Biomedical subjects

S H Oh

Publications and source records attributed to S H Oh.

At least 19 recordsLinked to original sources

PubMed2006

MRI findings and spreading patterns of necrotizing external otitis: is a poor outcome predictable?

AIM: To evaluate spreading patterns of necrotizing external otitis (NEO) by magnetic resonance imaging (MRI) and to identify spreading patterns related to a poor outcome. MATERIALS AND METHODS: Fourteen patients with NEO were divided into good and poor outcome groups according to their final clinical outcomes. Initial MRI images were retrospectively reviewed for regional abnormalities, and follow-up MRI images were reviewed for ICA flow void abnormality and for the following five spreading patterns: medial, crossed, anterior, intracranial, and combined. The frequencies of the abnormal flow void or spreading patterns were compared between the good and poor response groups. RESULTS: Seven (50%) and seven (50%) patients were respectively allocated to the good and poor outcome groups. Retrocondylar fat infiltration was the most commonest finding on initial MRI images (93%). The frequencies of the abnormal flow void and spreading patterns in the good and poor groups, respectively, were: abnormal flow void, 0 and four (57%); anterior, two (29%) and three (43%); medial, six (86%) and seven (100%); crossed, six (86%) and seven (100%); intracranial middle cranial fossa, one (14%) and four (57%); intracranial posterior cranial fossa, four (57%) and six (86%); intracranial foramen magnum, one (14%) and six (86%). CONCLUSIONS: NEO almost always involves the retrocondylar fat and spreads via various pathways to extracranial or intracranial spaces. The presence of an abnormal flow void and intracranial dural enhancement, particularly in the middle cranial fossa and foramen magnum, may indicate a poor prognosis.

Aged↗

PubMed2006

Genetic parameters for various random regression models to describe total sperm cells per ejaculate over the reproductive lifetime of boars.

The objective of this study was to model the variances and covariances of total sperm cells per ejaculate (TSC) over the reproductive lifetime of AI boars. Data from boars (n = 834) selected for AI were provided by Smithfield Premium Genetics. The total numbers of records and animals were 19,629 and 1,736, respectively. Parameters were estimated for TSC by age of boar classification with a random regression model using the Simplex method and DxMRR procedures. The model included breed, collector, and year-season as fixed effects. Random effects were additive genetic, permanent environmental effect of boar, and residual. Observations were removed when the number of data at a given age of boar classification was < 10 records. Preliminary evaluations showed the best fit with fifth-order polynomials, indicating that the best model would have fifth-order fixed regression and fifth-order random regressions for animal and permanent environmental effects. Random regression models were fitted to evaluate all combinations of first- through seventh-order polynomial covariance functions. Goodness of fit for the models was tested using Akaike's Information Criterion and the Schwarz Criterion. The maximum log likelihood value was observed for sixth-, fifth-, and seventh-order polynomials for fixed, additive genetic, and permanent environmental effects, respectively. However, the best fit as determined by Akaike's Information Criterion and the Schwarz Criterion was by fitting sixth-, fourth-, and seventh-order polynomials; and fourth-, second-, and seventh-order polynomials for fixed, additive genetic, and permanent environmental effects, respectively. Heritability estimates for TSC ranged from 0.27 to 0.48 across age of boar classifications. In addition, heritability for TSC tended to increase with age of boar classification.

Age Factors↗

PubMed2006

Gamma radiation sensitivity of Enterobacter sakazakii in dehydrated powdered infant formula.

The observed Enterobacter sakazakii D10-values for tryptic soy broth and dehydrated powdered infant formula were 0.27 +/- 0.05 and 0.76 +/- 0.08 kGy, respectively. A decrease of approximately 3 log in the dehydrated powdered infant formula was obtained by irradiation with 3.0 kGy or rehydration with hot water at 80 degrees C. No recoverable bacteria were found in the powdered infant formula irradiated at 5.0 kGy and stored, either before or after rehydration. A radiation dose of up to 5.0 kGy had no marked effect on the sensory properties of the dehydrated powdered infant formula after rehydration and heating. Gamma radiation could potentially be used to inactivate E. sakazakii in dehydrated powdered infant formula; however, nutritional studies need to be conducted before the use of radiation can be recommended.

