Biomedical subjects

D S Isenschmid

Publications and source records attributed to D S Isenschmid.

9 recordsLinked to original sources

PubMed1990

Cocaine fatality: an unexplained blood concentration in a fatal overdose.

A case is presented of a 26-year-old female who died as a result of cocaine intoxication. A blood cocaine concentration of 330 mg/l, about 1.5 times greater than the highest concentration previously reported, was found. Blood benzoylecgonine and ecgonine methyl ester concentrations were 50 and 18 mg/l, respectively. The unusually high blood concentrations of cocaine and the metabolites are suggestive of a massive administration, however, the history suggests a series of recreational uses. The manner of death was undetermined.

Adult↗

PubMed1988

Incidence of cannabinoids in medical examiner urine specimens.

Cannabinoid use was studied in a nonspecific population of postmortem urine specimens in the State of Maryland. Of 500 sequential specimens screened for cannabinoids by enzyme multiplied immunoassay EMIT, 63 (13%) were initially positive and 58 (12%) were confirmed positive (92%). It was observed that geographic location and race did not correlate with cannabinoid prevalence. Cannabinoid use was observed to be strongly age related, with peak use by the 21- to 25-year-old age group where 22% of the cases were positive. Use of cannabinoids was also closely linked to homicides, which represented nearly half of the positive cases but only 13% of the total cases. When comparing manner of death, the greatest percent of confirmed positives was seen in homicide (26%) and drug-related (17%) deaths. The incidence of cannabinoid use was found to be more than 3 times as great in drug-related (17%) as compared to natural deaths (5%). The percent of cannabinoid-positive cases from vehicle-related accidents was low (6%) and that from nonvehicle-related accidents somewhat higher (10%). Other drugs appeared in cannabinoid-positive cases. Most prevalent was ethanol N = 18, followed by morphine (from heroin, N = 11), quinine N = 11, and cocaine N = 11. Phencyclidine (PCP) occurred twice and several other drugs were reported only once. Of the 25 homicide cases screened for drugs, 64% were positive for some drug including ethyl alcohol. Thus it appears that a high percentage of homicide cases are drug related. Males greatly outnumbered females (56:2) in positive cases, but the number of female specimens received was small.

Adult↗

PubMed1982

Fluorometry of selenium in human hair, urine and blood. A single-tube process for submicrogram determination of selenium.

This communication introduces a special lyophilization process for selenium determination by fluorometric methods. It permits a small sample volume, with several modifications including a single test tube process. Samples and standard are lyophilized first, then digested with nitric-perchloric acid mixture in a heated sand bath. Selenium is complexed with 2,3-diaminonaphthalene and extracted by n-hexane in the same test tube. The n-hexane layer is transferred to a cuvette and measured fluorometrically. Selenium concentration in healthy children from Long Island (aged 5-18 years) was: hair 0.765 +/- 0.114 microgram/g (n = 52), urine 28.65 +/- 8.27 micrograms/g creatinine (n = 66), and serum 95.4 +/- 14.4 ng/ml (n = 44). The current literature reflects an increase in the role of selenium in human nutrition. Thus, a simple but reliable method for determination of selenium in biological materials is needed in the clinical and research laboratory.

Adolescent↗

PubMedDate not supplied

A method for the determination of 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid in urine using high performance liquid chromatography with electrochemical detection.

11-Nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) was isolated using solid phase extraction and identified with high performance liquid chromatography (HPLC) with electrochemical detection (EC). HPLC/EC was compared to an established HPLC procedure using ultraviolet (UV) detection. Statistical analysis revealed good precision, linearity, and correlation between the HPLC/EC and HPLC/UV methods. Within-run and between-run precision for the HPLC/EC vs. HPLC/UV analyses yielded coefficients of variation of 4.1 vs. 6.7% and 8.3 vs. 10.9%, respectively. Standard curves over a range of 20 to 160 ng/mL of THC-COOH in fortified urine on four separate analytical runs yielded correlation coefficients of greater than 0.99 for each method. Quantitative results from 15 positive urine specimens also compared favorably between the two methods (r = 0.9923). Using an immunoassay screening technique with confirmation by HPLC/UV and high efficiency thin layer chromatography (HETLC), further evaluation of the HPLC/EC method was achieved by examining 50 cannabinoid positive and 50 cannabinoid negative clinical urine specimens and 500 sequentially collected postmortem urine specimens.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

A method for the simultaneous determination of cocaine, benzoylecgonine, and ecgonine methyl ester in blood and urine using GC/EIMS with derivatization to produce high mass molecular ions.

