Training in hypoxia fails to further enhance endurance performance and lactate clearance in well-trained men and impairs glucose metabolism during prolonged exercise.

The aim of this study was to investigate the synergistic effects of endurance training and hypoxia on endurance performance in normoxic and hypoxic conditions (approximately 3000 m above sea level) as well as on lactate and glucose metabolism during prolonged exercise. For this purpose, 14 well-trained cyclists performed 12 training sessions in conditions of normobaric hypoxia (HYP group, n = 7) or normoxia (NOR group, n = 7) over 4 weeks. Before and after training, lactate and glucose turnover rates were measured by infusion of exogenous lactate and stable isotope tracers. Endurance performance was assessed during incremental tests performed in normoxia and hypoxia and a 40 km time trial performed in normoxia. After training, performance was similarly and significantly improved in the NOR and HYP groups (training, P < 0.001) in normoxic conditions. No further effect of hypoxic training was found on markers of endurance performance in hypoxia (training x hypoxia interaction, n.s.). In addition, training and hypoxia had no significant effect on lactate turnover rate. In contrast, there was a significant interaction of training and hypoxia (P < 0.05) on glucose metabolism, as follows: plasma insulin and glucose concentrations were significantly increased; glucose metabolic clearance rate was decreased; and the insulin to glucagon ratio was increased after training in the HYP group. In conclusion, our results show that, compared with training in normoxia, training in hypoxia has no further effect on endurance performance in both normoxic and hypoxic conditions or on lactate metabolic clearance rate. Additionally, these findings suggest that training in hypoxia impairs blood glucose regulation in endurance-trained subjects during exercise.

Specific fibroblastic niches in secondary lymphoid organs orchestrate distinct Notch-regulated immune responses.

Fibroblast-like cells of secondary lymphoid organs (SLO) are important for tissue architecture. In addition, they regulate lymphocyte compartmentalization through the secretion of chemokines, and participate in the orchestration of appropriate cell-cell interactions required for adaptive immunity. Here, we provide data demonstrating the functional importance of SLO fibroblasts during Notch-mediated lineage specification and immune response. Genetic ablation of the Notch ligand Delta-like (DL)1 identified splenic fibroblasts rather than hematopoietic or endothelial cells as niche cells, allowing Notch 2-driven differentiation of marginal zone B cells and of Esam(+) dendritic cells. Moreover, conditional inactivation of DL4 in lymph node fibroblasts resulted in impaired follicular helper T cell differentiation and, consequently, in reduced numbers of germinal center B cells and absence of high-affinity antibodies. Our data demonstrate previously unknown roles for DL ligand-expressing fibroblasts in SLO niches as drivers of multiple Notch-mediated immune differentiation processes.

Genetic evidence for a role of adiponutrin in the metabolism of apolipoprotein B-containing lipoproteins.

Adiponutrin (PNPLA3) is a predominantly liver-expressed transmembrane protein with phospholipase activity that is regulated by fasting and feeding. Recent genome-wide association studies identified PNPLA3 to be associated with hepatic fat content and liver function, thus pointing to a possible involvement in the hepatic lipoprotein metabolism. The aim of this study was to examine the association between two common variants in the adiponutrin gene and parameters of lipoprotein metabolism in 23,274 participants from eight independent West-Eurasian study populations including six population-based studies [Bruneck (n = 800), KORA S3/F3 (n = 1644), KORA S4/F4 (n = 1814), CoLaus (n = 5435), SHIP (n = 4012), Rotterdam (n = 5967)], the SAPHIR Study as a healthy working population (n = 1738) and the Utah Obesity Case-Control Study including a group of 1037 severely obese individuals (average BMI 46 kg/m2) and 827 controls from the same geographical region of Utah. We observed a strong additive association of a common non-synonymous variant within adiponutrin (rs738409) with age-, gender-, and alanine-aminotransferase-adjusted lipoprotein concentrations: each copy of the minor allele decreased levels of total cholesterol on average by 2.43 mg/dl (P = 8.87 x 10(-7)), non-HDL cholesterol levels by 2.35 mg/dl (P = 2.27 x 10(-6)) and LDL cholesterol levels by 1.48 mg/dl (P = 7.99 x 10(-4)). These associations remained significant after correction for multiple testing. We did not observe clear evidence for associations with HDL cholesterol or triglyceride concentrations. In conclusion, our study suggests that adiponutrin is involved in the metabolism of apoB-containing lipoproteins.

Gut microbiota metabolism of dietary fiber influences allergic airway disease and hematopoiesis.

