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Biomedical subjects

J H Song

Publications and source records attributed to J H Song.

At least 109 records · Page 6Linked to original sources
PubMed1996

The effects of the muscle relaxant, CS-722, on synaptic activity of cultured neurones.

1. The pharmacological properties of the centrally acting muscle relaxant, CS-722, were studied in cultured hippocampal cells and dorsal root ganglion cells of the rat using the whole-cell variation of the patch clamp technique. 2. CS-722 inhibited the occurrence of spontaneous excitatory and inhibitory postsynaptic currents in hippocampal neurones at concentrations of 100-300 microM, but had no effect on postsynaptic currents evoked by the application of glycine, gamma-aminobutyric acid, glutamate or N-methyl-D-aspartate. 3. CS-722 reduced voltage-gated sodium currents, while shifting the sodium channel inactivation curve to more negative membrane potentials. This effect is similar to that reported for local anaesthetics. Voltage-gated potassium currents were decreased by CS-722 by approximately 20%, whereas voltage-activated calcium currents were inhibited by about 25%. 4. CS-722 inhibited evoked inhibitory postsynaptic currents. However, the spontaneous quantal release of inhibitory transmitter was not affected. 5. The inhibitory effect of CS-722 on spontaneous inhibitory postsynaptic currents and excitatory postsynaptic currents in hippocampal cultures probably results from an inhibition of both sodium and calcium currents. This inhibitory effect is likely to be amplified in polysynaptic neuronal circuits.

Anesthetics↗
PubMed1996

Vertex epidural hematomas: considerations in the MRI era.

Two cases of vertex epidural hematomas are described to illustrate their unique diagnostic and treatment problems. Due to its specific location, a correct diagnosis of the intracranial hematoma was delayed in the first case. Quantitative analysis of the hematoma volume was performed in the second case. We would like to emphasize the usefulness of the magnetic resonance imaging and quantitative analysis of vertex epidural hematoma in choosing treatment options in such patients.

Adult↗
PubMed1996

Modulation of sodium channels of rat cerebellar Purkinje neurons by the pyrethroid tetramethrin.

The pyrethroid insecticides are known to slow the kinetics of the activation and inactivation gates of sodium channels. This results in prolonged openings of individual sodium channels and prolonged flow of whole-cell sodium current, which in turn cause hyperexcitation in animals. The aim of the present study was to solve three important remaining questions. First, the percentages of the sodium channels modified by the pyrethroid tetramethrin were measured and compared with the threshold concentration to initiate repetitive discharges in rat cerebellar Purkinje neurons. Tetramethrin at 0.1 microM modified only 0.6% of the sodium channels and generated repetitive afterdischarges. Thus, the pyrethroid toxicity is greatly amplified from the sodium channel to the whole animal. The pyrethroid sensitivity of Purkinje neuron sodium channels was lower than that of invertebrate sodium channels by a factor of > or = 10. Chloramine-T at 200 microM removed the sodium channel inactivation and increased the percentage of sodium channel modification by tetramethrin through open channel modification. Second, temperature had a profound effect on the ability of tetramethrin to cause repetitive afterdischarges; at 0.1 to 0.3 microM tetramethrin, repetitive discharges were induced at l5 degrees C and 20 degrees C, but this effect subsided at 25 degrees C to 35 degrees C. This negative temperature dependence could be explained by an increase in charge movement during slow tail current as temperature was lowered. The Q10 value for the charge movement during tail current was 0.22 between 20 degrees C and 30 degrees C. Third, the selective toxicity of pyrethroids between mammals and insects could be explained quantitatively on the basis of sodium channel factors that include temperature dependence, intrinsic sensitivity and recovery rate and detoxication factors.

Animals↗
PubMed1995

Comparative study of efficacy and safety of low-dose diltiazem or betaxolol in combination with digoxin to control ventricular rate in chronic atrial fibrillation: randomized crossover study.

