Long-term Bed Rest Research Articles

Effect of 5-day dry immersion on the human foot morphology evaluated by computer plantography and soft tissues stiffness measuring

16 participants have been subjected to Dry Immersion model (DI) for 5 days. DI reproduces the space flight factors such as lack of support, mechanical and axial unloading, physical inactivity, elimination of vertical vascular gradient. Long-term bed rest is also associated with similar factors, so the results of the study may be useful for clinical medicine. Computer plantography and measuring the stiffness of the soft tissues of the foot and superficial muscles of the shin (mm. tibialis anterior and peroneus longus) were performed twice before DI exposure, on the 2nd and 4th days of DI exposure, as well as on the 2nd day of the recovery period. DI exposure effects the parameters under study in two ways: by raising the longitudinal arch and by flattening the transverse arch, which is accompanied by a decrease in the soft tissues stiffness of the foot and superficial muscles of the shin. The work reveals the phenomenon of compensating the longitudinal arch state by changing the characteristics that reflect the transverse arch state. The results of the study for the first time demonstrate the correlation of the foot morphological characteristics with a decrease in stiffness of mm. peroneus longus and tibialis anterior.

Nonuniform loss of muscle strength and atrophy during bed rest: a systematic review.

Muscle atrophy and decline in muscle strength appear very rapidly with prolonged disuse or mechanical unloading after acute hospitalization or experimental bed rest. The current study analyzed data from short-, medium-, and long-term bed rest (5-120 days) in a pooled sample of 318 healthy adults and modeled the mathematical relationship between muscle strength decline and atrophy. The results show a logarithmic disuse-induced loss of strength and muscle atrophy of the weight-bearing knee extensor muscles. The greatest rate of muscle strength decline and atrophy occurred in the earliest stages of bed rest, plateauing later, and likely contributed to the rapid neuromuscular loss of function in the early period. In addition, during the first 2 wk of bed rest, muscle strength decline is much faster than muscle atrophy: on day 5, the ratio of muscle atrophy to strength decline as a function of bed rest duration is 4.2, falls to 2.4 on day 14, and stabilizes to a value of 1.9 after ∼35 days of bed rest. Positive regression revealed that ∼79% of the muscle strength loss may be explained by muscle atrophy, while the remaining is most likely due to alterations in single fiber mechanical properties, excitation-contraction coupling, fiber architecture, tendon stiffness, muscle denervation, neuromuscular junction damage, and supraspinal changes. Future studies should focus on neural factors as well as muscular factors independent of atrophy (single fiber excitability and mechanical properties, architectural factors) and on the role of extracellular matrix changes. Bed rest results in nonuniform loss of isometric muscle strength and atrophy over time, where the magnitude of change was greater for muscle strength than for atrophy. Future research should focus on the loss of muscle function and the underlying mechanisms, which will aid in the development of countermeasures to mitigate or prevent the decline in neuromuscular efficiency.NEW & NOTEWORTHY Our study contributes to the characterization of muscle loss and weakness processes reflected by a logarithmic decline in muscle strength induced by chronic bed rest. Acute short-term hospitalization (≤5 days) associated with periods of disuse/immobilization/prolonged time in the supine position in the hospital bed is sufficient to significantly decrease muscle mass and size and induce functional changes related to weakness in maximal muscle strength. By bringing together integrated evaluation of muscle structure and function, this work identifies that 79% of the loss in muscle strength can be explained by muscle atrophy, leaving 21% of the functional loss unexplained. The outcomes of this study should be considered in the development of daily countermeasures for preserving neuromuscular integrity as well as preconditioning interventions to be implemented before clinical bed rest or chronic gravitational unloading (e.g., spaceflights).

Effects of ultrasound, radial extracorporeal shock waves, and electrical stimulation on rat bone defect healing.

