Biomedical subjects

J S Choi

Publications and source records attributed to J S Choi.

At least 19 recordsLinked to original sources

PubMed2006

Assessment of converting from intravenous to oral administration of cyclosporin A in pediatric allogeneic hematopoietic stem cell transplant recipients.

We studied the administration method during a transition period from continuous intravenous (i.v.) infusion to oral administration of cyclosporin A (CsA). Thirty-two pediatric hematopoietic stem cell transplant (HSCT) recipients, between the ages of 8 months and 15.6 years (median 7.1 years) participated in this study. The pharmacokinetic properties of CsA was evaluated during the transition period from i.v. to oral CsA. The daily oral dose of CsA was three times higher than the i.v. dose. Oral dosing began immediately after the continuous infusion was discontinued. Whole-blood CsA concentrations were measured by a monoclonal fluorescence polarization immunoassay (FPIA). The mean+/-s.d. value of bioavailability (F), maximum concentration (C(max)), half-life (t(1/2)) of CsA were 43.1+/-14.4%, 1135.3+/-340.6 ng/ml and 3.1+/-1.2 h, respectively. Mean clearance (CL)+/-s.d. was 480.9+/-103.7, 414.9+/-137.1 and 320+/-51.8 ml/h/kg in patients <20, 20-40 and >40 kg of body weight, respectively. The CsA CL of younger children was significantly greater than for older children (P=0.044). CsA trough levels were maintained within the therapeutic range throughout the transition period. Therefore, our findings suggest that the immediate administration of an oral formulation, after discontinuation of the continuous infusion, would be practical and effective for routine clinical use.

Administration, Oral↗

PubMed2006

Biofeedback therapy for rectal intussusception.

BACKGROUND: Surgery for isolated internal rectal intussusception is controversial due to high morbidity. Therefore, there is interest in other forms of treatment that are safe and effective. The aim of this study was to determine outcome and identify predictors for success of biofeedback therapy in patients with rectal intussusception. METHODS: We retrospectively evaluated the results of electromyography (EMG)-based biofeedback in 34 patients with rectal intussusception without any other major pelvic floor or colonic physiologic disorder. RESULTS: A total of 34 patients (7 men) had undergone at least 2 biofeedback sessions. The patients had a mean age of 68.5 years (SD=11.4 years). In the 27 patients with constipation, the frequency of weekly spontaneous bowel movements (mean+/-SD) was 2.0+/-6.8 before and 4.1+/-4.6 after biofeedback (p<0.05). The frequency of weekly assisted bowel movements decreased from 3.8+/-3.5 before to 1.5+/-2.2 after therapy (p<0.005). The number of patients who experienced incomplete evacuation decreased from 17 (63%) to 9 (33%) (p<0.05). Thirty-three percent of patients had complete resolution of the symptoms, 19% had partial improvement, and 48% had no improvement. Patients with constipation lasting less than nine years had a 78% success rate vs. 13% in patients who were constipated more than 9 years (p<0.01). In seven patients with incontinence, the frequency of daily incontinence episodes decreased from 1.0+/-0.7 before to 0.07+/-0.06 after biofeedback (p<0.05). The fecal incontinence score decreased from 13.1+/-4.2 before to 4.6+/-3.6 after treatment (p<0.005). Two patients (29%) were completely continent following biofeedback, 2 had partial improvement, and 3 (43%) had no significant improvement. There was no mortality in either group. CONCLUSIONS: Biofeedback is a safe and effective treatment option for constipation and fecal incontinence due to rectal intussusception in patients who are willing to complete the course of treatment. Long-standing constipation is less effectively cured by biofeedback.

Aged↗

PubMed2005

Methanolic extract of Pterocarpus santalinus induces apoptosis in HeLa cells.

