Combining sensor tracking with a GPS-based mobility survey to better measure physical activity in trips: public transport generates walking.

BACKGROUND: Policymakers need accurate data to develop efficient interventions to promote transport physical activity. Given the imprecise assessment of physical activity in trips, our aim was to illustrate novel advances in the measurement of walking in trips, including in trips incorporating non-walking modes. METHODS: We used data of 285 participants (RECORD MultiSensor Study, 2013-2015, Paris region) who carried GPS receivers and accelerometers over 7 days and underwent a phone-administered web mobility survey on the basis of algorithm-processed GPS data. With this mobility survey, we decomposed trips into unimodal trip stages with their start/end times, validated information on travel modes, and manually complemented and cleaned GPS tracks. This strategy enabled to quantify walking in trips with different modes with two alternative metrics: distance walked and accelerometry-derived number of steps taken. RESULTS: Compared with GPS-based mobility survey data, algorithm-only processed GPS data indicated that the median distance covered by participants per day was 25.3 km (rather than 23.4 km); correctly identified transport time vs. time at visited places in 72.7% of time; and correctly identified the transport mode in 67% of time (and only in 55% of time for public transport). The 285 participants provided data for 8983 trips (21,163 segments of observation). Participants spent a median of 7.0% of their total time in trips. The median distance walked per trip was 0.40 km for entirely walked trips and 0.85 km for public transport trips (the median number of accelerometer steps were 425 and 1352 in the corresponding trips). Overall, 33.8% of the total distance walked in trips and 37.3% of the accelerometer steps in trips were accumulated during public transport trips. Residents of the far suburbs cumulated a 1.7 times lower distance walked per day and a 1.6 times lower number of steps during trips per 8 h of wear time than residents of the Paris core city. CONCLUSIONS: Our approach complementing GPS and accelerometer tracking with a GPS-based mobility survey substantially improved transport mode detection. Our findings suggest that promoting public transport use should be one of the cornerstones of policies to promote physical activity.

Understanding the role of contrasting urban contexts in healthy aging: an international cohort study using wearable sensor devices (the CURHA study protocol).

BACKGROUND: Given the challenges of aging populations, calls have been issued for more sustainable urban re-development and implementation of local solutions to address global environmental and healthy aging issues. However, few studies have considered older adults' daily mobility to better understand how local built and social environments may contribute to healthy aging. Meanwhile, wearable sensors and interactive map-based applications offer novel means for gathering information on people's mobility, levels of physical activity, or social network structure. Combining such data with classical questionnaires on well-being, physical activity, perceived environments and qualitative assessment of experience of places opens new opportunities to assess the complex interplay between individuals and environments. In line with current gaps and novel analytical capabilities, this research proposes an international research agenda to collect and analyse detailed data on daily mobility, social networks and health outcomes among older adults using interactive web-based questionnaires and wearable sensors. METHODS/DESIGN: Our study resorts to a battery of innovative data collection methods including use of a novel multisensor device for collection of location and physical activity, interactive map-based questionnaires on regular destinations and social networks, and qualitative assessment of experience of places. This rich data will allow advanced quantitative and qualitative analyses in the aim to disentangle the complex people-environment interactions linking urban local contexts to healthy aging, with a focus on active living, social networks and participation, and well-being. DISCUSSION: This project will generate evidence about what characteristics of urban environments relate to active mobility, social participation, and well-being, three important dimensions of healthy aging. It also sets the basis for an international research agenda on built environment and healthy aging based on a shared and comprehensive data collection protocol.

What triggers selective daily mobility among older adults? A study comparing trip and environmental characteristics between observed path and shortest path.

Interest is growing in neighborhood effects on health beyond individual's home locations. However, few studies accounted for selective daily mobility bias. Selective mobility of 470 older adults (aged 67-94) living in urban and suburban areas of Luxembourg, was measured through detour percentage between their observed GPS-based paths and their shortest paths. Multilevel negative binomial regression tested associations between detour percentage, trips characteristics and environmental exposures. Detour percentage was higher for walking trips (28%) than car trips (16%). Low-speed areas and connectivity differences between observed and shortest paths vary by transport mode, indicating a potential selective daily mobility bias. The positive effects of amenities, street connectivity, low-speed areas and greenness on walking detour reinforce the existing evidence on older adults' active transportation. Urban planning interventions favoring active transportation will also promote walking trips with longer detours, helping older adults to increase their physical activity levels and ultimately promote healthy aging.

[Environnement résidentiel et vieillissement en santé : le rôle de l'activité physique et de la participation sociale].

