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Biomedical subjects

H Chung

Publications and source records attributed to H Chung.

143 records · Page 8Linked to original sources
PubMed1978

Diazepam and halazepam in anxiety: some prognostic indicators.

A multiple step-search regression procedure was applied to data obtained with 37 diazepam and 42 halazepam treated anxious outpatients. Good treatment outcome was predicted for those patients who reported a more adequate family adjustment, the presence of precipitating stress, and who either had no prior psychotropic drug treatment, or if they had received such treatment, had experienced a good response. Probably of greatest interest to the practicing clinician was the observation that patients high in initial anxiety but low in initial interpersonal problems improved the most with both medications. Differential drug effects indicated halazepam to do particularly poorly in less anxious patients and in those patients given a good prognosis by the doctor. Diazepam response was much less affected by these variables. It is speculated that the excessive sedating effect of the daily halazepam dosage (160 mg/d) used in this study may explain these differential drug effects. In the dosages employed, namely, diazepam 20 mg/d and halazepam 160 mg/d, diazepam produced the more consistent anti-anxiety effects. The indication that halazepam 160 mg/d was more effective than diazepam 20 mg/d in the initially sicker patients, while of interest, is probably simply a dose-related phenomenon, indicating that diazepam 20 mg/d was too low a daily dosage for severely anxious patients, a fact well known by most clinicians.

Adult↗
PubMed1977

Primary type V hyperlipoproteinemia in childhood.

Metabolic studies of a 9-year-old girl with primary type V hyperlipoproteinemia demonstrated normal glucose tolerance, plasma insulin and glucagon responses to stimuli, and serum uric acid level. Fasting plasma triglyceride levels rapidly increased when the patient received a diet containing 40% of the total calories as fat and rapidly decreased on a 10% fat diet. Hepatic and nonhepatic lipase activities in postheparin plasma were normal, thus excluding type I hyperlipoproteinemia. Because of the potential complication of acute pancreatitis in this disorder, early diagnosis and prompt institution of diet therapy is important.

Age Factors↗
PubMed1977

Morphology, growth, chromosomal pattern and fibrinolytic activity of two new human neuroblastoma cell lines.

Neuroblastoma cell lines LA-N-1 and LA-N-2 were extablished from neuroblastoma cells in the bone marrow and in the primary tumor, respectively, of two children with metastatic neuroblastoma. Morphology, growth in vitro and in athymic nude mice, chromosomal patter, and fibrinolytic activity of these cell lines and of previously extablished human neuroblastoma cell lines IMR-32, SK-N-MC, and SK-N-SH were compared. Most LA-N-1 cells were tear-drop shaped, small cells with processes; they tended to grow in clusters. LA-N-2 was comprised of elongated cells and small round cells, the latter growing in dense clumps on the former. Electron microscopy revealed numerous cytoplasmic dense cores in many LA-N-1 cells but none in LA-N-2 CELLS. During logarithmic growth in vitro, doubling times for LA-N-1, LA-N-2, SK-N-MC, SK-N-SH, and IMR-32 cells were 32,56, 23, 36, and 26 hr, respectively. Cells of all lines formed colonies in soft agar, and, after variable latency periods, LA-N-1, LA-N-2, SK-N-MC, and IMR-32 cells formed tumors in athymic nude mice. The marker chromosome(s) characteristic of each cell line was present in more than 90% of cells of given line. Significant plasminogen-dependent fibrinolytic activity was present in cells of all lines. These studies indicate that LA-N-1 and LA-N-2 cells arose from single but different aberrant progenitor cells and that they have properties of neuroblastoma cells. They also demonstrate that cell lines derived from human neuroblastomas are heterogenous as are the tumors in children.

Animals↗
PubMed1974

Purification and properties of a diacetyl reductase from Escherichia coli.

A reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reductase with the ability to reduce diacetyl has been isolated from Escherichia coli and has been purified 800-fold to near homogeneity. The product of the reduction of diacetyl was shown to be acetoin. The enzyme proved to catalyze the oxidation of NADPH in the presence of both uncharged alpha- and beta-dicarbonyl compounds. Even monocarbonyl compounds showed slight activity with the enzyme. On the basis of its substrate specificity, it is suggested that the enzyme functions as a diacetyl reductase. In contrast to other diacetyl reductases, the one reported here is specific for NADPH and does not possess acetoin reductase activity. The pH optimum of this enzyme was found to be between 6 and 7. The maximal velocity for the NADPH-dependent reduction of diacetyl was determined to be 9.5 mumol per min per mg of protein and the K(m) values for diacetyl and NADPH were found to be 4.44 mM and 0.02 mM, respectively. The molecular weight was estimated by gel filtration on Sephadex G-100 to be approximately 10,000.

Acetoacetates↗
PubMedDate not supplied

Structural characteristics of size-controlled self-aggregates of deoxycholic acid-modified chitosan and their application as a DNA delivery carrier.

Precise control of the size and structure is one critical design parameter of micellar systems for drug delivery applications. To control the size of self-aggregates, chitosan was depolymerized with various amounts of sodium nitrite, and hydrophobically modified with deoxycholic acid to form self-aggregates in aqueous media. Formation and physicochemical characteristics of size-controlled self-aggregates were investigated using dynamic light scattering, fluorescence spectroscopy, and computer simulation method. The size of self-aggregates varied in the range of 130-300 nm in diameter, and their structures were found to depend strongly on the molecular weight of chitosan ranging from 5 to 200 kDa. Due to the chain rigidity of chitosan molecule, the structure of self-aggregates was suggested to be a cylindrical bamboolike structure when the molecular weight of chitosan was larger than 40 kDa, which might form a very poor spherical form of a birdnestlike structure. To explore the potential applications of self-aggregates as a gene delivery carrier, complexes between chitosan self-aggregates and plasmid DNA were prepared and confirmed by measuring the fluorescence intensity of ethidium bromide and electrophoresis on agarose gels. The complex formation had strong dependency on the size and structure of chitosan self-aggregates and significantly influenced the transfection efficiency of COS-1 cells (up to a factor of 10). This approach to control the size and structure of chitosan-derived self-aggregates may find a wide range of applications in gene delivery as well as general drug delivery applications.

