Influence of phase of respiratory cycle on ultrasound imaging of deep abdominal muscle thickness.

BACKGROUND: It is difficult to evaluate the transversus abdominis (TrA) and internal oblique (IO) due to their dual role in both trunk control and breathing. OBJECTIVES: To investigate whether TrA and IO thickness as measured by ultrasound differs across the respiratory cycle in upright standing. DESIGN: Observational study. METHODS: Thickness of TrA and IO was measured with ultrasound in 67 subjects in upright standing. Measures were performed 3 times and by 2 assessors, at the end of relaxed expiration, at the end of a full inspiration, and at the end of full expiration. Differences were assessed by ANOVA. Intra- and inter-rater reliability (of a single measure and the average of 3 measures) were assessed by intra-class correlation (ICC). RESULTS: Thickness of the TrA and IO was higher at full expiration than at the end of relaxed expiration (p < 0.001), and in turn compared to at full inspiration (p < 0.001). Intra-rater reliability was excellent at all respiratory phases (ICC 0.76-0.87). Whereas inter-rater reliability for a single measure was only fair to good for TrA (ICC 0.52-0.71) and good to excellent for IO (ICC 0.61-0.78), the inter-rater reliability of the average was excellent at all respiratory phases (ICC 0.75-0.90). CONCLUSIONS: Thickness of TrA and IO increases when lung volume decreases. The intra- and inter-rater reliability of an average measure were excellent at the end of relaxed expiration, full inspiration and full expiration. This provides new opportunities to evaluate the deep abdominal muscles, and their role in respiration, in a physiotherapeutic setting.

Environmental Fate of RNA Interference Pesticides: Adsorption and Degradation of Double-Stranded RNA Molecules in Agricultural Soils.

Double-stranded RNA (dsRNA) pesticides are a new generation of crop protectants that interfere with protein expression in targeted pest insects by a cellular mechanism called RNA interference (RNAi). The ecological risk assessment of these emerging pesticides necessitates an understanding of the fate of dsRNA molecules in receiving environments, among which agricultural soils are most important. We herein present an experimental approach using phosphorus-32 (32P)-radiolabeled dsRNA that allows studying key fate processes of dsRNA in soils with unprecedented sensitivity. This approach resolves previous analytical challenges in quantifying unlabeled dsRNA and its degradation products in soils. We demonstrate that 32P-dsRNA and its degradation products are quantifiable at concentrations as low as a few nanograms of dsRNA per gram of soil by both Cerenkov counting (to quantify total 32P-activity) and by polyacrylamide gel electrophoresis followed by phosphorimaging (to detect intact 32P-dsRNA and its 32P-containing degradation products). We show that dsRNA molecules added to soil suspensions undergo adsorption to soil particle surfaces, degradation in solution, and potential uptake by soil microorganisms. The results of this work on dsRNA adsorption and degradation advance a process-based understanding of the fate of dsRNA in soils and will inform ecological risk assessments of emerging dsRNA pesticides.

Functioning Without Cartilage: Older People With Radiographic Knee Osteoarthritis Who Self-Report No Functional Limitations Do Score Lower on a Performance Battery.

The majority of the older population shows signs of radiographic knee osteoarthritis. However, many remain without functional complaints for a long period. This study aims to find early functional changes associated with stages of radiographic knee osteoarthritis. A group of older people without self-reported complaints was divided in two groups: knee osteoarthritis (K&L = 2-4, N = 29) and control (K&L = 0-1, N = 31). Muscle function was assessed with voluntary and electrically-stimulated isometric knee contractions, including a fatigue test. Physical functioning was assessed with a 6-min walk test (6MWT), a stair climb test (SCT), and a short performance battery. There were no differences in muscle function parameters, 6MWT, and SCT between groups. A clinically relevant lower score on the performance battery was found in participants with knee osteoarthritis. In conclusion, even when older people indicate to have no functional limitations, a decline in functional outcome can be measured with a physical performance battery.

Mosquito Rasputin interacts with chikungunya virus nsP3 and determines the infection rate in Aedes albopictus.

