Search PubMed⌕ Search

Biomedical subjects

C H Kim

Publications and source records attributed to C H Kim.

At least 325 records · Page 18Linked to original sources
PubMed1994

In vivo replicative status and envelope heterogeneity of equine infectious anemia virus in an inapparent carrier.

The distribution and replicative status of equine infectious anemia virus (EIAV) DNA in the tissues of a well-characterized inapparent carrier horse were established by using the PCR technique. The EIAV pol region could be amplified in all of the tissues tested, including the cerebellum and periventricular tissue, at concentrations approximately 10(5)-fold less than in the same tissue from an acutely infected horse. Further analysis of the EIAV genome, with primer pairs diagnostic for sequential stages of reverse transcription, suggests that EIAV DNA in the brain, liver, and lymph nodes was incompletely synthesized. The products of reverse transcription were found to diminish progressively during first-strand synthesis, while products indicative of second-strand synthesis were observed only in kidney and spleen DNA samples. Sequences specific for different regions of the envelope could not be amplified from any of the tissues of the inapparent carrier, suggesting that the envelope is highly variable and may be subject to extensive drift. Together, the data suggest that low levels of EIAV replication persist without causing clinical disease in an inapparent carrier.

Animals↗
PubMed1994

Isoform-specific regulation of myocardial Na,K-ATPase alpha-subunit in congestive heart failure. Role of norepinephrine.

BACKGROUND: Myocardial ouabain-binding sites and Na,K-ATPase activity are reduced in congestive heart failure (CHF), but the mechanisms by which CHF reduces the Na,K-ATPase remain unknown. We proposed to investigate whether the changes are accompanied by isoform-specific reductions of the Na,K-ATPase alpha-subunit proteins in CHF and whether similar changes could be produced by exogenous norepinephrine administration. METHODS AND RESULTS: CHF was induced in dogs by rapid ventricular pacing at a rate of 225 beats per minute for 8 weeks (protocol 1). A second group of dogs were paced at 100 beats per minute and served as controls. In protocol 2, norepinephrine was infused in normal dogs using a subcutaneous osmotic minipump for 8 weeks. The control dogs received normal saline through the pump. Animals were studied after 8 weeks of pacing or norepinephrine infusion. After the baseline hemodynamics and interstitial norepinephrine concentration had been obtained, the hearts were removed for measuring [3H]ouabain-binding sites and Na,K-ATPase alpha-subunit proteins using isoform-specific monoclonal antibodies. RESULTS: Myocardial [3H]ouabain-binding sites were reduced in dogs with CHF and chronic norepinephrine infusion. The Western blot analysis showed that adult canine hearts possess both alpha 1 and alpha 3 isoforms of the Na,K-ATPase alpha-subunit but not the alpha 2 isoform protein. CHF and NE infusion had no effect on the Na,K-ATPase alpha 1-subunit protein but did reduce the alpha 3 isoform protein significantly. In addition, there was a significant inverse correlation between the amount of myocardial alpha 3 isoform protein and interstitial norepinephrine content in the dogs. In contrast, the specific activity of the sarcolemmal marker 5'-nucleotidase did not differ among the groups of animals. CONCLUSIONS: The reduction of myocardial Na,K-ATPase in CHF is limited to the alpha 3 isoform. Furthermore, because similar changes in myocardial ouabain-binding sites and Na,K-ATPase alpha 3 isoform were produced by chronic norepinephrine infusion, the decrease in the Na,K-ATPase in CHF is most likely mediated via excess sympathetic stimulation.

Animals↗
PubMed1994

Atrial natriuretic peptide and C-type natriuretic peptide in spontaneously hypertensive rats and their vasorelaxing actions in vitro.

The present study determined circulating concentrations of atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) in Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) and also investigated the vasorelaxing action of ANP and CNP on isolated contracted aorta. We also defined the vasorelaxing action of a novel and newly synthesized 27-amino acid chimera of ANP and CNP termed vasonatrin peptide (VNP), which we compared with ANP and CNP in WKY rats and SHR. Plasma and urinary cyclic GMP and sodium excretion were also investigated. Plasma ANP was increased in SHR in contrast to no change in circulating CNP. Plasma and urinary cyclic GMP and sodium excretion were no different between WKY rats and SHR. In WKY rats maximal relaxations to VNP in aortic rings without endothelium were greater than those to ANP and CNP. In SHR aortic rings the potency of VNP relaxation was preserved, the actions of ANP were enhanced, and the actions of CNP were markedly impaired. In association with these vasorelaxing actions, these data suggest that (1) circulating CNP is not different in SHR and WKY rats, but the aortic relaxing action of CNP is markedly impaired in SHR; (2) endogenous plasma ANP is significantly increased in SHR without associated increases in plasma or urinary cyclic GMP; (3) there is an increase in aortic relaxation to exogenous ANP in SHR; and (4) VNP has a potent endothelium-independent aortic relaxing action in both WKY rats and SHR.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Metal affinity engineering of proinsulin carrying genetically attached (His)10-X-Met affinity tail and removal of the tag by cyanogen bromide.

