Microbial carbon turnover in the detritusphere

Microbial decomposition processes at the soil-litter interface involves a complex food web including fungi, bacteria, and archaea that compete for the organic matter. During the decomposition, the nutrient quantity and quality changes as well as the microbial community composition. It is still a challenge to identify and quantify active microbial species in concurrency with their absolute contribution to the carbon (C) turnover. In the frame of the DFG-Project (FOR 918) “Carbon flow in belowground food webs assessed by isotope tracers“ we determined the C flow and turnover of differently aged maize litter in bacteria and fungi of an arable soil. A microcosm experiment was set up with C-13-labeled and unlabeled maize litter on top of soil cores. A reciprocal transplantation of the labeled litter on soil cores with unlabeled litter allowed us to follow the C flow into different microbial groups at the early (0-4d), intermediate (4-12d) and late stage (28-36d) of litter decomposition. We analyzed microbial CO2 respiration, microbial biomass and PLFA pattern in the top 3 mm of the soil cores. To identify and quantify microbial species feeding on the substrate and to assess their degree of C-13 assimilation, DNA stable isotope probing followed by gene-targeted sequencing of bacteria and fungi are currently performed on the soil metagenome. We expected specific microbial communities (copio- and oligotrophic) involved in maize litter decomposition at the different stages of litter decay. During the initial days of the experiment, up to 17% of the CO2-C was maize-derived C. The C-13 content in the CO2 decreased with continuous decomposition of the litter. The highest absolute amount of maize-derived C was found in gram-positive bacteria in the early stage of litter decomposition. For fungi, the highest maize C incorporation was in the intermediate stage of litter decomposition. We calculated a faster C turnover in the fungal biomass than in the bacterial biomass for all three decomposition stages. But during the later stage of litter decomposition, maize-derived C was less utilized by both bacteria and fungi. These results will be concluded by the quantitative DNA-SIP method to provide a species-resolved contribution to the C turnover in the microbial food web at different decomposition stages in the detritusphere

DNA repair capacity as a possible biomarker of breast cancer risk in female BRCA1 mutation carriers

The BRCA1 gene product helps to maintain genomic integrity through its participation in the cellular response to DNA damage: specifically, the repair of double-stranded DNA breaks. An impaired cellular response to DNA damage is a plausible mechanism whereby BRCA1 mutation carriers are at increased risk of breast cancer. Hence, an individual's capacity to repair DNA may serve as a useful biomarker of breast cancer risk. The overall aim of the current study was to identify a biomarker of DNA repair capacity that could distinguish between BRCA1 mutation carriers and non-carriers. DNA repair capacity was assessed using three validated assays: the single-cell alkaline gel electrophoresis (comet) assay, the micronucleus test, and the enumeration of γ-H2AX nuclear foci. DNA repair capacity of peripheral blood lymphocytes from 25 cancer-free female heterozygous BRCA1 mutation carriers and 25 non-carrier controls was assessed at baseline and following cell exposure to γ – irradiation (2 Gy). We found no significant differences in the mean tail moment, in the number of micronuclei or in the number of γ-H2AX nuclear foci between the carriers and non-carriers at baseline, and following γ-irradiation. These data suggest that these assays are not likely to be useful in the identification of women at a high risk for breast cancer

Assessing the quality and communicative aspects of patient decision aids for early-stage breast cancer treatment: a systematic review

Purpose: Decision aids (DAs) support patients in shared decision-making by providing balanced evidence-based treatment information and eliciting patients’ preferences. The purpose of this systematic review was to assess the quality and communicative aspects of DAs for women diagnosed with early-stage breast cancer. Methods: Twenty-one currently available patient DAs were identified through both published literature (MEDLINE, Embase, CINAHL, CENTRAL, and PsycINFO) and online sources. The DAs were reviewed for their quality by using the International Patient Decision Aid Standards (IPDAS) checklist, and subsequently assessed to what extent they paid attention to various communicative aspects, including (i) information presentation, (ii) personalization, (iii) interaction, (iv) information control, (v) accessibility, (vi) suitability, and (vii) source of information. Results: The quality of the DAs varied substantially, with many failing to comply with all components of the IPDAS criteria (mean IPDAS score = 64%, range 31–92%). Five aids (24%) did not include any probability information, 10 (48%) presented multimodal descriptions of outcome probabilities (combining words, numbers, and visual aids), and only 2 (10%) provided personalized treatment outcomes based on patients and tumor characteristics. About half (12; 57%) used interaction methods for eliciting patients’ preferences, 16 (76%) were too lengthy, and 5 (24%) were not fully accessible. Conclusions: In addition to the limited adherence to the IPDAS checklist, our findings suggest that communicative aspects receive even less attention. Future patient DA developments for breast cancer treatment should include communicative aspects that could influence the uptake of DAs in daily clinical practice

Superantigens from Staphylococcus aureus induce procoagulant activity and monocyte tissue factor expression in whole blood and mononuclear cells via IL-1beta.

Background: Staphylococcus aureus is one of the most common bacteria in human sepsis, a condition in which the activation of blood coagulation plays a critical pathophysiological role. During severe sepsis and septic shock microthrombi and multiorgan dysfunction are observed as a result of bacterial interference with the host defense and coagulation systems. Objectives: In the present study, staphylococcal superantigens were tested for their ability to induce procoagulant activity and tissue factor (TF) expression in human whole blood and in peripheral blood mononuclear cells. Methods and results: Determination of clotting time showed that enterotoxin A, B and toxic shock syndrome toxin 1 from S. aureus induce procoagulant activity in whole blood and in mononuclear cells. The procoagulant activity was dependent on the expression of TF in monocytes since antibodies to TF inhibited the effect of the toxins and TF was detected on the surface of monocytes by flow cytometry. In the supernatants from staphylococcal toxin-stimulated mononuclear cells, interleukin (IL)-1beta was detected by ELISA. Furthermore, the increased procoagulant activity and TF expression in monocytes induced by the staphylococcal toxins were inhibited in the presence of IL-1 receptor antagonist, a natural inhibitor of IL-1beta. Conclusions: The present study shows that superantigens from S. aureus activate the extrinsic coagulation pathway by inducing expression of TF in monocytes, and that the expression is mainly triggered by superantigen-induced IL-1beta release