Ptercarpus santalinus (Fabaceae) has been used as a folk remedy in Korea, and it has been shown to exhibit antiinflammations, antiulcers and anticancer effects. In this study, therefore, we report the cytotoxic activity and the mechanism of cell death exhibited by the methanol extract of Ptercarpus santalinus (MEPS) against human cervical adenocarcinoma cell line, HeLa. Treatment of HeLa cells with various concentrations of MEPS resulted in growth inhibition and induction of apoptosis in a dose-dependent manner as determined by cell viability, chromatin condensation, DNA fragmentation and sub-G1 phase accumulation. In Western blot analysis, apoptosis in the HeLa cells was associated with the release of cytochrome C from mitochondria into the cytosol, activation of caspases-3, -8, -9 and proteolytic cleavage of PARP. These results suggest that MEPS exhibits antiproliferative effect on HeLa cells via apoptosis, and it may be a potential candidate in field of anticancer drug discovery.

Apoptosis↗

PubMed2005

Prognostic values of KAI1 and survivin expression in an infiltrating ductal carcinoma of the breast.

AIMS: To investigate KAI1 and survivin expression in infiltrating ductal carcinomas, and to evaluate the relationship between clinicopathological factors and KAI1 and survivin expression levels in breast cancers. METHODS AND RESULTS: KAI and survivin expression levels were measured in 62 patients, using immunohistochemical staining. Western blot analysis was performed on eight frozen cases. DNA ploidy was determined by flow cytometry. The results of the KAI1 expression analyses were as follows: in 14 cases (22.6%) levels were preserved (++), in 30 cases (48.4%) levels were reduced (+), in 18 cases (29.0%) no KAI1 expression was detected, so these were designated 'lost' (-). Results of assessments of survivin expression were as follows: six cases (9.7%) were strong positive (++), 28 cases (45.15%) were positive (+), and 28 cases (45.15%) were negative. Survivin (p=0.0009) and KAI1 (p=0.0091) expression levels were directly correlated with survival rate. However, no significant difference was determined to exist between survivin and KAI1 expression levels and the clinicopathological factors. DNA ploidy did not correlate with survivin and KAI1 expression levels and survival rate. Four different groups, according to their survivin and KAI1 expression levels, correlated with the clinical stage and survival rate. CONCLUSION: KAI1 and survivin expression levels might be prognostic factors in breast cancers.

Adult↗

PubMed2005

Teratogen risk counselling by internet: a prospective cohort study.

Although the internet may play a role in providing proper teratogen-risk counselling for pregnant women, the experience with this type of service has not been reported. We aimed to compare the pregnancy outcome of women counselled by the internet to women that received typically in-clinic teratogen risk counselling in the clinic. In a prospective cohort design, 1,011 patients were counselled in the clinic and 235 patients were counselled via the internet. Teratogen risk counselling was provided according with the information obtained from medical literature and specialised software. Information about pregnancy outcome (delivery, spontaneous abortion, or termination of pregnancy and major malformations) was obtained from 903 (89.3%) patients from the clinic group and 141 (60%) from the internet group. The amount of alcohol, cigarettes smoked, and millirads of X-ray were greater ( p < 0.05) in patients counselled by internet than in clinic. The rate of deliveries, ongoing pregnancies, pregnancy terminations, and spontaneous abortions were similar between clinic and internet (chi2 = 1.32; p = 0.7). Of 498 babies born to mothers counselled in the clinic, major malformations were identified in 3.6%. Of 67 babies born to mothers counselled by internet, major malformations were present in 1.5% ( p = 0.6). Teratogen-risk counselling by internet and clinic seems to have a similar efficacy in pregnancy outcome.

Abnormalities, Drug-Induced↗

PubMed2005

Electron beam treatment of textile dyeing wastewater: operation of pilot plant and industrial plant construction.

A pilot plant for treating 1000 m3/day of dyeing wastewater with e-beam has been constructed and operated since 1998 in Daegu, Korea together with the biological treatment facility. The wastewater from various stages of the existing purification process has been treated with an electron beam in this plant, and it gave rise to elaborating the optimal technology of the electron beam treatment of wastewater with increased reliability for instant changes in the composition of wastewater. Installation of the e-beam pilot plant resulted in decolorizing and destructive oxidation of organic impurities in wastewater, appreciable reduction of chemical reagent consumption, in reduction of the treatment time, and in increase in the flow rate limit of existing facilities by 30-40%. Industrial plant for treating 10,000 m3/day each, based upon the pilot experimental result, is under construction and will be finished by 2005. This project is supported by the International Atomic Energy Agency (IAEA) and Korean Government.

