Science.gov

Sample records for 90-day bed rest

  1. Baroreflex Sensitivity Decreases During 90-Day Bed Rest

    NASA Technical Reports Server (NTRS)

    Stenger, M. B.; Arzeno, N. M.; Platts, S. H.

    2008-01-01

    Baroreflex sensitivity (BRS) decreases during spaceflight and simulated spaceflight (head down bed rest [BR]). However, previous studies have only examined BRS in response to a limited blood pressure (BP) range or to a single sudden change in BP. PURPOSE: The purpose of this study was to examine BRS during 90 days of 6deg head-down tilt BR over a broad range of BP perturbations. METHODS: Nineteen normal volunteers (12M, 7F) were tested one day before BR, and then near BR days 30, 60 and 90. BP was pharmacologically altered by continuous infusions of phenylephrine (PE) and sodium nitroprusside (SNP). Electrocardiogram and continuous BP were collected during 10 min of normal saline (NS), followed by increasing concentrations of PE (10 min each of 0.4, 0.8 and 1.6 micro-g/kg/min). After a 20 min break, NS was infused again for 10 min, followed by increasing concentrations of SNP (10 min each of 0.4, 0.8, 1.2 micro-g/kg/min). Baroreceptor sensitivity was measured as the slope of a sequence of 3 or more beats in which the systolic BP and following R-R interval (RR) both increased or decreased. Spectral heart rate variability (HRV) and mean RR were analyzed using data from only the NS infusions. Two-way repeated-measures analysis of variance was performed to examine the effects of BR and gender. RESULTS: RR decreased (p<0.001) from pre- BR across BR days. High frequency in normalized units, a measure of parasympathetic activity, decreased with BR (p=0.027) and was lower (p=0.046) in men (0.39+/-0.02, mean+/-SEM) than women (0.48+/-0.02). The spontaneous baroreflex slope, our measure of BRS, increased with PE and decreased with SNP across BR (p<0.001). The percentage decrease in BRS from pre- to post-BR appeared to be larger in women (43.6+/-7.0%) than in men (31.3+/-3.9%, p=0.06). CONCLUSION: Parasympathetic activity and baroreflex sensitivity decrease during 90 days of BR, and BRS tends to diminish more in women than in men.

  2. Effects of 30-, 60-, and 90-Day Bed Rest on Postural Control in Men and Women

    NASA Technical Reports Server (NTRS)

    Esteves, Julie; Taylor, Laura C.; Vanya, Robert D.; Dean, S. Lance; Wood, Scott J.

    2011-01-01

    INTRODUCTION Head-down-tilt bed rest (HDT) has been used as a safe gr ound-based analog to mimic and develop countermeasures for the physiological effects of spaceflight, including decrements in postural stability. The purpose of this investigation was to characterize the effects of 30-, 60-, and 90-day bed rest on postural control in men and women. METHODS Twenty-nine subjects (18M,11F) underwent 13 days of ambula tory acclimatization and were placed in 6? HDT for 30 (n=12), 60 (n=8), or 90 (n=9) days, followed by 14 days of ambulatory recovery. Computerized dynamic posturography (CDP) was used to assess changes in sensory and motor components of postural control, and recovery after HDT. Sensory Organization Tests (SOTs) objectively evaluate one?s ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Stability during the SOTs was assessed using peak-to-peak sway and convergence toward stability limits to derive an equilibrium score. Motor Control Tests (MCTs) evaluate one?s ability to recover from unexpected support surface perturbations, with performance determined by center-of-pressure path length. Whole-body kinematic data were collected to determine body-sway strategy used to maintain stability during each condition. Baselines were determined pre-HDT. Recovery was tracked post-HDT on days 0, 1, 2, and 4. RESULTS Immediately after HDT, subjects showed decreased performance on most SOTs, primarily on sway-referenced support conditions, typically returning to baseline levels within 4 days. MCT performance was not significantly affected. There were no significant gender or duration differences in performance. Kinematic data revealed a tendency to use ankle strategy to maintain an upright stance during most SOT conditions. Interestingly, six subjects (2M,4F) experienced orthostatic intolerance and were unable to complete day 0 testing. CONCLUSION HDT mimics some un loading mechanisms of spaceflight and

  3. Anatomical sector analysis of load-bearing tibial bone structure during 90-day bed rest and 1-year recovery.

    PubMed

    Cervinka, Tomas; Rittweger, Jörn; Hyttinen, Jari; Felsenberg, Dieter; Sievänen, Harri

    2011-07-01

    The aim of this study was to investigate whether the bone response to long bed rest-related immobility and during subsequent recovery differed at anatomically different sectors of tibial epiphysis and diaphysis. For this study, peripheral quantitative tomographic (pQCT) scans obtained from a previous 90-day 'Long Term Bed Rest' intervention were preprocessed with a new method based on statistical approach and re-analysed sector-wise. The pQCT was performed on 25 young healthy males twice before the bed rest, after the bed rest and after 1-year follow-up. All men underwent a strict bed rest intervention, and in addition, seven of them received pamidronate treatment and nine did flywheel exercises as countermeasures against disuse-related bone loss. Clearly, 3-9% sector-specific losses in trabecular density were observed at the tibial epiphysis on average. Similarly, cortical density decreased in a sector-specific way being the largest at the anterior sector of tibial diaphysis. During recovery, the bed rest-induced bone losses were practically restored and no consistent sector-specific modulation was observed in any subgroup. It is concluded that the sector-specific analysis of bone cross-sections has potential to reveal skeletal responses to various interventions that cannot be inferred from the average analysis of the whole bone cross-section. This approach is considered also useful for evaluating the bone responses from the biomechanical point of view. PMID:21672131

  4. Low Magnitude Mechanical Signals Reduce Risk-Factors for Fracture during 90-Day Bed Rest

    NASA Technical Reports Server (NTRS)

    Muir, J. W.; Xia, Y.; Holquin, N.; Judex, S.; Qin, Y.; Evans, H.; Lang, T.; Rubin, C.

    2007-01-01

    Long duration spaceflight leads to multiple deleterious changes to the musculoskeletal system, where loss of bone density, an order of magnitude more severe than that which follows the menopause, combined with increased instability, conspire to elevate the risk of bone fracture due to falls on return to gravitational fields. Here, a ground-based analog for spaceflight is used to evaluate the efficacy of a low-magnitude mechanical intervention, VIBE (Vibrational Inhibition of Bone Erosion), as a potential countermeasure to preserve musculoskeletal integrity in the face of disuse. Twenty-six subjects consented to ninety days of six-degree head-down tilt bed-rest. 18 completed the 90d protocol, 8 of which received daily 10-minute exposure to 30 Hz, 0.3g VIBE, applied in the supine position using a vest elastically coupled to the vibrating platform. The shoulder harness induced a load of 60% of the subjects body weight. At baseline and 90d, Qualitative Ultrasound Scans (QUS) of the calcaneus and CT-scans of the hip and spine were performed to measure changes in bone density. Postural control (PC) was assessed through center of pressure (COP) recordings while subjects stood on a force platform for 4 minutes of quiet stance with eyes closed, and again with eyes opened. As compared to control bedrest subjects,

  5. Vertical jump performance after 90 days bed rest with and without flywheel resistive exercise, including a 180 days follow-up.

    PubMed

    Rittweger, Jörn; Felsenberg, Dieter; Maganaris, Constantinos; Ferretti, José Luis

    2007-07-01

    Muscle atrophy and neuromuscular de-conditioning occur in response to space flight and bed-rest. In this study, we investigated the efficacy of flywheel training to conserve jumping power and height during 90 days bed rest. Twenty-four young healthy men underwent strict bed-rest (-6 degrees head down tilt) for 90 days. Eight participants were assigned to a flywheel group (FW) and 16 to a control group (Ctrl). The ground reaction force was measured during vertical jump tests twice during baseline data collection, and on day 4, 7, 14, 90 and 180 of recovery. In half of the participants, jump tests were also performed within minutes after re-ambulation and on four more occasions during the first 2 days of recovery. Jump height was reduced from 40.6 cm (SD 6.1 cm) during the first baseline measurement to 27.6 cm (SD 5.6 cm) on day 4 of recovery in Ctrl, but only from 38.6 cm (SD 3.9 cm) to 34.4 cm (SD 6.5 cm) in FW (P < 0.001). At the same time, peak power was reduced from 47.4 W/kg (SD 8.0 W/kg) to 34.5 W/kg in Ctrl, but only from 46.2 W/kg (6.0 W/kg) to 42.2 W/kg SD 4.6 W/kg) in FW (P < 0.001). Jump height and peak power were completely recovered after 163 and 140 days in Ctrl, respectively, and after 72 and 18 days in FW (regression analysis). In conclusion, flywheel exercise could effectively offset neuromuscular de-conditioning during bed-rest, and led to full recovery at an earlier stage. These findings nourish the hope that adequate training paradigms can fully sustain neuromuscular function under microgravity conditions. PMID:17406887

  6. Collagen content in the vastus lateralis and the soleus muscle following a 90-day bed rest period with or without resistance exercises

    PubMed Central

    Nielsen, Rasmus Oestergaard; Schjerling, Peter; Tesch, Per; Stål, Per; Langberg, Henning

    2015-01-01

    Summary Introduction spaceflight seems associated with deterioration of the function of the skeletal muscles. Since muscle collagen is critical for muscle function, an improved understanding of the content of the muscle collagen during long-term inactivity seems important. Bed-rest with in-bed resistance training serves as a proxy for the conditions in space. Therefore, ground-based studies may improve the understanding of the consequences of long-term inactivity. Purpose the purpose is to compare the change in collagen protein in the vastus lateralis (VL) and the soleus (SOL) muscle amongst persons exposed to a 90-day bed rest with or without resistance exercise. Methods an explorative analysis was completed based on data from a randomized, controlled trial. The intervention group (BRE, SOL n=4, VL n=8) performed supine-based squat exercises, whereas the controls (BE, SOL n=6, VL n=12) remained inactive during follow-up. Muscle biopsies from vastus lateralis and soleus were taken at baseline (pre) and after 90-days’ follow-up (post). Muscle collagen (μg collagen/mg protein) was quantified. Two-way repeated measurements ANOVA was used to compare the interaction between the intervention (BRE/BR) and time (pre/post) for each muscle. Results the collagen content of VL was similar between pre and post in the BRE group (−3.8 μg collagen/mg protein [95% CI: −22.0; 14.4], p=0.68) while it rose amongst individuals in the BR group (14.9 μg collagen/mg protein [95% CI: −0.01; 29.7], p=0.05). The difference of 18.66 [95% CI: −6.5; 43.9] between BRE and BR across time was, however, not significant (p=0.14). No significant reduction in SOL muscle collagen content was observed from pre to post in the BR group (−9.3 μg collagen/mg protein [95% CI: −24.9; 6.4], p=0.25) or in the BRE group (−6.5 μg collagen/mg protein [95% CI: −25.6; 12.6], p=0.50). There was no difference in the effect of BR versus BRE over time (mean difference −2.78 μg collagen

  7. Recovery of muscle atrophy and bone loss from 90 days bed rest: results from a one-year follow-up.

    PubMed

    Rittweger, J; Felsenberg, D

    2009-02-01

    Earlier studies found the recovery of bone loss after clinical immobilization to be incomplete. It has been argued that this is due to the human skeleton's inability to accrue bone mass once peak bone mass has been attained. However, recent studies suggest that bone losses can fully recover when complete functional rehabilitation is achieved. Accordingly, we hypothesized that bone losses by experimental bed rest would recover within one-year of follow-up. Twenty-five men (mean age 32 years, SD 4.2) were randomly assigned to either bed rest only (Ctrl), resistive flywheel exercise (FW), or to a group receiving 60 mg. i.v pamidronate prior to bed rest (Pam). Calf muscle cross sectional area and bone mineral content of the tibia was measured by peripheral quantitative computed tomography. Calcium, PTH and alkaline phosphatase blood levels were assessed along with urinary desoxypyridinoline excretion. Physical activity was assessed by the Freiburg questionnaire. In Pam and FW, diaphyseal bone losses were completely recovered at a 180-day follow-up, and there was even a small surplus after 1 year (p=0.016). Epiphyseal bone losses were largely, although not completely recovered after 1 year, when they still amounted to -0.6% (SD 1.3%, p=0.034, averaged over all groups). Bone formation and resorption markers had returned to baseline values at this time. However, epiphyseal recovery may still have been on-going, and fitting an exponential model yielded full recovery of the epiphysis within 2 years. Importantly, recovery of calf muscle cross-section and resumption of impact sport activities seemed to precede bone recovery, and bone accrual was closely matching the prior losses on an individual basis. No relationship was found between the epiphyseal BMC deficit at one-year follow-up and the participants' age. Results demonstrate recovery of bed rest induced bone losses in healthy adults. The initial re-accrual rate was remarkably high and is comparable to the accrual of bone

  8. Bed rest in pregnancy.

    PubMed

    Bigelow, Catherine; Stone, Joanne

    2011-01-01

    The use of bed rest in medicine dates back to Hippocrates, who first recommended bed rest as a restorative measure for pain. With the formalization of prenatal care in the early 1900s, maternal bed rest became a standard of care, especially toward the end of pregnancy. Antepartum bed rest is a common obstetric management tool, with up to 95% of obstetricians utilizing maternal activity restriction in some way in their practice. Bed rest is prescribed for a variety of complications of pregnancy, from threatened abortion and multiple gestations to preeclampsia and preterm labor. Although the use of bed rest is pervasive, there is a paucity of data to support its use. Additionally, many well-documented adverse physical, psychological, familial, societal, and financial effects have been discussed in the literature. There have been no complications of pregnancy for which the literature consistently demonstrates a benefit to antepartum bed rest. Given the well-documented adverse effects of bed rest, disruption of social relationships, and financial implications of this intervention, there is a real need for scientific investigation to establish whether this is an appropriate therapeutic modality. Well-designed randomized, controlled trials of bed rest versus normal activity for various complications of pregnancy are required to lay this debate to rest once and for all. PMID:21425272

  9. Bed rest and immunity

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Gerald; Aviles, Hernan; Butel, Janet S.; Shearer, William T.; Niesel, David; Pandya, Utpal; Allen, Christopher; Ochs, Hans D.; Blancher, Antoine; Abbal, Michel

    2007-02-01

    Space flight has been shown to result in altered immune responses. The current study was designed to investigate this possibility by using the bed rest model of some space flight conditions. A large number of women are included as subjects in the study. The hypothesis being tested is: 60 days head-down tilt bed rest of humans will affect the immune system and resistance to infection. Blood, urine and saliva samples will be obtained from bed rest subjects prior to, at intervals during, and after completion of 60 days of head-down tilt bed rest. Leukocyte blastogenesis, cytokine production and virus reactivation will be assessed. The ability of the subjects to respond appropriately to immunization with the neoantigen bacteriophage φX-174 will also be determined. Bed rest is being carried out at MEDES, Toulouse France, and the University of Texas Medical Branch, Galveston, TX. The studies to be carried out in France will also allow assessment of the effects of muscle/bone exercise and nutritional countermeasures on the immune system in addition to the effects of bed rest.

  10. Bed rest during pregnancy

    MedlinePlus

    ... for support groups, bulletin boards, and chat rooms online for moms-to-be who are also on bed rest. Expect emotional ups and downs. Share your hopes and worries with your partner. Let each other vent if needed. If sex is not allowed, look for other ways to ...

  11. Bed Rest Muscular Atrophy

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.

    2000-01-01

    A major debilitating response from prolonged bed rest (BR) is muscle atrophy, defined as a "decrease in size of a part of tissue after full development has been attained: a wasting away of tissue as from disuse, old age, injury or disease". Part of the complicated mechanism for the dizziness, increased body instability, and exaggerated gait in patients who arise immediately after BR may be a result of not only foot pain, but also of muscular atrophy and associated reduction in lower limb strength. Also, there seems to be a close association between muscle atrophy and bone atrophy. A discussion of many facets of the total BR homeostatic syndrome has been published. The old adage that use determines form which promotes function of bone (Wolff's law) also applies to those people exposed to prolonged BR (without exercise training) in whom muscle atrophy is a consistent finding. An extreme case involved a 16-year-old boy who was ordered to bed by his mother in 1932: after 50 years in bed he had "a lily-white frame with limbs as thin as the legs of a ladder-back chair". These findings emphasize the close relationship between muscle atrophy and bone atrophy. In addition to loss of muscle mass during deconditioning, there is a significant loss of muscle strength and a decrease in protein synthesis. Because the decreases in force (strength) are proportionately greater than those in fiber size or muscle cross-sectional area, other contributory factors must be involved; muscle fiber dehydration may be important.

  12. Flight Analogs (Bed Rest Research)

    NASA Video Gallery

    Flight Analogs / Bed Rest Research Projects provide NASA with a ground based research platform to complement space research. By mimicking the conditions of weightlessness in the human body here on ...

  13. Physiology Of Prolonged Bed Rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.

    1991-01-01

    Report describes physiological effects of prolonged bed rest. Rest for periods of 24 hours or longer deconditions body to some extent; healing proceeds simultaneously with deconditioning. Report provides details on shifts in fluid electrolytes and loss of lean body mass, which comprises everything in body besides fat - that is, water, muscle, and bone. Based on published research.

  14. Clinical physiology of bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.

    1993-01-01

    Maintenance of optimal health in humans requires the proper balance between exercise, rest, and sleep as well as time in the upright position. About one-third of a lifetime is spent sleeping; and it is no coincidence that sleeping is performed in the horizontal position, the position in which gravitational influence on the body is minimal. Although enforced bed rest is necessary for the treatment of some ailments, in some cases it has probably been used unwisely. In addition to the lower hydrostatic pressure with the normally dependent regions of the cardiovascular system, body fuid compartments during bed rest in the horizontal body position, and virtual elimination of compression on the long bones of the skeletal system during bed rest (hypogravia), there is often reduction in energy metabolism due to the relative confinement (hypodynamia) and alteration of ambulatory circadian variations in metabolism, body temperature, and many hormonal systems. If patients are also moved to unfamiliar surroundings, they probably experience some feelings of anxiety and some sociopsychological problems. Adaptive physiological responses during bed rest are normal for that environment. They are attempts by the body to reduce unnecessary energy expenditure, to optimize its function, and to enhance its survival potential. Many of the deconditioning responses begin within the first day or two of bed rest; these early responses have prompted physicians to insist upon early resumption of the upright posture and ambulation of bedridden patients.

  15. Cognitive Functioning in Long Duration Head-down Bed Rest

    NASA Technical Reports Server (NTRS)

    Seaton, Kimberly A.; Slack, Kelley J.; Sipes, Walter A.; Bowie, Kendra

    2008-01-01

    The Space Flight Cognitive Assessment Tool for Windows (WinSCAT) is a self-administered battery of tests used on the International Space Station for evaluating cognitive functioning. Here, WinSCAT was used to assess cognitive functioning during extended head-down bed rest. Thirteen subjects who participated in 60 or 90 days of 6 deg head-down bed rest took WinSCAT during the pre-bed rest phase, the in-bed rest phase, and the post-bed rest (reconditioning) phase of study participation. After adjusting for individual baseline performance, 12 off-nominal scores were observed out of 351 total observations during bed rest and 7 of 180 during reconditioning. No evidence was found for systematic changes in off-nominal incidence as time in bed rest progressed, or during the reconditioning period. Cognitive functioning does not appear to be adversely affected by long duration head-down bed rest. Individual differences in underlying cognitive ability and motivation level are likely explanations for the current findings.

  16. Nutritional Status in Humans during Long-Duration Bed Rest

    NASA Technical Reports Server (NTRS)

    Smith, Scott M.; MatthewsOliver, Susan A.; Dillon, E. Lichar; Fesperman, Vernell

    2006-01-01

    Bed rest is a valuable ground-based model for many of the physiological changes associated with space flight. A series of studies was undertaken to evaluate nutritional changes during and after 60 or 90 days of -6 head-down-tilt bed rest. A total of 11 subjects (8 M, 3 F; age 26-55 y) participated in the studies. Blood and urine were collected twice before bed rest and once per month during bed rest. Samples were analyzed in batch at the end of each study. Data were analyzed using repeated-measures ANOVA. Markers of bone resorption (such as n-telopeptide excretion, p less than 0.05) increased during bed rest, and 25-OH vitamin D status tended to decline (p=0.06). During bed rest oxidative damage markers, such as superoxide dismutase increased (p less than 0.01) and 8-(OH)-2'-deoxyguanosine tended to increase (p=0.07); whereas total antioxidant capacity decreased (p less than 0.02). Iron status indices showed patterns of increased iron stores, with decreased transferrin receptors (p less than 0.001). Biochemical markers revealed a tendency toward a loss of muscle mass, by lower excretion of creatinine and 3-methyl-histidine during bed rest. All of these changes are very similar to those observed during space flight, and further document the utility of bed rest as a model of space flight.

  17. The NASA Bed Rest Project

    NASA Technical Reports Server (NTRS)

    Rhodes, Bradley; Meck, Janice

    2005-01-01

    NASA s National Vision for Space Exploration includes human travel beyond low earth orbit and the ultimate safe return of the crews. Crucial to fulfilling the vision is the successful and timely development of countermeasures for the adverse physiological effects on human systems caused by long term exposure to the microgravity environment. Limited access to in-flight resources for the foreseeable future increases NASA s reliance on ground-based analogs to simulate these effects of microgravity. The primary analog for human based research will be head-down bed rest. By this approach NASA will be able to evaluate countermeasures in large sample sizes, perform preliminary evaluations of proposed in-flight protocols and assess the utility of individual or combined strategies before flight resources are requested. In response to this critical need, NASA has created the Bed Rest Project at the Johnson Space Center. The Project establishes the infrastructure and processes to provide a long term capability for standardized domestic bed rest studies and countermeasure development. The Bed Rest Project design takes a comprehensive, interdisciplinary, integrated approach that reduces the resource overhead of one investigator for one campaign. In addition to integrating studies operationally relevant for exploration, the Project addresses other new Vision objectives, namely: 1) interagency cooperation with the NIH allows for Clinical Research Center (CRC) facility sharing to the benefit of both agencies, 2) collaboration with our International Partners expands countermeasure development opportunities for foreign and domestic investigators as well as promotes consistency in approach and results, 3) to the greatest degree possible, the Project also advances research by clinicians and academia alike to encourage return to earth benefits. This paper will describe the Project s top level goals, organization and relationship to other Exploration Vision Projects, implementation

  18. 90-Day Cycle Handbook

    ERIC Educational Resources Information Center

    Park, Sandra; Takahashi, Sola

    2013-01-01

    90-Day Cycles are a disciplined and structured form of inquiry designed to produce and test knowledge syntheses, prototyped processes, or products in support of improvement work. With any type of activity, organizations inevitably encounter roadblocks to improving performance and outcomes. These barriers might include intractable problems at…

  19. Physiology of prolonged bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.

    1988-01-01

    Bed rest has been a normal procedure used by physicians for centuries in the treatment of injury and disease. Exposure of patients to prolonged bed rest in the horizontal position induces adaptive deconditioning responses. While deconditioning responses are appropriate for patients or test subjects in the horizontal position, they usually result in adverse physiological responses (fainting, muscular weakness) when the patient assume the upright posture. These deconditioning responses result from reduction in hydrostatic pressure within the cardiovascular system, virtual elimination of longitudinal pressure on the long bones, some decrease in total body metabolism, changes in diet, and perhaps psychological impact from the different environment. Almost every system in the body is affected. An early stimulus is the cephalic shift of fluid from the legs which increases atrial pressure and induces compensatory responses for fluid and electrolyte redistribution. Without countermeasures, deterioration in strength and muscle function occurs within 1 wk while increased calcium loss may continue for months. Research should also focus on drug and carbohydrate metabolism.

  20. [Kidney stone formation during space flight and long-term bed rest].

    PubMed

    Okada, Atsushi; Ichikawa, Jun; Tozawa, Keiichi

    2011-10-01

    Microgravity environment like space flight or a condition requiring long-term bed-rest increase bone resorption and decrease bone formation, inducing the rapid decrease of bone minerals to osteoporosis. Bone mineral loss increases urinary calcium excretion and the risk of urinary stone formation. To clarify the influence of the conditions on renal stone formation, a 90-day bed rest test was performed to analyze the mechanism of microgravity or bed rest-induced stone formation and prevention by bisphosphonate medication and bed-rest exercise. As the results, renal stone formation was observed in control and exercise groups and no stone was seen in the medication group. In the medication group, urinary calcium excretion and relative supersaturation of calcium oxalate were lower than in the control group throughout the bed-rest and recovery period. Bisphosphonate is useful for the prevention of renal stone formation during space flight and long-term bed-rest. PMID:21960236

  1. Gender Differences in Bed Rest: Preliminary Analysis of Vascular Function

    NASA Technical Reports Server (NTRS)

    Platts, Steven H.; Stenger, Michael B.; Martin, David S.; Freeman-Perez, Sondra A.; Phillips, Tiffany; Ribeiro, L. Christine

    2008-01-01

    Orthostatic intolerance is a recognized consequence of spaceflight. Numerous studies have shown that women are more susceptible to orthostatic intolerance following spaceflight as well as bed rest, the most commonly used ground-based analog for spaceflight. One of the possible mechanisms proposed to account for this is a difference in vascular responsiveness between genders. We hypothesized that women and men would have differing vascular responses to 90 days of 6-degree head down tilt bed rest. Additionally, we hypothesized that vessels in the upper and lower body would respond differently, as has been shown in the animal literature. Thirteen subjects were placed in bedrest for 90 days (8 men, 5 women) at the Flight Analogs Unit, UTMB. Direct arterial and venous measurements were made with ultrasound to evaluate changes in vascular structure and function. Arterial function was assessed, in the arm and leg, during a reactive hyperemia protocol and during sublingual nitroglycerin administration to gauge the contributions of endothelial dependent and independent dilator function respectively. Venous function was assessed in dorsal hand and foot veins during the administration of pharmaceuticals to assess constrictor and dilator function. Both gender and day effects are seen in arterial dilator function to reactive hyperemia, but none are seen with nitroglycerin. There are also differences in the wall thickness in the arm vs the leg during bed rest, which return toward pre-bed rest levels by day 90. More subjects are required, especially females as there is not sufficient power to properly analyze venous function. Day 90 data are most underpowered.

  2. International Standardization of Bed Rest Standard Measures

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.

    2010-01-01

    This slide presentation gives an overview of the standardization of bed rest measures. The International Countermeasures Working Group attempted to define and agree internationally on standard measurements for spaceflight based bed rest studies. The group identified the experts amongst several stakeholder agencys. It included information on exercise, muscle, neurological, psychological, bone and cardiovascular measures.

  3. Retrospective Study of Serum Sclerostin Measurements in Bed Rest Subjects

    NASA Technical Reports Server (NTRS)

    Spatz, J. M.; Fields, E. E.; Yu, E. W.; Divieti, Pajevic P.; Bouxsein, M. L.; Sibonga, M. L.; Zwart, S. R.; Smith, S. M.

    2011-01-01

    Animal models and human studies suggest that osteocytes regulate the skeleton s response to mechanical unloading at the cellular level in part by an increase in sclerostin, an inhibitor of the anabolic Wnt pathway. However, few studies have reported changes in serum sclerostin in humans exposed to reduced mechanical loading. Thus, we determined changes in serum sclerostin and bone turnover markers in healthy adult men who participated in a controlled bed rest study. Seven healthy adult men (31 +/- 3 yrs old) underwent 90-day six-degree head down tilt bed rest at the University of Texas Medical Branch in Galveston's Institute for Translational Sciences - Clinical Research Center (ITS-CRC). Serum sclerostin, PTH, serum markers of bone turnover (bone specific alkaline phosphatase, RANKL/OPG, and osteocalcin), urinary calcium and phosphorus excretion, and 24 hour pooled urinary markers of bone resorption (NTX, DPD, PYD) were evaluated pre-bed rest (BL), bed rest day 28 (BR-28), bed rest day 60 (BR-60), and bed rest day 90 (BR-90). In addition, bone mineral density (BMD) was assessed by dual-energy X-ray absorptiometry (DXA) at BL, BR-60, and post bed rest day 5 (BR+5). Data are reported as mean +/- standard deviation. We used repeated measures ANOVA to compare baseline values to BR-28, BR-60, and BR-90. RESULTS Consistent with prior reports, BMD declined significantly (1-2% per month) at weight-bearing skeletal sites (spine, hip, femur neck, and calcaneus). Serum sclerostin levels were elevated above BL at BR-28 (+29% +/- 20%, p = 0.003), BR-60 (+42% +/- 31%, p < 0.001), and BR-90 (22% +/- 21%, p = 0.07). Serum PTH levels were reduced at BR-28 (-17% +/- 16%, p = 0.02), BR-60 (-24% +/- 14%, p = 0.03), and returned to baseline at BR-90 (-21% +/- 21%, p = 0.14). Serum bone turnover markers did not change, however urinary bone resorption markers and calcium were significantly elevated following bed rest (p < 0.01). CONCLUSION We observed an increase of serum sclerostin

  4. Effects Of Exercise During Bed Rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.; Bernauer, Edmund M.

    1993-01-01

    Pair of reports adds to growing body of knowledge of physical deconditioning caused by prolonged bed rest and effectiveness of various exercise regimens in preserving or restoring fitness. Major objective to determine what regimens to prescribe to astronauts before flight, during prolonged weightlessness, and immediately before returning to Earth. Knowledge also benefits patients confined by illness or injury. First report discusses experiment on effects of two types of periodic, intense, short-duration exercise during bed rest. Experiment also discussed in documents "Effects Of Exercise During Prolonged Bed Rest" (ARC-12190), and "Isotonic And Isokinetic Exercise During Bed Rest" (ARC-12180). Second report reviews knowledge acquired with view toward development of protocols for exercise regimens.

  5. The Physiology of Bed Rest. Chapter 39

    NASA Technical Reports Server (NTRS)

    Fortney, Suzanne M.; Schneider, Victor S.; Greenleaf, John E.

    1996-01-01

    Prolonged rest in bed has been utilized by physicians and other health-care workers to immobilize and confine patients for rehabilitation and restoration of health since time immemorial. The sitting or horizontal position is sought by the body to relieve the strain of the upright or vertical postures, for example during syncopal situations, bone fractures, muscle injuries, fatigue, and probably also to reduce energy expenditure. Most health-care personnel are aware that adaptive responses occurring during bed rest proceed concomitantly with the healing process; signs and symptoms associated with the former should be differentiated from those of the latter. Not all illnesses and infirmities benefit from prolonged bed rest. Considerations in prescribing bed rest for patients-including duration, body position, mode and duration of exercise, light-dark cycles, temperature, and humidity-have not been investigated adequately. More recently, adaptive physiological responses have been measured in normal, healthy subjects in the horizontal or slightly head-down postures during prolonged bed rest as analogs for the adaptive responses of astronauts exposed to the microgravity environment of outer and bed-rest research.

  6. Exercise countermeasures for bed-rest deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, John (Editor)

    1993-01-01

    The purpose for this 30-day bed rest study was to investigate the effects of short-term, high intensity isotonic and isokinetic exercise training on maintenance of working capacity (peak oxygen uptake), muscular strength and endurance, and on orthostatic tolerance, posture and gait. Other data were collected on muscle atrophy, bone mineralization and density, endocrine analyses concerning vasoactivity and fluid-electrolyte balance, muscle intermediary metabolism, and on performance and mood of the subjects. It was concluded that: The subjects maintained a relatively stable mood, high morale, and high esprit de corps throughout the study. Performance improved in nearly all tests in almost all the subjects. Isotonic training, as opposed to isokinetic exercise training, was associated more with decreasing levels of psychological tension, concentration, and motivation; and improvement in the quality of sleep. Working capacity (peak oxygen uptake) was maintained during bed rest with isotonic exercise training; it was not maintained with isokinetic or no exercise training. In general, there was no significant decrease in strength or endurance of arm or leg muscles during bed rest, in spite of some reduction in muscle size (atrophy) of some leg muscles. There was no effect of isotonic exercise training on orthostasis, since tilt-table tolerance was reduced similarly in all three groups following bed rest. Bed rest resulted in significant decreases of postural stability and self-selected step length, stride length, and walking velocity, which were not influenced by either exercise training regimen. Most pre-bed rest responses were restored by the fourth day of recovery.

  7. Cardiac atrophy after bed rest and spaceflight

    NASA Technical Reports Server (NTRS)

    Perhonen, M. A.; Franco, F.; Lane, L. D.; Buckey, J. C.; Blomqvist, C. G.; Zerwekh, J. E.; Peshock, R. M.; Weatherall, P. T.; Levine, B. D.

    2001-01-01

    Cardiac muscle adapts well to changes in loading conditions. For example, left ventricular (LV) hypertrophy may be induced physiologically (via exercise training) or pathologically (via hypertension or valvular heart disease). If hypertension is treated, LV hypertrophy regresses, suggesting a sensitivity to LV work. However, whether physical inactivity in nonathletic populations causes adaptive changes in LV mass or even frank atrophy is not clear. We exposed previously sedentary men to 6 (n = 5) and 12 (n = 3) wk of horizontal bed rest. LV and right ventricular (RV) mass and end-diastolic volume were measured using cine magnetic resonance imaging (MRI) at 2, 6, and 12 wk of bed rest; five healthy men were also studied before and after at least 6 wk of routine daily activities as controls. In addition, four astronauts were exposed to the complete elimination of hydrostatic gradients during a spaceflight of 10 days. During bed rest, LV mass decreased by 8.0 +/- 2.2% (P = 0.005) after 6 wk with an additional atrophy of 7.6 +/- 2.3% in the subjects who remained in bed for 12 wk; there was no change in LV mass for the control subjects (153.0 +/- 12.2 vs. 153.4 +/- 12.1 g, P = 0.81). Mean wall thickness decreased (4 +/- 2.5%, P = 0.01) after 6 wk of bed rest associated with the decrease in LV mass, suggesting a physiological remodeling with respect to altered load. LV end-diastolic volume decreased by 14 +/- 1.7% (P = 0.002) after 2 wk of bed rest and changed minimally thereafter. After 6 wk of bed rest, RV free wall mass decreased by 10 +/- 2.7% (P = 0.06) and RV end-diastolic volume by 16 +/- 7.9% (P = 0.06). After spaceflight, LV mass decreased by 12 +/- 6.9% (P = 0.07). In conclusion, cardiac atrophy occurs during prolonged (6 wk) horizontal bed rest and may also occur after short-term spaceflight. We suggest that cardiac atrophy is due to a physiological adaptation to reduced myocardial load and work in real or simulated microgravity and demonstrates the plasticity

  8. Exercise Training During Bed Rest Attenuates Deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Hargens, Alan R. (Technical Monitor)

    1995-01-01

    A 30-day 6 deg. head-down bed rest study was conducted to evaluate high-intensity, short-duration, alternating isotonic cycle ergometer exercise (ITE) training and high-intensity intermittent isokinetic exercise (IKE) training regiments designed to maintain peak VO2 and muscle mass, strength, and endurance at ambulatory control levels throughout prolonged bed rest. Other elements of the deconditioning (acclimation) syndrome, such as proprioception, psychological performance, hypovolemia, water balance, body composition, and orthostatic tolerance, were also measured. Compared with response during bed rest of the no exercise (NOE) control group: the ITE training regimen (a) maintained work capacity (peak VO2), (b) maintained plasma and red cell volume, (c) induced positive body water balance, (d) decreased quality of sleep and mental concentration, and (e) had no effect on the decrease in orthostatic tolerance; the IKE training regimen (a) attenuated the decrease in peak VO2 by 50%, (b) attenuated loss of red cell volume by 40%, but had no effect on loss of plasma volume, (c) induced positive body water balance, (d) had no adverse effect on quality of sleep or concentration, and (e) had no effect on the decrease in orthostatic tolerance. These findings suggest that various elements of the deconditioning syndrome can be manipulated by duration and intensity of ITE or IKE training regiments, and that several different training protocols will be required to maintain or restore physiological and psychological performance of individuals confined to prolonged bed rest.

  9. Effects Of Exercise During Prolonged Bed Rest

    NASA Technical Reports Server (NTRS)

    Arnaud, S.; Berry, P; Cohen, M.; Danelis, J.; Deroshia, C.; Greenleaf, J.; Harris, B.; Keil, L.; Bernauer, E.; Bond, M.; Ellis, S.; Lee, P.; Selzer, R.; Wade, C.

    1992-01-01

    Report describes experiment to investigate effects of isotonic and isokinetic leg exercises in counteracting effects of bed rest upon physical and mental conditions of subjects. Data taken on capacity for work, endurance and strength, tolerance to sitting up, equilibrium, posture, gait, atrophy, mineralization and density of bones, endocrine analyses concerning vasoactivity and fluid and electrolyte balances, intermediary metabolism of muscles, mood, and performance.

  10. Sex‐specific responses of bone metabolism and renal stone risk during bed rest

    PubMed Central

    Morgan, Jennifer L. L.; Heer, Martina; Hargens, Alan R.; Macias, Brandon R.; Hudson, Edgar K.; Shackelford, Linda C.; Zwart, Sara R.; Smith, Scott M.

    2014-01-01

    Abstract The purpose of this study was to directly assess sex differences in bone loss, bone biochemistry, and renal stone risk in bed rest. Bed rest simulates some spaceflight effects on human physiology and can be used to address the potential existence of sex‐specific effects on bone metabolism and renal stone risk in space. We combined data from the control subjects in five head‐down‐tilt bed rest studies (combined n = 50 men, 24 women) of differing durations (14–90 days). All subjects were healthy volunteers. Mean age was 35 ± 9 years for women and 33 ± 8 years for men. The main outcome measures were bone density and biochemistry, and renal stone risk chemistry. Before bed rest began, men had higher bone mineral density and content (P < 0.001), and excreted more biomarkers of bone resorption and calcium per day than did women (P < 0.05). These differences remained during bed rest. A number of urine chemistry analytes increased (e.g., calcium) or decreased (e.g., sodium, citrate, and urine volume) significantly for men and women during bed rest. These changes may predispose men to higher stone risk. Men and women do not have substantially different responses to the skeletal unloading of bed rest. PMID:25107989

  11. Exercise countermeasures for bed rest deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, John (Editor)

    1989-01-01

    The major objectives were to evaluate the efficiency of different modes of exercise (isotonic and isokinetic) for countering the effects of bed rest deconditioning on work capacity (peak oxygen uptake), muscular strength, orthostatic tolerance, posture, equilibrium and gait; and to collect additional data of a more fundamental nature to help understand how these deconditioning responses occur. These data will be used for writing prescriptions for exercise to be utilized by astronauts for maintaining work capacity and well-being on Freedom Station, and to determine what exercise devices should be place in the station.

  12. Exercise thermoregulation after 14 days of bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Reese, R. D.

    1980-01-01

    The effects of bed rest and exercise training during bed rest on body temperature and thermoregulatory responses at rest and during exercise are investigated. Seven male subjects underwent three two-week periods of bed rest during which isometric, isotonic, or no exercises were performed, separated by two ambulatory control periods and preceded by a two-week control period, during which they exercised regularly. Rectal and mean skin temperatures and sweating responses were determined during 70-min submaximal supine exercise during the bed rest and recovery periods. Measurements reveal a reduction in basal oral temperature during the control-recovery periods, with a relatively constant level during bed rest periods, and a significant increase in the rectal temperature elavation brought on by exercise following all three bed-rest regimes. It is concluded that the excessive increase in rectal temperature could be influenced by changes in skin heat conductance or the inhibition of sweating.

  13. Recovery After Prolonged Bed-Rest Deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.; Quach, David T.

    2003-01-01

    Recovery data were analyzed from normal healthy test subjects maintained in the horizontal or head-down body position in well-controlled bed rest (BR) studies in which adherence to the well-designed protocol was monitored. Because recovery data were almost always of secondary importance to the data collected during the BR period, there was little consistency in the recovery experimental designs regarding control factors (e.g., diet or exercise), duration, or timing of data collection. Thus, only about half of the BR studies that provided appropriate data were analyzed here. These recovery data were sorted into two groups: those from BR protocols of less than 37 days, and those from protocols greater than 36 days. There was great disparity in the unchanged responses at the end of BR in these two groups. Likewise with the variables that required more than 40 days for recovery; for example, some immune variables required more than 180 days. Knowledge of the recovery process after BR in healthy people should assist rehabilitation workers in differentiating "healthy" BR recovery responses from those of the infirmity of sick or injured patients; this should result in more appropriate and efficient health care.

  14. Lack of evidence for prescription of antepartum bed rest

    PubMed Central

    Maloni, Judith A

    2011-01-01

    Antepartum bed-rest treatment is based on assumptions that it is both effective and safe for mother and fetus. However, research indicates, that bed-rest treatment is ineffective for preventing preterm birth and fetal growth restriction, and for increasing gestational age at birth and infant birthweight. Studies of women treated with pregnancy bed-rest identify numerous side effects, including muscle atrophy, bone loss, weight loss, decreased infant birthweight in singleton gestations and gestational age at birth, and psychosocial problems. Studies conducted by aerospace scientists who have used bed rest as a model for the study of weightlessness in space using nonpregnant individuals report similar results. Antepartum bed-rest treatment should be discontinued until evidence of effectiveness is found. PMID:22140399

  15. Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Wood, S. J.; Cerisano, J. M.; Kofman, I. S.; Fisher, E. A.; Esteves, J. T.; Taylor, L. C.; DeDios, Y. E.; Harm, D. L.

    2011-01-01

    Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed

  16. Long-duration bed rest as an analog to microgravity.

    PubMed

    Hargens, Alan R; Vico, Laurence

    2016-04-15

    Long-duration bed rest is widely employed to simulate the effects of microgravity on various physiological systems, especially for studies of bone, muscle, and the cardiovascular system. This microgravity analog is also extensively used to develop and test countermeasures to microgravity-altered adaptations to Earth gravity. Initial investigations of bone loss used horizontal bed rest with the view that this model represented the closest approximation to inactivity and minimization of hydrostatic effects, but all Earth-based analogs must contend with the constant force of gravity by adjustment of the G vector. Later concerns about the lack of similarity between headward fluid shifts in space and those with horizontal bed rest encouraged the use of 6 degree head-down tilt (HDT) bed rest as pioneered by Russian investigators. Headward fluid shifts in space may redistribute bone from the legs to the head. At present, HDT bed rest with normal volunteers is the most common analog for microgravity simulation and to test countermeasures for bone loss, muscle and cardiac atrophy, orthostatic intolerance, and reduced muscle strength/exercise capacity. Also, current physiologic countermeasures are focused on long-duration missions such as Mars, so in this review we emphasize HDT bed rest studies with durations of 30 days and longer. However, recent results suggest that the HDT bed rest analog is less representative as an analog for other important physiological problems of long-duration space flight such as fluid shifts, spinal dysfunction and radiation hazards. PMID:26893033

  17. Reduction in peak oxygen uptake after prolonged bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Kozlowski, S.

    1982-01-01

    The hypothesis that the magnitude of the reduction in peak oxygen uptake (VO2) after bed rest is directly proportional to the level of pre-bed rest peak VO2 is tested. Complete pre and post-bed rest working capacity and body weight data were obtained from studies involving 24 men (19-24 years old) and 8 women (23-34 years old) who underwent bed rest for 14-20 days with no remedial treatments. Results of regression analyses of the present change in post-bed rest peak VO2 on pre-bed rest peak VO2 with 32 subjects show correlation coefficients of -0.03 (NS) for data expressed in 1/min and -0.17 for data expressed in ml/min-kg. In addition, significant correlations are found that support the hypothesis only when peak VO2 data are analyzed separately from studies that utilized the cycle ergometer, particularly with subjects in the supine position, as opposed to data obtained from treadmill peak VO2 tests. It is concluded that orthostatic factors, associated with the upright body position and relatively high levels of physical fitness from endurance training, appear to increase the variability of pre and particularly post-bed rest peak VO2 data, which would lead to rejection of the hypothesis.

  18. Cardiovascular consequences of bed rest: effect on maximal oxygen uptake

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.

    1997-01-01

    Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age or gender. Bed rest induces an elevated maximal heart rate which, in turn, is associated with decreased cardiac vagal tone, increased sympathetic catecholamine secretion, and greater cardiac beta-receptor sensitivity. Despite the elevation in heart rate, VO2max is reduced primarily from decreased maximal stroke volume and cardiac output. An elevated ejection fraction during exercise following bed rest suggests that the lower stroke volume is not caused by ventricular dysfunction but is primarily the result of decreased venous return associated with lower circulating blood volume, reduced central venous pressure, and higher venous compliance in the lower extremities. VO2max, stroke volume, and cardiac output are further compromised by exercise in the upright posture. The contribution of hypovolemia to reduced cardiac output during exercise following bed rest is supported by the close relationship between the relative magnitude (% delta) and time course of change in blood volume and VO2max during bed rest, and also by the fact that retention of plasma volume is associated with maintenance of VO2max after bed rest. Arteriovenous oxygen difference during maximal exercise is not altered by bed rest, suggesting that peripheral mechanisms may not contribute significantly to the decreased VO2max. However reduction in baseline and maximal muscle blood flow, red blood cell volume, and capillarization in working muscles represent peripheral mechanisms that may contribute to limited oxygen delivery and, subsequently, lowered VO2max. Thus, alterations in cardiac and vascular functions induced by prolonged confinement to bed rest contribute to diminution of maximal oxygen uptake

  19. Cardiovascular consequences of bed rest: effect on maximal oxygen uptake.

    PubMed

    Convertino, V A

    1997-02-01

    Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age or gender. Bed rest induces an elevated maximal heart rate which, in turn, is associated with decreased cardiac vagal tone, increased sympathetic catecholamine secretion, and greater cardiac beta-receptor sensitivity. Despite the elevation in heart rate, VO2max is reduced primarily from decreased maximal stroke volume and cardiac output. An elevated ejection fraction during exercise following bed rest suggests that the lower stroke volume is not caused by ventricular dysfunction but is primarily the result of decreased venous return associated with lower circulating blood volume, reduced central venous pressure, and higher venous compliance in the lower extremities. VO2max, stroke volume, and cardiac output are further compromised by exercise in the upright posture. The contribution of hypovolemia to reduced cardiac output during exercise following bed rest is supported by the close relationship between the relative magnitude (% delta) and time course of change in blood volume and VO2max during bed rest, and also by the fact that retention of plasma volume is associated with maintenance of VO2max after bed rest. Arteriovenous oxygen difference during maximal exercise is not altered by bed rest, suggesting that peripheral mechanisms may not contribute significantly to the decreased VO2max. However reduction in baseline and maximal muscle blood flow, red blood cell volume, and capillarization in working muscles represent peripheral mechanisms that may contribute to limited oxygen delivery and, subsequently, lowered VO2max. Thus, alterations in cardiac and vascular functions induced by prolonged confinement to bed rest contribute to diminution of maximal oxygen uptake

  20. Effect of exercise on the pseudodiabetes of bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.

    1982-01-01

    The effect of intensive isotonic exercise and isometric exercise (with its low metabolic rate) during bed rest on plasma insulin and glucose tolerance test was investigated. The subjects were seven healthy men, 19 to 22 years in age, 166 to 188 cm in height, and 62.40 to 103.80 kg in weight; maximal oxygen uptakes ranged from 3.36 to 4.38 liters/min. It appears that bed-rest-induced glucose intolerance is diminished with increasing energy expenditure during both bed rest and recovery.

  1. Stretch Reflex as a Simple Measure to Evaluate the Efficacy of Potential Flight Countermeasures Using the Bed Rest Environment

    NASA Technical Reports Server (NTRS)

    Cerisano, J. M.; Reschke, M. F.; Kofman, I. S.; Fisher, E. A.; Harm, D. L.

    2010-01-01

    INTRODUCTION: Spaceflight is acknowledged to have significant effects on the major postural muscles. However, it has been difficult to separate the effects of ascending somatosensory changes caused by the unloading of these muscles during flight from changes in sensorimotor function caused by a descending vestibulo-cerebellar response to microgravity. It is hypothesized that bed rest is an adequate model to investigate postural muscle unloading given that spaceflight and bed rest may produce similar results in both nerve axon and muscle tissue. METHODS: To investigate this hypothesis, stretch reflexes were measured on 18 subjects who spent 60 to 90 days in continuous 6 head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 deg at a peak velocity of approximately 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender and compared with spaceflight data. RESULTS: Although no gender differences were found, bed rest induced changes in reflex latency and CV similar to the ones observed during spaceflight. Also, a relationship between CV and loss of muscle strength in the lower leg was observed for most bed rest subjects. CONCLUSION: Even though bed rest (limb unloading) alone may not mimic all of the synaptic and muscle tissue loss that is observed as a result of spaceflight, it can serve as a working analog of flight for the evaluation of potential countermeasures that may be beneficial in mitigating unwanted changes in the major postural muscles that are observed post flight.

  2. Bed rest after embryo transfer: Is it harmful?

    PubMed

    Küçük, M

    2013-04-01

    Many interventions have been proposed to increase the success of assisted reproductive techniques (ART). The most controversial is bed rest after embryo transfer (ET). Patients are frequently advised to restrict their physical activity (PA) during ART, and many fertility clinics recommend bed rest after ET for variable periods of time. It is the author's belief, however, that there is insufficient evidence to support the recommendation of bed rest after ET. In fact, accumulated data indicate that bed rest after ET or restriction of PA during ART not only fails to bring about benefits, but may actually be detrimental and associated with worse ART outcomes. As such, it is considered that the long-standing policy of bed rest after ET should be abandoned. Patients should not be encouraged to rest in bed after ET, and should maintain their routine PA during ART. If the practice is to be changed, it is important to recognize the reasons why patients tend to restrict their PA during this time period. Health professionals may play a key role in this context.

  3. Attenuated sympathetic nerve responses after 24 hours of bed rest

    NASA Technical Reports Server (NTRS)

    Khan, Mazhar H.; Kunselman, Allen R.; Leuenberger, Urs A.; Davidson, William R Jr; Ray, Chester A.; Gray, Kristen S.; Hogeman, Cynthia S.; Sinoway, Lawrence I.

    2002-01-01

    Bed rest reduces orthostatic tolerance. Despite decades of study, the cause of this phenomenon remains unclear. In this report we examined hemodynamic and sympathetic nerve responses to graded lower body negative pressure (LBNP) before and after 24 h of bed rest. LBNP allows for baroreceptor disengagement in a graded fashion. We measured heart rate (HR), cardiac output (HR x stroke volume obtained by echo Doppler), and muscle sympathetic nerve activity (MSNA) during a progressive and graded LBNP paradigm. Negative pressure was increased by 10 mmHg every 3 min until presyncope or completion of -60 mmHg. After bed rest, LBNP tolerance was reduced in 11 of 13 subjects (P <.023), HR was greater (P <.002), cardiac output was unchanged, and the ability to augment MSNA at high levels of LBNP was reduced (rate of rise for 30- to 60-mmHg LBNP before bed rest 0.073 bursts x min(-1) x mmHg(-1); after bed rest 0.035 bursts x min(-1) x mmHg(-1); P < 0.016). These findings suggest that 24 h of bed rest reduces sympathetic nerve responses to LBNP.

  4. Regulation of muscle sympathetic nerve activity after bed rest deconditioning

    NASA Technical Reports Server (NTRS)

    Pawelczyk, J. A.; Zuckerman, J. H.; Blomqvist, C. G.; Levine, B. D.

    2001-01-01

    Cardiovascular deconditioning reduces orthostatic tolerance. To determine whether changes in autonomic function might produce this effect, we developed stimulus-response curves relating limb vascular resistance, muscle sympathetic nerve activity (MSNA), and pulmonary capillary wedge pressure (PCWP) with seven subjects before and after 18 days of -6 degrees head-down bed rest. Both lower body negative pressure (LBNP; -15 and -30 mmHg) and rapid saline infusion (15 and 30 ml/kg body wt) were used to produce a wide variation in PCWP. Orthostatic tolerance was assessed with graded LBNP to presyncope. Bed rest reduced LBNP tolerance from 23.9 +/- 2.1 to 21.2 +/- 1.5 min, respectively (means +/- SE, P = 0.02). The MSNA-PCWP relationship was unchanged after bed rest, though at any stage of the LBNP protocol PCWP was lower, and MSNA was greater. Thus bed rest deconditioning produced hypovolemia, causing a shift in operating point on the stimulus-response curve. The relationship between limb vascular resistance and MSNA was not significantly altered after bed rest. We conclude that bed rest deconditioning does not alter reflex control of MSNA, but may produce orthostatic intolerance through a combination of hypovolemia and cardiac atrophy.

  5. Vitamin D: Findings from Antarctic, Bed Rest, Houston, and ISS

    NASA Technical Reports Server (NTRS)

    Zwart, Sara R.; Locke, J.; Pierson, D.; Mehta, S.; Bourbeau, Y.; Parsons, H.; Smith, S. M.

    2009-01-01

    Obtaining vitamin D is critical for space travelers because they lack ultraviolet light exposure and have an insufficient dietary supply of vitamin D. Despite the provision of 400 IU vitamin D supplements to International Space Station (ISS) early crewmembers, vitamin D status was consistently lower after flight than before flight, and in several crewmembers has decreased to levels considered clinically significant. Vitamin D has long been known to play a role in calcium metabolism, and more recently its non-calcitropic functions have been recognized. According to the results of several recent studies, functionally relevant measures indicate that the lower limit of serum 25-hydroxyvitamin D (a marker of vitamin D status) should be raised from the current 23 nmol/L to 80 nmol/L. The mean preflight serum 25-hydroxyvitamin D (25-OH vit D) for U.S. ISS crewmembers to date is 63 +/- 16 nmol/L, and after a 4- to 6-mo space flight it typically decreases 25-30% despite supplementation (400 IU/d). The sub-optimal pre- and postflight vitamin D status is an issue that needs to be addressed, to allow NASA to better define the appropriate amount of supplemental vitamin D to serve as a countermeasure against vitamin D deficiency in astronaut crews. A series of ground-based and flight studies in multiple models have been conducted, including Antarctica in winter months when UV-B radiation levels are essentially zero, bed rest where subjects are not exposed to UV-B radiation for 60-90 days, in free-living individuals in Houston, and in International Space Station crewmembers. In these studies, we looked at dose regimen and efficacy, compliance issues, as well as toxicity. Preliminary results from these studies will be presented. Together, the data from these studies will enable us to provide space crews with evidence-based recommendations for vitamin D supplementation. The findings also have implications for other persons with limited UV light exposure, including polar workers and

  6. Feasibility Study of a Lunar Analog Bed Rest Model

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.; Platts, Steven H.; Yarbough, Patrice; Buccello-Stout, Regina

    2010-01-01

    The purpose of this study was to determine the feasibility of using a 9.5deg head-up tilt bed rest model to simulate the effects of the 1/6 g load to the human body that exists on the lunar surface. The lunar analog bed rest model utilized a modified hospital bed. The modifications included mounting the mattress on a sled that rolled on bearings to provide freedom of movement. The weight of the sled was off-loaded using a counterweight system to insure that 1/6 body weight was applied along the long axis (z-axis) of the body. Force was verified through use of a force plate mounted at the foot of the bed. A seating assembly was added to the bed to permit periods of sitting. Subjects alternated between standing and sitting positions throughout the day. A total of 35% of the day was spent in the standing position and 65% was spent sitting. In an effort to achieve physiologic fluid shifts expected for a 1/6 G environment, subjects wore compression stockings and performed unloaded foot and ankle exercises. Eight subjects (3 females and 5 males) participated in this study. Subjects spent 13 days in the pre-bed rest phase, 6 days in bed rest and 3 days post bed rest. Subjects consumed a standardized diet throughout the study. To determine feasibility, measures of subject comfort, force and plasma volume were collected. Subject comfort was assessed using a Likert scale. Subjects were asked to assess level of comfort (0-100) for 11 body regions and provide an overall rating. Results indicated minimal to no discomfort as most subjects reported scores of zero. Force measures were performed for each standing position and were validated against subject s calculated 1/6 body weight (r(sup 2) = 0.993). The carbon monoxide rebreathing technique was used to assess plasma volume during pre-bed rest and on the last day of bed rest. Plasma volume results indicated a significant decrease (p = 0.001) from pre to post bed rest values. Subjects lost on average 8.3% (sd = 6.1%) during the

  7. Artificial gravity training reduces bed rest-induced cardiovascular deconditioning.

    PubMed

    Stenger, Michael B; Evans, Joyce M; Knapp, Charles F; Lee, Stuart M C; Phillips, Tiffany R; Perez, Sondra A; Moore, Alan D; Paloski, William H; Platts, Steven H

    2012-02-01

    We studied 15 men (8 treatment, 7 control) before and after 21 days of 6º head-down tilt to determine whether daily, 1-h exposures to 1.0 G(z) (at the heart) artificial gravity (AG) would prevent bed rest-induced cardiovascular deconditioning. Testing included echocardiographic analysis of cardiac function, plasma volume (PV), aerobic power (VO(2)pk) and cardiovascular and neuroendocrine responses to 80º head-up tilt (HUT). Data collected during HUT were ECG, stroke volume (SV), blood pressure (BP) and blood for catecholamines and vasoactive hormones. Heart rate (HR), cardiac output (CO), total peripheral resistance, and spectral power of BP and HR were calculated. Bed rest decreased PV, supine and HUT SV, and indices of cardiac function in both groups. Although PV was decreased in control and AG after bed rest, AG attenuated the decrease in orthostatic tolerance [pre- to post-bed rest change; control: -11.8 ± 2.0, AG: -6.0 ± 2.8 min (p = 0.012)] and VO(2)pk [pre- to post-bed rest change; control: -0.39 ± 0.11, AG: -0.17 ± 0.06 L/min (p = 0.041)]. AG prevented increases in pre-tilt levels of plasma renin activity [pre- to post-bed rest change; control: 1.53 ± 0.23, AG: -0.07 ± 0.34 ng/mL/h (p = 0.001)] and angiotensin II [pre- to post-bed rest change; control: 3.00 ± 1.04, AG: -0.63 ± 0.81 pg/mL (p = 0.009)] and increased HUT aldosterone [post-bed rest; control: 107 ± 30 pg/mL, AG: 229 ± 68 pg/mL (p = 0.045)] and norepinephrine [post-bed rest; control: 453 ± 107, AG: 732 ± 131 pg/mL (p = 0.003)]. We conclude that AG can mitigate some aspects of bed rest-induced cardiovascular deconditioning, including orthostatic intolerance and aerobic power. Mechanisms of improvement were not cardiac-mediated, but likely through improved sympathetic responsiveness to orthostatic stress. PMID:21626041

  8. Blood volume responses of men and women to bed rest

    NASA Technical Reports Server (NTRS)

    Fortney, S. M.; Turner, C.; Steinmann, L.; Driscoll, T.; Alfrey, C.

    1994-01-01

    This paper reviews a series of studies that indicate that estrogens play an important role in blood volume regulation. The first study illustrates that the plasma volume (PV) of ambulatory women fluctuates during the menstrual cycle, increasing during periods of elevated estrogens. In the second study, it was shown that exogenous and endogenous elevations in blood estrogens attenuate the decrease in PV during bed rest. In the third study, the hypothesis was tested that women, who naturally have a higher blood estrogen content compared with men, will have a smaller loss of PV during bed rest. Ten men and ten women underwent a 13-day, 6 degrees head-down bed rest. Plasma volume and red cell mass (RCM) were measured before and after bed rest using 125I and 51Cr labeling, respectively. Before bed rest, the men and women had similar blood volume (BV) and PV (mL/kg body weight), but the women had a smaller (P < .01) RCM (22.2 +/- 0.9 versus 26.2 +/- 0.8 mL/kg, mean +/- SE). During bed rest, the decrease in RCM (mL/kg) was similar in men and women. However, the decrease in BV was greater in men (8.0 +/- 0.8 mL/kg versus 5.8 +/- 0.8 mL/kg), because of a greater reduction in PV (6.3 +/- 0.6 mL/kg versus 4.1 +/- 0.6 mL/kg). Because the decline in BV has been proposed to contribute to the cardiovascular deconditioning after bed rest, it is possible that women may experience less cardiac and circulatory strain on reambulation.

  9. Cardiovascular Adaptations to Long Duration Head Down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Platts, Steven H.; Meck, Janice V.; Martin, David S.; Freeman-Perez, Sondra A.; Riberio, Christine; Garcia, Kathleen M.; Waters, Wendy W.

    2007-01-01

    Orthostatic hypotension is a recognized risk for crewmembers returning from space. Numerous cardiovascular mechanisms have been proposed to account for this problem including vascular and cardiac dysfunction. We studied arterial and cardiac function in 6-degree head-down tilt bed rest, which is the most widely accepted ground-based analog of spaceflight. Eleven subjects are included in this study (8 men and 3 women). Data analysis was limited to the first 49 days, and compared to pre-bed rest baseline data. Using ultrasound, data was collected on arterial diameters and flows at baseline and during reactive hyperemia and following administration of nitroglycerin. Echocardiography was used to acquire information regarding systolic and diastolic function as well as ventricular mass and diameter. Plasma volumes were significantly decreased by 7 days of bed rest and stayed down through 49 days. There were no differences in reactive hyperemic response in the arm at any time point. However, the hyperemic response in the leg was significantly increased at day 49. Arterial responses to nitroglycerin did not change over the duration of bed rest (day effect) in either the arm or leg, but there was a significant difference between the arm and the leg responses. There was a marked decrease in anterior tibial intimal-medial thickness at days 21, 35 and 49. Several cardiac functional parameters including IVRT, Mitral e-wave, ejection time, velocity of circumferential shortening and myocardial performance index were significantly changed following 49 days of bed rest. These data show that some cardiovascular measures change during bed rest, while others do not. Further study is needed to determine if these measures can provide any insight into the effects of bed rest, or spaceflight, on human cardiovascular performance.

  10. Decremental reset in basal metabolism during 20-days bed rest.

    PubMed

    Haruna, Y; Suzuki, Y; Kawakubo, K; Yanagibori, R; Gunji, A

    1994-01-01

    Changes in basal metabolism during 20 days bed rest were measured in 9 young healthy males and 5 females. Food intake was unrestricted and supplementary meals were allowed. All food intake was monitored. A special sleeping pattern was not enforced, although an ordinary day-night diurnal rhythm was kept in the rooms. Body temperatures were measured daily every 2 hours from 7:00 to 22:00. Basal oxygen uptake decreased significantly during the first 10 days of bed rest and levelled off during the following 10 days. Body weight and composition remained substantially unchanged in spite of a decreased energy consumption during the bed rest. In conclusion, basal VO2 was reset at a decreased level during the first 10 days of bedrest with no relationship to the dietary energy intake or to the body temperature, while no more change took place during the following 10 days.

  11. Thyroid and adrenal cortical rhythmicity during bed rest.

    NASA Technical Reports Server (NTRS)

    Vernikos-Danellis, J.; Leach, C. S.; Winget, C. M.; Rambaut, P. C.; Mack, P. B.

    1972-01-01

    The effects of prolonged bed rest on adrenocortical and thyroid function were assessed in eight healthy males, aged 20-40 years, who were submitted to bed rest for 56 days on a 14L:10D regimen (lights-on, 9:00 AM). Four of these subjects exercised three times daily throughout the experiment. Circulating cortisol, triiodothyronine, and thyroxine, concentrations were determined in blood samples drawn at four hourly intervals for 48-hr periods before, 10, 20, 30, 42, and 54 days during, and 10 days post-bed rest. Significant fluctuations in the circulating levels of all three hormones occurred with peaks at 7:30 AM. The suggestion is advanced that thyroid rhythms may be posture dependent.

  12. Exercise thermoregulation with bed rest, confinement, and immersion deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.

    1997-01-01

    Altered thermoregulation following exposure to prolonged (12-14 days) of bed rest and 6 hr of head-down thermoneutral water immersion in humans, and cage confinement (8 weeks) in male, mongrel dogs resulted in occasional increased core temperature (Tcore) at rest, but consistent "excessive" increase in Tcore during submaximal exercise. This excessive increase in Tcore in nonexercising and exercising subjects was independent of the mode (isometric or isotonic) of exercise training during bed rest, and was associated with the consistent hypovolemia in men but not in women taking estrogen supplementation (1.25 mg premarin/ day) which restored plasma volume during bed rest to ambulatory control levels. Post-bed rest exercise sweating (evaporative heat loss) was unchanged or higher than control levels; however, calculated tissue heat conductance was significantly lower in men, and forearm venoconstriction was greater (venous volume was reduced) in women during exercise after bed rest. Because sweating appeared proportional to the increased level of Tcore, these findings suggest that one major factor for the excessive hyperthermia is decreased core to periphery heat conduction. Exercising dogs respond like humans with excessive increase in both rectal (Tre) and exercising muscle temperatures (Tmu) after confinement and, after eight weeks of exercise training on a treadmill following confinement, they had an attenuated rate of increase of Tre even below ambulatory control levels. Intravenous infusion of glucose also attenuated not only the rise in Tre during exercise in normal dogs, but also the excessive rise in Tre and exercising Tmu after confinement. Oral glucose also appeared to reduce the rate of increase in excessive Tre in men after immersion deconditioning. There was a greater rate of rise in Tcore in two cosmonauts during supine submaximal exercise (65% VO2 max) on the fifth recovery day after the 115-day Mir 18 mission. Thus, the excessive rise in core

  13. Dietary Support of Extended-Duration Bed Rest Studies

    NASA Technical Reports Server (NTRS)

    Inniss, A. M.; Rice, B. L.; Smith, S. M.

    2006-01-01

    Dietary control and nutrient intake are critical aspects of any metabolic study, but this is especially true in the case of bed rest studies. We sought to define nutrient requirements, develop menus, and implement them in a series of three long-duration bed rest studies. With regard to energy intake, the goal was to maintain subject body weight to within 3% of their body weight on day 3 of bed rest (after fluid shift had occurred). For other nutrients, intakes were based on the NASA space flight nutritional requirements (with some adaptations based on the ground-based model used here). A secondary goal was to develop menus with foods similar to those expected to be approved for space flight (however, this was relaxed to attain desired nutrient intakes). This paper also describes the role of the research dietitian as part of the multi-disciplinary team and the importance of the metabolic kitchen staff. It also provides insight into some of the dietary challenges that arise during extended-duration bed rest studies. Regardless of the overall objective of the study, nutrition must be carefully planned, implemented, and monitored for results to be uncompromised.

  14. Fuel utilization during exercise after 7 days of bed rest

    NASA Technical Reports Server (NTRS)

    Barrows, Linda H.; Harris, Bernard A.; Moore, Alan D.; Siconolfi, Steven F.

    1992-01-01

    Energy yield from carbohydrate, fat, and protein during physical activity is partially dependent on an individual's fitness level. Prolonged exposure to microgravity causes musculoskeletal and cardiovascular deconditioning; these adaptations may alter fuel utilization during space flight. Carbohydrate and fat metabolism during exercise were analyzed before and after 7 days of horizontal bed rest.

  15. Intensive exercise training during bed rest attenuates deconditioning.

    PubMed

    Greenleaf, J E

    1997-02-01

    A 30-d 6 degrees head-down bed rest project was conducted to evaluate variable high-intensity, short-duration, isotonic cycle ergometer exercise (ITE) training and high-intensity intermittent resistive isokinetic exercise (IKE) training regimens designed to maintain peak VO2 and muscle mass, strength, and endurance at ambulatory control levels throughout prolonged bed rest. Other elements of the deconditioning (adaptive) syndrome, such as proprioception, psychological performance, hypovolemia, water balance, body composition, and orthostatic tolerance, were also measured. Major findings are summarized in this paper. Compared with response during bed rest of the no exercise (NOE) control group: the ITE training regimen (a) maintained work capacity (peak VO2), (b) maintained plasma and red cell volumes (c) induced positive body water balance, (d) decreased quality of sleep and mental concentration, and (e) had no effect on the decrease in orthostatic tolerance; the IKE training regimen (f) attenuated the decrease in peak VO2 by 50%, (g) attenuated loss of red cell volume by 40% but had no effect on loss of plasma volume, (h) induced positive body water balance, (i) had no adverse effect on quality of sleep or concentration, and (j) had no effect on the decrease in orthostatic tolerance. These findings suggest that various elements of the deconditioning syndrome can be manipulated by duration and intensity of ITE or IKE training regimens and that several different training protocols will be required to maintain or restore physiological and psychological performance of individuals confined to prolonged bed rest.

  16. Gradient Compression Stockings may Prevent Recovery after Bed Rest Deconditioning

    NASA Technical Reports Server (NTRS)

    Stenger, Michael B.; Lee, Stuart M.; Westby, Christian M.; Willig, Michael C.; Platts, Steven H.

    2011-01-01

    Introduction: Astronauts continue to wear a compression garment during and immediately after landing to prevent orthostatic intolerance (OI). We recently developed a custom-fitted, 3-piece garment that consists of thigh-high stockings with biker-style shorts that provides continuous, gradient compression: 55 mmHg at the ankle that decreases to approximately 20 mmHg at the top of the leg and 15 mmHg over the abdomen. This garment has been shown to be effective in preventing symptoms of OI during a short stand test after Space Shuttle missions, but symptoms may persist for several days after a long-duration mission in some astronauts. The purpose of this study was to confirm the effectiveness of wearing these elastic, gradient compression garments during orthostatic testing after 2 weeks of 6 degree head-down tilt bed rest as a model of spaceflight and to determine whether they would impact recovery after bed rest. Methods: Eight (5 treatment, 3 control) of 16 subjects have completed this study to-date. All subjects wore the 3-piece garment from waking until tilt testing (3 h) as a simulation of the timeline for astronauts on landing day (BR+0). Control subjects removed the garment after the tilt test. Treatment subjects wore the garment for the remainder of the day and wore lower compression thigh-high only garments on the day after bed rest (BR+1). Blood pressure, heart rate, and stroke volume responses to a 15-min 80 degree head-up tilt test were determined before 2 weeks of 6 degree head-down tilt, and on BR+0 and BR+1. Plasma volume (PV) was measured before each of these test sessions. Data are mean SE. Results: Compression garments prevented signs of OI on BR+0; all subjects in both groups completed the full 15-min test. Heart rate responses to tilt were lower on BR+0 than all other test days. Control subjects demonstrated a marginal PV decrease after bed rest, but showed typical recovery the day after bed rest (BR+0: 2.32 plus or minus 0.15 L to BR+1: 2

  17. Intensive Exercise Training During Bed Rest Attenuates Deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.

    1997-01-01

    Intensive exercise training during bed rest attenuates deconditioning. Med. Sci. Sports Exerc., Vol. 29, No. 2, pp. 207-215, 1997. A 30-d 6 deg head-down bed rest project was conducted to evaluate variable high-intensity, short-duration, isotonic cycle ergometer exercise (ITE) training and high-intensity intermittent resistive isokinetic exercise (IKE) training regimens designed to maintain peak VO2 and muscle mass, strength, and endurance at ambulatory control levels throughout prolonged bed rest. Other elements of the deconditioning (adaptive) syndrome, such as proprioception, psychological performance, hypovolemia, water balance, body composition, and orthostatic tolerance, were also measured. Major findings are summarized in this paper. Compared with response during bed rest of the no exercise (NOE) control group: the ITE training regimen (a) maintained work capacity (peak VO2), (b) maintained plasma and red cell volumes, (c) induced positive body water balance, (d) decreased quality of sleep and mental concentration, and (e) had no effect on the decrease in orthostatic tolerance; the IKE training regimen (f) attenuated the decrease in peak VO2 by 50%, (g) attenuated loss of red cell volume by 40% but had no effect on loss of plasma volume, (b) induced positive body water balance, (i) had no adverse effect on quality of sleep or concentration, and 0) had no effect on the decrease in orthostatic tolerance. These findings suggest that various elements of the deconditioning syndrome can be manipulated by duration and intensity of ITE or IKE training regimens and that several different training protocols will be required to maintain or restore physiological and psychological performance of individuals confined to prolonged bed rest.

  18. Leadership Transitions and the First 90 Days.

    PubMed

    Shirey, Maria R

    2016-04-01

    This department highlights change management strategies that may be successful in strategically planning and executing organizational change initiatives. In this article, the author discusses leadership role transitions and provides a framework for successfully navigating the crucial 1st 90 days in an executive leadership role. PMID:27011151

  19. Limited effect of fly-wheel and spinal mobilization exercise countermeasures on lumbar spine deconditioning during 90 d bed-rest in the Toulouse LTBR study

    NASA Astrophysics Data System (ADS)

    Belavý, Daniel L.; Ohshima, Hiroshi; Bareille, Marie-Pierre; Rittweger, Jörn; Felsenberg, Dieter

    2011-09-01

    We examined the effect of high-load fly-wheel (targeting the lower-limb musculature and concurrent loading of the spine via shoulder restraints) and spinal movement countermeasures against lumbar spine muscle atrophy, disc and spinal morphology changes and trunk isokinetic torque loss during prolonged bed-rest. Twenty-four male subjects underwent 90 d head-down tilt bed-rest and performed either fly-wheel (FW) exercises every three days, spinal movement exercises in lying five times daily (SpMob), or no exercise (Ctrl). There was no significant impact of countermeasures on losses of isokinetic trunk flexion/extension ( p≥0.65). Muscle volume change by day-89 of bed-rest in the psoas, iliacus, lumbar erector spinae, lumbar multifidus and quadratus lumborum, as measured via magnetic resonance imaging (MRI), was statistically similar in all three groups ( p≥0.33). No significant effect on MRI-measures of lumbar intervertebral disc volume, spinal length and lordosis ( p≥0.09) were seen either, but there was some impact ( p≤0.048) on axial plane disc dimensions (greater reduction than in Ctrl) and disc height (greater increases than in Ctrl). MRI-data from subjects measured 13 and 90-days after bed-rest showed partial recovery of the spinal extensor musculature by day-13 after bed-rest with this process complete by day-90. Some changes in lumbar spine and disc morphology parameters were still persistent 90-days after bed-rest. The present results indicate that the countermeasures tested were not optimal to maintain integrity of the spine and trunk musculature during bed rest.

  20. The Effects of Long Duration Bed Rest on Functional Mobility and Balance: Relationship to Resting State Motor Cortex Connectivity

    NASA Technical Reports Server (NTRS)

    Erdeniz, B.; Koppelmans, V.; Bloomberg, J. J.; Kofman, I. S.; DeDios, Y. E.; Riascos-Castaneda, R. F.; Wood, S. J.; Mulavara, A. P.; Seidler, R. D.

    2014-01-01

    NASA offers researchers from a variety of backgrounds the opportunity to study bed rest as an experimental analog for space flight. Extended exposure to a head-down tilt position during long duration bed rest can resemble many of the effects of a low-gravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The aim of our study is to a) identify changes in brain function that occur with prolonged bed rest and characterize their recovery time course; b) assess whether and how these changes impact behavioral and neurocognitive performance. Thus far, we completed data collection from six participants that include task based and resting state fMRI. The data have been acquired through the bed rest facility located at the University of Texas Medical Branch (Galveston, TX). Subjects remained in bed with their heads tilted down 6 degrees below their feet for 70 consecutive days. Behavioral measures and neuroimaging assessments were obtained at seven time points: a) 7 and 12 days before bed rest; b) 7, 30, and 65 days during bed rest; and c) 7 and 12 days after bed rest. Functional connectivity magnetic resonance imaging (FcMRI) analysis was performed to assess the connectivity of motor cortex in and out of bed rest. We found a decrease in motor cortex connectivity with vestibular cortex and the cerebellum from pre bed rest to in bed rest. We also used a battery of behavioral measures including the functional mobility test and computerized dynamic posturography collected before and after bed rest. We will report the preliminary results of analyses relating brain and behavior changes. Furthermore, we will also report the preliminary results of a spatial working memory task and vestibular stimulation during in and out of bed rest.

  1. Serum Sclerostin Increases in Healthy Adult Men during Bed Rest

    PubMed Central

    Fields, E. E.; Yu, E. W.; Pajevic, P. Divieti; Bouxsein, M. L.; Sibonga, J. D.; Zwart, S. R.; Smith, S. M.

    2012-01-01

    Context: Animal models and human studies suggest that osteocytes regulate the skeleton's response to mechanical unloading in part by an increase in sclerostin. However, few studies have reported changes in serum sclerostin in humans exposed to reduced mechanical loading. Objective: We determined changes in serum sclerostin and bone turnover markers in healthy adult men undergoing controlled bed rest. Design, Setting, and Participants: Seven healthy adult men (31 ± 3 yr old) underwent 90 d of 6° head down tilt bed rest at the University of Texas Medical Branch Institute for Translational Sciences-Clinical Research Center. Outcomes: Serum sclerostin, PTH, vitamin D, bone resorption and formation markers, urinary calcium and phosphorus excretion, and 24-h pooled urinary markers of bone resorption were evaluated before bed rest [baseline (BL)] and at bed rest d 28 (BR-28), d 60 (BR-60), and d 90 (BR-90). Bone mineral density was measured at BL, BR-60, and 5 d after the end of the study (BR+5). Data are reported as mean ± sd. Results: Consistent with prior reports, bone mineral density declined significantly (1–2% per month) at weight-bearing skeletal sites. Serum sclerostin was elevated above BL at BR-28 (+29 ± 20%; P = 0.003) and BR-60 (+42 ± 31%; P < 0.001), with a lesser increase at BR-90 (+22 ± 21%; P = 0.07). Serum PTH levels were reduced at BR-28 (−17 ± 16%; P = 0.02) and BR-60 (−24 ± 14%; P = 0.03) and remained lower than BL at BR-90 (−21 ± 21%; P = 0.14), but did not reach statistical significance. Serum bone turnover markers were unchanged; however, urinary bone resorption markers and calcium were significantly elevated at all time points after bed rest (P < 0.01). Conclusions: In healthy men subjected to controlled bed rest for 90 d, serum sclerostin increased, with a peak at 60, whereas serum PTH declined, and urinary calcium and bone resorption markers increased. PMID:22767636

  2. Sympathetic discharge and vascular resistance after bed rest

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. K.; Hogeman, C. S.; Leuenberger, U. A.; Herr, M. D.; Gray, K.; Silber, D. H.; Sinoway, L. I.

