Biomedical subjects
D J Pounder
Publications and source records attributed to D J Pounder.
Prevalence of HIV antibody in forensic cases.
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Postmortem toxico-kinetics of co-proxamol.
Postmortem drug redistribution in suicidal poisonings by co-proxamol (dextropropoxyphene and paracetamol) has been studied. Analytical data for 8 tissue samples, including muscle and fat, up to 8 blood samples, and gastric and small bowel contents were obtained in 4 cases. Blood samples were taken from multiple sites at the start of autopsy and after 24 or 48 h. Concentrations of both drugs were site dependent with the lowest concentrations in peripheral blood. Paracetamol concentrations varied two to threefold and propoxyphene concentrations varied seven to tenfold. Pulmonary artery concentrations of paracetamol did not change significantly with time; propoxyphene concentrations typically increased twofold over 24 h and threefold over 48 h. Propoxyphene concentrations in the inferior vena cava increased unpredictably but occasionally significantly (up to sevenfold). For both drugs the most dramatic elevations of blood concentrations were seen in the aorta; in one case paracetamol rose to 1.9 g/l, 8 times the peripheral blood concentration and 4 times the liver level (454 mg/kg); propoxyphene rose to 191.5 mg/l, 55 times the peripheral blood concentration. This appears to reflect postmortem diffusion of unabsorbed drug from the gastric lumen. It is likely that markedly higher concentrations in the putrefactive fluid from the left pleural cavity as compared with the right also reflect diffusion from the stomach.
Evaluating suspected co-proxamol overdose.
In three instances of suicidal poisoning by co-proxamol (paracetamol and dextropropoxyphene) blood samples were obtained from 11 sites together with eight tissue samples, bile, urine, gastric contents and duodenal contents. Site-dependent differences in blood propoxyphene concentration varied between the three cases but concentrations were consistently lowest in peripheral blood and highest in central sites: 3.9-5.5 (pulmonary vein) mg/l; 4.6-25 (pulmonary vein) mg/l; 3.2-40 (aorta) mg/l. There was a less than twofold variation in corresponding blood paracetamol concentrations. Reference data on fatal propoxyphene blood concentrations do not specify the blood sampling site and can be misleading. The intra-individual variability of propoxyphene concentrations in blood in these three cases underscores this problem. Tissue concentrations of propoxyphene showed considerable inter-individual variability in degree and pattern. Tissue concentrations of paracetamol showed a less than twofold intra-individual variation. Body drug loads were calculated by two methods: from organ weights and tissue concentrations; from published volume of distribution data (Vd). For paracetamol the body drug load is underestimated by the organ weight calculation but the Vd calculation approximates the suspected dose based on anamnestic information. For propoxyphene the body drug load is seriously underestimated by the organ weight calculation and overestimated up to 2.5 times by the Vd calculation. Since the two drugs have a fixed ratio in co-proxamol then the dose of propoxyphene (the effective lethal agent) can be inferred from the paracetamol dose calculated by Vd. This approach may be applicable to cases of overdose with other compounded drug preparations.
Efficacy of cerebro-spinal fluid biochemistry in the diagnosis of brain insult.
Postmortem biochemical indices may provide a useful adjunct to morphological studies in the identification of antemortem brain insult. We studied 34 routine medico-legal cases categorising them into one of four diagnostic groups. There were 11 cases of head trauma, 7 of 'hypoxia' (3 hangings and 4 carbon monoxide or drug poisonings), 7 sudden cardiac deaths and 9 miscellaneous cases. Survival time and postmortem interval was known for each case. The degree of cranio-cerebral trauma was graded. Cerebro-spinal fluid (CSF) and vitreous humour were analysed for calcium, glucose, total proteins, aldolase, aspartate transaminase (AST), alanine transaminase (ALT), gamma glutamyltransferase (GGT), lactate dehydrogenase (LDH), creatine kinase (CK) and creatine kinase BB isoenzyme (CK-BB). CK-BB was also measured in superior vena cava serum. In CSF there was a significant correlation between the severity of cranio-cerebral trauma and levels of aldolase, CK-BB, AST, ALT and total proteins. CSF CK-BB, median units/l (range), for the groupings of head trauma, hypoxia, sudden cardiac death and miscellaneous were respectively 823 (2-3431); 96 (2-187); 4 (2-25); 5 (1-69). Corresponding serum CK-BB levels were 240 (28-322); 390 (26-411); 180 (20-482); 79 (18-530).
