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Biomedical subjects

S Kim

Publications and source records attributed to S Kim.

At least 1,351 records · Page 75Linked to original sources
PubMed1985

Preparation of multilamellar vesicles of defined size-distribution by solvent-spherule evaporation.

A novel method of preparing multilamellar vesicles is described. The process involves dispersing in aqueous solutions small spherules of volatile hydrophobic solvents in which amphipathic lipids are dissolved. The lipids form vesicles when the solvents are evaporated in the proper manner. The resulting vesicles have been characterized morphologically with microscopy and electron microscopy. The method yields multilamellar vesicles with a defined size distribution which can be adjusted by varying the duration of mechanical agitation of the spherules and by varying the concentration of amphipathic lipids in the solvents. This is the first fundamentally new method of multilamellar vesicle preparation since Bangham's report in 1965 (Bangham, A.D., Standish, M.M. and Watkins, J.C. (1965) J. Mol. Biol. 13, 238-252).

Liposomes↗
PubMed1985

Immunohistochemical localization of protein-O-carboxylmethyltransferase in rat brain neurons.

The distribution of the enzyme protein-O-carboxylmethyltransferase (EC 2.1.1.24) has been investigated in the rat brain using both immunohistochemical and biochemical techniques. The enzyme, which carboxylmethylates free aspartic and glutamic acid residues of protein substrates, was localized in neurons, but not other cell types throughout the brain. The highest immunoreactivity was detected throughout the cortex, followed by the hippocampus, the corpus striatum, the thalamus and the amygdala. Immunoreactive cells were detected in other brain regions but were not as prominent as those regions listed above. The distribution of immunoreactivity in the hippocampus was most striking, with considerable labelling of the pyramidal and granule cells in all regions. Numerous pyramidal cells were labelled in the cerebral cortex, with some ascending processes exhibiting immunoreactivity. The corpus striatum was uniformly labelled, suggesting that the enzyme was not localized to any specific neurotransmitter system. The antisera employed in this study was generated against purified bovine brain protein-O-carboxylmethyltransferase and Western immunoblot analysis showed cross reactivity against both rat brain and human erythrocyte forms of the enzyme. Enzyme activity and methyl acceptor protein capacity were examined in 1.5 mm coronal sections of rat brain. The regions with highest enzyme activities were found in cross-sections containing cortex and corpus striatum or cortex and hippocampus. The lowest enzyme activities were noted in slices of brainstem and cerebellum, areas exhibiting low amounts of immunoreactive protein-O-carboxylmethyltransferase. Methyl acceptor protein capacity was highest in slices of cortex and corpus striatum, cortex and hippocampus and was lowest in slices of brainstem and cerebellum. These results demonstrate that protein-O-carboxylmethyltransferase has an unique neuronal pattern of distribution in the rodent central nervous system, and suggest that the carboxylmethylation of proteins may be of functional significance in these neurons.

Animals↗
PubMed1985

Effects of infection with Eimeria tenella upon Salmonella typhimurium infection in the gnotobiotic chicks. Scanning electron microscopic study.

The gnotobiotic chicks infected with Eimeria tenella received an oral inoculation of Salmonella typhimurium 4 or 8 days after E. tenella infection. Chicks were necropsied one day after the salmonella infection. In the experiments 1 and 2, there were two groups; birds infected with S. typhimurium alone and birds infected with a combination of E. tenella and S. typhimurium. The number of S. typhimurium in the cecal contents was significantly greater in the concurrent infections than S. typhimurium infection alone. The S. typhimurium counts in the cecal wall of gnotobiotic chickens killed 5 days after E. tenella infection were significantly greater than those of chickens infected with S. typhimurium alone. In the experiment 3, the scanning electron microscopic study was made on damage of cecal mucosa. There were four groups; uninfected birds as control, birds infected with E. tenella, birds infected with S. typhimurium and birds infected with a combination of E. tenella and S. typhimurium. No damage was observed on the cecal mucosa of both the control and the S. typhimurium infection alone. The concurrent infections caused greater damage on the cecal mucosa than did the E. tenella infection alone.

Animals↗
PubMed1985

Influence of preoperative parenteral alimentation on postoperative growth in adolescent Crohn's disease.

The postoperative growth rates achieved in eight early pubertal adolescent males with Crohn's disease undergoing surgery for obstructive complications is reported as a function of the use of 1 month's preoperative central venous alimentation. All patients had ileal strictures with ileocolitis, bone ages less than 13, Tanner stages 1 or 2, and growth velocities below the 3rd percentile for age. During a 3-year follow-up, those receiving preoperative venous alimentation demonstrated greater oral caloric intake (significant for 1 year) and greater postoperative growth velocity (significant for 2 years) in comparison to those patients who did not receive preoperative venous alimentation. There was no significant difference between the two groups of patients in postoperative weight gain, sexual development, and 3-year disease control.