Colony Count, Microbial↗

PubMed2005

Ordered liquid aluminum at the interface with sapphire.

Understanding the nature of solid-liquid interfaces is important for many processes of technological interest, such as solidification, liquid-phase epitaxial growth, wetting, liquid-phase joining, crystal growth, and lubrication. Recent studies have reported on indirect evidence of density fluctuations at solid-liquid interfaces on the basis of x-ray scattering methods that have been complemented by atomistic simulations. We provide evidence for ordering of liquid atoms adjacent to an interface with a crystal, based on real-time high-temperature observations of alumina-aluminum solid-liquid interfaces at the atomic-length scale. In addition, crystal growth of alumina into liquid aluminum, facilitated by interfacial transport of oxygen from the microscope column, was observed in situ with the use of high-resolution transmission electron microscopy.

Journal Article↗

PubMed2005

Neuroprotection by extract of Petasites japonicus leaves, a traditional vegetable, against oxidative stress in brain of mice challenged with kainic acid.

BACKGROUND: Reactive oxygen radicals have been implicated in the pathophysiology of many neurologic disorders and brain dysfunctions. Kainic acid has been used as a model agent for the study of neurotoxicity of various excitatory amino acids, since it induces neuronal damage through excessive production of reactive oxygen species. Petasites japonicus MAX (butterbur), cultivated as culinary vegetables in Eastern Asia, contains various kinds of phenolic compounds as well as sesquiterpenes, such as petasin. In European countries, the extracts from roots of Petasites species have been used in the therapy of headache or asthma. AIM OF THE STUDY: The objective of our study is to examine the neuroprotective action of the Petasites japonicus MAX (butterbur) extract against oxidative damage in the brain of mice treated with kainic acid. METHODS: Male ICR mice, 6-8 weeks of age, were administered orally the butanol fraction from methanol extract of Petasites japonicus (BMP) or its subfraction (BMP-I or BMP-II) for 5 consecutive days. Thirty min after the final administration, the animals were challenged s. c. with kainic acid (45 mg/kg), and neurobehavioral activities were monitored. In addition, biomarkers of oxidative stress and neuronal loss in the hippocampus for the biochemical, neurobehavioral,morphological evaluations were analyzed 2 days after the kainic acid challenge. RESULTS: During 5-day treatment with BMP or BMP-1, the body weight gain was not significantly different from that of vehicle- treated control animals. Administration of kainic acid alone induced severe epileptiform seizures, causing a lethality of approximately 50%, and injuries of pyramidal cells in the hippocampus of mice which survived the challenge. Kainic acid exposure also resulted in a remarkable decrease in total glutathione level and glutathione peroxidase activity, and an increase in the thiobarbituric acid-reactive substance (TBARS) value in brain tissues. In comparison, coadministration with BMP (400 mg/kg) reduced the 54% lethality of mice, administered with kainic acid alone, to 25 % (P <0.05). Moreover, BMP at the same dose restored the levels of reduced glutathione and TBARS to control values (P <0.05). In further studies, BMP-I (200 mg/kg) ameliorated significantly (P <0.05) the kainic acid-induced behavioral signs, such as seizure activity, and all mice administered with BMP-I (200 mg/kg) survived the kainic acid toxicity. Consistent with the above, the administration with BMP-1 remarkably attenuated the neurobehavioral signs and neuronal loss in hippocampal CA1 and CA3 regions. CONCLUSION: On the basis of these results, the butanol fraction, especially BMP-I, of Petasites japonicus MAX extract is possibly suggested to be a functional agent to prevent oxidative damage in the brain of mice.

Administration, Oral↗

PubMed2005

A more persistent tolerance to islet allografts through bone marrow transplantation in minimal nonmyeloablative conditioning therapy.

