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Biomedical subjects

S H Oh

Publications and source records attributed to S H Oh.

At least 55 records · Page 3Linked to original sources
PubMed2000

Identification of a novel human member of the DEAD box protein family.

The cDNA library of human pancreatic islets was screened with sera from patients with insulin-dependent diabetes mellitus (IDDM). From the library screening, we isolated a novel cDNA, RNA helicase-like protein (RHELP), which exhibited strong sequence homology to p68 RNA helicase, a prototypic member of the DEAD (Asp-Glu-Ala-Asp) box protein family. Sequence analysis of the cDNA revealed that RHELP contained DEAD sequence motif and other conserved motifs of the DEAD box protein family, indicating that RHELP is a new member of this family. DEAD box-containing proteins are involved in the RNA processing, ribosome assembly, spermatogenesis, embryogenesis, and cell growth and division. RHELP showed 42% and 44% amino acid sequence identity to human p68 RNA helicase and yeast DBP2 RNA helicase, respectively, among the DEAD box protein family. Northern blot analysis revealed that RHELP is expressed in most tissues including the liver, lung, tonsil, thymus, and muscle in addition to the pancreatic islets. In vivo or in vitro functions of RHELP as a putative RNA helicase and its potential role as a diabetic autoantigen need to be further investigated.

Amino Acid Sequence↗
PubMed2000

Hemidystonia and hemichoreoathetosis as an initial manifestation of moyamoya disease.

OBJECTIVE: To describe hemidystonia and hemichoreoathetosis in an adult patient with moyamoya disease without a previous history of cerebrovascular accident. DESIGN: Case report. SETTING: Tertiary care center. PATIENT: A 22-year-old woman suddenly developed dystonic spasms in her left hand and left foot after a severe emotional stress. The dyskinesia gradually subsided over the next 4 months. Five months after the onset, she suddenly developed choreoathetoid movement in her right hand and right foot. MAIN OUTCOME AND RESULTS: The patient had both somatic and cortical sensory deficits in the right hand and right foot. Magnetic resonance imaging of the brain showed an infarction at the right putamen and lesions involving the right frontal lobe and the left frontotemporoparietal lobe. Magnetic resonance cerebral angiography showed severe stenoses of both internal carotid arteries at the supraclinoid portion and numerous collateral vessels, compatible with moyamoya disease. Single photon emission tomography of the brain showed hypoperfused areas at the right frontal and left frontotemporoparietal lobes. The choreoathetosis of the right limbs improved markedly, along with improvement of sensory deficits. CONCLUSIONS: To our knowledge, this is the first report of an adult patient presenting with hemidystonia and hemichoreoathetosis as the initial manifestations of moyamoya disease. Arch Neurol. 2000;57:1510-1512

Adult↗
PubMed2000

Expression of 3 beta-hydroxysteroid/dehydrogenase/delta5-delta4/isomerase in the tracheal cartilage of the rat.

The enzyme complex 3beta-hydroxysteroid dehydrogenase isomerase/delta5-delta4 (3beta-HSD) is involved in the biosynthesis of all classes of active steroids. In this study, the presence of 3beta-HSD was defined in rat tracheal cartilage. The expression of the 3beta-HSD gene was examined by Northern blot analysis from 30-day-old rats. Western blot and immunohistochemical localization were also performed with antibodies raised against purified human placental 3beta-HSD to obtain further information on the expression of 3beta-HSD protein during fetal and postnatal periods of development in rat cartilage. Northern blot analysis using an oligonucleotide common to the 4 known 3beta-HSD isoforms showed 3beta-HSD mRNA corresponding to a transcript of 1.7 kb. Furthermore, a 42 KDa protein band was detected in the tracheal cartilage extracts by Western blot analysis. Immunostaining for 3beta-SD was observed in chondrocytes. The first expression was detected on the 17th day of fetal life by Western blot and immunohistochemistry. Immunoreactivity of 3beta-HSD showed a significant increase at 7 and 15 days after birth, and then remained unchanged through adulthood, in agreement with the data of the Western blot. Our results demonstrated the expression for 3beta-HSD in the tracheal cartilage at both the mRNA and protein levels during fetal life and postnatal development of the rat. These results suggest that 3beta-HSD may synthesize certain steroids which play major roles in differentiation and maintenance of function during development of rat cartilage.

