bluuebunny/crossref_metadata_2025 huggingface dataset:
Acid and Aluminum Effects on Sodium Homeostasis and Survival of Acid-Sensitive and Acid-Tolerant Cladocera
Authors: Havens Karl E.
Published: September 2009

Acid-sensitive (Daphnia galeata mendotae) and acid-tolerant (Bosmina longirostris) cladocerans were exposed to 0, 100, or 200 μg Al/L at pH 4.5, 6.0, or 7.5. Whole-body Na content and survivals were determined after 12- and 24-h exposures to the nine treatments. Daphnia galeata mendotae experienced significant decreases in body Na content and survival at pH 4.5. Aluminum effects were pH dependent. At pH 7.5 and 6.0, Na content and survival declined with increasing Al; at pH 4.5, the highest Al concentration enhanced Na content and prolonged survival. Bosmina longirostris Na content and survival were only slightly reduced at pH 4.5, and there were no significant Al or pH × Al interaction effects. The results support the view that (1) the extinction of D. galeata mendotae and the relative increase of B. longirostris during lake acidification are largely due to differential impacts of acid stress on osmoregulation and (2) Al toxicity might also be a factor responsible for D. galeata mendotae population declines, which are most pronounced near pH 6.0.
Isolation and characterization of the ryeWaxygene
Authors: Xu Jie , Frick Michele , Laroche André , Ni Zhong-Fu , Li Bao-Yun , Lu Zhen-Xiang
Published: September 2009

Complete genomic and cDNA sequences of the Waxy gene encoding granule-bound starch synthase I (GBSSI) were isolated from the rye genome and characterized. The full-length rye Waxy genomic DNA and cDNA are 2767 bp and 1815 bp, respectively. The genomic sequence has 11 exons interrupted by 10 introns. The rye Waxy gene is GC-rich, with a higher GC frequency in the coding region, especially in the third position of the codons. Exon regions of the rye Waxy gene are more conserved than intron regions when compared with the homologous sequences of other cereals. The mature rye GBSSI proteins share more than 95% sequence identity with their homologs in wheat and barley. A phylogenetic tree based on sequence comparisons of available plant GBSSI proteins shows the evolutionary relationship among Waxy genes from rye and other plant genomes. The identification of the rye Waxy gene will enable the manipulation of starch metabolism in rye and triticale.
Genetic differentiation of wild and cultivated populations: diversity ofCoffea canephoraPierre in Uganda
Authors: Musoli P. , Cubry P. , Aluka P. , Billot C. , Dufour M. , De Bellis F. , Pot D. , Bieysse D. , Charrier A. , Leroy T.
Published: September 2009

Coffea canephora Pierre ex Frohener is a perennial plant originated from Africa. Two main groups, Guinean and Congolese, have already been identified within this species. They correspond to main refugia in western and central Africa. In this paper we present the analysis of a region that has not yet been studied, Uganda. Two wild, one feral (once cultivated but abandoned for many years), and two cultivated populations of C. canephora from Uganda were evaluated using 24 microsatellite markers. Basic diversity, dissimilarity and genetic distances between individuals, genetic differentiation between populations, and structure within populations were analysed. Expected heterozygosity was high for wild compartments (0.48 to 0.54) and for cultivated and feral ones (0.57 to 0.59), with the number of private alleles ranging from 12 for cultivated genotypes to 37 for a wild compartment. The Ugandan samples show significant population structuring. We compared the Ugandan populations with a representative sample of known genetic diversity groups within the species using 18 markers. Coffea canephora of Ugandan origin was found to be genetically different from previously identified diversity groups, implying that it forms another diversity group within the species. Given its large distribution and extremely recent domestication, C. canephora can be used to understand the effect of refugia colonization on genetic diversity.
Mapping of STS markers obtained from oat resistance gene analog sequences
Authors: Loarce Yolanda , Sanz María Jesús , Irigoyen María Luisa , Fominaya Araceli , Ferrer Esther
Published: September 2009

Two previously isolated resistance gene analogs (RGAs) of oat have been located as RFLPs in the reference map of Avena byzantina ‘Kanota’ × Avena sativa ‘Ogle’ in regions either homologous or homoeologous to loci for resistance to Puccinia coronata , the causal agent of crown rust. In this study, the RGAs were mapped in two recombinant inbred line (RIL) populations that segregate for crown rust resistance: the diploid Avena strigosa × Avena wiestii RIL population (Asw), which has been used for mapping the complex locus PcA, and the hexaploid MN841801-1 × Noble-2 RIL population (MN), in which QTLs have been located. To obtain single-locus markers, RGAs were converted to sequence tagged site (STS) markers using a procedure involving extension of the original RGA sequence lengths by PCR genome walking, amplification and cloning of the parental fragments, and identification of single nucleotide polymorphisms. The procedure successfully obtained STSs from different members of the L7M2 family of sequences, the initial NBS of which have nucleotide similarities of >83%. However, for RGA III2.18, the parental lines were not polymorphic for the STSs assayed. A sequence characterized amplified region (SCAR) marker with features of an RGA had been previously identified for gene Pc94. This marker was also mapped in the above RIL populations. Markers based on RGA L7M2 co-localized with markers defining the QTL Prq1a in linkage group MN3, and were located 15.2 cM from PcA in linkage group AswAC. The SCAR marker for Pc94 was also located in the QTL Prq1a but at 39.5 cM from PcA in AswAC, indicating that the NBS-LRR sequence represented by this marker is not related to PcA. L7M2 was also excluded as a member of the PcA cluster, although it could be an appropriate marker for the Prq1a cluster if chromosome rearrangements are postulated.
EST-SSR markers derived from an elite barley cultivar (Hordeum vulgareL. ‘Morex’): polymorphism and genetic marker potential
Authors: Emebiri Livinus C.
Published: September 2009