INTRODUCTION: Islet transplantation is a therapeutic approach to prevent diabetes complications. However, the side effects of the required lifelong immunosuppressive regimens to prevent graft rejection restrict the impact of type 1 diabetes. One strategy to overcome these limitations is tolerance induction and graft acceptance through hematopoietic chimerism. In this study we investigated whether tolerance to major histocompatibility complex (MHC) and minor-disparate islet allografts could be induced by minimal nonmyeloablative conditioning and whether more persistent donor-specific islet allografts were accepted if the grafts were implanted with simultaneous bone marrow cells. METHODS: The donor and recipient mice were BALB/c(H-2(b)) and C57BL/6(H-2(d)), respectively. In group 1 streptozotocin-induced diabetic C57BL/6(H-2(d)) mice received only 500 islets of BALB/c(H-2(b)). Group 2 recipients conditioned with antilymphocyte serum, 100 cGy total body irradiation and cyclophosphamide were given islet cells of BALB/c(H-2(b)), but group 3 were simultaneously given 30 x 10(6) BALB/c(H-2(b)) mice BMCs and islet cells similar to group 2. RESULTS: We obtained 5% to 6% allogeneic donor chimerism and 60% graft survival at 80 days after islet transplantation in group 3. We observed lymphocyte infiltration around the islet without destruction of endocrine cells and the presence of strong insulin/glucagon-stained cells in group 3. CONCLUSION: This minimal nonmyeloablative conditioning therapy induced donor chimerism and immune tolerance between MHC- and minor-disparate (BALB/c-->C57BL/6) mice and long-term islet graft survival was obtained through cotransplantation of bone marrow cells.

Animals↗

PubMed2005

Pathogenesis of deep white matter medullary infarcts: a diffusion weighted magnetic resonance imaging study.

BACKGROUND AND PURPOSE: The pathogenesis of deep white matter medullary (WMM) artery infarcts remains controversial. To address this question, we analysed the stroke patterns of WMM infarcts using diffusion weighted magnetic resonance imaging (DWI) to detect embolic signals and investigate stroke subtypes according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classifications. METHODS: We identified WMM infarcts on DWI using templates to determine the subcortical vascular territories. We classified WMM infarcts into those with small artery disease (SAD), large artery disease (LAD), cardioembolism (CE), two or more aetiologies, or undetermined aetiology. Clinical course, risk factors, and cortical spotty lesions were compared. RESULTS: Of the 1420 consecutive patients, 103 (7.3%) met the criteria for WMM infarcts. The stroke subtypes were as follows: 65 (63.1%) patients with LAD, 18 (17.5%) with SAD, 12 (11.7%) with CE, four (3.9%) with two or more aetiologies, three (2.1%) with undetermined aetiology, and one (1.0%) with other determined aetiology. LAD (87.7%) or CE (83.3%) was significantly accompanied by cortical embolic signals as compared to SAD (0%, p<0.001). The LAD infarcts were larger and tended to be chain-like in shape. Ischaemic stroke recurrence was more common in strokes with cortical embolic signals than in those without embolic signals (18.9% v 0%, p = 0.009). CONCLUSIONS: In present study, the most common pathogenesis of WMM infarcts was LAD. Our study indicates that WMM infarcts accompanying cortical embolic signals warrant evaluation of the underlying embolic sources in the large artery or the heart.

Aged↗

PubMed2005

Effects of dissolved calcium and phosphorous on osteoblast responses.

The dissolution behavior of hydroxyapatite (HA) and its effect on the initial cellular response is of both fundamental and clinical importance. In this study, plasma-sprayed HA coatings were characterized by X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). Calcium (Ca) and inorganic phosphorous (Pi) ions released from plasma-sprayed HA coatings within 3 weeks were measured by flame atomic absorption and colorimetrically molybdenum blue complex, respectively. To investigate the effect of dissolution of HA coatings on osteoblast response, additional Ca and Pi were added into the cell culture media to simulate the dissolution concentrations. Human embryonic palatal mesenchyme cells, an osteoblast precursor cell line, were used to evaluate the biological responses to enhanced Ca and Pi media over 2 weeks. Osteoblast differentiation and mineralization were measured by alkaline phosphatase-specific assay and 1,25 (OH)2 vitamin D3 stimulated osteocalcin production. The coatings exhibited an HA-type structure. FTIR indicated the possible presence of carbonates on the coatings. A dissolution study indicated a continual increase in Ca and Pi over time. In the cell culture study, enhanced osteoblast differentiation occurred in the presence of additional Ca concentration in the cell culture media. However, additional Pi concentration in the cell culture media was suggested to slow down osteoblast differentiation and mineralization.

