PubMed Health⌕ Search

Biomedical subjects

S C Park

Publications and source records attributed to S C Park.

At least 19 recordsLinked to original sources
PubMed1997

Experiences of epilepsy surgery in intractable seizures with past history of CNS infection.

We studied the clinical characteristics, location of epileptogenic regions, and the surgical outcomes in 18 patients with intractable epilepsy associated with previous CNS infections. All patients underwent an extensive presurgical evaluation and 11 patients had intracranial EEG monitoring. On the basis of presurgical evaluation, epileptic regions were localized to the mesial temporal (n = 12) and the neocortical (n = 6) regions. The age of the time of CNS infection was significantly younger and the latent period of non-febrile seizures after CNS infection was longer in patients with mesial temporal lobe epilepsy (MTLE). MRI showed hippocampal atrophy and hippocampal signal changes in 11 of 12 patients with MTLE. Among 6 patients with neocortical epilepsy (NE) 5 patients had normal MRI and one showed cerebral hemi-atrophy. Surgery was successful (class I & II) in all patients with MTLE, however, in the patients with neocortical epilepsy, seizure-free results were not achieved in any patients after resective surgery (6 patients) and only 2 patients achieved Class II outcomes after a second epilepsy surgery consisting of neocortical resection. Patients with MTLE after CNS infection were differentiated from the group of neocortical epilepsy by an earlier onset of CNS infection, a prolonged latent period and a higher frequency of meningitis. The characteristic pathology in this group was hippocampal sclerosis and the surgical result was excellent. Neocortical epilepsy following CNS infection usually had no focal lesion on MRI and was associated with a relatively poor surgical result. This study suggested that the surgical outcome was influenced by the type of epileptic syndromes rather than the etiology of seizures. The association of MTLE with the younger age of CNS infections and with meningitis more frequently suggested that the neocortical neurons during infancy or early childhood may be more resistant to the epileptogenesis, or that the CNS infections in patients with MTLE might be milder in severity to cause selective injuries to the hippocampal neurons during their vulnerable stage.

Adolescent↗
PubMed1997

Effect of the distraction rate on the activity of the osteoblast lineage in distraction osteogenesis of rat's tibia. Immunostaining study of the proliferating cell nuclear antigen, osteocalcin, and transglutaminase C.

The purpose of this study was to investigate kinetics of the osteoblast lineage in the periosteum and endosteum according to different distraction rates in distraction osteogenesis of rat's tibia. An osteotomy was performed on 144 rats at the proximal diaphysis of the left tibia. The lengthening process was started after a latency period of 3 days, with varying distraction rates of 0.25 mm (group I), 0.5 mm (group II), 0.75 mm (group III), 1.0 mm (group IV) and proceeded until a 3.5 mm length gain was achieved. The animals that had an osteotomy alone, without lengthening, served as a control (group V). Immunohistochemical staining of proliferating cell nuclear antigen (PCNA), osteocalcin, and transglutaminase C (TGase C) were done on the four animals in each group sacrificed at post-distraction days 1, 3, 5, 7, 14, and 28 in order to observe the temporal changes among the experimental and control groups. Also, in order to compare the staining rates at a given length gain among the groups, animals in each group were additionally sacrificed 2 days post-distraction in group II; 2 and 4 days in group III; and 1.5, 2 and 2.5 days in group IV. The results of the expression rates of PCNA, osteocalcin, and TGase C in each group were analyzed quantitatively. The immunohistochemical study on callotasis of rat's tibia revealed that the osteoblast lineage in the periosteum is more activated than that in the endosteum for proliferation and differentiation by distraction, suggesting that the periosteum plays a more important role in neoosteogenesis in the distraction gap. Daily distraction rates ranging from 0.25 mm to 0.75 mm in two increments is appropriate for successful distraction osteogenesis of rat's tibia, but the rate of 0.25 mm a day is significantly better than that of 0.75 mm as was made evident in the immunohistochemical observations.

Animals↗
PubMed1996

Change of glutathione S-transferases in the skin by ultraviolet B irradiation.

