Inhibitory effect of neuropeptide Y on stimulated renin secretion of awake rats.

1. (1-36)-NPY is a vasoconstrictor peptide widely distributed in sympathetic nerve terminals. This peptide exerts an inhibitory action on renin release induced by various stimuli. Post-synaptic neuropeptide Y (NPY) receptors show a high affinity for (1-36)-NPY as well as for the agonist (Pro34)-NPY, while presynaptic receptors bind preferentially (13-36)-NPY. 2. This study was undertaken to assess whether the NPY induced renin suppression in awake normotensive rats infused with the beta-adrenoceptor stimulant isoproterenol is mediated by activation of pre- or post-synaptic receptors. 3. Non-pressor doses of (1-36)-NPY and (Pro34)-NPY markedly attenuated the renin secretion triggered by isoproterenol whereas (13-36)-NPY had no effect. This suggests that the effect of NPY on renin release is due to the stimulation of post-synaptic receptors. However it remains unknown whether NPY acts directly on juxtaglomerular cells or indirectly by modifying intraglomerular haemodynamics.

Effect of a small dose of alcohol on the endurance performance of trained cyclists.

AIM: The aim of this study was to investigate the effect of an acute small ethanol (EtOH) dose (0.5 ml EtOH/kg fat-free mass, combined with carbohydrate) in a drink on endurance performance of trained cyclists. METHODS: Thirteen well-trained male cyclists took part in this study. A 60-min cycling endurance performance test (time trial) was performed in a calorimetric chamber after drinking an EtOH (30 +/- 1.8 ml) or a non-EtOH control (C) drink. RESULTS: Overall, EtOH induced a significant decrease in the average cycling power output (PO) (EtOH: 233 +/- 23 W versus C: 243 +/- 24 W, P < 0.01). The time course of mechanical PO showed an early decrease during the EtOH trial as compared to C (P < 0.01). Due to the lower PO, oxygen consumption, carbon dioxide production and glucose oxidation were significantly lower (P < 0.05) as compared to C. Relative to PO, heart rate response and ratings of perceived exertion (RPE) were increased by EtOH as compared to C (P < 0.05). In contrast, EtOH did not influence gross work efficiency, glycaemia and blood lactate concentration. CONCLUSIONS: These results show that the acute low dose of EtOH decreased endurance performance. An increase of cardio-vascular strain and psychobiological mechanisms may explain this decrease of endurance performance.

Modifying effect of dual antiplatelet therapy on incidence of stent thrombosis according to implanted drug-eluting stent type.

AIM: To investigate the putative modifying effect of dual antiplatelet therapy (DAPT) use on the incidence of stent thrombosis at 3 years in patients randomized to Endeavor zotarolimus-eluting stent (E-ZES) or Cypher sirolimus-eluting stent (C-SES). METHODS AND RESULTS: Of 8709 patients in PROTECT, 4357 were randomized to E-ZES and 4352 to C-SES. Aspirin was to be given indefinitely, and clopidogrel/ticlopidine for ≥3 months or up to 12 months after implantation. Main outcome measures were definite or probable stent thrombosis at 3 years. Multivariable Cox regression analysis was applied, with stent type, DAPT, and their interaction as the main outcome determinants. Dual antiplatelet therapy adherence remained the same in the E-ZES and C-SES groups (79.6% at 1 year, 32.8% at 2 years, and 21.6% at 3 years). We observed a statistically significant (P = 0.0052) heterogeneity in treatment effect of stent type in relation to DAPT. In the absence of DAPT, stent thrombosis was lower with E-ZES  vs. C-SES (adjusted hazard ratio 0.38, 95% confidence interval 0.19, 0.75; P = 0.0056). In the presence of DAPT, no difference was found (1.18; 0.79, 1.77; P = 0.43). CONCLUSION: A strong interaction was observed between drug-eluting stent type and DAPT use, most likely prompted by the vascular healing response induced by the implanted DES system. These results suggest that the incidence of stent thrombosis in DES trials should not be evaluated independently of DAPT use, and the optimal duration of DAPT will likely depend upon stent type (Clinicaltrials.gov number NCT00476957).

