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Biomedical subjects

S Kim

Publications and source records attributed to S Kim.

At least 1,387 records · Page 77Linked to original sources
PubMed1983

Studies on compartmentation of S-adenosyl-L-methionine in Saccharomyces cerevisiae and isolated rat hepatocytes.

The existence of metabolically distinct pools of S-adenosyl-L-methionine in Saccharomyces cerevisiae and isolated rat hepatocytes was investigated. Utilizing a relatively long labeling period with [methyl-14C]methionine, a metabolically 'stable' pool was labeled. A subsequent short labeling with [methyl-3H]methionine selectively labeled a putative metabolically 'labile' pool. The existence of these distinguishable pools was ascertained by following the 3H and 14C label disappearance in S-adenosyl-L-methionine during the chase-period in label-free media containing cycloleucine to prevent further synthesis of S-adenosyl-L-methionine. In both yeast and hepatocytes, the 3H/14C ratio in S-adenosyl-L-methionine decreased sharply. The individual 3H and 14C decrease in S-adenosyl-L-methionine showed t1/2 values of 3 and 8 min for yeast and 4 and 18 min for hepatocytes. The results strongly indicate that at least two metabolically distinct S-adenosyl-L-methionine pools actually do exist in both systems. Subcellular fractionation revealed that the 'labile' pool exist in the cytosol for both yeast and hepatocytes while the 'stable' pool exists in the vacuolar and the mitochondrial fraction for the yeast and hepatocytes respectively. The S-adenosyl-L-methionine pools were also studied in normal yeast under anaerobic chase condition and petite mutant yeast. Sharply contrasting with aerobically chased normal yeast, both showed closely parallel 3H and 14C decreases in S-adenosyl-L-methionine.

Animals↗
PubMed1983

Preparation of multivesicular liposomes.

A novel type of liposome, named here multivesicular liposomes, was prepared by evaporation of organic solvents from chloroform-ether spherules suspended in water. Within each spherule were numerous water droplets that contained solutes to be trapped in liposomes upon solvent evaporation. Liposome preparations of different average diameters were made, varying from 29 +/- 10 microns to 5.6 +/- 1.7 microns. The liposomes were morphologically characterized by light microscopy and transmission electron microscopy. Materials successfully trapped within the liposomes ranged in molecular size from glucose to nucleic acids. Extremely high percentages of encapsulation (up to 89%) were achieved.

Chemical Phenomena↗
PubMed1983

Applications of carbon dioxide laser surgery and radiation. A preliminary report.

Ten patients with advanced or recurrent squamous cell carcinomas of the upper airway were treated with a combination of carbon dioxide laser surgery and radiation therapy to evaluate the tolerance to rapid sequencing of both modalities in a variety of clinical situations. Other considerations were to accurately stage infiltrating tumors, to provide cytoreduction for T3 and T4 tumors, and to facilitate the optimal placement of intracavitary radium applicators. Because of minimal postoperative pain or dysfunction associated with the laser, patients were able to receive irradiation considerably sooner than with conventional surgery. Local tolerance was good to excellent in seven of the ten patients treated and, based on preliminary results, the combination would appear to offer advantages in curative approaches to advanced head and neck tumors.

Adult↗
PubMed1983

Adjuvant effects of glyceryl esters of acetoacetic acid on rectal absorption of insulin and inulin in rabbits.

The promoting effect of glyceryl esters of acetoacetic acid on the rectal absorption of insulin and inulin was studied. A decrease in the serum glucose level was observed in rabbits following the administration of an insulin suppository containing glyceryl-1,3-diacetoacetate (adjuvant II) or 1,2-isopropylideneglycerine-3-acetoacetate (adjuvant IV). The promoting effects of adjuvants II and IV on the rectal absorption of insulin and inulin were suppressed by the addition of calcium and magnesium to the suppository. This indicates that adjuvant interaction with the calcium and magnesium ion located in the rectal membrane is involved in the enhanced absorption of insulin and inulin. Adjuvant release from the suppository formulation in addition to adjuvant lipid solubility were found to be other important factors for enhanced absorption of insulin and inulin.

Acetoacetates↗
PubMed1983

Measurement of blood flow in the dental pulp of dogs with the 133xenon washout method.