    1998-01-01

    The effect of -6 degrees head-down-tilt bed rest (HDBR) for 14 days on supine sympathetic discharge and cardiovascular hemodynamics at rest was assessed. Mean arterial pressure, heart rate (n = 25), muscle sympathetic nerve activity (MSNA; n = 16) burst frequency, and forearm blood flow (n = 14) were measured, and forearm vascular resistance (FVR) was calculated. Stroke distance, our index of stroke volume, was derived from measurements of aortic mean blood velocity (Doppler) and R-R interval (n = 7). With these data, an index of total peripheral resistance was determined. Heart rate at rest was greater in the post (71 +/- 2 beats/min)- compared with the pre-HDBR test (66 +/- 2 beats/min; P < 0.003), but mean arterial pressure was unchanged. Aortic stroke distance during post-HDBR (15.5 +/- 1.1 cm/beat) was reduced from pre-HDBR levels (20.0 +/- 1.5 cm/beat) (P < 0.03). Also, MSNA burst frequency was reduced in the post (16.7 +/- 2.8 beats/min)- compared with the pre (25.2 +/- 2.6 beats/min)-HDBR condition (P < 0.01). Bed rest did not alter forearm blood flow, FVR, or total peripheral resistance. Thus reductions in MSNA with HDBR were not associated with a decrease in FVR.

  3. Calcium kinetics during bed rest with artificial gravity and exercise countermeasures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest. Subjects ingested less calcium during bed rest, and with artificial gravity, they also absorbed less calcium. With exercise, they excreted less calcium. To retain bone during bed rest, calcium intake ne...

  4. Assessment of Immune Status, Latent Viral Reactivation and Stress during Long Duration Bed Rest as an Analog for Spaceflight

    NASA Technical Reports Server (NTRS)

    Crucian, Brian E.; Stowe, Raymond P.; Mehta, Satish K.; Yetman, Deborah L.; Leaf, Melanie J.; Pierson, Duane L.; Sams, Clarence F.

    2007-01-01

    As logistical access for in-flight space research becomes more limited, the use of ground based spaceflight analogs for life science studies will increase. These studies are particularly important as NASA progresses towards the Lunar and eventually Mars missions outlined in the 2005 Vision for Space Exploration. Countermeasures must be developed to mitigate the clinical risks associated with exploration class space missions. In an effort to coordinate studies across multiple disciplines, NASA has selected 90-day bed rest as the analog of choice, and initiated the Flight Analogs Project to implement research studies with or without the evaluation of countermeasures. Although bed rest is not the analog of choice to evaluate spaceflight-associated immune dysfunction, a standard Immune Assessment was developed for subjects participating in the 90-day bed best studies. The Immune Assessment consists of: leukocyte subset distribution, T cell functional responses, intracellular cytokine production profiles, latent viral reactivation, virus specific T cell levels, virus specific T cell function, stress hormone levels and a behavioral assessment using stress questionnaires. The purpose of the assessment during the initial studies (without countermeasure) is to establish control data against which future studies (with countermeasure) will be evaluated. It is believed that some of the countermeasures planned to be evaluated in future studies, such as exercise, pharmacologic intervention or nutritional supplementation, have the ability to impact immune function. Therefore immunity will likely be monitored during those studies. The data generated during the first three control studies showed that the subjects in general did not display altered peripheral leukocyte subsets, constitutive immune activation, significant latent viral reactivation (EBV, VZV) or altered T cell function. Interestingly, for some subjects the level of constitutively activated T cells (CD8+/CD69+) and

  5. Early mobilization versus bed rest for deep vein thrombosis.

    PubMed

    Izcovich, Ariel; Popoff, Federico; Rada, Gabriel

    2016-06-28

    Aiming to prevent thromboembolic events, bed rest was historically considered in the management of patient with deep vein thrombosis. Nevertheless early ambulation could have beneficial effects. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified seven systematic reviews including 10 randomized trials answering this question. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded early ambulation is probably effective in reducing deep vein thrombosis progression and improving limb pain, and might not increase the risk of thromboembolism.

  6. Cardiovascular Adaptations to Long Duration Head-Down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Platts, Steven H.; Martin, David S.; Perez, Sondar A.; Ribeiro, Christine; Stenger, Michael B.; Summers, Richard; Meck, Janice V.

    2008-01-01

    INTRODUCTION: Orthostatic hypotension is a serious risk for crewmembers returning from spaceflight. Numerous cardiovascular mechanisms have been proposed to account for this problem, including vascular and cardiac dysfunction, which we studied during bed rest. METHODS: Thirteen subjects were studied before and during bed rest. Statistical analysis was limited to the first 49-60 days of bed rest, and compared to pre-bed rest data. Ultrasound data were collected on vascular and cardiac structure and function. Tilt testing was conducted for 30 minutes or until presyncopal symptoms intervened. RESULTS: Plasma volume was significantly reduced by day 7 of bed rest. Flow-mediated dilation in the leg was significantly increased at bed rest day 49. Arterial responses to nitroglycerin differed in the arm and leg, but did not change as a result of bed rest. Intimal-medial thickness markedly decreased at bed rest days 21, 35 and 49. Several cardiac functional parameters including isovolumic relaxation time, ejection time and myocardial performance index were significantly increased (indicating a decrease in cardiac function) during bed rest. There was a trend for decreased orthostatic tolerance following 60 days of bed rest. DISCUSSION: These data suggest that 6 head-down tilt bed rest alters cardiovascular structure and function in a pattern similar to short duration spaceflight. Additionally, the vascular alterations are primarily seen in the lower body, while vessels of the upper body are unaffected. KEY WORDS: spaceflight, orthostatic intolerance, hypotension, fluid-shift, plasma volume

  7. Implementation of the NASA AG-Bed Rest Pilot

    NASA Technical Reports Server (NTRS)

    Warren, L. E.; Paloski, W. H.; Young, L. R.

    2007-01-01

    To examine the efficacy of artificial gravity (AG) as a countermeasure to spaceflight deconditioning, intermittent AG produced by a horizontal short-radius centrifuge (SRC) was utilized on human test subjects deconditioned by bed rest. This poster will present the subject screening, study design, logistics, and implementation of the 41 day pilot study conducted at the University of Texas Medical Branch, Galveston, TX bed rest facility. An extensive screening process was employed to exclude subjects that were dissimilar to the U.S. astronaut population. Candidates underwent a modified U.S. Air Force Class III physical and tests of bone density, cardiovascular fitness, vestibular system function, psychological fitness and centrifuge tolerance. 15 subjects completed the study; 7 control and 8 AG treatment. All provided written consent to volunteer after the nature of the study and its hazards were clearly explained to them. Standard conditions were strictly regulated; Ta = 72 +/- 2 F, humidity = 70 +/- 5%, light/dark cycle 16h:8h. All fluid intake (minimum 28.5 ml/kg body weight/day) and urine output was monitored. Caloric intake was adjusted as necessary to maintain body weight. Carbohydrate, fat and protein were provided in a ratio of 55:30:15. Phosphorus intake was 1400 mg/d, sodium intake was 2 mmol/kg/d, potassium intake was 1.3 mmol/kg/d, and dietary calcium intake was 1000 mg/d. A physician examined each subject daily. During the first 11 days of the study protocol, subjects were ambulatory, but confined to the facility. Subjects participated in multiple baseline tests of bone, muscle, cardiovascular, sensory-motor, immunological, and psychological function. On the 12th day, subjects entered the bed rest phase of the study, during which they were confined to strict 6? head down tilt bed rest for 21 days. Beginning 24 hrs into this period, treatment subjects received 1 hour daily exposures to artificial gravity which was produced by spinning the subjects on a 3

  8. Catecholaminergic effects of prolonged head-down bed rest

    NASA Technical Reports Server (NTRS)

    Goldstein, D. S.; Vernikos, J.; Holmes, C.; Convertino, V. A.

    1995-01-01

    Prolonged head-down bed rest (HDBR) provides a model for examining responses to chronic weightlessness in humans. Eight healthy volunteers underwent HDBR for 2 wk. Antecubital venous blood was sampled for plasma levels of catechols [norepinephrine (NE), epinephrine, dopamine, dihydroxyphenylalanine, dihydroxyphenylglycol, and dihydroxyphenylacetic acid] after supine rest on a control (C) day and after 4 h and 7 and 14 days of HDBR. Urine was collected after 2 h of supine rest during day C, 2 h before HDBR, and during the intervals 1-4, 4-24, 144-168 (day 7), and 312-336 h (day 14) of HDBR. All subjects had decreased plasma and blood volumes (mean 16%), atriopeptin levels (31%), and peripheral venous pressure (26%) after HDBR. NE excretion on day 14 of HDBR was decreased by 35% from that on day C, without further trends as HDBR continued, whereas plasma levels were only variably and nonsignificantly decreased. Excretion rates of dihydroxyphenylglycol and dihydroxyphenylalanine decreased slightly during HDBR; excretion rates of epinephrine, dopamine, and dihydroxyphenylacetic acid and plasma levels of catechols were unchanged. The results suggest that HDBR produces sustained inhibition of sympathoneural release, turnover, and synthesis of NE without affecting adrenomedullary secretion or renal dopamine production. Concurrent hypovolemia probably interferes with detection of sympathoinhibition by plasma levels of NE and other catechols in this setting. Sympathoinhibition, despite decreased blood volume, may help to explain orthostatic intolerance in astronauts returning from spaceflights.

  9. Simulated microgravity [bed rest] has little influence on taste, odor or trigeminal sensitivity

    NASA Technical Reports Server (NTRS)

    Vickers, Z. M.; Rice, B. L.; Rose, M. S.; Lane, H. W.

    2001-01-01

    Anecdotal evidence suggests that astronauts' perceptions of foods in space flight may differ from their perceptions of the same foods on Earth. Fluid shifts toward the head experienced in space may alter the astronauts' sensitivity to odors and tastes, producing altered perceptions. Our objective was to determine whether head-down bed rest, which produces similar fluid shifts, would produce changes in sensitivity to taste, odor or trigeminal sensations. Six subjects were rested three times prior to bed rest, three times during bed rest and two times after bed rest to determine their threshold sensitivity to the odors isoamylbutyrate and menthone, the tastants sucrose, sodium chloride, citric acid, quinine and monosodium glutamate, and to capsaicin. Thresholds were measured using a modified staircase procedure. Self-reported congestion was also recorded at each test time. Thresholds for monosodium glutamate where slightly higher during bed rest. None of the other thresholds were altered by bed rest.

  10. Atropine unmasks bed-rest effect - A spectral analysis of cardiac interbeat intervals

    NASA Technical Reports Server (NTRS)

    Goldberger, Ary L.; Goldwater, Danielle; Bhargava, Valmik

    1986-01-01

    Heart rate spectral data obtained for 10 male subjects between 35-49 years following orthostatic tolerance testing with lower body negative pressure prebed rest and after 7-10 days of bed rest, while on placebo and after intravenous atropine are analyzed. Comparison of the spectral atropine rms for subjects prebed rest and after bed rest reveal a decrease from 63 + or - 24 ms to 40 + or - 23 ms. It is observed that heart rate interval variability for subjects after bed rest and with atropine is reduced; the heart rate at bed rest with atropine is increased from 70.4 + or - 12.4 beats/min prebed rest to 83.7 + or - 18.9 beats/min; and the exercise tolerance time for subjects in the atropine prebed-rest phase (658 + or - 352 s) is higher than the bed-rest phase (505 + or - 252 s). It is noted that bed rest impairs the cardiovascular capacity to adaptively modulate physiological responses, atropine exposes bed-rest deconditioning effects, and spectral analysis is useful for studying the effects of bed-rest deconditioning on cardiac dynamics.

  11. Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans.

    PubMed

    Kamiya, Atsunori; Michikami, Daisaku; Shiozawa, Tomoki; Iwase, Satoshi; Hayano, Junichiro; Kawada, Toru; Sunagawa, Kenji; Mano, Tadaaki

    2004-05-01

    Although spaceflight and bed rest are known to cause muscular atrophy in the antigravity muscles of the legs, the changes in sympathetic and cardiovascular responses to exercises using the atrophied muscles remain unknown. We hypothesized that bed rest would augment sympathetic responses to isometric exercise using antigravity leg muscles in humans. Ten healthy male volunteers were subjected to 14-day 6 degrees head-down bed rest. Before and after bed rest, they performed isometric exercises using leg (plantar flexion) and forearm (handgrip) muscles, followed by 2-min postexercise muscle ischemia (PEMI) that continues to stimulate the muscle metaboreflex. These exercises were sustained to fatigue. We measured muscle sympathetic nerve activity (MSNA) in the contralateral resting leg by microneurography. In both pre- and post-bed-rest exercise tests, exercise intensities were set at 30 and 70% of the maximum voluntary force measured before bed rest. Bed rest attenuated the increase in MSNA in response to fatiguing plantar flexion by approximately 70% at both exercise intensities (both P < 0.05 vs. before bed rest) and reduced the maximal voluntary force of plantar flexion by 15%. In contrast, bed rest did not alter the increase in MSNA response to fatiguing handgrip and had no effects on the maximal voluntary force of handgrip. Although PEMI sustained MSNA activation before bed rest in all trials, bed rest entirely eliminated the PEMI-induced increase in MSNA in leg exercises but partially attenuated it in forearm exercises. These results do not support our hypothesis but indicate that bed rest causes a reduction in isometric exercise-induced sympathetic activation in (probably atrophied) antigravity leg muscles.

  12. Energy and thermal regulation during bed rest and spaceflight

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.

    1989-01-01

    This paper presents data available from bed-rest and flight studies on the energy metabolism and thermoregulatory parameters and their changes during long-duration space missions which may influence requirements of astronauts for food and water. It is calculated, on the basis of 3100 kcal and 2.2 l water a day, with 1 h/day moderate exercise, that the requirements for a 2-yr flight would be 2,263,000 kcal and 1606 l water for each astronaut. One daily 5-h-long extravehicular sortie would require an additional 529,250 kcal and 1,095 l of water per year. Changes in the efficiency of work or metabolism would affect these nutritional requirements for long spaceflights. Factors that would increase food and water requirements are discussed.

  13. Immune response to 60-day head-down bed rest

    NASA Astrophysics Data System (ADS)

    Song, Jinping; Guo, Aihua; Zhong, Ping; Zhang, Hongyu; Wu, Feng; Wan, Yumin; Bai, Yanqiang; Chen, Shanguang; Li, Yinghui

    Introduction: Exposure of humans to spaceflight has resulted in disregulation of the immune system. Head-down bed rest (HDBR) has been extensively used as an earth-bound analog to study physiologic effects mimicking those occurring in weightlessness during spaceflight. It is uncertain how a prolonged period of bed rest affect human immune responses. The objective of this study was to investigate the effects of 60-day HDBR on immune function and EB virus reactivation in seven male volunteers. Methods: There were seven healthy male volunteers who were subjected to HDBR for 60d. Immunological parameters including leukocyte subset distribution, lymphocyte proliferation to mitogens, secreted cytokine profiles and EB virus reactivation were monitored. Results: Total WBC conunts increased significantly 10d post-HDBR as compared with pre-HDBR. At the same time, the relative percentage of neutrophils was also higher than pre-HDBR but not significant. MFI of CD11b in neutrophils was reduced obviously at thd end of HDBR. T Lymphocyte proliferations to PHA reduced at HDBR 30, HDBR 60 and 10d post-HDBR while IL-2 production decreased significantly at the same time. IFN-and IL-4 production trended to decrease at HDBR 30 and HDBR 60. The relative percentage of T lymphocyte subset, B lymphocyte and NK cells were not altered. EBV EA (early antigen) were negative and EBV VCA titers had no changes through HDBR. Conclusion: The results indicate that several immunological parameters (mainly cellular immunity) are altered significantly by prolonged HDBR, and these changes were similar to those happened in spaceflight.

  14. Sympathetic responses to Valsalva's manoeuvre following bed rest

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. Kevin; Hogeman, Cynthia S.; Sinoway, Lawrence I.

    2003-01-01

    The purpose of this study was to examine whether 14 days of head-down tilt bed rest (HDBR) alters autonomic regulation during Valsalva's manoeuvre (VM) and if this would predict blood pressure control during a 60 degrees head-up tilt (HUT) test. To examine autonomic control of blood pressure, we measured the changes in systolic (delta SBP) and diastolic (delta DBP) blood pressure between baseline and the early straining (Phase IIE) period of VM (20 sec straining to 40 mmHg; N = 7) in conjunction with changes in muscle sympathetic nerve activity (MSNA; microneurography) burst frequency (B/min) and total activity (% delta) from baseline over the 20-sec straining period. MSNA data were successfully recorded from 6 of the 7 individuals. The averaged responses from three repeated VMs performed in the supine position were compared between the pre- and post-HDBR tests. Compared with the pre-HDBR test, a greater reduction in SBP, DBP, and MAP was observed during Phase IIE following HDBR, p < 0.05. The increase in MSNA burst frequency during straining was augmented in the post- compared with the pre-HDBR test, p < 0.0001, as was the Phase IV blood pressure overshoot, p < 0.05. Although all subjects completed the 20-min pre-HDBR tilt test without evidence of hypotension or orthostatic intolerance, the post-HDBR test was stopped early in 5 of the 7 subjects due to systolic hypotension. The responses during the VM suggest that acute autonomic adjustments to rapid blood pressure changes are preserved after bed rest. Furthermore, MSNA and blood pressure responses during VM did not predict blood pressure control during orthostasis following HDBR.

  15. Orthostatic hypotension in patients, bed rest subjects, and astronauts

    NASA Technical Reports Server (NTRS)

    Lathers, C. M.; Charles, J. B.

    1994-01-01

    Orthostatic hypotension after even short space flights has affected a significant number of astronauts. Given the need for astronauts to function at a high level of efficiency during and after their return from space, the application of pharmacologic and other treatments is strongly indicated. This report addresses the clinical problem of orthostatic hypotension and its treatments to ascertain whether pharmacologic or physiologic treatment may be useful in the prevention of orthostatic hypotension associated with space flight. Treatment of orthostatic hypotension in patients now includes increasing intravascular volume with high sodium intake and mineralocorticoids, or increasing vascular resistance through the use of drugs to stimulate alpha or block beta vascular receptors. Earlier treatment used oral sympathomimetic ephedrine hydrochloride alone or with "head-up" bed rest. Then long-acting adrenocortical steroid desoxycorticosterone preparations with high-salt diets were used to expand volume. Fludrocortisone was shown to prevent the orthostatic drop in blood pressure. The combination of the sympathomimetic amine hydroxyamphetamine and a monoamine oxidase inhibitor tranylcypromine has been used, as has indomethacin alone. Davies et al. used mineralocorticoids at low doses concomitantly with alpha-agonists to increase vasoconstrictor action. Schirger et al used tranylcypromine and methylphenidate with or without a Jobst elastic leotard garment or the alpha-adrenergic agonist midodrine (which stimulates both arterial and venous systems without direct central nervous system or cardiac effects). Vernikos et al established that the combination of fludrocortisone, dextroamphetamine, and atropine exhibited a beneficial effect on orthostatic hypotension induced by 7-day 6 degrees head-down bed rest (a model used to simulate the weightlessness of space flight). Thus, there are numerous drugs that, in combination with mechanical techniques, including lower body negative

  16. Effect of 14 days of bed rest on urine metabolite excretion and plasma enzyme levels

    NASA Technical Reports Server (NTRS)

    Pace, N.; Grunbaum, B. W.; Kodama, A. M.; Rahlmann, D. F.; Newsom, B. D.

    1974-01-01

    After 1 week of ambulatory base-line measurement, a group of 8 men 19-26 years of age remained continuously recumbent for 14 days. Studies were continued for 1 week following the prolonged recumbency. Urine excretion rates for a number of constituents were determined 2 days before bed rest, on day 14 of bed rest, and day 6 after bed rest. Blood plasma samples were also obtained at these times, and analyzed for several enzymes. On day 14 of bed rest significant increases were observed in urine excretion of total osmotically-active substances, magnesium, calcium, phosphate, creatinine, hydroxyproline, and 17-OH corticosteroids. A decrease occurred in urinary glucose excretion. Plasma levels of alkaline phosphatase and LDH-3 were depressed, while plasma GPT was elevated. Many of these changes persisted on day 6 after bed rest, and are interpreted as concomitants of the disuse atrophy of the musculoskeletal system that characterizes prolonged bed rest and weightlessness.

  17. Changes in markers of bone formation and resorption in a bed rest model of weightlessness

    NASA Technical Reports Server (NTRS)

    Lueken, S. A.; Arnaud, S. B.; Taylor, A. K.; Baylink, D. J.

    1993-01-01

    To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

  18. Gender Differences in Baroreflex Sensitivity after Bed Rest

    NASA Technical Reports Server (NTRS)

    Arzeno, Natalia M.; Stenger, M. B.; Ribeiro, L. C.; Lee, S. M.; Platts, S. H.

    2009-01-01

    Two potential contributing factors to post-spaceflight orthostatic intolerance are decreases in baroreflex sensitivity (BRS) and sympathetic nervous system response. The purpose of this study was to examine the shape of the BRS curve and sympathetic response to a wide range of blood pressures (BP) before and during 6 head-down bed rest (BR). METHODS: Normal volunteers were tested one day before BR (20M, 1 0F) and near BR days 30 (20M, 10F), 60 (16M, 8F), and 90 (1 0M, 5F). BP was pharmacologically manipulated by 10-min infusions of phenylephrine (PE) and sodium nitroprusside (SNP) at 3 increasing concentrations with a 20-min rest between PE and SNP. Electrocardiogram and continuous finger blood pressure were recorded. A blood sample was drawn at the end of each infusion to measure plasma norepinephrine levels. The spontaneous baroreflex slope (SBS), a measure of BRS, was calculated as the slope of a sequence of 3 or more beats in which the systolic BP (SBP) and following R-R interval (RR) both increased or decreased. The data included saturated responses at the upper but not the lower end of the BP range. Mean response curves were constructed using second-order mixed model analysis. Results are based on term significance in the models. RESULTS RR: RR was lower during BR than pre BR (p<0.001). Pre BR males were modeled by a linear RR response to SBP (p=0.000) while females had a quadratic response which saturated at high SBP (p=0.019). By day 30, both genders were modeled by a linear response; compared to males, females had an attenuated (lower slope) RR response to changes in SBP (p=0.031). SBS: SBS vs SBP analysis showed a lower SBS during BR (p<0.001) when compared to pre BR. Females had a higher SBS than males pre BR (p=0.006). Females exhibited saturating SBS at higher SBP (p=0.016) on day 30, while males were modeled by a linear SBS response to SBP (p=0.035). NE: Females had different NE response to diastolic BP than males pre BR (p=0.035) and on day 30 (p=0

  19. Pressure distension in leg vessels as influenced by prolonged bed rest and a pressure habituation regimen.

    PubMed

    Eiken, Ola; Mekjavic, Igor B; Kounalakis, Stylianos N; Kölegård, Roger

    2016-06-15

    Bed rest increases pressure distension in arteries, arterioles, and veins of the leg. We hypothesized that bed-rest-induced deconditioning of leg vessels is governed by the removal of the local increments in transmural pressure induced by assuming erect posture and, therefore, can be counteracted by intermittently increasing local transmural pressure during the bed rest. Ten men underwent 5 wk of horizontal bed rest. A subatmospheric pressure (-90 mmHg) was intermittently applied to one lower leg [pressure habituation (PH) leg]. Vascular pressure distension was investigated before and after the bed rest, both in the PH and control (CN) leg by increasing local distending pressure, stepwise up to +200 mmHg. Vessel diameter and blood flow were measured in the posterior tibial artery and vessel diameter in the posterior tibial vein. In the CN leg, bed rest led to 5-fold and 2.7-fold increments (P < 0.01) in tibial artery pressure-distension and flow responses, respectively, and to a 2-fold increase in tibial vein pressure distension. In the PH leg, arterial pressure-distension and flow responses were unaffected by bed rest, whereas bed rest led to a 1.5-fold increase in venous pressure distension. It thus appears that bed-rest-induced deconditioning of leg arteries, arterioles, and veins is caused by removal of gravity-dependent local pressure loads and may be abolished or alleviated by a local pressure-habituation regimen. PMID:27079693

  20. Pressure distension in leg vessels as influenced by prolonged bed rest and a pressure habituation regimen.

    PubMed

    Eiken, Ola; Mekjavic, Igor B; Kounalakis, Stylianos N; Kölegård, Roger

    2016-06-15

    Bed rest increases pressure distension in arteries, arterioles, and veins of the leg. We hypothesized that bed-rest-induced deconditioning of leg vessels is governed by the removal of the local increments in transmural pressure induced by assuming erect posture and, therefore, can be counteracted by intermittently increasing local transmural pressure during the bed rest. Ten men underwent 5 wk of horizontal bed rest. A subatmospheric pressure (-90 mmHg) was intermittently applied to one lower leg [pressure habituation (PH) leg]. Vascular pressure distension was investigated before and after the bed rest, both in the PH and control (CN) leg by increasing local distending pressure, stepwise up to +200 mmHg. Vessel diameter and blood flow were measured in the posterior tibial artery and vessel diameter in the posterior tibial vein. In the CN leg, bed rest led to 5-fold and 2.7-fold increments (P < 0.01) in tibial artery pressure-distension and flow responses, respectively, and to a 2-fold increase in tibial vein pressure distension. In the PH leg, arterial pressure-distension and flow responses were unaffected by bed rest, whereas bed rest led to a 1.5-fold increase in venous pressure distension. It thus appears that bed-rest-induced deconditioning of leg arteries, arterioles, and veins is caused by removal of gravity-dependent local pressure loads and may be abolished or alleviated by a local pressure-habituation regimen.

  1. Focal Gray Matter Plasticity as a Function of Long Duration Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Koppelmans, V.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Koppelmans, V.

    2014-01-01

    Long duration spaceflight (i.e., > or = 22 days) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes may be related to structural and functional brain changes is yet unknown. However, experimental studies revealed changes in the gray matter (GM) of the brain after simulated microgravity. Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning and motor behavior. Long duration head-down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system. Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on the brain. VBM analysis revealed a progressive decrease from pre- to in- bed rest in GM volume in bilateral areas including the frontal medial cortex, the insular cortex and the caudate. Over the same time period, there was a progressive increase in GM volume in the cerebellum, occipital-, and parietal cortex, including the precuneus. The majority of these changes did not fully recover during the post-bed rest period. Analysis of lobular GM volumes obtained with BRAINS showed significantly increased volume from pre-bed rest to in-bed rest in GM of the parietal lobe and the third ventricle. Temporal GM volume at 70 days in bed rest was smaller than that at the first pre-bed rest measurement. Trend analysis showed significant positive linear and negative quadratic relationships between parietal GM and time, a positive linear relationship between third ventricle volume and time, and a negative linear

  2. A Comparison of Tandem Walk Performance Between Bed Rest Subjects and Astronauts

    NASA Technical Reports Server (NTRS)

    Miller, Chris; Peters, Brian; Kofman, Igor; Philips, Tiffany; Batson, Crystal; Cerisano, Jody; Fisher, Elizabeth; Mulavara, Ajitkumar; Feiveson, Alan; Reschke, Millard; Bloomberg, Jacob

    2015-01-01

    Astronauts experience a microgravity environment during spaceflight, which results in a central reinterpretation of both vestibular and body axial-loading information by the sensorimotor system. Subjects in bed rest studies lie at 6deg head-down in strict bed rest to simulate the fluid shift and gravity-unloading of the microgravity environment. However, bed rest subjects still sense gravity in the vestibular organs. Therefore, bed rest isolates the axial-unloading component, thus allowing for the direct study of its effects. The Tandem Walk is a standard sensorimotor test of dynamic postural stability. In a previous abstract, we compared performance on a Tandem Walk test between bed rest control subjects, and short- and long-duration astronauts both before and after flight/bed rest using a composite index of performance, called the Tandem Walk Parameter (TWP), that takes into account speed, accuracy, and balance control. This new study extends the previous data set to include bed rest subjects who performed exercise countermeasures. The purpose of this study was to compare performance during the Tandem Walk test between bed rest subjects (with and without exercise), short-duration (Space Shuttle) crewmembers, and long-duration International Space Station (ISS) crewmembers at various time points during their recovery from bed rest or spaceflight.

  3. Plasma vasopressin and renin activity in women exposed to bed rest and +G/z/ acceleration

    NASA Technical Reports Server (NTRS)

    Keil, L. C.; Ellis, S.

    1976-01-01

    To study the effect of prolonged recumbency on plasma vasopressin and renin activity, eight women were subjected to 17 days of absolute bed rest. The tolerance to +3G vertical acceleration of the subjects was tested before and after 14 days of bed rest. From day 2 and through day 17 of bed rest, plasma arginine vasopressin (AVP) levels were reduced 33%. Plasma renin activity (PRA) increased 91% above ambulatory control values from days 10 through 15 of bed rest. When compared to precentrifuge values, exposure to vertical acceleration prior to bed rest provoked a 20-fold rise in mean plasma AVP but resulted in only a slight increase in PRA. After bed rest, acceleration increased plasma AVP 7-fold; however, the magnitude of this increase was less than the post +3G acceleration value obtained prior to bed rest. After bed rest, no significant rise was noted in PRA following +3G acceleration. This study demonstrates that prolonged bed rest leads to a significant rise in the PRA of female subjects, while exposure to positive vertical acceleration provokes a marked rise in plasma AVP.

  4. Effects of head-down bed rest on complex heart rate variability: Response to LBNP testing

    NASA Technical Reports Server (NTRS)

    Goldberger, Ary L.; Mietus, Joseph E.; Rigney, David R.; Wood, Margie L.; Fortney, Suzanne M.

    1994-01-01

    Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 deg head-down bed rest study with serial lower body negative pressure (LBNP) trials. Heart rate variability was measured on a 4-min data sets using conventional time and frequency domain measures as well as with a new measure of signal 'complexity' (approximate entropy). Data were obtained pre-bed rest (control), during bed rest (day 4 and day 9 or 11), and 2 days post-bed rest (recovery). Tolerance to LBNP was significantly reduced on both bed rest days vs. pre-bed rest. Heart rate variability was assessed at peak LBNP. Heart rate approximate entropy was significantly decreased at day 4 and day 9 or 11, returning toward normal during recovery. Heart rate standard deviation and the ratio of high- to low-power frequency did not change significantly. We conclude that short-term bed rest is associated with a decrease in the complex variability of heart rate during LBNP testing in healthy young adult women. Measurement of heart rate complexity, using a method derived from nonlinear dynamics ('chaos theory'), may provide a sensitive marker of this loss of physiological variability, complementing conventional time and frequency domain statistical measures.

  5. Effects of Fourteen-Day Bed Rest on Trunk Stabilizing Functions in Aging Adults

    PubMed Central

    Sarabon, Nejc; Rosker, Jernej

    2015-01-01

    Bed rest has been shown to have detrimental effects on structural and functional characteristics of the trunk muscles, possibly affecting trunk and spinal stability. This is especially important in populations such as aging adults with often altered trunk stabilizing functions. This study examined the effects of a fourteen-day bed rest on anticipatory postural adjustments and postural reflex responses of the abdominal wall and back muscles in sixteen adult men. Postural activation of trunk muscles was measured using voluntary quick arm movement and sudden arm loading paradigm. Measurements were conducted prior to the bed rest, immediately after, and fourteen days after the bed rest. Immediately after the bed rest, latencies of anticipatory postural adjustments showed significant shortening, especially for the obliquus internus and externus muscles. After a fourteen-day recuperation period, anticipatory postural adjustments reached a near to complete recovery. On the contrary, reactive response latencies increased from pre-bed-rest to both post-bed-rest measurement sessions. Results indicate an important effect of bed rest on stabilizing functions of the trunk muscles in elderly adults. Moreover, there proved to be a significant deterioration of postural reactive responses that outlasted the 14-day post-bed-rest rehabilitation. PMID:26601104

  6. Changes in mood status and neurotic levels during a 20-day bed rest

    NASA Astrophysics Data System (ADS)

    Ishizaki, Yuko; Ishizaki, Tatsuro; Fukuoka, Hideoki; Kim, Chang-Sun; Fujita, Masayo; Maegawa, Yuko; Fujioka, Hiroshi; Katsura, Taisaku; Suzuki, Yoji; Gunji, Atsuaki

    2002-04-01

    This study evaluated changes of mood status and depressive and neurotic levels in nine young male subjects during a 20-day 6° head-down tilting bed rest and examined whether exercise training modified these changes. Participants were asked to complete psychometrical inventories on before, during, and after the bed rest experiment. Depressive and neurotic levels were enhanced during bed rest period according to the Japanese version of Zung's Self-rating Depression Scale and the Japanese version of the General Health Questionnaire. Mood state "vigor" was impaired and "confusion" was increased during bed rest and recumbent control periods compared to pre-bed rest and ambulatory control periods according to the Japanese version of Profiles of Mood State, whereas the mood "tension-anxiety", "depression-dejection", "anger-hostility" and "fatigue" were relatively stable during experiment. Isometric exercise training did not modify these results. Microgravity, along with confinement to bed and isolation from familiar environments, induced impairment of mental status.

  7. Fibroblast Growth Factor-23 in Bed Rest and Spaceflight

    NASA Technical Reports Server (NTRS)

    Bokhari, R.; Zwart, S. R; Fields, E.; Heer, M.; Sibonga, J.; Smith, S. M.

    2014-01-01

    Many nutritional factors influence bone, from the basics of calcium and vitamin D, to factors which influence bone through acid/base balance, including protein, sodium, and more. Fibroblast growth factor 23 (FGF23) is a recently identified factor, secreted from osteocytes, which is involved in classic (albeit complex) feedback loops controlling phosphorus homeostasis through both vitamin D and parathyroid hormone (PTH) (1, 2). As osteocytes are gravity sensing cells, it is important to determine if there are changes in FGF23 during spaceflight. In extreme cases, such as chronic kidney disease, FGF23 levels are highly elevated. FGF23 imbalances, secondary to dietary influences, may contribute to skeletal demineralization and kidney stone risk during spaceflight. Presented with an imbalanced dietary phosphorus to calcium ratio, increased secretion of FGF23 will inhibit renal phosphorus reabsorption, resulting in increased excretion and reduced circulating phosphorus. Increased intake and excretion of phosphorus is associated with increased kidney stone risk in both the terrestrial and microgravity environments. Highly processed foods and carbonated beverages are associated with higher phosphorus content. Ideally, the dietary calcium to phosphorus ratio should be at minimum 1:1. Nutritional requirements for spaceflight suggest that this ratio not be less than 0.67 (3), while the International Space Station (ISS) menu provides 1020 mg Ca and 1856 mg P, for a ratio of 0.55 (3). Subjects in NASA's bed rest studies, by design, have consumed intake ratios much closer to 1.0 (4). FGF23 also has an inhibitory influence on PTH secretion and 1(alpha)-hydroxylase, both of which are required for activating vitamin D with the conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D. Decreased 1,25-dihydroxyvitamin D will result in decreased intestinal phosphorus absorption, and increased urinary phosphorus excretion (via decreased renal reabsorption). Should a decrease in 1

  8. Exercise Thermoregulation Following 13 Days of Bed Rest

    NASA Technical Reports Server (NTRS)

    Lee, Stuart M. C.; Williams, W. Jon; Schneider, Suzanne M.

    2001-01-01

    This investigation examined two potential mechanisms, altered skin blood flow (SBF) and sweating rate (SR) responses, that may be responsible for an elevated core temperature during exercise after bed rest (BR) and space flight. Seven healthy men (29 +/- 5 yr, 179.6 +/- 7.1 cm, 77.2 +/- 17.0kg; mean +/- SD) underwent 13 days of 6 deg head-down BR. Pre- and post-BR, subjects completed supine submaximal cycle ergometry (20 min at 40% and 20 min at 65% of pre-BR supine VO2pk) in a thermoneutral room (23.4 +/- 0.5 C, 56 +/- 8 %RH) during, heat production (VO2 ; indirect calorimetry), intestinal temperature (T(sub in) ; ingestible pill), SBF (laser Doppler velocimetry), local SR (dew point hygrometry), and total sweat loss (TSL; Delta body weight) were measured. Pre- and post- BR plasma volume (PV) was measured using I-125 dilution. After BR, T(sub in) was elevated at rest (36.99 +/- 0.14 vs. 37.30 +/- 0.06 C; p<_0.05) and at the end of exercise (37.57 +/- 0.13 vs. 37.90 +/- 0.09 C; P less than or equal to 0.05). However, the increase in T(sub in) from rest to the end of exercise was not different after BR (0.59 +/- 0.07 vs. 0.60 +/- 0.07 C). There was no difference in VO2 pre- to post-BR during rest (0.28 +/- 0.04 vs. 0.24 +/- 0.03 1 multiplied by min(exp -1) ) or 40% VO2pk (0.95 +/- 0.08 vs. 0.96 +/- 0.05 1 multiplied by min(exp -1)), but VO2 was significantly less at the end of the 65% VO2pk stage (1.53 +/- 0.09 vs. 1.42 +/- 0.11 1 multiplies by min(exp - 1); p less than or equal to 0.05). The percent change in SBF from rest to end of exercise was less after BR (211 +/- 53 vs. 96 +/- 31%; p less than or equal to 0.05), the threshold for the onset of SBF was greater (37.17 +/- 0.18vs. 37.51 +/- 0.17 C; p less than or equal to 0.05), and the slope of the response tended to be reduced (536 +/- 184 vs. 201 +/- 46 %A PC; p=0.08). TSL was not different after BR (0.42+0.06 vs. 0.44 +/- 0.08 kg), but the T in threshold at the onset of sweating was delayed significantly (37

  9. Bone metabolism and nutritional status during 30-day head-down-tilt bed rest.

    PubMed

    Morgan, Jennifer L L; Zwart, Sara R; Heer, Martina; Ploutz-Snyder, Robert; Ericson, Karen; Smith, Scott M

    2012-11-01

    Bed rest studies provide an important tool for modeling physiological changes that occur during spaceflight. Markers of bone metabolism and nutritional status were evaluated in 12 subjects (8 men, 4 women; ages 25-49 yr) who participated in a 30-day -6° head-down-tilt diet-controlled bed rest study. Blood and urine samples were collected twice before, once a week during, and twice after bed rest. Data were analyzed using a mixed-effects linear regression with a priori contrasts comparing all days to the second week of the pre-bed rest acclimation period. During bed rest, all urinary markers of bone resorption increased ~20% (P < 0.001), and serum parathyroid hormone decreased ~25% (P < 0.001). Unlike longer (>60 days) bed rest studies, neither markers of oxidative damage nor iron status indexes changed over the 30 days of bed rest. Urinary oxalate excretion decreased ~20% during bed rest (P < 0.001) and correlated inversely with urinary calcium (R = -0.18, P < 0.02). These data provide a broad overview of the biochemistry associated with short-duration bed rest studies and provide an impetus for using shorter studies to save time and costs wherever possible. For some effects related to bone biochemistry, short-duration bed rest will fulfill the scientific requirements to simulate spaceflight, but other effects (antioxidants/oxidative damage, iron status) do not manifest until subjects are in bed longer, in which case longer studies or other analogs may be needed. Regardless, maximizing research funding and opportunities will be critical to enable the next steps in space exploration. PMID:22995395

  10. Bed-rest studies: Fluid and electrolyte responses

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.

    1983-01-01

    Confinement in the horizontal position for 2 to 3 weeks results in a chronic decrease in plasma volume, increased interstitial fluid volume, and unchanged or slightly increased extracellular fluid volume. Concentrations of blood electrolytes, glucose, and nitrogenous constituents remain within normal limits of variability when maintenance levels of isometric or isotonic exercise are performed for 1 hr/day. Hematocrit and plasma osmolality can be elevated significantly throughout bed rest (BR). Significant diuresis occurs on the first day, and increases in urine Na and Ca continue throughout BR, although voluntary fluid intake is unchanged. Urine Na and K are evaluated during the second week of BR in spite of stabilization of PV and extracellular volume. The initial diuresis probably arises from the extracellular fluid while subsequent urine loss above control levels must come from the intracellular fluid. Preservation of the extracellular volume takes precedance over maintenance of the intracellular fluid volume. The functioning of a natriuretic factor (hormone) to account for the continued increased loss of Na in the urine is suggested.

  11. Depression, mood state, and back pain during microgravity simulated by bed rest

    NASA Technical Reports Server (NTRS)

    Styf, J. R.; Hutchinson, K.; Carlsson, S. G.; Hargens, A. R.

    2001-01-01

    OBJECTIVE: The objective of this study was to develop a ground-based model for spinal adaptation to microgravity and to study the effects of spinal adaptation on depression, mood state, and pain intensity. METHODS: We investigated back pain, mood state, and depression in six subjects, all of whom were exposed to microgravity, simulated by two forms of bed rest, for 3 days. One form consisted of bed rest with 6 degrees of head-down tilt and balanced traction, and the other consisted of horizontal bed rest. Subjects had a 2-week period of recovery between the studies. The effects of bed rest on pain intensity in the lower back, depression, and mood state were investigated. RESULTS: Subjects experienced significantly more intense lower back pain, lower hemisphere abdominal pain, headache, and leg pain during head-down tilt bed rest. They had higher scores on the Beck Depression Inventory (ie, were more depressed) and significantly lower scores on the activity scale of the Bond-Lader questionnaire. CONCLUSIONS: Bed rest with 6 degrees of head-down tilt may be a better experimental model than horizontal bed rest for inducing the pain and psychosomatic reactions experienced in microgravity. Head-down tilt with balanced traction may be a useful method to induce low back pain, mood changes, and altered self-rated activity level in bed rest studies.

  12. In Vivo measurement of human body composition. [during continuous bed rest

    NASA Technical Reports Server (NTRS)

    Pace, N.; Grunbaum, B. W.; Kodama, A. M.; Price, D. C.

    1975-01-01

    Physiological changes in human beings were studied during a 21 day bed rest regime. Results of blood analyses indicated clearly that major metabolic adjustments occurred during prolonged bed rest. However, urinary metabolic analyses showed variances attributed to specimen collection inaccuracies and the small number of test subjects.

  13. Effects of prolonged head-down bed rest on working memory

    PubMed Central

    Liu, Qing; Zhou, Renlai; Zhao, Xin; Oei, Tian Po S

    2015-01-01

    Background The weightlessness caused by prolonged bed rest results in changes in cerebral circulation and thus, brain functions, which is of interest. Methods We investigated the effects of 45-day, −6° head-down bed rest, which stimulated microgravity, on working memory in 16 healthy male participants. The 2-back task was used to test the working memory variations on the 2nd day before bed rest (R−2); on the 11th (R11), 20th (R20), 32nd (R32), and 40th (R40) days of bed rest; and on the eighth day after bed rest (R+8). The cognitive response and the physiological reactivity (such as galvanic skin response, heart rate, and heart rate variability) under the 2-back task were recorded simultaneously. Results The results showed that compared with R−2, on the R+8, the participants’ galvanic skin response increased significantly, and the high frequency of heart rate variability (HF), low frequency of heart rate variability (LF), and reaction time in the 2-back task decreased significantly. There were positive correlations between the participants’ reaction time of working memory and the LF/HF under head-down bed rest (at R11, R20, and R32). Conclusion The results suggested that the prolonged head-down bed rest may have a detrimental effect on individual physiology and working memory. Physiology indices, such as galvanic skin response and heart rate variability, were sensitive to the prolonged bed rest. PMID:25848281

  14. Effects of Head-Down Bed Rest on the Executive Functions and Emotional Response

    PubMed Central

    Liu, Qing; Zhou, Renlai; Chen, Shanguang; Tan, Cheng

    2012-01-01

    Prolonged bed rest may cause changes in the autonomic nervous system that are related to cognition and emotion. This study adopted an emotional flanker task to evaluate the effect of 45 days -6° head-down bed rest (HDBR) on executive functioning in 16 healthy young men at each of six time points: the second-to-last day before the bed rest period, the eleventh, twentieth, thirty-second and fortieth day during the bed rest period, and the eighth day after the bed rest period. In addition, self-report inventories (Beck Anxiety Inventory, BAI; Beck Depression Inventory, BDI; Positive Affect and Negative Affect Scale, PANAS) were conducted to record emotional changes, and the participants’ galvanic skin response (GSR), heart rate (HR) and heart rate variability (HRV) were assessed as measures of physiological activity. The results showed that the participants’ reaction time on the flanker task increased significantly relative to their responses on the second-to-last day before the period of bed rest, their galvanic skin response weakened and their degrees of positive affect declined during the bed rest period. Our results provide some evidence for a detrimental effect of prolonged bed rest on executive functioning and positive affect. Whether this stems from a lack of aerobic physical activity and/or the effect of HDBR itself remains to be determined. PMID:23284916

  15. Study report on modification of the long term circulatory model for the simulation of bed rest

    NASA Technical Reports Server (NTRS)

    Leonard, J. I.; Grounds, D. J.

    1977-01-01

    Modifications were made of the circulatory, fluid, and electrolyte control model which was based on the model of Guyton. The modifications included separate leg compartments and the addition of gravity dependency. It was found that these modifications allowed for more accurate bed rest simulation by simulating changes in the orthostatic gradient and simulating the response to the fluid shifts associated with bed rest.

  16. Effect of prolonged bed rest on lung volume in normal individuals

    NASA Technical Reports Server (NTRS)

    Beckett, W. S.; Vroman, N. B.; Nigro, D.; Thompson-Gorman, S.; Wilkerson, J. E.

    1986-01-01

    The effect of prolonged bed rest on the lung function was studied by measuring forced vital capacity (FVC) and total lung capacity (TLC) in normal subjects before, during, and after 11- to 12-day rest periods. It was found that both FVC and TLC increased during bed rest (compared with the ambulatory controls), while residual volume and functional residual capacity of the respiratory system did not change. It is concluded that the increase in TLC by prolonged bed rest is not dependent on alterations in plasma volume.

  17. The NASA performance assessment workstation: Cognitive performance during head-down bed rest

    NASA Astrophysics Data System (ADS)

    Shehab, Randa L.; Schlegel, Robert E.; Schiflett, Samuel G.; Eddy, Douglas R.

    The NASA Performance Assessment Workstation was used to assess cognitive performance changes in eight males subjected to seventeen days of 6 ° head-down bed rest. PAWS uses six performance tasks to assess directed and divided attention, spatial, mathematical, and memory skills, and tracking ability. Subjective scales assess overall fatigue and mood state. Subjects completed training trials, practice trials, bed rest trials, and recovery trials. The last eight practice trials and all bed rest trials were performed with subjects lying face-down on a gurney. In general, there was no apparent cumulative effect of bed rest. Following a short period of performance stabilization, a slight but steady trend of performance improvement was observed across all trials. For most tasks, this trend of performance improvement was enhanced during recovery. No statistically significant differences in performance were observed when comparing bed rest with the control period. Additionally, fatigue scores showed little change across all periods.

  18. Resistance exercise prevents plantar flexor deconditioning during bed rest

    NASA Technical Reports Server (NTRS)

    Bamman, M. M.; Hunter, G. R.; Stevens, B. R.; Guilliams, M. E.; Greenisen, M. C.

    1997-01-01

    Because resistance exercise (REX) and unloading induce opposing neuromuscular adaptations, we tested the efficacy of REX against the effects of 14 d of bed rest unloading (BRU) on the plantar flexor muscle group. Sixteen men were randomly assigned to no exercise (NOE, N = 8) or REX (N = 8). REX performed 5 sets x 6-10 repetitions to failure of constant resistance concentric/eccentric plantar flexion every other day during BRU. One-repetition maximum (1RM) strength was tested on the training device. The angle-specific torque-velocity relationship across 5 velocities (0, 0.52, 1.05, 1.75, and 2.97 rad.s-1) and the full range-of-motion power-velocity relationship were assessed on a dynamometer. Torque-position analyses identified strength changes at shortened, neutral, and stretched muscle lengths. Concentric and eccentric contractile work were measured across ten repetitions at 1.05 rad.s-1. Maximal neural activation was measured by surface electromyography (EMG). 1RM decreased 9% in NOE and improved 11% in REX (P < 0.05). Concentric (0.52 and 1.05 rad.s-1), eccentric (0.52 and 2.97 rad.s-1), and isometric angle-specific torques decreased (P < 0.05) in NOE, averaging 18%, 17%, and 13%, respectively. Power dropped (P < 0.05) in NOE at three eccentric (21%) and two concentric (14%) velocities. REX protected angle-specific torque and average power at all velocities. Concentric and eccentric strength decreased at stretched (16%) and neutral (17%) muscle lengths (P < 0.05) in NOE while REX maintained or improved strength at all joint positions. Concentric (15%) and eccentric (11%) contractile work fell in NOE (P < 0.05) but not in REX. Maximal plantar flexor EMG did not change in either group. In summary, constant resistance concentric/eccentric REX completely prevented plantar flexor performance deconditioning induced by BRU. The reported benefits of REX should prove useful in prescribing exercise for astronauts in microgravity and for patients susceptible to functional

  19. Intensive exercise training suppresses testosterone during bed rest

    NASA Technical Reports Server (NTRS)

    Wade, C. E.; Stanford, K. I.; Stein, T. P.; Greenleaf, J. E.

    2005-01-01

    Spaceflight and prolonged bed rest (BR) alter plasma hormone levels inconsistently. This may be due, in part, to prescription of heavy exercise as a countermeasure for ameliorating the adverse effects of disuse. The initial project was to assess exercise programs to maintain aerobic performance and leg strength during BR. The present study evaluates the effect of BR and the performance of the prescribed exercise countermeasures on plasma steroid levels. In a 30-day BR study of male subjects, the efficacy of isotonic (ITE, n = 7) or isokinetic exercise (IKE, n = 7) training was evaluated in contrast to no exercise (n = 5). These exercise countermeasures protected aerobic performance and leg strength successfully. BR alone (no-exercise group) did not change steroidogenesis, as assessed by the plasma concentrations of cortisol, progesterone, aldosterone, and free (FT) and total testosterone (TT). In the exercise groups, both FT and TT were decreased (P < 0.05): FT during IKE from 24 +/- 1.7 to 18 +/- 2.0 pg/ml and during ITE from 21 +/- 1.5 to 18 +/- 1 pg/ml, and TT during IKE from 748 +/- 68 to 534 +/- 46 ng/dl and during ITE from 565 +/- 36 to 496 +/- 38 ng/dl. The effect of intensive exercise countermeasures on plasma testosterone was not associated with indexes of overtraining. The reduction in plasma testosterone associated with both the IKE and ITE countermeasures during BR supports our hypothesis that intensive exercise countermeasures may, in part, contribute to changes in plasma steroid concentrations during spaceflight.

  20. The Effects of Long Duration Bed Rest on Brain Functional Connectivity and Sensorimotor Functioning

    NASA Technical Reports Server (NTRS)

    Cassady, K.; Koppelmans, V.; De Dios, Y.; Stepanyan, V.; Szecsy, D.; Gadd, N.; Wood, S.; Reuter-Lorenz, P.; Castenada, R. Riascos; Kofman, I.; Bloomberg, J.; Mulavara, A; Seidler, R.

    2016-01-01

    Long duration spaceflight has been associated with detrimental alterations in human sensorimotor functioning. Prolonged exposure to a head-down tilt (HDT) position during long duration bed rest can resemble several effects of the microgravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The question of whether microgravity affects other central nervous system functions such as brain functional connectivity and its relationship with behavior is largely unknown, but of importance to the health and performance of astronauts both during and post-flight. In the present study, we investigate the effects of prolonged exposure to HDT bed rest on resting state brain functional connectivity and its association with behavioral changes in 17 male participants. To validate that our findings were not due to confounding factors such as time or task practice, we also acquired resting state functional magnetic resonance imaging (rs-fMRI) and behavioral measurements from 14 normative control participants at four time points. Bed rest participants remained in bed with their heads tilted down six degrees below their feet for 70 consecutive days. Rs-fMRI and behavioral data were obtained at seven time points averaging around: 12 and 8 days prior to bed rest; 7, 50, and 70 days during bed rest; and 8 and 12 days after bed rest. 70 days of HDT bed rest resulted in significant increases in functional connectivity during bed rest followed by a reversal of changes in the post bed rest recovery period between motor cortical and somatosensory areas of the brain. In contrast, decreases in connectivity were observed between temporoparietal regions. Furthermore, post-hoc correlation analyses revealed a significant relationship between motor-somatosensory network connectivity and standing balance performance changes; participants that exhibited the greatest increases in connectivity strength showed the least deterioration in postural

  1. Bed rest decreases mechanically induced myofiber wounding and consequent wound-mediated FGF release.

    PubMed

    Clarke, M S; Bamman, M M; Feeback, D L

    1998-08-01

    Using a terrestrial model of spaceflight (i.e., bed rest), we investigated the amount of myofiber wounding and fibroblast growth factor (FGF) release that occurs during unloading. Myofiber wounding was determined by serum levels of the creatine kinase MM (CKMM) isoform before and after bed rest. Serum levels of both acidic FGF (aFGF) and basic FGF were also determined. A second group of subjects was treated in an identical fashion except that they underwent a resistive exercise program during bed rest. Bed rest alone caused significant (P < 0.05; n = 7) reductions in post-bed-rest serum levels of both CKMM and aFGF, which were paralleled by a significant (P < 0.05; n = 7) decrease in myofiber size. In contrast, bed rest plus resistive exercise resulted in significant (P < 0.05; n = 7) increases in post-bed-rest serum levels of both CKMM and aFGF, which were paralleled by inhibition of the atrophic response. These results suggest that mechanically induced, myofiber wound-mediated FGF release may play an important role in the etiology of unloading-induced skeletal muscle atrophy. PMID:9688737

  2. Short term bed-rest reduces conduction velocity of individual motor units in leg muscles.

    PubMed

    Cescon, Corrado; Gazzoni, Marco

    2010-10-01

    Space permanence simulations such as prolonged bed-rest can mimic some of the physiological modifications in the human body and provide study conditions that are more accessible than during space flight. A short term bed-rest experiment was organized to simulate the effects of weightlessness for studying the adaptation to this condition. Eight healthy young volunteers were studied before and immediately after the 14day periods of strict bed-rest. Surface EMG signals were detected with linear electrode arrays from vastus medialis, vastus lateralis and tibialis anterior muscle during isometric voluntary contractions at 20% MVC. Motor unit action potentials (MUAPs) of individual motor units were extracted from the interference EMG signals with a partial decomposition algorithm and averaged. MUAP templates generated by the same motor unit could be retrieved before and after bed-rest period. Muscle fiber conduction velocity (CV) was estimated from each averaged MUAP template and from the global EMG signal. Both global and single MU conduction velocity was observed to decrease by about 10% after the bed-rest period (p<0.05). Amplitude and power spectral parameters did not significantly change after the bed-rest period. It is concluded that a short term bed-rest reduces the CV of individual motor units without a significant effect on muscle force or on other electrophysiological parameters.

  3. Branched-chain amino acid supplementation during bed rest: effect on recovery

    NASA Technical Reports Server (NTRS)

    Stein, T. P.; Donaldson, M. R.; Leskiw, M. J.; Schluter, M. D.; Baggett, D. W.; Boden, G.

    2003-01-01

    Bed rest is associated with a loss of protein from the weight-bearing muscle. The objectives of this study are to determine whether increasing dietary branched-chain amino acids (BCAAs) during bed rest improves the anabolic response after bed rest. The study consisted of a 1-day ambulatory period, 14 days of bed rest, and a 4-day recovery period. During bed rest, dietary intake was supplemented with either 30 mmol/day each of glycine, serine, and alanine (group 1) or with 30 mmol/day each of the three BCAAs (group 2). Whole body protein synthesis was determined with U-(15)N-labeled amino acids, muscle, and selected plasma protein synthesis with l-[(2)H(5)]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with l-[U-(13)C(3)]alanine and [6,6-(2)H(2)]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 +/- 6 vs. 26 +/- 12 mg N. kg(-1). day(-1), P < 0.05). There was no effect of BCAA supplementation on either whole body, muscle, or plasma protein synthesis or the rate of 3-MeH excretion. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 +/- 0.066 vs. 0.088 +/- 0.12 nmol/mg protein, P < 0.05). Total glucose production and gluconeogenesis from alanine were unchanged with bed rest but were significantly reduced (P < 0.05) with the BCAA group in the recovery phase. In conclusion, the improved N retention during bed rest is due, at least in part, to accretion of amino acids in the tissue free amino acid pools. The amount accreted is not enough to impact protein kinetics in the recovery phase but does improve N retention by providing additional essential amino acids in the early recovery phase.

  4. Effects of acute exercise on attenuated vagal baroreflex function during bed rest

    NASA Technical Reports Server (NTRS)

    Convertino, Victor A.; Doerr, Donald F.; Guell, Antonio; Marini, J.-F.

    1992-01-01

    We measured carotid baroreceptor-cardiac reflex responses in six healthy men, 24 h before and 24 h after a bout of leg exercise during 6 deg head-down bed rest to determine if depressed vagal baroreflex function associated with exposure to microgravity environments could be reversed by a single exposure to acute intense exercise. Baroreflex responses were measured before bed rest and on day 7 of bed rest. An exercise bout consisting of dynamic and isometric actions of the quadriceps at graded speeds and resistances was performed on day 8 of bed rest and measurements of baroreflex response were repeated 24 h later. Vagally-mediated cardiac responses were provoked with ramped neck pressure-suction sequences comprising pressure elevations to +40 mm Hg, followed by serial, R-wave triggered 15 mm Hg reductions, to -65 mm Hg. Baroreceptor stimulus-cardiac response relationships were derived by plotting each R-R interval as a function of systolic pressure less the neck chamber pressure applied during the interval. Compared with pre-bed rest baseline measurements, 7 d of bed rest decreased the gain (maximum slope) of the baroreflex stimulus-response relationship by 16.8 +/- 3.4 percent (p less than 0.05). On day 9 of bed rest, 24 h after exercise, the maximum slope of the baroreflex stimulus-response relationship was increased (p less than 0.05) by 10.7 +/- 3.7 percent above pre-bed rest levels and 34.3 +/- 7.9 percent above bed rest day 7. Our data verify that vagally-mediated baroreflex function is depressed by exposure to simulated microgravity and demonstrate that this effect can be acutely reversed by exposure to a single bout of intense exercise.

  5. Analysis of Arterial Mechanics During Head-Down-Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Elliott, Morgan B.; Martin, David S.; Westby, Christian M.; Stenger, Michael B.; Platts, Steven H.

    2014-01-01

    Carotid, brachial, and tibial arteries reacted differently to HDTBR. Previous studies have not analyzed the mechanical properties of the human brachial or anterior tibial arteries. After slight variations during bed-rest, arterial mechanical properties and IMT returned to pre-bed rest values, with the exception of tibial stiffness and PSE, which continued to be reduced post-bed rest while the DC remained elevated. The tibial artery remodeling was probably due to decreased pressure and volume. Resulting implications for longer duration spaceflight are unclear. Arterial health may be affected by microgravity, as shown by increased thoracic aorta stiffness in other ground based simulations (Aubert).

  6. Long Duration Head-Down Tilt Bed Rest Studies: Safety Considerations Regarding Vision Health

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.; Zanello, S. B.; Yarbough, P. O.; Ploutz-Snyder, Robert; Taibbi, G.; Vizzeri, G.

    2012-01-01

    Visual symptoms reported in astronauts returning from long duration missions in low Earth orbit, including hyperopic shift, choroidal folds, globe flattening and papilledema, are thought to be related to fluid shifts within the body due to microgravity exposure. Because of this possible relation to fluid shifts, safety considerations have been raised regarding the ocular health of head-down tilt (HDT) bed rest subjects. HDT is a widely used ground ]based analog that simulates physiological changes of spaceflight, including fluid shifts. Thus, vision monitoring has been performed in bed rest subjects in order to evaluate the safety of HDT with respect to vision health. Here we report ocular outcomes in 9 healthy subjects (age range: 27-48 years; Male/Female ratio: 8/1) completing bed rest Campaign 11, an integrated, multidisciplinary 70-day 6 degrees HDT bed rest study. Vision examinations were performed on a weekly basis, and consisted of office-based (2 pre- and 2 post-bed rest) and in-bed testing. The experimental design was a repeated measures design, with measurements for both eyes taken for each subject at each planned time point. Findings for the following tests were all reported as normal in each testing session for every subject: modified Amsler grid, red dot test, confrontational visual fields, color vision and fundus photography. Overall, no statistically significant differences were observed for any of the measures, except for both near and far visual acuity, which increased during the course of the study. This difference is not considered clinically relevant as may result from the effect of learning. Intraocular pressure results suggest a small increase at the beginning of the bed rest phase (p=0.059) and lesser increase at post-bed rest with respect to baseline (p=0.046). These preliminary results provide the basis for further analyses that will include correlations between intraocular pressure change pre- and post-bed rest, and optical coherence

  7. The Influence of Roughness and Pyrethroid Formulations on Bed Bug (Cimex lectularius L.) Resting Preferences.

    PubMed

    Hottel, Benjamin A; Pereira, Roberto M; Koehler, Philip G

    2015-01-01

    Two-choice tests were conducted to examine the effect of surface roughness on the resting preference of bed bugs, Cimex lectularius L., on copper, basswood, and acrylic materials. The influence of pyrethroid formulation applications on resting preferences was also evaluated. Bed bugs were given the choice of resting between two sanded halves of each material tested. One half was sanded with a P60 grit sandpaper and the other with a less rough P600 grit sandpaper. A significantly higher proportion of bed bugs chose to rest on the rougher P60 grit sanded half of all materials tested. Pyrethroid applications were made to either the P60 grit half or both halves of acrylic arenas and resting preferences were again assessed. Behavioral responses of bed bugs to pyrethroid formulation applications varied depending on the bed bug strain used and the formulation applied. Bed bugs would still rest on the P60 grit half when Suspend SC formulation (0.06% deltamethrin) was applied; however, an avoidance response was observed from a bed bug strain susceptible to D-Force aerosol formulations (0.06% deltamethrin). The avoidance behavior is likely attributed to one, more than one, or even an interaction of multiple spray constituents and not the active ingredient. PMID:26463196

  8. The Influence of Roughness and Pyrethroid Formulations on Bed Bug (Cimex lectularius L.) Resting Preferences

    PubMed Central

    Hottel, Benjamin A.; Pereira, Roberto M.; Koehler, Philip G.

    2015-01-01

    Two-choice tests were conducted to examine the effect of surface roughness on the resting preference of bed bugs, Cimex lectularius L., on copper, basswood, and acrylic materials. The influence of pyrethroid formulation applications on resting preferences was also evaluated. Bed bugs were given the choice of resting between two sanded halves of each material tested. One half was sanded with a P60 grit sandpaper and the other with a less rough P600 grit sandpaper. A significantly higher proportion of bed bugs chose to rest on the rougher P60 grit sanded half of all materials tested. Pyrethroid applications were made to either the P60 grit half or both halves of acrylic arenas and resting preferences were again assessed. Behavioral responses of bed bugs to pyrethroid formulation applications varied depending on the bed bug strain used and the formulation applied. Bed bugs would still rest on the P60 grit half when Suspend SC formulation (0.06% deltamethrin) was applied; however, an avoidance response was observed from a bed bug strain susceptible to D-Force aerosol formulations (0.06% deltamethrin). The avoidance behavior is likely attributed to one, more than one, or even an interaction of multiple spray constituents and not the active ingredient. PMID:26463196

  9. Comparison of Ocular Outcomes in Two 14-Day Bed Rest Studies

    NASA Technical Reports Server (NTRS)

    Cromwell, R. L.; Zanello, S. B.; Yarbough, P. O.; Taibbi, G.; Vizzeri, G.

    2011-01-01

    Reports of astronauts visual changes raised concern about ocular health during long-duration spaceflight. Some of these findings included hyperopic shifts, choroidal folds, optic disc edema, retinal nerve fiber layer (RNFL) thickening, and cotton wool spots. While the etiology remains unknown, hypotheses speculate that hypertension in the brain caused by cephalad fluid shifts during spaceflight is a possible mechanism for these ocular changes. Head-down tilt (HDT) bed rest is a spaceflight analog that induces cephalad fluid shifts. In addition, previous studies of the HDT position demonstrated body fluid shifts associated with changes in intraocular pressure (IOP). For these reasons, vision monitoring of HDT bed rest subjects was implemented for NASA bed rest studies. Subjects selected for these studies were healthy adults (14 males and 5 females). Average age was 37.5 plus or minus 9.1 years, weight was 77.4 plus or minus 11.3 Kg, and height was 173.4 plus or minus 7.2 14 cm. Controlled conditions followed for all NASA bed rest studies were implemented. These conditions included factors such as eating a standardized diet, maintaining a strict sleep wake cycle, and remaining in bed for 24 hours each day. In one study, subjects maintained a horizontal (0 degree) position while in bed and were exercised six days per week with an integrated resistance and aerobic training (iRAT) program. In the other study, subjects were placed at 6 degrees HDT while in bed and did not engage in exercise. All subjects underwent pre- and post bed rest vision testing. While the battery of vision tests for each study was not identical, measures common to both studies will be presented. These measures included IOP and measures that provided an indication of optic disc swelling as derived from optical coherence tomography (OCT) testing: average retinal nerve fiber layer (RNFL) thickness (millimeters), disc area (square millimeters), rim area (square millimters), and average cup to disc (C

  10. Effects of exercise on fluid exchange and body composition in man during 14-day bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Juhos, L. T.; Young, H. L.; Morse, J. T.; Staley, R. W.

    1977-01-01

    A description is presented of an investigation in which body composition, fluid intake, and fluid and electrolyte losses were measured in seven normal, healthy men during three 2-wk bed-rest periods, separated by two 3-wk recovery periods. During bed rest the subjects remained in the horizontal position continuously. During the dietary control periods, body mass decreased significantly with all three regimens, including no exercise, isometric exercise, and isotonic excercise. During bed rest, body mass was essentially unchanged with no exercise, but decreased significantly with isotonic and isometric exercise. With one exception, there were no statistically significant changes in body density, lean body mass, or body fat content by the end of each of the three bed-rest periods.

  11. Plasma lactic dehydrogenase activities in men during bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Juhos, L. T.; Young, H. L.

    1985-01-01

    Peak oxygen uptake and the activity of lactic dehydrogenase (LDH-T) and its five isoenzymes were measured by spectrophotometer in seven men before, during, and after bed rest and exercise training. Exercise training consisted of isometric leg exercises of 250 kcal/hr for a period of one hour per day. It is found that LDH-T was reduced by 0.05 percent in all three regimens by day 10 of bed rest, and that the decrease occurred at different rates. The earliest reduction in LDH-T activity in the no-exercise regimen was associated with a decrease in peak oxygen uptake of 12.3 percent. It is concluded that isometric (aerobic) muscular strength training appear to maintain skeletal muscle integrity better during bed rest than isotonic exercise training. Reduced hydrostatic pressure during bed rest, however, ultimately counteracts the effects of both moderate isometric and isotonic exercise training, and may result in decreased LDH-T activity.

  12. NASA'S Standard Measures During Bed Rest: Adaptations in the Cardiovascular System

    NASA Technical Reports Server (NTRS)

    Lee, Stuart M. C.; Feiveson, Alan H.; Martin, David S.; Cromwell, Roni L.; Platts, Steven H.; Stenger, Michael B.

    2016-01-01

    Bed rest is a well-accepted analog of space flight that has been used extensively to investigate physiological adaptations in a larger number of subjects in a shorter amount of time than can be studied with space flight and without the confounding effects associated with normal mission operations. However, comparison across studies of different bed rest durations, between sexes, and between various countermeasure protocols have been hampered by dissimilarities in bed rest conditions, measurement protocols, and testing schedules. To address these concerns, NASA instituted standard bed rest conditions and standard measures for all physiological disciplines participating in studies conducted at the Flight Analogs Research Unit (FARU) at the University of Texas-Medical Branch. Investigators for individual studies employed their own targeted study protocols to address specific hypothesis-driven questions, but standard measures tests were conducted within these studies on a non-interference basis to maximize data availability while reducing the need to implement multiple bed rest studies to understand the effects of a specific countermeasure. When possible, bed rest standard measures protocols were similar to tests nominally used for medically-required measures or research protocols conducted before and after Space Shuttle and International Space Station missions. Specifically, bed rest standard measures for the cardiovascular system implemented before, during, and after bed rest at the FARU included plasma volume (carbon monoxide rebreathing), cardiac mass and function (2D, 3D and Doppler echocardiography), and orthostatic tolerance testing (15- or 30-minutes of 80 degree head-up tilt). Results to-date indicate that when countermeasures are not employed, plasma volume decreases and the incidence of presyncope during head-up tilt is more frequent even after short-duration bed rest while reductions in cardiac function and mass are progressive as bed rest duration

  13. Effects of head-down-tilt bed rest on cerebral hemodynamics during orthostatic stress

    NASA Technical Reports Server (NTRS)

    Zhang, R.; Zuckerman, J. H.; Pawelczyk, J. A.; Levine, B. D.; Blomqvist, C. G. (Principal Investigator)

    1997-01-01

    Our aim was to determine whether the adaptation to simulated microgravity (microG) impairs regulation of cerebral blood flow (CBF) during orthostatic stress and contributes to orthostatic intolerance. Twelve healthy subjects (aged 24 +/- 5 yr) underwent 2 wk of -6 degrees head-down-tilt (HDT) bed rest to simulate hemodynamic changes that occur when humans are exposed to microG. CBF velocity in the middle cerebral artery (transcranial Doppler), blood pressure, cardiac output (acetylene rebreathing), and forearm blood flow were measured at each level of a ramped protocol of lower body negative pressure (LBNP; -15, -30, and -40 mmHg x 5 min, -50 mmHg x 3 min, then -10 mmHg every 3 min to presyncope) before and after bed rest. Orthostatic tolerance was assessed by using the cumulative stress index (CSI; mmHg x minutes) for the LBNP protocol. After bed rest, each individual's orthostatic tolerance was reduced, with the group CSI decreased by 24% associated with greater decreases in cardiac output and greater increases in systemic vascular resistance at each level of LBNP. Before bed rest, mean CBF velocity decreased by 14, 10, and 45% at -40 mmHg, -50 mmHg, and maximal LBNP, respectively. After bed rest, mean velocity decreased by 16% at -30 mmHg and by 21, 35, and 39% at -40 mmHg, -50 mmHg, and maximal LBNP, respectively. Compared with pre-bed rest, post-bed-rest mean velocity was less by 11, 10, and 21% at -30, -40, and -50 mmHg, respectively. However, there was no significant difference at maximal LBNP. We conclude that cerebral autoregulation during orthostatic stress is impaired by adaptation to simulated microG as evidenced by an earlier and greater fall in CBF velocity during LBNP. We speculate that impairment of cerebral autoregulation may contribute to the reduced orthostatic tolerance after bed rest.

  14. A technological evaluation of the Microsoft Kinect for automated behavioural mapping at bed rest.

    PubMed

    Gibson, Simon; McBride, Simon J; McClelland, Coen; Watson, Marcus

    2013-01-01

    Behavioural mapping (BM) is a long established method of structured observational study used to understand where patients are and what they are doing within a hospital setting. BM is prominent in stroke rehabilitation research, where that research indicates patients spend most of their time at bed rest. We evaluate the technical feasibility of using the Microsoft Kinect to automate patient physical activity classification at bed rest.

  15. Exercise Effects on the Course of Gray Matter Changes Over 70 Days of Bed Rest

    NASA Technical Reports Server (NTRS)

    Koppelmans, V.; Ploutz-Snyder, L.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Seidler, R. D.

    2014-01-01

    Long duration spaceflight affects posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes through direct effects on peripheral changes that result from reduced vestibular stimulation and body unloading. Effects of microgravity on sensorimotor function have been investigated on earth using bed rest studies. Long duration bed rest serves as a space-flight analogue because it mimics microgravity in body unloading and bodily fluid shifts. It has been hypothesized that the cephalad fluid shift that has been observed in microgravity could potentially affect central nervous system function and structure, and thereby indirectly affect sensorimotor or cognitive functioning. Preliminary results of one of our ongoing studies indeed showed that 70 days of long duration head down-tilt bed rest results in focal changes in gray matter volume from pre-bed rest to various time points during bed rest. These gray matter changes that could reflect fluid shifts as well as neuroplasticity were related to decrements in motor skills such as maintenance of equilibrium. In consideration of the health and performance of crewmembers both inand post-flight we are currently conducting a study that investigates the potential preventive effects of exercise on gray matter and motor performance changes that we observed over the course of bed rest. Numerous studies have shown beneficial effects of aerobic exercise on brain structure and cognitive performance in healthy and demented subjects over a large age range. We therefore hypothesized that an exercise intervention in bed rest could potentially mitigate or prevent the effects of bed rest on the central nervous system. Here we present preliminary outcomes of our study.

  16. Role of skin blood flow and sweating rate in exercise thermoregulation after bed rest

    NASA Technical Reports Server (NTRS)

    Lee, Stuart M C.; Williams, W. Jon; Schneider, Suzanne M.

    2002-01-01

    Two potential mechanisms, reduced skin blood flow (SBF) and sweating rate (SR), may be responsible for elevated intestinal temperature (T(in)) during exercise after bed rest and spaceflight. Seven men underwent 13 days of 6 degrees head-down bed rest. Pre- and post-bed rest, subjects completed supine submaximal cycle ergometry (20 min at 40% and 20 min at 65% of pre-bed rest supine peak exercise capacity) in a thermoneutral room. After bed rest, T(in) was elevated at rest (+0.31 +/- 0.12 degrees C) and at the end of exercise (+0.33 +/- 0.07 degrees C). Percent increase in SBF during exercise was less after bed rest (211 +/- 53 vs. 96 +/- 31%; P < or = 0.05), SBF/T(in) threshold was greater (37.09 +/- 0.16 vs. 37.33 +/- 0.13 degrees C; P < or = 0.05), and slope of SBF/T(in) tended to be reduced (536 +/- 184 vs. 201 +/- 46%/ degrees C; P = 0.08). SR/T(in) threshold was delayed (37.06 +/- 0.11 vs. 37.34 +/- 0.06 degrees C; P < or = 0.05), but the slope of SR/T(in) (3.45 +/- 1.22 vs. 2.58 +/- 0.71 mg x min-1 x cm-2 x degrees C-1) and total sweat loss (0.42 +/- 0.06 vs. 0.44 +/- 0.08 kg) were not changed. The higher resting and exercise T(in) and delayed onset of SBF and SR suggest a centrally mediated elevation in the thermoregulatory set point during bed rest exposure.

  17. Upright exercise or supine lower body negative pressure exercise maintains exercise responses after bed rest

    NASA Technical Reports Server (NTRS)

    Lee, S. M.; Bennett, B. S.; Hargens, A. R.; Watenpaugh, D. E.; Ballard, R. E.; Murthy, G.; Ford, S. R.; Fortney, S. M.

    1997-01-01

    Adaptation to bed rest or space flight is accompanied by an impaired ability to exercise in an upright position. We hypothesized that a daily, 30-min bout of intense, interval exercise in upright posture or supine against lower body negative pressure (LBNP) would maintain upright exercise heart rate and respiratory responses after bed rest. Twenty-four men (31 +/- 3 yr) underwent 5 d of 6 degree head-down tilt: eight performed no exercise (CON), eight performed upright treadmill exercise (UPex), and eight performed supine treadmill exercise against LBNP at -51.3 +/- 0.4 mm Hg (LBNPex). Submaximal treadmill exercise responses (56, 74, and 85% of VO2peak) were measured pre- and post-bed rest. In CON, submaximal heart rate, respiratory exchange ratio, and ventilation were significantly greater (P < or = 0.05) after bed rest. In UPex and LBNPex, submaximal exercise responses were similar pre- and post-bed rest. Our results indicate that a daily 30-min bout of intense, interval upright exercise training or supine exercise training against LBNP is sufficient to maintain upright exercise responses after 5 d of bed rest. These results may have important implications for the development of exercise countermeasures during space flight.

  18. Comparison of Ocular Outcomes in Two 14-Day Bed Rest Studies

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.; Zanello, S. B.; Yarbough, P. O.; Tabbi, G.; Vizzeri, G.

