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Biomedical subjects

Y Koh

Publications and source records attributed to Y Koh.

At least 55 records · Page 3Linked to original sources
PubMed1999

Value of ICAM-1 expression and soluble ICAM-1 level as a marker of activity in sarcoidosis.

BACKGROUND: The natural course of sarcoidosis is variable, but no single parameter has been generally accepted as a good marker for disease activity. Adhesion molecules are required for the migration of inflammatory cells; thus, they may be markers of activity in sarcoidosis. METHODS: In 16 patients with active sarcoidosis and 11 with inactive disease (10 were male, 17 were female; mean age [-/+ SD], 39.6+/-11.0 years; mean follow-up, 21+/-16 months), the expression of adhesion molecules on cells obtained with BAL (measured by flow cytometry) and the level of soluble intercellular adhesion molecule 1 (sICAM-1) in the serum and BAL fluid (BALF) were measured at the time of diagnosis and during the follow-up. The changes in serum sICAM-1 level and ICAM-1 expression on cells obtained with BAL were compared with the clinical course of the disease. RESULTS: In patients with active disease, the ICAM-1 on alveolar macrophage (AM) (relative linear median fluorescence intensity [RMFI], 3.21+/-1.55) and sICAM-1 levels in serum (575+/-221 ng/mL) and BALF (47.3+/-19.3 ng/mL) were higher than those for patients with inactive disease (RMFI, 1.67+/-0.66; p = 0.0034; serum, 263+/-98.5 ng/mL; p = 0.0001; BALF, 27.5+/-19.0 ng/mL; p = 0.0209). In the patients with active disease, ICAMN-1 on AM and serum sICAM-1 decreased (RMFI, 1.51+/-0.84; 284+/-118 ng/mL, respectively) after steroid therapy, but no significant change was noted in patients with inactive disease. We also found that the initial ICAM-1 on AM and serum sICAM-1 had a significant correlation with the degree of improvement in pulmonary function tests after the therapy. The disease relapsed in four patients after the discontinuation of steroids, and the serum sICAM-1 level was elevated again at the time of relapse. CONCLUSION: Our data suggest that the serum sICAM-1 level and the ICAM-1 expression on AM may be good markers of disease activity and also a predictor of outcome in sarcoidosis.

Adult↗
PubMed1999

The effect of varying inspiratory to expiratory ratio on gas exchange in partial liquid ventilation.

BACKGROUND: In partial liquid ventilation (PLV), the nondependent lung was observed to be inflated first and the dependent lung later. The inflational time difference between the lung regions can lead to maldistribution of tidal gas and inefficient gas bubbling in the slow-inflating region during PLV. In this situation, increasing the inspiratory to expiratory (I:E) ratio of the mechanical ventilator would lessen the heterogeneity of regional ventilation and improve gas exchange possibly to a greater degree than in gas ventilation (GV). DESIGN AND SETTING: Animal study at the Asan Institute for Life Sciences, Seoul, Korea Subjects: Eighteen rabbits (2.6 +/- 0.5 kg) with acute lung injury by saline solution lavage. INTERVENTIONS: Three I:E ratios were tried in GV and then in PLV. I:E ratios were changed by adjusting pause (1:2, 1:1, and 2:1; group 1) or by adjusting inspiratory flow rate (1:3, 1:1, and 2:1; group 2). MEASUREMENTS AND RESULTS: With increasing I:E ratio in all animals, PaO(2)/FIO(2) increased (80 +/- 24, 143 +/- 74, and 147 +/- 88 mm Hg; p = 0.001), and PaCO(2) decreased (74 +/- 15, 66 +/- 16, and 66 +/- 15 mm Hg; p = 0.006). The increases of PaO(2)/FIO(2) from 1:2/1:3 to 1:1 (p = 0.006) and from 1:1 to 2:1 (p = 0.036) were both greater in group 1 than in group 2. PaCO(2) decreased with increasing I:E ratio in group 1, but not in group 2. The change of PaO(2)/FIO(2) by varying the I:E ratio was 49 +/- 65% in PLV and 14 +/- 14% in GV (p = 0.003). CONCLUSIONS: Extending the I:E ratio, especially by adding pause, improved gas exchange in PLV. Oxygenation in PLV was affected by the I:E ratio to a greater degree than in GV.

