International Olympic Committee consensus statement on thermoregulatory and altitude challenges for high-level athletes

Challenging environmental conditions, including heat and humidity, cold, and altitude, pose particular risks to the health of Olympic and other high-level athletes. As a further commitment to athlete safety, the International Olympic Committee (IOC) Medical Commission convened a panel of experts to review the scientific evidence base, reach consensus, and underscore practical safety guidelines and new research priorities regarding the unique environmental challenges Olympic and other international-level athletes face. For non-aquatic events, external thermal load is dependent on ambient temperature, humidity, wind speed and solar radiation, while clothing and protective gear can measurably increase thermal strain and prompt premature fatigue. In swimmers, body heat loss is the direct result of convection at a rate that is proportional to the effective water velocity around the swimmer and the temperature difference between the skin and the water. Other cold exposure and conditions, such as during Alpine skiing, biathlon and other sliding sports, facilitate body heat transfer to the environment, potentially leading to hypothermia and/or frostbite; although metabolic heat production during these activities usually increases well above the rate of body heat loss, and protective clothing and limited exposure time in certain events reduces these clinical risks as well. Most athletic events are held at altitudes that pose little to no health risks; and training exposures are typically brief and well-tolerated. While these and other environment-related threats to performance and safety can be lessened or averted by implementing a variety of individual and event preventative measures, more research and evidence-based guidelines and recommendations are needed. In the mean time, the IOC Medical Commission and International Sport Federations have implemented new guidelines and taken additional steps to mitigate risk even further.

High-level molecular diversity of copper-zinc superoxide dismutase genes among and within species of arbuscular Mycorrhizal fungi.

In the ecologically important arbuscular mycorrhizal fungi (AMF), Sod1 encodes a functional polypeptide that confers increased tolerance to oxidative stress and that is upregulated inside the roots during early steps of the symbiosis with host plants. It is still unclear whether its expression is directed at scavenging reactive oxygen species (ROS) produced by the host, if it plays a role in the fungus-host dialogue, or if it is a consequence of oxidative stress from the surrounding environment. All these possibilities are equally likely, and molecular variation at the Sod1 locus can possibly have adaptive implications for one or all of the three mentioned functions. In this paper, we analyzed the diversity of the Sod1 gene in six AMF species, as well as 14 Glomus intraradices isolates from a single natural population. By sequencing this locus, we identified a large amount of nucleotide and amino acid molecular diversity both among AMF species and individuals, suggesting a rapid divergence of its codons. The Sod1 gene was monomorphic within each isolate we analyzed, and quantitative PCR strongly suggest this locus is present as a single copy in G. intraradices. Maximum-likelihood analyses performed using a variety of models for codon evolution indicated that a number of amino acid sites most likely evolved under the regime of positive selection among AMF species. In addition, we found that some isolates of G. intraradices from a natural population harbor very divergent orthologous Sod1 sequences, and our analysis suggested that diversifying selection, rather than recombination, was responsible for the persistence of this molecular diversity within the AMF population.

International Olympic Committee consensus statement on thermoregulatory and altitude challenges for high-level athletes.

Challenging environmental conditions, including heat and humidity, cold, and altitude, pose particular risks to the health of Olympic and other high-level athletes. As a further commitment to athlete safety, the International Olympic Committee (IOC) Medical Commission convened a panel of experts to review the scientific evidence base, reach consensus, and underscore practical safety guidelines and new research priorities regarding the unique environmental challenges Olympic and other international-level athletes face. For non-aquatic events, external thermal load is dependent on ambient temperature, humidity, wind speed and solar radiation, while clothing and protective gear can measurably increase thermal strain and prompt premature fatigue. In swimmers, body heat loss is the direct result of convection at a rate that is proportional to the effective water velocity around the swimmer and the temperature difference between the skin and the water. Other cold exposure and conditions, such as during Alpine skiing, biathlon and other sliding sports, facilitate body heat transfer to the environment, potentially leading to hypothermia and/or frostbite; although metabolic heat production during these activities usually increases well above the rate of body heat loss, and protective clothing and limited exposure time in certain events reduces these clinical risks as well. Most athletic events are held at altitudes that pose little to no health risks; and training exposures are typically brief and well-tolerated. While these and other environment-related threats to performance and safety can be lessened or averted by implementing a variety of individual and event preventative measures, more research and evidence-based guidelines and recommendations are needed. In the mean time, the IOC Medical Commission and International Sport Federations have implemented new guidelines and taken additional steps to mitigate risk even further.

