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S I Cho

Publications and source records attributed to S I Cho.

At least 19 recordsLinked to original sources
PubMed1998

Motor neurons and Schwann cells distinguish between synaptic and extrasynaptic isoforms of laminin.

Laminin is a major component of all basement membranes. However, its composition varies with location because there are numerous forms of each of the three chains (alpha, beta, and gamma) that together comprise this heterotrimeric molecule. In the neuromuscular system, motor neurons and Schwann cells encounter unique trimers of laminin at different sites. The question thus arises as to whether these local differences in laminin composition act to direct the behavior of these two classes of cells. To address this question, we compared the responses of cultured rat motor neurons and Schwann cells to three forms of rodent laminin purified in our laboratory: Laminin-1 (Lmn-1; alpha1beta1gamma1); Laminin-11 (Lmn-11), a synapse-specific isoform consisting of alpha5beta2gamma1 chains; and a third preparation, a mixture of three kinds of laminin (Lmn-2/4/8), that is enriched for the alpha2, alpha4, beta1, beta2, and gamma1 subunits. Schwann cells attached best to a substrate of Lmn-2/4/8 and showed the weakest adhesion on Lmn-11. Interestingly, no such difference was seen with motor neurons; all three substrates promoted neuronal adhesion, survival, and neurite initiation equally well. With longer time in culture, however, these embryonic motor neurons extended extremely long processes on Lmn-1 and on Lmn-2/4/8, while those on Lmn-11 bore shorter neurites with unusually large, flattened growth cones. These results demonstrate that the behavior of Schwann cells and motor neurons can be regulated directly by the local laminin composition. The precise geometric relationship of these cells at the neuromuscular junction may therefore reflect the unique composition of laminin at this synapse.

Animals↗
PubMed1998

Primary hyperaldosteronism causing posttransplantation hypertension: localization by adrenal vein sampling.

A 58 year-old man with end-stage renal disease who had received a cadaveric renal transplant presented with persistent hypertension and hypokalemia. Allograft renal artery stenosis, rejection, and cyclosporine effects were excluded. Hypokalemia persisted despite potassium supplementation and antihypertensive medications with hyperkalemic effects. The biochemical findings of primary hyperaldosteronism with a normal adrenal anatomy imaged by magnetic resonance imaging (MRI) necessitated adrenal vein sampling to lateralize a left adrenal adenoma. His hypokalemia was cured by the removal of the adenoma, and his blood pressure (BP) control was easily achieved with a less complex regimen of antihypertensives. We suggest that the concomitant existence of resistant hypokalemia and posttransplantation hypertension, especially in the cyclosporine era, should stimulate a search for hyperaldosteronism; once transplant renal artery stenosis has been excluded, the patient should be investigated for primary hyperaldosteronism. When imaging studies fail to show adrenal pathology, adrenal vein sampling will likely do so.

Adrenocortical Adenoma↗
PubMed1998

Association of petrochemical exposure with spontaneous abortion.

OBJECTIVES: To assess the association between petrochemical exposure and spontaneous abortion, a retrospective epidemiological study in a large petrochemical complex in Beijing, China was conducted. METHODS: Plant employment records identified 3105 women who were married, were 20-44 years of age, and had never smoked. Of those, 3070 women (98.8%) reported at least one pregnancy. From this group, 2853 (93%) of the women participated in the study. According to their plant employment record, about 57% of these women workers reported occupational exposure to petrochemicals during the first trimester of their pregnancy. Trained interviewers administered a standardised questionnaire to this group of women and their husbands, collecting information on reproductive history, pregnancy outcomes, employment history, occupational exposure, smoking habits, alcohol consumption, indoor air pollution, and demographic variables. The results from the womens' first pregnancies were analysed. RESULTS: There was a significantly increased risk of spontaneous abortion for women working in all of the production plants with frequent exposure to petrochemicals (8.8%; range of 5.8%-9.8%) compared with those working in nonchemical plants (2.2%; range of 0.0%-7.1%). Also, when a comparison was made between exposed and non-exposed groups within each plant, exposure to petrochemicals was consistently associated with an increased risk of spontaneous abortion. The overall odds ratio (OR) was 2.7 (95% confidence interval (95% CI) 1.8 to 3.9) after adjusting for potential confounders. When the analysis was performed with the exposure information obtained from the women' interview responses for (self reported) exposures, the estimated OR for spontaneous abortions was 2.9 (95% CI 2.0 to 4.0). The analysis was repeated by excluding those 452 women who provided inconsistent reports between recalled exposure and work history, and a comparable risk of spontaneous abortion (OR 2.9; 95% CI 2.0 to 4.4) was found. In analyses for exposure to specific chemicals, an increased risk of spontaneous abortion was found with exposure to most chemicals, and the results for benzene (OR 2.5; 95% CI 1.7 to 3.7), gasoline (OR 1.8; 95% CI 1.1 to 2.9), and hydrogen sulphide (OR 2.3; 95% CI 1.2 to 4.4) were significant. CONCLUSION: An increased risk of spontaneous abortion was found associated with the exposure to petrochemicals, including benzene, gasoline, and hydrogen sulphide.