Animals↗
PubMed1998

Two types of chicken 2',5'-oligoadenylate synthetase mRNA derived from alleles at a single locus.

We have isolated two types of chicken 2',5'-oligoadenylate synthetase cDNAs, A and B, which encode predicted proteins of 508 amino acids (58316 Da) and 476 amino acids (54336 Da), respectively. The region of A-protein comprising 33 amino acid residues from 385Ala to 417Cys is substituted by a single amino acid 385Tyr in B-protein. The homology between chicken and mammalian 2',5'-oligoadenylate synthetases is 49.5% over the amino-terminal 337 residues. Proteins expressed from A- and B-cDNAs in E. coli cells were both active in synthesizing 2',5'-oligoadenylate. However, the activity of B-protein was 10-15% of that of A-protein. Southern blotting hybridization indicated that the chicken synthetases are encoded by a single gene. RT-PCR and PCR analyses of RNA and DNA of chicken erythrocytes together with the sequence data of the PCR products showed that A- and B-mRNAs are derived from alleles at a single locus encoding chicken 2',5'-oligoadenylate synthetase, designated as OAS * A and OAS * B. Chickens carrying OAS * A/B produce two types of synthetase with molecular masses of 58 and 54 kDa, and those carrying OAS * A/A produce only a single type of 58 kDa.

2',5'-Oligoadenylate Synthetase↗
PubMed1998

[Mitral valve replacement for three cases of hypertrophic obstructive cardiomyopathy--surgical treatment].

Three patients with obstructive cardiomyopathy underwent surgical treatment. Mitral valve replacement was performed in all three cases and myectomy of hypertrophic septal muscle was performed in one case. The pressure gradients between the left ventricle and the aorta was less than 10 mmHg in all cases after surgery, Clinical symptoms strikingly improved in three cases. An accurate surgical treatment could be achieved by choosing either myotomy-myectomy, mitral valve replacement or both in the setting of individual condition of each patients.

Cardiomyopathy, Hypertrophic↗
PubMed1997

A case of superior vena cava syndrome caused by Klebsiella pneumoniae.

A 27 yr old man presented with productive cough, fever and manifestations of superior vena cava syndrome. He was an alcoholic but had been in good health until 3 days prior to admission. The physical examination, the chest radiograph and the results of the sputum culture were compatible with Klebsiella pneumoniae pneumonia of the right upper lobe. The superior vena cava scintigram using technetium-99m showed near total occlusion of the superior vena cava, while sputum cytology, chest computed tomography, and bronchoscopy were all negative for malignant aetiology. Antibiotic therapy brought about slow resolution of the pneumonia and also of the superior vena caval obstruction. The follow-up scintigram showed normalized venous flow of the superior vena cava. To our knowledge, this is the first case of superior vena cava syndrome developed in probable association with Klebsiella pneumoniae pneumonia.

Adult↗
PubMed1997

[Pulmonary arterial reconstruction with autologous pulmonary arterial tissue for pulmonary artery sling].

One-year and two-month-old boy with pulmonary artery sling underwent pulmonary artery reconstruction with autologous pulmonary arterial tissue. Surgical repair consisted of the transection of the left pulmonary artery at its origin with trimming a button hole and the creation of an oval hole with the same size to the left pulmonary button. An autologous pulmonary patch and the left pulmonary button were exchanged and sutured to the former partner's place. He recovered uneventfully in post-operative course. Postoperative CT revealed a well developed left pulmonary artery from 5 mm to 10 mm in diameter without any distortion or stenosis. This exchange method could allow the natural growth of the anastomotic places without narrowing or distortion.