    2012-01-01

    Reports of astronauts' visual changes have raised concern about ocular health during long-duration spaceflight. Some of these findings include globe flattening with hyperopic shifts, choroidal folds, optic disc edema, retinal nerve fiber layer (RNFL) thickening, and cotton wool spots. While the etiology remains unknown, it is hypothesized that, in predisposed individuals, hypertension in the brain may follow cephalad fluid shifts during spaceflight. This possible mechanism of ocular changes may also apply to analogous cases of idiopathic intracranial hypertension (IIH) or pseudotumor cerebri on Earth patients. Head-down t ilt (HDT) bed rest is a spaceflight analog that induces cephalad fluid shifts. Previous studies of the HDT position demonstrated body fluid shifts associated with changes in intraocular pressure (IOP) but the conditions of bed rest varied among experiments, making it difficult to compare data and draw conclusions. For these reasons, vision evaluation of bed rest subjects was implemented for NASA bed rest studies since 2010, in an attempt to monitor vision health in subjects subjected to bed rest. Vision monitoring is thus currently performed in all NASA-conducted bed rest campaigns

  19. Evaluation of a Reverse Gradient Garment for prevention of bed-rest deconditioning

    NASA Technical Reports Server (NTRS)

    Sandler, H.; Dolkas, D.; Newsom, B.; Webb, P.; Annis, J.; Pace, N.; Grunbaum, B. W.

    1983-01-01

    A Reverse Gradient Garment (RGG) was used to intermittently induce venous pooling in the extremities of a magnitude similar to that seen in going from a lying to standing position during the course of a 15-d period of horizontal bed rest. Venous pooling failed to improve bed-rest-induced losses in +2.5 Gz and +3.0 Gz centrifugation tolerance or to prevent increased heart-rate responses to lower-body negative pressure (LBNP). Four subjects served as controls, four were treated. Tests during the 7-d recovery period showed fluid/electrolyte and body composition values to have returned to pre-bed-rest levels with continued depression of acceleration tolerance times (56% decreased at +2.5 Gz and 74% decreased at +3.0 Gz compared to pre-bed-rest levels) and exaggerated blood insulin response on glucose tolerance testing (blood insulin for treated group increased 95% at 1 h before bed rest and 465% during recovery). This study demonstrates that the physiologic changes after bed rest persist for significant periods of time. Acceleration tolerance time proved to be a sensitive test for the deconditioning process.

  20. Supine lower body negative pressure exercise during bed rest maintains upright exercise capacity.

    PubMed

    Watenpaugh, D E; Ballard, R E; Schneider, S M; Lee, S M; Ertl, A C; William, J M; Boda, W L; Hutchinson, K J; Hargens, A R

    2000-07-01

    Bed rest and spaceflight reduce exercise fitness. Supine lower body negative pressure (LBNP) treadmill exercise provides integrated cardiovascular and musculoskeletal stimulation similar to that imposed by upright exercise in Earth gravity. We hypothesized that 40 min of supine exercise per day in a LBNP chamber at 1.0-1.2 body wt (58 +/- 2 mmHg LBNP) maintains aerobic fitness and sprint speed during 15 days of 6 degrees head-down bed rest (simulated microgravity). Seven male subjects underwent two such bed-rest studies in random order: one as a control study (no exercise) and one with daily supine LBNP treadmill exercise. After controlled bed-rest, time to exhaustion during an upright treadmill exercise test decreased 10%, peak oxygen consumption during the test decreased 14%, and sprint speed decreased 16% (all P < 0.05). Supine LBNP exercise during bed rest maintained all the above variables at pre-bed-rest levels. Our findings support further evaluation of LBNP exercise as a countermeasure against long-term microgravity-induced deconditioning. PMID:10904055

  1. Cardiorespiratory responses to exercise after bed rest in men and women

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Bernauer, E. M.; Stremel, R. W.; Greenleaf, J. E.

    1977-01-01

    The purpose of this study was to compare cardiorespiratory responses of men and women to submaximal and maximal workloads before and after bed rest (BR). Fifteen male college students (19-23 yr) and eight female nurses (23-34 yr) underwent 14 d and 17 d, respectively, of bed rest. The maximal work capacity test was performed in the supine position on a bicycle ergometer just before and immediately after bed rest. Compared with pre-BR values, after bed rest the maximal ventilatory volume was essentially unchanged in the men (+1.8%) and women (+2.3%), but maximal heart rate was elevated from 185 to 193 b/min (+4.3%) in the men and from 181 to 187 b/min (3.3%) in the women. Mean corpuscular volume was unchanged in both groups pre- and post-bed rest. It is concluded that the proportional deterioration in maximal VO2 following prolonged bed rest was essentially the same in young men and women.

  2. The Effects of Long Duration Bed Rest as a Spaceflight Analogue on Resting State Sensorimotor Network Functional Connectivity and Neurocognitive Performance

    NASA Technical Reports Server (NTRS)

    Cassady, K.; Koppelmans, V.; Yuan, P.; Cooke, K.; De Dios, Y.; Stepanyan, V.; Szecsy, D.; Gadd, N.; Wood, S.; Reuter-Lorenz, P.; Castenada, R. Riascos; Kofman, I.; Bloomberg, J.; Mulavara, A.; Seidler, R.

    2015-01-01

    Long duration spaceflight has been associated with detrimental alterations in human sensorimotor systems and neurocognitive performance. Prolonged exposure to a head-down tilt position during long duration bed rest can resemble several effects of the microgravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The question of whether microgravity affects other central nervous system functions such as brain functional connectivity and its relationship with neurocognitive performance is largely unknown, but of potential importance to the health and performance of astronauts both during and post-flight. The aims of the present study are 1) to identify changes in sensorimotor resting state functional connectivity that occur with extended bed rest exposure, and to characterize their recovery time course; 2) to evaluate how these neural changes correlate with neurocognitive performance. Resting-state functional magnetic resonance imaging (rsfMRI) data were collected from 17 male participants. The data were acquired through the NASA bed rest facility, located at the University of Texas Medical Branch (Galveston, TX). Participants remained in bed with their heads tilted down six degrees below their feet for 70 consecutive days. RsfMRI data were obtained at seven time points: 7 and 12 days before bed rest; 7, 50, and 65 days during bed rest; and 7 and 12 days after bed rest. Functional connectivity magnetic resonance imaging (fcMRI) analysis was performed to measure the connectivity of sensorimotor networks in the brain before, during, and post-bed rest. We found a decrease in left putamen connectivity with the pre- and post-central gyri from pre bed rest to the last day in bed rest. In addition, vestibular cortex connectivity with the posterior cingulate cortex decreased from pre to post bed rest. Furthermore, connectivity between cerebellar right superior posterior fissure and other cerebellar regions decreased from

  3. Joint US/USSR study: Comparison of effects of horizontal and head-down bed rest

    NASA Technical Reports Server (NTRS)

    Sandler, Harold; Grigoriev, Anatoli I.

    1990-01-01

    An account is given of the results of the first joint U.S./U.S.S.R. bed rest study. The study was accomplished in two parts: A soviet part (May to June 1979) and an American part (July to August 1979). Both studies were conducted under identical conditions and provided a basis for comparison of physiologic reactions and standardizing procedures and methods. Each experiment consisted of three periods: 14 days of pre-bed rest control, 7 days of bed rest, and a 10 to 14 day recovery period. Ten males participated in each study, with five subjects experiencing horizontal bed rest and five subjects a -6 deg head-down body position. Biochemical and hormonal measurements were made of blood and urine, with particular attention to electrolyte metabolism and kidney function; cardio-pulmonary changes at rest and exercise; influence of Lower Body Negative Pressure (LBNP); and incremental exercise using a bicyle ergometer while supine and sitting. Expected moderate changes were noted to occur for various physiologic parameters. Clinical evidence pointed to the fact that head-down bed rest when compared to horizontal conditions more closely matched the conditions seen after manned spaceflight. For the most part, statistically significant differences between the two body positions were not observed.

  4. Induced venous pooling and cardiorespiratory responses to exercise after bed rest

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Sandler, H.; Webb, P.; Annis, J. F.

    1982-01-01

    Venous pooling induced by a specially constructed garment is investigated as a possible means for reversing the reduction in maximal oxygen uptake regularly observed following bed rest. Experiments involved a 15-day period of bed rest during which four healthy male subjects, while remaining recumbent in bed, received daily 210-min venous pooling treatments from a reverse gradient garment supplying counterpressure to the torso. Results of exercise testing indicate that while maximal oxygen uptake endurance time and plasma volume were reduced and maximal heart rate increased after bed rest in the control group, those parameters remained essentially unchanged for the group undergoing venous pooling treatment. Results demonstrate the importance of fluid shifts and venous pooling within the cardiovascular system in addition to physical activity to the maintenance of cardiovascular conditioning.

  5. Long-Duration Space Flight and Bed Rest Effects on Testosterone and Other Steroids

    PubMed Central

    Heer, Martina; Wang, Zuwei; Huntoon, Carolyn L.; Zwart, Sara R.

    2012-01-01

    Context: Limited data suggest that testosterone is decreased during space flight, which could contribute to bone and muscle loss. Objective: The main objective was to assess testosterone and hormone status in long- and short-duration space flight and bed rest environments and to determine relationships with other physiological systems, including bone and muscle. Design: Blood and urine samples were collected before, during, and after long-duration space flight. Samples were also collected before and after 12- to 14-d missions and from participants in 30- to 90-d bed rest studies. Setting: Space flight studies were conducted on the International Space Station and before and after Space Shuttle missions. Bed rest studies were conducted in a clinical research center setting. Data from Skylab missions are also presented. Participants: All of the participants were male, and they included 15 long-duration and nine short-duration mission crew members and 30 bed rest subjects. Main Outcome Measures: Serum total, free, and bioavailable testosterone were measured along with serum and urinary cortisol, serum dehydroepiandrosterone, dehydroepiandrosterone sulfate, and SHBG. Results: Total, free, and bioavailable testosterone was not changed during long-duration space flight but were decreased (P < 0.01) on landing day after these flights and after short-duration space flight. There were no changes in other hormones measured. Testosterone concentrations dropped before and soon after bed rest, but bed rest itself had no effect on testosterone. Conclusions: There was no evidence for decrements in testosterone during long-duration space flight or bed rest. PMID:22049169

  6. The effect of supplemental oral phosphate on the bone mineral changes during prolonged bed rest

    PubMed Central

    Hulley, Stephen B.; Vogel, John M.; Donaldson, Charles L.; Bayers, Jon H.; Friedman, Ronald J.; Rosen, Sheldon N.

    1971-01-01

    Five healthy young men were studied during 24-30 wk of continuous bed rest. During the first 12 wk of bed rest, untreated subjects increased calcium excretion in the urine by 109 mg/day and in the feces by 147 mg/day. The rate of total body calcium loss was 0.5-0.7% per month. Losses of central calcaneus mineral, assessed by gamma ray transmission scanning, occurred at a tenfold higher rate, whereas the mineral content of the radius did not change. Changes in phosphorus balance resembled the calcium pattern, and increased excretion of nitrogen and hydroxyproline also occurred during bed rest. Upon reambulation, the subjects' calcium balance became positive in 1 month and recovery of their calcaneus mineral was complete within 10-20 wk. Treatment with potassium phosphate supplements (1327 mg P/day) entirely prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. During the first 12 wk, calcium balance was slightly less negative (mean - 193 mg/day) than during bed rest without added phosphate (mean - 267 mg/day). This effect was not seen during the second 12 wk of bed rest. The patterns of magnesium excretion were similar to those of calcium. Fecal and urinary phosphorus excretions were doubled, and phosphorus balance became positive (+ 113 mg/day). Mineral loss from the central calcaneus was similar to that of untreated subjects. It is concluded that this form of phosphate supplementation reduces urinary calcium excretion but does not prevent bone loss during bed rest. PMID:5129304

  7. Vestibular and Somatosensory Covergence in Postural Equilibrium Control: Insights from Spaceflight and Bed Rest Studies

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Batson, C. D.; Buxton, R. E.; Feiveson, A. H.; Kofman, I. S.; Lee, S. M. C.; Miller, C. A.; Peters, B. T.; Phillips, T.; Platts, S. H.; Ploutz-Snyder, L. L.; Reschke, M. F.; Ryder, J. W.; Stenger, M. B.; Taylor, L. C.; Bloomberg, J. J.

    2014-01-01

    The goal of the Functional Task Test study is to determine the effects of space flight on functional tests that are representative of high priority exploration mission tasks and to identify the key underlying physiological factors that contribute to decrements in performance. We are currently conducting studies on both International Space Station (ISS) astronauts experiencing up to 6 months of microgravity and subjects experiencing 70 days of 6??head-down bed-rest as an analog for space flight. Bed-rest provides the opportunity for us to investigate the role of prolonged axial body unloading in isolation from the other physiological effects produced by exposure to the microgravity environment of space flight. This allows us to parse out the contribution of the body unloading somatosensory component on functional performance. Both ISS crewmembers and bed-rest subjects were tested using a protocol that evaluated functional performance along with tests of postural and locomotor control before and after space flight and bed-rest, respectively. Functional tests included ladder climbing, hatch opening, jump down, manual manipulation of objects and tool use, seat egress and obstacle avoidance, recovery from a fall, and object translation tasks. Astronauts were tested three times before flight, and on 1, 6, and 30 days after landing. Bed-rest subjects were tested three times before bed-rest and immediately after getting up from bed-rest as well as 1, 6, and 12 days after re-ambulation. A comparison of bed-rest and space flight data showed a significant concordance in performance changes across all functional tests. Tasks requiring a greater demand for dynamic control of postural equilibrium (i.e. fall recovery, seat egress/obstacle avoidance during walking, object translation, jump down) showed the greatest decrement in performance. Functional tests with reduced requirements for postural stability showed less reduction in performance. Results indicate that body unloading

  8. Body Unloading Associated with Space Flight and Bed-rest Impacts Functional Performance

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Ballard, K. L.; Batson, C. D.; Buxton, R. E.; Feiveson, A. H.; Kofman, I. S.; Lee, S. M. C.; Miller, C. A.; Mulavara, A. P.; Peters, B. T.; Phillips, T.; Platts, S. H.; Ploutz-Snyder, L. L.; Reschke, M. F.; Ryder, J. W.; Stenger, M. B.; Taylor, L. C.; Wood, S. J.

    2014-01-01

    The goal of the Functional Task Test study is to determine the effects of space flight on functional tests that are representative of high priority exploration mission tasks and to identify the key underlying physiological factors that contribute to decrements in performance. Ultimately this information will be used to assess performance risks and inform the design of countermeasures for exploration class missions. We are currently conducting studies on both ISS crewmembers and on subjects experiencing 70 days of 6 degrees head-down bed-rest as an analog for space flight. Bed-rest provides the opportunity for us to investigate the role of prolonged axial body unloading in isolation from the other physiological effects produced by exposure to the microgravity environment of space flight. This allows us to parse out the contribution of the body unloading component on functional performance. In this on-going study both ISS crewmembers and bed-rest subjects were tested using an interdisciplinary protocol that evaluated functional performance and related physiological changes before and after 6 months in space and 70 days of 6? head-down bed-rest, respectively. Functional tests included ladder climbing, hatch opening, jump down, manual manipulation of objects and tool use, seat egress and obstacle avoidance, recovery from a fall, and object translation tasks. Crewmembers were tested three times before flight, and on 1, 6 and 30 days after landing. Bed-rest subjects were tested three times before bed-rest and immediately after getting up from bed-rest as well as 1, 6 and 12 days after reambulation. A comparison of bed-rest and space flight data showed a significant concordance in performance changes across all functional tests. Tasks requiring a greater demand for dynamic control of postural equilibrium (i.e. fall recovery, seat egress/obstacle avoidance during walking, object translation, jump down) showed the greatest decrement in performance. Functional tests with

  9. Cardiovascular control and stabilization via inclination and mobilization during bed rest.

    PubMed

    Wieser, Martin; Gisler, Stefan; Sarabadani, Amirehsan; Ruest, Rafael M; Buetler, Lilith; Vallery, Heike; Klamroth-Marganska, Verena; Hund-Georgiadis, Margret; Felder, Morena; Schoenberger, Josef L; Gutknecht, Clemens; Riener, Robert

    2014-01-01

    Cardiovascular deconditioning has long been recognized as a characteristic of the physiological adaptation to long-term bed rest in patients. The process is thought to contribute to orthostatic intolerance and enhance secondary complications in a significant way. Mobilization is a cost-effective and simple method to maintain the cardiovascular parameters (i.e., blood pressure, heart rate) stable, counter orthostatic intolerance and reduce the risk of secondary problems in patients during long-term immobilization. The aim of this project is to control the cardiovascular parameters such as heart rate and blood pressure of bed rest patients via automated leg mobilization and body tilting. In a first step, a nonlinear model predictive control strategy was designed and evaluated on five healthy subjects and 11 bed rest patients. In a next step, a clinically feasible study was conducted on two patients. The mean values differed on average less than 1 bpm from the predetermined heart rate and less than 2.5 mmHg from the desired blood pressure values. These results of the feasibility study are promising, although heterogeneous disease etiologies and individual medication strongly influence the mechanically induced reactions. The long-term goal is an automation of the control of physiological signals and the mobilization of bed rest patients in an early phase of the rehabilitation process. Therefore, this new approach could help to strengthen the cardiovascular system and prevent secondary health problems arising from long-term bed rest. PMID:24096595

  10. Attenuation of the protein wasting associated with bed rest by branched-chain amino acids

    NASA Technical Reports Server (NTRS)

    Stein, T. P.; Schluter, M. D.; Leskiw, M. J.; Boden, G.

    1999-01-01

    Bed rest is generally accepted as being an appropriate ground-based model for human spaceflight. The objectives of this study were to test the hypothesis that increasing the amount of branched-chain amino acids (BCAAs) in the diet could attenuate the protein loss associated with bed rest. Nineteen healthy subjects were randomized into two groups according to diet. During the 6 d of bed rest, the diets were supplemented with either 30 mmol/d each of three non-essential amino acids, glycine, serine, and alanine (control group), or with 30 mmol/d each of the BCAAs, leucine, isoleucine, and valine (BCAA group). Nutrition was supplied as a commercially available defined formula diet at a rate of 1.3 x REE. Nitrogen (N) balance and urinary 3-MeH excretion were determined for the 6 d. In our results, the urine-based estimate of N balance was 22.2 +/- 14.4 (n = 9) mg N.kg-1.d-1 and 60.5 +/- 10.1 mg (n = 8) N.kg-1.d-1 for the control and BCAA-supplemented groups, respectively (P < 0.05). Urinary 3-MeH excretion was unchanged in both groups with bed rest. We conclude that BCAA supplementation attenuates the N loss during short-term bed rest.

  11. Zinc, copper, and nitrogen balances during bed rest and fluoride supplementation in healthy adult males

    NASA Technical Reports Server (NTRS)

    Krebs, J. M.; Schneider, V. S.; LeBlanc, A. D.

    1988-01-01

    The effects of bed rest and fluoride supplementation on zinc, copper, and nitrogen balances and Zn and Cu serum levels were measured in 15 healthy males. Subjects aged 19-54 y remained on a metabolic research ward for 10 wk. During weeks 1-5, subjects were ambulatory. During wks 6-10 they remained in continuous bed rest. During weeks 3-10 nine subjects received 10 or 20 mg F/d as sodium fluoride. Daily urine and weekly fecal composites were made and biweekly fasting blood samples were taken. Dietary intakes were 1.40 +/- 0.17 mg Cu/d (22.0 +/- 2.7 mumol Cu/d), 10.82 +/- 0.49 mg Zn/d (165.6 +/- 7.6 mumol Zn/d), and 14.27 +/- 0.23 g N/d (1019 +/- 16 mmol N/d). Bed rest increased urinary Zn and N excretions and fecal Zn excretions and decreased Zn balance (p less than 0.05) whereas Cu balance was unchanged. During bed rest, F supplementation increased Zn and N balances compared with untreated control subjects (p less than 0.05). These results are compatible with bone and muscle atrophy during bed rest and increased bone formation with F supplementation.

  12. Cardiovascular control and stabilization via inclination and mobilization during bed rest.

    PubMed

    Wieser, Martin; Gisler, Stefan; Sarabadani, Amirehsan; Ruest, Rafael M; Buetler, Lilith; Vallery, Heike; Klamroth-Marganska, Verena; Hund-Georgiadis, Margret; Felder, Morena; Schoenberger, Josef L; Gutknecht, Clemens; Riener, Robert

    2014-01-01

    Cardiovascular deconditioning has long been recognized as a characteristic of the physiological adaptation to long-term bed rest in patients. The process is thought to contribute to orthostatic intolerance and enhance secondary complications in a significant way. Mobilization is a cost-effective and simple method to maintain the cardiovascular parameters (i.e., blood pressure, heart rate) stable, counter orthostatic intolerance and reduce the risk of secondary problems in patients during long-term immobilization. The aim of this project is to control the cardiovascular parameters such as heart rate and blood pressure of bed rest patients via automated leg mobilization and body tilting. In a first step, a nonlinear model predictive control strategy was designed and evaluated on five healthy subjects and 11 bed rest patients. In a next step, a clinically feasible study was conducted on two patients. The mean values differed on average less than 1 bpm from the predetermined heart rate and less than 2.5 mmHg from the desired blood pressure values. These results of the feasibility study are promising, although heterogeneous disease etiologies and individual medication strongly influence the mechanically induced reactions. The long-term goal is an automation of the control of physiological signals and the mobilization of bed rest patients in an early phase of the rehabilitation process. Therefore, this new approach could help to strengthen the cardiovascular system and prevent secondary health problems arising from long-term bed rest.

  13. Systematic reviews of bed rest and advice to stay active for acute low back pain.

    PubMed Central

    Waddell, G; Feder, G; Lewis, M

    1997-01-01

    BACKGROUND: In the United Kingdom (UK), 9% of adults consult their doctor annually with back pain. The treatment recommendations are based on orthopaedic teaching, but the current management is causing increasing dissatisfaction. Many general practitioners (GPs) are confused about what constitutes effective advice. AIM: To review all randomized controlled trials of bed rest and of medical advice to stay active for acute back pain. METHOD: A systematic review based on a search of MEDLINE and EMBASE from 1966 to April 1996 with complete citation tracking for randomized controlled trials of bed rest or medical advice to stay active and continue ordinary daily activities. The inclusion criteria were: primary care setting, patients with low back pain of up to 3 months duration, and patient-centred outcomes (rate of recovery from the acute attack, relief of pain, restoration of function, satisfaction with treatment, days off work and return to work, development of chronic pain and disability, recurrent attacks, and further health care use). RESULTS: Ten trials of bed rest and eight trials of advice to stay active were identified. Consistent findings showed that bed rest is not an effective treatment for acute low back pain but may delay recovery. Advice to stay active and to continue ordinary activities results in a faster return to work, less chronic disability, and fewer recurrent problems. CONCLUSION: A simple but fundamental change from the traditional prescription of bed rest to positive advice about staying active could improve clinical outcomes and reduce the personal and social impact of back pain. PMID:9474831

  14. Changes in intervertebral disc cross-sectional area with bed rest and space flight

    NASA Technical Reports Server (NTRS)

    LeBlanc, A. D.; Evans, H. J.; Schneider, V. S.; Wendt, R. E. 3rd; Hedrick, T. D.

    1994-01-01

    STUDY DESIGN. We measured the cross-sectional area of the intervertebral discs of normal volunteers after an overnight rest; before, during, and after 5 or 17 weeks of bed rest; and before and after 8 days of weightlessness. OBJECTIVES. This study sought to determine the degree of expansion of the lumbar discs resulting from bed rest and space flight. SUMMARY OF BACKGROUND DATA. Weightlessness and bed rest, an analog for weightlessness, reduce the mechanical loading on the musculoskeletal system. When unloaded, intervertebral discs will expand, increasing the nutritional diffusion distance and altering the mechanical properties of the spine. METHODS. Magnetic resonance imaging was used to measure the cross-sectional area and transverse relaxation time (T2) of the intervertebral discs. RESULTS. Overnight or longer bed rest causes expansion of the disc area, which reaches an equilibrium value of about 22% (range 10-40%) above baseline within 4 days. Increases in disc area were associated with modest increases in disc T2. During bed rest, disc height increased approximately 1 mm, about one-half of previous estimates based on body height measurements. After 5 weeks of bed rest, disc area returned to baseline within a few days of ambulation, whereas after 17 weeks, disc area remained above baseline 6 weeks after reambulation. After 8 days of weightlessness, T2, disc area, and lumbar length were not significantly different from baseline values 24 hours after landing. CONCLUSIONS. Significant adaptive changes in the intervertebral discs can be expected during weightlessness. These changes, which are rapidly reversible after short-duration flights, may be an important factor during and after long-duration missions.

  15. Bed rest suppresses bioassayable growth hormone release in response to muscle activity

    NASA Technical Reports Server (NTRS)

    McCall, G. E.; Goulet, C.; Grindeland, R. E.; Hodgson, J. A.; Bigbee, A. J.; Edgerton, V. R.

    1997-01-01

    Hormonal responses to muscle activity were studied in eight men before (-13 or -12 and -8 or -7 days), during (2 or 3, 8 or 9, and 13 or 14 days) and after (+2 or +3 and +10 or +11 days) 17 days of bed rest. Muscle activity consisted of a series of unilateral isometric plantar flexions, including 4 maximal voluntary contractions (MVCs), 48 contractions at 30% MVC, and 12 contractions at 80% MVC, all performed at a 4:1-s work-to-rest ratio. Blood was collected before and immediately after muscle activity to measure plasma growth hormone by radioimmunoassay (IGH) and by bioassay (BGH) of tibia epiphyseal cartilage growth in hypophysectomized rats. Plasma IGH was unchanged by muscle activity before, during, or after bed rest. Before bed rest, muscle activity increased (P < 0.05) BGH by 66% at -13 or -12 days (2,146 +/- 192 to 3,565 +/- 197 microg/l) and by 92% at -8 or -7 days (2,162 +/- 159 to 4,161 +/- 204 microg/l). After 2 or 3 days of bed rest, there was no response of BGH to the muscle activity, a pattern that persisted through 8 or 9 days of bed rest. However, after 13 or 14 days of bed rest, plasma concentration of BGH was significantly lower after than before muscle activity (2,594 +/- 211 to 2,085 +/- 109 microg/l). After completion of bed rest, muscle activity increased BGH by 31% at 2 or 3 days (1,807 +/- 117 to 2,379 +/- 473 microg/l; P < 0.05), and by 10 or 11 days the BGH response was similar to that before bed rest (1,881 +/- 75 to 4,160 +/- 315 microg/l; P < 0.05). These data demonstrate that the ambulatory state of an individual can have a major impact on the release of BGH, but not IGH, in response to a single bout of muscle activity.

  16. Does 48 hours' bed rest influence the outcome of acute low back pain?

    PubMed Central

    Wilkinson, M J

    1995-01-01

    BACKGROUND. Bed rest is a traditional treatment for back pain, yet only in recent years has the therapeutic benefit of this been questioned. AIM. The aim of this pilot study was to ascertain whether or not 48 hours' bed rest had an effect on the outcome of acute low back pain. METHOD. The study was conducted as a randomized controlled trial to compare a prescription of 48 hours' strict bed rest with controls; the control subjects were encouraged to remain mobile and to have no daytime rest. Nine general practitioners from practices in the West Midlands recruited patients in the age range 16-60 years who presented with low back pain of less than seven days' duration, with or without pain radiation. The outcome measures assessed were: change in straight leg raise and lumbar flexion after seven days, Oswestry and Roland-Morris disability scores after seven days and 28 days, and time taken from work. RESULTS. Forty two patients were recruited: 20 were allocated to bed rest and 22 as controls. Compared with the bed rest group the control group had statistically better Roland-Morris scores at day seven (P < 0.05) but not at day 28. At day seven, there were no statistically significant differences between groups in straight leg raise or lumbar flexion measurements although the control group had a better mean lumbar flexion than the bed rest group. The improvement in disability scores at day seven compared with day one was similar for the two groups but more of the control group had fully recovered (defined as scores of one or zero on the Roland-Morris disability scale and five or less on the Oswestry disability scale) by day seven. Remaining mobile did not appear to cause any adverse effects. The number of days lost from work in both groups was equal. A large number of self-remedies and physical therapies were recorded by subjects from both groups. CONCLUSION. The results of this pilot study did not indicate whether bed rest or remaining mobile was superior for the

  17. Physiological responses to prolonged bed rest and fluid immersion in humans

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.

    1984-01-01

    For many centuries, physicians have used prolonged rest in bed and immersion in water in the treatment of ailments and disease. Both treatments have positive remedial effects. However, adverse physiological responses become evident when patients return to their normal daily activities. The present investigation is concerned with an analysis of the physiological changes during bed rest and the effects produced by water immersion. It is found that abrupt changes in body position related to bed rest cause acute changes in fluid compartment volumes. Attention is given to fluid shifts and body composition, renal function and diuresis, calcium and phosphorus metabolism, and orthostatic tolerance. In a discussion of water immersion, fluid shifts are considered along with cardiovascular-respiratory responses, renal function, and natriuretic and diuretic factors.

  18. Regional changes in muscle mass following 17 weeks of bed rest

    NASA Technical Reports Server (NTRS)

    Leblanc, Adrian D.; Schneider, Victor S.; Evans, Harlan J.; Pientok, Colette; Rowe, Roger; Spector, Elisabeth

    1992-01-01

    This work reports on the muscle loss and recovery after 17 wk of continuous bed rest and 8 wk of reambulation in eight normal male volunteers. Muscle changes were assessed by urinary levels of 3-methylhistidine (3-MeH), nitrogen balance, dual-photon absorptiometry (DPA), magnetic resonance imaging (MRI), and isokinetic muscle performance. The total body lean tissue loss during bed rest calculated from nitrogen balance was 3.9 +/- 2.1 kg. Although the total loss is minimal, DPA scans showed that nearly all of the lean tissue loss occurred in the lower limbs. Similarly, MRI muscle volume measurements showed greater percent loss in the limbs relative to the back muscles. MRI, DPA, and nitrogen balance suggest that muscle atrophy continued throughout bed rest with rapid recovery after reambulaton. Isokinetic muscle strength decreased significantly in the thigh and calf with no loss in the arms and with rapid recovery during reambulation.

  19. Pharmacologic counter measures minimizing post-space flight orthostatic intolerance. [bed rest, drug disposition, and physiological function

    NASA Technical Reports Server (NTRS)

    Harrison, D. C.; Kates, R.

    1982-01-01

    The effect of bed rest on drug disposition and physiological function was investigated as part of a project to determine the cardiovascular effects of space flight. One group of subjects was given doses of lidocane, penicillin-G, and ICG during a control period and following seven days of bed rest. Cardiac function was evaluated by echo-cardiography. Renal function was evaluated in a second group before and after several days of bed rest. Inulin, para-aminohippurate, and dextran clearances were studied. In the first group, the post-bed rest parameters were not statistically different from the pre-bed rest valves. In the second study, renal function did not change significantly after seven days of bed rest. Plans for future research are reviewed.

  20. Triiodothyronine increases calcium loss in a bed rest antigravity model for space flight.

    PubMed

    Smith, Steven R; Lovejoy, Jennifer C; Bray, George A; Rood, Jennifer; Most, Marlene M; Ryan, Donna H

    2008-12-01

    Bed rest has been used as a model to simulate the effects of space flight on bone metabolism. Thyroid hormones accelerate bone metabolism. Thus, supraphysiologic doses of this hormone might be used as a model to accelerate bone metabolism during bed rest and potentially simulate space flight. The objective of the study was to quantitate the changes in bone turnover after low doses of triiodothyronine (T(3)) added to short-term bed rest. Nine men and 5 women were restricted to bed rest for 28 days with their heads positioned 6 degrees below their feet. Subjects were randomly assigned to receive either placebo or oral T(3) at doses of 50 to 75 microg/d in a single-blind fashion. Calcium balance was measured over 5-day periods; and T(3), thyroxine, thyroid-stimulating hormone, immunoreactive parathyroid hormone, osteocalcin, bone alkaline phosphatase, and urinary deoxypyridinoline were measured weekly. Triiodothyronine increased 2-fold in the men and 5-fold in the women during treatment, suppressing both thyroxine and thyroid-stimulating hormone. Calcium balance was negative by 300 to 400 mg/d in the T(3)-treated volunteers, primarily because of the increased fecal loss that was not present in the placebo group. Urinary deoxypyridinoline to creatinine ratio, a marker of bone resorption, increased 60% in the placebo group during bed rest, but more than doubled in the T(3)-treated subjects (P < .01), suggesting that bone resorption was enhanced by treatment with T(3). Changes in serum osteocalcin and bone-specific alkaline phosphatase, markers of bone formation, were similar in T(3)- and placebo-treated subjects. Triiodothyronine increases bone resorption and fecal calcium loss in subjects at bed rest.

  1. The Metabolic Cost of a High Intensity Exercise Program During Bed Rest

    NASA Technical Reports Server (NTRS)

    Hackney, Kyle; Everett, Meghan; Guined, Jamie; Cunningham, Daid

    2012-01-01

    Background: Given that disuse-related skeletal muscle atrophy may be exacerbated by an imbalance between energy intake and output, the amount of energy required to complete exercise countermeasures is an important consideration in the well being of subject health during bed rest and spaceflight. Objective: To evaluate the energy cost of a high intensity exercise program performed during short duration bed rest. Methods: 9 subjects (8 male and 1 female; 34.5 +/- 8.2 years) underwent 14 days of bed rest and exercise countermeasures. Exercise energy expenditure and excess post exercise oxygen consumption (EPOC) were collected once in each of 5 different exercise protocols (30 second, 2 minute and 4 minute intervals, continuous aerobic and a variety of resistance exercises) during bed rest. Body mass, basal metabolic rate (BMR), upper and lower leg muscle, subcutaneous, and intramuscular adipose tissue (IMAT) volumes were assessed before and at the end of bed rest. Results: There were no significant differences in body mass (pre: 75.1 +/- 10.5 kg; post: 75.2 +/- 10.1 kg), BMR (pre: 1649 +/- 216 kcal; post: 1657 +/- 177 kcal), muscle subcutaneous, or IMAT volumes (Table 2) after 14 days of bed rest and exercise. Body mass was maintained with an average daily intake of 2710 +/- 262 kcal (36.2 +/- 2.1 kcal/kg/day), while average daily energy expenditure was 2579 +/-311 kcal (34.5 +/- 3.6 kcal/kg/day). Exercise energy expenditure was significantly greater as a result of continuous aerobic exercise than all other exercise protocols.

  2. Fluid and salt supplementation effect on body hydration and electrolyte homeostasis during bed rest and ambulation

    NASA Astrophysics Data System (ADS)

    Zorbas, Yan G.; Kakurin, Vassily J.; Kuznetsov, Nikolai A.; Yarullin, Vladimir L.

    2002-06-01

    Bed rest (BR) induces significant urinary and blood electrolyte changes, but little is known about the effect of fluid and salt supplements (FSS) on catabolism, hydration and electrolytes. The aim was to measure the effect of FSS on catabolism, body hydration and electrolytes during BR. Studies were done during 7 days of a pre-bed rest period and during 30 days of a rigorous bed rest period. Thirty male athletes aged, 24.6±7.6 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS groups were kept under a rigorous bed rest regime for 30 days. The SBRS daily took 30 ml water per kg body weight and 0.1 sodium chloride per kg body weight. Plasma sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) levels, urinary Na, K, Ca and Mg excretion, plasma osmolality, plasma protein level, whole blood hemoglobin (Hb) and hematocrit (Hct) level increased significantly ( p≤0.05), while plasma volume (PV), body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly ( p≤0.05) in the UBRS group when compared with the SBRS and UACS groups. In contrast, plasma and urinary electrolytes, osmolality, protein level, whole blood Hct and Hb level decreased significantly ( p≤0.05), while PV, fluid intake, body weight and peak oxygen uptake increased significantly ( p≤0.05) in the SBRS group when compared with the UBRS group. The measured parameters did not change significantly in the UACS group when compared with their baseline control values. The data indicate that FSS stabilizes electrolytes and body hydration during BR, while BR alone induces significant changes in electrolytes and body hydration. We conclude that FSS may be used to prevent catabolism and normalize body hydration status and electrolyte values during BR.

  3. An overview of the issues: physiological effects of bed rest and restricted physical activity

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Bloomfield, S. A.; Greenleaf, J. E.

    1997-01-01

    Reduction of exercise capacity with confinement to bed rest is well recognized. Underlying physiological mechanisms include dramatic reductions in maximal stroke volume, cardiac output, and oxygen uptake. However, bed rest by itself does not appear to contribute to cardiac dysfunction. Increased muscle fatigue is associated with reduced muscle blood flow, red cell volume, capillarization and oxidative enzymes. Loss of muscle mass and bone density may be reflected by reduced muscle strength and higher risk for injury to bones and joints. The resultant deconditioning caused by bed rest can be independent of the primary disease and physically debilitating in patients who attempt to reambulate to normal active living and working. A challenge to clinicians and health care specialists has been the identification of appropriate and effective methods to restore physical capacity of patients during or after restricted physical activity associated with prolonged bed rest. The examination of physiological responses to bed rest deconditioning and exercise training in healthy subjects has provided significant information to develop effective rehabilitation treatments. The successful application of acute exercise to enhance orthostatic stability, daily endurance exercise to maintain aerobic capacity, or specific resistance exercises to maintain musculoskeletal integrity rather than the use of surgical, pharmacological, and other medical treatments for clinical conditions has been enhanced by investigation and understanding of underlying mechanisms that distinguish physical deconditioning from the disease. This symposium presents an overview of cardiovascular and musculoskeletal deconditioning associated with reduced physical work capacity following prolonged bed rest and exercise training regimens that have proven successful in ameliorating or reversing these adverse effects.

  4. Improvements and validation of the erythropoiesis control model for bed rest simulation

    NASA Technical Reports Server (NTRS)

    Leonard, J. I.

    1977-01-01

    The most significant improvement in the model is the explicit formulation of separate elements representing erythropoietin production and red cell production. Other modifications include bone marrow time-delays, capability to shift oxyhemoglobin affinity and an algorithm for entering experimental data as time-varying driving functions. An area of model development is suggested by applying the model to simulating onset, diagnosis and treatment of a hematologic disorder. Recommendations for further improvements in the model and suggestions for experimental application are also discussed. A detailed analysis of the hematologic response to bed rest including simulation of the recent Baylor Medical College bed rest studies is also presented.

  5. Behavioral and Psychological Issues in Long Duration Head-down Bed Rest

    NASA Technical Reports Server (NTRS)

    Seaton, Kimberly A.; Bowie, Kendra; Sipes, Walter A.

    2008-01-01

    Behavioral health services, similar to those offered to the U.S. astronauts who complete six-month missions on board the International Space Station, were provided to 13 long-duration head-down bed rest participants. Issues in psychological screening, selection, and support are discussed as they relate to other isolated and confined environments. Psychological services offered to participants are described, and challenges in subject selection and retention are discussed. Psychological support and training provided to both subjects and study personnel have successfully improved the well-being of study participants. Behavioral health services are indispensable to long-duration head-down tilt bed rest studies.

  6. Body water compartments during bed rest: Evaluation of analytical methods

    NASA Technical Reports Server (NTRS)

    Young, H. L.; Juhos, L.; Castle, B. L.; Yusken, J.; Greenleaf, J. E.

    1973-01-01

    Nine healthy young men were studied to determine the reproducibility and interchangeability of the use of radio-iodinated human serum albumin and Evans Blue dye for estimating plasma volume, sodium bromide for extracellular fluid volume, and deuterium oxide for total body water volume. All subjects were tested in a semibasal condition and allowed to rest for at least 30 min. after arriving at the laboratory. The results indicate that there was uniform distribution of I131 and Evans Blue dye 10 min. after injection and of NaBr and D2O 3 hours after oral ingestion; the buildup of residual tracer did not interfere appreciably with the measurement of either or Evans Blue spaces when they are administered at equal intervals, and the buildup of background tracer after ingestion of NaBr and D2O once per week for three consecutive weeks did not affect the accuracy of the measurement. It was found that I131 and Evans Blue may be used interchangeably for estimating plasma volume; for estimating bromide and D2O spaces, one 3-hour equilibrium blood sample gives results similar to the extrapolation of multiple samples.

  7. Prevention of disuse osteoporosis: Effect of sodium fluoride during five weeks of bed rest

    NASA Technical Reports Server (NTRS)

    Schneider, Victor S.

    1987-01-01

    An attempt was made to modify factors which promote disuse osteoporosis and thereby prevent it from occurring. Since fluoride is currently used to enhance bone formation in the treatment of low turnover osteoporosis, it was hypothesized that if the fluoride ion was available over a long period of time that it would slow the demonstrated loss of calcium by inhibiting bone resorption and enhancing bone formation. This study was used to determine whether oral medication with sodium F will modify or prevent 5 weeks of bed rest induced disuse osteoporosis, to determine the longitudinal effects of 5 weeks of bed rest on PTH, CT and calcitriol, to measure muscle volume changes and metabolic activity by magnetic resonance imaging and magnetic resonance spectroscopy during prolonged bed rest, to measure changes in peak muscle strength and fatigability, and to measure bone turnover in bone biopsies. Subjects were studied during 1 week of equilibration, 4 weeks of control ambulation, 5 weeks of bed rest, and 1 week of reambulation.

  8. Physiological responses to prolonged bed rest in humans: A compendium of research, 1981-1988

    NASA Technical Reports Server (NTRS)

    Luu, Phuong B.; Ortiz, Vanessa; Barnes, Paul R.; Greenleaf, John E.

    1990-01-01

    Clinical observations and results form more basic studies that help to elucidate the physiological mechanisms of the adaptation of humans to prolonged bed rest. If the authors' abstract or summary was appropriate, it was included. In some cases a more detailed synopsis was provided under the subheadings of purpose, methods, results, and conclusions.

  9. Zinc and copper balances in healthy adult males during and after 17 wk of bed rest

    NASA Technical Reports Server (NTRS)

    Krebs, J. M.; Schneider, V. S.; LeBlanc, A. D.; Kuo, M. C.; Spector, E.; Lane, H. W.

    1993-01-01

    The effects of long-term bed rest on zinc and copper balances were measured in seven healthy men. Volunteers aged 22-54 y (mean +/- SD, 34 +/- 12 y), 168-185 cm in height (173 +/- 5 cm), and 64-86 kg in weight (74 +/- 9 kg) remained on a metabolic ward for 29 wk. Subjects were ambulatory during weeks 1-5, remained in continuous bed rest for weeks 6-22, and were reambulated during weeks 23-29. Copper and zinc were measured in weekly urine and fecal composites. Dietary intakes provided (mean +/- SD) 19.2 +/- 1.2 mumol Cu (1.22 +/- 0.08 mg), 211 +/- 11 mumol Zn (13.81 +/- 0.72 mg), 25.2 +/- 1.2 mmol Ca (1011 +/- 46 mg), 1086 +/- 46 mmol N (15.21 +/- 0.65 g), and 48.1 +/- 1.4 mmol K (1489 +/- 44 mg)/d. Bed rest increased fecal zinc excretion and decreased zinc balance, whereas copper balance was unchanged. Reambulation decreased fecal zinc excretion and increased both zinc and copper balances. These results suggest that during long-term bed rest or space flight, individuals will lose total body zinc and will retain more zinc and copper when they reambulate.

  10. Countermeasures and Functional Testing in Head-Down Tilt Bed Rest (CFT 70)

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.

    2013-01-01

    This 70-day bed rest campaign was comprised of 6 integrated studies and conducted at the NASA Flight Analogs Research Unit (FARU). The FARU is located at the University of Texas Medical Branch, Galveston, Texas and is a satellite unit of the Institute for Translational Sciences - Clinical Research Center. This presentation will describe the FARU, discuss the utility of the bed rest platform for use in these studies, and introduce the studies that participated in the CFT 70 bed rest campaign. Information in this presentation will serve as the background for subsequent talks from each individual study. Individual study presentations will discuss preliminary results from completed subjects. Studies included in CFT70 were: ? Physiological Factors Contributing to Post Flight Changes in Functional Performance. J. Bloomberg, NASA ? Integrated Resistance and Aerobic Training Study. L. Ploutz-Snyder, USRA ? Testosterone Supplementation as a Countermeasure Against Musculoskeletal losses during Space Exploration. R. Urban, University of Texas Medical Branch ? Effects of Retronasal Smelling, Variety and Choice on Appetite & Satiety. J. Hunter, Cornell University ? AD ASTRA: Automated Detection of Attitudes and States through Transaction Recordings Analysis. C. Miller, Smart Information Flow Technologies, LLC ? Bed Rest as a Spaceflight Analog to Study Neuro-cognitive Changes: Extent, Longevity, and Neural Bases. R. Seidler, University of Michigan

  11. Biochemical and hormonal changes in endurance trained volunteers during and after exposure to bed rest and chronic hyperhydration

    NASA Astrophysics Data System (ADS)

    Zorbas, Y. G.; Naexu, K. A.; Yaroshenko, Y. N.

    2000-04-01

    The objective of this investigation was to assess the effect of a daily intake of fluid and salt supplementation on biochemical and hormonal changes in endurance trained volunteers aged 19-24 yrs during 30-day bed rest and during 15 days of post bed rest period. The studies were performed on 30 long distance runners aged 19-24 yrs who had a peak oxygen uptake of 66 ml/kg/min and had taken 14.5 km/day on average prior to their participation in the study. The volunteers were divided into three groups: the volunteers in the first group were under normal ambulatory conditions (control subjects); the second group subjected to bed rest alone unsupplemented (bed rested volunteers); the third group was submitted to bed rest and consumed daily 30 ml water/kg bodyweight and 0.1 g of sodium chloride (NaCl)/kg body weight (supplemented bed rested volunteers). The second and third groups of volunteers were kept under a rigorous bed rest regime for 30 days. During the pre bed rest period of 15 days, during the bed rest period of 30 days and during the post bed rest period of 15 days cyclic adenosine monophosphate, cyclic guanosine monophosphate, prostaglandins of pressor, prostaglandins depressor groups, renin activity in plasma and aldosterone in plasma and in urine were determined. We found that in bed rested volunteers without fluid and salt supplementation intake plasma renin activity and aldosterone in plasma and urine continued to increase during the bed rest period as plasma volume decreased. Moreover, in this group, cyclic nucleotides measured as an indicator of adrenosympathetic system activity increased and prostaglandins as local vasoactive substances decreased during the bed rest period. These variables returned toward the baselines in the post bed rest period as plasma volume deficit was restituted. On the other hand, the hormonal levels in the other two groups remained rather constant during the experimental period. We concluded that daily intake of fluid and salt

  12. Biochemical and hemodynamic changes in normal subjects during acute and rigorous bed rest and ambulation

    NASA Astrophysics Data System (ADS)

    Zorbas, Yan G.; Kakurin, Vassily J.; Afonin, Victor B.; Yarullin, Vladimir L.

    2002-06-01

    Rigorous bed rest (RBR) induces significant biochemical and circulatory changes. However, little is known about acute rigorous bed rest (ARBR). Measuring biochemical and circulatory variables during ARBR and RBR the aim of this study was to establish the significance of ARBR effect. Studies were done during 3 days of a pre-bed rest (BR) period and during 7 days of ARBR and RBR period. Thirty normal male individuals aged, 24.1±6.3 years were chosen as subjects. They were divided equally into three groups: 10 subjects placed under active control conditions served as unrestricted ambulatory control subjects (UACS), 10 subjects submitted to an acute rigorous bed rest served as acute rigorous bed rested subjects (ARBRS) and 10 subjects submitted to a rigorous bed rest served as rigorous bed rested subjects (RBRS). The UACS were maintained under an average running distance of 9.7 km day -1. For the ARBR effect simulation, ARBRS were submitted abruptly to BR for 7 days. They did not have any prior knowledge of the exact date and time when they would be asked to confine to RBR. For the RBR effect simulation, RBRS were subjected to BR for 7 days on a predetermined date and time known to them right away from the start of the study. Plasma renin activity (PRA), plasma cortisol (PC), plasma aldosterone (PA), plasma and urinary sodium (Na) and potassium (K) levels, heart rate (HR), cardiac output (CO), and arterial blood pressure (ABP) increased significantly, and urinary aldosterone (UA), stroke volume (SV) and plasma volume (PV) decreased significantly ( p<0.05) in ARBRS and RBRS as compared with their pre-BR values and the values in UACS. Electrolyte, hormonal and hemodynamic responses were significantly ( p<0.05) greater and occurred significantly faster ( p<0.05) during ARBR than RBR. Parameters change insignificantly ( p>0.05) in UACS compared with pre-BR control values. It was concluded that, the more abruptly muscular activity is restricted in experimental subjects

  13. Artificial Gravity as a Multi-System Countermeasure to Bed Rest Deconditioning: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Warren, L. E.; Paloski, William H.; Young, L. R.

    2006-01-01

    Artificial gravity paradigms may offer effective, efficient, multi-system protection from the untoward effects of adaptation to the microgravity of space or the hypogravity of planetary surfaces. Intermittent artificial gravity (AG) produced by a horizontal short-radius centrifuge (SRC) has recently been utilized on human test subjects deconditioned by bed rest. This presentation will review preliminary results of a 41 day study conducted at the University of Texas Medical Branch, Galveston, TX bed rest facility. During the first eleven days of the protocol, subjects were ambulatory, but confined to the facility. They began a carefully controlled diet, and participated in multiple baseline tests of bone, muscle, cardiovascular, sensory-motor, immunological, and psychological function. On the twelfth day, subjects entered the bed rest phase of the study, during which they were confined to strict 6deg head down tilt bed rest for 21 days. Beginning 24 hrs into this period, treatment subjects received one hour daily exposures to artificial gravity which was produced by spinning the subjects on a 3.0 m radius SRC. They were oriented radially in the supine position so that the centrifugal force was aligned with their long body axis, and while spinning, they "stood" on a force plate, supporting the centrifugal loading (2.5 g at the feet, 1.0 g at the heart). The subject station allowed free translation over approximately 10 cm to ensure full loading of the lower extremities and to allow for anti-orthostatic muscle contractions. Control subjects were positioned on the centrifuge but did not spin. Following the bed rest phase, subjects were allowed to ambulate again, but remained within the facility for an additional 9 days and participated in multiple follow-up tests of physiological function.

  14. Plasma volume and biochemical changes in athletes during bed rest chronic hyperhydration

    NASA Astrophysics Data System (ADS)

    Zorbas, Yan G.; Yarullin, Vladimir L.; Denogradov, Sergei D.; Afonin, Victor B.

    Daily fluid and salt supplements (FSS) may be used to reduce plasma biochemical changes during bed rest (BR). The aim of this study was to evaluate the effect of a daily intake of FSS on plasma volume (PV) and biochemical changes during BR. Studies were done during a pre BR period of 15 days and during a BR period of 30 days. Thirty male athletes aged 22-26 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS were kept under a rigorous bed rest regime for 30 days. The SBRS took 26 ml water/kg body weight and 0.1 g sodium chloride/kg body weight daily. PV, protein, albumin, sodium (Na), Chloride (Cl), potassium (K), osmolality, creatinine, glucose, and whole blood haematocrit (Hct) and haemoglobin (Hb) concentrations were measured. PV increased significantly ( P≤0.01) while plasma protein, albumin, Na, Cl, K, glucose, creatinine, osmolality, and whole blood Hb and Hct concentration decreased significantly ( P≤0.01) in the SBRS group when compared with the UBRS group. By contrast, PV decreased significantly ( P≤0.01), while plasma protein, albumin, Na, Cl, K, glucose, creatinine, osmolality and whole blood Hct and Hb concentration increased significantly ( P≤0.01) in the UBRS group when compared with the SBRS and UACS groups. The measured parameters did not change significantly in the UACS group when compared with the baseline control values. It was concluded that a daily intake of FSS may be used to attenuate PV losses and biochemical changes in endurance trained athletes during bed rest.

  15. Effect of acute hypercapnia during 10-day hypoxic bed rest on posterior eye structures.

    PubMed

    Jaki Mekjavic, Polona; Lenassi, Eva; Eiken, Ola; Mekjavic, Igor B

    2016-05-15

    To gain insights into microgravity-induced ophthalmic changes (microgravity ocular syndrome), and as part of a project investigating effects of future planetary habitats, we investigated the effect of acute hypercapnia following 10-day bed rest and hypoxia on posterior eye structures. Female subjects (N = 7) completed three 10-day experimental interventions: 1) normoxic bed rest [NBR; partial pressure of inspired O2 (PiO2 ) = 132.9 ± 0.3 Torr]; 2) hypoxic ambulatory confinement (HAMB; PiO2 = 90.4 ± 0.3 Torr); and 3) hypoxic bed rest (HBR; n = 12; PiO2 = 90.4 ± 0.3 Torr). Before and on the last day of each intervention, optical coherence tomography (OCT) of the optic disk was performed, and the thicknesses of the retinal nerve fiber layer (RNFL), retina, and choroid were measured. OCT examinations were conducted with the subjects breathing the prevailing normocapnic breathing mixture (either normoxic or hypoxic) and then following a 10-min period of breathing the same gas mixture, but with the addition of 1% CO2 Choroidal thickness was greater during both bed-rest conditions (NBR and HBR) compared with the ambulatory (HAMB) condition (ANOVA, P < 0.001). Increases in RNFL thickness compared with baseline were observed in the hypoxic trials (HBR, P < 0.001; and HAMB, P = 0.021), but not the normoxic trial (NBR). A further increase in RNFL thickness (P = 0.019) was observed after the 10-min hypercapnic trial in the NBR condition only. The fact that choroidal thickness was not affected by Po2 or Pco2, but increased by bed rest, suggests a hydrostatic rather than a vasoactive effect. The increments in RNFL thickness were most likely associated with local hypoxia and hypercapnia-induced dilatation of the retinal blood vessels. PMID:27013607

  16. Towards a 90-Day Monthly Storm Outlook for Alaska

    NASA Astrophysics Data System (ADS)

    Partain, J. L.

    2011-12-01

    In all seasons, storms represent high-impact weather events in Alaska. Alaska's extensive coastline makes the region especially vulnerable to coastal flooding and erosion, particularly where a protective sea ice buffer is absent. There exists a major need for an expanded temporal range of storm outlooks to enable proactive responses by coastal communities and the various industries noted above. The expansion envisioned here is to the 90-day range. The NOAA Climate Prediction Center's (CPC) Storm Tracks website presently includes summaries of storm tracks and accumulated precipitation for the past 10-, 30- and 90-day periods, together with Week-1 and Week-2 forecast storm tracks from the Global Forecast System's (GFS) operational run and the GFS ensemble. Given the limits of deterministic predictability, we will extend the window of the storm outlook to 90 days by drawing upon the present and CPC-predicted states of ENSO, the Pacific Decadal Oscillation, and the Arctic Oscillation -- three large-scale modes of variability known to affect Alaska. In order to link the large-scale modes of variability to storm probabilities in various Alaskan sub-regions, we will explore the use of composites and analog years based on the states of the major teleconnection modes. This presentation will include an end-to-end plan for the development and testing of this product.

  17. Immune Response and Function: Exercise Conditioning Versus Bed-Rest and Spaceflight Deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Jackson, C. G. R.; Lawless, D.

    1994-01-01

    Immune responses measured at rest immediately or some hours after exercise training (some with and some without increase in maximal oxygen uptake) gave variable and sometimes conflicting results; therefore, no general conclusions can be drawn. On the other hand, most immune responses were either unchanged (immunoglobulin, T cells, CD4+, and natural killer activity) or decreased (blood properdin, neutrophil phagocytic activity, salivary lysozymes, brain immunoglobulin A and G, and liver B lymphocytes and phytohemagglutinin activity) during prolonged bed rest. Some data suggested that exercise training during bed rest may partially ameliorate the decreased functioning of the immune system. Exercise and change in body position, especially during prolonged bed rest with plasma fluid shifts and diuresis, may induce a change in plasma protein concentration and content, which can influence drug metabolism as well as immune function. Leukocytosis, accompanied by lymphopenia and a depressed lymphocyte response, occurs in astronauts on return to Earth from spaceflight; recovery may depend on time of exposure to microgravity. It is clear that the effect of drugs and exercise used as countermeasures for microgravity deconditioning should be evaluated for their effect on an astronaut's immune system to assure optimal health and performance on long-duration space missions.

  18. Prospective Evaluation of the Optimal Duration of Bed Rest After Vascular Interventions Using a 3-French Introducer Sheath

    SciTech Connect

    Aramaki, Takeshi Moriguchi, Michihisa Bekku, Emima; Endo, Masahiro Asakura, Koiku; Boku, Narikazu; Yoshimura, Kenichi

    2015-02-15

    PurposeTo assess optimal bed-rest duration after vascular intervention by way of the common femoral artery using 3F introducer sheaths.Materials and MethodsEligibility criteria for this single-center, prospective study included clinically necessary angiography, no coagulopathy or anticoagulant therapy, no hypersensitivity to contrast medium, age >20 years, and written, informed consent. Enrolled patients were assigned to one of three groups (105/group) with the duration of bed rest deceased sequentially. A sheath was inserted by way of the common femoral artery using the Seldinger technique. The first group (level 1) received 3 h of bed rest after the vascular intervention. If no bleeding or hematomas developed, the next group (level 2) received 2.5 h of bed rest. If still no bleeding or hematomas developed, the final group (level 3) received 2 h of bed rest. If any patient had bleeding or hematomas after bed rest, the study was terminated, and the bed rest of the preceding level was considered the optimal duration.ResultsA total of 105 patients were enrolled at level 1 between November 2010 and September 2011. Eight patients were excluded from analysis because cessation of bed rest was delayed. None of the remaining subjects experienced postoperative bleeding; therefore, patient enrollment at level 2 began in September 2011. However, puncture site bleeding occurred in the 52nd patient immediately after cessation of bed rest, necessitating study termination.ConclusionTo prevent bleeding, at least 3 h of postoperative bed rest is recommended for patients undergoing angiography using 3F sheaths.

  19. Gender Differences in Isokinetic Strength after 60 and 90 d Bed Rest

    NASA Technical Reports Server (NTRS)

    English, K. L.; Ploutz-Snyder, R. J.; Cromwell, R. L.; Ploutz-Snyder, L. L.

    2010-01-01

    Recent reports suggest that changes in muscle strength following disuse may differ between males and females. PURPOSE: To examine potential gender differences in strength changes following 60 and 90 d of experimental bed rest. METHODS: Isokinetic extensor and flexor strength of the knee (60deg and 180deg/s, concentric only), ankle (30deg/s, concentric and eccentric), and trunk (60deg/s, concentric only) were measured following 60 d (males: n=4, 34.5+/-9.6 y; females: n=4, 35.5+/-8.2 y) and 90 d (males: n=10, 31.4+/-4.8 y; females: n=5, 37.6+/-9.9 y) of 6-degree head-down-tilt bed rest (BR; N=23). Subjects were fed a controlled diet (55%/15%/ 30%, CHO/PRO/FAT) that maintained body weight within 3% of the weight recorded on Day 3 of bed rest. After a familiarization session, testing was conducted 6 d before BR and 2 d after BR completion. Peak torque and total work were calculated for the tests performed. To allow us to combine data from both 60- and 90-d subjects, we used a mixed-model statistical analysis in which time and gender were fixed effects and bed rest duration was a random effect. Log-transformations of strength measures were utilized when necessary in order to meet statistical assumptions. RESULTS: Main effects were seen for both time and gender (p<0.05), showing decreased strength in response to bed rest for both males and females, and males stronger than females for most strength measures. Only one interaction effect was observed: females exhibited a greater loss of trunk extensor peak torque at 60 d versus pre-BR, relative to males (p=0.004). CONCLUSION: Sixty and 90 d of BR induced significant losses in isokinetic muscle strength of the locomotor and postural muscles of the knee, ankle, and trunk. Although males were stronger than females for most of the strength measures that we examined, only changes in trunk extensor peak torque were greater for females than males at day 60 of bed rest

  20. Bone Loss in Space: Shuttle/MIR Experience and Bed Rest Countermeasure Program

    NASA Technical Reports Server (NTRS)

    Shackelford, L. C.; LeBlanc, A.; Feiveson, A.; Oganov, V.

    1999-01-01

    Loss of bone mineral during space flight was documented in the 1970's Skylab missions. The USSR space program made similar observations in the 1980's. The Institute of Biomedical Problems in Moscow and NASA JSC in 1989 began to collect pre- and post-flight bone mineral density (BMD) using Hologic QDR 1000 DEXA scanners transferred from JSC to Moscow and Star City. DEXA whole body, hip, and lumbar spine scans were performed prior to and during the first week after return from 4- to 6-month missions (plus one 8-month mission and one 14- month mission) on the Mir space station. These data documented the extent and regional nature of bone loss during long duration space flight. Of the 18 cosmonauts participating in this study between 1990 and 1995, seven flew two missions. BMD scans prior to the second flight compared to the first mission preflight scans indicated that recovery was possibly delayed or incomplete. Because of these findings, NASA and IBMP initiated the study "Bone Mineral Loss and Recovery After Shuttle/Mir Flights" in 1995 to evaluate bone recovery during a 3-year post-flight period. All of the 14 participants thus far evaluated lost bone in at least one region of the spine and lower extremities during flight. Of the 14, only one to date has exhibited full return to baseline BNM values in all regions. The current study will continue until the last participant has reached full bone recovery in all regions, has reached a plateau, or until three years after the flight (2001 for the last mission of the program). Bone mineral density losses in space and difficulty in returning to baseline indicate a need for countermeasure development. In late 1996 NASA JSC and Baylor College of Medicine were approved to conduct two countermeasure studies during 17 weeks of bed rest. In 1997 the studies were begun in the bed rest facility established by NASA, Baylor College of Medicine, and The Methodist Hospital in Houston. To date, three bed rest controls, five resistive

  1. Exercise Effects on the Brain and Sensorimotor Function in Bed Rest

    NASA Technical Reports Server (NTRS)

    Koppelmans, V.; Cassady, K.; De Dios, Y. E.; Szecsy, D.; Gadd, N.; Wood, S. J.; Reuter-Lorenz, R. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Ploutz-Snyder, L.; Seidler, R. D.

    2016-01-01

    Long duration spaceflight microgravity results in cephalad fluid shifts and deficits in posture control and locomotion. Effects of microgravity on sensorimotor function have been investigated on Earth using head down tilt bed rest (HDBR). HDBR serves as a spaceflight analogue because it mimics microgravity in body unloading and bodily fluid shifts. Preliminary results from our prior 70 days HDBR studies showed that HDBR is associated with focal gray matter (GM) changes and gait and balance deficits, as well as changes in brain functional connectivity. In consideration of the health and performance of crewmembers we investigated whether exercise reduces the effects of HDBR on GM, functional connectivity, and motor performance. Numerous studies have shown beneficial effects of exercise on brain health. We therefore hypothesized that an exercise intervention during HDBR could potentially mitigate the effects of HDBR on the central nervous system. Eighteen subjects were assessed before (12 and 7 days), during (7, 30, and 70 days) and after (8 and 12 days) 70 days of 6-degrees HDBR at the NASA HDBR facility in UTMB, Galveston, TX, US. Each subject was randomly assigned to a control group or one of two exercise groups. Exercise consisted of daily supine exercise which started 20 days before the start of HDBR. The exercise subjects participated either in regular aerobic and resistance exercise (e.g. squat, heel raise, leg press, cycling and treadmill running), or aerobic and resistance exercise using a flywheel apparatus (rowing). Aerobic and resistance exercise intensity in both groups was similar, which is why we collapsed the two exercise groups for the current experiment. During each time point T1-weighted MRI scans and resting state functional connectivity scans were obtained using a 3T Siemens scanner. Focal changes over time in GM density were assessed using voxel based morphometry (VBM8) under SPM. Changes in resting state functional connectivity was assessed

  2. Effects of long-duration bed rest on structural compartments of m. soleus in man

    NASA Technical Reports Server (NTRS)

    Belozerova, I.; Shenkman, B.; Mazin, M.; Leblanc, A.; LeBlanc, A. D. (Principal Investigator)

    2001-01-01

    Magnetic resonance imaging (MRI), histomorphometry and electron microscopy of muscle demonstrate that long-term exposure to actual or simulated weightlessness (including head down bed rest) leads to decreased volume of antigravity muscles in mammals. In muscles interbundle space is occupied by the connective tissue. Rat studies show that hindlimb unloading induces muscle fiber atrophy along with increase in muscle non-fiber connective tissue compartment. Beside that, usually 20% of the muscle fiber volume is comprised by non-contractile (non-myofibrillar) compartment. The aim of the present study was to compare changes in muscle volume, and in muscle fiber size with alterations in myofibrillar apparatus, and in connective tissue compartment in human m. soleus under conditions of 120 day long head down bed rest (HDBR).

  3. Head-down bed rest impairs vagal baroreflex responses and provokes orthostatic hypotension

    NASA Technical Reports Server (NTRS)

    Convertino, Victor A.; Doerr, Donald F.; Eckberg, Dwain L.; Fritsch, Janice M.; Vernikos-Danellis, Joan

    1990-01-01

    The hypothesis that baroreflex malfunction contributes to orthostatic hypotension in microgravity was tested by studying vagally mediated carotid baroreceptor-cardiac reflexes in healthy human subjects before, during, and after 30 days of 6-deg head-down bed rest. The baroreflex response relationships were provoked with ramped neck pressure-suction sequences comprising pressure elevations to 40 mm Hg followed by serial R-wave-triggered 15-mm Hg reductions to -65 mm0 Hg; each R-R interval was plotted as a function of systolic pressure minus the neck chamber pressure applied during the interval. It is shown that head-down bed rest led to an impairment of vagal baroreflex function and that it was associated with an impairment of hemodynamic adjustments to standing, indicating that baroreflex impairment may contribute to orthostatic hypotension observed in spacecrews after a flight.

  4. Effects of prolonged bed rest on the total peripheral resistance baroreflex

    NASA Technical Reports Server (NTRS)

    Xiao, X.; Mukkamala, R.; Sheynberg, N.; Williams, G. H.; Cohen, R. J.; Mark, R. G. (Principal Investigator)

    2002-01-01

    Orthostatic intolerance following prolonged exposure to microgravity continues to be a primary concern of the human space program. Reduced autonomic tone has been demonstrated to contribute to this phenomenon, and the heart rate baroreflex, in particular, has been repeatedly shown to be impaired. However, only the works of Yelle et al. have attempted to address the role of the total peripheral resistance (TPR) baroreflex, a potentially more significant contributor to blood pressure regulation. We applied a previously developed method for estimating the static gains of both the arterial and cardiopulmonary TPR baroreflexes to data obtained before and after 16-day bed rest. Reductions in the estimated static gains of the arterial (statistically significant) and cardiopulmonary TPR baroreflexes were found after bed rest. This study supports the works of Yelle et al, which imply that the TPR baroreflex is reduced after spaceflight.

  5. Physiology of Fluid and Electrolyte Responses During Inactivity: Water Immersion and Bed Rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.

    1984-01-01

    This manuscript emphasizes the physiology of fluid-electrolyte-hormonal responses during the prolonged inactivity of bed rest and water immersion. An understanding of the total mechanism of adaptation (deconditioning) should provide more insight into the conditioning process. Findings that need to be confirmed during bed rest and immersion are: (1) the volume and tissues of origin of fluid shifted to the thorax and head; (2) interstitial fluid pressure changes in muscle and subcutaneous tissue, particularly during immersion; and (3) the composition of the incoming presumably interstitial fluid that contributes to the early hypervolemia. Better resolution of the time course and source of the diuretic fluid is needed. Important data will be forthcoming when hypotheses are tested involving the probable action of the emerging diuretic and natriuretic hormones, between themselves and among vasopressin and aldosterone, on diuresis and blood pressure control.

  6. Reference intervals for the markers of proteinuria with a standardised bed-rest collection of urine.

    PubMed

    Kouri, T; Harmoinen, A; Laurila, K; Ala-Houhala, I; Koivula, T; Pasternack, A

    2001-05-01

    Reference intervals for markers of proteinuria or glomerular charge selectivity were measured in 61 healthy female and 61 healthy male individuals. Timed bed-rest and daytime collections were used to assess significance of preanalytical variability of results. Bed-rest collections are advisable for research on renal damage, whereas in routine care, robust protein/creatinine ratios work as practical estimates of protein excretion rates, the correlations to excretion rates improving with increasing proteinuria. For glomerular charge selectivity, pancreatic/salivary isoamylase clearance ratio showed lower within-subject biological variation than IgG/IgG4 clearance ratio, allowing more accurate classification into normal and reduced charge selectivity. With our method, the lower 2.5% reference intervals for isoamylase clearance ratio were 1.1 in men and 1.9 in women.

  7. Work capacity during 30 days of bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Trowbridge, T. S.; Wade, C. E.

    1989-01-01

    Results are presented from a study to determine whether or not short-term variable intensity isotonic and intermittent high-intensity isokinetic short-duration leg exercise is effective for the maintenance of peak O2 (VO2) uptake and muscular strength and endurance, respectively, during 30 days of -6 deg head-down bed rest deconditioning. The results show no significant changes in leg peak torque, leg mean total work, arm total peak torque, or arm mean total work for members of the isotonic, isokinetic, and controls groups. Changes are observed, however, in peak VO2 levels. The results suggest that near-peak variabile intensity, isotonic leg excercise maintains peak VO2 during 30 days of bed rest, while peak intermittent, isokinetic leg excercise protocol does not.

  8. Analog Exercise Hardware to Implement a High Intensity Exercise Program During Bed Rest

    NASA Astrophysics Data System (ADS)

    Loerch, Linda; Newby, Nate; Sinka, Joe; Ploutz-Snyder, Lori

    2013-02-01

    To evaluate novel countermeasure protocols in a spaceflight analog setting before validation on the International Space Station, NASA’s Human Research Program is sponsoring a multi-investigator bed rest campaign that uses a combination of commercial and custom-made exercise training hardware to conduct daily resistance and aerobic exercise protocols. These devices include the stand alone zero-gravity locomotion simulator, horizontal squat device, Lode commercial supine cycle ergometer, Cybex commercial prone leg curl machine, and Quantum Fitness commercial horizontal leg press. This paper will describe these pieces of hardware that are used to support current bed rest studies at NASA’s Flight Analog Research Unit in Galveston, Texas, USA.

  9. Physiological Effects of Aquatic Exercise in Pregnant Women on Bed Rest.

    PubMed

    Sechrist, Dawndra M; Tiongco, Cynthia Gorter; Whisner, Sandra M; Geddie, Matthew D

    2015-01-01

    This pilot study examined the effectiveness of an Aquatic Exercise Program (AEP) provided by an occupational therapist for pregnant women on hospitalized bed rest. Researchers conducted a retrospective analysis of medical records of hospitalized pregnant women comparing those who attended an AEP (n = 19) to a control group who received no AEP (n = 12). Statistical tests were used to assess evidence of differences in length of gestation as well as blood pressure and amniotic fluid index (AFI) at discharge. Women who received an AEP had increased AFI and length of gestation compared to the control group. This study supports the use of an AEP as an intervention for pregnant women on prescribed bed rest. Further research is recommended to validate these findings with a larger sample.

  10. Cardiorespiratory deconditioning with static and dynamic leg exercise during bed rest

    NASA Technical Reports Server (NTRS)

    Stremel, R. W.; Convertino, V. A.; Bernauer, E. M.; Greenleaf, J. E.

    1976-01-01

    Results are presented for an experimental study designed to compare the effects of heavy static and dynamic exercise training during 14 days of bed rest on the cardiorespiratory responses to submaximal and maximal exercise performed by seven healthy men aged 19-22 yr. The parameters measured were submaximal and maximal oxygen uptake, minute ventilation, heart rate, and plasma volume. The results indicate that exercise alone during bed rest reduces but does not eliminate the reduction in maximal oxygen uptake. An additional positive hydrostatic effect is therefore necessary to restore maximal oxygen uptake to ambulatory control levels. The greater protective effect of static exercise on maximal oxygen uptake is probably due to a greater hydrostatic component from the isometric muscular contraction. Neither the static nor the dynamic exercise training regimes are found to minimize the changes in all the variables studied, thereby suggesting a combination of static and dynamic exercises.

  11. Bed Rest is an Analog to Study the Physiological Changes of Spaceflight and to Evaluate Countermeasures

    NASA Technical Reports Server (NTRS)

    Pfannenstiel, P.; Ottenbacher, M.; Inniss, A.; Ware, D.; Anderson, K.; Stranges, S.; Keith, K.; Cromwell, R.; Neigut. J.; Powell, D.

    2012-01-01

    The UTMB/NASA Flight Analog Research Unit is an inpatient unit with a bionutrition kitchen and unique testing areas for studying subjects subjected to 6 degree head-down complete bed rest for prolonged periods as an analog for zero gravity. Bed rest allows study of physiological changes and performance of functional tasks representative of critical interplanetary mission operations and measures of the efficacy of countermeasures designed to protect against the resulting deleterious effects. METHODS/STUDY POPULATION: Subjects are healthy adults 24-55 years old; 60 75 in tall; body mass index 18.5-30; and bone mineral density normal by DXA scan. Over 100 subjects have been studied in 7 campaigns since 2004. The iRAT countermeasure combines high intensity interval aerobic exercises on alternating days with continuous aerobic exercise. Resistance exercise is performed 3 days per week. Subjects are tested on an integrated suite of functional and interdisciplinary physiological tests before and after 70 days of total bed rest. RESULTS/ANTICIPATED RESULTS: It is anticipated that post-bed rest functional performance will be predicted by a weighted combination of sensorimotor, cardiovascular and muscle physiological factors. Control subjects who do not participate in the exercise countermeasure will have significantly greater decreases in these parameters. DISCUSSION/SIGNIFICANCE OF IMPACT: Astronauts experience alterations in multiple physiological systems due to exposure to the microgravity, leading to disruption in the ability to perform functional tasks after reintroduction to a gravitational environment. Current flight exercise countermeasures are not fully protective of cardiovascular, muscle and bone health. There is a need to refine and optimize countermeasures to mitigate health risks associated with long-term space missions.

  12. Calcium kinetics during bed rest with artificial gravity and exercise countermeasures

    PubMed Central

    Smith, S. M.; Castaneda-Sceppa, C.; O’Brien, K. O.; Abrams, S. A.; Gillman, P.; Brooks, N. E.; Cloutier, G. J.; Heer, M.; Zwart, S. R.; Wastney, M. E.

    2015-01-01

    Summary We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest. Subjects ingested less calcium during bed rest, and with artificial gravity, they also absorbed less calcium. With exercise, they excreted less calcium. To retain bone during bed rest, calcium intake needs to be maintained. Introduction This study aims to assess the potential for artificial gravity (AG) and exercise (EX) to mitigate loss of bone calcium during space flight. Methods We performed two studies: (1) a 21-day bed rest (BR) study with subjects receiving 1 h/day AG (n=8) or no AG (n=7) and (2) a 28-day BR study with 1 h/day resistance EX (n=10) or no EX (n=3). In both studies, stable isotopes of Ca were administered orally and intravenously, at baseline and after 10 days of BR, and blood, urine, and feces were sampled for up to 14 days post dosing. Tracers were measured using thermal ionization mass spectrometry. Data were analyzed by compartmental modeling. Results Less Ca was absorbed during BR, resulting in lower Ca balance in BR+AG (−6.04±3.38 mmol/day, P=0.023). However, Ca balance did not change with BR+EX, even though absorbed Ca decreased and urinary Ca excretion increased, because endogenous excretion decreased, and there was a trend for increased bone deposition (P=0.06). Urinary N-telopeptide excretion increased in controls during BR, but not in the EX group. Markers of bone formation were not different between treatment groups for either study. Ca intake decreased during BR (by 5.4 mmol/day in the AG study and 2.8 mmol/day in the EX study), resulting in lower absorbed Ca. Conclusions During BR (or space flight), Ca intake needs to be maintained or even increased with countermeasures such as exercise, to enable maintenance of bone Ca. PMID:24861908

  13. Physical inactivity as the culprit of metabolic inflexibility: evidence from bed-rest studies.

    PubMed

    Bergouignan, Audrey; Rudwill, Floriane; Simon, Chantal; Blanc, Stéphane

    2011-10-01

    Although it is no longer debatable that sedentary behaviors are an actual cause of many metabolic diseases, the physiology of physical inactivity has been poorly investigated for this purpose. Along with microgravity, the physiological adaptations to spaceflights require metabolic adaptations to physical inactivity, and that is exceedingly well-simulated during the ground-based microgravity bed-rest analogs. Bed rest thus represents a unique model to investigate the mechanisms by which physical inactivity leads to the development of current societal chronic diseases. For decades, however, clinicians and physiologists working in space research have worked separately without taking full awareness of potential strong mutual questioning. This review summarizes the data collected over the last 60 years on metabolic adaptations to bed rest in healthy subjects. Our aim is to provide evidence that supports the hypothesis that physical inactivity per se is one of the primary causes in the development of metabolic inflexibility. This evidence will focus on four main tenants of metabolic inflexiblity: 1) insulin resistance, 2) impaired lipid trafficking and hyperlipidemia, 3) a shift in substrate use toward glucose, and 4) a shift in muscle fiber type and ectopic fat storage. Altogether, this hypothesis places sedentary behaviors upstream on the list of factors involved in metabolic inflexibility, which is considered to be a primary impairment in several metabolic disorders such as obesity, insulin resistance, and type 2 diabetes mellitus. PMID:21836047

  14. Electrical impedance measurements in the arm and the leg during a thirty day bed rest study

    NASA Technical Reports Server (NTRS)

    Cardus, David; Jaweed, Mazher; McTaggart, Wesley

    1995-01-01

    The need to detect, follow, and understand the effects of gravity on body fluid distribution is a constant stimulus to the quest for new techniques in this area of research. One of these techniques is electrical bioimpedance spectroscopy (BIS). Although not new, this is a technique whose applications to biomedical research are fairly recent. What is new is the development of instrumentation that has made practical the use of impedance spectroscopy in the biomedical setting, particularly in studies involving human subjects. The purpose of this paper is to report impedance spectroscopy observations made on a subject who was submitted to bed rest for a period of thirty days. These observations were made as part of a study on muscle atrophy during a thirty day head down bed rest. Since bed rest studies are very costly in human and financial terms, and technically difficult to realize, we felt that even though the present study deals only with a single case it was worthy of reporting because it illustrates kinds of questions impedance spectroscopy may help to answer in microgravity research.

