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Biomedical subjects

S C Hong

Publications and source records attributed to S C Hong.

At least 37 records · Page 2Linked to original sources
PubMed2000

Surgical treatment of intractable epilepsy accompanying cortical dysplasia.

OBJECT: Surgical treatment of cortical dysplasia (CD) together with intractable seizures is challenging because both visualization and localization of the lesion are difficult, correlation with seizure foci requires comprehensive study, and the surgical outcomes reported thus far are unsatisfactory. The authors report their experience in the surgical treatment of CD classified according to a surgical point of view. METHODS: The definition of CD used in this study was a dysplastic lesion visible on magnetic resonance (MR) images or a lesion that, although not visible on MR images, was diagnosed as moderate-to-severe dysplasia by using pathological analysis. During the last 4.5 years, the authors treated 36 patients with intractable epilepsy accompanied by CD. They divided the 36 cases of CD into four characteristic groups: Group A, diffuse bilateral hemispheric dysplasia; Group B, diffuse lobar dysplasia; Group C, focal dysplasia; and Group D, a moderate to severe degree of CD with a normal appearance on MR images. All but one patient in Group C were monitored in the epilepsy monitoring unit by using subdural electrodes for seizure localization and functional mapping. The incidence of CD among a cohort of 291 patients who had undergone epilepsy surgery at the authors' center during the study period was 12.4%. The mean age of the 36 patients was 21.3 years and the mean age at seizure onset was 8.5 years. The mean follow-up period was 26 months. Twenty-six patients (72.2%) belonged to Engel Class I or II (20 and six, respectively). There were five cases in Group A, nine in Group B, nine in Group C, and 13 in Group D. Patients in Groups A and B were significantly younger at seizure onset and had significantly poorer surgical outcomes compared with patients in Groups C and D (p < 0.05). If outcome is compared on the basis of the extent of removal of CD, patients in whom CD was completely removed had significantly better outcomes than those in whom CD was only partially removed (p < 0.001). CONCLUSIONS: The authors conclude that intractable epilepsy accompanied by CD can be treated surgically using comprehensive preoperative approaches. Deliberate resective procedures aimed at complete removal of dysplastic tissue ensure excellent seizure control without permanent neurological deficit.

Adolescent↗
PubMed2000

Seroprevalence of toxoplasmosis in the residents of Cheju island, Korea.

This study was performed to evaluate the epidemiological status of toxoplasmosis among the residents of Cheju island. The sera of local students from 18 high schools (boys 2110, girls 2460) and those of adults (474 admitted to Cheju Chungang General Hospital) were collected and checked for the IgG antibody titers against Toxoplasma gondii. Serum samples collected from both the students and adults showed sero-positive rate of 5.5% and 12.9%, respectively. Although the rates were not significantly different between the sexes (5.4% for the boys and 5.5% for the girls attending school), the geographical difference showed a significant difference between the urban (4.6-6.9%) and rural areas (5.6-8.8%) (p < 0.05). Based on the high positive rates, it should be necessary to control toxoplasmosis in Cheju island.

Adolescent↗
PubMed1999

Spider mite allergy in apple-cultivating farmers: European red mite (Panonychus ulmi) and two-spotted spider mite (Tetranychus urticae) may be important allergens in the development of work-related asthma and rhinitis symptoms.

