Transient impairments in single muscle fibre contractile function after prolonged cycling in elite endurance athletes

AIM

Prolonged muscle activity impairs whole-muscle performance and function. However, little is known about the effects of prolonged muscle activity on the contractile function of human single muscle fibres. The purpose of this study was to investigate the effects of prolonged exercise and subsequent recovery on the contractile function of single muscle fibres obtained from elite athletes.

METHODS

Nine male triathletes (26 ± 1 years, 68 ± 1 mL O2  min(-1) kg(-1) , training volume 16 ± 1 h week(-1) ) performed 4 h of cycling exercise (at 73% of HRmax ) followed by 24 h of recovery. Biopsies from vastus lateralis were obtained before and following 4 h exercise and following 24 h recovery. Measurements comprised maximal Ca(2+) -activated specific force and Ca(2+) sensitivity of slow type I and fast type II single muscle fibres, as well as cycling peak power output.

RESULTS

Following cycling exercise, specific force was reduced to a similar extent in slow and fast fibres (-15 and -18%, respectively), while Ca(2+) sensitivity decreased in fast fibres only. Single fibre-specific force was fully restored in both fibre types after 24 h recovery. Cycling peak power output was reduced by 4-9% following cycling exercise and fully restored following recovery.

CONCLUSION

This is the first study to demonstrate that prolonged cycling exercise transiently impairs specific force in type I and II fibres and decreases Ca(2+) sensitivity in type II fibres only, specifically in elite endurance athletes. Further, the changes in single fibre-specific force induced by exercise and recovery coincided temporally with changes in cycling peak power output.

Electromagnetically induced transparency in a diamond spin ensemble enables all-optical electromagnetic field sensing

We use electromagnetically induced transparency (EIT) to probe the narrow electron-spin resonance of nitrogen-vacancy centers in diamond. Working with a multipass diamond chip at temperatures 6-30 K, the zero-phonon absorption line (637 nm) exhibits an optical depth of 6 and inhomogeneous linewidth of ~30 GHz FWHM. Simultaneous optical excitation at two frequencies separated by the ground-state zero-field splitting (2.88 GHz) reveals EIT resonances with a contrast exceeding 6% and FWHM down to 0.4 MHz. The resonances provide an all-optical probe of external electric and magnetic fields with a projected photon-shot-noise-limited sensitivity of 0.2 V/cm/√[Hz] and 0.1 nT/√[Hz], respectively. Operation of a prototype diamond-EIT magnetometer measures a noise floor of ~/<1 nT/√[Hz] for frequencies above 10 Hz and Allan deviation of 1.3±1.1 nT for 100 s intervals. The results demonstrate the potential of diamond-EIT devices for applications ranging from quantum-optical memory to precision measurement and tests of fundamental physics.

The parasite-host interface in the zonetail butterfly ray, Gymnura zonura (Bleeker), infected with Hexacanalis folifer (Cestoda: Lecanicephalidea)

A wild-caught specimen of the zonetail butterfly ray, Gymnura zonura (Bleeker), harboured numerous specimens of Hexacanalis folifer Cielocha & Jensen, 2011 (Systematic Parasitology, 79, 1-16; Cestoda: Lecanicephalidea) within its spiral intestine. The cestodes were primarily attached in single rows along the base of mucosal folds, each associated with a nodular mucosal thickening. Microscopically, the scolex was embedded within the submucosa and muscularis; the attachment sites were marked by ulceration and necro-proliferative inflammation demarcating the parasite from normal host tissues. Physical attachment of the cestode was restricted to the anterior portion of its scolex where presumed tegumental secretions from the apical organ contributed to a cementing intermediate layer blending with necrotic host cells. The presence of tegumental differentiation between the apical organ and the scolex proper, associated with presumed different roles in attachment, correlated with ultrastructural observations of the surface modifications on the scolex. Despite the locally severe pathological change, insignificant morbidity owing to this particular host-parasite relationship is suggested.

Abstract P1-07-02: New high-quality HER2 IQFISH pharmDx™ assay with a ½ working day procedure and high concordance to HER2 FISH pharmDx™

Introduction: HER2 assessment for selection of patients that may benefit from HER2 targeting treatment can be performed by either immunohistochemistry (IHC), fluorescence or chromogen in situ hybridization (FISH or CISH). FISH is a robust and reliable technique for direct visualization and quantitative determination of gene amplifications, deletions and translocations in human cancer cells, but FISH protocols are time-consuming and involve toxic reagents. By introducing a new non-toxic ethylene carbonate based hybridization buffer that perform with very short hybridization times, the total FISH assay time on breast cancer tissue sections can be reduced from the traditional 16–20 hours to 3½–4½ hours.

