Energy balance of human locomotion in water

In this paper a complete energy balance for water locomotion is attempted with the aim of comparing different modes of transport in the aquatic environment (swimming underwater with SCUBA diving equipment, swimming at the surface: leg kicking and front crawl, kayaking and rowing). On the basis of the values of metabolic power (Ė), of the power needed to overcome water resistance (_d) and of propelling efficiency (_P=_d/_tot, where _tot is the total mechanical power) as reported in the literature for each of these forms of locomotion, the energy cost per unit distance (C=Ė/v, where v is the velocity), the drag (performance) efficiency (_d=_d/Ė) and the overall efficiency (_o=_tot/Ė=_d/_P) were calculated. As previously found for human locomotion on land, for a given metabolic power (e.g. 0.5 kW=1.43 l·min^–1 O₂) the decrease in C (from 0.88 kJ·m^–1 in SCUBA diving to 0.22 kJ·m^–1 in rowing) is associated with an increase in the speed of locomotion (from 0.6 m·s^–1 in SCUBA diving to 2.4 m·s^–1 in rowing). At variance with locomotion on land, however, the decrease in C is associated with an increase, rather than a decrease, of the total mechanical work per unit distance (W_tot, kJ·m^–1). This is made possible by the increase of the overall efficiency of locomotion (_o=_tot/Ė=W_tot/C) from the slow speeds (and loads) of swimming to the high speeds (and loads) attainable with hulls and boats (from 0.10 in SCUBA diving to 0.29 in rowing).     

Mumps outbreak in a highly vaccinated student population,The Netherlands, 2004

In September 2004 a mumps outbreak occurred at an international hotel school in The Netherlands. We investigated this outbreak to identify risk factors for mumps. There were 105 mumps cases (overall mumps attack rate (AR) 12% (95% CI: 10–15%)). The AR for Dutch vaccinated and unvaccinated participants was 12% (95% CI: 10–15%) and 15% (95% CI: 3–42%), respectively. Independent risk factor was mumps contact. Explanations for the relatively high AR among vaccinated participants include primary vaccine failure, waning immunity and incomplete vaccine-induced immunity in the context of high mumps virus exposure in a school party and a crowded boarding school.     

Food insecurity and mental health: Surprising trends among community health volunteers in Addis Ababa,Ethiopia during the 2008 food crisis

The 2008 food crisis may have increased household food insecurity and caused distress among impoverished populations in low-income countries. Policy researchers have attempted to quantify the impact that a sharp rise in food prices might have on population wellbeing by asking what proportion of households would drop below conventional poverty lines given a set increase in prices. Our understanding of the impact of food crises can be extended by conducting micro-level ethnographic studies. This study examined self-reported household food insecurity (FI) and common mental disorders (CMD) among 110 community health AIDS care volunteers living in Addis Ababa, Ethiopia during the height of the 2008 food crisis. We used generalized estimating equations that account for associations between responses given by the same participants over 3 survey rounds during 2008, to model the longitudinal response profiles of FI, CMD symptoms, and socio-behavioral and micro-economic covariates. To help explain the patterns observed in the response profiles and regression results, we examine qualitative data that contextualize the cognition and reporting behavior of AIDS care volunteers, as well as potential observation biases inherent in longitudinal, community-based research. Our data show that food insecurity is highly prevalent, that is it associated with household economic factors, and that it is linked to mental health. Surprisingly, the volunteers in this urban sample did not report increasingly severe FI or CMD during the peak of the 2008 food crisis. This is a counter-intuitive result that would not be predicted in analyses of population-level data such as those used in econometrics simulations. But when these results are linked to real people in specific urban ecologies, they can improve our understanding of the psychosocial consequences of food price shocks.     

Direct observations of the kinetics of migrating T cells suggest active retention by endothelial cells with continual bidirectional migration

The kinetics and regulatory mechanisms of T cell migration through the endothelium have not been fully defined. In experimental, filter-based assays in vitro, transmigration of lymphocytes takes hours, compared with minutes, in vivo. We cultured endothelial cell (EC) monolayers on filters, solid substrates, or collagen gels and treated them with TNF-alpha, IFN-gamma, or both prior to analysis of lymphocyte migration in the presence or absence of flow. PBL, CD4+ cells, or CD8+ cells took many hours to migrate through EC-filter constructs for all cytokine treatments. However, direct microscopic observations of EC filters, which had been mounted in a flow chamber, showed that PBL crossed the endothelial monolayer in minutes and were highly motile in the subendothelial space. Migration through EC was also observed on clear plastic, with or without flow. After a brief settling without flow, PBL and isolated CD3+ or CD4+ cells crossed EC in minutes, but the numbers of migrated cells varied little with time. Close observation revealed that lymphocytes migrated back and forth continuously across endothelium. Under flow, migration kinetics and the proportions migrating back and forth were altered little. On collagen gels, PBL again crossed EC in minutes and migrated back and forth but showed little penetration of the gel over hours. In contrast, neutrophils migrated efficiently through EC and into gels. These observations suggest a novel model for lymphoid migration in which EC support migration but retain lymphocytes (as opposed to neutrophils), and additional signal(s) are required for onward migration.     