BACKGROUND: Recent investigations have suggested that the citrus red mite (Panonychus citri) is the most important allergen affecting citrus-cultivating farmers with asthma, allergic rhinitis, or both. OBJECTIVE: We sought to evaluate type I hypersensitivity to spider mites, particularly the European red mite (Panonychus ulmi) and the two-spotted spider mite (Tetranychus urticae), and to determine the relationship between hypersensitivity to spider mites and respiratory dysfunction. METHODS: We performed a cross-sectional survey. Questionnaires were given, and skin prick tests for 11 inhalant allergens common in Korea and 2 species of spider mites (European red mite and two-spotted spider mite) were performed in 725 apple-cultivating farmers in Korea. RESULTS: Results of skin prick tests in the apple farmers indicated that European red mite (23.2%) was the most common sensitizing allergen, followed by Tyrophagus putrescentiae (21.2%), two-spotted spider mite (16.6%), Dermatophagoides farinae (16.3%), D pteronyssinus (14.4%), cockroach (13.1%), and Hop Japanese (Humulus Japonicus) pollen (12.0%). Positive skin responses (mean wheal size >/=3 mm) to one or more of 13 inhalant allergens were found in 48.2% of farmers tested, whereas 40 subjects (8.6%) had an isolated skin response to the spider mites. Among 119 farmers with work-related asthmatic symptoms, the positive skin response rates to European red mite and two-spotted spider mite were 40.4% and 27.0%, respectively. These figures were significantly higher than those found among farmers without work-related symptoms (19.1% and 14.1%, respectively; P <.01). The prevalence of work-related asthma symptoms was higher in farmers with positive skin responses to spider mites than in those with negative skin responses to spider mites and those with positive skin responses to any allergen tested (31.4% vs 15.0% vs 21.0%, respectively; P <.05). CONCLUSION: Spider mites, particularly European red mite and 2-spotted spider mite, are common sensitizing allergens in apple-cultivating farmers. These spider mites may be important causative allergens in the development of work-related respiratory symptoms in these workers.

Administration, Inhalation↗
PubMed1999

White-matter change in mesial temporal sclerosis: correlation of MRI with PET, pathology, and clinical features.

PURPOSE: To assess the magnetic resonance imaging (MRI), positron emission tomography (PET), pathology, and clinical findings of patients with the MRI feature of white-matter change (WMC) in the anterior temporal lobe. METHODS: Fifty-six patients with pathologically proven mesial temporal sclerosis were included in this study. MRI and 18F-2-deoxyglucose-(FDG) PET images were obtained before surgery in all patients. The patients were divided into two groups according to the presence of WMC on their MRI. WMC consists of an indistinct gray-white matter demarcation and an increased signal intensity of the anterior temporal lobe on T2-weighted images. The two groups were then compared in terms of MRI, PET, pathology, and clinical features. RESULTS: The MRI feature of WMC was observed in 18 (32%) of the 56 patients. PET images of those patients revealed more severe hypometabolism of the ipsilateral temporal lobes (p< 0.05). In terms of histologic findings, larger numbers of heterotopic neurons were observed in the anterior temporal lobe white matter of these patients who also shared the following clinical features: earlier seizure onset, frequent history of febrile convulsions, and favorable surgical outcomes. CONCLUSIONS: The MRI feature of WMC is an additive sign for correct seizure lateralization and may be related to a favorable surgical outcome in patients with temporal lobe epilepsy.

Adolescent↗
PubMed1999

Antidepressant-induced bruxism successfully treated with gabapentin.

BACKGROUND: Symptoms consistent with bruxism are a common chief complaint in dental practice. The authors describe a case of bruxism likely induced by the antidepressant venlafaxine and successfully treated with gabapentin. CASE DESCRIPTION: A case of bruxism, anxiety, insomnia and tremor is reported in a man with bipolar disorder that developed a few days after he initiated venlafaxine therapy for depression. The patient's psychiatrist prescribed gabapentin for anxiety symptoms, and shortly thereafter the man experienced a complete resolution of the bruxism. CLINICAL IMPLICATIONS: On the basis of this case and the available literature, the authors conclude that bruxism secondary to antidepressant therapy may be common. Thus, dentists should inquire about the use of these medications in patients who have bruxism. Gabapentin may offer promise in the treatment of this condition.

Acetates↗
PubMed1998

Signalling initiated with CD4-TCR or TCR-TCR interactions: comparison of tyrosine phosphorylation patterns and CD45 effects.

Antigen-triggered response in T cells is mediated by the T cell receptor (TCR)/CD3-complex. This signalling, however, is modulated by a number of other surface molecules. Among the most important of these is the CD4/CD8 molecule which associates with the TCR/CD3-complex and binds to the MHC complex. The molecular mechanisms involved in interactions between TCR-TCR and TCR-CD4 are not fully understood. We have earlier described an experimental model that allows us to dissect signals involving CD4-TCR interactions and those involving TCR-TCR interactions using a mouse CD4-CD8- T cell hybridoma cell-line transfected either with the TCR from a mouse T-helper 2 cell-line (D10) alone or with both the TCR and the CD4 molecule. To further characterize these two different modes of signalling in T lymphocytes we have studied the tyrosine phosphorylation patterns resulting from these interactions. In addition, we have studied the modulatory effect of the CD45 molecule on these interactions. In contrast to some earlier reports, we found that both the patterns of induced tyrosine phosphorylation and the effects of CD45 modulation were essentially similar in the CD4-TCR and the TCR-TCR signal transduction cascades. The results are consistent with a purely synergistically amplifying function for CD4 on the TCR-mediated signalling.