Microsatellites or simple sequence repeats have become the markers of choice for marker-assisted selection because of their low template DNA requirement, high reproducibility, and high level of polymorphism. This study investigated a new set of barley ( Hordeum vulgare L.) EST-derived SSR markers designed to target gene sequences expressed during grain development, as they are more likely to be important in determining grain quality. The EST sequences (HVSMEh and HVSMEi) were derived from cDNA libraries of the elite six-rowed cultivar Morex, made from spikes harvested at 5 to 45 days after pollination. Approximately half of the 110 SSR markers derived from the ESTs were polymorphic in a panel of 8 diverse barley genotypes, with PIC values between 0.19 and 0.79. Twenty of the new markers were mapped to chromosomal locations using 2 doubled haploid populations. To demonstrate marker potential, quantitative trait locus (QTL) analyses were carried out with phenotypic data on wort β-glucan content and β-glucanase activity, two traits with a long history of genetic studies. Most of the EST-SSR markers mapped to within 10 cM of the cellulose synthase (HvCesA) and cellulose synthase-like (HvCslF) genes, which provides highly informative functional markers for tracking these genes in breeding programs. It was also observed that on any given chromosome, the QTL for β-glucan content and β-glucanase activity were rarely coincident but tended to occur in adjacent intervals along chromosomal regions, which agreed with their independent genetic basis; the adjacent localization may be important for coordination of cell wall degradation during germination and malting.
Characterization of Salt Overly Sensitive 1 (SOS1) gene homoeologs in quinoa (Chenopodium quinoa Willd.)
Authors: Maughan P. J. , Turner T. B. , Coleman C. E. , Elzinga D. B. , Jellen E. N. , Morales J. A. , Udall J. A. , Fairbanks D. J. , Bonifacio A.
Published: September 2009

Salt tolerance is an agronomically important trait that affects plant species around the globe. The Salt Overly Sensitive 1 (SOS1) gene encodes a plasma membrane Na+/H+ antiporter that plays an important role in germination and growth of plants in saline environments. Quinoa (Chenopodium quinoa Willd.) is a halophytic, allotetraploid grain crop of the family Amaranthaceae with impressive nutritional content and an increasing worldwide market. Many quinoa varieties have considerable salt tolerance, and research suggests quinoa may utilize novel mechanisms to confer salt tolerance. Here we report the cloning and characterization of two homoeologous SOS1 loci (cqSOS1A and cqSOS1B) from C. quinoa, including full-length cDNA sequences, genomic sequences, relative expression levels, fluorescent in situ hybridization (FISH) analysis, and a phylogenetic analysis of SOS1 genes from 13 plant taxa. The cqSOS1A and cqSOS1B genes each span 23 exons spread over 3477 bp and 3486 bp of coding sequence, respectively. These sequences share a high level of similarity with SOS1 homologs of other species and contain two conserved domains, a Nhap cation-antiporter domain and a cyclic-nucleotide binding domain. Genomic sequence analysis of two BAC clones (98 357 bp and 132 770 bp) containing the homoeologous SOS1 genes suggests possible conservation of synteny across the C. quinoa sub-genomes. This report represents the first molecular characterization of salt-tolerance genes in a halophytic species in the Amaranthaceae as well as the first comparative analysis of coding and non-coding DNA sequences of the two homoeologous genomes of C. quinoa.
Enrichment of a papaya high-density genetic map with AFLP markers
Authors: Blas Andrea L. , Yu Qingyi , Chen Cuixia , Veatch Olivia , Moore Paul H. , Paull Robert E. , Ming Ray
Published: September 2009

A high-density genetic linkage map of papaya, previously developed using an F2mapping population derived from the intraspecific cross AU9 × SunUp, was enriched with AFLP markers. The comprehensive genetic map presented here spans 945.2 cM and covers 9 major and 5 minor linkage groups containing 712 SSR, 277 AFLP, and 1 morphological markers. The average marker density for the 9 major linkage groups is 0.9 cM between adjacent markers, and the total number of gaps >5 cM was reduced from 48 to 27 in the current map. AFLPs generated by EcoRI/MseI primer combinations were distributed throughout the 14 linkage groups and resulted in several large locus order rearrangements within the 9 major linkage groups. Integration of AFLP markers provided tighter linkage association between loci, leading to a reduction in map distance on LGs 1, 2, and 4, which were inflated in the previous map, and correction of the marker order on LG8. Suppression of recombination in the male-specific Y region (MSY) of LG1 is further validated by the addition of 27 sex co-segregating AFLP markers. A large region of distorted segregation surrounding the MSY spans 54.4 cM and represents ∼71% of the linkage group. This comprehensive high-density genetic map provides a framework for mapping quantitative trait loci and for fine mapping as well as for comparative genomic studies of crop plant development and evolution.
EST mining for structure and expression of genes in the region of the wheat high-molecular-weight glutenin loci
Authors: Anderson O. D.
Published: September 2009