Ammonia↗

PubMed2002

Secondary reconstruction of an ileal reservoir in patients with failed straight ileoanal pull-through: report of two cases.

The ileoanal reservoir is a widely accepted option for the treatment of mucosal ulcerative colitis and familial adenomatous polyposis. Function of an ileoanal anastomosis without the reservoir may be unacceptable. The aim of this study was to assess the technical feasibility of conversion of a straight ileoanal anastomosis to an ileoanal reservoir anastomosis. Two patients underwent straight ileoanal anastomosis and then underwent subsequent conversion to an ileoanal reservoir anastomosis. A 16-year-old girl with mucosal ulcerative colitis and a 38-year-old woman with familial adenomatous polyposis presented with 20-25 bowel movements per day and severe diarrheal-related symptoms within 11 months of ileoanal anastomosis. In each case, the anastomosis was reversed and an ileal Jpouch was fashioned and anastomosed to the dentate line; there was no postoperative morbidity. The 38-year-old patient reported 4-5 bowel movements per day without the need for any medication at 1-8 months after ileostomy closure. The 16-year-old patient is waiting ileostomy closure. In conclusion, it is technically possible to convert a straight ileoanal anastomosis to an ileoanal reservoir anastomosis with expectations of improvement in function.

Adenomatous Polyposis Coli↗

PubMed2002

Intraperitoneal gene delivery mediated by a novel cationic liposome in a peritoneal disseminated ovarian cancer model.

We have previously synthesized a new cationic liposome that displays high efficiency and low toxicity, 3 beta[l-ornithinamide-carbamoyl] cholesterol (O-Chol), using solid-phase synthesis. In this study, O-Chol was applied to in vitro and in vivo models of ovarian cancer. Intraperitoneal gene delivery for peritoneal disseminated ovarian cancer in nude mice was achieved using a stable chloramphenicol acetyl transferase (CAT)-expressing ovarian cancer cell line (OV-CA-2774/CAT), which allowed us to quantify the exact tumor burden of organs. When luciferase and beta-galactosidase genes were used as reporter genes, O-Chol showed better efficiency than other commercial transfection reagents such as lipofectin, lipofectAMINE, DC-Chol, and FuGENE 6, both in vitro and in vivo. Moreover, the transfection efficiency of this new cationic lipid reagent remained high in serum-containing medium and under serum-free conditions. Furthermore, in vivo transfection with O-Chol showed high levels of gene expression specific to peritoneal tumor cells. Consequently, the O-Chol:DNA lipoplex appears to offer potential advantages over other commercial transfection reagents because of (1) its higher level of gene expression in vitro and in vivo; (2) its reduced susceptibility to serum inhibition; and (3) its highly selective transfection into tumor cells. These results suggest that the O-Chol:DNA lipoplex is a promising tool in gene therapy for patients with peritoneal disseminated ovarian cancer.

Animals↗

PubMed2001

Transient expression of phospholipase D1 in developing rat hippocampus.

We investigated the distribution of phospholipase D1 (PLD1) protein in the developing rat hippocampus using an affinity-purified peptide antibody against PLD1. Immunoreactivity for PLD1 was first seen in some scattered cells in the hippocampus at embryonic day 18. At postnatal day 1 (P1), many PLD1 immunoreactive cells were observed in the CA1 and CA3 sectors, subiculum and the hilus of the dentate gyrus. During the first postnatal week, there was an abrupt increase of immunoreactive neurons in the hippocampus, and their number and intensity peaked at P7. During the second postnatal week, there was an abrupt decrease in the number of immunoreactive hippocampal neurons. By P14, no significant labeling was found in the hippocampus. These results corresponded well with those from Western blot analysis, suggesting that PLD1 may regulate the developmental processes of hippocampal neurons.

Animals↗

PubMed2001

Effect of sodium chloride on the gelation temperature, gel strength and bioadhesive force of poloxamer gels containing diclofenac sodium.