Le vieillissement démographique est un des défis majeurs du 21e siècle. Il pose directement la question du « vieillissement en santé ¼, un processus aidant les personnes âgées à rester en bonne santé et indépendantes le plus longtemps possible. L'influence des facteurs environnementaux sur ce processus peut varier selon les individus et leurs comportements. L'enchevêtrement de ces facteurs représente un défi autant théorique que méthodologique. Cet article a pour objectifs i) de quantifier les associations entre l'environnement physique et social du quartier des personnes âgées et leur vieillissement en santé et ii) d'examiner si leur activité physique et leur participation sociale jouent un rôle de médiation dans ces associations. Si certaines caractéristiques du quartier relatives à la réputation, l'accès aux services, et la cohésion sociale sont associées au vieillissement en santé, il existe un soutien limité à l'idée que les comportements tiennent un rôle d'intermédiaire dans cette relation.

[End-stage nephropathy in type 1-diabetes mellitus - kidney transplantation alone or combined with islet or pancreas transplantation?]. / Der nierenkranke Patient mit Typ 1-Diabetes mellitus - Nierentransplantation allein oder mit Insel- oder Pankreastransplantation?

Due to the recent changes in reimbursement politics in islet and pancreas transplantation in Switzerland, the question, which patients with type 1-diabetes mellitus get which form of beta-cell replacement, is of utmost importance for referring physicians. As of July 1, 2010 all forms of islet- or pancreas-transplantations are reimbursed by the Swiss health care system. The limited availability of donor organs and the necessity of transplantation of the islets of several pancreata in order to achieve insulin independence has led to a change in paradigms in Switzerland, where insulin independence by multiple islet transplantations is not the key goal in islet transplantation any longer. The primary goal is achieving a good blood glucose control and avoidance of severe hypoglycaemic episodes. This goal can be achieved in 80 - 90 % of all patients. Only if this goal cannot be achieved by a single islet transplantation, a second or third islet transplantation is performed. By adapting this strategy more patients can benefit from this new therapy. Unlike the North American centers, the Swiss centers in Zurich and Geneva concentrated their efforts on islet after kidney and simultaneous islet kidney transplantation. Due to the organ donor shortage in Switzerland, 50 % of kidney transplants are nowadays living-organ donations, therefore this option has to be included in the decision tree of a beta cell replacement. The choice between islet and pancreas transplantation depends on the existence of diabetes complications (because the perioperative risk is considerably higher in pancreas transplantation) and the potential benefit of a pancreas- or islet transplantation. The first question in the decision tree is, therefore, whether the patient with type 1-diabetes and severe renal failure is a potential candidate for simultaneous pancreas-islet transplantation. If the perioperative risk is considered to be too high, or if revascularisation procedures cannot be done before transplantation, the patient qualifies only for islet transplantation. If a living organ donation for the kidney is possible and the patient not yet on dialysis then the patient can be listed for simultaneous islet-kidney or pancreas-kidney-transplantation. If dialysis is imminent or already performed, a living-donor kidney should be transplanted with the option of a later islet- or pancreas after kidney transplantation. If the patient with type 1-diabetes mellitus is able to maintain a reasonable glycemic level, he would be a good candidate for islet transplantation. If the patient is willing to take the additional risk of complications associated with a pancreas transplant, was never able to maintain a good glycated haemoglobin, has an acceptable perioperative risk, and wishes to become insulin-independent, a simultaneous pancreas-kidney transplant would be recommended. If the kidney has already been transplanted previously, a pancreas- after kidney transplantation would be the procedure of choice. An islet or pancreas transplantation alone is reserved for the patient with type 1-diabetes with a good renal function and frequent life-threatening hypoglycemias, which have to be balanced against the risks of a life-long immunosuppression. In this review article the advantages, disadvantages, and current indications for both beta-cell replacement options in Switzerland are discussed in the light of the available evidence with the help of a new flow chart.

Arthritogenic monoclonal antibodies from K/BxN mice.

Arthritis in the K/BxN mouse model is provoked by pathogenic antibodies (Abs) directed against a ubiquitously expressed protein, glucose-6-phosphate isomerase (GPI). To begin dissecting the repertoire of arthritogenic immunoglobulins (Igs) in the K/BxN model, and to provide a basis for comparison with RA patients we have generated anti-GPI monoclonal Abs (mAbs) from spontaneously activated B cells in the lymphoid organs of arthritic mice. B cell clones with anti-GPI specificities were present at extraordinarily high frequencies in the spleen, and less frequently in other lymphoid organs and in the synovial fluid. None of the anti-GPI mAbs induced arthritis when injected individually into healthy recipients, but most were effective when combined in pairs or larger pools. Arthritogenic combinations depended on mAbs of the IgG1 isotype, which bound to GPI with Kd in the 10(-9) M range, with no indication of cooperative binding between complementing pairs. Pathogenicity was not associated with recognition of a particular epitope, but the ability to form mAb/GPI multimers by simultaneous recognition of different epitopes was clearly required, consistent with the known role of complement and FcRs in this model. Sequence analysis revealed structural similarities amongst the mAbs, indicating that a particular subset of B cells may evade tolerance in K/BxN mice, and that affinity maturation by somatic mutation likely takes place. These results confirm that GPI itself, rather than a cross-reactive molecule, is the target of pathogenic Igs.