Effect of SR 49059, a V1a vasopressin receptor antagonist, in Raynaud's phenomenon.

OBJECTIVE: To assess whether vasopressin V1a receptor blockade reduces the abnormal vasoactive response to cold in patients suffering from Raynaud's phenomenon (RP). METHODS: SR 49059, an orally active, non-peptidic vasopressin V1a receptor antagonist, was given orally (300 mg once daily) to 20 patients with RP in a single-centre, double-blind, placebo-controlled, randomized cross-over study with two 7-day periods of treatment separated by 21 days of washout. Bilateral finger systolic blood pressure and skin temperature were assessed before and after immersion of the hand in cold water for 3 min (15 degrees C) during the screening phase and three times (before and 2 and 4 h after drug intake) on days 1 and 7 of each of the two treatment periods. Recovery of digital pressure and skin temperature was measured 0, 10, 20 and 32 min after the end of the cold immersion test. RESULTS: SR 49059 significantly attenuated the cold-induced fall in systolic pressure by 14.5% (95% confidence interval 0-29; P = 0.045) on the most affected hand on day 7 compared with placebo. Temperature recovery after the end of the cold test showed a trend to enhancement 2 and 4 h after SR 49059 on day 7 (P = 0.060 and P = 0.062 respectively). The beneficial effects on finger pressure and temperature recovery were obtained without changes in supine blood pressure or in heart rate. CONCLUSION: SR 49059 given orally once a day for 7 days to patients with RP showed favourable effects compared with placebo on finger systolic pressure and temperature recovery after cold immersion, without inducing side-effects.

Effect of hormone replacement therapy on vasomotor function of the coronary microcirculation in post-menopausal women with medically treated cardiovascular risk factors.

Aims The aim of this study was to evaluate the effect of hormone replacement therapy (HRT) on coronary vasomotor function in post-menopausal women (PM) with medically treated cardiovascular risk factors (RFs) in a cross-sectional and a longitudinal follow-up (FU) study. Methods and results Myocardial blood flow (MBF) response to cold pressor testing (CPT) and during pharmacologically induced hyperaemia was measured with positron emission tomography in pre-menopausal women (CON), in PM with HRT and without HRT, and repeated in PM after a mean FU of 24 +/- 14 months. When compared with CON at baseline, the endothelium-related change in MBF (DeltaMBF) to CPT progressively declined in PM with HRT and without HRT (0.35 +/- 0.23 vs. 0.24 +/- 0.20 and 0.16 +/- 0.12 mL/g/min; P = 0.171 and P = 0.021). In PM without HRT and in those with HRT at baseline but with discontinuation of HRT during FU, the endothelium-related DeltaMBF to CPT was significantly less at FU than at baseline (0.05 +/- 0.19 vs. 0.16 +/- 0.12 and -0.03 +/- 0.14 vs. 0.25 +/- 0.18 mL/g/min; P = 0.023 and P = 0.001), whereas no significant change was observed in PM with HRT (0.19 +/- 0.22 vs. 0.23 +/- 0.22 mL/g/min; P = 0.453). Impaired hyperaemic MBFs when compared with CON were not significantly altered from those at baseline exam. Conclusion Long-term administration of oestrogen may contribute to maintain endothelium-dependent coronary function in PM with medically treated cardiovascular RFs.

Thermogenic effect of the new beta-adrenoreceptor agonist Ro 16-8714 in healthy male volunteers.

Previous investigations in experimental animals have shown that a new type of beta-adrenoceptor agonist (Ro 16-8714) possesses both thermogenic and antihyperglycemic properties. The aim of the study was to assess the thermogenic capacity of the compound in man after acute administration. Following an overnight fast three different doses (5, 10 and 20 mg) and a placebo were given per os to six normal-weight young men. The rate of energy expenditure (EE) and substrate utilization were determined by indirect calorimetry (hood system) before and for 6 h following the drug administration. Heart rate and blood pressure as well as plasma glucose, insulin and free fatty acid (FFA) concentrations were also measured at regular intervals throughout the study. The increment relative to base-line (mean +/- s.e.m.) in EE with placebo, 5, 10 and 20 mg was 4 +/- 3, 10 +/- 2, 11 +/- 2 and 21 +/- 2 percent respectively whereas heart rate was enhanced by 2 +/- 2, 8 +/- 3, 22 +/- 2, and 49 +/- 8 percent. Systolic blood pressure increased less (1 +/- 2, 8 +/- 1, 11 +/- 1 and 13 +/- 2 percent), and diastolic blood pressure did not change significantly. Simultaneously we observed a slight and transient increase in blood glucose, insulin and FFA concentrations. It is concluded that in lean individuals Ro 16-8714 is a potent thermogenic agent; however, new beta-adrenoceptor agonists should be developed in order to avoid the tachycardia associated with the thermogenic effect.