Post-mortem toxico-kinetics of trazodone.
Trazodone is a structurally unique bicyclic anti-depressant, said to be significantly less toxic than other anti-depressants following an acute overdose. We studied the tissue distribution and post-mortem redistribution of trazodone in two fatalities, one of which allowed comparison with trimipramine, a typical tricyclic anti-depressant. Case 1, a 53-year-old female weighing 72 kg, had femoral vein concentrations of trimipramine 5.5 micrograms/ml, trazodone 14.4 micrograms/ml and alcohol 107 mg%. Case 2, a 48-year-old female of 70 kg, had a femoral vein trazodone of 15.5 micrograms/ml and alcohol 34 mg%, with no other drugs detected. For case 1 and case 2 respectively, trazodone tissue concentrations were: skeletal muscle 7.3 and 9.0 micrograms/g; left and right lungs 13.3, 12.9 and 35.3, 40.1; myocardium, 30.9 and 28.9; kidneys 34.7 and 39.6; liver 73.7 and 82.4; fat 18.5 and 16.5; brain 48.6 and 20.9. For case 1 and 2, respectively, blood trazodone concentrations in 10 initial autopsy samples ranged from 13.7-17.3 and 14.4-16.9 micrograms/ml. Twenty-four and forty-eight hours later the respective ranges were 12.8-18.0 and 12.4-19.9 for case 1, 12.5-20.1 and 12.7-27.0 for case 2. By contrast, for trimipramine, blood concentrations at 0 time, 24 h and 48 hours ranged from 5.5-11.4, 5.2-14.3, and 4.2-18.2, respectively. We conclude that trazodone shows little preferential concentration in solid organs and consequently has relatively stable post-mortem blood concentrations with little drug redistribution artefact. Both the clinical pharmacokinetics and post-mortem toxicokinetics of trazodone differ significantly from the tricyclic anti-depressants.
Postmortem absorption of drugs and ethanol from aspirated vomitus--an experimental model.
Using human cadavers an experimental model was developed to simulate the agonal aspiration of drug- and alcohol-laden vomitus. By needle puncture, an acidified (N/20 HCl) 60-ml slurry of drugs (paracetamol 3.25 g, dextropropoxyphene 325 mg) and ethanol 3% w/v was introduced into the trachea. After 48 h undisturbed at room temperature, blood samples were obtained from ten sites. Ethanol and drug concentrations were highest in the pulmonary vessels in all five cases studied. Pulmonary vein mean ethanol was 58 mg% (range 13-130), paracetamol 969 mg/l (range 284-1934), propoxyphene 70 mg/l (range 11-168). Pulmonary artery mean ethanol was 53 mg% (range 10-98), paracetamol 476 mg/l (range 141-882), propoxyphene 29 mg/l (range 7.6-80). Ethanol and drug concentrations in aortic blood were higher than in the left heart and concentrations in the superior vena cava were higher than in the right heart, suggesting direct diffusion into these vessels rather than diffusion via the pulmonary and cardiac blood. Potential interpretive problems arising from this phenomenon can be avoided by using femoral vein blood for quantitative toxicological analysis.
Changing patterns of male suicide in Scotland.