Glutathione S-transferases (GSTs) may play an important role in protecting skin from ultraviolet radiation (UVR). However, the study on the response of GST to UVR is limited at present. We have examined the effects of a single exposure to ultraviolet B (UVB) radiation on GST in cultured human keratinocytes and the epidermis of SKH/hr-1 hairless mice. We have also investigated the changes of skin GST by chronic irradiation of UVB on the hairless mice. Significant decreases in GST activities in vitro and in vivo were observed at 24 h after 30 and 50 mJ/cm2 UVB irradiation. Chronic UVB exposure also caused decrease in GST activities of the skin tissue. However, any changes in mRNA expression or protein amount of GST have not been observed by Northern blot analysis and Western blot analysis after 30 mJ/cm2 UVB irradiation in cultured human keratinocytes, which suggests that mRNA expression and protein amount of GST are not affected by UVB. These results suggest that UVB irradiation results in inhibitory effect on GST activity in the skin.

Animals↗
PubMed1996

Immunohistochemical evaluation of transglutaminase C in tumours of salivary glands.

Transglutaminase C (TGase C), a family of Ca(2+)-dependent enzymes and an essential component in the cross-linking of peptide bonds, has been found to be a marker of epithelial differentiation with a possible role in cellular apoptosis, extracellular matrix stabilisation and Ca2+ binding, thereby having a potential role in tumour growth, differentiation and invasive behaviour. The expression of TGase C was evaluated in normal human salivary glands and their neoplastic lesions which included pleomorphic adenoma (n = 30), Warthin's tumour (n = 5), adenoid cystic carcinoma (n = 10), acinic cell carcinoma (n = 5), mucoepidermoid carcinoma (n = 5) and control tissue specimens of normal oral mucosa and squamous cell carcinoma, using polyclonal antibody, the specificity of which was determined by Western blotting, generated by immunising rabbits with purified transglutaminase. The TGase C was observed in the epithelial cells in the control tissue specimens examined. Pleiomorphic adenoma revealed reaction products in luminal tumour cells, the non-luminal or modified myoepithelial cells and their plasmacytoid variants, squamous metaplastic cells and chondroid cells. Adenoid cystic carcinomas had tumour cells in the luminal cells of tubular and cribriform structures and the acinic cell carcinoma had from low to moderate immunoreactivity in the tumour cell component and a diffuse immunoreactivity in the stroma for TGase C. Mucoepidermoid carcinoma showed no reaction products in the mucous-producing cells, while intermediate and epidermoid cells had immunoreactivity in the cell cytoplasm. As the presence of TGase C in salivary gland tumours was confined to those tumour cells which form the predominant histomorphology in each tumour subtype, it may be suggested that these enzymes may have a potential role in the regulation of cellular function in neoplastic salivary tissues affecting tumour growth, differentiation and neoplastic behaviour.

Adenolymphoma↗
PubMed1996

Cis-acting elements essential for light regulation of the nuclear gene encoding the A subunit of chloroplast glyceraldehyde 3-phosphate dehydrogenase in Arabidopsis thaliana.

We report the characterization of cis-acting elements involved in light regulation of the nuclear gene (GapA) that encodes the A subunit of glyceraldehyde 3-phosphate dehydrogenase in Arabidopsis thaliana. Our previous deletion analyses indicate that the -277 to -195 upstream region of GapA is essential for light induction of the beta-glucuronidase reporter gene in transgenic tobacco (Nicotiana tabacum) plants. This region contains three direct repeats with the consensus sequence 5'-CAAATGAA(A/G)A-3' (Gap boxes). Our results show that 2-bp substitutions of the last four nucleotides (AA or GA) of the Gap boxes by CC abolish light induction of the beta-glucuronidase reporter gene in vivo and affect binding of the Gap box binding factor in vitro. We have also identified an additional cis-acting element, AE (Activation Element) box, that is involved in regulation of GapA. A combination of a Gap box trimer and an AE box dimer can confer light responsiveness of the cauliflower mosaic virus 35S promoter containing the -92 to +6 upstream sequence, whereas oligomers of Gap boxes or AE boxes alone cannot confer light responsiveness on the same promoter. These results suggest that Gap boxes and AE boxes function together as the light-responsive element of GapA.

