Days Of Bed Rest Research Articles

Lower body negative pressure treadmill exercise as a countermeasure for bed rest-induced bone loss in female identical twins

Supine weight-bearing exercise within lower body negative pressure (LBNP) alleviates some of the skeletal deconditioning induced by simulated weightlessness in men. We examined this potential beneficial effect in women. Because dietary acid load affected the degree of bone resorption in men during bed rest, we also investigated this variable in women. Subjects were 7 pairs of female identical twins assigned at random to 2 groups, sedentary bed rest (control) or bed rest with supine treadmill exercise within LBNP. Dietary intake was controlled and monitored. Urinary calcium and markers of bone resorption were measured before bed rest and on bed rest days 5/6, 12/13, 19/20, and 26/27. Bone mineral content was assessed by dual-energy X-ray absorptiometry before and after bed rest. Data were analyzed by repeated-measures two-way analysis of variance. Pearson correlation coefficients were used to define the relationships between diet and markers of bone metabolism and to estimate heritability of markers. During bed rest, all markers of bone resorption and urinary calcium and phosphorus increased ( P < 0.001); parathyroid hormone ( P = 0.06), bone-specific alkaline phosphatase ( P = 0.06), and 1,25-dihydroxyvitamin D ( P = 0.09) tended to decrease. LBNP exercise tended to mitigate bone density loss. The ratio of dietary animal protein to potassium was positively correlated with urinary calcium excretion for all weeks of bed rest in the control group, but only during weeks 1 and 3 in the exercise group. Pre-bed rest data suggested that many markers of bone metabolism have strong genetic determinants. Treadmill exercise within LBNP had less of a protective effect on bone resorption during bed rest in women than previously published results had shown for its effect in men, but the same trends were observed for both sexes. Dietary acid load of these female subjects was significantly correlated with calcium excretion but not with other bone resorption markers.

Bed rest and immunity

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 φ X-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.

Quality‐of‐life and health benefits of early treatment of mild anemia

Chemotherapy-related anemia is prevalent among patients with hematologic malignancies. A randomized, open-label, multicenter trial of early versus late epoetin alfa in this population was conducted, focusing on quality of life (QOL). Patients with non-Hodgkin lymphoma, Hodgkin lymphoma, chronic lymphocytic leukemia, or multiple myeloma and baseline hemoglobin of 10 to 12 g/dL who were scheduled for > or = 4 months of myelosuppressive chemotherapy were randomized to receive < or = 16 weeks of epoetin alfa at a dose of 40,000 U once weekly immediately (early) or to wait and only receive epoetin alfa if hemoglobin decreased to < 9 g/dL (late). Those patients with a hemoglobin level > 12 g/dL after 3 chemotherapy cycles were not randomized. The primary endpoint was a mean change in the Functional Assessment of Cancer Therapy-Anemia (FACT-An) total. In all, 269 patients with a hemoglobin level < or = 12 g/dL were randomized. The mean total FACT-An increased 3.84 (95% confidence interval [95% CI], 0.21-7.46) in early patients and decreased 4.37 (95% CI, -7.99 to -0.74) in late patients (P = .003). Early patients had significantly (P < .05) higher mean scores for total FACT-General; FACT-General physical and functional well-being subscales, total anemia scale, and fatigue subscale; and daily activity, energy, and important activity Linear Analog Scale Assessment scales, as well as reduced bedrest days and restricted activity days. The mean hemoglobin increased 1.2 g/dL (95% CI, 0.98-1.46) in early patients but decreased 0.2 g/dL (95% CI, -0.32-0.12) in late patients (P < .0001). Adverse events were similar between groups (with fatigue being the most prevalent); clinically relevant thromboembolic events were more common in early patients. Treating mild anemia immediately with epoetin alfa during chemotherapy for hematologic malignancy significantly improved QOL, productivity, and hemoglobin compared with delaying treatment until the hemoglobin level decreases to < 9.0 g/dL.

