Spaceflight: Immune Effects and Nutritional Countermeasure

Microgravity is predicted to be a significant challenge to immune system during space travel. Consequences of weakened immune responses range from increased disease susceptibility to neoplastic growth. Degree of immune dysfunction is considered proportional to duration of stay in spaceflights. As a result of these risks, there is major concern over potential health risk for space travels that ultimately result in serious and considerable loss of mission objectives. Therefore, here is a need to explore the immune effects of spaceflight and its countermeasures. Several attempts have been made to develop effective measure to alleviate or prevent immune dysfunction due to microgravity. Among them, immunonutritional model has been shown to effectively modulate and upregulate immune system. This is further supported by our experiments demonstrating that supplementation of nutritional substrates like nucleotide and mushroom extracts active hexose-correlated compound (AHCC) effective in maintaining or restoring immunity in microgravity analog models

Cardiopulmonary Changes with Moderate Decompression in Rats

Sprague-Dawley rats were compressed to 616 kPa for 120 min then decompressed at 38 kPa/min to assess the cardiovascular and pulmonary responses to moderate decompression stress. In one series of experiments the rats were chronically instrumented with Doppler ultrasonic probes for simultaneous measurement of blood pressure, cardiac output, heart rate, left and right ventricular wall thickening fraction, and venous bubble detection. Data were collected at base-line, throughout the compression/decompression protocol, and for 120 min post decompression. In a second series of experiments the pulmonary responses to the decompression protocol were evaluated in non-instrumented rats. Analyses included blood gases, pleural and bronchoalveolar lavage (BAL) protein and hemoglobin concentration, pulmonary edema, BAL and lung tissue phospholipids, lung compliance, and cell counts. Venous bubbles were directly observed in 90% of the rats where immediate post-decompression autopsy was performed and in 37% using implanted Doppler monitors. Cardiac output, stroke volume, and right ventricular wall thickening fractions were significantly decreased post decompression, whereas systemic vascular resistance was increased suggesting a decrease in venous return. BAL Hb and total protein levels were increased 0 and 60 min post decompression, pleural and plasma levels were unchanged. BAL white blood cells and neutrophil percentages were increased 0 and 60 min post decompression and pulmonary edema was detected. Venous bubbles produced with moderate decompression profiles give detectable cardiovascular and pulmonary responses in the rat

AHCC Activation and Selection of Human Lymphocytes via Genotypic and Phenotypic Changes to an Adherent Cell Type: A Possible Novel Mechanism of T Cell Activation

Active Hexose Correlated Compound (AHCC) is a fermented mushroom extract and immune supplement that has been used to treat a wide range of health conditions. It helps in augmentation of the natural immune response and affects immune cell activation and outcomes. The goal of this project was to study and understand the role and mechanisms of AHCC supplementation in the prevention of immunosuppression through T cell activation. The method described here involves “in vitro” culturing of lymphocytes, exposing them to different concentrations of AHCC (0 μg/mL, 50 μg/mL, 100 μg/mL, 250 μg/mL, and 500 μg/mL) at 0 hours. Interestingly, clumping and aggregation of the cells were seen between 24 and 72 hours of incubation. The cells lay down extracellular matrix, which become adherent, and phenotypical changes from small rounded lymphocytes to large macrophage-like, spindle shaped, elongated, fibroblast-like cells even beyond 360 hours were observed. These are probably translated from genotypic changes in the cells since the cells propagate for at least 3 to 6 generations (present observations). RNA isolated was subjected to gene array analysis. We hypothesize that cell adhesion is an activation and survival pathway in lymphocytes and this could be the mechanism of AHCC activation in human lymphocytes

Regulation of Coronary Blood Flow

The heart is uniquely responsible for providing its own blood supply through the coronary circulation. Regulation of coronary blood flow is quite complex and, after over 100 years of dedicated research, is understood to be dictated through multiple mechanisms that include extravascular compressive forces (tissue pressure), coronary perfusion pressure, myogenic, local metabolic, endothelial as well as neural and hormonal influences. While each of these determinants can have profound influence over myocardial perfusion, largely through effects on end-effector ion channels, these mechanisms collectively modulate coronary vascular resistance and act to ensure that the myocardial requirements for oxygen and substrates are adequately provided by the coronary circulation. The purpose of this series of Comprehensive Physiology is to highlight current knowledge regarding the physiologic regulation of coronary blood flow, with emphasis on functional anatomy and the interplay between the physical and biological determinants of myocardial oxygen delivery. © 2017 American Physiological Society. Compr Physiol 7:321-382, 2017

Towards the forecast of false positives in nuclear network monitoring due to atmospheric radon.