Induced pluripotent stem cells as a promising tool to study the effect of interleukin-22 in multiple sclerosis

La sclérose en plaques (SEP) est une maladie démyélinisante du système nerveux central (SNC) provoquant des pertes motrices, sensitives et cognitives. La SEP se déclare chez le jeune adulte ayant des prédispositions génétiques, mais semble induite, par des facteurs environnementaux. La SEP touche principalement les femmes et sa prévalence dans les zones à haut risque, tel que la Suisse, est de 0.1%. Bien que son étiologie exacte reste méconnue, nous savons que la maladie est médiée par des lymphocytes T autoréactifs périphériques, qui infiltrent le SNC où ils activent d'autres cellules immunitaires ainsi que les cellules du SNC elles-mêmes, créant un foyer inflammatoire, qui va attaquer et finir par tuer les oligodendrocytes et les neurones. Les épisodes inflammatoires sont entrecoupés par des phases de rémission associées à une guérison partielle des lésions. Cette première phase de la maladie, comprenant des épisodes inflammatoires et de rémissions est appelé SEP récurrente-rémittente (SEP-RR) et touche 90% des patients. Elle évolue, dans deux-tiers des cas, vers une SEP secondaire progressive (SEP-SP), qui est caractérisée par une progression constante de la maladie, associée à une réduction de l'inflammation mais une augmentation de la neurodégénérescence. Les patients souffrants de SEP primaire progressive (SEP-PP) développent directement les symptômes de la phase progressive de la maladie. Les thérapies disponibles ont considérablement amélioré l'évolution de la maladie des patients SEP-RR, en agissant sur une diminution de la réponse immunitaire et donc de l'inflammation. Cependant, ces traitements sont inefficaces chez les patients SEP-SP et SEP-PP, n'agissant pas sur la neurodégénérescence. IL-22, une cytokine sécrétée notoirement par les cellules Th17, a été associée à la SEP en contribuant à la perméabilisation de la barrière hémato-encéphalique et à l'inflammation du SNC, qui sont des étapes clés de la pathogenèse de la maladie. En outre, le gène codant pour un inhibiteur puissant d'IL- 22, 'IL-22 binding protein' (IL-22BP), a été démontré comme un facteur de risque de la SEP. Ces indices nous ont poussés à nous intéresser de plus près au rôle de l'IL-22 dans la SEP. Nous avons pu montrer qu'IL-22 et IL-22BP étaient augmentées dans le sang des patients SEP par rapport à des sujets sains. Nous avons trouvé qu'IL-22 cible spécifiquement les astrocytes dans le SNC et que son récepteur est particulièrement exprimé dans les lésions des patient SEP. Contre toute attente, nous avons pu montrer que l'IL-22 semble soutenir la survie des astrocytes. Cette découverte, suggérant qu'IL-22 serait protecteur pour le SNC et pour la SEP, confirme de récentes publications et ouvre la voie à de potentielles applications thérapeutiques. En parallèle, dans le but de mieux comprendre l'immunopathogenèse de la SEP, nous avons développé les techniques de culture de cellules souches pluripotentes induites (iPSC). Nos iPSC sont dérivées du sang des donneurs et acquièrent toutes les propriétés des cellules souches embryonnaires après induction. Les iPSC peuvent ensuite être différenciées en différents types de cellules, dont les cellules du SNC. Nous avons ainsi pu obtenir avec succès des neurones, dérivés de cellules du sang, en passant par le stade des iPSC. La prochaine étape consiste à générer des cultures d'astrocytes et d'oligodendrocytes et ainsi obtenir les principales cellules du SNC, le but étant de former de véritables 'cerveaux-en-culture'. Cet outil semble particulièrement adapté à l'étude de l'activité de diverses molécules sur les cellules du SNC, comme par exemple l'IL-22 et d'autres molécules ayant un potentiel intérêt thérapeutique au niveau du SNC. Le but ultime étant de développer des co-cultures de cellules du SNC avec des cellules immunitaires autologues, de patients SEP et de sujets sains, afin de mettre en évidence l'attaque des cellules du SNC par des leucocytes autoréactifs. Ce projet prospectif a permis d'accroître nos connaissance sur des aspects immunitaires de la SEP et à pour but de mieux comprendre l'immunopathogenèse de la SEP afin d'élaborer de nouvelles stratégies thérapeutiques. -- La sclérose en plaques est une maladie auto-inflammatoire du système nerveux central conduisant à la destruction de la myéline, indispensable à la conduction nerveuse, et finalement à la mort des neurones eux-mêmes. Cela a pour conséquence des pertes motrices, sensorielles et cognitives, qui ont tendance à s'aggraver au fil de la maladie. Elle se déclare chez le jeune adulte, entre l'âge de 20 et 40 ans, et prédomine chez la femme. En Suisse, environ une personne sur l'OOO est atteinte de sclérose en plaques. Les causes exactes de cette maladie, qui incluent des facteurs génétiques et environnementaux, sont encore mal connues. Des traitements de plus en plus efficaces ont été développés ces dernières années et ont permis de drastiquement améliorer l'évolution de la maladie chez les patients atteints de sclérose en plaques. Cependant, ces traitements ne sont efficaces que sur certaines catégories de patients et peuvent engendrer de lourds effets secondaires. Ces thérapies