Biomedical subjects

O S Kwon

Publications and source records attributed to O S Kwon.

At least 55 records · Page 3Linked to original sources

PubMed1997

Fumonisin B1 in developing rats alters brain sphinganine levels and myelination.

Objectives of this study were to test the hypothesis that fumonisin B1 (FB1) alters sphinganine (Sa) levels and myelin synthesis in the central nervous system of developing rats. FB1 (subcutaneous, 0.4 or 0.8 mg/kg/day) from postnatal days (PND) 3 to PND 12 resulted in a significant reduction of body weight gain and decreased survival rates. Both Sa levels and Sa/sphingosine (So) ratios were significantly increased in the brain of rats given 0.8 mg FB1/kg/day. To confirm the effect of limited nutrition on changes in the Sa levels and myelinogenesis, rats given 0.8 mg FB1/kg/day or treated by limited nutrition (temporary removal from dam during postnatal period) were compared to those in saline controls. Sa levels and Sa/So ratios were increased significantly in the 0.8 FB1-treated, but were not altered in the limited nutrition group. Myelin deposition in the corpus callosum and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) activities were decreased significantly in both nutritionally limited and FB1-exposed rats. These data indicate that sphingolipid metabolism in the central nervous system of developing rats is vulnerable to FB1 exposure. The hypomyelination associated with FB1-treatment may be mediated by limited nutrition.

Animal Nutritional Physiological Phenomena↗

PubMed1997

Epstein-Barr virus-associated lymphoproliferative eruption with progression to large granular lymphocytic leukaemia.

A 12-year-old Korean girl gave a 9-year history of recurrent necrotizing papules and vesicles on the face, scalp and extremities. Skin biopsy specimens showed an atypical lymphoreticular infiltrate with vasculitis in the dermis and subcutis. In situ hybridization demonstrated latent infection by Epstein-Barr virus (EBV) of the lymphoid cells in the dermis. The disease was diagnosed as an EBV-associated lymphoproliferative skin eruption presenting as recurrent necrotic papulovesicles. The patient subsequently developed large granular lymphocytic leukaemia of natural killer cell origin. Our observations suggest that a patient with an EBV-associated lymphoproliferative skin eruption presenting with recurrent necrotic papulovesicles might progress to develop leukaemia as well as lymphoma.

Child↗

PubMed1997

A newly designed miniplate staple for high tibial osteotomy.

A biomechanical study was made to compare the mechanical performance of the newly designed Miniplate staple to the conventional Coventry staple in high tibial osteotomy (HTO). Using twenty fresh porcine tibiae, the fixational strength of the two different types of staples in HTO was compared. To minimize the error due to the specimen-to-specimen individuality, the bone mineral density of the tibiae was measured with bone densitometry and those with 0.8 to 1.2 gm/cm2 at the proximal tibia were used in the biomechanical test. Testing was performed on a material testing system with aid of a commercial data processor. Using two different loading modes, "pull-out" and "push-out," the maximum resistant force required to release the staple from the substrate bone was recorded. In the pull-out test, ten nonosteotomized specimens were used and the staple was pulled out by subjecting an axial tension on the head of the staple inserted. In the push-out test ten tibiae osteotomized in the usual method of HTO were used and the staple was not directly loaded. In this testing, as a mimic condition of the natural knee, the proximal part of the specimen tibia was pushed horizontally in order for the staple to be pulled out while the distal tibia was fixed. The pull-out strength of Coventry staple and Miniplate staple were found to be 27.88 +/- 5.12 kgf and 182.47 +/- 32.75 kgf, respectively. The push-out strength of Coventry staple and Miniplate staple were 18.40 +/- 4.47 kgf and 119.95 +/- 19.06 kgf, respectively. The result revealed that the Miniplate staple has both a pull-out and push-out strength that is more than six times higher than Coventry staple. Based on the data, it is believed that the Miniplate staple provides better postoperative fixation in HTO. The postoperative application of long leg casting may not be needed after HTO surgery.

Animals↗

PubMed1997

Snapping knee caused by the gracilis and semitendinosus tendon. A case report.

There are many reports about the snapping syndrome in the hip, shoulder, and ankle, but the snapping knee has rarely been reported. In general, the symptom of this disorder is relatively tolerable and seldom requires operative treatment. We experienced one case of the snapping knee, for which the pain, easy fatigability, and feeling of instability on both knee joints were the main complaints. During an exploratory operation, we confirmed the gracilis and semitendinosus tendon passing over the medial tibial condyle. The clinical, radiologic, and operative findings are reviewed.