Anastomosis, Surgical↗
PubMed1997

[Immunohistochemical study of p21 expression in gastric carcinoma].

In this study, the expression of p21 protein was investigated immunohistochemically in 152 patients with gastric cancer. Expression of p21 was detected in 64 tumors (42.1%). There were significant differences among the expression of p21, histologic type, depth of invasion, lymph node metastasis, liver metastasis, and peritoneal metastasis. The deeper the tumor invaded, the more frequent p21 expression increased. Of the 152 patients, lymph node, liver and peritoneal metastasis were found in 86, 13 and 23 patients, respectively. p21 expression was more frequently lost in tumors from patients with metastasis. In relation to prognosis, patients with p21-positive tumors had a significantly better prognosis than those with p21-negative tumors. In conclusion, this study suggested that expression of p21 has a prognostic value in gastric cancer.

Cyclin-Dependent Kinase Inhibitor p21↗
PubMed1996

Tumor necrosis factor induced acute lung leak in rats: less than with interleukin-1.

Although local tumor necrosis factor-alpha (TNF) release by alveolar macrophages has been postulated to contribute to the development of acute respiratory distress syndrome (ARDS), the effects of instilling TNF intratracheally on the development of acute lung leak are not known. Our goal was to determine the effect of intratracheally administered TNF on the development of acute lung leak in rats. We found that rats given TNF (500 ng) 5 hours previously intratracheally had increased (p < 0.05) lung lavage cytokine induced neutrophil chemoattractant (CINC) concentrations, lung lavage neutrophils, lung myeloperoxidase (MPO) activity, and lung leak compared to saline-treated control rats. However, all of the responses following TNF instillation were much lower than the responses to interleukin-1 alpha (IL-1) instillation. For example, instilling 50 ng of IL-1 caused 6.4 times the increases in lung lavage CINC concentrations, 15.5 times the increase in lung lavage neutrophils, 3.6 times the increase in lung MPO activity and 3.8 times the increase in lung leak caused by giving 500 ng of TNF intratracheally. Co-treatment with TNF-binding protein decreased both lung MPO and lung leak increases in rats given TNF intratracheally. These observations suggest that locally elevated levels of TNF may induce lung neutrophil recruitment and acute lung leak but that IL-1 is a much more potent agent than TNF in causing lung neutrophil accumulation and lung leak.

Animals↗
PubMed1996

Trial production of titanium orthodontic brackets fabricated by metal injection molding (MIM) with sintering.

Safety and esthetics are two indispensable factors to consider when fabricating orthodontic brackets. However, these factors are not easily achieved when conventional techniques (including forging and casting) are used in the mass production of titanium brackets, albeit the brackets exhibit excellent biocompatibility. In the present study, orthodontic brackets were manufactured by metal powder injection molding with sintering. Brackets with three different base designs were made and subjected to compression shear tests for evaluation of their bonding strength to enamel substrate. The shapes given to the dimple of the base were spherical, oval, and grooved. The maximum shear forces for each type were 11.1 kgf, 7.6 kgf, and 18.5 kgf, respectively. The bonding strengths of the titanium bracket were equivalent to those obtained with conventional stainless steel brackets. Moreover, uniform distribution of Vickers hardness values (average, 240 +/- 40 Hv) measured at three locations indicated that the titanium bracket was uniformly sintered. Accordingly, titanium brackets thus fabricated exhibit a potential for clinical application.

Analysis of Variance↗
PubMed1996

[Aortic valve replacement due to Libman-Sacks endocarditis combined with infectious endocarditis].

A 40-year-old female had a history of fever, arthralgia, proteinuria, and dyspnea on effort twenty years ago, and was diagnosed as SLE, renal failure, and aortic regurgitation. She also suffered from pyelonephritis and sepsis due to the infection of E. coli. Preoperative examination revealed non-active phase of SLE. Echocardiography and aortography showed massive aortic regurgitation and operation was recommended. Operative findings showed fresh vegetation on the aortic leaflets, and aortic valve replacement (Tekna-Edwards 19 mm) was performed. Histological findings of the vegetation showed Libman-Sacks endocarditis and infectious endocarditis. Predonisolone was infused intravenously to prevent the acute deterioration of SLE after the operation. She was discharged from the hospital three weeks after the operation.

