Increase in S6K1 phosphorylation in human skeletal muscle following resistance exercise occurs mainly in type II muscle fibres

To investigate the in vivo effects of resistance exercise on translational control in human skeletal muscle, we determined the phosphorylation of AMP-activated kinase (AMPK), eukaryotic initiation factor 4E-binding protein (4E-BP1), p70/p85-S6 protein kinase (S6K1), and ribosomal S6 protein (S6). Furthermore, we investigated whether changes in the phosphorylation of S6K1 are muscle fiber type specific. Eight male subjects performed a single high-intensity resistance exercise session. Muscle biopsies were collected before and immediately after exercise and after 30 and 120 min of postexercise recovery. The phosphorylation statuses of AMPK, 4E-BP1, S6K1, and S6 were determined by Western blotting with phospho-specific and pan antibodies. To determine fiber type-specific changes in the phosphorylation status of S6K1, immunofluorescence microscopy was applied. AMPK phosphorylation was increased approximately threefold immediately after resistance exercise, whereas 4E-BP1 phosphorylation was reduced to 27 ± 6% of preexercise values. Phosphorylation of S6K1 at Thr421/Ser424 was increased 2- to 2.5-fold during recovery but did not induce a significant change in S6 phosphorylation. Phosphorylation of S6K1 was more pronounced in the type II vs. type I muscle fibers. Before exercise, phosphorylated S6K1 was predominantly located in the nuclei. After 2 h of postexercise recovery, phospho-S6K1 was primarily located in the cytosol of type II muscle fibers. We conclude that resistance exercise effectively increases the phosphorylation of S6K1 on Thr421/Ser424, which is not associated with a substantial increase in S6 phosphorylation in a fasted state.

Interaction of exercise and diet on GLUT-4 protein and gene expression in type I and type II rat skeletal muscle

We determined the interaction of exercise and diet on glucose transporter (GLUT-4) protein and mRNA expression in type I (soleus) and type II [extensor digitorum longus (EDL)] skeletal muscle. Forty-eight Sprague Dawley rats were randomly assigned to one of two dietary conditions: high-fat (FAT, n =24) or high-carbohydrate (CHO, n =24). Animals in each dietary condition were allocated to one of two groups: control (NT, n =8) or a group that performed 8 weeks of treadmill running (4 sessions week^–1 of 1000 m @ 28 m min^–1 , RUN, n =16). Eight trained rats were killed after their final exercise bout for determination of GLUT-4 protein and mRNA expression: the remainder were killed 48 h after their last session for measurement of muscle glycogen and triacylglycerol concentration. GLUT-4 protein expression in NT rats was similar in both muscles after 8 weeks of either diet. However, there was a main effect of training such that GLUT-4 protein was increased in the soleus of rats fed with either diet (P < 0.05) and in the EDL in animals fed with CHO (P < 0.05). There was a significant diet–training interaction on GLUT-4 mRNA, such that expression was increased in both the soleus (100% ↑P < 0.05) and EDL (142% ↑P < 0.01) in CHO-fed animals. Trained rats fed with FAT decreased mRNA expression in the EDL (↓ 45%, P < 0.05) but not the soleus (↓ 14%, NS). We conclude that exercise training in CHO-fed rats increased both GLUT-4 protein and mRNA expression in type I and type II skeletal muscle. Despite lower GLUT-4 mRNA in muscles from fat-fed animals, exercise-induced increases in GLUT-4 protein were largely preserved, suggesting that control of GLUT-4 protein and gene expression are modified independently by exercise and diet.

Identification of genes in the liver of Psammomys obesus associated with Type II diabetes

Type II diabetes is characterised by hyperglycemia and disturbances of fat, carbohydrate and protein metabolism. It occurs mainly in adults, with obesity being the most modifiable risk factor. This project utilised the Israeli Sand Rat (Psammomys obesus) and some of the latest molecular biology technology including differential display, membrane microarray and real-time PCR to detect genes in the liver that may be associated with the development of Type II diabetes and/or obesity. This study showed calpain, a proteolytic inhibitor and calpastatin, its natural inhibitor to be disregulated in the liver during the diabetic state.

