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Biomedical subjects

B K Logan

Publications and source records attributed to B K Logan.

At least 37 records · Page 2Linked to original sources
PubMed1996

Simple versus sophisticated models of breath alcohol exhalation profiles.

For medicolegal purposes, breath alcohol content is typically determined from an end-expiratory sample. Measurements obtained by this method necessarily underestimate the alveolar breath alcohol content, and therefore underestimate the blood alcohol content. We suggest and analyse an improved paradigm which uses the entire time-series of breath alcohol measurements during exhalation, not simply the last recorded value. We present two mathematical models for the exhaling lung, and discuss the implications of each for more accurate and therefore more reliable breath alcohol measurement.

Adult↗
PubMed1996

Gastric contamination of postmortem blood samples during blind-stick sample collection.

A blood sample drawn by a blind stick through the chest was collected for toxicologic examination in a suspected natural death. Drug screen results on the blood sample indicated a combined overdose of alcohol and amitriptyline. An autopsy was later performed and a peripheral blood sample was drawn. A drug screen of this sample showed the presence of therapeutic quantities of amitriptyline and a trace of alcohol. Cytologic examination of the blind-stick sample showed the presence of columnar cells and food debris, confirming that the sample was contaminated either by stomach contents or gastric aspirate during the collection procedure. We strongly encourage all agencies to refrain from the use of blind-stick sample collection for toxicologic specimens.

Autopsy↗
PubMed1996

Differentiation of Mycobacterium genavense and Mycobacterium simiae by automated mycolic acid analysis with high-performance liquid chromatography.

Mycobacterium genavense, a fastidious opportunist in patients with AIDS, cannot be identified by conventional biochemical methods. Computerized mycolic acid analysis by high-performance liquid chromatography offers an alternative that distinguishes the mycolic acid profile of M. genavense from those of all other organisms in the database developed at the Centers for Disease Control and Prevention.

Bacterial Typing Techniques↗
PubMed1996

Methamphetamine and driving impairment.

Following a review of the effects of methamphetamine on human performance, actual driving and behavior were evaluated in 28 cases in which drivers arrested or killed in traffic accidents had tested positive for methamphetamine. The circumstances surrounding the arrest or accident were examined, together with any observations by the arresting officer regarding behavioral irregularities. The investigators also made a determination of culpability. Most of the arrests resulted from accidents in which the driver was determined to be culpable. Typical driving behaviors included drifting out of the lane of travel, erratic driving, weaving, speeding, drifting off the road, and high speed collisions. Behavioral manifestations of methamphetamine use in arrestees included rapid or confused speech, rapid pulse, agitation, paranoia, dilated pupils, violet or aggressive attitude. Combined alcohol and methamphetamine use was uncommon, however use of marijuana was evident in about one third of the cases. In addition to impairing judgment and increasing risk taking, the effects of withdrawal from methamphetamine use including fatigue, hypersomnnolence, and depression are likely contributors to many of these accidents. A consideration of the literature and the cases discussed here, leads to the conclusion that methamphetamine at any concentration is likely to produce symptoms that are inconsistent with safe driving.

Adolescent↗
PubMed1996

Drug and alcohol use in fatally injured drivers in Washington State.

Blood and/or urine from fatally injured drivers in Washington State were collected and tested for the presence of drugs and alcohol. Drug and/or alcohol use was a factor in 52% of all fatalities. Among single vehicle accidents, alcohol use was a factor in 61% of cases versus 30% for multiple vehicle accidents. Drugs most commonly encountered were marijuana (11%), cocaine (3%), amphetamines (2%), together with a variety of depressant prescription medications. Trends noted included an association of depressant use with higher blood alcohol levels, while marijuana use was associated with lower blood alcohol levels. Marijuana use was noted to be most prominent in the 15-30 year age group, stimulant use in the 21-40 year old group, and prescription depressant use was more prevelant in the 45 + age group. Drug use demographics in this population are consistent with those noted in other jurisdictions.

Accidents, Traffic↗
PubMed1996

Postmortem distribution and redistribution of morphine in man.

This study evaluated both site dependent differences and time dependent changes in postmortem morphine concentrations in man. In 32 deaths involving morphine, left ventricular blood, femoral blood, and cisternal cerebrospinal fluid, were collected as soon after death as possible (T1), and collected again together with iliac blood at the time of autopsy (T2). Samples were analyzed for morphine by radioimmunoassay. No evidence was found for changes in morphine concentration with respect to time at either central or peripheral sites, or in the cerebrospinal fluid. Ventricular blood morphine concentrations were however consistently higher than those in the peripheral compartment, represented by either femoral or iliac blood. This was particularly true when the ventricular morphine concentration exceeded 0.300 mg/L. At peripheral sites, femoral and iliac blood morphine concentrations were well correlated with each other, making either an appropriate site for collection of peripheral blood for toxicological testing.

Adult↗
PubMed1996

Case report: distribution of methamphetamine in a massive fatal ingestion.