Calcium↗

PubMed2004

Changes of 2-deoxyglucose uptake in the rat auditory pathway after bilateral ablation of the cochlea.

It has been reported that the area of decreased glucose metabolism in the FDG-PET of prelingually deaf children correlates significantly with speech performance after cochlear implantation. In this study, we undertook to confirm changes of glucose metabolism in the cerebral cortex using an animal model with age-matching groups to completely exclude the influence of age differences between the deaf and normal-hearing groups. The cochlea was ablated bilaterally at a postnatal 10-14 days in the deaf groups; 3-4 deaf and normal rats were included at each time point at 1, 2, 4 and 8 weeks and 7 months after ablation. After injecting 2-deoxyglucose intraperitoneally, digitalized autoradiographic images were obtained, and analyzed by using two different methods; 3-dimensional voxel-wise statistical analysis and conventional 2-dimensional densitometry. The hypometabolic area analyzed using 3-dimensional analysis and the differences of optical density between normal and deaf as determined by densitometry were widest and most prominent between 4 and 8 weeks after ablation. Differences were not significant before 2 weeks or after 7 months after ablation. This result shows that the hypometabolic area becomes prominent after a critical period and it decreases as the duration of deafness increases. We believe that cross-modal plasticity may be the mechanism of changes in glucose metabolism and that this result reinforced the usefulness of evaluating hypometabolic area using FDG-PET in deaf children.

Animals↗

PubMed2004

The influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate-pMMA composite cement.

The objective of this study is to assess the influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate (CA)-polymethylmethacrylate (PMMA) composite cement exhibiting quick setting time ( < 15 min), low exothermic temperature (< 47 degrees C), and high compressive strength (> 100 MPa). The biocompatibility was measured by examining cytotoxicity tests such as the agar diffusion test with L929 cell line and the hemolysis test with fresh rabbit blood. To estimate the bioactivity of CA-PMMA composite cement, we determined hydroxyapatite (HAp) formation on the surface of composite cement in the simulated body (SBF) solution by using thin-film XRD, XPS, SEM, EPMA and ICP-AES. The results of biocompatibility tests indicated that all experimental compositions of this study had no cytotoxicity and no hemolysis so that there was no cytotoxicity with regard to non-reacted monomers (MMA and TEGDMA) and lithium fluoride. The results of bioactivity tests revealed that CA-PMMA composite cement without lithium fluoride did not form HAp on its surface after 60 days of soaking in the SBF. On the other hand, LiAl2(OH)7 . 2H2O and HAp were formed on the surface of CA-PMMA composite cement including 1.0% by weight of lithium fluoride after 7 and 15 days of soaking in the SBF, respectively. The 5 microm of LiAl2(OH)7 . 2H2O and HAp mixed layers were formed on the surface of specimen after 60 days of soaking in the SBF.

Acrylic Resins↗

PubMed2004

Evaluation of proximal tooth contact tightness at rest and during clenching.

The aims of this study were to develop a device for measuring the tightness of proximal tooth contact and to evaluate the proximal contact tightness using this device at rest and during clenching. Twenty young adult volunteers with healthy dentition participated in this experiment. The tightness of proximal tooth contact between the second premolar and the first molar of both the maxilla and the mandible was measured by pulling a stainless steel strip between them at rest, and at 20 and 50% clenching levels of maximum voluntary contraction of masseter muscles at intercuspal position. Proximal contact tightness increased as the clenching levels of both the maxilla and the mandible increased. At rest, proximal contact tightness was less in the maxilla than in the mandible, whereas during clenching it was less in the mandible. These results indicate that during clenching, the teeth are displaced and they contact appropriately with adjacent teeth, making it possible to exert sufficient occlusal force while maintaining the integrity of dental arches.