Transcriptional regulation of the yghJ-pppA-yghG-gspCDEFGHIJKLM cluster, encoding the type II secretion pathway in Enterotoxigenic Escherichia coli

The gene cluster gspCDEFGHIJKLM codes for various structural components of the type II secretion pathway which is responsible for the secretion of heat-labile enterotoxin by enterotoxigenic Escherichia coli (ETEC). In this work, we used a variety of molecular approaches to elucidate the transcriptional organization of the ETEC type II secretion system and to unravel the mechanisms by which the expression of these genes is controlled. We showed that the gspCDEFGHIJKLM cluster and three other upstream genes, yghJ, pppA, and yghG, are cotranscribed and that a promoter located in the upstream region of yghJ plays a major role in the expression of this 14-gene transcriptional unit. Transcription of the yghJ promoter was repressed 168-fold upon a temperature downshift from 37°C to 22°C. This temperature-induced repression was mediated by the global regulatory proteins H-NS and StpA. Deletion mutagenesis showed that the promoter region encompassing positions −321 to +301 relative to the start site of transcription of yghJ was required for full repression. The yghJ promoter region is predicted to be highly curved and bound H-NS or StpA directly. The binding of H-NS or StpA blocked transcription initiation by inhibiting promoter open complex formation. Unraveling the mechanisms of regulation of type II secretion by ETEC enhances our understanding of the pathogenesis of ETEC and other pathogenic varieties of E. coli.

The type II secretion system and its ubiquitous lipoprotein substrate, SsIE are required for biofilm formation and virulence of enteropathogenic escherichia coli

Enteropathogenic Escherichia coli (EPEC) is a major cause of diarrhea in infants in developing countries. We have identified a functional type II secretion system (T2SS) in EPEC that is homologous to the pathway responsible for the secretion of heat-labile enterotoxin by enterotoxigenic E. coli. The wild-type EPEC T2SS was able to secrete a heat-labile enterotoxin reporter, but an isogenic T2SS mutant could not. We showed that the major substrate of the T2SS in EPEC is SslE, an outer membrane lipoprotein (formerly known as YghJ), and that a functional T2SS is essential for biofilm formation by EPEC. T2SS and SslE mutants were arrested at the microcolony stage of biofilm formation, suggesting that the T2SS is involved in the development of mature biofilms and that SslE is a dominant effector of biofilm development. Moreover, the T2SS was required for virulence, as infection of rabbits with a rabbit-specific EPEC strain carrying a mutation in either the T2SS or SslE resulted in significantly reduced intestinal colonization and milder disease.

The effect of oral administration of iron saturated-bovine lactoferrin encapsulated chitosan-nanocarriers on osteoarthritis

In this study, the therapeutic potentials of 100% iron saturated-bovine lactoferrin encapsulated in alginate-chitosan polymeric nanocarriers (AEC-CP-Fe-bLf-NCs) were examined in in vitro inflammatory OA model and in collagen-induced arthritis (CIA) mice. Oral administration of nanocarriers in mice were non-toxic and significantly induced disease modifying activity by reducing joint inflammation and downregulating the expression of catabolic genes, IL-1β, NO, JNK and MAPK. In addition, up-regulation of type II collagen, aggrecan and inflammation depleted iron and calcium metabolisms via inhibition of miRNA of iron transporting receptors was shown in AEC-CP-Fe-bLf-NCs treated mice.

Changes in the composition of the extracellular matrix in patellar tendinopathy

Objective: To compare the chemical levels and mRNA expression of proteoglycan and collagen in normal human patellar tendons and tendons exhibiting chronic overuse tendinopathy.

Methods: Sulfated glycosaminoglycan and hydroxyproline content were investigated by spectrophotometric measurement using papain-digested samples. Deglycosylated proteoglycan core proteins were analysed by Western blot using specific antibodies. Total mRNA isolated from samples of frozen tendons was assayed by relative quantitative RT-PCR for decorin, biglycan, fibromodulin, versican, aggrecan, and collagens Type I, II and III and normalised to glyceraldehyde-3-phosphate dehydrogenase.

Results: There was a significant increase in sulfated glycosaminoglycan content in pathologic tendons compared to normal. This was attributed to an increased deposition of the large aggregating proteoglycans versican and aggrecan and the small proteoglycans biglycan and fibromodulin, but not decorin. Aggrecan and versican were extensively degraded in both normal and pathologic tendons, biglycan was more fragmented in the pathologic tendons while predominantly intact fibromodulin and decorin were present in normal and pathologic tendons. There was a greater range in total collagen content but no change in the level of total collagen in pathologic tendons. There were no significant differences between the pathologic and normal tendon for all genes, however p values close to 0.05 indicated a trend in downregulation of Type I collagen and fibromodulin, and upregulation in versican and Type III genes in pathologic tissue.