Arabidopsis↗
PubMed1996

Comparative pharmacokinetics and tissue distribution of norfloxacin-glycine acetate in flounder, (Paralichthys olivaceus) at two different temperatures.

The pharmacokinetics of norfloxacin-glycine acetate (NFXGA), a newly formulated norfloxacin, was investigated in healthy flounders at two different seawater temperature (at 12 degrees C and 20 degrees C) varying concentrations (100 ppm and 10 ppm), using dipping administration. It was shown that the elimination half-life (T1/2) of norfloxacin at 20 degrees C (10 ppm: 13.95 +/- 1.18 hr, 100 ppm: 11.71 +/- 1.32 hr) was significantly shorter than that at 12 degrees C (10 ppm: 16.61 +/- 1.47 hr, 100 ppm: 16.32 +/- 1.19 hr) in flounders. Mean residence time (MRT) was calculated at 12 degrees C (10 ppm: 194.87 +/- 29.88 hr, 100 ppm: 1,222.37 +/- 161.45 hr) and 20 degrees C (10 ppm: 168.42 +/- 25.85, 100 ppm: 606.14 +/- 122.75 hr). Meanwhile, in the flounder tissue distribution of norfloxacin. It was shown that serum, muscle, kidney, and liver exhibited different elimination half-lives of norfloxacin.

Animals↗
PubMed1996

Effect of steroids and nonsteroidal anti-inflammatory agents on stromal wound healing following excimer laser keratectomy in rabbits.

BACKGROUND AND OBJECTIVE: The effect of topical corticosteroids and nonsteroidal anti-inflammatory drugs (NSAIDs) on stromal wound healing after excimer laser keratectomy was evaluated quantitatively. MATERIALS AND METHODS: Excimer laser keratectomy was performed in each eye of 75 rabbits and the animals were divided into five groups according to planned post-operative medications: group I, 0.1% dexamethasone; group II, 0.1% fluorometholone; group III, 0.03% flurbiprofen; group IV, 0.1% dexamethasone and 0.03% flurbiprofen; and control group V, balanced salt solution. All treatment regimens were instilled four times daily. After dichlorotriazinyl aminofluorescein (DTAF) or hematoxylin-eosin staining, the thickness of new collagen and keratocyte density were quantified by image analysis system. In addition, the ultrastructural alterations in stroma were examined by transmission electron microscopy. RESULTS: At four weeks, keratocyte density had peaked and new collagen identified in all groups. At 12 weeks, new collagen thickness and keratocyte density of the control were significantly different from that of each experimental group (P < 0.05). Transmission electron microscopy showed the activated keratocytes and extracellular matrixes deposition. At 12 weeks, the structural changes had much subsided in each experimental group but sustained in control. CONCLUSION: Topically applied corticosteroids and NSAIDs can modulate stromal wound healing after excimer laser keratectomy and the effect of dexamethasone, which can be evaluated by the quantitative analysis of the morphologic changes, is the most prominent.

Administration, Topical↗
PubMed1995

Differential expression of TIS21 and TIS1 genes in the various organs of Balb/c mice, thymic carcinoma tissues and human cancer cell lines.

As a part of a series of investigations on the functions of TIS21 and TIS1 genes, we measured in vivo 12-O-tetradecanoylphorbol-13-acetate (TPA) inducibility of primary response genes (TIS21, TIS8 and TIS1) in the Balb/c mice and the changes of TIS gene expression in thymic carcinoma tissues and A549 and NCIH69 human lung cancer cell lines. In vivo induction of the TIS genes (TIS21, -8 and -1) by intraperitoneal injection of TPA was dramatic only at the needle contact site, i.e. in the abdominal muscle, not in the thigh muscle. Expression of TIS21 and TIS1 in the Balb/c mice thymus, lung, stomach and spleen was very strong (Lim IK et al. 1994a), regardless of TPA injection. Thymic carcinoma tissues developed in SV40-T-antigen-containing transgenic mice did not express TIS21 and TIS1, and expressed TIS8 weakly. Interestingly, induction of TIS21 expression was obliterated in the human lung cancer cells; A549 cells completely lost the ability to express TIS21 after a combined treatment of TPA and cycloheximide. We also measured the induction of TIS genes by TPA and/or cycloheximide in Raw264.7 mouse macrophage cells and U937 human histiocytic lymphoma cells. However, the induction profile was quite different; repressed and deregulated expression in the U937 cells as compared to rapid and transient induction of TIS genes in the Raw264.7 cells. These data may suggest a repressed expression of TIS21 and TIS1 in the cancer tissues and cells derived from the organs that constitutively express TIS21 in mice and in human cancer cells.