Metabolites from intestinal microbiota are key determinants of host-microbe mutualism and, consequently, the health or disease of the intestinal tract. However, whether such host-microbe crosstalk influences inflammation in peripheral tissues, such as the lung, is poorly understood. We found that dietary fermentable fiber content changed the composition of the gut and lung microbiota, in particular by altering the ratio of Firmicutes to Bacteroidetes. The gut microbiota metabolized the fiber, consequently increasing the concentration of circulating short-chain fatty acids (SCFAs). Mice fed a high-fiber diet had increased circulating levels of SCFAs and were protected against allergic inflammation in the lung, whereas a low-fiber diet decreased levels of SCFAs and increased allergic airway disease. Treatment of mice with the SCFA propionate led to alterations in bone marrow hematopoiesis that were characterized by enhanced generation of macrophage and dendritic cell (DC) precursors and subsequent seeding of the lungs by DCs with high phagocytic capacity but an impaired ability to promote T helper type 2 (TH2) cell effector function. The effects of propionate on allergic inflammation were dependent on G protein-coupled receptor 41 (GPR41, also called free fatty acid receptor 3 or FFAR3), but not GPR43 (also called free fatty acid receptor 2 or FFAR2). Our results show that dietary fermentable fiber and SCFAs can shape the immunological environment in the lung and influence the severity of allergic inflammation.

Glutamatergic and GABAergic energy metabolism measured in the rat brain by (13) C NMR spectroscopy at 14.1 T.

Energy metabolism supports both inhibitory and excitatory neurotransmission processes. This study investigated the specific contribution of astrocytic metabolism to γ-aminobutyric acid (GABA) synthesis and inhibitory GABAergic neurotransmission that remained to be ilucidated in vivo. Therefore, we measured (13) C incorporation into brain metabolites by dynamic (13) C nuclear magnetic resonance spectroscopy at 14.1 T in rats under α-chloralose anaesthesia during infusion of [1,6-(13) C]glucose. The enhanced sensitivity at 14.1 T allowed to quantify incorporation of (13) C into the three aliphatic carbons of GABA non-invasively. Metabolic fluxes were determined with a mathematical model of brain metabolism comprising glial, glutamatergic and GABAergic compartments. GABA synthesis rate was 0.11 ± 0.01 μmol/g/min. GABA-glutamine cycle was 0.053 ± 0.003 μmol/g/min and accounted for 22 ± 1% of total neurotransmitter cycling between neurons and glia. Cerebral glucose oxidation was 0.47 ± 0.02 μmol/g/min, of which 35 ± 1% and 7 ± 1% was diverted to the glutamatergic and GABAergic tricarboxylic acid cycles, respectively. The remaining fraction of glucose oxidation was in glia, where 12 ± 1% of the TCA cycle flux was dedicated to oxidation of GABA. 16 ± 2% of glutamine synthesis was provided to GABAergic neurons. We conclude that substantial metabolic activity occurs in GABAergic neurons and that glial metabolism supports both glutamatergic and GABAergic neurons in the living rat brain. We performed (13) C NMR spectroscopy in vivo at high magnetic field (14.1 T) upon administration of [1,6-(13) C]glucose. This allowed to measure (13) C incorporation into the three aliphatic carbons of GABA in the rat brain, in addition to those of glutamate, glutamine and aspartate. These data were then modelled to determine fluxes of energy metabolism in GABAergic and glutamatergic neurons and glial cells.

Effects of infused amino acids and lipids on glucose metabolism in healthy lean humans.

The effects of infusion of a triglyceride emulsion (which induces peripheral insulin resistance) and amino acids (which stimulate gluconeogenesis) on glucose metabolism were investigated in healthy lean humans during exogenous infusion of glucose. One group of subjects (n = 5) was infused for 7.5 h with 11.1 mumol/kg/min glucose; during the last 4 h, amino acids were also infused at a rate of 3.33 mg/kg/min. A second group of subjects (n = 5) was infused with glucose+lipids (Lipovenös, 10% 10 ml/min) for 7.5 h and amino acids were added during the last 4 h. Infusion of lipids suppressed the increase in glucose oxidation observed during infusion of glucose alone (delta glucose oxidation: -2.1 +/- 1.1 vs. + 4.5 +/- 1.4 mumol/kg/min; P < 0.05) and during infusion of glucose+amino acids (delta glucose oxidation: + 1.6 +/- 1.4 vs. + 10.6 +/- 1.2 mumol/kg/min; P < 0.05). Gluconeogenesis (determined from 13C glucose synthesis during infusion of 13C bicarbonate) increased from 1.1 +/- 0.2 mumol/kg/min during infusion of glucose and 1.6 +/- 0.3 during infusion of glucose+lipids to 3.2 +/- 0.4 and 3.1 +/- 0.4, respectively, when amino acid infusion was superimposed (P < 0.05 in both instances). Plasma glucose concentrations were identical during infusion of glucose alone or glucose+amino acids, with or without lipids. Insulin concentrations were significantly increased by lipids both during infusion of glucose alone and of glucose+amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic modulation of CCR7 expression and function on naive T lymphocytes in vivo.

