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Biomedical subjects

J Park

Publications and source records attributed to J Park.

479 records · Page 27Linked to original sources
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Systematic analysis of stimulants and narcotic analgesics by gas chromatography with nitrogen specific detection and mass spectrometry.

The recovery data of 40 doping agents from human urine were evaluated. Retention data were standardized by the calculation of relative retention times using N,N-diisopropyl-n-dodecane as the internal standard. The relative standard deviations of retention times were less than 0.5% for the within batch analyses and less than 0.8% for the day-to-day analyses. Good recoveries (greater than 70%) were observed for most of the drugs.

Analgesics, Opioid↗
PubMedDate not supplied

Determination of phenolalkylamines, narcotic analgesics, and beta-blockers by gas chromatography/mass spectrometry.

An analytical procedure for determination of phenolalkylamines, narcotic analgesics, and beta-blockers in urine by gas chromatography/mass spectrometry (GC/MS) is described. The detection of phenolalkylamines, narcotic analgesics, and beta-blockers is based on acid hydrolysis, liquid-liquid extraction, and selective derivatization. For screening of phenolalkylamines the m/e 179 and 267 ions were monitored by GC/MS. With narcotic analgesics, the extracted ion corresponded to the molecular ion (M+) of the drug and two additional characteristic ions. Beta-blockers were analyzed as the selectively derivatized forms of the parent molecule and its metabolites by GC/MS with selected ion monitoring. The ions monitored for screening of beta-blockers containing an isopropylamine group were m/e 284 and 129 ions. The ion at m/e 86 was monitored to characterize the tert-butylamine group of beta-blockers.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Systematic analysis of diuretic doping agents by HPLC screening and GC/MS confirmation.

The simultaneous analysis of diuretic agents by reversed-phase liquid chromatography with a diode-array detector (DAD) was performed by using a gradient elution with acetonitrile and phosphate buffer on a Hypersil-ODS column. For the spiked urine the extraction recovery of solid-phase extraction (SPE) using Sep-Pak C18 cartridge was compared with that of liquid-liquid extraction (LLE) with diethyl ether at various pH. The standard calibration curves were linear from 0.20-20.0 micrograms/mL for all diuretic agents except amiloride, 1.0-20.0 micrograms/mL, and the detection limit was about 0.2 micrograms/mL for 3 mL of urine, except that of amiloride, which was 1.0 micrograms/mL. The confirmation analysis was performed by gas chromatography/mass spectrometry (GC/MS) following methylation. The characteristic mass fragment ions obtained by electron-impact (EI) ionization (70 eV) provided identification of each diuretic agent.

Adult↗
PubMedDate not supplied

Analysis of anabolic steroids using GC/MS with selected ion monitoring.

This study describes the use of gas chromatography/mass spectrometry with selected ion monitoring to screen 18 anabolic steroids banned by the International Olympic Committee. These anabolic steroids are analyzed in two fractions depending on their excretion pattern: nonconjugated (free) or conjugated fraction. The wet procedure of extracting steroids from urine consists of an initial isolation of lipophilic compounds on a column packed with Amberlite XAD-2 resin, followed by enzymatic hydrolysis with beta-glucuronidase from Escherichia coli. After extraction, the hydrolyzed steroids are derivatized to the corresponding trimethylsilyl ethers. The derivatized steroids are analyzed by gas chromatography/mass spectrometry with selected ion monitoring of their characteristic ions. It takes 12 and 26 min to run GC/MS and edit the raw data for nonconjugated and conjugated fractions respectively.

Anabolic Agents↗
PubMedDate not supplied

Chloral hydrate: unusually high concentrations in a fatal overdose.

A case in which chloral hydrate as a pure chemical rather than the prescribed drug caused the death of a 27-year-old white male is presented. Trichloroethanol was quantified in blood and tissues by electron capture gas chromatography. The blood trichloroethanol concentration found in this case (1700 mg/L) was higher than had been previously reported in the literature.

Adult↗
PubMedDate not supplied

Diabetes insipidus as a presenting symptom of acute myelogenous leukemia.

