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- Arinell, Karin, et al.
(författare)
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Downregulation of platelet activation markers during long-term immobilization
- 2013
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Ingår i: Platelets. - : Taylor & Francis. - 0953-7104 .- 1369-1635. ; 24:5, s. 369-374
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Tidskriftsartikel (refereegranskat)abstract
- Immobilization and sedentary lifestyle are risk factors for venous thromboembolism and cardiovascular disease, yet little is known about platelet function during long-term physical inactivity. Our aim was to investigate platelet activation markers and their coupling to standardized immobilization: platelet-derived growth factor (PDGF-BB) and P-selectin. We studied 15 healthy females participating in the Women International Space simulation for Exploration study. Following a 20-day ambulatory control period, the subjects underwent 60 days of bed rest in head-down tilt position (-6 degrees) 24 hours a day, finalized by 20 days of recovery. The subjects were randomized into two groups during bed rest: a control group (n = 8) that remained physically inactive and an exercise group (n = 7) that participated in both supine resistance and aerobic exercise training. Blood samples for the analysis of platelet activation markers were collected at baseline (5 days before bed rest), after 44 days of bed rest and 8 days into the recovery period. Compared to baseline, the levels of P-selectin and PDGF-BB decreased after bed rest (by 55%, p = 0.01 and 73%, p < 0.03, respectively) and remained decreased in the recovery period (by 76%, p < 0.001 and 78%, p < 0.02, respectively, compared to baseline). Platelet count (baseline value for the exercise group 260 000/mu l +/- 34 000 and baseline value for the control group 210 000/mu l +/- 30 000) did not change during the bed rest study (two-way repeated measurements ANOVA, p = ns). There were no statistical differences between the physically inactive and the exercise group. During long-term immobilization, a known risk factor for thrombosis, the levels of P-selectin and PDGF-BB decreased. Our findings indicate downregulation of platelet activation during immobilization.
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- Arinell, Karin, 1982-, et al.
(författare)
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Effect of prolonged standardized bed rest on cystatin C and other markers of cardiovascular risk
- 2011
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Ingår i: BMC Physiology. - : BioMed Central (BMC). - 1472-6793. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Sedentary lifestyle is associated with coronary artery disease but even shorter periods of physical inactivity may increase cardiovascular risk. Cystatin C is independently associated with cardiovascular disease and our objective was to investigate the relation between this novel biomarker and standardized bed rest. Research of immobilization physiology in humans is challenging because good biological models are in short supply. From the Women International Space simulation for Exploration study (WISE) we studied markers of atherosclerosis and kidney function, including cystatin C, in a standardized bed rest study on healthy volunteers. Fifteen healthy female volunteers participated in a 20-day ambulatory control period followed by 60 days of bed rest in head-down tilt position (-6°) 24 h a day, finalized by 20 days of recovery. The subjects were randomized into two groups during bed rest: a control group (n = 8) that remained physically inactive and an exercise group (n = 7) that participated in both supine resistance and aerobic exercise training.RESULTS: Compared to baseline values there was a statistically significant increase in cystatin C in both groups after bed rest (P < 0.001). Glomerular filtration rate (GFR), calculated by both cystatin C and Cockcroft-Gault equation, decreased after bed rest while there were no differences in creatinine or creatine kinase levels. CRP did not change during bed rest in the exercise group, but there was an increase of CRP in the control group during recovery compared to both the baseline and the bed rest periods. The apo-B/apo-Ai ratio increased during bed rest and decreased again in the recovery period. Subjects experienced a small but statistically significant reduction in weight during bed rest and compared to baseline weights remained lower at day 8 of recovery.CONCLUSION: During and following prolonged standardized bed rest the concentrations of several clinically relevant cardiovascular risk markers change.
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- Revsbech, Inge G., et al.