Effects of Acute Simulated Microgravity on Nocturnal Sleep, Daytime Vigilance, and Psychomotor Performance: Comparison of Horizontal and 6° Head-Down Bed Rest

This study examined the effect of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance. Each of 7 volunteers were maintained for 3 days of head-down and horizontal bed rest in a counter-balanced design. Assessment measures were polysomnographic recordings on the first night and performance on psychophysiological tasks on the second day involving subjective and objective vigilance, P300, simple reaction time tasks, and dual performance tasks. No clear difference in sleep structure was observed between the head-down and horizontal conditions, except for a slight decrease in Stage 4 for head-down. Both subjective and objective daytime vigilance, P300, and the simple RT task showed no statistical difference, although tracking performance on the dual task showed deterioration at 10:00 for the head-down condition. These results suggest that nocturnal sleep, daytime vigilance, and psychophysiological functions were not disturbed in head-down sleep conditions, although there was a mild deterioration of higher attentional function in the morning.

Factors determining the time course of $${\dot{V}}\hbox{O}_{2\max}$$ decay during bedrest: implications for $${\dot{V}}\hbox{O}_{2\max}$$ limitation

The aim of this study was to characterize the time course of maximal oxygen consumption VO2(max) changes during bedrests longer than 30 days, on the hypothesis that the decrease in VO2(max) tends to asymptote. On a total of 26 subjects who participated in one of three bedrest campaigns without countermeasures, lasting 14, 42 and 90 days, respectively, VO2(max) maximal cardiac output (Qmax) and maximal systemic O2 delivery (QaO2max) were measured. After all periods of HDT, VO2max, Qmax, and QaO2max were significantly lower than before. The VO2max decreased less than qmax after the two shortest bedrests, but its per cent decay was about 10% larger than that of Qmax after 90-day bedrest. The VO2max decrease after 90-day bedrest was larger than after 42- and 14-day bedrests, where it was similar. The Qmax and QaO2max declines after 90-day bedrest was equal to those after 14- and 42-day bedrest. The average daily rates of the VO2max, Qmax, and QaO2max decay during bedrest were less if the bedrest duration were longer, with the exception of that of VO2max in the longest bedrest. The asymptotic VO2max decay demonstrates the possibility that humans could keep working effectively even after an extremely long time in microgravity. Two components in the VO2max decrease were identified, which we postulate were related to cardiovascular deconditioning and to impairment of peripheral gas exchanges due to a possible muscle function deterioration.

Why Is Orthostatic Tolerance Lower in Women than in Men? Renal and Cardiovascular Responses to Simulated Microgravity and the Role of Midodrine

BackgroundExposure to microgravity induces cardiovascular deconditioning, manifested by orthostatic intolerance (OI). We assessed the renal, cardioendocrine, and cardiovascular responses of women and men to simulated microgravity to examine the impact...

Human skeletal muscle structure and function preserved by vibration muscle exercise following 55 days of bed rest

Prolonged immobilization of the human body results in functional impairments and musculoskeletal system deconditioning that may be attenuated by adequate muscle exercise. In a 56-day horizontal bed rest campaign involving voluntary males we investigated the effects of vibration muscle exercise (RVE, 2x6 min daily) on the lower limb skeletal muscles using a newly designed foot plantar trainer (Galileo Space) for use at supine position during bed rest. The maximally voluntary isometric plantar flexion force was maintained following regular RVE bouts during bed rest (controls -18.6 %, P<0.05). At the start (BR2) and end of bed rest (BR55) muscle biopsies were taken from both mixed fast/slow-type vastus lateralis (VL) and mainly slow-type soleus muscle (SOL), each having n=10. RVE group: the size of myofiber types I and II was largely unchanged in VL, and increased in SOL. Ctrl group: the SOL depicted a disrupted pattern of myofibers I/II profiles (i.e., type II>140 % vs. preBR) suggesting a slow-to-fast muscle phenotype shift. In RVE-trained SOL, however, an overall conserved myofiber I/II pattern was documented. RVE training increased the activity-dependent expression of nitric oxide synthase type 1 immunofluorescence at SOL and VL myofiber membranes. These data provide evidence for the beneficial effects of RVE training on the deconditioned structure and function of the lower limb skeletal muscle. Daily short RVE should be employed as an effective atrophy countermeasure co-protocol preferentially addressing postural calf muscles during prolonged clinical immobilization or long-term human space missions.