An E. coli expression clone coding for human proinsulin, which was fused to NH2-terminal beta-galactosidase, was engineered for the separation from host proteins by introducing peptide devices, and for the sequential removal of the fused polypeptide by cyanogen bromide in front of the NH2 terminal residue (methionine) of the human proinsulin gene. Short synthetic genes encoding oligopeptide residues including (Glu)n, (His)n, (Trp)n, and (Ser)n (n = 10 or 11), which have certain characteristic physical properties such as metal-affinity, polarity, hydrophobicity, and hydrophilicity, respectively, were inserted at the junction region of the gene fusion. Interestingly, it was found that among the oligopeptides, the oligohistidine residue as an affinity-tag has greatly facilitated the procedures for FPI purification, particularly in the manner of selective metal-affinity precipitation. The chelating peptide covering the NH2-terminal beta-galactosidase portion could then be removed simply after purification to generate a protein with the natural amino acid sequence of proinsulin by cyanogen bromide.

Affinity Labels↗
PubMed1994

Antiarrhythmic agents in older patients. Current state of knowledge.

The treatment of ventricular arrhythmias in the elderly population is a challenging problem. Elderly patients are more predisposed to arrhythmias, are less responsive to antiarrhythmic agents and are more susceptible to the adverse effects of antiarrhythmic agents. Results from recent trial have altered the general approach to management of ventricular arrhythmias. The results of the Cardiac Arrhythmia Suppression Trials (CAST I and II) exemplified the disappointing results from numerous other studies, revealing the overall lack of efficacy of class I agents in reducing mortality in patients with coronary artery disease and asymptomatic premature ventricular complexes (PVCs). The results of CAST I and II also demonstrated the higher likelihood of older patients developing ventricular arrhythmias and toxicity to antiarrhythmic agents. Combined results of these studies have discouraged empirical antiarrhythmic therapy, especially in older patients with asymptomatic PVCs. In contrast, secondary prevention trials with beta-blockers in post-myocardial infarction patients have shown definitive survival benefit and reduction in ventricular arrhythmias, especially in the older patient population. Smaller trials with amiodarone have also shown survival benefit in post-myocardial infarction patients with or without PVCs. Management of ventricular tachycardia and fibrillation has become less empirical and more systematic with use of electrophysiologically guided and/or Holter monitor-guided therapy. Sotalol and amiodarone are especially effective agents. The efficacy of implantable cardioverter/defibrillators are also being compared with medical therapy systematically in multicentre trials. In general, empirical antiarrhythmic therapy is discouraged especially in the treatment of asymptomatic PVCs and should be reserved for systematic use in life-threatening arrhythmias.

Aged↗
PubMed1994

A case of nephrotic syndrome associated with protein S deficiency and cerebral thrombosis.

Protein S is found in two forms in plasma; as free and functionally active protein S, and complexed to C4b-binding protein. Patients with nephrotic syndrome are at risk for arterial and venous thrombosis at various localizations, and acquired protein S deficiency due to the selective urinary loss of the free form may be a risk factor for the development of thromboembolic complications. We report a case of cerebral arterial thrombosis associated with decreased level of free protein S antigen (44%) in a 39-year-old female patient with nephrotic syndrome.

Adult↗
PubMed1994

[Intestinal parasite and Clonorchis sinensis infection among the inhabitants in the upper stream of Taechong Dam, Kumgang (River)].

