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Biomedical subjects

S C Park

Publications and source records attributed to S C Park.

At least 37 records · Page 2Linked to original sources
PubMed2003

Muscle fibre size and capillarity in Korean diving women.

AIM: Effects of prolonged habitual cold-water immersion on fibre size and capillarity in vastus lateralis muscle were studied in human beings. The hypothesis tested in the present study was that cold acclimatized human skeletal muscle would have reduced muscle fibre size and higher capillarity, favouring the idea of efficacy of recruitment under cold environment. METHODS: Ten women breath-hold divers (BHDs) and 10 active women (controls CONs) participated in this study. Muscle biopsy was obtained from vastus lateralis and determined fibre type composition and capillary density. RESULTS: A major finding was that all BHDs revealed a markedly smaller cross-sectional area (CSA) in all fibre types than the CONs, or even than any other morphological data reported in previous investigations. Furthermore, mean CSA of type II fibre (range 1205-2766 microm2) was much smaller than type I fibre (2343-4327 microm2). The number of capillaries per fibre in different fibre types in the BHDs was higher than in the CONs (P < 0.001), and diffusional area was smaller in type II fibres than in type I fibres (P < 0.001). The BHDs and the CONs have similarity in the percentage of type I fibres, but type II fibre was predominant in both groups. Interestingly the proportion of type IIx fibre in the BHDs was higher (31%) than in the CONs (22%). No significant difference was found in the thigh circumference between the groups. CONCLUSION: The present study demonstrates that prolonged habitual cold-water immersion may induce a decrease in fibre size and an increase in capillarity in human skeletal muscle.

Adipose Tissue↗
PubMed2003

Solubilization of waste activated sludge by alkaline pretreatment and biochemical methane potential (BMP) tests for anaerobic co-digestion of municipal organic waste.

Biochemical methane potential (BMP) tests have been carried out to determine the anaerobic digestibility of the waste activated sludge (WAS) and the sludge pretreated by NaOH (PWAS). The optimal NaOH dosage was determined to be 45 meq NaOH/L. The maximum SCOD solubilization was 27.7, 31.4 and 38.3% at the temperatures of 25, 35 and 55 degrees C respectively after 4 hours reaction. The final methane yield of simulated food waste (SFW) was 430 ml CH4/g VS(added), and those of PWAS (25 degrees C), PWAS (35 degrees C) and PWAS (55 degrees C) was 274, 286 and 310 ml CH4/g VS(added) respectively after 20 days. The figures were 66%, 73% and 88% higher than that of WAS. The methane production in anaerobic co-digestion is considerably affected by the fraction of SFW and PWAS in the feed. The anaerobic digestibility of the feed mixture (SFW with PWAS) is higher than that of the feed mixture (SFW with WAS). Anaerobic co-digestion of food waste with the PWAS is found to be an attractive option to reduce the solid waste volume with improved methane recovery.

Bacteria, Anaerobic↗
PubMed2002

Ictal electrocorticographic findings related with surgical outcomes in nonlesional neocortical epilepsy.

PURPOSE: To characterize ictal electrocorticographic features related to surgical outcomes in nonlesional neocortical epilepsy (NE). METHODS: We analyzed 187 ictal electrocorticograms (ECoG) obtained from 18 patients who had undergone presurgical evaluation and subsequent neocortical resections (frontal: seven, parietal: one, occipital: four, multilobar: six). None of them had any MRI-detectable lesions. Various ECoG data sets recorded from eight patients who achieved a favorable surgical outcome (either seizure free or more than 90% reduction of seizure frequencies) were compared with that from ten patients with unfavorable outcome (less than 90% reduction of seizure frequencies) (follow up duration: 47+/-11 months). RESULTS: Reproducible ictal onset zone (IOZ) in recurrent seizures (P=0.013) and persistent ictal discharges in IOZ from the onset to the end of seizure (P=0.004) were found more frequently in the patients with good outcome. Ictal onset patterns consisting of low voltage fast or high amplitude beta spikes predicted a good surgical outcome while rhythmic sinusoidal activity or rhythmic spike/sharp waves of slow frequency were predictive of poor outcome (P=0.01). The ictal onset rhythm consisting of gamma or beta frequencies was more prevalent in the favorable group (P=0.015). CONCLUSIONS: The presence of stable ictal circuit suggested by the consistent earliest activation of specific electrodes in the repetitive seizures (reproducible IOZ) and the active participation of IOZ throughout the attack were valuable prognostic factors in addition to the morphology and frequency of ictal onset rhythm.

