Periods Of Immobility Research Articles

Effects of Posture and Walking on Tibial Vascular Hemodynamics Before and After 14 Days of Head-Down Bed Rest.

Human skeletal hemodynamics remain understudied. Neither assessments in weight-bearing bones during walking nor following periods of immobility exist, despite knowledge of altered nutrient-artery characteristics after short-duration unloading in rodents. We studied 12 older adults (8 females, aged 59 ± 3 years) who participated in ambulatory near-infrared spectroscopy (NIRS) assessments of tibial hemodynamics before (PRE) and after (POST) 14 days of head-down bed rest (HDBR), with most performing daily resistance and aerobic exercise countermeasures during HDBR. Continual simultaneous NIRS recordings were acquired over the proximal anteromedial tibial prominence of the right lower leg and ipsilateral lateral head of the gastrocnemius muscle during supine rest, walking, and standing. During 10 minutes of walking, desaturation kinetics in the tibia were slower (time to 95% nadir values 125.4 ± 56.8 s versus 55.0 ± 30.1 s, p = 0.0014). Tibial tissue saturation index (TSI) immediately fell (-9.9 ± 4.55) and did not completely recover by the end of 10 minutes of walking (-7.4 ± 6.7%, p = 0.027). Upon standing, total hemoglobin (tHb) kinetics were faster in the tibia (p < 0.0001), whereas HDBR resulted in faster oxygenated hemoglogin (O2Hb) kinetics in both tissues (p = 0.039). After the walk-to-stand transition, changes in O2Hb (p = 0.0022) and tHb (p = 0.0047) were attenuated in the tibia alone after bed rest. Comparisons of NIRS-derived variables during ambulation and changes in posture revealed potentially deleterious adaptations of feed vessels after HDBR. We identify important and novel tibial hemodynamics in humans during ambulation before and after bed rest, necessitating further investigation. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Jekyll and Hyde: Day–night personality differences in the water scorpionNepa hoffmanni

AbstractDifferences between daytime and night-time behaviors are common in insects due to potential trade-offs between predator avoidance and foraging. While diel effects on average behavior are well documented, it remains unclear whether individuals differ in how they adjust their behavior between daytime and night-time. In this study, we focused on two light dependent behaviors, activity and tonic immobility, in the water scorpion (Nepa hoffmanni). Each individual was assayed for each behavior six times during the day and six times at night. Then, we explored diel differences in (1) average behavior, (2) among-individual variation in behavior, (3) individual rank order of behavioral expression, and (4) the sign and magnitude of behavioral syndromes (among-individual correlations between behaviors). At night, N. hoffmanni was more active and exhibited shorter periods of tonic immobility. Among-individual variation in activity was greater at night than during the day, but among-individual variation in tonic immobility did not differ between day and night. Individuals also differed in their diel plasticity in activity but not in tonic immobility. Thus, both (1) day–night differences in among-individual variation and (2) individual variation in diel plasticity contributed to the light-dependent sign of the behavioral syndromes. Our findings highlight the need for individual-level studies to fully elucidate diel influences on animal behavior. We suggest that day–night differences in behavioral syndromes as well as in selection might be key to behavioral evolution, especially in animals active during both day and night.

Precarious Emplacement in Croatia: Conceptualising More-Than-Transient Migration on the Balkan Route

The article argues that the dynamic of migration on the Balkan route is changing into something more than transit. Croatia is presented as a case in point of a site where former migration aspirations are redefined as migrants encounter various types of bordering mechanisms that decelerate migration and begin developing relations with other residents. We argue that the dynamic of mobility and immobility and the ways it entangles localities en route are crucial for understanding the changing migration patterns in the Balkans. We overview concepts such as “stuckness”, “waiting”, “permanent temporariness”, “limbo”, and “liminality”, which describe the ways in which migrants navigate between temporary and permanent states of movement and residence. Additionally, the article develops the concept of “precari¬ous emplacement” in order to move beyond transit and to capture the ambiguities between moving and staying, temporariness and permanence, and inclusion and exclusion. The concept highlights that the practices related to settling, along with the social interactions with other residents associated with them, occur in conditions of uncertainty and social marginalisation. Precarious emplacement encompasses the ways precarity permeates migrants’ experiences and the fabric of post-war and post-socialist urban spaces and relations they move through and come to inhabit. The article concludes by arguing that, given the heterogeneity of migrants’ life trajectories, the concept of a “transit migrant” may obscure the vulnerabilities migrants experience during periods of immobility, and it advocates for a more nuanced conceptual approach.

