Elevated Postmortem Vitreous Sodium and Chloride Level in a Salt Water Drowning Death During Self-Contained Underwater Breathing Apparatus Diving With Diving Mask in Place: Case Report.

Elevation of postmortem vitreous sodium and chloride (PMVSC) levels in salt water drowning (SWD) is hypothesized to result from electrolyte changes in blood from salt water inhalation/ingestion during drowning. After approximately 1 hour after death, electrolytes may diffuse into the vitreous humor via the eye coverings. This hypothesis was based on a study where bovine eyeballs were immersed in salt water. There is no human study that could confirm that SWD would result in an initial elevation of PMVSC with no effects from immersion. We present an SWD during self-contained underwater breathing apparatus diving in which the face mask remained in its correct position while the deceased was underwater. The face mask would have prevented the orbits from being in direct contact with salt water and therefore stopped any effects of immersion on PMVSC. The PMVSC was 294 mmol/L, above control levels, and the reported cut-off of 259 mmol/L for a diagnosis SWD. The elevated PMVSC would unlikely be owing to immersion but SWD. This case report supports the observation that during SWD PMVSC would initially increase from salt water inhalation and ingestion and not from immersion.

Sudden Cardiac Death Due to Deficiency of the Mitochondrial Inorganic Pyrophosphatase PPA2.

We have used whole-exome sequencing in ten individuals from four unrelated pedigrees to identify biallelic missense mutations in the nuclear-encoded mitochondrial inorganic pyrophosphatase (PPA2) that are associated with mitochondrial disease. These individuals show a range of severity, indicating that PPA2 mutations may cause a spectrum of mitochondrial disease phenotypes. Severe symptoms include seizures, lactic acidosis, cardiac arrhythmia, and death within days of birth. In the index family, presentation was milder and manifested as cardiac fibrosis and an exquisite sensitivity to alcohol, leading to sudden arrhythmic cardiac death in the second decade of life. Comparison of normal and mutant PPA2-containing mitochondria from fibroblasts showed that the activity of inorganic pyrophosphatase was significantly reduced in affected individuals. Recombinant PPA2 enzymes modeling hypomorphic missense mutations had decreased activity that correlated with disease severity. These findings confirm the pathogenicity of PPA2 mutations and suggest that PPA2 is a cardiomyopathy-associated protein, which has a greater physiological importance in mitochondrial function than previously recognized.

Two fatal cases of immersion pulmonary oedema - using dive accident investigation to assist the forensic pathologist.

Immersion pulmonary oedema (IPE) is being increasingly recognized in swimmers, snorkellers and scuba divers presenting with acute symptoms of respiratory distress following immersion, but fatal case reports are uncommon. We report two fatal cases of probable IPE in middle-aged women, one whilst snorkelling and the other associated with a scuba dive. In the snorkeller's case, an episode of exercise-related chest tightness and shortness of breath that occurred 10 months previously was investigated but this proved negative, and she was on no medications. However, at autopsy, moderate left ventricular hypertrophy was noted. The scuba diver had suffered several previous episodes of severe shortness of breath following dives, one being so severe it led to cyanosis and impaired consciousness. At inquest, the pathologist's diagnosis was given as drowning and IPE was not mentioned. Expert input from doctors trained in diving medicine should be compulsory in the investigation of diving deaths, and forensic pathologists should be properly trained in and have guidelines for the conduct of post-immersion and post-diving autopsies.

Could intra-alveolar hemosiderin deposition in adults be used as a marker for previous asphyxial episodes in cases of autoerotic death?

Intra-alveolar hemorrhage and hemosiderin have been cited as possible markers of recent and remote asphyxial events. Little study has been undertaken of the potential significance of intra-alveolar hemosiderin in adults as a potential marker of previous sublethal asphyxial episodes. Ten cases of lethal sexual asphyxia (an entity known to be associated with repetitive sublethal asphyxial episodes) and 20 randomly selected, age- and sex-matched controls had sections of lung stained for hemosiderin. Subsequently, intra-alveolar, iron-containing macrophages were counted. All cases were men (ages 15-50 years; mean 31.8). No significant increase in hemosiderin was found in victims of sexual asphyxia, indicating that asphyxial episodes in sublethal sexual asphyxial activities may not be sufficiently intense or prolonged to cause intra-alveolar hemorrhage or that intra-alveolar hemorrhage in adults is a relatively nonspecific finding. These results do not support intra-alveolar hemosiderin deposition as a marker for previous sublethal asphyxial events in autoerotic asphyxia.

Displacement matrix elements of Deng-Fan oscillators.

Analytic expressions for matrix elements of integral powers of the displacement of the coordinate from equilibrium for the Deng-Fan oscillator have been derived. A comparison is made with the corresponding matrix elements for the Morse oscillator. These matrix elements are useful in high overtone spectroscopy and in models for DNA melting.

Artefactual contraction band necrosis of the myocardium in fatal air crashes.

BACKGROUND: The detection of conditions associated with possible medical incapacitation is a crucial component of the aviation autopsy. Acute myocardial ischemia is notoriously difficult to diagnose at autopsy, although various pathological markers may strongly support a diagnosis of acute myocardial infarction occurring just prior to the crash. HYPOTHESIS: Contraction band necrosis may not be a reliable indicator of acute myocardial ischemia in aircraft crashes because of the forces on myocardial tissue sustained in the crash. METHODS: Microscopic examination of the myocardium of fatal air crash occupants was compared with a control group of suicidal hanging deaths. This study examined 80 air crash fatalities and 44 age and sex matched suicidal ligature hanging controls. We assessed both the presence and extent of contraction band necrosis type lesions in both groups and scored the lesions. RESULTS: Contraction band lesions were seen in the left ventricular myocardium of all study groups. There was no significant difference between the contraction band score for crash victim deaths and hanging deaths. However, widespread contraction banding was significantly more common in air crash victims (p = 0.032). There was no significant difference between contraction banding in victims of impacts without a post-crash fire compared with those in crashes with a post-crash fire. CONCLUSIONS: Contraction band necrosis-like lesions in isolation should not be considered as evidence of acute myocardial ischemia in cases of massive trauma. Severe trauma, possibly as a result of sudden stretching of the cardiac myocytes, may cause a microscopic lesion which is indistinguishable from contraction band necrosis.

Site-site potentials in neopentane and tetramethylsilane.

Neopentane and TMS are used as model M(CH(3))(4) systems to investigate intramolecular interactions. The nonbonded site-site potential between two proximal hydrogen atoms on different methyl groups, V(nb)(d(HH)), is not Lennard-Jones- or Morse-like but is found to be pseudolinear in hydrogen-hydrogen internuclear separation, d(HH), for both neopentane and TMS. The Morse potential is found to be a poor basis in which to expand V(nb)(d(HH)). The nonbonded site-site potential is conformation-dependent and not transferable between molecules. The individual contributions to V(nb)(d(HH)) are presented. The local mode parameters for neopentane and TMS are calculated ab initio for a variety of molecular conformations. The ab initio values of the local mode frequency and local mode anharmonicity are increasingly blue-shifted with increasing steric hindrance. Electron correlation is found to be increasingly important with decreasing internuclear separations, d(HH).