Adolescent↗
PubMed2001

Improvement of salt tolerance in transgenic potato plants by glyceraldehyde-3 phosphate dehydrogenase gene transfer.

In the previous experiment, we isolated and characterized glyceraldehyde-3-phosphate dehydrogenase (GPD) gene of the oyster mushroom, Pleurotus sajor-caju. Expression levels of the GPD gene in the mycelia of P sajor-caju was significantly increased by exposing the mycelia to abiotic stresses, such as salt, cold, heat, and drought. We also showed that GPD confers abiotic stress resistance when introduced into yeast cells. The survival rate of the transgenic yeast cell that harbored the GPD gene was significantly higher when the yeast cells were subjected to salt, cold, heat, and drought stresses, compared with the yeast that was transformed with the pYES2 vector alone. In order to investigate the functional role of the P. sajor-caju GPD gene in higher plant cells, the complete P. sajor-caju GPD cDNA was fused into the CaMV35S promoter and then introduced into potato plants. Putative potato transformants were screened by using PCR. Twenty-one transformants were further analyzed with RT-PCR to confirm the expression of P. sajor-caju GPD. A RT-PCR Southern blot analysis revealed that 12 transgenics induced the P. sajor-caju GPD gene expression. A bioassay of these transformants revealed that the P. sajor-caju GPD gene was enough to confer salt stress resistance in the potato plant cell system. Results showed that P. sajor-caju GPD, which was continuously expressed in transgenic potato plants under normal growing conditions, resulted in improved tolerance against salt loading.

Gene Expression↗
PubMed2001

Differential activation of mitogen-activated protein kinases by methyl methanesulfonate in the kidney of young and old rats.

Mitogen-activated protein kinases (MAPKs) play a critical role in the regulation of cell proliferation, differentiation and apoptosis. We evaluated MAPKs, extracellular signal-regulated kinases (ERKs), c-Jun NH2-terminal kinases (JNKs) and p38 MAPKs in the kidney of young and old rats in response to a direct-acting alkylating agent, methyl methanesulfonate (MMS). It is shown that the basal activity of ERKs was strongly down-regulated in the kidney of old rats compared to their young counterparts without a significant difference in the basal expression of ERKs. Upon treatment with MMS, ERKs were deactivated about 5-fold (P<0.05) in the kidney of young rats, whereas they were activated about 4-fold (P<0.01) in old rats. Strikingly, expression of JNKs was not detected in old animals, whereas it was clearly present and strongly activated after MMS treatment in the kidney of young animals. The basal activity of p38 significantly increased in the kidney of old rats as compared to young animals, whereas no difference in the basal expression of p38 was detected. After treatment with MMS, p38 was activated in the kidney of both young and old rats, where activation was dramatically stronger than in young animals. Taken together, these results demonstrate age-specific MAPKs signaling pathways in the rat kidney. The implications in age-related changes in susceptibility of the kidney to MMS-induced carcinogenesis are discussed.

Aging↗
PubMed2001

The protective role of HSP90 against 3-hydroxykynurenine-induced neuronal apoptosis.