Adult↗
PubMed1995

Effect of air-powder polishing on adhesion of bonding systems to tooth substrates.

OBJECTIVES: The air-powder polisher was introduced to provide a method to quickly remove stains and plaque. The purpose of this study was to evaluate what effect preparing teeth with an air-powder polisher (Air-flow 2, Shofu) has on bonding to enamel and dentin substrates. METHODS: The bonding systems used in this study were one-step etching/priming systems (KBT-5, Kanebo; and Clearfil Liner Bond II, Kuraray) and a two-step etching/priming system (Superbond D-Liner Plus, Sun Medical). Bovine enamel and dentin surfaces were prepared and finished with 600-grit silicon carbide paper. Then the surfaces were either not treated (control) or air-powder polished for 15 s. A 4-mm bonding area was demarcated, and the tooth substrates were bonded with the three bonding systems according to the manufacturers' instructions. Tensile bond strengths were measured 24 h after storage in water at 37 degrees C. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were performed on air-powder polished specimens to determine changes in the surface morphology and detect residual material from the air-powder polisher. SEM and transmission electron microscopic (TEM) observations of the interface between the bonding resins and dentin were performed to detect variations in the hybrid layers of the control and treated specimens. RESULTS: The results indicated that air-powder polishing did not influence the tensile bond strength to enamel, but adversely affected the tensile bond strength to dentin for the one-step systems, but not for the two-step system. Changes to the enamel surface after air-powder polishing were minimal, but an increase in surface roughness and complete removal of the smear layer were observed on dentin. SEM and TEM observations of the resin/dentin interface suggested that the air-powder polisher might cause superficial maceration of the collagen fibers on the dentin surface. This change may have decreased the ability of the etching/priming agents and bonding resin to penetrate into the dentin, which would have resulted in a poor quality hybrid layer. SIGNIFICANCE: For those systems that contain only an acidic primer for dentin conditioning, the use of air-powder polishing for surface preparation prior to restoration of dentin margin cavities is contraindicated because of the loss of reliable bonding.

Air Pressure↗
PubMed1995

Cytokine-induced neutrophil chemoattractant is necessary for interleukin-1-induced lung leak in rats.

Because interleukin-1 (IL-1) is not a potent chemoattractant intrinsically, our goal was to determine whether cytokine-induced neutrophil chemoattractant (CINC) mediates neutrophil accumulation and leak that occur in lungs of rats given IL-1 intratracheally. We found that rats given IL-1 intratracheally had increased lung lavage CINC concentrations, lung myeloperoxidase (MPO) activity, lung lavage neutrophil numbers, and lung leak compared with saline-treated control rats. In parallel, rats given increasing doses of anti-CINC antibody along with IL-1 intratracheally had progressively decreased lung lavage CINC concentrations, lung lavage neutrophil numbers, and lung leak, but the same lung MPO activity, as did rats given only IL-1 intratracheally. In addition, lavage CINC concentrations correlated with lavage neutrophil numbers in rats. Because CINC is a chemoattractant in vitro and because anti-CINC antibody decreased lung leak induced by IL-1, CINC was then given alone intratracheally. Rats given only CINC intratracheally had the same lung MPO activity, lung lavage neutrophil numbers, and lung leak as did saline-treated control rats. These observations suggest that instilling IL-1 intratracheally induces lung leak via a CINC-dependent pathway but that administering CINC alone in concentrations exceeding the levels measured in lung lavages from IL-1-treated rats is not sufficient to cause lung neutrophil accumulation and lung leak.