Effects of 10 days of bedrest on body composition and the rate of muscle protein synthesis in older men and women

The effects of bed rest are well described in younger subjects but have not been evaluated in older adults. The objective of this study was to examine the effects of 10 days of bed rest on body composition changes and muscle protein synthesis in healthy older people. Eight subjects (68 ± 5 yo, M/F: 2/6) remained in bed, except for toileting, for 10 consecutive days. All subjects consumed a eucaloric diet providing 0.8 g protein·kg−1·d−1. Body composition (DEXA), and muscle protein synthesis (24-hr infusion of 13C6-phenylalanine) were assessed before and immediately after bed rest. On average, there was a 7% loss of lower extremity lean tissue in these subjects (14454 g to 13511 g, p<0.05), and the fractional muscle protein synthetic rate declined 44% (n=4, 0.086 %·hr−1 to 0.048 %·hr−1, p<0.05). These results indicate that there is a significant loss of muscle, with a more pronounced decline in muscle protein synthesis as a result of 10 days of bed rest. This loss of muscle in these older people after 10 days is greater than that seen in previous studies in young subjects after 28 days of bed rest. These data are of particular significance given the number of older adults that experience prolonged bed rest during hospitalization or institutionalization. Prophylactic measures to prevent loss of skeletal muscle in elderly people during prolonged periods of inactivity should be given a high priority. NIH PO1 AG023591, M01 RR14288

Skeletal Muscle Strength and Functional Ability in Older Adults Following 10 Days of Bed Rest

Older adults tend to be less physically active than the general population. During the course of treatment for illness, trauma or major surgery, activity is further impaired by bed rest and may lead to declines in muscle strength and functional ability beyond those of normal aging. We evaluated the effects on muscle strength and overall function following 10 days of bed rest in healthy older adults (n=9, 67±5yrs). Primary outcome measures included leg press 1-RM strength, unilateral knee extensor 1-RM strength, and standing plantar flexion strength. Functional ability was assessed by the Short Physical Performance Battery (SPPB) (timed balance, timed 4m walk and timed chair rise) and by summing 4 tests (gait speed, timed floor transfer, timed 5-step test and gait endurance). Ten days of bed rest decreased unilateral knee extensor 1-RM strength by 12±12% (p=0.02) and standing plantar flexion strength by 17±10% (p=0.02); while leg press 1-RM strength was unaffected (p=0.08). Functional ability (p=0.04) and the SPPB (p=0.59) were unchanged. Ten days of bed rest resulted in decreased strength of the knee extensors and plantar flexors without an impairment of functional ability that could be assessed by our measures. This data suggests either the need for more sensitive tests of functional ability or the existence of a muscle strength threshold that must be breached before functional impairment occurs. AG 023591, MO1 RR 00073, RR14288

WISE‐2005: 60 days head‐down bed rest causes a shift towards a pro‐atherosclerotic environment

This study reports on the first 12 subjects of the Women International Space Simulation for Exploration (WISE) who completed 60 days of head-down tilt (HDT) bed rest to test exercise and nutrition countermeasures compared to controls. We hypothesized that exercise would prevent an increase in pro-atherosclerotic factors associated with the inactivity of bed rest. Blood samples were collected before and at the end of bed rest to examine the difference in angiotensin II (ANG II), adhesion molecules (ICAM, VCAM, and e-SEL), and nitric oxide metabolites (NOmet), among others. ANG II was increased in both of the non-exercising groups (nutrition and control combined increased from 11.34±2.2pg/ml to 25.5±5.5pg/ml) but not in the exercise group (16.1±3.9pg/ml and 14.1±3.6pg/ml). ICAM and e-SEL showed no change; however VCAM increased in the non-exercising groups after the bed rest (584.8±23.8ng/ml and 630.2±17.0ng/ml). ANG II is known to increase the formation of reactive oxygen species (ROS), and may be a reason for the decrease seen in the levels of NOmet in the non-exercising groups (40.1±3.4μM and 26.5±3.8μM) but not in the exercising group (50.98±9.73μM to 47.88±5.21μM). 60 days of bed rest in HDT causes a shift in some factors towards a pro-atherosclerotic state while regular exercise during the bed rest prevented these changes. Supported by Canadian Space Agency, NASA, ESA, CNES