Adult↗

PubMed1996

Survey of natural occurrence of trichothecene mycotoxins and zearalenone in Korean cereals harvested in 1992 using gas chromatography/mass spectrometry.

For the survey of the natural occurrence of trichothecene mycotoxins, produced by species of fungi imperfecti such as Fusarium and Trichothecium, a sensitive analytical method was developed for the simultaneous detection and quantitation of the major trichothecene mycotoxins, viz. T-2 toxin (T-2), HT-2 toxin (HT-2), nivalenol (NIV), fusarenon-X (F-X), deoxynivalenol (DON), 3-acetyl deoxynivalenol (3-Ac DON), and zearalenone (ZEN), using gas chromatography/mass spectrometry-selected ion monitoring (GC/MS-SIM) mode after trimethyl silyl derivatization. The incidence of NIV and DON in 30 barley samples were 93% and 67%, respectively; the average contents of NIV and DON in positive samples were 390 ng/g (range 40-2038) and 106 ng/g (range 5-361) respectively. In 15 maize samples, the incidences of NIV and DON were 53% and 93% respectively and the average contents were 168 ng/g and 145 ng/g, respectively. These results suggest that NIV and DON were the major contaminating trichothecene mycotoxins in Korean barley and maize samples harvested in 1992.

Edible Grain↗

PubMed1996

Congenital onychodysplasia of the index fingers--Iso-Kikuchi syndrome. A case involving the second toenail.

We report a case of congenital onychodysplasia of the index fingers (Iso-Kikuchi syndrome) in a 2-year-old boy who had nail deformities on both index fingers and the left second toe. He had a micronychia of the left index fingernail, malalignment and abnormal lunula of the right index fingernail and micronychia and malalignment of the left second toenail. Congenital onychodysplasia of the index fingers (COIF) is a rare condition characterized by various forms of nail dysplasia commonly involving the index fingers, but not infrequently also the neighbouring fingers such as the middle fingers and thumbs. The five criteria characterizing COIF include the following: (i) congenital occurrence; (ii) unilateral or bilateral index finger involvement; (iii) variability in nail appearance; (iv)possible hereditary involvement; and (v) frequently associated bone abnormalities. The nails of COIF include the full spectrum of nail dysplasia, from an irregular lunula, malalignment, micronychia (hypoplastic and rudimental), polyonychia (split rudimental), and anonychia, specifically affecting the index fingers. Our patient represents various forms of nail dysplasia of the both index fingers and left second toe such as micronychia, malalignment and abnormal lunula. To our knowledge, the association with second toenail dysplasia in COIF has not previously been reported.

Child, Preschool↗

PubMed1996

Enhanced proliferation and collagen synthesis of human dermal fibroblasts in chronically photodamaged skin.

Cutaneous aging can be divided into intrinsic aging and photoaging. We investigated the influence of aging and photoaging on the proliferation and collagen synthesis of human dermal fibroblasts cultured 3-dimensionally in a collagen gel. We examined 11 human dermal fibroblast cell lines cultured from 3 newborn skins (1 day old), and both exposed and unexposed skin from 4 elderly volunteers (60, 60, 73, 76 years old), respectively. Newborn fibroblasts actively proliferated within the attached collagen gels compared with the elderly cell lines. Within the attached collagen gels in the presence of 10% fetal calf serum (FCS), the fibroblasts from exposed skin proliferated rapidly compared with fibroblasts from unexposed skin from the same individuals. In collagen gel and monolayer cultures with 1% FCS, the percentage of collagen synthesized by photoaged and aged fibroblasts decreased significantly compared with that by newborn fibroblasts. When the fibroblasts were cultured three dimensionally in attached collagen gels in the presence of 1% FCS, the relative levels of collagen synthesis by cultured fibroblasts from photoaged skin were increased significantly compared with those of aged skin fibroblasts from the same individuals. These results suggest that fibroblasts of exposed skin may be more active than those of unexposed skin and that the three-dimensional culture of fibroblast can be used as a model to investigate the influence of aging and photoaging on cell functions.

Aged↗

PubMed1994

Luminescence spectroscopy of pyridoxic acid and pyridoxic acid bound to proteins.

