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Biomedical subjects

S Kim

Publications and source records attributed to S Kim.

At least 1,459 records · Page 81Linked to original sources
PubMed1978

Development of a method of evaluating cardiac performance using interactive computer graphics.

The authors discuss an objective method of analyzing local wall motion to detect and measure the pattern of contraction of the left ventricle using computer graphics. The method's advantages include: (a) the use of modular hardward and software, which can be extended and upgraded; (b) a minimal expenditure of time and money; (c) uniformly calculated results; and (d) a graphic and legible report.

Computers↗
PubMed1977

Cytochrome c-specific protein methylase III from Neurospora crassa.

A protein methylase III responsible for specifically methylating the cytochrome c in Neurospora crassa was partially characterized by using unmethylated horse heart cytochrome c as a substrate. This enzyme utilizes S-adenosyl-L-methionine as the methyl donor. An analysis of the distribution of [14C]methyl groups in the peptides obtained by chymotrypsin digestion of the enzymically methylated cytochrome c showed that all of the radioactivity could be recovered within a single peak after chromatography. This indicates that the enzyme methylates a specific amino acid sequence within cytochrome c. On hydrolysis of the radioactive chymotryptic peptide, Me-14C-labelled epsilon -N-mono-methyl-lysine, epsilon-N-dimethyl-lysine and epsilon-N-trimethyl-lysine were identified. The enzyme can easily be extracted from the N. crassa mycelial pads and was purified approx. 30-fold.

Chymotrypsin↗
PubMed1977

S-adenosylmethionine: protein-arginine methyltransferase. Purification and mechanism of the enzyme.

Protein methylase I (S-adenosylmethionine: protein-arginine methyltransferase, EC 2.1.1.23) has been purified from calf brain approximately 120-fold with a 14% yield. The final preparation is completely free of any other protein-specific methyltransferases and endogenous substrate protein. The enzyme has an optimum pH of 7.2 and pI value of 5.1. The Km values for S-adenosyl-L-methionine, histone H4, and an ancephalitogenic basic protein are 7.6 X 10(-6), 2.5 X 10(-5), and 7.1 X 10(-5) M, respectively, and the Ki value for S-adenosyl-L-homocysteine is 2.62 X 10(-6) M. The enzyme is highly specific for the arginine residues of protein, and the end products after hydrolysis of the methylated protein are NG,NG-di(asymmetric), NG,N'G-di(symmetric), and NG-monomethylarginine. The ratio of [14C]methyl incorporation into these derivatives by enzyme preparation at varying stages of purification remains unchanged at 40:5:55, strongly indicating that a single enzyme is involved in the synthesis of the three arginine derivatives. The kinetic mechanism of the protein methylase I reaction was studied with the purified enzyme. Initial velocity patterns converging at a point on the extended axis of abscissas were obtained with either histone H4 or S-adenosyl-L-methionine as the varied substrate. Product inhibition by S-adenosyl-L-homocysteine with S-adenosyl-L-methionine as the varied substrate was competitive regardless of whether or not the enzyme was saturated with histone H4. On the other hand, when histone H4 is the variable substrate, noncompetitive inhibition was obtained with S-adenosyl-L-homocysteine under conditions where the enzyme is not saturated with the other substrate, S-adenosyl-L-methionine. These results suggest that the mechanism of the protein methylase I reaction is a Sequential Ordered Bi Bi mechanism with S-adenosyl-L-methionine as the first substrate, histone H4 as the second substrate, methylated histone H4 as the first product, and S-adenosyl-L-homocysteine as the second product released.

Animals↗
PubMed1977

Protein bound carboxyl-methyl ester as a precursor of methanol formation during oxidation of dimethylnitrosamine in vitro.

Protein modification with dimethylnitrosamine was studied in vitro in the presence of hamster liver microsomal fraction. Incorporation of radioactive methyl groups from dimethylnitrosamine into the exogenously added protein was dependent on the microsomal mixed function oxidase system. The methylation yielded chemically labile and stable products. The former was completely hydrolyzed by the mild alkaline treatment, pH 7.4, 100 degrees C, for 5 min and the hydrolytic product was identified as methanol indicating that the activated methyl groups from dimethylnitrosamine were incorporated into a protein as a carboxyl-methyl ester. Thus, it is suggested that methanol, recovered as one of the products during the biodegradation of dimethylnitrosamine [8], is derived, at least in part, from protein carboxyl-methyl ester which is unstable under physiological conditions.

Animals↗
PubMed1977

Enzymatic methyl esterification of Escherichia coli ribosomal proteins.