Animals↗
PubMed1998

Relation between CT scan findings and human sense of smell.

Symptom questionnaires were obtained from 106 patients immediately before nasal and sinus computed tomography scans at the Johns Hopkins Outpatient Center. Their scans were analyzed by two otolaryngologists and three neuroradiologists by using a semiobjective rating system of the size and opacity of 36 anatomic areas. Patients estimated their own left and right sense of smell as excellent, diminished, or absent. Results of the data are as follows: (1) There is no correlation between smell ability and size of the nasal and sinus structures. This indicates that there is no gross effect of the bulging of sinuses into the nasal airway; (2) As a rule, opacity of only left-sided anatomic structures was correlated with both left and right sense of smell (p < 0.01). This suggests that our subjects were using their left smell receptors preferentially, to the exclusion of and in place of the right smell receptors; and (3) Total, not partial, opacity of the left olfactory cleft, frontal recess, or ethmoidal infundibulum was correlated with decreased sense of smell. This suggests that these anterior structures in the region of the olfactory cleft do affect airflow, but complete obstruction of these spaces is needed. Possible explanations for the effect of opacified sinuses on the sense of smell include (1) The presence of fluid or thickened mucosa in the sinuses may interfere with perceived olfactory ability by changing nasal airflow patterns or odorant access to receptors; (2) There may be olfactory receptors inside the sinuses; and (3) There may be a relation between the trigeminal receptors in the sinuses and the olfactory system.

Humans↗
PubMed1997

The orientation of a T cell receptor to its MHC class II:peptide ligands.

The TCR found on CD4 T cells recognizes peptides bound to self MHC class II molecules as well as non-self MHC class II molecules. We have used the receptor on a cloned T cell line called D10.G4.1 (D10) to perform a structure-function analysis of this interaction. The D10 T cell clone recognizes not only a peptide from conalbumin (CA-wt) bound to syngeneic I-Ak against which it was raised, but also the allogeneic MHC molecules I-A(b,v,p,q,d). In the present study, we show that residue 30 in complementarity-determining region 1 (CDR1) of the TCR alpha-chain interacts with the I-A alpha-chain at hvr2 (residues 52, 53, and 55). We also show that residue 51 in CDR2 of the TCR alpha-chain interacts with the peptide at peptide residue 2. Finally, we show that residue 29 in CDR1 of the TCR beta-chain affects recognition of the glutamic acid at residue 66 in the I-A beta-chain. These data suggest an orientation of TCR relative to its peptide:MHC class II ligands. We argue that this orientation will be shared by all CD4 TCRs, and that it is only subtly different from the common orientation proposed for receptors binding to MHC class I.

Animals↗
PubMed1997

A genetic animal model of human neocortical heterotopia associated with seizures.

Malformations of the human neocortex are commonly associated with developmental delays, mental retardation, and epilepsy. This study describes a novel neurologically mutant rat exhibiting a forebrain anomaly resembling the human neuronal migration disorder of double cortex. This mutant displays a telencephalic internal structural heterotopia (tish) that is inherited in an autosomal recessive manner. The bilateral heterotopia is prominent below the frontal and parietal neocortices but is rarely observed in temporal neocortex. Neurons in the heterotopia exhibit neocortical-like morphologies and send typical projections to subcortical sites; however, characteristic lamination and radial orientation are disturbed in the heterotopia. The period of neurogenesis during which cells in the heterotopia are generated is the same as in the normotopic neocortex; however, the cells in the heterotopia exhibit a "rim-to-core" neurogenetic pattern rather than the characteristic "inside-out" pattern observed in normotopic neocortex. Similar to the human syndrome of double cortex, some of the animals with the tish phenotype exhibit spontaneous recurrent electrographic and behavioral seizures. The tish rat is a unique neurological mutant that shares several features with a human cortical malformation associated with epilepsy. On the basis of its regional connectivity, histological composition, and period of neurogenesis, the heterotopic region in the tish rat is neocortical in nature. This neurological mutant represents a novel model system for investigating mechanisms of aberrant neocortical development and is likely to provide insights into the cellular and molecular events contributing to seizure development in dysplastic neocortex.

