Gravity “steps” at Mt. Etna volcano (Italy). Instrumental effects or evidences of earthquake-triggered magma density changes?

On two occasions, sudden gravity changes occurred simultaneously at two summit Etna’s stations, during local low-magnitude earthquakes. A systematic coupling between earthquakes inducing comparable maximum acceleration and displacement at the observation points and gravity steps is missing, implying (a) the non-instrumental nature of the steps and (b) the need for particular underlying conditions for the triggering mechanism(s) to activate. We review some of the volcanological processes that could induce fast underground mass redistributions, resulting in gravity changes at the surface. These processes involve bubbles and crystals present in the magma and require particular conditions in order to be effective as mass-redistributing processes. The gravity steps could be a geophysical evidence of the dynamical stress transfer between tectonic and magmatic systems at a local scale. Given the implications that these transfers may have on the volcanic activity, routine volcano monitoring should include the observation of fast gravity changes

Preface: Approaches and methods to improve risk management in volcanic areas

Active volcanoes can generate multiple types of geological hazards. Besides syneruptive threats (e.g., lava, pyroclastic flows or ash fall), other adverse events such as landslides or lahars can occur at any time. To manage these threats efficiently, three key objectives must be jointly addressed: (1) improving prevention tools, through the collection and acquisition of data on hazards and risks, and its dissemination as maps and scenarios; (2) improving crisis management capabilities, based on monitoring and early warning systems, but also reliable communications systems; and (3) reducing people’s vulnerability and developing recovery and resilience capabilities after an event has occurred. The special issue “Approaches and methods to improve risk management in volcanic areas” presents research results focusing on these three objectives. It demonstrates the utility of addressing them jointly, and particularly examines the case of volcanoes where little knowledge is available. These results were presented at the conference Integrated Approaches for Volcanic Risk Management (Hohenheim University, Stuttgart, 11/12 September 2012) of the European MIAVITA (MItigate and Assess risk from Volcanic Impact on Terrain and human Activities) project

In vivo measurements of atrial repolarization alternans based on standard pacemaker technology

It has been shown that repolarization alternans, a beat-to-beat alternation in action potential duration, enhances dispersion of repolarization above a critical heart rate and promotes susceptibility to ventricular arrhythmias. It is unknown whether repolarization alternans is measurable in the atria using standard pacemakers and whether it plays a role in promoting atrial fibrillation. In this work, atrial repolarization alternans amplitude and periodicity are studied in a sheep model of pacing-induced atrial fibrillation. Two pacemakers, each with one right atrial and ventricular lead, were implanted in 4 male sheep after ablation of the atrioventricular junction. The first one was used to deliver rapid pacing for measurements of right atrial repolarization alternans and the second one to record a unipolar electrogram. Atrial repolarization alternans appeared rate-dependent and its amplitude increased as a function of pacing rate. Repolarization alternans was intermittent but no periodicity was detected. An increase of repolarization alternans preceding episodes of non-sustained atrial fibrillation suggests that repolarization alternans is a promising parameter for assessment of atrial fibrillation susceptibility

Updated review of postmortem biochemical exploration of hypothermia with a presentation of standard strategy of sampling and analyses.

Hypothermia is defined as a core body temperature below 35°C and can be caused by environmental exposure, drug intoxication, metabolic or nervous system dysfunction. This lethal pathology with medico-legal implications is complex to diagnose because macroscopic and microscopic lesions observed at the autopsy and the histological analysis are suggestive but not pathognomonic. Postmortem biochemical explorations have been progressively developed through the study of several biomarkers to improve the diagnosis decision cluster. Here, we present an updated review with novel biomarkers (such as catecholamines O-methylated metabolites, thrombomodulin and the cardiac oxyhemoglobin ratio) as well as some propositional interpretative postmortem thresholds and, to the best of our knowledge, for the first time, we present the most adapted strategy of sampling and analyses to identify biomarkers of hypothermia. For our consideration, the most relevant identified biomarkers are urinary catecholamines and their O-methylated metabolites, urinary free cortisol, blood cortisol, as well as blood, vitreous humor and pericardial fluid for ketone bodies and blood free fatty acids. These biomarkers are increased in response either to cold-mediated stress or to bioenergetics ketogenesis crisis and significantly contribute to the diagnosis by exclusion of death by hypothermia

Léiomyosarcome de la veine rénale gauche dans un contexte de polyarthrite rhumatoïde sous méthotrexate

RésuméLe léiomyosarcome de la veine rénale est une tumeur maligne exceptionnelle dont la détection est délicate, le traitement mal codifié et le pronostic sombre. Nous décrivons le cas d’une patiente de 68 ans atteinte de polyarthrite rhumatoïde et développant un léiomyosarcome de la veine rénale gauche avec une issue fatale en moins d’un an. L’association à une polyarthrite rhumatoïde traitée par méthotrexate pose donc la question d’une combinaison fortuite ou d’un terrain favorisant compte tenu des études récentes qui tendent à prouver l’association entre ce rhumatisme et certains cancers

