Christian Forster

Low-dose radiotherapy selectively reduces adhesion of peripheral blood mononuclear cells to endothelium in vitro☆

BACKGROUND AND PURPOSE The anti-inflammatory effect of low-dose radiotherapy (LD-RT) still is not understood. The adhesion of leukocytes to endothelial cells (EC) of the vessel wall is the initial event of tissue invasion, and thus, crucially contributes to the regulation of inflammation. We investigated the influence of LD-RT on the adhesion process in vitro. MATERIALS AND METHODS Isolated peripheral-blood-mononuclear-cells (PBMC) were incubated with an activated murine endothelioma cell-line under shear conditions at 4 degrees C after irradiation with single doses between 0.1 and 10.0 Gy. Adherent cells were counted microscopically and compared to a non-irradiated control. In parallel, viability and expression of adhesion molecules, especially of L-selectin, and lineage-specific markers on the cell surface were determined by dye exclusion and cytofluorometry, respectively. Modulation of adhesion by soluble L-selectin was tested in the adhesion assay. RESULTS Radiation doses of 0.1-0.5 Gy reduced the adhesion of viable PBMC to EC in vitro by 70% of the control level 4 h after irradiation. Leukocytes showed a marked reduction of L-selectin expression after LD-RT. Soluble L-selectin can inhibit the adhesion of PBMC to EC. CONCLUSION The anti-inflammatory effect of LD-RT might, in part, be due to the reduction in the adhesion of PBMC to EC. This reduction in adhesion might be a consequence of the reduced expression of L-selectin on the surface of PBMC, and the inhibition of adherence by soluble L-selectin shed by PBMC in vitro.

In vitro apoptosis in peripheral blood mononuclear cells induced by low-dose radiotherapy displays a discontinuous dose-dependence

PURPOSE Cells undergoing apoptosis contribute to the regulation of activated mononuclear cells (Voll et al. 1997). Low-dose radiotherapy (LD-RT) is known to improve inflammatory symptoms, but the mechanism of action is still unclear. The aim of this study was to investigate the rate of apoptosis of peripheral blood mononuclear cells (PBMC) induced by LD-RT within the therapeutic dose range of anti-inflammatory RT. MATERIALS AND METHODS PBMC were isolated from venous blood of ten healthy volunteers and were irradiated with single doses between 0.1 and 3.0 Gy. Apoptotic nuclei were detected by flow cytometry after propidium iodide (PI) triton staining, and apoptotic cells were detected by annexin V/PI staining and cell scatter analysis. Since apoptotic cells display increased cytoplasmatic granularity and concomitant reduced cell size, they can be distinguished from viable cells in forward/side scatter (FSC/SSC) histograms. Apoptotic PBMC were further subtyped by double staining with annexin V and directly labelled monoclonal antibodies recognizing the lineage-specific surface markers CD4, CD8, and CD19, respectively. The apoptosis rate of irradiated cells was analysed in a time and dose dependent fashion and was compared to a sham-irradiated control. RESULTS After irradiation, a dose-dependent increase in apoptosis was observed, with a discontinuity (plateau or peak) between 0.3Gy and 0.7Gy in 9/10 donors (90%) and 59/80 samples (74%). 8/10 donors (80%) and 38/80 samples (47%) showed not only a discontinuous increase with a plateau but a relative maximum of apoptosis peaking within the dose range of 0.3 Gy and up to 0.7 Gy. CONCLUSION LD-RT induces a relative maximum of apoptosis in PBMC in the does range between 0.3 Gy and 0.7 Gy. This may contribute to its anti-inflammatory effect observed clinically.

Low-flow CO 2 removal integrated into a renal-replacement circuit can reduce acidosis and decrease vasopressor requirements

IntroductionLung-protective ventilation in patients with ARDS and multiorgan failure, including renal failure, is often paralleled with a combined respiratory and metabolic acidosis. We assessed the effectiveness of a hollow-fiber gas exchanger integrated into a conventional renal-replacement circuit on CO2 removal, acidosis, and hemodynamics.MethodsIn ten ventilated critically ill patients with ARDS and AKI undergoing renal- and respiratory-replacement therapy, effects of low-flow CO2 removal on respiratory acidosis compensation were tested by using a hollow-fiber gas exchanger added to the renal-replacement circuit. This was an observational study on safety, CO2-removal capacity, effects on pH, ventilator settings, and hemodynamics.ResultsCO2 elimination in the low-flow circuit was safe and was well tolerated by all patients. After 4 hours of treatment, a mean reduction of 17.3 mm Hg (−28.1%) pCO2 was observed, in line with an increase in pH. In hemodynamically instable patients, low-flow CO2 elimination was paralleled by hemodynamic improvement, with an average reduction of vasopressors of 65% in five of six catecholamine-dependent patients during the first 24 hours.ConclusionsBecause no further catheters are needed, besides those for renal replacement, the implementation of a hollow-fiber gas exchanger in a renal circuit could be an attractive therapeutic tool with only a little additional trauma for patients with mild to moderate ARDS undergoing invasive ventilation with concomitant respiratory acidosis, as long as no severe oxygenation defects indicate ECMO therapy.