Liquid suppository systems composed of poloxamers and bioadhesive polymers were easy to administer to the anus and mucoadhesive to the rectal tissues without leakage after the dose. However, a liquid suppository system containing diclofenac sodium could not be developed using bioadhesive polymers, since the drug was precipitated in this preparation. To develop a liquid suppository system using sodium chloride instead of bioadhesive polymers, the physicochemical properties such as gelation temperature, gel strength and bioadhesive force of various formulations composed of diclofenac sodium, poloxamers and sodium chloride were investigated. The mixtures of P 407 (15%) and P 188 (15-20%) existed as a liquid at room temperature, but gelled at physiological temperature. Diclofenac sodium significantly increased the gelation temperature and weakened the gel strength and bioadhesive force, while sodium chloride did the opposite. Furthermore, the poloxamer gels with less than 1.0% of sodium chloride, in which the drug was not precipitated, were inserted into the rectum of rabbits without difficulty and leakage, and retained in the rectum of rats for at least 6 h. Our results suggested that a thermosensitive liquid suppository system with sodium chloride and poloxamers was a more physically stable and convenient rectal dosage form for diclofenac sodium.

Animals↗

PubMed2001

Effects of (-)-epigallocatechin-3-gallate, the main component of green tea, on the cloned rat brain Kv1.5 potassium channels.

The interaction of (-)-epigallocatechin-3-gallate (EGCG), the main component of green tea (Camellia sinensis), with rat brain Kv1.5 channels (rKv1.5) stably expressed in Chinese hamster ovary (CHO) cells was investigated using the whole-cell patch-clamp technique. EGCG inhibited rKv1.5 currents at +50 mV in a concentration-dependent manner, with an IC50 of 101.2+/-6.2 microM. Pretreatment with protein tyrosine kinase (PTK) inhibitors (10 microM genistein, 100 microM AG1296), a tyrosine phosphatase inhibitor (500 microM sodium orthovanadate), or a protein kinase C (PKC) inhibitor (10 microM chelerythrine) did not block the inhibitory effect of EGCG on rKv1.5. The inhibition of rKv1.5 by EGCG displayed voltage-independence over the full activation voltage range positive to +10 mV. EGCG had no effect on the midpoint potential or the slope factor for steady-state activation and inactivation. EGCG did not affect the ion selectivity of rKv1.5. The activation (at +50 mV) kinetics was significantly slowed by EGCG. During repolarization (at -40 mV), EGCG also slowed the deactivation of the tail currents, resulting in a crossover phenomenon. Reversal of inhibition was detected by the application of repetitive depolarizing pulses and of identical double pulses, especially during the early part of the activating pulse, in the presence of EGCG. EGCG-induced inhibition of rKv1.5 showed identical affinity between EGCG and the multiple closed states of rKv1.5. These results suggest that EGCG interacts directly with rKv1.5 channels. Furthermore, by analyzing the kinetics of the interaction between EGCG and rKv1.5, we conclude that the inhibition of rKv1.5 channels by EGCG includes at least two effects: EGCG preferentially binds to the channel in the closed state, and blocks the channel by pore occlusion while depolarization is maintained.

Animals↗

PubMed2001

Self-assembly and dynamics of [2]- and [3]rotaxanes with a dinuclear macrocycle containing reversible Os-N coordinate bonds.