Possible large phase in psi(2S) -> 1-0- Decays

The strong and the electromagnetic amplitudes are analyzed on the basis of the measurements of J/psi, psi(2S) -> 1-0- in e+e- experiments. The currently available experimental information is revised with inclusion of the contribution from e+e- -> gamma * -> 1-0- . The study shows that a large phase around minus 90 degree between the strong and the electromagnetic amplitudes could not be ruled out by the experimental data for psi(2S).Comment: 4 page

Intermittent atrial tachycardia facilitates atrial fibrillation by a shortening of activation recovery interval

Introduction: We recently observed in a chronic ovine model that a shortening of action potential duration (APD) as assessed by the activation recovery interval (ARI) may be a mechanism whereby pacing-induced atrial tachycardia (PIAT) facilitates atrial fibrillation (AF), mediated by a return to 1:1 atrial capture after the effective refractory period has been reached. The aim of the present study is to evaluate the effect of long term intermittent burst pacing on ARI before induction of AF.Methods: We specifically developed a chronic ovine model of PIAT using two pacemakers (PM) each with a right atrial (RA) lead separated by ∼2cm. The 1st PM (Vitatron T70) was used to record a broadband unipolar RA EGM (800 Hz, 0.4 Hz high pass filter). The 2nd was used to deliver PIAT during electrophysiological protocols at decremental pacing CL (400 beats, from 400 to 110ms) and long term intermittent RA burst pacing to promote electrical remodeling (5s of burst followed by 2s of sinus rhythm) until onset of sustained AF. ARI was defined as the time difference between the peak of the atrial repolarization wave and the first atrial depolarization. The mean ARIs of paired sequences (before and after remodeling), each consisting of 20 beats were compared.Results: As shown in the figure, ARIs (n=4 sheep, 46 recordings) decreased post remodeling compared to baseline (86±19 vs 103±12 ms, p<0.05). There was no difference in atrial structure as assessed by light microscopy between control and remodeled sheep.Conclusions: Using standard pacemaker technology, atrial ARIs as a surrogate of APDs were successfully measured in vivo during the electrical remodeling process leading to AF. The facilitation of AF by PIAT mimicking salvos from pulmonary veins is heralded by a significant shortening of ARI

Thanatobiochemistry: post mortem study of the vitreous humor for the diagnosis of diabetic ketoacidosis death

Thanatobiochemistry refers to a post mortem study of biochemical parameters enabling to shed light on a cause of death. This discipline shines when suspected lethal pathology doesn\u27t have any noticeable macroscopic or microscopic features such as diabetic ketoacidosis. We relate the case of fourty-five years old patient followed-up for type I diabetes mellitus, discovered dead at home, for which only post mortem biochemical exploration of vitreous humor allowed to determine the cause of death by diabetic ketoacidosis

Gene expression profiling of Spodoptera frugiperda hemocytes and fat body using cDNA microarray reveals polydnavirus-associated variations in lepidopteran host genes transcript levels

BACKGROUND: Genomic approaches provide unique opportunities to study interactions of insects with their pathogens. We developed a cDNA microarray to analyze the gene transcription profile of the lepidopteran pest Spodoptera frugiperda in response to injection of the polydnavirus HdIV associated with the ichneumonid wasp Hyposoter didymator. Polydnaviruses are associated with parasitic ichneumonoid wasps and are required for their development within the lepidopteran host, in which they act as potent immunosuppressive pathogens. In this study, we analyzed transcriptional variations in the two main effectors of the insect immune response, the hemocytes and the fat body, after injection of filter-purified HdIV. RESULTS: Results show that 24 hours post-injection, about 4% of the 1750 arrayed host genes display changes in their transcript levels with a large proportion (76%) showing a decrease. As a comparison, in S. frugiperda fat body, after injection of the pathogenic JcDNV densovirus, 8 genes display significant changes in their transcript level. They differ from the 7 affected by HdIV and, as opposed to HdIV injection, are all up-regulated. Interestingly, several of the genes that are modulated by HdIV injection have been shown to be involved in lepidopteran innate immunity. Levels of transcripts related to calreticulin, prophenoloxidase-activating enzyme, immulectin-2 and a novel lepidopteran scavenger receptor are decreased in hemocytes of HdIV-injected caterpillars. This was confirmed by quantitative RT-PCR analysis but not observed after injection of heat-inactivated HdIV. Conversely, an increased level of transcripts was found for a galactose-binding lectin and, surprisingly, for the prophenoloxidase subunits. The results obtained suggest that HdIV injection affects transcript levels of genes encoding different components of the host immune response (non-self recognition, humoral and cellular responses). CONCLUSION: This analysis of the host-polydnavirus interactions by a microarray approach indicates that the presence of HdIV induces, directly or indirectly, variations in transcript levels of specific host genes, changes that could be responsible in part for the alterations observed in the parasitized host physiology. Development of such global approaches will allow a better understanding of the strategies employed by parasites to manipulate their host physiology, and will permit the identification of potential targets of the immunosuppressive polydnaviruses