Effects of methylphenidate on attention in Wistar rats treated with the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4)

The aim of this study was to assess the effects of the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) on attention in rats as measured using the 5-choice-serial-reaction-time task (5CSRTT) and to investigate whether methylphenidate has effects on DSP4-treated rats. Methylphenidate is a noradrenaline and dopamine reuptake inhibitor and commonly used in the pharmacological treatment of individuals with attention deficit/hyperactivity disorder (ADHD). Wistar rats were trained in the 5CSRTT and treated with one of three doses of DSP4 or saline. Following the DSP4 treatment rats were injected with three doses of methylphenidate or saline and again tested in the 5CSRTT. The treatment with DSP4 caused a significant decline of performance in the number of correct responses and a decrease in response accuracy. A reduction in activity could also be observed. Whether or not the cognitive impairments are due to attention deficits or changes in explorative behaviour or activity remains to be investigated. The treatment with methylphenidate had no beneficial effect on the rats’ performance regardless of the DSP4 treatment. In the group without DSP4 treatment, methylphenidate led to a reduction in response accuracy and bidirectional effects in regard to parameters related to attention. These findings support the role of noradrenaline in modulating attention and call for further investigations concerning the effects of methylphenidate on attentional processes in rats

Are proton pump inhibitors the first choice for acute treatment of gastric ulcers? A meta analysis of randomized clinical trials

BACKGROUND: Gastric ulcers are a frequent problem in the United States. Proton pump inhibitors have been shown to increase healing rates and improve clinical symptoms. The objective of this study is to compare gastric ulcer healing rates for patients treated with a proton pump inhibitor (PPI) (omeprazole, rabeprazole, pantoprazole, or lansoprazole), an histamine 2- receptor antagonist (ranitidine) or placebo. METHODS: A literature search was conducted to identify randomized, controlled clinical trials that included a PPI in at least one treatment arm and assessed the gastric ulcer healing rates endoscopically. The healing rates were estimated for each treatment at specific time points, and Rate Ratios (RR) and 95% confidence intervals (CI) were estimated for each trial. RESULTS: Sixteen trials met the inclusion criteria: four compared a PPI versus placebo, nine compared a PPI versus ranitidine (no trials of rabeprazole versus ranitidine met the inclusion criteria), and three compared a newer PPI (lansoprazole, pantoprazole or rabeprazole) versus omeprazole. In relation to ranitidine, the pooled RR of PPIs (lansoprazole, omeprazole and pantoprazole) was 1.33 (95% CI 1.24 to 1.42) at four weeks. In each trial, greater improvement in the studied clinical symptoms was found with the newer PPIs (rabeprazole, pantoprazole and lansoprazole) when compared to omeprazole. CONCLUSION: In this study treatment with PPIs resulted in higher healing rates than ranitidine or placebo. This evidence suggests that the first choice for gastric ulcer treatment for the greater relief of symptoms is one of the newer PPIs

Multiplexing information flow through dynamic signalling systems

We consider how a signalling system can act as an information hub by multiplexing information arising from multiple signals. We formally define multiplexing, mathematically characterise which systems can multiplex and how well they can do it. While the results of this paper are theoretical, to motivate the idea of multiplexing, we provide experimental evidence that tentatively suggests that the NF-κB transcription factor can multiplex information about changes in multiple signals. We believe that our theoretical results may resolve the apparent paradox of how a system like NF-κB that regulates cell fate and inflammatory signalling in response to diverse stimuli can appear to have the low information carrying capacity suggested by recent studies on scalar signals. In carrying out our study, we introduce new methods for the analysis of large, nonlinear stochastic dynamic models, and develop computational algorithms that facilitate the calculation of fundamental constructs of information theory such as Kullback–Leibler divergences and sensitivity matrices, and link these methods to a new theory about multiplexing information. We show that many current models such as those of the NF-κB system cannot multiplex effectively and provide models that overcome this limitation using post-transcriptional modifications