Conclusion: The changes in proteoglycan and collagen levels observed in patellar tendinopathy appear to be primarily due to changes in the metabolic turnover of these macromolecules. Changes in the expression of these macromolecules may not play a major role in this process.

Dietary regulation of fat oxidative gene expression in different skeletal musle fiber types

Objective: To determine the effect of a high-fat diet on the expression of genes important for fat oxidation, the protein abundance of the transcription factors peroxisome proliferator-activated receptor (PPAR) isoforms α and γ, and selected enzyme activities in type I and II skeletal muscle. Research Methods and Procedures: Sprague-Dawley rats consumed either a high-fat (HF: 78% energy, n = 8) or high-carbohydrate (64% energy, n = 8) diet for 8 weeks while remaining sedentary. Results: The expression of genes important for fat oxidation tended to increase in both type I (soleus) and type II (extensor digitorum longus) fiber types after an HF dietary intervention. However, the expression of muscle type carnitine palmitoyltransferase I was not increased in extensor digitorum longus. Analysis of the gene expression of both peroxisome proliferator-activated receptor-γ coactivator and forkhead transcription factor O1 demonstrated no alteration in response to the HF diet. Similarly, PPARα and PPARγ protein levels were also not altered by the HF diet. Discussion: An HF diet increased the expression of an array of genes involved in lipid metabolism, with only subtle differences evident in the response within differing skeletal muscle fiber types. Despite changes in gene expression, there were no effects of diet on peroxisome proliferator-activated receptor-gamma coactivator and forkhead transcription factor O1 mRNA and the protein abundance of PPARα and PPARγ.

What are we looking at, and how big is it?

Some of the most important outcomes of physical therapy treatment have to do with behaviour and quality of life. This article involves examining what it is we are measuring in physical therapy research and what those measurements mean. In looking at differences between groups (e.g. placebo-control) or strength of association between variables (e.g. correlation, regression) the practitioner/researcher must consider what are meaningful magnitudes of effects. Depending on the variable that one measures, a medium effect size (e.g. Cohen's d=0.50) may, in the real world, be insignificant, or in the case of elite athletic performance such an effect size might be gigantic. A major problem in the sports sciences is the confusion of p values and significance testing with the results of interest, the magnitudes of effects. Also, the prevalence of possible Type II errors in the sports sciences and medicine may be quite high in light of the small sample sizes and the paucity of power analyses for non-significant results. We make an appeal for determining a priori minimal meaningful differences (or associations) to use as the primary metrics in discussing results.

Evaluation of fixed sample-size plans for Plutella xylostella (Lepidoptera: Plutellidae) on broccoli crops in Australia

Fixed sample-size plans for monitoring Plutella xylostella (L.) (Lepidoptera: Plutellidae) on broccoli and other Brassica vegetable crops are popular in Australia for their simplicity and ease of application. But the sample sizes used are often small, ≈10–25 plants per crop, and it may be that they fail to provide sufficient information upon which to base pest control decisions. We tested the performance of seven fixed sample-size plans (10, 15, 20, 30, 35, 40, and 45 plants) by resampling a large data set on P. xylostella in commercial broccoli crops. For each sample size, enumerative and presence-absence plans were assessed. The precision of the plans was assessed in terms of the ratio of the standard error to the mean; and at least 45 and 35 samples were necessary for the enumerative and presence-absence plans, respectively, to attain the generally accepted benchmark of ≤0.3. Sample sizes of 10–20 were highly imprecise. We also assessed the consequences of classifications based on action thresholds (ATs) of 0.2 and 0.8 larvae per plant for the enumerative case, and 0.15 and 0.45 proportion of plants of infested for the presence-absence case. Operating characteristic curves and investigations of the frequency of correct decisions suggest improvements in the performance of plans with increased sample size. In both the enumerative and presence-absence cases, the proportion of incorrect decisions was much higher for the lower of the two ATs assessed, and type II errors (i.e., failure to suggest pest control upon the AT is exceeded) generally accounted for the majority of this error. Type II errors are the most significant from a producer’s standpoint. Further consideration is necessary to determine what is an acceptable type II error rate.

