Long-term Bed Rest Research Articles

Rapidly assessing changes in bone mineral balance using natural stable calcium isotopes

The ability to rapidly detect changes in bone mineral balance (BMB) would be of great value in the early diagnosis and evaluation of therapies for metabolic bone diseases such as osteoporosis and some cancers. However, measurements of BMB are hampered by difficulties with using biochemical markers to quantify the relative rates of bone resorption and formation and the need to wait months to years for altered BMB to produce changes in bone mineral density large enough to resolve by X-ray densitometry. We show here that, in humans, the natural abundances of Ca isotopes in urine change rapidly in response to changes in BMB. In a bed rest experiment, use of high-precision isotope ratio MS allowed the onset of bone loss to be detected in Ca isotope data after about 1 wk, long before bone mineral density has changed enough to be detectable with densitometry. The physiological basis of the relationship between Ca isotopes and BMB is sufficiently understood to allow quantitative translation of changes in Ca isotope abundances to changes in bone mineral density using a simple model. The rate of change of bone mineral density inferred from Ca isotopes is consistent with the rate observed by densitometry in long-term bed rest studies. Ca isotopic analysis provides a powerful way to monitor bone loss, potentially making it possible to diagnose metabolic bone disease and track the impact of treatments more effectively than is currently possible.

Passive stretch reduces calpain activity through nitric oxide pathway in unloaded soleus muscles

Unloading in spaceflight or long-term bed rest induces to pronounced atrophy of anti-gravity skeletal muscles. Passive stretch partially resists unloading-induced atrophy of skeletal muscle, but the mechanism remains elusive. The aims of this study were to investigate the hypotheses that stretch tension might increase protein level of neuronal nitric oxide synthase (nNOS) in unloaded skeletal muscle, and then nNOS-derived NO alleviated atrophy of skeletal muscle by inhibiting calpain activity. The tail-suspended rats were used to unload rat hindlimbs for 2 weeks, at the same time, left soleus muscle was stretched by applying a plaster cast to fix the ankle at 35° dorsiflexion. Stretch partially resisted atrophy and inhibited the decreased protein level and activity of nNOS in unloaded soleus muscles. Unloading increased frequency of calcium sparks and elevated intracellular resting and caffeine-induced Ca(2+) concentration ([Ca(2+)]i) in unloaded soleus muscle fibers. Stretch reduced frequency of calcium sparks and restored intracellular resting and caffeine-induced Ca(2+) concentration to control levels in unloaded soleus muscle fibers. The increased protein level and activity of calpain as well as the higher degradation of desmin induced by unloading were inhibited by stretch in soleus muscles. In conclusion, these results suggest that stretch can preserve the stability of sarcoplasmic reticulum Ca(2+) release channels which prevents the elevated [Ca(2+)]i by means of keeping nNOS activity, and then the enhanced protein level and activity of calpain return to control levels in unloaded soleus muscles. Therefore, stretch can resist in part atrophy of unloaded soleus muscles.

New therapy using bisphosphonate for urolithiasis

Osteoporosis is characterized by a reduction in bone mineral density (BMD) . Reduced BMD has been reported in urolithiasis patients with hypercalciuria, as well as in those with normocalciuria. Bisphosphonates potently inhibit bone resorption and are used in the management of osteoporosis. We show the ability of bisphosphonate to prevent the recurrence of urolithiasis. Bisphosphonate reduced the excretion of urinary calcium and the ion activity product index of calcium phosphate in urolithiasis patients, and prevented urinary stone formation in long-term bed rest test. The results suggest that ALN not only improves osteoporosis but also reduces the risk of calcium stone formation. Bisphosponates are believed to reduce the urinary excretion of calcium by improvement of bone metabolism, and to have a direct effect in the prevention of urolithiasis.

One Size Does Not Fit All: Using Research to Improve the Postpartum Care of Women on Long-Term Antepartum Bed Rest

Despite a lack of proven efficacy, bed rest continues to be prescribed for patients with complications of pregnancy. Physical, psychological, and social sequelae of bed rest on the high-risk antepartum patient have been documented. A recent qualitative study provided insight into the postpartum experiences and the physical and psychological needs of this population. The purpose of this program was to empower nurses to take an active role in a cultural change to optimize postpartum care for women on long-term antepartum bed rest based on research.

