Space weather phenomena on heart rate: a study in the Greek region.

Many scientific investigations have focused on how space weather phenomena, taking place in the vicinity of the Earth, may influence different aspects of life on Earth and presumably human health itself. From 2005, the National and Kapodistrian University of Athens has established an important position in the field of these investigations by collaborating with various scientists and Institutes, both international and domestic, in different heliobiological projects. In this work, the Cosmic Ray Group of the National and Kapodistrian University of Athens has co-operated with the medical staff from different hospitals and clinics around the country so as to develop large records of medical data (heart rate) which covers a long time period. These data are analyzed in regard to physical activity, either on a daily basis or on different levels of geomagnetic disturbances and variations of the cosmic ray intensity using the ANalysis Of Variance (ANOVA) and the multiple linear regression analysis. Results suggest that space weather phenomena may be related to heart rate variability, i.e., heart rate is statistically significantly effected either by variations of cosmic rays intensity or geomagnetic activity.

The Duffy antigen receptor for chemokines transports chemokines and supports their promigratory activity.

The Duffy antigen receptor for chemokines (DARC) belongs to a family of 'silent' heptahelical chemokine receptors that do not couple to G proteins and fail to transmit measurable intracellular signals. DARC binds most inflammatory chemokines and is prominently expressed on venular endothelial cells, where its function has remained contentious. Here we show that DARC, like other silent receptors, internalized chemokines but did not effectively scavenge them. Instead, DARC mediated chemokine transcytosis, which led to apical retention of intact chemokines and more leukocyte migration across monolayers expressing DARC. Mice overexpressing DARC on blood vessel endothelium had enhanced chemokine-induced leukocyte extravasation and contact-hypersensitivity reactions. Thus, interactions of chemokines with DARC support their activity on apposing leukocytes in vitro and in vivo.

Slit and Robo regulate dendrite branching and elongation of space-filling neurons in Drosophila.

Space-filling neurons extensively sample their receptive fields with fine dendritic branches. In this study we show that a member of the conserved Robo receptor family, Robo, and its ligand Slit regulate the dendritic differentiation of space-filling neurons. Loss of Robo or Slit function leads to faster elongating and less branched dendrites of the complex and space-filling class IV multi-dendritic dendrite-arborization (md-da) neurons in the Drosophila embryonic peripheral nervous system, but not of the simpler class I neurons. The total dendrite length of Class IV neurons is not modified in robo or slit mutant embryos. Robo mediates this process cell-autonomously. Upon Robo over-expression in md-da neurons the dendritic tree is simplified and time-lapse analysis during larval stages indicates that this is due to reduction in the number of newly formed branches. We propose that Slit, through Robo, provides an extrinsic signal to coordinate the growth rate and the branching level of space-filling neurons, thus allowing them to appropriately cover their target field.

Effect of local and global geomagnetic activity on human cardiovascular homeostasis.

The authors investigated the effects of local and planetary geomagnetic activity on human physiology. They collected data in Sofia, Bulgaria, from a group of 86 volunteers during the periods of the autumnal and vernal equinoxes. They used the factors local/planetary geomagnetic activity, day of measurement, gender, and medication use to apply a four-factor multiple analysis of variance. They also used a post hoc analysis to establish the statistical significance of the differences between the average values of the measured physiological parameters in the separate factor levels. In addition, the authors performed correlation analysis between the physiological parameters examined and geophysical factors. The results revealed that geomagnetic changes had a statistically significant influence on arterial blood pressure. Participants expressed this reaction with weak local geomagnetic changes and when major and severe global geomagnetic storms took place.