scholarly journals Pain and Vertebral Dysfunction in Dry Immersion: A Model of Microgravity Simulation Different from Bed Rest Studies

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
L. Treffel ◽  
N. Massabuau ◽  
K. Zuj ◽  
M.-A. Custaud ◽  
G. Gauquelin-Koch ◽  
...  
Keyword(s):  
Back Pain ◽  
Simulated Microgravity ◽  
Simulation Models ◽  
Bed Rest ◽  
Dry Immersion ◽  
Somatic Dysfunction ◽  
Clinical Methods ◽  
Microgravity Simulation ◽  
Before And After ◽  
Manual Palpation

Background. Astronauts frequently experience back pain during and after spaceflight. The aim of this study was to utilize clinical methods to identify potential vertebral somatic dysfunction (VD) in subjects exposed to dry immersion (DI), a model of microgravity simulation. Method. The experiment was performed in a space research clinic, respecting all the ethical rules, with subjects completing three days of dry immersion (n=11). Assessments of VD, spine height, and back pain were made before and after simulated microgravity. Results. Back pain was present in DI with great global discomfort during the entire protocol. A low positive correlation was found (Pearson r=0.44; P<0.001) between VD before DI and pain developed in the DI experiment. Conclusions. There is a specific location of pain in both models of simulation. Our analysis leads to relativizing constraints on musculoskeletal system in function of simulation models. This study was the first to examine manual palpation of the spine in a space experience. Additionally, osteopathic view may be used to select those individuals who have less risk of developing back pain.

Prolonged head-down tilt exposure reduces maximal cutaneous vasodilator and sweating capacity in humans

2003 ◽  
Vol 94 (6) ◽  
pp. 2330-2336 ◽  
Author(s):  
C. G. Crandall ◽  
M. Shibasaki ◽  
T. E. Wilson ◽  
J. Cui ◽  
B. D. Levine
Keyword(s):  
Sweat Gland ◽  
Simulated Microgravity ◽  
Sweat Rate ◽  
Bed Rest ◽  
Exercise Group ◽  
Aerobic Exercise Training ◽  
Before And After ◽  
Rate Maximum ◽  
Gland Function ◽  
Cutaneous Vascular Conductance

Cutaneous vasodilation and sweat rate are reduced during a thermal challenge after simulated and actual microgravity exposure. The effects of microgravity exposure on cutaneous vasodilator capacity and on sweat gland function are unknown. The purpose of this study was to test the hypothesis that simulated microgravity exposure, using the 6° head-down tilt (HDT) bed rest model, reduces maximal forearm cutaneous vascular conductance (FVC) and sweat gland function and that exercise during HDT preserves these responses. To test these hypotheses, 20 subjects were exposed to 14 days of strict HDT bed rest. Twelve of those subjects exercised (supine cycle ergometry) at 75% of pre-bed rest heart rate maximum for 90 min/day throughout HDT bed rest. Before and after HDT bed rest, maximal FVC was measured, via plethysmography, by heating the entire forearm to 42°C for 45 min. Sweat gland function was assessed by administering 1 × 10−6 to 2 M acetylcholine (9 doses) via intradermal microdialysis while simultaneously monitoring sweat rate over the microdialysis membranes. In the nonexercise group, maximal FVC and maximal stimulated sweat rate were significantly reduced after HDT bed rest. In contrast, these responses were unchanged in the exercise group. These data suggest that 14 days of simulated microgravity exposure, using the HDT bed rest model, reduces cutaneous vasodilator and sweating capacity, whereas aerobic exercise training during HDT bed rest preserves these responses.

scholarly journals Effects of artificial gravity during bed rest on bone metabolism in humans

2009 ◽  
Vol 107 (1) ◽  
pp. 47-53 ◽  
Author(s):  
S. M. Smith ◽  
S. R. Zwart ◽  
M. A. Heer ◽  
N. Baecker ◽  
H. J. Evans ◽  
...  
Keyword(s):  
Bone Metabolism ◽  
Bone Mineral ◽  
Rest Period ◽  
Bed Rest ◽  
Bone Alkaline Phosphatase ◽  
Artificial Gravity ◽  
Whole Body ◽  
Mineral Density ◽  
Microgravity Simulation ◽  
Before And After