Fractures associated with osteoporosis are a major public health concern. Current treatments for fractures are limited to surgery or fixation, leading to long-term bedrest, which is linked to increased mortality. Alternatively, utilization of physical agents has been suggested as a promising therapeutic approach for fractures. Here, we examined the effects of ultrasound, radial extracorporeal shock waves, and electrical stimulation on normal or osteoporotic fracture healing. Femoral bone defects were created in normal or ovariectomized rats. Rats were divided into four groups: untreated, and treated with ultrasound, shock waves, or electrical stimulation after surgery. Samples were collected at 2 or 4 weeks after surgery, and the healing process was evaluated with micro-CT, histological, and immunohistochemical analyses. Ultrasound at intensities of 0.5 and 1.0 W/cm2 , but not 0.05 W/cm2 , accelerated new bone formation. Shock wave exposure also increased newly formed bone, but formed abnormal periosteal callus around the defect site. Conversely, electrical stimulation did not affect the healing process. Ultrasound exposure increased osteoblast activity and cell proliferation and decreased sclerostin-positive osteocytes. We demonstrated that higher-intensity ultrasound and radial extracorporeal shock waves accelerate fracture healing, but shock wave treatment may increase the risk of periosteal callus formation.

The Role of Long-Term Head-Down Bed Rest in Understanding Inter-Individual Variation in Response to the Spaceflight Environment: A Perspective Review.

Exposure to the spaceflight environment results in profound multi-system physiological adaptations in which there appears to be substantial inter-individual variability (IV) between crewmembers. However, performance of countermeasure exercise renders it impossible to separate the effects of the spaceflight environment alone from those associated with exercise, whilst differences in exercise programs, spaceflight operations constraints, and environmental factors further complicate the interpretation of IV. In contrast, long-term head-down bed rest (HDBR) studies isolate (by means of a control group) the effects of mechanical unloading from those associated with countermeasures and control many of the factors that may contribute to IV. In this perspective, we review the available evidence of IV in response to the spaceflight environment and discuss factors that complicate its interpretation. We present individual data from two 60-d HDBR studies that demonstrate that, despite the highly standardized experimental conditions, marked quantitative differences still exist in the response of the cardiorespiratory and musculoskeletal systems between individuals. We also discuss the statistical concept of “true” and “false” individual differences and its potential application to HDBR data. We contend that it is currently not possible to evaluate IV in response to the spaceflight environment and countermeasure exercise. However, with highly standardized experimental conditions and the presence of a control group, HDBR is suitable for the investigation of IV in the physiological responses to gravitational unloading and countermeasures. Such investigations may provide valuable insights into the potential role of IV in adaptations to the spaceflight environment and the effectiveness of current and future countermeasures.

Regular exercise counteracts circadian shifts in core body temperature during long-duration bed rest

With NASA’s plans for the human exploration of Mars, astronauts will be exposed to mission durations much longer than current spaceflight missions on the International Space Station. These mission durations will increase the risk for circadian misalignment. Exercise has gained increasing interest as a non-pharmacological aid to entrain the circadian system. To assess the potential of exercise as a countermeasure to mitigate the risk for circadian disorders during spaceflight, we investigated the effects of long-term head-down tilt bed rest (HDBR) with and without exercise on the circadian rhythm of core body temperature. Core body temperature was recorded for 24 h using a rectal probe in sixteen healthy men (age: 30.5 ± 7.5 years (mean ± SD)) after 7 days and 49 days of HDBR. Five participants underwent HDBR only (CTR), five participants underwent HDBR and performed resistive exercises (RE), and six participants underwent HDBR and performed resistive exercises superimposed with vibrations (RVE). The exercise was scheduled three times per week. CTR showed a phase delay of 0.69 h. In contrast, both exercise groups were characterized by a phase advance (0.45 h for RE and 0.45 h for RVE; p = 0.026 for interaction between time and group). These findings suggest that resistive exercise (with or without vibration) may also serve as a countermeasure during spaceflight to mitigate circadian misalignments. The results could also be important for increasing awareness about the role of circadian disorders in long-term bedridden patients.