BACKGROUND: The combination therapy of low-dose diltiazem or bexatolol with digoxin can be a useful adjunct for achieving heart rate control with minimal side effects. But there has not been a study including patients with impaired left ventricular function and evaluating whether the beneficial effects of medication will be maintained during a follow-up period. OBJECTIVES: The purpose of this study was three-fold: (1) to compare the efficacy of digoxin with low-dose diltiazem and digoxin with low-dose betaxolol on randomized crossover study; (2) to evaluate whether the beneficial effects of medication will be maintained after 7 months; (3) to evaluate the safety of the combination therapy in patients with impaired left ventricular function. METHODS: We did a prospective randomized crossover study in 35 patients with chronic atrial fibrillation (AF) including 15 patients with left ventricular dysfunction. After enrollment, each patient was evaluated for heart rate, blood pressure, rate-pressure products, maximal exercise tolerance at rest and during symptom-limited treadmill test before medication, at 4 weeks after medication of digoxin (0.125-0.5 mg daily) with diltiazem (90 mg twice daily), and at 4 weeks after digoxin with betaxolol (20 mg once daily). We performed 24-h ambulatory electrocardiogram (ECG) in 15 patients at the end of each phase of treatment. We repeated symptom-limited treadmill test like above method in 15 patients at 7 months of medication. RESULTS: (1) Ventricular rates were significantly reduced in digoxin with low-dose betaxolol therapy at rest and during exercise (67 +/- 3, 135 +/- 5 (mean +/- S.E.M.) beats/min, respectively) in comparison to digoxin with low-dose diltiazem therapy (80 +/- 7, 154 +/- 5) (P < 0.05). (2) Rate-pressure products were significantly less in digoxin with low-dose betaxolol at rest and during exercise (85 +/- 4, 213 +/- 12 x 10(2) mmHg/min) than in digoxin with low-dose diltiazem therapy (105 +/- 6, 269 +/- 12) (P < 0.05). (3) Exercise capacity was significantly improved in digoxin with low-dose betaxolol (9.3 +/- 0.5 METS) or digoxin with low-dose diltiazem (9.7 +/- 0.5) in comparison to control state (8.3 +/- 0.5) (P < 0.05). (4) At 7 months evaluation, there was no significant difference between at 4 weeks and at 7 months. (5) Results on 24-h ambulatory ECG showed the same findings as on treadmill test. (6) Although side effects occurred more frequently in digoxin with low-dose betaxolol therapy, they were minimal and no patient had to withdraw medication. Worsening of left ventricular dysfunction was not observed. CONCLUSION: Our study suggested that (1) combination therapy of low-dose betaxolol with digoxin was more superior to low-dose diltiazem with digoxin in controlling ventricular rate and reducing rate-pressure products; (2) the effects controlling ventricular rate, reducing rate-pressure products and improving exercise capacity have been well maintained even after 7 months of medication with each combination therapy.

Adrenergic beta-Antagonists↗
PubMed1995

Interaction of intravenous heparin and organic nitrates in acute ischemic syndromes.

We evaluated whether a drug interaction between intravenous nitroglycerin or isosorbide dinitrate and heparin exists. Ninety-six patients with a diagnosis of acute myocardial infarction, unstable angina, or other thromboembolic disorders were divided into 3 groups: group I (control group, n = 35) received intravenous heparin alone; group II (n = 31) received combined intravenous nitroglycerin and heparin; and group III (n = 30) received combined intravenous isosorbide dinitrate and heparin. We determined the mean of 2 separate measurements of heparin dosage requirement, antithrombin III activity, and the dose of intravenous nitroglycerin or isosorbide dinitrate at the time that the ratio of activated partial thromboplastin time (aPTT) to baseline aPTT was 1.5 to 2.0. The mean therapeutic heparin dose standardized to total body weight of each group was 13.8, 15.4, and 15.5 U/kg/hour, respectively. At that time, patients were receiving intravenous nitroglycerin at doses of 58.8 +/- 38.6 micrograms/min or intravenous isosorbide dinitrate at doses of 3.7 +/- 2.0 mg/hour. The mean antithrombin III activity of each group was 22.2, 22.8, and 21.3 mg/dl, respectively. The overall results for groups I, II, and III, and results for the subgroup of patients with acute ischemic syndromes in those groups, did not differ significantly. The heparin dose did not show a significant correlation to the dose of intravenous nitroglycerin (r = -0.26, p > 0.05) nor to that of isosorbide dinitrate (r = 0.30, p > 0.05).

Acute Disease↗
PubMed1995

Ultrasonographic analysis of gestation in mink (Mustela vison).