An in-depth analysis was carried out with expressed sequence tags (ESTs) for genes in and near the HMW-GS loci. Considerations for using ESTs are discussed, including the occurrence of chimeric and aberrant HMW-GS ESTs. Complete gene sequences demonstrated the feasibility of constructing accurate full-length coding regions from EST assemblies and found, or supported, errors in several previously reported HMW-GS gene sequences. New complete HMW-GS gene sequences are reported for the cultivars Chinese Spring and Glenlea. The Ay subunit gene, which is considered null in cultivated wheats, was shown to transcribe in at least two germplasms. Analyses support the conclusion that of the five known genes within this genomic region, the two HMW-GS genes and the globulin gene are highly expressed. The other two genes, encoding a receptor kinase and a protein kinase, have one and no identifiable wheat EST, respectively, although ESTs are found for the orthologous genes in barley. The ESTs of all five genes within the HMW-GS region are either definitely associated with the endosperm or possibly originate from imbibed seed, suggesting the four distinct gene classes in this region are part of a seed or endosperm chromatin domain. EST resources were also used to determine relative abundance of ESTs for all classes of wheat prolamines and indicated differential levels of expression both among germplasms and among the three genomes of hexaploid wheats.
Daily physical activity and macronutrient distribution of low-calorie diets jointly affect body fat reduction in obese women
Authors: López-Fontana Constanza Matilde , Sánchez-Villegas Almudena , Martínez-Gonzalez Miguel Angel , Martinez José Alfredo
Published: September 2009

Inadequate dietary patterns and sedentary lifestyles are believed to be important factors in predisposing people to obesity. This study analyzed the potential interaction between habitual physical activity and the carbohydrate (CHO)-fat distribution in 2 hypocaloric diets and the impact of such interplay on body composition changes. Forty healthy obese women, 20–50 years old, were randomly assigned to a high- or low-CHO energy-restricted diet, which was low or high in fat, respectively, during 10 weeks. Baseline and final measurements were performed to assess dietary habits, resting metabolic rate, and body composition changes. Physical activity was measured with a triaxial accelerometer and with a questionnaire. There were no significant differences in anthropometric and metabolic variables between both dietary groups at baseline. However, there was a positive correlation between total free-living physical activity and arm muscle preservation after 10 weeks (r = 0.371; p = 0.024). Interestingly, an interaction between macronutrient (CHO–fat distribution) intake and physical activity was found, since less-active subjects with a high-CHO–low-fat diet showed a greater fat loss than those more active with a lower-CHO–high-fat diet, whereas more-active subjects with a high-CHO–low-fat diet showed a smaller fat loss than those receiving a low-CHO–high-fat diet. Physical activity and the macronutrient content of energy-restricted diets, when designed to promote body fat mass reduction, should be considered together to better predict the outcome.
Prevention of overweight and obesity in children under the age of 6 yearsA report commissioned by the Canadian Council of Food and Nutrition.
Authors: Olstad Dana Lee , McCargar Linda
Published: September 2009

Although obesity was rarely observed among children 30 years ago, it is now evident among Canadian children of all ages. Currently, 15.2% of 2- to 5-year-old children are overweight, whereas 6.3% are obese. Limited data suggest that poor dietary and physical activity patterns are increasing obesity risk among these young children. Body weight and lifestyle behaviours are known to track from childhood to adulthood, thereby increasing the risk for obesity and other chronic diseases later in life. Intrauterine life, infancy, and the preschool years may all include critical periods that program the long-term regulation of energy balance, and therefore obesity-prevention strategies should be initiated in utero and continue throughout childhood and adolescence. Although single-strategy obesity-prevention initiatives have had limited success, programs that target multiple behaviours may help reduce body weight and body fat among young children. Parental involvement is key to the success of obesity-prevention programs at a young age, as parents have primary control over their children’s food and activity environments. Accordingly, parental obesity is the best predictor of childhood obesity. Parents should be encouraged to teach and role model healthy lifestyle behaviours for their young children. Health professionals can also be involved in obesity prevention, as they are ideally placed to identify young children at risk for obesity. By calculating and plotting the body mass index for all children, and initiating obesity-prevention strategies in utero, health professionals can help curb the rise in overweight and obesity among young children.
Exercise-induced lymphocyte apoptosis attributable to cycle ergometer exercise in endurance-trained individuals
Authors: Navalta James Wilfred , McFarlin Brian Keith , Lyons Thomas Scott , Faircloth John Clifton , Bacon Nicholas T. , Callahan Zachary J.
Published: September 2009

Exercise as a stimulus to induce lymphocyte apoptosis remains controversial. Differences may be due to participant fitness level or the methodology of assessing cell death. Another important issue is the mode of exercise used to induce physiological changes. Treadmill exercise typically induces significant apoptosis in human lymphocytes; however, the effect of cycle exercise is less clear. The 2 main purposes of this study were to assess if cycle ergometer exercise induces similar changes in apoptosis, and to further characterize the morphological method of assessing cell death. Endurance athletes (n = 10; peak oxygen consumption = 55.1 mL·kg–1·min–1) completed a 60-min ride on a cycle ergometer at ~80% peak oxygen consumption. Blood samples taken before (PRE) and after (POST) exercise were used to make blood films for apoptotic analysis via the morphological technique. A significant increase was observed in the apoptotic index following cycle exercise (PRE = 7.3 ± 2%, POST = 12.9 ± 2%; p < 0.01). On average, it took 42 ± 9 min to read PRE sample slides, which was significantly longer than the 27 ± 4 min needed for POST slides (p < 0.01). To our knowledge, this study is the first to report that exercise on the cycle ergometer produces changes in lymphocyte apoptosis. The values measured during this study were about 20% lower than those we have observed following treadmill running, which may be explained by differences in active muscle mass and the resultant physiological stress between the 2 exercise modes. It is likely that cycling may result in reduced immunosuppression, compared with running at the same intensity.
The effects of increased endurance training load on biomarkers of heat intolerance during intense exercise in the heat
Authors: Lim Chin Leong , Pyne David , Horn Peggy , Kalz Amelia , Saunders Philo , Peake Jonathan , Suzuki Katsuhiko , Wilson Gary , Mackinnon Laurel T.
Published: September 2009