We report results from a study designed to explore the utility of artificial gravity (AG) as a countermeasure to bone loss induced by microgravity simulation. After baseline testing, 15 male subjects underwent 21 days of 6° head-down bed rest to simulate the deconditioning associated with spaceflight. Eight of the subjects underwent 1 h of centrifugation (AG; 1 Gz at the heart, 2.5 Gz at the feet) each day for 21 days, whereas seven of the subjects served as untreated controls (Con). Blood and urine were collected before, during, and after bed rest for bone marker determinations. Bone mineral density (BMD) and bone mineral content (BMC) were determined by dual-energy X-ray absorptiometry and peripheral quantitative computerized tomography before and after bed rest. Urinary excretion of bone resorption markers increased during bed rest, but the AG and Con groups did not differ significantly. The same was true for serum C-telopeptide. During bed rest, bone alkaline phosphatase (ALP) and total ALP tended to be lower in the AG group ( P = 0.08, P = 0.09). Neither BMC nor BMD changed significantly from the pre-bed rest period in AG or Con groups, and the two groups were not significantly different. However, when AG and Con data were combined, there was a significant ( P < 0.05) effect of time for whole body total BMC and total hip and trochanter BMD. These data failed to demonstrate efficacy of this AG prescription to prevent the changes in bone metabolism observed during 3 wk of bed rest.

scholarly journals The Effects of Spaceflight Factors on the Human Plasma Proteome, Including Both Real Space Missions and Ground-Based Experiments

2019 ◽  
Vol 20 (13) ◽  
pp. 3194 ◽  
Author(s):  
Alexander G. Brzhozovskiy ◽  
Alexey S. Kononikhin ◽  
Lyudmila Ch. Pastushkova ◽  
Daria N. Kashirina ◽  
Maria I. Indeykina ◽  
...  
Keyword(s):  
Space Station ◽  
Bed Rest ◽  
Real Space ◽  
Space Missions ◽  
Label Free ◽  
Dry Immersion ◽  
Proteomic Data ◽  
Before And After ◽  
Effective Development ◽  
Common Pathogenesis

The aim of the study was to compare proteomic data on the effects of spaceflight factors on the human body, including both real space missions and ground-based experiments. LC–MS/MS-based proteomic analysis of blood plasma samples obtained from 13 cosmonauts before and after long-duration (169–199 days) missions on the International Space Station (ISS) and for five healthy men included in 21-day-long head-down bed rest (HDBR) and dry immersion experiments were performed. The semi-quantitative label-free analysis revealed significantly changed proteins: 19 proteins were significantly different on the first (+1) day after landing with respect to background levels; 44 proteins significantly changed during HDBR and 31 changed in the dry immersion experiment. Comparative analysis revealed nine common proteins (A1BG, A2M, SERPINA1, SERPINA3, SERPING1, SERPINC1, HP, CFB, TF), which changed their levels after landing, as well as in both ground-based experiments. Common processes, such as platelet degranulation, hemostasis, post-translational protein phosphorylation and processes of protein metabolism, indicate common pathogenesis in ground experiments and during spaceflight. Dissimilarity in the lists of significantly changed proteins could be explained by the differences in the dynamics of effective development in the ground-based experiments. Data are available via ProteomeXchange using the identifier PXD013305.

Changes in size and compliance of the calf after 30 days of simulated microgravity

1989 ◽  
Vol 66 (3) ◽  
pp. 1509-1512 ◽  
Author(s):  
V. A. Convertino ◽  
D. F. Doerr ◽  
S. L. Stein
Keyword(s):  
Simulated Microgravity ◽  
Orthostatic Intolerance ◽  
Bed Rest ◽  
Calf Muscle ◽  
Venous Compliance ◽  
Cross Sectional ◽  
Percent Change ◽  
Long Duration ◽  
Before And After ◽  
Muscle Compartment

