Effects of insect opportunists on a four-level trophobiotic system involving nectar-producing galls of the cynipid wasp Disholcaspis quercusmamma (Hymenoptera: Cynipidae)

The induction of plant galls is considered an adaptive life history trait found in many insect groups. The formation of galls provides several advantages to the gall maker, such as enhanced nutrition, favorable microclimate, and protection from natural enemies, including parasitoids, inquilines, and predators. Order Hymenoptera has many gall-making species, belonging to the gall wasp family Cynipidae. As an extended phenotype of the gall makers, some galls exhibit very sophisticated adaptive mechanisms involving multilevel species interactions. In particular, the oak galls of the Cynipid species Disholcaspis quercusmamma, found in much of Illinois, produce a palatable, sugary nectar-like secretion, attracting other insects. It is hypothesized that visiting insects discourage potential parasitoids and inquilines questing for oviposition sites within the galls, possibly producing an enemy-free space. Several studies on the species interactions involved in this four-level trophobiotic association have examined the role of visiting ant species in the system. However, other insect species have also been observed to be attracted to the extrafloral nectar of the galls, and their roles in the gall wasp-natural enemy interaction system have not yet been studied. This study aimed to examine the effects of all visiting insects, including ants, on the success of the gall-makers as a result of potentially reduced parasitism. Exclusion experiments were carried out on three oak trees in study sites in central Illinois. Statistical analyses of field data found no effect of treatment on gall wasp success, parasitism, or inquilinism. However, additional tests showed a positive correlation between gall wasp success and inquilinism rate compared to gall cluster size. Gall diameter correlated positively with gall maker success and negatively with inquilinism rate. This suggests an underlying complexity to the system. Additional research is necessary to better understand this uniquely adapted relationship

Enzyme activity below the dynamical transition at 220 K

Enzyme activity requires the activation of anharmonic motions, such as jumps between potential energy wells. However, in general, the forms and time scales of the functionally important anharmonic dynamics coupled to motion along the reaction coordinate remain to be determined. In particular, the question arises whether the temperature-dependent dynamical transition from harmonic to anharmonic motion in proteins, which has been observed experimentally and using molecular dynamics simulation, involves the activation of motions required for enzyme function. Here we present parallel measurements of the activity and dynamics of a cryosolution of glutamate dehydrogenase as a function of temperature. The dynamical atomic fluctuations faster than ~100 ps were determined using neutron scattering. The results show that the enzyme remains active below the dynamical transition observed at ~220 K, i.e., at temperatures where no anharmonic motion is detected. Furthermore, the activity shows no significant deviation from Arrhenius behavior down to 190 K. The results indicate that the observed transition in the enzyme's dynamics is decoupled from the rate-limiting step along the reaction coordinate

155?Sex-related differences in muscle co-activation in individuals with knee osteoarthritis

Background: Sex-related differences in muscle function have been well established in healthy individuals. In individuals with knee osteoarthritis (KOA), impairments in muscle function such as muscle weakness and high muscle co-activation have also been demonstrated. Muscle dysfunction has been shown to be a strong contributor to poor physical function and low health-related quality of life in patients with KOA. The purpose of this study was, therefore, to analyse sex and osteoarthritis-related differences in muscle function, to establish to what extent both sex and disease status contribute to muscle dysfunction.Methods: Muscle co-activation was assessed in 77 symptomatic KOA participants (62.5±8.1yrs; 48/29 women/men) and 18 age-matched asymptomatic controls (62.5±10.4yrs; 9/9 women/men), using electromyography (EMG) during a series of walking, stair ascent and descent and sit-to-walk activities. EMG was recorded from 7 sites medial/lateral gastrocnemius, biceps femoris, semitendinosus, vastus lateralis/medialis and normalised to maximal voluntary contraction. Normalised EMG was used to calculate hamstrings-quadriceps and medial-lateral muscle co-activation as (antagonist/agonist) *(antagonist+agonist). The stance phase of walking was split into pre-stance (150ms prior to initial contact), loading (0-15% of stance), early-stance (15-40%), mid-stance (40-60%), late-stance (60-100%) and overall-stance (0-100%). Stairs negotiation was also split into transition (stance phase on the floor) and continuous (stance phase on the second step of the staircase). All participants provided written informed consent and the study was approved by Research Ethics committees (HLS12/86, 13/ws/0146). Independent samples T-tests were performed to assess the differences between KOA and controls. Linear regressions were performed to investigate the relationship between muscle function, sex and disease status, and Bonferroni corrected for multiple comparisons.Results: Individuals with KOA were weaker than controls (P < 0.007). Overall there were very few differences in muscle co-activation between KOA and controls. Women were weaker than men (P ⩽ 0.002) and had higher hamstrings-quadriceps and medial-lateral muscle co-activation across all activities of daily living. In multiple regression analyses sex and muscle weakness, but not age or disease status, predicted high muscle co-activation.Conclusion: High muscle co-activation was associated with female sex and muscle weakness regardless of disease status and age. It has previously been suggested that muscle co-activation acts as a compensatory mechanism for muscle weakness, accommodating for the diminished force generating capabilities to maintain a certain level of function and movement activation patterns. This suggests that muscle weakness may be the main contributing factor for high muscle co-activation which is thought to increase joint loads with detrimental effects on cartilage and joint integrity. This may explain high muscle co-activation in women with muscle weakness and increased risk of incidence and progression of KOA in women