NIRS-Derived Tissue Oxygen Saturation and Hydrogen Ion Concentration following Bed Rest

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 erogmeter 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. Taken together, these data suggest that longer duration BR induces a number of changes that result in peripheral adaptations which contribute to cardiovascular and muscular deconditioning as measured by NIRS-derived SO2 and [H+] in the VL and may contribute to lower post-BR exercise tolerance. Supported by the National Space Biomedical Research Institute through NASA NCC 9-58

Analysis on the related factors and nursing of the lower extremity deep-venous thrombosis in operated patients with cerebral hemorrhage

Objective To explore the relevant factors to the lower extremity deep-venous thrombosis in patients with cerebral hemorrhage after operation. Methods Patients with cerebral hemorrhage in our department were surveyed. The incidence of lower extremity deep-venous thrombosis and its related factors were analyzed. Results The incidence rate of deep-venous thrombosis in the operated patients with cerebral hemorrhage is 20.35%;through logistic regression analysis, five factors related with lower extremity deepvenous thrombosis were found;they were old age, diabetes, mannitol, femoral vein catheter, paralysis of limbs.The highest occurrence rate of lower extremity deep-venous thrombosis is the left lower limb. Conclusions Old age, long-term bed rest, hypercoagulable state with cerebral hemorrhage should be given early limb function training in clinical response;applying the necessary anticoagulant drugs to prevent deep-venous thrombosis occurred. Key words: Deep-venous thrombosis; Cerebral hemorrhage; Related factors; Nursing

Enhanced physiological tremor deteriorates plantar flexor torque steadiness after bed rest

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 20 Hz 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.

Sympathetic neural influence on bone metabolism in microgravity (Review)

Bone loss is one of the most important complications for astronauts who are exposed to long-term microgravity in space and also for bedridden elderly people. Recent studies have indicated that the sympathetic nervous system plays a role in bone metabolism. This paper reviews findings concerning with sympathetic influences on bone metabolism to hypothesize the mechanism how sympathetic neural functions are related to bone loss in microgravity. Animal studies have suggested that leptin stimulates hypothalamus increasing sympathetic outflow to bone and enhances bone resorption through noradrenaline and β-adrenoreceptors in bone. In humans, even though there have been some controversial findings, use of β-adrenoblockers has been reported to be beneficial for prevention of osteoporosis and bone fracture. On the other hand, microneurographically-recorded sympathetic nerve activity was enhanced by exposure to microgravity in space as well as dry immersion or long-term bed rest to simulate microgravity. The same sympathetic activity became higher in elderly people whose bone mass becomes generally reduced. Our recent findings indicated a significant correlation between muscle sympathetic nerve activity and urinary deoxypyridinoline as a specific marker measuring bone resorption. Based on these findings we would like to propose a following hypothesis concerning the sympathetic involvement in the mechanism of bone loss in microgravity: An exposure to prolonged microgravity may enhance sympathetic neural traffic not only to muscle but also to bone. This sympathetic enhancement increases plasma noradrenaline level and inhibits osteogenesis and facilitates bone resorption through β-adrenoreceptors in bone to facilitate bone resorption to reduce bone mass. The use of β-adrenoblockers to prevent bone loss in microgravity may be reasonable.

The “Wini, Wally, and Wanda” Program for the Hospitalized Antepartum Woman

Long-term bed rest is a recommended option for 700,000 women with high-risk pregnancies. Because we work at a regional tertiary hospital, we frequently provide care for two or three of these long-term patients at any one time. Nursing diagnosis for these patients includes possible fetal injury due to pregnancy complications and possible skin and hematologic complications from prolonged inactivity. These patients are also far more susceptible to mood disorders (Brandon et al., 2008). Several studies have recorded that pregnancy stress, antenatal depression, and postnatal depression are interrelated (Austin, Tully, & Parker, 2007; Lee et al., 2007).