The effects of increased training (IT) load on plasma concentrations of lipopolysaccharides (LPS), proinflammatory cytokines, and anti-LPS antibodies during exercise in the heat were investigated in 18 male runners, who performed 14 days of normal training (NT) or 14 days of 20% IT load in 2 equal groups. Before (trial 1) and after (trial 2) the training intervention, all subjects ran at 70% maximum oxygen uptake on a treadmill under hot (35 °C) and humid (∼40%) conditions, until core temperature reached 39.5 °C or volitional exhaustion. Venous blood samples were drawn before, after, and 1.5 h after exercise. Plasma LPS concentration after exercise increased by 71% (trial 1, p < 0.05) and 21% (trial 2) in the NT group and by 92% (trial 1, p < 0.01) and 199% (trial 2, p < 0.01) in the IT group. Postintervention plasma LPS concentration was 35% lower before exercise (p < 0.05) and 47% lower during recovery (p < 0.01) in the IT than in the NT group. Anti-LPS IgM concentration during recovery was 35% lower in the IT than in the NT group (p < 0.05). Plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-α concentrations after exercise (IL-6, 3−7 times, p < 0.01, and TNF-α, 33%, p < 0.01) and during recovery (IL-6, 2−4 times, p < 0.05, and TNF-α, 30%, p < 0.01) were higher than at rest within each group. These data suggest that a short-term tolerable increase in training load may protect against developing endotoxemia during exercise in the heat.
Effects of the self-contained breathing apparatus on left-ventricular function at rest and during graded exercise
Authors: Mayne Jonathan R. , Haykowsky Mark J. , Nelson Michael D. , Hartley Timothy C. , Butcher Scott J. , Jones Richard L. , Petersen Stewart R.
Published: September 2009

The purpose of this study was to examine the effects of the self-contained breathing apparatus (SCBA) on left-ventricular (LV) function at rest and during mild- to moderate-intensity exercise, using 2-dimensional echocardiography. Twenty-three healthy male volunteers exercised on a stair-climber at work rates equivalent to 50%, 60%, 70%, and 80% of peak oxygen consumption. Esophageal pressure LV diastolic and systolic cavity areas, and myocardial areas were acquired during the final minute of each stage of exercise. As expected, the esophageal pressure response during SCBA breathing revealed significantly lower (more negative) inspiratory pressures and higher (more positive) expiratory pressures and, consequently, higher pressure swings, than free breathing (FB). End-diastolic cavity area (EDCA) and end-systolic cavity area (ESCA) were lower with the SCBA than with FB. LV contractility was higher (p < 0.05) with the SCBA, which can partially be explained by decreases in end-systolic wall stress. Therefore, the SCBA was found to decrease LV preload during moderate-intensity exercise, but did not negatively affect stroke area because of a similar reduction in ESCA.
Greater daily leisure time physical activity is associated with lower chronic disease risk in adults with spinal cord injury
Authors: Buchholz Andrea C. , Martin Ginis Kathleen A. , Bray Steven R. , Craven B. Catharine , Hicks Audrey L. , Hayes Keith C. , Latimer Amy E. , McColl Mary Ann , Potter Patrick J. , Wolfe Dalton L.
Published: September 2009

The objective of this study was to examine the relationship between leisure time physical activity (LTPA) and common risk factors for cardiovascular disease (CVD) and type 2 diabetes in community-dwelling adults with chronic spinal cord injury (SCI). LTPA was measured using the Physical Activity Recall Assessment for People with SCI in 76 men and women with chronic (≥1 year) paraplegia or tetraplegia, living in or near Hamilton, Ontario. Body mass index (BMI), waist circumference, body composition (fat mass (FM) and fat-free mass (FFM)), blood pressure, and biochemical data were collected. Thirty-seven percent (n = 28 participants) were inactive, reporting no LTPA whatsoever, and were compared with an equal-sized group consisting of the most active study participants (≥25 min of LTPA per day). After adjusting for significant covariates, BMI (18.7%), %FM (19.4%), and C-reactive protein (143%) were all lower, and %FFM was higher (7.2%), in active participants (all p ≤ 0.05). Ten percent of active participants vs. 33% of inactive participants were insulin resistant (p = 0.03). Waist circumference (17.6%) and systolic blood pressure (15.3%) were lower in active vs. inactive participants with paraplegia (both p ≤ 0.05), but not tetraplegia. In conclusion, greater daily LTPA is associated with lower levels of selected CVD and type 2 diabetes risk factors in individuals living with SCI. Whether this relationship translates into a lower incidence of these chronic diseases has yet to be determined.
Preinfection aerobic treadmill training improves resistance against Trypanosoma cruzi infection in mice
Authors: Schebeleski-Soares Cristiano , Occhi-Soares Roberta Cristhiany , Franzói-de-Moraes Solange Marta , de Oliveira Dalálio  Márcia Machado , Almeida Felipe Natali , de Ornelas Toledo Max Jean , de Araújo Silvana Marques
Published: September 2009