Do parents understand the medical information provided in paediatric emergency departments? A prospective multicenter study

Aim: We evaluated the extent to which parents understood the medical information about hospitalization of their child in an emergency department and looked for characteristics likely to increase the risk of poor comprehension. Methods: Prospective multicenter study in thirteen paediatric emergency departments. The parents and doctors completed questionnaires based on closed‐ended questions with a common core of four items: reasons of hospitalization, diagnosis, treatment and seriousness of child condition. We evaluated concordance between parents and doctor answers for these items by comparing their responses. Results: This study included 380 parents. Percentage of concordance was 55% for the reason of hospitalization, 78% for the diagnosis, 92% for the treatment, 48% for the seriousness of the condition and 19% for all four items. The mean number of concordant items was 2.76 (CI 95%, 2.66–2.86). Parents whose children seemed not in pain and parents who received additional information from the nurse showed significantly slightly higher levels of concordance with doctor’s answers (2.98 vs 2.66, p = 0.006 and 2.89 vs 2.60, p = 0.004, respectively). Conclusion: This study shows that improvements are required in the clarity of the information delivered to the parents. The assistance of nurses and optimal pain management may help to improve communication.     

Growth in X-linked hypophosphatemic rickets

Growth failure appears frequently in children with X-linked hypophosphatemic rickets (XLHR) due to hypophosphatemia, disease severity, body disproportion, and primary bone abnormality. Recombinant human growth hormone (rhGH) increases phosphate tubular reabsorption and phosphate level in blood and, thus, constitutes an attractive but controversial therapy in short children with XLHR, those efficacy was demonstrated in small uncontrolled series. Our aim was to report our experience regarding growth in XLHR. Twenty-seven children with XLHR—20 girls, seven boys—diagnosed at a median (md) of 1.46 years of age, (range 0.39–8.5 years), were studied at 10.12 years of age (1.58–18.56), md (range). All received oral treatment with phosphate and calcitriol. At the first visit, grouped Z-height was −1; (−4.58; 0.54) md (range). After 5 years’ follow-up (0.92–15.6), Z-height was −0.91 (− 4.56; 0.17), not different from that at baseline (P = 0.465). In 16 children entirely controlled in our program upon presentation, a “catch up” phenomenon after the rickets had healed (P = 0.823) or throughout the long-term was not observed (P = 0.995). Eight patients had a Z-height ≤ −2SD at the last visit, and impaired linear growth was associated with age >2 years at diagnosis, male gender and non-adherence to treatment. Four children, all boys, received rhGH, and in two cases with sufficient follow up stature normalized. No rhGH side effects were observed, and phosphate and calcitriol doses remained stable. Linear growth failure appeared in a third of XLHR children. Efforts need to be made to reduce the age of diagnosis and to improve adherence to treatment. Treatment with rhGH should be considered early, after the rickets has been controlled, in those patients with impaired growth or delayed diagnosis.     

Ghrelin concentrations reflect body mass index rather than feeding status in obese girls

Ghrelin stimulates both appetite and secretion of growth hormone (GH). We hypothesized that fasting should increase ghrelin, thereby increasing GH concentrations in obesity. Eight obese girls underwent a 48-h fast, receiving 25% of calories for ideal body weight. Blood was obtained every 15 min for the last 24 h of the fast. Four months later, six obese girls had blood obtained in the fed state. Two additional obese and five lean girls had blood obtained in the fed state. Ghrelin was determined in 3-h pools. Mean ghrelin concentrations were 0.41 +/- 0.03 ng/mL for lean girls and 0.16 +/- 0.01 ng/mL in obese fed girls (p < 0.0001). Lean fed girls had diurnal variation of ghrelin whereas obese fed girls did not. Fasting neither increased ghrelin (0.18 +/- 0.01 ng/mL) nor restored diurnal variation. Ghrelin concentrations were related to the body mass index (BMI) SD score (SDS) (r = 0.45, p = 0.005). For the six obese girls who participated in both fasting and fed studies, change in mean ghrelin concentration between studies was related to change in BMI SDS but not fed or fasting state. Ghrelin concentrations are, thus, a function of BMI rather than feeding status in obese girls.     

Mortality in the catastrophic antiphospholipid syndrome: causes of death and prognostic factors

In order to know the causes of death and the prognostic factors, our group analyzed 250 patients included until February 2005 in the web-site based international registry of patients with catastrophic antiphospholipid syndrome (APS) ("CAPS Registry") (http://www.med.ub.es/MIMMUN/FORUM/CAPS.HTM). Cerebral involvement, mainly consisting of stroke, followed by cardiac involvement and infections were considered the main causes of death in patients with catastrophic APS. The presence of systemic lupus erythematosus was related with higher mortality. According to the results of this analysis, anticoagulation plus steroids plus plasma exchange should be the first line of therapy in patients with catastrophic APS.     

Ca2+ signalling in urethral interstitial cells of Cajal

Interstitial cells of Cajal (ICC) in the urethra have been proposed as specialized pacemakers that are involved in the generation of urethral tone and therefore the maintenance of urinary continence. Recent studies on freshly dispersed ICC from the urethra of rabbits have demonstrated that pacemaker activity in urethra ICC is characterized by spontaneous transient depolarizations (STDs) under current clamp and spontaneous transient inward currents (STICs) under voltage clamp. When these events were simultaneously recorded with changes in intracellular Ca²⁺ (using a Nipkow spinning disk confocal microscope) they were found to be associated with global Ca²⁺ oscillations. In this short review we will consider some of these recent findings regarding the contribution of intracellular Ca²⁺ stores and Ca²⁺ influx to the generation of pacemaker activity in urethral ICC with particular emphasis on the contribution of reverse Na⁺/Ca²⁺ exchange (NCX).