  15. Comparison of Structural and Functional Ocular Outcomes Between 14- and 70 Day Bed Rest

    NASA Technical Reports Server (NTRS)

    Cromwell, R. L.; Taibbi, G.; Zanello, S. B.; Yarbough, P. O.; Ploutz-Snyder, R. J.; Vizzeri, G.

    2016-01-01

    Purpose: To compare structural and functional ocular outcomes in healthy human subjects undergoing 14- and/or 70-day head-down-tilt bed rest (HDTBR). We hypothesized the amount of HDTBR-induced ocular changes be affected by the HDTBR duration. Methods: The studies were conducted at the NASA Flight Analogs Research Unit, The University of Texas Medical Branch at Galveston, Galveston, TX. Participants were selected using NASA standard screening procedures. Standardized NASA screening procedures and bed rest conditions (e.g., strict sleep-wake cycle, standardized diet, continuous video monitoring) were implemented in both studies. Participants maintained a 6deg HDTBR position for 14 and/or 70 consecutive days and did not engage in exercise. Weekly ophthalmological examinations were conducted in the sitting (pre/post-bed rest only) and HDT positions. Ocular outcomes of interest included: near best-corrected visual acuity (BCVA); spherical equivalent, as determined by cycloplegic autorefraction; Goldmann applanation tonometry and iCare (Icare Finland Oy, Espoo, Finland) intraocular pressure (IOP) measurement; color vision; red dot test; modified Amsler grid test; confrontational visual field; stereoscopic color fundus photography; Spectralis OCT (Heidelberg Engineering, GmbH, Heidelberg, Germany) retinal nerve fiber layer thickness (RNFLT), peripapillary and macular retinal thicknesses. Mixed-effects linear models were used to compare pre- and post-HDTBR observations between 14- and 70-day HDTBR for our continuously scaled outcomes.

  16. Collagen cross-link excretion during space flight and bed rest

    NASA Technical Reports Server (NTRS)

    Smith, S. M.; Nillen, J. L.; Leblanc, A.; Lipton, A.; Demers, L. M.; Lane, H. W.; Leach, C. S.; LeBlanc, A. (Principal Investigator)

    1998-01-01

    Extended exposure to weightlessness results in bone loss. However, little information exists as to the precise nature or time course of this bone loss. Bone resorption results in the release of collagen breakdown products, including N-telopeptide and the pyridinium (PYD) cross-links, pyridinoline and deoxypyridinoline. Urinary pyridinoline and deoxypyridinoline are known to increase during bed rest. We assessed excretion of PYD cross-links and N-telopeptide before, during, and after long (28-day, 59-day, and 84-day) Skylab missions, as well as during short (14-day) and long (119-day) bed-rest studies. During space flight, the urinary cross-link excretion level was twice those observed before flight. Urinary excretion levels of the collagen breakdown products were also 40-50% higher, during short and long bed rest, than before. These results clearly show that the changes in bone metabolism associated with space flight involve increased resorption. The rate of response (i.e. within days to weeks) suggests that alterations in bone metabolism are an early effect of weightlessness. These studies are important for a better understanding of bone metabolism in space crews and in those who are bedridden.

  17. Focal Gray Matter Plasticity as a Function of Long Duration Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Koppelmans, Vincent; Erdeniz, Burak; DeDios, Yiri; Wood, Scott; Reuter-Lorenz, Patricia; Kofman, Igor; Bloomberg, Jacob; Mulavara, Ajitkumar; Seidler, Rachael

    2014-01-01

    Long duration spaceflight (i.e., 22 days or longer) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes may be related to structural and functional brain changes is yet unknown. However, increased intracranial pressure that by itself has been related to microgravity-induced bodily fluid shifts: [1] has been associated with white matter microstructural damage, [2] Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning. Long duration head-down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system, [3] Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on brain structure, and [4] Here we present results of the first eight subjects.

  18. Pyridoxic acid excretion during low vitamin B-6 intake, total fasting, and bed rest

    NASA Technical Reports Server (NTRS)

    Coburn, S. P.; Thampy, K. G.; Lane, H. W.; Conn, P. S.; Ziegler, P. J.; Costill, D. L.; Mahuren, J. D.; Fink, W. J.; Pearson, D. R.; Schaltenbrand, W. E.

    1995-01-01

    Vitamin B-6 metabolism in 10 volunteers during 21 d of total fasting was compared with results from 10 men consuming a diet low only in vitamin B-6 (1.76 mumol/d) and with men consuming a normal diet during bed rest. At the end of the fast mean plasma concentrations of vitamin B-6 metabolites and urinary excretion of 4-pyridoxic acid tended to be higher in the fasting subjects than in the low-vitamin B-6 group. The fasting subjects lost approximately 10% of their total vitamin B-6 pool and approximately 13% of their body weight. The low-vitamin B-6 group lost only approximately 4% of their vitamin B-6 pool. Compared with baseline, urinary excretion of pyridoxic acid was significantly increased during 17 wk of bed rest. There was no increase in pyridoxic acid excretion during a second 15-d bed rest study. These data suggest the possibility of complex interactions between diet and muscle metabolism that may influence indexes that are frequently used to assess vitamin B-6 status.

  19. Prolonged bed rest decreases skeletal muscle and whole body protein synthesis

    NASA Technical Reports Server (NTRS)

    Ferrando, A. A.; Lane, H. W.; Stuart, C. A.; Davis-Street, J.; Wolfe, R. R.

    1996-01-01

    We sought to determine the extent to which the loss of lean body mass and nitrogen during inactivity was due to alterations in skeletal muscle protein metabolism. Six male subjects were studied during 7 days of diet stabilization and after 14 days of stimulated microgravity (-6 degrees bed rest). Nitrogen balance became more negative (P < 0.03) during the 2nd wk of bed rest. Leg and whole body lean mass decreased after bed rest (P < 0.05). Serum cortisol, insulin, insulin-like growth factor I, and testosterone values did not change. Arteriovenous model calculations based on the infusion of L-[ring-13C6]-phenylalanine in five subjects revealed a 50% decrease in muscle protein synthesis (PS; P < 0.03). Fractional PS by tracer incorporation into muscle protein also decreased by 46% (P < 0.05). The decrease in PS was related to a corresponding decrease in the sum of intracellular amino acid appearance from protein breakdown and inward transport. Whole body protein synthesis determined by [15N]alanine ingestion on six subjects also revealed a 14% decrease (P < 0.01). Neither model-derived nor whole body values for protein breakdown change significantly. These results indicate that the loss of body protein with inactivity is predominantly due to a decrease in muscle PS and that this decrease is reflected in both whole body and skeletal muscle measures.

  20. Contributions of MSNA and stroke volume to orthostatic intolerance following bed rest

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. K.; Hogeman, C. S.; Sinoway, L. I.

    1999-01-01

    We examined whether the altered orthostatic tolerance following 14 days of head-down tilt bed rest (HDBR) was related to inadequate sympathetic outflow or to excessive reductions in cardiac output during a 10- to 15-min head-up tilt (HUT) test. Heart rate, blood pressure (BP, Finapres), muscle sympathetic nerve activity (MSNA, microneurography), and stroke volume blood velocity (SVV, Doppler ultrasound) were assessed during supine 30 degrees (5 min) and 60 degrees (5-10 min) HUT positions in 15 individuals who successfully completed the pre-HDBR test without evidence of orthostatic intolerance. Subjects were classified as being orthostatically tolerant (OT, n = 9) or intolerant (OI, n = 6) following the post-HDBR test. MSNA, BP, and SVV during supine and HUT postures were not altered in the OT group. Hypotension during 60 degrees HUT in the post-bed rest test for the OI group (P < 0.05) was associated with a blunted increase in MSNA (P < 0.05). SVV was reduced following HDBR in the OI group (main effect of HDBR, P < 0.02). The data support the hypothesis that bed rest-induced orthostatic intolerance is related to an inadequate increase in sympathetic discharge that cannot compensate for a greater postural reduction in stroke volume.

  1. Markers of bone resorption and calcium metabolism are related to dietary intake patterns in male and female bed rest subjects

    NASA Technical Reports Server (NTRS)

    Smith, Scott M.; Zwart, S. R.; Hargens, A. r.

    2006-01-01

    Dietary potassium and protein intakes predict net endogenous acid production in humans. Intracellular buffers, including exchangeable bone mineral, play a crucial role in balancing chronic acid-base perturbations in the body; subsequently, chronic acid loads can potentially contribute to bone loss. Bone is lost during space flight, and a dietary countermeasure would be desirable for many reasons. We studied the ability of diet protein and potassium to predict levels of bone resorption markers in males and females. Identical twin pairs (8 M, 7 F) were assigned to 2 groups: bed rest (sedentary, SED) or bed rest with supine treadmill exercise in a lower body negative pressure chamber (EX). Diet was controlled for 3 d before and 30 d of bed rest (BR). Urinary Ca, N-telopeptide (NTX), and pyridinium crosslinks (PYD) were measured before and on days 5, 12, 19, and 26 of BR. Data were analyzed by Pearson correlation (P<0.05). The ratio of dietary animal protein/potassium intake was not correlated with NTX before BR for males or females, but they were positively correlated in both groups of males during bed rest. Dietary animal protein/potassium and urine Ca were correlated before and during bed rest for the males, and only during bed rest for the females. Conversely, the ratio of dietary vegetable protein/potassium intake was negatively correlated with urinary calcium during bed rest for the females, but there was no relationship between vegetable protein/potassium intake and bone markers for the males. These data suggest that the ratio of animal protein/potassium intake may affect bone, particularly in bed rest subjects. These data show that the type of protein and gender may be additional factors that modulate the effect of diet on bone metabolism during bed rest. Altering this ratio may help prevent bone loss on Earth and during space flight.

  2. The interplay of central and peripheral factors in limiting maximal O2 consumption in man after prolonged bed rest.

    PubMed Central

    Ferretti, G; Antonutto, G; Denis, C; Hoppeler, H; Minetti, A E; Narici, M V; Desplanches, D

    1997-01-01

    1. The effects of bed rest on the cardiovascular and muscular parameters which affect maximal O2 consumption (VO2,max) were studied. The fractional limitation of VO2,max imposed by these parameters after bed rest was analysed. 2. The VO2,max, by standard procedure, and the maximal cardiac output (Qmax), by the pulse contour method, were measured during graded cyclo-ergometric exercise on seven subjects before and after a 42-day head-down tilt bed rest. Blood haemoglobin concentration ([Hb]) and arterialized blood gas analysis were determined at the highest work load. 3. Muscle fibre types, oxidative enzyme activities, and capillary and mitochondrial densities were measured on biopsy samples from the vastus lateralis muscle before and at the end of bed rest. The measure of muscle cross-sectional area (CSA) by NMR imaging at the level of biopsy site allowed computation of muscle oxidative capacity and capillary length. 4. The VO2,max was reduced after bed rest (-16.6%). The concomitant decreases in Qmax (-30.8%), essentially due to a change in stroke volume, and in [Hb] led to a huge decrease in O2 delivery (-39.7%). 5. Fibre type distribution was unaffected by bed rest. The decrease in fibre area corresponded to the significant reduction in muscle CSA (-17%). The volume density of mitochondria was reduced after bed rest (-16.6%), as were the oxidative enzyme activities (-11%). The total mitochondrial volume was reduced by 28.5%. Capillary density was unchanged. Total capillary length was 22.2% lower after bed rest, due to muscle atrophy. 6. The interaction between these muscular and cardiovascular changes led to a smaller reduction in VO2,max than in cardiovascular O2 transport. Yet the latter appears to play the greatest role in limiting VO2,max after bed rest (> 70% of overall limitation), the remaining fraction being shared between peripheral O2 diffusion and utilization. PMID:9218227

  3. Neuro-Motor Responses to Daily Centrifugation in Bed-Rested Subjects

    NASA Technical Reports Server (NTRS)

    Reschke, Millard F.; Somers, Jeffery T.; Krnavek, Jody; Fisher, Elizibeth; Ford, George; Paloski, William H.

    2007-01-01

    It is well known from numerous space flight studies that exposure to micro-g produces both morphological and neural adaptations in the major postural muscles. However, the characteristics and mechanism of these changes, particularly when it may involve the central nervous system are not defined. Furthermore, it is not known what role unloading of the muscular system may have on central changes in sensorimotor function or if centrifugation along the +Gz direction (long body axis) can mitigate both the peripheral changes in muscle function and modification of the central changes in sensorimotor adaptation to the near weightless environment of space flight. The purpose of this specific effort was, therefore, to investigate the efficacy of artificial gravity (AG) as a method for maintaining sensorimotor function in micro-g. Eight male subjects were exposed to daily 1 hr centrifugation during a 21 day 6 degree head-down bed rest study. Seven controls were placed on the centrifuge without rotation. The radius and angular velocity of the centrifuge were adjusted such that each subject experienced a centripetal acceleration of 2.5g at the feet, and approximately 1.0g at the heart. Both the tendon (MSR) and functional stretch reflexes (FSR) were collected using an 80 lb. ft. servomotor controlled via position feedback to provide a dorsiflexion step input to elicit the MSR, and the same step input with a built in 3 sec hold to evoke the FSR. EMG data were obtained from the triceps surae. Supplementary torque, velocity and position data were collected with the EMG responses. All data were digitized and sampled at 4 kHz. Only the MSR data has been analyzed at this time, and preliminary results suggest that those subjects exposed to active centrifugation (treatment group) show only minor changes in MSR peak latency times, either as a function of time spent in bed rest or exposure to centrifugation, while the control subjects show delays in the MSR peak latencies that are

  4. Effect of prolonged LBNP and saline ingestion on plasma volume and orthostatic responses during bed rest

    NASA Technical Reports Server (NTRS)

    Fortney, Suzanne M.; Dussack, Larry; Rehbein, Tracy; Wood, Margie; Steinmann, Laura

    1991-01-01

    Orthostatic intolerance remains a significant problem following space flight despite frequent use of the saline fluid-loading countermeasure and volitional use of an anti-gravity suite during reentry and landing. The purpose of this project is to examine the plasma volume (PV), endocrine, and orthostatic responses of bedrested subjects following 2-hr and 4-hr treatments of lower body negative pressure (LBNP) and saline ingestion. Ten healthy men were randomly assigned into 2 groups. Group A underwent a 4-hr LBNP/saline treatment on best rest day 5 and the 2-hr treatment on day 11. Group B underwent the 2-hr treatment on day 6 and the 4-hr treatment on day 10. Blood volume was determined before and after bed rest using radiolabelling. Changes in PV between measurements were calculated from changes in hematocrit and estimated red cell volume. Urinary excretion of anti-diuretic hormone (ADH) and aldosterone (ALD) were measured each day during the study. Orthostatic responses were measured using a ramp LBNP protocol before bed rest, before each treatment, and 24 hours after each treatment. Both 2-hr and 4-hr treatments resulted in a restoration of PV to pre-bed rest levels which persisted at least 24 hours. This increase in PV was associated with significant increases in urinary excretion of ADH and ALD. Twenty-four hours after the 4-hr treatment, the heart rate and pulse pressure response to LBNP were significantly lower and stroke volumes during LBNP were increased. Twenty-four hours after the 2-hr treatment, there was no evidence of improvement in orthostatic responses. These results suggest that a countermeasure which simply restores PV during space flight may not be sufficient for restoring orthostatic responses.

  5. Symposium Conclusion: Women's cardiovascular health after bed rest or space flight

    NASA Astrophysics Data System (ADS)

    Hughson, Richard L.; Arbeille, Phillipe; Shoemaker, Kevin; Edgell, Heather

    The Canadian Space Agency has recently funded research on two long-duration missions to study cardiovascular deconditioning associated with bed rest or space flight. The first, Women's International Space simulation for Exploration (WISE-2005) examined the responses during a 60-day head down bed rest (HDBR) of 24 women with or without a countermeasure that consisted of supine treadmill running within a lower body negative pressure (LBNP) device followed by 10-minutes resting LBNP and on different days high intensity resistance exercise on a flywheel device. The second study, Cardiovascular and cerebrovascular Control on return from the International Space Station (CCISS) is currently underway with two male astronauts tested and the first woman anticipated later this year. Women have been previously identified as being more susceptible to orthostatic intolerance than men after both bed rest and space flight studies. Thus, in the WISE-2005 study we examined responses of the cardiovascular system after HDBR in women and compared these to previously published data from men. We found that after HDBR women have a greater increase in heart rate with infusion of the drug isoproterenol and this was consistent with observations in men. However, during drug infusion the women had a reduction in leg vascular resistance while men had an increase. The exercise countermeasure group had preserved heart rate and leg vascular resistance responses to drug infusion. The ability to vasoconstrict the legs and splanchnic region is critical to maintenance of upright posture after HDBR and space flight. In the WISE-2005 study, subjects who were able to constrict the legs and/or splanchnic region after HDBR were much less likely to have a marked drop in blood pressure before the end of 10-minutes upright tilt, and subjects who performed the countermeasure were more likely to be in this group of tilt test finishers. These data provide new insight into mechanisms that might be responsible for

  6. Cardiac atrophy after bed-rest deconditioning: a nonneural mechanism for orthostatic intolerance

    NASA Technical Reports Server (NTRS)

    Levine, B. D.; Zuckerman, J. H.; Pawelczyk, J. A.; Blomqvist, C. G. (Principal Investigator)

    1997-01-01

    BACKGROUND: The cardiovascular adaptation to bed rest leads to orthostatic intolerance, characterized by an excessive fall in stroke volume (SV) in the upright position. We hypothesized that this large fall in SV is due to a change in cardiac mechanics. METHODS AND RESULTS: We measured pulmonary capillary wedge pressure (PCWP), SV, left ventricular end-diastolic volume (LVEDV), and left ventricular mass (by echocardiography) at rest, during lower-body negative pressure, and after saline infusion before and after 2 weeks of bed rest with -6 degrees head-down tilt (n=12 subjects aged 24+/-5 years). Pressure (P)-volume (V) curves were modeled exponentially by P=ae(kV)+b and logarithmically by P=-Sln[(Vm-V)/(Vm-V0)], where V0 indicates volume at P=0, and the constants k and S were used as indices of normalized chamber stiffness. Dynamic stiffness (dP/dV) was calculated at baseline LVEDV. The slope of the line relating SV to PCWP during lower-body negative pressure characterized the steepness of the Starling curve. We also measured plasma volume (with Evans blue dye) and maximal orthostatic tolerance. Bed rest led to a reduction in plasma volume (17%), baseline PCWP (18%), SV (12%), LVEDV (16%), V0 (33%), and orthostatic tolerance (24%) (all P<.05). The slope of the SV/PCWP curve increased from 4.6+/-0.4 to 8.8+/-0.9 mL/mm Hg (P<.01) owing to a parallel leftward shift in the P-V curve. Normalized chamber stiffness was unchanged, but dP/dV was reduced by 50% at baseline LVEDV, and cardiac mass tended to be reduced by 5% (P<.10). CONCLUSIONS: Two weeks of head-down-tilt bed rest leads to a smaller, less distensible left ventricle but a shift to a more compliant portion of the P-V curve. This results in a steeper Starling relationship, which contributes to orthostatic intolerance by causing an excessive reduction in SV during orthostasis.

  7. Physiological responses to prolonged bed rest and fluid immersion in man: A compendium of research (1974 - 1980)

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Silverstein, L.; Bliss, J.; Langenheim, V.; Rosson, H.; Chao, C.

    1982-01-01

    Water immersion and prolonged bed rest reproduce nearly all the physiological responses observed in astronauts in the weightless state. Related to actual weightlessness, given responses tend to occur sooner in immersion and later in bed rest. Much research was conducted on humans using these two techniques, especially by Russian scientists. Abstracts and annotations of reports that appeared in the literature from January 1974 through December 1980 are compiled and discussed.

  8. Bone mineral loss and recovery after 17 weeks of bed rest

    NASA Technical Reports Server (NTRS)

    Leblanc, A. D.; Schneider, V. S.; Evans, H. J.; Engelbretson, D. A.; Krebs, J. M.; LaBlanc, A. D. (Principal Investigator)

    1990-01-01

    The purpose of this work was to determine the rate and extent of bone loss and recovery from long-term disuse and in particular from disuse after exposure to weightlessness. For this purpose, bed rest is used to simulate the reduced stress and strain on the skeleton. This study reports on the bone loss and recovery after 17 weeks of continuous bed rest and 6 months of reambulation in six normal male volunteers. Bone regions measured were the lumbar spine, hip, tibia, forearm, calcaneus, total body, and segmental regions from the total-body scan. The total body, lumbar spine, femoral neck, trochanter, tibia, and calcaneus demonstrated significant loss, p less than 0.05. Expressed as the percentage change from baseline, these were 1.4, 3.9, 3.6, 4.6, 2.2, and 10.4, respectively. Although several areas showed positive slopes during reambulation, only the calcaneus was significant (p less than 0.05), with nearly 100% recovery. Segmental analysis of the total-body scans showed significant loss (p less than 0.05) in the lumbar spine, total spine, pelvis, trunk, and legs. During reambulation, the majority of the regions demonstrated positive slopes, although only the pelvis and trunk were significant (p less than 0.05). Potential redistribution of bone mineral was observed: during bed rest the bone mineral increased in the skull of all subjects. The change in total BMD and calcium from calcium balance were significantly (p less than 0.05) correlated, R = 0.88.

  9. Multi-System Effects of Daily Artificial Gravity Exposures in Humans Deconditioned by Bed Rest

    NASA Technical Reports Server (NTRS)

    Paloski, William H.

    2007-01-01

    We have begun to explore the utility of intermittent artificial gravity (AG) as a multi-system countermeasure to the untoward health and performance effects of adaptation to decreased gravity during prolonged space flight. The first study in this exploration was jointly designed by an international, multi-disciplinary team of scientists interested in standardizing an approach so that comparable data could be obtained from follow-on studies performed in multiple international locations. Fifteen rigorously screened male volunteers participated in the study after providing written informed consent. All were subjected to 21 days of 6deg head-down-tilt (HDT) bed rest. Eight were treated with daily 1hr AG exposures (2.5g at the feet decreasing to 1.0g at the heart) aboard a short radius (3m) centrifuge, while the other seven served as controls. Multiple observations were made of dependent measures in the bone, muscle, cardiovascular, sensory-motor, immune, and behavioral systems during a 10 day acclimatization period prior to HDT bed rest and again during an 8 day recovery period after the bed rest period. Comparisons between the treatment and control subjects demonstrated salutary effects of the AG exposure on aspects of the muscle and cardiovascular systems, with no untoward effects on the vestibular system, the immune system, or cognitive function. Bone deconditioning was similar between the treatment and control groups, suggesting that the loading provided by this specific AG paradigm was insufficient to protect that system from deconditioning. Future work will be devoted to varying the loading duty cycle and/or coupling the AG loading with exercise to provide maximum physiological protection across all systems. Testing will also be extended to female subjects. The results of this study suggest that intermittent AG could be an effective multi-system countermeasure.

  10. Effect of 21 days of horizontal bed rest on behavioural thermoregulation.

    PubMed

    Yogev, Daniel; Eiken, Ola; Pisot, Rado; Biolo, Gianni; di Prampero, Pietro; Narici, Marco; Mekjavic, Igor B

    2010-01-01

    The present study investigated the effect of 21 days of horizontal bed rest on cutaneous cold and warm sensitivity, and on behavioural temperature regulation. Healthy male subjects (N = 10) were accommodated in a hospital ward for the duration of the study and were under 24-h medical care. All activities (eating, drinking, hygiene, etc.) were conducted in the horizontal position. On the 1st and 22nd day of bed rest, cutaneous temperature sensitivity was tested by applying cold and warm stimuli of different magnitudes to the volar region of the forearm via a Peltier element thermode. Behavioural thermoregulation was assessed by having the subjects regulate the temperature of the water within a water-perfused suit (T (wps)) they were wearing. A control unit established a sinusoidal change in T (wps), such that it varied from 27 to 42 degrees C. The subjects could alter the direction of the change of T (wps), when they perceived it as thermally uncomfortable. The magnitude of the oscillations towards the end of the trial was assumed to represent the upper and lower boundaries of the thermal comfort zone. The cutaneous threshold for detecting cold stimulus decreased (P < 0.05) from 1.6 (1.0) degrees C on day 1 to 1.0 (0.3) degrees C on day 22. No effect was observed on the ability to detect warm stimuli or on the regulated T (wps). We conclude that although cold sensitivity increased after bed rest, it was not of sufficient magnitude to cause any alteration in behavioural thermoregulatory responses.

  11. Artificial Gravity as a Multi-System Countermeasure to Bed Rest Deconditioning: Pilot Study Overview

    NASA Technical Reports Server (NTRS)

    Paloski, William H.; Young, L. R.

    2007-01-01

    Efficient, effective, multi-system countermeasures will likely be required to protect the health, safety, and performance of crews aboard planned exploration-class space flight missions to Mars and beyond. To that end, NASA, DLR, and IMBP initiated a multi-center international project to begin systematically exploring the utility of artificial gravity (AG) as a multi-system countermeasure in ground based venues using test subjects deconditioned by bed rest. The goal of this project is to explore the efficacy of short-radius, intermittent AG as a countermeasure to bone, muscle, cardiovascular, and sensory-motor adaptations to hypogravity. This session reports the results from a pilot study commissioned to validate a standardized protocol to be used by all centers involved in the project. Subject selection criteria, medical monitoring requirements, medical care procedures, experiment control procedures, and standardized dependent measures were established jointly. Testing was performed on 15 rigorously screened male volunteers subjected to 21 days of 6deg HDT bed rest. (All provided written consent to volunteer after the nature of the study and its hazards were clearly explained to them.) Eight were treated with daily 1hr AG exposures (2.5g at the feet decreasing to 1.0g at the heart) aboard a short radius (3m) centrifuge, while the other seven served as controls. Multiple tests of multiple dependent measures were made in each of the primary physiological systems of interest during a 10 day acclimatization period prior to HDT bed rest and again during an 8 day recovery period after the bed rest period was complete. Analyses of these data (presented in other papers in this session) suggest the AG prescription had salutary effects on aspects of the bone, muscle, and cardiovascular systems, with no untoward effects on the vestibular system, the immune system, or cognitive function. Furthermore, treatment subjects were able to tolerate 153/160 centrifuge sessions over

  12. Analysis of Arterial Mechanics During Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Elliot, Morgan; Martin, David S.; Westby, Christian M.; Stenger, Michael B.; Platts, Steve

    2014-01-01

    Arterial health may be affected by microgravity or ground based analogs of spaceflight, as shown by an increase in thoracic aorta stiffness1. Head-down tilt bed rest (HDTBR) is often used as a ground-based simulation of spaceflight because it induces physiological changes similar to those that occur in space2, 3. This abstract details an analysis of arterial stiffness (a subclinical measure of atherosclerosis), the distensibility coefficient (DC), and the pressure-strain elastic modulus (PSE) of the arterial walls during HDTBR. This project may help determine how spaceflight differentially affects arterial function in the upper vs. lower body.

  13. Male reproductive system in conditions of bed-rest in a head-down tilt.

    PubMed

    Nichiporuk, I A; Evdokimov, V V; Erasova, V I; Smirnov, O A; Goncharova, A G; Vassilieva GYu; Vorobiev, D V

    1998-07-01

    Study of reproductive function in simulating experiments is important as for expansion of our theoretical knowledge in the field of gravitational physiology and space biology and for the decision of applied problems in space and clinical medicine. Long-term bed rest in a head-down tilt--6 degrees (BRHDT)--antiorthostatic hypokinesia is a wide spread method for ground-based simulation of space flight's conditions (mainly of hemodynamical effects of microgravity and restriction of locomotor activity). The aim of the present research was to study a reproductive function in males during 60-120 day BRHDT.

  14. Male reproductive system in conditions of bed-rest in a head-down tilt.

    PubMed

    Nichiporuk, I A; Evdokimov, V V; Erasova, V I; Smirnov, O A; Goncharova, A G; Vassilieva GYu; Vorobiev, D V

    1998-07-01

    Study of reproductive function in simulating experiments is important as for expansion of our theoretical knowledge in the field of gravitational physiology and space biology and for the decision of applied problems in space and clinical medicine. Long-term bed rest in a head-down tilt--6 degrees (BRHDT)--antiorthostatic hypokinesia is a wide spread method for ground-based simulation of space flight's conditions (mainly of hemodynamical effects of microgravity and restriction of locomotor activity). The aim of the present research was to study a reproductive function in males during 60-120 day BRHDT. PMID:11542307

  15. Zinc and Copper Balances During 3 Weeks of Bed Rest, With or Without Artificial Gravity

    NASA Technical Reports Server (NTRS)

    Heacox, Hayley

    2016-01-01

    During my internship with the Johnson Space Center's Nutritional Biochemistry Laboratory, I led on a project evaluating the effects of bed rest on copper and zinc metabolism to better understand the role of these nutrients in human adaptation to (simulated) space flight. Furthermore, the effects of artificial gravity, a multisystem countermeasure, were explored. In this project, I studied mineral balance is defined as the body's net loss or gain of a nutrient over time, and thus losses (in urine or feces) are subtracted from dietary intake. In my project, it was hypothesized that artificial gravity may have more of an effect on muscle versus bone, and this may be evident through effects observed with copper and zinc. In this study, dietary intake and fecal excretion of zinc and copper were previously determined. I was responsible for determining urinary zinc and copper content. This required preparation of all urine samples in a 1:10 dilution fashion with a diluent comprised of 1%Nitric Acid (grade), 2% ETOH, and 0.005% Triton X-100 in 18mOhm water along with a 1:1 Gallium Germanium internal standard. The diluted samples were then analyzed via inductively coupled plasma mass spectrometry (ICP-MS). Concentrations were determined by comparing unknown sample analyses to calibration curves, which were prepared daily. Upon completing cumulative copper and zinc balance determinations, I found that AG-treated subjects had more positive copper balance than control subjects during best, which suggests that AG-treated subjects tended to retain more copper. The opposite was observed for zinc; although positive, AG-treated subjects had a lower zinc balance than control subjects during bed rest. This suggests less preservation of this mineral. Previously, cumulative calcium balance was determined for this study. It was found that calcium balance decreased in both control and AG-treated subjects during bed rest. The zinc and copper balances found in this study reveal positive

  16. WISE-2005: Integrative Cardiovascular Responses with LBNP during 60-Day Bed Rest in Women

    NASA Technical Reports Server (NTRS)

    Hughson, R. L.; Kerbeci, P.; Arbeille, Ph.; Mattar, L.; Shoemaker, J. K.

    2005-01-01

    During 2005, 24 women will take part in the Women International Space-simulation for Exploration (WISE). In this paper we report on the first phase that studied 4 Exercise (EX+LBNP), 4 nutrition (NUT), and 4 no countermeasure control (CON) subjects. The EX+LBNP group completed regular exercise on a treadmill inside LBNP, flywheel resistive exercise and static periods of LBNP, and had recovery days. The NUT group received daily protein supplements. Integrative cardiovascular responses were obtained and here we report data for heart rate during LBNP, blood volume and angiotensin 11. LBNP was applied at 0, -10, -20 and -30 mmHg for 2-minutes for each stage. Blood was sampled prebed rest and on HDT-60. After 60-days head down bed rest, HR in the CON group increased by 6.1+/-2.8 bpm at rest and by 20.7+/-5.0 bpm at -30 mmHg LBNP. The EX+LBNP group had increases of 3.6+/-5.6 and 11.6+/-5.4 bpm, while the NUT group HR increased 2.6+/-3.1 and 9.4+/-3.6 bpm. The EX+LBNP group had almost no change in blood volume or plasma angiotensin II from pre-bed rest to HDT60, while both the CON and NUT groups had larger increases in plasma volume and almost double concentrations of angiotensin II. These data show a positive effect in the EX+LBNP group on the heart rate response as well as an unexpected possible benefit in the NUT group. Further studies are required to confirm possible cardiovascular benefits of the protein supplement.

  17. Use of bed rest and head-down tilt to simulate spaceflight-induce immune system changes

    NASA Technical Reports Server (NTRS)

    Schmitt, D. A.; Schaffar, L.; Taylor, G. R.; Loftin, K. C.; Schneider, V. S.; Koebel, A.; Abbal, M.; Sonnenfeld, G.; Lewis, D. E.; Reuben, J. R.; Ferebee, R.

    1996-01-01

    Bed rest, both with and without head-down tilt, has been extensively used as an earth-bound analog to study physiologic effects mimicking those occurring in weightlessness during spaceflight. We have been able to show in six subjects that 4 weeks of head-down tilt bed rest induces a significant decrease in interleukin-2 secretion by PHA-stimulated T lymphocytes. Another study, lasting 113 days, with two subjects showed a decreased interleukin-2 receptor expression in PHA-stimulated peripheral blood mononuclear cells but a decreased interleukin-2 production in one subject only. Under the same conditions, interleukin-1 production was largely increased in both subjects. Several other immune parameters were also analyzed. Increased interleukin-1 production could contribute to bone mineral loss encountered during bed rest and decreased interleukin-2 secretion could play a role in the appearance of infectious diseases often observed during bed red.

  18. Disproportionate loss of thin filaments in human soleus muscle after 17-day bed rest

    NASA Technical Reports Server (NTRS)

    Riley, D. A.; Bain, J. L.; Thompson, J. L.; Fitts, R. H.; Widrick, J. J.; Trappe, S. W.; Trappe, T. A.; Costill, D. L.

    1998-01-01

    Previously we reported that, after 17-day bed rest unloading of 8 humans, soleus slow fibers atrophied and exhibited increased velocity of shortening without fast myosin expression. The present ultrastructural study examined fibers from the same muscle biopsies to determine whether decreased myofilament packing density accounted for the observed speeding. Quantitation was by computer-assisted morphometry of electron micrographs. Filament densities were normalized for sarcomere length, because density depends directly on length. Thick filament density was unchanged by bed rest. Thin filaments/microm2 decreased 16-23%. Glycogen filled the I band sites vacated by filaments. The percentage decrease in thin filaments (Y) correlated significantly (P < 0.05) with the percentage increase in velocity (X), (Y = 0.1X + 20%, R2 = 0.62). An interpretation is that fewer filaments increases thick to thin filament spacing and causes earlier cross-bridge detachment and faster cycling. Increased velocity helps maintain power (force x velocity) as atrophy lowers force. Atrophic muscles may be prone to sarcomere reloading damage because force/microm2 was near normal, and force per thin filament increased an estimated 30%.

  19. Effects of Daily Centrifugation on Segmental Fluid Distribution in Bed-rested Subjects

    NASA Technical Reports Server (NTRS)

    Diedrich, Andre; Moore, S. T.; Stenger, M.; Arya, T. M.; Newby, N.; Tucker, J. M.; Milstead, L.; Acock, K.; Knapp, C.; Jevans, J.; Paloski, W.

    2007-01-01

    The effect of daily centrifugation on segmental fluid distribution have been studied during 21 days of 6 degree head down bedrest. One group (N=7) underwent no countermeasure while the other (N=8) received a daily, one hour, dose (2.5 gz at the foot, decreasing to 1.0 gz at the heart) of artificial gravity (AG) training on the Johnson Space Center short radius centrifuge. Fluid shifts of thoracic(VTO), abdominal (VAB), thigh (VTH), and calf (VCA) regions were measured by the tetrapolar segmental body impedance technique. Untrained subjects reduced their total volume from 18.9 plus or minus 0.5L to 17.9 plus or minus 0.9L (MN plus or minus SE, P less than 0.05) while trained subjects maintained their total volume. In untrained, control, subjects after bed rest, there was a trend toward reduced volume in all segments, with significant reductions in thigh and calf (fig, P less than 0.05). Trained subjects maintained volume in all segments. Our data indicate that artificial gravity treatment counteracts bed rest-induced hypovolemia.

  20. Surveillance of Ocular Parameters and Visual Function in Bed Rest Subjects

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.

    2011-01-01

    Recent visual changes in astronauts have raised concern about ocular health during long duration spaceflight. Seven cases have been documented in astronauts who spent 6 months aboard the International Space Station. These astronauts were male ranging in age from 45 to 55 years old. All astronauts exhibited pre- to post flight refractive changes. Decreased intraocular pressure (IOP) post flight was observed in 3 cases. Fundoscopic exams revealed post flight findings of choroidal folds in 4 cases, optic disc edema in 5 cases and the presence of cotton wool spots in 3 cases. Optical coherence tomography (OCT) confirmed findings of choroidal folds and disc edema, and also documented retinal nerve fiber layer thickening (5 cases). Findings from MRI examinations showed posterior globe flattening (5 cases), optic nerve sheath distention (6 cases) and torturous optic nerves (2 cases). Of the 7 cases, intracranial pressure was measured on 4 astronauts. These 4 showed elevated ICP post-flight that remained elevated for as long as 19 months in one case. While the etiology remains unknown, hypotheses speculate that venous insufficiency or hypertension in the brain caused by cephalad fluid shifts during spaceflight are possible mechanisms for ocular changes seen in astronauts. Head-down tilt bed rest is a spaceflight analog that induces cephalad fluid shifts. This study is designed to provide ocular monitoring of bed rest subjects and determine whether clinically relevant changes are found. Ocular Changes

  1. Changes in prevalence of subjective fatigue during 14-day 6° head-down bed rest

    NASA Astrophysics Data System (ADS)

    Hirayanagi, Kaname; Natsuno, Toyoki; Shiozawa, Tomoki; Yamaguchi, Nobuhisa; Watanabe, Yoriko; Suzuki, Satomi; Iwase, Satoshi; Mano, Tadaaki; Yajima, Kazuyoshi

    2009-06-01

    The present study examines the prevalence of subjective fatigue in young healthy males during 14 days of 6° head-down bed rest (HDBR) by using a multidimensional questionnaire. Forty-one subjects completed the Subjective Fatigue Scale questionnaire to assess the fatigue-related complaints and symptoms. The questionnaire is composed of three sections, with 10 items each. The sections measured drowsiness and dullness (Section 1), difficulty in concentration (Section 2), and the projection of physical disintegration (Section 3). The subjects answered simple questions between 1400 and 1700 on 6 measurement days before and during the HDBR period. The prevalence rate of low back pain was markedly high (80.5%) on the second day and more than 50% in the first half of the HDBR period, and any complaints related to either a lack of sleep or a deterioration in the quality of sleep continued until the end of the HDBR period. Our findings may be useful in developing preventive strategies against physical and mental fatigue associated with prolonged HDBR, horizontal bed rest, and microgravity environments.

  2. Postural responses of head and foot cutaneous microvascular flow and their sensitivity to bed rest

    NASA Technical Reports Server (NTRS)

    Aratow, Michael; Hargens, Alan R.; Meyer, J.-UWE; Arnaud, Sara B.

    1991-01-01

    To explore the mechanism for facial puffiness, headache, and nasal congestion associated with microgravity and cephalad fluid shifts, the postural responses of the cutaneous microcirculation (CMC) in the forehead and dorsum of the foot of eight healthy men were studied by changing body position on a tilt table and measuring blood flows with a laser Doppler flowmeter. Increasing arterial pressure in the feet by moving from a -6-deg head-down tilt to a 60-deg head-up posture decreased foot CMC by 46.5 + or - 12.0 percent. Raising arterial pressure in the head increased forehead CMC by 25.5 + or - 0.7 percent (p less than 0.05). To investigate the possibility that these opposite responses could be modified by simulated microgravity, tilt test were repeated after 7 d of -6-deg head-down-tilt bed rest. The responses were not significantly different from those recorded before bed rest. Therefore, CMC in the feet is well regulated to prevent edema when shifting to an upright position, whereas there is less regulation in the head CMC.

  3. Head-down-tilt bed rest alters forearm vasodilator and vasoconstrictor responses

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. K.; Hogeman, C. S.; Silber, D. H.; Gray, K.; Herr, M.; Sinoway, L. I.

    1998-01-01

    To test the hypothesis that head-down-tilt bed rest (HDBR) for 14 days alters vascular reactivity to vasodilatory and vasoconstrictor stimuli, the reactive hyperemic forearm blood flow (RHBF, measured by venous occlusion plethysmography) and mean arterial pressure (MAP, measured by Finapres) responses after 10 min of circulatory arrest were measured in a control trial (n = 20) and when sympathetic discharge was increased by a cold pressor test (RHBF + cold pressor test; n = 10). Vascular conductance (VC) was calculated (VC = RHBF/MAP). In the control trial, peak RHBF at 5 s after circulatory arrest (34.1 +/- 2.5 vs. 48.9 +/- 4.3 ml . 100 ml-1 . min-1) and VC (0.34 +/- 0.02 vs. 0.53 +/- 0.05 ml . 100 ml-1 . min-1 . mmHg-1) were reduced in the post- compared with the pre-HDBR tests (P < 0. 05). Total excess RHBF over 3 min was diminished in the post- compared with the pre-HDBR trial (84.8 vs. 117 ml/100 ml, P < 0.002). The ability of the cold pressor test to lower forearm blood flow was less in the post- than in the pre-HDBR test (P < 0.05), despite similar increases in MAP. These data suggest that regulation of vascular dilation and the interaction between dilatory and constrictor influences were altered with bed rest.

  4. Study of bone mineral metabolism. [during body immobilization, bed rest, and space flight

    NASA Technical Reports Server (NTRS)

    Palmer, H. E.

    1975-01-01

    The use of Sr-85 as an indicator of the skeletal location and relative amount of bone demineralization which occurs during immobilization of the body or body parts, bed-rest or space flight was studied. The bone mineral replacement which occurs after immobilization was measured rather than the bone loss which occurs during immobilization. In a study with two adult beagle dogs, the Sr-85 uptake in a leg which had been immobilized for two months was 400 percent higher than the uptake in the legs in regular use. This increased uptake probably resulted from only a few percent loss in bone mineral and indicates that losses less than one percent can be easily detected and located. The sensitivity, simplicity, and low radiation dose associated with the use of this method indicates that it should receive consideration for use on humans in bed-rest and space flight studies. Methods for measuring changes in total body nitrogen and in assisting the Johnson Space Center in calibrating a whole body counter for total body potassium measurements were also investigated.

  5. FemHab: The effects of bed rest and hypoxia on oxidative stress in healthy women.

    PubMed

    Debevec, Tadej; Pialoux, Vincent; Ehrström, Sabine; Ribon, Alexandra; Eiken, Ola; Mekjavic, Igor B; Millet, Grégoire P

    2016-04-15

    Independently, both inactivity and hypoxia augment oxidative stress. This study, part of the FemHab project, investigated the combined effects of bed rest-induced unloading and hypoxic exposure on oxidative stress and antioxidant status. Healthy, eumenorrheic women were randomly assigned to the following three 10-day experimental interventions: normoxic bed rest (NBR;n= 11; PiO2 = 133 mmHg), normobaric hypoxic bed rest (HBR;n= 12; PiO2 = 90 mmHg), and ambulatory hypoxic confinement (HAMB;n= 8: PiO2 = 90 mmHg). Plasma samples, obtained before (Pre), during (D2, D6), immediately after (Post) and 24 h after (Post+1) each intervention, were analyzed for oxidative stress markers [advanced oxidation protein products (AOPP), malondialdehyde (MDA), and nitrotyrosine], antioxidant status [superoxide dismutase (SOD), catalase, ferric-reducing antioxidant power (FRAP), glutathione peroxidase (GPX), and uric acid (UA)], NO metabolism end-products (NOx), and nitrites. Compared with baseline, AOPP increased in NBR and HBR on D2 (+14%; +12%;P< 0.05), D6 (+19%; +15%;P< 0.05), and Post (+22%; +21%;P< 0.05), respectively. MDA increased at Post+1 in NBR (+116%;P< 0.01) and D2 in HBR (+114%;P< 0.01) and HAMB (+95%;P< 0.05). Nitrotyrosine decreased (-45%;P< 0.05) and nitrites increased (+46%;P< 0.05) at Post+1 in HAMB only. Whereas SOD was higher at D6 (+82%) and Post+1 (+67%) in HAMB only, the catalase activity increased on D6 (128%) and Post (146%) in HBR and HAMB, respectively (P< 0.05). GPX was only reduced on D6 (-20%;P< 0.01) and Post (-18%;P< 0.05) in HBR. No differences were observed in FRAP and NOx. UA was higher at Post in HBR compared with HAMB (P< 0.05). These data indicate that exposure to combined inactivity and hypoxia impairs prooxidant/antioxidant balance in healthy women. Moreover, habitual activity levels, as opposed to inactivity, seem to blunt hypoxia-related oxidative stress via antioxidant system upregulation. PMID:26796757

  6. Weightlessness and cardiac rhythm disorders: current knowledge from space flight and bed-rest studies

    NASA Astrophysics Data System (ADS)

    Caiani, Enrico; Martin-Yebra, Alba; Landreani, Federica; Bolea, Juan; Laguna, Pablo; Vaïda, Pierre

    2016-08-01

    Isolated episodes of heart rhythm disorders have been reported during 40 years of space flight, triggering research to evaluate the risk of developing life-threatening arrhythmias induced by prolonged exposure to weightlessness. In fact, these events could compromise astronaut performance during exploratory missions, as well as pose at risk the astronaut health, due to limited options of care on board the International Space Station. Starting from original observations, this mini review will explore the latest research in this field, considering results obtained both during space flight and on Earth, the latter by simulating long-term exposure to microgravity by head-down bed rest maneuver in order to elicit cardiovascular deconditioning on normal volunteers.

  7. Hormonal changes during 17 days of head-down bed-rest

    NASA Technical Reports Server (NTRS)

    Custaud, Marc-Antoine; Arnaud, Sara B.; Monk, Timothy H.; Claustrat, Bruno; Gharib, Claude; Gauquelin-Koch, Guillemette

    2003-01-01

    We investigated in six men the impact of 17 days of head-down bed rest (HDBR) on the daily rhythms of the hormones involved in hydroelectrolytic regulation. This HDBR study was designed to mimic a real space flight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of Growth Hormone (GH), Cortisol, 6 Sulfatoxymelatonin, Normetadrenaline (NMN) and Metadrenaline (NM) was determined. A decrease in urinary cortisol excretion during the night of HDBR was noted. For GH, a rhythm was found before and during HDBR. The rhythm of melatonin, evaluated with the urine excretion of 6 Sulfatoxymelatonin (aMT6S), the main hepatic metabolite, persisted throughout the experiment without any modification to the level of phase. A decrease during the night was noted for normetadrenaline urinary derivates, but only during the HDBR.

  8. Physiological responses of women to simulated weightlessness: A review of the first female bed-rest study

    NASA Technical Reports Server (NTRS)

    Sandler, H.; Winter, D. L.

    1978-01-01

    Subjects were exposed to centrifugation, to lower body negative pressure (LBNP), and to exericse stress both before and after bed rest. Areas studied were centrifugation tolerance, fluid electrolyte changes and hematology, tolerance to LBNP, physical working capacity, biochemistries, blood fibrinolytic activity, female metabolic and hormonal responses, circadian alterations, and gynecology. Results were compared with the responses observed in similarly bed-rested male subjects. The bed-rested females showed deconditioning responses similar to those of the males, although with some differences. Results indicate that women are capable of coping with exposure to weightlessness and, moreover, that they may be more sensitive subjects for evaluating countermeasures to weightlessness and developing criteria for assessing applicants for shuttle voyages.

  9. Daily Supine LBNP Treadmill Exercise Maintains Upright Exercise Capacity During 14 Days of Bed Rest

    NASA Technical Reports Server (NTRS)

    Ertl, Andy C.; Watenpaugh, D. E.; Hargens, Alan R.; Fortney, S. M.; Lee, S. M. C.; Ballard, R. E.; William, J. M.

    1996-01-01

    Exposure to microgravity or bed rest reduces upright exercise capacity. Exercise modes, durations, and intensities which will effectively and efficiently counteract such deconditioning are presently unresolved. We that daily supine treadmill interval training with lower body negative pressure (LBNP) would prevent reduction in upright exercise capacity during 14 days of 6 deg. head-down bed rest (BR). Eight healthy male subjects underwent two 14 day BR protocols separated by 3 months. In a crossover design, subjects either remained at strict BR or performed 40 min of daily exercise consisting of supine walking and running at intensities varying from 40-80% of pre-BR upright peak oxygen uptake (VO2). LBNP during supine exercise was used to provide 1.0 to 1.2 times body weight of footward force. An incremental upright treadmill test to measure submaximal and peak exercise responses was given pre- and post-BR. In the non-exercise condition, peak VO2 and time to exhaustion were reduced 16 +/- 4% and 10 +/- 1% (p less than 0.05), respectively, from pre-BR. With LBNP exercise these variables were not significantly different (NS) from pre-BR. During submaximal treadmill speeds after BR, heart rate was higher (11 +/- 11 bpm, p less than 0.05) and respiratory exchange ratio was elevated (p less than 0.05) in the no exercise condition. Both were maintained at pre-BR levels in the LBNP exercise condition (NS from pre-BR). Since this supine treadmill interval training with addition of LBNP maintained upright exercise responses and capacity during BR, this countermeasure may also be effective during space flight.

  10. Twins Bed Rest Project: LBNP/Exercise Minimizes Changes in Lean Leg Mass, Strength and Endurance

    NASA Technical Reports Server (NTRS)

    Amorim, Fabiano T.; Schneider, Suzanne M.; Lee, Stuart M. C.; Boda, Wanda L.; Watenpaugh, Donald E.; Hargens, Alan R.

    2006-01-01

    Decreases in muscle strength and endurance frequently are observed in non-weightbearing conditions such as bed rest (BR), spaceflight or limb immobilization. Purpose: Ow purpose was to determine if supine treadmill exercise against simulated gravity, by application of lower body negative pressure (LBNP), prevents loss of lean leg mass, strength and endurance during 30 d of 6deg head-down bed rest (BR). Methods: Fifteen pairs of monozygous twins (8 male, 7 female pairs; 26+/-4 yrs; 170+/-12 cm; 62.6+/-11.3 kg; mean+/-SD) were subjects in the present study. One sibling of each pair of twins was randomly assigned to either an exercise (EX) or non-exercise (CON) group. The EX twin walked/jogged on a vertical treadmill within LBNP chamber 6 d/wk using a 40-min interval exercise protocol at 40-80% of pre-BR VO(sub 2peak). LBNP was adjusted individually for each subject such that footward force was between 1.0 and 1.2 times body weight (-53+/-5 mmHg LBNP). The CON twin performed no exercise during BR. Subjects performed isokinetic knee (60 and 120deg/s) and ankle (60deg/s) testing to assess strength and endurance (End) before and after BR. They also had their lean leg mass (L(sub mass)) evaluated by DEXA before and after BR. Results: Changes in peak torque (T(sub pk)) were smaller for flexion (flex) than for extension (ext) after BR and did not differ between groups. The CON group had larger decreases (P<0.05) in L(sub mass), knee and ankle ext T(sub pk), and knee ext End.

  11. Changes in plasma volume during bed rest - Effects of menstrual cycle and estrogen administration

    NASA Technical Reports Server (NTRS)

    Fortney, S. M.; Beckett, W. S.; Carpenter, A. J.; Davis, J.; Drew, H.

    1988-01-01

    The effect of increased blood estrogen concentration, caused either during normal menstrual cycles or by exogenous administration of premarin, on the bed-rest (BR) induced decrease in plasma volume (PV) was investigated. In women who underwent duplicate 11-day BR without estrogen supplementation, the PV was found to decrease significantly, during the first 5 days of BR, to a lower level at which it remained for the rest of the BR period. In women who began BR in the periovulatory stage of the menstrual cycle, the loss of PV was delayed, while women who began BR during other stages of the cycle exhibited the usual trend of the PV decrease during the BR. In women who underwent a single 12-day BR period while taking premarin (1.25 mg/day), PV was found to decrease during the first 4-5 days of BR, but then returned toward the pre-BR level during the remainder of the BR, indicating that estrogens have a role in stabilizing body fluid volume.

  12. WISE 2005: vascular responses to 60-day bed rest in women.

    PubMed

    Hughson, R L; Shoemaker, J K; Arbeille, Ph; Dyson, K S; Edgell, H; Kerbeci, P; Mattar, L; Zuj, K; Greaves, D K

    2007-07-01

    WISE-2005 studied 24 women during a 60-day head down bed rest (HDBR) who look part in an exercise countermeasure (LBNP-treadmill plus flywheel, EX) and no-exercise (No-EX). We conducted a series of experiments to explore changes in cardiovascular function and the ability of EX to prevent these changes. Resting arterial diameter in the arm was not affected but the leg arteries (femoral and popliteal) were significantly reduced in Np-EX, but was increased in EX. In this study we report on drug stimulated responses with sublingual nitroglycerin and infused isoproterenol. Heart rate increased in response to nitroglycerin with larger increases in No-EX after HDBR. Likewise during isoproterenol infusion the HR increase was greater after HDBR in the No-EX group. In all cases, the higher HR was associated with lower stroke volume in No-EX while stroke volume was protected in EX. These data do not support a change in sensitivity of beta-adrenergic receptors after HDBR. The leg vascular resistance decreased in response to isoproterenol and it decreased to a greater extent in No-EX than EX. These data were consistent with observations of lower leg vascular resistance during orthostatic challenge tests after HDBR. We conclude that consistent changes in cardiovascular function in the No-EX were detected by different methods that point to mechanisms contributing to orthostatic intolerance after HDBR. PMID:18372696

  13. Changes in the diurnal rhythms during a 45-day head-down bed rest.

    PubMed

    Liang, Xiaodi; Zhang, Lin; Wan, Yufeng; Yu, Xinyang; Guo, Yiming; Chen, Xiaoping; Tan, Cheng; Huang, Tianle; Shen, Hanjie; Chen, Xianyun; Li, Hongying; Lv, Ke; Sun, Fei; Chen, Shanguang; Guo, Jinhu

    2012-01-01

    In spaceflight human circadian rhythms and sleep patterns are likely subject to change, which consequently disturbs human physiology, cognitive abilities and performance efficiency. However, the influence of microgravity on sleep and circadian clock as well as the underlying mechanisms remain largely unknown. Placing volunteers in a prone position, whereby their heads rest at an angle of -6° below horizontal, mimics the microgravity environment in orbital flight. Such positioning is termed head-down bed rest (HDBR). In this work, we analysed the influence of a 45-day HDBR on physiological diurnal rhythms. We examined urinary electrolyte and hormone excretion, and the results show a dramatic elevation of cortisol levels during HDBR and recovery. Increased diuresis, melatonin and testosterone were observed at certain periods during HDBR. In addition, we investigated the changes in urination and defecation frequencies and found that the rhythmicity of urinary frequency during lights-off during and after HDBR was higher than control. The grouped defecation frequency data exhibits rhythmicity before and during HDBR but not after HDBR. Together, these data demonstrate that HDBR can alter a number of physiological processes associated with diurnal rhythms. PMID:23110150

  14. Mechanical Vibrations Reduce the Intervertebral Disc Swelling and Muscle Atrophy from Bed Rest

    NASA Technical Reports Server (NTRS)

    Holguin, Nilsson; Muir, Jesse; Evans, Harlan J.; Qin, Yi-Xian; Rubin, Clinton; Wagshul, Mark; Judex, Stefan

    2007-01-01

    Loss of functional weight bearing, such as experienced during space flight or bed rest (BR), distorts intervertebral disc (IVD) and muscle morphology. IVDs are avascular structures consisting of cells that may derive their nutrition and waste removal from the load induced fluid flow into and out of the disc. A diurnal cycle is produced by forces related to weight bearing and muscular activity, and comprised of a supine and erect posture over a 24 hr period. A diurnal cycle will include a disc volume change of approx. 10-13%. However, in space there are little or no diurnal changes because of the microgravity, which removes the gravitational load and compressive forces to the back muscles. The BR model and the etiology of the disc swelling and muscle atrophy could provide insight into those subjects confined to bed for chronic disease/injury and aging. We hypothesize that extremely low-magnitude, high frequency mechanical vibrations will abate the disc degeneration and muscle loss associated with long-term BR.

  15. Static Histomorphometry of the iliac crest after 360 days of antiorthostatic bed rest with and without countermeasures

    NASA Astrophysics Data System (ADS)

    Thomsen, J. S.; Morukov, B. V.; Vico, L.; Saparin, P. I.; Gowin, W.

    The loss of bone during immobilization is well-known and investigated, whereas the structural changes human cancellous bone undergoes during disuse is less well examined. The aim of the study was to examine the influence of hypokinesia on the static histomorphometric measures of the iliac crest using a 360-day-long bed rest experiment, simulating exposure to microgravity. Eight healthy males underwent 360 days of 5° head-down tilt bed rest. Three subjects were treated with the bisphosphonate Xidifon (900 mg/day) combined with a treadmill and ergonometer exercise regimen (1--2 hours/day) for the entire study period. Five subjects underwent 120 days of bed rest without countermeasures followed by 240 days of bed rest with the treadmill and ergonometer exercise regimen. Transiliac bone biopsies were obtained either at day 0 and 360 or at day 0, 120, and 360 at alternating sides of the ileum. The biopsies were embedded in methylmethacrylate, cut in 7-μm-thick sections, stained with Goldner trichrome, and static histomorphometry was performed. 120 days of bed rest without countermeasures resulted in decreased trabecular bone volume (-6.3%, p = 0.046) and trabecular number (-10.2%, p = 0.080) and increased trabecular separation (14.7%, p = 0.020), whereas 240 days of subsequent bed rest with exercise treatment prevented further significant deterioration of the histomorphometric measures. 360 days of bed rest with bisphosphonate and exercise treatment did not induce any significant changes in any of the histomorphometric measures. The study showed that 120 days of antiorthostatic bed rest without countermeasures induced significant deterioration of iliac crest trabecular bone histomorphometric properties. There are indications that the immobilization induced changes involve a loss of trabeculae rather than a general thinning of the trabeculae. On average, the countermeasures consisting of either bisphosphonate and exercise or exercise alone were able to either prevent

  16. Effects of three day bed-rest on circulatory, metabolic and hormonal responses to oral glucose load in endurance trained athletes and untrained subjects

    NASA Technical Reports Server (NTRS)

    Smorawinski, J.; Kubala, P.; Kaciuba-Uociako, H.; Nazar, K.; Titow-Stupnicka, E.; Greenleaf, J. E.

    1996-01-01

    Endurance trained long distance runners and untrained individuals underwent three days of bed rest and oral glucose loading. Before and after bed rest, individuals were given glucose tolerance tests, and their heart rates, blood pressure, blood glucose levels, insulin levels, and catecholamine interactions were measured. Results indicated that glucose tolerance is more affected by bed rest-induced deconditioning in untrained individuals than in trained individuals.

  17. Plasma volume restoration with salt tablets and water after bed rest prevents orthostatic hypotension and changes in supine hemodynamic and endocrine variables.

    PubMed

    Waters, Wendy W; Platts, Steven H; Mitchell, Brett M; Whitson, Peggy A; Meck, Janice V

    2005-02-01

    Head-down bed rest changes the values of many cardiovascular and endocrine variables and also elicits significant hypovolemia. Because previous studies had not controlled for hypovolemia, it is unknown whether the reported changes were primary effects of bed rest or secondary effects of bed rest-induced hypovolemia. We hypothesized that restoring plasma volume with salt tablets and water after 12 days of head-down bed rest would result in an absence of hemodynamic and endocrine changes and a reduced incidence of orthostatic hypotension. In 10 men, we measured changes from pre-bed-rest to post-bed-rest in venous and arterial pressures; heart rate; stroke volume; cardiac output; vascular resistance; plasma norepinephrine, epinephrine, vasopressin, renin activity (PRA), and aldosterone responses to different tilt levels (0 degrees, -10 degrees, 20 degrees, 30 degrees, and 70 degrees); and plasma volume and platelet alpha2- and lymphocyte beta2-adrenoreceptor densities and affinities (0 degrees tilt only). Fluid loading at the end of bed rest restored plasma volume and resulted in the absence of post-bed-rest orthostatic hypotension and changes in supine hemodynamic and endocrine variables. Fluid loading did not prevent post-bed-rest increases in beta2-adrenoreceptor density or decreases in the aldosterone-to-PRA ratio (P = 0.05 for each). Heart rate, epinephrine, and PRA responses to upright tilt after bed rest were increased (P < 0.05), despite the fluid load. These results suggest that incidents of orthostatic hypotension and many of the changes in supine hemodynamic and endocrine variables in volume-depleted bed-rested subjects occur secondarily to the hypovolemia. Despite normovolemia after bed rest, beta2-adrenoreceptors were upregulated, and heart rate, epinephrine, and PRA responses to tilt were augmented, indicating that these changes are independent of volume depletion.

  18. Association Between Cardiovascular and Intraocular Pressure Changes in a 14-day 6 deg Head Down Tilt (HDT) Bed Rest Study: Possible Implications in Retinal Anatomy

    NASA Technical Reports Server (NTRS)

    Cromwell, R. L.; Zanello, S. B.; Yarbough, P. O.; Ploutz-Snyder, R.; Taibbi, G.; Brewer, J. L.; Vizzeri, G.

    2013-01-01

    Mean IOP significantly increased while at 6deg HDT and returned towards pre-bed rest values upon leaving bed rest. While mean IOP increased during bed rest, it remained within the normal limits for subject safety. A diuretic shift and cardiovascular deconditioning occurs during in-bed rest, as expected. There was no demonstrable correlation between the largest change in IOP (pre/post) and cardiovascular measure changes (pre/post). Additional mixed effects linear regression modeling may reveal some subclinical physiological changes that might assist in describing the VIIP syndrome pathophysiology.

  19. Behavioral, Brain Imaging and Genomic Measures to Predict Functional Outcomes Post - Bed Rest and Spaceflight

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; DeDios, Y. E.; Gadd, N. E.; Caldwell, E. E.; Batson, C. D.; Goel, R.; Seidler, R. D.; Oddsson, L.; Zanello, S.; Clarke, T.; Peters, B.; Cohen, H. S.; Reschke, M.; Wood, S.; Bloomberg, J. J.

    2016-01-01

    Astronauts experience sensorimotor disturbances during their initial exposure to microgravity and during the re-adaptation phase following a return to an Earth-gravitational environment. These alterations may disrupt crewmembers' ability to perform mission critical functional tasks requiring ambulation, manual control and gaze stability. Interestingly, astronauts who return from spaceflight show substantial differences in their abilities to readapt to a gravitational environment. The ability to predict the manner and degree to which individual astronauts would be affected would improve the effectiveness of countermeasure training programs designed to enhance sensorimotor adaptability. For such an approach to succeed, we must develop predictive measures of sensorimotor adaptability that will allow us to foresee, before actual spaceflight, which crewmembers are likely to experience the greatest challenges to their adaptive capacities. The goals of this project are to identify and characterize this set of predictive measures. Our approach includes: 1) behavioral tests to assess sensory bias and adaptability quantified using both strategic and plastic-adaptive responses; 2) imaging to determine individual brain morphological and functional features, using structural magnetic resonance imaging (MRI), diffusion tensor imaging, resting state functional connectivity MRI, and sensorimotor adaptation task-related functional brain activation; and 3) assessment of genotypic markers of genetic polymorphisms in the catechol-O-methyl transferase, dopamine receptor D2, and brain-derived neurotrophic factor genes and genetic polymorphisms of alpha2-adrenergic receptors that play a role in the neural pathways underlying sensorimotor adaptation. We anticipate that these predictive measures will be significantly correlated with individual differences in sensorimotor adaptability after long-duration spaceflight and exposure to an analog bed rest environment. We will be conducting a

  20. Supine Lower Body Negative Pressure Exercise Maintains Upright Exercise Capacity in Male Twins during 30 Days of Bed Rest

    NASA Technical Reports Server (NTRS)

    Lee, Stuart M. C.; Schneider, Suzanne M.; Boda, Wanda L.; Watenpaugh, Donald E.; Macias, Brandon R.; Meyer, R. Scott; Hargens, Alan R.

    2006-01-01

    Exercise capacity is reduced following both short and long duration exposures to microgravity. We have shown previously that supine lower body negative pressure with exercise (LBNP(sub ex) maintains upright exercise capacity in men after 5d and 15d bed rest, as a simulation of microgravity. We hypothesized that LBNP(sub ex) would protect upright exercise capacity (VO2pk) and sprint performance in eight sets of identical male twins during a 30-d bed rest. Twins within each set were randomly assigned to either a control group (CON) who performed no exercise or to an exercise group (EX) who performed a 40-min interval (40-80% pre-BR VO2pk) LBNP(sub ex) (55+/-4 mmHg) exercise protocol, plus 5 min of resting LBNP, 6 d/wk. LBNP produced footward force equivalent to 1.0- 1.2 times body weight. Pre- and post-bed rest, subjects completed an upright graded exercise test to volitional fatigue and sprint test of 30.5 m. After bed rest, VO2pk was maintained in the EX subjects (-3+/-3%), but was significantly decreased in the CON subjects (-24+/-4%). Sprint time also was increased in the CON subjects (24+/-8%), but maintained in the EX group (8+/-2%). The performance of a supine, interval exercise protocol with LBNP maintains upright exercise capacity and sprint performance during 30 d of bed rest. This exercise countermeasure protocol may help prevent microgravity-induced deconditioning during long duration space flight.

  1. The effects of bed rest on crew performance during simulated shuttle reentry. Volume 1: Study overview and physiological results

    NASA Technical Reports Server (NTRS)

    Chambers, A.; Vykukal, H. C.

    1974-01-01

    A centrifuge study was carried out to measure physiological stress and control task performance during simulated space shuttle orbiter reentry. Jet pilots were tested with, and without, anti-g-suit protection. The pilots were exposed to simulated space shuttle reentry acceleration profiles before, and after, ten days of complete bed rest, which produced physiological deconditioning similar to that resulting from prolonged exposure to orbital zero g. Pilot performance in selected control tasks was determined during simulated reentry, and before and after each simulation. Physiological stress during reentry was determined by monitoring heart rate, blood pressure, and respiration rate. Study results indicate: (1) heart rate increased during the simulated reentry when no g protection was given, and remained at or below pre-bed rest values when g-suits were used; (2) pilots preferred the use of g-suits to muscular contraction for control of vision tunneling and grayout during reentry; (3) prolonged bed rest did not alter blood pressure or respiration rate during reentry, but the peak reentry acceleration level did; and (4) pilot performance was not affected by prolonged bed rest or simulated reentry.

  2. Effect of heat acclimation on sitting orthostatic tolerance in the heat after 48 and 96 hour bed rest in men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Matter, M., Jr.

    1995-01-01

    The purpose of this pilot study was to investigate sitting orthostatic tolerance and determine potentially adverse signs and symptoms that would incapacitate subjects in a hot environment (Gemini reentry cabin temperature profile) after 48 hr and 96 hr of horizontal bed rest (BR), which simulated microgravity deconditioning. Six college men (23-29 yr) were allocated into two groups: heat acclimated (three subjects: No. 1- control, No. 2- 48 hr BR, and No. 3- 96 hr BR) and nonheat acclimated (three subjects: No. 4- control, No. 5- 48 hr BR, and No. 6- 96 hr BR). After BR they sat in an ambient temperature of 57 C (135 F) for 30 min which then was decreased to 49 C (120 F) for up to 480 min. Tolerance time in the heat with seated orthostatic stress was 480 min (subject No. 1) and 180 min (subject No. 4) in the two ambulatory men, but was reduced to 22-150 min in the four bed-rested men irrespective of their heat acclimation status. Although heat acclimation appeared to enhance tolerance and attenuate accompanying physiological responses, as well as ameliorate the frequency and intensity of adverse signs and symptoms at termination of exposure, tolerance was reduced in the bed-rest deconditioned subjects regardless of their acclimation level. Thus, these few collective findings do not indicate an unequivocal positive effect of acute heat acclimation on sitting orthostatic tolerance in acute bed-rest deconditioned subjects.

  3. Effects of daily mild supine exercise on physical performance after 20 days bed rest in young persons

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.; Kashihara, H.; Takenaka, K.; Kawakubo, K.; Makita, Y.; Goto, S.; Ikawa, S.; Gunji, A.

    To investgate the effects of daily mild supine exercise on physical performance capacity identified as maximal oxygen uptake rate (VO 2max) after 20 days bed-rest, 3 male students performed a supine pedaling at 40 % intensity of VO 2max for one hour every day, while 6 male and 5 female students were control. Before and after the bed-rest, muscle mass and strength of exercising leg and cardio-vascular responses during -40 mmHg lower body negative pressure (LBNP) and moderate upright cycling exercise were measured. Despite the exercise programme VO 2max was similarly decreased to the control subjects after the bed-rest. The delta VO 2max was correlated to delta % left ventricular fractional shortening during LBNP, and also % delta VO 2max to % delta stroke volume of the moderate exercise (both p<0.05). The exercise programme should be too weak to maintain cardiovascular functions and thus to present the decrease in VO 2max against pro-longed bed-rest as well as weightlessness stress.

  4. Vibration mechanosignals superimposed to resistive exercise result in baseline skeletal muscle transcriptome profiles following chronic disuse in bed rest.

    PubMed

    Salanova, Michele; Gambara, Guido; Moriggi, Manuela; Vasso, Michele; Ungethuem, Ute; Belavý, Daniel L; Felsenberg, Dieter; Cerretelli, Paolo; Gelfi, Cecilia; Blottner, Dieter

    2015-01-01

    Disuse-induced muscle atrophy is a major concern in aging, in neuromuscular diseases, post-traumatic injury and in microgravity life sciences affecting health and fitness also of crew members in spaceflight. By using a laboratory analogue to body unloading we perform for the first time global gene expression profiling joined to specific proteomic analysis to map molecular adaptations in disused (60 days of bed rest) human soleus muscle (CTR) and in response to a resistive exercise (RE) countermeasure protocol without and with superimposed vibration mechanosignals (RVE). Adopting Affymetrix GeneChip technology we identified 235 differently transcribed genes in the CTR group (end- vs. pre-bed rest). RE comprised 206 differentially expressed genes, whereas only 51 changed gene transcripts were found in RVE. Most gene transcription and proteomic changes were linked to various key metabolic pathways (glycolysis, oxidative phosphorylation, tricarboxylic acid (TCA) cycle, lipid metabolism) and to functional contractile structures. Gene expression profiling in bed rest identified a novel set of genes explicitly responsive to vibration mechanosignals in human soleus. This new finding highlights the efficacy of RVE protocol in reducing key signs of disuse maladaptation and atrophy, and to maintain a close-to-normal skeletal muscle quality outcome following chronic disuse in bed rest. PMID:26596638

  5. Vibration mechanosignals superimposed to resistive exercise result in baseline skeletal muscle transcriptome profiles following chronic disuse in bed rest

    PubMed Central

    Salanova, Michele; Gambara, Guido; Moriggi, Manuela; Vasso, Michele; Ungethuem, Ute; Belavý, Daniel L.; Felsenberg, Dieter; Cerretelli, Paolo; Gelfi, Cecilia; Blottner, Dieter

    2015-01-01

    Disuse-induced muscle atrophy is a major concern in aging, in neuromuscular diseases, post-traumatic injury and in microgravity life sciences affecting health and fitness also of crew members in spaceflight. By using a laboratory analogue to body unloading we perform for the first time global gene expression profiling joined to specific proteomic analysis to map molecular adaptations in disused (60 days of bed rest) human soleus muscle (CTR) and in response to a resistive exercise (RE) countermeasure protocol without and with superimposed vibration mechanosignals (RVE). Adopting Affymetrix GeneChip technology we identified 235 differently transcribed genes in the CTR group (end- vs. pre-bed rest). RE comprised 206 differentially expressed genes, whereas only 51 changed gene transcripts were found in RVE. Most gene transcription and proteomic changes were linked to various key metabolic pathways (glycolysis, oxidative phosphorylation, tricarboxylic acid (TCA) cycle, lipid metabolism) and to functional contractile structures. Gene expression profiling in bed rest identified a novel set of genes explicitly responsive to vibration mechanosignals in human soleus. This new finding highlights the efficacy of RVE protocol in reducing key signs of disuse maladaptation and atrophy, and to maintain a close-to-normal skeletal muscle quality outcome following chronic disuse in bed rest. PMID:26596638

  6. Bone Resorption Increases as Early as the Second Day in Head- Down Bed Rest

    NASA Astrophysics Data System (ADS)

    Heer, M.; Kamps, N.; Mika, C.; Boese, A.; Gerzer, R.