Following rapid injection of 133Xe into the maxillary artery, the radioactivity from a dog canine tooth was monitored with a specially-designed scintillation probe connected to a multichannel analyser. With a PDP 11/10 minicomputer, the semilogarithmic radioactivity-time curve was resolved into a fast component and a slow component using best fit least-square lines and the exponential rate constant (k) was determined for each component. The blood flow per unit of pulp mass (Q, in ml/min per 100 g) was obtained using the equation: Q = k X lambda tb, where lambda tb is the tissue-blood partition coefficient of 133Xe in the pulp determined for the haematocrit value of the individual experiments. The fast-component blood flow was 53.12 +/- 3.12 and the slow-component blood flow was 8.86 +/- 0.53 ml/min per 100 g (mean +/- SEM, n = 21). Although the exact anatomical areas for the fast and slow components are yet to be determined, the results show heterogeneity of blood flow in the pulp. The study showed that pulp blood flow in an intact tooth can be measured with the 133Xe washout method; the method enables study of circulatory physiology of the pulp in health and disease.

Animals↗
PubMed1983

Further investigation of methylation on sickle erythrocyte membranes.

The methylation of erythrocyte membrane proteins has been investigated with fractionated reversible and irreversible sickle erythrocytes to better understand conflicting results obtained from two laboratories (Green and Kalra (6), Ro et al. (1). When subpopulations of intact erythrocytes obtained by two different separation methods (33% bovine serum albumin and Stractan II gradient centrifugations) were incubated with L-[methyl-3H] methionine at pH 7.2 and 37 degrees C, membranes from both reversible and irreversible sickle erythrocyte populations showed about half the [3H]methyl group incorporation than that observed in normal erythrocytes. In addition, this difference in the level of methylation between normal and sickle cells was maintained during the entire course of a 2-hr incubation utilizing S-adenosyl-L-[methyl-3H]methionine, the immediate in vivo methyl donor.

Anemia, Sickle Cell↗
PubMed1983

Purification of protein methylase II from human erythrocytes.

Protein methylase II (S-adenosylmethionine:protein-carboxyl O-methyltransferase, EC. 2.1.1.24) which methyl esterifies free carboxyl groups of protein substrate using S-adenosyl-L-methionine as the methyl donor, has been purified from human erythrocytes approximately 13000-fold with a yield of 12%. The purified enzyme was over 95% pure as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A bulk of hemoglobin present in the erythrocyte lysate, which severely limited the use of affinity chromatography for purification, was effectively removed by ammonium sulfate precipitation and by the subsequent salt washing of the precipitates followed by molecular sieve chromatography on Sephadex G-75. This preparation can be further purified by affinity chromatography, in which S-adenosyl-L-homocysteine is covalently linked to Sepharose-4B, followed by Sephadex G-75 chromatography to yield an enzyme with an activity of 27000 pmol methyl group transferred/mg/min at 37 degrees C.

Chromatography, Affinity↗
PubMed1983

Effect of enamine derivatives on the rectal absorption of insulin in dogs and rabbits.

Enamine derivatives resulting from the reaction between ethyl acetoacetate and amino acids were found to promote rectal absorption of insulin in normal rabbits, with the enamine of sodium DL-phenylalanate being the most effective adjuvant tested. Results of glucose tolerance tests in fasted alloxan diabetic rabbits showed that after oral administration of glucose, insulin suppositories containing enamines derived from either sodium phenylalanine or leucine were able to lower the serum glucose level to within the normal range for more than 2.5 h. The absorption-promoting effect of the sodium DL-phenylalanate enamine on rectal absorption of insulin in dogs was studied in two different formulations, gelatin microenema and suppository. The gelatin microenema containing the insulin solution caused a greater increase in the plasma insulin level than that obtained after administration of an insulin suppository.

Adjuvants, Pharmaceutic↗
PubMed1983

Metabolism of NG-monomethyl-L-arginine.

Rat kidney contains an enzyme which hydrolyzes NG-monomethyl-L-arginine to give rise to the formation of ornithine and N-methylurea. Confirmation of formation of these reaction products is carried out colorimetrically as well as radiochemically employing NG-monomethyl-L-[ornithine-14C(U)]arginine. This pattern of reaction products suggests that the enzyme responsible is an arginase type. However, the kidney enzyme is quite distinct from the hepatic arginase; commercial bovine hepatic arginase (L-arginine amidinohydrolase, EC 3.5.3.1) is completely inactive toward NG-monomethyl-L-arginine. Among various rat tissues examined, the hydrolytic activity is the highest in kidney, followed by the activity in liver and pancreas.

Animals↗
PubMed1983

Butanol extracts from myelin fragments: tryptamine binding to lipid fractions.

