Evaluation of skin irritation following weathered crude oil exposure in two mouse strains.

Petroleum crude oil spills are common and vary in size and scope. Spill response workers throughout the course of remediation are exposed to so-called weathered oil and are known to report diverse health effects, including contact dermatitis. A murine model of repeated exposure to weathered marine crude oil was employed utilizing two strains of mice, C57BL/6 and BALB/c, to investigate the pathology of this irritant and identify the principal hydrocarbon components deposited in skin. Histopathology demonstrated clear signs of irritation in oil-exposed skin from both mouse strains, characterized by prominent epidermal hyperplasia (acanthosis). BALB/c mice exposed to oil demonstrated more pronounced irritation compared with C57BL/6 mice, which was characterized by increased acanthosis as well as increased inflammatory cytokine/chemokine protein expression of IL-1ß, IL-6, CXCL10, CCL2, CCL3, CCL4, and CCL11. A gas chromatography/mass spectrometry method was developed for the identification and quantification of 42 aliphatic and EPA priority aromatic hydrocarbons from full thickness skin samples of C57BL/6 and BALB/c mice exposed to oil samples. Aromatic hydrocarbons were not detected in skin; however, aliphatic hydrocarbons in skin tended to accumulate with carbon numbers greater than C16. These preliminary data and observations suggest that weathered crude oil is a skin irritant and this may be related to specific hydrocarbon components, although immune phenotype appears to impact skin response as well.

Time- and temperature-dependent postmortem ∆9-tetrahydrocannabinol concentration changes in rabbits following controlled inhaled cannabis administration.

ostmortem redistribution (PMR), a well-known phenomenon in forensic toxicology, can result in substantial changes in drug concentrations after death, depending on the chemical characteristics of the drug, blood collection site, storage conditions of the body and postmortem interval (PMI). Limited PMR data are available for ∆9-tetrahydrocannabinol (THC), the primary psychoactive component in Cannabis sativa. PMR was evaluated after controlled cannabis inhalation via a smoking machine and exposure chamber in New Zealand white rabbits. Necropsies were performed on five control rabbits immediately after euthanasia, whereas 27 others were stored at room temperature (21°C) or refrigerated conditions (4°C) until necropsy at 2, 6, 16, 24 or 36 h after death. THC and its Phase I and glucuronidated Phase II metabolites were quantified in blood, vitreous humor, urine, bile and tissues by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Under refrigerated temperature, heart blood THC concentrations significantly increased at PMI 2 h in rabbits, whereas peripheral blood THC concentrations showed a significant increase at PMI 16 h. Central:peripheral blood and liver:peripheral blood ratios for THC ranged from 0.13 to 4.1 and 0.28 to 8.9, respectively. Lung revealed the highest THC concentrations, while brain and liver exhibited the most stable THC concentrations over time. This report contributes much needed data to our understanding of postmortem THC behavior and can aid toxicologists in the interpretation of THC concentrations in medicolegal death investigations.

Predicting in vivo cardiovascular properties of ß-blockers from cellular assays: a quantitative comparison of cellular and cardiovascular pharmacological responses.

ß-Adrenoceptor antagonists differ in their degree of partial agonism. In vitro assays have provided information on ligand affinity, selectivity, and intrinsic efficacy. However, the extent to which these properties are manifest in vivo is less clear. Conscious freely moving rats, instrumented for measurement of heart rate (ß1; HR) and hindquarters vascular conductance (ß2; HVC) were used to measure receptor selectivity and ligand efficacy in vivo. CGP 20712A caused a dose-dependent decrease in basal HR (P<0.05, ANOVA) at 5 doses between 6.7 and 670 µg/kg (i.v.) and shifted the dose-response curve for isoprenaline to higher agonist concentrations without altering HVC responses. In contrast, at doses of 67 µg/kg (i.v.) and above, ICI 118551 substantially reduced the HVC response to isoprenaline without affecting HR responses. ZD 7114, xamoterol, and bucindolol significantly increased basal HR (ΔHR: +122 ± 12, + 129 ± 11, and + 59 ± 11 beats/min, respectively; n=6), whereas other ß-blockers caused significant reductions (all at 2 mg/kg i.v.). The agonist effects of xamoterol and ZD 7114 were equivalent to that of the highest dose of isoprenaline. Bucindolol, however, significantly antagonized the response to the highest doses isoprenaline. An excellent correlation was obtained between in vivo and in vitro measures of ß1-adrenoceptor efficacy (R(2)=0.93; P<0.0001).