Inactivity and hormonal deregulation increase human skeletal muscle protein loss

We sought to quantify changes in human skeletal muscle protein kinetics during prolonged inactivity with and without accompanying hypercortisolemia. Oral hydrocortisone sodium succinate (~22 μg/dL) was administered to an experimental group (EXP: male, n=6, 28± 2 y; 84±4 kg; 178± 3 cm;) throughout 28 days of bedrest. The control group (CON: male, n=6; 38±8 y; 86±10 kg; 179±3 cm) received no exogenous cortisol (~10 μg/dL). Femoral arterio-venous blood samples and a vastus lateralis muscle biopsy were obtained during a primed constant infusion of L-[ring-2H5] phenylalanine before and after bed rest. Postabsorptive net balance became more negative in the EXP group following bedrest, a change largely facilitated by a ~40% reduction in protein synthesis in the EXP group. Table 1.. 3-pool model data representing protein synthesis (Fom) and breakdown (Fmo) (nmol/min/100mL leg) before and after bedrest. A similar superscript represents a statistical difference (p<0.05). The EXP group experienced a decrease in plasma testosterone (Day 1: 503.5±56.3 vs. Day 28: 409.5±28.6 ng/dL) and sex hormone binding globulin (SHBG) (Day 1: 22.5±2.5 vs. 12.2±1.5 nmol/L), (p<0.05). This was consistent with 3-fold greater loss of lean leg mass (LLM) in the EXP group (EXP: −1.4±0.1 vs. CON: −0.4±0.1 kg), (p<0.05). In conclusion, a combination of inactivity and hypercortisolemia leads to hormonal deregulation which in-turn further exacerbates muscle protein catabolism. Supported by funding from NPFR00205.

Mobilization versus immobilization in the treatment of acute proximal deep venous thrombosis: a prospective, randomized, open, multicentre trial

ABSTRACTObjective: The aim of prescribing strict bed rest for acute deep venous thrombosis is to reduce the risk of pulmonary embolism and pain in the legs, as well as swelling. This study was performed in order to compare outcome of mobilization against 5 days of strict bed rest in patients with acute proximal deep venous thrombosis (DVT).Methods: 103 in-patients with proximal DVT or patients admitted to the hospital because of proximal DVT were recruited to a randomized study. All patients were treated in hospital and given a lower leg and thigh compression bandage as well as therapeutic doses of the low molecular weight heparin, dalteparin-sodium (Fragmin).* Fragmin is a trade name of Pfizer Inc., New York, USAResults: Seven of 52 patients (13.5%) in the mobile group versus 14 of 50 patients (28.0%) in the immobile group suffered at least one of the outcomes defined under the combined primary endpoint (clinically relevant pulmonary embolisms, pulmonary embolisms detectable by scintigraphy or computer tomography, progression of thrombosis or new thrombosis, nosocomial infections and/or serious adverse events) ( p = 0.088), whereby serious adverse events occurred once in the mobile group and three times in the immobile group. New pulmonary embolisms over the course were seen in 10 of 50 patients (20%) with a perfusion disorder at baseline scintigraphy, while such was ascertained only in one of 52 patients (1.9%) without a perfusion disorder at baseline scintigraphy. Leg pain was reduced from 54.1 (± 30.4) to 20.7 (± 19.2) in the mobilized group and from 41.0 (± 26.8) to 14.0 (± 11.1) in the immobilized patients. Leg pain was assessed using the visual analogue scale (0 = no pain, 100 = maximum pain). More immobilized patients complained of increasing back pain (23% versus 6%) and disturbed micturition (10% versus 2%) as well as defecation (13% versus 6%) on day 5. More patients in the mobile group reported increased stress from the thrombosis and its treatment (15% versus 6%).Conclusions: No benefit of prescribing bed rest in patients with deep venous thrombosis could be detected in this study. Based on data available, strict bed rest for at least 5 days is not justified if adequate therapy with low molecular weight heparin and adequate compression is assured. It remains open whether patients with initial signs of pulmonary embolism might profit from a brief immobilization.