Material and methods: The new Dako HER2 IQFISH pharmDx™ was compared with Dako HER2 FISH pharmDx™ in a comparative study on 120 breast cancer specimens, and reproducibility of the HER2 IQFISH pharmDx™ assay was investigated in a study comprising 3 different sites and a total of 6 different observers. Samples for the comparative study was evaluated by Dako HercepTest™ to include all IHC scoring groups (0, 1+, 2+, 3+). Slides were stained according to manufacturer's instructions using microwave oven for heat pretreatment and RTU pepsin for 3–5 minutes at 37 °C. Hybridization was performed for 2 hours when using HER2 IQFISH pharmDx™ and for 17–20 hours when using HER2 FISH pharmDx™ Kit. All slides were blinded before evaluation. HER2 status was classified as “Non-amplified” when the HER2/CEN17 ratio &lt; 2.0 and “Amplified” when the HER2/CEN17 ratio ≥ 2.0.

Results: The new non-toxic hybridization buffer introduces a major safety improvement since formamide is no longer needed. Significantly shorter hybridization times are required to generate the same signal intensity (1–2 hour hybridization versus overnight). HER2 IQFISH pharmDx™ was compared with the traditional HER2 FISH pharmDx™ in a comparative study on 120 breast tissue specimens of human breast carcinoma. The preliminary data on HER2 status for 78 patients obtained by the two assays gave an overall agreement of 98.7% with lower and upper 95% confidence limits at 94.2% and 99.9%. The Kappa value was 0.96 (95% CL: 0.89–1.00). The p-value for McNemars test was 1.00 indicating absence of bias between the two assays. Disagreement between the two assays was observed for one specimen - a heterogeneous tissue with a small amplified area. Data from the reproducibility study that included site-to-site variation, day-to-day variation and inter-observer variation showed that the assay has a high degree of reproducibility.

Conclusion: The validation studies of the new HER2 IQFISH pharmDx™ showed a very high concordance to the traditional HER2 FISH pharmDx™ and also that the assay is robust and reproducible. Reduction of the overall assay time from a two-day to a half-day procedure for HER2 FISH, offers more flexible laboratory routines and same day reporting for all working days of the week, which could be used for fast and simultaneous FISH and IHC answers and improved patient care. Taken together, the study demonstrates the potential of a new revolutionary platform that enables optimization and acceleration of FISH analysis to the benefit of cancer patients and laboratory personnel.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-07-02.

[Evidence-based medicine in surgical practice - locating clinical studies and systematic reviews by searching the Medline database]

BACKGROUND

Every day approximately 75 clinical trials and 11 systematic reviews are published in the health-care intervention and medical field. Due to this growing number of publications it is a challenge for every practicing clinician to keep track with the latest research. The implementation of new and effective diagnostic and therapeutic interventions into daily clinical routine may thus be delayed. Conversely, ineffective or even harmful interventions might still be in use. Decision-making in evidence-based medicine (EBM) requires consideration of the most recent high quality evidence. Randomised controlled trials (RCTs) are regarded as the "gold standard" to prove the efficacy of surgical interventions in patient-oriented research. Systematic reviews combine results from RCTs by summarising single RCTs which answer a particular clinical question. Some basic knowledge in systematic literature searching is required and helpful for detecting relevant publications.

MATERIAL AND METHODS

This article shows various possibilities for locating clinical studies and systematic reviews in the database Medline on the basis of illustrative step-by-step instructions. RESULTS AND CONCLUSION. Depending on the aim and topic of the literature search, the time required for the task may vary. In routine practice, a systematic literature search is unrealistic in most cases. Clinicians in need of a quick update of current evidence on a certain clinical topic may make use of up-to-date systematic reviews. During a systematic literature search, different approaches and strategies might be necessary.

Acceptance and commitment therapy for fibromyalgia: A randomized controlled trial

Background

Recent developments within cognitive behavior therapy (CBT) have emphasized the utility of acceptance and mindfulness strategies, contrasting interventions focused on reduction or control of symptoms. A study of fMRI changes after CBT in females with fibromyalgia (FM) has been performed and results are presented elsewhere (under review). The aim of the present study was evaluate the effectiveness of Acceptance and Commitment Therapy (ACT)-based intervention for patient diagnosed with FM in comparison with a wait-list control

Method

Female patients aged 18–55 years, fulfilling the American College of Rheumatology classification criteria for FM, and with a weekly self-reported average pain intensity of >40 (VAS 0–100) were considered eligible for inclusion. Participants completed a set of questionnaires prior to treatment, immediately following the treatment and at follow 3–4 months post treatment. Primary outcome variable was pain disability (PDI). FIQ, SF36, SES, STAI, pain intensity, BDI, PIPS (psychological inflexibility in pain scale) were also used. The ACT-intervention consisted of twelve weekly group sessions, ten with psychologist and two with pain physician. Treatment was evaluated and mediation analyses were performed.