Behaviourally modulated hippocampal theta oscillations in the ferret persist during both locomotion and immobility

Theta oscillations are a hallmark of hippocampal activity across mammals and play a critical role in many hippocampal models of memory and spatial navigation. To reconcile the cross-species differences observed in the presence and properties of theta, we recorded hippocampal local field potentials in rats and ferrets during auditory and visual localisation tasks designed to vary locomotion and sensory attention. Here, we show that theta oscillations occur during locomotion in both ferrets and rats, however during periods of immobility, theta oscillations persist in the ferret, contrasting starkly with the switch to large irregular activity (LIA) in the rat. Theta during immobility in the ferret is identified as analogous to Type 2 theta that has been observed in rodents due to its sensitivity to atropine, and is modulated by behavioural state with the strongest theta observed during reward epochs. These results demonstrate that even under similar behavioural conditions, differences exist between species in the relationship between theta and behavioural state.

Effect of functional relaxation on the quality of life in patients with periprosthetic joint infection: Protocol for a randomised controlled trial

IntroductionPeriprosthetic joint infection (PJI) is a devastating complication in orthopaedic and trauma surgery, which puts a high burden on the patients involving recurrent hospitalisation, prolonged courses of antibiotic medication, severe...

Shock temporality: international students coping with disrupted lives and suspended futures

During the COVID-19 pandemic, people around the word experienced periods of local, state and international immobility due to lockdowns, border closers and travel restrictions. For transient migrants such as international students, these kinds of immobility have resulted in disrupted lives with professional and personal futures suspended as careers and relationships become stuck in limbo. Moreover, such sudden and extended periods of immobility have not been sufficiently covered in temporality literature due to the novelty of the pandemic crisis in the international education, migration and mobility studies spaces. By conducting a pilot project investigating current and recently graduated higher degree by research (HDR) international students (PhD, Masters and Honours) from public institutions in the Australian city of Melbourne, this paper, thus, introduces the concept of ‘shock temporality’ caused by the global COVID-19 pandemic. Shock temporality takes place when the expected and finite temporary/transitory experience becomes forcefully broken and appears to be ongoing outside of the individual’s control. While shock temporality has left HDR international students’ professional and personal agendas and aspirations in suspension, students interviewed use the time to plan and prepare for truncated futures. The findings of this paper, thus, become relevant in assisting higher education student support services in creating potential approaches and strategies for a post-pandemic future.

PREDISPOSING FACTORS FOR PHYSICAL INACTIVITY IN THE COVID-19 PANDEMIC CONTEXT

Introduction: The pandemic caused by the SARS-CoV-2 virus has been causing major impacts on public health. The main risk factor for the development of comorbidities is a sedentary lifestyle, so, due to the readjustment of habits, the emergence of negative impacts from this process is noticeable, such as the increase in physical inactivity and the acquisition of habits harmful to health. In this way, several recommendations have been released drawing attention to the follow-up of physical activity during the pandemic. Objectives: To identify in the literature, scientific evidence about the predisposing factors for physical inactivity during the Covid-19 pandemic. Methodology: This is an integrative literature review, through a descriptive and exploratory effort, carried out in the scientific databases: MEDLINE, SCIELO, BRISA and LILACS. Results and Discussions: From the realization of the titles and abstracts of the articles, 15 studies were selected and after reading in full, 11 were left to compose the final sample. In view of the analysis of the literature, it was evidenced that the lack of adherence to programs for physical exercises at home, through new technologies, blocked the integral assistance to the citizen in the context of the promotion of physical activity, as well as preexisting factors even before the pandemic, such as diseases non-communicable diseases, chronic degenerative diseases, long periods of physical immobility and social inequalities. Final considerations: The study showed that the difficulties in carrying out the practice exist, although there are paths that can be outlined to reverse this scenario. Therefore, public policies to promote physical activity are suggested, which are more consistent on the part of government agencies. In addition, adherence to technological resources also becomes a relevant alternative, combined with health education actions, so that the population has knowledge about the benefits and correct guidelines on how to carry out the practices.