High-level transgene expression by homologous recombination-mediated gene transfer.

Gene transfer and expression in eukaryotes is often limited by a number of stably maintained gene copies and by epigenetic silencing effects. Silencing may be limited by the use of epigenetic regulatory sequences such as matrix attachment regions (MAR). Here, we show that successive transfections of MAR-containing vectors allow a synergistic increase of transgene expression. This finding is partly explained by an increased entry into the cell nuclei and genomic integration of the DNA, an effect that requires both the MAR element and iterative transfections. Fluorescence in situ hybridization analysis often showed single integration events, indicating that DNAs introduced in successive transfections could recombine. High expression was also linked to the cell division cycle, so that nuclear transport of the DNA occurs when homologous recombination is most active. Use of cells deficient in either non-homologous end-joining or homologous recombination suggested that efficient integration and expression may require homologous recombination-based genomic integration of MAR-containing plasmids and the lack of epigenetic silencing events associated with tandem gene copies. We conclude that MAR elements may promote homologous recombination, and that cells and vectors can be engineered to take advantage of this property to mediate highly efficient gene transfer and expression.

Bilateral symmetry of radial pulse in high-level tennis players: implications for the validity of central aortic pulse wave analysis.

BACKGROUND: Reconstruction of the central aortic pressure wave from the noninvasive recording of the radial pulse with applanation tonometry has become a standard tool in the field of hypertension. It is not presently known whether recording the radial pulse on the dominant or the nondominant side has any effect on such reconstruction. METHOD: We carried out radial applanation tonometry on both forearms in young, healthy, male volunteers, who were either sedentary (n = 11) or high-level tennis players (n = 10). The purpose of including tennis players was to investigate individuals with extreme asymmetry between the dominant and nondominant upper limb. RESULTS: In the sedentary individuals, forearm circumference and handgrip strength were slightly larger on the dominant (mean +/- SD respectively 27.9 +/- 1.5 cm and 53.8 +/- 10 kg) than on nondominant side (27.3 +/- 1.6 cm, P < 0.001 vs. dominant, and 52.1 +/- 11 kg, P = NS). In the tennis players, differences between sides were more conspicuous (forearm circumference: dominant 28.0 +/- 1.7 cm nondominant 26.4 +/- 1.5 cm, P < 0.001; handgrip strength 61.4 +/- 10.8 vs. 53.4 +/- 9.7 kg, P < 0.001). We found that in both sedentary individuals and tennis players, the radial pulse had identical shape on both sides and, consequently, the reconstructed central aortic pressure waveforms, as well as derived indices of central pulsatility, were not dependent on the side where applanation tonometry was carried out. CONCLUSION: Evidence from individuals with maximal asymmetry of dominant vs. nondominant upper limb indicates that laterality of measurement is not a methodological issue for central pulse wave analysis carried out with radial applanation tonometry.

Hyperpolarizing gases via dynamic nuclear polarization and sublimation.

A high throughput method was designed to produce hyperpolarized gases by combining low-temperature dynamic nuclear polarization with a sublimation procedure. It is illustrated by applications to 129Xe nuclear magnetic resonance in xenon gas, leading to a signal enhancement of 3 to 4 orders of magnitude compared to the room-temperature thermal equilibrium signal at 7.05 T.

High level expression of human neuropeptide Y receptors in mammalian cells infected with a recombinant vaccinia virus.