    Long-term bed rest and space mission studies have shown that immobilization as well as microgravity induce increased bone resorption while bone formation tends to decrease. In order to analyze the kinetics of short-term changes in bone turnover we studied in a randomized, strictly controlled crossover design the effects of 6 days 6° head-down tilt bed rest (HDT) in 8 male healthy subjects (mean body weight (BW): 70.1 +/- 1.88 kg; mean age: 25.5 +/- 1.04 years) in our metabolic ward. Two days before arriving in the metabolic ward the subjects started with a diet consisting of an energy content of 10 MJ/d, 2000 mg Calcium/d, 400 i.U. Vitamin D, 200 mEq Na+ and 50 ml water/kg BW/d. The diet was continued in the metabolic ward. The metabolic ward period (11days) was divided into 3 parts: 4 ambulatory days, 6 days either HDT or control and 1 recovery day. Continuous urine collection started on the first day in the metabolic ward to analyze calcium excretion and bone resorption markers, namely C-telopeptide (CTX) and N-telopeptide (NTX). On the 2nd ambulatory day in the metabolic ward and on the 5th day in HDT or control blood was drawn to analyze serum calcium, parathyroid hormone, and bone formation markers (bone Alkaline Phosphatase (bAP), Procollagen-I-Propeptide (P-I-CP). Both study phases were identical with respect to environmental conditions, study protocol and diet. Urinary calcium excretion was as early as the first day in immobilization increased (p<0.01). CTX- and NTX-excretion stayed unchanged the first 24 hours in HDT compared to the control. But, already on the 2nd day of immobilization both bone resorption markers significantly increased. NTX-excretion was increased by 28.7 +/- 14.0% (p<0.05), while CTX-excretion rose by 17.8 +/- 8.3% (p<0.01). Both, the CTX- excretion as well as the calcium excretion keep the significantly higher level during the HDT period, and even continued through the first day of recovery. However, NTX excretion, descended from day

  7. Effect of head-down-tilt bed rest and hypovolemia on dynamic regulation of heart rate and blood pressure

    NASA Technical Reports Server (NTRS)

    Iwasaki, K. I.; Zhang, R.; Zuckerman, J. H.; Pawelczyk, J. A.; Levine, B. D.; Blomqvist, C. G. (Principal Investigator)

    2000-01-01

    Adaptation to head-down-tilt bed rest leads to an apparent abnormality of baroreflex regulation of cardiac period. We hypothesized that this "deconditioning response" could primarily be a result of hypovolemia, rather than a unique adaptation of the autonomic nervous system to bed rest. To test this hypothesis, nine healthy subjects underwent 2 wk of -6 degrees head-down bed rest. One year later, five of these same subjects underwent acute hypovolemia with furosemide to produce the same reductions in plasma volume observed after bed rest. We took advantage of power spectral and transfer function analysis to examine the dynamic relationship between blood pressure (BP) and R-R interval. We found that 1) there were no significant differences between these two interventions with respect to changes in numerous cardiovascular indices, including cardiac filling pressures, arterial pressure, cardiac output, or stroke volume; 2) normalized high-frequency (0.15-0.25 Hz) power of R-R interval variability decreased significantly after both conditions, consistent with similar degrees of vagal withdrawal; 3) transfer function gain (BP to R-R interval), used as an index of arterial-cardiac baroreflex sensitivity, decreased significantly to a similar extent after both conditions in the high-frequency range; the gain also decreased similarly when expressed as BP to heart rate x stroke volume, which provides an index of the ability of the baroreflex to alter BP by modifying systemic flow; and 4) however, the low-frequency (0.05-0.15 Hz) power of systolic BP variability decreased after bed rest (-22%) compared with an increase (+155%) after acute hypovolemia, suggesting a differential response for the regulation of vascular resistance (interaction, P < 0.05). The similarity of changes in the reflex control of the circulation under both conditions is consistent with the hypothesis that reductions in plasma volume may be largely responsible for the observed changes in cardiac

  8. LBNP/ergometer effects on female cardiovascular and muscle deconditioning in 15d head-down bed rest

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Jie

    2012-07-01

    Female has already been an important part of astronaut corps but gender characteristics in weightlessness and countermeasure effects still not clearly elucidated. In this study the LBNP/Ergometer effects on female cardiovascular deconditioning and muscle atrophy in 15d head-down bed rest were explored. 22 female university students were recruited as volunteers that participated in the 15d head-down bed rest. They were divided into control group (Con,n=8), LBNP exercise group (LBNP,n=7) and LBNP combined with ergometer exercise group (LBNP+Ergo, n=7). Grade negative pressures of -10,-20,-30,-40mmHg 20 or 55min were used in LBNP exercise. In ergometer exercises the subjects must maintain 60-80% VO2peak of pre-bed rest at pedal speed of about 70cycle/min for 15min and the entire exercise duration was 30min. LBNP were performed at 6th,8th,10th,12th,and 13th day and Ergometer were operated at 4th,5th,7th,9th,11th day during bed rest. Before and after bed rest, cardiovascular tilt test were performed to evaluate orthostatic intolerance, supine cycle ergometer were used to test the cardiopulmonary function, MRI tests were operated to examine the volume variations of leg muscle groups and isokinetic test were given to test the muscle strength and endurance of knee. 40% of female subjects did not pass the tilt table test after bed rest and exercises made no difference. Compared with pre-BR, VO2max and VO2max /body weight, VO2/HRmax, maximal power and duration significantly decreased in CON group and LBNP group. For the ERGO+LBNP group, there were no visible different in the parameters of cardiopulmonary function except that maximal power and duration decreased. Muscle maximal voluntary contraction and muscle (quadriceps, rectus femoris, gastrocnemius and soleus) volume decreasing in non-predominant leg was larger in Con group than in LBNP+Ergo group. It is suggested that LBNP combined with ergometer in some degrees can counteract the cardiovascular and muscle deconditioning

  9. Medical Monitoring during Short Radius Centrifugation in Bed-rested Subjects

    NASA Technical Reports Server (NTRS)

    Reinertson, Randal; Nelson, Victor; Aunon, Serena; Schlegel, Todd; Paloski, William

    2007-01-01

    The artificial gravity pilot project was designed to investigate the efficacy of daily exposure to a Gz acceleration gradient for counteracting the physiologic decrements induced by prolonged bed rest. A short radius centrifuge was used to produce a Gz gradient such that 1 g was applied at the level of the subject s heart and 2.5 g at the feet. For inclusion in the study, subjects were required to complete a 75-minute screening spin on the centrifuge. During the study, each active treatment subject was scheduled for a 60-minute spin each day for 20 consecutive days. During centrifugation, subjects were continuously monitored by a physician for signs and symptoms of pre-syncope, motion sickness, arrhythmias, joint/muscle pain and any other unanticipated problems. The physician was also present to provide emergency care in the case of a medical emergency. Cameras mounted on the centrifuge were used to provide a means of observing the subject s face and torso. Audio communication was continuously maintained. Other monitoring tools included two-lead EKG tracings, pulse oximetry, intermittent sphygmomanometer readings, lights in the peripheral visual field, and continuous blood pressure readout from a tonometry device. Thirty screening runs were attempted using twenty-seven subjects. Seven of these runs were terminated early for symptoms of pre-syncope, motion sickness, or GI distress. A total of eight subjects completed the active treatment arm of the study. Of the 160 centrifuge runs that were scheduled for these eight treatment subjects, 152 were completed, seven were terminated early, and one was not attempted. Of the seven early terminations, four were related to symptoms of pre-syncope, one to leg pain, one to GI discomfort, and one to equipment failure. Three terminations for adverse symptoms occurred on the first treatment day. Three terminations occurred on day nineteen of treatment and within 24 hours after scheduled soleus and quadriceps muscle biopsies. We

  10. Effects of Artificial Gravity and Bed Rest on Spatial Orientation and Balance Control

    NASA Technical Reports Server (NTRS)

    Paloski, William H.; Moore, S. T.; Feiveson, A. H.; Taylor, L. C.

    2007-01-01

    While the vestibular system should be well-adapted to bed rest (a condition it experiences approximately 8/24 hrs each day), questions remain regarding the degree to which repeated exposures to the unusual gravito-inertial force environment of a short-radius centrifuge might affect central processing of vestibular information used in spatial orientation and balance control. Should these functions be impaired by intermittent AG, its feasibility as a counter-measure would be diminished. We, therefore, examined the effects of AG on spatial orientation and balance control in 15 male volunteers before and after 21 days of 6 HDT bed rest (BR). Eight of the subjects were treated with daily 1hr AG exposures (2.5g at the feet; 1.0g at the heart) aboard a short radius (3m) centrifuge, while the other seven served as controls (C). Spatial orientation was assessed by measures of ocular counter-rolling (OCR; rotation of the eye about the line of sight, an otolith-mediated reflex) and subjective visual vertical (SVV; perception of the spatial upright). Both OCR and SVV measurements were made with the subject upright, lying on their left sides, and lying on their right sides. OCR was measured from binocular eye orientation recordings made while the subjects fixated for 10s on a point target directly in front of the face at a distance of 1 m. SVV was assessed by asking subjects (in the dark) to adjust to upright (using a handheld controller) the orientation of a luminous bar randomly perturbed (15) to either side of the vertical meridian. Balance control performance was assessed using a computerized dynamic posturography (CDP) protocol similar to that currently required for all returning crew members. During each session, the subjects completed a combination of trials of sensory organization test (SOT) 2 (eyes closed, fixed platform) and SOT 5 (eyes closed, sway-referenced platform) with and without static and dynamic pitch plane head movements (plus or minus 20 deg., dynamic

  11. The Artificial Gravity Bed Rest Pilot Project: Effects on Knee Extensor and Plantar Flexor Muscle Groups

    NASA Technical Reports Server (NTRS)

    Caiozzo, V. J.; Haddad, F.; Lee, S.; Baker, M.; Baldwin, K. M.

    2007-01-01

    The goal of this project was to examine the effects of artificial gravity (2.5 g) on skeletal muscle strength and key anabolic/catabolic markers known to regulate muscle mass. Two groups of subjects were selected for study: 1) a 21 day-bed rest (BR) control (C) group (N=7); and 2) an AG group (N=8), which was exposed to 21 days of bed-rest plus daily 1 hr exposures to AG (2.5 g). This particular experiment was part of an integrated AG Pilot Project sponsored by NASA/Johnson Space Center. The in vivo torque-velocity relationships of the knee extensors and plantar flexors of the ankle were determined pre and post treatment. Also, pre- and post treatment biopsy samples were obtained from both the vastus lateralis and soleus muscles and were used, in part, for a series of analyses on gene expression (mRNA abundance) of key factors implicated in the anabolic versus catabolic state of the muscle. Post/Pre toque-velocity determinations revealed greater decrements in knee extensor performance in the C versus AG group (P less than 0.04). The plantar flexor muscle group of the AG subjects actually demonstrated a net gain in torque-velocity relationship; whereas, in the C group the overall post/pre responses declined (AG vs C; P less than 0.001). Measurements of muscle fiber cross-sectional area (for both muscles) demonstrated a loss of approx. 20% in the C group while no losses were evident in the AG group. RT-PCR analyses of muscle biopsy specimens demonstrated that markers of growth and cytoskeletal integrity (IGF-1, IGF-1 BP4, mechano growth factor, total RNA, and pro-collagen 3a) were higher in the AG group, whereas catabolic markers (myostatin and atrogen) were elevated in the C group. Importantly, these patterns were seen in both muscles. Based on these observations we conclude that paradigms of AG have the potential to maintain the functional, biochemical, and structural homeostasis of skeletal muscle in the face of chronic unloading states. These findings also

  12. Ocular Outcomes Evaluation in a 14-Day Head-Down Bed Rest Study

    PubMed Central

    Taibbi, Giovanni; Cromwell, Ronita L.; Zanello, Susana B.; Yarbough, Patrice O.; Ploutz-Snyder, Robert J.; Godley, Bernard F.; Vizzeri, Gianmarco

    2014-01-01

    Introduction We evaluated ocular outcomes in a 14-day head-down tilt (HDT) bed rest (BR) study designed to simulate the effects of microgravity on the human body. Methods Healthy subjects were selected using NASA standard screening procedures. Standardized NASA BR conditions were implemented (e.g., strict sleep-wake cycle, standardized diet, 24-hour-a-day BR, continuous video monitoring). Subjects maintained a 6° HDT position for 14 consecutive days. Weekly ophthalmological examinations were performed in the sitting (pre/post-BR) and HDT (in-bed phase) positions. Equivalency tests with optimal-alpha techniques evaluated pre/post-BR differences in best-corrected visual acuity (BCVA), spherical equivalent, intraocular pressure (IOP), Spectral-domain OCT retinal nerve fiber layer thickness (RNFLT), optic disc and macular parameters. Results 16 subjects (12 men and 4 women) were enrolled. Nearly all ocular outcomes were within our predefined clinically relevant thresholds following HDTBR, except near BCVA (pre/post-BR mean difference: −0.06 logMAR), spherical equivalent (−0.30 D), Tonopen XL IOP (+3.03 mmHg) and Spectralis OCT average (+1.14 μm), temporal-inferior (+1.58 μm) and nasal-inferior RNFLT (+3.48 μm). Modified Amsler grid, red dot test, confrontational visual field and color vision were within normal limits throughout. No changes were detected on stereoscopic color fundus photography. Discussion A few functional and structural changes were detected after 14-day HDTBR, notably an improved BCVA possibly due to learning effect and RNFL thickening without signs of optic disc edema. In general, 6° HDTBR determined a small non-progressive IOP elevation, which returned to baseline levels post-BR. Further studies with different BR duration and/or tilt angle are warranted to investigate microgravity-induced ophthalmological changes. PMID:25245897

  13. Effect of leg exercise training on vascular volumes during 30 days of 6 deg head-down bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Vernikos, J.; Wade, C. E.; Barnes, P. R.

    1992-01-01

    In order to investigate the effects of leg exercise training on vascular volumes during 30 d of 6-deg head-down bed rest, plasma and red cell volumes, body density, and water balance were measured in 19 men confined to bed rest (BR). One group had no exercise training (NOE), another near-maximal variable-intensity isotonic exercise (ITE) for 60 min/d, and the third near-maximal intermittent isokinetic exercise (IKE) for 60 min/d. Mean energy costs for the NOE, IKE, and ITE regimens were determined. Body densities within groups and mean urine volumes between groups were unchanged during BR. Changes in red cell volume followed changes in plasma volume. There was close coupling between resting plasma volume and plasma protein and osmotic content. It is argued that the ITE training protocol is better than the IKE protocol for maintaining plasma volume during prolonged exposure to BR.

  14. Evaluation of potentially significant increase of lead in the blood during long-term bed rest and space flight.

    PubMed

    Kondrashov, Vladislav; Rothenberg, Stephen J; Chettle, David; Zerwekh, Joseph

    2005-02-01

    We address a gap in the knowledge of lead turnover under conditions of prolonged bed rest and microgravity by developing a quantitative model of the amount of lead returned to blood circulation from bone. We offer the hypothesis that skeletal unloading, such as typically occurs during extended bed rest or microgravity, will result in bone lead being released to the blood, as has already been demonstrated in the case of calcium. We use initial bone lead concentrations to develop predictive models of blood lead elevation. Our theoretical calculations with typical bone lead loads measured in today's 40-60-year-old generation, suggest that the estimated blood lead concentrations in long duration (e.g., 100 days) space flight could average between 20 and 40 microg dl(-1), a range with well-established toxic effects. For a similar duration of bed rest, estimated blood lead concentration could be as high as 10-20 microg dl(-1), which is a level of concern, particularly if we consider females of childbearing age. The preliminary experimental results were obtained under multi-institutional collaborations, with the main outcome received from an on-going bed rest study, Prevention of Microgravity-Induced Stone Risk by KMgCitrate, conducted at the General Clinical Research Center (GCRC) of the University of Texas Southwestern Medical Center, Dallas. Based on theoretical modeling and some preliminary experimental results, this concept may have important clinical implications by allowing prediction of the magnitude of blood lead elevation, thereby establishing the means to prevent lead toxicity during long duration space flight of astronauts and in conditions of prolonged bed rest such as complicated pregnancy, spinal cord injury induced paralysis and comatose patients. PMID:15742874

  15. Alendronate and Resistive Exercise Countermeasures Against Bed Rest-Induced Bone Loss: Biochemical Markers of Bone and Calcium Metabolism

    NASA Technical Reports Server (NTRS)

    Smith, Scott M.; Nillen, Jeannie L.; Davis-Street, Janis E.; DeKerlegand, Diane E.; LeBlanc, Adrian; Shackelford, Linda C.

    2001-01-01

    Weightlessness-induced bone loss must be counteracted to ensure crew health during extendedduration space missions. Studies were conducted to assess two bone loss countermeasures in a ground-based model: horizontal bed rest. Following a 3-wk ambulatory adaptation period, male and female subjects (aged 21-56 y) completed a 17-wk bed rest protocol. Subjects were assigned to one of three treatments: alendronate (ALEN; 10 mg/d, n=6), resistive exercise (RE; 1.5 h/d, 6 d/wk, n=8), or control (CN; no countermeasure, n=8). Dietary intake was adjusted to maintain body weight. Endocrine and biochemical indices were measured in blood and urine using standard laboratory methods. All data reported are expressed as percent change from individual pre-bedrest data. Serum calcium changed little during bed rest, and tended to decrease (4-8%) in ALEN subjects. In RE subjects, bone alkaline phosphatase and osteocalcin were increased >65 and >30%, respectively, during bed rest, while these were unchanged or decreased in ALEN and CN subjects. Urinary calcium was increased 50% in CN subjects, but was unchanged or decreased in both ALEN and RE groups. Urinary n-telopeptide excretion was increased 40-50% in CN and RE subjects, but decreased 20% in ALEN subjects. Pyridinium crosslink and deoxypyridinoline excretion were increased 20-50% during bed rest. These data suggest that RE countermeasures are effective at increasing markers of bone formation in an analog of weightlessness, while ALEN reduces markers of bone resorption. Counteracting the bone loss of space flight may require both pharmacologic and exercise countermeasures.

  16. Focal Gray Matter Plasticity as a Function of Long Duration Head Down Tilted Bed Rest: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Koppelmans, V.; Erdeniz, B.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Seidler, R. D.

    2014-01-01

    Long duration spaceflight (i.e., 22 days or longer) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes are solely related to peripheral changes from reduced vestibular stimulation, body unloading, body fluid shifts or that they may be related to structural and functional brain changes is yet unknown. However, a recent study reported associations between microgravity and flattening of the posterior eye globe and protrusion of the optic nerve [1] possibly as the result of increased intracranial pressure due to microgravity induced bodily fluid shifts [3]. Moreover, elevated intracranial pressure has been related to white matter microstructural damage [2]. Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning. Long duration head down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system [4]. Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on brain structure [5]. Here we present results of the first six subjects. Six subjects were assessed at 12 and 7 days before-, at 7, 30, and 70 days in-, and at 8 and 12 days post 70 days of bed rest at the NASA bed rest facility in UTMB, Galveston, TX, USA. At each time point structural MRI scans (i.e., high resolution T1-weighted imaging and Diffusion Tensor Imaging (DTI)) were obtained using a 3T Siemens scanner. Focal changes over time in gray matter density were assessed using the voxel based morphometry 8 (VBM8) toolbox under SPM

  17. Lower-body negative-pressure exercise and bed-rest-mediated orthostatic intolerance

    NASA Technical Reports Server (NTRS)

    Schneider, Suzanne M.; Watenpaugh, Donald E.; Lee, Stuart M C.; Ertl, Andrew C.; Williams, W. Jon; Ballard, Richard E.; Hargens, Alan R.

    2002-01-01

    PURPOSE: Supine, moderate exercise is ineffective in maintaining orthostatic tolerance after bed rest (BR). Our purpose was to test the hypothesis that adding an orthostatic stress during exercise would maintain orthostatic function after BR. METHODS: Seven healthy men completed duplicate 15-d 6 degrees head-down tilt BR using a crossover design. During one BR, subjects did not exercise (CON). During another BR, subjects exercised for 40 min.d(-1) on a supine treadmill against 50-60 mm Hg LBNP (EX). Exercise training consisted of an interval exercise protocol of 2- to 3-min intervals alternating between 41 and 65% (.)VO(2max). Before and after BR, an LBNP tolerance test was performed in which the LBNP chamber was decompressed in 10-mm Hg stages every 3 min until presyncope. RESULTS: LBNP tolerance, as assessed by the cumulative stress index (CSI) decreased after BR in both the CON (830 +/- 144, pre-BR vs 524 +/- 56 mm Hg.min, post-BR) and the EX (949 +/- 118 pre-BR vs 560 +/- 44 mm Hg.min, post-BR) conditions. However, subtolerance (0 to -50 mm Hg LBNP) heart rates were lower and systolic blood pressures were better maintained after BR in the EX condition compared with CON. CONCLUSION: Moderate exercise performed against LBNP simulating an upright 1-g environment failed to protect orthostatic tolerance after 15 d of BR.

  18. Insulin and glucose responses during bed rest with isotonic and isometric exercise

    NASA Technical Reports Server (NTRS)

    Dolkas, C. B.; Greenleaf, J. E.

    1977-01-01

    The effects of daily intensive isotonic (68% maximum oxygen uptake) and isometric (21% maximum extension force) leg exercise on plasma insulin and glucose responses to an oral glucose tolerance test (OGTT) during 14-day bed-rest (BR) periods were investigated in seven young healthy men. The OGTT was given during ambulatory control and on day 10 of the no-exercise, isotonic, and isometric exercise BR periods during the 15-wk study. The subjects were placed on a controlled diet starting 10 days before each BR period. During BR, basal plasma glucose concentration remained unchanged with no exercise, but increased (P less 0.05) to 87-89 mg/100 ml with both exercise regimens on day 2, and then fell slightly below control levels on day 13. The fall in glucose content during BR was independent of the exercise regimen and was an adjustment for the loss of plasma volume. The intensity of the responses of insulin and glucose to the OGTT was inversely proportional to the total daily energy expenditure during BR. It was estimated that at least 1020 kcal/day must be provided by supplemental exercise to restore the hyperinsulinemia to control levels.

  19. Temporal Changes in Left Ventricular Mechanics: Impact of Bed Rest and Exercise

    NASA Technical Reports Server (NTRS)

    Scott, J. M.; Downs, M.; Ploutz-Snyder, L. L.

    2014-01-01

    The use of more sensitive and specific echocardiographic techniques such as speckle tracking imaging may address the current limitations of conventional cardiac imaging techniques to provide insight into the extent and time course of cardiac deconditioning following spaceflight or headdown tilt bed rest (HDTBR). METHODS Speckle tracking assessment of longitudinal, radial, and circumferential strain and twist was used to evaluate the impact of 70 days of HDTBR (n=7) and HDTBR + exercise (n=11) on temporal changes in LV mechanics. Echocardiograms were performed pre (BR-2), during (BR31, 70), and following (BR+4hr) HDTBR. Repeated measures ANOVA was used to evaluate the effect of HDTBR on cardiac variables in control and exercise subjects. RESULTS After sedentary HDTBR, longitudinal (-19.0 +/- 1.8% vs. -14.9 +/- 2.4%) and radial (15.0 +/- 1.9% vs. 11.3 +/- 2.2%) strain and twist (18.0 +/- 4.0deg vs. 17.0 +/- 3.6deg) were significantly impaired. In contrast, exercise preserved LV mechanics, and there were non-significant improvements from BR-2 to BR70 in longitudinal strain (-18.7 +/- 1.5% vs. -20.4 +/- 2.7%), radial strain (13.2 +/- 2.4% vs. 14.2 +/- 1.6%), and twist (16.3 +/- 3.6deg vs. 18.6 +/- 5.9deg). CONCLUSIONS Using speckle tracking echocardiography provides important new insights into temporal changes in LV mechanics during disuse and exercise training.

  20. Enhanced physiological tremor deteriorates plantar flexor torque steadiness after bed rest.

    PubMed

    Mulder, Edwin R; Horstman, Astrid M; Gerrits, Karin; Massa, Mark; Kleine, Bert U; de Haan, Arnold; Belavý, Daniel L; Felsenberg, Dieter; Zwarts, Machiel; Stegeman, Dick F

    2011-04-01

    This study evaluated the effectiveness of resistance training to preserve submaximal plantar flexor (PF) torque steadiness following 60 days of bed rest (BR). Twenty-two healthy male subjects underwent either BR only (CTR, n=8), or BR plus resistance training (RT, n=14). The magnitude of torque fluctuations during steady submaximal isometric PF contractions (20%, 40%, 60% and 80% of maximum) were assessed before and after BR. Across contraction intensities, torque fluctuations (coefficient of variation, CV) increased more (P<0.05) after BR for CTR (from 0.31±0.10 to 0.92±0.63; P<0.001), than for RT (from 0.30±0.09 to 0.54±0.27; P<0.01). A shift in the spectral content of torque fluctuations towards increased rhythmic activity between 6.5 and 20Hz was observed in CTR only (P<0.05). H-reflex amplitude (H(max)/M(max) ratio) declined across groups from 0.57±0.18 before BR to 0.44±0.14 following BR (P<0.01) without correlation to CV. The present study showed that increased torque fluctuation after BR resulted from enhanced physiological tremor. Resistance training prevented the spectral shift in isometric PF torque fluctuation and offset ∼50% of the decline in performance associated with long-term BR.

  1. Effects of prolonged head-down bed rest on physiological responses to moderate hypoxia

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Roach, R. C.; Selland, M. A.; Scotto, P.; Greene, E. R.; Luft, U. C.

    1993-01-01

    To determine the effects of hypoxia on physiological responses to simulated zero-gravity cardiopulmonary and fluid balance measurements were made in 6 subjects before and during 5-degree head-down bed rest (HDBR) over 8 d at 10,678 ft and a second time at this altitude as controls (CON). The V-dot(O2)(max) increased by 9 percent after CON, but fell 3 percent after HDBR. This reduction in work capacity during HDBR could be accounted for by inactivity. The heart rate response to a head-up tilt was greatly enhanced following HDBR, while mean blood pressure was lower. No significant negative impact of HDBR was noted on the ability to acclimatize to hypoxia in terms of pulmonary mechanics, gas exchange, circulatory or mental function measurements. No evidence of pulmonary interstitial edema or congestion was noted during HDBR at the lower PIO2 and blood rheology properties were not negatively altered. Symptoms of altitude illness were more prevalent, but not marked, during HDBR and arterial blood gases and oxygenation were not seriously effected by simulated microgravity. Declines in base excess with altitude were similar in both conditions. The study demonstrated a minimal effect of HDBR on the ability to adjust to this level of hypoxia.

  2. Effect of intermittent standing and walking on physiological changes induced by head-down bed rest

    NASA Technical Reports Server (NTRS)

    Vernikos, J.; Ludwig, D. A.; Ertl, A. C.; Wade, C. E.; Keil, L.; OHara, D.

    1994-01-01

    Continuous exposure to gravity may not be necessary to prevent compromised physiological function resulting from exposure to microgravity. However, minimum gravity (G) exposure requirements, effectiveness of passive Gz versus activity in a G field, and optimal G stimulus amplitude, duration, and frequency are unknown. To partially address these questions, a 4-day, 6 degree head-down bed rest (HDBR) study (one ambulatory control day, 4 full HDBR days, one recovery day) was conducted. Nine males, 30-50 yr, were subjected to four different +1 Gz (head-foot) exposure protocols (periodic standing or controlled walking for 2 or 4 h/day in 15 min doses), plus a continuous HDBR (0 Gz) control. Standing 4 h completely prevented and standing 2 h partially prevented post-HDBR orthostatic intolerance. Both walking conditions (2 h and 4 h) attenuated the decrease in peak VO2 and prevented the increased urinary Ca2+ excretion associated with HDBR. Both 4 h conditions (standing and walking) attenuated plasma volume loss during HDBR. It was concluded that various physiological systems benefit differentially from passive +1 Gz or activity in +1 Gz and the duration (2 h vs. 4 h) of the stimulus may be an important moderating factor.

  3. Body fluid alterations during head-down bed rest in men at moderate altitude

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Roach, R. C.; Selland, M. A.; Scotto, P.; Luft, F. C.; Luft, U. C.

    1993-01-01

    To determine the effects of hypoxia on fluid balance responses to simulated zero-gravity, measurements were made in six subjects before and during -5 deg continuous head-down bed rest (HDBR) over 8 d at 10,678 ft. The same subjects were studied again at this altitude without HDBR as a control (CON) using a cross-over design. During this time, they maintained normal upright day-time activities, sleeping in the horizontal position at night. Fluid balance changes during HDBR in hypoxia were more pronounced than similar measurements previously reported from HDBR studies at sea level. Plasma volume loss was slightly greater and the diuresis and natriuresis were doubled in magnitude as compared to previous studies in normoxia and sustained for 4 d during hypoxia. These changes were associated with an immediate but transient rise in plasma atrial natriuretic peptide (ANP) to day 4 of 140 percent in HDBR and 41 percent in CON (p less than 0.005), followed by a decline towards baseline. Differences were less striking between HDBR and CON for plasma antidiuretic hormone and aldosterone, which were transiently reduced by HDBR. Plasma catecholamines showed a similar pattern to ANP in both HDBR and CON, suggesting that elevated ANP and catecholamines together accounted for the enhanced fluid shifts with HDBR during hypoxia.

  4. Long Duration Head Down Tilt Bed Rest Effects on Neurocognitive Performance: Extent, Longevity and Neural Bases

    NASA Technical Reports Server (NTRS)

    Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Cassady, K.; Yuan, P.; Kofman, I. S.; De Dios, Y. E.; Szecsy, D. L.; Riascos-Castaneda, R F.; Wood, S. J.

    2016-01-01

    We are conducting ongoing experiments in which we are performing structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations following a six month International Space Station mission and following 70 days exposure to a spaceflight analog, head down tilt bedrest. Our central hypothesis is that measures of brain structure, function, and network integrity will change from pre to post intervention (spaceflight, bedrest). Moreover, we predict that these changes will correlate with indices of cognitive, sensory, and motor function in a neuroanatomically selective fashion. Our interdisciplinary approach utilizes cutting edge neuroimaging techniques and a broad ranging battery of sensory, motor, and cognitive assessments that will be conducted preflight, during flight, and post flight to investigate potential neuroplastic and maladaptive brain changes in crewmembers following long-duration spaceflight. Success in this endeavor would 1) result in identification of the underlying neural mechanisms and operational risks of spaceflight-induced changes in behavior, and 2) identify whether a return to normative behavioral function following re-adaptation to Earth's gravitational environment is associated with a restitution of brain structure and function or instead is supported by substitution with compensatory brain processes. In this presentation I will provide an overview of changes in behavior, brain structure, and brain function that we are observing in our bed rest participants in comparison to normative control subjects.

  5. Comparison of a space shuttle flight (STS-78) and bed rest on human muscle function

    NASA Technical Reports Server (NTRS)

    Trappe, S. W.; Trappe, T. A.; Lee, G. A.; Widrick, J. J.; Costill, D. L.; Fitts, R. H.

    2001-01-01

    The purpose of this investigation was to assess muscle fiber size, composition, and in vivo contractile characteristics of the calf muscle of four male crew members during a 17-day spaceflight (SF; Life and Microgravity Sciences Spacelab Shuttle Transport System-78 mission) and eight men during a 17-day bed rest (BR). The protocols and timelines of these two investigations were identical, therefore allowing for direct comparisons between SF and the BR. The subjects' age, height, and weight were 43 +/- 2 yr, 183 +/- 4 cm, and 86 +/- 3 kg for SF and 43 +/- 2 yr, 182 +/- 3 cm, and 82 +/- 4 kg for BR, respectively. Calf muscle strength was examined before SF and BR; on days 2, 8, and 12 during SF and BR; and on days 2 and 8 of recovery. Muscle biopsies were obtained before and within 3 h after SF (gastrocnemius and soleus) and BR (soleus) before reloading. Maximal isometric calf strength and the force-velocity characteristics were unchanged with SF or BR. Additionally, neither SF nor BR had any effect on fiber composition or fiber size of the calf muscles studied. In summary, no changes in calf muscle strength and morphology were observed after the 17-day SF and BR. Because muscle strength is lost during unloading, both during spaceflight and on the ground, these data suggest that the testing sequence employed during the SF and BR may have served as a resistance training countermeasure to attenuate whole muscle strength loss.

  6. WISE 2005-2006: 60-days of Head-Down Bed Rest Increases the Incidence of Menstrual Cycle Disruption

    NASA Astrophysics Data System (ADS)

    Wade, Charles

    Objective: It has been suggested that acute bed rest of short duration (11 days) disrupts the menstrual cycle of healthy subjects. Furthermore, use of countermeasures such as heavy exercise or dietary manipulations may adversely effect the menstrual cycle. We hypothesized that bed rest of 60 days and the use of countermeasures would increase the incidence of disruption of the menstrual cycle (MC). Methods: Twenty-four healthy subjects with a mean age of 32±0.8 yr, body mass of 59±0.8 kg and MC lengths of 25-32 days were enrolled. Three months prior to the study subjects did not use hormonal birth control methods. Subjects were assigned to one of three groups (n=8 per group): control, exercise countermeasures, and dietary countermeasures. MC lengthening was defined as an increase in duration of 10 or more days. Analysis was performed accounting for the effects of bedrest as well as treatment group. Results: Effects of countermeasures were not significant in the present analysis. After the conclusion of the study, subjects were classified as either normal (N; n=16) or oligomenorrhea (O; n=8) as determined by MC length during the pre-bed rest (PB) and bed rest (BR) periods. During the control period prior to bed rest one subject (4%) had an increase MC length. During the control period the average MC length was 31±0.8 days with a leutinizing hormone (LH) surge 12±0.8 days prior to menses. The duration of menses was 4±0.4 days. During BR there was an increase to 33% (p¡0.05) in the number of subjects having MC lengthening. In these subjects the mean length was increased from 31±0.9 to 62±8.2 days (p¡0.05). There was no change in the period from the LH surge prior to the next menses, 11±0.8 days, or duration of menses, 4±0.2 days. Plasma LH, follicle stimulating hormone (FSH), prolacin (PRL), progesterone (PRG), estradiol (E2), dehydroepiandrosterone sulfate (DHEA-S), aldosterone (Aldo), testosterone (T) and cortisol (C) were measured during PB, BR, early

  7. PlanHab: hypoxia exaggerates the bed-rest-induced reduction in peak oxygen uptake during upright cycle ergometry.

    PubMed

    Keramidas, Michail E; Kölegård, Roger; Mekjavic, Igor B; Eiken, Ola

    2016-08-01

    The study examined the effects of hypoxia and horizontal bed rest, separately and in combination, on peak oxygen uptake (V̇o2 peak) during upright cycle ergometry. Ten male lowlanders underwent three 21-day confinement periods in a counterbalanced order: 1) normoxic bed rest [NBR; partial pressure of inspired O2 (PiO2 ) = 133.1 ± 0.3 mmHg]; 2) hypoxic bed rest (HBR; PiO2 = 90.0 ± 0.4 mmHg), and 3) hypoxic ambulation (HAMB; PiO2 = 90.0 ± 0.4 mmHg). Before and after each confinement, subjects performed two incremental-load trials to exhaustion, while inspiring either room air (AIR), or a hypoxic gas (HYPO; PiO2 = 90.0 ± 0.4 mmHg). Changes in regional oxygenation of the vastus lateralis muscle and the frontal cerebral cortex were monitored with near-infrared spectroscopy. Cardiac output (CO) was recorded using a bioimpedance method. The AIR V̇o2 peak was decreased by both HBR (∼13.5%; P ≤ 0.001) and NBR (∼8.6%; P ≤ 0.001), with greater drop after HBR (P = 0.01). The HYPO V̇o2 peak was also reduced by HBR (-9.7%; P ≤ 0.001) and NBR (-6.1%; P ≤ 0.001). Peak CO was lower after both bed-rest interventions, and especially after HBR (HBR: ∼13%, NBR: ∼7%; P ≤ 0.05). Exercise-induced alterations in muscle and cerebral oxygenation were blunted in a similar manner after both bed-rest confinements. No changes were observed in HAMB. Hence, the bed-rest-induced decrease in V̇o2 peak was exaggerated by hypoxia, most likely due to a reduction in convective O2 transport, as indicated by the lower peak values of CO. PMID:27342877

  8. Ocular Outcomes Comparison Between 14- and 70-day Head-down Tilt Bed Rest

    NASA Technical Reports Server (NTRS)

    Cromwell, R.L.; Taibbi, G.; Zanello, S.B.; Yarbough, P.O.; Ploutz-Snyder, R.J.; Vizzen, G.

    2015-01-01

    INTRODUCTION: Ophthalmological changes, including optic disc edema with optic nerve sheath distension, posterior globe flattening with hyperopic shift, choroidal folds and cotton wool spots have been detected in some astronauts involved in long-duration spaceflights. (sup 1) It is hypothesized that elevated intracranial pressure resulting from microgravity-induced cephalad fluid shifts may be responsible for most of these findings. Head-down tilt bed rest (HTDBR) is a ground-based microgravity analog which also produces cephalad fluid shifts. It is conceivable that prolonged HDTBR exposure may induce ocular changes similar to those experienced in microgravity. Therefore, the purpose of the present study was to compare structural and functional ocular outcomes between 14- and 70-day HDTBR in healthy human subjects. It is hypothesized that 70-d HDTBR induced ocular changes of greater magnitude as compared to 14-d HDTBR. METHODS: Two HDTBR studies were conducted at the NASA Flight Analogs Research Unit, located at The University of Texas Medical Branch at Galveston, TX. Identical NASA standard screening procedures and BR conditions (e.g., strict sleep-wake cycle, standardized diet, continuous video monitoring) were implemented in both studies. Participants spent 14 and/or 70 consecutive days in a 6deg HDT position and did not engage in exercise. Subjects received weekly ocular examinations before, during, and after HDTBR. Ocular testing included: distance and near best-corrected visual acuity (BCVA), cycloplegic refraction, intraocular pressure (IOP) measurement, color vision, red dot test, modified Amsler grid test, confrontational visual field, color fundus photography and Spectral-domain OCT scans of the macula and the optic disc. Pre/post HDTBR differences between the two studies will be evaluated for BCVA, spherical equivalent, IOP, retinal nerve fiber layer (RNFL) thickness and macular OCT parameters. RESULTS: 16 (12 males and 4 females) and 6 (5 males and 1

  9. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight.

  10. Clinical effects of thigh cuffs during a 7-day 6° head-down bed rest

    NASA Astrophysics Data System (ADS)

    Pavy-Le Traon, Anne; Maillet, Alain; Vasseur Clausen, Pascale; Custaud, Marc-Antoine; Alferova, Irina; Gharib, Claude; Fortrat, Jacques-Olivier

    2001-08-01

    Thigh cuffs are used by Russian cosmonauts to limit the fluid shift induced by space flight. A ground simulation using the head-down bed rest (HDBR) model was performed to assess the effects of thigh cuffs on clinical tolerance and orthostatic adaptation. 8 male healthy volunteers (32.4±1.9 years) participated twice in a 7-day HDBR — one time with thigh cuffs (worm daily from 9 am to 7 pm) (TC) and one time without (WTC). Orthostatic tolerance was assessed by a 10 minute stand test and by a LBNP test (5 min at -15, -30, -45 mmHg) before (BDC-1) and at the end of the HDBR period (R+1). Plasma volume was measured before and at the end of HDBR by the Evans blue dye dilution technique. Thigh cuffs limits headache due to fluid shift, as well as the loss in plasma volume (TC: -5.85±0.95%; WTC: -9.09±0.82%, p<0.05). The mean duration of the stand test (R+1) did not differ in the two group (TC 7.1±1.3 min; WTC 7.0±1.0 min). The increase in HR and decrease in diastolic blood pressure were slightly but significantly larger without thigh cuffs. Duration of the LBNP tests did not differ with thigh cuffs. Thigh cuffs limit the symptoms due to fluid shift and the loss in plasma volume. They partly reduced the increase in HR during orthostatic stress but had no effect on duration of orthostatic stress tests.

  11. Effect of dietary sodium on fluid/electrolyte regulation during bed rest

    NASA Technical Reports Server (NTRS)

    Williams, W. Jon; Schneider, Suzanne M.; Gretebeck, Randall J.; Lane, Helen W.; Stuart, Charles A.; Whitson, Peggy A.

    2003-01-01

    BACKGROUND: A negative fluid balance during bed rest (BR) is accompanied by decreased plasma volume (PV) which contributes to cardiovascular deconditioning. HYPOTHESIS: We hypothesized that increasing dietary sodium while controlling fluid intake would increase plasma osmolality (POSM), stimulate fluid conserving hormones, and reduce fluid/electrolyte (F/E) losses during BR; conversely, decreasing dietary sodium would decrease POSM, suppress fluid conserving hormones, and increase F/E losses. METHODS: We controlled fluid intake (30 ml x kg(-1) x d(-1)) in 17 men who consumed either a 4.0 +/- 0.06 g x d(-1) (174 mmol x d(-1)) (CONT; n = 6), 1.0 +/- 0.02 g x d(-1) (43 mmol x d(-1)) (LS; n = 6), or 10.0 +/- 0.04 g x d(-1) (430 mmol x d(-1)) (HS; n = 5) sodium diet before, during, and after 21 d of 6 degrees head-down BR. PV, total body water, urine volume and osmolality, POSM, and F/E controlling hormone concentrations were measured. RESULTS: In HS subjects, plasma renin activity (-92%), plasma/urinary aldosterone (-59%; -64%), and PV (-15.0%; 6.0 ml x kg(-1); p < 0.05) decreased while plasma atrial natriuretic peptide (+34%) and urine antidiuretic hormone (+24%) increased during BR (p < 0.05) compared with CONT. In LS, plasma renin activity (+166%), plasma aldosterone (+167%), plasma antidiuretic hormone (+19%), and urinary aldosterone (+335%) increased with no change in PV compared with CONT (p < 0.05). Total body water did not change in any of the subjects. CONCLUSIONS: Contrary to our hypothesis, increasing dietary sodium while controlling fluid intake during BR resulted in a greater loss of PV compared with the CONT subjects. Reducing dietary sodium while controlling fluid intake did not alter the PV response during BR compared with CONT subjects.

  12. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest.

    PubMed

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A; De Dios, Yiri E; Gadd, Nichole E; Wood, Scott J; Riascos, Roy; Kofman, Igor S; Bloomberg, Jacob J; Mulavara, Ajitkumar P; Seidler, Rachael D

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  13. Muscle Adaptations Following Short-Duration Bed Rest with Integrated Resistance, Interval, and Aerobic Exercise

    NASA Technical Reports Server (NTRS)

    Hackney, Kyle J.; Scott, Jessica M.; Buxton, Roxanne; Redd-Goetchius, Elizabeth; Crowell, J. Brent; Everett, Meghan E.; Wickwire, Jason; Ryder, Jeffrey W.; Bloomberg, Jacob J.; Ploutz-Snyder, Lori L.

    2011-01-01

    Unloading of the musculoskeletal system during space flight results in deconditioning that may impair mission-related task performance in astronauts. Exercise countermeasures have been frequently tested during bed rest (BR) and limb suspension; however, high-intensity, short-duration exercise prescriptions have not been fully explored. PURPOSE: To determine if a high intensity resistance, interval, and aerobic exercise program could protect against muscle atrophy and dysfunction when performed during short duration BR. METHODS: Nine subjects (1 female, 8 male) performed a combination of supine exercises during 2 weeks of horizontal BR. Resistance exercise (3 d / wk) consisted of squat, leg press, hamstring curl, and heel raise exercises (3 sets, 12 repetitions). Aerobic (6 d / wk) sessions alternated continuous (75% VO2 peak) and interval exercise (30 s, 2 min, and 4 min) and were completed on a supine cycle ergometer and vertical treadmill, respectively. Muscle volumes of the upper leg were calculated pre, mid, and post-BR using magnetic resonance imaging. Maximal isometric force (MIF), rate of force development (RFD), and peak power of the lower body extensors were measured twice before BR (averaged to represent pre) and once post BR. ANOVA with repeated measures and a priori planned contrasts were used to test for differences. RESULTS: There were no changes to quadriceps, hamstring, and adductor muscle volumes at mid and post BR time points compared to pre BR (Table 1). Peak power increased significantly from 1614 +/- 372 W to 1739 +/- 359 W post BR (+7.7%, p = 0.035). Neither MIF (pre: 1676 +/- 320 N vs. post: 1711 +/- 250 N, +2.1%, p = 0.333) nor RFD (pre: 7534 +/- 1265 N/ms vs. post: 6951 +/- 1241 N/ms, -7.7%, p = 0.136) were significantly impaired post BR.

  14. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  15. WISE-2005: Countermeasures to prevent muscle deconditioning during bed rest in women.

    PubMed

    Lee, Stuart M C; Schneider, Suzanne M; Feiveson, Alan H; Macias, Brandon R; Smith, Scott M; Watenpaugh, Donald E; Hargens, Alan R

    2014-03-15

    The objectives of this study were to evaluate the efficacy of two separate countermeasures, exercise and protein supplementation, to prevent muscle strength and lean tissue mass losses during 60 days of bed rest (BR) in women and whether countermeasure efficacy was influenced by pre-BR muscular fitness (strength, endurance, tissue mass). Twenty-four women were assigned to an exercise (EX, n = 8), a no-exercise control (CON, n = 8), or a no-exercise protein supplementation group (PROT, n = 8). EX performed supine treadmill exercise within lower body negative pressure 3-4 days/wk and maximal concentric and eccentric supine leg- and calf-press exercises 2-4 days/wk. PROT consumed a diet with elevated protein content compared with CON and EX (1.6 vs. 1.0 g·kg(-1)·day(-1)). Knee and calf isokinetic strength and endurance, isotonic leg-press strength, and leg lean mass were measured before and after BR. Post-BR knee extensor strength and endurance, ankle strength, and leg lean mass were significantly greater and leg-press strength tended to be higher in EX than in CON and PROT. Post-BR measures in PROT were not different than those in CON. Exercise countermeasure efficacy was less, and strength, endurance, and leg lean mass losses in CON and PROT were greater, in subjects who were more fit pre-BR. An exercise protocol combining resistive and aerobic exercise training protects against losses in strength, endurance, and leg lean mass in women during BR, while a nutritional countermeasure without exercise was not effective. Exercise countermeasures may require individualization to protect higher levels of strength and endurance. PMID:24458754

  16. Changes in plasma volume during bed rest: effects of menstrual cycle and estrogen administration.

    PubMed

    Fortney, S M; Beckett, W S; Carpenter, A J; Davis, J; Drew, H; LaFrance, N D; Rock, J A; Tankersley, C G; Vroman, N B

    1988-08-01

    Bed rest (BR) is associated with a decrease in plasma volume (PV), which may contribute to the impaired orthostatic and exercise tolerances seen immediately after BR. The purpose of this study was to determine whether increases in blood estrogen concentration, either during normal menstrual cycles or during exogenous estrogen administration, would attenuate this loss of PV. Nineteen healthy women (21-39 yr of age) completed the study. Twelve women underwent duplicate 11-day BR without estrogen supplementation. PV decreased significantly (P less than or equal to 0.01) during both BR's, from 2,531 +/- 113 to 2,027 +/- 102 ml during BR1 and from 2,445 +/- 115 to 2,244 +/- 96 ml during BR2. The women who began BR in the periovulatory stage of the menstrual cycle (n = 3), a time of elevated endogenous estrogens, had a transient delay in loss of PV during the first 5 days of BR. Women who began BR during other stages of the menstrual cycle (n = 17) showed the established trend to decrease PV primarily during the first few days of BR. Seven additional women underwent a single 12-day BR while taking estrogen supplementation (1.25 mg/day premarin). PV decreased during the first 4-5 days of BR, then returned toward the pre-BR level during the remainder of the BR (pre-BR PV, 2,525 +/- 149 ml; post-BR PV, 2,519 +/- 162 ml). Thus menstrual fluctuations in endogenous estrogens appear to have only small transient effects on the loss of PV during BR, whereas exogenous estrogen supplementation significantly attenuates PV loss.

  17. Impact of resistance exercise during bed rest on skeletal muscle sarcopenia and myosin isoform distribution

    NASA Technical Reports Server (NTRS)

    Bamman, M. M.; Clarke, M. S.; Feeback, D. L.; Talmadge, R. J.; Stevens, B. R.; Lieberman, S. A.; Greenisen, M. C.

    1998-01-01

    Because resistance exercise (REx) and bed-rest unloading (BRU) are associated with opposing adaptations, our purpose was to test the efficacy of REx against the effects of 14 days of BRU on the knee-extensor muscle group. Sixteen healthy men were randomly assigned to no exercise (NoEx; n = 8) or REx (n = 8). REx performed five sets of leg press exercise with 80-85% of one repetition maximum (1 RM) every other day during BRU. Muscle samples were removed from the vastus lateralis muscle by percutaneous needle biopsy. Myofiber distribution was determined immunohistochemically with three monoclonal antibodies against myosin heavy chain (MHC) isoforms (I, IIa, IIx). MHC distribution was further assessed by quantitative gel electrophoresis. Dynamic 1-RM leg press and unilateral maximum voluntary isometric contraction (MVC) were determined. Maximal neural activation (root mean squared electromyogram) and rate of torque development (RTD) were measured during MVC. Reductions (P < 0.05) in type I (15%) and type II (17%) myofiber cross-sectional areas were found in NoEx but not in REx. Electrophoresis revealed no changes in MHC isoform distribution. The percentage of type IIx myofibers decreased (P < 0.05) in REx from 9 to 2% and did not change in NoEx. 1 RM was reduced (P < 0.05) by 9% in NoEx but was unchanged in REx. MVC fell by 15 and 13% in NoEx and REx, respectively. The agonist-to-antagonist root mean squared electromyogram ratio decreased (P < 0.05) 19% in REx. RTD slowed (P < 0.05) by 54% in NoEx only. Results indicate that REx prevented BRU-induced myofiber atrophy and also maintained training-specific strength. Unlike spaceflight, BRU did not induce shifts in myosin phenotype. The reported benefits of REx may prove useful in prescribing exercise for astronauts in microgravity.

  18. 12 CFR 220.117 - Exception to 90-day rule in special cash account.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Exception to 90-day rule in special cash... Exception to 90-day rule in special cash account. (a) The Board of Governors has recently interpreted... stock in a special cash account with a member firm on Day 1. On Day 3 customer sold the same stock at...

  19. 19 CFR Annex Viii-A to Part 351 - Schedule for 90-Day Sunset Reviews

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Schedule for 90-Day Sunset Reviews VIII Annex VIII-A to Part 351 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE ANTIDUMPING AND COUNTERVAILING DUTIES Pt. 351, Annex VIII-A Annex VIII-A to Part 351—Schedule for 90-Day...

  20. 19 CFR Annex Viii-A to Part 351 - Schedule for 90-Day Sunset Reviews

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 3 2011-04-01 2011-04-01 false Schedule for 90-Day Sunset Reviews VIII Annex VIII-A to Part 351 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE ANTIDUMPING AND COUNTERVAILING DUTIES Pt. 351, Annex VIII-A Annex VIII-A to Part 351—Schedule for 90-Day...

  1. 19 CFR Annex Viii-A to Part 351 - Schedule for 90-Day Sunset Reviews

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 3 2013-04-01 2013-04-01 false Schedule for 90-Day Sunset Reviews VIII Annex VIII-A to Part 351 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE ANTIDUMPING AND COUNTERVAILING DUTIES Pt. 351, Annex VIII-A Annex VIII-A to Part 351—Schedule for 90-Day...

  2. 19 CFR Annex Viii-A to Part 351 - Schedule for 90-Day Sunset Reviews

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 3 2012-04-01 2012-04-01 false Schedule for 90-Day Sunset Reviews VIII Annex VIII-A to Part 351 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE ANTIDUMPING AND COUNTERVAILING DUTIES Pt. 351, Annex VIII-A Annex VIII-A to Part 351—Schedule for 90-Day...

  3. 19 CFR Annex Viii-A to Part 351 - Schedule for 90-Day Sunset Reviews

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 3 2014-04-01 2014-04-01 false Schedule for 90-Day Sunset Reviews VIII Annex VIII-A to Part 351 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE ANTIDUMPING AND COUNTERVAILING DUTIES Pt. 351, Annex VIII-A Annex VIII-A to Part 351—Schedule for 90-Day...

  4. [Effects of dehydration and infusion of blood substitutes on the hemostasis system in an experiment with 21-hour bed rest].

    PubMed

    Kuzichkin, D S; Baranov, M V; Kovalev, A S; Repenkova, L G; Morukov, B V; Markin, A A

    2009-01-01

    Eight volunteered male test-subjects (20-40 y.o.) took part in an experiment with 21-hr bed rest aimed to investigate trends in the hemostasis parameters (activated partial thromboplastin time, prothrombin time, thrombin time, fibrinogen, plasminogen, D-dimers, soluble fibrin-monomer complexes (SFMC), as well as antithrombin III (ATIII) and protein C (antiplasmin) activities) after diuretics-induced dehydration followed by intravenous infusion of colloid and crystalloid solutions. It was shown that noncompensible dehydration during bed rest does not lead to noteworthy alterations in the procoagulating component of hemostasis. Intravenous infusion of blood substituting sterofundin (crystalloid) and venofundin (colloid) to the bedrested human subjects accelerated coagulation within the physiological norm. In all series of the experiment ATIII was suppressed and plasminogen content went down causing growth in SFMC. Fibrinogen concentration remained essentially unchanged pointing to the absence of acute reaction of organism to the experimental conditions.

  5. Countermeasures against lumbar spine deconditioning in prolonged bed rest: resistive exercise with and without whole body vibration.

    PubMed

    Belavý, Daniel L; Armbrecht, Gabriele; Gast, Ulf; Richardson, Carolyn A; Hides, Julie A; Felsenberg, Dieter

    2010-12-01

    To evaluate the effect of short-duration, high-load resistive exercise, with and without whole body vibration on lumbar muscle size, intervertebral disk and spinal morphology changes, and low back pain (LBP) incidence during prolonged bed rest, 24 subjects underwent 60 days of head-down tilt bed rest and performed either resistive vibration exercise (n = 7), resistive exercise only (n = 8), or no exercise (n = 9; 2nd Berlin Bed-Rest Study). Discal and spinal shape was measured from sagittal plane magnetic resonance images. Cross-sectional areas (CSAs) of the multifidus, erector spinae, quadratus lumborum, and psoas were measured on para-axial magnetic resonance images. LBP incidence was assessed with questionnaires at regular intervals. The countermeasures reduced CSA loss in the multifidus, lumbar erector spinae and quadratus lumborum muscles, with greater increases in psoas muscle CSA seen in the countermeasure groups (P ≤ 0.004). There was little statistical evidence for an additional effect of whole body vibration above resistive exercise alone on these muscle changes. Exercise subjects reported LBP more frequently in the first week of bed rest, but this was only significant in resistive exercise only (P = 0.011 vs. control, resistive vibration exercise vs. control: P = 0.56). No effect of the countermeasures on changes in spinal morphology was seen (P ≥ 0.22). The results suggest that high-load resistive exercise, with or without whole body vibration, performed 3 days/wk can reduce lumbar muscle atrophy, but further countermeasure optimization is required.

  6. Effects of 14 days of head-down tilt bed rest on cutaneous vasoconstrictor responses in humans

    NASA Technical Reports Server (NTRS)

    Wilson, Thad E.; Shibasaki, Manabu; Cui, Jian; Levine, Benjamin D.; Crandall, Craig G.

    2003-01-01

    This study tested the hypothesis that head-down tilt bed rest (HDBR) reduces adrenergic and nonadrenergic cutaneous vasoconstrictor responsiveness. Additionally, an exercise countermeasure group was included to identify whether exercise during bed rest might counteract any vasoconstrictor deficits that arose during HDBR. Twenty-two subjects underwent 14 days of strict 6 degrees HDBR. Eight of these 22 subjects did not exercise during HDBR, while 14 of these subjects exercised on a supine cycle ergometer for 90 min a day at 75% of pre-bed rest heart rate maximum. To assess alpha-adrenergic vasoconstrictor responsiveness, intradermal microdialysis was used to locally administer norepinephrine (NE), while forearm skin blood flow (SkBF; laser-Doppler flowmetry) was monitored over microdialysis membranes. Nonlinear regression modeling was used to identify the effective drug concentration that caused 50% of the cutaneous vasoconstrictor response (EC(50)) and minimum values from the SkBF-NE dose-response curves. In addition, the effects of HDBR on nonadrenergic cutaneous vasoconstriction were assessed via the venoarteriolar response of the forearm and leg. HDBR did not alter EC(50) or the magnitude of cutaneous vasoconstriction to exogenous NE administration regardless of whether the subjects exercised during HDBR. Moreover, HDBR did not alter the forearm venoarteriolar response in either the control or exercise groups during HDBR. However, HDBR significantly reduced the magnitude of cutaneous vasoconstriction due to the venoarteriolar response in the leg, and this response was similarly reduced in the exercise group. These data suggest that HDBR does not alter cutaneous vasoconstrictor responses to exogenous NE administration, whereas cutaneous vasoconstriction of the leg due to the venoarteriolar response is reduced after HDBR. It remains unclear whether attenuated venoarteriolar responses in the lower limbs contribute to reduced orthostatic tolerance after bed rest and

  7. Energy absorption, lean body mass, and total body fat changes during 5 weeks of continuous bed rest

    NASA Technical Reports Server (NTRS)

    Krebs, Jean M.; Evans, Harlan; Kuo, Mike C.; Schneider, Victor S.; Leblanc, Adrian D.

    1990-01-01

    The nature of the body composition changes due to inactivity was examined together with the question of whether these changes are secondary to changes in energy absorption. Volunteers were 15 healthy males who lived on a metabolic research ward under close staff supervision for 11 weeks. Subjects were ambulatory during the first six weeks and remained in continuous bed rest for the last five weeks of the study. Six male volunteers (age 24-61 years) were selected for body composition measurements. Nine different male volunteers (age 21-50 years) were selected for energy absorption measurements. The volunteers were fed weighed conventional foods on a constant 7-d rotation menu. The average daily caloric content was 2,592 kcal. Comparing the five weeks of continuous bed rest with the previous six weeks of ambulation, it was observed that there was no change in energy absorption or total body weight during bed rest, but a significant decrease in lean body mass and a significant increase in total body fat (p less than 0.05).

  8. Heart rate and blood pressure response to short-term head-down bed rest: a nonlinear approach.

    PubMed

    Balocchi, R; Di Garbo, A; Michelassi, C; Chillemi, S; Varanini, M; Barbi, M; Legramante, J M; Raimondi, G; Zbilut, J P

    2000-06-01

    Although it is well-known that prolonged exposure to microgravity environment such as in space travel results in derangements of orthostasis, recent evidence suggests that even short-term exposure may have similar effects and parallels such common examples as prolonged bed rest. Whereas spectral analysis of heart rate and systolic blood pressure have been unable to detect changes, we hypothesized that nonlinear indexes may be better able to uncover such perturbations. Eighteen healthy subjects were exposed to 4-hour head-down tilt, and of these, 4 exhibited fainting. Two nonlinear indexes, mutual information and recurrence quantification were used to analyze the data. Only recurrence quantification was able to detect a "decoupling" of heart rate and systolic blood pressure at rest using discriminant analysis (p < 0.05). These results suggest that orthostatic intolerance may be due to a decoupling of heart rate from systolic blood pressure reflexive activity occurring at rest.

  9. Effects of an artificial gravity countermeasure on orthostatic tolerance, blood volumes and aerobic power after short-term bed rest (BR-AG1).

    PubMed

    Linnarsson, Dag; Hughson, Richard L; Fraser, Katelyn S; Clément, Gilles; Karlsson, Lars L; Mulder, Edwin; Paloski, William H; Rittweger, Jörn; Wuyts, Floris L; Zange, Jochen

    2015-01-01

    Exposure to artificial gravity (AG) in a short-arm centrifuge has potential benefits for maintaining human performance during long-term space missions. Eleven subjects were investigated during three campaigns of 5 days head-down bed rest: 1) bed rest without countermeasures (control), 2) bed rest and 30 min of AG (AG1) daily, and 3) bed rest and six periods of 5 min AG (AG2) daily. During centrifugation, the supine subjects were exposed to AG in the head-to-feet direction with 1 G at the center of mass. Subjects participated in the three campaigns in random order. The cardiovascular effects of bed rest and countermeasures were determined from changes in tolerance to a head-up tilt test with superimposed lower body negative pressure (HUT), from changes in plasma volume (PV) and from changes in maximum aerobic power (V̇o2 peak) during upright work on a cycle ergometer. Complete data sets were obtained in eight subjects. After bed rest, HUT tolerance times were 36, 64, and 78% of pre-bed rest baseline during control, AG1 and AG2, respectively, with a significant difference between AG2 and control. PV and V̇o2 peak decreased to 85 and 95% of pre-bed rest baseline, respectively, with no differences between the treatments. It was concluded that the AG2 countermeasure should be further investigated during future long-term bed rest studies, especially as it was better tolerated than AG1. The superior effect of AG2 on orthostatic tolerance could not be related to concomitant changes in PV or aerobic power. PMID:25342708

  10. Age-related differences in lean mass, protein synthesis and skeletal muscle markers of proteolysis after bed rest and exercise rehabilitation.

    PubMed

    Tanner, Ruth E; Brunker, Lucille B; Agergaard, Jakob; Barrows, Katherine M; Briggs, Robert A; Kwon, Oh Sung; Young, Laura M; Hopkins, Paul N; Volpi, Elena; Marcus, Robin L; LaStayo, Paul C; Drummond, Micah J

    2015-09-15

    Bed rest-induced muscle loss and impaired muscle recovery may contribute to age-related sarcopenia. It is unknown if there are age-related differences in muscle mass and muscle anabolic and catabolic responses to bed rest. A secondary objective was to determine if rehabilitation could reverse bed rest responses. Nine older and fourteen young adults participated in a 5-day bed rest challenge (BED REST). This was followed by 8 weeks of high intensity resistance exercise (REHAB). Leg lean mass (via dual-energy X-ray absorptiometry; DXA) and strength were determined. Muscle biopsies were collected during a constant stable isotope infusion in the postabsorptive state and after essential amino acid (EAA) ingestion on three occasions: before (PRE), after bed rest and after rehabilitation. Samples were assessed for protein synthesis, mTORC1 signalling, REDD1/2 expression and molecular markers related to muscle proteolysis (MURF1, MAFBX, AMPKα, LC3II/I, Beclin1). We found that leg lean mass and strength decreased in older but not younger adults after bedrest (P < 0.05) and was restored after rehabilitation. EAA-induced mTORC1 signalling and protein synthesis increased before bed rest in both age groups (P < 0.05). Although both groups had blunted mTORC1 signalling, increased REDD2 and MURF1 mRNA after bedrest, only older adults had reduced EAA-induced protein synthesis rates and increased MAFBX mRNA, p-AMPKα and the LC3II/I ratio (P < 0.05). We conclude that older adults are more susceptible than young persons to muscle loss after short-term bed rest. This may be partially explained by a combined suppression of protein synthesis and a marginal increase in proteolytic markers. Finally, rehabilitation restored bed rest-induced deficits in lean mass and strength in older adults.

  11. Individual Variability in Aerobic Fitness Adaptations to 70-d of Bed Rest and Exercise Training

    NASA Technical Reports Server (NTRS)

    Downs, Meghan; Buxton, Roxanne; Goetchius, Elizabeth; DeWitt, John; Ploutz-Snyder, Lori

    2016-01-01

    Change in maximal aerobic capacity (VO2pk) in response to exercise training and disuse is highly variable among individuals. Factors that could contribute to the observed variability (lean mass, daily activity, diet, sleep, stress) are not routinely controlled in studies. The NASA bed rest (BR) studies use a highly controlled hospital based model as an analog of spaceflight. In this study, diet, hydration, physical activity and light/dark cycles were precisely controlled and provided the opportunity to investigate individual variability. PURPOSE. Evaluate the contribution of exercise intensity and lean mass on change in VO2pk during 70-d of BR or BR + exercise. METHODS. Subjects completed 70-d of BR alone (CON, N=9) or BR + exercise (EX, N=17). The exercise prescription included 6 d/wk of aerobic exercise at 70 - 100% of max and 3 d/wk of lower body resistance exercise. Subjects were monitored 24 hr/d. VO2pk and lean mass (iDXA) were measured pre and post BR. ANOVA was used to evaluate changes in VO2pk pre to post BR. Subjects were retrospectively divided into high and low responders based on change in VO2pk (CON > 20% loss, n=5; EX >10% loss, n=4, or 5% gain, n=4) to further understand individual variability. RESULTS. VO2pk decreased from pre to post BR in CON (P<0.05) and was maintained in EX; however, significant individual variability was observed (CON: -22%, range: -39% to -.5%; EX: -1.8%, range: -16% to 12.6%). The overlap in ranges between groups included 3 CON who experienced smaller reduction in VO2pk (<16%) than the worst responding EX subjects. Individual variability was maintained when VO2pk was normalized to lean mass (range, CON: -33.7% to -5.7%; EX: -15.8% to 11%), and the overlap included 5 CON with smaller reductions in VO2pk than the worst responding EX subjects. High responders to disuse also lost the most lean mass; however, this relationship was not maintained in EX (i.e. the largest gains/losses in lean mass were observed in both high and low

  12. Cardiovascular and Body Fluid Adjustments During Bed Rest and Space Flight

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.; Tomko, David L. (Technical Monitor)

    1995-01-01

    Although a few scientific bed rest (BR) studies were conducted soon after World War II, advent of the space program provided impetus for utilizing prolonged (days-months) BR, which employed the horizontal or 6 degree head-down tilt (HDT) body positions, to simulate responses of healthy people to microgravity. Shorter (hours) HDT protocols were used to study initial mechanisms of the acclimation-deconditioning (reduction of physical fitness) syndromes. Of the major physiological factors modified during BR, reduced force on bones, ligaments, and muscles, and greatly reduced hydrostatic pressure within the cardiovascular system, the latter: which involves shifts of blood from the lower extremities into the upper body, increase in central venous pressure, and diuresis, appears to be the initial stimulus for acclimation. Increase in central venous pressure occurs in subjects during weightless parabolic flight, but not in astronauts early during orbital flight. But significant reduction in total body water (hypohydration) and plasma volume (hypovolemia) occurs in subjects during both BR and microgravity. Response of interstitial fluid volume is not as clear, It has been reported to increase during BR, and it may have increased in Skylab II and IV astronauts. Reduction of total body water, and greater proportional reduction of extracellular volume, indicates increased cellular volume which may contribute to inflight cephalic edema. Cerebral pressure abates after a few days of HDT, but not during flight. accompanied by normal (eugravity) blood constituent concentrations suggesting some degree of acclimation had occurred. But during reentry, with moderately increased +Gz (head-to-foot) acceleration and gravitational force, the microgravity "euhydration" becomes functional progressive dehydration contributing to the general reentry syndrome (GRS) which, upon landing the Shuttle, can and often results in gastrointestinal distress, disorientation, vertigo, fatigue, and

  13. High Intensity Exercise Countermeasures does not Prevent Orthostatic Intolerance Following Prolonged Bed Rest

    NASA Technical Reports Server (NTRS)

    Platts, Steven H.; Stenger, Michael B.; Ploutz-Snyder, Lori L.; Lee, Stuart M. C.

    2014-01-01

    Approximately 20% of Space Shuttle astronauts became presyncopal during operational stand and 80deg head-up tilt tests, and the prevalence of orthostatic intolerance increases after longer missions. Greater than 60% of the US astronauts participating in Mir and early International Space Station missions experienced presyncope during post-flight tilt tests, perhaps related to limitations of the exercise hardware that prevented high intensity exercise training until later ISS missions. The objective of this study was to determine whether an intense resistive and aerobic exercise countermeasure program designed to prevent cardiovascular and musculoskeletal deconditioning during 70 d of bed rest (BR), a space flight analog, would protect against post-BR orthostatic intolerance. METHODS Twenty-six subjects were randomly assigned to one of three groups: non-exercise controls (n=11) or one of two exercise groups (ExA, n=8; ExB, n=7). Both ExA and ExB groups performed the same resistive and aerobic exercise countermeasures during BR, but one exercise group received testosterone supplementation while the other received a placebo during BR in a double-blinded fashion. On 3 d/wk, subjects performed lower body resistive exercise and 30 min of continuous aerobic exercise (=75% max heart rate). On the other 3 d/wk, subjects performed only highintensity, interval-style aerobic exercise. Orthostatic intolerance was assessed using a 15-min 80? head-up tilt test performed 2 d (BR-2) before and on the last day of BR (BR70). Plasma volume was measured using carbon monoxide rebreathing on BR-3 and before rising on the first recovery day (BR+0). The code for the exercise groups has not been broken, and results are reported here without group identification. RESULTS Only one subject became presyncopal during tilt testing on BR-2, but 7 of 11 (63%) controls, 3 of 8 (38%) ExA, and 4 of 7 (57%) ExB subjects were presyncopal on BR70. Survival analysis of post-BR tilt tests revealed no

  14. Analog Exercise Hardware to Implement a High Intensity Exercise Program During Bed Rest

    NASA Technical Reports Server (NTRS)

    Loerch, Linda; Newby, Nate; Ploutz-Snyder, Lori

    2012-01-01

    Background: In order to evaluate novel countermeasure protocols in a space flight analog prior to validation on the International Space Station (ISS), NASA's Human Research Program (HRP) is sponsoring a multi-investigator bedrest campaign that utilizes a combination of commercial and custom-made exercise training hardware to conduct daily resistive and aerobic exercise protocols. This paper will describe these pieces of hardware and how they are used to support current bedrest studies at NASA's Flight Analog Research Unit in Galveston, TX. Discussion: To implement candidate exercise countermeasure studies during extended bed rest studies the following analog hardware are being utilized: Stand alone Zero-Gravity Locomotion Simulator (sZLS) -- a custom built device by NASA, the sZLS allows bedrest subjects to remain supine as they run on a vertically-oriented treadmill (0-15 miles/hour). The treadmill includes a pneumatic subject loading device to provide variable body loading (0-100%) and a harness to keep the subject in contact with the motorized treadmill to provide a ground reaction force at their feet that is quantified by a Kistler Force Plate. Supine Cycle Ergometer -- a commercially available supine cycle ergometer (Lode, Groningen, Netherlands) is used for all cycle ergometer sessions. The ergometer has adjustable shoulder supports and handgrips to help stabilize the subject during exercise. Horizontal Squat Device (HSD) -- a custom built device by Quantum Fitness Corp (Stafford, TX), the HSD allows for squat exercises to be performed while lying in a supine position. The HSD can provide 0 to 600 pounds of force in selectable 5 lb increments, and allows hip translation in both the vertical and horizontal planes. Prone Leg Curl -- a commercially available prone leg curl machine (Cybex International Inc., Medway, MA) is used to complete leg curl exercises. Horizontal Leg Press -- a commercially available horizontal leg press (Quantum Fitness Corporation) is

  15. NIRS-Derived Tissue Oxygen Saturation and Hydrogen Ion Concentration Following Bed Rest

    NASA Technical Reports Server (NTRS)

    Lee, S. M. C.; Everett, M. E.; Crowell, J. B.; Westby, C. M.; Soller, B. R.

    2010-01-01

    Long-term bed rest (BR), a model of spaceflight, results in a decrease in aerobic capacity and altered submaximal exercise responses. The strongest BR-induced effects on exercise appear to be centrally-mediated, but longer BR durations may result in peripheral adaptations (e.g., decreased mitochondrial and capillary density) which are likely to influence exercise responses. PURPOSE: To measure tissue oxygen saturation (SO2) and hydrogen ion concentration ([H+]) in the vastus lateralis (VL) using near infrared spectroscopy (NIRS) during cycle ergometry before and after . 30 d of BR. METHODS: Eight subjects performed a graded exercise test on a cycle ergometer to volitional fatigue 7 d before (pre-BR) and at the end or 1 day after BR (post-BR). NIRS spectra were collected from a sensor adhered to the skin overlying the VL. Oxygen consumption (VO2) was measured by open circuit spirometry. Blood volume (BV) was measured before and after BR using the carbon monoxide rebreathing technique. Changes in pre- and post-BR SO2 and [H+] data were compared using mixed model analyses. BV and peak exercise data were compared using paired t-tests. RESULTS: BV (pre-BR: 4.3+/-0.3, post-BR: 3.7+/-0.2 L, mean+/-SE, p=.01) and peak VO2 (pre-BR: 1.98+/-0.24, post-BR: 1.48 +/-0.21 L/min, p<.01) were reduced after BR. As expected, SO2 decreased with exercise before and after BR. However, SO2 was lower post compared with pre-BR throughout exercise, including at peak exercise (pre-BR: 50+/-3, post-BR: 43+/-4%, p=.01). After BR, [H+] was higher at the start of exercise and did not increase at the same rate as pre-BR. Peak [H+] was not different from pre to post-BR (pre-BR: 36+/-2; post-BR: 38+/-2 nmol/L). CONCLUSIONS: Lower SO2 during exercise suggests that oxygen extraction in the VL is higher after BR, perhaps due to lower circulating blood volume. The higher [H+] after BR suggests a greater reliance upon glycolysis during submaximal exercise, although [H+] at peak exercise was unchanged

  16. Ocular Outcomes Comparison Between 14- and 70-Day Head-Down-Tilt Bed Rest

    PubMed Central

    Taibbi, Giovanni; Cromwell, Ronita L.; Zanello, Susana B.; Yarbough, Patrice O.; Ploutz-Snyder, Robert J.; Godley, Bernard F.; Vizzeri, Gianmarco

    2016-01-01

    Purpose To compare ocular outcomes in healthy subjects undergoing 14- and/or 70-day head-down-tilt (HDT) bed rest (BR). Methods Participants were selected by using NASA standard screening procedures. Standardized NASA BR conditions were implemented. Subjects maintained a 6° HDT position for 14 and/or 70 consecutive days. Weekly ophthalmologic examinations were performed in the sitting (pre/post-BR only) and HDT positions. Mixed-effects linear models compared pre- and post-HDT BR observations between 14- and 70-day HDT BR in best-corrected visual acuity, spherical equivalent, intraocular pressure (IOP), Spectralis OCT retinal nerve fiber layer thickness, peripapillary and macular retinal thicknesses. Results Sixteen and six subjects completed the 14- and 70-day HDT BR studies, respectively. The magnitude of HDT BR–induced changes was not significantly different between the two studies for all outcomes, except the superior (mean pre/post difference of 14- vs. 70-day HDT BR: +4.69 μm versus +11.50 μm), nasal (+4.63 μm versus +11.46 μm), and inferior (+4.34 μm versus +10.08 μm) peripapillary retinal thickness. A +1.42 mm Hg and a +1.79 mm Hg iCare IOP increase from baseline occurred during 14- and 70-day HDT BR, respectively. Modified Amsler grid, red dot test, confrontational visual field, color vision, and stereoscopic fundus photography were unremarkable. Conclusions Seventy-day HDT BR induced greater peripapillary retinal thickening than 14-day HDT BR, suggesting that time may affect the amount of optic disc swelling. Spectralis OCT detected retinal nerve fiber layer thickening post BR, without clinical signs of optic disc edema. A small IOP increase during BR subsided post HDT BR. Such changes may have resulted from BR-induced cephalad fluids shift. The HDT BR duration may be critical for replicating microgravity-related ophthalmologic changes observed in astronauts on ≥6-month spaceflights. PMID:26868753

  17. Arterial Structure and Function in Women and Men Following Long Duration Bed Rest

    NASA Technical Reports Server (NTRS)

    Lee, Stuart M. C.; Stenger, Michael B.; Martin, David S.; Platts, Steven H.

    2008-01-01

    Orthostatic intolerance is a well-recognized consequence of space flight and bed rest (BR), with a greater incidence reported in women. We hypothesized that leg, but not arm, arterial structure and function would be altered following prolonged BR, as a model of space flight, and that women would be more susceptible to BR-induced deconditioning than men. METHODS: Ten volunteers (5 males, 5 females) completed 90 d of 6 head-down BR. Subjects participated in tests of brachial (BA) and anterior tibial (AT) artery endothelium-dependent (flow mediated dilation [FMD] following 5-7 min of arterial occlusion) and endothelium-independent (0.4 mg sublingual nitroglycerin [SN]) vasodilation before BR (PRE) and on days 7 (BR7), 21 (BR21), and 90 (BR90) of BR. Vessel diameter and intimal medial thickness (IMT) were measured by ultrasound. IMT, baseline diameter, and percent change in diameter from baseline during FMD and SN tests were compared across BR and between genders using repeated measures two-way ANOVA with Bonferroni post-hoc tests in which PRE and women were control conditions. RESULTS: Baseline vessel diameter was lower in women than in men in both the BA (p=0.005) and AT (p=0.01) across all days. Baseline AT diameter decreased during BR (p=0.01) and tended to be more profound in women (interaction, p=0.06). AT diameter was reduced in women at BR21 and BR90 (p<0.01) but not in men. In contrast, there was no BR effect on baseline BA diameter. IMT also decreased in the AT (p<0.001) but not in the BA during BR; AT IMT was reduced by BR21 (p<0.05). As a group, there was no effect of BR on AT FMD, BA FMD, and AT SN-dilation, although BA SN-dilation was significantly reduced on BR21 (p=0.01). Across all BR days, women exhibited higher AT FMD (p=0.03), BA FMD (p=0.02), and BA SN-dilation (p=0.01) and tended to demonstrate greater AT SN-dilation (p=0.11). CONCLUSIONS: These preliminary results suggest that arterial remodeling occurs during BR in the leg (decreased diameter

  18. Integrated Resistance and Aerobic Training Maintains Cardiovascular and Skeletal Muscle Fitness During 14 Days of Bed Rest

    NASA Technical Reports Server (NTRS)

    Ploutz-Snyder, Lori; Goetchius, Elizabeth; Crowell, Brent; Hackney, Kyle; Wickwire, Jason; Ploutz-Snyder, Robert; Snyder, Scott

    2012-01-01

    Background: Known incompatibilities exist between resistance and aerobic training. Of particular importance are findings that concurrent resistance and aerobic training reduces the effectiveness of the resistance training and limits skeletal muscle adaptations (example: Dudley & Djamil, 1985). Numerous unloading studies have documented the effectiveness of resistance training alone for the maintenance of skeletal muscle size and strength. However the practical applications of those studies are limited because long ]duration crew members perform both aerobic and resistance exercise throughout missions/spaceflight. To date, such integrated training on the International Space Station (ISS) has not been fully effective in the maintenance of skeletal muscle function. Purpose: The purpose of this study was to evaluate the efficacy of high intensity concurrent resistance and aerobic training for the maintenance of cardiovascular fitness and skeletal muscle strength, power and endurance over 14 days of strict bed rest. Methods: 9 subjects (8 male and 1 female; 34.5 +/- 8.2 years) underwent 14 days of bed rest with concurrent training. Resistance and aerobic training were integrated as shown in table 1. Days that included 2 exercise sessions had a 4-8 hour rest between exercise bouts. The resistance training consisted of 3 sets of 12 repetitions of squat, heel raise, leg press and hamstring curl exercise. Aerobic exercise consisted of periodized interval training that included 30 sec, 2 min and 4 min intervals alternating by day with continuous aerobic exercise.

  19. Effects of encouraged water drinking on thermoregulatory responses after 20 days of head-down bed rest in humans

    NASA Astrophysics Data System (ADS)

    Sato, Maki; Kanikowska, Dominika; Iwase, Satoshi; Shimizu, Yuuki; Inukai, Yoko; Nishimura, Naoki; Sugenoya, Junichi

    2009-09-01

    We tested the hypothesis that encouraged water drinking according to urine output for 20 days could ameliorate impaired thermoregulatory function under microgravity conditions. Twelve healthy men, aged 24 ± 1.5 years (mean ± SE), underwent -6° head-down bed rest (HDBR) for 20 days. During bed rest, subjects were encouraged to drink the same amount of water as the 24-h urine output volume of the previous day. A heat exposure test consisting of water immersion up to the knees at 42°C for 45 min after a 10 min rest (baseline) in the sitting position was performed 2 days before the 20-day HDBR (PRE), and 2 days after the 20-day HDBR (POST). Core temperature (tympanic), skin temperature, skin blood flow and sweat rate were recorded continuously. We found that the -6° HDBR did not increase the threshold temperature for onset of sweating under the encouraged water drinking regime. We conclude that encouraged water drinking could prevent impaired thermoregulatory responses after HDBR.