Promotion of plasma membrane repair by vitamin E

Severe vitamin E deficiency results in lethal myopathy in animal models. Membrane repair is an important myocyte response to plasma membrane disruption injury as when repair fails, myocytes die and muscular dystrophy ensues. Here we show that supplementation of cultured cells with α-tocopherol, the most common form of vitamin E, promotes plasma membrane repair. Conversely, in the absence of α-tocopherol supplementation, exposure of cultured cells to an oxidant challenge strikingly inhibits repair. Comparative measurements reveal that, to promote repair, an anti-oxidant must associate with membranes, as α-tocopherol does, or be capable of α-tocopherol regeneration. Finally, we show that myocytes in intact muscle cannot repair membranes when exposed to an oxidant challenge, but show enhanced repair when supplemented with vitamin E. Our work suggests a novel biological function for vitamin E in promoting myocyte plasma membrane repair. We propose that this function is essential for maintenance of skeletal muscle homeostasis

THE EFFECTS OF 10 WEEKS OF CONTINUOUS CYCLING ON MUSCLE ACTIVATION OF THE VASTUS LATERALIS

Stephanie. A. Sontag*1, Michael A. TrevinoƗ2, Adam J. SterczalaƗ1, Jonathan D. MillerƗ1, and Trent J. Herdaǂ1. 1University of Kansas, Lawrence, KS; 2Armstrong State University, Savannah, GA Differences in motor unit (MU) control strategies have been reported as a function of chronic training. The effects of aerobic training on cardiovascular markers are well understood; however, less is known regarding the effects on neuromuscular behavior. PURPOSE: This study examined the effects of 10 weeks of continuous cycling training on maximal aerobic fitness (VO2MAX), maximal strength (MVC) of the leg extensors, and the electromyographic amplitude (EMGRMS)-force relationships for the vastus lateralis (VL). METHODS: Thirteen sedentary individuals (mean ± SD, age = 22.31 ± 5.34 yrs) completed 40 aerobic cycling training sessions over 10 weeks. Weeks 1 – 3 consisted of 30 mins of cycling at 70% of heart rate reserve (HRR), whereas, weeks 4 – 6 and 7 – 10 were 40 mins at 75% and 80% of HRR. Pre- and post-training, participants performed (1) incremental cycling to determine relative VO2MAX and maximal HR, and (2) MVC on an isokinetic dynamometer followed by a submaximal (70% relative to pre-training MVC) linearly increasing muscle action of the leg extensors. An EMG sensor was placed over the VL prior to strength. For the linearly increasing muscle action, linear regression models were fit to the log-transformed EMGRMS-force relationships and the slope (b term) was calculated. Separate paired samples t-tests were used to examine relative VO2MAX, MVC, and the b terms. Alpha was set at 0.05. RESULTS: There was a significant increase (P\u3c0.001) in relative VO2MAX (Pre=34.38±6.89 ml/kg/min, Post=39.87±7.30 ml/kg/min) following 10 weeks of continuous cycling training. For MVC, there was no significant difference (P=0.442) between pre- (150.17±46.38 Nm) and post-training (147.30±48.46 Nm). In addition, there was no significant difference (P=0.901) for the b terms (Pre=1.099±0.188 µV/Nm; Post=1.106±0.214 µV/Nm) from the EMGRMS-force relationships. CONCLUSION: Ten weeks of continuous cycling training improved maximal aerobic capacity while maximal strength for the leg extensors was unaffected. The EMGRMS patterns of response (b terms) during an increasing muscle action were not different between pre- and post-testing and, thus, muscle activation for the VL was unchanged following 10 weeks of continuous cycling training. This work was supported in part by a National Strength and Conditioning Association Foundation (NSCAF) Graduate Research Doctoral Grant