The prevalence of intestinal parasites and Clonorchis sinensis infection was observed among inhabitants in the upper stream of Kumgang (River) from January to October 1991. A total of 743 fecal specimens was examined by cellophane thick smear and formalin-ether concentration technique. The parasite positive rate including helminth eggs and protozoan cysts was 40.8%, the positive rates for every species were: Clonorchis sinensis 30.8%, Metagonimus spp. 14.5%, Fasciola spp. 0.7%, Taenia spp. 1.5%, Ascaris lumbricoides 0.4%, Enterobius vermicularis 0.1%, Hookworm 0.1%, Trichuris trichiura 1.6%, Entamoeba coli 0.7%, E. histolytica 0.3%, Endolimax nana 0.3%, Giardia lamblia 0.3% and Iodamoeba buetschlii 0.1%, respectively. The cumulative positive rate in Okchon-gun showed 51.1%, in the Kumsan-gun 50.8% and in the Muju-gun 28.6%. Through this survey, it was concluded that the soil transmitted intestinal parasites including helminthseggs and protozoan cysts have been decreased remarkably among the inhabitants along the upper stream of Taechong Dam, Kum-gang (River), on the other side, Clonorchis sinensis, Metagonimus spp. and Taenia spp. are still morderate prevalent.

Adolescent↗
PubMed1993

Domain structure and multiplicity of raw-starch-digesting amylase from Bacillus circulans: extensive proteolysis with proteinase K, endopeptidase Glu-C and thermolysin.

Raw-starch-digesting amylase (RSDA) is a key extracellular enzyme of mesophilic Bacillus circulans F-2 which uses raw starch granules as a carbon source. Previous work has demonstrated that there are two domains of the enzyme during digestion with subtilisin, and that RSDA activity is selectively inactivated by limited proteolysis with subtilisin, which cleaves the enzyme between these hydrolytic and adsorption domains (Kim, C.-H., Kwon, S.-T., Taniguchi, H. and Lee, D.-S. (1992) Biochim. Biophys. Acta 1122, 243-250). In this work we show that a similar phenomenon is observed during limited proteinase K, thermolysin and endopeptidase Glu-C proteolysis of the enzyme. Fragments resulting from proteolysis were characterized by immunoblotting with anti-RSDA. The proteolytic patterns resulting from proteinase K and subtilisin were the same, producing 63 and 30-kDa fragments. Similar patterns were obtained with endopeptidase Glu-C or thermolysin. All proteolytic digests contained a common, major 63-kDa fragment. Inactivation of RSDA activity results from splitting off the C-terminal domain. Hence, it seems probable that the proteinase-sensitive locus is in a hinge region susceptible to cleavage. Extracellular enzymes immunoreactive towards anti-RSDA were detected through whole bacterial cultivation. 93, 75, 63, 55, 38 and 31-kDa proteins were immunologically identical to RSDA. Of these, the 75-kDa and 63-kDa proteins correspond to the major products of proteolysis with Glu-C and thermolysin. These results suggest that enzyme heterogeneity of the raw-starch hydrolysis system might arise from the endogenous proteolytic activity of the bacterium.

Amylases↗
PubMed1993

Delivery of radionuclides to pretargeted monoclonal antibodies using dihydrofolate reductase and methotrexate in an affinity system.

A novel affinity system for a two-phase delivery of radionuclides to tumor cells has been developed. In the first phase, a nontoxic bivalent monoclonal antibody conjugated to an enzyme is targeted to the tumor cells. In the second phase, a radionuclide-derivatized enzyme inhibitor, specific for the enzyme conjugated to the antibody, is administered. The model system selected for this study is the recombinant human enzyme dihydrofolate reductase (rhDHFR) and its high-affinity competitive inhibitor methotrexate (MTX). MTX was labeled with a radionuclide by covalent attachment of diethylenetriaminepentaacetic acid (DTPA) complexed with 111In. Using the gamma-carboxyl residue of MTX for the attachment of DTPA, binding of the inhibitor to rhDHFR was not affected. The inhibitory activities of nonderivatized MTX and DTPA-MTX were indistinguishable. Human K562 erythroleukemia cells were used to evaluate under in vitro conditions the DHFR-MTX affinity system for the delivery of 111In-labeled DTPA-MTX to pretargeted alpha-transferrin receptor antibody-rhDHFR conjugates (alpha-TFR-DHFR). The data demonstrate that the delivery of 111In is dose dependent and highly specific. Under saturating conditions, binding of 111In-DTPA-MTX to alpha-TFR-DHFR-treated cells was 14-fold higher than to cells treated with nonconjugated alpha-TFR antibody. Further experiments indicated that the low level of nonspecific binding of 111In-DTPA-MTX was comparable to that of 111In-DTPA, known for its complete extracellular distribution and rapid clearance through the kidneys. Based on the data of this study, antibody-conjugated rhDHFR and radionuclide-labeled DTPA-MTX complexes provide components for an alternative radioimmunotherapeutic approach that can be expected to result in improved tumor tissue ratios of both the targeting moiety and the radionuclide-labeled derivative as compared to current approaches.