Exercise performed before infections has been linked to improvement of the immune response against infections. The purpose of this study was to evaluate the influence of preinfection moderate-intensity treadmill training on acute Trypanosoma cruzi infection in mice. Ninety-nine female BALB/c mice were divided into 4 groups, as follows: training + infection (T+I) (n = 41); no training + infection (NT+I) (n = 38); training + no infection (T+NI) (n = 10); and no training + no infection (NT+NI) (n = 10). The exercise program for trained groups was carried out on a motorized treadmill for 8 weeks. Infected groups were inoculated with the Y strain of T. cruzi. Infectivity, prepatent period, patent period, parasitemia peak, mortality, survival time, weight, food intake, tumor necrosis factor-alpha serum levels, and peritoneal macrophage hydrogen peroxide production were evaluated. We found that preinfection training induced statistically significant reductions in parasitemia peak (p < 0.03) and weight loss (p < 0.04). However, no statistically significant differences were found for the other parameters evaluated when trained and nontrained infected groups were compared. We conclude that preinfection aerobic training induces some improvement in the immune response to T. cruzi infection in female BALB/c mice.
Estimating leisure-time physical activity energy expenditure in the Canadian population: a comparison of 2 methods
Authors: Bryan Shirley N. , Katzmarzyk Peter T.
Published: September 2009

The purpose of this study was to determine the impact of 2 different calculation methods for total leisure-time physical activity energy expenditure (LTPAEE) and LTPAEE from different intensity activities on the classification of level of physical activity in the population. Nationally representative cross-sectional data from the Canadian Community Health Survey Cycle 4.1 (2007) were used for this study (N = 64 397). LTPAEE was calculated using a metabolic equivalent (MET) value of 4.0 for all activities in the “other activity” category for method 1 (currently employed by Statistics Canada) and using activity-specific MET values for method 2. The weighted prevalence and 95% confidence intervals of active (≥3  kcal·kg–1·day–1 (kkd)), moderately active (1.5–2.9 kkd), and inactive (<1.5 kkd) were determined for each method by demographic characteristics. The agreement between the 2 methods was assessed overall, and for light, moderate, and vigorous activities. There was no difference between methods in the proportion classified as active, moderately active, or inactive for any of the subgroups studied and there was no difference in the distribution or mean LTPAEE between methods. However, assessment of the agreement showed a large number of outliers and a tendency to underestimate LTPAEE from light and vigorous activities while overestimating LTPAEE from moderate activities at the individual level. The results of this study should be considered when performing inferential statistics on the relationship between physical activity and health outcomes.
The effect of an inverted body position on lower limb muscle force and activation
Authors: Paddock Natasha , Behm David
Published: September 2009

Complete inversion of the body in a seated position may occur in exceptional circumstances such as in overturned vehicles and during military maneuvers, with direct consequences on health and fatalities. However, the physiological responses to this condition have not been published previously. The purpose of this study was to compare neuromuscular responses to upright and inverted seated positions. Sixteen subjects performed maximal voluntary contraction (MVC) and submaximal voluntary contraction knee extensions (25%, 50%, and 75% of MVC) under upright and inverted seated positions. Force, quadriceps activation as measured by the interpolated twitch technique, electromyographic (EMG) activity of the vastus lateralis, and semitendenosis and evoked contractile properties of the quadriceps were measured. Results demonstrated that MVC force (p = 0.01, ↓6.1%) and vastus lateralis EMG (p = 0.009, ↓29.6%) decreased in the inverted compared with the upright position. Instantaneous strength in the inverted position was 19.3% lower than in the upright position (p = 0.005). Heart rate and diastolic and systolic blood pressures were 12.4%, 9.2%, and 10.7% lower (p < 0.0001), respectively, in the inverted position. In conclusion, a seated inverted position impaired MVC force and EMG activity, which could not be attributed to evoked contractile properties. The changes in heart rate and blood pressure may suggest inversion-induced alterations to the sympathetic nervous stimulation.
Sex alters impact of repeated bouts of sprint exercise on neuromuscular activity in trained athletes
Authors: Billaut François , Smith Kurt
Published: September 2009

This study characterized the effect of sex on neuromuscular activity during repeated bouts of sprint exercise. Thirty-three healthy male and female athletes performed twenty 5-s cycle sprints separated by 25 s of rest. Mechanical work and integrated electromyograhs (iEMG) of 4 muscles of the dominant lower limb were calculated in every sprint. The iEMG signals from individual muscles were summed to represent overall electrical activity of these muscles (sum-iEMG). Neuromuscular efficiency (NME) was calculated as the ratio of mechanical work and sum-iEMG for every sprint. Arterial oxygen saturation was estimated (SpO2) with pulse oximetry throughout the protocol. The sprint-induced work decrement (18.9% vs. 29.6%; p < 0.05) and sum-iEMG reduction (11.4% vs. 19.4%; p < 0.05) were less for the women than for the men. However, the sprints decreased NME (10.1%; p < 0.05) and SpO2(3.4%; p < 0.05) without showing sex dimorphism. Changes in SpO2and sum-iEMG were strongly correlated in both sexes (men, R2= 0.87; women, R2= 0.91; all p < 0.05), although the slope of this relationship differed (6.3 ± 2.9 vs. 3.8 ± 1.6, respectively; p < 0.05). It is suggested that the sex difference in fatigue during repeated bouts of sprint exercise is not likely to be explained by a difference in muscle contractility impairment in men and women, but may be due to a sex difference in muscle recruitment strategy. We speculate that women would be less sensitive to arterial O2desaturation than men, which may trigger lower neuromuscular adjustments to exhaustive exercise.
Effects of ovariectomy and resistance training on MMP-2 activity in skeletal muscle
Authors: Prestes Jonato , de Cássia Marqueti Rita , Shiguemoto Gilberto Eiji , Leite Richard Diego , Pereira Guilherme Borges , Selistre-de-Araújo Heloisa Sobreiro , Baldissera Vilmar , de Andrade Perez Sérgio Eduardo
Published: September 2009

