Brain ventricular volume changes induced by long-duration spaceflight
Long-duration spaceflight induces detrimental changes in human physiology. Its residual effects and mechanisms remain unclear. We prospectively investigated the changes in cerebrospinal fluid (CSF) volume of the brain ventricular regions in space crew by means of a region of interest analysis on structural brain scans. Cosmonaut MRI data were investigated preflight (n = 11), postflight (n = 11), and at long-term follow-up 7 mo after landing (n = 7). Post hoc analyses revealed a significant difference between preflight and postflight values for all supratentorial ventricular structures, i.e., lateral ventricle (mean % change ± SE = 13.3 ± 1.9), third ventricle (mean % change ± SE = 10.4 ± 1.1), and the total ventricular volume (mean % change ± SE = 11.6 ± 1.5) (all P < 0.0001), with higher volumes at postflight. At follow-up, these structures did not quite reach baseline levels, with still residual increases in volume for the lateral ventricle (mean % change ± SE = 7.7 ± 1.6; P = 0.0009), the third ventricle (mean % change ± SE = 4.7 ± 1.3; P = 0.0063), and the total ventricular volume (mean % change ± SE = 6.4 ± 1.3; P = 0.0008). This spatiotemporal pattern of CSF compartment enlargement and recovery points to a reduced CSF resorption in microgravity as the underlying cause. Our results warrant more detailed and longer longitudinal follow-up. The clinical impact of our findings on the long-term cosmonauts’ health and their relation to ocular changes reported in space travelers requires further prospective studies.
Long-duration spaceflight has detrimental effects in several physiological systems. Several studies have shown an upward shift of the cerebral hemispheres, a decrease in frontotemporal volume, and an increase in ventricle size after spaceflight. However, information is limited about the effects of microgravity on brain volume, particularly regarding changes that are evident more than 1 month after spaceflight.
We prospectively studied data from T1-weighted magnetic resonance imaging (MRI) that was performed in 10 male cosmonauts (mean age, 44 years; average space-mission duration, 189 days) at three time points: preflight (in 10 cosmonauts), short-term postflight (average, 9 days postflight; in 10), and long-term postflight follow-up (average, 209 days postflight; in 7). The volumes of gray matter, white matter, and cerebrospinal fluid (CSF) were analyzed with the use of voxel-based morphometry. (The complete methods and additional analyses are provided in the Supplementary Appendix, which is available with the full text of this letter at NEJM.org.) Aging effects that may occur over the interval between preflight and postflight were accounted for by longitudinal data from matched controls.
The gray-matter volume postflight as compared with preflight showed a widespread decrease in the orbitofrontal and temporal cortexes; the maximal decrease was 3.3% in the right middle temporal gyrus. At long-term postflight follow-up, most reductions in gray-matter volume had recovered toward preflight levels (e.g., a 1.2% reduction in gray-matter volume persisted in the right temporal gyrus). The white-matter volume postflight as compared with preflight was reduced along a longitudinal tract of the left temporal lobe, but there was a global reduction of cerebral white-matter volume at long-term follow-up as compared with postflight. The ventral CSF spaces of the cerebral hemispheres and the ventricles had increased in volume postflight as compared with preflight (maximal increase, 12.9% in the third ventricle), while CSF volume below the vertex decreased. At long-term follow-up, the CSF volume in the ventricles had returned toward preflight values, while the CSF volume in the entire subarachnoid space around the brain had increased. Changes in the volumes of gray matter and CSF are shown in Figure 1.
The findings from an average of 7 months after a return to Earth can be summarized as showing that most of the loss in the gray-matter volume that was seen immediately postflight had recovered to preflight levels, while CSF volume continued to increase in the subarachnoid compartment. The expansion of CSF spaces in light of postflight decreases in the gray-matter volume and a reduction in the white-matter volume at follow-up suggests a persistent disturbance in CSF circulation even many months after a return to Earth. These brain-volume changes may relate to clinical findings, such as ocular and visual abnormalities after long-duration spaceflight. Future investigation is required in order to determine the overall clinical significance of the findings and to mitigate risks in long space missions.