The importance of personality measurement in the assessment of response to treatment for ischaemic rest pain.

The purpose of the study was to investigate the relationship between personality and ischaemic rest pain. Twenty-four patients wth peripheral vascular disease unsuitable for surgery and suffering from ischaemic rest pain were treated equally with 14 days of bed rest and intravenous naftidrofuryl and their pain analogue scores and personality structures were analysed. There was a general trend of improvement in their analogue pain scores and patients with high neuroticism (N) and extroversion (E) levels had a better response to treatment, but which only became significant on one occasion when both N and E levels were high. Levels of N and E were compared with those of the normal population both before and after treatment and were found to be similar even after amputation.

Outpatient Surgery: A View Through History

C e CARING FOR PATIENTS who are having outpatient surgery is an everyday occurrence, as common today as any duty in the perianesthesia (PA) nursing world. However many still-practicing PA nurses can remember when, in the late 1960s, a patient remained in a hospital bed for several days after cataract surgery, head “sandbagged” to prevent movement. Days of bed rest followed a simple herniorrhaphy. Now, mind you, I speak of those baby-boomer nurses among us to illustrate that ambulatory surgery became a major force in the delivery of health care in the United States within recent history.

Highly Demanding Resistive Vibration Exercise Program is Tolerated During 56 Days of Strict Bed-Rest

Several studies have tried to find countermeasures against musculoskeletal de-conditioning during bed-rest, but none of them yielded decisive results. We hypothesised that resistive vibration exercise (RVE) might be a suitable training modality. We have therefore carried out a bed-rest study to evaluate its feasibility and efficacy during 56 days of bed-rest. Twenty healthy male volunteers aged 24 to 43 years were recruited and, after medical check-ups, randomised to a non-exercising control (Ctrl) group or a group that performed RVE 11 times per week. Strict bed-rest was controlled by video surveillance. The diet was controlled. RVE was performed in supine position, with a static force component of about twice the body weight and a smaller dynamic force component. RVE comprised four different units (squats, heel raises, toe raises, kicks), each of which lasted 60 - 100 seconds. Pre and post exercise levels of lactate were measured once weekly. Body weight was measured daily on a bed scale. Pain questionnaires were obtained in regular intervals during and after the bed-rest. Vibration frequency was set to 19 Hz at the beginning and progressed to 25.9 Hz (SD 1.9) at the end of the study, suggesting that the dynamic force component increased by 90 %. The maximum sustainable exercise time for squat exercise increased from 86 s (SD 21) on day 11 of the BR to 176 s (SD 73) on day 53 (p = 0.006). On the same days, post-exercise lactate levels increased from 6.9 mmol/l (SD2.3) to 9.2 mmol/l (SD 3.5, p = 0.01). On average, body weight was unchanged in both groups during bed-rest, but single individuals in both groups depicted significant weight changes ranging from - 10 % to + 10 % (p < 0.001). Lower limb pain was more frequent during bed-rest in the RVE subjects than in Ctrl (p = 0.035). During early recovery, subjects of both groups suffered from muscle pain to a comparable extent, but foot pain was more common in Ctrl than in RVE (p = 0.013 for plantar pain, p = 0.074 for dorsal foot pain). Our results indicate that RVE is feasible twice daily during bed-rest in young healthy males, provided that one afternoon and one entire day per week are free. Exercise progression, mainly by progression of vibration frequency, yielded increases in maximum sustainable exercise time and blood lactate. In conclusion, RVE as performed in this study, appears to be safe.