With a dinuclear macrocycle 2 that contains weak reversible OsVI-N coordinate bonds, self-assembly and equilibrium dynamics of [2]- and [3]rotaxanes have been investigated. When the macrocycle 2 was mixed together with threads 4a-e, which all contain an adipamide station but different sizes of end groups, [2]pseudorotaxane- and rotaxane-like complexes were immediately formed with large association constants of >7 x 103M(-1) in CDCl3 at 298 K. Exchange dynamics, explored by 2D-EXSY experiments, suggest that assembly and disassembly of complexes occur through two distinct pathways, slipping or clipping, and this depends on the size of the end groups. The slipping pathway is predominant with smaller end groups that give pseudorotaxane-like complexes, while the clipping pathway is observed with larger end groups that yield rotaxane-like complexes. Under the same conditions, exchange barriers (deltaG++) were 14.3 kcalmol(-1) for 4a and 16.7 kcalmol(-1) for 4d, and indicate that the slipping process is at least one order of magnitude faster than the clipping process. Using threads 13a and 13b that contain two adipamide groups, more complicated systems have been investigated in which [2]rotaxane, [3]rotaxane, and free components are in equilibrium. Concentration- and temperature-dependent 1H NMR spectroscopic studies allowed the identification of all possible elements and the determination of their relative distributions in solution. For example, the relative distribution of the free components, [2]rotaxane, and [3]rotaxane are 30, 45, and 25 %, respectively, in a mixture of 2 (2mM) and 13a (2mM) in CDCl3 at 10 degrees C. However, [3]rotaxane exists nearly quantitatively in a mixture of 2 (4 mM) and 13 a (2 mM) in CDCl3 at a low temperature - 10 degrees C.

Journal Article↗

PubMed2001

Amygdalar nmda receptors are critical for the expression of multiple conditioned fear responses.

There is conflicting evidence regarding the issue of whether NMDA receptors in the basolateral amygdalar complex (BLA) are critically involved in the expression of conditioned fear. This matter was addressed by infusing the rat BLA with d,l-2-amino-5-phosphonovaleric acid (APV), a competitive NMDA receptor antagonist. APV infusion into the BLA was reported to block the expression of conditioned fear when measured by freezing but not when measured by fear-potentiated startle response to a loud noise. To examine this issue further, here we used multiple indices of conditioned fear, including analgesia, 22 kHz ultrasonic vocalization (USV), defecation, and freezing. Rats with bilateral BLA cannula implants underwent fear conditioning consisting of 10 tone-footshock pairings. Before context and tone fear-retention tests, animals received intra-BLA infusions with APV (2.5 microg/side) or artificial CSF. Both tone and context tests demonstrated that the expression of conditioned freezing, USV, defecation, and analgesia were significantly impaired by intra-amygdalar infusions of APV. In a second set of experiments, intra-BLA infusions of APV markedly impaired the normal expression of postshock fear responses during training, as measured by freezing, USV, and defecation. Immediate postshock fear expression was predictive of subsequent fear retention to the tone and context when the animals were not infused. These results are consistent with the hypothesis that amygdalar NMDA receptors participate in normal synaptic transmission and therefore the overall functioning of the amygdala.

2-Amino-5-phosphonovalerate↗

PubMed2001

ctr1, a gene involved in a signal transduction pathway of the gliding motility in the cyanobacterium Synechocystis sp. PCC 6803.

We generated random Tn5 mutations in Synechocystis sp. PCC 6803 in search for genes involved in the signal transduction cascade for the cyanobacterial gliding motility. One of the non-gliding Tn5 mutants, S1-105, had an insertional inactivation in the slr1044 gene encoding a putative methyl-accepting chemotaxis protein. Interposon mutation on the slr1044 (named ctr1) in the bacterium also eliminated gliding motility. In the interposon mutant, the expression of pilA1 was 5-fold decreased compared with that of wild-type and thick pili, that are believed to be the motor for gliding, could not be observed by an electron microscope. Therefore, we suggest that the Ctr1 protein functions as a transducer that regulates the expression of pilA1, and thus is required for the biogenesis of thick pili.

Amino Acid Sequence↗

PubMed2001

Complementarity of ecological goal functions.

This paper summarizes, in the framework of network environ analysis, a set of analyses of energy-matter flow and storage in steady-state systems. The network perspective is used to codify and unify ten ecological orientors or extremal principles: maximum power (Lotka), maximum storage (Jørgensen-Mejer), maximum empower and emergy (Odum), maximum ascendency (Ulanowicz), maximum dissipation (Schneider-Kay), maximum cycling (Morowitz), maximum residence time (Cheslak-Lamarra), minimum specific dissipation (Onsager, Prigogine), and minimum empower to exergy ratio (Bastianoni-Marchettini). We show that, seen in this framework, these seemingly disparate extrema are all mutually consistent, suggesting a common pattern for ecosystem development. This pattern unfolds in the network organization of systems.