Cannabinoid distribution in fatally-injured pilots' postmortem fluids and tissues.

The primary psychoactive component of cannabis, Δ9-tetrahydrocannabinol (THC) impairs cognitive function and psychomotor performance, particularly for complex tasks like piloting an aircraft. The Federal Aviation Administration's (FAA) Forensic Sciences Section at the Civil Aerospace Medical Institute (Oklahoma City, OK) performs toxicological analyses on pilots fatally injured in general aviation incidents, permitting cannabinoids measurement in a broad array of postmortem biological specimens. Cannabinoid concentrations in postmortem fluids and tissues from 10 pilots involved in airplane crashes are presented. Median (range) THC blood concentration was 1.6 (1.0-13.7) ng/mL. Phase I metabolites, 11-hydroxy-THC (11-OH-THC) and 11-nor-9-carboxy-THC (THCCOOH) and phase II glucuronide metabolite, THCCOOH-glucuronide, had median (range) blood concentrations of 1.4 (0.5-1.8), 9.9 (2.2-72.6) and 36.6 (7.1-160) ng/mL, respectively. Urine analyses revealed positive results for THCCOOH, THC-glucuronide, THCCOOH-glucuronide and 11-nor-9-carboxy-Δ9-tetrahydrocannabivarin (THCVCOOH). THC was readily distributed to lung, brain, kidney, spleen and heart. The psychoactive metabolite, 11-OH-THC, was identified in liver and brain with median (range) concentrations 7.1 (3.5-10.5) and 2.4 (2.0-6.0) ng/g, respectively. Substantial THCCOOH and THCCOOH-glucuronide concentrations were observed in liver, lung, brain, kidney, spleen and heart. These cannabinoid concentrations from multiple types of postmortem specimens add to the limited postmortem cannabinoid research data and suggest useful biological matrices for investigating cannabinoid-related deaths.

Identification and quantification of cannabinoids in postmortem fluids and tissues by liquid chromatography-tandem mass spectrometry.

Cannabis sativa is commonly used worldwide and is frequently detected by forensic laboratories working with biological specimens from potentially impaired drivers or pilots. To address the problem of limited published methods for cannabinoids quantification in postmortem specimens, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to quantify Δ9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), 11-nor-9-carboxy-THC (THCCOOH), 8ß,11-dihydroxy-THC (8ß-diOH-THC), 8ß-hydroxy-THC (8ß-OH-THC), THC-glucuronide (THC-g), THCCOOH-glucuronide (THCCOOH-g), cannabidiol (CBD), cannabinol (CBN), cannabigerol (CBG), Δ9-tetrahydrocannabivarin (THCV), and 11-nor-9-carboxy-THCV (THCVCOOH). Solid phase extraction concentrated analytes prior to analysis on a biphenyl column coupled to a mass spectrometer in electrospray positive ionization mode using multiple reaction monitoring. Linearity ranged from 0.25-50 ng/mL (THC-g), 0.5-100 ng/mL (CBN), 0.5-250 ng/mL (THC, 11-OH-THC, THCCOOH, CBD, and CBG), 1-100 ng/mL (8ß-diOH-THC, THCVCOOH, 8ß-OH-THC, and THCV) and 1-250 ng/mL (THCCOOH-g). Within-run imprecision was <11.2% CV, between-run imprecision <18.1% CV, and bias was less than ±15.1% of target concentration in blood for all cannabinoids at three concentrations. No carryover or interferences were observed. All cannabinoids were stable in blood at room temperature for 24 h, refrigerated (4°C) for 96 h, and following three freeze/thaw cycles. Matrix effects greater than 25% were observed for most analytes in tissues. The proof of concept for method applicability involved measurement of cannabinoids in a pilot fatally injured in an aviation crash. This new analytical method is robust and sensitive, enabling collection of additional cannabinoid postmortem distribution data to improve interpretation of postmortem cannabinoid results.