Luminescence techniques, i.e. fluorescence and phosphorescence, have been employed to study pyridoxic acid bound to proteins through a stable amide linkage. Proteins tagged with 4-pyridoxic acid display the following fluorescence properties: (a) emission and excitation spectra centered at around 430 and 320 nm, respectively; (b) fluorescence quantum yields of 0.3-0.4 and (c) average decay times covering the range 8-9.6 ns. The fluorescence properties of the probe have been used to study the dynamics of the protein in the nanosecond time scale. In the absence of molecular oxygen, free and bound 4-pyridoxic acid exhibit long-lived emission at room temperature. The long-lived emission is red-shifted when compared to fluorescence and decays with average life times ranging over 2.2-0.6 ms depending on the nature of the protein. The fluorophore pyridoxic acid covalently linked to proteins is suitable to study the dynamics of proteins, i.e. fast and slow motions of the macromolecule in the nanosecond and millisecond time scales, respectively.

Fluorescence Polarization↗

PubMed1994

Interaction of 70-kDA heat shock cognate protein with peptides and myo-inositol monophosphatase.

Fluorescence techniques have been used to investigate the interaction of bovine 70-kDa heat shock cognate protein (Hsc 70) with small molecular weight peptides and myo-inositol monophosphatase. The emission properties of Hsc 70 remain invariant upon addition of ATP. The results of steady-state fluorescence indicate that the tryptophan residues of Hsc 70 are exposed to the rapidly relaxing aqueous solvent. Binding of residues 1-20 of ribonuclease A (RNase S-peptide) to Hsc 70 causes protein fluorescence quenching which was used to determine a dissociation constant Kd = 2.7 microM for the binary Hsc 70.RNase S-peptide complex. The octapeptide corresponding to the NH2-terminal portion of sickle cell hemoglobin recognizes Hsc 70 and binds with a Kd = 9.3 microM. Binding of RNase S-peptide to Hsc 70 produces a small enhancement of ATPase activity. Unfolded myo-inositol monophosphatase, tagged with the fluorescent probe 5-[2-(2-iodoacetamido)ethylamino]-1-naphthalenesulfonic acid, recognizes Hsc 70; the formation of a stable complex was detected by steady-state emission anisotropy measurements. The rate and extent of recovery of catalytic activity of unfolded myo-inositol monophosphatase is not influenced by Hsc 70. It is suggested that interaction of Hsc 70 with unfolded proteins in the cell may be able to delay the formation of misfolded structures.

Adenosine Triphosphatases↗

PubMed1993

Reversible unfolding of myo-inositol monophosphatase.

myo-Inositol monophosphatase isolated from pig brain is a very stable dimeric protein characterized by a rotational correlation time of 30 ns. The unfolding and dissociation of the dimeric enzyme (58 kDa) by guanidine hydrochloride have been investigated at equilibrium. The overall process was reversible as judged from the complete recovery of catalytic activity after dilution of guanidine hydrochloride-treated samples. Unfolding of myo-inositol monophosphatase was monitored by circular dichroism, fluorescence, and steady state emission anisotropy. A folded, monomeric form of the monophosphatase was not detected by the method of denaturant gel filtration. Uncoupled dissociation and unfolding of the oligomeric enzyme could not be demonstrated. The circular dichroism and emission anisotropy results are consistent with a model in which the dimeric protein unfolds in a single cooperative transition from folded dimer to two unfolded monomers.

Animals↗

PubMed1993

Interaction of ATP analogs with yeast 3-phosphoglycerate kinase. Affinity labeling of the hinge region.

Yeast 3-phosphoglycerate kinase is inactivated by incubation with pyridoxal 5'-diphospho-5'-adenosine (AdoP2Pxy) [Tamura, J. K., Rakov, R. D. & Gross, R. L. (1986) J. Biol. Chem. 261, 4126-4133). Incorporation of 1 mol affinity label/mol enzyme was sufficient for complete inactivation of 3-phosphoglycerate kinase. The substrate ATP affords substantial protection against inactivation. Partial protection is afforded by the substrate glycerate 3-phosphate. When AdoP2Pxy-modified phosphoglycerate kinase was reduced with [3H]NaBH4 and subjected to trypsin hydrolysis, only one radioactive peptide was isolated by reverse-phase high-performance liquid chromatography. The amino acid composition and sequence analysis of the purified radioactive peptide revealed that it spans residues 379-403 of the enzyme and Lys385 specifically reacted with the affinity label. This peptide represents the hinge region between the two domains of the protein, where the active site is also located. The fluorescence intensity of enzyme-bound AdoP2Pxy is enhanced when glycerate 3-phosphate is added, suggesting exposure of the fluorescent probe to a more hydrophobic environment. Another fluorescent analog, anthraniloyl-dATP (ant-dATP), which carries the fluorescent reporter group on the ribose ring, binds to the enzyme at two distinct sites with Kd values of 6 +/- 2 microM and 25 +/- 3 microM, as determined by steady-state anisotropy measurements. Bound ant-dATP was displaced from the enzyme by glycerate 3-phosphate and ATP, as monitored by the fluorescence anisotropy. These results suggest that both fluorescent ATP analogs bind to the active site, which is at the hinge region of the enzyme. Model-building studies showed that when AdoP2Pxy is built into the open form of the enzyme, as described in X-ray studies, the pyridoxyl group of AdoP2Pxy cannot reach Lys385 for Schiff-base formation. Labeled Lys385 is on a beta-turn immediately following helix XII, which was suggested to interact with the nucleotide and become ordered at the active site of 3-phosphoglycerate kinase [Watson, H. C., Walker, N. P. C., Shaw, P. J., Bryant, T. N., Wendell, P. L., Fothergill, L. A., Perkins, R. E., Conroy, S. C., Dobson, M. J., Tuite, M. F., Kinesman, A. J. & Kinesman, S. M. (1982) EMBO J. 1, 1635-1640]. The results presented here suggest that binding of substrates cause significant structural changes in the enzyme.