Mortality statistics published annually by the Registrar General Scotland for 1970-1989 are analysed. There has been a recent increase in the suicide rate amongst younger males in Scotland which cannot be explained by changes in the misattribution between suicides (ICD E950-E959) and undetermined deaths (ICD E980-E989). The increase is almost entirely attributable to hanging and the use of motor vehicle exhaust fumes. Analysis of the sex/age/method-specific suicide rates demonstrates that age-specific increases in the male suicide rate are linked to age-specific increases in the use of these two methods. The increased suicide rate involving motor vehicle exhaust fumes can be explained by changes in method availability and acceptability. The increased suicide rate involving hanging may be explained by increased acceptability, possibly flowing from the abolition of judicial hanging in 1965. The increased suicide rate in younger males may reflect a change in the proportion of suicidal attempts resulting in a completed suicide consequent on an age-specific shift to the use of more lethal methods, namely hanging and motor vehicle exhaust fumes. This possibility needs to be evaluated before assessing the influence of other social factors on the suicide rate.
Post-mortem drug redistribution--a toxicological nightmare.
Detailed human case data is presented to illustrate the dramatic extent of the phenomenon of post-mortem drug redistribution. The data suggests that there is a post-mortem diffusion of drugs along a concentration gradient, from sites of high concentration in solid organs, into the blood with resultant artefactual elevation of drug levels in blood. Highest drug levels were found in central vessels such as pulmonary artery and vein, and lowest levels were found in peripheral vessels such as subclavian and femoral veins. In individual cases, in multiple blood samples obtained from ligated vessels, concentrations of doxepin and desmethyldoxepin ranged from 3.6 to 12.5 mg/l and 1.2 to 7.5 mg/l, respectively; amobartital, secobarbital and pentobarbital from 4.3 to 25.8 mg/l, 3.9 to 25.3 mg/l and 5.1 to 31.5 mg/l respectively; clomipramine and desmethylclomipramine from 4.0 to 21.5 mg/l and 1.7 to 8.1 mg/l, respectively and flurazepam 0.15 to 0.99 mg/l; imipramine and desipramine from 4.1 to 18.1 mg/l and 1.0 to 3.6 mg/l, respectively. We conclude that this poorly studied phenomenon creates major difficulties in interpretation and undermines the reference value of data bases where the site of origin of post-mortem blood samples is unknown.
Spinocerebral faecal migration in a shotgun injury.
Migration of foreign material within the subarachnoid space is a rare event, seldom reported in the medical literature. We report a unique case in which spinocerebral migration of faecal material occurred as a direct consequence of a shotgun injury to the pelvis.
Sudden death and left ventricular outflow disease.
Aortic stenosis is a well-recognized cause of sudden death, but in our experience, it is uncommon as the sole cause of sudden death. The most common overall cause of AS is the calcified congenitally bicuspid valve. There is an increased incidence of subaortic stenosis in relatives of patients with subaortic stenosis, although Mendelian inheritance has not been reported. Supravalvular AS may be an autosomal dominant with variable penetrance, it may be sporadic, or it may be one of the manifestations of Williams' syndrome. The principal mechanisms of sudden death in AS appear to be due to (1) activation of left ventricular baroreceptors which causes reflex bradycardia and cardiac arrhythmias, or (2) arrhythmias as complications of LVH. Myocardial ischemia has been anatomically proven and may be due to diastolic compression of intramural coronary arteries. Aortic dissection occurs with increased frequency in patients with a bicuspid aortic valve. Heart block can result from calcification of the bundle of His in AS of any cause. Supravalvular AS may be complicated by adherence of an aortic valve cusp to the aorta resulting in coronary ostial stenosis, and coronary narrowing by intimal hyperplasia. AS at any level may lead to IE, which has been responsible for occasional sudden deaths.
Forensic entomo-toxicology.
Drugs present in a decomposing corpse may be identified through analysis of maggots feeding off it. Case reports in forensic entomo-toxicology are sparse and the data base is unstructured. Drug concentrations should be measured in residual skeletal muscle, the principal food source for fly larvae, as well as in washed maggots, and the fly species should be determined. An untested possibility is the analysis of puparia or puparial cases which could extend the time frame for analysis into years or even into palaeopathology. In deaths indoors, the analysis of flies known to have emerged from the corpse is a theoretical possibility. To what extent drugs are retained in successive levels of the food chain is entirely unknown; drugs might be detectable in beetles feeding off fly larvae.
The Peden case: an Australian forensic disaster.
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