Haslea silbo, A Novel Cosmopolitan Species of Blue Diatoms.

Specimens of a new species of blue diatoms from the genus Haslea Simonsen were discovered in geographically distant sampling sites, first in the Canary Archipelago, then North Carolina, Gulf of Naples, the Croatian South Adriatic Sea, and Turkish coast of the Eastern Mediterranean Sea. An exhaustive characterization of these specimens, using a combined morphological and genomic approach led to the conclusion that they belong to a single new to science cosmopolitan species, Haslea silbo sp. nov. A preliminary characterization of its blue pigment shows similarities to marennine produced by Haslea ostrearia, as evidenced by UV-visible spectrophotometry and Raman spectrometry. Life cycle stages including auxosporulation were also observed, providing data on the cardinal points of this species. For the two most geographically distant populations (North Carolina and East Mediterranean), complete mitochondrial and plastid genomes were sequenced. The mitogenomes of both strains share a rare atp6 pseudogene, but the number, nature, and positions of the group II introns inside its cox1 gene differ between the two populations. There are also two pairs of genes fused in single ORFs. The plastid genomes are characterized by large regions of recombination with plasmid DNA, which are in both cases located between the ycf35 and psbA genes, but whose content differs between the strains. The two sequenced strains hosts three plasmids coding for putative serine recombinase protein whose sequences are compared, and four out of six of these plasmids were highly conserved.

Opening angles and material properties of the early embryonic chick brain.

Mechanical forces play an important role during brain development. In the early embryo, the anterior end of the neural tube enlarges and differentiates into the major brain subdivisions, including three expanding vesicles (forebrain, midbrain, and hindbrain) separated by two constrictions. Once the anterior neuropore and the spinal neurocoel occlude, the brain tube undergoes further regional growth and expansion in response to increasing cerebrospinal fluid pressure. Although this is known to be a response to mechanical loads, the mechanical properties of the developing brain remain largely unknown. In this work, we measured regional opening angles (due to residual stress) and stiffness of the embryonic chick brain during Hamburger-Hamilton stages 11-13 (approximately 42-51 h incubation). Opening angles resulting from a radial cut on transverse brain slices were about 40-110 deg (depending on region and stage) and served as an indicator of circumferential residual stress. In addition, using a custom-made microindentation device and finite-element models, we determined regional indentation stiffness and material properties. The results indicate that the modulus is relatively independent of position and stage of development with the average shear modulus being about 220 Pa for stages 11-13 chick brains. Information on the regional material properties of the early embryonic brain will help illuminate the process of early brain morphogenesis.

Cohort differences in exercise adherence among primary care patients referred for mental health versus physical health conditions.

Aim To compare the characteristics of mental health and physical health participants attending an exercise referral scheme (ERS) and investigate associations with their adherence to exercise. BACKGROUND: While people referred to an ERS with a mental health diagnosis have similar initial rates of uptake as physical health participants, they are more likely to drop out. Comparisons of the groups to understand their differences and how these might impact on their adherence have been limited by the typically low numbers of mental health referrals in many schemes. METHODS: Retrospective analysis of a participant cohort. Data were extracted on all participants enrolled over a 12- month period (n = 701) and included measurements at baseline, mid-point (13 weeks) and end of programme (20-26 weeks). Differences were explored between the mental health (n=141) and physical health (n=560) subcohorts, and between adherers and non-adherers in each group. Binomial logistic regression estimated the effect of group-level factors associated with adherence. Findings Mental health referrals were more likely to be younger, White and unemployed, and had a lower mean body mass index and lower proportion of participants with high blood pressure. They were also more likely to drop out. While occupation was associated with exercise adherence among the physical health group, no predictive factors were identified in the mental health group. CONCLUSION: Participants referred for mental health disorders are more likely to drop out of exercise referral schemes than those with physical health problems. While no factors were found to be predictive of their exercise adherence, an understanding of their distinguishing characteristics and attendance behaviour can guide in making better referral decisions concerning them and planning more appropriately tailored support.