Spring-loaded body mass equivalent horizontal reactive countermovement jump ground contact and flight times, but not peak forces, are comparable to vertical jumping

Horizontal (cylinder-based) sledge jumping has been shown to ameliorate multi-system deconditioning induced by long-term bed-rest. However, biomechanics differ from 1 g vertical jumping, in particular prolongation of ground contact times (GCT), reduction of peak force, rate of force development (RFD) (and presumably stretch shortening cycle [SSC] efficacy) and stiffness, whilst also requiring relatively complex equipment. Thus, we sought to determine if horizontal spring-loaded countermovement jumps were more analogous to vertical jumping.9 healthy (5 female) subjects (27 ± 7yrs; 169.0 ± 5.3 cm; 63.6 ± 2.6 kg) performed 10 reactive countermovement jumps vertically, and horizontally (randomized) when lay on a spring-loaded carriage performed against loading (at lift-off) equivalent (±6%) to their body weight. Jump kinetics, kinematics and lower limb/trunk electromyographic activity were compared between conditions (paired t-tests).Mean flight and GCTs did not differ, however, peak jump height (p = 0.003; d = −0.961) was greater when jumping horizontally. In contrast, ground reaction forces (zGRF) during take-off (p < 0.001; d = 1.645) and landing (p = 0.002; d = 1.309), peak acceleration (p = 0.001; d = 1.988), leg stiffness (p = 0.001; d = 2.371) and RFD (p = 0.023; d = 1.255) were lower horizontally. Mean rectus femoris activity was lower during landing (p = 0.033; d = 0.691) when horizontal, but did not differ during either take-off or land-lift. Mean medial gastrocnemius activity was significantly (p = 0.018; d = 0.317) lower during horizontal take-off.Spring-loading (1 g at take-off) maintained short GCTs and flight times presumably maintaining muscle SSC efficacy in a manner that appears intuitive (in young active subjects), simple, robust and potentially compatible with spaceflight. Whether appropriate jump characteristics can be achieved in older subjects and in μg/hypogravity needs to be determined. However, greater jump height, lower peak zGRF, RFD and leg stiffness along with reduced lower limb and trunk muscle activity suggests that 1 g at take-off is insufficient to replicate vertical jump biomechanics. Thus, further investigation is warranted to optimize, and evaluate spring-loaded jumping as a gravity-independent multi-systems countermeasure on Earth, and in Space.

Central pontine myelinolysis during treatment of hyperglycemic hyperosmolar syndrome: a case report

BackgroundCentral pontine myelinolysis (CPM) is a non-inflammatory demyelinating lesion of the pons. CPM and extrapontine demyelination (EPM) are together termed osmotic demyelination syndrome (ODS), a known and serious complication of acute correction of hyponatremia. Conversely, hyperglycemic hyperosmolarity syndrome (HHS) develops in patients with type 2 diabetes who still have some insulin secretory ability due to infection, non-compliance with treatment, drugs, and coexisting diseases, and is often accompanied by ketosis. HHS represents a life-threatening endocrine emergency (mortality rate, 10–50%) associated with marked hyperglycemia and severe dehydration. HHS may develop ODS, and some cases have been associated with hypernatremia.Case presentationThe patient was an 87-year-old woman with hyperglycemia, dehydration, malnutrition, and potential thrombus formation during long-term bed rest. HHS was suspected to have developed due to progression of hyperglycemia and dehydration caused by pneumonia. Furthermore, ketoacidosis developed from ketosis and prerenal renal failure associated with circulating hypovolemia shock, which was also associated with disseminated intravascular coagulation. Treatment was started with continuous intravenous injection of fast-acting insulin and low-sodium replacement fluid. In addition, ceftriaxone sodium hydrate, heparin sodium, thrombomodulin α, human serum albumin, and dopamine hydrochloride were administered. Blood glucose, serum sodium, serum osmolality, and general condition (including vital, infection/inflammatory findings, and disseminated intravascular coagulation) improved promptly, but improvements in disturbance of consciousness were poor. Diffusion-weighted imaging of the brain 72 h after starting treatment showed no obvious abnormalities, but high-intensity signals in the midline of the pons became apparent 30 days later, leading to definitive diagnosis of CPM.ConclusionsFluctuation of osmotic pressure by treatment from hyperosmolarity due to hyperglycemia and hypernatremia in the presence of risk factors such as malnutrition, severe illness, and metabolic disorders may be a cause of CPM onset. When treating HHS with risk factors, the possibility of progression to ODS needs to be kept in mind.

Tolerability of daily intermittent or continuous short-arm centrifugation during 60-day 6o head down bed rest (AGBRESA study).