Enzymatic methyl ester formation in Escherichia coli ribosomal proteins was observed. Alkali lability of the methylated proteins and derivatization of the methyl groups as methyl esters of 3,5-dinitrobenzoate indicate the presence of protein methyl esters. The esterification reaction occurs predominantly on the 30S ribosomal subunit, with protein S3 as the major esterified protein. When the purified 30S subunit was used as the methyl acceptor, protein S9 was also found to be esterified. The enzyme responsible for the esterification of free carboxyl groups in proteins, protein methylase II (S-adenosyl-L-methionine:protein carboxyl methyltransferase, EC 2.1.1.24), was identified in E. coli Q13. This enzyme is extremely unstable when compared with that from mammalian origin. By molecular sieve chromatography, E. coli protein methylase II showed multiple peaks, with a major broad peak around 120,000 daltons and several minor peaks in the lower-molecular-weight region. Rechromatography of the major enzyme peak showed activities in several fractions that are much lower in molecular weight. The substrate specificity of the E. coli enzyme is similar to that of the mammalian enzyme. The Km value for S-adenosyl-L-methionine is 1.96 X 10(-6) M, and S-adenosyl-L-homocysteine was found to be a competitive inhibitor, with a Ki value of 1.75 X 10(-6) M.

Chromatography, Gel↗
PubMed1977

New technique for pelvic venography during ascending phlebography.

A technique of pelvic venography making it possible to obtain satisfactory opacification of the iliofemoral segment of the pelvic veins consistently during ascending phlebography is described. The main features are the compression of the inferior vena cava with a compression band and balloon, and the use of a large amount of contrast material.

Humans↗
PubMed1977

Approximation of the left ventricle by a cone of revolution using biplane measurements.

A new method based only on area measurements was developed for calculating left ventricular volume from biplane (RAO and LAO) left ventriculograms; the ventricle was approximated by a cone of revolution. Twenty-three patients with normal and 23 patients with abnormal left ventricles were studied. The Dodge method provided reference values. There was no significant difference between values for EDV calculated by either method; values for ESV calculated by the cone method were consistently higher, but the error is acceptable. The cone method provides results similar to those obtained by the corrected Dodge method, eliminating the problem of choosing and measuring the long axis.

Cineangiography↗
PubMed1977

Comparison of the left ventricular volume using the Ahlkerg and Dodge methods.

Single plane cine left ventriculography was performed in 24 patients, 12 with normal and 12 with abnormal ventricular shapes. End diastolic and systolic volume and ejection fractions were calculated by two methods (Ahlberg and Dodge). The volumes and ejection fraction from either method were not significantly different. If calculated manually, the Ahlberg method took ten times longer than the Dodge method. At present some steps are difficult but a computer can perform the measurements and calculations, and print the results for ventricular areas.

Angiocardiography↗
PubMed1977

Diminished ketosis and triglyceridemia during fasting in odd-carbon enriched pregnant rats.

The lipolysis, ketosis and hypertriglyceridemia of fasted rats in late pregnancy may be related to decreased insulin secretion geared to decreased glucose availability. In odd-carbon fatty acid enriched (OCE) rats, the odd-carbon fatty acids (OCFA) mobilized during fasting provide terminal three-carbon residues which are glucogenic, thereby permitting blood glucose and insulin to be maintained close to fed levels. The present study has used OCE rats to evaluate the role of insulin in the altered fat metabolism of the fasted rats in late pregnancy. The adipose tissue of 24 female Sprague-Dawley rats was enriched to more than 25% undecanoate (c11:0) and higher OCFA by feeding them a complete diet high in triundecanoin content for six weeks. Twenty-four female controls were fed a similar diet except that the fat was exclusively corn oil. Both OCE and control rats were than mated and on day 18 of pregnancy were divided into four groups: one group was killed fed, one after a 24 h fast, and one after a 48 h fast; the fourth group was fed to day 20 of pregnancy and then killed. In the fed state, the concentrations of glucose, ketones, and cholesterol in serum, as well as that of glycogen in liver, were the same in control and OCE rats. Insulin and triglycerides were similarly elevated in the two groups. After two days of fasting, serum glucose, insulin, and liver glycogen concentrations were significantly higher in OCE than in control rats, while ketones and triglycerides were significantly lower. No significant changes occurred in serum cholesterol. The results are consistent with a predominantly insulin effect in the pregnant OCE rats in diminsihing the marked fasting lipolysis, hyperketonemia and hypertriglyceridemia observed in controls, but do not rule out inhibition of FFA release by in situ re-esterification to glycerol derived from glucose or propionic acid.

Acidosis↗
PubMed1977

Effect of hydrocortisone on ammonia intoxication in the adrenalectomized rat.

Adrenalectomy induces a hypersensitivity in the rat to ammonia intoxication. Daily injection of hydrocortisone hydrochloride to adrenalectomized rats restored normal sensitivity to ammonia intoxication, with concomitant restoration of liver urea-synthesizing capacity to the normal value. When injected with a large dose of ammonium acetate, hydrocortisone-treated adrenalectomized rats were able to reduce the plasma ammonia concentration much more rapidly than the adrenalectomized control rats. However, neither the increase in liver urea synthesis nor the more rapid decrease in the plasma ammonia concentration were sufficient to explain the protective aciton of hydrocortisone against ammonia intoxication.

Adrenalectomy↗