Regional heterogeneity in the haemodynamic responses to urotensin II infusion in relation to UT receptor localisation.

The aim of the study was to measure regional haemodynamic responses to 6 h infusions of human urotensin II (hUII), to identify possible mediators of the effects observed, and to relate the findings to the distribution of urotensin II receptors (UT receptors). Male, Sprague-Dawley rats had pulsed Doppler flow probes and intravascular catheters implanted for measurement of regional haemodynamics in the conscious, freely moving state. Infusions of saline (0.4 ml h(-1)) or hUII (30, 300 and 3,000 pmol kg(-1) h(-1)) were given i.v. for 6 h, and the effects of pretreatment with indomethacin (5 mg kg(-1) h(-1)), N(G)-nitro-L-arginine methyl ester (L-NAME, 3 mg kg(-1) h(-1)) or propranolol (1 mg kg(-1); 0.5 mg kg(-1) h(-1)) on responses to hUII (300 pmol kg(-1) h(-1) for 6 h) were assessed. Cellular localisation of UT receptor-like immunoreactivity was determined in relevant tissues. hUII caused dose-dependent tachycardia and hindquarters vasodilatation, accompanied by a slowly developing rise in blood pressure. Haemodynamic effects of hUII were attenuated by propranolol or L-NAME and abolished by indomethacin. UT receptor-like immunoreactivity was detected in skeletal and vascular smooth muscle. The findings indicate that in conscious rats, infusions of hUII cause vasodilatation, which, of the vascular beds monitored, is selective for the hindquarters and dependent on cyclooxygenase products and nitric oxide. The pressor effect of hUII under these conditions is likely to be due to an increase in cardiac output, possibly due to a positive inotropic effect. UT receptor-like immunoreactivity present in skeletal muscle is consistent with the haemodynamic pattern.

A work-based learning approach for clinical support workers on mental health inpatient wards.

Background With a rise in the number of unqualified staff providing health and social care, and reports raising concerns about the quality of care provided, there is a need to address the learning needs of clinical support workers. This article describes a qualitative evaluation of a service improvement project that involved a work-based learning approach for clinical support workers on mental health inpatient wards. Aim To investigate and identify insights in relation to the content and process of learning using a work-based learning approach for clinical support workers. Method This was a qualitative evaluation of a service improvement project involving 25 clinical support workers at the seven mental health inpatient units in South London and Maudsley NHS Foundation Trust. Three clinical skills tutors were appointed to develop, implement and evaluate the work-based learning approach. Four sources of data were used to evaluate this approach, including reflective journals, qualitative responses to questionnaires, three focus groups involving the clinical support workers and a group interview involving the clinical skills tutors. Data were analysed using thematic analysis. Findings The work-based learning approach was highly valued by the clinical support workers and enhanced learning in practice. Face-to-face learning in practice helped the clinical support workers to develop practice skills and reflective learning skills. Insights relating to the role of clinical support workers were also identified, including the benefits of face-to-face supervision in practice, particularly in relation to the interpersonal aspects of care. Conclusion A work-based learning approach has the potential to enhance care delivery by meeting the learning needs of clinical support workers and enabling them to apply learning to practice. Care providers should consider how the work-based learning approach can be used on a systematic, organisation-wide basis in the context of budgetary restrictions.

Paroxetine in Postmortem Fluids and Tissues from Nine Aviation Accident Victims.