Exploration of the Postpartum Experience of Women on Long-Term Bed Rest for Pregnancy Complications

Exploration of the Postpartum Experience of Women on Long-Term Bed Rest for Pregnancy Complications

Plasma 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol concentrations are decreased in hind limb unloaded Dahl salt-sensitive female rats

Plasma 1,25-dihydroxyvitamin D (1,25-(OH) 2D) concentration was shown to decrease during bed rest in several studies when baseline plasma 25-hydroxyvitamin D (25-OHD) concentration was sub-optimal. Dahl salt-sensitive female (S) rats, but not Dahl salt-resistant female (R) rats, demonstrated a 50% decrease in plasma 1,25-dihydroxycholecalciferol (1,25-(OH) 2D 3) concentration after 28 days of hind limb unloading (HU, disuse model) during low salt intake (0.3%). We tested the vitamin D endocrine system response of female S rats to hind limb unloading during high salt intake (2%, twice that of standard rat chow to mimic salt intake in the USA). Hind limb unloading resulted in lower plasma 25-OHD 3 concentrations in S-HU rats than in R-HU rats ( P < 0.05) and greater urinary loss of 25-OHD 3 by S-HU rats than by S rats ( P < 0.05). Plasma 1,25-(OH) 2D 3 concentration of S-HU rats was half that of S rats, but was unchanged in R-HU rats. The association of low plasma 25-OHD concentration with decrease in plasma 1,25-(OH) 2D concentration of hind limb unloaded rats and of bed rest participants (published studies) suggests that low vitamin D status might be a risk factor for decrease in plasma vitamin D hormone concentration during long-term immobilization or bed rest.

Stress and recovery assessment during simulated microgravity: Effects of exercise during a long-term head-down tilt bed rest in women

The aim of this study was to determine the effects of a 60-day head-down tilt long-term bed rest (HDT) on stress and recovery in sixteen healthy female volunteers. Participants were randomly assigned to either an exercise group (Exe) that followed a training program combining resistive and aerobic exercises, or to a no-exercise control group (Ctl). Psychological states were assessed using the Rest-Q, a validated questionnaire based on stress–recovery responses. A longitudinal analysis revealed significant changes in the general and specific-stress scales for all participants throughout the experiment with a critical stage from supine to standing posture leading to a significant decrease in physical recovery. During HDT, Exe reported higher scores on stress subscales, as well as lower recovery scores compared to the Ctl. During the post-HDT ambulatory recovery period, the exercisers still reported higher scores than the non-exercisers on the Lack of energy stress-related scale, along with lower scores in general well-being and personal accomplishment. The present findings show that simulated weightlessness such as HDT may induce psychological stress and lead to subsequent alterations in perceived recovery. Exercise did not reduce HDT impaired effects on stress and recovery states. Several suggestions, including psychological preparation, are proposed to support the beneficial effects of exercise on psychological factors.

Personality, social support and affective states during simulated microgravity in healthy women

This study investigated the time-course of stress and recovery states and their relations to social support and personality traits in healthy women during a long-term head-down tilt bed rest. Personality, social support and affective states were assessed in 16 women exposed to simulated microgravity for a 60-day duration involving three stages: a 20-day baseline control period (BDC), a 60-day head-down tilt bed rest (HDT) and a 20-day post-HDT ambulatory recovery period (R+). Participants were divided into two groups: an exercise (Exe, n = 8) and a control group (Ctl, n = 8). All the participants experienced significantly more stress during the HDT period. But exercise did not improve the impaired effects of simulated microgravity. The Exe group perceived more stress and less recovery than the Ctl group during the HDT period. Among the five major personality factors, only Neuroticism was related to both social and affective variables. Neuroticism was positively associated with stress and negatively associated with recovery and social support (S-SSQ). Practical implications in psychological countermeasures for better dealing with the key human factor in spaceflights are discussed.