Adolescent↗
PubMed1985

Chromium-induced pulmonary cancer. Report of a case and a review of the literature.

A 57-year-old man, whose occupational history was that of a chromate worker for about 35 years, suffered nasal perforation during and died due to pulmonary cancer. In the autopsy materials, the concentration of chromium in the lung tissues was very high, being about 90 times the amount found in normal lungs. The chromium particles in the lung tissues could not be detected by analytical electron microscope, but they could be found in the anthoracotic lesions of the lungs by means of an X-ray microanalyser. The present case was judged to be a case of chromium-induced pulmonary cancer since all the pathologic data obtained were similar to those found in similar cases reported in the literature.

Adenocarcinoma↗
PubMed1985

Lymphatic transport of sodium cefoxitin in the presence of sodium 5-methoxysalicylate after injection into rat rectal connective tissue, femoral muscle and femoral vein.

Lymphatic uptake of sodium cefoxitin after injection into rectal connective tissue was greater than after injection into the femoral muscle of rats. Coadministration with sodium 5-methoxysalicylate enhanced lymphatic drug uptake at both sites. This enhancement may be an indirect result of 5-methoxysalicylate's suppression of vascular permeation of the cefoxitin. An adjuvant-induced increase in lymphatic fluid flow may also be partially involved in the enhancement of cefoxitin lymphatic transport.

Animals↗
PubMed1985

Regulation of pulpal blood flow.

The regulation of blood flow of the dental pulp was investigated in dogs and rats anesthetized with sodium pentobarbital. Pulpal blood flow was altered by variations of local and systemic hemodynamics. Variation in pulpal hemodynamics was attained by means of close intra-arterial injections of adrenergic agonists (NE and ISO) and their antagonists (PBZ and Propranolol). Variation in systemic hemodynamics was achieved by hemodilution, hemo-concentration, hemorrhage, and SNP infusion. Macrocirculatory blood flow (ml/min/100 g) in the dental pulp was measured with both the 133Xe washout and the 15-microns radioisotope-labeled microsphere injection methods on the canine teeth of dogs, to provide a comparison of the two methods in the same tooth. Microcirculatory studies were conducted in the rat incisor tooth with microscopic determination of the vascular pattern, RBC velocity, and intravascular volumetric flow distribution. Pulpal resistance vessels have alpha- and beta-adrenergic receptors. Activation of alpha-receptors by intra-arterial injection of NE caused both a reduction in macrocirculatory Qp in dogs and decreases in arteriolar and venular diameters and intravascular volumetric flow (Qi) in rats. These responses were blocked by the alpha-antagonist PBZ. Activation of beta-receptors by intra-arterial injection of ISO caused a paradoxical reduction of Qp in dogs. In rats, ISO caused a transient increase in arteriolar Qi followed by a flow reduction; arteriolar dilation was accompanied by venular constriction. These macrocirculatory and microcirculatory responses to ISO were blocked by the alpha-antagonist propranolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic Fibers↗
PubMed1985

Effects of experimental hypotension on hemodynamics and renin secretion rate.

The effects of hypotension on systemic and renal hemodynamics, plasma renin activity (PRA), and renin secretion rate (RSR) were determined in dogs anesthetized with sodium pentobarbital plus chloralose. Renal blood flow (RBF) was determined with microspheres (15 micron) and with an electromagnetic flowmeter connected to an extra-corporeal circuit from the femoral artery to the renal artery. Hypotension was induced by nitroprusside infusion, which decreased peripheral resistance, and by hemorrhage, which reduced cardiac output. RSR increased in both forms of hypotension, but the increase following hemorrhage was greater than that after nitroprusside. Thus, when the mean arterial pressure (MAP) was reduced to 75 mmHg, RSR increased from 470 +/- 26 units/min to 990 +/- 12 units/min with nitroprusside and from 415 +/- 13 units/min to 1,509 +/- 21 units/min following hemorrhage. At MAP of 50 mmHg, RSR increased to 1,541 +/- 64 units/min with nitroprusside and to 2,254 +/- 98 units/min following hemorrhage. Nitroprusside increased renin secretion not only by an increase in sympathetic beta adrenergic activity through the baroreceptor reflex, but also by its direct vasolidatory effect in the renal circulation. In hemorrhagic hypotension, the increase in renin secretion was accompanied by renal vasoconstriction. The greater increase in RSR following hemorrhage than after nitroprusside at given levels of hypotension may be explained by a stronger beta adrenergic activation, the activation of prostaglandin and kallikrein systems, a lower microvascular pressure level, and/or smaller pulse pressure and lower sodium load in the macula densa. The comparison of renin secretion at the same degree of hypotension induced by different hemodynamic alterations serves to elucidate the mechanisms of renin secretion.