Paroxetine is a selective serotonin reuptake inhibitor commonly prescribed for the treatment of depression, obsessive-compulsive disorder, panic disorder, social anxiety disorder and post-traumatic stress disorder. While the use of paroxetine is considered relatively safe, negative side effects, including nausea, drowsiness, insomnia and dizziness, can adversely affect a pilot's ability to safely operate an aircraft. The use of paroxetine may increase suicidal behavior and suicidal ideation. When relying on postmortem specimens for toxicological evaluation, a general understanding of drug distribution throughout postmortem specimens is important. This laboratory has determined the distribution of paroxetine in postmortem tissues and fluids from nine aviation accident fatalities. Specimens were processed using an n-butyl chloride liquid/liquid extraction followed by gas chromatographic/mass spectrometeric analysis. Blood paroxetine concentrations obtained from these cases ranged from 0.019 to 0.865 µg/mL. The distribution of paroxetine, expressed as mean specimen/blood ratio, was 1.67 ± 1.16 urine (n = 4), 0.08 ± 0.04 vitreous humor (n = 6), 5.77 ± 1.37 liver (n = 8), 9.66 ± 2.58 lung (n = 9), 1.44 ± 0.57 kidney (n = 8), 3.80 ± 0.69 spleen (n = 8), 0.15 ± 0.04 muscle (n = 8), 4.27 ± 2.64 brain (n = 7) and 1.05 ± 0.43 heart (n = 8). The large standard deviations associated with the paroxetine distribution coefficients suggest that paroxetine can experience significant postmortem concentration changes.

Distribution of ∆(9)-Tetrahydrocannabinol and 11-Nor-9-Carboxy-∆(9)-Tetrahydrocannabinol Acid in Postmortem Biological Fluids and Tissues From Pilots Fatally Injured in Aviation Accidents.

Little is known of the postmortem distribution of ∆(9)-tetrahydrocannabinol (THC) and its major metabolite, 11-nor-9-carboxy-∆(9)-tetrahydrocannabinol (THCCOOH). Data from 55 pilots involved in fatal aviation accidents are presented in this study. Gas chromatography/mass spectrometry analysis obtained mean THC concentrations in blood from multiple sites, liver, lung, and kidney of 15.6 ng/mL, 92.4 ng/g, 766.0 ng/g, 44.1 ng/g and mean THCCOOH concentrations of 35.9 ng/mL, 322.4 ng/g, 42.6 ng/g, 138.5 ng/g, respectively. Heart THC concentrations (two cases) were 184.4 and 759.3 ng/g, and corresponding THCCOOH measured 11.0 and 95.9 ng/g, respectively. Muscle concentrations for THC (two cases) were 16.6 and 2.5 ng/g; corresponding THCCOOH, "confirmed positive" and 1.4 ng/g. The only brain tested in this study showed no THC detected and 2.9 ng/g THCCOOH, low concentrations that correlated with low values in other specimens from this case. This research emphasizes the need for postmortem cannabinoid testing and demonstrates the usefulness of a number of tissues, most notably lung, for these analyses.

Bolus injection of human UII in conscious rats evokes a biphasic haemodynamic response.

A biphasic cardiovascular response to bolus i.v. injection of human urotensin II (hUII, 3 nmol kg(-1)) in conscious, male, Sprague-Dawley (SD) rats was identified and underlying mechanisms were explored. Initially (0-5 min) there was tachycardia, hypotension and mesenteric and hindquarters vasodilatation; later (30-120 min), tachycardia, hindquarters vasodilatation and a modest rise in blood pressure occurred. Pretreatment with indomethacin or N(G) nitro-l-arginine methylester (l-NAME) reduced the mesenteric vasodilator response to hUII, and abolished the late tachycardia and hindquarters vasodilatation. Indomethacin also abolished the hypotension and early hindquarters vasodilatation, and substantially reduced the initial tachycardia. Indomethacin and l-NAME together prevented all haemodynamic responses to hUII. Inhibition of inducible NOS had no effect on responses to hUII, whereas inhibition of neuronal NOS reduced the delayed tachycardic response to hUII but did not significantly affect the vasodilatation. Only the initial tachycardic response to hUII was antagonised by propranolol. In spontaneously hypertensive rats (SHR), the initial haemodynamic responses to hUII were qualitatively similar to those in SD rats, although there was also a modest renal vasodilatation. The secondary response comprised a smaller tachycardia and a small rise in blood pressure, with no significant hindquarters vasodilatation. Haemodynamic responses to hUII were not enhanced by endothelin and angiotensin receptor antagonism in either SD rats or in SHRs. One interpretation of these results is that the primary response to bolus injection of hUII is prostanoid- or prostanoid- and NO-mediated (mesenteric vasodilatation) and that this triggers secondary events, which are dependent on eNOS (hindquarters vasodilatation) and neuronal NOS (tachycardia).