Animals↗

PubMed2001

Reproducibility of colonic transit study in patients with chronic constipation.

PURPOSE: Major therapeutic decisions are rendered based on a single colonic transit study. Therefore, the aim of this study was to assess the reproducibility of colonic transit time in patients with chronic constipation. MATERIALS AND METHODS: Fifty-one patients with chronic idiopathic constipation were randomly selected to undergo two separate colonic transit tests. All clinical conditions, methodology, and patients' instructions were identical on both occasions. The gamma rate (linear correlation analysis) was undertaken between the first and second colonic transit times. Groups were divided according to the diagnoses of colonic inertia (slow-transit constipation), paradoxical puborectalis contraction, and chronic idiopathic constipation (normal-transit constipation). RESULTS: In 35 of 51 patients (69 percent), the results were identical between the two studies; however, in 16 patients (31 percent), the results were disparate (gamma correlation coefficient = 0.53; P < 0.01). The specific correlation coefficients for patients with colonic inertia, paradoxical puborectalis contraction, and chronic idiopathic constipation were 0.12, 0.21, and 0.60 (P < 0.01), respectively. Moreover, the success rate of colectomy for colonic inertia was significantly higher in patients who underwent a repeat transit study confirming inertia than in patients who underwent colectomy based on a single study. CONCLUSIONS: Overall, colonic transit time is reproducible in patients with chronic constipation. The correlation coefficient is best for patients with idiopathic constipation and worst for patients with colonic inertia. This new finding suggests that suboptimal surgical outcome may be attributable to inaccurate diagnosis. Because of this poor correlation coefficient, in patients with colonic inertia, consideration should be given to repeating the colonic transit study before colectomy to help secure the diagnosis and improve outcome.

Adult↗

PubMed2001

Pharmacokinetics of diltiazem and its major metabolite, deacetyidiltiazem after oral administration of diltiazem in mild and medium folate-induced renal failure rabbits.

The pharmacokinetic changes of diltiazem (DTZ) and its main metabolite, deacetyldiltiazem (DAD) were studied after oral administration of DTZ to normal rabbits and mild and medium folate-induced renal failure rabbits. DTZ 10 mg/kg was given to the rabbits either orally (n=6). Plasma concentrations of DTZ and DAD were determined by a high performance liquid chromatography assay. The area under the plasma concentration-time curves (AUC) and maximum plasma concentration (Cmax) of DTZ were significantly increased in mild and medium folate-induced renal failure rabbits. The metabolite ratio of the DTZ to DAD were significantly decreased in mild and medium folate-induced renal failure rabbits. The volume of distribution (Vd) and total body clearance (CLt) of DTZ were significantly decreased in mild and medium folate-induced renal failure rabbits. The elimination rate constant (beta) of DTZ was significantly decreased in folate-induced renal failure rabbits, but that of DAD was significantly increased. These findings suggest that the hepatic metabolism of DTZ was inhibited and the Vd, CLt and beta of DTZ were significantly decreased in mild and medium folate-induced renal failure rabbits.

Acute Kidney Injury↗

PubMed2001

Circadian changes in pharmacokinetics of sulfamethoxazole administered orally to rabbits.

Circadian variations of sulfamethoxazole pharmacokinetics were studied after a single oral administration of sulfamethoxazole, 50 mg/kg, to rabbits at 09:00 (a.m.) and 22:00 (p.m.). The profiles of plasma sulfamethoxazole concentration showed from 6 h to 24 h significant statistical difference (p<0.05) between 09:00 and 22:00. The half-life (t(1/2)) was significantly shorter in the morning (11.2 +/- 3.2 h) when compared to the nighttime (15.4 +/- 3.5 h) (p< 0.05). The AUC was significantly decreased in the morning (1325 +/- 264 microg/ml x h) than that in the nighttime (2059 +/- 379 microg/ml x h) (p<0.05). Total body clearance (CLt) was significantly higher when sulfamethoxazole was given in the morning (6.65 +/- 0.23 ml/min) versus in the nighttime (4.28 +/- 0.20 ml/min) (p<0.05).

Animals↗