Abstracts which were sent to Organizing Comittee in electronic form are included in digest. The Conference is supported by Russian Foundation fo Basic Research (grant 13-08-06122-G).
The volume fraction of water related to myelin (fmy) is a promising MRI index for in vivo assessment of brain myelination, that can be derived from multi-component analysis of T1 and T2 relaxometry signals. However, existing quantification methods require rather long acquisition and/or post-processing times, making implementation difficult both in research studies on healthy unsedated children and in clinical examinations. The goal of this work was to propose a novel strategy for fmy quantification within acceptable acquisition andpost-processing times. Our approach is based on a 3-compartment model (myelin-related water, intra/extra-cellular water and unrestricted water), and uses calibrated values of inherent relaxation times (T1c and T2c) for each compartment c. Calibration was first performed on adult relaxometry datasets (N = 3) acquired with large numbers of inversion times (TI) and echo times (TE), using an original combination of a region contraction approach and a non-negative least-square (NNLS) algorithm. This strategy was compared with voxel-wise fitting, and showed robust estimation of T1c and T2c. The accuracy of fmy calculations depending on multiple factors was investigated using simulated data. In the testing stage, our strategy enabled fast fmy mapping, based on relaxometry datasets acquired with reduced TI and TE numbers (acquisition <6 min), and analyzed with NNLS algorithm (post-processing <5min). In adults (N = 13, mean age 22.4±1.6 years), fmy maps showed variability across white matter regions, in agreement with previous studies. In healthy infants (N = 18, aged 3 to 34 weeks), asynchronous changes in fmy values were demonstrated across bundles, confirming the well-known progression of myelination.
This book presents the results of analysis of human capital in Murmansk and Archangelsk regions, republics of Komi and Karelia, and Nenets Autonomous Region. The authors considered migration processes and their trends; some of these were analyzed at municipal level. Having taken in account the importance of life expectancy as a complex indicator of sustainable development, the authors identified the periods of its growth and decline. Age-specific differences were also scrutinized. The relative contributions of major causes of mortality in life expectancy at birth were estimated. The authors described the dynamics of population of small indigenous peoples of the North (Vepsians, Nenets, Komi), the problems associated with their self-identification, census administration, migration, childbirth and life expectancy. The authors analyzed climate change as the new health risk factor, which affects safety of food and drinking water, accessibility of medical services and specific practices of deer-herding. A separate chapter of the book is devoted to current and future trends in working-age population until 2002. Each territory of Barents Sea Region displayed its own peculiar behavior of this indicator. The authors compared selected social, economic and demographic indicators in European part of Russian Arctic with those in foreign countries which belong to Barents Sea Region. This monograph was a product of collaborative efforts of the researchers from Economic Forecasting Institute and Institute of Demography of Higher School of Economics. B. A. Revich, Doctor of Medicine, and B. N. Porfiryev, Corresponding Member of Russian Academy of Sciences, edited this book.
In the internal medicine wide spectrum the gastroenterology is one of the chapters, less enlightened by the scientific evidence. It does not mean that the practice of the grasntroenterology may ot be improved by the systematic use of the approaches of the evidence based medicine
This prototype development explains the challenges encountered during the ISO/IEEE 11073 standard implementation process. The complexity of the standard and the consequent heavy requirements, which have not encouraged software engineers to adopt the standard. The developing complexity evaluation drives us to propose two possible implementation strategies that cover almost all possible use cases and eases handling the standard by non-expert users. The first one is focused on medical devices (MD) and proposes a low-memory and low-processor usage technique. It is based on message patterns that allow simple functions to generate ISO/IEEE 11073 messages and to process them easily. MD act as X73 agent. Second one is focused on more powerful device X73 manager, which do not have the MDs' memory and processor usage constraints. The protocol between Agent and Manager is point-to-point and we can distribute the functionality between devices.
Developed both implementation X73 Agent and Manager will cut developing time for applications based on ISO/EEE 11073.