International audienceRadon-222 is a progeny of Uranium-238, naturally present in the Earth’s crust. After its migration through the soil, it reaches the atmosphere. As a noble gas, it does not interact with other gas or aerosol particles whereas its progenies do. These progenies can concentrate in rain drops and lead to gamma dose rate peaks occurring during rainfall events. This may trigger alarms of emergency monitoring networks. These peaks can be used as a suitable radiological case study for model validation and improvement. Hundreds of gamma dose rate monitoring stations are available in France, recording data each five minutes all year round. Atmospheric dispersion models used for emergency purposes are usually meant to simulate the atmospheric transport of radioisotopes released from a damaged nuclear facility. The quality of this response is a critical issue and has to be constantly improved. However, long-range measurement campaigns for model validation are scarce, especially for radioactive pollutants. We built a Radon-222 atmospheric transport modelling calculation chain, from input data to model-to-measurement comparisons on a national scale. Preliminary results of these comparisons are presented. The final objective is to discriminate, on a gamma dose rate monitoring network, false alarms due to natural radioactivity from real nuclear incidents in a forecast mode

Towards the forecast of false positives in nuclear network monitoring due to atmospheric radon.

International audienceRadon-222 is a progeny of Uranium-238, naturally present in the Earth’s crust. After its migration through the soil, it reaches the atmosphere. As a noble gas, it does not interact with other gas or aerosol particles whereas its progenies do. These progenies can concentrate in rain drops and lead to gamma dose rate peaks occurring during rainfall events. This may trigger alarms of emergency monitoring networks. These peaks can be used as a suitable radiological case study for model validation and improvement. Hundreds of gamma dose rate monitoring stations are available in France, recording data each five minutes all year round. Atmospheric dispersion models used for emergency purposes are usually meant to simulate the atmospheric transport of radioisotopes released from a damaged nuclear facility. The quality of this response is a critical issue and has to be constantly improved. However, long-range measurement campaigns for model validation are scarce, especially for radioactive pollutants. We built a Radon-222 atmospheric transport modelling calculation chain, from input data to model-to-measurement comparisons on a national scale. Preliminary results of these comparisons are presented. The final objective is to discriminate, on a gamma dose rate monitoring network, false alarms due to natural radioactivity from real nuclear incidents in a forecast mode

Outdoor exposure due to long-range atmospheric transport of radon can it be assessed by modelling?

International audienceRadon-222 is a progeny of U-238, naturally present in the Earth’s crust. After diffusing out of the soil, it reaches the atmosphere. As a noble gas, it does not interact with other gas or aerosol particles. Transported by the atmosphere, it can be breathed. Its disintegration inside the lung can damage the cells, increasing the risk of cancer. Radon-222 is therefore a major public health issue in some regions. Significant Radon-222 air concentration at one location is the combination of a potentially high local source – within few kilometers – and a long-distance origin – dozens or hundreds of kilometers. A local source can be estimated by modelling or measuring the ground exhalation rate. A distant origin is far more problematic to determine since it involves all the atmospheric processes and many potential exhalation sites. Therefore, the simulation of Radon-222 air concentrations must be made at regional or continental scale. We built a Radon-222 atmospheric transport modelling calculation chain, from input data to model-to-measurement comparisons. The main issues about the input data were to get reliable the radon exhalation rate and meteorological data. The quality of the modelling was then evaluated by a model-to-measurements comparison. Hundreds of gamma dose rate monitoring stations are available in France, recording data each five minutes all year round. They record dose rate peaks due to the Radon-222 progenies concentrated in rainfall events. Preliminary results are presented

REAL-TIME USE OF INVERSE MODELING TECHNIQUES TO ASSESS THE ATMOSPHERIC ACCIDENTAL RELEASE OF A NUCLEAR POWER PLANT

International audienceThe assessment of the source term including the time evolution of the release rate into the atmosphere and its distribution between radionuclides is one of the key issues in the understanding of the consequences of a nuclear accident. Inverse modeling methods which combine environmental measurements and atmospheric dispersion models have been proven to be efficient in assessing the source term due to an accidental situation. We developed our own tool which has been applied to the Fukushima accident by using dose rate measurements and air concentration measurements. The inverse modeling tool has been implemented and tested during exercises implying fictitious radioactive releases with the aim of testing this method for emergency management. The exercises showed the relevance of the inverse modeling tool and it is a rewarding experience which helped us to identify the required developments for the purpose of an operational use