A method for the simultaneous analysis of cocaine (COC), derivatized benzoylecgonine (BE), and derivatized ecgonine methyl ester (EME) has been developed. Blood or urine containing deuterated analogs of the three analytes is extracted by pouring over a Chem-Elut column and eluting with chloroform/isopropanol (9:1). The eluent is collected, split into two equal aliquots, and evaporated to dryness. In one aliquot, dimethylformamide and dimethylformamide dipropyl acetal are allowed to react and to derivatize BE to n-propyl COC. In the other aliquot, 4-fluorobenzoyl chloride, pyridine, and benzene are used to derivatize EME to p-fluoro-COC. COC is not affected by these reactions and may be found in either aliquot. Separation was performed on an HP 5890 GC using an HP-1 capillary column. The oven temperature was initially 100 degrees C for 1 minute, then programmed at 30 degrees/minute to a final temperature of 260 degrees C. The GC/MS was operated in the SIM mode, and the masses monitored were 303, 321, and 331 respectively for COC and derivatized EME and BE, and 308, 324, and 334 for the respective deuterated internal standards. The assay showed a minimum linear range of 0.05-2.0 mg/L for COC and 0.10-4.0 mg/L for each of the metabolites.

Cocaine↗

PubMedDate not supplied

A comprehensive study of the stability of cocaine and its metabolites.

The stability of cocaine (COC) in blood bank blood, postmortem human whole blood, and buffers was evaluated with consideration for the presence of the degradation products, benzoylecgonine (BE) and ecgonine methyl ester (EME). At COC concentrations commonly seen, the rate of COC hydrolysis was independent of concentration. COC was stable in blood for at least 150 days if the blood was adjusted to pH 5 and preserved with 2% NaF or organophosphates and maintained at 4 degrees C or lower. Without preservation, most COC hydrolyzed to EME. The addition of a pseudocholinesterase (PChE) inhibitor without a reduction of pH caused COC to hydrolyze to BE. COC also hydrolyzed to BE in phosphate buffer. The rate of COC hydrolysis in all studies increased with increasing pH and temperature. COC was more stable in unpreserved postmortem blood than blood bank blood due to the lower pH of the former. The incubation of COC in enzyme solutions provided further evidence of the generally accepted hypothesis that COC is hydrolyzed to EME by PChE and to BE by chemical hydrolysis. In unpreserved blood, BE was more stable than EME at room temperature. There was little loss of BE or EME at refrigerated temperature over a period of 35 days and no evidence that EME or BE could be hydrolyzed enzymatically.

Acetylcholinesterase↗

PubMedDate not supplied

Concentration of cocaine and metabolites in plasma of humans following intravenous administration and smoking of cocaine.

Plasma was obtained from 10 human subjects at various intervals after administration of two rapid doses of cocaine, either intravenously or by smoking, and multiple doses by smoking and intravenously. The plasma was analyzed for COC and its metabolites, benzoylecgonine (BE) and ecgonine methyl ester (EME). Plasma concentrations of COC were found to be dose-dependent. For patients receiving two successive doses of COC intravenously (IV) or by smoking (SM), the average half-life of COC was found to be between 38 and 39 minutes, regardless of the dose or route of administration. Considerable interindividual variation was observed. Multiple doses of both SM and IV COC were administered to three patients in a manner consistent with COC abuse. The maximum COC concentration observed was 1.2 mg/L following a total administration of 316 mg of COC over 90 min. Analysis of BE and EME confirmed that BE is the principle metabolite of COC in blood. All COC was accounted for by BE. EME, when present, did not exceed 5% of the BE concentration.

Cocaine↗

PubMedDate not supplied

The role of ecgonine methyl ester in the interpretation of cocaine concentrations in postmortem blood.

A study of the metabolism of in vivo cocaine (COC) and the stability of in vitro COC suggests that the presence of benzoylecgonine (BE) in unpreserved blood arises from in vivo COC metabolism and that ecgonine methyl ester (EME) in unpreserved blood arises from in vitro COC hydrolysis. Postmortem cases positive for COC were studied to determine if molar concentrations of EME in unpreserved blood could be used to estimate the blood COC concentration at the time of death when added to the molar COC concentrations. COC was analyzed in 10 postmortem blood specimens between 1 and 8 days following death and again 10 to 70 days after further storage. The COC lost was accounted for by its hydrolysis to EME. Good correlation (r = 0.9677, p < 0.001) was observed when the blood COC concentrations in postmortem cases were compared to blood COC concentrations predicted by the addition of blood COC and EME concentrations; hence, analysis for EME and estimation of perimortem COC concentrations can assist in defining deaths associated with COC use.

Adolescent↗

PubMedDate not supplied

Urine cannabinoid analysis: an integrated multi-method approach.

The Enzyme Multiplied Immunoassay Technique (EMIT) Urine Cannabinoid Assay (Syva) was adapted for automated analysis on a centrifugal analyzer allowing for cost-effective, rapid, high-volume urine testing. Confirmation of positive EMIT results was accomplished by a modification of a recently published high performance liquid chromatographic (HPLC) technique for 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH). Further confirmation of the presence of THC-COOH was achieved by high efficiency thin layer chromatography (HETLC). The reported protocol was applied to urine samples obtained from an emergency toxicology population and a drug counseling population. Results indicated that specimens testing positive by all three methods suggest valid forensic evidence for the presence of THC-COOH.

Cannabinoids↗