3-Hydroxysteroid Dehydrogenases↗
PubMed2000

Expression of heat shock protein 72 in rat cochlea with cisplatin-induced acute ototoxicity.

Cisplatin ototoxicity is known to involve mainly the organ of Corti. Outer hair cells (OHCs). especially in the basal turn, are preferentially involved. One possible mechanism of ototoxicity might be alteration of the antioxidant system causing an increase in free radicals. It has been demonstrated that heat shock proteins (HSPs), which are believed to protect cells by dissolving and refolding misfolded or denatured protein are induced by various form of stress. HSP is also demonstrated to be induced by free radicals. The purpose of this study was to evaluate HSP 72 induction in cochlea following cisplatin injection in the animal model. Sprague-Dawley (SD) rats were injected intraperitoneally with normal saline as control or cisplatin at a dose of 5, 10 or 20 mg/kg. Cochleae were harvested 1, 3, 6 and 12 h after injection and compared with those of controls. Immunocytochemical study with surface preparation and Western blotting were performed to investigate the expression of HSP 72. Auditory brainstem response (ABR) was also recorded to assess functional change according to the dosage of cisplatin and duration after injection. In the 5 and 10 mg/kg groups, immunostaining for HSP 72 in the OHCs reached a plateau level at 3 h, which was maintained until 12 h after injection. The amount of immunoreactive OHCs in the 20 mg/kg group was smaller than those in 5 and 10 mg/kg groups and declined after 6 h. The bands for HSP 72 became less intense as the cisplatin dosage increased from 5 to 10 and 20 mg/kg in Western blotting. The change in ABR threshold was small in the 5 and 10 mg/kg groups and a marked change in threshold was observed in the 20 mg/kg group. Detection of HSP 72 after cisplatin injection could confirm the OHCs as one of the major injured cells in the cochlea. With a lethal dosage of cisplatin (20 mg/kg), HSP 72 expression was less prominent and declined after 6 h.

Animals↗
PubMed2000

Chronic Helicobacter pylori infection induces an apoptosis-resistant phenotype associated with decreased expression of p27(kip1).

Helicobacter pylori infection is associated with the development of gastric cancer. In short-term coculture with AGS gastric cells, H. pylori inhibits cell cycle progression and induces dose-dependent apoptosis. Based on the concept that an imbalance between proliferation and apoptosis may contribute to the emergence of gastric cancer, we chronically exposed AGS cells to H. pylori as a model of chronic exposure in humans. The AGS derivatives selected by this process were stably resistant not only to H. pylori-induced apoptosis but also to apoptosis induced by other enteric bacteria and by several toxic agents including radiation and cancer chemotherapy. Like the parental AGS cells, the derivatives underwent G(1)/S-phase cell cycle inhibition in response to H. pylori. The AGS derivatives displayed a marked decrease in cellular levels of the cell cycle control protein p27(kip1). We found a similar decrease in epithelial cell p27(kip1) expression in gastric biopsy specimens from H. pylori-infected patients. These findings are consistent with observations that link decreases in the p27(kip1) level to increased susceptibility to cancer in mice with p27(kip1) deleted and to a poor prognosis of gastric cancer in humans. This is the first demonstration that bacterial infection can lead to apoptosis resistance and to cross-resistance to other inducers of apoptosis such as bacteria, chemotherapeutic agents, and radiation. The development of apoptosis resistance and downmodulation of p27(kip1) may contribute to the increased risk for gastric cancer observed in humans chronically exposed to H. pylori.

Apoptosis↗
PubMed2000

Pyriform sinus fistula: management with chemocauterization of the internal opening.