Increased leg venous compliance may contribute to postflight orthostatic intolerance in astronauts. We reported that leg compliance was inversely related to the size of the muscle compartment. The purpose of this study was to test the hypothesis that reduced muscle compartment after long-duration exposure to microgravity would cause increased leg compliance. Eight men, 31–45 yr old, were measured for vascular compliance of the calf and serial circumferences of the calf before and after 30 days of continuous 6 degrees head-down bed rest. Cross-sectional areas (CSA) of muscle, fat, and bone compartments in the calf were determined before and after bed rest by computed tomography. From before to after bed rest, calculated calf volume (cm3) decreased (P less than 0.05) from 1,682 +/- 83 to 1,516 +/- 76. Calf muscle compartment CSA (cm2) also decreased (P less than 0.05) from 74.2 +/- 3.6 to 70.6 +/- 3.4; calf compliance (ml.100 ml-1.mmHg-1.100) increased (P less than 0.05) from 3.9 +/- .7 to 4.9 +/- .5. The percent change in calf compliance after bed rest was significantly correlated with changes in calf muscle compartment CSA (r = 0.72, P less than 0.05). The increased leg compliance observed after exposure to simulated microgravity can be partially explained by reduced muscle compartment. Countermeasures designed to minimize muscle atrophy in the lower extremities may be effective in ameliorating increased venous compliance and orthostatic intolerance after spaceflight.

scholarly journals Does simulated microgravity induce significant changes in human gut microbiota? New answers with dry immersion, an innovative ground-based model.

2020 ◽  
Author(s):  
Maxence Jollet ◽  
Bénédicte Goustard ◽  
Mahendra Mariadassou ◽  
Olivier Rué ◽  
Vincent Ollendorff ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Simulated Microgravity ◽  
Human Model ◽  
Strong Impact ◽  
Human Gut ◽  
Human Gut Microbiota ◽  
Dry Immersion ◽  
Α Diversity ◽  
Before And After ◽  
And Performance

Abstract Background A new problematic on the gut microbiota of the astronauts and the effects of microgravity emerged recently as that bacteria community is sensitive to physical (in)activity which could be hampered during spaceflights. Therefore, the objective of our study was thus to determine the effects of dry immersion, an innovative ground-based human model of simulated microgravity, on human gut microbiota composition. We collected stools from 14 healthy men before and after 5 days of Dry Immersion to determine taxonomic profiles by 16S metagenomic.Results Our analyses show preservation of α–diversity through Observed, Chao1, Shannon and InvSimpson indices. β–diversity is also not impacted by Dry Immersion as represented by PCoA plots with Jaccard, Bray-Curtis and UniFrac indices. Phyla abundances for OTUs associated to BacteroidetesP, FirmicutesP, ProteobacteriaP and ActinobacteriaP are also preserved. Interestingly, metagenomics analysis of the 32 families and 44 associated genera underscored that OTUs associated to ClostridialesO order and LachnospiraceaeF family are increased (p < 0.01) belonging to FirmicutesP phylum.Conclusion The diversity and global composition of the gut microbiome remained unaltered in response to Dry Immersion confirming the robustness of gut microbiota. However, it’s sufficient to led to several significant changes at the lower taxonomy levels. This suggests that the human gut microbiota, with its known strong impact on human health and performance, is a potential biological target of microgravity and underscores the need to investigate further this new field of research on gut microbiota – microgravity.Trial registration: ClinicalTrials.gov Identifier NCT03915457- Registered 16 April 2019 - Retrospectively registered - https://clinicaltrials.gov/ct2/show/NCT03915457.

Effects of simulated microgravity on closed-loop cardiovascular regulation and orthostatic intolerance: analysis by means of system identification

2004 ◽  
Vol 96 (2) ◽  
pp. 489-497 ◽  
Author(s):  
Xinshu Xiao ◽  
Ramakrishna Mukkamala ◽  
Natalie Sheynberg ◽  
S. Marlene Grenon ◽  
Michael D. Ehrman ◽  
...  
Keyword(s):  
System Identification ◽  
Simulated Microgravity ◽  
Closed Loop ◽  
Orthostatic Intolerance ◽  
Bed Rest ◽  
Model Parameters ◽  
Primary Concern ◽  
Loop Model ◽  
Before And After ◽  
Coupling Mechanisms

Microgravity-induced orthostatic intolerance (OI) continues to be a primary concern for the human space program. To test the hypothesis that exposure to simulated microgravity significantly alters autonomic nervous control and, thus, contributes to increased incidence of OI, we employed the cardiovascular system identification (CSI) technique to evaluate quantitatively parasympathetic and sympathetic regulation of heart rate (HR). The CSI method analyzes second-to-second fluctuations in noninvasively measured HR, arterial blood pressure, and instantaneous lung volume. The coupling mechanisms between these signals are characterized by using a closed-loop model. Parameters reflecting parasympathetic and sympathetic responsiveness with regard to HR regulation can be extracted from the identified coupling mechanisms. We analyzed data collected from 29 human subjects before and after 16 days of head-down-tilt bed rest (simulated microgravity). Statistical analyses showed that parasympathetic and sympathetic responsiveness was impaired by bed rest. A lower sympathetic responsiveness and a higher parasympathetic responsiveness measured before bed rest identified individuals at greater risk of OI before and after bed rest. We propose an algorithm to predict OI after bed rest from measures obtained before bed rest.