Moving forward, waiting or standing still? Service users’ experiences from a Norwegian labour activation programme

ABSTRACT Labour activation policy relies on a notion of temporal homogeneity, with the assumption that the service user, once enrolled in a labour activation programme, moves forward on a linear and progressive trajectory into the labour market. However, for many, labour activation is experienced as a discontinuous and interrupted trajectory, through which one occasionally moves forward, but which also contains periods of immobility and standstill. The literature has illuminated the complex nature of labour activation trajectories, including transitions over time. We introduce a focus on how servicer users in a Norwegian labour activation programme construct understandings of time itself, as ‘waiting’ or ‘moving forward’, in connection with their labour activation experiences. Applying a rhythm analysis that attends to biography and change over time, we explore how service users’ life course rhythms meet with and diverge from the institutionally defined labour activation rhythms, and how dissonance may shape the way that users understand their labour activation experiences. The study is based on fieldwork in The Norwegian labour and welfare services (NAV). Our findings point to how participants experience the time spent in labour activation differently and how seemingly similar experiences and activities may mean ‘waiting’ for some and ‘moving forward’ for others.

The grade of instability in fragility fractures of the pelvis correlates with impaired early mobilization

PurposeThis study aimed to investigate whether gait patterns of patients with fragility fractures of the pelvis (FFP) comply with the grade of fracture instability, defined by radiological patterns.Patients and methodsThis prospective, single-center, observational study included 39 patients with an FFP. Gait analysis was performed with a wearable insole force sensor (Loadsol® by Novel, Munich, Germany) 4–7 days after admission. Patients were divided in two groups: Group A included FFP type 1 fractures, which affect the anterior pelvic ring only, Group B contained FFP type 2–4 fractures with an involvement of the posterior pelvic ring. Primary outcome parameter was the FTI ratio (force–time integral (N*s)).ResultsThe mean age was 85.08 years (SD ± 6.45), 94.9% (37/39) of the patients were female. The most common fracture type was an FFP 2b (64.1%, 25/39). Group A showed a significantly higher FTI ratio (45.12%, SD ± 4.19%) than Group B (38.45%, SD ± 5.97%, p = 0.002). Further, a significant correlation of the FTI ratio and the average (r = 0.570, p < 0.001) and maximum (r = 0.394, p = 0.013) peak force was observed.ConclusionThe gait pattern of patients with an FFP type 2–4 was more imbalanced than of patients with an FFP type 1 fracture. These findings match with the radiological classification of FFP, which indicates higher instability, when the posterior pelvis is affected. Gait analysis might offer earlier functional diagnostics and may accelerate the treatment decision with shorter periods of immobility in future. Especially in cross-border cases, early gait analysis could be beneficial to clarify the indication for or against surgery.

Exploring the Impacts of Shrub‐Overwash Feedbacks in Coastal Barrier Systems With an Ecological‐Morphological Model

AbstractShrubs are common – and presently expanding – across coastal barrier interiors (the land between the foredune system and back‐barrier bay), and have the potential to influence barrier morphodynamics by obstructing cross‐shore overwash flow. The ecological and geomorphological consequences of ecomorphodynamic couplings of the barrier interior, however, remain largely unexplored. In this contribution, we add an ecological module of shrub expansion and mortality to a spatially‐explicit exploratory model of barrier evolution (Barrier3D) to explore the effects of shrub‐barrier feedbacks. In our model simulations, we find that the presence of shrubs significantly alters barrier morphology and behavior. Over timescales of decades to centuries, barriers with shrubs (relative to those without) tend to be narrower, migrate landward more slowly, and have a greater proportion of subaerial volume distributed toward the ocean‐side of the barrier. Shrubs also tend to increase the likelihood of discontinuous barrier retreat, a behavior in which a barrier oscillates between periods of transgression and relative immobility, because shrubs induce prolonged periods of barrier immobility by obstructing overwash flow. However, shrubs can increase barrier vulnerability to drowning by preventing periods of transgression needed to maintain barrier elevation relative to rising sea levels. Additionally, physical barrier processes influence shrub expansion in our simulations; we find that greater dune erosion and overwash disturbance tends to slow the rate of shrub expansion across the barrier interior. Complementing recent observational studies of barrier islands in Virginia, USA, our results suggest that interior ecology can be a key component of barrier evolution on annual to centurial timescales.