To investigate the nature of the tryptamine binding components that originated from myelin butanol extracts (i.e., myelin proteolipids), the lipid mixtures obtained from these extracts were further fractionated by silicic acid column chromatography, and binding assays of 14C-tryptamine to those fractions were carried out by Sephadex LH20 column chromatography. Among several lipid fractions, only the F-C fraction retained the tryptamine binding properties of the original myelin butanol extracts, i.e., binding capacity, chromatographic profile and interaction with indoleamine analogues and other neurotransmitters. Since the quantitative TLC analysis indicated that this fraction contained a considerable amount of phosphatidylserine (PS) and phosphatidylinositol (PI), recombination experiments with these two acidic lipids were planned. The recombination system with PI did not show a tryptamine binding capacity, while the PS fraction possessed a tryptamine binding capacity similar to that of the myelin butanol extracts. However, displacement studies revealed that the recombinant fraction with PS alone did not display the complete regeneration of the specificity which had been observed in the myelin extracts. All these observations infer that the tryptamine binding components from myelin proteolipids are lipid in nature, and its binding entity is mainly PS. However, some specifically organized constitution with PS and other lipid molecule(s) may be necessary to regenerate the original tryptamine binding properties.

Animals↗
PubMed1983

Aortocolic fistula: a rare cause of profuse rectal bleeding.

A 62-year-old man with multiple myeloma survived for 19 months following massive hemorrhage from an aortocolic fistula secondary to an aortoiliac aneurysm that was adherent to the sigmoid colon. The literature indicates that early death from multisystem failure is to be expected and that sepsis is an inevitable consequence of aortocolic fistula. However, in this case the patient did not die despite multisystem complications and his eventual death was unrelated to sepsis or graft complications. Reasons for the unexpected outcome are suggested. No survivors have been reported in the literature.

Aged↗
PubMed1982

Purification and properties of protein methylase II from wheat germ.

Protein methylase II (S-adenosylmethionine: protein-carboxyl O-methyltransferase, EC 2.1.1.24) was purified from wheat germ approximately 1200-fold with a yield of 4.6% by employing gel filtration. The enzyme, using S-adenosyl-L-methionine, methyl-esterifies the free carboxyl group of protein. Since the enzymatic product was unstable and hydrolyzed non-enzymatically to yield methanol, methanol was identified from the hydrolysate by the formation of the methyl ester of 3.5-dinitrobenzoate. The pH optimum for the wheat germ enzyme was 7.0 in contrast to the 6.0 for the methylase II of calf brain. The wheat germ enzyme had a molecular weight of 41 000 compared to 25 000 for the corresponding rat erythrocyte enzyme [S. Kim (1975) Arch. Biochem. Biophys. 161, 652-657]. The enzyme also differed with the mammalian enzyme in protein substrate preference: the mammalian enzyme showed equal preference to histone and immunoglobulin G while the wheat germ enzyme transferred a methyl group 4.5 times more to histone than to immunoglobulin G. The Km values for histone and S-adenosyl-L-methionine were 0.2 mM and 5 microM. S-Adenosyl-L-homocysteine and its analogues, sinefungin and A9145C, were competitive inhibitors with Ki values 1.5 microM, 0.4 microM and 0.1 microM, respectively. To investigate the identity of endogenous substrate(s) for protein methylase II, the crude wheat germ extract was incubated with S-adenosyl-L-[methyl-3H]methionine and the methylated proteins were analyzed by acid/urea and sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Among other methyl acceptors in the wheat germ, histone polypeptides were the major endogenous substrates.

Kinetics↗
PubMed1982

Cytochrome c specific methylase from wheat germ.

The cytochromes c of plants (e.g., wheat germ) possess two trimethyllysines, residues 72 and 86. In order to investigate the nature of these methylations, we have purified a cytochrome c specific methylase S-adenosylmethionine: protein(lysine) N-methyltransferase (protein methylase III) from wheat germ 135-fold. The in vitro site of methylation by both the purified enzyme and crude wheat germ extract toward various forms of horse heart cytochrome c was localized by two dimensional peptide mapping, Aminex A-5 column peptide analysis, and CNBr cleavage analysis to be the residue 72 lysine. However, no additional sites, in particular residue 86, were seen to be methylated. Although the enzyme is highly specific toward cytochrome c as an in vitro protein substrate, avian cytochromes c are seen to be much better substrates than those from mammalian sources. The enzyme possesses an extremely low Km for apocytochrome c (1.21 microM), suggesting that methylation may occur before heme attachment in vivo. Various S-adenosyl-L-homocysteine analogues were tested for their inhibitor capability toward the enzyme; it was observed that only the D and L forms of S-adenosylhomocysteine are inhibitors while analogues modified in the adenine or homocysteine moieties do not possess inhibitory capability. Results from the Aminex A-5 column chromatography of horse heart cytochrome c chymotryptic digest showed the N epsilon-methyl-, N epsilon-dimethyl-m and N epsilon-trimethyllysine forms of the residue 68-74 peptide to elute earlier than the unmethylated form. This results suggest that the methylated peptides are less basic than the unmethylated form.

Cytochrome c Group↗