Animals↗
PubMed1997

Correlation between bone scan findings and collagenase activities in patients with breast cancer.

RATIONALE AND OBJECTIVES: This study correlates nuclear bone scan findings and measurements of type IV collagenases for the evaluation of bony metastasis in patients with proven breast cancer. METHODS: The authors retrospectively evaluated the final diagnosis of a bone scan and the results of an immunohistochemical staining for 92 kDa and 72 kDa type IV collagenases in, respectively, 30 and 30 patients with metastatic breast cancer, and, respectively, 27 and 26 patients with primary breast cancer. The immunohistochemical staining was performed with tissue specimens obtained from a primary or metastatic breast tumor lesion. The amounts of the enzyme were graded from 0 to 4 and scored by multiplication with the percentage of tumor cells. The confidence of bone scan interpretation also was scored from 1 to 5 with increasing probability. RESULTS: There was a significant difference in enzyme scores between patients with and without metastases. Patients with < 170 92 kDa (26 of 27), 72 kDa (26 of 26) type IV collagenase, showed no active bony, lung, or liver metastases. However, there were variable bone scan findings in patients with a > 200 enzyme score. CONCLUSIONS: Bone scan provides no additional benefit in breast cancer patients with a type IV collagenase score of < 170. A bone scan is necessary to confirm, localize, or followup bony metastases in patients with an enzyme score of > 200.

Bone Neoplasms↗
PubMed1997

Temporal changes in proton MRS metabolites after kainic acid-induced seizures in rat brain.

PURPOSE: In situ 1H-magnetic resonance spectroscopy (MRS) was used to study temporal metabolic changes in a rat model of temporal lobe epilepsy (TLE) by using kainic acid (KA). METHODS: Rat brains were scanned at the level of the hippocampal body for MRS measurements. Relative ratios of N-acetyl groups (NA: N-acetylaspartate and N-acetylaspartyl glutamate), choline, and lactate (Lac) over creatine (Cr) were calculated. RESULTS: NA/Cr ratios increased significantly during the ictal phase. During the postictal and interictal phases, the NA/Cr ratio decreased. There was a significant and prolonged increase of the lactate/Cr ratio in the hippocampi of rats that started 1 h after the onset of KA-induced seizure activity and persisted up to 24 h after the injection. The prolonged lactate/Cr increase in an area susceptible to neuronal damage (e.g., hippocampus) correlated with the onset of seizure activity but remained elevated thereafter. CONCLUSIONS: The ictal and early postictal increase in lactate ratios may reflect increased cellular activity and metabolism resulting from KA excitotoxicity. Assuming that the changes in NA/Cr ratios are due to NAA increase, we speculate that an activation of the N-acetylaspartylglutamate (NAAG) dipeptidase pathway may explain the ictal increase in NA/Cr ratios. The late postictal decrease in NA/Cr ratios is a reflection of KA-induced neuronal cell loss.

Animals↗
PubMed1996

Mild postischemic hypothermia limits cerebral injury following transient focal ischemia in rat neocortex.

Intraischemic mild hypothermia has been shown to attenuate cerebral infarction occurring after transient focal ischemia. In contrast, the capacity of mild hypothermia to provide a protective effect when administered postischemically has not been clearly defined for transient focal events such as occur in many types of stroke. The present study addressed this issue by investigating the influence of timing and duration of mild hypothermia on cerebral infarction in a rat model of reversible focal ischemia. Sprague-Dawley rats (n = 45) were subjected to 3 h of focal neocortical ischemia by occluding reversibly one middle cerebral artery and both carotid arteries. Mild hypothermia was established after reperfusion and maintained for brief (1 h) or prolonged (21 h) periods. Animals were sacrificed 24 or 48 h after ischemia. A significant reduction (32%) in the volume of infarction was obtained when hypothermia was established immediately after reperfusion and maintained for a prolonged (21 h) period. In contrast, immediate but brief (1 h) hypothermia did not reduce infarction volume. Delaying hypothermia until 30 min post reperfusion and maintaining it for 21 h reduced infarction volume by 22%; however, this effect did not achieve statistical significance. These findings demonstrate that mild postischemic hypothermia is capable of protecting against cerebral injury following transient focal ischemia but that prolonged hypothermia is required to achieve this effect. These findings are consistent with increasing evidence that the window of therapeutic opportunity after transient focal ischemia is rather brief and that critical mechanisms involved in this form of ischemic injury remain activated over a rather lengthy postischemic interval.