Animals↗
PubMed1995

Expression of tenascin in hamster buccal pouch mucosa during experimental carcinogenesis.

Experimental carcinogenesis by topical application of 7,12-dimethylbenz(a)anthracene (DMBA) in hamster buccal pouch mucosa was evaluated for expression of tenascin, an extracellular matrix glycoprotein expressed at the epithelial-mesenchymal interface during embryonic and fetal development, wound healing and in the stroma of various neoplastic lesions, by using immunohistochemical methods. The buccal pouch mucosa in normal hamsters showed immunoreactive tenascin either as a linear delicate band or without reactivity at the immediate vicinity of the basement membrane. During carcinogenesis, in the second to fourth week of application of DMBA, the hyalinous changes in the submucosal connective tissue had a weak but diffuse immunoreactivity for tenascin. The hyperkeratinised and hyperplastic mucosa following 5 weeks of application of DMBA showed focal areas of enhanced expression in the vicinity of the basement membrane. Subsequently, specimens showing hyperplasia, dysplasia, carcinoma in situ and invasive carcinomas had comparatively more widespread stromal immunoreactivity where the extent of enhanced reactivity positively correlated with the advancing lesion. These results compared with the results of expression in human normal mucosa, leukoplakia and squamous cell carcinoma of the oral cavity (Shrestha et al., Oral Oncol, Eur J Cancer 1994, 30, 132-137) suggest that the expression of tenascin in experimental carcinogenesis of hamster buccal pouch mucosa, as a model, faithfully mimics the same in human oral mucosa.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

Intrathecal synthesis of immunoglobulin G and Mycobacterium tuberculosis-specific humoral immune response in tuberculous meningitis.

Local synthesis of immunoglobulin G (IgG) in the central nervous system was investigated in 10 patients with tuberculous meningitis (TBM), 15 patients with aseptic meningitis (AM), and 15 patients with pulmonary tuberculosis only (PTBO). The IgG synthesis rate for patients with TBM was 56.4 +/- 18.9 mg/day (mean +/- standard deviation), which was significantly higher than that for patients with AM (8.0 +/- 6.7 mg/day, P < 0.001) and that for patients with PTBO (7.5 +/- 4.4 mg/day, P < 0.001). Therefore, the increased IgG synthesis rate in the central nervous system provided supporting evidence for differentiating the diagnosis of TBM from that of AM (sensitivity, 100%; specificity, 83.3%). Simultaneous measurement by enzyme-linked immunosorbent assay of IgG seroreactivity to lipoarabinomannan and purified protein derivative antigens in cerebrospinal fluid (CSF) demonstrated seropositivity in all 6 patients with TBM, 4 of 15 patients with AM, and 4 of 10 patients with PBTO. All patients showing false-positive reactivity in CSF demonstrated seropositivity in sera and normal ranges for IgG synthesis rates in CSF. Also, the semiquantitive measurement of IgG antibody (Ab) titers in these patients demonstrated higher IgG Ab titers in serum than in CSF except for one patient with a highly elevated albumin quotient, suggesting a leaky blood-brain barrier. The results strongly suggested that the Mycobacterium tuberculosis-specific IgG Abs were diffusible through the blood-brain barrier, which addresses the pitfall of serological tests for the early diagnosis of TBM. The serological detection of IgG Abs to lipoarabinomannan and purified protein derivative antigens in CSF could be misleading in the presence of simultaneously elevated of IgG Abs in serum.

Antibodies, Bacterial↗
PubMed1995

Expression of transglutaminase C during the prenatal development of human submandibular glands.