Artificial gravity through short-arm centrifugation has potential as a multi-system countermeasure for deconditioning and cranial fluid shifts that may underlie ocular issues in microgravity. However, the optimal short-arm centrifugation protocol that is effective whilst remaining tolerable has yet to be determined. Given that exposure to centrifugation is associated with presyncope and syncope and in addition motion sickness an intermittent protocol has been suggested to be more tolerable. Therefore, we assessed cardiovascular loading and subjective tolerability of daily short arm centrifugation with either an intermittent or a continuous protocol during long-term head-down bed rest as model for microgravity exposure in a mixed sex cohort. During the Artificial Gravity Bed Rest with European Space Agency (AGBRESA) 60 day 6° head down tilt bed rest study we compared the tolerability of daily +1 Gz exposure at the center of mass centrifugation, either performed continuously for 30 minutes, or intermittedly (6 x 5 minutes). Heart rate and blood pressure were assessed daily during centrifugation along with post motion sickness scoring and rate of perceived exertion. During bed rest, 16 subjects (6 women, 10 men), underwent 960 centrifuge runs in total. Ten centrifuge runs had to be terminated prematurely, 8 continuous runs and 2 intermittent runs, mostly due to pre-syncopal symptoms and not motion sickness. All subjects were, however, able to resume centrifuge training on subsequent days. We conclude that both continuous and intermittent short-arm centrifugation protocols providing artificial gravity equivalent to +1 Gz at the center of mass is tolerable in terms of cardiovascular loading and motion sickness during long-term head down tilt bed rest. However, intermittent centrifugation appears marginally better tolerated, albeit differences appear minor.

Exercise-induced changes in brain activity during memory encoding and retrieval after long-term bed rest

Episodic memory depends decisively on the hippocampus and the parahippocampal gyrus, brain structures that are also prone to exercise-induced neuroplasticity and cognitive improvement. We conducted a randomized controlled trial to investigate the effects of a high-intensity exercise program in twenty-two men resting in bed for 60 days on episodic memory and its neuronal basis. All participants were exposed to 60 days of uninterrupted bed rest. Eleven participants were additionally assigned to a high-intensity interval training that was performed five to six times weekly for 60 days. Episodic memory and its neural basis were determined four days prior to and on the 58th day of bed rest using functional magnetic resonance imaging (fMRI). We found increased BOLD signal in the left hippocampus and parahippocampal gyrus in the non-exercising group compared to the exercising bed rest group whereas the mnemonic performance did not differ significantly. These findings indicate a higher neuronal efficiency in the training group during memory encoding and retrieval and may suggest a dysfunctional mechanism in the non-exercising bed rest group induced by two months of physical inactivity. Our results provide further support for the modulating effects of physical exercise and adverse implications of a sedentary lifestyle and bedridden patients.

Effect of acupuncture method of removing-stasisand resuscitating on the consciousness of patients with severe traumatic brain injury: A randomized clinical trial.

Introduction:With the development of social economy, transportation and various infrastructures have also developed, but it has objectively increased the number of patients with head injury. Although the current craniocerebral medicine technology continues to advance, long-term bed rest and other complications have led to an insignificant decrease in the mortality rate of coma patients. It is not uncommon for patients with disturbance of consciousness caused by head injury in major hospitals.Methods/design:This will be a retrospective, single-blind clinical observational study. We will select 50 cases that meet the subject's selection criteria. According to whether they received acupuncture treatment or not, they will be randomly divided into 2 groups, namely treatment group and control group. The control group will be given conventional Western medicine treatment, and the treatment group will be given acupuncture method of removing-stasis and resuscitating treatment on the basis of the control group.Discussion:Our purpose is to observe the role of acupuncture method of removing-stasis and resuscitating in promoting the recovery of patients with severe head injury. We aim to provide more evidence-based medical evidence for acupuncture treatment of this disease.Trial registration:ClinicalTrials.gov, ChiCTR2000034732, Registered on 19 July 2020

Disposable rubber gloves that are filled or inflated for prevention of pressure sores

For patients with long-term bed rest and limited autonomous activity clinically, the cubital joint, sacrum, scapula, and other bony protuberances are most likely to incur skin integrity damage and stress injury, which could increase patient pain and reduce the quality of nursing care.

Intracranial pressure and visual acuity: The final frontier?

Intracranial pressure and visual acuity: The final frontier?

Benign paroxysmal positional vertigo as a complication of 90-day head-down bed rest.