Animals↗
PubMedDate not supplied

Postmortem distribution of zipeprol.

The abuse of zipeprol, an antitussive agent, is prevalent among young people in Korea. For its hallucinogenic effects, abusers have taken overdoses of the drug; thus, fatalities from zipeprol overdose have risen since 1991. In order to determine the postmortem distribution of zipeprol, tissues and blood from 23 decedents who had histories of drug abuse were examined. Homogenized tissue (1 g) and 1 mL blood were extracted by ethyl acetate. Cinnarizine was used as an internal standard. A Varian GC 4600 equipped with a thermionic specific detector was used to quantitate the drug using a DB-5 megabore column, and a Finnigan GC-MS model 4021 was used to obtain mass spectral identification of the extracts. The blood zipeprol concentrations varied from 2.3 to 38.3 micrograms/mL. The highest concentration of zipeprol was found in stomach tissue. Zipeprol concentrations in tissues were higher than the corresponding blood concentrations.

Adolescent↗
PubMedDate not supplied

Fatal zipeprol and dextromethorphan poisonings in Korea.

Zipeprol and dextromethorphan are abused together by young people in Korea to obtain a stronger hallucinogenic effect. Because large amounts of these drugs are taken for this reason, nine fatal poisonings due to zipeprol and dextromethorphan have been reported since 1993. In this paper, the concentration of drugs in the postmortem blood and gastric contents of these victims is examined. The determination and identification of the drugs in biological fluids were conducted by gas chromatography (GC)-thermionic specific detection and GC-mass spectrometry. Linear calibration curves and high recoveries were obtained. The blood concentrations of zipeprol varied from 1.3 to 28.6 micrograms/mL, and the concentrations of dextromethorphan ranged from 1.1 to 18.3 micrograms/mL. The concentration of zipeprol in the gastric contents ranged from 26.8 to 1384.8 micrograms/g, and dextromethorphan concentrations varied from 2.1 to 243.7 micrograms/g.

Adult↗
PubMedDate not supplied

A fatality due to injection of tiletamine and zolazepam.

A 22-year-old male with more than 28 needle marks on his right arm was found dead. First, he was suspected as a drug abuser. Blood, urine, spleen, and injection-site tissue was collected during autopsy. The blood and urine specimens were screened for drugs. Immunoassay studies did not show any illegal drugs. However, two unidentified peaks were isolated in both of these biological fluids by routine gas chromatography-flame-ionization detection (GC-FID) and thermionic specific detection. Additional gas chromatography-mass spectrometry analysis determined these two peaks to be tiletamine and zolazepam. These two agents are used in combination as veterinary anesthesia. The concentrations of these drugs in blood were quantitated by GC-FID and found to be 0.85 mg/L of tiletamine and 3.3 mg/L of zolazepam. In urine, tiletamine and its metabolite, 2-(ethylamino)-2-(2-thionyl) cyclohexanol, were identified to be present along with zolazepam. The concentrations of tiletamine and zolazepam in spleen were revealed to be 0.92 and 3.5 mg/kg, respectively. Injection-site tissue concentrations were determined to be 25.1 mg/kg tiletamine and 23.3 mg/kg for zolazepam. The cause of death in this case was determined to be due to the multiple drug intoxication of tiletamine and zolazepam.

Adult↗
PubMedDate not supplied

Deficiencies and improvement of methemoglobin assay.

A day-to-day variability in results was encountered when using the Dubowski method for the routine clinical determination of methemoglobin in blood. Therefore, studies were performed to determine the source(s) of variability in the method as described by Dubowski. It was determined that complete lysing of red blood cells is dependent upon both temperature of the buffer and the amount of lysing agent. Low buffer temperatures (less than 14 degrees C) produced highly variable results. This variability can be reduced by increasing the level of lysing agent to 40 mg per 20 mL of diluted blood. It was found that by using 37 degrees C buffer solution temperature and 40 mg Triton X-100 as lysing agent per 20 mL of diluted blood (1:20 with 0.25M sodium phosphate buffer, pH 7.4), the precision (percent coefficient of variation = 2%) and the accuracy (percent coefficient variation = 5.5%) were excellent.

Animals↗
PubMedDate not supplied

The disposition of threo-alpha-(2-piperidyl)-2-trifluoromethyl-6-(4-trifluoromethylphenyl)-4-pyridinemethanol phosphate in mice.

Following oral administration of the 14C-labeled title compound to male mice, the drug was well absorbed and rapidly distributed throughout the body. At least 90% of the radioactivity in the tissues at 2 hr after dosing was identified as parent compound by thin-layer chromatography. The peak plasma level of radioactivity occurred at 4 hr, and the t1/2 of elimination of parent drug was about 26 hr from the plasma and about 27 hr from the red blood cells. The major route of elimination of total radioactivity was fecal (84%), with only 5.5% in the urine at 240 hr. Only a trace of radioactivity (0.32%) was found in the expired air over a 192-hr period.

Animals↗