Large-scale mRNA analysis of female skeletal muscles during 60 days of bed rest with and without exercise or dietary protein supplementation as countermeasures

Microgravity has a dramatic impact on human physiology, illustrated in particular, with skeletal muscle impairment. A thorough understanding of the mechanisms leading to loss of muscle mass and structural disorders is necessary for defining efficient clinical and spaceflight countermeasures. We investigated the effects of long-term bed rest on the transcriptome of soleus (SOL) and vastus lateralis (VL) muscles in healthy women (BRC group, n = 8), and the potential beneficial impact of protein supplementation (BRN group, n = 8) and of a combined resistance and aerobic training (BRE group, n = 8). Gene expression profiles were obtained using a customized microarray containing 6,681 muscles-relevant genes. A two-class statistical analysis was applied on 2,103 genes with consolidated expression in BRC, BRN, and BRE groups. We identified 472 and 207 mRNAs whose expression was modified in SOL and VL from BRC group, respectively. Further clustering analysis, identifying relevant biological mechanisms and pathways, reported five main subclusters. Three are composed of upregulated mRNAs involved mainly in nucleic acid and protein metabolism, and two made up of downregulated transcripts encoding components involved in energy metabolism. Exercise countermeasure demonstrated drastic compensatory effects, decreasing the number of differentially expressed mRNAs by 89 and 96% in SOL and VL, respectively. In contrast, nutrition countermeasure had moderate effects and decreased the number of differentially-expressed transcripts by 40 and 25% in SOL and VL. Together, these data present a systematic, global and comprehensive view of the adaptive response of female muscle to long-term atrophy.

The efficacy of percutaneous vertebroplasty for palliation of pain in vertebral metastases associated with solid malignancies

e20670 Background: Painful vertebral metastases are a debilitating and common complication of a number of solid malignancies. Percutaneous vertebroplasty appears beneficial for patients with acute compression fractures of multiple aetiologies including myeloma, and osteoporosis. There are few reports on its use in the setting of metastatic solid malignancy. Methods: We identified all individuals who had undergone percutaneous vertebroplasty at our institution since 2004 and focused on those with metastatic solid malignancies. Their clinical characteristics and outcomes were investigated. Results: From 136 cases that underwent percutaneous vertebroplasties, 19 were performed mainly in breast, prostate, lung, and renal cancers. Of these 19 cases, ten patients (53%) were treated for solitary lesions, 3 (16%) were injected at two levels and the remaining 6 cases (31%) underwent cement injection at three levels. The majority of patients (84%) reported short (within 48 hours) and longer term symptomatic improvements. At a median follow up of one year, 6 patients have died. Conclusions: This study illustrates that percutaneous vertebroplasty can be a safe and beneficial palliative procedure for patients with pain related to metastatic vertebral disease. Up to three vertebral levels maybe injected at one sitting with good results. Its use can be successfully combined with other treatment modalities (radiotherapy and chemotherapy). For optimal results its use before radiotherapy has been recommended. Although it does not improve the survival outcome, palliation is a reasonable goal when life expectancy is short. Cost benefits from this procedure will come from reduced analgesic requirements and avoided complications of long-term bed rest, with significant potential savings from reduced in-patient admissions for pain control, home care costs, community nursing, and out-of ours access to clinical services. No significant financial relationships to disclose.

Quantification of Muscle Volume by Echography: Comparison with MRI Data on Subjects in Long-Term Bed Rest

The objective of this study was to determine the accuracy of an echographic method for measuring the change in leg muscle volume against the gold standard, magnetic resonance imaging (MRI). Leg muscle volume was measured using an echographic scanner, which consisted of two metallic rails on which a probe holder moved via an electric engine. Ten to 20 transverse muscle views were collected along the area scanned, and the muscle cross-sectional area (CSA, cm 2) was measured on each of them. The integration of all the CSAs along the scanned area provided the muscle volume (cm 3). Echographic results were compared with MRI data on 24 subjects undergoing 60 d of bed rest (8 control “Con,” 8 with exercise countermeasures “Ex” and 8 with nutrition countermeasures “Nut”). The vastus intermedius (VI) and the vastus medialis (VM) volumes decreased significantly and similarly in both Con and Nut (VI, –17%; VM, –21%; p < 0.02). In the Ex group, the VI and VM did not change significantly. The correlation coefficient between the muscle volume change measured with the echographic and MRI methods was 0.78. The present study confirms that the echographic scanner is sufficiently accurate for assessing muscle volume changes and detects the effect of exercise countermeasures on muscle volume during long-term bed rest. (E-mail: arbeille@med.univ-tours.fr)

Does antioxidant system adaptive response alleviate related oxidative damage with long term bed rest?