Validation of Ray Tracing Code Refraction Effects

NASA's current predictive capabilities using the ray tracing program (RTP) are validated using helicopter noise data taken at Eglin Air Force Base in 2007. By including refractive propagation effects due to wind and temperature, the ray tracing code is able to explain large variations in the data observed during the flight test

Longer Electromechanical Delay Impairs Hamstrings Explosive Force versus Quadriceps

Introduction Explosive neuromuscular performance refers to the ability to rapidly increase force in response to neuromuscular activation. The lower explosive force production of the hamstrings relative to the quadriceps could compromise knee joint stability and increase the risk of anterior cruciate ligament injury. However, the time course of the rise in explosive force of the hamstrings and quadriceps from their initial activation, and thus the explosive hamstrings-to-quadriceps (H/Q) force ratio, has not been documented.Methods The neuromuscular performance of 20 untrained males was assessed during a series of isometric knee flexion and extension contractions, with force and surface EMG of the hamstrings and quadriceps recorded during explosive and maximum voluntary contractions. Hamstrings force was expressed relative to quadriceps force to produce hamstring-to-quadriceps ratios of explosive H/Q force and H/Q maximum voluntary force. For the explosive contractions, agonist electromechanical delay (EMD), agonist and antagonist neural activation were assessed.Results The quadriceps was 79% stronger than the hamstrings, but quadriceps explosive force was up to 480% greater than the hamstrings from 25 to 50 ms after first activation. Consequently, the explosive H/Q force ratio was very low at 25 and 50 ms (0%–17%) and significantly different from H/Q maximum voluntary force ratio (56%). Hamstrings EMD was 95% greater than quadriceps EMD (44.0 vs 22.6 ms), resulting in a 21-ms later onset of force in the hamstrings that appeared to explain the low explosive H/Q force ratio in the early phase of activation.Conclusions Prolonged hamstrings EMD appears to impair early phase (0–50 ms) explosive force production relative to the quadriceps and may render the knee unstable and prone to anterior cruciate ligament injury during this period

Can patient characteristics explain variance in ultrasound strain elastography measures of the quadratus femoris and patellar tendons?

Objectives To explore the associations between participant characteristics and magnitudes of difference in paired elastography measures of knee tendon from different ultrasound systems, and to compare strain elastography pattern description. Materials and Methods Quadriceps and patellar tendons of 20 healthy volunteers (40 tendons) were examined by an experienced operator employing two ultrasound systems (GE S8 and Esaote MyLab 70XVG). Pearson/Spearman correlations explored the influence of participant characteristics (BMI, body fat %, leg circumference, activity level) on the magnitude of differences between measures. Paired-sample t test or Wilcoxon signed rank test were performed to compare repeated measures of individual ultrasound systems. Results The quadriceps tendon was characteristically stiffer than the patellar tendon. Participant characteristics were associated with within machine differences of the distal quadriceps tendon (BMI; r = 0.49, p = 0.028–0.03 and body fat %; r = 0.43, p = 0.05–0.056) ER measures. Conclusions Anthropometric and body composition parameters were associated with within machine differences for elasticity measures, where high BMI and body fat % contribute to paired measurement variance at the distal quadriceps tendon. Strain elastography protocols should be standardised, repeated ER measures performed using the same US system and patient characteristics considered for future clinical applications

Validation and reliability of the Alzheimer’s disease-Commonwealth Scientific and Industrial Research Organisation food frequency questionnaire

Accuracy in measuring intake of dietary constituents is an important issue in studies reporting the associations between diet and chronic diseases. We modified a Commonwealth Scientific and Industrial Research Organisation (CSIRO) food frequency questionnaire (FFQ) to include foods of interest in the field of Alzheimer’s disease (AD) research. The aim of the current study was to determine the reliability and validity of the AD-CSIROFFQ in 148 cognitively normal older adults. The AD-CSIROFFQ was completed before and after completion of a four-day weighed food record. Of the 508 food and beverage items reported, 309 had sufficient consumption levels for analysis of reliability. Of the 309 items, over 78% were significantly correlated between the two questionnaire administrations (Spearman’s rank correlations). We used two additional methods to assess absolute nutrient intake agreement between the AD-CSIROFFQ and the weighed food records (Pearson’s correlation coefficients and Bland–Altman plots) and quintile rankings to measure group level agreement. The adequate correlations observed between questionnaire responses suggest that the AD-CSIROFFQ is reliable. All nutrient intakes were acceptable for ranking of individuals on a group level, whilst the agreement levels with respect to the weighed food records for 11 of the 46 nutrients show validity in terms of their individual level absolute intake. The AD-CSIROFFQ makes an important contribution to the tools available for assessing usual dietary intake in groups of older adults with respect to AD research