THE RELATIONSHIP BETWEEN FATIGUE AND ACUTE TESTOSTERONE RESPONSE FOLLOWING A FATIGUING JUMP PROTOCOL

Matthew J. Hermes1, Mandy E. Parra1, Stephanie A. Sontag1, Trent J. Herda1, Andrew C. Fry1 1The University of Kansas, Lawrence, Kansas Vertical jumping ability is often viewed as a favorable quality in athletic performance. Previous research has indicated significant relationships between basal testosterone levels and vertical jump or sprint performances for trained individuals. However, the relationship between the acute testosterone response and vertical jump fatigue following a fatiguing task remains unclear. PURPOSE: The purpose of this study was to assess the relationship between the acute testosterone response and changes in peak power output over the course of a repeated jump protocol. METHODS: 9 recreationally trained males (X±SD; age = 22.8±3.4yrs, height = 182.3±5.7cm, mass = 89.1±12.0kg) volunteered for this study. Following anthropometric data collection and standardized warmup, subjects completed a repeated jump protocol on a force platform consisting of 10 sets of maximal repeated jumps. Each set lasted 15 seconds, with 15 seconds of rest between sets. Subjects were instructed to reach 90º knee flexion, to jump maximally for each jump, and to perform as many jumps as they could per set. Peak power of the second and second to last jumps of the first and last sets were analyzed. Blood samples were taken prior to and 5 minutes after the completion of the jump protocol to determine testosterone values. Pearson product-moment correlations were used to assess the relationship between jump fatigue and changes in testosterone (p\u3c.05). RESULTS: No significant relationships were found between absolute changes in testosterone and changes in peak power within the first set (p=0.37, r=0.34), within the last set (p=0.29, r=0.40), or between the first and last sets (p=0.18, r=0.49). In addition, relative changes between changes in testosterone and changes in peak power within the first set (p=0.48, r=0.27), within the last set (p=0.40, r=0.32), and between first and last sets (p=0.26, r=0.42) yielded no significant relationships. CONCLUSION: Although previous research has indicated a relationship between basal testosterone and vertical jump performance in elite athletes, there does not appear to be a relationship between the acute testosterone response and power fatigue in recreationally trained males. However, further research is needed in order to fully assess how testosterone is affected by fatigue

BASAL TESTOSTERONE IS NOT PREDICTIVE OF VERTICAL JUMP PERFORMANCE IN RECREATIONALLY ACTIVE MALES

Jonathan D. Miller1, Matthew J. Hermes1, Mandy E. Parra1, Stephanie A. Sontag1, Trent J. Herdal & Andrew C. Fry1 1The University of Kansas, Lawrence, Kansas The vertical jump is a commonly studied measure of athletic performance. Previously, relationships between basal testosterone and vertical jumps or other measures of explosive performance have been observed in highly trained athletes. However, the relationship between basal testosterone and vertical jump performance in untrained or recreationally active individuals is less clear. PURPOSE: The purpose of this study was to assess the relationship between basal testosterone levels and vertical jump performance in recreationally active males. METHODS: 10recreationally active males (mean±SD; age = 23.0±3.3yrs, height = 182.0±5.5cm, mass = 88.1±11.7kg) participated in this study. The experimental protocol involved anthropometric data and blood sample collection, a standardized warmup, and performing counter-movement jumps (CMJ) on a force plate sampling at 1000 Hz. Subjects were instructed to perform the CMJ with arms akimbo, descend to90º knee flexion, and jump maximally. Peak force (PF), peak power (PP), eccentric rate of force development (ERFD) and jump height (JH) were quantified from the CMJ. PF and PP were normalized by body weight in Newtons for analysis. Basal testosterone levels were determined from blood samples. Pearson product-moment correlations were used to analyze relationships between CMJ performance variables (PF, PP, ERFD, and JH) and basal testosterone(α=0.05). RESULTS: No significant relationships were observed between basal testosterone levels and the CMJ performance variables (r=-0.12 ‒ 0.06, p=0.737 –0.836), including JH (r=0.08, p=0.82). In addition, PF and ERFD were unrelated to JH(r=-0.04 ‒ -0.25, p=0.483‒ 0.912), but PP was predictive of JH(r=0.90, p\u3c0.001), accounting for 81% of the variance. CONCLUSION: The training status and the homogeneity of the subjects likely play a role in the discrepancy in findings between the current study and previous studies which observed positive relationships between basal testosterone and vertical jump performance. Specifically, previous studies have used highly trained athletes, or more homogenous groups of subjects than the current study. Increased variability in confounding factors such as familiarity with maximal jumping and body adiposity likely obscure the relationship between basal testosterone and vertical jump height