Cell-free DNA release under psychosocial and physical stress conditions.

The understanding of mechanisms linking psychological stress to disease risk depend on reliable stress biomarkers. Circulating cell-free DNA (cfDNA) has emerged as a potential biomarker of cellular stress, aging, inflammatory processes, and cell death. Recent studies indicated that psychosocial stress and physical exercise might also influence its release. We compared the effects of acute psychosocial and physical exercise stress on cfDNA release by exposing 20 young, healthy men to both an acute psychosocial laboratory stressor and an acute physical exercise stressor. Venous blood and saliva samples were collected before and after stress exposure. Cell-free DNA was extracted from plasma and quantified by qPCR. Furthermore, cfDNA fragment length was analyzed and cfDNA methylation patterns were assayed across time. In addition, release of stress hormones and subjective stress responses were measured. Results showed a twofold increase of cfDNA after TSST and fivefold increase after exhaustive treadmill exercise, with an overabundance of shorter cfDNA fragments after physical exhaustion. Interestingly, cell-free mitochondrial DNA showed similar increase after both stress paradigms. Furthermore, cfDNA methylation signatures-used here as a marker for diverse cellular origin-were significantly different post stress tests. While DNA methylation decreased immediately after psychosocial stress, it increased after physical stress, suggesting different cellular sources of active DNA release. In summary, our results suggest stimulus and cell-specific regulation of cfDNA release. Whereas the functional role of stress-associated cfDNA release remains elusive, it might serve as a valuable biomarker in molecular stress research as a part of the psychophysiological stress response.

Direct and long-term detection of gene doping in conventional blood samples.

The misuse of somatic gene therapy for the purpose of enhancing athletic performance is perceived as a coming threat to the world of sports and categorized as 'gene doping'. This article describes a direct detection approach for gene doping that gives a clear yes-or-no answer based on the presence or absence of transgenic DNA in peripheral blood samples. By exploiting a priming strategy to specifically amplify intronless DNA sequences, we developed PCR protocols allowing the detection of very small amounts of transgenic DNA in genomic DNA samples to screen for six prime candidate genes. Our detection strategy was verified in a mouse model, giving positive signals from minute amounts (20 µl) of blood samples for up to 56 days following intramuscular adeno-associated virus-mediated gene transfer, one of the most likely candidate vector systems to be misused for gene doping. To make our detection strategy amenable for routine testing, we implemented a robust sample preparation and processing protocol that allows cost-efficient analysis of small human blood volumes (200 µl) with high specificity and reproducibility. The practicability and reliability of our detection strategy was validated by a screening approach including 327 blood samples taken from professional and recreational athletes under field conditions.

Antisense transcription: a critical look in both directions.

The mammalian genome contains a large layer of hidden biological information. High-throughput methods have provided new insights into the regulatory networks that orchestrate the "when, where and how" of gene expression, revealing a complex interplay between proteins, regulatory RNAs, and chemical and structural alterations of the genome itself. Naturally occurring antisense transcription has been considered as an important feature in creating transcriptional and hence cellular and organismal complexity. Here, we review the current understanding of the extent, functions and significance of antisense transcription. We critically discuss results from genome-wide studies and documented examples of individual antisense transcripts. So far, the regulatory potential of gene overlaps has been demonstrated only in a few selected cases of experimentally characterized antisense transcripts. Facing the large-scale antisense transcription observed in eukaryotic genomes, it still remains an open challenge to distinguish transcriptional noise from biological function of gene overlapping patterns.

Serologic angiogenesis factors and microvascular density in renal cell carcinoma: two independent parameters.

Renal Cell Carcinoma (RCC) is characterized by high intratumoral microvascular density (iMVD) and significantly elevated serologic titers of angiogenesis factors, basic fibroblast growth factor (bFGF), vascular endothelial growth factor (vEGF) and angiogenin (Ag). The goal of the present study was to find whether a correlation exists between any of these factors and intratumoral microvascular density (iMVD). Serologic angiogenesis factors were determined directly before nephrectomy of a tumorous kidney in 12 patients (average age: 67.6 years [49-78] with localized clear-cell RCC (Robson I-II) (Quantikine', R&D Systems Europe, Abington, UK). Sections were taken in each case from the microscopically most aggressive area of the tumorous kidney preparations. Staining was carried out with a primary antibody against CD31 (DAKO M 0823, Hamburg, Germany). iMVD was counted at 160x magnification at five "hot spots" 200 x 200 microns in size, and the individual factors were then correlated with the areas of maximum and average iMVD (iMVDmax, iMVD-d). Average concentrations of 38 pg/ml +/- 68 were found for bFGF, 712 pg/ml +/- 791 for vEGF, and 358 ng/ml +/- 97 for Ag. iMVDmax was 20 +/- 11 per area, iMVD-d was 410/mm2 +/- 243. No correlation was found between microvascular density and serologic angiogenesis factors for any parameter. Actual tumor vascularization, expressed as iMVD, was not correlated with the 3 angiogenesis parameters which were studied. On the one hand, this raises the question whether angiogenesis can be measured at all with these parameters; on the other, it remains nuclear whether the continuous process of angiogenesis can be registered at all by chronologic, specific factor analysis.

Tacrolimus impairs wound healing: a possible role of decreased nitric oxide synthesis.

BACKGROUND: The effect of the immunosuppressant tacrolimus on wound healing is not known. Tacrolimus has been shown to decrease nitric oxide synthesis. The systemic inhibition of wound nitric oxide synthesis leads to impaired healing. METHODS: We studied the effect of systemic tacrolimus treatment on wound-breaking strength and collagen deposition 10 days after wounding in rats and to correlate the outcome of healing with wound nitric oxide synthesis. Beginning at the day of wounding, rats were treated once daily by intraperitoneal injections with 0.5, 1.0, or 2.0 mg tacrolimus/kg body weight. Nitrite and nitrate were measured in wound fluid as an index of wound nitric oxide synthesis. Expression of inducible nitric oxide synthase in the wound was investigated by immunohistochemistry. Splenic lymphocytes were tested for proliferative activity. Tacrolimus levels in blood and wound fluid were measured by enzyme-linked immunosorbent assay. RESULTS: Systemic tacrolimus treatment was well tolerated by all rats. Tacrolimus accumulated in wound fluid. Tacrolimus levels in wound fluid were found to be approximately 10-fold higher than blood levels (P < 0.001). Tacrolimus (2.0 mg/kg/day) reduced wound-breaking strength (P < 0.01) and collagen deposition (P < 0.05). This was paralleled by decreased wound nitrite + nitrate levels (P < 0.001) and wound-inducible nitric oxide synthase expression. Splenic lymphocyte proliferative activity was significantly decreased by 1.0 and 2.0 mg tacrolimus/kg body weight/day (P < 0.05), indicating that the tacrolimus doses used were immunosuppressive. CONCLUSION: Our data show for the first time that tacrolimus impairs wound healing, and this is reflected by diminished wound nitric oxide synthesis.