Comparison of Plasma and Urine Biomarker Performance in Acute Kidney Injury

Background New renal biomarkers measured in urine promise to increase specificity for risk stratification and early diagnosis of acute kidney injury (AKI) but concomitantly may be altered by urine concentration effects and chronic renal insufficiency. This study therefore directly compared the performance of AKI biomarkers in urine and plasma. Methods This single-center, prospective cohort study included 110 unselected adults undergoing cardiac surgery with cardiopulmonary bypass between 2009 and 2010. Plasma and/or urine concentrations of creatinine, cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), liver fatty acid-binding protein (L-FABP), kidney injury molecule 1 (KIM1), and albumin as well as 15 additional biomarkers in plasma and urine were measured during the perioperative period. The primary outcome was AKI defined by AKIN serum creatinine criteria within 72 hours after surgery. Results Biomarkers in plasma showed markedly better discriminative performance for preoperative risk stratification and early postoperative (within 24h after surgery) detection of AKI than urine biomarkers. Discriminative power of urine biomarkers improved when concentrations were normalized to urinary creatinine, but urine biomarkers had still lower AUC values than plasma biomarkers. Best diagnostic performance 4h after surgery had plasma NGAL (AUC 0.83), cystatin C (0.76), MIG (0.74), and L-FAPB (0.73). Combinations of multiple biomarkers did not improve their diagnostic power. Preoperative clinical scoring systems (EuroSCORE and Cleveland Clinic Foundation Score) predicted the risk for AKI (AUC 0.76 and 0.71) and were not inferior to biomarkers. Preexisting chronic kidney disease limited the diagnostic performance of both plasma and urine biomarkers. Conclusions In our cohort plasma biomarkers had higher discriminative power for risk stratification and early diagnosis of AKI than urine biomarkers. For preoperative risk stratification of AKI clinical models showed similar discriminative performance to biomarkers. The discriminative performance of both plasma and urine biomarkers was reduced by preexisting chronic kidney disease.

UVB-irradiated T-cells undergoing apoptosis lose L-selectin by metalloprotease-mediated shedding

PURPOSE L-selectin (CD62L) is a prerequisite for leucocyte adhesion to endothelial cells of blood vessels and consequently for transmigration. Its expression on the cell surface therefore regulates the ability of lymphocytes to enter lymph nodes, to re-enter blood vessels or to invade tissues at sites of inflammation. The aim of this study was to determine the expression of CD62L on apoptotic lymphocytes after UVB irradiation. MATERIALS AND METHODS Peripheral blood mononuclear cells (PBMC) were isolated from peripheral blood of normal healthy volunteers. Cells were stimulated with phorbol myristate acetate (PMA) and ionomycin for activation. Apoptosis in peripheral T-cells and Jurkat cells was induced by irradiation with UVB (120 mJ/cm2). In addition, T-cells or Jurkat cells were cultured for the indicated time with anti-Fas antibody CH11. The CH11-induced apoptosis was inhibited by the pan-caspase inhibitor zVAD-fmk. For detection of apoptosis, cells were analysed by cytofluorometry for morphological changes typical for apoptosis. The reliability of the apoptotic cell gate was confirmed by staining with FITC-labelled annexin-V in the presence ofpropidium iodide (PI). For FACS analysis of CD62L expression on the cell-surface immunofluorescence was performed using FITC-conjugated anti-CD62L and PE-conjugated anti-CD3 antibodies. Soluble CD62L (sCD62L) in the cell supernatants was measured by standard ELISA technique. Assays were performed in the presence and absence of metalloprotease inhibitor KB8301. RESULTS PBMC from healthy volunteers undergoing apoptosis following UVB irradiation selectively shed CD62L, whereas the expression of the lineage-specific marker CD3 showed only minor changes. Shedding was blocked by the hydroxamic acid-based metalloprotease inhibitor KB8301. When Jurkat cells were treated with the caspase inhibitor zVAD-fmk, anti-CD95 antibodies did not induce apoptosis, and the expression of CD62L remained unaltered. CONCLUSION UVB or ionizing radiation induce apoptosis in lymphocytes. The loss of CD62L is associated with apoptosis and will influence lymphocyte trafficking and, by excluding them from CD62L-mediated adhesion and tissue invasion, might contribute to the regulation of inflammation.Abstract. Purpose : L-selectin (CD62L) is a prerequisite for leucocyte adhesion to endothelial cells of blood vessels and consequently for transmigration. Its expression on the cell surface therefore regulates the ability of lymphocytes to enter lymph nodes, to re-enter blood vessels or to invade tissues at sites of inflammation. The aim of this study was to determine the expression of CD62L on apoptotic lymphocytes after UVB irradiation. Materials and methods : Peripheral blood mononuclear cells (PBMC) were isolated from peripheral blood of normal healthy volunteers. Cells were stimulated with phorbol myristate acetate (PMA) and ionomycin for activation. Apoptosis in peripheral T-cells and Jurkat cells was induced by irradiation with UVB (120 mJ/cm2). In addition, T-cells or Jurkat cells were cultured for the indicated time with anti-Fas antibody CH11. The CH11-induced apoptosis was inhibited by the pan-caspase inhibitor zVAD-fmk. For detection of apoptosis, cells were analysed by cytofluorometry for morphological changes typical for apoptosis. The reliability of the apoptotic cell gate was confirmed by staining with FITClabelled annexin-V in the presence of propidium iodide (PI). For FACS analysis of CD62L expression on the cell-surface immunofluorescence was performed using FITC-conjugated anti-CD62L and PE-conjugated anti-CD3 antibodies. Soluble CD62L (sCD62L) in the cell supernatants was measured by standard ELISA technique. Assays were performed in the presence and absence of metalloprotease inhibitor KB8301. Results : PBMC from healthy volunteers undergoing apoptosis following UVB irradiation selectively shed CD62L, whereas the expression of the lineage-specific marker CD3 showed only minor changes. Shedding was blocked by the hydroxamic acid-based metalloprotease inhibitor KB8301. When Jurkat cells were treated with the caspase inhibitor zVAD-fmk, anti-CD95 antibodies did not induce apoptosis, and the expression of CD62L remained unaltered. Conclusion : UVB or ionizing radiation induce apoptosis in lymphocytes. The loss of CD62L is associated with apoptosis and will influence lymphocyte tra Ýcking and, by excluding them from CD62L-mediated adhesion and tissue invasion, might contribute to the regulation of inflammation.