Applying GIS in physical activity research: community walkability and walking behaviours.

Physical activity provides many health benefits, including reduced risk of cardiovascular disease, Type II diabetes and some cancers. Environmental exposure factors (e.g., the built environment) are now receiving ever-increasing attention. Large-scale interdisciplinary studies on the association between attributes of local community environments and residents’ physical activity are being conducted. We will focus on findings from Australia - the Physical Activity in Localities and Community Environments (PLACE) study. PLACE is examining factors that may influence the prevalence and the social and spatial distribution of walking for transport and walking for recreation. A stratified two-stage cluster sampling strategy was used to select 32 urban communities (154 census collection districts), classified as high and low ‘walkable’ using a GISbased walkability index (dwelling density, intersection density, net retail area and land use mix) and matched for socio-economic status. We report data on a sub-sample of 1,216 residents who provided information on the perceived attributes of their community environments (e.g., dwelling density, access to services, street connectivity) and weekly minutes of walking for transport and for recreation. Moderate to strong associations were found between GIS indicators of walkability and the corresponding self-report measures. The walkability index explained the same amount of neighborhood-level variance in walking for transport as did the complete set of self-report measures. No significant associations were found with walking for recreation. Relevant GIS-based indices of walkability, for purposes other than transport need to be   developed.

Effect of dietary omega-3 fatty acid deficiency on heart rate variability in hooded rats

Introduction: Recent reports in adult humans suggest that heart rate variability is modulated by the concentration of omega-3 polyunsaturated fatty acids (PUFA) contained in blood cell membranes. Material and methods: Hurst analysis of ECG data was conducted on 12 male adult hooded (Long-Evans) rats, representing the 3rd generation to be fed diets that were either deficient in, or supplemented with, omega-3 PUFA. ECG data were obtained from surface electrodes and 4000 beats were analyzed for each animal. Results: Dietary manipulation, despite leading to large changes in tissue omega- 3 PUFA levels, did not significantly affect the complexity of heart rate dynamics, with Hurst exponent (H) values of 0.15±0.02 and 0.12±0.03, for animals fed omega- 3 fatty acid-adequate and -deficient diets, respectively. Mean heart rate was also unaffected by the diets. A power calculation revealed that about one hundred animals per group would have been required to avoid a type II error. Conclusions: According to this model of dietary PUFA manipulation, omega-3 fatty acids are unlikely to exert a large effect on the autonomic functions that control heart rate variability. Prospective studies into the effect of omega-3 fatty acids on HRV should consider the need for large sample size as estimated by the results contained in this report.

Intertester reliability of sonography in patellar tendinopathy

Objective. Intertester reliability is imperative during the sonographic assessment of patellar tendinopathy because hypoechoic areas can change over time, and repeated examination may involve multiple examiners. Given that, to our knowledge, it has not been reported in the literature, the objective of this study was to investigate the intertester reliability of sonography for the detection and measurement of hypoechoic areas associated with patellar tendinopathy.

Methods. The study cohort comprised 8 patients with clinically diagnosed patellar tendinopathy and 4 patients with bilateral asymptomatic patellar tendons. Two equally experienced musculoskeletal radiologists imaged both patellar tendons from each patient (n = 24). All 24 tendons were assessed on the same day with the use of identical sonography machines.

Results. The radiologists had 100% chance-corrected agreement for detecting 12 normal (hypoechoic free) and 12 abnormal (hypoechoic) tendons. All measurement data were normally distributed (P > .05), and a range of hypoechoic area sizes was evident. No statistically significant differences were found for the measurements of hypoechoic area, axial plane height and width, and sagittal plane height (P > .05). In addition, these measurements were equally highly correlated (Pearson r > 0.87; P < .01).

Conclusions. The results reported in this study suggest that the intertester
reliability of sonography for the assessment of patellar tendinopathy is high. Although these results are encouraging, a small sample was analyzed, and this increases the probability of type II measurement error. Larger studies are therefore required to confirm these findings. High intertester reliability indicates that multiple experienced radiologists can reliably assess the same tendon and provides researchers with a necessary foundation for furthering research in tendon rehabilitation.