Results

Primary outcome measure (PDI): A significant improvement in pain disability for ACT in relation to the control condition, p < 0.001. Secondary outcome measures: ACT showed significant improvement in mental health quality of life, self-efficacy, depression, and anxiety. Consistent with hypotheses, ACT did not result in significant changes in either physical quality of life or pain intensity. Mediation analyses: A decrease in psychological inflexibility from pre to post assessments significantly mediated the improvement in pain disability.

Conclusion

The present study supports the utility of using a relatively brief ACT intervention in a group format for women diagnosed with fibromyalgia, and data suggests a mediating function on improvements in psychological flexibility.

Temperature- and magnetic-field-dependent longitudinal spin relaxation in nitrogen-vacancy ensembles in diamond

We present an experimental study of the longitudinal electron-spin relaxation time (T1) of negatively charged nitrogen-vacancy (NV) ensembles in diamond. T1 was studied as a function of temperature from 5 to 475 K and magnetic field from 0 to 630 G for several samples with various NV and nitrogen concentrations. Our studies reveal three processes responsible for T1 relaxation. Above room temperature, a two-phonon Raman process dominates; below room temperature, we observe an Orbach-type process with an activation energy of 73(4) meV, which closely matches the local vibrational modes of the NV center. At yet lower temperatures, sample dependent cross-relaxation processes dominate, resulting in temperature independent values of T1 from milliseconds to minutes. The value of T1 in this limit depends sensitively on the magnetic field and can be tuned by more than 1 order of magnitude.

Abstract 3875: Exploiting the Anticalin therapeutic protein platform for the treatment of cMet ligand-independent and dependent tumors - discovery and characterization of a highly specific and potent c-Met antagonist with drug-like properties

Background: Activation of the c-Met oncogenic pathway has been implicated in the development of aggressive cancers which are difficult to treat with current chemotherapies. Dimerization of c-Met receptor upon binding of Hepatocyte Growth Factor (HGF) leads to the stimulation of proliferative, migratory and survival pathways implicated in tumor development. Moreover it has recently been discovered that patients who become resistant / nonresponsive to therapies such as EGFR or VEGF inhibitors often show an enhanced c-Met expression. This has led to an increased interest in developing novel therapies that target the c-Met pathway. However, most existing drug modalities are confounded by their inability to specifically target and/or antagonize this pathway. Anticalins, a novel class of small biologics, are hypothesized to be ‘fit for purpose’ for developing highly specific and potent antagonists of cancer pathways. A monovalent Anticalin c-Met antagonist displaying efficacy in both ligand-dependent and independent cancer models has been developed. Methods/Results: Here we describe the in vitro and in vivo characterisation of the Anticalin c-Met antagonist PRS-110. In protein-based binding assays PRS-110 specifically binds to c-Met with high affinity and blocks HGF interaction (IC50 3.4 ± 0.7 nM). HUVEC cell proliferation assays demonstrated that PRS-110 efficiently antagonizes HGF-mediated growth. As a monovalent antagonist PRS-110 does not induce the c-Met pathway in the absence of ligand by receptor dimerization - an unwanted activation that can occur with bivalent antibodies. In mice, rats and non-human primates, PEGylated PRS-110 displayed favourable plasma elimination half-life profiles of 41 hours, 61 hours and 72 hours (T½α) respectively, with no signs of macrotoxicity. In vivo administration of PRS-110 resulted in significant, dose-dependent tumor growth inhibition in multiple xenograft models representative of ligand-dependent and ligand-independent c-Met activation. Analysis of c-Met protein levels on xenograft biopsy samples demonstrated a significant reduction in total c-Met (p&lt;0.01) and pMet (p&lt;0.01) following therapy with PRS-110. Furthermore, safety profiling using in silico epitope analysis and ex vivo human donor PBMC screening demonstrated a low risk of potential immunogenicity when compared to other approved biologic agents. Conclusion: Inhibition of the c-Met pathway by PRS-110 leads to attenuation of cell proliferation, dose-dependent tumour growth inhibition and a reduction in c-Met phosphorylation. Taken together these data indicate that the c-Met inhibitor PRS-110 has potentially broad anticancer activity which warrants evaluation in patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3875. doi:1538-7445.AM2012-3875

Increased steady-state VO2 and larger O2 deficit with CO2 inhalation during exercise

AIM

To examine whether inhalation of CO(2) -enriched gas would increase steady-state VO(2) during exercise and enlarge O(2) deficit.