The chemokine receptor CCR7 is critical for the recirculation of naive T cells. It is required for T cell entry into secondary lymphoid organs (SLO) and for T cell motility and retention within these organs. How CCR7 activity is regulated during these processes in vivo is poorly understood. Here we show strong modulation of CCR7 surface expression and occupancy by the two CCR7 ligands, both in vitro and in vivo. In contrast to blood, T cells in SLO had most surface CCR7 occupied with CCL19, presumably leading to continuous signaling and cell motility. Both ligands triggered CCR7 internalization in vivo as shown in Ccl19(-/-) and plt/plt mice. Importantly, CCR7 occupancy and down-regulation led to strongly impaired chemotactic responses, an effect reversible by CCR7 resensitization. Therefore, during their recirculation, T cells cycle between states of free CCR7 with high ligand sensitivity in blood and occupied CCR7 associated with continual signaling and reduced ligand sensitivity within SLO. We propose that these two states of CCR7 are important to allow the various functions CCR7 plays in T cell recirculation.

A high-fructose diet impairs basal and stress-mediated lipid metabolism in healthy male subjects.

The effects of a 7 d high-fructose diet (HFrD) or control diet on lipid metabolism were studied in a group of six healthy lean males. Plasma NEFA and beta-hydroxybutyrate concentrations, net lipid oxidation (indirect calorimetry) and exogenous lipid oxidation (13CO2 production) were monitored in basal conditions, after lipid loading (olive oil labelled with [13C]triolein) and during a standardised mental stress. Lactate clearance and the metabolic effects of an exogenous lactate infusion were also monitored. The HFrD lowered plasma concentrations of NEFA and beta-hydroxybutyrate as well as lipid oxidation in both basal and after lipid-loading conditions. In addition, the HFrD blunted the increase in plasma NEFA and exogenous lipid oxidation during mental stress. The HFrD also increased basal lactate concentrations by 31.8 %, and lactate production by 53.8 %, while lactate clearance remained unchanged. Lactate infusion lowered plasma NEFA with the control diet, and net lipid oxidation with both the HFrD and control diet. These results indicate that a 7 d HFrD markedly inhibits lipolysis and lipid oxidation. The HFrD also increases lactate production, and the ensuing increased lactate utilisation may contribute to suppress lipid oxidation.

Fatty acids and retinoids control lipid metabolism through activation of peroxisome proliferator-activated receptor-retinoid X receptor heterodimers.

The nuclear hormone receptors called PPARs (peroxisome proliferator-activated receptors alpha, beta, and gamma) regulate the peroxisomal beta-oxidation of fatty acids by induction of the acyl-CoA oxidase gene that encodes the rate-limiting enzyme of the pathway. Gel retardation and cotransfection assays revealed that PPAR alpha heterodimerizes with retinoid X receptor beta (RXR beta; RXR is the receptor for 9-cis-retinoic acid) and that the two receptors cooperate for the activation of the acyl-CoA oxidase gene promoter. The strongest stimulation of this promoter was obtained when both receptors were exposed simultaneously to their cognate activators. Furthermore, we show that natural fatty acids, and especially polyunsaturated fatty acids, activate PPARs as potently as does the hypolipidemic drug Wy 14,643, the most effective activator known so far. Moreover, we discovered that the synthetic arachidonic acid analogue 5,8,11,14-eicosatetraynoic acid is 100 times more effective than Wy 14,643 in the activation of PPAR alpha. In conclusion, our data demonstrate a convergence of the PPAR and RXR signaling pathways in the regulation of the peroxisomal beta-oxidation of fatty acids by fatty acids and retinoids.

Secondary Cancer Risk for Stage I Seminoma Patients - a Comparison of Adjuvant Treatment Versus Surveillance