Matrix metallopeptidases (MMPs) are crucial to the maintenance of healthy tissue. The aim of this study was to investigate MMP-2 activity in gastrocnemius, soleus, tibialis anterior (TA), and extensor digitorium longus (EDL) muscle after resistance training in ovariectomized rats. Wistar adult female rats were grouped into 7 groups (n = 10 per group): sedentary (Sed-Intact); ovariectomized sedentary (Sed-Ovx); pseudo-ovariectomized sedentary (Sed-Pseudo); acute exercise (AcuteEx-Intact); ovariectomized acute exercise (AcuteEx-Ovx); strength trained (ChronicEx-Intact); and ovariectomized strength trained (ChronicEx-Ovx). A 12-week resistance training period, during which the animals climbed a 1.1-m vertical ladder with weights secured to their tails, was used. The sessions were performed once every 3 days, with 4–9 climbs and 8–12 dynamic movements per climb. The MMP-2 activity was analyzed by zymography. There was higher MMP-2 activity in soleus muscle in the ChronicEx-Intact and ChronicEx-Ovx groups, and lower MMP-2 activity in the AcuteEx-Ovx group, compared with the Sed-Intact group (p ≤ 0.05). The Sed-Ovx and ChronicEx-Ovx groups presented lower MMP-2 activity than the Sed-Intact group in TA. There was higher MMP-2 activity in AcuteEx-Intact and the AcuteEx-Ovx compared with the Sed-Intact and Sed-Ovx in TA, respectively (p ≤ 0.05). In TA and EDL, training increased MMP-2 activity in the Sed-Intact group. No statistically significant alterations were observed for gastrocnemius muscle. Strength training increases MMP-2 activity in soleus, TA, and EDL muscle, which may be important for muscle remodeling. Ovariectomy downregulates MMP-2 in TA and EDL, which may compromise muscle function.
Physical activity of children in family child care
Authors: Temple Viviene A. , Naylor Patti-Jean , Rhodes Ryan E. , Higgins Joan Wharf
Published: September 2009

Physical activity was monitored for 65 boys and girls, during family child care, using accelerometry. Average accelerometer wear time was 7.0 h (SD = 0.83), and average counts per epoch were 104.6 (SD = 31.6). Mean minutes per hour of moderate-vigorous physical activity and sedentary behaviour were 1.76 min (SD = 0.90) and 39.49 min (SD = 4.50), respectively. The very low levels of moderate-vigorous physical activity suggest that the young children in this study may be insufficiently active during child care.
Age- and sex-associated differences in isokinetic knee muscle endurance between young children and adults
Authors: De Ste Croix Mark B.A. , Deighan Martine A. , Ratel Sebastien , Armstrong Neil
Published: September 2009

The purpose of this study was to examine the age- and sex-associated differences of repeated isokinetic knee extension and flexion. Fifty one participants, 30 young children (16 boys and 14 girls; aged 11 and 12 years) and 21 adults (9 males and 12 females; aged 18–35 years), agreed to participate in the study. Isokinetic concentric peak knee extension (PET) and flexion (PFT) torque were measured using a calibrated Biodex System 3. Participants performed 4 concentric extension–flexion cycles with maximum effort; after a 2 min rest, 50 continuous concentric cycles were performed at 1.56 rad·s–1. Total work of the extensors (WKEX) and flexors (WKFL) for the complete 50 repetitions was recorded. Average peak torque and average work for the first and last 3 repetitions were calculated to represent the percentage decline in torque and work. There were no significant differences between groups in the peak torque generated during the pretrial and endurance task, suggesting that participants gave a maximal effort at the start of the endurance task. There was a significant interaction effect in the total work done for both extensors and flexors, with adult males producing the greatest amount of work (6622 and 3444 J, respectively). When total work was divided by body mass, there were no significant sex effects, only main effects for group. The percentage decline for PET (40% vs. 60%), PFT (50% vs. 65%), WKET(43% vs. 61%), and WKFL(60% vs. 69%) demonstrated significant main effects for group, with greater fatigue in adults. We found no significant sex effect for fatigue. This study concludes that females do not resist fatigue from repeated isokinetic muscle actions to a greater extent than males, and that the greater fatigue in adults than in children is probably a product of greater initial torque production and work performed.
Postexercise rehydration in man: the effects of carbohydrate content and osmolality of drinks ingested ad libitum
Authors: Evans Gethin H. , Shirreffs Susan M. , Maughan Ronald J.
Published: September 2009