Animals↗
PubMed1996

Different superantigens interact with distinct sites in the Vbeta domain of a single T cell receptor.

CD4 T cell receptors (TCRs) recognize antigenic peptides presented by self major histocompatibility complex (MHC) class II molecules as well as non-self MHC class II molecules. The TCRs can also recognize endogenous retroviral gene products and bacterial toxins known collectively as superantigens (SAGs) that act mainly on the Vbeta gene segment-encoded portion of the Vbeta domain; most SAGs also require MHC II class for presentation. We have studied the interaction of the TCR from a well-characterized CD4 T cell line with SAGs by mutational analysis of its Vbeta domain. This appears to separate viral (v)SAG from bacterial (b)SAG recognition. T cells having a TCR with glycine to valine mutation in amino acid residue 51 (G51V) in complementarity determining region 2 of the TCR Vbeta domain fail to respond the bSAGs staphylococcal enterotoxin B (SEB), SEC1, SEC2, and SEC3, whereas they retain the ability to respond to non-self MHC class II molecules and to foreign peptides presented by self MHC class II molecules. It is interesting to note that T cells expressing mutations of both G51V and G53D of V beta regain the response to SEB and partially that to SEC1, but do not respond to SEC2, and SEC3, suggesting that different bacterial SAGs are viewed differently by the same TCR. These results are surprising, because it has been generally believed that SAG recognition by T cells is mediated exclusively by hypervariable region 4 on the exposed, lateral face of the TCR Vbeta domain. Response to the vSAG Mtv-7 was generated by mutation in Vbeta residue 24 (N24H), confirming previously published data. These data show that the vSAG Mtv-7 and bSAGs are recognized by different regions of the TCR Vbeta domain. In addition, various bSAGs are recognized differently by the same TCR. Thus, these mutational data, combined with the crystal structure of the TCR beta chain, provide evidence for distinct recognition sites for vSAG and bSAG.

Animals↗
PubMed1996

The specificity and orientation of a TCR to its peptide-MHC class II ligands.

A T cell-mediated immune response is mainly determined by the 3-5 aa residues that protrude upwards from a peptide bound to an MHC molecule. Alterations of these peptide residues can diminish, eliminate or radically alter the signal that the T cell receives through its T cell receptor (TCR). We have used peptide immunizations of normal mice and mice carrying alpha or beta chain TCR transgenes to identify three distinct peptide contact points. One, near the carboxyl terminus of the peptide, involves the beta chain CDR3 region; the second was centrally located and interacted with both the alpha and beta chain CDR3 loops; the third was near the amino terminus of the peptide, and affected V alpha gene usage, but not the structure of CDR3 of either TCR chain. Based on these results, we propose an orientation for the TCR of this cloned line and argue for its generality.

Amino Acid Sequence↗
PubMed1996

Mice lacking the MHC class II transactivator (CIITA) show tissue-specific impairment of MHC class II expression.

CIITA activates the expression of multiple genes involved in antigen presentation and it is believed to be required for both constitutive and IFN gamma-inducible expression of these genes. To understand the role of CIITA in vivo, we have used gene targeting to generate mice that lack CIITA. CIITA-deficient (-/-) mice do not express conventional MHC class II molecules on the surface of splenic B cells and dendritic cells. In addition, macrophages resident in the peritoneal cavity do not express MHC class II molecules upon IFN gamma stimulation nor do somatic tissues of mice injected with IFN gamma, in contrast with wild-type mice. The levels of Ii and H-2M gene transcripts are substantially decreased but absent in CIITA (-/-) mice. The transcription of nonconventional MHC class II genes is, however not affected by CIITA deficiency. A subset of thymic epithelial cells express MHC class II molecules. Nonetheless, very few mature CD4 T cells are present in the periphery of CIITA (-/-) mice despite MHC class II expression in the thymus. Consequently, CIITA(-/-) mice are impaired in T-dependent antigen responses and MHC class II-mediated allogeneic responses.

Animals↗