Neuropeptide Y (NPY) is a 36 amino acid peptide present in the central and peripheral nervous system. Numerous studies point to a role of NPY in cardiovascular regulation. NPY effects are mediated through stimulation of specific cell surface G protein-coupled receptors. To allow biochemical studies of the receptor and of its interaction with the ligand, we have developed a potent expression system for NPY receptors using a recombinant vaccinia virus. A human NPY receptor cDNA was fused to a strong vaccinia virus promoter and inserted into the viral genome by homologous recombination. Recombinant viruses were isolated and tested for their ability to induce NPY binding site expression following infection of mammalian cell lines. Using saturation and competition binding experiments we measured a Bmax of 5-10 x 10(6) NPY binding sites per cell. The Kd for the binding of NPY is about 20 nM. Labelling of infected cells with a fluorochrome-labelled NPY indicated that the recombinant protein integrates into the cell membrane.

Expression hierarchy of T cell epitopes from melanoma differentiation antigens: unexpected high level presentation of tyrosinase-HLA-A2 Complexes revealed by peptide-specific, MHC-restricted, TCR-like antibodies.

Peptide Ags presented by class I MHC molecules on human melanomas and that are recognized by CD8(+) T cells are the subjects of many studies of antitumor immunity and represent attractive candidates for therapeutic approaches. However, no direct quantitative measurements exist to reveal their expression hierarchy on the cell surface. Using novel recombinant Abs which bind these Ags with a peptide-specific, MHC-restricted manner, we demonstrate a defined pattern of expression hierarchy of peptide-HLA-A2 complexes derived from three major differentiation Ags: gp100, Melan-A/Mart-1, and tyrosinase. Studying melanoma cell lines derived from multiple patients, we reveal a surprisingly high level of presentation of tyrosinase-derived complexes and moderate to very low expression of complexes derived from other Ags. No correlation between Ag presentation and mRNA expression was found; however, protein stability may play a major role. These results provide new insights into the characteristics of Ag presentation and are particularly important when such targets are being considered for immunotherapy. These results may shed new light on relationships between Ag presentation and immune response to cancer Ags.

Bilateral symmetry of radial pulse in high-level tennis players : implications for the validity of central aortic pulse wave analysis

Rapport de synthèse Ce travail de thèse s'articule autour de l'importance de l'évaluation de la fonction vasculaire et des répercussions au niveau central, cardiaque, des perturbations du réseau vasculaire. Les maladies cardiovasculaires sont prédominantes dans notre société et causes de morbidité et mortalité importante. La mesure de la pression artérielle classique reste le moyen le plus utilisé pour suivre la santé des vaisseaux, mais ne reflète pas directement ce qui se passe au niveau du coeur. La tonométrie d'aplanation permet depuis quelques années de mesurer l'onde de pouls radial, et par le biais d'une fonction mathématique de transfert validée, il est possible d'en déduire la forme et Γ amplitude de l'onde de pouls central, donc de la pression aortique centrale. Cette dernière est un reflet bien plus direct de la post-charge cardiaque, et de nombreuses études cliniques actuelles s'intéressent à cette mesure pour stratifier le risque ou évaluer l'effet d'un traitement vasculaire. Toutefois, bien que cet outil soit de plus en plus utilisé, il est rarement précisé si la latéralité de la mesure joue un rôle, sachant que certaines propriétés des membres supérieurs peuvent être affectées par un usage préférentiel (masse musculaire, densité osseuse, diamètre des artères, capillarisation musculaire, et même fonction endothéliale). On a en effet observé que ces divers paramètre étaient tous augmentés sur un bras entraîné. Dès lors on peut se poser la question de l'influence de ces adaptations physiologiques sur la mesure indirecte effectuée par le biais du pouls radial. Nous avons investigué les deux membres supérieurs de sujets jeunes et sédentaires (SED), ainsi que ceux de sujets sportifs avec un développement fortement asymétrique des bras, soit des joueurs de tennis de haut niveau (TEN). Des mesures anthropométriques incluant la composition corporelle et la circonférence des bras et avant-bras ont montré que TEN présente une asymétrie hautement significative aux deux mesures entre le bras dominant (entraîné) et l'autre, ce qui est aussi présent pour la force de serrage (mesurée au dynamomètre de Jamar). L'analyse des courbes centrales de pouls ne montre aucune différence entre les deux membres dans chaque groupe, par contre on peut observer une différence entre SED et TEN, avec un index d'augmentation diastolique qui est 50 % plus élevé chez TEN. Les index d'augmentation systolique sont identiques dans les deux groupes. On peut retenir de cette étude la validité de la méthode de tonométrie d'aplanation quel que soit le bras utilisé (dominant ou non-dominant) et ce même si une asymétrie conséquente est présente. Ces données sont clairement nouvelles et permettent de s'affranchir de cette variable dans la mesure d'un paramètre cardiovasculaire dont l'importance est actuellement grandissante. Les différences d'index diastolique sont expliquées par la fréquence cardiaque et la vitesse de conduction de l'onde de pouls plus basses chez TEN, causant un retard diastolique du retour de l'onde au niveau central, phénomène précédemment bien décrit dans la littérature.