  20. Effects of long-term head-down-tilt bed rest and different training regimes on the coagulation system of healthy men

    PubMed Central

    Haider, Thomas; Gunga, Hanns-Christian; Matteucci-Gothe, Raffaella; Sottara, Elke; Griesmacher, Andrea; Belavý, Daniel L; Felsenberg, Dieter; Werner, Andreas; Schobersberger, Wolfgang

    2013-01-01

    Immobility plus preexisting chronic disease or acute trauma can activate the coagulation system, thus increasing the risk for thromboembolic events. The effects of long-term bed-rest immobility and microgravity on the coagulation system of healthy persons (e.g., during crewed Mars missions) have not yet been studied. The main objective of the second Berlin BedRest Study (BBR2-2) “Coagulation Part” was to investigate adaptations of the hemostatic system during long-term bed rest (60 days) under simulated microgravity (6° head-down-tilt [6°HDT]) and after mobilization in three different volunteer groups (randomly assigned to CTR= inactive control group; RE= resistive exercise only group; and RVE= resistive exercise with whole-body vibration group). In 24 males (aged 21–45 years), before, during, and after long-term bed rest, key parameters of coagulation were measured from venous blood samples: D-dimer (DD), thrombin–antithrombin III complex (TAT), and prothrombin fragment F1 + 2 (PT-F1 + 2). Additionally, modified rotational thrombelastometry (ROTEM®) analysis was performed. Times of exploratory analyses were as follows: baseline data collection 2 days before bed rest (BDC-2); eight different days of 6°HDT bed rest (HDT1–HDT60), and two different days after reambulation (R + 3 and R + 6). We found significant changes in DD, TAT, and PT-F1 + 2 over the total time course, but no consistent effect of physical interventions (RE, RVE) on these parameters. Notably, no parameter reached levels indicative of intravascular thrombin formation. All ROTEM® parameters remained within the normal range and no pathological traces were found. Sixty days of 6°HDT bed rest are not associated with pronounced activation of the coagulation system indicative of intravascular thrombus formation in healthy volunteers independent of the training type during the bed rest. PMID:24400137

  1. Effect of three day bed-rest on circulatory and hormonal responses to active orthostatic test in endurance trained athletes and untrained subjects

    NASA Technical Reports Server (NTRS)

    Kubala, P.; Smorawinski, J.; Kaciuba-Uscilko, H.; Nazar, K.; Bicz, B.; Greenleaf, J. E.

    1996-01-01

    Circulatory and hormonal parameters were measured in endurance-trained athletes and control subjects during orthostatic tolerance tests conducted prior to and after three days of bed rest. Heart rate and blood pressure changes due to bed rest appeared to be the same in both groups. Hormonal changes, however, were different between the two groups, with the athletes having decreased sympathoadrenal activity and increased plasma renin activity. Untrained subjects had changes in cortisol secretion only.

  2. High dietary sodium chloride causes further protein loss during head-down tilt bed rest (HDBR)

    NASA Astrophysics Data System (ADS)

    Buehlmeier, Judith; Frings-Meuthen, Petra; Baecker, Natalie; Stehle, Peter; Heer, Martina

    Human spaceflight is associated with a loss of body protein most likely caused by muscle degradation. Additionally astronauts tend towards a high dietary intake of sodium chloride (NaCl), which has recently been shown to induce low grade metabolic acidosis (Frings-Meuthen et al. JBMR, Epub 2007). In several patterns, e.g. chronical renal failure, metabolic acidosis is associated with protein catabolism. We therefore hypothesized that high dietary intake of NaCl enforces protein losses in HDBR, a model for physiological changes in microgravity (µG). Eight healthy male subjects (mean age 26.25 ± 3.5; mean body weight: 78.5 ± 4.1 kg) participated in a 14-day bed rest study in the metabolic ward of the DLR - Institute of Aerospace Medicine, Cologne, Germany. The study was carried out in a cross over design, consisting of two phases, each lasting 22 days (5 days adaptation, 14 days 6° HDBR and 3 days recovery). Both study phases were identical with respect to environmental conditions and study protocol. Subjects received an individually tailored, weight-maintaining diet containing 1.3 g protein/kg/day. The diet was identical in both study phases with the exception of NaClintake: Every subject received a low NaCl diet (0.7 mmol/kg/day) in one phase and a high NaCl diet (7.7 mmol/kg/day) in another one. Blood gas for analysis of acid-base balance was implemented at days 4 and 5 of adaptation, days 2, 5, 7, 10, 12, 14 of HDBR and days 2, 3 of recovery. Continuous urine collection started on the first day in the metabolic ward to analyze nitrogen excretion. Nitrogen balance was calculated from the difference between protein intake and urinary nitrogen excretion, determined by use of chemiluminescence (Grimble et al. JPEN, 1988). Plasma pH did not change significantly (p=0.285), but plasma bicarbonate and base excess decreased (p=0.0175; p=0.0093) with high NaCl intake in HDBR compared to the low NaCl diet. Nitrogen balance in HDBR was negative, as expected in

  3. Effect of high sodium intake during 14 days of bed-rest on acid-base balance

    NASA Astrophysics Data System (ADS)

    Frings, P.; Baecker, N.; Heer, M.

    Lowering mechanical load like in microgravity is the dominant stimulus leading to bone loss However high dietary sodium intake is also considered as a risk factor for osteoporosis and thereby might exacerbate the microgravity induced bone loss In a metabolic balance non bed-rest study we have recently shown that a very high sodium intake leads to an increased bone resorption most likely because of a mild metabolic acidosis Frings et al FASEB J 19 5 A1345 2005 To test if mild metabolic acidosis also occurs during immobilization we examined the effect of increased dietary sodium on bone metabolism and acid-base balance in eight healthy male test subjects mean age 26 25 pm 3 49 years body weight 77 98 pm 4 34 kg in our metabolic ward during a 14-day head-down tilt HDT bed-rest study The study was designed as a randomized crossover study with two study periods Each period was divided into three parts 4 ambulatory days with 200 mmol sodium intake 14 days of bed-rest with either 550 mmol or 50 mmol sodium intake and 3 recovery days with 200 mmol sodium intake The sodium intake was altered by variations in dietary sodium chloride content Blood pH P CO2 and P O2 were analyzed in fasting morning fingertip blood samples several times during the entire study Bicarbonate HCO 3 - and base excess BE were calculated according to the Henderson-Hasselbach equation Preliminary results in the acid-base balance from the first study period 4 subjects with 550 mmol and 4 subjects with 50 mmol sodium intake strongly

  4. Effects of space flight and -6 degrees bed rest on the neuroendocrine response to metabolic stress in physically fit subjects.

    PubMed

    Ksinantová, Lucia; Koska, Juraj; Martinkovic, Miroslav; Vigas, Milan; Macho, Ladislav; Kvetnansky, Richard

    2004-06-01

    The aim of this study was to evaluate the association of plasma epinephrine (EPI) and norepinephrine (NE) responses to insulin-induced hypoglycemia (ITT) 3 weeks before the space flight (SF), on the fifth day of SF, on days 2 and 16 after landing in the first Slovak astronaut, and before and on the fifth day of prolonged bed rest (BR) in 15 military aircraft pilots, aged 33.5 +/- 1.4 years, body mass index (BMI) 26.5 +/- 0.7 kg/m(2), maximal oxygen uptake (VO(2max)) 55.2 +/- 2.4 mL/kg/min, who volunteered for the study. ITT was induced by i.v. administrations of 0.1 IU/kg body weight insulin (Actrapid HM) in a bolus. Insulin administration led to a comparable hypoglycemia in preflight, actual flight conditions, and before and after bed rest. ITT led to a pronounced increase in EPI levels and moderate increase in NE in preflight studies. However, an evidently reduced plasma elevation of EPI was found after insulin administration during SF and during BR. Thus, during the real microgravity in SF and simulated microgravity in BR, ITT activates the adrenomedullary system to less extent that at conditions of the Earth's gravitation. Post-flight changes in EPI and NE did not differ from those of preflight values, since SF was relatively short (8 days) and the readaptation to Earth's gravitation was fast. It seems that an increased blood flow in brain might be responsible for the reduced EPI response to insulin. Responses to ITT in physically fit subjects indicate the stimulus specificity of the deconditioning effect of 5 days of bed rest on the stress response. PMID:15240415

  5. WISE 2005: Aerobic and resistive countermeasures prevent paraspinal muscle deconditioning during 60-day bed rest in women.

    PubMed

    Holt, Jacquelyn A; Macias, Brandon R; Schneider, Suzanne M; Watenpaugh, Donald E; Lee, Stuart M C; Chang, Douglas G; Hargens, Alan R

    2016-05-15

    Microgravity-induced lumbar paraspinal muscle deconditioning may contribute to back pain commonly experienced by astronauts and may increase the risk of postflight injury. We hypothesized that a combined resistive and aerobic exercise countermeasure protocol that included spinal loading would mitigate lumbar paraspinal muscle deconditioning during 60 days of bed rest in women. Sixteen women underwent 60-day, 6° head-down-tilt bed rest (BR) and were randomized into control and exercise groups. During bed rest the control group performed no exercise. The exercise group performed supine treadmill exercise within lower body negative pressure (LBNP) for 3-4 days/wk and flywheel resistive exercise for 2-3 days/wk. Paraspinal muscle cross-sectional area (CSA) was measured using a lumbar spine MRI sequence before and after BR. In addition, isokinetic spinal flexion and extension strengths were measured before and after BR. Data are presented as means ± SD. Total lumbar paraspinal muscle CSA decreased significantly more in controls (10.9 ± 3.4%) than in exercisers (4.3 ± 3.4%; P < 0.05). The erector spinae was the primary contributor (76%) to total lumbar paraspinal muscle loss. Moreover, exercise attenuated isokinetic spinal extension loss (-4.3 ± 4.5%), compared with controls (-16.6 ± 11.2%; P < 0.05). In conclusion, LBNP treadmill and flywheel resistive exercises during simulated microgravity mitigate decrements in lumbar paraspinal muscle structure and spine function. Therefore spaceflight exercise countermeasures that attempt to reproduce spinal loads experienced on Earth may mitigate spinal deconditioning during long-duration space travel.

  6. WISE 2005: Aerobic and resistive countermeasures prevent paraspinal muscle deconditioning during 60-day bed rest in women.

    PubMed

    Holt, Jacquelyn A; Macias, Brandon R; Schneider, Suzanne M; Watenpaugh, Donald E; Lee, Stuart M C; Chang, Douglas G; Hargens, Alan R

    2016-05-15

    Microgravity-induced lumbar paraspinal muscle deconditioning may contribute to back pain commonly experienced by astronauts and may increase the risk of postflight injury. We hypothesized that a combined resistive and aerobic exercise countermeasure protocol that included spinal loading would mitigate lumbar paraspinal muscle deconditioning during 60 days of bed rest in women. Sixteen women underwent 60-day, 6° head-down-tilt bed rest (BR) and were randomized into control and exercise groups. During bed rest the control group performed no exercise. The exercise group performed supine treadmill exercise within lower body negative pressure (LBNP) for 3-4 days/wk and flywheel resistive exercise for 2-3 days/wk. Paraspinal muscle cross-sectional area (CSA) was measured using a lumbar spine MRI sequence before and after BR. In addition, isokinetic spinal flexion and extension strengths were measured before and after BR. Data are presented as means ± SD. Total lumbar paraspinal muscle CSA decreased significantly more in controls (10.9 ± 3.4%) than in exercisers (4.3 ± 3.4%; P < 0.05). The erector spinae was the primary contributor (76%) to total lumbar paraspinal muscle loss. Moreover, exercise attenuated isokinetic spinal extension loss (-4.3 ± 4.5%), compared with controls (-16.6 ± 11.2%; P < 0.05). In conclusion, LBNP treadmill and flywheel resistive exercises during simulated microgravity mitigate decrements in lumbar paraspinal muscle structure and spine function. Therefore spaceflight exercise countermeasures that attempt to reproduce spinal loads experienced on Earth may mitigate spinal deconditioning during long-duration space travel. PMID:26893030

  7. Altered autonomic regulation of cardiac function during head-up tilt after 28-day head-down bed-rest with counter-measures.

    PubMed

    Hughson, R L; Yamamoto, Y; Maillet, A; Fortrat, J O; Pavy-Le Traon, A; Butler, G C; Güell, A; Gharib, C

    1994-05-01

    The effects of 28 days continuous 6 degrees head-down tilt bed-rest on heart rate variability and the slope of the spontaneous arterial baroreflex were evaluated during supine rest and the first 10 min of 60 degrees head-up tilt. Twelve healthy men were assigned to either a no counter-measure (No-CM), or a counter-measure (CM) group so that there was no difference in maximal oxygen uptake. Counter-measures consisted of short-term, high resistance exercise for 6 days per week from days 7-28, and lower body negative pressure (-28 mmHg) for 15 min on days 16, 18, 20 and 22-28. In spite of balanced between-group fitness, mean RR-interval was different between the No-CM and the CM group prior to bed-rest, but neither this nor any other variables showed significant counter-measure by bed-rest interaction effects. Therefore, all data presented are from the main effects of bed-rest or tilt from the analysis of variance. RR-interval was reduced significantly by bed-rest and by tilt (P < 0.0001). Indicators from spectral analysis of heart-rate variability suggested reduced parasympathetic nervous system activity with bed-rest (P < 0.01) and head-up tilt (P < 0.05), and increased sympathetic nervous system activity after bed-rest (P < 0.01). An indicator of complexity of cardiovascular control mechanisms, taken from the slope (beta) of log spectral power vs. log frequency relationship, suggested reduced complexity with bed-rest (P < 0.05) and head-up tilt (P < 0.01). The spontaneous baroreflex slope was reduced significantly by bed-rest (P < 0.03) and by head-up tilt (P < 0.04). Taken together, these data support the concept of altered autonomic nervous system function in the aetiology of cardiovascular deconditioning with bed-rest or space travel; and it would appear that no benefit is derived from these specific counter-measures.

  8. [Space flight/bedrest immobilization and bone. Bone metabolism in space flight and long-duration bed rest].

    PubMed

    Ohshima, Hiroshi; Matsumoto, Toshio

    2012-12-01

    Bone loss and urolithiasis are inevitable outcome in human space flight and long-duration bet rest. The rate of space flight induced bone loss is 10 times faster than in those with osteoporosis. Significant bone loss at weight bearing bones, elevated urinary calcium excretion, and un-coupling of bone resorption and bone formation are observed during the long-term bed rest study. Improvements of resistive exercise device and vitamin-D supplementation for astronauts in International Space Station can partially maintain bone mass, however, they can not fully supress bone resorption and urinary calcium excretion during space flight. JAXA and NASA are performing joint study to validate the mitigration effects on bone resorption and urolithiasis of bisphosphonate supplement in conjunction with excercise.

  9. Performance and mood-state parameters during 30-day 6 deg head-down bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    Deroshia, Charles W.; Greenleaf, J. E.

    1993-01-01

    A study aimed at determining if the performance and mood impairments occur in bed-rested subjects, and if different exercise-training regimens modify or prevent them is presented. Eighteen healthy men were divided into three groups performing no exercise, isotonic exercise, and isokinetic exercise. Few deleterious changes occurred in performance and mood of the three groups which did not exceed baseline ambulatory levels. It is concluded that mood and performance did not deteriorate in response to prolonged bedrest and were not altered by exercise training.

  10. Once-yearly zoledronic acid and days of disability, bed rest, and back pain: randomized, controlled HORIZON Pivotal Fracture Trial.

    PubMed

    Cauley, Jane A; Black, Dennis; Boonen, Steven; Cummings, Steven R; Mesenbrink, Peter; Palermo, Lisa; Man, Zulema; Hadji, Peyman; Reid, Ian R

    2011-05-01

    The objective of this study was to determine the effect of once-yearly zoledronic acid on the number of days of back pain and the number of days of disability (ie, limited activity and bed rest) owing to back pain or fracture in postmenopausal women with osteoporosis. This was a multicenter, randomized, double-blind, placebo-controlled trial in 240 clinical centers in 27 countries. Participants included 7736 postmenopausal women with osteoporosis. Patients were randomized to receive either a single 15-minute intravenous infusion of zoledronic acid (5 mg) or placebo at baseline, 12 months, and 24 months. The main outcome measures were self-reported number of days with back pain and the number of days of limited activity and bed rest owing to back pain or a fracture, and this was assessed every 3 months over a 3-year period. Our results show that although the incidence of back pain was high in both randomized groups, women randomized to zoledronic acid experienced, on average, 18 fewer days of back pain compared with placebo over the course of the trial (p = .0092). The back pain among women randomized to zoledronic acid versus placebo resulted in 11 fewer days of limited activity (p = .0017). In Cox proportional-hazards models, women randomized to zoledronic acid were about 6% less likely to experience 7 or more days of back pain [relative risk (RR) = 0.94, 95% confidence interval (CI) 0.90-0.99] or limited activity owing to back pain (RR = 0.94, 95% CI 0.87-1.00). Women randomized to zoledronic acid were significantly less likely to experience 7 or more bed-rest days owing to a fracture (RR = 0.58, 95% CI 0.47-0.72) and 7 or more limited-activity days owing to a fracture (RR = 0.67, 95% CI 0.58-0.78). Reductions in back pain with zoledronic acid were independent of incident fracture. Our conclusion is that in women with postmenopausal osteoporosis, a once-yearly infusion with zoledronic acid over a 3-year period significantly reduced the

  11. Six-Degree Head-Down Tilt Bed Rest: Forty Years of Development as a Physiological Analog for Weightlessness

    NASA Technical Reports Server (NTRS)

    Smith, Jeffrey D.; Cromwell, Ronita L.; Kundrot, Craig E.; Charles, John B.

    2011-01-01

    Early on, bed rest was recognized as a method for inducing many of the physiological changes experienced by spaceflight. Head-down tilt (HDT) bed rest was first introduced as an analog for spaceflight by a Soviet team led by Genin and Kakurin. Their study was performed in 1970 (at -4 degrees) and lasted for 30 days; results were reported in the Russian Journal of Space Biology (Kosmicheskaya Biol. 1972; 6(4): 26-28 & 45-109). The goal was to test physiological countermeasures for cosmonauts who would soon begin month-long missions to the Salyut space station. HDT was chosen to produce a similar sensation of blood flow to the head reported by Soyuz cosmonauts. Over the next decade, other tilt angles were studied and comparisons with spaceflight were made, showing that HDT greater than 4 degrees was superior to horizontal bed rest for modeling acute physiological changes observed in space; but, at higher angles, subjects experienced greater discomfort without clearly improving the physiological comparison to spaceflight. A joint study performed by US and Soviet investigators, in 1979, set the goal of standardization of baseline conditions and chose 6-degrees HDT. This effectively established 6-degree HDT bed rest as the internationally-preferred analog for weightlessness and, since 1990, nearly all further studies have been conducted at 6-degrees HDT. A thorough literature review (1970-2010) revealed 534 primary scientific journal articles which reported results from using HDT as a physiological analog for spaceflight. These studies have ranged from as little as 10 minutes to the longest duration of 370 days. Long-term studies lasting four weeks or more have resulted in over 170 primary research articles. Today, the 6-degree HDT model provides a consistent, thoroughly-tested, ground-based analog for spaceflight and allows the proper scientific controls for rigorous testing of physiological countermeasures; however, all models have their strengths and limits. The 6

  12. Performance and mood-state parameters during 30-day 6 degrees head-down bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    DeRoshia, C. W.; Greenleaf, J. E.

    1993-01-01

    The study was designed to determine if performance and mood impairments occur in bed-rested subjects, and if different exercise-training regimens modify or prevent them. Eighteen normal, healthy men were divided on the basis of age, peak oxygen uptake, and maximal isometric knee extension strength into three similar groups: no exercise (NOE), isotonic exercise (ITE), and isokinetic exercise (IKE). A 15-min battery of 10 performance tests and 8 mood and 2 sleep scales were administered daily during ambulatory control, 30 d of absolute bed rest (BR), and 4 d of ambulatory recovery. Performance test proficiency increased (p < 0.05) for all three groups during BR in 7 of 10 tests and there were no consistent significant differences between the three groups. However, during BR, the ITE group was distinguished from the other groups by a decline (p < 0.05) in the activation mood dimension and in two of its constituent scales (motivation and concentration), and by improvement (p < 0.05) in the trouble-falling-asleep and psychological-tension scales. Since few deleterious changes in performance and mood occurred in the three groups and did not exceed baseline ambulatory levels, we conclude that mood and performance did not deteriorate in response to prolonged BR and were not altered by exercise training. However, the decline in activation mood scales in the ITE group may reflect overtraining or excess total workload in this group.

  13. Effect of head-down bed rest on the neuroendocrine response to orthostatic stress in physically fit men.

    PubMed

    Koska, J; Ksinantová, L; Kvetnanský, R; Marko, M; Hamar, D; Vigas, M; Hatala, R

    2003-01-01

    The role of neuroendocrine responsiveness in the development of orthostatic intolerance after bed rest was studied in physically fit subjects. Head-down bed-rest (HDBR, -6 degrees, 4 days) was performed in 15 men after 6 weeks of aerobic training. The standing test was performed before, after training and on day 4 of the HDBR. Orthostatic intolerance was observed in one subject before and after training. The blood pressure response after training was enhanced (mean BP increments 18+/-2 vs. 13+/- 2 mm Hg, p<0.05, means +/- S.E.M.), although noradrenaline response was diminished (1.38+/-0.18 vs. 2.76+/-0.25 mol.l(-1), p<0.01). Orthostatic intolerance after HDBR was observed in 10 subjects, the BP response was blunted, and noradrenaline as well as plasma renin activity (PRA) responses were augmented (NA 3.10+/-0.33 mol.l(-1), p<0.001; PRA 2.98+/-1.12 vs. 0.85+/-0.15 ng.ml(-1), p<0.05). Plasma noradrenaline, adrenaline and aldosterone responses in orthostatic intolerant subjects were similar to the tolerant group. We conclude that six weeks of training attenuated the sympathetic response to standing and had no effect on the orthostatic tolerance. In orthostatic intolerance the BP response induced by subsequent HDBR was absent despite an enhanced sympathetic response. PMID:12790765

  14. Effects of endurance training on endocrine response to physical exercise after 5 days of bed rest in healthy male subjects.

    PubMed

    Koska, Juraj; Ksinantová, Lucia; Kvetnanský, Richard; Hamar, Dusan; Martinkovic, Miroslav; Vigas, Milan

    2004-06-01

    The study was designed to evaluate how a bout of endurance training (ET) influences the endocrine response after head-down bed rest (HDBR). Eleven healthy males completed the study, which consisted of a 6-wk ET followed by 5 days of -6 degrees head-down HDBR. Treadmill exercise at 80% of pretraining maximal aerobic capacity (VO(2max)) was performed before and after ET as well as after HDBR. ET increased VO(2max) by 13%. The response of norepinephrine was attenuated after ET and exaggerated after HDBR (P < 0.001). The differences in epinephrine responses were not statistically significant. The responses of cortisol and plasma renin activity (PRA) were unchanged after ET and were enhanced after HDBR (P < 0.001). The response of growth hormone after HDBR was reduced (P < 0.05). Only the change in cortisol response was associated with the increment of VO(2max) after ET (r = 0.68, P < 0.01). Endurance training failed to completely prevent changes in endocrine responses seen after HDBR. Improvement of physical fitness was associated with an enhancement of the cortisol response to exercise following the period of bed rest. PMID:15240416

  15. Physiological Observations and Omics to Develop Personalized Sensormotor Adaptability Countermeasures Using Bed Rest and Space Flight Data

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Seidler, R. D.; Feiveson, A.; Oddsson, L.; Zanello, S.; Oman, C. M.; Ploutz-Snyder, L.; Peters, B.; Cohen, H. S.; Reschke, M.; Wood, S.; Bloomberg, J. J.

    2014-01-01

    Astronauts experience sensorimotor disturbances during the initial exposure to microgravity and during the re-adapation phase following a return to an earth-gravitational environment. These alterations may disrupt the ability to perform mission critical functional tasks requiring ambulation, manual control and gaze stability. Interestingly, astronauts who return from space flight show substantial differences in their abilities to readapt to a gravitational environment. The ability to predict the manner and degree to which individual astronauts would be affected would improve the effectiveness of countermeasure training programs designed to enhance sensorimotor adaptability. For such an approach to succeed, we must develop predictive measures of sensorimotor adaptability that will allow us to foresee, before actual space flight, which crewmembers are likely to experience the greatest challenges to their adaptive capacities. The goals of this project are to identify and characterize this set of predictive measures that include: 1) behavioral tests to assess sensory bias and adaptability quantified using both strategic and plastic-adaptive responses; 2) imaging to determine individual brain morphological and functional features using structural magnetic resonance imaging (MRI), diffusion tensor imaging, resting state functional connectivity MRI, and sensorimotor adaptation task-related functional brain activation; 3) genotype markers for genetic polymorphisms in Catechol-O-Methyl Transferase, Dopamine Receptor D2, Brain-derived neurotrophic factor and genetic polymorphism of alpha2-adrenergic receptor that play a role in the neural pathways underlying sensorimotor adaptation. We anticipate these predictive measures will be significantly correlated with individual differences in sensorimotor adaptability after long-duration space flight and an analog bed rest environment. We will be conducting a retrospective study leveraging data already collected from relevant

  16. The implementation of game in a 20-day head-down tilting bed rest experiment upon mood status and neurotic levels of rest subjects

    NASA Astrophysics Data System (ADS)

    Ishizaki, Yuko; Fukuoka, Hideoki; Ishizaki, Tatsuro; Tanaka, Hidetaka; Ishitobi, Hiromi

    2004-12-01

    This study evaluated the effect of the implementation of game on mental health among participants in a bed rest (BR) experiment. Subjects were 12 healthy males aged 20-26, who participated in a 20-day 6-degrees head-down tilting BR experiment. The participants were asked to complete psychometrical questionnaires before, during, and after the experiment. We entrusted the participants to manage their leisure time and they intended a game in which all of them could take part over the experiment period. The general conversation and light-hearted mood among the subjects continued during the experimental period. Longitudinal data analysis showed that levels of neurosis and mood status did not deteriorate during the experiment, while our previous experiments, which were performed under the same protocol as this study except for the implementation of the game showed a distinct deterioration in psychosocial status. We consider that the implementation of game autonomously contributes to the positive effects on the mental health among the participants.

  17. 49 CFR 24.402 - Replacement housing payment for 90-day occupants.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... occupied the displacement dwelling for at least 90 days immediately prior to the initiation of negotiations... or she moves from the displacement dwelling; or (ii) For an owner-occupant, the later of: (A) The date he or she receives final payment for the displacement dwelling, or in the case of...

  18. 49 CFR 24.402 - Replacement housing payment for 90-day occupants.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... occupied the displacement dwelling for at least 90 days immediately prior to the initiation of negotiations... or she moves from the displacement dwelling; or (ii) For an owner-occupant, the later of: (A) The date he or she receives final payment for the displacement dwelling, or in the case of...

  19. A 90-Day Tenofovir Reservoir Intravaginal Ring for Mucosal HIV Prophylaxis

    PubMed Central

    Johnson, Todd J.; Clark, Meredith R.; Albright, Theodore H.; Nebeker, Joel S.; Tuitupou, Anthony L.; Clark, Justin T.; Fabian, Judit; McCabe, R. Tyler; Chandra, Neelima; Doncel, Gustavo F.; Friend, David R.

    2012-01-01

    A vaginal gel containing the antiretroviral tenofovir (TFV) recently demonstrated 39% protection against HIV infection in women. We designed and evaluated a novel reservoir TFV intravaginal ring (IVR) to potentially improve product effectiveness by providing a more controlled and sustained vaginal dose to maintain cervicovaginal concentrations. Polyurethane tubing of various hydrophilicities was filled with a high-density TFV/glycerol/water semisolid paste and then end-sealed to create IVRs. In vitro, TFV release increased with polyurethane hydrophilicity, with 35 weight percent water-swelling polyurethane IVRs achieving an approximately 10-mg/day release for 90 days with mechanical stiffness similar to that of the commercially available NuvaRing. This design was evaluated in two 90-day in vivo sheep studies for TFV pharmacokinetics and safety. Overall, TFV vaginal tissue, vaginal fluid, and plasma levels were relatively time independent over the 90-day duration at approximately 104 ng/g, 106 ng/g, and 101 ng/ml, respectively, near or exceeding the highest observed concentrations in a TFV 1% gel control group. TFV vaginal fluid concentrations were approximately 1,000-fold greater than levels shown to provide significant protection in women using the TFV 1% gel. There were no toxicological findings following placebo and TFV IVR treatment for 28 or 90 days, although slight to moderate increases in inflammatory infiltrates in the vaginal epithelia were observed in these animals compared to naïve animals. In summary, the controlled release of TFV from this reservoir IVR provided elevated sheep vaginal concentrations for 90 days to merit its further evaluation as an HIV prophylactic. PMID:23006751

  20. Analysis by NASA's VESGEN Software of Retinal Blood Vessels Before and After 70-Day Bed Rest: A Retrospective Study

    NASA Technical Reports Server (NTRS)

    Raghunandan, Sneha; Vyas, Ruchi J.; Vizzeri, Gianmarco; Taibbi, Giovanni; Zanello, Susana B.; Ploutz-Snyder, Robert; Parsons-Wingerter, Patricia A.

    2016-01-01

    Significant risks for visual impairment associated with increased intracranial pressure (VIIP) are incurred by microgravity spaceflight, especially long-duration missions. Impairments include decreased near visual acuity, posterior globe flattening, choroidal folds, optic disc edema and cotton wool spots. We hypothesize that microgravity-induced fluid shifts result in pathological changes within the retinal blood vessels that precede development of visual and other ocular impairments. Potential contributions of retinal vascular remodeling to VIIP etiology are therefore being investigated by NASAs innovative VESsel GENeration Analysis (VESGEN) software for two studies: (1) head-down tilt in human subjects before and after 70 days of bed rest, and (2) U.S. crew members before and after ISS missions. VESGEN analysis in previous research supported by the US National Institutes of Health identified surprising new opportunities to regenerate retinal vessels during early-stage, potentially reversible progression of the visually impairing and blinding disease, diabetic retinopathy.

  1. Effects of 1-week head-down tilt bed rest on bone formation and the calcium endocrine system

    NASA Technical Reports Server (NTRS)

    Arnaud, Sara B.; Whalen, Robert T.; Fung, Paul; Sherrard, Donald J.; Maloney, Norma

    1992-01-01

    The -6-deg head-down tilt (HDT) is employed in the study of 8 subjects to determine early responses in human bone and calcium endocrines during spaceflight. The average rates of bone formation in the iliac crest are determined by means of a single-dose labeling schedule and are found to decrease in 6 of the subjects. The decrease varies directly with walking miles, and increased excretion of urinary Ca and Na are observed preceding increased levels of ionized serum calcium on a bed-rest day late in the week. Reduced phosphorous excretions are also followed by increased serum phosphorous on day six, and reductions are noted in parathyroid hormone and vitamin D by the end of the experiment. The data demonstrate the responsiveness of the skeletal system to biomechanical stimuli such as the HDT.

  2. Effects of 17 days of head-down bed rest on hydro-electrolytic regulation in men

    NASA Technical Reports Server (NTRS)

    Millet, C.; Custaud, M. A.; Allevard, A. M.; Zaouali-Ajina, M.; Monk, T. H.; Arnaud, S. B.; Gharib, C.; Gauquelin-Koch, G.

    2001-01-01

    Prolonged periods of head-down bed rest (HDBR) are commonly used to mimic the effects of microgravity. HDBR has been shown to produce, as in space, a cephalad redistribution of circulating blood volume with an increase in central blood volume which induces the early adaptations in blood volume regulating hormones. Changes in atrial natriuretic peptide (ANP), arginine vasopressin (AVP), renin activity and aldosterone have been observed. Many reports describe these endocrine adaptations but few investigations of rhythms are in the literature. We proposed to evaluate the circadian rhythms of the hormones and electrolytes involved in the hydro-electrolytic regulation during a HDBR study which was designed to simulate a 17-day spaceflight (Life and Microgravity Spacelab experiment, LMS, NASA).

  3. Exercise thermoregulation after 6 h of chair rest, 6 degrees head-down bed-rest, and water immersion deconditioning in men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Hutchinson, T.; Shaffer-Bailey, M.; Looft-Wilson, R.

    1996-01-01

    The purpose was to investigate the mechanism for the excessive exercise hyperthermia following deconditioning (reduction of physical fitness). Rectal (Tre) and mean skin (Tsk) temperatures and thermoregulatory responses were measured in six men [mean (SD) age, 32 (6) years; mass, 78.26 (5.80) kg; surface area, 1.95 (0.11) m2; maximum oxygen uptake (VO2max), 48 (6) ml.min-1.kg-1; whilst supine in air at dry bulb temperature 23.2 (0.6) degree C, relative humidity 31.1 (11.1)% and air speed 5.6 (0.1) m.min-1] during 70 min of leg cycle exercise [51 (4)% VO2max] in ambulatory control (AC), or following 6 h of chair rest (CR), 6 degree head-down bed rest (BR), and 20 degree (WI20) and 80 degree (WI80) foot-down water immersion [water temperature, 35.0 (0.1) degree C]. Compared with the AC exercise delta Tre [mean (SD) 0.77 (0.13) degree C (*P < 0.05), after WI80 0.96 (0.13) degree C*, and after WI20 1.03 (0.09) degree C*. All Tsk responded similarly to exercise: they decreased (NS) by 0.5-0.7 degree C in minutes 4-8 and equilibrated at +0.1 to +0.5 degree C at 60-70. Skin heat conductance was not different among the five conditions (range = 147-159 kJ.m-2.h-1.degree C-1). Results from an intercorrelation matrix suggested that total body sweat rate was more closely related to Tre at 70 min (Tre70) than limb sweat rate or blood flow. Only 36% of the variability in Tre70 could be accounted for by total sweating, and less than 10% from total body dehydration. It would appear that multiple factors are involved which may include change in sensitivity of thermo- and osmoreceptors.

  4. Exercise Thermoregulation After 6 hours of Chair Rest, 6 deg Head-Down Bed-Rest, and Water Immersion Deconditioning in Men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Hutchinson, T.; Shaffer-Bailey, M.; Looft-Wilson, R.

    1996-01-01

    The purpose was to investigate the mechanism for the excessive exercise hyperthermia following deconditioning (reduction of physical fitness). Rectal (T(sub re)) and mean skin (T(bar)(sub sk)) temperatures and thermoregulatory responses were measured in six men [mean (SD) age, 32 (6) years; mass, 78.26 (5.80) kg; surface area, 1.95 (0.11) sq m; maximum oxygen uptake (VO2max), 48 (6) ml/min/kg; whilst supine in air at dry bulb temperature 23.2 (0.6)C, relative humidity 31.1 (11.1)% and air speed 5.6 (0.1) m/min] during 70 min of leg cycle exercise [51 (4)% VO2max] in ambulatory control (AC), or following 6 h of chair rest (CR), 6deg head-down bed rest (BR), and 20deg (W120) and 80deg (W180) foot-down water immersion [water temperature, 35.0 (0.1) C]. Compared with the AC exercise (Delta)T(sub re) [mean (SD) 0.77 (0.13)C], (Delta)T(sub re), after CR was 0.83 (0.08)C (NS), after BR 0.92 (0.13)C (*P <0.05), after W180 0.96 (0.13)C*, and after W120 1.03 (0.09)C*. All T(sub sk) responded similarly to exercise: they decreased (NS) by 0.5-0.7 C in minutes 4-8 and equilibrated at +0.1 to +0.5 C at 60-70. Skin heat conductance was not different among the five conditions (range = 147-159 kJ/sq/C. Results from an intercorrelation matrix suggested that total body sweat rate was more closely related to T(sub re) at 70 min (T(sub re70)) than limb sweat rate or blood flow. Only 36% of the variability in T(sub re70) could be accounted for by total sweating, and less than 10% from total body dehydration. It would appear that multiple factors are involved which may include change in sensitivity of thermo- and osmoreceptors.

  5. Exercise as potential countermeasure for the effects of 70 days of bed rest on cognitive and sensorimotor performance

    PubMed Central

    Koppelmans, Vincent; Mulavara, Ajitkumar P.; Yuan, Peng; Cassady, Kaitlin E.; Cooke, Katherine A.; Wood, Scott J.; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Stepanyan, Vahagn; Szecsy, Darcy L.; Gadd, Nichole E.; Kofman, Igor; Scott, Jessica M.; Downs, Meghan E.; Bloomberg, Jacob J.; Ploutz-Snyder, Lori; Seidler, Rachael D.

    2015-01-01

    Background: Spaceflight has been associated with changes in gait and balance; it is unclear whether it affects cognition. Head down tilt bed rest (HDBR) is a microgravity analog that mimics cephalad fluid shifts and body unloading. In consideration of astronaut’s health and mission success, we investigated the effects of HDBR on cognition and sensorimotor function. Furthermore, we investigated if exercise mitigates any cognitive and sensorimotor sequelae of spaceflight. Method: We conducted a 70-day six-degree HDBR study in 10 male subjects who were randomly assigned to a HDBR supine exercise or a HDBR control group. Cognitive measures (i.e., processing speed, manual dexterity, psychomotor speed, visual dependency, and 2D and 3D mental rotation) and sensorimotor performance (functional mobility (FMT) and balance performance) were collected at 12 and 8 days pre-HDBR, at 7, 50, and 70 days in HDBR, and at 8 and 12 days post-HDBR. Exercise comprised resistance training, and continuous and high-intensity interval aerobic exercise. We also repeatedly assessed an outside-of-bed rest control group to examine metric stability. Results: Small practice effects were observed in the control group for some tasks; these were taken into account when analyzing effects of HDBR. No significant effects of HDBR on cognition were observed, although visual dependency during HDBR remained stable in HDBR controls whereas it decreased in HDBR exercise subjects. Furthermore, HDBR was associated with loss of FMT and standing balance performance, which were almost fully recovered 12 days post-HDBR. Aerobic and resistance exercise partially mitigated the effects of HDBR on FMT and accelerated the recovery time course post-HDBR. Discussion: HDBR did not significantly affect cognitive performance but did adversely affect FMT and standing balance performance. Exercise had some protective effects on the deterioration and recovery of FMT. PMID:26388746

  6. Gender differences in endocrine responses to posture and 7 days of 6 deg head down bed rest

    NASA Technical Reports Server (NTRS)

    Vernikos, J.; Dallman, M. F.; Keil, L. C.; Ohara, D.; Convertino, V. A.

    1993-01-01

    Endocrine regulation of fluids and electrolytes during seven days of 6 deg head down bed rest (HDBR) was compared in male (n = 8) and, for the first time, female (n = 8) volunteers. The subjects' responses to quiet standing for 2 hr before and after HDBR were also tested. In both sexes, diuresis and natriuresis were evident during the first 2-3 days of HDBR, resulting in a marked increase in the urinary Na/K ratio and significant Na retention on reambulation. After the first day of HDBR, plasma renin activity (PRA) was increased relative to aldosterone, plasma volume was decreased, and the renal response to aldosterone appeared to be appropriate. Circulating levels of arginine vasopressin (AVP), cortisol, and ACTH were unchanged during HDBR. Plasma testosterone decreased slightly on day 2 of HDBR in males. The ratio of AM ACTH to cortisol was lower in females than in males because ACTH was lower in females. Urinary cortisol increased and remained elevated throughout the HDBR in males only. There were no gender differences in the responses to 7 day HDBR, except those in the pituitary-adrenal system; those differences appeared unrelated to the postural change. The provocative cardiovascular test of quiet standing before and after bed rest revealed both sex differences and effects of HDBR. There were significant sex differences in cardiovascular responses to standing, before and after HDBR. Females had greater PRA and aldosterone responses to standing before bedrest and larger aldosterone responses to standing after HDBR than males. Cardiovascular responses to standing before and after bedrest differed markedly: arterial pressure and heart rates increased with standing before HDBR, by contrast, arterial pressure decreased, with greater increases in heart rates after HDBR. In both sexes, all hormonal responses to standing were greater after HDBR. The results show clearly that similar responses to standing as well as to HDBR occur in both sexes, but that females exhibit

  7. Impact of 14-day bed rest on serum adipokines and low-grade inflammation in younger and older adults.

    PubMed

    Jurdana, Mihaela; Jenko-Pražnikar, Zala; Mohorko, Nina; Petelin, Ana; Jakus, Tadeja; Šimunič, Boštjan; Pišot, Rado

    2015-12-01

    Ageing and inactivity both contribute to systemic inflammation, but the effects of inactivity on inflammation in healthy elderly individuals have not been elucidated. We hypothesised that 14-day bed rest could affect the pro- and anti-inflammatory markers in young subjects differently than in older adults. A short-term 14-day horizontal bed rest study (BR14) has been used as a model of inactivity in two groups of healthy male volunteers: 7 aged 18-30 years (young) and 16 aged 55-65 years (older adults). The effects of inactivity on inflammation were compared. Key low-grade inflammation mediators, tumour necrosis factor α (TNF-α), interleukin-6 (IL-6), visfatin, resistin, and anti-inflammatory adiponectin were measured in fasting serum samples, collected at baseline (BDC) and post BR14. Young responded to BR14 by increasing serum visfatin and resistin while older adults responded to BR14 by increasing IL-6 and TNF-α. In addition, serum adiponectin increased in all participants. Data from correlation analysis demonstrated positive association between Δ serum visfatin and Δ IL-6 in both groups, while Δ serum adiponectin was negatively associated with Δ TNF-α in young and positively associated with Δ resistin in the older adults. As little as 14 days of complete physical inactivity (BR14) negatively affected markers of low-grade inflammation in both groups, but the inflammation after BR14 was more pronounced in older adults. The effect of BR14 on IL-6 and resistin differed between young and older adults. Inflammatory responses to BR14 in older adults differed from those reported in the literature for obese or subjects in pathological states, suggesting potentially different mechanisms between inactivity- and obesity-induced inflammations.

  8. WISE-2005: Adrenergic Responses Before and After 60 Days of 6 Degree Head-Down Bed-Rest in Women

    NASA Technical Reports Server (NTRS)

    Edgell, H.; Dyson, K.; Shoemaker, J. K.; Custaud, M. A.; Arbeille, Ph.; Greaves, D.; Hughson, R. L.; Hughson, R. L.

    2006-01-01

    Sixteen women who participated in the WISE-2005 headdown bed rest (HDBR) were studied before and on day 56 of bed rest to test the hypothesis that chronic changes in circulating norepinephrine (NOR) would change the response to adrenergic receptor agonists. Five minute infusions of 2 doses of isoproterenol (ISO), and 2 doses of NOR were administered while heart rate (HR), mean arterial pressure (MAP) and total peripheral resistance (TPR) were measured. Before HDBR, the higher dose of ISO increased HR by 13 beats/min (P

  9. The effect of rowing ergometry and resistive exercise on skeletal muscle structure and function during bed rest.

    PubMed

    Krainski, Felix; Hastings, Jeffrey L; Heinicke, Katja; Romain, Nadine; Pacini, Eric L; Snell, Peter G; Wyrick, Phil; Palmer, M Dean; Haller, Ronald G; Levine, Benjamin D

    2014-06-15

    Exposure to microgravity causes functional and structural impairment of skeletal muscle. Current exercise regimens are time-consuming and insufficiently effective; an integrated countermeasure is needed that addresses musculoskeletal along with cardiovascular health. High-intensity, short-duration rowing ergometry and supplemental resistive strength exercise may achieve these goals. Twenty-seven healthy volunteers completed 5 wk of head-down-tilt bed rest (HDBR): 18 were randomized to exercise, 9 remained sedentary. Exercise consisted of rowing ergometry 6 days/wk, including interval training, and supplemental strength training 2 days/wk. Measurements before and after HDBR and following reambulation included assessment of strength, skeletal muscle volume (MRI), and muscle metabolism (magnetic resonance spectroscopy); quadriceps muscle biopsies were obtained to assess muscle fiber types, capillarization, and oxidative capacity. Sedentary bed rest (BR) led to decreased muscle volume (quadriceps: -9 ± 4%, P < 0.001; plantar flexors: -19 ± 6%, P < 0.001). Exercise (ExBR) reduced atrophy in the quadriceps (-5 ± 4%, interaction P = 0.018) and calf muscle, although to a lesser degree (-14 ± 6%, interaction P = 0.076). Knee extensor and plantar flexor strength was impaired by BR (-14 ± 15%, P = 0.014 and -22 ± 7%, P = 0.001) but preserved by ExBR (-4 ± 13%, P = 0.238 and +13 ± 28%, P = 0.011). Metabolic capacity, as assessed by maximal O2 consumption, (31)P-MRS, and oxidative chain enzyme activity, was impaired in BR but stable or improved in ExBR. Reambulation reversed the negative impact of BR. High-intensity, short-duration rowing and supplemental strength training effectively preserved skeletal muscle function and structure while partially preventing atrophy in key antigravity muscles. Due to its integrated cardiovascular benefits, rowing ergometry could be a primary component of exercise prescriptions for astronauts or patients suffering from severe

  10. The effect of rowing ergometry and resistive exercise on skeletal muscle structure and function during bed rest.

    PubMed

    Krainski, Felix; Hastings, Jeffrey L; Heinicke, Katja; Romain, Nadine; Pacini, Eric L; Snell, Peter G; Wyrick, Phil; Palmer, M Dean; Haller, Ronald G; Levine, Benjamin D

    2014-06-15

    Exposure to microgravity causes functional and structural impairment of skeletal muscle. Current exercise regimens are time-consuming and insufficiently effective; an integrated countermeasure is needed that addresses musculoskeletal along with cardiovascular health. High-intensity, short-duration rowing ergometry and supplemental resistive strength exercise may achieve these goals. Twenty-seven healthy volunteers completed 5 wk of head-down-tilt bed rest (HDBR): 18 were randomized to exercise, 9 remained sedentary. Exercise consisted of rowing ergometry 6 days/wk, including interval training, and supplemental strength training 2 days/wk. Measurements before and after HDBR and following reambulation included assessment of strength, skeletal muscle volume (MRI), and muscle metabolism (magnetic resonance spectroscopy); quadriceps muscle biopsies were obtained to assess muscle fiber types, capillarization, and oxidative capacity. Sedentary bed rest (BR) led to decreased muscle volume (quadriceps: -9 ± 4%, P < 0.001; plantar flexors: -19 ± 6%, P < 0.001). Exercise (ExBR) reduced atrophy in the quadriceps (-5 ± 4%, interaction P = 0.018) and calf muscle, although to a lesser degree (-14 ± 6%, interaction P = 0.076). Knee extensor and plantar flexor strength was impaired by BR (-14 ± 15%, P = 0.014 and -22 ± 7%, P = 0.001) but preserved by ExBR (-4 ± 13%, P = 0.238 and +13 ± 28%, P = 0.011). Metabolic capacity, as assessed by maximal O2 consumption, (31)P-MRS, and oxidative chain enzyme activity, was impaired in BR but stable or improved in ExBR. Reambulation reversed the negative impact of BR. High-intensity, short-duration rowing and supplemental strength training effectively preserved skeletal muscle function and structure while partially preventing atrophy in key antigravity muscles. Due to its integrated cardiovascular benefits, rowing ergometry could be a primary component of exercise prescriptions for astronauts or patients suffering from severe

  11. Hummocky moraine: sedimentary record of stagnant Laurentide Ice Sheet lobes resting on soft beds

    NASA Astrophysics Data System (ADS)

    Eyles, N.; Boyce, J. I.; Barendregt, R. W.

    1999-02-01

    Over large areas of the western interior plains of North America, hummocky moraine (HM) formed at the margins of Laurentide Ice Sheet (LIS) lobes that flowed upslope against topographic highs. Current depositional models argue that HM was deposited supraglacially from stagnant debris-rich ice (`disintegration moraine'). Across southern Alberta, Canada, map and outcrop data show that HM is composed of fine-grained till as much as 25 m thick containing rafts of soft, glaciotectonized bedrock and sediment. Chaotic, non-oriented HM commonly passes downslope into weakly-oriented hummocks (`washboard moraine') that are transitional to drumlins in topographic lows; the same subsurface stratigraphy and till facies is present throughout. These landforms, and others such as doughnut-like `rim ridges', flat-topped `moraine plateaux' and linear disintegration ridges, are identified as belonging to subglacially-deposited soft-bed terrain. This terrain is the record of ice lobes moving over deformation till derived from weakly-lithified, bentonite-rich shale. Drumlins record continued active ice flow in topographic lows during deglaciation whereas HM was produced below the outer stagnant margins of ice lobes by gravitational loading (`pressing') of remnant dead ice blocks into wet, plastic till. Intervening zones of washboard moraine mark the former boundary of active and stagnant ice and show `hybrid' drumlins whose streamlined form has been altered by subglacial pressing (` humdrums') below dead ice. The presence of hummocky moraine over a very large area of interior North America provides additional support for glaciological models of a soft-bedded Laurentide Ice Sheet.

  12. Interpersonal relationships in isolation and confinement: Long-term bed rest in head-down tilt position

    NASA Astrophysics Data System (ADS)

    Karine, Weiss; Gabriel, Moser

    The long-term bed-rest was organized by ESA and CNES, in order to simulate the physiological effects of weightlessness: eight volunteers had to stay 42 days in bed, in a head down tilt position (-6 °). There were two subjects in a room, they could not be alone and it was difficult for them to have their own personal space and intimacy. In these circumstances, as in outer space, interpersonal relationships were of prime importance. This situation enabled us, through systematic observation, to analyze the evolution of the relational behavior in dyads, and to quote some social indicators of adaptation. Results show significant withdrawal, and the time spent alone was marked by the emergence, during the experiment, of specific preferential activities. Behavioral contagion was observed in each dyad (people engaged in the same activities at the same time), except in the one case of abandon. Moreover, the highest rates of inactivity and withdrawal were noted in this case. Verbal indicators were useful to comment these results and showed that, for all the dyads, one of the two subjects always played a regulating role by expressing a very positive perception of the situation. These results emphasize the importance of psycho-sociological factors in isolation and confinement. Thus, it appears that different modalities of interpersonal relationships, and not only verbal interactions, play a significant role in adaptation to stress situations.

  13. WISE-2005: effect of aerobic and resistive exercises on orthostatic tolerance during 60 days bed rest in women

    PubMed Central

    Guinet, Patrick; Schneider, Suzanne M.; Macias, Brandon R.; Watenpaugh, Donald E.; Hughson, Richard L.; Le Traon, Anne Pavy; Bansard, Jean-Yves; Hargens, Alan R.

    2009-01-01

    Cardiovascular deconditioning after long duration spaceflight is especially challenging in women who have a lower orthostatic tolerance (OT) compared with men. We hypothesized that an exercise prescription, combining supine aerobic treadmill exercise in a Lower Body Negative Pressure (LBNP) chamber followed by 10 min of resting LBNP, 3 to 4 times a week, and flywheel resistive training every third day would maintain orthostatic tolerance (OT) in women during a 60-day head-down-tilt bed rest (HDBR). Sixteen women were assigned to two groups (exercise, control). Pre and post HDBR OT was assessed with a tilt/LBNP test until presyncope. OT time (mean ± SE) decreased from 17.5±1.0 min to 9.1±1.5 min (−50±6%) in control group (p<0.001) and from 19.3 ±1.3 min to 13.0 ± 1.9 min (−35±7%) in exercise group (p<0.001), with no significant difference in OT time between the two groups after HDBR (p=0.13). Nevertheless compared with controls post HDBR, exercisers had a lower heart rate (mean±SE) during supine rest (71±3 versus 85±4, p<0.01), a slower increase in heart rate and a slower decrease in stroke volume over the course of tilt/LBNP test (p<0.05). Blood volume (mean±SE) decreased in controls (−9±2%, p<0.01) but was maintained in exercisers (−4±3%, p=0.17). Our results suggest that the combined exercise countermeasure fails to protect OT but improves cardiovascular response to subtolerance levels of orthostatic stress. PMID:19247686

  14. Effect of leg exercise training on vascular volumes during 30 days of 6 degrees head-down bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Vernikos, J.; Wade, C. E.; Barnes, P. R.

    1992-01-01

    Plasma and red cell volumes, body density, and water balance were measured in 19 men (32-42 yr) confined to bed rest (BR). One group (n = 5) had no exercise training (NOE), another near-maximal variable-intensity isotonic exercise for 60 min/day (ITE; n = 7), and the third near-maximal intermittent isokinetic exercise for 60 min/day (IKE; n = 7). Caloric intake was 2,678-2,840 kcal/day; mean body weight (n = 19) decreased by 0.58 +/- 0.35 (SE) kg during BR due to a negative fluid balance (diuresis) on day 1. Mean energy costs for the NOE, and IKE, and ITE regimens were 83 (3.6 +/- 0.2 ml O2.min-1.kg-1), 214 (8.9 +/- 0.5 ml.min-1.kg-1), and 446 kcal/h (18.8 +/- 1.6 ml.min-1.kg-1), respectively. Body densities within groups and mean urine volumes (1,752-1,846 ml/day) between groups were unchanged during BR. Resting changes in plasma volume (ml/kg) after BR were -1.5 +/- 2.3% (NS) in ITE, -14.7 +/- 2.8% (P less than 0.05) in NOE, and -16.8 +/- 2.9% (P less than 0.05) in IKE, and mean water balances during BR were +295, -106, and +169 ml/24 h, respectively. Changes in red cell volume followed changes in plasma volume. The significant chronic decreases in plasma volume in the IKE and NOE groups and its maintenance in the ITE group could not be accounted for by water balance or by responses of the plasma osmotic, protein, vasopressin, or aldosterone concentrations or plasma renin activity. There was close coupling between resting plasma volume and plasma protein and osmotic content.(ABSTRACT TRUNCATED AT 250 WORDS).

  15. WISE-2005: effect of aerobic and resistive exercises on orthostatic tolerance during 60 days bed rest in women.

    PubMed

    Guinet, Patrick; Schneider, Suzanne M; Macias, Brandon R; Watenpaugh, Donald E; Hughson, Richard L; Le Traon, Anne Pavy; Bansard, Jean-Yves; Hargens, Alan R

    2009-05-01

    Cardiovascular deconditioning after long duration spaceflight is especially challenging in women who have a lower orthostatic tolerance (OT) compared with men. We hypothesized that an exercise prescription, combining supine aerobic treadmill exercise in a lower body negative pressure (LBNP) chamber followed by 10 min of resting LBNP, three to four times a week, and flywheel resistive training every third day would maintain orthostatic tolerance (OT) in women during a 60-day head-down-tilt bed rest (HDBR). Sixteen women were assigned to two groups (exercise, control). Pre and post HDBR OT was assessed with a tilt/LBNP test until presyncope. OT time (mean +/- SE) decreased from 17.5 +/- 1.0 min to 9.1 +/- 1.5 min (-50 +/- 6%) in control group (P < 0.001) and from 19.3 +/- 1.3 min to 13.0 +/- 1.9 min (-35 +/- 7%) in exercise group (P < 0.001), with no significant difference in OT time between the two groups after HDBR (P = 0.13). Nevertheless, compared with controls post HDBR, exercisers had a lower heart rate during supine rest (mean +/- SE, 71 +/- 3 vs. 85 +/- 4, P < 0.01), a slower increase in heart rate and a slower decrease in stroke volume over the course of tilt/LBNP test (P < 0.05). Blood volume (mean +/- SE) decreased in controls (-9 +/- 2%, P < 0.01) but was maintained in exercisers (-4 +/- 3%, P = 0.17).Our results suggest that the combined exercise countermeasure did not significantly improve OT but protected blood volume and cardiovascular response to sub tolerance levels of orthostatic stress. PMID:19247686

  16. Safety assessment of meat from transgenic cattle by 90-day feeding study in rats.

    PubMed

    Liu, Shan; Li, Chen-Xi; Feng, Xiao-Lian; Wang, Hui-Ling; Liu, Hai-Bo; Zhi, Yuan; Geng, Gui-Ying; Zhao, Jie; Xu, Hai-Bin

    2013-07-01

    The study was carried out to evaluate the subchronic toxicity of meat derived from human lactoferrin gene-modified cattle in male and female Wistar rats. Rats were fed 5% or 10% transgenic meat diet, 5% or 10% conventional meat diet, or AIN93G diet for 90 days. During the study, body weight and food consumption were weighed weekly and clinical observations were conducted daily. At the end of the study, urinary examination, hematology and blood biochemistry examination, macroscopic and microscopic examinations were performed. There were no biologically significant differences in these factors between the rat groups fed transgenic meat diet and conventional meat diet. Therefore, the present 90-day rodent feeding study suggests that meat derived from the transgenic cattle is equivalent to meat from conventional cattle in use as dietary supplements.

  17. 12 CFR 220.117 - Exception to 90-day rule in special cash account.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the language and intent of the above-quoted exception in § 220.4(c)(8), until it has been honored by... substantially the same as language found in section 4(f) of Regulation T as originally promulgated in 1934. The language of the subject exception to the 90-day rule of § 220.4(c)(8), i.e., the exception based...

  18. Association Between Cardiovascular and Intraocular Pressure Changes in a 14-Day 6 deg Head Down Tilt (HDT) Bed Rest Study: Possible Implications in Retinal Anatomy

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita; Zanello, Susana; Yarbough, Patrice; Ploutz-Snyder, Robert; Taibbi, Giovanni; Vizzeri, Gianmarco

    2013-01-01

    Visual symptoms and intracranial pressure increase reported in astronauts returning from long duration missions in low Earth-orbit are thought to be related to fluid shifts within the body due to microgravity exposure. Because of this possible relation to fluid shifts, studies conducted in head-down tilt (HDT) bed rest are being monitored for potential changes in ocular health. These measures will also serve to determine whether HDT is a suitable ground-based analog to model subclinical cardiovascular and ocular changes that could shed light on the etiology of the VIIP syndrome observed in spaceflight. Sixteen healthy normotensive (12M, 4F, age range 29-54 years), non-smoker and normal weight subjects, volunteered to participate in a 14 day 6 deg head HDT study conducted at the NASA Flight Analogs Research Unit (FARU). This facility provides standard bed rest conditions (diet, wake/sleep time, time allowed in sunlight) during the time that the subjects stay at the FARU. Cardiovascular parameters were obtained in supine posture at BR-5, BR+0, and BR+3 and ocular monitoring was performed weekly. Intraocular pressure (IOP) increased from pre-bed rest BR-3) to the third day into bed rest (BR+3). Values reached a plateau towards the end of the bed rest phase (BR10) and decreased within the first three days of recovery (BR+2) returning to levels comparable to baseline at BR-3. As expected, most cardiovascular parameters were affected by 14 days of HDT bed rest. Plasma volume decreased as a result of bed rest but recovered to baseline levels by BR+3. Indications of cardiovascular deconditioning included increase in both systolic and diastolic blood pressure and heart rate, and a decrease in stroke volume and cardiac output between BR-5 and BR+3. Due to the experimental design of this study, we were not able to test the hypothesis that fluid shifts might be involved in the IOP increase during the bed rest phase, since cardiovascular measures were not available for those

  19. 78 FR 41716 - Hours of Service; Limited 90-Day Waiver From the 30-Minute Rest Break Requirement for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-11

    ... December 27, 2011 (76 FR 81133), FMCSA published a final rule amending its hours-of-service regulations for... CFR 395.1(k), 78 FR 16189). Therefore, the waiver would not be applicable to them, leaving fewer than... final rule published on March 14, 2013 (78 FR 16189). In addition, section 32934 of MAP-21...

  20. Pharmacokinetics of Intranasal Scopolamine Gel Formulation During Antiorthostatic Bed Rest, a Microgravity Analog

    NASA Technical Reports Server (NTRS)

    Singh, Rajendra P.; Daniels, Vernie R.; Crady, Camille J.; Derendorf, H.; Putcha, L.

    2011-01-01

    Statement of Purpose, Innovation or Hypothesis: Space Motion sickness (SMS) is a long-standing problem for astronauts on both short and long duration space flights. Scopolamine (SCOP) is frequently used for the treatment of motion sickness (MS), and is available as transdermal patch and tablet dosage forms. These formulations of SCOP are ineffective for the treatment of SMS. Intranasal dosage forms are noninvasive with rapid absorption and enhanced bioavailability, thus allowing precise and reduced dosing in addition to offering rescue and treatment options. An intranasal gel dosage formulation of scopolamine (INSCOP) was developed and pharmacokinetics (PK) and bioavailability were determined in clinical trials with human subjects under IND guidelines.Description of Methods and Materials: The present clinical trial compares PK and bioavailability of INSCOP in 12 normal, healthy subjects (6 male/ 6 female) during ambulation (AMB) and antiorthostaticbed rest (ABR) used as a ground-based microgravity analog. Subjects received 0.2 mg and 0.4 mg doses of INSCOP during AMB and ABR in a 4-way crossover design.Data and Results: Results indicated no difference between AMB and ABR in PK parameters after 0.2 mg dose, Clearance (Cls) decreased with a concomitant increase in maximum concentration and area under concentration-versus-time curve (AUC) during ABR after the 0.4 mg dose.Interpretation, Conclusion or Significance: The difference in AUC and Cls at the higher (0.4 mg) but not the lower dose (0.2 mg) during ABR suggests that ABR may affect metabolism and/or clearance of INSCOP at higher doses . These results indicate that dosing adjustment may be required for treatment of SMS with INSCOP in space.

  1. Effects of normobaric hypoxic bed rest on the thermal comfort zone.

    PubMed

    Ciuha, Ursa; Eiken, Ola; Mekjavic, Igor B

    2015-01-01

    Future Lunar and Mars habitats will maintain a hypobaric hypoxic environment to minimise the risk of decompression sickness during the preparation for extra-vehicular activity. This study was part of a larger study investigating the separate and combined effects of inactivity associated with reduced gravity and hypoxia, on the cardiovascular, musculoskeletal, neurohumoural, and thermoregulatory systems. Eleven healthy normothermic young male subjects participated in three trials conducted on separate occasions: (1) Normobaric hypoxic ambulatory confinement, (2) Normobaric hypoxic bedrest and (3) Normobaric normoxic bedrest. Normobaric hypoxia was achieved by reduction of the oxygen fraction in the air (FiO2 = 0.141 ± 0.004) within the facility, while the effects of reduced gravity were simulated by confining the subjects to a horizontal position in bed, with all daily routines performed in this position for 21 days. The present study investigated the effect of the interventions on behavioural temperature regulation. The characteristics of the thermal comfort zone (TCZ) were assessed by a water-perfused suit, with the subjects instructed to regulate the sinusoidally varying temperature of the suit within a range considered as thermally comfortable. Measurements were performed 5 days prior to the intervention (D-5), and on days 10 (D10) and 20 (D20) of the intervention. no statistically significant differences were found in any of the characteristics of the TCZ between the interventions (HAMB, HBR and NBR), or between different measurement days (D-5, D10, D20) within each intervention. rectal temperature remained stable, whereas skin temperature (Tsk) increased during all interventions throughout the one hour trial. no difference in Tsk between D-5, D10 and D20, and between HAMB, HBR and NBR were revealed. subjects perceived the regulated temperature as thermally comfortable, and neutral or warm. we conclude that regulation of thermal comfort is not compromised by

  2. Effects of normobaric hypoxic bed rest on the thermal comfort zone.

    PubMed

    Ciuha, Ursa; Eiken, Ola; Mekjavic, Igor B

    2015-01-01

    Future Lunar and Mars habitats will maintain a hypobaric hypoxic environment to minimise the risk of decompression sickness during the preparation for extra-vehicular activity. This study was part of a larger study investigating the separate and combined effects of inactivity associated with reduced gravity and hypoxia, on the cardiovascular, musculoskeletal, neurohumoural, and thermoregulatory systems. Eleven healthy normothermic young male subjects participated in three trials conducted on separate occasions: (1) Normobaric hypoxic ambulatory confinement, (2) Normobaric hypoxic bedrest and (3) Normobaric normoxic bedrest. Normobaric hypoxia was achieved by reduction of the oxygen fraction in the air (FiO2 = 0.141 ± 0.004) within the facility, while the effects of reduced gravity were simulated by confining the subjects to a horizontal position in bed, with all daily routines performed in this position for 21 days. The present study investigated the effect of the interventions on behavioural temperature regulation. The characteristics of the thermal comfort zone (TCZ) were assessed by a water-perfused suit, with the subjects instructed to regulate the sinusoidally varying temperature of the suit within a range considered as thermally comfortable. Measurements were performed 5 days prior to the intervention (D-5), and on days 10 (D10) and 20 (D20) of the intervention. no statistically significant differences were found in any of the characteristics of the TCZ between the interventions (HAMB, HBR and NBR), or between different measurement days (D-5, D10, D20) within each intervention. rectal temperature remained stable, whereas skin temperature (Tsk) increased during all interventions throughout the one hour trial. no difference in Tsk between D-5, D10 and D20, and between HAMB, HBR and NBR were revealed. subjects perceived the regulated temperature as thermally comfortable, and neutral or warm. we conclude that regulation of thermal comfort is not compromised by

  3. Bed rest following embryo transfer might negatively affect the outcome of IVF/ICSI: a systematic review and meta-analysis.

    PubMed

    Craciunas, Laurentiu; Tsampras, Nikolaos

    2016-04-01

    The majority of patients undergoing in vitro fertilization (IVF) and intracytoplasmatic sperm injection (ICSI) treatment will reach the stage of embryo transfer (ET), but only a small proportion of transferred embryos implant. Bed rest following ET has been recommended as a way to prevent embryo expulsion by gravity. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) published prior to May 2014 reporting the effect of bed rest following ET, and irrespective of language, country of origin, blinding or sample size. Four RCTs, including 757 women met the inclusion criteria. Bed rest following ET did not improve clinical pregnancy and live birth rates, but reduced the implantation rate. The quality of the trials included was moderate because of attrition bias and possible reporting bias. The findings of this systematic review and meta-analysis are concordant with previously published literature and suggest that bed rest is not beneficial following ET. Moreover, it might negatively affect the outcome of IVF/ICSI cycles via stress/anxiety mechanisms.

  4. Bed rest following embryo transfer might negatively affect the outcome of IVF/ICSI: a systematic review and meta-analysis.

    PubMed

    Craciunas, Laurentiu; Tsampras, Nikolaos

    2016-04-01

    The majority of patients undergoing in vitro fertilization (IVF) and intracytoplasmatic sperm injection (ICSI) treatment will reach the stage of embryo transfer (ET), but only a small proportion of transferred embryos implant. Bed rest following ET has been recommended as a way to prevent embryo expulsion by gravity. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) published prior to May 2014 reporting the effect of bed rest following ET, and irrespective of language, country of origin, blinding or sample size. Four RCTs, including 757 women met the inclusion criteria. Bed rest following ET did not improve clinical pregnancy and live birth rates, but reduced the implantation rate. The quality of the trials included was moderate because of attrition bias and possible reporting bias. The findings of this systematic review and meta-analysis are concordant with previously published literature and suggest that bed rest is not beneficial following ET. Moreover, it might negatively affect the outcome of IVF/ICSI cycles via stress/anxiety mechanisms. PMID:26986834

  5. Blood volume regulating hormones response during two space related simulation protocols: Four-week confinement and head-down bed-rest

    NASA Astrophysics Data System (ADS)

    Maillet, A.; Gauquelin, G.; Gunga, H. C.; Fortrat, J. O.; Kirsch, K.; Guell, A.; Bizollon, Ch. A.; Gharib, C.

    1995-04-01

    The volume of regulating hormones (renin, aldosterone, arginine vasopressin and atrial natriuretic factor), electrolytes and creatinine concentrations, and blood pressure were measured in two different four-week experimental protocols: respectively -6 ° head-down bed-rest (5 subjects) and confinement (6 subjects). We observed a significant increase ( P < 0.01 at D2 vs D-5) of systolic blood pressure during confinement and a different level of response for some hormones, especially for arginine vasopressin (300% increase during confinement instead of 50% during bed-rest). The renin-angiotensin-aldosterone system was enhanced during confinement and head-down bed-rest. In both conditions, we obtained a similar pattern of response for blood volume regulating hormones. During confinement, two main factors were inactivity and stress activation of the sympathetic nervous system. In the bed-rest study the response is principally due to the fluid shift and blood volume adaptation but it is not possible to exclude the role of inactivity and stress.

  6. Using Natural Stable Calcium Isotopes to Rapidly Assess Changes in Bone Mineral Balance Using a Bed Rest Model to Induce Bone Loss

    NASA Technical Reports Server (NTRS)

    Morgan, J. L. L.; Skulan, J. L.; Gordon, G. E.; Smith, Scott M.; Romaniello, S. J.; Anbar, A. D.

    2012-01-01

    Metabolic bone diseases like osteoporosis result from the disruption of normal bone mineral balance (BMB) resulting in bone loss. During spaceflight astronauts lose substantial bone. Bed rest provides an analog to simulate some of the effects of spaceflight; including bone and calcium loss and provides the opportunity to evaluate new methods to monitor BMB in healthy individuals undergoing environmentally induced-bone loss. Previous research showed that natural variations in the Ca isotope ratio occur because bone formation depletes soft tissue of light Ca isotopes while bone resorption releases that isotopically light Ca back into soft tissue (Skulan et al, 2007). Using a bed rest model, we demonstrate that the Ca isotope ratio of urine shifts in a direction consistent with bone loss after just 7 days of bed rest, long before detectable changes in bone mineral density (BMD) occur. The Ca isotope variations tracks changes observed in urinary N-teleopeptide, a bone resorption biomarker. Bone specific alkaline phosphatase, a bone formation biomarker, is unchanged. The established relationship between Ca isotopes and BMB can be used to quantitatively translate the changes in the Ca isotope ratio to changes in BMD using a simple mathematical model. This model predicts that subjects lost 0.25 0.07% ( SD) of their bone mass from day 7 to day 30 of bed rest. Given the rapid signal observed using Ca isotope measurements and the potential to quantitatively assess bone loss; this technique is well suited to study the short-term dynamics of bone metabolism.

  7. PlanHab: Hypoxia counteracts the erythropoietin suppression, but seems to exaggerate the plasma volume reduction induced by 3 weeks of bed rest.

    PubMed

    Keramidas, Michail E; Mekjavic, Igor B; Kölegård, Roger; Choukèr, Alexander; Strewe, Claudia; Eiken, Ola

    2016-04-01

    The study examined the distinct and synergistic effects of hypoxia and bed rest on the erythropoietin (EPO) concentration and relative changes in plasma volume (PV). Eleven healthy male lowlanders underwent three 21-day confinement periods, in a counterbalanced order: (1) normoxic bed rest (NBR; PIO2: 133.1 ± 0.3 mmHg); (2) hypoxic bed rest (HBR; PIO2: 90.0 ± 0.4 mmHg, ambient simulated altitude of ~4000 m); and (3) hypoxic ambulation (HAMB; PIO2: 90.0 ± 0.4 mmHg). Blood samples were collected before, during (days 2, 5, 14, and 21) and 2 days after each confinement to determineEPOconcentration. Qualitative differences inPVchanges were also estimated by changes in hematocrit and hemoglobin concentration along with concomitant changes in plasma renin concentration.NBRcaused an initial reduction inEPOby ~39% (P = 0.04). By contrast,HBRenhancedEPO(P = 0.001), but the increase was less than that induced byHAMB(P < 0.01). All three confinements caused a significant reduction inPV(P < 0.05), with a substantially greater drop inHBRthan in the other conditions (P < 0.001). Thus, present results suggest that hypoxia prevents theEPOsuppression, whereas it seems to exaggerate thePVreduction induced by bed rest. PMID:27081163

  8. Evaluation of Treadmill Exercise in a Lower Body Negative Pressure Chamber as a Countermeasure for Weightlessness-Induced Bone Loss: a Bed Rest Study with Identical Twins

    NASA Technical Reports Server (NTRS)

    Smith, Scott M.; Davis-Street, Janis E.; Fesperman, J. Vernell; Calkins, D. S.; Bawa, Maneesh; Macias, Brandon R.; Meyer, R. Scott; Hargens, Alan R.

    2003-01-01

    Counteracting bone loss is required for future space exploration. We evaluated the ability of treadmill exercise in a LBNP chamber to counteract bone loss in a 30-day bed rest study. Eight pairs of identical twins were randomly assigned to sedentary control or exercise groups. Exercise within LBNP decreased the bone resorption caused by bed rest and may provide a countermeasure for spaceflight. INTRODUCTION: Bone loss is one of the greatest physiological challenges for extended-duration space missions. The ability of exercise to counteract weightlessness-induced bone loss has been studied extensively, but to date, it has proven ineffective. We evaluated the effectiveness of a combination of two countermeasures-treadmill exercise while inside a lower body negative pressure (LBNP) chamber-on bone loss during a 30-day bed rest study. MATERIALS AND METHODS: Eight pairs of identical twins were randomized into sedentary (SED) or exercise/LBNP (EX/LBNP) groups. Blood and urine samples were collected before, several times during, and after the 30-day bed rest period. These samples were analyzed for markers of bone and calcium metabolism. Repeated measures ANOVA was used to determine statistical significance. Because identical twins were used, both time and group were treated as repeated variables. RESULTS: Markers of bone resorption were increased during bed rest in samples from sedentary subjects, including the collagen cross-links and serum and urinary calcium concentrations. For N-telopeptide and deoxypyridinoline, there were significant (p < 0.05) interactions between group (SED versus EX/LBNP) and phase of the study (sample collection point). Pyridinium cross-links were increased above pre-bed rest levels in both groups, but the EX/LBNP group had a smaller increase than the SED group. Markers of bone formation were unchanged by bed rest in both groups. CONCLUSIONS: These data show that this weight-bearing exercise combined with LBNP ameliorates some of the negative

  9. The effects of twelve weeks of bed rest on bone histology, biochemical markers of bone turnover, and calcium homeostasis in eleven normal subjects

    NASA Technical Reports Server (NTRS)

    Zerwekh, J. E.; Ruml, L. A.; Gottschalk, F.; Pak, C. Y.; Blomqvist, C. G. (Principal Investigator)

    1998-01-01

    This study was undertaken to examine the effects of 12 weeks of skeletal unloading on parameters of calcium homeostasis, calcitropic hormones, bone histology, and biochemical markers of bone turnover in 11 normal subjects (9 men, 2 women; 34 +/- 11 years of age). Following an ambulatory control evaluation, all subjects underwent 12 weeks of bed rest. An additional metabolic evaluation was performed after 12 days of reambulation. Bone mineral density declined at the spine (-2.9%, p = 0.092) and at the hip (-3.8%, p = 0.002 for the trochanter). Bed rest prompted a rapid, sustained, significant increase in urinary calcium and phosphorus as well as a significant increase in serum calcium. Urinary calcium increased from a pre-bed rest value of 5.3 mmol/day to values as high as 73 mmol/day during bed rest. Immunoreactive parathyroid hormone and serum 1,25-dihydroxyvitamin D declined significantly during bed rest, although the mean values remained within normal limits. Significant changes in bone histology included a suppression of osteoblastic surface for cancellous bone (3.1 +/- 1.3% to 1.9 +/- 1.5%, p = 0.0142) and increased bone resorption for both cancellous and cortical bone. Cortical eroded surface increased from 3.5 +/- 1.1% to 7.3 +/- 4.0% (p = 0.018) as did active osteoclastic surface (0.2 +/- 0.3% to 0.7 +/- 0.7%, p = 0.021). Cancellous eroded surface increased from 2.1 +/- 1.1% to 4.7 +/- 2.2% (p = 0.002), while mean active osteoclastic surface doubled (0.2 +/- 0.2% to 0.4 +/- 0.3%, p = 0.020). Serum biochemical markers of bone formation (osteocalcin, bone-specific alkaline phosphatase, and type I procollagen extension peptide) did not change significantly during bed rest. Urinary biochemical markers of bone resorption (hydroxyproline, deoxypyridinoline, and N-telopeptide of type I collagen) as well as a serum marker of bone resorption (type I collagen carboxytelopeptide) all demonstrated significant increases during bed rest which declined toward normal

  10. Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men

    NASA Technical Reports Server (NTRS)

    Smorawinski, J.; Nazar, K.; Kaciuba-Uscilko, H.; Kaminska, E.; Cybulski, G.; Kodrzycka, A.; Bicz, B.; Greenleaf, J. E.

    2001-01-01

    To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

  11. Using RFID and accelerometer-embedded tracers to measure probabilities of bed load transport, step lengths, and rest times in a mountain stream

    NASA Astrophysics Data System (ADS)

    Olinde, Lindsay; Johnson, Joel P. L.

    2015-09-01

    We present new measurements of bed load tracer transport in a mountain stream over several snowmelt seasons. Cumulative displacements were measured using passive tracers, which consisted of gravel and cobbles embedded with radio frequency identification tags. The timing of bed load motion during 11 transporting events was quantified with active tracers, i.e., accelerometer-embedded cobbles. Probabilities of cobble transport increased with discharge above a threshold, and exhibited slight to moderate hysteresis during snowmelt hydrographs. Dividing cumulative displacements by the number of movements recorded by each active tracer constrained average step lengths. Average step lengths increased with discharge, and distributions of average step lengths and cumulative displacements were thin tailed. Distributions of rest times followed heavy-tailed power law scaling. Rest time scaling varied somewhat with discharge and with the degree to which tracers were incorporated into the streambed. The combination of thin-tailed displacement distributions and heavy-tailed rest time distributions predict superdiffusive dispersion.