METHODS

Ten physically active men (VO(2) 53.7 ± 3.6 mL min(-1) kg(-1) ; x ± SD) performed transitions from low-load cycling (baseline; 40 W) to work rates representing light (≈ 45% VO(2); 122 ± 15 W) and heavy (≈ 80% VO(2); 253 ± 29 W) exercise while inhaling normal air (air) or a CO(2) mixture (4.2% CO(2) , 21% O(2) , balance N(2) ). Gas exchange was measured with Douglas bag technique at baseline and at min 0-2, 2-3 and 5-6.

RESULTS

Inhalation of CO(2) -enriched air consistently induced respiratory acidosis with increases in PCO(2) and decreases in capillary blood pH (P < 0.01). Hypercapnic steady-state VO(2) was on average about 6% greater (P < 0.01) than with air in both light and heavy exercise, presumably because of increased cost of breathing (ΔVE 40-50 L min(-1) ; P < 0.01), and a substrate shift towards increased lipid oxidation (decline in R 0.12; P < 0.01). VO(2) during the first 2 min of exercise were not significantly different whereas the increase in VO(2) from min 2-3 to min 5-6 in heavy exercise was larger with CO(2) than with air suggesting a greater VO(2) slow component. As a result, O(2) deficit was greater with hypercapnia in heavy exercise (2.24 ± 0.51 L vs. 1.91 ± 0.45 L; P < 0.05) but not in light (0.64 ± 0.21 L vs. 0.54 ± 0.20 L; ns).

CONCLUSION

Inhalation of CO(2)-enriched air and the ensuing respiratory acidosis increase steady-state VO(2) in both light and heavy exercise and enlarges O(2) deficit in heavy exercise.

An anti-PCSK9 antibody reduces LDL-cholesterol on top of a statin and suppresses hepatocyte SREBP-regulated genes

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a promising therapeutic target for treating coronary heart disease. We report a novel antibody 1B20 that binds to PCSK9 with sub-nanomolar affinity and antagonizes PCSK9 function in-vitro. In CETP/LDLR-hemi mice two successive doses of 1B20, administered 14 days apart at 3 or 10 mpk, induced dose dependent reductions in LDL-cholesterol (≥ 25% for 7-14 days) that correlated well with the extent of PCSK9 occupancy by the antibody. In addition, 1B20 induces increases in total plasma antibody-bound PCSK9 levels and decreases in liver mRNA levels of SREBP-regulated genes PCSK9 and LDLR, with a time course that parallels decreases in plasma LDL-cholesterol (LDL-C). Consistent with this observation in mice, in statin-responsive human primary hepatocytes, 1B20 lowers PCSK9 and LDLR mRNA levels and raises serum steady-state levels of antibody-bound PCSK9. In addition, mRNA levels of several SREBP regulated genes involved in cholesterol and fatty-acid synthesis including ACSS2, FDPS, IDI1, MVD, HMGCR, and CYP51A1 were decreased significantly with antibody treatment of primary human hepatocytes. In rhesus monkeys, subcutaneous (SC) dosing of 1B20 dose-dependently induces robust LDL-C lowering (maximal ~70%), which is correlated with increases in target engagement and total antibody-bound PCSK9 levels. Importantly, a combination of 1B20 and Simvastatin in dyslipidemic rhesus monkeys reduced LDL-C more than either agent alone, consistent with a mechanism of action that predicts additive effects of anti-PCSK9 agents with statins. Our results suggest that antibodies targeting PCSK9 could provide patients powerful LDL lowering efficacy on top of statins, and lower cardiovascular risk.

Slide-based ergometer rowing: effects on force production and neuromuscular activity

Force production profile and neuromuscular activity during slide-based and stationary ergometer rowing at standardized submaximal power output were compared in 14 male and 8 female National Team rowers. Surface electromyography (EMG) was obtained in selected thoracic and leg muscles along with synchronous measurement of handle force and rate of force development (RFD). Compared to stationary conditions, slide-based peak force decreased by 76 (57-95) N (mean 95% CI) in males (P < 0.001) and 20 (8-31) N (P < 0.05) in females. Stroke rate increased (+10.7%) and late-phase RFD decreased (-20.7%) in males (P < 0.05). Neuromuscular activity in m. vastus lateralis decreased in the initial drive phase from 59% to 51% of EMG max in males and from 57% to 52% in females (P < 0.01-0.05), while also decreasing in the late recovery phase from 20% to 7% in males and 17% to 7% in females (P < 0.01). Peak force and maximal neuromuscular activity in the shoulder retractors always occurred in the second quartile of the drive phase. In conclusion, peak force and late-phase RFD (males) decreased and stroke rate increased (males) during slide-based compared to stationary ergometer rowing, potentially reducing the risk of overuse injury. Neuromuscular activity was more affected in leg muscles than thoracic muscles by slide-based ergometer rowing.