Mink are seasonal breeders that display an obligate delay preceding implantation and a post implantation gestation of 31 d. The purpose of this study was to evaluate gestational parameters in mink by ultrasonography. A total of 92 female mink were mated twice during the period from March 2 to 20. The mink were scanned once and allowed to whelp (n=55); or scanned at 3 to 5-d intervals until parturition (n=13); or immediately subjected to autopsy (n=24) after scanning. Embryonic age was calculated from the date of parturition or from crown rump length. Uterine swelling diameter and fetal head size were correlated with embryonic age. The gestational sac grew rapidly once implantation had occurred. Uterine swellings of 4 to 5 mm in diameter were found on Days 2 to 4 post implantation and increased through Days 18 to 20, at which time they began to elongate due to the longitudinal growth of the fetus. Fetal cardiac activity could be detected on Days 10 to 12 post implantation in live embryos. The heart frequency was 198 +/- 3.0 beats per minute and did not vary from Days 12 to 30 post implantation. Fetal head diameter of 5 mm was first detected on Day 19 post implantation and grew gradually to 9 to 10 mm at parturition. It was not possible to accurately assess the number of conceptuses in utero. We conclude that ultrasonography can be employed in mink to diagnose pregnancy, to predict the parturition date and to determine the presence of live fetuses.

Journal Article↗
PubMed1995

Sodium channels and GABAA receptor-channel complex as targets of environmental toxicants.

Voltage-activated sodium channels and GABAA receptor-chloride channel complex are among the most important target sites of various environmental neurotoxicants. Pyrethroids keep the sodium channels open for prolonged periods of time leading to hyperexcitation of the entire nervous system. In rat cerebellar Purkinje neurons and dorsal root ganglion neurons, only about 1% of sodium channel population needed to be modified by the pyrethroid tetramethrin to increase the depolarizing after-potential to the level of the threshold membrane potential for generation of repetitive after-discharges. This concept of toxicity amplification is applicable to other chemicals that go through a threshold phenomenon to exert their effects. The potency of pyrethroids on neuronal sodium channels increased with lowering the temperature with a Q10 value of 0.2. The selective pyrethroid toxicity between mammals and insects can be quantitatively explained on the basis of the differences in 5 factors, i.e. the intrinsic sodium channel sensitivity, the sodium channel modification due to temperature difference, the reversibility of sodium channel, the detoxication of pyrethroids, and body size. These 5 factors are multiplied to approximately 2000 which is in the same order of magnitude as that of the difference in LD50. Dieldrin had a dual action on the GABAA receptor-chloride channel complex of rat dorsal root ganglion neurons. The initial transient potentiation of GABA-induced currents after application of dieldrin was followed by a suppression. Dieldrin-induced potentiation of current was observed only when the gamma 2 subunit was present in embryonic kidney cells (HEK-293) transfected with GABA receptor subunits. Dieldrin-induced suppression was observed in the presence and absence of the gamma 2 subunit. The dieldrin suppression of GABA-induced currents is deemed directly responsible for hyperactive symptoms of poisoning in animals.

Animals↗
PubMed1995

Short-course doxycycline treatment versus conventional tetracycline therapy for scrub typhus: a multicenter randomized trial.

To assess the clinical efficacy of short-course doxycycline in the treatment of scrub typhus, we compared conventional 7-day tetracycline therapy with 3-day doxycycline therapy in 116 patients. Patients were randomized to receive either tetracycline (500 mg four times daily; n = 50) or doxycycline (100 mg twice daily; n = 66) and were followed for 4 weeks after the completion of treatment. The cure rate was 100% in the tetracycline group and 93.9% in the doxycycline group (P > .05). The two groups did not differ significantly in terms of the interval required for defervescence or for the alleviation of symptoms. There were no relapses in either group. These data suggest that 3-day doxycycline therapy is as effective as conventional 7-day tetracycline therapy for the cure of scrub typhus and the prevention of relapses.

Adult↗
PubMed1995

Relationship between tissue plasminogen activator, plasminogen activator inhibitor and CT image in chronic subdural hematoma.