Cardiorespiratory responses to physical work during and following 17 days of bed rest and spaceflight

To determine the influence of a 17-day exposure to real and simulated spaceflight (SF) on cardiorespiratory function during exercise, four male crewmembers of the STS-78 space shuttle flight and eight male volunteers were studied before, during, and after the 17-day mission and 17 days of -6 degrees head-down-tilt bed rest (BR), respectively. Measurements of oxygen uptake, pulmonary ventilation, and heart rate were made during submaximal cycling 60, 30, and 15 days before the SF liftoff and 12 and 7 days before BR; on SF days 2, 8, and 13 and on BR days 2, 8, and 13; and on days 1, 4, 5, and 8 after return to Earth and on days 3 and 7 after BR. During 15 days before liftoff, day 4 after return, and day 8 after return and all BR testing, each subject completed a continuous exercise test to volitional exhaustion on a semirecumbent (SF) or supine (BR) cycle ergometer to determine the submaximal and maximal cardiorespiratory responses to exercise. The remaining days of the SF testing were limited to a workload corresponding to 85% of the peak pre-SF peak oxygen uptake (Vo2 peak) workload. Exposure to and recovery from SF and BR induced similar responses to submaximal exercise at 150 W. Vo2 peak decreased by 10.4% from pre-SF (15 days before liftoff) to day 4 after return and 6.6% from pre-BR to day 3 after return, which was partially (SF: -5.2%) or fully (BR) restored within 1 wk of recovery. Workload corresponding to 85% of the peak pre-SF Vo2 peak showed a rapid and continued decline throughout the flight (SF day 2, -6.2%; SF day 8, -9.0%), reaching a nadir of -11.3% during testing on SF day 13. During BR, Vo2 peak also showed a decline from pre-BR (BR day 2, -7.3%; BR day 8, -7.1%; BR day 13, -9.0%). These results suggest that the onset of and recovery from real and simulated microgravity-induced cardiorespiratory deconditioning is relatively rapid, and head-down-tilt BR appears to be an appropriate model of this effect, both during and after SF.

Portal vein cross-sectional area and flow and orthostatic tolerance: a 90-day bed rest study.

The objective of this study was to evaluate the changes in the portal vein cross-sectional area (PV CSA) and flow during a stand test associated with orthostatic intolerance. Eighteen subjects underwent a 90-day head-down tilt (HDT) bed rest at 6 degrees: 9 controls (Con) and 9 with flywheel exercise countermeasures (CM). At post-HDT, nine subjects (5 CM, 4 Con) were tolerant, and nine were intolerant. The PV CSA was measured by echography. We found that at HDT day 85, the PV CSA at rest had increased less in the CM subjects than in the Con (+12 vs. +27% from pre-HDT supine; P < 0.05), whereas it increased similarly in tolerant and intolerant subjects (23 and 16%, respectively). Two days after the HDT, there was a decrease in the PV CSA supine compared with the pre-HDT PV CSA supine that was similar for all groups (Con: -11%, CM: -21%; tolerant: -10%, intolerant: -16%; P < 0.05). The PV CSA decreased significantly less from supine to standing in the Con than in the CM group (-2 vs. -10% compared with the pre-HDT stand test; P < 0.05). The PV CSA also decreased significantly from supine to standing compared with the pre-HDT stand test in the tolerant group but not in the intolerant group (-20 vs. +2%; P < 0.05). From these findings, we conclude the following. 1) Because the portal vein is the only output from the splanchnic vascular area, we suggest that the lower reduction in the PV CSA and flow associated with orthostatic intolerance was related to a lower splanchnic arterial vasoconstriction. 2) The flywheel exercise CM helped to reduce the distention of the splanchnic network at rest and to maintain partially the splanchnic vasoconstriction, but it did not reduce the orthostatic intolerance.