scholarly journals SAT0179 Back pain and disability before, and after, clinically-diagnosed vertebral fractures

2001 ◽  
Author(s):  
M Nevitt ◽  
L Palermo ◽  
D Thompson ◽  
D Bauer ◽  
K Stone ◽  
...  
Keyword(s):  
Back Pain ◽  
Vertebral Fractures ◽  
Before And After

scholarly journals Module to Support Real-Time Microscopic Imaging of Living Organisms on Ground-Based Microgravity Analogs

2021 ◽  
Vol 11 (7) ◽  
pp. 3122
Author(s):  
Srujana Neelam ◽  
Audrey Lee ◽  
Michael A. Lane ◽  
Ceasar Udave ◽  
Howard G. Levine ◽  
...  
Keyword(s):  
Real Time ◽  
High Speed ◽  
Simulated Microgravity ◽  
Image Acquisition ◽  
Time Lapse ◽  
Moving Frames ◽  
Cell Functions ◽  
Microgravity Simulation ◽  
Division Cell ◽  
Over Time

Since opportunities for spaceflight experiments are scarce, ground-based microgravity simulation devices (MSDs) offer accessible and economical alternatives for gravitational biology studies. Among the MSDs, the random positioning machine (RPM) provides simulated microgravity conditions on the ground by randomizing rotating biological samples in two axes to distribute the Earth’s gravity vector in all directions over time. Real-time microscopy and image acquisition during microgravity simulation are of particular interest to enable the study of how basic cell functions, such as division, migration, and proliferation, progress under altered gravity conditions. However, these capabilities have been difficult to implement due to the constantly moving frames of the RPM as well as mechanical noise. Therefore, we developed an image acquisition module that can be mounted on an RPM to capture live images over time while the specimen is in the simulated microgravity (SMG) environment. This module integrates a digital microscope with a magnification range of 20× to 700×, a high-speed data transmission adaptor for the wireless streaming of time-lapse images, and a backlight illuminator to view the sample under brightfield and darkfield modes. With this module, we successfully demonstrated the real-time imaging of human cells cultured on an RPM in brightfield, lasting up to 80 h, and also visualized them in green fluorescent channel. This module was successful in monitoring cell morphology and in quantifying the rate of cell division, cell migration, and wound healing in SMG. It can be easily modified to study the response of other biological specimens to SMG.

Investigations Into Asperity Persistence in Heavily Loaded Contacts

1999 ◽  
Vol 121 (3) ◽  
pp. 441-448 ◽  
Author(s):  
I. Lee-Prudhoe ◽  
R. S. Sayles ◽  
A. Kaderic
Keyword(s):  
Rough Surface ◽  
Simulation Models ◽  
Simulation Method ◽  
Asperity Contact ◽  
Local Contact ◽  
Before And After ◽  
Indentation Tests ◽  
Mechanisms Of Persistence ◽  
Contact Pressures ◽  
Smooth Roller

Experimental results are presented along the lines of the early work of Moore (1948) where a hard smooth roller is pressed into a softer rough surface to study the resulting real to apparent areas of contact and their associated local contact pressures. Results are presented for a hard steel roller deforming mild-steel and aluminum-alloy rough surface specimens. An analysis of the local contact mechanics is performed before and after indentation using a recently developed numerical elastic contact simulation method which allows local asperity contact pressures and areas to be studied in detail. The method is shown to reveal the level and distribution of pressures and asperity contact areas prevalent during the indentation process, and therefore allows the contribution of elastic and plastic load support to be quantified. The persistence of asperities during such indentation tests is discussed in terms of the pressures the asperities can support in relation to reported mechanisms of persistence. Results of subsequent sub-surface stresses are also presented and discussed in terms of how the method might be used to create an elastic-plasticdeformation model that can account for asperity persistence in future numerical contact simulation models.

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