Haemodynamic effects of the selective phosphodiesterase 5 inhibitor, UK-357,903, in conscious SHR.

1. Regional haemodynamic responses to a continuous, 4-day infusion of the selective phosphodiesterase type 5 inhibitor, UK-357,903 (0.133 or 1.33 mg x kg(-1) h(-1)) were measured in conscious spontaneously hypertensive rats, and compared with those of enalapril (1 mg x kg(-1) h(-1)). 2. Both doses of UK-357,903 caused modest reductions in mean blood pressure that were not dose-dependent and only significantly different from the vehicle effects on Day 1 of the study (mean -11.8 and -15.3 mmHg for low and high doses, respectively). UK-357,903 had mesenteric and hindquarters vasodilator effects, which were, again, similar for both dose levels and only significantly different from vehicle on Day 1. Neither dose of UK-357,903 affected renal vascular conductance or heart rate. 3. Although the haemodynamic effects of UK-357,903 were not clearly dose-related and some appeared to wane with time, geometric mean plasma levels of UK-357,903 increased in proportion to dose, and were sustained throughout the infusion period. Furthermore, plasma cyclic guanosine monophosphate, a biomarker of phosphodiesterase 5 inhibition, was persistently elevated, and increased with increasing dose. 4. Enalapril caused a fall in mean blood pressure on day 1 (-14.1 mmHg) that was associated with dilatation in renal, mesenteric and hindquarters vascular beds. The haemodynamic effects of enalapril were sustained or increased over the 4-day infusion, although plasma free drug levels were stable. 5. In conclusion, we have shown regional and temporal changes in the haemodynamic effects of UK-357,903, which may be due to activation of compensatory mechanisms, but there were no signs of functional compensation to the cardiovascular effects of enalapril.

Comparative regional haemodynamic effects of the nitric oxide synthase inhibitors, S-methyl-L-thiocitrulline and L-NAME, in conscious rats.

1. The regional haemodynamic effects of the putative nNOS inhibitor, S-methyl-L-thiocitrulline (SMTC), were compared with those of the nonselective NOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), in conscious, male Sprague-Dawley rats. 2. SMTC (0.3 mg kg(-1) bolus) produced a significant, short-lived, pressor effect associated with renal, mesenteric and hindquarters vasoconstriction; the same dose of L-NAME did not affect mean blood pressure (BP), although it caused bradycardia and mesenteric vasoconstriction. 3. At the highest dose tested (10 mg kg(-1)), L-NAME produced a significantly greater bradycardia and fall in mesenteric vascular conductance than SMTC, although the initial pressor response to SMTC was greater, but less sustained, than that to L-NAME. 4. Infusion of SMTC or L-NAME (3 mg kg(-1) h(-1)) induced rises in BP and falls in renal, mesenteric and hindquarters vascular conductances, but the effects of L-NAME were greater than those of SMTC, and L-NAME also caused bradycardia. 5. The renal vasodilator response to acetylcholine was markedly attenuated by infusion of L-NAME, but unaffected by SMTC. The hindquarters vasodilatation induced by salbutamol was attenuated by L-NAME, but not by SMTC. The mesenteric vasodilator response to bradykinin was modestly enhanced by SMTC, but not by L-NAME. The depressor and renal, mesenteric and hindquarters vasodilator responses to sodium nitroprusside were enhanced by L-NAME, whereas SMTC modestly enhanced the hypotensive and renal vasodilator effects of sodium nitroprusside, but attenuated the accompanying tachycardia. 6. The results are consistent with the cardiovascular effects of low doses of SMTC being attributable to nNOS inhibition.

Acute marihuana (THC) exposure produces a "transient" topographic quantitative EEG profile identical to the "persistent" profile seen in chronic heavy users.

In two published pilot studies and a controlled replication using screened normals, chronic marihuana (THC) use was associated with a unique topographic quantitative EEG profile, consisting of significant elevations of Absolute and Relative Power and Coherence of alpha activity over the bilateral frontal cortex as well as a significant decrease in alpha frequency. This report attempts to establish the causal influence of THC in the above findings by the transient production of this exact quantitative EEG profile in subjects who did not display it at the beginning. Using paced smoking of marihuana with high and low dose THC content and placebo marihuana in a counterbalanced design under double blind conditions, all four of the topographic features of chronic THC exposure were produced as transient effects by THC but not by placebo.