A branchial remnant originating in the pyriform sinus causes a recurrent fistula or abscess in the neck. In spite of excision, recurrence may result from inadequate removal of the fistula tract. We attempted chemocauterization of the internal opening of the fistula tract with trichloroacetic acid (TCA) on direct endoscopy. This is a 6-year review of 18 patients with pyriform sinus fistula. Medical history, barium esophagography, computed tomography scans, operative findings, and treatment results were analyzed. By direct endoscopy, all patients were found to have a fistula opening in the pyriform sinus, exclusively on the left side. In only 9 patients, the fistula tract was identified by barium esophagography before operation. Computed tomography revealed a suspicious fistula tract originating from the pyriform sinus in 8 of 10 patients. Sixteen patients were initially managed by TCA chemocauterization. There were no serious intraoperative or postoperative complications. Four patients had recurrent masses, which were managed by simple excision in 2 patients and repeated TCA cauterization in the other 2 patients with unobliterated internal openings. We recommend barium swallow study and direct endoscopy for all patients presenting with a recurrent lateral neck abscess, especially on the left side. Our results suggest that initial chemocauterization of the internal opening can be a reasonable alternative procedure for the management of pyriform sinus fistula.

Abscess↗
PubMed2000

Zinc as a paracrine effector in pancreatic islet cell death.

Because of a huge amount of Zn2+ in secretory granules of pancreatic islet beta-cells, Zn2+ released in certain conditions might affect the function or survival of islet cells. We studied potential paracrine effects of endogenous Zn2+ on beta-cell death. Zn2+ induced insulinoma/islet cell death in a dose-dependent manner. Chelation of released endogenous Zn2+ by CaEDTA significantly decreased streptozotocin (STZ)-induced islet cell death in an in vitro culture system simulating in vivo circumstances but not in the conventional culture system. Zn2+ chelation in vivo by continuous CaEDTA infusion significantly decreased the incidence of diabetes after STZ administration. N-(6-methoxy-quinolyl)-para-toluene-sulfonamide staining revealed that Zn2+ was densely deposited in degenerating islet cells 24 h after STZ treatment, which was decreased by CaEDTA infusion. We show here that Zn2+ is not a passive element for insulin storage but an active participant in islet cell death in certain conditions, which in time might contribute to the development of diabetes in aged people.

Biological Transport↗
PubMed1999

Synthesis of recombinant blood coagulation factor VIII (FVIII) heavy and light chains and reconstitution of active form of FVIII.

FVIII is synthesized as a single chain precursor of approximately 280 kD with the domain structure of A1-A2-B-A3-C1-C2 and it circulates as a series of metal ion-linked heterodimers that result from cleavages at B-A3 junction as well as additional cleavages within B domain. Factor VIII is converted to its active form, factor VIIIa, upon proteolytic cleavages by thrombin and is a heterotrimer composed of the A1, A2, and A3-C1-C2 subunits. A1 subunits of factor VIIIa terminates with 36 residue segment (Met337-Arg372) rich in acidic residues. This segment is removed after cleavages at Arg336 by activated protein C, which results in inactivation of the cofactor. In the present study, site-directed mutagenesis of FVIII at Arg336 to Gln336 was performed in order to produce an inactivation resistant mutant rFVIII (rFVIIIm) with an extended physiological stability. A recombinant mutant heavy chain of FVIII (rFVIII-Hm; Arg336 to Gln336) and wild-type light chain of FVIII (rFVIII-L) were expressed in Baculovirus-insect cell (Sf9) system, and a biologically active recombinant mutant FVIII (rFVIIIm) was reconstituted from rFVIII-Hm and rFVIII-L in the FVIII-depleted human plasma containing 40 mM CaCl2. The rFVIIIm exhibited cofactor activity of FVIIIa (2.85 x 10(-2) units/mg protein) that sustained the high level activity during in vitro incubation at 37 degrees C for 24 h, while the cofactor activity of normal plasma was declined steadily for the period. These results indicate that rFVIIIm (Arg336 to Gln336) expressed in Baculovirus-insect cell system is inactivation resistant in the plasma coagulation milieu and may be useful for the treatment of hemophilia A.

Animals↗
PubMed1999

Helicobacter pylori inhibits the G1 to S transition in AGS gastric epithelial cells.