Calpastatin-mediated inhibition of calpains in the mouse brain prevents mutant ataxin 3 proteolysis, nuclear localization and aggregation, relieving Machado-Joseph disease.

Machado-Joseph disease is the most frequently found dominantly-inherited cerebellar ataxia. Over-repetition of a CAG trinucleotide in the MJD1 gene translates into a polyglutamine tract within the ataxin 3 protein, which upon proteolysis may trigger Machado-Joseph disease. We investigated the role of calpains in the generation of toxic ataxin 3 fragments and pathogenesis of Machado-Joseph disease. For this purpose, we inhibited calpain activity in mouse models of Machado-Joseph disease by overexpressing the endogenous calpain-inhibitor calpastatin. Calpain blockage reduced the size and number of mutant ataxin 3 inclusions, neuronal dysfunction and neurodegeneration. By reducing fragmentation of ataxin 3, calpastatin overexpression modified the subcellular localization of mutant ataxin 3 restraining the protein in the cytoplasm, reducing aggregation and nuclear toxicity and overcoming calpastatin depletion observed upon mutant ataxin 3 expression. Our findings are the first in vivo proof that mutant ataxin 3 proteolysis by calpains mediates its translocation to the nucleus, aggregation and toxicity and that inhibition of calpains may provide an effective therapy for Machado-Joseph disease.

STAT3α interacts with nuclear GSK3beta and cytoplasmic RISK pathway and stabilizes rhythm in the anoxic-reoxygenated embryonic heart.

Activation of the Janus Kinase 2/Signal Transducer and Activator of Transcription 3 (JAK2/STAT3) pathway is known to play a key role in cardiogenesis and to afford cardioprotection against ischemia-reperfusion in adult. However, involvement of JAK2/STAT3 pathway and its interaction with other signaling pathways in developing heart transiently submitted to anoxia remains to be explored. Hearts isolated from 4-day-old chick embryos were submitted to anoxia (30 min) and reoxygenation (80 min) with or without the antioxidant MPG, the JAK2/STAT3 inhibitor AG490 or the PhosphoInositide-3-Kinase (PI3K)/Akt inhibitor LY-294002. Time course of phosphorylation of STAT3α(tyrosine705) and Reperfusion Injury Salvage Kinase (RISK) proteins [PI3K, Akt, Glycogen Synthase Kinase 3beta (GSK3beta), Extracellular signal-Regulated Kinase 2 (ERK2)] was determined in homogenate and in enriched nuclear and cytoplasmic fractions of the ventricle. STAT3 DNA-binding was determined. The chrono-, dromo- and inotropic disturbances were also investigated by electrocardiogram and mechanical recordings. Phosphorylation of STAT3α(tyr705) was increased by reoxygenation, reduced (~50%) by MPG or AG490 but not affected by LY-294002. STAT3 and GSK3beta were detected both in nuclear and cytoplasmic fractions while PI3K, Akt and ERK2 were restricted to cytoplasm. Reoxygenation led to nuclear accumulation of STAT3 but unexpectedly without DNA-binding. AG490 decreased the reoxygenation-induced phosphorylation of Akt and ERK2 and phosphorylation/inhibition of GSK3beta in the nucleus, exclusively. Inhibition of JAK2/STAT3 delayed recovery of atrial rate, worsened variability of cardiac cycle length and prolonged arrhythmias as compared to control hearts. Thus, besides its nuclear translocation without transcriptional activity, oxyradicals-activated STAT3α can rapidly interact with RISK proteins present in nucleus and cytoplasm, without dual interaction, and reduce the anoxia-reoxygenation-induced arrhythmias in the embryonic heart.