  12. The impact of 90-day prescriptions on adherence at workplace pharmacies compared to traditional mail order.

    PubMed

    Patwardhan, Avinash; Davis, Jeffery; Murphy, Patricia; Khandelwal, Nikhil; Sherman, Bruce; Manfred, James

    2011-12-01

    This study evaluated adherence to medications used to treat chronic conditions for patients with 90-day prescriptions, comparing patients with access to workplace pharmacy services versus patients using mail order services. De-identified pharmacy claims data were used to compute medication possession ratio and gaps in therapy. Results were compared for patients who filled 90-day prescriptions at workplace pharmacies versus patients who filled 90-day prescriptions using mail order pharmacy services in a 1-year period. Statistical tests to assess between group differences were performed controlling for differences because of age, sex, number of select chronic conditions, number of unique medication therapeutic classes, and patient out-of-pocket cost per therapy day. Statistically significant differences were found between patients who filled their maintenance medications at the worksite compared to those who used mail-order pharmacy services. Patients filling prescriptions at a workplace pharmacy were 22% less likely to have a gap in therapy of over 30 days compared to similar patients using mail order services. Workplace pharmacy utilizers also had overall adherence rates 3.68% higher than patients who utilized mail order pharmacy services. Our analysis suggests that it may not be just the quantity of medication dispensed that impacts patients' adherence to their prescription medication, but a variety of other factors including pharmacist-patient interaction. Having a pharmacist on-site and available to patients with chronic considerations could provide added value. These results can aid employers and other stakeholders to decide which prescription benefits to offer their employees and members. PMID:22092153

  13. On the combined effects of normobaric hypoxia and bed rest upon bone and mineral metabolism: Results from the PlanHab study.

    PubMed

    Rittweger, Jörn; Debevec, Tadej; Frings-Meuthen, Petra; Lau, Patrick; Mittag, Uwe; Ganse, Bergita; Ferstl, Philip G; Simpson, Elizabeth J; Macdonald, Ian A; Eiken, Ola; Mekjavic, Igor B

    2016-10-01

    Bone losses are common as a consequence of unloading and also in patients with chronic obstructive pulmonary disease (COPD). Although hypoxia has been implicated as an important factor to drive bone loss, its interaction with unloading remains unresolved. The objective therefore was to assess whether human bone loss caused by unloading could be aggravated by chronic hypoxia. In a cross-over designed study, 14 healthy young men underwent 21-day interventions of bed rest in normoxia (NBR), bed rest in hypoxia (HBR), and hypoxic ambulatory confinement (HAmb). Hypoxic conditions were equivalent to 4000m altitude. Bone metabolism (NTX, P1NP, sclerostin, DKK1) and phospho-calcic homeostasis (calcium and phosphate serum levels and urinary excretion, PTH) were assessed from regular blood samples and 24-hour urine collections, and tibia and femur bone mineral content was assessed by peripheral quantitative computed tomography (pQCT). Urinary NTX excretion increased (P<0.001) to a similar extent in NBR and HBR (P=0.69) and P1NP serum levels decreased (P=0.0035) with likewise no difference between NBR and HBR (P=0.88). Serum total calcium was increased during bed rest by 0.059 (day D05, SE 0.05mM) to 0.091mM (day D21, P<0.001), with no additional effect by hypoxia during bed rest (P=0.199). HAmb led, at least temporally, to increased total serum calcium, to reduced serum phosphate, and to reduced phosphate and calcium excretion. In conclusion, hypoxia did not aggravate bed rest-induced bone resorption, but led to changes in phospho-calcic homeostasis likely caused by hyperventilation. Whether hyperventilation could have mitigated the effects of hypoxia in this study remains to be established. PMID:27443510

  14. One Week of Bed Rest Leads to Substantial Muscle Atrophy and Induces Whole-Body Insulin Resistance in the Absence of Skeletal Muscle Lipid Accumulation.

    PubMed

    Dirks, Marlou L; Wall, Benjamin T; van de Valk, Bas; Holloway, Tanya M; Holloway, Graham P; Chabowski, Adrian; Goossens, Gijs H; van Loon, Luc J C

    2016-10-01

    Short (<10 days) periods of muscle disuse, often necessary for recovery from illness or injury, lead to various negative health consequences. The current study investigated mechanisms underlying disuse-induced insulin resistance, taking into account muscle atrophy. Ten healthy, young males (age: 23 ± 1 years; BMI: 23.0 ± 0.9 kg · m(-2)) were subjected to 1 week of strict bed rest. Prior to and after bed rest, lean body mass (dual-energy X-ray absorptiometry) and quadriceps cross-sectional area (CSA; computed tomography) were assessed, and peak oxygen uptake (VO2peak) and leg strength were determined. Whole-body insulin sensitivity was measured using a hyperinsulinemic-euglycemic clamp. Additionally, muscle biopsies were collected to assess muscle lipid (fraction) content and various markers of mitochondrial and vascular content. Bed rest resulted in 1.4 ± 0.2 kg lean tissue loss and a 3.2 ± 0.9% decline in quadriceps CSA (both P < 0.01). VO2peak and one-repetition maximum declined by 6.4 ± 2.3 (P < 0.05) and 6.9 ± 1.4% (P < 0.01), respectively. Bed rest induced a 29 ± 5% decrease in whole-body insulin sensitivity (P < 0.01). This was accompanied by a decline in muscle oxidative capacity, without alterations in skeletal muscle lipid content or saturation level, markers of oxidative stress, or capillary density. In conclusion, 1 week of bed rest substantially reduces skeletal muscle mass and lowers whole-body insulin sensitivity, without affecting mechanisms implicated in high-fat diet-induced insulin resistance.

  15. Isokinetic Strength and Endurance During 30-day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bond, M.; Bulbulian, R.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle orgometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  16. No effect of artificial gravity on lung function with exercise training during head-down bed rest

    NASA Astrophysics Data System (ADS)

    Su, Longxiang; Guo, Yinghua; Wang, Yajuan; Wang, Delong; Liu, Changting

    2016-04-01

    The aim of this study is to explore the effectiveness of microgravity simulated by head-down bed rest (HDBR) and artificial gravity (AG) with exercise on lung function. Twenty-four volunteers were randomly divided into control and exercise countermeasure (CM) groups for 96 h of 6° HDBR. Comparisons of pulse rate, pulse oxygen saturation (SpO2) and lung function were made between these two groups at 0, 24, 48, 72, 96 h. Compared with the sitting position, inspiratory capacity and respiratory reserve volume were significantly higher than before HDBR (0° position) (P < 0.05). Vital capacity, expiratory reserve volume, forced vital capacity, forced expiratory volume in 1 s, forced inspiratory vital capacity, forced inspiratory volume in 1 s, forced expiratory flow at 25, 50, and 75%, maximal mid-expiratory flow and peak expiratory flow were all significantly lower than those before HDBR (P < 0.05). Neither control nor CM groups showed significant differences in pulse rate, SpO2, pulmonary volume and pulmonary ventilation function over the HDBR observation time. Postural changes can lead to variation in lung volume and ventilation function, but a HDBR model induced no changes in pulmonary function and therefore should not be used to study AG countermeasures.

  17. Influence of head-down bed rest on the circadian rhythms of hormones and electrolytes involved in hydroelectrolytic regulation

    NASA Technical Reports Server (NTRS)

    Millet, C.; Custaud, M. A.; Allevard, A. M.; Zaouali-Ajina, M.; Monk, T. H.; Arnaud, S. B.; Claustrat, B.; Gharib, C.; Gauquelin-Koch, G.

    2001-01-01

    We investigated in six men the impact of a 17-day head-down bed rest (HDBR) on the circadian rhythms of the hormones and electrolytes involved in hydroelectrolytic regulation. This HDBR study was designed to mimic an actual spaceflight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of aldosterone, arginine vasopressin (AVP), cyclic guanosine monophosphate (cGMP), cortisol, electrolytes (Na+ and K+) and creatinine were determined. HDBR resulted in a significant reduction of body mass (P < 0.01) and of caloric intake [mean (SEM) 2,778 (37) kcal.24 h(-1) to 2,450 (36) kcal.24 h(-1), where 1 kcal.h(-1) = 1.163 J.s(-1); P< 0.01]. There was a significant increase in diastolic blood pressure [71.8 (0.7) mmHg vs 75.6 (0.91) mmHg], with no significant changes in either systolic blood pressure or heart rate. The nocturnal hormonal decrease of aldosterone was clearly evident only before and after HDBR, but the day/night difference did not appear during HDBR. The rhythm of K+ excretion was unchanged during HDBR, whereas for Na+ excretion, a large decrease was shown during the night as compared to the day. The circadian rhythm of cortisol persisted. These data suggest that exposure to a 17-day HDBR could induce an exaggeration of the amplitude of the Na+ rhythm and abolition of the aldosterone rhythm.

  18. Electromyography-based analysis of human upper limbs during 45-day head-down bed-rest

    NASA Astrophysics Data System (ADS)

    Fu, Anshuang; Wang, Chunhui; Qi, Hongzhi; Li, Fan; Wang, Zheng; He, Feng; Zhou, Peng; Chen, Shanguang; Ming, Dong

    2016-03-01

    Muscle deconditioning occurs in response to simulated or actual microgravity. In spaceflight, astronauts become monkey-like for mainly using their upper limbs to control the operating system and to complete corresponding tasks. The changes of upper limbs' athletic ability will directly affect astronauts' working performance. This study investigated the variation trend of surface electromyography (sEMG) during prolonged simulated microgravity. Eight healthy males participating in this study performed strict 45-day head-down bed-rest (HDBR). On the 5th day of pre-HDBR, and the 15th, the 30th and the 45th days of HDBR, the subjects performed maximum pushing task and maximum pulling task, and sEMG was collected from upper limbs synchronously. Each subject's maximum volunteer contractions of both the tasks during these days were compared, showing no significant change. However, changes were detected by sEMG-based analysis. It was found that integrated EMG, root mean square, mean frequency, fuzzy entropy of deltoid, and fuzzy entropy of triceps brachii changed significantly when comparing pre-HDBR with HDBR. The variation trend showed a recovery tendency after significant decline, which is inconsistent with the monotonic variation of lower limbs that was proved by previous research. These findings suggest that EMG changes in upper limbs during prolonged simulated microgravity, but has different variation trend from lower limbs.

  19. Isokinetic strength and endurance during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bulbulian, R.; Bond, M.

    1994-01-01

    The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle ergometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.

  20. Lower Extremity Muscle Thickness During 30-Day 6 degrees Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Ellis, S.; Kirby, L. C.; Greenleaf, J. E.

    1993-01-01

    Muscle thickness was measured in 19 Bed-Rested (BR) men (32-42 year) subjected to IsoTonic (ITE, cycle orgometer) and IsoKi- netic (IKE, torque orgometer) lower extremity exercise training, and NO Exercise (NOE) training. Thickness was measured with ultrasonography in anterior thigh-Rectus Femoris (RF) and Vastus Intermadius (VI), and combined posterior log-soleus, flexor ballucis longus, and tibialis posterior (S + FHL +TP) - muscles. Compared with ambulatory control values, thickness of the (S + FHL + TP) decreased by 90%-12% (p less than 0.05) In all three test groups. The (RF) thickness was unchanged in the two exercise groups, but decreased by 10% (p less than 0.05) in the NOE. The (VI) thickness was unchanged In the ITE group, but decreased by 12%-l6% (p less than 0.05) in the IKE and NOE groups. Thus, intensive, alternating, isotonic cycle ergometer exercise training is as effective as intensive, intermittent, isokinetic exercise training for maintaining thicknesses of rectus femoris and vastus lntermedius anterior thigh muscles, but not posterior log muscles, during prolonged BR deconditioning.

  1. Unilateral lower limb suspension does not mimic bed rest or spaceflight effects on human muscle fiber function

    NASA Technical Reports Server (NTRS)

    Widrick, J. J.; Trappe, S. W.; Romatowski, J. G.; Riley, D. A.; Costill, D. L.; Fitts, R. H.

    2002-01-01

    We used Ca2+-activated skinned muscle fibers to test the hypothesis that unilateral lower leg suspension (ULLS) alters cross-bridge mechanisms of muscle contraction. Soleus and gastrocnemius biopsies were obtained from eight subjects before ULLS, immediately after 12 days of ULLS (post-0 h), and after 6 h of reambulation (post-6 h). Post-0 h soleus fibers expressing type I myosin heavy chain (MHC) showed significant reductions in diameter, absolute and specific peak Ca2+-activated force, unloaded shortening velocity, and absolute and normalized peak power. Fibers obtained from the gastrocnemius were less affected by ULLS, particularly fibers expressing fast MHC isoforms. Post-6 h soleus fibers produced less absolute and specific peak force than did post-0 h fibers, suggesting that reambulation after ULLS induced cell damage. Like bed rest and spaceflight, ULLS primarily affects soleus over gastrocnemius fibers. However, in contrast to these other models, slow soleus fibers obtained after ULLS showed a decrease in unloaded shortening velocity and a greater reduction in specific force.

  2. Influence of head-down bed rest on the circadian rhythms of hormones and electrolytes involved in hydroelectrolytic regulation.

    PubMed

    Millet, C; Custaud, M A; Allevard, A M; Zaouali-Ajina, M; Monk, T H; Arnaud, S B; Claustrat, B; Gharib, C; Gauquelin-Koch, G

    2001-07-01

    We investigated in six men the impact of a 17-day head-down bed rest (HDBR) on the circadian rhythms of the hormones and electrolytes involved in hydroelectrolytic regulation. This HDBR study was designed to mimic an actual spaceflight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of aldosterone, arginine vasopressin (AVP), cyclic guanosine monophosphate (cGMP), cortisol, electrolytes (Na+ and K+) and creatinine were determined. HDBR resulted in a significant reduction of body mass (P < 0.01) and of caloric intake [mean (SEM) 2,778 (37) kcal.24 h(-1) to 2,450 (36) kcal.24 h(-1), where 1 kcal.h(-1) = 1.163 J.s(-1); P< 0.01]. There was a significant increase in diastolic blood pressure [71.8 (0.7) mmHg vs 75.6 (0.91) mmHg], with no significant changes in either systolic blood pressure or heart rate. The nocturnal hormonal decrease of aldosterone was clearly evident only before and after HDBR, but the day/night difference did not appear during HDBR. The rhythm of K+ excretion was unchanged during HDBR, whereas for Na+ excretion, a large decrease was shown during the night as compared to the day. The circadian rhythm of cortisol persisted. These data suggest that exposure to a 17-day HDBR could induce an exaggeration of the amplitude of the Na+ rhythm and abolition of the aldosterone rhythm.

  3. Orthostatic Intolerance Is Independent of the Degree of Autonomic Cardiovascular Adaptation after 60 Days of Head-Down Bed Rest

    PubMed Central

    Liu, Jiexin; Li, Yongzhi; Verheyden, Bart; Chen, Zhanghuang; Wang, Jingyu; Li, Yinghui; Aubert, André E.; Yuan, Ming

    2015-01-01

    Spaceflight and head-down bed rest (HDBR) can induce the orthostatic intolerance (OI); the mechanisms remain to be clarified. The aim of this study was to determine whether or not OI after HDBR relates to the degree of autonomic cardiovascular adaptation. Fourteen volunteers were enrolled for 60 days of HDBR. A head-up tilt test (HUTT) was performed before and after HDBR. Our data revealed that, in all nonfainters, there was a progressive increase in heart rate over the course of HDBR, which remained higher until 12 days of recovery. The mean arterial pressure gradually increased until day 56 of HDBR and returned to baseline after 12 days of recovery. Respiratory sinus arrhythmia and baroreflex sensitivity decreased during HDBR and remained suppressed until 12 days of recovery. Low-frequency power of systolic arterial pressure increased during HDBR and remained elevated during recovery. Three subjects fainted during the HUTT after HDBR, in which systemic vascular resistance did not increase and remained lower until syncope. None of the circulatory patterns significantly differed between the fainters and the nonfainters at any time point. In conclusion, our data indicate that the impaired orthostatic tolerance after HDBR could not be distinguished by estimation of normal hemodynamic and/or neurocardiac data. PMID:26425559

  4. Orthostatic Intolerance Is Independent of the Degree of Autonomic Cardiovascular Adaptation after 60 Days of Head-Down Bed Rest.

    PubMed

    Liu, Jiexin; Li, Yongzhi; Verheyden, Bart; Chen, Zhanghuang; Wang, Jingyu; Li, Yinghui; Aubert, André E; Yuan, Ming

    2015-01-01

    Spaceflight and head-down bed rest (HDBR) can induce the orthostatic intolerance (OI); the mechanisms remain to be clarified. The aim of this study was to determine whether or not OI after HDBR relates to the degree of autonomic cardiovascular adaptation. Fourteen volunteers were enrolled for 60 days of HDBR. A head-up tilt test (HUTT) was performed before and after HDBR. Our data revealed that, in all nonfainters, there was a progressive increase in heart rate over the course of HDBR, which remained higher until 12 days of recovery. The mean arterial pressure gradually increased until day 56 of HDBR and returned to baseline after 12 days of recovery. Respiratory sinus arrhythmia and baroreflex sensitivity decreased during HDBR and remained suppressed until 12 days of recovery. Low-frequency power of systolic arterial pressure increased during HDBR and remained elevated during recovery. Three subjects fainted during the HUTT after HDBR, in which systemic vascular resistance did not increase and remained lower until syncope. None of the circulatory patterns significantly differed between the fainters and the nonfainters at any time point. In conclusion, our data indicate that the impaired orthostatic tolerance after HDBR could not be distinguished by estimation of normal hemodynamic and/or neurocardiac data. PMID:26425559

  5. 90-day dietary toxicity study with esterified propoxylated glycerol (EPG) in rats.

    PubMed

    Christian, Brian J; Bechtel, David H

    2014-12-01

    The subchronic (90-day) toxicity of a "core" version of EPG was assessed in rats. Crl:CD-1®(ICR)BR rats (70/sex) received diets containing a constant level of 5% EPG (w/w) or adjusted to deliver 0 (control), 0.5, 1, or 2g/kg of body weight/day (g/kg bw/day). Subsets of animals from each group (20/sex) were evaluated after 30 days (interim sacrifice); the remainder after 90 days. EPG intake at all dose levels was associated with lower mean liver vitamin E levels; liver vitamin A and serum vitamin D were also lower, but less consistently. Animals given 5% EPG had higher fecal output (males) and cholesterol (males and females) without corresponding changes in serum cholesterol. Urinary pH was also mildly lower in males given 5% EPG. However, detailed evaluation of general health and assessment of blood, organs and tissues showed no evidence that EPG administration compromised the nutritional requirements of the animals, caused a state of fat-soluble vitamin deficiency, or caused' toxicity to any organ system. Based on the results of this study, it was not possible to establish a no-observable-effect level (NOEL). The possible effect of EPG on vitamin levels in the absence of any clinical signs of deficiency was not considered "adverse" per se. As such, the 2g/kg and 5% EPG level were considered to represent a no-observable-adverse-effect levels (NOAELs). PMID:25497991

  6. The 90-day oral toxicity of d-psicose in male Wistar rats

    PubMed Central

    Matsuo, Tatsuhiro; Ishii, Reika; Shirai, Yoko

    2012-01-01

    d-Psicose is a rare sugar present in small quantities in natural products. In a previous study, we showed that d-psicose suppresses increase in plasma glucose and reduces body fat accumulation in rats. Based on acute toxicity testing in rats, d-psicose is classified as an ordinary substance (LD50 = 16 g/kg). Elucidating the effects of sub-chronic feeding of d-psicose in rats is essential before it can be utilized as a physiologically functional food. In this study, male Wistar rats (3 weeks old) were fed diets containing 3% d-psicose or sucrose for 90 days. The body weight gain and intra-abdominal adipose tissue weight did not differ between the sucrose and the d-psicose groups. The weights of the liver and kidneys were significantly higher in the d-psicose group than in the sucrose group. However, no gross pathological findings were evident at dietary doses of 3% d-psicose or were correlated with hypertrophy of the liver and kidney. In a clinical chemistry analysis, the erythrocyte and leukocyte courts were significantly higher in the d-psicose group, but that was not considered to be toxicologically significant. Therefore, the present study found no adverse effects of d-psicose in rats fed a diet containing 3% d-psicosefor 90 days. PMID:22448098

  7. The 90-day oral toxicity of d-psicose in male Wistar rats.

    PubMed

    Matsuo, Tatsuhiro; Ishii, Reika; Shirai, Yoko

    2012-03-01

    d-Psicose is a rare sugar present in small quantities in natural products. In a previous study, we showed that d-psicose suppresses increase in plasma glucose and reduces body fat accumulation in rats. Based on acute toxicity testing in rats, d-psicose is classified as an ordinary substance (LD(50) = 16 g/kg). Elucidating the effects of sub-chronic feeding of d-psicose in rats is essential before it can be utilized as a physiologically functional food. In this study, male Wistar rats (3 weeks old) were fed diets containing 3% d-psicose or sucrose for 90 days. The body weight gain and intra-abdominal adipose tissue weight did not differ between the sucrose and the d-psicose groups. The weights of the liver and kidneys were significantly higher in the d-psicose group than in the sucrose group. However, no gross pathological findings were evident at dietary doses of 3% d-psicose or were correlated with hypertrophy of the liver and kidney. In a clinical chemistry analysis, the erythrocyte and leukocyte courts were significantly higher in the d-psicose group, but that was not considered to be toxicologically significant. Therefore, the present study found no adverse effects of d-psicose in rats fed a diet containing 3% d-psicosefor 90 days.

  8. Submaximal exercise VO2 and Qc during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Ertl, A. C.; Bernauer, E. M.

    1996-01-01

    BACKGROUND: Maintaining intermediary metabolism is necessary for the health and well-being of astronauts on long-duration spaceflights. While peak oxygen uptake (VO2) is consistently decreased during prolonged bed rest, submaximal VO2 is either unchanged or decreased. METHODS: Submaximal exercise metabolism (61 +/- 3% peak VO2) was measured during ambulation (AMB day-2) and on bed rest days 4, 11, and 25 in 19 healthy men (32-42 yr) allocated into no exercise (NOE, N = 5) control, and isotonic exercise (ITE, N = 7) and isokinetic exercise (IKE, N = 7) training groups. Exercise training was conducted supine for two 30-min periods per day for 6 d per week: ITE training was intermittent at 60-90% peak VO2; IKE training was 10 sets of 5 repetitions of peak knee flexion-extension force at a velocity of 100 degrees s-1. Cardiac output was measured with the indirect Fick CO2 method, and plasma volume with Evans blue dye dilution. RESULTS: Supine submaximal exercise VO2 decreased significantly (*p < 0.05) by 10.3%* with ITE and by 7.3%* with IKE; similar to the submaximal cardiac output decrease of 14.5%* (ITE) and 20.3%* (IKE), but different from change in peak VO2 (+1.4% with ITE and -10.2%* with IKE) and decrease in plasma volume of -3.7% (ITE) and -18.0%* (IKE). Reduction of submaximal VO2 during bed rest correlated 0.79 (p < 0.01) with submaximal Qc, but was not related to change in peak VO2 or plasma volume. CONCLUSION: Reduction in submaximal oxygen uptake during prolonged bed rest is related to decrease in exercise but not resting cardiac output; perturbations in active skeletal muscle metabolism may be involved.

  9. Surviving Bed Rest

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... to think about catching up on correspondence or reading your favorite author's latest novel. Try these time ...

  10. Program operational summary: Operational 90 day manned test of a regenerative life support system

    NASA Technical Reports Server (NTRS)

    Jackson, J. K.; Wamsley, J. R.; Bonura, M. S.; Seeman, J. S.

    1972-01-01

    An operational 90-day manned test of a regenerative life support system was successfully completed. This test was performed with a crew of four carefully selected and trained men in a space station simulator (SSS) which had a two gas atmosphere maintained at a total pressure of 68.9, 10 psia, and composed of oxygen at a partial pressure of 3.05 psia with nitrogen as the diluent. The test was planned to provide data on regenerative life support subsystems and on integrated system operations in a closed ecology, similar to that of a space station. All crew equipment and expendables were stored onboard at the start of the mission to eliminate the need for pass-in operations. The significant accomplishments of the test, some of the pertinent test results, some of the problem areas, and conclusions are presented.

  11. Ultrastructural response of rat lung to 90 days' exposure to oxygen at 450 mm Hg

    NASA Technical Reports Server (NTRS)

    Harrison, G. A.

    1974-01-01

    Young Sprague-Dawley rats were exposed to 100% oxygen at 450 mm Hg in constant environment capsules for 90 days. Lung tissue examined by electron microscopy revealed a number of changes, many similar to those observed after exposure to oxygen at 760 mm Hg for shorter periods of time. Alterations in vesicle size and number and in mitochondrial matrix and cristae appear in both the endothelial and epithelial cells. Blebbing and rarefication of cytoplasm occur in both cell layers of the alveolo-capillary wall. Also seen are fluid in the basement membrane, platelets in the capillaries, and alveolar fluid and debris. All of these alterations occur at 1 atm exposure. However, after exposure to 450 mm Hg the changes are not as widespread nor as destructive as they are at the higher pressure.

  12. Training plan for the 1164 {lt}90-day non-radioactive hazardous waste storage building

    SciTech Connect

    Demarest, J.L., Westinghouse Hanford

    1996-07-01

    In accordance with Washington Administrative Code (WAC), Chapter 173- 303, `Dangerous Waste Regulations,` a written training plan is required for a {lt}90-day accumulation area. WAC 173-303-200, `Accumulating Dangerous Waste On-site,` requires compliance with WAC- 173-303-330, Personnel Training. This training plan complies with WAC 173-303-330. This training plan, including the names of personnel in Table 1, may be given to a regulatory agency inspector upon request provided that this plan is cleared for public release. Training records associated with personnel identified in this plan are not be given to an outside regulatory agency inspector unless prior approval by the specific individual is obtained. Training records requests by regulatory agency inspectors without the individual`s approval are to be processed via a Freedom of Information Act request through the U.S. Department of Energy, Richland Operations Office.

  13. A 90-Day Subchronic Toxicity Study of Submerged Mycelial Culture of Cordyceps cicadae (Ascomycetes) in Rats.

    PubMed

    Chen, Yen-Lien; Yeh, Shu-Hsing; Lin, Ting-Wei; Chen, Chin-Chu; Chen, Chin-Shuh; Kuo, Chia-Feng

    2015-01-01

    Cordyceps cicadae is a parasitic fungus that hibernates inside a host (Cicada flammata Dist.) and then grows its fruiting body on the surface of the insect. The complete insect/fungus combination of C. cicadae has been widely applied in Chinese traditional medicine. Recent studies have demonstrated that the medicinal benefits of cultured mycelia are as effective as those found in the wild. However, toxicological information regarding the chronic consumption of C. cicadae mycelia culture is not available. This study was conducted to evaluate the possible toxicity arising from repeated exposure to freeze-dried submerged mycelial culture of C. cicadae for 90 days. A total of eighty 8-week-old Sprague-Dawley rats were divided into 4 groups (10 males and 10 females in each group). C. cicadae was administered daily to animals by gavage at doses of 0, 500, 1000, and 2000 mg/kg body weight for 90 days. No animal deaths occurred and no treatment-related clinical signs were observed during the study period. No statistical differences in body weight gain, relative organ weight, hematology, serum chemistry, and urinalysis were observed. Gross necropsy and histopathological findings indicated that there was no treatment-related abnormality. Based on the results, the no observed adverse effect level of C. cicadae whole broth is determined to be > 2000 mg/kg for male and female Sprague-Dawley rats. The results of this study provides support for the use of C. cicadae fermentation product as a safe agent in functional food. PMID:26559863

  14. Co-morbidities and 90-day outcomes in hospitalized COPD exacerbations.

    PubMed

    Roberts, Christopher M; Stone, Robert A; Lowe, Derek; Pursey, Nancy A; Buckingham, Rhona J

    2011-10-01

    COPD exacerbations resulting in hospitalization are accompanied by high mortality and morbidity. The contribution of specific co-morbidities to acute outcomes is not known in detail: existing studies have used either administrative data or small clinical cohorts and have provided conflicting results. Identification of co-existent diseases that affect outcomes provides opportunities to address these conditions proactively and improve overall COPD care. Cases were identified prospectively on admission then underwent retrospective case note audit to collect data including co-morbidities on up to 60 unselected consecutive acute COPD admissions between March and May in each hospital participating in the 2008 UK National COPD audit. Outcomes recorded were death in hospital, length of stay, and death and readmission at 90 days after index admission. 232 hospitals collected data on 9716 patients, mean age 73, 50% male, mean FEV1 42% predicted. Prevalence of co-morbidities were associated with increased age but better FEV1 and ex-smoker status and with worse outcomes for all four measures. Hospital mortality risk was increased with cor pulmonale, left ventricular failure, neurological conditions and non-respiratory malignancies whilst 90 day death was also increased by lung cancer and arrhythmias. Ischaemic and other heart diseases were important factors in readmission. This study demonstrates that co-morbidities adversely affect a range of short-term patient outcomes related to acute admission to hospital with exacerbations of COPD. Recognition of relevant accompanying diseases at admission provides an opportunity for specific interventions that may improve short-term prognosis. PMID:21864116

  15. Bioregenerative Life Support Experiment for 90-days in a Closed Integrative Experimental Facility LUNAR PALACE 1

    NASA Astrophysics Data System (ADS)

    Liu, Hong

    A 90-day bioregenerative life support experiment with three-member crew was carried out in the closed integrative experimental facility, LUNAR PALACE 1 regenerating basic living necessities and disposing wastes to provide life support for crew. It was composed of higher plant module, animal module, and waste treatment module. The higher plant module included wheat, chufa, pea, carrot and green leafy vegetables, with aim to satisfy requirement of 60% plant food and 100% O2 and water for crew. The yellow mealworm was selected as animal module to provide partial animal protein for crew, and reared on plant inedible biomass. The higher plant and yellow mealworm were both cultivated and harvested in the conveyor-type manner. The partial plant inedible biomass and human feces were mixed and co- fermented in the waste treatment module for preparation of soil-like substrate by bioconversion, maintaining gas balance and increasing closure degree. Meanwhile, in the waste treatment module, the water and partial nitrogen from human urine were recovered by physical-chemical means. Circulation of O2 and water as well as food supply from crops cultivated in the LUNAR PALACE 1 were investigated and calculated, and simultaneously gas exchange, mass flow among different components and system closure degree were also analyzed, respectively. Furthermore, the system robustness with respect to internal variation was tested and evaluated by sensitivity analysis of the aggregative index consisting of key performance indicators like crop yield, gaseous equilibrium concentration, microbial community composition, biogenic elements dynamics, etc., and comprehensively evaluating the operating state, to number change of crew from 2 to 4 during the 90-day closed experiment period.

  16. A 90 day chronic toxicity study of Nigerian herbal preparation DAS-77 in rats

    PubMed Central

    2012-01-01

    Background The herbal preparation DAS-77, used for the treatment of various ailments in Nigeria, contains the milled bark of Mangifera indica L. and root of Carica papaya L. Toxicological assessment of the preparation was carried out in this study. Methods In the acute toxicity study, DAS-77 was administered to mice p.o. up to 20 g/kg in divided doses and i.p. at 250–3000 mg/kg. Mortality within 24 h was recorded. In the chronic toxicity study, rats were treated p.o. for 90 days at doses of 80, 400 (therapeutic dose, TD) and 2000 mg/kg. By 90 days, animals were sacrificed and blood samples collected for hematological and biochemical analysis. Organs were harvested for weight determination, antioxidants and histopathological assessments. Results DAS-77 did not produce any lethality administered p.o. up to 20 g/kg in divided doses but the i.p. LD50 was 1122.0 mg/kg. At TD, DAS-77 produced significant (p < 0.05) reductions in body weight, food intake and K+, and increases in ovary weight, neutrophils and HDL, which were reversible. Histopathological presentations were generally normal. Effects at the other doses were comparable to those at TD except for reversible increases in antioxidants in the liver, kidney and testes, and sperm abnormality, and reductions in liver enzymes, sperm motility and count. Conclusions Findings in this study revealed that DAS-77 is relatively safe with the potential for enhancing in vivo antioxidant activity. However, possibly reversible side-effects include electrolyte imbalance and sterility in males. PMID:22892317

  17. Leg muscle volume during 30-day 6-degree head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Lee, P. L.; Ellis, S.; Selzer, R. H.; Ortendahl, D. A.

    1994-01-01

    Magnetic resonance imaging (MRI) was used to compare the effect of two modes of lower-extremity exercise training on the mass (volume) of posterior leg group (PLG) muscles (soleus, flexor hallucis longus, tibialis posterior, lateral and medial gastrocnemius, and flexor digitorum longus) on 19 men (ages 32-42 years) subjected to intense dynamic-isotonic (ITE, cycle ergometer, number of subjects (N) = 7), isokinetic (IKE, torque egrometer, N = 7), and no exercise (NOE, N = 5) training for 60 min/day during head-down bed rest (HDBR). Total volume of the PLG muscles decreased (p less than 0.05) similarly: ITE = 4.3 +/- SE 1.6%, IKE = 7.7 +/- 1.6%, and NOE = 6.3 +/- 0.8%; combined volume (N = 19) loss was 6.1 +/- 0.9%. Ranges of volume changes were 2.6% to -9.0% (ITE), -2.1% to -14.9% (IKE), and -3.4% to -8/1% (NOE). Correlation coefficients (r) of muscle volume versus thickness measured with ultrasonography were: ITE r + 0.79 (p less than 0.05), IKE r = 0.27 (not significant (NS)), and NOE r = 0.63 (NS). Leg-muscle volume and thickness were highly correlated (r = 0.79) when plasma volume was maintained during HDBR with ITE. Thus, neither intensive lower extremity ITE nor IKE training influence the normal non-exercised posterior leg muscle atrophy during HDBR. The relationship of muscle volume and thickness may depend on the mode of exercise training associated with the maintenance of plasma volume.

  18. Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest.

    PubMed

    Schneider, Suzanne M; Lee, Stuart M C; Feiveson, Alan H; Watenpaugh, Donald E; Macias, Brandon R; Hargens, Alan R

    2016-08-01

    Leg muscle mass and strength are decreased during reduced activity and non-weight-bearing conditions such as bed rest (BR) and spaceflight. Supine treadmill exercise within lower body negative pressure (LBNPEX) provides full-body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40-min interval exercise protocol performed against LBNPEX 6 days week(-1) would attenuate losses in leg lean mass (LLM), strength, and endurance during 6° head-down tilt BR, with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non-exercise control (CON) and the other twin as the exercise subject (EX). Before and after BR, LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre- to post-BR in the male CON subjects (P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre- to post-BR changes were significant in the female subjects, either CON or EX, likely due to their lower pre-BR values. Importantly, the LBNPEX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit. PMID:27495299

  19. Gender differences in endocrine responses to posture and 7 days of -6 degrees head-down bed rest

    NASA Technical Reports Server (NTRS)

    Vernikos, J.; Dallman, M. F.; Keil, L. C.; O'Hara, D.; Convertino, V. A.

    1993-01-01

    Endocrine regulation of fluids and electrolytes during 7 days of -6 degrees head-down bed rest (HDBR) was compared in male (n = 8) and, for the first time, female (n = 8) volunteers. The subjects' responses to quiet standing for 2 h before and after HDBR were also tested. In both sexes, diuresis and natriuresis were evident during the first 2-3 days of HDBR, resulting in a marked increase in the urinary Na(+)-to-K+ ratio and significant Na+ retention on re-ambulation. After the 1st day of HDBR, plasma renin activity (PRA) was increased relative to aldosterone (Aldo), plasma volume was decreased, and the renal response to Aldo appeared to be appropriate. Circulating levels of arginine vasopressin, cortisol, and ACTH were unchanged during HDBR. Plasma testosterone decreased slightly on day 2 of HDBR in males. The ratio of early morning ACTH to cortisol was lower in females than in males because ACTH was lower in females. Urinary cortisol increased and remained elevated throughout the HDBR in males only. There were no gender differences in the responses to 7 days of HDBR, except those in the pituitary-adrenal system; those differences appeared unrelated to the postural change. The provocative cardiovascular test of quiet standing before and after HDBR revealed both sex differences and effects of HDBR. There were significant sex differences in cardiovascular responses to standing before and after HDBR. Females had greater PRA and Aldo responses to standing before HDBR and larger Aldo responses to standing after HDBR than males.(ABSTRACT TRUNCATED AT 250 WORDS).

  20. Gender differences in endocrine responses to posture and 7 days of -6 degrees head-down bed rest.

    PubMed

    Vernikos, J; Dallman, M F; Keil, L C; O'Hara, D; Convertino, V A

    1993-07-01

    Endocrine regulation of fluids and electrolytes during 7 days of -6 degrees head-down bed rest (HDBR) was compared in male (n = 8) and, for the first time, female (n = 8) volunteers. The subjects' responses to quiet standing for 2 h before and after HDBR were also tested. In both sexes, diuresis and natriuresis were evident during the first 2-3 days of HDBR, resulting in a marked increase in the urinary Na(+)-to-K+ ratio and significant Na+ retention on re-ambulation. After the 1st day of HDBR, plasma renin activity (PRA) was increased relative to aldosterone (Aldo), plasma volume was decreased, and the renal response to Aldo appeared to be appropriate. Circulating levels of arginine vasopressin, cortisol, and ACTH were unchanged during HDBR. Plasma testosterone decreased slightly on day 2 of HDBR in males. The ratio of early morning ACTH to cortisol was lower in females than in males because ACTH was lower in females. Urinary cortisol increased and remained elevated throughout the HDBR in males only. There were no gender differences in the responses to 7 days of HDBR, except those in the pituitary-adrenal system; those differences appeared unrelated to the postural change. The provocative cardiovascular test of quiet standing before and after HDBR revealed both sex differences and effects of HDBR. There were significant sex differences in cardiovascular responses to standing before and after HDBR. Females had greater PRA and Aldo responses to standing before HDBR and larger Aldo responses to standing after HDBR than males.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8338147

  1. LBNP exercise protects aerobic capacity and sprint speed of female twins during 30 days of bed rest.

    PubMed

    Lee, Stuart M C; Schneider, Suzanne M; Boda, Wanda L; Watenpaugh, Donald E; Macias, Brandon R; Meyer, R Scott; Hargens, Alan R

    2009-03-01

    We have shown previously that treadmill exercise within lower body negative pressure (LBNPex) maintains upright exercise capacity (peak oxygen consumption, Vo(2peak)) in men after 5, 15, and 30 days of bed rest (BR). We hypothesized that LBNPex protects treadmill Vo(2peak) and sprint speed in women during a 30-day BR. Seven sets of female monozygous twins volunteered to participate. Within each twin set, one was randomly assigned to a control group (Con) and performed no countermeasures, and the other was assigned to an exercise group (Ex) and performed a 40-min interval (40-80% pre-BR Vo(2peak)) LBNPex (51 +/- 5 mmHg) protocol, plus 5 min of static LBNP, 6 days per week. Before and immediately after BR, subjects completed a 30.5-m sprint test and an upright graded treadmill test to volitional fatigue. These results in women were compared with previously reported reductions in Vo(2peak) and sprint speed in male twins after BR. In women, sprint speed (-8 +/- 2%) and Vo(2peak) (-6 +/- 2%) were not different after BR in the Ex group. In contrast, both sprint speed (-24 +/- 5%) and Vo(2peak) (-16 +/- 3%) were significantly less after BR in the Con group. The effect of BR on sprint speed and Vo(2peak) after BR was not different between women and men. We conclude that treadmill exercise within LBNP protects against BR-induced reductions in Vo(2peak) and sprint speed in women and should prove effective during long-duration spaceflight.

  2. Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest.

    PubMed

    Schneider, Suzanne M; Lee, Stuart M C; Feiveson, Alan H; Watenpaugh, Donald E; Macias, Brandon R; Hargens, Alan R

    2016-08-01

    Leg muscle mass and strength are decreased during reduced activity and non-weight-bearing conditions such as bed rest (BR) and spaceflight. Supine treadmill exercise within lower body negative pressure (LBNPEX) provides full-body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40-min interval exercise protocol performed against LBNPEX 6 days week(-1) would attenuate losses in leg lean mass (LLM), strength, and endurance during 6° head-down tilt BR, with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non-exercise control (CON) and the other twin as the exercise subject (EX). Before and after BR, LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre- to post-BR in the male CON subjects (P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre- to post-BR changes were significant in the female subjects, either CON or EX, likely due to their lower pre-BR values. Importantly, the LBNPEX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit.

  3. The Effects of Long Duration Head Down Tilt Bed Rest on Neurocognitive Performance: The Effects of Exercise Interventions

    NASA Technical Reports Server (NTRS)

    Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Erdeniz. B.; Kofman, I. S.; DeDios, Y. E.; Szecsy, D. L.; Riascos-Castaneda, R. F.; Wood, S. J.; Bloomberg, J. J.

    2014-01-01

    We are conducting ongoing experiments in which we are performing structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations following a six month International Space Station mission and following 70 days exposure to a spaceflight analog, head down tilt bedrest. Our central hypothesis is that measures of brain structure, function, and network integrity will change from pre to post intervention (spaceflight, bedrest). Moreover, we predict that these changes will correlate with indices of cognitive, sensory, and motor function in a neuroanatomically selective fashion. Our interdisciplinary approach utilizes cutting edge neuroimaging techniques and a broad ranging battery of sensory, motor, and cognitive assessments that will be conducted pre flight, during flight, and post flight to investigate potential neuroplastic and maladaptive brain changes in crewmembers following long-duration spaceflight. Success in this endeavor would 1) result in identification of the underlying neural mechanisms and operational risks of spaceflight-induced changes in behavior, and 2) identify whether a return to normative behavioral function following re-adaptation to Earth's gravitational environment is associated with a restitution of brain structure and function or instead is supported by substitution with compensatory brain processes. Our ongoing bed rest participants are also engaging in exercise studies directed by Dr. Lori Ploutz Snyder. In this presentation, I will briefly highlight the existing literature linking exercise and fitness to brain and behavioral functions. I will also overview the metrics from my study that could be investigated in relation to the exercise and control subgroups.

  4. Effects of 30-Day Head-Down Bed Rest on Ocular Structures and Visual Function in a Healthy Subject

    PubMed Central

    Taibbi, Giovanni; Kaplowitz, Kevin; Cromwell, Ronita L.; Godley, Bernard F.; Zanello, Susana B.; Vizzeri, Gianmarco

    2013-01-01

    Introduction We report ocular changes occurring in a healthy human subject enrolled in a bed rest (BR) study designed to replicate the effects of a low-gravity environment. Case report A 25-year-old Caucasian male spent 30 consecutive days in a 6° head-down-tilt position at the NASA Flight Analogs Research Unit. Comprehensive ophthalmologic exams, optic disc stereo-photography, Standard Automated Perimetry (SAP) and optic disc Spectralis OCT scans were performed at baseline, immediately post-BR (BR+0) and 6 months post-BR. Main outcome measures: changes in best-corrected visual acuity, intraocular pressure (IOP), cycloplegic refraction, SAP and Spectralis OCT measures. At BR+0 IOP was 11 and 10 mmHg in the right (OD) and left eye (OS), respectively (a bilateral 4 mmHg decrease compared to baseline); SAP documented a possible bilateral symmetrical inferior scotoma; Spectralis OCT showed an average 19.4 μm (+5.2%) increase in peripapillary retinal thickness, and an average 0.03 mm3 (+5.0%) increase in peripapillary retinal volume bilaterally. However, there were no clinically detectable signs of optic disc edema. 6 months post-BR, IOP was 13 and 14 mmHg in OD and OS, respectively, and the scotoma had resolved. Spectralis OCT measurements matched the ones recorded at baseline. Discussion In this subject, a reduction in IOP associated with subtle structural and functional changes compared to baseline were documented after prolonged head-down BR. These changes may be related to cephalad fluid shifts in response to tilt. Further studies should clarify whether decreased translaminar pressure (i.e., the difference between IOP and intracranial pressure) may be responsible for these findings. PMID:23447853

  5. Knee-joint proprioception during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily leg proprioceptive training, would influence leg proprioceptive tracking responses during bed rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a no-exercise (NOE) training control group (n = 5), and isotonic exercise (ITE, n = 7) and isokinetic exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min periods.d-1, 5 d.week-1. Only the IKE group performed proprioceptive training using a new isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pre-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p < 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9* +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.5%, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both isotonic exercise training (without additional proprioceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  6. Knee-Joint Proprioception During 30-Day 6 deg Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Bernauer, E. M.; Walby, W. F.; Ertl, A. C.; Dempster, P. T.; Bond, M.; Greenleaf, J. E.

    1994-01-01

    To determine if daily isotonic exercise or isokinetic exercise training coupled with daily log proprioceptive training, would influence log proprioceptive tracking responses during Bed Rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a NO-Exercise (NOE) training control group (n = 5), and IsoTanic Exercise (ITE, n = 7) and IsoKinetic Exercise (IKE, n = 7) training groups. Exercise training was conducted during BR for two 30-min period / d, 5 d /week. Only the IKE group performed proprioceptive training using a now isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pro-BR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p less than 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9 +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.50, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both lsotonic exercise training (without additional propriaceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR.

  7. Effects of leg strength and bicycle ergometry exercise on cardiovascular deconditioning after 30-day head-down bed rest

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Liu, Yusheng; Sun, Hongyi; Zhao, Dongming; Wang, Yue; Wu, Ping; Ni, Chengzhi

    2010-10-01

    The purpose of this study is to determine if the intermittent leg muscular strength exercise and bicycle ergometry exercise could attenuate cardiovascular deconditioning induced by prolonged -6° head-down bed rest (HDBR). Fifteen male subjects were randomly allocated into group A ( n=5, 30 days HDBR without exercise), group B ( n=5, 30 days HDBR with leg muscular strength exercise) and group C ( n=5, 30 days HDBR with bicycle ergometry exercise). The orthostatic tolerance (OT) was determined by +75°/20 min head-up tilt (HUT) test and the submaximal exercise capacity was determined by bicycle ergometry before and after HDBR. The results were as follows: (1) Compared with that before HDBR, OT time decreased dramatically by 57.6% ( p<0.001) after HDBR in group A, while it decreased by 36.4% ( p=0.084) in group B and by 34.7% ( p=0.062) in group C. (2) Compared with that before HDBR, the submaximal exercise time decreased significantly by 17.7% ( p<0.05) and 21.1% ( p<0.05) in groups A and B, respectively, after HDBR. However, it had no change (+1.3%, p>0.77) in group C. (3) compared with that before HDBR, the changes of heart rate (HR) and blood pressure were slightly improved in group B and C, while deteriorated in group A during orthostatic test and exercise test after HDBR. The results indicate that leg muscular strength exercise and bicycle ergometry exercise could partially attenuate the cardiovascular deconditioning induced by 30 d HDBR, and the latter exercise training could fully provide the protection for the loss of exercise capacity.

  8. Fourteen days of bed rest induces a decline in satellite cell content and robust atrophy of skeletal muscle fibers in middle-aged adults.

    PubMed

    Arentson-Lantz, Emily J; English, Kirk L; Paddon-Jones, Douglas; Fry, Christopher S

    2016-04-15

    Bed rest, a ground-based spaceflight analog, induces robust atrophy of skeletal muscle, an effect that is exacerbated with increasing age. We examined the effect of 14 days of bed rest on skeletal muscle satellite cell content and fiber type atrophy in middle-aged adults, an understudied age demographic with few overt signs of muscle aging that is representative of astronauts who perform long-duration spaceflight. Muscle biopsies were obtained from the vastus lateralis of healthy middle-aged adults [n= 7 (4 male, 3 female); age: 51 ± 1 yr] before (Pre-BR) and after (Post-BR) 14 days of bed rest. Immunohistochemical analyses were used to quantify myosin heavy chain (MyHC) isoform expression, cross-sectional area (CSA), satellite cell and myonuclear content, and capillary density. Peak oxygen consumption, knee extensor strength, and body composition were also measured Pre-BR and Post-BR. Post-BR MyHC type 2a fiber percentage was reduced, and mean CSA decreased in all fiber types (-24 ± 5%;P< 0.05). Satellite cell content was also reduced Post-BR (-39 ± 9%;P< 0.05), and the change in satellite cell content was significantly correlated with the change in mean fiber CSA (r(2)= 0.60;P< 0.05). A decline in capillary density was observed Post-BR (-23 ± 6%;P< 0.05), and Post-BR capillary content was significantly associated with Post-BR peak aerobic capacity (r(2)= 0.59;P< 0.05). A subtle decline in myonuclear content occurred during bed rest (-5 ± 1%;P< 0.05). The rapid maladaptation of skeletal muscle to 14 days of mechanical unloading in middle-aged adults emphasizes the need for robust countermeasures to preserve muscle function in astronauts. PMID:26796754

  9. A combination of whey protein and potassium bicarbonate supplements during head-down-tilt bed rest: Presentation of a multidisciplinary randomized controlled trial (MEP study)

    NASA Astrophysics Data System (ADS)

    Buehlmeier, Judith; Mulder, Edwin; Noppe, Alexandra; Frings-Meuthen, Petra; Angerer, Oliver; Rudwill, Floriane; Biolo, Gianni; Smith, Scott M.; Blanc, Stéphane; Heer, Martina

    2014-02-01

    Inactivity, as it appears during space flight and in bed rest, induces reduction of lean body and bone mass, glucose intolerance, and weakening of the cardiovascular system. Increased protein intake, whey protein in particular, has been proposed to counteract some of these effects, but has also been associated with negative effects on bone, likely caused by a correspondingly high ratio of acid to alkali precursors in the diet.

  10. WISE-2005: tibial and gastrocnemius vein and calf tissue response to LBNP after a 60-day bed rest with and without countermeasures.

    PubMed

    Arbeille, P; Kerbeci, P; Mattar, L; Shoemaker, J K; Hughson, R L

    2008-04-01

    The objective of this study was to quantify by echography the changes in the intramuscular [gastrocnemius (Gast)] and nonintramuscular [posterior tibial (Tib)] calf veins cross-sectional area (CSA) and the superficial tissue thickness (STth) in response to lower body negative pressure (LBNP) after 60-day head-down bed rest (HDBR). Twenty-four healthy women (25-40 yr) were divided into three groups: control (Con), treadmill-LBNP and flywheel (Ex-Lb), nutrition (Nut; protein supplement). All underwent a LBNP (0 and -45 mmHg) before and on day 55 of HDBR. Subjects were identified as finisher (F) or nonfinisher (NF) of a 10-min tilt test after 60 days of HDBR. There were no differences in resting CSA of the Tib and Gast veins on HDBR day 55 compared with pre-HDBR for the Ex-Lb, Con and Nut, or the F groups; however, for NF both the Tib and Gast vein CSA at rest were significantly smaller after HDBR. At -45 mmHg LBNP, Tib and Gast CSAs were not significantly different from before HDBR in all groups (Ex-Lb, Con, Nut, F, NF). However, percent change in CSA of both veins from rest to -45 mmHg LBNP was significantly greater in the Con and Nut groups compared with Ex-Lb, and also NF compared with F. Similarly, the percent increase in STth on going from rest to -45 mmHg was higher after HDBR in the Con and Nut groups compared with Ex-Lb, as well as NF compared with F. These results showed that the Ex-Lb countermeasure minimized the bed rest effect on leg vein capacitance (CSA percent change) and STth increase during LBNP, whereas Nut had no effect and that higher leg vein and superficial tissue capacitance were associated with reduced orthostatic tolerance. PMID:18202168

  11. A 90-Day Oral Toxicological Evaluation of the Methylurate Purine Alkaloid Theacrine

    PubMed Central

    Hirka, Gábor; Glávits, Róbert; Palmer, Philip A.; Endres, John R.; Pasics Szakonyiné, Ilona

    2016-01-01

    A 90-day repeated-dose oral toxicological evaluation was conducted according to GLP and OECD guidelines on the methylurate purine alkaloid theacrine, which is found naturally in certain plants. Four groups of Hsd.Brl.Han Wistar rats (ten/sex/group) were administered theacrine by gavage doses of 0 (vehicle only), 180, 300, and 375 mg/kg bw/day. Two females and one male in the 300 and 375 mg/kg bw/day groups, respectively, died during the study. Histological examination revealed centrilobular hepatocellular necrosis as the probable cause of death. In 375 mg/kg bw/day males, slight reductions in body weight development, food consumption, and feed efficiency, decreased weight of the testes and epididymides and decreased intensity of spermatogenesis in the testes, lack or decreased amount of mature spermatozoa in the epididymides, and decreased amount of prostatic secretions were detected at the end of the three months. At 300 mg/kg bw/day, slight decreases in the weights of the testes and epididymides, along with decreased intensity of spermatogenesis in the testes, and lack or decreased amount of mature spermatozoa in the epididymides were detected in male animals. The NOAEL was considered to be 180 mg/kg bw/day, as at this dose there were no toxicologically relevant treatment-related findings in male or female animals. PMID:27635133

  12. A 90-day subchronic toxicity study of neem oil, a Azadirachta indica oil, in mice.

    PubMed

    Wang, C; Cao, M; Shi, D-X; Yin, Z-Q; Jia, R-Y; Wang, K-Y; Geng, Y; Wang, Y; Yao, X-P; Yang, Z-R; Zhao, J

    2013-09-01

    To determine the no-observed-adverse-effect level (NOAEL) of exposure and target organs of neem oil for establishing safety criteria for human exposure, the subchronic toxicity study with neem oil in mice was evaluated. The mice (10 per sex for each dose) was orally administered with neem oil with the doses of 0 (to serve as a control), 177, 533 and 1600 mg/kg/day for 90 days. After the treatment period, observation of reversibility or persistence of any toxic effects, mice were continuously fed without treatment for the following 30 days. During the two test periods, the serum biochemistry, organ weight and histopathology were examined. The results showed that the serum biochemistry and organ coefficient in experimental groups had no statistical difference compared with those of the control group. At the 90th day, the histopathological examinations showed that the 1600 mg/kg/day dose of neem oil had varying degrees of damage on each organ except heart, uterus and ovarian. After 30-day recovery, the degree of lesions to the tissues was lessened or even restored. The NOAEL of neem oil was 177 mg/kg/day for mice and the target organs of neem oil were determined to be testicle, liver and kidneys.

  13. A 90-Day Oral Toxicological Evaluation of the Methylurate Purine Alkaloid Theacrine.

    PubMed

    Clewell, Amy; Hirka, Gábor; Glávits, Róbert; Palmer, Philip A; Endres, John R; Murbach, Timothy S; Marx, Tennille; Pasics Szakonyiné, Ilona

    2016-01-01

    A 90-day repeated-dose oral toxicological evaluation was conducted according to GLP and OECD guidelines on the methylurate purine alkaloid theacrine, which is found naturally in certain plants. Four groups of Hsd.Brl.Han Wistar rats (ten/sex/group) were administered theacrine by gavage doses of 0 (vehicle only), 180, 300, and 375 mg/kg bw/day. Two females and one male in the 300 and 375 mg/kg bw/day groups, respectively, died during the study. Histological examination revealed centrilobular hepatocellular necrosis as the probable cause of death. In 375 mg/kg bw/day males, slight reductions in body weight development, food consumption, and feed efficiency, decreased weight of the testes and epididymides and decreased intensity of spermatogenesis in the testes, lack or decreased amount of mature spermatozoa in the epididymides, and decreased amount of prostatic secretions were detected at the end of the three months. At 300 mg/kg bw/day, slight decreases in the weights of the testes and epididymides, along with decreased intensity of spermatogenesis in the testes, and lack or decreased amount of mature spermatozoa in the epididymides were detected in male animals. The NOAEL was considered to be 180 mg/kg bw/day, as at this dose there were no toxicologically relevant treatment-related findings in male or female animals. PMID:27635133

  14. 90-day dermal toxicity study and neurotoxicity evaluation of nitromusks in the albino rat.

    PubMed

    Ford, R A; Api, A M; Newberne, P M

    1990-01-01

    Musk ketone, musk xylene, musk tibetene and moskene, synthetic musks used in fragrances, were applied dermally to rats in daily doses of 240 (musk ketone and musk xylene only), 75, 24 or 7.5 mg/kg body weight for 90 days. The chemically related musk ambrette, a known neurotoxin in rats, was used as a positive control. While musk ambrette was clearly neurotoxic and caused testicular atrophy, as had been previously reported, the other compounds tested caused neither effect. The only effects of application of these materials were some organ weight changes at the higher doses, but these were not associated with histopathological changes in any of the tissues. The no-effect levels were: musk ketone, 75 mg/kg for males and females; musk xylene, 75 mg/kg for males and 24 mg/kg for females; moskene, 24 mg/kg for males and 75 mg/kg (highest dose administered) for females; and musk tibetene, 75 mg/kg (highest dose) for males and females.

  15. Safety assessment of dietary bamboo charcoal powder: a 90-day subchronic oral toxicity and mutagenicity studies.

    PubMed

    Zhenchao, Jia; Yuting, Zhong; Jiuming, Yan; Yedan, Lu; Yang, Song; Jinyao, Chen; Lishi, Zhang

    2015-01-01

    Vegetable carbon has been used as food additive in EU (E153) and China for many years; however, no experimental data have been available on its dietary safety. This study was designed to evaluate the subchronic toxicity and genotoxicity of bamboo charcoal powder (BCP). In the study of subchronic oral toxicity, BCP was administered orally at doses of 2.81, 5.62, and 11.24 g/kg BW for 90 days to SD rats. Additional satellite groups from the control group and high dose group were observed for a 28-day recovery period. At the end of the treatment and recovery periods, animals were sacrificed, and their organs were weighed and blood samples were collected. The toxicological endpoints observed included clinical signs, food consumption, body and organ weights, hematological and biochemical parameters, macroscopic and microscopic examinations. The results showed no significant differences between the BCP treated groups and control group. The genotoxicity of BCP was assessed with the Salmonella typhimurium mutagenicity assay (Ames test) and a combination of comet assay and mammalian erythrocyte micronucleus protocol. The results did not reveal any genotoxicity of BCP. Based on our study, the no-observed-adverse-effect level (NOAEL) for BCP is 11.24 g/kg BW/day.

  16. A 90-day subchronic toxicity study of neem oil, a Azadirachta indica oil, in mice.

    PubMed

    Wang, C; Cao, M; Shi, D-X; Yin, Z-Q; Jia, R-Y; Wang, K-Y; Geng, Y; Wang, Y; Yao, X-P; Yang, Z-R; Zhao, J

    2013-09-01

    To determine the no-observed-adverse-effect level (NOAEL) of exposure and target organs of neem oil for establishing safety criteria for human exposure, the subchronic toxicity study with neem oil in mice was evaluated. The mice (10 per sex for each dose) was orally administered with neem oil with the doses of 0 (to serve as a control), 177, 533 and 1600 mg/kg/day for 90 days. After the treatment period, observation of reversibility or persistence of any toxic effects, mice were continuously fed without treatment for the following 30 days. During the two test periods, the serum biochemistry, organ weight and histopathology were examined. The results showed that the serum biochemistry and organ coefficient in experimental groups had no statistical difference compared with those of the control group. At the 90th day, the histopathological examinations showed that the 1600 mg/kg/day dose of neem oil had varying degrees of damage on each organ except heart, uterus and ovarian. After 30-day recovery, the degree of lesions to the tissues was lessened or even restored. The NOAEL of neem oil was 177 mg/kg/day for mice and the target organs of neem oil were determined to be testicle, liver and kidneys. PMID:23444337

  17. A 90-Day Oral Toxicological Evaluation of the Methylurate Purine Alkaloid Theacrine

    PubMed Central

    Hirka, Gábor; Glávits, Róbert; Palmer, Philip A.; Endres, John R.; Pasics Szakonyiné, Ilona

    2016-01-01

    A 90-day repeated-dose oral toxicological evaluation was conducted according to GLP and OECD guidelines on the methylurate purine alkaloid theacrine, which is found naturally in certain plants. Four groups of Hsd.Brl.Han Wistar rats (ten/sex/group) were administered theacrine by gavage doses of 0 (vehicle only), 180, 300, and 375 mg/kg bw/day. Two females and one male in the 300 and 375 mg/kg bw/day groups, respectively, died during the study. Histological examination revealed centrilobular hepatocellular necrosis as the probable cause of death. In 375 mg/kg bw/day males, slight reductions in body weight development, food consumption, and feed efficiency, decreased weight of the testes and epididymides and decreased intensity of spermatogenesis in the testes, lack or decreased amount of mature spermatozoa in the epididymides, and decreased amount of prostatic secretions were detected at the end of the three months. At 300 mg/kg bw/day, slight decreases in the weights of the testes and epididymides, along with decreased intensity of spermatogenesis in the testes, and lack or decreased amount of mature spermatozoa in the epididymides were detected in male animals. The NOAEL was considered to be 180 mg/kg bw/day, as at this dose there were no toxicologically relevant treatment-related findings in male or female animals.

  18. WISE-2005: LBNP/Treadmill and Resistive Exercise Countermeasures Maintain Aerobic Capacity during a 60-d Bed Rest

    NASA Technical Reports Server (NTRS)

    Schneider, Suzanne M.; Lee, Stuart M. C.; Watenpaugh, Donald E.; Macias, Brandon R.; Hargens, Alan R.

    2006-01-01

    We have previously documented that supine treadmill exercise within lower body negative pressure (LBNPex) performed 6 sessions (raised dot) wk(sup -1) during 15- and 30-day bed rests (BR) maintained upright aerobic capacity (VO2pk). In the present study, ure are evaluating whether aerobic capacity is maintained during a 60-d BR when the LBNPex frequency is reduced to 2-4 sessions (raised dot) wk(sup -1) and resistance exercise (REX) is added 2-3 sessions (raised dot) wk(sup -1). Eight healthy women (32 plus or minus 4 yrs; 56.4 plus or minus 3.6 kg; 164 plus or minus 8 cm; mean plus or minus SD) performed maximal-exertion, graded treadmill tests before and 3 days after a 60-d, 6 deg. head-down tilt BR. (Earliest day the medical monitors would permit a maximal exercise test post-BR). During BR, four subjects performed no exercise (CON), while four other subjects (EX) performed LBNPex and REX on separate days. The LBNPex countermeasure employed an intermittent (40-80% pre-BR VO2pk), 40-min protocol against an LBNP pressure (-49 plus or minus 3 mmHg) applied to provide a footward force equivalent to 1.0-1.2 body weight. REX consisted of maximal concentric and eccentric supine leg press and heel raise exercises using a gravity-independent flywheel ergometer. Comparisons were performed using paired (within-group) or non-paired (between-group) t-tests. Three days post-BR, VO2pk of the CON group was reduced significantly from pre-BR (Pre:37.2 plus or minus 1.2, Post: 29.4 plus or minus 2 ml (raised dot) kg(sup -1) (raised dot) min(sup -1), P less than 0.05), while the VO2pk of the EX group was not significantly reduced (Pre: 39.6 plus or minus 1.9, Post: 38.0 plus or minus 0.6 ml (raised dot) kg(sup -1) (raised dot) min(sup -1)). Peak heart rate, ventilation, rating of perceived exertion, and respiratory exchange ratio were not significantly different between the two groups pre- and post-BR. These preliminary results suggest that the combined LBNPex and REX

  19. Effect of Head-Down Bed Rest and Artificial Gravity Countermeasure on Cardiac Autonomic and Advanced Electrocardiographic Function

    NASA Technical Reports Server (NTRS)

    Schlegel, T. T.; Platts, S.; Stenger, M.; Ribeiro, C.; Natapoff, A.; Howarth, M.; Evans, J.

    2007-01-01

    To study the effects of 21 days of head-down bed rest (HDBR), with versus without an artificial gravity (AG) countermeasure, on cardiac autonomic and advanced electrocardiographic function. Fourteen healthy men participated in the study: seven experienced 21 days of HDBR alone ("HDBR controls") and seven the same degree and duration of HDBR but with approximately 1hr daily short-arm centrifugation as an AG countermeasure ("AG-treated"). Five minute supine high-fidelity 12-lead ECGs were obtained in all subjects: 1) 4 days before HDBR; 2) on the last day of HDBR; and 3) 7 days after HDBR. Besides conventional 12-lead ECG intervals and voltages, all of the following advanced ECG parameters were studied: 1) both stochastic (time and frequency domain) and deterministic heart rate variability (HRV); 2) beat-to-beat QT interval variability (QTV); 3) T-wave morphology, including signal-averaged T-wave residua (TWR) and principal component analysis ratios; 4) other SAECG-related parameters including high frequency QRS ECG and late potentials; and 5) several advanced ECG estimates of left ventricular (LV) mass. The most important results by repeated measures ANOVA were that: 1) Heart rates, Bazett-corrected QTc intervals, TWR, LF/HF power and the alpha 1 of HRV were significantly increased in both groups (i.e., by HDBR), but with no relevant HDBR*group differences; 2) All purely "vagally-mediated" parameters of HRV (e.g., RMSSD, HF power, Poincare SD1, etc.), PR intervals, and also several parameters of LV mass (Cornell and Sokolow-Lyon voltages, spatial ventricular activation times, ventricular gradients) were all significantly decreased in both groups (i.e., by HDBR), but again with no relevant HDBR*group differences); 3) All "generalized" or "vagal plus sympathetic" parameters of stochastic HRV (i.e., SDNN, total power, LF power) were significantly more decreased in the AG-treated group than in the HDBR-only group (i.e., here there was a relevant HDBR*group difference

  20. Effect of 17 days of bed rest on peak isometric force and unloaded shortening velocity of human soleus fibers

    NASA Technical Reports Server (NTRS)

    Widrick, J. J.; Romatowski, J. G.; Bain, J. L.; Trappe, S. W.; Trappe, T. A.; Thompson, J. L.; Costill, D. L.; Riley, D. A.; Fitts, R. H.

    1997-01-01

    The purpose of this study was to examine the effect of prolonged bed rest (BR) on the peak isometric force (P0) and unloaded shortening velocity (V0) of single Ca(2+)-activated muscle fibers. Soleus muscle biopsies were obtained from eight adult males before and after 17 days of 6 degrees head-down BR. Chemically permeabilized single fiber segments were mounted between a force transducer and position motor, activated with saturating levels of Ca2+, and subjected to slack length steps. V0 was determined by plotting the time for force redevelopment vs. the slack step distance. Gel electrophoresis revealed that 96% of the pre- and 87% of the post-BR fibers studied expressed only the slow type I myosin heavy chain isoform. Fibers with diameter > 100 microns made up only 14% of this post-BR type I population compared with 33% of the pre-BR type I population. Consequently, the post-BR type I fibers (n = 147) were, on average, 5% smaller in diameter than the pre-BR type I fibers (n = 218) and produced 13% less absolute P0. BR had no overall effect on P0 per fiber cross-sectional area (P0/CSA), even though half of the subjects displayed a decline of 9-12% in P0/CSA after BR. Type I fiber V0 increased by an average of 34% with BR. Although the ratio of myosin light chain 3 to myosin light chain 2 also rose with BR, there was no correlation between this ratio and V0 for either the pre- or post-BR fibers. In separate fibers obtained from the original biopsies, quantitative electron microscopy revealed a 20-24% decrease in thin filament density, with no change in thick filament density. These results raise the possibility that alterations in the geometric relationships between thin and thick filaments may be at least partially responsible for the elevated V0 of the post-BR type I fibers.

  1. High Intensity Resistive and Rowing Exercise Countermeasures Do Not Prevent Orthostatic Intolerance Following 70 Days of Bed Rest

    NASA Technical Reports Server (NTRS)

    Lee, Stuart M. C.; Stenger, Michael B.; Laurie, Steven S.; Ploutz-Snyder, Lori L.; Platts, Steven H.

    2015-01-01

    More than 60% of US astronauts participating in Mir and early International Space Station missions (greater than 5 months) were unable to complete a 10-min 80 deg head-up tilt test on landing day. This high incidence of post-spaceflight orthostatic intolerance may be related to limitations of the inflight exercise hardware that prevented high intensity training. PURPOSE: This study sought to determine if a countermeasure program that included intense lower-body resistive and rowing exercises designed to prevent cardiovascular and musculoskeletal deconditioning during 70 days of 6 deg head-down tilt bed rest (BR), a spaceflight analog, also would protect against post- BR orthostatic intolerance. METHODS: Sixteen males participated in this study and performed no exercise (Control, n=10) or performed an intense supine exercise protocol with resistive and aerobic components (Exercise, n=6). On 3 days/week, exercise subjects performed lower body resistive exercise and a 30-min continuous bout of rowing (greater than or equal to 75% max heart rate). On 3 other days/week, subjects performed only high-intensity, interval-style rowing. Orthostatic intolerance was assessed using a 15-min 80 deg head-up tilt test performed 2 days (BR-2) before and on the last day of BR (BR70). Plasma volume was measured using a carbon monoxide rebreathing technique on BR-3 and before rising on the first recovery day (BR+0). RESULTS: Following 70 days of BR, tilt tolerance time decreased significantly in both the Control (BR-2: 15.0 +/- 0.0, BR70: 9.9 +/- 4.6 min, mean +/- SD) and Exercise (BR-2: 12.2 +/- 4.7, BR70: 4.9 +/- 1.9 min) subjects, but the decreased tilt tolerance time was not different between groups (Control: -34 +/- 31, Exercise: -56 +/- 16%). Plasma volume also decreased (Control: -0.56 +/- 0.40, Exercise: -0.48 +/- 0.33 L) from pre to post-BR, with no differences between groups (Control: -18 +/- 11%, Exerciser: -15 +/-1 0%). CONCLUSIONS: These findings confirm previous reports

  2. Zinc oxide nanoparticles: a 90-day repeated-dose dermal toxicity study in rats

    PubMed Central

    Ryu, Hwa Jung; Seo, Mu Yeb; Jung, Sung Kyu; Maeng, Eun Ho; Lee, Seung-Young; Jang, Dong-Hyouk; Lee, Taek-Jin; Jo, Ki-Yeon; Kim, Yu-Ri; Cho, Kyu-Bong; Kim, Meyoung-Kon; Lee, Beom Jun; Son, Sang Wook

    2014-01-01

    Zinc oxide (ZnO) works as a long-lasting, broad-spectrum physical sunblock, and can prevent skin cancer, sunburn, and photoaging. Nanosized ZnO particles are used often in sunscreens due to consumer preference over larger sizes, which appear opaque when dermally applied. Although the US Food and Drug Administration approved the use of nanoparticles (NPs) in sunscreens in 1999, there are ongoing safety concerns. The aim of this study was to evaluate the subchronic toxicity of ZnO NPs after dermal application according to the Organization for Economic Cooperation and Development Test Guidelines 411 using Good Laboratory Practice. Sprague Dawley rats were randomly divided into eight (one control, one vehicle control, three experimental, and three recovery) groups. Different concentrations of ZnO NPs were dermally applied to the rats in the experimental groups for 90 days. Clinical observations as well as weight and food consumption were measured and recorded daily. Hematology and biochemistry parameters were determined. Gross pathologic and histopathologic examinations were performed on selected tissues from all animals. Analyses of tissue were undertaken to determine target organ tissue distribution. There was no increased mortality in the experimental group. Although there was dose-dependent irritation at the site of application, there were no abnormal findings related to ZnO NPs in other organs. Increased concentrations of ZnO in the liver, small intestine, large intestine, and feces were thought to result from oral ingestion of ZnO NPs via licking. Penetration of ZnO NPs through the skin seemed to be limited via the dermal route. This study demonstrates that there was no observed adverse effect of ZnO NPs up to 1,000 mg/kg body weight when they are applied dermally. PMID:25565832

  3. Zinc oxide nanoparticles: a 90-day repeated-dose dermal toxicity study in rats.

    PubMed

    Ryu, Hwa Jung; Seo, Mu Yeb; Jung, Sung Kyu; Maeng, Eun Ho; Lee, Seung-Young; Jang, Dong-Hyouk; Lee, Taek-Jin; Jo, Ki-Yeon; Kim, Yu-Ri; Cho, Kyu-Bong; Kim, Meyoung-Kon; Lee, Beom Jun; Son, Sang Wook

    2014-01-01

    Zinc oxide (ZnO) works as a long-lasting, broad-spectrum physical sunblock, and can prevent skin cancer, sunburn, and photoaging. Nanosized ZnO particles are used often in sunscreens due to consumer preference over larger sizes, which appear opaque when dermally applied. Although the US Food and Drug Administration approved the use of nanoparticles (NPs) in sunscreens in 1999, there are ongoing safety concerns. The aim of this study was to evaluate the subchronic toxicity of ZnO NPs after dermal application according to the Organization for Economic Cooperation and Development Test Guidelines 411 using Good Laboratory Practice. Sprague Dawley rats were randomly divided into eight (one control, one vehicle control, three experimental, and three recovery) groups. Different concentrations of ZnO NPs were dermally applied to the rats in the experimental groups for 90 days. Clinical observations as well as weight and food consumption were measured and recorded daily. Hematology and biochemistry parameters were determined. Gross pathologic and histopathologic examinations were performed on selected tissues from all animals. Analyses of tissue were undertaken to determine target organ tissue distribution. There was no increased mortality in the experimental group. Although there was dose-dependent irritation at the site of application, there were no abnormal findings related to ZnO NPs in other organs. Increased concentrations of ZnO in the liver, small intestine, large intestine, and feces were thought to result from oral ingestion of ZnO NPs via licking. Penetration of ZnO NPs through the skin seemed to be limited via the dermal route. This study demonstrates that there was no observed adverse effect of ZnO NPs up to 1,000 mg/kg body weight when they are applied dermally. PMID:25565832

  4. A-90 Day Gavage Safety Assessment of Boswellia serrata in Rats

    PubMed Central

    Singh, Pooja; Chacko, K. Mathai; Aggarwal, M. L.; Bhat, Binu; Khandal, R. K.; Sultana, Sarwat; Kuruvilla, Binu T.

    2012-01-01

    The present study deals with the evaluation and assessment of the safety/toxic potential of Boswellia serrata, a well known Ayurvedic herb used to treat disorders of digestive system, respiratory ailments and bone related diseases. A repeated dose oral (90 days) toxicity study of Boswellia serrata was carried out. For this, 10 rats of each sex were treated with the Boswellia serrata at three different doses i.e. 100, 500 and 1000 mg/kg B. wt. /day. As a control, 10 rats of each sex were treated with corn oil only which was the vehicle. Two groups consisting of five male and five female rats were kept as control recovery and high dose recovery group which were treated with the vehicle (corn oil) and the Boswellia serrata at the dose of 1000 mg/kg B. wt. Animals of control recovery and high dose recovery groups were further observed for 28 days without any treatment. From this study, it was found that the rats treated with high dose of the Boswellia serrata gained their body weight with much less rate than that of the control group. However, during the recovery period, the loss in body weight gain as observed during the study period exhibits a reversible effect on the metabolic activity and recovered. The results also indicate that Boswellia serrata is relatively safe in rat up to the dose of 500 mg/kg B.wt. as no adverse impact on health factors was observed. Thus, the No observed adverse effect level is 500 mg/kg B. wt. PMID:23293466

  5. Petroleum prices and profits in the 90 days following the invasion of Kuwait

    SciTech Connect

    Not Available

    1990-11-01

    For the third in the past 20 years the world has experienced an interruption in the flow of oil from the Persian Gulf. The Iraqi invasion of Kuwait on August 2, 1990, and shut down of Kuwait oil production capacity followed by the United Nations boycott of Iraqi oil removed 8 percent of the world's oil supply. The result was a sharp increase in the process of crude oil and petroleum products. These events raised numerous questions about the performance of energy markets and energy firms. This report supplies a first answer for some of those questions. At the time this report was prepared the invasion has been in effect for 90 days. Not all the data is available to fully answer every question. Some issues can only be completely resolved after more time has passed in which the invasion and its effects have had an opportunity to be fully assimilated. This report was specifically requested by W. Henson Moore, Deputy Secretary of Energy as a way of supplying the American public with what could be said about the current situation. Rumors abound and mixconceptions have proliferated. This report strives to give a proper perspective on some of the more vexing issues which the invasion produced. The Energy Information Administration (EIA) has addressed many questions in this report. By the way of summary these are the 10 most most frequently asked questions and EIA's quick answers. The page references tell the reader where to look in the report for further explanation. These are not the only issues addressed and EIA hopes that readers will be able to satisfy their curiosity about their own questions within the pages of this report.

  6. Prevention of bone mineral changes induced by bed rest: Modification by static compression simulating weight bearing, combined supplementation of oral calcium and phosphate, calcitonin injections, oscillating compression, the oral diophosphonatedisodium etidronate, and lower body negative pressure

    NASA Technical Reports Server (NTRS)

    Schneider, V. S.; Hulley, S. B.; Donaldson, C. L.; Vogel, J. M.; Rosen, S. N.; Hantman, D. A.; Lockwood, D. R.; Seid, D.; Hyatt, K. H.; Jacobson, L. B.

    1974-01-01

    The phenomenon of calcium loss during bed rest was found to be analogous to the loss of bone material which occurs in the hypogravic environment of space flight. Ways of preventing this occurrence are investigated. A group of healthy adult males underwent 24-30 weeks of continuous bed rest. Some of them were given an exercise program designed to resemble normal ambulatory activity; another subgroup was fed supplemental potassium phosphate. The results from a 12-week period of treatment were compared with those untreated bed rest periods. The potassium phosphate supplements prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. The exercise program did not diminish the negative calcium balance. Neither treatment affected the heavy loss of mineral from the calcaneus. Several additional studies are developed to examine the problem further.