This study aimed to report the occurrence of benign paroxysmal positional vertigo (BPPV) in a 90-day head-down bed rest experiment and evaluate the potential relationship between BPPV-related seizures and bone metabolic changes. Five cases of lateral semicircular canal (LSC) BPPV were diagnosed during a 90-day head-down bed rest experiment. Five age-matched subjects who participated in this experiment and never felt dizziness or vertigo were assigned as controls. The differences between the BPPV and the controls in lumbar bone mineral density, 25-hydroxyvitamin D level, corrected serum calcium, potassium, sodium, phosphorus, iron, uric acid and N-terminal osteocalcin were analyzed to determine the cause of LSC-BPPV. BPPV occurred from Day 17 to Day 42 during head-down bed rest. The occurrences of BPPV were related to low 25-hydroxyvitamin D level (BPPV:20.70 ± 1.95ng/L vs. control: 30.59 ± 2.75ng/L at Day 30 during HDBR, p < 0.05). The relatively longer duration in the prone posture at 6° head down in this experiment may have a potential role in the involvement of the LSC. The maneuver used in the experiment effectively alleviated the acute symptoms of LSC-BPPV. The cases of LSC-BPPV in the early period of 90-day of head-down bed rest were related to the low 25-hydroxyvitamin D level and the 6° head-down posture. These results suggest that the potential role of unloading-induced bone loss on BPPV-related seizures deserves attention in future studies of long-term bed rest.

Protein Nutritional Support: The Classical and Potential New Mechanisms in the Prevention and Therapy of Sarcopenia.

Sarcopenia commonly occurs in the elderly and patients with wasting diseases. The main reason is an imbalance in protein metabolism (protein degradation exceeding protein synthesis). It causes a serious decline in muscle strength and motion ability, even leading to long-term bed rest. Recent studies indicate that nutritional support is beneficial for ameliorating sarcopenia and restoring muscle function. This review will summarize the classical mechanisms of protein nutritional support for alleviating sarcopenia, such as modulating the ubiquitin-proteasome system, oxidative response, and cell autophagy, as well as the potential new mechanisms, including altering miRNA profiles and gut microbiota. In addition, the clinical application and outcome of protein nutritional support in the elderly and patients with wasting diseases are also introduced. Protein nutritional support is expected to provide new approaches for the prevention and adjuvant therapy of sarcopenia.

Long-Term Immobilization in Elderly Females Causes a Specific Pattern of Cortical Bone and Osteocyte Deterioration Different From Postmenopausal Osteoporosis.

Immobilization as a result of long-term bed rest can lead to gradual bone loss. Because of their distribution throughout the bone matrix and remarkable interconnectivity, osteocytes represent the major mechanosensors in bone and translate mechanical into biochemical signals controlling bone remodeling. To test whether immobilization affects the characteristics of the osteocyte network in human cortical bone, femoral diaphyseal bone specimens were analyzed in immobilized female individuals and compared with age-matched postmenopausal individuals with primary osteoporosis. Premenopausal and postmenopausal healthy individuals served as control groups. Cortical porosity, osteocyte number and lacunar area, the frequency of hypermineralized lacunae, as well as cortical bone calcium content (CaMean) were assessed using bone histomorphometry and quantitative backscattered electron imaging (qBEI). Bone matrix properties were further analyzed by Fourier transform infrared spectroscopy (FTIR). In the immobilization group, cortical porosity was significantly higher, and qBEI revealed a trend toward higher matrix mineralization compared with osteoporotic individuals. Osteocyte density and canalicular density showed a declining rate from premenopausal toward healthy postmenopausal and osteoporotic individuals with peculiar reductions in the immobilization group, whereas the number of hypermineralized lacunae accumulated inversely. In conclusion, reduced osteocyte density and impaired connectivity during immobilization are associated with a specific bone loss pattern, reflecting a phenotype clearly distinguishable from postmenopausal osteoporosis. Immobilization periods may lead to a loss of survival signals for osteocytes, provoking bone loss that is even higher than in osteoporosis states, whereas osteocytic osteolysis remains absent. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Evaluation of Percutaneous Pedicle Screw Fixation in Patients with Pyogenic Spondylitis of the Thoracolumbar Spine