Animals↗
PubMed1984

Studies on myelin basic protein-specific protein methylase I in various dysmyelinating mutant mice.

Jimpy mice are dysmyelinating mutants characterized by producing near normal levels of myelin basic protein (MBP) in the brain but failing to incorporate these proteins into the myelin sheath. In this study, the activity of MBP-specific protein-arginine N-methyltransferase (protein methylase I) was studied in the brains of normal and jimpy mice of different ages. The enzyme activity varied little with age in normal mice but in 18 and 21 days-old homozygous jimpy mice the activity was reduced by 50% and 75% respectively from the level of their normal littermates. Interestingly, however, heterozygous jimpy mice who are phenotypically normal and quaking mice (a similar dysmyelinating mutant) showed unaltered enzyme levels.

Age Factors↗
PubMed1984

Differential membrane protein carboxyl-methylation of intact human erythrocytes by exogenous methyl donors.

The patterns of membrane protein carboxyl-methylation by protein methylase II (S-adenosylmethionine: protein-carboxyl O-methyltransferase, EC 2.1.1.24) in intact human erythrocytes were shown to differ markedly whether the methyl donor, S-adenosyl-L-[methyl-3H]methionine, was supplied exogenously or formed intracellularly via exogenously added L-[methyl-3H]methionine. The differences include the following. (1) The methylation of cytoskeletal components (band 2.1 and 4.1) occurs only in the case of the L-[methyl-3H]methionine-labelled cells. (2) The methionine-mediated methylation was much less sensitive to S-adenosyl-L-homocysteine inhibition than the adenosylmethionine-mediated methylation (22% versus 95% inhibition at 10 microM). (3) The membrane protein methylation mediated by exogenous adenosylmethionine and methionine differed markedly in their alkali labilities; at pH 6.0, 30% of the adenosylmethionine-mediated protein methyl esters were hydrolysed after 30 min (37 degrees C) while the methionine-mediated esters were stable. At pH 7.4, the respective labilities were 60% and 30% for the 30 min incubation. To explain these results, a possible involvement of cytoskeletal structure associated with the intact erythrocyte is discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1984

Determination of the partition coefficient of 133xenon between oral tissues and blood in the dog.

Ostwald solubility coefficients for 133Xe in plasma (Sp), red blood cells (Sc), and selected oral tissue homogenates (St) obtained from the dog were determined at 4, 20, 27 and 37 degrees C by counting the 133Xe activity of the air phase and the sample (liquid, red cells or tissue) in the same tube following equilibration. The partition coefficient for xenon (lambda, in ml/g) between red cells and plasma (lambda cp) and that between tissues and plasma (lambda tp) were calculated from the measured Sp, Sc and St. The tissue-blood partition coefficients (lambda tb) of oral tissues for 133Xe were then calculated using lambda cp, lambda tp and the haematocrit value. The calculated values of lambda tb at 37 degrees C and 50 per cent haematocrit were 0.650 for the pulp, 0.674 for the tongue, 0.828 for the submandibular gland and 0.881 for the gingiva of the dog. lambda cp increased and lambda tp decreased as the temperature was reduced from 37 to 4 degrees C.

Animals↗
PubMed1984

Effect of developmental stage on arginase and urea production in the liver of rat.

Arginase activity in the liver, brain, and testis of rats was examined during the different phases of life span. When expressed as specific activity (micromoles of L-arginine hydrolyzed per minute per gram of whole homogenate protein), the enzyme activity in the brain and testis decreased markedly during the early stage of life and stayed low during the remainder of the life span. On the other hand, the arginase in the liver showed a great dependency on the developmental phase of the animal, showing two distinct peaks: one during the early phase (20 days after birth) and the other at a later time (3 months of age). This pattern of change in the hepatic arginase activity closely coincided with the pattern of the rate of urea synthesis determined with liver slices and expressed in terms of micromoles of urea formed per hour per gram of tissue slice. In contrast to the above observations, however, curves obtained by plotting the total liver arginase or urea synthetic activity vs the developmental stage of rats showed no measurable discontinuity. Further studies revealed that the observed pattern of specific activity of hepatic arginase was, in part, due to the change in the relative concentration of arginase protein in the liver.

Aging↗