Adenosine Diphosphate↗

PubMed1993

Seroepidemiological observation of Taenia solium cysticercosis in epileptic patients in Korea.

Prevalence survey of neurocysticercosis was made in a mixed epilepsy patients of Changmi Club in Korea. From February 1987 to July 1990, a total of 2,667 randomly selected patients at 27 local centers was tested for their serum levels of anti-Cysticercus antibody (IgG) by enzyme-linked immunosorbent assay. Positive rate of the antibody was 4.0% in the examined patients. The standardized antibody positive rate by provincial population was 3.1%. The rate was the highest in patients living in Cheju Do (8.4%). The patient age brackets of 0 approximately 9 years and over 50-year showed higher positive rates of the antibody. In 750 normal persons who checked up routine physical examination, the antibody positive rate was 2.1% (standardized rate was 1.8%). These seroepidemiological data disclosed for the first time the prevalence of cysticercosis in epileptic patients and in population.

Adolescent↗

PubMed1992

Brain 4-aminobutyrate aminotransferase. Isolation and sequence of a cDNA encoding the enzyme.

4-Aminobutyrate aminotransferase is a key enzyme of the 4-aminobutyric acid shunt. It is responsible for the conversion of the neurotransmitter 4-aminobutyrate to succinic semialdehyde. By using oligonucleotide probes based on partial amino acid sequence data for the pig brain enzyme, several overlapping cDNA clones of 2.0-2.2 kilobases in length have been isolated. The largest cDNA clone was selected for sequence analysis. The amino acid sequence predicted from the cDNA sequence shows that the precursor of 4-aminobutyrate aminotransferase consists of the mature enzyme of 473 amino acid residues and an amino-terminal segment of 27 amino acids attributed to the signal peptide. The cofactor pyridoxal-5-P is bound to lysine residue 330 of the deduced amino acid sequence of the mature enzyme.

4-Aminobutyrate Transaminase↗

PubMed1992

The effects of probenecid on the excretion kinetics of stanozolol, an anabolic steroid, in rats.

The pharmacokinetic behaviour and the mechanism of renal excretion of stanozolol (STZ), as affected by co-treatment with probenecid, were studied in male Sprague-Dawley rats. Pharmacokinetic parameters following intravenous (i.v.) administration of STZ (20 mg kg-1 body wt.) were measured in both STZ-treated (control) and STZ plus probenecid-treated (treatment) groups. In order to assess the renal clearance of STZ, bolus doses of STZ and inulin (40 mg kg-1 body wt.) were injected i.v. either in the presence or absence of probenecid (40 mg kg-1 body wt.). The blood and urine concentrations of STZ were determined by capillary gas chromatography-mass spectrometry (GC-MS). In the probenecid treatment group, the area under the plasma disappearance and urinary excretion curves (AUC) of STZ were significantly decreased (P < 0.01) and the volume of distribution (Vd) and total clearance (CLt) were significantly increased statistically (P < 0.05 and P < 0.01, respectively). No remarkable differences in the urine flow rate, urine pH values, glomerular filtration rate (GFR) or renal clearance were observed in the treatment group. However, the clearance ratio in the treatment group was significantly increased from 11.72 to 17.27. From these results, it is suggested that the significant decrease of AUC, i.e. increase of disappearance of STZ in plasma by co-administration with probenecid, is due to the increase of the clearance ratio.

Animals↗

PubMed1991

[Antigenic localities in the tissues of the young adult worm of Paragonimus westermani using immunogold labeling method].