Objectives The aim of the study was to evidence oxidative damage and erythrocyte antioxidant enzyme activities during long term bed rest (LTBR) and recovery, while verifying the prophylactic effects of resistance exercise on LTBR-induced oxidative damage. Design and methods 11 healthy male participated in the study. Nutrient intakes were monitored. Assessments occurred during LTBR (60th and 90th day) and 90 days after the end. Results LTBR induced only a slight decrease in total thiol protein (SH) group concentrations. Glutathione peroxidase (GPx) activity was upregulated during LTBR and down regulated after recovery suggesting that hypokinesia induces an oxidative stress. These effects where not correlated to antioxidant intake as nutritional density is preserved. Lipoperoxidative markers stay unchanged . Conclusions Exercise alleviates hypokinesia outcomes by preserving glutathione reductase activity with minor effect on hypokinesia-induced antioxidant response and oxidative stress which both exhibit a high magnitude inter-individual variability. Return to initial physical activity allows biomarkers to return to initial values marking the end of the stress. Hypokinetic situations should be considered as an oxidative stressful situation requiring exercise and nutritional strategies.

A Case of Fissure-Like Pressure Ulcer on the Coccygeal Area Successfully Treated with Changing of Wound Dressing

A 61-year-old Japanese woman developed pressure ulcer on her sacral and coccygeal area due to a long-term bed rest. After she received the treatment by bucladesine sodium ointment, trafermin (recombinant human basic FGF) splay and TIELLE® (Johnson&Johnson Co) hydropolymer dressing, the ulcer gradually reduced in size and depth. However, the improvement of the fissure-like ulcer decelerated when the size became around 2X2cm. Thereafter the occlusion by hydrocolloid dressing was continued for around two years with only slight effect, decreasing the size to around 1X1cm. Finally, we changed the dressing to the hydropolymer dressing TIELLE® plus, which can absorb superfluous oozing well, because maceration was found on the perilesional skin. Then, the ulcer was rapidly healed and epithelized in two weeks, suggesting that the excess secretion had delayed of wound healing.

The effect of bed rest and an exercise countermeasure on leg venous function

This study was performed to assess the effect of resistive vibration exercise during bed rest deconditioning on venous vascular dimension and function, as measured with ultrasound in the popliteal vein. Sixteen men were assigned to bed rest (BR-Ctrl) or bed rest with resistive vibration exercise (BR-RVE). Before and at 25 and 52 days of bed rest, popliteal vein diameter was measured at increasing cuff pressures. Venous capacitance and compliance were calculated from the pressure-volume curve. After 52 days of bed rest, BR-Ctrl showed no change in baseline popliteal vein diameter or compliance, while venous capacitance decreased. Resistive vibration exercise had no effect on the response in venous diameter, capacitance or compliance to 52 days of bed rest. The decline in venous capacitance due to long-term bed rest is not effectively counteracted by resistive vibration exercise, indicating that an alternative factor during bed rest deconditioning is responsible for venous changes.

Clinical analysis of pulmonary tuberculosis with candida albicans infection in 86 cases

Objective To analyze the merger candida albicans pulmonary tuberculosis irfection risk factors, clinical characteristics,treatment and prognosis,ways of improving the coexistence of the two diseases in the early di-agnosis and treatment methods. Methods 86 cases with pulmonary tuberculosis combined candida albicans infection were analyzed. Results Pulmonary lung infection candida albicans no specific clinical manifestations, in addition to X-ray signs of tuberculosis,mainly for the merger under the shadow of lung flake fuzzy; prediction for risk factors: long-term use of broad-spectrum antibiotics, the multi-antibiotics, glucocorticoid or immunosuppreasanta, long-term bed rest, physical weakness, the length of hospitalization, chronic bronchitis and obstructive pulmonary disease (COPD), respiratory failure, mechanical ventilation, diabetes, hypoproteinemia, blood diseases, multiple organ failure,mechanical ventilation,and other invasive operation is closely related to a higher mortality rate of pulmonary fungal infections. Conclusion Active tuberculosis disease and therapy to reduce risk factors, prevention and early diagnosis of good,reasonable use of antibiotics,hormones,and so un,the key is to improve the cure rate. Key words: Tuberculosis, pulmonary; Candida albicans; Infection