Animals↗
PubMed1995

Relationships among 64k autoantibodies, pancreatic beta-cell function, HLA-DR antigens and HLA-DQ genes in patients with insulin-dependent diabetes mellitus in Korea.

OBJECTIVES: Among autoantibodies detected in patients with insulin-dependent diabetes mellitus (IDDM), antibodies to 64,000(Mr) islet protein(64k), now recognized as glutamic acid decarboxylase(GAD), appear to be an even more predictive marker of IDDM than islet cytoplasmic antibody (ICA) or insulin autoantibody (IAA). We examined the relationships among 64k autoantibodies, pancreatic beta-cell function, HLA-DR antigens and HLA-DQ genes in patients with IDDM in Korea. METHODS: To identify the 64k autoantibody, the immunoprecipitation method was performed for 35 patients with IDDM and 10 normal controls. In patients with IDDM, serum C-peptide levels were measured and HLA-DR typings and HLA-DQA1 and DQB1 gene typings were performed. RESULTS: 12 of 35 (34%) patients with IDDM were positive for 64k autoantibody in contrast to none of 10(0%) normal controls. There were no differences in residual pancreatic beta-cell function between 64k autoantibody positive and negative groups. 64k autoantibody was detected more frequently in patients with recent (duration < 6 months, 10/25[40%]) and young -aged(aged < 15 years, 7/18[39%]) onset of IDDM. All of 3(100%) patients with HLA-DR3/DR4 heterotypes were positive in 64k autoantibody, in contrast to 1 of 7(14%) patients without HLA-DR3 nor DR4. The frequencies of HLA-DQA1*0301, HLA-DQB1*0201, DQB1* 0302 and DQB1*0303 gene types were higher in patients with 64k autoantibody (12/12 [100%]) vs. without 64k autoantibody 18/22[81%], 5/11[45%] vs. without 64k autoantibody 5/22[23%], 5/11[45%] vs. without 64k autoantibody 8/22[36%] and 6/11 [55%] vs. without 64k autoantibody 9/22[41%]. CONCLUSIONS: There results suggest that 64k autoantibodies have some relationship with HLA-DR, DQA1 and DQB1 genes, but not with residual pancreatic beta-cell function in Korean patients with IDDM.

Adolescent↗
PubMed1993

Requirement of phenylalanine 343 for the preferential delta 4-lyase versus delta 5-lyase activity of rat CYP17.

Site-directed mutagenesis of a domain (amino acids 343-348) within the conserved region of rat CYP17 was performed to investigate species-specific differences between rat and human/bovine delta 4-versus delta 5-lyase activity. This domain displays substantial deviations between the rat and human/bovine/pig sequences and includes Arg346, which is known to be essential for delta 4-lyase (Kitamura, M., Buczko, E., and Dufau, M. L. (1991) Mol. Endocrinol. 5, 1373-1380) and delta 5-lyase activities. Analysis of the delta 4-lyase activity of mutant rat CYP17 cDNA expressed in nonsteroidogenic COS-1 cells revealed that substitution of Phe at position 343 in the rat with Ile of the human/bovine sequence resulted in a reduction in delta 4-lyase activity to levels in the range of the delta 5-supported reaction. This Phe343-->Ile mutant CYP17 did not exhibit changes either in delta 5-supported lyase activity or in delta 4- and delta 5-hydroxylase activities. Substitution of Asn344, Ser347, and His348 in rat CYP17 with the corresponding bovine amino acids Ser, Asn, and Arg did not enhance this effect. Thus, the reduced activity of the bovine CYP17 delta 4-lyase reaction can be mimicked in part in the rat polypeptide by the substitution of Phe343 with the bovine counterpart, Ile. Unlike the bovine CYP17-catalyzed reaction, the rat Phe343-->Ile mutant exhibited a low level lyase activity (kcat) that did not discriminate between delta 4- and delta 5-substrates. These results suggest that the presence of Phe343 enhances the delta 4-supported lyase activity possibly through stabilization of a delta 4-specific interaction.

Aldehyde-Lyases↗