3-hydroxykynurenine (3HK), an endogenous metabolite of tryptophan in the kynurenine pathway, is a potential neurotoxin in several neurodegenerative disorders. Stabilizing protein structure, heat shock proteins (HSPs) have diverse roles as molecular chaperones to mediate stress tolerance. In the present study, we investigated the possible protective role of HSPs against 3HK induced neuronal cell death. Here we report that 3HK induced in a dose- and time-dependent manner neuronal cell death in neuroblastoma SK-N-SH cells. The cell death showed characteristic apoptotic features such as cell shrinkage, plasma membrane blebbing, chromatin condensation, and nuclear condensation and fragmentation. Furthermore, SK-N-SN cells were protected from 3HK induced cytotoxicity by prior elevation of HSPs expression. Our results show that the protective effect was abolished by HSP90 anti-sense oligonucleotides while not by HSP27 and HSP70 anti-sense oligonucleotides. Also, our result shows that HSP90 effectively inhibits caspases activities leading to the apoptosis. These results suggest that 3HK induces apoptosis in neuroblastoma SK-N-SN cells and that HSP90 is major contributing protein component of protection against 3HK induced apoptosis.

Apoptosis↗
PubMed2001

Bacteremia due to quinolone-resistant Escherichia coli in a teaching hospital in South Korea.

Quinolone-resistant Escherichia coli (QREC) strains are being isolated with increasing frequency. From 1993 to 1998, 40 cases of QREC bacteremia were observed in a teaching hospital; 25 episodes (63.5%) were community-acquired. The incidence of QREC bacteremia increased steadily, from 6.7% to 24.6% during 5 years, and correlated with the significantly increased use of fluoroquinolones (P = .003, r = 0.98). When the 40 QREC bacteremic patients were compared with 80 patients with bacteremia due to quinolone-susceptible E. coli, prior fluoroquinolone use was the only independent risk factor for QREC bacteremia (P = .001). A high APACHE II score was the only independent risk factor for death. The rate of multidrug resistance of QREC was much higher (60%) than that of quinolone-susceptible isolates (13.8%). Pulsed-field gel electrophoresis patterns of these isolates were diverse. Therefore, the isolates revealed little evidence of clonal spread and may have emerged in direct response to the selective pressure exerted by prior fluoroquinolone use.

Anti-Bacterial Agents↗
PubMed2001

Two-point correlation functions of the diffusion-limited annihilation in one dimension.

Two-point density-density correlation functions for the diffusive binary reaction system A+A--> phi are obtained in one dimension via Monte Carlo simulation. The long-time behavior of these correlation functions clearly deviates from that of a recent analytical prediction of Bares and Mobilia [Phys. Rev. Lett. 83, 5214 (1999)]. An alternative expression for the asymptotic behavior is conjectured from numerical data.

Journal Article↗
PubMed2001

Selective left-lobe atrophy by nodularin treatment accompanied by reduced protein phosphatase 1/2A and increased peroxisome proliferation in rat liver.

The effect of nodularin on selective atrophy of left lobes in the liver was investigated in F344 rats. Nodularin was injected for 10 weeks from the third week of initiation with saline or N-nitrosodiethylamine (DEN), grouped as S/N and D/N, respectively. Nodularin significantly decreased weights of left (LL) and caudate (CL) lobes but increased right (RL) and middle (ML) lobes in S/N rats. Activity of protein phosphatases [types 1 (PPI) and 2A (PP2A)] was more severely reduced in S/N than D/N rats; moreover, in LL compared with RL of S/N rats, activity was significantly inhibited by nodularin treatment from week 4, which corresponded to 2 weeks after nodularin injection. However, nodularin significantly induced peroxisomal palmitoyl-CoA oxidase and cytochrome P-450 4A1 expression in S/N compared with D/N rats. An effect of nodularin on apoptosis was evident since expression of Bcl-Xs was clearly induced in LL of S/N rats as opposed to various inductions of Bcl-XL. However, Bcl-XL in RL was persistently induced, with undetectable Bcl-Xs expression. These results demonstrate biochemical evidence of selective atrophy of LL by inhibition of PP1 and PP2A activity, increase of peroxisomal enzymes and induction of Bcl-Xs expression, in contrast to proliferation of RL in rats treated with nodularin alone. However, nodularin endowed DEN-altered hepatocytes with regenerating power and concomitant restoration of phosphatase activity as well as persistent expression of Bcl-XL in D/N rats.