Exercise following immobility increases lower motor neuron excitability: F-wave and H-reflex studies

ObjectivesThe excitability of lower motor neurons can be explored non-invasively by several neurophysiological techniques, e.g., F-wave and H-reflex studies after a period of immobility and then after subsequent exercise. The aim of this study is to investigate the impact of exercise and high frequency repetitive nerve stimulation (RNS) following changes induced by 75 min of immobility. MethodsWe studied 10 healthy subjects following 75 min lower limb immobility, then randomized to RNS or cycling on different days. The neurophysiological studies of M-response, F-wave latency, F/M amplitude ratio and persistence; H-reflex threshold and latency, H/M amplitude ratio, and homosynaptic depression were performed at baseline, after immobility and immediately following the intervention, using stimulation of posterior tibial and peroneal nerves. ResultsAfter immobility F-wave latencies were delayed and homosynaptic depression at 2 Hz was increased (p < 0.025). RNS had no effect, but cycling exercise reduced H-reflex latencies (p = 0.025) and decreased homosynaptic depression at 2 Hz. DiscussionOur findings suggest that both proprioceptive stimulation and supraspinal pathways modulate intraspinal physiological changes after immobility. These observations suggest that specific exercise protocols may be useful in managing patients recovering from periods of immobility.

Compassion, communication, and the perception of control: a mixed methods study to investigate patients’ perspectives on clinical practices for alleviating distress and promoting empowerment during awake craniotomies

Purpose To inquire into clinical practices perceived to mitigate patients’ intraoperative distress during awake craniotomies. Methods This mixed-methods study involved administration of Amsterdam Preoperative Anxiety and Information Scale and PTSD Checklist prior to the awake craniotomy to evaluate anxiety and information-seeking related to the procedure and symptoms of PTSD. Generalized Anxiety Disorder Scale and Depression Module of the Patient Health Questionnaire were administered before and after the procedure to evaluate generalized anxiety and depression. Patient interviews were conducted 2-weeks postprocedure and included a novel set of patient experience scales to assess patients’ recollection of intraoperative pain, overall distress, anxiety, distress due to noise, perception of empowerment, perception of being well-prepared, overall satisfaction with anaesthesia management, and overall satisfaction with the procedure. Qualitative data were analysed using conventional content analysis. Results Participants (n = 14) had undergone an awake craniotomy for tissue resection due to primary brain tumours or medically-refractory focal epilepsy. Validated self-report questionnaires demonstrated reduced levels of generalized anxiety (pre mean = 8.66; SD = 6.41; post mean= 4.36; SD = 4.24) following the awake craniotomy. Postprocedure interviews revealed very high satisfaction with the awake craniotomy and anaesthesia management and minimal levels of intraoperative pain, anxiety, and distress. The most stressful aspects of the procedure included global recognition of medical diagnosis, anxiety provoked by unfamiliar sights, sounds, and sensations, a perception of a lack of information or misinformation, and long periods of immobility. Important factors in alleviating intraoperative distress included the medical team’s ability to promote patient perceptions of control, establish compassionate relationships, address unfamiliar intraoperative sensations, and deliver effective anaesthesia management. Conclusion Compassion, communication, and patient perception of control were critical in mitigating intraoperative distress. Clinical practice recommendations with implications for all clinicians involved in patient care during awake craniotomies are provided. Use of these interventions and strategies to reduce distress are important to holistic patient care and patient experiences of care and may improve the likelihood of optimal brain mapping procedures to improve clinical outcomes during awake craniotomies.

