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Arrhythmogenic right ventricular dysplasia (ARVD) is a poorly understood and often underdiagnosed disorder of the right ventricle, characterized by replacement of myocardium by fibroadipose tissue, arrhythmic manifestations, and sudden death. The disease occurs in families and is inherited as an autosomal dominant trait. This report describes five cases of ARVD identified by autopsy. In three of the cases, sudden death occurred in the young (16-28 years old) during or shortly after exercise. In another case, a 46-year-old man with no relevant medical history was found dead in his bathroom. In the last case, a 57-year-old woman died from pulmonary thromboembolism. In none of the subjects had the disease been diagnosed or suspected before death. Only one (a 21-year-old man) had previous typical symptoms of the disease. Autopsy examination showed right ventricle dilation and, in four cases, cardiomegaly. The right ventricular myocardium of all hearts was almost replaced by adipose tissue and to a variable degree by fibrous tissue, while the left ventricle myocardium demonstrated no, or only scattered, fibro-fatty infiltration. Postmortem diagnosis of ARVD can be important in identifying possible affected family members in order to initiate treatment.

Mercury vapor produces tremor in humans and experimental animals. We have previously reported that mercury vapor intoxication over an 8-week period induces only subtle changes in dorsal root ganglia and nerve roots in rats. In the present study we have carried out stereological analyses of the cerebellum of the same rats, and demonstrated significant losses of Purkinje cells (12.7%, 2P = 0.005) and granule cells (15.6%, 2P = 0.016). All sizes of Purkinje cells were lost with an equal probability, i.e. there were no indication of any preferential loss of any subpopulation of the neurons. The volume of the granular cell layer was significantly reduced (18.9%, 2P = 0.0 15), whereas the volumes of the molecular layer and the white matter were unchanged. Previous stereological studies have demonstrated that methyl mercury intoxication primarily induces degeneration in the peripheral nervous system, while sparing the cerebellum. We therefore suggest that metallic mercury vapor and methyl mercury have different toxicological profiles in rats, where metallic mercury vapor mainly affects the central nervous system and methyl mercury mainly affects the peripheral nervous system.

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Schionning JD, Danscher G. Autometallographic mercury correlates with degenerative changes in dorsal root ganglia of rats intoxicated with organic mercury. APMIS 1999;107:303-10.Organic mercury intoxication in rats produces degenerative changes in the dorsal root ganglia and dorsal nerve roots. In a previous study of rats treated with organic mercury (2 mg/kg ) for 19 days, significant losses of ganglion cells (especially A-cells) and myelinated axons were observed in dorsal nerve roots and there was qualitative evidence of glial cell proliferation and the formation of Nageotte bodies (1). In the present study, the autometallographic silver-enhancement technique, for tracing inorganic mercury bound to sulphide or selenide (AMG-Hg), was applied to tissue sections of dorsal root ganglia and dorsal nerve roots of the same rats used in the earlier study. Satellite cells and macrophages that surrounded ganglion cells and formed Nageotte bodies were heavily labelled by coarse deposits of AMG-Hg, while the labelling of ganglion cells was less pronounced. A-cells were consistently labelled, while B-cells were only occasionally labelled. In the dorsal nerve roots, only a few AMG-Hg deposits could be seen in macrophages. At the ultrastructural level, AMG-Hg was observed within lysosomes of target cells. It is concluded that AMG-Hg is primarily located in glial cells and that the pattern of deposition of AMG-Hg is the same as that for the morphological changes observed in rats intoxicated with organic mercury.