(författare)
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Decrease in the red cell cofactor 2,3-diphosphoglycerate increases hemoglobin oxygen affinity in the hibernating brown bear Ursus arctos
- 2013
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 304:1, s. R43-R49
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Tidskriftsartikel (refereegranskat)abstract
- Revsbech IG, Malte H, Frobert O, Evans A, Blanc S, Josefsson J, Fago A. Decrease in the red cell cofactor 2,3-diphosphoglycerate increases hemoglobin oxygen affinity in the hibernating brown bear Ursus arctos. Am J Physiol Regul Integr Comp Physiol 304: R43-R49, 2013. First published November 21, 2012; doi:10.1152/ajpregu.00440.2012.-During winter hibernation, brown bears (Ursus arctos) reduce basal O-2 consumption rate to similar to 25% compared with the active state, while body temperature decreases moderately (to similar to 30 degrees C), suggesting a temperature-independent component in their metabolic depression. To establish whether changes in O-2 consumption during hibernation correlate with changes in blood O-2 affinity, we took blood samples from the same six individuals of hibernating and nonhibernating free-ranging brown bears during winter and summer, respectively. A single hemoglobin (Hb) component was detected in all samples, indicating no switch in Hb synthesis. O-2 binding curves measured on red blood cell lysates at 30 degrees C and 37 degrees C showed a less temperature-sensitive O-2 affinity than in other vertebrates. Furthermore, hemolysates from hibernating bears consistently showed lower cooperativity and higher O-2 affinity than their summer counterparts, regardless of the temperature. We found that this increase in O-2 affinity was associated with a significant decrease in the red cell Hb-cofactor 2,3-diphosphoglycerate (DPG) during hibernation to approximately half of the summer value. Experiments performed on purified Hb, to which DPG had been added to match summer and winter levels, confirmed that the low DPG content was the cause of the left shift in the Hb-O-2 equilibrium curve during hibernation. Levels of plasma lactate indicated that glycolysis is not upregulated during hibernation and that metabolism is essentially aerobic. Calculations show that the increase in Hb-O-2 affinity and decrease in cooperativity resulting from decreased red cell DPG may be crucial in maintaining a fairly constant tissue oxygen tension during hibernation in vivo.
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- Sahdo, Berolla, 1984-, et al.
(författare)
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Body temperature during hibernation is highly correlated with a decrease in circulating innate immune cells in the brown bear (Ursus arctos) : a common feature among hibernators?
- 2013
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Ingår i: International Journal of Medical Sciences. - Sydney, Australia : Ivyspring International Publisher. - 1449-1907. ; 10:5, s. 508-514
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Tidskriftsartikel (refereegranskat)abstract
- Background: Hibernation involves periods of severely depressed metabolism (torpor) and decreases in body temperature (Tb). Small arctic mammals (<5kg), in which Tb generally drop drastically, display leukopenia during hibernation. This raised the question of whether the decreased leukocyte counts in mammalian hibernators is due to torpor per se or is secondary to low Tb. The present study examined immune cell counts in brown bears (Ursus arctos), where torpor is only associated with shallow decreases in Tb. The results were compared across hibernator species for which immune and Tb data were available.Methods and Results: The white blood cell counts were determined by flow cytometry in 13 bears captured in the field both during summer and winter over 2 years time. Tb dropped from 39.6+/-0.8 to 33.5+/-1.1 degrees C during hibernation. Blood neutrophils and monocytes were lower during hibernation than during the active period (47%, p=0.001; 43%, p=0.039, respectively), whereas no change in lymphocyte counts was detected (p=0.599). Further, combining our data and those from 10 studies on 9 hibernating species suggested that the decline in Tb explained the decrease in innate immune cells (R-2=0.83, p<0.0001).Conclusions: Bears have fewer innate immune cells in circulation during hibernation, which may represent a suppressed innate immune system. Across species comparison suggests that, both in small and large hibernators, Tb is the main driver of immune function regulation during winter dormancy. The lack of a difference in lymphocyte counts in this context requires further investigations.
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