The effectiveness of different carbohydrate solutions in restoring fluid balance in situations of voluntary fluid intake has not been examined previously. The effect of the carbohydrate content of drinks ingested after exercise was examined in 6 males and 3 females previously dehydrated by 1.99 ± 0.07% of body mass via intermittent exercise in the heat. Beginning 30 min after the cessation of exercise, subjects drank ad libitum for a period of 120 min. Drinks contained 31 mmol·L–1 Na+ as NaCl and either 0%, 2%, or 10% glucose with mean ± SD osmolalities of 74 ± 1, 188 ± 3, and 654 ± 4 mosm·kg–1, respectively. Blood and urine samples were collected before and after exercise, midway through rehydration, and throughout a 5 h recovery period. Total fluid intake was not different among trials (0%: 2258 ± 519 mL; 2%: 2539 ± 436 mL; 10%: 2173 ± 252 mL; p = 0.173). Urine output was also not different among trials (p = 0.160). No differences among trials were observed in net fluid balance or in the fraction of the ingested drink retained. In conclusion, in situations of voluntary fluid intake, hypertonic carbohydrate-electrolyte solutions are as effective as hypotonic carbohydrate-electrolyte solutions at restoring whole-body fluid balance.
Relationship of blood pressure, behavioral mood state, and physical activity following caffeine ingestion in younger and older women
Authors: Arciero Paul J. , Ormsbee Michael J.
Published: September 2009

The purpose of this study was to examine the age-related differences in blood pressure, heart rate, and behavioral mood state after caffeine ingestion in younger and older women. Using a placebo-controlled, double-blind design, 10 younger (Y; 18–22 years) and 10 older (O; 50–67 years) healthy women who were moderate consumers of caffeine (self-reported mean intake: Y, 139 ± 152 mg·day–1; O, 204 ± 101 mg·day–1) were investigated. All volunteers were characterized for fasting plasma glucose, insulin, free-fatty acids and caffeine levels, body composition, cardiovascular fitness, physical activity, and energy intake. Before and after placebo and caffeine ingestion (5 mg·kg–1 fat-free mass; ~208–270 mg) test days, the following variables were measured in all subjects: plasma caffeine levels, heart rate, blood pressure, and behavioral mood state. Results showed that, following caffeine ingestion: (i) both systolic and diastolic blood pressure (SBP and DBP, respectively) increased significantly (p < 0.05) in the older women (SBP, 128.4 ± 14.2 vs. 132.1 ± 13.0 mm Hg (3%); DBP, 80.2 ± 6.9 vs. 83.4 ± 7.5 mm Hg (4%), whereas only DBP increased in the youger women (67.1 ± 4.7 vs. 69.9 ± 5.4 mm Hg (4.2%); p < 0.05); (ii) heart rate decreased significantly (Y, 59.2 ± 8.7 to 53.9 ± 10.6 beats·min–1 (p < 0.05); O, 61.9 ± 9.2 to 59.2 ± 8.4 beats·min–1 (p < 0.05)) in both groups; and (iii) self-reported feelings of tension and vigor increased and feelings of fatigue decreased (p < 0.05) in younger women, whereas depression decreased (p ≤ 0.05) in older women. Self-reported level of physical activity was inversely related to change in DBP following caffeine ingestion in younger women. In conclusion, blood pressure response is augmented and subjective feelings of behavioral mood state are attenuated to a greater degree in older than in younger women following acute caffeine ingestion. Less physically active younger women are more vulnerable to the pressor response to caffeine than more active younger women. It should be noted that these findings are limited to moderate consumers of caffeine who abstained for 48 h prior to testing, and who ingested caffeine in pill form (~240 mg).
Physiological correlates of 2-mile run performance as determined using a novel on-demand treadmill
Authors: Tolfrey Keith , Hansen Simon A. , Dutton Katie , McKee Tom , Jones Andrew M.
Published: September 2009

The purpose of this study was to assess the reproducibility of an on-demand motorised treadmill to measure 2-mile (3.2 km) race performance and to examine the physiological variables that best predict this free-running performance in active men. Twelve men (mean (SD): age, 28 (9) years; stature, 1.79 (0.05) m; body mass, 72 (9) kg) completed the study in which maximum oxygen uptake (VO2 max), running economy, and running speed at VO2 max (vVO2 max), lactate threshold (vLT), and 4 mmol·L–1 fixed blood lactate concentration (v4) were measured. Subsequently, the maximal lactate steady state (MLSS) was identified using a series of 30-min treadmill runs. Finally, each participant completed a 2-mile running performance trial on 2 separate occasions, using an on-demand treadmill that adjusts belt speed according to the participant’s position on the moving belt. The average 2-mile run speed was 15.7 (SD, 1.9) km·h–1, with small individual differences between repeat-performance trials (intraclass correlation coefficient = 0.99, 95% CI 0.953 to 0.996; standard error of measurement as coefficient of variation = 1.5%, 95% CI 1.0% to 2.5%). Bivariate regression analyses identified VO2 max, vVO2 max, VO2 (mL·kg–1·min–1) at MLSS, vLT, v4, and velocity at MLSS (vMLSS) as the strongest individual predictor variables (r2 = 0.69 to 0.87; standard error of the estimate = 1.08 to 0.72 km·h–1) for 2-mile running performance. The vLT and vMLSS explained 85% and 87% of the variance in running performance, respectively, suggesting that there is considerable shared variance between these parameters. In conclusion, the on-demand treadmill system provided a reliable measure of distance running performance. Both vLT and vMLSS were strong predictors of 2-mile running performance, with vMLSS explaining marginally more of the variance.
Acute and chronic contractile activity-induced adaptations in muscle and mitochondrial function
Authors: Ljubicic Vladimir
Published: September 2009