In order to observe the antigenic localization in the tissues of the young adult Paragonimus westermani, immunogold labeling method was applied using serum immunoglobulins(IgG) of the dog which infected with isolated metacercariae from Cambaroides similis. The sectioned worm tissue was embedded in Lowicryl HM 20 medium and stained with infected serum IgG and protein A gold complex (particle size; 12 nm). It was observed by electron microscopy at each tissues of the worm. The gold particles were not observed on the basal lamina of the tegument, interstitial matrix of the parenchyma, the muscle tissue and mitochondria of the tegument. The gold particles were specifically labeled in the secretory granules in the vitelline cells. They were predominantly labeling on the epithelial lamela and lumen of caecum. The above finding showed that antigenic materials in young adult worm tissue were specifically concentrated on the tegumental syncytium as well as cytoplasm of tegumental cells.

Animals↗

PubMed1986

Immunological abnormalities in patient with IgA nephropathy.

T cell immunity and phagocytic activity were studied in the blood of patients with IgA nephropathy in order to clarify their roles in the pathogenesis of IgA nephropathy. The percentages of total T lymphocytes, helper T cell and suppressor T cells were significantly reduced in patients. A significantly elevated helper T cell/suppressor T cell ratio in patients showed a predominant reduction in suppressor T cells. There was a significant relationship between histologic findings and helper T cell/suppressor T cell ratio in patients. Natural Killer (NK) cell activity was significantly reduced but the lymphocyte response after phytohemagglutinin (PHA) stimulation was not in patients. ConA-induced suppressor cell activity was not depressed despite of a decrease in suppressor T cells in patients. Phagocytic activity of polymorphonuclear leucocytes (PMNs) ingesting yeasts was significantly reduced in patients. Also an inverse correlation was found between serum IgA levels and phagocytic activity of PMN. It is concluded that suppressor T cell defects, depressed phagocytic activity and impaired NK cell activity may play a role in the pathogenesis of IgA nephropathy.

B-Lymphocytes↗

PubMedDate not supplied

Biochemical and morphological effects of fumonisin B(1) on primary cultures of rat cerebrum.

Chronic dietary consumption of the mycotoxin fumonisin B(1) (FB(1)) is associated with leukoencephalomalacia and neuronal degeneration, but identification of the cellular mechanisms underlying this neurotoxicity is difficult due to concurrent adverse systemic changes. For this reason, the present investigation used an in vitro approach to assess the short-term consequences of direct FB(1) (0. 5-75 microM) exposure on astrocytes and oligodendrocytes in primary cultures of rat cerebrum. Beginning at 5 days in vitro, the cultures were exposed to FB(1) at five concentrations (0.5-75 microM), and the cultures were evaluated at 10 and 15 days in vitro. The levels of the sphingolipid-associated constituents sphingosine and sphinganine were determined with a high-performance liquid chromatography. Relative to untreated cultures, exposure to FB(1) diminished the levels of sphingosine at 15 days in vitro, whereas FB(1)-exposed cultures showed significantly increased sphinganine levels and sphinganine/sphingosine ratios. In addition to these changes in sphingolipid constituents, FB(1)-exposed (0.5-75 microM) cultures exhibited a two-fold increase in the number of process-bearing cells by 15 days in vitro. Also, the activity of 2', 3'-cyclic nucleotide 3'-phosphohydrolase, an enzyme associated with myelin and oligodendrocytes, was increased in FB(1)-treated cultures. This study suggests that short-term exposure to FB(1) may modify the proliferation or differentiation of glial cells.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗

PubMedDate not supplied

Effects of fumonisin B1 treatment on blood-brain barrier transfer in developing rats.

Fumonisin B1 (FB1), a toxic metabolite of the fungus Fusarium moniliforme found in contaminated corn, is considered an etiologic agent of equine leukoencephalomalacia. Because FB1 exposure is associated with alteration of sphingolipid metabolism, the purpose of this study was to elucidate whether blood sphinganine (Sa) levels affect brain Sa levels. Sa and sphingosine (So) levels in brain tissue and plasma were analyzed by HPLC. Area under the curve (AUC0-20h) ratios of brain Sa to plasma Sa levels were about 40 after a single 0.8 or 8 mg/kg SC dose of FB1. The AUC0-12h ratio of brain FB1 to plasma FB1 was 0.02. The fact that FB1 alters brain Sa levels and Sa/So ratios indicates that sphingolipid metabolism in the central nervous system of developing rats is vulnerable to FB1 exposure. These data support our hypothesis that alterations of the brain Sa levels are related to the direct action of FB1 on the brain rather than transport of peripheral Sa to the brain.

Animals↗