agissent presque exclusivement sur les cellules du système immunitaire en les désactivant partiellement, mais pas sur les cellules nerveuses, qui sont pourtant celles qui conditionnent le devenir du patient. Le développement de médicaments protégeant ou permettant la régénération des cellules du système nerveux central est donc primordial. L'étude de l'interleukine-22 nous a permis de montrer que cette cytokine ('hormone' du système immunitaire) pouvait cibler spécifiquement les astrocytes, des cellules gliales qui jouent un rôle central dans le maintien de l'équilibre du système nerveux central. Nos recherches ont montré que cette interleukine-22 permettrait une meilleure survie des astrocytes durant la phase aiguë de la maladie et aurait aussi des propriétés neuroprotectrices. En parallèle, nous sommes en train de développer un nouveau modèle in vitro d'étude de la sclérose en plaques grâce à la technologie des cellules souches pluripotentes induites. Ces cellules souches sont induites à partir de cellules du sang du donneur et acquièrent toutes les caractéristiques des cellules souches embryonnaires présentes dans un organisme en formation. Ainsi, ces cellules souches pluripotentes ont, par exemple, la capacité de se différencier en cellules du système nerveux central. Nous avons pu, de cette manière, obtenir des neurones. Le but ultime serait de pouvoir reconstituer une ébauche de cerveau in vitro, en cultivant ensemble différents types de cellules du système nerveux central, afin d'y réaliser des expériences avec des cellules immunitaires du même donneur. Ces travaux ont pour but d'améliorer notre compréhension de la pathogenèse de la sclérose en plaques et de permettre le développement de nouvelles stratégies thérapeutiques. --Multiple sclerosis (MS) is a demyelinating disease of the central nervous system leading to cognitive, sensitive and motor disabilities. MS occurs in genetically predisposed young adults with probable environmental triggers. MS affects predominantly women and its prevalence in high risk area such as Switzerland is 0.1%. Though its exact aetiology remains undetermined, we know that autoreactive T cells from de periphery are reactivated and recruited into the central nervous system (CNS) were they further activate other immune cells and resident cells, creating inflammatory foci, where oligodendrocytes and neurons are insulted and, eventually, killed. Inflammatory episodes, called relapses, are interspersed with remission phases where partial recovery of the lesions occurs. This first phase of the disease, occurring in 90% of the patients, is called relapsing-remitting MS (RR-MS) and is leading, in two-third of the cases, to secondary-progressive MS (SP-MS), where there is a continuous steady progression of the disease, associated with reduced inflammation but increased neurodegeneration. Primary-progressive MS (PP-MS) patients experience directly this progressive phase of the disease. Whereas disease modifying therapies have dramatically ameliorated the disease course of RR-MS patients by dampening immunity and, in turn, inflammation, treatments of SP-MS and PP-MS patients, who suffer primarily from the neurodegenerative aspect of the disease, are still inexistent. IL-22, a pro-inflammatory Th17 cell cytokine, has been associated with MS by participating to blood-brain barrier infiltration and CNS inflammation, which are crucial steps in MS pathogenesis. In addition, the gene coding for IL-22 binding protein (IL-22BP), which is a potent secreted IL-22 inhibitor, has been associated with MS risk. These findings call for further investigation on the role of IL-22 in MS. We detected increased IL-22 and IL-22BP in the blood of MS patients as compared to healthy controls. Acting exclusively on cells of nonhematopoietic origin, we found that IL-22 targets specifically astrocytes in the CNS and that its receptor is highly expressed in the lesion of MS patients. Unexpectedly, we found that IL-22 seems to promote survival of astrocytes. This finding, suggesting that IL-22 might be protective for the CNS in the context of MS, is consistent with recent publications and might open putative therapeutic applications at the CNS level. In parallel, with the aim of better understanding the immunopathogenesis of MS, we developed induced pluripotent stem cell (iPSC) techniques. IPSC are derived from blood cells of the donors and bear embryonic stem cell properties. IPSC can be differentiated into various cell types including CNS cells. We successfully obtained neurons derived from the donor blood cells, through iPSC. We further aim at developing astrocytes and oligodendrocytes cultures to recreate a 'brain-in-a-dish'. This would be a powerful tool to test the activity of various compounds on CNS cells, including IL-22 and other putative neuroprotective drugs. Ultimately, the goal is to develop co-cultures of CNS cells with autologous immune cells of MS patients as well as healthy controls to try to expose evidence of CNS cells targeted by autoreactive leukocytes. This prospective project has increased our knowledge of immune aspects of MS and further aims at better understanding the immunopathology of MS in order to pave the way to the elaboration of new therapeutic strategies.