Adult↗

PubMed2004

Isolated middle cerebral artery disease: clinical and neuroradiological features depending on the pathogenesis.

BACKGROUND: Isolated atherosclerotic middle cerebral artery (MCA) disease is often difficult to differentiate from cardioembolic disease if intracranial atherosclerosis coexists with cardiac disease. OBJECTIVES: To evaluate whether clinical and neuroradiological features of isolated MCA disease differ according to the underlying aetiology. METHODS: Isolated MCA disease was defined as a unilateral angiographically occlusive lesion of the MCA on the symptomatic side without lesions of other intracranial or extracranial vessels. Patients with isolated MCA disease were divided into atherosclerotic and potentially cardioembolic, and the clinical, laboratory, and neuroradiological data analysed. RESULTS: Among the 850 consecutive patients with acute ischaemic stroke or transient ischaemic attack, 107 (12.6%) met the criteria for isolated MCA disease (76 with atherosclerotic disease and 31 with a potential source of cardiac embolism). Total anterior circulation infarcts were more common and baseline NIHSS score was higher in potentially embolic occlusions than in atherosclerotic disease (each p<0.001). While cortical infarcts and territorial infarcts were more common in the potential embolism group (p = 0.028 and p<0.001, respectively), subcortical border zone infarcts were more common in the atherosclerotic group (p<0.001). Multiple regression analysis showed that border zone infarcts and mild stroke were independently associated with atherosclerotic MCA disease, while territorial and cortical infarcts were associated with potential cardiac embolic disease. CONCLUSIONS: Clinical and neuroradiological characteristics can differentiate isolated atherosclerotic MCA disease from MCA disease associated with potential sources of cardiac embolism, and may reflect the differences in underlying pathogenesis.

Acute Disease↗

PubMed2004

Delayed hemolytic transfusion reaction due to anti-Fyb caused by a primary immune response: a case study and a review of the literature.

Delayed hemolytic transfusion reactions (DHTRs) usually occur between 3 and 14 days posttransfusion as a result of a secondary immune response, with a drop in Hb level, fever, jaundice, or hemoglobinuria. DHTRs caused by a primary immune response are particularly rare events, and only a few reports have been known. In this report, we describe an unusual case of a DHTR caused by anti-Fyb in a 42-year-old man, who had no prior history of transfusion. Although it seems to be a rare phenomenon, we suggest that DHTRs by a primary immune response may be considered even in the case of the patient who had typical evidence of hemolysis but who had no previous transfusion history.

Adult↗

PubMed2003

Delayed-onset pineal abscess following transsphenoidal surgery for pituitary adenoma: a case report.

A 41-year-old woman suffered fever, speech disturbance and confusion four months after transsphenoidal surgery for pituitary macroadenoma. Meanwhile, the patient had been well except for transient asymptomatic postoperative pneumocephalus without cerebrospinal fluid (CSF) rhinorrhoea. Brain computed tomographic scan revealed a peripherally enhancing pineal abscess which superimposed on a preexisting pineal cyst. CSF findings showed elevated leukocyte count and positive bacterial culture. Three weeks of intensive antibiotic therapy and surgical evacuation of the pineal abscess ensued. The patient showed restricted postoperative recovery with moderate hypothalamic dysfunction. A unique case of delayed-onset postoperative pineal abscess which complicates the preexisting asymptomatic pineal cyst is presented and the possible explanation for this is speculated with review of the available literatures.

Abscess↗

PubMed2003

Developmental hemispheric asymmetry of interregional metabolic correlation of the auditory cortex in deaf subjects.