The involvement of transglutaminase C (TGase C) in morphogenesis and cytodifferentiation during glandular tubule formation was addressed by immunolocalization of the protein at different stages of prenatal human submandibular gland development in 100 fetuses and 20 adult salivary glands. Immunocytochemical detection was carried out using a monospecific antibody to TGase C. The results showed TGase C reactivity in both acini and ducts early in development (from 10 to 14 weeks), followed by a marked increase in ductal activity and a decline in acinar activity up to 32 weeks. During the peak of reactivity at 25 to 32 weeks, staining was concentrated in the apical ends of the columnar cells. In the adult, staining was weakly and diffusely distributed in the striated and excretory ducts. Western blot analysis of the cellular extracts of pooled samples from various stages of salivary gland development showed a single strong band at 76 kDa early in development. This band became weaker after 32 weeks of prenatal development and in the adult. These findings of transient high expression of TGase C, which coincide with the development of tubulo-alveolar structure, suggest that TGase C may play a role in morphogenesis in human salivary gland development.

Adult↗
PubMed1995

Antibacterial substance produced by Streptococcus faecium under anaerobic culture.

A facultative anaerobe isolated from Korean domestic soil produced an antibacterial substance under strict anaerobic conditions. Based on the morphological and biochemical tests, and cellular fatty acid profiles, the anaerobe was identified as Streptococcus faecium. An antimicrobial compound produced from the S. faecium was identified as 3,7,12-trihydroxy-24-cholanic acid methylester on the basis of its physico-chemical analysis. This substance had potent antibacterial activities against a test organism harboring multiple antibiotic resistance markers, and a variety of pathogenic bacteria. The isolated S. faecium produced lactic acid as well as the antibiotic compound under the anaerobic conditions.

Anaerobiosis↗
PubMed1994

Selective inactivation of viruses in the presence of human platelets: UV sensitization with psoralen derivatives.

Inactivation of viruses in blood products requires that the method employed display selectivity in its action for viral elements while not affecting the biological entity of interest. Several methods have been developed for the treatment of human plasma or products derived from human plasma. An effective technique for the treatment of the cellular components of blood has been lacking, in part due to the inability to develop agents capable of selectively targeting viral agents in the milieu of cellular material. In this paper, we examine the behavior of a group of viral sensitizers designed to be added to cellular samples and be activated upon exposure to UVA light. Upon activation, these agents are capable of disrupting nucleic acids of the virus in a manner that renders them inactive for proliferation. The selectivity observed in this inactivation is determined by the chemical structure of the sensitizer, which can be varied to increase viral killing capacity while diminishing collateral damage to cellular and protein constituents.

Adenosine Diphosphate↗
PubMed1994

Transatrial lead placement for endocardial pacing in children.

Transvenous placement of endocardial leads in children may be difficult due to restrictions and complications of vascular access. We have placed endocardial leads from a transatrial approach in 5 children with various cardiac malformations. The usual surgical approach involved an anterolateral thoracotomy and, under fluoroscopic guidance, passage of the lead tip directly through the right atrial wall and across the tricuspid valve to the apex of the right ventricle. At a mean follow-up time of 23.2 months (range, 12.0 to 27.9 months), all patients have low thresholds for myocardial capture, and there have been no complications. We conclude that placement of endocardial leads by a transatrial approach provides an excellent alternative to an epicardial system in children destined for lifelong pacing.

Cardiac Pacing, Artificial↗
PubMed1994

Identification of a light-responsive region of the nuclear gene encoding the B subunit of chloroplast glyceraldehyde 3-phosphate dehydrogenase from Arabidopsis thaliana.