The present study was performed to investigate the relationship between the concentrations of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) and the CT images in 23 cases of chronic subdural hematomas (SDHs). The concentrations of t-PA and PAI-1 were quantified by enzyme-linked immunosorbent assay (ELISA). Chronic SDHs were divided into five groups according to their appearance on computed tomography: high-density (n = 4), isodensity (n = 8), low-density (n = 5), mixed-density (n = 3), layering (n = 3) types. The volume of hematoma was measured with an image analyzing software program. The concentrations of t-PA were higher in layering (41.2 +/- 0.3 ng/ml, mean +/- standard error of the mean) and high-density (40.0 +/- 1.1 ng/ml) types compared to those of low-density (23.3 +/- 4.1 ng/ml) and iso-density (25.1 +/- 3.7 ng/ml) types. The concentrations of PAI-1 were lower in layering (95.9 +/- 1.0 ng/ml) and high-density (103.4 +/- 34.5 ng/ml) types compared to that of low-density (192.5 +/- 2.6 ng/ml) type. So the ratio between t-PA and PAI-1 (t-PA/PAI) was greater in layering and high-density types. The volume of hematoma was larger in mixed-density and layering types but statistically insignificant. These results presumably suggest that the ratio between t-PA and PAI concentration may contribute to the pathogenesis of the chronic SDH.

Adult↗
PubMed1995

Effects of endoscopic variceal ligation in lower esophageal motor function: a prospective study.

OBJECTIVES: Endoscopic variceal ligation (EVL), a recently developed method for controlling active variceal bleeding and eradicating esophageal varices, has similar efficacy to endoscopic injection sclerotherapy (EIS) and is known to have a minimal risk of complications and fewer complications in the lower esophagus. However, since the site of EVL is chiefly done in the lower esophagus, we prospectively evaluated to investigate the effect of EVL on the lower esophageal motor function. METHODS: We evaluated the severity of esophageal varix with the endoscopy and the lower esophageal manometry in 27 patients who had no history of interventional therapy, for varices before EVL, 3 weeks and 6 months after the last EVL session. RESULTS: The EVL caused considerable diminution in the size of esophageal varix by a mean 8.2 (range 3-21) ligations in mean 1.7 (range 1-3) sessions. In most of the cases, the varices reappeared and enlarged when the procedure of EVL was stopped. There were two different types of changes (intermediate and late) in the lower esophageal motility. The intermediate post-EVL effects were the increase of peristaltic contraction amplitude and duration in the lower esophageal body after EVL. The late post-EVL effects were the prolongation of lower esophageal sphinctor (LES) relaxation duration and speedier peristaltic velocity in the lower esophageal body. CONCLUSIONS: We conclude from these findings that the intermediate post-EVL effect may be transient and the increase of peristaltic wave was due to diminution of esophageal varix.

Adult↗
PubMed1995

Selective block of tetramethrin-modified sodium channels by (+/-)-alpha-tocopherol (vitamin E).

Pyrethroids exert their hyperexcitatory effects by prolonging the open time of individual neuronal sodium channels. Occupational exposure to pyrethroids frequently leads to abnormal skin sensation or paresthesia. Vitamin E is known to reduce the cutaneous paresthesia. However, the mechanism of action has been totally unclear. Because the sodium channel is the major target site of pyrethroids, it is possible that vitamin E interferes with pyrethroid modification of the sodium channel. Patch clamp experiments were performed using rat dorsal root ganglion neurons and cerebellar Purkinje cells. (+/-)-alpha-Tocopherol (vitamin E) selectively blocked the tetramethrin(type I pyrethroid)-modified sodium channels in a dose-dependent, but voltage-independent manner without affecting normal sodium channels. The concentration-response curves for tetramethrin modification of the sodium channels were shifted in the direction of higher concentrations by (+/-)-alpha-tocopherol in a competitive manner. Elevated depolarizing after-potential or repetitive after-discharges caused by tetramethrin were effectively blocked by (+/-)-alpha-tocopherol. (+/-)-alpha-Tocopherol did not reverse the tetramethrin-induced shift in the current-voltage curve for peak sodium current, but partially reversed the shift in the steady-state sodium channel inactivation curve. Vitamin A and its metabolic derivative, retinoic acid, slightly reduced both normal and tetramethrin-modified sodium currents. The selective block of tetramethrin-modified sodium channels by (+/-)-alpha-tocopherol is one of the important mechanisms underlying (+/-)-alpha-tocopherol alleviation of paresthesia.

Animals↗
PubMed1994

High allele frequency of apolipoprotein(a) phenotype LpS4 is associated with low serum Lp(a) concentrations in Koreans.

