The death-associated protein kinase 2 is up-regulated during normal myeloid differentiation and enhances neutrophil maturation in myeloid leukemic cells

The death-associated protein kinase 2 (DAPK2) belongs to a family of Ca(2+)/calmodulin-regulated serine/threonine kinases involved in apoptosis. During investigation of candidate genes operative in granulopoiesis, we identified DAPK2 as highly expressed. Subsequent investigations demonstrated particularly high DAPK2 expression in normal granulocytes compared with monocytes/macrophages and CD34(+) progenitor cells. Moreover, significantly increased DAPK2 mRNA levels were seen when cord blood CD34(+) cells were induced to differentiate toward neutrophils in tissue culture. In addition, all-trans retinoic acid (ATRA)-induced neutrophil differentiation of two leukemic cell lines, NB4 and U937, revealed significantly higher DAPK2 mRNA expression paralleled by protein induction. In contrast, during differentiation of CD34(+) and U937 cells toward monocytes/macrophages, DAPK2 mRNA levels remained low. In primary leukemia, low expression of DAPK2 was seen in acute myeloid leukemia samples, whereas chronic myeloid leukemia samples in chronic phase showed intermediate expression levels. Lentiviral vector-mediated expression of DAPK2 in NB4 cells enhanced, whereas small interfering RNA-mediated DAPK2 knockdown reduced ATRA-induced granulocytic differentiation, as evidenced by morphology and neutrophil stage-specific maturation genes, such as CD11b, G-CSF receptor, C/EBPepsilon, and lactoferrin. In summary, our findings implicate a role for DAPK2 in granulocyte maturation.

Is right coronary artery hypoplasia and sudden death an underdiagnosed association?

Determining whether hypoplasia of a coronary artery has caused or contributed to death is often complicated by an absence of histologic evidence of myocardial ischemia in the area of the heart supplied by the affected artery and also by the lack of data for assessing coronary artery size at autopsy. A 45-year-old woman is reported who collapsed and died and who was found at autopsy to have a dominant, small-caliber, right coronary artery, with acute and chronic ischemic changes in the posterior interventricular septum supplied by the diminutive vessel. This case provides evidence that small-caliber coronary arteries may be associated with a lethal outcome. Given the difficulties that may occur in determining whether there is a causal link between small coronary artery caliber and death, it is possible that this may be an underdiagnosed cause of sudden cardiac death, rather than a coincidental finding of minimal significance.

Mechanisms of unexpected death and autopsy findings in Leigh syndrome (subacute necrotising encephalomyelopathy)

A 21-year-old previously-well woman who was undergoing medical investigations for problems with balance and suspected multiple sclerosis, developed a headache and breathing difficulties, and died suddenly and unexpected at home. The autopsy was unremarkable except for pulmonary and cerebral oedema. However, subsequent microscopy of the brain revealed characteristic features of Leigh syndrome with multifocal areas of astrogliosis, capillary proliferation, and parenchymal vacuolation. While Leigh syndrome is more commonly diagnosed in infancy, manifestations may occur throughout early life into adulthood. Sudden and unexpected death is a rare presentation that may be associated with cerebral necrosis and oedema. An awareness of the variable manifestations of Leigh syndrome is necessary in forensic practice as not all cases will present in a typical manner and sudden death may occur before a diagnosis has been established. The heritable nature of this condition makes accuracy of diagnosis essential.