No abstract

Endonuclease G is a mitochondrial protein implicated in DNA fragmentation during apoptosis in cell types ranging from fungi to mammals. Features of programmed cell death have been reported in a number of single-celled organisms, including the human trypanosomatid parasites Leishmania and Trypanosoma. However, the protozoan cell death pathways and the effector molecules involved in such processes remain to be identified. In this report, we describe the pro-apoptotic function of endonuclease G in trypanosomatid parasites. Similar to metazoans, trypanosome endoG showed intrinsic nuclease activity, is localized in mitochondria and is released from this organelle when cell death is triggered. Overexpression of endoG strongly promoted apoptotic cell death under oxidant or differentiation-related stress in Leishmania and, conversely, loss of endoG expression conferred robust resistance to oxidant-induced cell death in T. brucei. These data demonstrate the conservation of the pro-apoptotic endonuclease activity of endoG in these evolutionarily ancient eukaryotic organisms. Furthermore, nuclear DNA degradation by endoG upon release from mitochondria might represent a caspase-independent cell death mechanism in trypanosomatid parasites as genes encoding caspase-like proteins have not been identified in their genomes.

Background & Aims Patients with acute liver failure (ALF) have high mortality and frequently require liver transplantation (LT); few reliable prognostic markers are available. Levels of M30, a cleavage product of cytokeratin-18 caspase, are significantly increased in serum samples from patients with ALF who die or undergo LT. We developed a prognostic index for ALF based on level of M30 and commonly measured clinical variables (called the ALFSG index), and compared its accuracy with that of the King’s College criteria (KCC) and model for end stage liver disease (MELD). We also validated our model in an independent group of patients with ALF. Methods Serum levels of M30 and M65 antigen (the total cytokeratin-18 fragment, a marker of apoptosis and necrosis) were measured on 3 of the first 4 days following admission of 250 patients with ALF. Logistic regression was used to determine if the following factors, measured on day 1, were associated with LT or death: age, etiology; coma grade; international normalized ratio (INR); serum pH; body mass index; levels of creatinine, bilirubin, phosphorus, arterial ammonia, and lactate; and log10M30 and log10M65. The area under the receiver operating characteristic (AUROC) was calculated for the ALFSG and other indices. Results Coma grade, INR, levels of bilirubin and phosphorus, and log10 M30 value at study entry most accurately identified patients that would require LT or die. The ALFSG index identified these patients with 85.6% sensitivity and 64.7% specificity. Based on comparison of AUROC values, the ALFSG Index (AUROC 0.822) better identified patients most likely to require LT or die than the KCC (AUROC 0.654) or MELD (AUROC 0.704) (P=.0002 and P=.0010, respectively). We validated these findings in a separate group of 250 patients with ALF. Conclusions The ALFSG Index, a combination of clinical markers and measurements of the apoptosis biomarker M30, better predicts outcomes of patients with ALF than the KCC or MELD. ClinicalTrials.gov NCT00518440

Broader indications for SI healing of Mohs surgical defects may be appropriate than previously understood. In addition to concave, temporal, periocular, perinasal, and periauricular sites, SI healing may be appropriate for convex sites such as the scalp and anterior lower extremity, deep wounds, and large wounds, as well as wounds with dehiscence, flap necrosis, or infection. Certain patient-specific and lesional factors are also appropriate indications for SI healing.