Antibodies, Monoclonal↗
PubMed1993

NIGMS human/rodent somatic cell hybrid mapping panels 1 and 2.

The NIGMS Human Genetic Mutant Cell Repository is currently distributing two well-characterized human/rodent somatic cell hybrid mapping panels. Mapping Panel 1 consists of DNA isolated from 18 hybrid cell cultures retaining from 1 to 19 human chromosomes. Mapping Panel 2 contains DNA from hybrids retaining 1 or 2 human chromosomes. All but 2 of the hybrids retain a single intact human chromosome. Mapping Panel 2 is also available as cell cultures. These resources should prove valuable to the Human Genome Project initiative. This article describes the sources of the hybrid cell cultures and the procedures utilized to prepare and characterize the panels.

Animals↗
PubMed1993

Relation of pulmonary venous flow to mean left atrial pressure in mitral stenosis with sinus rhythm.

To determine whether pulmonary venous flow measured by transesophageal Doppler echocardiography can be used to estimate mean left atrial pressure (LAP), we prospectively studied 12 consecutive patients with sinus rhythm undergoing percutaneous mitral balloon commissurotomy for their severe mitral stenosis (mitral valve area < 1.5 cm2). We correlated Doppler variables of pulmonary venous flow and the mean LAP measured by left atrial catheterization. Among the variables of the pulmonary venous flow, the systolic fraction (i.e., the systolic velocity-time integral expressed as a fraction of the sum of systolic and early diastolic velocity-time integral) correlated significantly with mean LAP (r = -0.71, p < 0.05) and mitral valve area (r = 0.64, p < 0.05). Peak velocity and velocity-time integral in systole also significantly correlated with mean LAP (r = -0.66, r = -0.67 respectively, p < 0.05). We conclude that the more severe the degree of mitral stenosis in patients with sinus rhythm, the less systolic pulmonary venous flow in severe mitral stenosis.

Adult↗
PubMed1993

Nonspecific motor disorder of the esophagus: a real disorder or a manometric curiosity?

BACKGROUND: Nonspecific esophageal motility disorder (NEMD) has become a catchall term to describe abnormal esophageal manometric findings that do not meet strict criteria for established esophageal motility disorders. The aim of this study was to determine whether NEMD is a real esophageal motility disorder characterized by impairment of its motor function or simply a manometric disturbance with no clinical consequences. METHODS: Esophageal transit of liquid and semisolids was studied using radioscintigraphic techniques in 10 symptomatic patients with manometrically diagnosed NEMD, 26 healthy control subjects, and 40 disease control subjects. The disease controls included 24 patients with achalasia, 9 with scleroderma, and 7 with diffuse esophageal spasm. RESULTS: Patients with NEMD had no impairment of liquid emptying compared with healthy controls. Liquid emptying was markedly delayed in patients with achalasia and scleroderma. However, semisolid emptying was markedly delayed in patients with NEMD compared with healthy controls (P < 0.001), and the extent of its delayed emptying was similar to that seen in patients with achalasia, scleroderma, and diffuse esophageal spasm. CONCLUSIONS: NEMD is not a manometric curiosity but a disorder characterized by selective impairment of semisolid emptying.

Adult↗
PubMed1993

Effect of menstrual cycle on esophageal emptying of liquid and solid boluses.

The effect of the menstrual cycle on esophageal emptying is unknown. We investigated the influence of the menstrual cycle on esophageal transit of liquid and solid boluses in 30 healthy, normally menstruating women who were 20 to 46 years of age. Each subject was studied during the follicular (days 8 through 10) and the luteal (days 18 through 20) phase of the menstrual cycle. Subjects swallowed a 10-ml bolus of water and two solid boluses, each radiolabeled with 100 microCi of 99mTc sulfur colloid. Esophageal scintigraphy was used to assess esophageal emptying of the liquid and solid boluses. Our results showed no significant differences in esophageal transit of either liquid or solid material between follicular and luteal phases. We conclude that esophageal emptying is unaffected by the phases of the menstrual cycle.

Adult↗
PubMed1993

Achalasia: prospective evaluation of relationship between lower esophageal sphincter pressure, esophageal transit, and esophageal diameter and symptoms in response to pneumatic dilation.