BACKGROUND: Chikungunya virus (CHIKV) is an arthritogenic alphavirus (family Togaviridae), transmitted by Aedes species mosquitoes. CHIKV re-emerged in 2004 with multiple outbreaks worldwide and recently reached the Americas where it has infected over a million individuals in a rapidly expanding epidemic. While alphavirus replication is well understood in general, the specific function (s) of non-structural protein nsP3 remain elusive. CHIKV nsP3 modulates the mammalian stress response by preventing stress granule formation through sequestration of G3BP. In mosquitoes, nsP3 is a determinant of vector specificity, but its functional interaction with mosquito proteins is unclear. METHODS: In this research we studied the domains required for localization of CHIKV nsP3 in insect cells and demonstrated its molecular interaction with Rasputin (Rin), the mosquito homologue of G3BP. The biological involvement of Rin in CHIKV infection was investigated in live Ae. albopictus mosquitoes. RESULTS: In insect cells, nsP3 localized as cytoplasmic granules, which was dependent on the central domain and the C-terminal variable region but independent of the N-terminal macrodomain. Ae. albopictus Rin displayed a diffuse, cytoplasmic localization, but was effectively sequestered into nsP3-granules upon nsP3 co-expression. Site-directed mutagenesis showed that the Rin-nsP3 interaction involved the NTF2-like domain of Rin and two conserved TFGD repeats in the C-terminal variable domain of nsP3. Although in vitro silencing of Rin did not impact nsP3 localization or CHIKV replication in cell culture, Rin depletion in vivo significantly decreased the CHIKV infection rate and transmissibility in Ae.albopictus. CONCLUSIONS: We identified the nsP3 hypervariable C-terminal domain as a critical factor for granular localization and sequestration of mosquito Rin. Our study offers novel insight into a conserved virus-mosquito interaction at the molecular level, and reveals a strong proviral role for G3BP homologue Rin in live mosquitoes, making the nsP3-Rin interaction a putative target to interfere with the CHIKV transmission cycle.

Effects of self-reported osteoarthritis on physical performance: a longitudinal study with a 10-year follow-up.

BACKGROUND AND AIMS: Osteoarthritis (OA) of the knee or hip is associated with limitations in activities of daily life. There are only a few long-term studies on how knee or hip OA affects the course of physical performance. The aim of this study was to investigate the effects of knee or hip OA on physical performance during a follow-up period of 10 years. METHODS: Participants in the Longitudinal Aging Study Amsterdam with self-reported hip or knee OA (N = 155) were prospectively followed for 10 years on 4 occasions from the onset of OA and compared to participants without OA (N = 1004). Physical performance was tested with walk, chair stand and balance tests. Scores for each test were summed to a total performance score (range 0-12), higher scores indicating better performance. Generalized estimating equations were used to analyze differences between participants with and without OA, unadjusted as well as adjusted for confounders. RESULTS: There was a significant interaction between OA and sex (P = 0.068). Both in men and women, total performance was lower for participants with OA, with greater differences in men. Chair stand and walking performance (P < 0.05), but not balance, were lower in participants with OA. After adjustment for confounders, these associations remained significant in men but not in women. Additional analyses correcting for follow-up duration and attrition showed lower performance scores for men and women with OA. CONCLUSIONS: OA negatively affected physical performance 3-6 years after it was first reported. Performance in men with OA was more affected than in women.

Effect of stimulation intensity on assessment of voluntary activation.

INTRODUCTION: The interpolated twitch technique is often used to assess voluntary activation (VA) of skeletal muscles. We investigated VA and the voluntary torque-superimposed torque relationship using either supramaximal nerve stimulation or better tolerated submaximal muscle stimulation, which is often used with patients. METHODS: Thirteen healthy subjects performed maximal and submaximal isometric knee extensions with superimposed maximal or submaximal doublets (100 Hz). RESULTS: Superimposed torque relative to potentiated resting doublets was smaller with maximal nerve than with submaximal muscle stimulation. Maximal VA was 87 ± 7% and 93 ± 5% for submaximal muscle and maximal nerve stimulation, respectively. The individual voluntary torque-superimposed torque relationships were more linear for submaximal muscle stimulation, possibly leading to less overestimation of VA. CONCLUSIONS: Submaximal muscle stimulation can be used to estimate VA in the knee extensors. It is less painful, and overestimation of VA may be less compared with maximal nerve stimulation.