Abortion, Spontaneous↗
PubMed1997

Reproducibility of nasal peak inspiratory flow among healthy adults: assessment of epidemiologic utility.

STUDY OBJECTIVE: To assess the reproducibility of nasal peak inspiratory flow (PIFn). PARTICIPANTS: Twelve healthy nonsmoking volunteers were studied. METHODS: Repeated measurements of PIFn and oral (PIFm) peak inspiratory flow were performed for 5 consecutive days. Two methods of inhalation were compared. In the residual volume (RV) method, the forced maximal inspiratory maneuver was initiated from the end of a maximal expiration, while in the functional residual capacity (FRC) method, the maneuver was from the end of a tidal breath. Reproducibility was assessed by the intraclass correlation coefficient. Time trend for the 5 days was assessed by random effect models adjusting for different baseline for each subject. RESULTS: The intraclass correlation coefficient (ICC) of PIFn was 0.89 (lower limit of one-sided 95% confidence interval is 0.80) by the RV method and 0.78 (95% lower limit is 0.63) by the FRC method, suggesting that both methods have good reproducibility. These were similar to the ICCs of PIFm by each method. The FRC method did not show a significant time trend for PIFn. The RV method had a small, but significant, decreasing time trend of a magnitude considered inconsequential for the purpose of epidemiologic study. CONCLUSION: PIFn, measured from either RV or from FRC, showed good reproducibility and can be employed in epidemiologic studies investigating the upper airways' response to air pollutant exposure. Further studies of the relationships between PIFn and signs and symptoms of rhinitis are needed to evaluate the utility of this test for clinical and epidemiologic use.

Adult↗
PubMed1996

Esophagorespiratory fistulae due to esophageal carcinoma: palliation with a covered Gianturco stent.

PURPOSE: To evaluate therapeutic effects and complications of a covered Gianturco stent for esophagorespiratory fistulae. MATERIALS AND METHODS: Of 95 patients with esophageal carcinomas, 10 had esophagorespiratory fistulae and were treated with a silicone-covered Gianturco stent. The authors retrospectively assessed patients' food intake capacity and delayed problem of the stent. RESULTS: All fistulae were occluded without immediate complications. Two patients could swallow all foods; four, most foods; three soft foods; and one, only liquids. Clinical problems occurred between 1 and 24 weeks in four patients: reopened fistula (n = 1), recurrent fistula (n = 1) (both patients were successfully treated with another esophageal stent), and dyspnea (n = 2) due to tracheal compression by stent and tracheal invasion by tumor (one patient was treated with a tracheal stent). CONCLUSION: A silicone-covered modified Gianturco stent is effective for palliation of esophagorespiratory fistulae caused by esophageal cancer. Simultaneous use of a tracheal stent is recommended for extrinsic tracheal narrowing by the proximal tip of the stent and invasion by tumor.

Bronchial Fistula↗
PubMed1995

Magnetic resonance angiography in the evaluation of living-related renal donors.

Live-donor kidney donation requires an accurate determination of renal arterial anatomy. Traditionally, conventional angiography has supplied this information. The present study was undertaken to determine the accuracy of magnetic resonance angiography (MRA) compared with conventional angiography (CA) in the evaluation of potential living renal donors. Fifteen potential living renal donors underwent both conventional angiography (midstream aortic injection) and three-dimensional phase contrast MRA. Two overlapping volumes of 64 slices (slice thickness 1.5 mm) were obtained in the axial plane to allow coverage from the celiac trunk to the aortic bifurcation. Conventional angiography demonstrated single renal arteries in 24 kidneys and multiple renal arteries in 6 kidneys. Magnetic resonance angiography demonstrated multiple renal arteries in 5 of the 6 kidneys. The sensitivity of MRA in determining kidneys with multiple renal arteries was 83% (5/6). One kidney with an accessory 2-mm polar artery was incorrectly identified as having a single renal artery by MRA. The overall accuracy of MRA in identifying the number of renal arteries was 97% (29/30). Fibromuscular dysplasia was demonstrated in 2 patients by CA, but was not visualized prospectively by MRA. Based on standard physician and hospital fees for each procedure, use of MRA alone would represent a cost savings of approximately $1900 over CA. Despite its minimally invasive and economic attractions, MRA does not achieve the level of accuracy required to replace CA in the evaluation of potential living kidney donors.

Female↗
PubMed1994

Differential effects of ginsenoside Rb1 and malonylginsenoside Rb1 on long-term potentiation in the dentate gyrus of rats.