  7. Comparative 90-day dietary study of paraffin wax in Fischer-344 and Sprague-Dawley rats.

    PubMed

    Griffis, L C; Twerdok, L E; Francke-Carroll, S; Biles, R W; Schroeder, R E; Bolte, H; Faust, H; Hall, W C; Rojko, J

    2010-01-01

    Highly refined mineral hydrocarbons (MHCs) such as low melting point paraffin wax (LMPW) and low viscosity white oils can cause inflammatory changes in the liver and mesenteric lymph nodes (MLNs) of the Fischer-344 (F-344) rat. In contrast, only minimal MLN changes are seen in the Sprague-Dawley (S-D) rat with no changes in the liver. In this study, the response of female F-344 and S-D rats was compared after 90days dietary treatment with 0%, 0.2% or 2% LMPW. Effects in the F-344 rats were significantly greater than in the S-D rats: increased liver and splenic weights and inflammatory changes (hepatic microgranulomas) in these tissues were observed only in the F-344 rats. Microgranulomas in the MLNs were observed in both strains but the effects were substantially greater in the F-344 rats. Cellular markers of inflammation were examined in a subset of rats from each group using immunohistochemical staining. An increase in staining for CD3 (T-cells), CD8a (suppresser/cytotoxic T-cells) and CD4 (helper T-cells) correlated with an increase in lymphoid cells in the livers of treated F-344 rats. The majority of macrophages in the hepatic microgranulomas of treated F-344 rats were negative for the ED2 marker, indicating a likely origin from non-resident macrophages. Electron microscopy showed Kupffer cell hypertrophy and hyperplasia in treated F-344 rats. However, lysozyme staining (indicating activation of epithelioid macrophages) decreased with increasing granuloma size. Non-ED2 expressing cells may have been recruited but not sufficiently activated to be lysozyme positive. Inflammatory changes in the cardiac mitral valve noted in previous studies of LMPW were also seen in the F-344 rats in this study but not in the S-D rats. Chemical analysis showed that MHC accumulated in livers from treated F-344 but not S-D rats and the concentration was more than 2-fold greater in MLNs from the F-344 than from the S-D rats. The F-344 appears to be more immunologically sensitive to

  8. An evaluation of the effects of bed rest, sleep deprivation and discontinuance of training on the physical fitness of highly trained young men

    NASA Technical Reports Server (NTRS)

    Olree, H. D.; Corbin, B.; Dugger, G.; Smith, C.

    1973-01-01

    This experiment was conducted to determine what physiological effects result when highly trained subjects are confined to bed, deprived of sleep, or allowed to discontinue training. Results indicated: (1) There was a moderate increase in strength variables due to the training in this experiment but the stress which the subjects received caused a negligible change in strength variables. (2) The training program resulted in highly significant changes in specific bicycle ergometer variables indicating good increases in cardiopulmonary fitness. Five days of bed rest or fifty hours of sleep deprivation caused comparable drastic decreases in cardiopulmonary fitness. Post stress the subjects reverted to a normal daily schedule and after two weeks they had recovered about half of what they lost. (3) Cardiac output remains relatively constant at a constant work load, but stroke volume increases with conditioning and decreases with deconditioning due to stress.

  9. [Space flight/bedrest immobilization and bone. Bisphosphonate and the loss of bone mineral due to space flight or prolonged bed rest].

    PubMed

    Endo, Itsuro; Matsumoto, Toshio

    2012-12-01

    Bone mass and strength are maintained by appropriate weight bearing. The loss of bone mineral due to space flight or prolonged bed rest has been recognized by space scientists and physicians. In spite of the wealth of knowledge obtained thus far, many questions remain unanswered regarding the mechanism of bone loss as well as the factors affecting these skeletal processes. Bisphosphonates have a potential to become countermeasures against space flight-induced or disuse osteoporosis. In this review, the effect and the possible role of biphosphonates on the prevention and treatment of unloading-induced osteoporosis are summarized and future prospects are discussed.

  10. Submaximal Exercise VO2 and Q During 30-Day 6 degree Head-Down Bed Rest with Isotonic and Isokinetic Exercise Training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Erti, A. C.

    1995-01-01

    Submaximal exercise (61+3% peak VO2) metabolism was measured before (AC day-2) and on bed rest day 4, 11, and 25 in 19 healthy men (32-42 yr) allocated into no exercise (NOE, N=5) control, and isotonic exercise (ITE, N=7)and isokinetic exercise (IKE, N=7) training groups. Training was conducting supine for two 30-min periods/d for 6 d/wk: ITE was 60-90% peak VO2: IKE was peak knee flexion-extension at 100 deg/s. Supine submaximal exercise 102 decreased significantly (*p<0.05) by 10.3%, with ITE and by 7.3%* with IKE; similar to the submaximal cardiac output (Q) change of -14.5%* (ITE) and -203%* (IKE), but different from change in peak VO2 (+1.4% with ITE and - 10.2%, with IKE) and plasma volume of -3.7% (ITE) and - 18.0% * (IKE). Thus, reduction of submaximal V02 during prolonged bed rest appears to respond to submaximal Q but is not related to change in peak VO2 or plasma volume.

  11. 78 FR 46322 - Endangered and Threatened Species; 90-Day Finding on Petition To Delist the Southern Oregon...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-31

    ... artificially produced hatchery stocks (70 FR 37160; June 28, 2005). The SCWUA has previously submitted several... be warranted. Negative 90-day findings were published for these petitions on October 7, 2011 (76 FR 62375), January 11, 2012 (77 FR 1668), and September 10, 2012 (77 FR 55458). SCWUA Petition In this...

  12. 76 FR 36053 - Endangered and Threatened Wildlife and Plants; Revised 90-Day Finding on a Petition To Reclassify...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-21

    ...-day finding published on February 21, 2007 (72 FR 7843), constituted our compliance with the... Columbia vacated and remanded our February 21, 2007, not- substantial 90-day finding (72 FR 7843) back to... endangered species on June 4, 1973 (38 FR 14678), pursuant to the Endangered Species Conservation Act of...

  13. 75 FR 19925 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition to List a Distinct...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-16

    ... Biodiversity Project, and others requesting that the Pacific fisher (Martes pennanti pacifica) be listed as an... 90-day finding (56 FR 1159) indicating that the fisher in the Pacific States is a distinct population... habitat needs, population size and trends, and demographic parameters (56 FR 1159). On December 29,...

  14. 75 FR 52928 - Endangered and Threatened Wildlife and Plants; Notice of 90-Day Finding for a Petition to List...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-30

    ... rockfish and tiger rockfish) was insubstantial and we therefore did not conduct status reviews (64 FR 33037... segments of Puget Sound/Georgia Basin distinct population segments of rockfish, 75 FR 22276 (April 28, 2010...; Notice of 90-Day Finding for a Petition to List Georgia Basin Populations of China Rockfish and...

  15. 75 FR 42059 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Giant...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-20

    ... that listing the GPE may be warranted (72 FR 57273). On January 24, 2008, the petitioners filed a... presented a threat (72 FR 57273). The 2009 petition includes a letter of support from Samuel W. James... educational purposes as a potential threat to the GPE. In our October 9, 2007, 90-day finding (72 FR 57273)...

  16. 77 FR 43799 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Gila...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-26

    ... for feeding, breeding, and sheltering; (b) Genetics and taxonomy; (c) Historical and current range... Regional Office. On December 16, 2009 (74 FR 66866), we published a partial 90-day finding on the petition... from dog and horse waste, manipulation and alteration of streamflow by swimmers, and the trampling...

  17. 76 FR 10299 - Endangered and Threatened Wildlife and Plants: 90-Day Finding on a Petition To List the Wild...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-24

    ... completed a 90-day finding on August 15, 2007 (72 FR 45717). Based upon the information available at that... FR 54707), for the Arctic grayling (Thymallus arcticus) and a 12-month finding published on September 22, 2010, for the plant Agave eggersiana (75 FR 57720), we have focused on wild populations in...

  18. 78 FR 23533 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To Delist the Wood Bison

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-19

    ... February 8, 2011 (76 FR ] 6734). Please refer to that document for the complete listing history. Here we... Wildlife, which was published in the Federal Register on June 2, 1970 (35 FR 8491). In 1974, the first list... of Wild Fauna and Flora (CITES). In a 90-day finding published on November 25, 1998 (63 FR 65164),...

  19. 76 FR 60431 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the American...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-29

    ..., 2005, the Service issued a 90-day finding (70 FR 38849), which found that the petition presented... threatened or ] endangered was not warranted (72 FR 4967). Species Information This section is a summary of the species information presented in the Service's 2007 12-month finding (72 FR 4967),...

  20. 77 FR 21920 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Eastern...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-12

    ... a notice of a 90-day finding for the petition in the Federal Register on July 22, 1994 (59 FR 37439... warranted but precluded by other higher priority actions (60 FR 15281). At that time, a listing priority..., 2005 (70 FR 24870). On October 7, 2002, as part of an agreement regarding multiple species, the...

  1. 75 FR 23654 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition to List Hermes Copper...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-04

    ... finding (71 FR 44966, August 8, 2006) is limited to Marschalek and Deutschman's (2008) study of the effect... previous 90-day finding published in the Federal Register on August 8, 2006 (71 FR 44966). Previous Federal... Hermes copper (71 FR 44966) or Thorne's hairstreak butterflies (71 FR 44980) was warranted. (For...

  2. 75 FR 18782 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List Thorne's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List Thorne's Hairstreak Butterfly as Endangered Correction In Federal...

  3. 76 FR 23256 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Arapahoe...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-26

    ... assertion in the petition that mountain biking can cause soil erosion and compaction, degraded water quality... the western United States have been well documented, and include increased soil erosion, sedimentation... published two 90-day findings, on January 6, 2009 (74 FR 419), and February 5, 2009 (74 FR 6122)....

  4. 78 FR 13614 - Endangered and Threatened Wildlife; 90-Day Finding on a Petition To List the Humphead Wrasse as...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-28

    ..., delisting, and reclassifying a species under the ESA (``DPS Policy''; 61 FR 4722; February 7, 1996). A... publications, copies of reports or letters from authorities, and maps (50 CFR 424.14(b)(2)). At the 90-day..., including parts of Fiji, southwestern Indian Ocean and the South China Sea (Sadovy et al., 2003). Threats...

  5. 77 FR 55458 - Endangered and Threatened Species; 90-Day Finding on Petition To Delist the Southern Oregon...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-10

    ... these petitions was published on October 7, 2011 (76 FR 62375) and a second negative 90-day finding for the fourth petition was published on January 11, 2012 (77 FR 1668). The new petition largely..., and drought) rather than man-made factors are responsible for the decline in coho salmon...

  6. Reducing bed rest time from five to three hours does not increase complications after cardiac catheterization: the THREE CATH Trial 1

    PubMed Central

    Matte, Roselene; Hilário, Thamires de Souza; Reich, Rejane; Aliti, Graziella Badin; Rabelo-Silva, Eneida Rejane

    2016-01-01

    Abstract Objective: to compare the incidence of vascular complications in patients undergoing transfemoral cardiac catheterization with a 6F introducer sheath followed by 3-hour versus 5-hour rest. Methods: randomized clinical trial. Subjects in the intervention group (IG) ambulated 3 hours after sheath removal, versus 5 hours in the control group (CG). All patients remained in the catheterization laboratory for 5 hours and were assessed hourly, and were contacted 24, 48, and 72 h after hospital discharge. Results: the sample comprised 367 patients in the IG and 363 in the GC. During cath lab stay, hematoma was the most common complication in both groups, occurring in 12 (3%) IG and 13 (4%) CG subjects (P=0.87). Bleeding occurred in 4 (1%) IG and 6 (2%) CG subjects (P=0.51), and vasovagal reaction in 5 (1.4%) IG and 4 (1.1%) CG subjects (P=0.75). At 24-h, 48-h, and 72-h bruising was the most commonly reported complication in both groups. None of the comparisons revealed any significant between-group differences. Conclusion: the results of this trial show that reducing bed rest time to 3 hours after elective cardiac catheterization is safe and does not increase complications as compared with a 5-hour rest. ClinicalTrials.gov Identifier: NCT-01740856 PMID:27463113

  7. NO{sub x} Abatement Pilot Plant 90-day test results report

    SciTech Connect

    McCray, J.A.; Boardman, R.D.

    1991-08-30

    High-level radioactive liquid wastes produced during nuclear fuel reprocessing at the Idaho Chemical Processing Plant are calcined in the New Waste Calcining Facility (NWCF) to provide both volume reduction and a more stable waste form. Because a large component of the HLW is nitric acid, high levels of oxides of nitrogen (NO{sub x}) are produced in the process and discharged to the environment via the calciner off-gas. The NO{sub x} abatement program is required by the new Fuel Processing Restoration (FPR) project permit to construct to reduce NO{sub x} emissions from the NWCF. Extensive research and development has indicated that the selective catalytic reduction (SCR) process is the most promising technology for treating the NWCF off-gas. Pilot plant tests were performed to determine the compatibility of the SCR process with actual NWCF off-gas. Test results indicate that the SCR process is a viable method for abating the NO{sub x} from the NWCF off-gas. Reduction efficiencies over 95% can be obtained, with minimal amounts of ammonia slip, provided favorable operating conditions exist. Two reactors operated with series flow will provide optimum reduction capabilities. Typical operation should be performed with a first reactor stage gas space velocity of 20,000 hr{sup {minus}1} and an inlet temperature of 320{degrees}C. The first stage exhaust NO{sub x} concentration will then dictate the parameter settings for the second stage. Operation should always strive for a peak reactor temperature of 520{degrees}C in both reactors, with minimal NH{sub 3} slip from the second reactor. Frequent fluctuations in the NWCF off-gas NO{sub x} concentration will require a full-scale reduction facility that is versatile and quick-responding. Sudden changes in NWCF off-gas NO{sub x} concentrations will require quick detection and immediate response to avoid reactor bed over-heating and/or excessive ammonia slip.

  8. Visual-motor response of crewmen during a simulated 90-day space mission as measured by the critical task battery

    NASA Technical Reports Server (NTRS)

    Allen, R. W.; Jex, H. R.

    1973-01-01

    In order to test various components of a regenerative life support system and to obtain data on the physiological and psychological effects of long duration exposure to confinement in a space station atmosphere, four carefully screened young men were sealed in a space station simulator for 90 days and administered a tracking test battery. The battery included a clinical test (Critical Instability Task) designed to measure a subject's dynamic time delay, and a more conventional steady tracking task, during which dynamic response (describing functions) and performance measures were obtained. Good correlation was noted between the clinical critical instability scores and more detailed tracking parameters such as dynamic time delay and gain-crossover frequency. The levels of each parameter span the range observed with professional pilots and astronaut candidates tested previously. The chamber environment caused no significant decrement on the average crewman's dynamic response behavior, and the subjects continued to improve slightly in their tracking skills during the 90-day confinement period.

  9. 76 FR 9309 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Sand...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-17

    ...We, the U.S. Fish and Wildlife Service, announce a 90-day finding on a petition to list the sand verbena moth, Copablepharon fuscum, as endangered or threatened under the Endangered Species Act of 1973, as amended. Based on our review, we find the petition presents substantial information indicating that listing the sand verbena moth may be warranted. Therefore, with the publication of this......

  10. Chronic kidney disease is associated with a higher 90-day mortality than other chronic medical conditions in patients with sepsis

    PubMed Central

    Mansur, Ashham; Mulwande, Evelyn; Steinau, Maximilian; Bergmann, Ingo; Frederik Popov, Aron; Ghadimi, Michael; Beissbarth, Tim; Bauer, Martin; Hinz, José

    2015-01-01

    According to previous studies, the clinical course of sepsis could be affected by preexisting medical conditions, which are very common among patients with sepsis. This observational study aimed at investigating whether common chronic medical conditions affect the 90-day mortality risk in adult Caucasian patients with sepsis. A total of 482 patients with sepsis were enrolled in this study. The ninety-day mortality was the primary outcome; organ failure was the secondary outcome. Sepsis-related organ failure assessment (SOFA) scores and the requirements for organ support were evaluated to assess organ failure. A multivariate Cox regression model for the association between the 90-day mortality risk and chronic preexisting medical conditions adjusted for all relevant confounders and mortality predictors revealed the highest hazard ratio for patients with chronic kidney disease (CKD) (hazard ratio, 2.25; 95% CI, 1.46-3.46; p = 0.0002). Patients with CKD had higher SOFA scores than patients without CKD (8.9 ± 4.0 and 6.5 ± 3.4, respectively; p < 0.0001). Additionally, an analysis of organ-specific SOFA scores revealed higher scores in three organ systems (kidney, cardiovascular and coagulation). Patients with CKD have the highest 90-day mortality risk compared with patients without CKD or with other chronic medical conditions. PMID:25995131

  11. Inhalation toxicity study of disk-shaped potassium octatitanate particles (terracess TF) in rats following 90 days of aerosol exposure.

    PubMed

    Sakai, Seiya; Inada, Kousuke; Tanaka, Akira K; Kelly, David P; Sykes, Greg P; Lee, K P

    2010-01-01

    Since fibrous particles such as asbestos and some man-made fibers (MMF) have been known to produce carcinogenic or fibrogenic effects, disk-shaped potassium octatitanate (POT) particles (trade name: Terracess TF) were manufactured as nonfibrous particles. A 90-day inhalation toxicity study of Terracess TF was performed to evaluate comparative inhalation toxicity of the disk shape with a fibrous shape that was previously evaluated. Four groups of 20 male and 15 female rats each were exposed to Terracess TF aerosols at concentrations of 0, 2, 10, or 50 mg/m(3) for 90 days. Ten male and 10 female rats per group were sacrificed at 90 days of exposure. After 90 days of exposure, 5 male rats per group were sacrificed at 3 wk of recovery period and 4-5 male rats per group or 5 female rats per group were sacrificed at 15 wk of recovery for lung clearance and histopathology. The mass median aerodynamic equivalent diameter (MMAED) of the aerosols of test materials ranged from 2.5 to 2.9 microm. There were no test-substance-related adverse effects on clinical observations. At the end of the 90-day exposure, a slight increase in lung-to-body weight ratios was observed at 50 mg/m(3) in male but not in female rats. However, lung weights were within normal limits after 3- or 15-wk recovery periods. Microscopically, inhaled Terracess TF particles were mostly phagocytized by free alveolar macrophages (AMs) in the alveolar airspaces and alveolar walls maintained normal structure at 2 and 10 mg/m(3). At 50 mg/m(3), some alveoli were distended and filled with aggregates of particle-laden AMs. The alveolar walls showed slight type II pneumocyte hyperplasia, but neither proliferative inflammation nor alveolar fibrosis was present at 50 mg/m(3). The clearance half-times for Terracess TF were estimated to be in the order of 6 to 9 mo for the 50-mg/m(3) group and 2 to 3 mo for the 10- and 2-mg/m(3) groups. The lung responses and lung clearance rate were comparable to those of "nuisance

  12. WISE 2005: flow and nitroglycerin mediated dilation following 56 days of head down tilt bed rest with and without an exercise countermeasure.

    PubMed

    Dyson, K S; Arbeille, Ph; Shoemaker, J K; Custaud, M A; Hughson, R L

    2007-07-01

    This investigation set out to determine the effect of 56 days of head-down tilt bed rest (HDBR) and an exercise countermeasure on endothelial dependent and independent vascular function. 24women took part in this study. 8 subjects completed lower body resistance and aerobic exercise (EX, treadmill running 3-4 days per week for 40-min followed by 10-min of static LBNP, and resistive exercise on a flywheel device every 3rd day) and 16 subjects were considered as non-exercisers in a control group and a protein supplement group. FMD was induced by release of distal limb ischemia and NMD by sublingual administration of 0.3 mg of nitroglycerin before and after HDBR. Preliminary results of this study suggest that HDBR without EX results in a decreased resting diameter of the popliteal while EX increased the diameter. It is also suggested that FMD was elevated without exercise in both brachial and popliteal arteries, while pre-HDBR FMD was preserved by EX in the popliteal, but not the brachial artery. NMD appears to be elevated in the popliteal and femoral in the absence of exercise, but unchanged in the brachial artery or at any site for EX. PMID:18372697

  13. First Report of 90-Day Support of Two Calves with a Continuous-Flow Total Artificial Heart

    PubMed Central

    Karimov, Jamshid H.; Moazami, Nader; Kobayashi, Mariko; Sale, Shiva; Such, Kimberly; Byram, Nicole; Sunagawa, Gengo; Horvath, David; Gao, Shengqiang; Kuban, Barry; Golding, Leonard A.; Fukamachi, Kiyotaka

    2015-01-01

    Objective The Cleveland Clinic continuous-flow total artificial heart (CFTAH) is a compact, single-piece, valveless, pulsatile pump providing self-regulated hemodynamic output to left/right circulation. We evaluated chronic in vivo pump performance, physiologic and hemodynamic parameters, and biocompatibility of the CFTAH in a well-established calf model. Methods CFTAH pumps have been implanted in 17 calves total. Hemodynamics, pump performance, and device-related adverse events were evaluated during studies and at necropsy. Results In vivo experiments demonstrated good hemodynamic performance (pump flow, 7.3 ± 0.7 L/min; left atrial pressure [LAP], 16 ± 3 mm Hg; right atrial pressure [RAP], 17 ± 3 mm Hg; RAP-LAP difference, 1 ± 2 mm Hg; mean arterial pressure, 103 ± 7 mm Hg; arterial pulse pressure, 30 ± 11 mm Hg; pulmonary arterial pressure, 34 ± 5 mm Hg). The CFTAH has operated within design specifications and never failed. With ever-improving pump design, the implants have shown no chronic hemolysis. Three recent animals with the CFTAH recovered well, with no postoperative anticoagulation, during planned in vivo durations of 30, 90, and 90 days (last two were intended to be 90-day studies). All these longest-surviving cases showed good biocompatibility, with no thromboembolism in organs. Conclusions The current CFTAH has demonstrated reliable self-regulation of hemodynamic output and acceptable biocompatibility without anticoagulation throughout 90 days of chronic implantation in calves. Meeting these milestones is in accord with our strategy to achieve transfer of this unique technology to surgical practice, thus filling the urgent need for cardiac replacement devices as destination therapy. PMID:26173607

  14. Toxicological assessment of a prototype e-cigaret device and three flavor formulations: a 90-day inhalation study in rats.

    PubMed

    Werley, Michael S; Kirkpatrick, Dan J; Oldham, Michael J; Jerome, Ann M; Langston, Timothy B; Lilly, Patrick D; Smith, Donna C; Mckinney, Willie J

    2016-01-01

    A prototype electronic cigaret device and three formulations were evaluated in a 90-day rat inhalation study followed by a 42-day recovery period. Animals were randomly assigned to groups for exposure to low-, mid- and high-dose levels of aerosols composed of vehicle (glycerin and propylene glycol mixture); vehicle and 2.0% nicotine; or vehicle, 2.0% nicotine and flavor mixture. Daily targeted aerosol total particulate matter (TPM) doses of 3.2, 9.6 and 32.0 mg/kg/day were achieved by exposure to 1 mg/L aerosol for 16, 48 and 160 min, respectively. Pre-study evaluations included indirect ophthalmoscopy, virology and bacteriological screening. Body weights, clinical observations and food consumption were monitored weekly. Plasma nicotine and cotinine and carboxyhemoglobin levels were measured at days 28 and 90. After days 28, 56 and 90, lung function measurements were obtained. Biological endpoints after 90-day exposure and 42-day recovery period included clinical pathology, urinalysis, bronchoalveolar fluid (BALF) analysis, necropsy and histopathology. Treatment-related effects following 90 days of exposure included changes in body weight, food consumption and respiratory rate. Dose-related decreases in thymus and spleen weights, and increased BALF lactate dehydrogenase, total protein, alveolar macrophages, neutrophils and lung weights were observed. Histopathology evaluations revealed sporadic increases in nasal section 1-4 epithelial hyperplasia and vacuolization. Following the recovery period, effects in the nose and BALF were persistent while other effects were resolved. The no observed effect level based upon body weight decreases is considered to be the mid-dose level for each formulation, equivalent to a daily TPM exposure dose of approximately 9.6 mg/kg/day. PMID:26787428

  15. Toxicological assessment of a prototype e-cigaret device and three flavor formulations: a 90-day inhalation study in rats

    PubMed Central

    Werley, Michael S.; Kirkpatrick, Dan J.; Oldham, Michael J.; Jerome, Ann M.; Langston, Timothy B.; Lilly, Patrick D.; Smith, Donna C.; Mckinney, Willie J.

    2016-01-01

    Abstract A prototype electronic cigaret device and three formulations were evaluated in a 90-day rat inhalation study followed by a 42-day recovery period. Animals were randomly assigned to groups for exposure to low-, mid- and high-dose levels of aerosols composed of vehicle (glycerin and propylene glycol mixture); vehicle and 2.0% nicotine; or vehicle, 2.0% nicotine and flavor mixture. Daily targeted aerosol total particulate matter (TPM) doses of 3.2, 9.6 and 32.0 mg/kg/day were achieved by exposure to 1 mg/L aerosol for 16, 48 and 160 min, respectively. Pre-study evaluations included indirect ophthalmoscopy, virology and bacteriological screening. Body weights, clinical observations and food consumption were monitored weekly. Plasma nicotine and cotinine and carboxyhemoglobin levels were measured at days 28 and 90. After days 28, 56 and 90, lung function measurements were obtained. Biological endpoints after 90-day exposure and 42-day recovery period included clinical pathology, urinalysis, bronchoalveolar fluid (BALF) analysis, necropsy and histopathology. Treatment-related effects following 90 days of exposure included changes in body weight, food consumption and respiratory rate. Dose-related decreases in thymus and spleen weights, and increased BALF lactate dehydrogenase, total protein, alveolar macrophages, neutrophils and lung weights were observed. Histopathology evaluations revealed sporadic increases in nasal section 1–4 epithelial hyperplasia and vacuolization. Following the recovery period, effects in the nose and BALF were persistent while other effects were resolved. The no observed effect level based upon body weight decreases is considered to be the mid-dose level for each formulation, equivalent to a daily TPM exposure dose of approximately 9.6 mg/kg/day. PMID:26787428

  16. Gender-related Changes in Dorsal Hand and Foot Vein Function Following 60 Days of Head Down Bed Rest

    NASA Technical Reports Server (NTRS)

    Westby, Christian M.; Phillips, Tiffany; Stenger, Michael B.; Platts, Steven H.

    2009-01-01

    It is well known that female astronauts are more likely to experience post-flight orthostatic hypotension and presyncope compared to male astronauts. It has been suggested that the disproportionally higher incidence of presyncope (83% of female vs. 20% male crewmembers) may be due to sex-related differences in vascular function between the upper and lower limbs. However, much of this evidence is specific to changes in resistance vessels. Given that more than 70% of the circulating blood volume resides in compliance vessels, it is conceivable that even small changes in venous function may contribute to post-flight orthostatic hypotension. In spite of this, little is currently known regarding the influence of microgravity exposure on venous function between males and females. PURPOSE: To determine the influence of 60 days of HDBR on dorsal foot and hand vein function between healthy males (M) and females (F). METHODS: Using 2-D ultrasound, dorsal hand and foot vein diameter responses to intravenous infusions phenylephrine (PE), acetylcholine (ACh), and nitroglycerine (NTG) were determined in 26 adults; 10 females (age:37 +/- 2 yr ) and 16 males (age:34 +/- 2 yr ). Changes in venous function were calculated as the difference between diameter at baseline and following each venoactive drug. Differences in venous function between limb and sexes across HDBR were determined using mixed-effects linear regression. RESULTS: In response to 60 days of HDBR, the change in venousconstrictor response to PE in the dorsal hand veins was not significantly different between M and F. Interestingly, the change in constrictor response in the dorsal foot veins (compared to pre HDBR) was approximately 30% greater in the F, whereas the constrictor response was approximately 45% less in the M (p=0.026). HDBR had no influence on the change in dilator response to ACh, or NTG between M and F and between vascular beds. CONCLUSION: These results demonstrate that 60 days of HDBR contributes to sex

  17. Safety assessment of essential oil from Minthostachys verticillata (Griseb.) Epling (peperina): 90-days oral subchronic toxicity study in rats.

    PubMed

    Escobar, Franco Matías; Sabini, María Carola; Cariddi, Laura Noelia; Sabini, Liliana Inés; Mañas, Fernando; Cristofolini, Andrea; Bagnis, Guillermo; Gallucci, Mauro Nicolas; Cavaglieri, Lilia Renée

    2015-02-01

    Minthostachys verticillata (Lamiaceae), popularly known as peperina is largely used in popular medicine for its digestive, carminative, antispasmodic and antirheumatic properties. There are no reports of repeated exposure toxicity to guarantee their safety. The present study investigated the chemical composition, analyzed by GC-FID, and the 90-day toxicity and genotoxicity effect of M. verticillata essential oil (Mv-EO), using Wistar rats as test animals. The rats were divided into four groups (5 rats/sex/group) and Mv-EO was administered on diet at doses of 0, 1, 4 and 7 g/kg feed. The main components of Mv-EO were pulegone (64.65%) and menthone (23.92%). There was no mortality, adverse effects on general conditions or changes in body weight, food consumption and feed conversion efficiency throughout the study in male and female rats. Subchronic administration of Mv-EO did not alter the weights, morphological and histopathological analyses of liver, kidney and intestine. Genotoxicity was tested by micronucleus and comet assays. Mv-EO up to a concentration of 7 g/kg feed for 90 days did not exert a cyto-genotoxic effect on the bone marrow and cells blood of Wistar rats. These results suggest that Mv-EO appears to be safe and could be devoid of any toxic risk.

  18. A 90-day safety study of genetically modified rice expressing Cry1Ab protein (Bacillus thuringiensis toxin) in Wistar rats.

    PubMed

    Schrøder, Malene; Poulsen, Morten; Wilcks, Andrea; Kroghsbo, Stine; Miller, Andreas; Frenzel, Thomas; Danier, Jürgen; Rychlik, Michael; Emami, Kaveh; Gatehouse, Angharad; Shu, Qingyao; Engel, Karl-Heinz; Altosaar, Illimar; Knudsen, Ib

    2007-03-01

    An animal model for safety assessment of genetically modified foods was tested as part of the SAFOTEST project. In a 90-day feeding study on Wistar rats, the transgenic KMD1 rice expressing Cry1Ab protein was compared to its non-transgenic parental wild type, Xiushui 11. The KMD1 rice contained 15mg Bt toxin/kg and based on the average feed consumption the daily intake was 0.54mg Bt toxin/kg body weight. No adverse effects on animal behaviour or weight gain were observed during the study. Blood samples collected one week prior to sacrifice were analyzed and compared for standard haematological and biochemical parameters. A few parameters were significantly different, but all within the normal reference intervals for rats of this breed and age and not in relation to any other findings, thus not considered treatment related. Upon sacrifice a large number of organs were weighed, macroscopic and histopathological examinations were performed with only minor changes to report. The aim of the study was to use a known animal model in performance of safety assessment of a GM crop, in this case KMD1 rice. The results show no adverse or toxic effects of KMD1 rice when tested in the design used in this 90-day study. Nevertheless the experiences from this study lead to the overall conclusion that safety assessment for unintended effects of a GM crop cannot be done without additional test group(s).

  19. Effects of 90-day feeding of transgenic Bt rice TT51 on the reproductive system in male rats.

    PubMed

    Wang, Er Hui; Yu, Zhou; Hu, Jing; Xu, Hai Bin

    2013-12-01

    Rice is a staple food crop; however, the threat of pests leads to a serious decline in its output and quality. The CryAb/CryAc gene, encodes a synthetic fusion Bacillus thuringiensis (Bt) crystal protein, was introduced into rice MingHui63 to produce insect-resistant rice TT51. This study was undertaken to investigate potential unintended effects of TT51 on the reproductive system in male rats. Male rats were treated with diets containing 60% of either TT51 or MingHui63 by weight, nutritionally balanced to an AIN93G diet, for 90days. An additional negative control group of rats were fed with a rice-based AIN93G diet. Body weights, food intake, hematology, serum chemistry, serum hormone levels, sperm parameters and relative organ/body weights were measured, and gross as well as microscopic pathology were examined. No diet-related significant differences in the values of response variables were observed between rats that were fed with diet containing transgenic TT51, MingHui63 and the control in this 90-day feeding study. In addition, necropsy and histopathology examination indicated no treatment-related changes. The results from the present study indicated that TT51 does not appear to exert any effect on the reproductive system in male rats compared with MingHui63 or the control.

  20. The development and succession of microbial communities in 90-day Bioregenerative Life Support Experiment in the Lunar Palace 1

    NASA Astrophysics Data System (ADS)

    Sun, Yi; Liu, Hong; Fu, Yuming; Liu, Bojie; Su, Qiang; Xie, Beizhen; Qin, Youcai; Dong, Chen; Liu, Guanghui

    Lunar Palace 1, as an integrative experiment facility for permanent astrobase life-support artificial closed ecosystem, is an artificial ecosystem which consists of plant cultivation, animal breeding and waste treatment units. It has been used to carry out a 90-day bioregenerative life support experiment with three crew members. Apparently, it’s hard to prevent the growth of microorganisms in such closed ecosystem for their strong adaptive capacity. Original microorganisms in the cabin, microbes in the course of loads delivery and the autologous microorganism by crew members and animals themselves are all the main source of the interior microorganisms, which may grow and regenerate in air, water and plants. Therefore, if these microorganisms could not be effectively monitored and controlled, it may cause microbial contamination and even lead to the unsteadiness of the whole closed ecosystem. In this study, the development and succession of the microbial communities of air, water system, plant system, and key facilities surfaces in Lunar Palace 1 were continuously monitored and analyzed by using plate counting method and molecular biological method during the 90-day experiment. The results were quite useful for the controlling of internal microorganisms and the safe operation of the whole system, and could also reveal the succession rules of microorganisms in an artificial closed ecosystem.

  1. A 90-day subchronic oral toxicity study of triterpene-enriched extract from Alismatis Rhizoma in rats.

    PubMed

    Huang, Ming-Qing; Xu, Wen; Wu, Shui-Shen; Lu, Jin-Jian; Chen, Xiu-Ping

    2013-08-01

    Alismatis Rhizoma has been used in East Asia as a traditional treatment for various illnesses and symptoms, and the presence of protostane-type triterpenes has been claimed to provide health benefits. To investigate the subchronic toxicity of triterpene-enriched extract from Alismatis Rhizoma (TEAR), a 90-day oral toxicity study was conducted in rats. Sprague-Dawley rats were randomly divided into four groups (10 rats/sex/group) and received doses of 0, 360, 720, and 1440 mg/kg/d of TEAR for 90 days. Daily clinical observations as well as weekly measurement of body weight and food consumption were conducted. Blood samples were obtained on day 91 to measure changes in hematology and biochemistry. Urine samples were collected on days 0 and 91 for urinalysis. At necropsy, selected organs were weighed and recorded, and histological examination was performed. No mortality or obvious treatment-related clinical signs, hematology, urinalysis parameters, and macroscopic or microscopic examinations were observed. Differences in weight gain, food consumption, biochemistry, and relative organ weight between the treated group and the control group were not considered treatment-related. On the basis of these findings, the no-observed-adverse-effect level for TEAR was 1440 mg/kg/d in both sexes. PMID:23684999

  2. A 90-day subchronic toxicity study with sodium formononetin-3'-sulphonate (Sul-F) delivered to dogs via intravenous administration.

    PubMed

    Li, Chunmei; Li, Guisheng; Gao, Yonglin; Sun, Chengfeng; Wang, Xiaoyan

    2016-06-01

    Sodium formononetin-3'-sulphonate (Sul-F) is a water-soluble derivate of formononetin, and an increasing number of studies have shown that Sul-F not only possesses favorable water solubility but also exhibits good lipid-lowering and bioactivities. In the current study, the toxicity of Sul-F was evaluated in dogs after 90-day intravenous infusion. Dogs were treated with Sul-F at dose of 0, 33.3, 100, and 300 mg/kg, and observed for 90-day followed by 28-day recovery period. Weekly measurement of body weight, temperature and food consumption were conducted. Ophthalmoscopy, ECG examination, urinalysis, serum biochemistry and hematology examination were performed at pre-test, on days 45 and 90, and following by 28-day recovery period. Histological examination was performed on day 90 and 28-day recovery period. No mortality, ophthalmic abnormalities or treatment-related findings in body weight, clinical chemistry, hematology, and histopathological examination were detected. However, a white crystal (non-metabolic Sul-F), transient vomiting and recoverable vascular stimulation were observed in 300 mg/kg/day Sul-F treated dogs. Under the conditions, the no-observed-adverse-effect-level (NOAEL) for Sul-F was 100 mg/kg in dogs.

  3. Safety assessment of EPA-rich oil produced from yeast: Results of a 90-day subchronic toxicity study.

    PubMed

    MacKenzie, Susan A; Belcher, Leigh A; Sykes, Greg P; Frame, Steven R; Mukerji, Pushkor; Gillies, Peter J

    2010-12-01

    The safety of eicosapentaenoic acid (EPA) oil produced from genetically modified Yarrowia lipolytica yeast was evaluated following 90 days of exposure. Groups of rats received 0 (olive oil), 98, 488, or 976 mg EPA/kg/day, or GRAS fish oil or deionized water by oral gavage. Rats were evaluated for in-life, neurobehavioral, anatomic and clinical pathology parameters. Lower serum cholesterol (total and non-HDL) was observed in Medium and High EPA and fish oil groups. Lower HDL was observed in High EPA and fish oil males, only at early time points. Liver weights were increased in High EPA and Medium EPA (female only) groups with no associated clinical or microscopic pathology findings. Nasal lesions, attributed to oil in the nasal cavity, were observed in High and Medium EPA and fish oil groups. No other effects were attributed to test oil exposure. Exposure to EPA oil for 90 days produced no effects at 98 mg EPA/kg/day and no adverse effects at doses up to 976 mg EPA/kg/day. The safety profile of EPA oil was comparable to that of GRAS fish oil. These results support the use of EPA oil produced from yeast as a safe source for use in dietary supplements.

  4. Effects of Resistive Vibration Exercise Combined with Whey Protein and KHCO3 on Bone Tturnover Markers in Head-down Tilt Bed Rest (MTBR-MNX Study)

    NASA Technical Reports Server (NTRS)

    Graf, Sonja; Baecker, Natalie; Buehlmeier, Judith; Fischer, Annelie; Smith, Scott M.; Heer, Martina

    2014-01-01

    High protein intake further increases bone resorption markers in head-down tilt bed rest (HDBR), most likely induced by low-grade metabolic acidosis. Adding an alkaline salt to a diet with high protein content prevents this additional rise of bone resorption markers in HDBR. In addition, high protein intake, specifically whey protein, increases muscle protein synthesis and improves glucose tolerance, which both are affected by HDBR. Resistive vibration exercise (RVE) training counteracts the inactivity-induced bone resorption during HDBR. To test the hypothesis that WP plus alkaline salt (KHCO3) together with RVE during HDBR will improve bone turnover markers, we conducted a randomized, three-campaign crossover design study with 12 healthy, moderately fit male subjects (age 34+/-8 y, body mass [BM] 70 +/- 8 kg). All study campaigns consisted of a 7-d ambulatory period, 21days of -6 deg. head-down tilt bed rest (HDBR), and a 6-d recovery period. Diet was standardized and identical across phases. In the control (CON) campaign, subjects received no supplement or RVE. In the intervention campaigns, subjects received either RVE alone or combined with WP and KHCO3 (NEX). WP was applied in 3 doses per day of 0.6 g WP/kg BM together with 6 doses of 15 mmol KHCO3 per day. Eleven subjects completed the RVE and CON campaign, 8 subjects completed all three campaigns. On day 21 of HDBR excretion of the bone resorption marker C-telopeptide (CTX) was 80+/-28% (p<0.001) higher than baseline, serum calcium concentrations increased by 12 +/- 29% (p<0.001) and serum osteocalcin concentrations decreased by 6+/-12% (p=0.001). Urinary CTX excretion was 11+/- 25% (p=0.02) lower on day 21 of HDBR in the RVE- and tended to decrease by 3+/- 22% (p=0.06) in the NEX campaign compared to CON. Urinary calcium excretion was higher on day 21 in HDBR in the RVE and NEX (24+/- 43% p=0.01; 25+/- 37% p=0.03) compared to the CON campaign. We conclude that combination of RVE with WP/KHCO3 was not

  5. Effects of Three-Day Bed Rest on Physiological Responses to Graded Exercise in Endurance Athletes, Body Builders and Sedentary Men

    NASA Technical Reports Server (NTRS)

    Smorawinski, J.; Nazar, K.; Kaciuza-Uscilko, H.; Kaminska, E.; Cybulski, G.; Kodrzycka, A.; Bice, B.; Greenleaf, J. E.; Sun, Sid (Technical Monitor)

    2001-01-01

    To test the hypotheses that short-term bed rest (BR) deconditioning influences metabolic, cardiorespiratory and neurohormonal responses to exercise and that these effects depend on the subjects' training status 12 sedentary men, and 10 endurance- and 10 strength-trained athletes were submitted to three-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and HR were recorded continuously and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate [LA], adrenaline [A], noradrenaline, [NA], renting activity (PRA), growth hormone [hGH], testosterone and cortisol determination. Reduction of peak oxygen uptake (VO2peak) after BR was greater in the endurance athletes (than in the remaining groups (17 % vs. 100%). Decrements in VO2peak correlated positively with the initial values (r = 0.73, p less than 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased the in endurance athletes from 71 to 60 %VO2 peak (p less than 0.001); they also had an earlier increase in [NA], and an attenuated increase in [hGH), and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion: reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

  6. Effects of Three-Day Bed Rest on Physiological Responses to Graded Exercise in Endurance Athletes, Body Builders and Sedentary Men

    NASA Technical Reports Server (NTRS)

    Smorawinski, J.; Nazar, K.; Kaciuza-Uscilko; Kaminska, E.; Kodrzycka, A.; Bicz, B.; Greenleaf, J. E.

    2001-01-01

    To test the hypotheses that short-term bed rest (BR) deconditioning influences metabolic, cardiorespiratory and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men, and 10 endurance- and 10 strength-trained athletes were submitted to three-day BR. Before and after BR they performed incremental exercise tests until volitional exhaustion. Respiratory gas exchange and HR were recorded continuously and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate [LA], adrenaline [A], noradrenaline [NA], renin activity (PRA), growth hormone [hGH], testosterone and cortisol determination. Reduction of peak oxygen uptake (V02peak) after BR was greater in the endurance athletes than in the remaining groups (17 % vs. 10%). Decrements in VO2peak correlated positively with the initial values (r = 0.73, p is less than 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased the in endurance athletes from 71 to 60% V02 peak (p is less than0.001), they also had an earlier increase in [NA], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion: reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

  7. 90-Day Cycle: Exploration of Math Intensives as a Strategy to Move More Community College Students out of Developmental Math Courses

    ERIC Educational Resources Information Center

    Sherer, Jennifer Zoltners; Grunow, Alicia

    2010-01-01

    The authors prepared this report after exploring programs using a 90-day cycle process borrowed from the Institute for Healthcare Improvement (IHI). The IHI 90-day cycle scans activity in the field as a "quick way to research innovative ideas and assess their potential for advancing quality improvement". The goal was to "get under the hood" of…

  8. Pulmonary toxicity of simulated lunar and Martian dusts in mice: I. Histopathology 7 and 90 days after intratracheal instillation.

    PubMed

    Lam, Chiu-Wing; James, John T; McCluskey, Richard; Cowper, Shawn; Balis, John; Muro-Cacho, Carlos

    2002-09-01

    NASA is contemplating sending humans to Mars and to the moon for further exploration. Volcanic ashes from Arizona and Hawaii with mineral properties similar to those of lunar and Martian soils, respectively, are used to simulate lunar and Martian environments for instrument testing. Martian soil is highly oxidative; this property is not found in Earth's volcanic ashes. NASA is concerned about the health risk from potential exposure of workers in the test facilities. Fine lunar soil simulant (LSS), Martian soil simulant (MSS), titanium dioxide, or quartz in saline was intratracheally instilled into groups of 4 mice (C57BL/6J) at 0.1 mg/mouse (low dose, LD) or 1 mg/mouse (high dose, HD). Separate groups of mice were exposed to ozone (0.5 ppm for 3 h) prior to MSS instillation. Lungs were harvested for histopathological examination 7 or 90 days after the single dust treatment. The lungs of the LSS-LD groups showed no evidence of inflammation, edema, or fibrosis; clumps of particles and an increased number of macrophages were visible after 7 days but not 90 days. In the LSS-HD-7d group, the lungs showed mild to moderate alveolitis, and perivascular and peribronchiolar inflammation. The LSS-HD-90d group showed signs of mild chronic pulmonary inflammation, septal thickening, and some fibrosis. Foci of particle-laden macrophages (PLMs) were still visible. Lung lesions in the MSS-LD-7d group were similar to those observed in the LSS-HD-7d group. The MSS-LD-90d group had PLMs and scattered foci of mild fibrosis in the lungs. The MSS-HD-7d group showed large foci of PLMs, intra-alveolar debris, mild-to-moderate focal alveolitis, and perivascular and peribronchiolar inflammation. The MSS-HD-90d group showed focal chronic mild-to-moderate alveolitis and fibrosis. The findings in the O(3)-MSS-HD-90d group included widespread intra-alveolar debris, focal moderate alveolitis, and fibrosis. Lung lesions in the MSS groups were more severe with the ozone pretreatment. The effects of

  9. Pulmonary toxicity of simulated lunar and Martian dusts in mice: I. Histopathology 7 and 90 days after intratracheal instillation

    NASA Technical Reports Server (NTRS)

    Lam, Chiu-Wing; James, John T.; McCluskey, Richard; Cowper, Shawn; Balis, John; Muro-Cacho, Carlos

    2002-01-01

    NASA is contemplating sending humans to Mars and to the moon for further exploration. Volcanic ashes from Arizona and Hawaii with mineral properties similar to those of lunar and Martian soils, respectively, are used to simulate lunar and Martian environments for instrument testing. Martian soil is highly oxidative; this property is not found in Earth's volcanic ashes. NASA is concerned about the health risk from potential exposure of workers in the test facilities. Fine lunar soil simulant (LSS), Martian soil simulant (MSS), titanium dioxide, or quartz in saline was intratracheally instilled into groups of 4 mice (C57BL/6J) at 0.1 mg/mouse (low dose, LD) or 1 mg/mouse (high dose, HD). Separate groups of mice were exposed to ozone (0.5 ppm for 3 h) prior to MSS instillation. Lungs were harvested for histopathological examination 7 or 90 days after the single dust treatment. The lungs of the LSS-LD groups showed no evidence of inflammation, edema, or fibrosis; clumps of particles and an increased number of macrophages were visible after 7 days but not 90 days. In the LSS-HD-7d group, the lungs showed mild to moderate alveolitis, and perivascular and peribronchiolar inflammation. The LSS-HD-90d group showed signs of mild chronic pulmonary inflammation, septal thickening, and some fibrosis. Foci of particle-laden macrophages (PLMs) were still visible. Lung lesions in the MSS-LD-7d group were similar to those observed in the LSS-HD-7d group. The MSS-LD-90d group had PLMs and scattered foci of mild fibrosis in the lungs. The MSS-HD-7d group showed large foci of PLMs, intra-alveolar debris, mild-to-moderate focal alveolitis, and perivascular and peribronchiolar inflammation. The MSS-HD-90d group showed focal chronic mild-to-moderate alveolitis and fibrosis. The findings in the O(3)-MSS-HD-90d group included widespread intra-alveolar debris, focal moderate alveolitis, and fibrosis. Lung lesions in the MSS groups were more severe with the ozone pretreatment. The effects of

  10. A 90-day study of three bruchid-resistant mung bean cultivars in Sprague-Dawley rats.

    PubMed

    Yao, Yang; Cheng, Xuzhen; Ren, Guixing

    2015-02-01

    Mung bean has been traditionally and widely used as an edible and medicinal plant in the South and Southeast Asia. Bruchid resistance mung bean has more potential in commercial use, but scarcely been evaluated for safety through standard in vivo toxicological studies. In the present study, subchronic oral toxicity studies of bruchid-resistant mung bean were designed and conducted in Sprague-Dawley (SD) rats for 90 days. During the subchronic oral toxicity study, no mortality and toxicologically significant changes in clinical signs, food consumption, opthalmoscopic examination, hematology, clinical biochemistry, macroscopic findings, organ weights and histopathological examination were noted in animal administered diet containing bruchid-resistant mung bean. These results demonstrated that bruchid resistant mung bean is as safe as conventional mung bean.

  11. Dietary and Food Processing for a 90-day Bioregenerative Life Support Experiment in the Lunar Palace 1

    NASA Astrophysics Data System (ADS)

    Zhao, Zhiruo; Fu, Yuming; Dong, Chen; Liu, Guanghui

    A 4-day cycle dietary menu was developed to meet the requirements of balanced diet of the crew within the 90-day closed experiment of bioregenerative life support in the Lunar Palace 1. The menu consisted of items prepared from crops and insect grown inside the system, as well as prestored food. Dairy recipe was composed of breads, vegetables, meats and soups, which provided about 2900 kcal per crew member per day. During food processing, to maximize nutrient recovery and minimize waste production, the whole wheat grains and chufa nuts were milled. Further, the carrot leaves and yellow mealworms were used as salad materials and bread ingredients, respectively. The sensory acceptability of the dishes in the menu was evaluated by flavor, texture, and appearance. Our results show that all dishes in the 4-day cycle menu were highly acceptable, which satisfies nutritional requirement of the crew members in the closed habitation.

  12. Toxicity of 100 nm zinc oxide nanoparticles: a report of 90-day repeated oral administration in Sprague Dawley rats

    PubMed Central

    Kim, Yu-Ri; Park, Jong-Il; Lee, Eun Jeong; Park, Sung Ha; Seong, Nak-won; Kim, Jun-Ho; Kim, Geon-Yong; Meang, Eun-Ho; Hong, Jeong-Sup; Kim, Su-Hyon; Koh, Sang-Bum; Kim, Min-Seok; Kim, Cheol-Su; Kim, Soo-Ki; Son, Sang Wook; Seo, Young Rok; Kang, Boo Hyon; Han, Beom Seok; An, Seong Soo A; Yun, Hyo-In; Kim, Meyoung-Kon

    2014-01-01

    Nanoparticles (NPs) are used commercially in health and fitness fields, but information about the toxicity and mechanisms underlying the toxic effects of NPs is still very limited. The aim of this study is to investigate the toxic effect(s) of 100 nm negatively (ZnOAE100[−]) or positively (ZnOAE100[+]) charged zinc oxide (ZnO) NPs administered by gavage in Sprague Dawley rats, to establish a no observed adverse effect level, and to identify target organ(s). After verification of the primary particle size, morphology, hydrodynamic size, and zeta potential of each test article, we performed a 90-day study according to Organisation for Economic Co-operation and Development test guideline 408. For the 90-day study, the high dose was set at 500 mg/kg and the middle and low doses were set at 125 mg/kg and 31.25 mg/kg, respectively. Both ZnO NPs had significant changes in hematological and blood biochemical analysis, which could correlate with anemia-related parameters, in the 500 mg/kg groups of both sexes. Histopathological examination showed significant adverse effects (by both test articles) in the stomach, pancreas, eye, and prostate gland tissues, but the particle charge did not affect the tendency or the degree of the lesions. We speculate that this inflammatory damage might result from continuous irritation caused by both test articles. Therefore, the target organs for both ZnOAE100(−) and ZnOAE100(+) are considered to be the stomach, pancreas, eye, and prostate gland. Also, the no observed adverse effect level for both test articles was identified as 31.25 mg/kg for both sexes, because the adverse effects were observed at all doses greater than 125 mg/kg. PMID:25565830

  13. A 90-day safety study in Wistar rats fed genetically modified rice expressing snowdrop lectin Galanthus nivalis (GNA).

    PubMed

    Poulsen, Morten; Kroghsbo, Stine; Schrøder, Malene; Wilcks, Andrea; Jacobsen, Helene; Miller, Andreas; Frenzel, Thomas; Danier, Jürgen; Rychlik, Michael; Shu, Qingyao; Emami, Kaveh; Sudhakar, Duraialagraja; Gatehouse, Angharad; Engel, Karl-Heinz; Knudsen, Ib

    2007-03-01

    Genetically modified plants expressing insecticidal traits offer a new strategy for crop protection, but at the same time present a challenge in terms of food safety assessment. The present 90-day feeding study was designed to assess the safety of a rice variety expressing the snowdrop Galanthus nivalis lectin (GNA lectin), and forms part of a EU-funded project where the objective has been to develop and validate sensitive and specific methods to assess the safety of genetically modified foods. Male and female Wistar rats were given a purified diet containing either 60% genetically modified or parental rice for 90 days. This corresponds to a mean daily GNA lectin intake of approximately 58 and 67mg/kg body weight for males and females, respectively. Prior to the animal study comprehensive analytical characterization of both rice materials was performed. The chemical analyses showed a number of statistically significant differences, with the majority being within the ranges reported in the literature. In the animal study a range of clinical, biological, immunological, microbiological and pathological parameters were examined. A number of significant differences were seen between groups fed the two diets, but none of them were considered to be adverse. In conclusion, the design of the present animal study did not enable us to conclude on the safety of the GM food. Additional group(s) where the expressed gene products have been spiked to the diet should be included in order to be able to distinguish whether the observed effects were due to the GNA lectin per se or to secondary changes in the GM rice.

  14. Toxicity of 100 nm zinc oxide nanoparticles: a report of 90-day repeated oral administration in Sprague Dawley rats.

    PubMed

    Kim, Yu-Ri; Park, Jong-Il; Lee, Eun Jeong; Park, Sung Ha; Seong, Nak-won; Kim, Jun-Ho; Kim, Geon-Yong; Meang, Eun-Ho; Hong, Jeong-Sup; Kim, Su-Hyon; Koh, Sang-Bum; Kim, Min-Seok; Kim, Cheol-Su; Kim, Soo-Ki; Son, Sang Wook; Seo, Young Rok; Kang, Boo Hyon; Han, Beom Seok; An, Seong Soo A; Yun, Hyo-In; Kim, Meyoung-Kon

    2014-01-01

    Nanoparticles (NPs) are used commercially in health and fitness fields, but information about the toxicity and mechanisms underlying the toxic effects of NPs is still very limited. The aim of this study is to investigate the toxic effect(s) of 100 nm negatively (ZnO(AE100[-])) or positively (ZnO(AE100[+])) charged zinc oxide (ZnO) NPs administered by gavage in Sprague Dawley rats, to establish a no observed adverse effect level, and to identify target organ(s). After verification of the primary particle size, morphology, hydrodynamic size, and zeta potential of each test article, we performed a 90-day study according to Organisation for Economic Co-operation and Development test guideline 408. For the 90-day study, the high dose was set at 500 mg/kg and the middle and low doses were set at 125 mg/kg and 31.25 mg/kg, respectively. Both ZnO NPs had significant changes in hematological and blood biochemical analysis, which could correlate with anemia-related parameters, in the 500 mg/kg groups of both sexes. Histopathological examination showed significant adverse effects (by both test articles) in the stomach, pancreas, eye, and prostate gland tissues, but the particle charge did not affect the tendency or the degree of the lesions. We speculate that this inflammatory damage might result from continuous irritation caused by both test articles. Therefore, the target organs for both ZnO(AE100(-)) and ZnO(AE100(+)) are considered to be the stomach, pancreas, eye, and prostate gland. Also, the no observed adverse effect level for both test articles was identified as 31.25 mg/kg for both sexes, because the adverse effects were observed at all doses greater than 125 mg/kg. PMID:25565830

  15. A 90-Day Toxicology Study of Meat from Genetically Modified Sheep Overexpressing TLR4 in Sprague-Dawley Rats

    PubMed Central

    Hu, Rui; Kan, Tongtong; Li, Yan; Zhang, Xiaosheng; Zhang, Jinlong; Lian, Ling; Han, Hongbing; Lian, Zhengxing

    2015-01-01

    Genetic modification offers alternative strategies to traditional animal breeding. However, the food safety of genetically modified (GM) animals has attracted increasing levels of concern. In this study, we produced GM sheep overexpressing TLR4, and the transgene-positive offsprings (F1) were confirmed using the polymerase chain reaction (PCR) and Southern blot. The expression of TLR4 was 2.5-fold compared with that of the wild-type (WT) sheep samples. During the 90-day safety study, Sprague-Dawley rats were fed with three different dietary concentrations (3.75%, 7.5%, and 15% wt/wt) of GM sheep meat, WT sheep meat or a commercial diet (CD). Blood samples from the rats were collected and analyzed for hematological and biochemical parameters, and then compared with hematological and biochemical reference ranges. Despite a few significant differences among the three groups in some parameters, all other values remained within the normal reference intervals and thus were not considered to be affected by the treatment. No adverse diet-related differences in body weights or relative organ weights were observed. Furthermore, no differences were observed in the gross necropsy findings or microscopic pathology of the rats whose diets contained the GM sheep meat compared with rats whose diets contained the WT sheep meat. Therefore, the present 90-day rat feeding study suggested that the meat of GM sheep overexpressing TLR4 had no adverse effect on Sprague-Dawley rats in comparison with WT sheep meat. These results provide valuable information regarding the safety assessment of meat derived from GM animals. PMID:25874566

  16. A 90-day toxicology study of meat from genetically modified sheep overexpressing TLR4 in Sprague-Dawley rats.

    PubMed

    Bai, Hai; Wang, Zhixian; Hu, Rui; Kan, Tongtong; Li, Yan; Zhang, Xiaosheng; Zhang, Jinlong; Lian, Ling; Han, Hongbing; Lian, Zhengxing

    2015-01-01

    Genetic modification offers alternative strategies to traditional animal breeding. However, the food safety of genetically modified (GM) animals has attracted increasing levels of concern. In this study, we produced GM sheep overexpressing TLR4, and the transgene-positive offsprings (F1) were confirmed using the polymerase chain reaction (PCR) and Southern blot. The expression of TLR4 was 2.5-fold compared with that of the wild-type (WT) sheep samples. During the 90-day safety study, Sprague-Dawley rats were fed with three different dietary concentrations (3.75%, 7.5%, and 15% wt/wt) of GM sheep meat, WT sheep meat or a commercial diet (CD). Blood samples from the rats were collected and analyzed for hematological and biochemical parameters, and then compared with hematological and biochemical reference ranges. Despite a few significant differences among the three groups in some parameters, all other values remained within the normal reference intervals and thus were not considered to be affected by the treatment. No adverse diet-related differences in body weights or relative organ weights were observed. Furthermore, no differences were observed in the gross necropsy findings or microscopic pathology of the rats whose diets contained the GM sheep meat compared with rats whose diets contained the WT sheep meat. Therefore, the present 90-day rat feeding study suggested that the meat of GM sheep overexpressing TLR4 had no adverse effect on Sprague-Dawley rats in comparison with WT sheep meat. These results provide valuable information regarding the safety assessment of meat derived from GM animals.

  17. Transcutaneous electrical acupuncture stimulation as a countermeasure against cardiovascular deconditioning during 4 days of head-down bed rest in humans

    PubMed Central

    Sun, Jing; Li, Xiaotao; Yang, Changbin; Wang, Yongchun; Shi, Fei; Gao, Yuan; Luan, Qi; Zhu, Yongsheng; Sun, Xiqing

    2015-01-01

    Objective Spaceflight is associated with cardiovascular deregulation. However, the influence of microgravity on the cardiovascular system and its mechanisms and countermeasures remain unknown. Our previous studies have demonstrated that transcutaneous electrical acupuncture stimulation (TEAS) is effective in improving orthostatic tolerance (OT). The purpose of this study was to determine if TEAS treatment can attenuate cardiovascular deconditioning induced by a 4-day −6° head-down bed rest (HDBR). Methods Fourteen healthy male subjects were randomly allocated to a control group (control, n=6, 4 days HDBR without countermeasures) and a TEAS treatment group (TEAS, n=8, 4 days HDBR with TEAS at Neiguan (PC6) for 30 min each day for 4 consecutive days during HDBR). OT, plasma hormones, plasma volume and heart rate variability were assessed before and after HDBR. Cardiac function and cerebral blood flow were measured before, during and after HDBR. Results The data showed that TEAS treatment mitigated the decrease in OT that was observed in the control group and cardiac function, alleviated autonomic dysfunction, and partially prevented plasma volume reduction after HDBR. Angiotensin II and aldosterone were significantly increased by 129.3% and 133.3% after HDBR in the TEAS group (p<0.05). Conclusions These results indicate that 30 min of daily TEAS treatment at PC6 is partially effective in maintaining OT, probably due to increased plasma volume-regulating hormones and activation of the peripheral sympathetic nervous system. TEAS treatment appears effective at reducing cardiovascular deconditioning induced by HDBR for 4 days. Trial registration number NCT02300207. PMID:26025383

  18. Mapping by VESGEN of Blood Vessels in the Retinas of ISS Crew Members and Bed Rest Subjects for Increased Understanding of VIIP

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, P. A.; Vizzeri, G.; Tabbi, G.; Zanello, S. B.; Ploutz-Snyder, R.

    2014-01-01

    Research by NASA has established that significant risks for visual impairment in association with increased intracranial pressure (VIIP) are incurred by microgravity spaceflight, especially long-duration missions. Impairments include decreased near visual acuity, posterior globe flattening, choroidal folds, optic disc edema, and cotton wool spots. Much remains to be learned about the etiology of VIIP before effective countermeasures can be developed. Contributions of retinal vascular remodeling to the etiology of VIIP have not yet been investigated, primarily due to the current lack of ophthalmic tools for precisely measuring progressive pathophysiological remodeling of the retinal microvasculature. Although ophthalmic science and clinical practice are now highly sophisticated at detecting indirect, secondary signs of vascular remodeling such as cotton wool spots that arise during the progression of retinal vascular diseases, methods for quantifying direct, primary vascular changes are not yet established. To help develop insightful analysis of retinal vascular remodeling for aerospace medicine, we will map and quantify by our innovative VESsel GENeration Analysis (VESGEN) software the remodeling status of retinal blood vessels in crew members before and after ISS missions, and in healthy human subjects before and after head-down tilt bed rest. For this proof-of-concept study, we hypothesize that pathophysiological remodeling of retinal blood vessels occurs in coordination with microgravity-induced fluid shifts prior to development of visual impairments. VESGEN analysis in previous research supported by the US National Institutes of Health identified surprising new opportunities to regenerate retinal vessels during early-stage progression of the visually impairing, potentially blinding disease, diabetic retinopathy.

  19. WISE-2005: adrenergic responses of women following 56-days, 6 degrees head-down bed rest with or without exercise countermeasures.

    PubMed

    Edgell, Heather; Zuj, Kathryn A; Greaves, Danielle K; Shoemaker, J Kevin; Custaud, Marc-Antoine; Kerbeci, Pascaline; Arbeille, Phillipe; Hughson, Richard L

    2007-12-01

    We tested the hypotheses that women completing 56 days, 6 degrees head-down bed-rest (HDBR) would have changes in sensitivity of cardiovascular responses to adrenergic receptor stimulation and that frequent aerobic and resistive exercise would prevent these changes. Twenty-four women, eight controls, eight exercisers (lower body negative pressure treadmill and flywheel resistance exercise), and eight receiving nutritional supplement but no exercise were studied in baseline and during administration of the beta-agonist isoproterenol (ISO) and the alpha- and beta-agonist norepinephrine (NOR). In the control and nutrition groups, HDBR increased heart rate (HR) and reduced stroke volume (SV), and there was a significantly greater increase in HR with ISO after HDBR. In contrast, the HR and SV of the exercise group were unchanged from pre-HDBR. After HDBR, leg vascular resistance (LVR) was greater than pre-HDBR in the exercise group but reduced in control and nutrition. LVR was reduced with ISO and increased with NOR. Changes in total peripheral resistance were similar to those of LVR but of smaller magnitude, perhaps because changes in cerebrovascular resistance index were directionally opposite to those of LVR. There were no changes in sensitivity of the vascular resistance responses to adrenergic stimulation. The HR response might reflect a change in sensitivity or a necessary response to the reduction in SV after HDBR in control and nutrition groups. The reduced peripheral vascular resistance after HDBR might help to explain orthostatic intolerance in women. Exercise was an effective countermeasure to the HDBR effects. PMID:17928515

  20. Effect of computerized cognitive training with virtual spatial navigation task during bed rest immobilization and recovery on vascular function: A pilot study

    PubMed Central

    Goswami, Nandu; Kavcic, Voyko; Marusic, Uros; Simunic, Bostjan; Rössler, Andreas; Hinghofer-Szalkay, Helmut; Pisot, Rado

    2015-01-01

    We investigated the effects of bed rest (BR) immobilization, with and without computerized cognitive training with virtual spatial navigation task (CCT), on vascular endothelium on older subjects. The effects of 14-day BR immobilization in healthy older males (n=16) of ages 53–65 years on endothelial function were studied using EndoPAT®, a noninvasive and user-independent method. From the group of 16 older men, 8 randomly received CCT during the BR, using virtual navigation tasks in a virtual environment with joystick device. In all the cases, EndoPAT assessments were done at pre- and post-BR immobilization as well as following 28 days of ambulatory recovery. The EndoPAT index increased from 1.53±0.09 (mean ± standard error of the mean) at baseline to 1.61±0.16 following immobilization (P=0.62) in the group with CCT. The EndoPAT index decreased from 2.06±0.13 (mean ± standard error of the mean) at baseline to 1.70±0.09 at the last day of BR study, day 14 (BR14) (P=0.09) in the control group. Additionally, there were no statistically significant differences between BR14 and at 28 days of follow-up (rehabilitation program) (R28). Our results show a trend of immobilization in older persons affecting the vasoconstrictory endothelial response. As the control subjects had a greater increase in EndoPAT index after R28 (+0.018) compared to subjects who had cognitive training (+0.11) (calculated from the first day of BR study), it is possible that cognitive training during BR does not improve endothelial function but rather contributes to slowing down the impairment of endothelial function. Finally, our results also show that EndoPAT may be a useful noninvasive tool to assess the vascular reactivity. PMID:25709419

  1. Effect of computerized cognitive training with virtual spatial navigation task during bed rest immobilization and recovery on vascular function: a pilot study.

    PubMed

    Goswami, Nandu; Kavcic, Voyko; Marusic, Uros; Simunic, Bostjan; Rössler, Andreas; Hinghofer-Szalkay, Helmut; Pisot, Rado

    2015-01-01

    We investigated the effects of bed rest (BR) immobilization, with and without computerized cognitive training with virtual spatial navigation task (CCT), on vascular endothelium on older subjects. The effects of 14-day BR immobilization in healthy older males (n=16) of ages 53-65 years on endothelial function were studied using EndoPAT(®), a noninvasive and user-independent method. From the group of 16 older men, 8 randomly received CCT during the BR, using virtual navigation tasks in a virtual environment with joystick device. In all the cases, EndoPAT assessments were done at pre- and post-BR immobilization as well as following 28 days of ambulatory recovery. The EndoPAT index increased from 1.53±0.09 (mean ± standard error of the mean) at baseline to 1.61±0.16 following immobilization (P=0.62) in the group with CCT. The EndoPAT index decreased from 2.06±0.13 (mean ± standard error of the mean) at baseline to 1.70±0.09 at the last day of BR study, day 14 (BR14) (P=0.09) in the control group. Additionally, there were no statistically significant differences between BR14 and at 28 days of follow-up (rehabilitation program) (R28). Our results show a trend of immobilization in older persons affecting the vasoconstrictory endothelial response. As the control subjects had a greater increase in EndoPAT index after R28 (+0.018) compared to subjects who had cognitive training (+0.11) (calculated from the first day of BR study), it is possible that cognitive training during BR does not improve endothelial function but rather contributes to slowing down the impairment of endothelial function. Finally, our results also show that EndoPAT may be a useful noninvasive tool to assess the vascular reactivity.

  2. Two-hour methyl isocyanate inhalation and 90-day recovery study in B6C3F1 mice

    SciTech Connect

    Boorman, G.A.; Uraih, L.C.; Gupta, B.N.; Bucher, J.R.

    1987-06-01

    B6C3F1 mice were exposed by inhalation to 0, 3, 10, and 30 ppm methyl isocyanate for 2 hr followed by a 90-day recovery period. Sixteen of eight (20%) male mice in the 30 ppm group died following exposure. There were no other unscheduled deaths in the mice. Five mice/sex/group were examined at 2 hr or at 1, 3, 7, 14, 28, 49, or 91 days following exposure. Chemical-related changes were restricted to the respiratory system. At 30 ppm there were extensive necrosis and erosion of the respiratory and olfactory epithelium in the nasal cavity. Severe necrosis and epithelial erosion were also found in the trachea and main bronchi. Regeneration of the mucosal epithelium occurred rapidly in the nasal cavity and airways. In the turbinates, mild incomplete olfactory epithelial regeneration persisted to day 91 in the male mice. Intraluminal fibrotic projections covered by respiratory epithelium and bronchial fibrosis were found in the major airways of the 30 ppm male and female mice by day 7. The intraluminal fibrosis persisted to day 91. In males with severe bronchial fibrosis, chronic alveolitis and atelectasis were found. In mice exposed to 3 or 10 ppm, persistent pulmonary changes were not found. These studies indicate that methyl isocyanate inhalation at or near lethal concentrations can cause persistent fibrosis of the major bronchi in mice.

  3. A 90-day subchronic feeding study of genetically modified rice expressing Cry1Ab protein in Sprague-Dawley rats.

    PubMed

    Song, Huan; He, Xiaoyun; Zou, Shiying; Zhang, Teng; Luo, Yunbo; Huang, Kunlun; Zhu, Zhen; Xu, Wentao

    2015-04-01

    Bacillus thuringiensis (Bt) transgenic rice line (mfb-MH86) expressing a synthetic cry1Ab gene can be protected against feeding damage from Lepidopteran insects, including Sesamia inferens, Chilo suppressalis, Tryporyza incertulas and Cnaphalocrocis medinalis. Rice flour from mfb-MH86 and its near-isogenic control MH86 was separately formulated into rodent diets at concentrations of 17.5, 35 and 70 % (w/w) for a 90-day feeding test with rats, and all of the diets were nutritionally balanced. In this study, the responses of rats fed diets containing mfb-MH86 were compared to those of rats fed flour from MH86. Overall health, body weight and food consumption were comparable between groups fed diets containing mfb-MH86 and MH86. Blood samples were collected prior to sacrifice and a few significant differences (p < 0.05) were observed in haematological and biochemical parameters between rats fed genetically modified (GM) and non-GM diets. However, the values of these parameters were within the normal ranges of values for rats of this age and sex, thus not considered treatment related. In addition, upon sacrifice a large number of organs were weighed, macroscopic and histopathological examinations were performed with only minor changes to report. In conclusion, these results demonstrated that no toxic effect was observed in the conditions of the experiment, based on the different parameters assessed. GM rice mfb-MH86 is as safe and nutritious as non-GM rice.

  4. Results of a 90-day safety assurance study with rats fed grain from corn rootworm-protected corn.

    PubMed

    Hammond, B; Lemen, J; Dudek, R; Ward, D; Jiang, C; Nemeth, M; Burns, J

    2006-02-01

    The results of a 90-day rat feeding study with YieldGard (YieldGard Rootworm Corn is a registered trademark of Monsanto Technology, LLC.) Rootworm corn (MON 863) grain that is protected against feeding damage caused by corn rootworm larvae are presented. Corn rootworm-protection was accomplished through the introduction of a cry3Bb1 coding sequence into the corn genome for in planta production of a modified Cry3Bb1 protein from Bacillus thuringiensis. Grain from MON 863 and its near isogenic control were separately formulated into rodent diets at levels of 11% and 33% (w/w) by Purina Mills, Inc. Additionally, six groups of rats were fed diets containing grain from different conventional (non-biotechnology-derived) reference varieties. The responses of rats fed diets containing MON 863 were compared to those of rats fed grain from conventional corn varieties. All diets were nutritionally balanced and conformed to Purina Mills, Inc. specifications for Certified LabDiet 5002. There were a total of 400 rats in the study divided into 10 groups of 20 rats/sex/group. Overall health, body weight gain, food consumption, clinical pathology parameters (hematology, blood chemistry, urinalysis), organ weights, gross and microscopic appearance of tissues were comparable between groups fed diets containing MON 863 and conventional corn varieties. This study complements extensive agronomic, compositional and farm animal feeding studies with MON 863 grain, confirming that it is as safe and nutritious as existing conventional corn varieties.

  5. A 90-day toxicology study of high-amylose transgenic rice grain in Sprague-Dawley rats.

    PubMed

    Zhou, Xing Hua; Dong, Ying; Xiao, Xiang; Wang, Yun; Xu, Yong; Xu, Bin; Shi, Wei Dong; Zhang, Yi; Zhu, Li Jia; Liu, Qiao Quan

    2011-12-01

    A transgenic rice line (TRS) with high amylose level has been developed by antisense RNA inhibition of starch branching enzymes. Compositional analysis of TRS demonstrated that the content of resistant starch (RS) was significantly higher compared to conventional non-transgenic rice. High level of RS is an important raw material in food industry and has various physiological effects for human health. In order to provide the reliable theory basis for field release of TRS rice, we evaluated the potential health effects of long-term consumption of the TRS. The 90-day toxicology feeding experiment was conducted in Sprague-Dawley rats fed with diets containing 70% of either TRS rice flour, its near-isogenic rice flour or the control diet. The clinical performance variables (body weight, body weight gain and food consumption) were measured and pathological responses (hematological parameters and serum chemistry at the midterm and the completion of the experiment, urinalysis profile and serum sex hormone response at the completion of the experiment) were performed. Besides, clinical signs, relative organ weights and microscopic observations were also compared between TRS group and its near-isogenic rice group. The combined data indicates that high-amylose TRS grain is as safe as the conventional non-transgenic rice for rat consumption.

  6. A 90-day toxicology study of transgenic lysine-rich maize grain (Y642) in Sprague-Dawley rats.

    PubMed

    He, Xiao Yun; Tang, Mao Zhi; Luo, Yun Bo; Li, Xin; Cao, Si Shuo; Yu, Jing Juan; Delaney, Bryan; Huang, Kun Lun

    2009-02-01

    The gene for a lysine-rich protein (sb401) obtained from potatoes (Solanum berthaultii) was inserted into maize seed to produce Y642 transgenic maize. Compositional analysis of Y642 grain demonstrated that the concentrations of lysine and total protein were higher than those observed in maize grain from a near-isogenic non-genetically modified (non-GM) commercially available control quality protein maize (Nongda 108). The safety of Y642 maize grain was assessed by comparison of toxicology response variables in Sprague-Dawley (SD) rats consuming diets containing Y642 maize grain with those containing Nongda 108 maize grain. Maize grains from Y642 or Nongda 108 were incorporated into rodent diets at low (30%) or high concentrations (76%) and administered to SD rats (n=10/sex/group) for 90 days. An additional group of negative control group of rats (n=10/sex/group) were fed AIN93G diets. No adverse diet-related differences in body weights, feed consumption/utilization, clinical chemistry, hematology, absolute and relative organ weights were observed. Further, no differences in gross or microscopic pathology were observed between rats consuming diets with Y642 maize grain compared with rats consuming diets containing Nongda 108 maize grain. These results demonstrated that Y642 lysine-rich maize is as safe and nutritious as conventional quality protein maize.

  7. Results of a 90-day safety assurance study with rats fed grain from corn borer-protected corn.

    PubMed

    Hammond, B G; Dudek, R; Lemen, J K; Nemeth, M A

    2006-07-01

    The results of a 90-day rat feeding study with grain from MON 810 corn (YieldGard Cornborer -- YieldGard Cornborer is a registered trademark of Monsanto Technology, LLC) that is protected against feeding damage from corn and stalk boring lepidopteran insects are presented. Corn borer protection was accomplished through the introduction of cry1Ab coding sequences into the corn genome for in planta production of a bioactive form of Cry1Ab protein. Grain from MON 810 and its near-isogenic control was separately formulated into rodent diets at levels of 11% and 33% (w/w) by Purina Mills, Inc. (PMI). All diets were nutritionally balanced and conformed to PMI specifications for Certified LabDiet (PMI Certified LabDiet 5002 is a registered trademark of Purina Mills, Inc.) 5002. There were a total of 400 rats in the study divided into 10 groups of 20 rats/sex/group. The responses of rats fed diets containing MON 810 were compared to those of rats fed grain from conventional corn varieties. Overall health, body weight, food consumption, clinical pathology parameters (hematology, blood chemistry, urinalysis), organ weights, and gross and microscopic appearance of tissues were comparable between groups fed diets containing MON 810 and conventional corn varieties. This study complements extensive agronomic, compositional and farm animal feeding studies with MON 810 grain, confirming that it is as safe and nutritious as grain from existing commercial corn varieties.

  8. Fluid overload is associated with an increased risk for 90-day mortality in critically ill patients with renal replacement therapy: data from the prospective FINNAKI study

    PubMed Central

    2012-01-01

    Introduction Positive fluid balance has been associated with an increased risk for mortality in critically ill patients with acute kidney injury with or without renal replacement therapy (RRT). Data on