Overview on Complex Regional Pain Syndrome: A Review

Complex regional pain syndrome (CRPS) is a neuropathic pain disease characterized by the presence of allodynia, hyperalgesia, sudomotor and vasomotor abnormalities, and trophic alterations. CRPS can be caused by a variety of degrees or types of tissue damage, but it has also been reported in the absence of injury or after lengthy periods of immobility. A fracture is the most prevalent injury linked to the development of CRPS. CRPS is thought to be caused by a complex process involving both the peripheral and central nerve systems, according to a recent acceptance. Patients with CRPS are said to have all of the symptoms of inflammation, including heat, discomfort, redness, and swelling. CRPS symptoms have been greatly reduced by corticosteroids in several clinical studies. The diagnosis of CRPS is mostly dependent on a patient's medical history and clinical examination, which includes a variety of tests that can help rule out other diseases. Given the syndrome's complexity, it's doubtful that focusing on a single mechanism will be successful. Combination therapy, like with other chronic conditions, may be the future of CRPS treatment. In this review we will be looking at disease definition, pathophysiology, and treatment.

Towards threshold invariance in defining hippocampal ripples

Objective. Hippocampal ripples are transient neuronal features observed in high-frequency oscillatory bands of local field potentials (LFPs), and they occur primarily during periods of behavioral immobility and slow-wave sleep. Ripples have been defined based on mathematically engineered features, such as magnitudes, durations, and cycles per event. However, the ‘ripple’ could vary from laboratory to laboratory because their definition is subject to human bias, including the arbitrary choice of parameters and thresholds. In addition, LFPs are often influenced by myoelectric noise arising from animal movement, making it difficult to distinguish ripples from high-frequency noises. These problems have to be overcome. Approach. We extracted ripple candidates under few constraints and labeled them as binary or stochastic ‘true’ or ‘false’ ripples using Gaussian mixed model clustering and a deep convolutional neural network (CNN) in a weakly supervised fashion. Main results. Our automatic method separated ripples and myoelectric noise and was able to detect ripples even when the animals were moving. Moreover, we confirmed that a CNN detected ripples defined by our method. Leave-one-animal-out cross-validation estimated the accuracy, the area under the precision-recall curve, the receiver operating characteristic curve to be 0.88, 0.99 and 0.96, respectively. Significance. Our automatic ripple detection method will reduce time spent on performing laborious experiments and analyses.

Post-infectious and post-acute sequelae of critically ill adults with COVID-19.

BackgroundData on the post-acute and post-infectious complications of patients who have recovered from severe coronavirus disease 2019 (COVID-19) are limited. While studies report that approximately 5–15% of COVID-19 hospitalized patients require intensive care and mechanical ventilation, a substantially higher number need non-invasive ventilation and are subject to prolonged hospitalizations, with long periods of immobility and isolation. The purpose of this study is to describe the post-infectious sequelae of severe viral illness and the post-acute complications of intensive care treatments in critically ill patients who have recovered from severe COVID-19 infection.MethodsWe performed a retrospective chart review of adult patients initially hospitalized with confirmed COVID-19 infection, who recovered and were transferred to a general medical ward or discharged home between March 15, 2020 and May 15, 2020, dates inclusive, after an intensive care unit (ICU) or high dependency unit (HDU) admission in a designated COVID-19 hospital in the United Arab Emirates. Demographic data, underlying comorbidities, treatment, complications, and outcomes were collected. Descriptive statistical analyses were performed.ResultsOf 71 patients transferred out of ICU (n = 38, 54%) and HDU (n = 33, 46%), mean age was 48 years (SD, 9.95); 96% men; 54% under age 50. Mean ICU stay was 12.4 days (SD, 5.29), HDU stay was 13.4 days (SD, 4.53). Pre-existing conditions were not significantly associated with developing post-acute complications (Odds Ratio [OR] 1.1, 95% confidence interval [CI] 0.41, 2.93, p = 1.00). Fifty nine percent of patients had complications; myopathy, swallowing impairments, and pressure ulcers were most common. Delirium and confusion were diagnosed in 18% (n = 13); all were admitted to the ICU and required mechanical ventilation. Of note, of all patients studied, 59.2% (n = 42/71) had at least 1 complication, 32.4% (n = 23) had at least 2 complications, and 19.7% (n = 14) suffered 3 or more sequelae. Complications were significantly more common in ICU patients (n = 33/38, 87%), compared to HDU patients (n = 9/33, 27%) (OR 17.6, 95% CI 5.23, 59.21, p <0.05).ConclusionIn a subset of critically ill patients who recovered from severe COVID-19 infection, there was considerable short-term post-infectious and post-acute disability. Long-term follow-up of COVID-19 survivors is warranted.