Ginseng saponins are known to have various pharmacological actions on the central nervous system. In the present study, we investigated the effects of ginsenoside Rb1 (GRb1) and malonylginsenoside Rb1 (GRb1-m) on the induction of long-term potentiation (LTP) in the dentate gyrus using anesthetized rats. Injection (i.c.v.) of GRb1 did not affect the basal synaptic responses evoked by low-frequency test stimulation, but significantly attenuated the magnitude of LTP induced by strong tetanus (100 pulses at 100 Hz). The inhibitory effect of GRb1 depended on its doses (0.5-50 nmol, i.c.v.). On the other hand, GRb1-m did not affect the LTP induced by the strong tetanus, but facilitated the generation of LTP by the weak tetanus (20 pulses at 60 Hz) that produced only short-lasting potentiation in normal condition. The LTP-facilitating effect of GRb1-m was seen maximally at a dose of 5 nmol (i.c.v.) and diminished at a higher dose (50 nmol, i.c.v.). Since another ginseng saponin ginsenoside Rg1 did not affect the induction of LTP at all, the inhibition and facilitation of LTP induction are probably specific actions of GRb1 and GRb1-m, respectively. This is the first report providing direct evidence that ginseng saponins affect the activity-dependent synaptic plasticity in the brain.

Anesthesia↗
PubMed1994

The pentafraction of hydroxyethyl starch inhibits ischemia-induced compartment syndrome.

Pentafraction (PF), a solution of biodegradable hydroxyethyl starch macromolecules with molecular weights of 10 to 100 x 10(4) daltons, has been shown to minimize tissue edema by sealing interendothelial clefts at the capillary level. The effect of PF on ischemia-reperfusion-induced compartment syndrome was studied. Ten rabbits underwent bilateral femoral artery occlusion following ligation of branches from the terminal aorta to the popliteal artery. After 7 hours of ischemia, reperfusion was established with heparinized polyethylene shunts. Experimental animals (n = 5) received PF and control animals (n = 5) received normal saline (NS) as an intravenous infusion (30 mL/kg) for 1 hour, beginning 10 minutes after shunt placement. During reperfusion, anterior compartment pressure was continuously monitored in the left lower extremity. To quantitate oxidative metabolism, triphenyltetrazolium chloride (TTC) reduction (micrograms of TTC per milligram of protein) of tibialis anterior muscle from the right lower extremity was measured at femoral artery occlusion, 7 hours of ischemia, and 2 hours of reperfusion. In the NS group, anterior compartment pressure significantly increased from the end of the ischemic interval, 10.8 +/- 4.14 to 36.4 +/- 9.9 mmHg and 44.6 +/- 15.4 mmHg, after 1 and 2 hours of reperfusion (p < 0.007) compared with the PF group, which did not change significantly, 10.6 +/- 2.6 to 11.4 +/- 12.9 mmHg and 7.4 +/- 2.8 mmHg, after 1 and 2 hours of reperfusion (p < 0.67).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Malonylginsenoside Rb1 potentiates nerve growth factor (NGF)-induced neurite outgrowth of cultured chick embryonic dorsal root ganglia.

Effects of malonylginsenoside Rb1 (GRb1-m) isolated from dried root of Panax ginseng C. A. Meyer (Araliaceae) on neuronal survival and neurite outgrowth were compared with those of ginsenoside Rb1 (GRb1) using organ culture of chick embryonic dorsal root ganglia (DRG) and cell culture of DRG neurons. In the organ culture, nerve growth factor (NGF) showed neurite outgrowth promoting effect. GRb1-m (30 microM) significantly potentiated this NGF-induced neurite outgrowth with similar potency to that of GRb1 (30 microM). Low density cell culture of DRG neurons was employed to minimize the contribution of contaminating non-neuronal cells. NGF (10 ng/ml) prolonged duration of neuronal survival. Neither GRb1-m nor GRb1 (1-30 microM) changed the prolongation effect of NGF, nor did NGF show a significant effect on the neurite elongation and re-elongation after axotomy by laser beam irradiation. However, GRb1-m (10 microM) potentiated initial neurite elongation when co-treated with NGF. In the process of re-elongation of neurites, GRb1-m (1, 30 microM) also promoted it in the presence of NGF. These results suggest, first, that GRb1-m potentiates NGF-induced neurite outgrowth of chick embryonic DRGs and DRG neurons, but behaves in a slightly different manner from GRb1, and, second, that the effects of the two saponins may work primarily on neurons causing the potentiation of NGF-induced neurite outgrowth.

Animals↗
PubMed1994

Trial of intravesical versus extravesical ureteroneocystostomy in renal transplant recipients.

We carried out a trial to evaluate the complication rate of intravesical (LP) versus extravesical (Lich) ureteroneocystostomy in recipients of renal transplantation. Ureteric stenosis was the predominant complication in the LP technique, which was more difficult to correct. Complications by the Lich technique were urinary leaks, which were managed successfully by prolonged bladder drainage. We conclude that the Lich technique is simpler to perform and avoids the complication of ureteric stenosis, and should therefore be the procedure of choice for ureteric implantation in recipients of renal transplants.

Adult↗
PubMed1994

Deoxyspergualin--a novel immunosuppressant.

DSG appears to have a unique, although as yet undefined, mechanism of action and may be a useful immunosuppressive agent. Because DSG is effective in reducing preformed antibodies in the xenograft situation, it may have a significant advantage in ABO-incompatible grafts in transplant recipients with high panel-reactive antibodies. Most important, DSG may have a definitive role in immunosuppressive therapy for pancreatic grafts.

Animals↗