Infection with the bacterium Helicobacter pylori is associated epidemiologically with development of gastric cancer. To better understand the role of H. pylori in carcinogenesis, we examined the effects of H. pylori on cell cycle-related events in the AGS gastric cancer cell line. During coculture, wild-type, toxigenic, cagA-positive H. pylori induced both apoptosis and inhibition of cell cycle progression at G1-S in AGS cells. These effects were most apparent in AGS cells synchronized by serum-deprivation and then stimulated to progress through the cell cycle by refeeding. An isogenic cagA-negative mutant H. pylori, produced similar effects. In contrast to changes induced by 5-fluorouracil, the inhibition of cell cycle progression from G1 to S caused by H. pylori was not accompanied by sustained changes in p53 or p21cip1, but was associated with reduced expression of p27kip1 and inhibition of transcriptional activation of the serum-response element of c-fos. Our results indicate that H. pylori inhibits cell cycle progression at G1-S and induces apoptosis, associated with reduced expression of p27kip1 in AGS gastric cancer cells. In vivo, similar effects as a result of H. pylori infection may lead to potentially deleterious compensatory hyperproliferation by nonneoplastic gastric epithelial cells.

Antigens, Bacterial↗
PubMed1999

An efficient retrovirus-mediated transduction of human blood coagulation factor VIII cDNA in regenerating rat liver.

A retrovirus-mediated transduction of B-domain-deleted human blood coagulation factor VIII (FVIII-B) was attempted in partially hepatectomized rats. FVIII-B cDNA was inserted into a retroviral vector (pLNSX) and infective recombinant virus particles were produced in packaging cell lines (psi2 and PA317). Transfection of mouse NIH-3T3 cells with the FVIII-B cDNA inserted recombinant viruses, followed by G418 selection, gave a viral titer of 3.5 x 10(4) CFU/ml. FVIII-B protein, as well as FVIII-B mRNA, was detected in these cells. Transfusion of FVIII-B-expressing retrovirus particles into the tail vein of rats subjected to partial hepatectomy resulted in a relatively higher level of FVIII-B expression in liver and circulating plasma as compared with the sham-operated rats. These results indicate that the augmentation of FVIII activity in the blood of an animal by retroviral gene delivery can be enhanced by partial hepatectomy, and that the retrovirus-mediated FVIII-B cDNA delivery to regenerating liver may be an alternative method for the expression of FVIII-B cDNA in vivo.

3T3 Cells↗
PubMed1999

Effects of free radicals on ciliary movement in the human nasal epithelial cells.

OBJECTIVE: There have been few reports on the effects of free oxygen radicals on ciliary mobility of nasal respiratory epithelial cells. The aim of this study was to determine the effects of free radicals and antioxidants on human nasal epithelial cells (HNECs) using video-computerized analysis. METHODS: Human nasal epithelial cells were obtained from the nasal cavity of normal volunteers. Ciliary beat frequency (CBF) was calculated as the mean value of ten randomly selected cells. The proportion of the area with normal CBF (above 8 Hz) was calculated from 10 randomly selected sites per specimen. Free radicals were produced by xanthine-xanthine oxidase enzymatic system. The generation of free radicals was confirmed by chemoilluminometer. CBF and the proportion of the area with normal CBF were measured at every 5 min for 30 min after the addition of enzyme. For the evaluation of the antioxidant effects on free radical-mediated ciliary slowing in HNECs, cells were incubated in superoxide dismutase solution (300 unit/ml) for 30 min and 3-aminobenzamide (5 mM). RESULTS: Superoxide produced by 0.4 mM xanthine and 400 miliunit/ml xanthine oxidase decreased CBF (7.71 +/- 1.91 Hz). A total of 2 min later, ciliary slowing was evident (3.87 +/- 1.10 Hz). Regarding the changes in proportion of epithelial area that showed normal CBF experimental group showed a significant decrease in percentage of epithelial area with normal CBF over time. Superoxide dismutase prevented ciliary slowing (8.76 +/- 0.99 Hz). Moreover, 3-aminobenzamide, an inhibitor of the DNA repair enzyme poly-ADP ribose polymerase, prevented inhibition of CBF (8.32 +/- 0.61 Hz). CONCLUSIONS: These results suggest that oxygen-mediated damage to DNA may be the mechanism of the deterioration effects of oxygen radicals on the ciliated respiratory nasal epithelium.

Antioxidants↗
PubMed1999

Changes in intracellular content of glutathione and thiols associated with gamma-glutamyl cycle during sperm penetration and pronuclear formation in rat oocytes.