Nuclear translocation and DNA recognition signals colocalized within the bZIP domain of cyclic adenosine 3',5'-monophosphate response element-binding protein CREB.

CREB is a cAMP-responsive nuclear DNA-binding protein that binds to cAMP response elements and stimulates gene transcription upon activation of the cAMP signalling pathway. The protein consists of an amino-terminal transcriptional transactivation domain and a carboxyl-terminal DNA-binding domain (bZIP domain) comprised of a basic region and a leucine zipper involved in DNA recognition and dimerization, respectively. Recently, we discovered a testis-specific transcript of CREB that contains an alternatively spliced exon encoding multiple stop codons. CREB encoded by this transcript is a truncated protein lacking the bZIP domain. We postulated that the antigen detected by CREB antiserum in the cytoplasm of germinal cells is the truncated CREB that must also lack its nuclear translocation signal (NTS). To test this hypothesis we prepared multiple expression plasmids encoding carboxyl-terminal deletions of CREB and transiently expressed them in COS-1 cells. By Western immunoblot analysis as well as immunocytochemistry of transfected cells, we show that CREB proteins truncated to amino acid 286 or shorter are sequestered in the cytoplasm, whereas a CREB of 295 amino acids is translocated into the nucleus. Chimeric CREBs containing a heterologous NTS fused to the first 248 or 261 amino acids of CREB are able to drive the translocation of the protein into the nucleus. Thus, the nine amino acids in the basic region involved in DNA recognition between positions 287 and 295 (RRKKKEYVK) of CREB contain the NTS. Further, mutation of the lysine at position 290 in CREB to an asparagine diminishes nuclear translocation of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact and cost of a 2-week community-based screening and awareness program for diabetes and cardiovascular risk factors in a Swiss canton.

BACKGROUND: Community-based diabetes screening programs can help sensitize the population and identify new cases. However, the impact of such programs is rarely assessed in high-income countries, where concurrent health information and screening opportunities are common place. INTERVENTION AND METHODS: A 2-week screening and awareness campaign was organized as part of a new diabetes program in the canton of Vaud (population of 697,000) in Switzerland. Screening was performed without appointment in 190 out of 244 pharmacies in the canton at the subsidized cost of 10 Swiss Francs per participant. Screening included questions on risk behaviors, measurement of body mass index, blood pressure, blood cholesterol, random blood glucose (RBG), and A1c if RBG was >/=7.0 mmol/L. A mass media campaign promoting physical activity and a healthy diet was channeled through several media, eg, 165 spots on radio, billboards in 250 public places, flyers in 360 public transport vehicles, and a dozen articles in several newspapers. A telephone survey in a representative sample of the population of the canton was performed after the campaign to evaluate the program. RESULTS: A total of 4222 participants (0.76% of all persons aged >/=18 years) underwent the screening program (median age: 53 years, 63% females). Among participants not treated for diabetes, 3.7% had RBG >/= 7.8 mmol/L and 1.8% had both RBG >/= 7.0 mmol/L and A1c >/= 6.5. Untreated blood pressure >/=140/90 mmHg and/or untreated cholesterol >/=5.2 mmol/L were found in 50.5% of participants. One or several treated or untreated modifiable risk factors were found in 78% of participants. The telephone survey showed that 53% of all adults in the canton were sensitized by the campaign. Excluding fees paid by the participants, the program incurred a cost of CHF 330,600. CONCLUSION: A community-based screening program had low efficiency for detecting new cases of diabetes, but it identified large numbers of persons with elevated other cardiovascular risk factors. Our findings suggest the convenience of A1c for mass screening of diabetes, the usefulness of extending diabetes screening to other cardiovascular risk factors, and the importance of a robust background communication campaign.