its degradation was 1.5-fold lower in the DEHP group. COT was translated much more effectively in free polysomes than in membrane-bound polysomes. The molecular size of the in vitro product was the same as that of the mature enzyme. The translation activity of mRNA coding for COT measured with total hepatic RNA was 16.6-fold higher in the DEHP group. Carnitine palmitoyltransferase (CPT) was increased 5.9-fold after administration of DEHP. The rate of synthesis of CPT measured in the in vivo experiment was 5.0-fold higher in the DEHP group. The rate of its degradation was the same in the two groups. CPT was also translated much more effectively in free polysomes. The size of the preenzyme was larger than that of the subunit of the mature enzyme by about 2,400 daltons. In contrast to COT, the increase in the translation activity of mRNA for CPT by administration of DEHP was markedly higher than the increase in the rate of its synthesis measured in the in vivo experiment.

Acyltransferases↗