Is radiation synovectomy for arthritis of the knee more effective than intraarticular treatment with glucocorticoids? Results of an eighteen‐month, randomized, double‐blind, placebo‐controlled, crossover trial

To compare the clinical efficacy and safety of radiation synovectomy (RSO) with intraarticular (IA) yttrium-90 plus glucocorticoids (GCs) with the efficacy and safety of IA placebo yttrium plus GCs and to identify parameters that predict efficacy. The knees of 97 patients with persistent arthritis despite outpatient treatment with IA GCs (n = 113 knees), were treated with either IA (90)Y plus GCs (50%) or IA placebo yttrium plus GCs (50%), followed by 3 days of bed rest in the hospital clinic, with splinting of the treated knee. Predominant diagnoses were undifferentiated arthritis (39%) and rheumatoid arthritis (32%). The clinical effect of therapy was assessed at 6 months using a composite change index (CCI; range 0-12). The primary outcome measure was the response rate (i.e., the percentage of joints with a CCI > or =6). Knees with persistent arthritis after 6 months underwent crossover therapy (51% of the (90)Y plus GCs group versus 45% of the placebo plus GCs group). Adverse effects and radiologic damage during followup were documented. Neither the response rate (48% in both groups), the mean CCI, nor the duration of remission was significantly different between groups. No clinically relevant short-term adverse effects were observed, except for progression of radiologic damage in 34% of the (90)Y plus GCs group versus 28% of the placebo plus GCs group (knee prosthesis placement in 8% versus 1%). The functional and radiologic status at study entry predicted the clinical effect. Treatment with (90)Y plus GCs with bed rest and splinting is not superior to IA GCs with bed rest and splinting. Over the short term, both treatments appeared to be safe, although a negative effect of (90)Y on cartilage and bone cannot be ruled out. Thus, it appears that RSO with (90)Y should no longer be considered the treatment of first choice for persistent arthritis of the knee.

Baroreflex impairment during rapid posture changes at rest and exercise after 120 days of bed rest

Orthostatic intolerance is common after space flight and head-down tilt (HDT) bed rest. We hypothesized that HDT-induced impairments of arterial blood pressure (AP) control would be more marked during exercise and that recovery of baroreflex function after very long-term HDT would be delayed. Six subjects were studied before (BDC) during (day 60, D60; D113) and after (recovery day 0, R0; R3; R15) 120 days of HDT. Supine resting subjects were exposed to repeated 1 min passive tilts to upright at 3-min interval. During 50 W steady-state exercise corresponding tilt had a 2-min duration at 4-min interval. The amplitudes of the tilt-induced transient beat-by-beat deviations in AP and rate (HR) were determined during the gravity transients. At rest these deviations did not change over time, but during exercise the total peak-to-nadir range of deviations in systolic AP (SAP) at up-tilt and down-tilt increased to 168+/-16% (mean+/-SEM) of BDC at D113 with no clear recovery upto and including R15. Counter-regulatory HR responses were not increased proportionally and especially not tachycardic responses to up-tilt, resulting in a reduction of baroreflex sensitivity (deltaRR-interval/deltaSAP) by 55+/-9% of BDC at D113 with no recovery upto and including R15. We conclude that prolonged bed rest cause long-lasting impairments in AP control and baroreflex function in exercising humans.

Concurrent Hearing and Visual Impairment and Morbidity in Community-Residing Adults

To examine the association between the presence and severity of concurrent hearing and visual impairment (HI+VI) and morbidity. Data for adults 45 years and older were obtained from the National Health Interview Survey, 1986 to 1996 (n = 60,997). Covariate-adjusted logistic regression analyses were used to examine associations between HI+VI and five morbidity indicators: restricted activity days, bed rest days, doctor visits, hospitalizations and self-rated health. Associations with morbidity indicators tended to be stronger in adults with HI+VI, and in particular, among adults with more severe HI+VI, relative to adults reporting no impairment. These associations were somewhat stronger in adults 45 to 64 years versus older adults. HI+VI is associated with morbidity, although the strength of these associations varies across subgroups. Findings indicate that an increased focus on the provision of hearing and eye care services is required. Insurance coverage for these services should also be pursued by health policy makers.