Validation of a microtiter plate ELISA for screening of postmortem blood for opiates and benzodiazepines.

The object of this study was to evaluate the suitability of the Neogen Corp. microtiter plate enzyme-linked immunoassays (ELISA) for opiates and benzodiazepines for screening of postmortem blood. Ninety postmortem whole blood specimens were obtained from drug-involved deaths which had been screened and confirmed positive for opiates and/or benzodiazepines. Forty negative specimens were obtained from non-opiate-involved deaths. Specimens were tested using the Neogen Opiates Group and Neogen Benzodiazepines Group microtiter plate ELISA assays. No matrix effects were found for whole blood in these assays and a dilution of 1:5 was chosen to facilitate pipetting and to bring the IC50 of the microtiter plate ELISA assay within the range of opiates and benzodiazepines encountered in medical examiner specimens. True positive, true negatives, false positives, and false negatives were determined and graphed for the ELISA results against gas chromatography-mass spectrometry (GC-MS), gas chromatography-nitrogen-phosphorus detection and case histories. From these graphs and the ROC curves, the optimal cut-off for the Neogen Opiates Group ELISA was found to be between 20 and 50 ng/mL morphine equivalents and the optimum cut-off for the Neogen Benzodiazepines Group ELISA was between 20 and 50 ng/mL temazepam equivalents. The Neogen Opiates Group ELISA had a sensitivity of 95.2% +/- 2.7% and a specificity of 92.2% +/- 3.4% versus GC-MS at a cut-off of 20-ng/mL cut-off and a sensitivity of 88.8% +/- 3.9% and specificity of 96.8% +/- 2.1% versus GC-MS at a 50-ng/mL morphine equivalents cut-off. The Neogen Benzodizepines Group ELISA had a sensitivity of 100% +/- 1.3% and a specificity of 94.6% +/- 2.9% versus GC-MS (20-ng/mL temazepam equivalents cut-off) and a sensitivity of 95.8% +/- 2.5% and specificity of 98.2% +/- 1.8% versus GC-MS at a 50-ng/mL cut-off.

Choice of an ELISA assay for screening postmortem blood for amphetamine and/or methamphetamine.

The object of this study was to evaluate the suitability of the Neogen Corp. microtiter plate enzyme-linked immunoassays (ELISA) for the screening of postmortem blood for amphetamine and methamphetamine and to choose the more appropriate assay for screening. Forty-seven postmortem whole blood specimens were obtained from drug-involved deaths, which had been screened and confirmed positive for methamphetamine and/or amphetamine. Eighty-five negative specimens were obtained from non-amphetamines-involved deaths, 17 of which involved decomposition. Specimens were tested using the Neogen Amphetamine Ultra and Neogen Methamphetamine/MDMA microtiter plate ELISA assays. No matrix effects were found for whole blood in these assays, and a dilution of 1:5 was chosen to facilitate pipetting and to bring the IC50 of the microtiter plate ELISA assay within the range of amphetamines concentrations encountered in medical examiner specimens. True positives, true negatives, false positives, and false negatives were determined relative to gas chromatography-mass spectrometry (GC-MS) and graphed for the ELISA. From these graphs and the receiver operating curves (ROC), the optimal cut-off for the Neogen Methamphetamine/MDMA ELISA was 50 ng/mL methamphetamine equivalents and the optimum cut-off for the Neogen Amphetamine Ultra ELISA was 100 ng/mL amphetamine equivalents. The Neogen Methamphetamine ELISA had a sensitivity of 93.6% +/- 3.5% and a specificity of 77.6% +/- 4.5% versus GC-MS at the cut-off of 50-ng/mL methamphetamine equivalents. The Neogen Amphetamine Ultra ELISA had a sensitivity of 95.7% +/- 3.0% and a specificity of 72.9% +/- 5.2% versus GC-MS at the 100-ng/mL amphetamine equivalents cut-off. The areas under the ROCs were equivalent for the two ELISA assays.