The content of glutathione and other thiols in rat eggs was examined during sperm penetration and pronuclear formation by high-performance liquid chromatography with fluorescence detection. Reduced glutathione (GSH) content was higher in unfertilized oocytes (8.50 +/- 0.29 pmol/egg) and penetrated eggs with a decondensed sperm nucleus (DSH eggs; 7.72 +/- 0.56 pmol/egg) than eggs at the pronuclear stage (PN eggs; 5.93 +/- 0.10 pmol/egg). The content of oxidised glutathione (GSSG) was not different among experimental groups (152.6 +/- 74.1 nmol/egg in unfertilized eggs, 146.0 +/- 50.0 nmol/egg in DSH eggs and 39.7 +/- 17.3 nmol/egg in PN eggs). The GSSG/GSH ratio did not change during fertilization. Although the reduced cysteinylglycine content of eggs did not change among experimental groups, the oxidised form of cysteinylglycine increased (p < 0.025) between sperm decondensation (6.9 +/- 1.5 nmol/egg in unfertilized oocytes and 10.1 +/- 2.1 nmol/egg in DSH eggs) and pronuclear formation (40.5 +/- 11.5 nmol/egg in PN eggs). Low contents of cystine were detected during fertilization but cysteine and gamma-glutamylcysteine were not detected in any treatment groups. These results demonstrate that GSH content in rat eggs decreases between sperm decondensation and pronuclear formation, probably due to the increased activity of gamma-glutamyl transpeptidase.

Animals↗
PubMed1999

Expression of interleukin-1 receptors in the later period of foetal thymic organ culture and during suspension culture of thymocytes from aged mice.

Interleukin-1 has been reported to be involved in thymocyte development by exerting a variety of effects on immature CD4-CD8- double-negative (DN) thymocytes. In contrast to the well-documented involvement of IL-1 in thymocyte development, expression of IL-1 receptors (IL-1R) on thymocytes has not been well demonstrated. In the present study, expression of IL-1R on the developing thymocytes was investigated. Although normal thymocytes barely express IL-1R, expression of IL-1R (type I) substantially increased at days 12-15 of foetal thymic organ culture (FTOC), with an increase of the DN subset. The CD4/CD8 profile of the IL-1R (type I)+ cells showed that these cells were mostly restricted to the DN and CD4+CD8+ subsets. Interestingly, in vitro culture of the thymocytes from an aged mouse, but not those from young adult or newborn mice, revealed similar results to those of FTOC. In addition, half of the IL-1R+ cells that increased in the later period of FTOC were gammadelta thymocytes. These results demonstrate IL-1R expression on thymocytes during ex vivo culture and suggest that IL-1R is expressed in a certain environment during normal thymocyte differentiation.

Aging↗
PubMed1999

Monoclonal antibodies to recombinant Der p 2, a major house dust mite allergen: specificity, epitope analysis and development of two-site capture ELISA.

House dust mite allergens have been well established as sensitizing agents that are important in the induction of allergic diseases. In order to analyze epitopes of the allergen and to develop a quantitative method of the allergen exposure, monoclonal antibodies against a recombinant Der p 2 (rDer p 2), one of the major allergens of Dermatophagoides pteronyssinus, were produced. Four monoclonal antibodies produced were species-specific and did not cross-react to the D. farinae crude extract. Two of the monoclonal antibodies were found to be IgG1 and the others were IgM. For the analysis of epitopes, a Der p 2 cDNA encoding 126 amino acids (aa) was dissected into three fragments with several overlapping peptides. A (aa residues 1-49), B (44-93), and C fragment (84-126). Three monoclonal antibodies showed reactivities to the recombinant B fragment and to the full-length rDer p 2, but one monoclonal antibody reacted only with the full-length rDer p 2. Two-site capture ELISA was developed using two different monoclonal antibodies for quantitating Der p 2 in house dust. The sensitivity limit was 4 ng/ml with rDer p 2 and 8 micrograms/ml with the D. pteronyssinus crude extract. The result suggested that the assay using monoclonal antibodies against rDer p 2 could be useful for the environmental studies and for the standardization of mite allergen extracts.

Animals↗