We determined apo(a) phenotypes using SDS-PAGE followed by immunoblotting in samples from a control group of 179 and from 68 Korean patients with coronary artery disease (CAD). The CAD group showed significantly higher Lp(a) levels than the control group, which might be partially attributable to the differences in apo(a) phenotype frequencies although it was not statistically significant, and was partially attributable to the significant difference in Lp(a) levels of S2 or null phenotypes between the two groups. The apo(a) allele frequencies between ethnic groups already reported (Austrians, American blacks, Japanese, and Koreans), were compared by the Chi-square test. In the Korean population, the apo(a) allele frequencies demonstrated a high frequency of the LpS4 allele associated with a low Lp(a) concentration. This result suggests that the concentration and allele frequency of Lp(a) might be one of the factors in explaining the low incidence of CAD in the Korean population.

Alleles↗
PubMed1994

Clinical value of DMSA planar and single photon emission computed tomography as an initial diagnostic tool in adult women with recurrent acute pyelonephritis.

Routine DMSA scintigraphy, ultrasound (US) of the kidney, intravenous pyelography (IVP) and voiding cystoureterography (VCU) were performed in 27 consecutive adult women with recurrent acute pyelonephritis (APN) during a 12-month follow-up. Both planar and single photon emission computed tomography (SPECT) images were obtained for DMSA scan. DMSA scans were repeated in those patients with abnormal initial scan. DMSA-SPECT showed normal findings in 2, single renal cortical detect (RCD) in 9 and multiple RCD in 16 (including nonvisualization in 2). Of the 11 kidneys with normal findings or single RCD on DMSA-SPECT, only 1 (9%) showed vesicoureteral reflux (VUR) on VCU (grade I). A large proportion of those with multiple RCDs showed abnormal findings on IVP (44%, 7/16), US (38%, 6/16) or VCU (31%, 5/16); 63% in any of these three studies. 5 of 6 patients with VUR had multiple RCDs on DMSA-SPECT, and 3 of these 5 showed no abnormality on IVP or US. 7 patients who needed other managements besides initial standard antibiotic treatment had multiple RCDs on DMSA-SPECT. 15 normal women were also studied and showed normal DMSA-SPECT, US and IVP, in all cases. Follow-up DMSA-SPECT was done in 16 patients (7 with single RCD, 9 with multiple RCD). All 7 patients with single RCD showed improvement, in those with multiple RCDs improvement was observed in 2, no change in 7 on follow-up studies. We conclude: (1) DMSA-SPECT is a useful initial diagnostic tool in adult women with recurrent APN to identify patients who need more extensive radiological studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Cytomegalovirus is not specifically associated with immunoglobulin A nephropathy.

Cytomegalovirus (CMV) has been suspected to be involved in the pathogenesis of IgA nephropathy (IgAN). Whether CMV is present in renal tissue of IgAN, however, remains controversial. To determine the presence of CMV in IgAN, compared with other glomerulonephritis (GN) as disease control, polymerase chain reaction amplifying a 159-base-pair fragment of the immediate early gene of CMV and indirect immunofluorescence staining with anti-CMV monoclonal antibody were performed on 10 IgAN and 14 non-IgAN GN renal tissues. CMV DNA was detected in 6 of 10 IgAN tissues and 10 of 14 other GN by polymerase chain reaction, whereas no CMV antigen was detected in all renal tissues by immunofluorescence. This frequent observation of CMV DNA in various types of GN as well as in IgAN would suggest that CMV is not specifically associated with the pathogenesis of IgAN seen in endemic areas of CMV infection.

Antigens, Viral↗
PubMed1994

Ipsilateral synchronous renal cell carcinoma and transitional cell carcinoma.

The simultaneous occurrence of renal cell carcinoma(RCC) and transitional cell carcinoma(TCC) in the same kidney is unusual. We report a 53-year-old man with ipsilateral synchronous renal adenocarcinoma and renal pelvic transitional cell carcinoma with severe hypercalcemia and a huge staghorn calculus in the opposite kidney. The patient was admitted to the hospital because of left flank pain and intermittent fever which he had had for 2 months. Computerized tomography revealed a huge stone in the right kidney and a mass in the upper pole with an irregular calcified pelvis in the left enlarged kidney. Left radical nephrectomy was done. A section of the specimen revealed a renal cell carcinoma located at the upper pole and a papillary transitional cell carcinoma arising from the renal pelvis. This is a rare case of combined renal malignancies.

Carcinoma, Renal Cell↗