Intermachine variation of ultrasound strain elastographic measures of the quadriceps and patellar tendons in healthy participants

ObjectivesTo evaluate intermachine variation and compare intraoperator and interoperator agreement and repeatability characteristics of 2 ultrasound (US) systems for measurements of quadriceps and patellar tendons by strain elastography (SE).MethodsForty tendons from 20 healthy participants were investigated by operators with different experience (operator 1, 12 years of US experience and >50 SE examinations; operator 2, no US experience and 1 day of SE training). Repeated measures were performed on GE Healthcare (Waukesha, WI) and Esaote (Genoa, Italy) US systems. The percentage of agreement, Cohen κ, intraclass correlation coefficient, and correlation tests assessed agreement, repeatability, and associations of SE measures. A paired t test and Wilcoxon signed rank test assessed differences in SE measures. ResultsThe study participants included 5 male and 15 female volunteers (mean [range] age, 29.3 [21–39] years). Better agreement and repeatability characteristics were observed for the patellar compared to the quadriceps tendon and the color score (CS) method over the elasticity ratio (ER). Intraoperator agreement was better for the experienced operator. Intraoperator repeatability was achieved in 55% of ER (intraclass correlation coefficient, 0.40–0.91; P  [less than] .05) and 77% to 85% (κ = –0.25–1) of CS measures. Interoperator repeatability was achieved in 35% (t /z , –2.93–7.94; P  [less than] .001–.048) of all ER measures. No significant differences in proximal (z , –0.13– –0.78) and distal patellar (z , –1.52–2.26; P  > .5) patellar ER measures were observed. Seventy‐four percent to 75% mean agreement (κ = 0–0.5) for CS measures comparable across both US systems was observed. Intermachine ER associations were poor (r = –0.39–0.13; P  > .05), whereas greater than 70% agreement (κ = –0.87–0.53) for the CS was achieved. ConclusionsThe reproducibility of knee tendon SE measurements is influenced by the operator experience, US system, and tendon site

DNA mismatch repair-dependent responses to the food-borne carcinogen 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in the mouse

The DNA mismatch repair (MMR) pathway maintains genomic stability and reduces cancer risk (colorectal and other internal cancers) by correcting polymerase errors and activating cell cycle checkpoints and apoptosis in response to DNA damage. Few studies have examined the influence of commonly encountered environmental mutagens/carcinogens on the etiology of MMR-deficient cancers. 2-Amino-1-methyl-6- phenylimidazo [4,5-bJ pyridine (PhIP) is a cooked-meat mutagen implicated in human colorectal carcinogenesis. To determine whether PhIP represents a cancer risk to individuals with MMR-deficiency, I examined the effect of Mlh1-deficiency on PhIP-induced mutagenesis, turnorigenesis, and cell-turnover responses in mice following exposure to eight intraperitoneal (i.p.) injections of 50 mg/kg PhIP. Mlh1⁻/⁻ mice were hypermutable by PhIP in colon and small intestine (as measured using transgene shuttle vectors), demonstrating specific increases in mutations not typically associated with PhIP. In contrast, G/C to T/A transversions, the "signature PhIP mutation" were similarly induced in Mlh1⁻/⁻ and wild-type mice. In cancer studies, Mlh1⁻/⁻ mice showed heightened susceptibility to induction of colonic aberrant crypt foci (a biomarker for colon carcinogenesis), whereas adenomas of the small intestine and colon were not induced. Cell-turnover responses in Mlh1⁺/⁺ and Mlh1⁻/⁻ mouse colon were evaluated following multiple i.p. injections or a single i.p. injection of 50 mg/kg PhIP. These responses were compared to a single i.p. injection of 80 mg/kg 1 ,2-dimethylhydrazine (DMH). Colonic apoptosis in response to PhIP increased, shifted to predominately the stem cell compartment of colon crypts, and was partially Mlh1-dependent. This response was also rapid, occurring at 8 h after treatment and diminishing by 16 h. Similar effects were observed in DMH-exposed animals. The apoptotic response to PhIP was greater after multiple exposures compared to a single exposure. PhIP-exposure did not notably alter cell proliferation, whereas proliferation was consistently reduced in DMH-treated mice. These results suggest that loss of Mlh1 alters homeostatic functions of the colonic crypt that may contribute to suppression of the mutagenic effects of PhIP. These data are consistent with the hypothesis that PhIP exposure increases mutagenesis and carcinogenesis in Mlh1⁻/⁻ mice, and support further evaluation of the risk that consumption of heterocyclic amines may impart to MMR-deficient individuals