This report describes a case of diabetes insipidus associated with acute myelogenous leukemia. An 11-year-old boy presented with fatigue, polydipsia and polyuria. His evaluation revealed a diagnosis of acute myelogenous leukemia FAB-M2, and a water deprivation test confirmed the diagnosis of central diabetes insipidus. His brain magnetic resonance imaging (MRI) showed a thickened, enhancing pituitary stalk with absence of the normal hyperintense signal in the posterior pituitary. He was treated with systemic chemotherapy, intensive intrathecal therapy, and 1,000 cGy to the pituitary. The patient achieved a remission but continued to need desmopressin therapy to control his diabetes insipidus. Diabetes insipidus is a rare complication of acute myelogenous leukemia that can be caused by leukemic infiltration of the pituitary. The diabetes insipidus is irreversible despite intensive systemic and central nervous system chemotherapy and radiation.

Child↗
PubMedDate not supplied

Taurolidine 2% as an antimicrobial lock solution for prevention of recurrent catheter-related bloodstream infections.

BACKGROUND: This case report describes our preliminary data on the use of taurolidine as a lock technique. Taurolidine is a novel antimicrobial agent that has found a niche in Europe for prevention of bacteremia in home parenteral nutrition (HPN) patients who have multiple catheter-related blood-stream infections. METHODS: A 29-year-old male with short bowel syndrome was admitted 18 times in 9 years for treatment of Gram-positive, Gram-negative, and yeast-associated catheter-related bloodstream infections. Management consisted of conventional antibiotic treatment in accordance with blood culture and sensitivity results as well as catheter removal in 10 cases. Ten months before the last infection, the patient was instructed to instil 1.5 mL taurolidine 2% daily into his central line after finishing his HPN infusion and has continued to do so 2 years to date. RESULTS: The incidence of catheter-related bloodstream infections decreased from 8.5 to 1.5 infections per 1000 catheter days. CONCLUSIONS: These data support previous observations made outside North America and suggest that taurolidine may prove to be an effective and safe antimicrobial agent for the prevention of recurrent catheter-related bloodstream infections.

Adult↗
PubMedDate not supplied

Remediating munitions-contaminated soil with zerovalent iron and cationic surfactants.

Soils contaminated from military operations often contain mixtures of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and TNT (2,4,6-trinitrotoluene) rather than a single explosive. Differences among explosives in solubility and reactivity make developing a single remediation treatment difficult. When Fe(0) was used to treat a munitions-contaminated soil, we observed high rates of destruction for RDX and TNT (98%) but not HMX. Our objective was to determine if HMX destruction by Fe(0) could be enhanced by increasing HMX solubility by physical (temperature) or chemical (surfactants) means. To determine electron acceptor preference, we treated RDX and HMX with Fe(0) in homogeneous solutions and binary mixtures. Increasing aqueous temperature (20 to 55 degrees C) increased HMX solubility (2 to 22 mg L(-1)) but did not increase destruction by Fe(0) in a contaminated soil slurry that also contained RDX and TNT. Batch experiments using equal molar concentrations of RDX and HMX demonstrated that RDX was preferentially reduced over HMX by Fe(0). By testing various surfactants, we found that the cationic surfactants (HDTMA [hexadecyltrimethylammonium bromide], didecyl, and didodecyl) were most effective in increasing HMX concentration in solution. Didecyl and HDTMA were also found to be highly effective in facilitating the transformation of HMX by Fe(0). Using HDTMA or didecyl solutions (3%, w/v) containing solid-phase HMX, we observed that 100% of the added HMX was transformed by Fe(0) in the didecyl matrix and 60% in the HDTMA matrix. These results indicate that cationic surfactants can increase HMX solubility and facilitate Fe(0)-mediated transformation kinetics but HMX destruction rates will be slowed when RDX is present.

Azocines↗
PubMedDate not supplied

Evaluation of the VIDAS Listeria (LIS) immunoassay for the detection of Listeria in foods using demi-Fraser and Fraser enrichment broths, as modification of AOAC Official Method 999.06 (AOAC Official Method 2004.06).

A multilaboratory study was conducted to compare the VIDAS LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types--brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef--at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance.

Animals↗
PubMedDate not supplied

A modified brace (Prenyl) for scoliosis.

Sixty-six skeletally immature patients with idiopathic scoliosis were treated with a Prenyl brace and their results were analyzed. Fifty-three patients (80%) showed a satisfactory response. The best results were obtained in patients with lumbar curves and thoracolumbar curves less than 40 degrees. Advantages of this brace are simplicity of fabrication and fitting, patient comfort, patient acceptance and relatively low cost. The disadvantages of this brace are that it is less effective in thoracic curves in the upper thoracic spine, double major curves and kyphosis. It probably causes more significant chest restriction than the Milwaukee brace.

Adolescent↗