A subject who apparently swallowed a baggie containing "crank" (methamphetamine) while being arrested, was admitted to hospital and then experienced a massive overdose of the drug. The subject went through a seizure with associated fixed dilated pupils, and a depressed pulse and blood pressure. His cardiac and respiratory problems could not be stabilized, and he died. Methamphetamine levels in central and peripheral blood, liver, bile, vitreous, gastric and urine were determined. Blood levels of greater than 60 mg/L, were found together with even higher levels in the bile, urine and gastric. These levels are discussed in terms of other fatal, non-fatal and recreational methamphetamine use.

Adult↗
PubMed1995

Detection of cocaine and its polar transformation products and metabolites in human urine.

This paper describes a method for the analysis of thermal degradation compounds generated from cocaine during the smoking process, together with chemical and enzymatic biotransformation products which, by virtue of their polarity, are not recovered by existing analytical procedures. The method employs cation exchange solid phase extraction coupled with gas chromatography/mass spectrometry. Compounds identified in urine from subjects of cocaine-related death included cocaine, benzoylecgonine, ecgonine methyl ester and ecgonine, which were measured quantitatively, and ecgonidine, ecgonidine methyl ester, ecgonine ethyl ester, ethyl benzoylecgonine, norcocaine, benzoylnorecgonine, cinnamoylcocaine, and cinnamoylecgonine. The concentrations of ecgonine (0-104 micrograms/ml) and ecgonine methyl ester (0-177 micrograms/ml) were substantial and averaged about one tenth the concentrations of benzoylecgonine (0-1074 micrograms/ml) and cocaine (0-1221 micrograms/ml). These and several of the other compounds identified will be valuable markers for cocaine use, in degraded samples and for indicating the route of administration.

Biotransformation↗
PubMed1995

Unexpected amantadine intoxication in the death of a trauma patient.

We present a case of amantadine intoxication that developed unexpectedly in a hospitalized patient with craniocerebral trauma. The intoxication confused the clinical situation and contributed to the patient's deterioration and death. After excluding overdosage as the cause of the intoxication, we concluded that the excessive blood drug levels (39 mg/L) resulted from tubulointerstitial nephritis--induced renal failure. This case represents an example of an adverse drug reaction that resulted in an unusual drug intoxication and illustrates why toxicological analyses are important for investigation of deaths in hospitalized patients.

Adult↗
PubMed1995

Variability of ethanol absorption and breath concentrations during a large-scale alcohol administration study.

Ethanol disposition was evaluated in 77 female and 97 male college seniors during an alcohol challenge study. All were regular drinkers who exceeded legal intoxication levels at least twice a month by history. A standard ethanol dose (females, 0.43 g/kg; males, 0.51 g/kg) was administered over 10 min, after a 4-hr fast, and breath alcohol concentrations (BrACs) were measured for 2 hr. Intersubject variability in BrACs was greatest early in the study, during ethanol absorption; the coefficient of variation decreased from 39% at 14 min to 14% at 125 min after the start of drinking. The time to peak BrAC varied from 10 to 91 min after the start of drinking (mean 39.6 min). Mean BrACs were significantly lower in females than males; mean peak BrACs were 0.054 g/210 liters in females and 0.058 g/210 liters in males (p = 0.031). The beta- and r-values for both genders were higher than those typically used in ethanol dose calculation formulas. Data are discussed to direct future research. The constants used in Widmark's formula need to be revised differentially for males and females in this population to reach specific target BrACs. Furthermore, substantial variability in absorption rates must be accounted for when assessing rising versus falling limb BrAC phenomena.

Adult↗
PubMed1995

An evaluation of the reliability of Widmark calculations based on breath alcohol measurements.

This study evaluated the reliability of Widmark calculations, based on breath ethanol reading (BrACs), for estimating the amount of alcohol consumed. A standard ethanol dose (males 0.51 g/kg; females 0.43 g/kg) was given to 115 college seniors, and BrACs were measured for two hours. Calculations of ethanol dose were performed using BrACs taken at 60, 75, 105, and 125 minutes after drinking. Mean calculated ethanol doses were lower than actual doses at each time point (P < 0.001). Mean underestimates were 13, 12, 15, and 14 mL of 100 proof vodka at 60, 70, 105, and 125 min after drinking. Calculated doses overestimated actual doses in 11, 10, 3, and 3 subjects at 60, 75, 105, and 125 min after drinking. The maximum overestimates were 13, 11, 6, and 8 mL of vodka at 60, 75, 105, and 125 min after drinking. At the 95% confidence level, the calculated dose at 105 and 125 min did not overestimate the true dose, but could underestimate it by as much as 30 mL vodka.

Adult↗
PubMed1994

The significance of morphine concentrations in the cerebrospinal fluid in morphine caused deaths.