Effect of oral nitrate supplementation on pulmonary hemodynamics during exercise and time trial performance in normoxia and hypoxia: a randomized controlled trial.

BACKGROUND: Hypoxia-induced pulmonary vasoconstriction increases pulmonary arterial pressure (PAP) and may impede right heart function and exercise performance. This study examined the effects of oral nitrate supplementation on right heart function and performance during exercise in normoxia and hypoxia. We tested the hypothesis that nitrate supplementation would attenuate the increase in PAP at rest and during exercise in hypoxia, thereby improving exercise performance. METHODS: Twelve trained male cyclists [age: 31 ± 7 year (mean ± SD)] performed 15 km time-trial cycling (TT) and steady-state submaximal cycling (50, 100, and 150 W) in normoxia and hypoxia (11% inspired O2) following 3-day oral supplementation with either placebo or sodium nitrate (0.1 mmol/kg/day). We measured TT time-to-completion, muscle tissue oxygenation during TT and systolic right ventricle to right atrium pressure gradient (RV-RA gradient: index of PAP) during steady state cycling. RESULTS: During steady state exercise, hypoxia elevated RV-RA gradient (p > 0.05), while oral nitrate supplementation did not alter RV-RA gradient (p > 0.05). During 15 km TT, hypoxia lowered muscle tissue oxygenation (p < 0.05). Nitrate supplementation further decreased muscle tissue oxygenation during 15 km TT in hypoxia (p < 0.05). Hypoxia impaired time-to-completion during TT (p < 0.05), while no improvements were observed with nitrate supplementation in normoxia or hypoxia (p > 0.05). CONCLUSION: Our findings indicate that oral nitrate supplementation does not attenuate acute hypoxic pulmonary vasoconstriction nor improve performance during time trial cycling in normoxia and hypoxia.