The aims of this study were to investigate a group of patients with achalasia prospectively to determine (1) the relationship between changes in symptoms and esophageal motor function in response to pneumatic dilation and (2) the effects of the balloon size as well as the frequency and duration of inflation on the outcome of treatment. Fourteen patients with achalasia who were symptomatic for a median duration of 27 months participated in the study. The patients were randomized to one combination of the following pneumatic dilation conditions: a 30- or 35-mm balloon dilator, one or two balloon inflations, and 20, 40, or 60 seconds per balloon inflation. A comprehensive assessment of their symptoms and esophageal motility, transit, and diameter were performed before and 3 months after pneumatic dilation. Pneumatic dilation provided significant relief of dysphagia (P < 0.01), but other symptoms (heartburn, regurgitation, and chest pain) remained unchanged. Pneumatic dilation also caused a significant decrease in lower esophageal sphincter pressure and esophageal diameter and improved esophageal emptying of a solid bolus. Nevertheless, no significant association was detected between changes in the symptom score for dysphagia and changes in objective response measures as a result of pneumatic dilation. Changes in the symptom score for dysphagia or objective responses were similar regardless of the size of the dilator used or the frequency and duration of the balloon inflations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Discriminate value of esophageal symptoms: a study of the initial clinical findings in 499 patients with dysphagia of various causes.

The aim of this study was to determine whether the characteristics of esophageal symptoms may be of diagnostic utility in distinguishing dysphagia of various causes. Included in the study were a total of 499 patients with three types of dysphagia: 234 with dysphagia related to an obstructive lesion in the esophagus, 162 with dysphagia related to disturbed esophageal motility, and 103 with dysphagia who had no demonstrable structural or motor abnormalities in the esophagus. In the first part of the study, the initial esophageal symptoms of 402 patients with dysphagia were retrospectively reviewed and analyzed with use of a stepwise logistic regression. This analysis led to development of models that could distinguish among the various diagnostic groups of dysphagia. In the second segment of the study, these models were validated in a prospective assessment that involved 97 patients with dysphagia. In the third part of the study, the models were further refined by using data from all 499 patients from the first two parts. The results presented herein suggest that a subset of selected esophageal symptoms can distinguish among diagnostically identified groups of dysphagia. The discriminate models presented rely on a few easily determined clinical variables and hence are practical and potentially useful in the evaluation of undifferentiated dysphagia.

Adult↗
PubMed1993

Vasonatrin peptide: a unique synthetic natriuretic and vasorelaxing peptide.

This study reports the cardiovascular and renal actions of a novel and newly synthesized 27-amino acid peptide termed vasonatrin peptide (VNP). VNP is a chimera of atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP). This synthetic peptide possesses the 22-amino acid structure of CNP, which is a cardiovascular selective peptide of endothelial origin and is structurally related to ANP. VNP also possesses the five-amino acid COOH terminus of ANP. The current study demonstrates both in vitro and in vivo that VNP possesses the venodilating actions of CNP, the natriuretic actions of ANP, and unique arterial vasodilating actions not associated with either ANP or CNP.

Amino Acid Sequence↗
PubMed1993

Purification and biochemical properties of an alkaline pullulanase from alkalophilic Bacillus sp. S-1.

A novel extracellular pullulanase (PUL-E, pullulan 6-glucanohydrolase, EC 3.2.1.41) has been purified from the alkalophilic Bacillus sp. S-1. The purified enzyme had a molecular mass of about 140 kDa on denaturated and natural conditions. The pI was 5.5. The pullulanase, when resolved by SDS-PAGE, was negative for Schiff staining, suggesting that the enzyme is not a glycoprotein. The N-terminal amino acid sequence of the enzyme was Phe-Leu-Asn-Met-Ser-(Trp-Phe). The enzyme displayed a temperature optimum of around 60 degrees C and a pH optimum of around pH 9.0. The enzyme was stable to incubation from pH 4.0 to pH 11.0 at 4 degrees C for 24 h. The presence of pullulan protected the enzyme from heat inactivation, the extent depending upon the substrate concentration. The activity of the enzyme was stimulated by Mn2+ ions. Ca2+ ions and EDTA did not inhibit the enzyme activity. The enzyme hydrolyzed the alpha-1,6-linkages of amylopectin, glycogens, alpha,beta-limited dextrin, and pullulan. The enzyme had an apparent Km of 7.92 mg/ml for pullulan, a Km of 1.63 mg/ml for amylopectin, and a Km of 3.1 mg/ml for alpha,beta-limited dextrin, when measured at pH 9.0 and 50 degrees C. The enzyme caused the complete hydrolysis of pullulan to maltotriose. The activity was not inhibited by alpha, beta, or gamma-cyclodextrins. The western blotting analysis with mouse anti-serum against PUL-E showed that PUL-E is produced as a single enzyme form during bacterial cultivation.

Amino Acid Sequence↗