Alkylating Agents↗
PubMed2001

Immunobead RT-PCR versus regular RT-PCR amplification of CEA mRNA in peripheral blood.

PURPOSE: The reverse transcription polymerase chain reaction (RT-PCR) amplification of tumor-specific mRNA has been used for the detection of cancer cells in peripheral blood. More recently, an immunomagnetic isolation and reverse transcription polymerase chain reaction (immunobead RT-PCR) was developed which has reportedly significant advantages over the previous RT-PCR analysis. In our study, we compared these two methods using a model set of peripheral blood containing tumor cells under standardized conditions. MATERIAL AND METHODS: In order to compare the false positive rate, normal peripheral blood samples from five volunteers were analyzed by both methods. A model set of peripheral blood containing tumor cells was established by adding SNUC4 human colon cancer cells to peripheral blood collected from normal volunteers not showing any nonspecific bands upon electrophoresis of the PCR products. RT-PCR amplification of carcinoembryonic antigen (CEA) mRNA was done with total RNA and mRNA prepared from this model sample. In immunobead RT-PCR analysis, mRNA was prepared from the cells isolated with anti-CEA antibody-coated magnetic beads or anti-Ber-EP4 antibody-coated magnetic beads before the RT-PCR analysis. RESULT: The immunobead RT-PCR yielded no non-specific band, while the regular RT-PCR using total RNA did show non-specific band formation in all five samples. When mRNA rather than total RNA was used, nonspecific bands were formed in three of the five samples. Immunobead RT-PCR allowed the detection of 10(1) tumor cells in 1 ml of peripheral blood. The regular RT-PCR analysis had a detection limit of 10(2) tumor cells in 1 ml of peripheral blood. CONCLUSION: The immunobead RT-PCR proved to be more sensitive and specific than the regular RT-PCR at least in our model system.

Antibodies, Monoclonal↗
PubMed2001

Thymidine-dependent attenuation of the mitochondrial apoptotic pathway in adenosine-induced apoptosis of HL-60 cells.

OBJECTIVE: We previously reported that adenosine-induced apoptosis in HL-60 cells was attenuated by cotreating the cells with pyrimidine nucleosides. The mechanism involved in this adenosine-induced apoptosis by the differential supply of nucleosides is studied here with a particular focus on the regulation of apoptosis-associated mitochondrial events. METHODS: Time-dependent changes in the mitochondrial membrane potential (MMP) after treatment with adenosine and/or thymidine were monitored. RESULTS: The cells did not show any decrease of MMP level up to 2.5 h after 1 mM adenosine exposure, whereas cytochrome c release, caspase-9 and caspase-3 activity, and DNA fragmentation were already activated, suggesting that mitochondrial depolarization is not a prerequisite of other apoptosis-related mitochondrial events. In contrast, the translocation of Bax to mitochondria and the release of cytochrome c began within the first hour of adenosine treatment. CONCLUSION: Thus, it is believed that adenosine-induced apoptosis is mediated by the activation of the caspase cascade by cytochrome c release with concomitant increase of Bax in the mitochondria, which implies that the translocation of Bax might be a leading event in the adenosine-induced apoptosis. Moreover, we found that most of the apoptotic parameters in adenosine-induced cellular changes, such as translocation of Bax, the release of cytochrome c, and the consequent activation of caspase-9 and caspase-3, were attenuated by thymidine supplement, thus indicating that the sensing of a nucleoside or nucleotide balance might be an upstream event of cytochrome c release. Therefore, it can be concluded that thymidine can attenuate adenosine-induced apoptosis by modulating the earliest stage of the mitochondrial apoptotic pathway.