Exercise training is a potent stimulus for favourable phenotypic adaptations in muscle, including the induction of mitochondrial biogenesis. Although the occurrence of organelle expansion in response to chronic muscle use is accepted, the cellular events governing this remodeling are undefined. Thus, the purpose of this dissertation was to examine the acute and chronic contractile activity-induced adaptations in skeletal muscle and mitochondrial function in young and old animals. The intracellular signals associated with contractile activity are important for the induction of downstream phenotypic plasticity. In study 1, we investigated the influence of muscle oxygen consumption and reactive oxygen species (ROS) production on kinase signaling. The results demonstrate that mitochondrial content influenced the rate of ROS production in resting muscle. Furthermore, several protein kinases were differentially sensitive to increments in oxygen consumption, and this sensitivity was also related to the muscle mitochondrial volume. In study 2, we further explored the effect of mitochondrial content on the acute contraction-induced kinase signaling in skeletal muscle. We found that mitochondrial content was inversely related to kinase activation in resting skeletal muscle. Moreover, training-induced increases in mitochondrial volume were associated with an attenuated adaptive signaling response subsequent to a single bout of contractions, suggesting a mitochondrially mediated mechanism regulating training-elicited muscle remodeling. The aim of study 3 was to examine the effect of age on the acute exercise-induced signaling response. Skeletal muscle from old animals exhibited pathophysiological properties, including reduced force production, fatigue resistance, mitochondrial content, and ATP-synthesizing ability, all characteristic of aging-associated sarcopenia. This condition was correlated with an attenuated signaling response to acute exercise, which was dependent on muscle mitochondrial content. Study 4 assessed the adaptive plasticity of mitochondria in young and old animals after chronic muscle use. We found that the mitochondria from aged animals were able to adapt favourably to a period of chronic contractile activity, despite an attenuated signaling response after each individual bout of exercise. However, the adaptive plasticity of aged animals was lower than that observed in young animals. These findings underscore the importance of daily physical activity in the maintenance and improvement of health for individuals of all ages.
Conception sismique des murs de refend couplés, selon la norme canadienne Calcul des ouvrages en béton 2004 et le Code national du bâtiment – Canada 2005
Authors: Benazza Tewfik , Chaallal Omar
Published: September 2009

This paper presents a comprehensive review of the new provisions for the design of coupled shear walls in Canadian seismic zones. It follows major revisions that were incorporated in the National Building Code of Canada 2005 (NBCC 2005) and in the Canadian standard Design of concrete structures (CSA A23.3-04), which were due, in particular, to the adoption of a new Canadian map of seismic risk. The present study is intended to address recurring confusions in current practice and the difficulties expressed in the application and interpretation of the new NBCC 2005 and CSA A23.3-04 provisions. A design flowchart is thus proposed as a practical guide, describing, step by step, the required verifications at each stage of coupled shear walls calculation. Finally, to demonstrate the applicability of these new provisions, a numerical example is detailed, following the presented design flowchart.
Effects of full-height nonstructural partitions on modal properties of two nominally identical building floors
Authors: Miskovic Z. , Pavic A. , Reynolds P.
Published: September 2009

This paper presents a combined experimental and numerical investigation of the modal properties of two full-scale and nominally identical steel–concrete composite floors. The floors were one above the other in the same fully operational multi-storey building. Both floors accommodated open-plan as well as partitioned offices. Multi-input-multi-output (MIMO) modal testing was employed to measure as-built modal properties of both floors. It was found that the two nominally identical floors had different modal characteristics, likely due to the different arrangement of partitions in the floor. It was also found that the measured modes on both floor levels experienced a considerable level of complexity, likely to be caused by nonproportional damping. Finite element (FE) models were developed in ANSYS for both floors using best engineering judgement and their features and properties were then tuned to match the measured counterparts. The tuning was done manually by trial-and-error and then automatically using sensitivity-based FE model updating procedure implemented in the FEMtools software. It was found that the initial and geometrically very detailed FE models, which did not feature any nonstructural components, underestimated the measured natural frequencies by up to a considerable 20%–25%, depending on the floor level. When full-height plasterboard and glass partitions were explicitly modelled as vertical springs connected to the floor and grounded at the other end, the correlation between the experimental and FE results improved considerably.
Approach for uncertainty propagation and design in Saint Venant equations via automatic sensitive derivatives applied to Saar river
Authors: Souhar Otmane , Faure Jean-Baptiste
Published: September 2009

This paper describes the assessment of uncertainties of computational fluid dynamics (CFD) for modelling free surface flows. A series of CFD simulations, using MAillé GEnéralisé (MAGE), are employed to compute the flood extent resulting from the overflow of rivers. These simulated outputs are affected by uncertainties in the empiric roughness coefficients. Uncertainty propagation in MAGE outputs is difficult to evaluate because of the complexity and the nonlinearity of models. Assessment of uncertainties may be carried out by computing derivatives of the output results with respect to the inputs. Recently, automatic differentiation (AD) has become an efficient numerical method for sensitivity analysis and assessment of uncertainties. In this paper, AD is used to transform mechanically a given one-dimensional hydraulic model, MAGE, into a new program capable of computing the original simulation and the desired derivatives. Specifically, derivatives of the flood extent and the water width with respect to the roughness coefficients are computed. Numerical experiments of derivatives obtained from AD and divided difference (DD) approximations are compared, validating derivatives obtained by AD. Results can serve to evaluate existing flood models.