Background: Basic principle for the treatment of pyogenic spondylitis (PS) is conservative care, but surgical intervention is often required when conservative treatment may fail. We have experienced many conservative cases of various complications due to long-term bed rest and poor pain control. Recently we have adopted percutaneous pedicle screw (PPS) fixation for the treatment of PS as a minimally invasive spine stabilization (MISt) fusion to reduce such morbidity of the conservative care. Objective: To evaluate the impact of PPS fixation in patients with PS. Study Design: A retrospective analysis of the medical records. Subjects, Methods: We reviewed 54 consecutive patients who underwent treatment in our hospital for PS during 2005-2018 and observed for more than 12 months. Of those we excluded cases showing effectiveness to initial treatment (it was defined fever relief or C-reactive protein (CRP) inversion in 3 weeks of antibiotics) so that this study is a retrospective study in cases showing initial treatment resistance. Finally, this study included 29 cases. Medical records of these 29 cases were reviewed for baseline, organism isolated and its detection rate, the clinical outcome in 12 months (Discharge, Transfer, Death), the period from the first visit to our hospital to fever relief, CRP inversion, ambulation, and Discharge or Transfer. Results: These cases were divided into two groups, the conservative group (C-group): 17 cases, and the PPS group (P-group): 12 cases. There is no statistically significant difference in fever relief (p = 0.051) and CRP inversion (p = 0.208). The period to ambulation and discharge or transfer was significantly shorter in group P (p = 0.020, p = 0.031). 1-Year survival rate was 92% in the P-group, and 71% in the C-group. There is no statistically significant difference (p = 0.354) between the two groups. The rate of Discharge to home and care facility is 58% in P-group, and 47% in C-group. And the rate of Transfer is 34% in P-group, and 35% in C-group. Conclusion: PPS fixation was effective to achieve shortening the period to ambulation and discharge or transfer. But it was not effective in infection control. This suggests that PPS fixation should be aggressively administered to patients who can expect pain relief and early ambulation by PPS fixation in the patient of PS showing resistance to initial treatment.

Comparison of external fixation and intramedullary nailing in geriatric patients with intertrochanteric fractures of the femur

Aim: The healing time of femoral intertrochanteric fractures in the elderly population is prolonged due to the presence of osteoporosis. However, mortality is high because of major causes such as embolism due to long-term bed rest. It is particularly important that these patients be operated and given the freedom to move in the early postoperative period. In this study, we aimed to compare the clinical outcomes of Proximal Femoral Nail (PFN) and External Fixation (EF) in older patients with intertrochanteric fractures of the femur (ITFF).Methods: This study included 72 patients aged 65 years or older who were diagnosed with ITFF and underwent PFN (n=38) or EF (n=34) between 2011 and 2017. Patient data including demographic characteristics, preoperative ASA score, surgical technique, postoperative complications, and functional outcomes at final follow-up, Harris Hip Score (HHS) and Mean Mobility Score (MMS) scores were recorded for each patient.Results: The results indicated that both PFN and EF provided equally satisfactory functional outcomes in the patients. EF was found to have major advantages including significantly lower operative times, lower intraoperative blood loss, and administration of sedation only in high-risk patients. PFN was also found to have remarkable advantages such as lower reoperation risk, reduced mortality, and lower risk of superficial wound infection.Conclusion: Although both PFN and EF were found to have remarkable advantages, PFN seems to be more advantageous in terms of complications. Meaningfully, PFN could be more reliable and effective in the treatment of extracapsular ITFF in old-age patients.

Compression fractures of the spine in children: isn’t it time to change something?

Objective . To analyze the efficacy of various methods for treatment of children with compression fractures of the thoracic and lumbar spine on the basis of literature data. Material and Methods. A systematic review of the literature on methods for the diagnosis and treatment of compression fractures of the spine in children was carried out. PubMed, Science Direct, and Google Scholar databases were searched for literature sources for analysis. Results. A significant number of discrepancies between the approaches used in the treatment of compression fractures in children and the available literature data were noted. In particular, not any diagnostic protocol includes MRI as a tool to confirm the presence of a fracture, due to the high cost of the method and its low influence on the treatment tactic choice. The data of biomechanical studies cast doubt on the feasibility of long-term bed rest compliance and restrictions on sitting. As for bracing of patients with compression fractures, it has been demonstrated that wearing of rigid brace does not allow achieving better results in comparison with its absence. The child’s ability to remodel residual deformations of vertebral bodies ensures the restoration of their height and shape in the vast majority of cases. Currently, there is no data confirming the fact of earlier development of degenerative diseases and back pain in children who sustained compression vertebral fractures. Conclusion. The review results allow to analyze the efficacy of various treatment methods and can be the basis for reviewing the existing treatment tactics for children with compression fractures of the vertebral bodies.

