Light Intensity Physical Activity and Sedentary Behavior in Relation to Body Mass Index and Grip Strength in Older Adults: Cross-Sectional Findings from the Lifestyle Interventions and Independence for Elders (LIFE) Study

BackgroundIdentifying modifiable determinants of fat mass and muscle strength in older adults is important given their impact on physical functioning and health. Light intensity physical activity and sedentary behavior are potential determinants, but their relations to these outcomes are poorly understood. We evaluated associations of light intensity physical activity and sedentary time—assessed both objectively and by self-report—with body mass index (BMI) and grip strength in a large sample of older adults.MethodsWe used cross-sectional baseline data from 1130 participants of the Lifestyle Interventions and Independence for Elders (LIFE) study, a community-dwelling sample of relatively sedentary older adults (70-89 years) at heightened risk of mobility disability. Time spent sedentary and in light intensity activity were assessed using an accelerometer worn for 3–7 days (Actigraph GT3X) and by self-report. Associations between these exposures and measured BMI and grip strength were evaluated using linear regression.ResultsGreater time spent in light intensity activity and lower sedentary times were both associated with lower BMI. This was evident using objective measures of lower-light intensity, and both objective and self-reported measures of higher-light intensity activity. Time spent watching television was positively associated with BMI, while reading and computer use were not. Greater time spent in higher but not lower intensities of light activity (assessed objectively) was associated with greater grip strength in men but not women, while neither objectively assessed nor self-reported sedentary time was associated with grip strength.ConclusionsIn this cross-sectional study, greater time spent in light intensity activity and lower sedentary times were associated with lower BMI. These results are consistent with the hypothesis that replacing sedentary activities with light intensity activities could lead to lower BMI levels and obesity prevalence among the population of older adults. However, longitudinal and experimental studies are needed to strengthen causal inferences.     

Increased expression of costimulatory markers CD134 and CD80 on interleukin-17 producing T cells in patients with systemic lupus erythematosus

Introduction  

There is growing evidence that interleukin 17 (IL-17) producing T cells are involved in the pathogenesis of systemic lupus erythematosus (SLE). Previous studies showed that increased percentages of T-cell subsets expressing the costimulatory molecules CD80 and CD134 are associated with disease activity and renal involvement in SLE. The aim of this study was to investigate the distribution and phenotypical characteristics of IL-17 producing T-cells in SLE, in particular in patients with lupus nephritis, with emphasis on the expression of CD80 and CD134.     

The Role of Climate in Settlement and Landscape Change in the North Atlantic Islands: An Assessment of Cumulative Deviations in High-Resolution Proxy Climate Records

In order to assess possible contributions of climate change to the human ecology of the North Atlantic islands we evaluate the utility of cumulative deviations from the mean, calculated for the Greenland ice core storm frequency proxy (GISP2 Na⁺) and sea ice proxy (GISP2 chloride excess). Our aim is to identify episodes of unpredictable change in the context of long-term trends of cultural and environmental development. Key changes are identified in the proxy climate records in 975 and 980 ad, 1025 and 1040 ad, 1180 ad, 1425 and 1450 ad, and 1520 and 1525 ad. Some of these changes are consistent with those inferred from new studies of the palaeoecological record of the Faroes. This indicates that the cumulative deviation measure could give greatest prominence to the most important climate changes affecting landscapes and settlement (such as the changes of 1425 and 1450 ad and their immediate aftermath), rather than extreme events, such as great single storms.     

Shifts in the psychophysical function in rats

The primary goal was to compare results from a free-operant procedure with pigeons [Machado, A., Guilhardi, P., 2000. Shifts in the psychometric function and their implications for models of timing. J. Exp. Anal. Behav. 74, 25-54, Experiment 2] with new results obtained with rats. The secondary goal was to compare the results of both experiments with dependent variables that were not used in the original publication. As in the original study with pigeons, rats were trained on a two-alternative free-operant psychophysical procedure in which left lever press responses were reinforced during the first and second quarters of a 60-s trial, and right lever press responses were reinforced during the third and fourth quarters of the trial. The quarters were reinforced according to four independent variable interval (VI) schedules of reinforcement. The VI duration was manipulated in each quarter, and shifts in the psychophysical functions that relate response rate with time since trial onset were measured. The results obtained with rats were consistent with those previously obtained with pigeons. In addition, results not originally reported were also consistent between rats and pigeons, and provided insights into the perception, memory, and decision processes in Scalar Expectancy Theory and Learning-to-Time Theory.     

Fungal lysis by a soil bacterium fermenting cellulose

Recycling of plant biomass by a community of bacteria and fungi is fundamental to carbon flow in terrestrial ecosystems. Here we report how the plant fermenting, soil bacterium Clostridium phytofermentans enhances growth on cellulose by simultaneously lysing and consuming model fungi from soil. We investigate the mechanism of fungal lysis to show that among the dozens of different glycoside hydrolases C. phytofermentans secretes on cellulose, the most highly expressed enzymes degrade fungi rather than plant substrates. These enzymes, the GH18 Cphy1799 and Cphy1800, synergize to hydrolyse chitin, a main component of the fungal cell wall. Purified enzymes inhibit fungal growth and mutants lacking either GH18 grow normally on cellulose and other plant substrates, but have a reduced ability to hydrolyse chitinous substrates and fungal hyphae. Thus, C. phytofermentans boosts growth on cellulose by lysing fungi with its most highly expressed hydrolases, highlighting the importance of fungal interactions to the ecology of cellulolytic bacteria.     

Extending reference assembly models

The human genome reference assembly is crucial for aligning and analyzing sequence data, and for genome annotation, among other roles. However, the models and analysis assumptions that underlie the current assembly need revising to fully represent human sequence diversity. Improved analysis tools and updated data reporting formats are also required.     

The modular structure of haemagglutinin/adhesin regions in gingipains of Porphyromonas gingivalis

High-molecular-weight arginine- and lysine-specific (Kgp) gingipains are essential virulence factors expressed by the oral pathogen Porphyromonas gingivalis. Haemagglutinin/adhesin (HA) regions of these proteases have been implicated in targeting catalytic domains to biological substrates and in other adhesive functions. We now report the crystal structure of the K3 adhesin domain/module of Kgp, which folds into the distinct β-jelly roll sandwich topology previously observed for K2. A conserved structural feature of K3, previously observed in the Kgp K2 module, is the half-way point anchoring of the surface exposed loops via an arginine residue found in otherwise highly variable sequences. Small-angle X-ray scattering data for the recombinant construct K1K2K3 confirmed a structure comprising a tandem repeat of three homologous modules, K1, K2 and K3 while also indicating an unusual 'y'-shape arrangement of the modules connected by variable linker sequences. Only the K2 and K3 modules and a K1K2 construct were observed to be potently haemolytic. K2, K3 and the K1K2 construct showed preferential recognition of haem-albumin over albumin whereas only low affinity binding was detected for K1 and the K1K2K3 construct. The data indicate replication of some biological functions over the three adhesin domains of Kgp while other functions are restricted.