Persistent DNA Damage after High Dose In Vivo Gamma Exposure of Minipig Skin

Exposure to high doses of ionizing radiation (IR) can lead to localized radiation injury of the skin and exposed cells suffer dsDNA breaks that may elicit cell death or stochastic changes. Little is known about the DNA damage response after high-dose exposure of the skin. Here, we investigate the cellular and DNA damage response in acutely irradiated minipig skin.IR-induced DNA damage, repair and cellular survival were studied in 15 cm(2) of minipig skin exposed in vivo to ~50 Co-60 γ rays. Skin biopsies of control and 4 h up to 96 days post exposure were investigated for radiation-induced foci (RIF) formation using γ-H2AX, 53BP1, and active ATM-p immunofluorescence. High-dose IR induced massive γ-H2AX phosphorylation and high 53BP1 RIF numbers 4 h, 20 h after IR. As time progressed RIF numbers dropped to a low of <1% of keratinocytes at 28-70 days. The latter contained large RIFs that included ATM-p, indicating the accumulation of complex DNA damage. At 96 days most of the cells with RIFs had disappeared. The frequency of active-caspase-3-positive apoptotic cells was 17-fold increased 3 days after IR and remained >3-fold elevated at all subsequent time points. Replicating basal cells (Ki67+) were reduced 3 days post IR followed by increased proliferation and recovery of epidermal cellularity after 28 days.Acute high dose irradiation of minipig epidermis impaired stem cell replication and induced elevated apoptosis from 3 days onward. DNA repair cleared the high numbers of DBSs in skin cells, while RIFs that persisted in <1% cells marked complex and potentially lethal DNA damage up to several weeks after exposure. An elevated frequency of keratinocytes with persistent RIFs may thus serve as indicator of previous acute radiation exposure, which may be useful in the follow up of nuclear or radiological accident scenarios

The Effect of DNA-Dependent Protein Kinase on Adeno-Associated Virus Replication

BACKGROUND: DNA-dependent protein kinase (DNA-PK) is a DNA repair enzyme and plays an important role in determining the molecular fate of the rAAV genome. However, the effect this cellular enzyme on rAAV DNA replication remains elusive. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we characterized the roles of DNA-PK on recombinant adeno-associated virus DNA replication. Inhibition of DNA-PK by a DNA-PK inhibitor or siRNA targeting DNA-PKcs significantly decreased replication of AAV in MO59K and 293 cells. Southern blot analysis showed that replicated rAAV DNA formed head-to-head or tail-to-tail junctions. The head-to-tail junction was low or undetectable suggesting AAV-ITR self-priming is the major mechanism for rAAV DNA replication. In an in vitro replication assay, anti-Ku80 antibody strongly inhibited rAAV replication, while anti-Ku70 antibody moderately decreased rAAV replication. Similarly, when Ku heterodimer (Ku70/80) was depleted, less replicated rAAV DNA were detected. Finally, we showed that AAV-ITRs directly interacted with Ku proteins. CONCLUSION/SIGNIFICANCE: Collectively, our results showed that that DNA-PK enhances rAAV replication through the interaction of Ku proteins and AAV-ITRs

Use of Blood Products for Elective Surgery in 43 European Hospitals

The objective of this study was to assess the use of blood products and artificial colloids in six commonly performed elective surgical procedures in 43 teaching hospitals in 10 European countries. 7,195 patient data were analysed. For each product wide differences were found between hospitals, both in the proportion of patients transfused and the amount of product used for the same patient category. Adjustment for age, gender, preoperative haematocrit and blood loss, left major differences among hospitals in patient red unit transfusion. Hospitals in the Mediterranean area used less albumin and artificial colloids and more autotransfusion than those of central-northern Europe. The reasons for perioperative red cell transfusion were stated in the patient's medical record for 23% of patients. The ratio of preoperative blood request to transfusion was maximal in cholecystectomy, where it exceeded 10. The documentation of blood request and transfusion, and of transfusion complications in medical records, did not fully agree with that in the transfusion service in 49, 53 and 92% of the hospitals, respectively. The wide differences in blood product used for the same patient category were due to a variety of causes of which only some could be explained by the clinical factors taken into account. This suggests that consensus conferences and guidelines have so far had a limited impact on transfusion practice in many clinical units, even in teaching environments

Investigating possible regional dependence in strong ground motions

It is common practice to use ground-motion models, often developed by regression on recorded accelerograms, to predict the expected earthquake ground motions at sites of interest. An important consideration when selecting these models is the possible dependence of ground motions on geographical region, i.e., are median ground motions in the (target) region of interest for a given magnitude and distance the same as those in the (host) region where a ground-motion model is from, and are the aleatory variabilities of ground motions also similar? In this brief article, some of the recent literature with relevance to these questions is summarized. It is concluded that although some regions seem to show considerable differences in shaking it is currently more defensible to use well-constrained models, possibly based on data from other regions, rather than use local, often poorly-constrained, models. In addition, it is noted that the presence of "pseudo-regional dependency" due to differences in, for example, focal depths, average shear-wave velocity profiles or focal mechanisms can lead to apparent variations between areas when these variations could be captured in well-characterized ground-motion prediction equations