The functional connectivity of the auditory cortex might be altered in deaf subjects due to the loss of auditory input. We studied the developmental changes of functional connectivity of the primary auditory cortex (A1) in deaf children, deaf adults, and normal hearing adults by examining interregional metabolic correlation with (18)F-FDG PET. The mean activity of FDG uptake in the cytoarchitectonically defined A1 region served as a covariate in the interregional and interhemispheric correlation analysis. A1 metabolic rate was correlated with that of the ipsilateral superior temporal lobe in both normal and deaf subjects. This correlated area was larger in deaf children than in deaf or normal hearing adults. Concerning the functional connectivity of A1, a hemispheric asymmetry was found in that the extent of interregional correlation was clearly larger in the right than in the left hemisphere. This asymmetry was particularly pronounced in the younger deaf children. Both extent and asymmetry of the functional connectivity of A1 subsided with age. Contrary to this, a correlation between the left and the right primary auditory cortices was absent in younger deaf children but became apparent as they grew older.

Adolescent↗

PubMed2003

Association of HLA-DR and type II collagen autoimmunity with Meniere's disease.

To investigate HLA-associated genetic susceptibility to Meniere's disease in relation to type II collagen (CII) autoimmunity status, HLA-DRB1 genotyping and ELISA measurement of anti-CII antibody were performed in 41 Korean patients with Meniere's disease. In the anti-CII positive subgroup (20%) of patients, the frequency of HLA-DRB1*0405 was significantly increased (uncorrected) compared with both controls (63% vs 16%) and anti-CII negative patients (63% vs 12%). In the anti-CII negative subgroup, HLA-DRB1*1201 was significantly increased (uncorrected) (27% vs 10%) and DRB1*13 was decreased (6% vs 24%) compared with controls; these alleles appeared to confer susceptibility and resistance to the development of the disease. Association of HLA-DRB1*0405 with anti-CII positive Meniere's disease in this study suggests that it shares a specific HLA-DR sequence, QRRAA, as a genetic susceptibility factor with the anti-CII positive rheumatoid arthritis. In conclusion, whilst type II collagen autoimmunity may have a partial role in Meniere's disease, different HLA-DR alleles may also be associated with either susceptibility or resistance to the development of the disease in relation to anti-CII antibody status.

Adult↗

PubMed2003

Misidentification of Aeromonas veronii biovar sobria as Vibrio alginolyticus by the Vitek system.

AIMS: To find the cause of misidentification of aeromonads when using the Vitek system. METHODS AND RESULTS: Two Aeromonas veronii biovar sobria isolates were misidentified as Vibrio alginolyticus by the Vitek system. Both strains' identification was confirmed by biochemical testing, API 20E/20NE kits and/or 16S RFLP analysis. Thirty-one known Aeromonas species were tested by the Vitek system using 0.45 and 0.85% saline in the suspension medium. It was not clear whether low salinity causes misidentification of Aeromonas species more frequently. CONCLUSIONS: The specified reaction time may be inappropriately short for some critical biochemical tests of some strains. An ingenious reading strategy regarding incubation time is necessary to improve identification of Aeromonas species by the Vitek system. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first report of misidentification of A. veronii biovar sobria as V. alginolyticus in the Vitek system.

Aeromonas↗

PubMed2003

Hepatoprotective and free radical scavenging effects of Nelumbo nucifera.

Ethanol extracts from Nelumbo nucifera (ENN) seeds were studied for possible antioxidative and hepatoprotective effects. Antioxidative effects were measured spectrophotometrically by reduction of 2,2'-Diphenyl-1-picrylhydrazyl (DPPH) radicals. Hepatoprotective effects were tested using carbon tetrachloride (CCl4) and aflatoxin B1 (AFB1)-induced hepatocyte toxicity models. ENN showed potent free radical scavenging effects with a median inhibition concentration of 6.49 microg/ml. Treatment of hepatocytes with ENN inhibited both the production of serum enzymes and cytotoxicity by CCl4. The genotoxic and cytotoxic effects of AFB1 were also inhibited by ENN in dose-dependent manners. These hepatoprotective effects of ENN against CCl4 and AFB1 might result from its potent antioxidative properties.

Aflatoxin B1↗