Ischemia‐reperfusion injury. A phenomenon,that also occurs in the bone

Ischemia‐reperfusion injury of the bone occurs due to traumatic and non‐traumatic alterations affecting blood supply to the bone. It is likely to occur also upon insertion of an implant. Ischemia‐reperfusion injury of the bone has been studied by interruption of blood supply in situ, in limb replantation/transplantation models, in revascularized bone grafts and non‐vascularized bone fragments, as well as in isolated cultured cells. All cells of the bone are affected, including osteoblasts, osteocytes, osteoclasts, chondrocytes, and bone marrow cells. Critical ischemia times for induction of bone cell death, either in the ischemic period or following reperfusion, are in the range of 3 to 7 h. These critical ischemia times are significantly increased by decreasing the temperature from 37 °C to 0–4 °C. Anoxia is the most likely trigger of cell injury in the ischemic phase. In the reperfusion phase, reactive oxygen species are decisively involved in the injurious process. In general, however, the available information on the mechanism of ischemia‐reperfusion injury of the bone is relatively sparse. On the other hand, there are clear similarities to the mechanisms of ischemia‐reperfusion injury known from other organs, and there is a clear potential for protection against ischemia‐reperfusion injury of the bone.     

Flood risk mapping at European scale.

The aim of this article is to illustrate a framework for flood risk mapping at pan-European scale produced by the Weather-Driven Natural Hazards (WDNH) action of the EC-JRC-IES. Early results are presented in the form of flood risk index maps. We assess several flood risk factors that contribute to the occurrence of flood disasters. Among the causal factors of a flood disaster one is triggering a natural event in the form of extreme precipitation and consequently extreme river discharge and extreme flood water levels. The threatening natural event represents the hazard component in our assessment. Furthermore exposure and vulnerability are anthropogenic factors that contribute also to flood risk. In the proposed approach, flood risk is considered on the light of exposure, vulnerability and hazard. We use a methodology with a marked territorial approach for the assessment of the flood risk. Hence, based on mathematical calculations, risk is the product of hazard, exposure and vulnerability. Improvements on datasets availability and spatial scale are foreseen in the next phases of this study. This study is also a contribution to the discussion about the need for communication tools between the natural hazard scientific community and the political and decision making players in this field.     

Longitudinal analysis of semiconductor lasers with low reflectivity facets

An analysis is made of longitudinal effects in semiconductor lasers with low facet reflectivities. For this purpose, a self-consistent model is used based on the beam propagation method, which takes into account both the lateral and longitudinal dimension. The calculations show that longitudinal effects have a significant influence on the output fields in the laser.     

Adjuvant arthritis: influence of the adjuvant volume and composition on the non-specific inflammation

Adjuvant-induced arthritis is an animal model of chronic inflammatory disease widely used in anti-inflammatory and immunosuppressive drugs testing. When the development and the inhibition of the induced arthritis are measured by the injected paw oedema, it is difficult to delineate the immunological contribution from the persistent non-specific primary section. To study the influence of volume and composition of the injected adjuvant upon the primary non-specific inflammation, we devised a 3X4 factorial experiment on a strain of inbred rats with a low susceptibility to adjuvant-induced arthritis. The injection of mineral oil alone produces a persistent oedema. The injection of mycobacteriae in suspension in saline induces a rapid inflammatory response followed by a fast decrease of the oedema. When complete adjuvant is used, there is always a very strong interaction between the effects of the two components of the adjuvant, i.e. the measured oedemas are much greater than the calculated values, For a given injected volume, the inflammation is maximum when the concentration of mycobacteriae is 2.5 mg/ml. All the rats injected with complete adjuvant present a transient oedema of the non-injected hind paw. This oedema is very small and proportional to the amount of mycobacteria injected.     

Spatial learning deficits in mice with a targeted glucocorticoid receptor gene disruption

Previous studies in rats using the Morris water maze suggested that the processing of spatial information is modulated by corticosteroid hormones through mineralocorticoid and glucocorticoid receptors in the hippocampus. Mineralocorticoid receptors appear to be involved in the modulation of explorative behaviour, while additional activation of glucocorticoid receptors facilitates the storage of information. In the present study we used the water maze task to examine spatial learning and memory in mice homozygous and heterozygous for a targeted disruption of the glucocorticoid receptor gene. Compared with wild-type controls, homozygous and heterozygous mice were impaired in the processing of spatial but not visual information. Homozygous mutants performed variably during training, without specific platform-directed search strategies. The spatial learning disability was partly compensated for by increased motor activity. The deficits were indicative of a dysfunction of glucocorticoid receptors as well as of mineralocorticoid receptors. Although the heterozygous mice performed similarly to wild-type mice with respect to latency to find the platform, their strategy was more similar to that of the homozygous mice. Glucocorticoid receptor-related long-term spatial memory was impaired. The increased behavioural reactivity of the heterozygous mice in the open field points to a more prominent mineralocorticoid receptor-mediated function. The findings indicate that (i) the glucocorticoid receptor is of critical importance for the control of spatial behavioural functions, and (ii) mineralocorticoid receptor-mediated effects on this behaviour require interaction with functional glucocorticoid receptors. Until the development of site-specific, inducible glucocorticoid receptor mutants, glucocorticoid receptor-knockout mice present the only animal model for the study of corticosteroid-mediated effects in the complete absence of a functional receptor.     

Experimental and model investigations of bleaching and saturation of fluorescence in flow cytometry

We investigated the fluorescence emission from three fluorophores commonly used for labeling cells in flow cytometry. We have demonstrated that the fluorescence emission from cells labeled with fluorescein-isothiocyanate (FITC), phycoerythrin (PE), and allophycocyanin (APC) is considerably saturated and bleached in standard flow cytometric conditions. Therefore, for optimization of fluorescence detection in a flow cytometer, it is important to know the emission kinetics in detail. We made a mathematical model of the optical processes involved: absorption, fluorescence emission, nonradiative decay, photodestruction, and triplet state occupation. The validity of the model was experimentally tested with a set of averaged fluorescence pulses, measured in a large range of intensities and illumination times. The fluorescence of APC could be completely described by the model and produced the following rate constants: photodestruction rate kb1 = 6 x 10(3) s(-1), triplet state population rate k12 = 2 x 10(5) s(-1), and depopulation rate k20 = 5 x 10(4) s(-1). The fluorescence kinetics of FITC- and PE-labeled cells could not be fitted with only three parameters over the entire range, indicating that other optical processes are involved. We used the model to determine the sensitivity of our flow cytometer and to calculate the optimum conditions for the detection of APC. The results show that in principle a single APC molecule on a cell can be detected in the presence of background, i.e., autofluorescence and Raman scattering by water.     

Trypanosoma cruzi: nitrogenous-base-containing phosphatides in trypomastigote forms--isolation and chemical analysis

Increasingly clinicians attempt to base decisions regarding patient management on the results of clinical studies in addition to expert opinion and their own practical experience. In this article, the author reviews the published studies available to assist clinicians to make evidence-based decisions in three topics related to small volume red blood cell (RBC) transfusions for preterm infants; namely, studies examining the effects of RBC transfusions on possible symptoms of anemia such as tachypnea, apnea or other cardiorespiratory irregularities, studies investigating the collection and transfusion of umbilical cord blood and finally studies addressing the duration of storage and use of additive solutions for RBCs for transfusion to neonates. Based on the review of these studies, guidelines for small volume RBC transfusions in preterm infants are suggested.