The odds of running a nonlinear TV program using web technologies

Facing the problem of realizing a nonlinear TV program with all its requirements the usage of bare web technologies is proposed. Based on previous work a concept to enable nonlinear TV experience over any IP network is presented. Furthermore the chances of using unmodified web technologies and protocols for displaying and handling communication are highlighted. Special emphasis has been laid on being independent from a return channel, providing the possibility to use this framework for unidirectional broadcast systems (e.g. DVB-H). This paper focuses on such aspects as authoring, the database task for the abstraction layer, the push concept, playlist retrieval and channel switching.

Towards a Computable Data Corpus of Temporal Correlations between Drug Administration and Lab Value Changes

Background The analysis of electronic health records for an automated detection of adverse drug reactions is an approach to solve the problems that arise from traditional methods like spontaneous reporting or manual chart review. Algorithms addressing this task should be modeled on the criteria for a standardized case causality assessment defined by the World Health Organization. One of these criteria is the temporal relationship between drug intake and the occurrence of a reaction or a laboratory test abnormality. Appropriate data that would allow for developing or validating related algorithms is not publicly available, though. Methods In order to provide such data, retrospective routine data of drug administrations and temporally corresponding laboratory observations from a university clinic were extracted, transformed and evaluated by experts in terms of a reasonable time relationship between drug administration and lab value alteration. Result The result is a data corpus of 400 episodes of normalized laboratory parameter values in temporal context with drug administrations. Each episode has been manually classified whether it contains data that might indicate a temporal correlation between the drug administration and the change of the lab value course, whether such a change is not observable or whether a decision between those two options is not possible due to the data. In addition, each episode has been assigned a concordance value which indicates how difficult it is to assess. This is the first open data corpus of a computable ground truth of temporal correlations between drug administration and lab value alterations. Discussion The main purpose of this data corpus is the provision of data for further research and the provision of a ground truth which allows for comparing the outcome of other assessments of this data with the outcome of assessments made by human experts. It can serve as a contribution towards systematic, computerized ADR detection in retrospective data. With this lab value curve data as a basis, algorithms for detecting temporal relationships can be developed, and with the classification made by human experts, these algorithms can immediately be validated. Due to the normalization of the lab value data, it allows for a generic approach rather than for specific or solitary drug/lab value combinations.

Enhancements in DVB-H and DVB-SH Based Mobile-TV Multiplexing

Energy efficient broadcasting of mobile-TV content through DVB-H and DVB-SH suffers from signaling limitations introduced by the DVB-H and DVB-SH multiplexing scheme resulting in an increased system delay. This paper presents a novel scheduling and multiplexing approach to overcome these limitations. The proposed algorithm allows to trade time slicing efficiency for lower system delay and more flexible data rate assignments possibly resulting in better video quality. The algorithm is evaluated through extensive cross layer simulations for different parameter sets.