Adenosine↗
PubMed2001

Evaluation of rapid immunocapture assays for diagnosis of Plasmodium vivax in Korea.

The rapid immunocapture assays, OptiMal and ICT, were evaluated from 87 individuals for the diagnosis of malaria infections directly from whole blood. A total of 87 individuals was examined for malaria parasites by microscopic examination of Giemsa-stained blood smears, and 65 cases were positive for Plasmodium vivax by microscopy. Correspondingly, the OptiMal test identified malaria infection in 45 cases (69.2%) of microscopy positive cases. Of these, two cases were misinterpreted as Plasmodium falciparum, whereas ICT detected P. vivax infection in 29 (44.6%) patients. We would like to propose that rapid immuno capture assays are an easy method that can serve as a useful tool in addition to microscopy for the diagnosis of malaria, but sensitivity is not yet satisfactory for diagnosis of P. vivax in Korea.

Animals↗
PubMed2001

Radiologically confirmed de novo glioblastoma multiforme and hippocampal sclerosis associated with the first onset of nonconvulsive simple partial status epilepticus.

The authors report a case of an unusual progression of glioblastoma multiforme in the temporal lobe associated with the first onset of nonconvulsive simple partial status epilepticus (SPSE), a rare form of status epilepticus. The patient underwent a left temporal craniotomy and the tumor was removed. Concurrently, the hippocampus was removed as well. The pathological diagnosis of the tumor and the hippocampus were glioblastoma multiforme and hippocampal sclerosis. The patient's postoperative course was uneventful.

Brain Neoplasms↗
PubMed2001

A randomized comparison of prism adaptation and augmented surgery in the surgical management of esotropia associated with hypermetropia: one-year surgical outcomes.

OBJECTIVE: To compare motor and sensory 1-year surgical outcomes in patients with hypermetropic esotropia, managed with either augmented surgery based on the average of the near deviation with and without correction or preoperative prism adaptation. METHODS: Forty-three patients with hypermetropic esotropia without distance-near disparity entered a randomized prospective evaluation of augmented surgery (group A, 27 patients) versus prism adaptation (group P, 16 patients). The formula for augmenting the amount of the rectus muscle recession was based on the average of the near deviation with and without correction in group A and the prism-adapted angle of deviation in group P. During prism adaptation, 9 of 16 patients in group P responded to prism. Motor and sensory outcomes of the Worth 4-dot test at 6 and 0.33 m and the Titmus stereotest were evaluated 1, 3, 6, and 12 months after surgery. RESULTS: Postoperative deviations of 8 PD or less at distance were achieved in 24 of 27 patients (89%) of group A and in 7 of the remaining 8 patients (88%) of prism responders and in all 7 prism nonresponders (100%) in group P. No significant difference existed between groups A and P, as well as between the prism responders and prism nonresponders in group P in terms of near and distance deviation 1 year after surgery. The sensory outcomes improved over time in group A and prism responders. CONCLUSION: There were no significant differences in the surgical outcomes between each group. However, the small sample size may limit the power to detect any statistically significant differences.

Adaptation, Ocular↗
PubMed2001

Transglutaminase-mediated crosslinking of specific core histone subunits and cellular senescence.

We observed that the transglutaminase (tTGase) level and activity increased in aged rats and senescent primary fibroblasts, suggesting that the tTGase-mediated macromolecule crosslinking may play a mechanistic role during aging. Although preliminary, our in vitro experiment suggests that the target of tTGase is core histones: H2A:H2B and H3:H4 are specifically crosslinked by tTGase. On the basis of these data, we postulate that the changes of DNA metabolism in association with cellular aging may be ascribed primarily to the crosslinking of core histone subunits. Further speculation awaits substantive data showing increased histone crosslinking in senescent cells and also what crosslinked histones in various DNA metabolisms may imply. At the moment, present data are sufficient to propose that tTGase is a senescence marker and it may be primarily responsible for the phenotypes associated with cellular senescence.

Aging↗