A narrative-based exploration of aging, precariousness and housing instability among low-income older adults in Canada

ABSTRACT In this article we focus upon low-income older adults’ lived experiences of aging, precariousness and housing instability/homelessness in Hamilton, Canada. Precariousness includes involuntary or incentivized displacement, as well as ‘health discounting’ in the face of rising shelter costs, inappropriate housing, periods of homelessness and involuntary housing immobility. The lived experiences of aging, precariousness and housing instability were collected through arts-based methodologies, whereby participants were given tablets to record their photos, videos and written diaries of their housing-related experiences. Additionally, participants took part in individual semi-structured interviews and participant observation in community-based settings. The recounting of participant experiences through a sensemaking frame allows for an exploration of the question of what it means to be ‘devalued’ as one ages to the extent that securing shelter is an overwhelming and stressful journey. Participant narratives provide compelling counter stories contesting popular notions that older adults will be taken care of as they age by the state or private savings. In sharing these stories, we are attempting to bring ‘recognizability’ to the experiences of aging, precariousness and housing/homelessness in order to contribute to the conditions through which low-income older adults’ experiences can be folded into policy co-design geared towards affordable housing.

Transcriptional Changes and Preservation of Bone Mass in Hibernating Black Bears

Physical inactivity leads to losses of bone mass and strength in most mammalian species. In contrast, hibernating bears show no bone loss over the prolonged periods (4 - 6 months) of immobility during winter, which suggests that they have adaptive mechanisms to preserve bone mass and structure. To identify transcriptional changes that underlie molecular mechanisms preventing disuse osteoporosis, we conducted a large-scale gene expression screening in trabecular bone, ilium, of black bears, comparing hibernating and summer active animals using next generation sequencing of the transcriptome. A total of 2,466 differentially expressed genes (FDR < 0.05) were up-regulated and 2,938 genes down-regulated during hibernation. Gene set enrichment analysis showed a coordinated down-regulation of genes involved in bone resorption, osteoclast differentiation and osteoclast signaling as well as apoptosis during hibernation. In contrast, no significant enrichment indicating directional changes in gene expression was detected in the gene sets of ossification (bone biosynthesis), osteoblast signaling and differentiation in bone of hibernating bears. Unanticipated under general metabolic suppression of hibernation, our study revealed significant and coordinated transcriptional induction of gene sets involved in aerobic energy production including the fatty acid beta oxidation, tricarboxylic acid cycle, oxidative phosphorylation, mitochondrial metabolism, biogenesis and turnover during hibernation. Mitochondrial oxidation and biogenesis were likely up-regulated by transcriptionally induced AMPK/PGC1α pathway, upstream master stimulator of mitochondrial function. We also found down-regulation of genes involved in immune response including both innate and adaptive immunity in bone marrow/bone of hibernating bears. Coordinated transcriptional suppression of bone resorption, osteoclast signaling and apoptosis genes implies decrease in resorption that preserves bone mass through the prolonged periods of immobility of hibernation.

