Long-term spaceflight and the cardiovascular system

While early investigations into the physiological effects of spaceflight suggest the body’s ability to reversibly adapt,the corresponding effects of long-term spaceflight(>6months)aremuch less conclusive.Prolonged exposure to microgravity and radiation yields profound effects on the cardiovascular system,including a massive cephalad fluid translocation and altered arterial pressure,which attenuate blood pressure regulatory mechanisms and increase cardiac output.Also,central venous pressure decreases as a result of the loss of venous compression.The stimulation of baroreceptors by the cephalad shift results in an approximately 10%–15%reduction in plasma volume,with fluid translocating from the vascular lumen to the interstitium.Despite possible increases in cardiac workload,myocyte atrophy and notable,yet unexplained,alterations in hematocrit have been observed.Atrophy is postulated to result from shunting of protein synthesis from the endoplasmic reticulum to the mitochondria via mortalin-mediated action.While data are scarce regarding their causative agents,arrhythmias have been frequently reported,albeit sublethal,during both Russian and American expeditions,with QT interval prolongation observed in long,but not short duration,spaceflight.Exposure of the heart to the proton and heavy ion radiation of deep space has also been shown to result in coronary artery degeneration,aortic stiffness,carotid intima thickening via collagen-mediated action,accelerated atherosclerosis,and induction of a pro-inflammatory state.Upon return,long-term spaceflight frequently results in orthostatic intolerance and altered sympathetic responses,which can prove hazardous should any rapidmobilization or evacuation be required,and indicates that these cardiac risks should be especially monitored for future missions.

Improved gastrointestinal health for irritable bowel syndrome with metagenome-guided interventions

Irritable bowel syndrome(IBS)is the most prevalent functional gastrointestinal disorder worldwide,and the most common reason for referral to gastroenterology clinics.However,the pathophysiology is still not fully understood and consequently current management guidelines are very symptom-specific,leading to mixed results.Here we present a study of 88 individuals with IBS who had baseline sequencing of their gut microbiome(stool samples),received targeted interventions that included dietary,supplement,prebiotic/probiotic,and lifestyle recommendations for a 30-day period,and a follow-up sequencing of their gut microbiome.The study’s objectives were to demonstrate unique metagenomic signatures across the IBS phenotypes and to validate whether metagenomic-guided interventions could lead to improvement of symptom scores in individuals with IBS.Enrolled subjects also completed a baseline and post-intervention questionnaire that assessed their symptom scores.The average symptom score of an individual with IBS at baseline was 160 and at the endpoint of the study the average symptom score of the cohort was 100.9.The mixed IBS subtype showed the most significant reduction in symptom scores across the different subtypes(average decrease by 102 points,P=0.005).The metagenomics analysis reveals shifts in the microbiome post-intervention that have been cross-validated with the literature as being associated with improvement of IBS symptoms.Given the complex nature of IBS,further studies with larger sample sizes,more targeted analyses,and a broader population cohort are needed to explore these results further.