Arterial and venous cerebral blood flow responses to long-term head-down bed rest in male volunteers.

What is the central question of this study? A heterogeneous cerebral blood flow (CBF) response in the cerebral arteries has been demonstrated in several physiological conditions, and it might be attributable to different physiological properties. However, the whole cerebral haemodynamic response to weightlessness remains unknown. What is the main finding and its importance? Long-term head-down bed rest caused a heterogeneous CBF response between the anterior and posterior cerebral arteries and between the cerebral arteries and veins. Especially, in contrast to the anterior cerebral circulation, the posterior arterial and venous CBFs were well maintained throughout weightlessness. In this study, we investigated the whole cerebral haemodynamic response to long-term head-down bed rest (HDBR). We hypothesized that long-term exposure to weightlessness influences cerebral blood flow (CBF) or CBF distribution among cerebral arteries and veins because of the different physiological roles of each cerebral vessel. To test this hypothesis, 10 male volunteers were exposed to -6deg HDBR for 60days. Blood flows in the internal carotid artery, external carotid artery and vertebral artery or internal jugular vein and vertebral vein were measured using ultrasonography before and on days30 and 57 of the HDBR. The internal carotid artery blood flow was reduced on day30 (P=0.019) and had returned to the baseline level by day57. In contrast, the vertebral artery blood flow remained unaltered throughout the HDBR (P=0.626). The internal jugular vein blood flow was reduced on day30 (P=0.009), whereas the vertebral vein blood flow remained unaltered (P=0.397). These findings suggest that long-term HDBR causes a heterogeneous CBF response between the anterior and posterior cerebral circulation in the both arteries and veins. The posterior arterial and venous CBFs were well maintained throughout HDBR, and these CBF responses to HDBR were different from the anterior cerebral circulation.

Anti-Disuse Osteoporosis Activity of a Complex of Calcium-Binding Peptide from Auricularia auricula Protein Hydrolysates.

Osteoporosis is a common metabolic bone disease that is often seen in bedridden patients and astronauts. Long-term bed rest and nonweight bearing tend to induce disuse osteoporosis. Calcium supplements are commonly used to help treat disuse osteoporosis along with medications, most of which are calcium carbonate based, but they have poor absorption effects. In this study, we prepared a novel Auricularia auricula peptide-calcium complex (AP-Ca) and evaluated its protective effects on disuse osteoporosis. In vitro assays showed that AP-Ca significantly increased the contents of calcium (P<0.05) and the activity of alkaline phosphatase (AKP; P<0.05) of osteoblasts cultured in a two-dimensional-rotating wall vessel. Meanwhile, supplementation with AP-Ca also inhibited the production of pro-inflammatory factors induced by the loss of stress, especially TNF-α (P<0.05). In vivo, a mouse tail suspension (TS) model was established, and the results showed that AP-Ca helped to improve bone mineral density, bone mineral content, and bone organic content in TS mice and effectively alleviated the alteration of enzymes related to bone metabolism, including AKP (P<0.05) and serum tartrate-resistant acid phosphatase (P<0.05), to avoid more serious bone loss induced by TS. Furthermore, we found that AP-Ca downregulated the bone resorption-associated pro-inflammatory genes interleukin-1 (IL-1), tumor necrosis factor-α, and IL-6 by 59.53±3.55%, 48.01±5.68%, and 40.00±5.89%, respectively (P<0.05). In conclusion, AP-Ca showed potential to suppress bone loss induced by disuse and might be considered a new alternative to reduce the risk of disuse osteoporosis. PRACTICAL APPLICATION: This peptide-calcium complex supplement exhibited protective effects on the bone loss induced by disuse, which provided a new alternative for patients and astronauts to reduce the risk of disuse osteoporosis.