Morphine analysis was performed using a variety of immunoassay methods in blood, urine and the cisternal cerebrospinal fluid (CSF) from 23 patients dying opiate-related deaths. Of these, 16 were a result of intravenous morphine or heroin use. The blood and CSF morphine concentrations were determined using both fluorescence polarization immunoassay (FPIA) and radioimmunoassay (RIA), while urine was analyzed by enzyme multiplied immunoassay technique (EMIT). Urine morphine concentrations were greater than 0.300 microgram/mL in all but one case. Blood and CSF morphine concentrations were found to be poorly correlated, and it was concluded that one should not be used to predict the other. Following intravenous administration, CSF morphine concentrations of greater than 0.02 microgram/mL were however found to be consistent with death from morphine related respiratory depression. As intrathecal or epidural administration of morphine can greatly influence the CSF concentration without inducing respiratory depression, the site of collection of the CSF must be known, as must the route of administration in order to properly interpret CSF morphine concentrations.

Drug Overdose↗
PubMed1994

Isopropanol interference with breath alcohol analysis: a case report.

The presence of interfering substances, particularly acetone, has historically been a concern in the forensic measurement of ethanol in human breath. Although modern infrared instruments employ methods for distinguishing between ethanol and acetone, false-positive interferant results can arise from instrumental or procedural problems. The case described gives the analytical results of an individual arrested for driving while intoxicated and subsequently providing breath samples in two different BAC Verifier Datamaster infrared breath alcohol instruments. The instruments recorded ethanol results ranging from 0.09 to 0.17 g/210 L with corresponding interferant results of 0.02 to 0.06 g/210 L over approximately three hours. Breath and venous blood specimens collected later were analyzed by gas chromatography and revealed in the blood: isopropanol 0.023 g/100 mL, acetone 0.057 g/100 mL and ethanol 0.076g/100 mL. Qualitative analysis of the breath sample by GCMS also showed the presence of all three compounds. This individual had apparently consumed both ethanol and isopropanol with acetone resulting from the metabolism of isopropanol. An important observation is that the breath test instruments detected the interfering substances on each breath sample and yet they did not show tendencies to report false interferences when compared with statewide interferant data.

1-Propanol↗
PubMed1991

A rapid method for the determination of cocaine in brain tissue.

A rapid procedure is described for the extraction and analysis of brain samples for cocaine and benzoylecgonine. Human brain tissue was sectioned at autopsy, and samples were subjected to a lipase digestion, subsequent to solid-phase extraction. The distribution of cocaine and benzoylecgonine throughout different regions of the brain was determined by high-performance liquid chromatography.

Brain Chemistry↗
PubMed1990

Information resources useful in forensic toxicology.

This paper addresses information resources available to forensic toxicologists. The approach taken here is to discuss those resources found useful in problem solving situations. First, attempt to obtain information from someone familiar with the problem. This is generally the most efficient mechanism to use. The next most efficient mechanism is to search the published literature, electronically using bibliographic databases, if possible. The least efficient method of obtaining information is to go into the laboratory and generate the desired information. In many situations, however, the problem must be solved, or the information confirmed, in the laboratory. Suggested sources of information have been listed in the appendices. These are not intended to be exhaustive, but rather to stimulate and direct the access to information resources.

Databases, Bibliographic↗
PubMed1990

High-performance liquid chromatography with column switching for the determination of cocaine and benzoylecgonine concentrations in vitreous humor.

A sample concentration technique was adapted for the determination of cocaine and benzoylecgonine (BE) concentrations in vitreous humor. Vitreous humor (0.5 mL) was diluted 1:1 with water and applied through a filter onto a 3-cm preconcentration column. Following a simple wash step, the analytes were flushed directly onto a reversed-phase analytical high-performance liquid chromatography (HPLC) system. Absolute recoveries were high (above 90%) and the chromatograms were free from interference. Analysis for the drug and its breakdown product was performed using ultraviolet (UV) visible photodiode array detection, which allowed confirmation of peak identity. Recognizable UV spectra could be measured with as little as 20 ng on column. Comparison of the drug levels in 27 blood and vitreous humor samples showed that, while there was only a low correlation between the blood and vitreous concentrations (R = 0.70), vitreous cocaine and BE determinations were good indicators of antemortem cocaine use. In almost all cases, the vitreous BE concentrations were higher than the cocaine concentrations. The technique was easy to perform and the vitreous samples were especially compatible with this low-labor analytical procedure.

Chromatography, High Pressure Liquid↗
PubMed1989

Liquid/solid extraction on diatomaceous earth for drug analysis in postmortem blood.

Absorption extraction on diatomaceous earth was examined and found to be compatible with typical postmortem blood specimens encountered in forensic toxicology. The effects of solvent, solvent volume, eluate flow rate, and pH on drug recovery and extract quality were investigated. It was concluded that the best method was not necessarily that with the highest recoveries, but that considerations of extract quality were also required. The optimized method was compared with a single-step liquid/liquid extraction method and found to be superior in terms of ease of operation, extract quality, and absolute recovery. The results indicated also that although useful for screening, quantitative methods using liquid/solid extraction may be prone to error.

Chromatography, Gas↗