Transcriptional changes and preservation of bone mass in hibernating black bears

Physical inactivity leads to losses of bone mass and strength in most mammalian species. In contrast, hibernating bears show no bone loss over the prolonged periods (4–6 months) of immobility during winter, which suggests that they have adaptive mechanisms to preserve bone mass. To identify transcriptional changes that underlie molecular mechanisms preventing disuse osteoporosis, we conducted a large-scale gene expression screening in the trabecular bone and bone marrow, comparing hibernating and summer active bears through sequencing of the transcriptome. Gene set enrichment analysis showed a coordinated down-regulation of genes involved in bone resorption, osteoclast differentiation and signaling, and apoptosis during hibernation. These findings are consistent with previous histological findings and likely contribute to the preservation of bone during the immobility of hibernation. In contrast, no significant enrichment indicating directional changes in gene expression was detected in the gene sets of bone formation and osteoblast signaling in hibernating bears. Additionally, we revealed significant and coordinated transcriptional induction of gene sets involved in aerobic energy production including fatty acid beta oxidation, tricarboxylic acid cycle, oxidative phosphorylation, and mitochondrial metabolism. Mitochondrial oxidation was likely up-regulated by transcriptionally induced AMPK/PGC1α pathway, an upstream stimulator of mitochondrial function.

Reversible thrombocytopenia during hibernation originates from storage and release of platelets in liver sinusoids

Immobility is a risk factor for thrombosis due to low blood flow, which may result in activation of the coagulation system, recruitment of platelets and clot formation. Nevertheless, hibernating animals—who endure lengthy periods of immobility—do not show signs of thrombosis throughout or after hibernation. One of the adaptations of hemostasis in hibernators consists of a rapidly reversible reduction of the number of circulating platelets during torpor, i.e., the hibernation phase with reduction of metabolic rate, low blood flow and immobility. It is unknown whether these platelet dynamics in hibernating hamsters originate from storage and release, as suggested for ground squirrel, or from breakdown and de novo synthesis. A reduction in detaching forces due to low blood flow can induce reversible adhesion of platelets to the vessel wall, which is called margination. Here, we hypothesized that storage-and-release by margination to the vessel wall induces reversible thrombocytopenia in torpor. Therefore, we transfused labeled platelets in hibernating Syrian hamster (Mesocricetus auratus) and platelets were analyzed using flow cytometry and electron microscopy. The half-life of labeled platelets was extended from 20 to 30 h in hibernating animals compared to non-hibernating control hamsters. More than 90% of labeled platelets were cleared from the circulation during torpor, followed by emergence during arousal which supports storage-and-release to govern thrombocytopenia in torpor. Furthermore, the low number of immature platelets, plasma level of interleukin-1α and normal numbers of megakaryocytes in bone marrow make platelet synthesis or megakaryocyte rupture via interleukin-1α unlikely to account for the recovery of platelet counts upon arousal. Finally, using large-scale electron microscopy we revealed platelets to accumulate in liver sinusoids, but not in spleen or lung, during torpor. These results thus demonstrate that platelet dynamics in hibernation are caused by storage and release of platelets, most likely by margination to the vessel wall in liver sinusoids. Translating the molecular mechanisms that govern platelet retention in the liver, may be of major relevance for hemostatic management in (accidental) hypothermia and for the development of novel anti-thrombotic strategies.

Functional capacity and rehabilitation strategies in Covid-19 patients: current knowledge and challenges.

Covid-19 is a novel infectious disease whose spectrum of presentation ranges from absence of symptoms to widespread interstitial pneumonia associated with severe acute respiratory syndrome (SARS), leading to significant mortality. Given the systemic pattern of Covid-19, there are many factors that can influence patient's functional capacity after acute infection and the identification of such factors can contribute to the development of specific rehabilitation strategies. Pulmonary impairment is the primary cause of hospitalization due to Covid-19, and can progress to SARS as well as increase length of hospitalization. Moreover, cardiac involvement is observed in approximately 30% of hospitalized patients, with an increased risk of acute myocarditis, myocardial injury, and heart failure, which may compromise functional capacity in the long-term. Thromboembolic complications have also been reported in some patients with Covid-19 and are associated with a poor prognosis. Musculoskeletal complications may result from long periods of hospitalization and immobility, and can include fatigue, muscle weakness and polyneuropathy. Studies that address the functional capacity of patients after Covid-19 infection are still scarce. However, based on knowledge from the multiple systemic complications associated with Covid-19, it is reasonable to suggest that most patients, especially those who underwent prolonged hospitalization, will need a multiprofessional rehabilitation program. Further studies are needed to evaluate the functional impact and the rehabilitation strategies for patients affected by Covid-19.