We report here the identification of a cis-acting region involved in light regulation of the nuclear gene (GapB) encoding the B subunit of chloroplast glyceraldehyde 3-phosphate dehydrogenase from Arabidopsis thaliana. Our results show that a 664-bp GapB promoter fragment is sufficient to confer light induction and organ-specific expression of the Escherichia coli beta-glucuronidase reporter gene (Gus) in transgenic tobacco (Nicotiana tabacum) plants. Deletion analysis indicates that the -261 to -173 upstream region of the GapB gene is essential for light induction. This region contains four direct repeats with the consensus sequence 5'-ATGAA(A/G)A-3' (Gap boxes). Deletion of all four repeats abolishes light induction completely. In addition, we have linked a 109-bp (-263 to -152) GapB upstream fragment containing the four direct repeats in two orientations to the -92 to +6 upstream sequence of the cauliflower mosaic virus 35S basal promoter. The resulting chimeric promoters are able to confer light induction and to enhance leaf-specific expression of the Gus reporter gene in transgenic tobacco plants. Based on these results we conclude that Gap boxes are essential for light regulation and organ-specific expression of the GapB gene in A. thaliana. Using gel mobility shift assays we have also identified a nuclear factor from tobacco that interacts with GapA and GapB DNA fragments containing these Gap boxes. Competition assays indicate that Gap boxes are the binding sites for this factor. Although this binding activity is present in nuclear extracts from leaves and roots of light-grown or dark-treated tobacco plants, the activity is less abundant in nuclear extracts prepared from leaves of dark-treated plants or from roots of greenhouse-grown plants. In addition, our data show that this binding factor is distinct from the GT-1 factor, which binds to Box II and Box III within the light-responsive element of the RbcS-3A gene of pea.

Arabidopsis↗
PubMed1994

Characterization of cis-acting elements in light regulation of the nuclear gene encoding the A subunit of chloroplast isozymes of glyceraldehyde-3-phosphate dehydrogenase from Arabidopsis thaliana.

We have characterized cis-acting elements involved in light regulation of the nuclear gene (GapA) encoding the A subunit of chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in Arabidopsis thaliana. Our results show that a 1.1-kb promoter fragment of the GapA gene is sufficient to confer light inducibility and organ specificity in transgenic Nicotiana tabacum (tobacco) plants, using the beta-glucuronidase gene of Escherichia coli as the reporter gene. Deletion analysis indicates that the -359 to -110 bp region of the GapA gene is necessary for light responsiveness. Within this region there are three copies of a decamer repeat (termed the Gap box) having the consensus sequence 5'-CAAATGAA(A/G)A-3', which has not been characterized in the promoter regions of other light-regulated genes. A deletion (to -247) producing loss of one copy of these elements from the GapA promoter reduces light induction by two- to threefold compared with a promoter deletion (to -359) with all three Gap boxes present, while deletion of all three Gap boxes (to -110) abolishes light induction completely. Gel mobility shift experiments using tobacco nuclei as the source of nuclear proteins show that GapA promoter fragments that contain these repeats bind strongly to a factor in the nuclear extract and that binding can be abolished by synthetic competitors consisting only of a monomer or dimer of the Gap box. Furthermore, a trimer, dimer, and monomer of the Gap box show binding activity and, like the authentic GapA promoter-derived probes, show binding activities that are correlated with Gap box copy number. These results strongly suggest that these repeats play important roles in light regulation of the GapA gene of A. thaliana.

Arabidopsis↗
PubMed1994

Modulation of transglutaminase expression in rat skeletal muscle by induction of atrophy and endurance training.

The persistence of muscle fiber number regardless of size reduction in muscle atrophy has not yet been fully explained. For the mechanism inherent in skeletal muscle tissues for preventing cellular death, the protective function of muscle tissue through transglutaminases has been tested, since the enzyme is responsible for structural stabilization and participates in signal transduction. In the present experiment, hindlimb suspension for two weeks caused a marked muscle atrophy in Wistar female rats. Comparison of muscle weight and histological analysis showed that suspension-induced atrophy in the hindlimb was more prominent in the soleus muscle, comprised mainly of type I fiber than that in the plantaris muscle of type II fibers. The immunohistochemical analysis with antitransglutaminase C antibody (anti TGase C Ab) showed that some atrophic bundles of soleus muscle were positively reacted with the antibody. The anti-TGase C Ab-reactive substances were observed to disappear significantly after endurance exercise, indicating their characteristic atrophy-dependency. The enzymatic analysis of transglutaminase showed the increase in activity in the atrophic soleus muscle tissue, compared with that in the normal or exercise-trained muscle tissues. From these results, the expression of TGase in the atrophic muscle is suggested to be the possible marker for muscle atrophy and its expression is probably related with the protective mechanism of the muscle tissue to prevent further cellular damage in the atrophic process.

Animals↗