Background: Post-surgical management of stage I seminoma includes: surveillance with repeated CT-scans and treatment reserved for those who relapse, or adjuvant treatment with either immediate radiation therapy (RT) or carboplatin. The cancer specific survival is close to 100%. Cure without long-term sequelae of treatment is the aim. Our goal is to estimate the risk of radiation-induced secondary cancers (SC) death from for patients undergoing S, adjuvant RT or adjuvant carboplatin (AC).Materials and Methods: We measured organ doses from CT scans (3 phases each one) of a seminoma patient who was part of the active surveillance strategy and from a man undergoing adjuvant RT 20-Gy and a 30-Gy salvage RT treatment to the para-aortic area using helical Intensity Modulated RT (Tomotherapy®) with accurate delineation of organs at risk and a CTV to PTV expansion of 1 cm. Effective doses to organs in mSv were estimated according to the tissue-weighting factors recommendations of the International Commission on Radiological Protection 103 (Ann ICRP 2007). We estimated SC incidence and mortality for a 10,000 people population based on the excess absolute risk model from the Biological Effects of Ionizing Radiation (BEIR) VII (Health Risk of Exposure to Low Levels of Ionizing Radiation, NCR, The National Academies Press Washington, DC, 2006) assuming a seminoma diagnosis at age 30, a total life expectancy of 80 years.Results: The nominal risk for a fatal secondary cancers was calculated 1.5% for 15 abdominal CT scans, 14.8% for adjuvant RT (20 Gy paraaortic field) and 22.2% for salvage RT (30 Gy). The calculation assumed that the risk of relapse on surveillance and adjuvant AC was 15% and 4% respectively and that all patients were salvaged at relapse with RT. n CT abdomen/Pelvis = secondary cancer % RT Dose and % receiving treatment = secondary cancer % Total secondary cancer risk in % Active surveillance 15 = 1.5% 30 Gy in 15% of pts = 3.3% 4.8 Adjuvant carboplatin 7 = 0.7% 30 Gy in 4% of pts = 0.88% 1.58 Adjuvant radiotherapy 7 = 0.7% 20 Gy in 100% of pts = 14.8% 15.5Conclusions: These data suggest that: 1) Adjuvant radiotherapy is harmful and should not anymore be regarded as a standard option for seminoma stage I. 2) AC seems to be an option to reduce radiation induced cancers. Limitations: the study does not consider secondary cancers due to chemotherapy with AC (unknown). The use of BEIR VII for risk modeling with higher doses of RT needs to be validated.

Can Valproic Acid be an Inducer of Clozapine Metabolism?

Introduction: Prior clozapine studies indicated no effects, mild inhibition or induction of valproic acid (VPA) on clozapine metabolism. The hypotheses that (i) VPA is a net inducer of clozapine metabolism, and (ii) smoking modifies this inductive effect were tested in a therapeutic drug monitoring study. Methods: After excluding strong inhibitors and inducers, 353 steady-state total clozapine (clozapine plus norclozapine) concentrations provided by 151 patients were analyzed using a random intercept linear model. Results: VPA appeared to be an inducer of clozapine metabolism since total plasma clozapine concentrations in subjects taking VPA were significantly lower (27% lower; 95% confidence interval, 14-39%) after controlling for confounding variables including smoking (35% lower, 28-56%). Discussion: Prospective studies are needed to definitively establish that VPA may (i) be an inducer of clozapine metabolism when induction prevails over competitive inhibition, and (ii) be an inducer even in smokers who are under the influence of smoking inductive effects on clozapine metabolism.

Training in hypoxia fails to further enhance endurance performance and lactate clearance in well-trained men and impairs glucose metabolism during prolonged exercise.

The aim of this study was to investigate the synergistic effects of endurance training and hypoxia on endurance performance in normoxic and hypoxic conditions (approximately 3000 m above sea level) as well as on lactate and glucose metabolism during prolonged exercise. For this purpose, 14 well-trained cyclists performed 12 training sessions in conditions of normobaric hypoxia (HYP group, n = 7) or normoxia (NOR group, n = 7) over 4 weeks. Before and after training, lactate and glucose turnover rates were measured by infusion of exogenous lactate and stable isotope tracers. Endurance performance was assessed during incremental tests performed in normoxia and hypoxia and a 40 km time trial performed in normoxia. After training, performance was similarly and significantly improved in the NOR and HYP groups (training, P < 0.001) in normoxic conditions. No further effect of hypoxic training was found on markers of endurance performance in hypoxia (training x hypoxia interaction, n.s.). In addition, training and hypoxia had no significant effect on lactate turnover rate. In contrast, there was a significant interaction of training and hypoxia (P < 0.05) on glucose metabolism, as follows: plasma insulin and glucose concentrations were significantly increased; glucose metabolic clearance rate was decreased; and the insulin to glucagon ratio was increased after training in the HYP group. In conclusion, our results show that, compared with training in normoxia, training in hypoxia has no further effect on endurance performance in both normoxic and hypoxic conditions or on lactate metabolic clearance rate. Additionally, these findings suggest that training in hypoxia impairs blood glucose regulation in endurance-trained subjects during exercise.

Anthropogenic disturbance as a driver of microspatial and microhabitat segregation of cytotypes of Centaurea stoebe and cytotype interactions in secondary contact zones.

BACKGROUND AND AIMS: In a mixed-ploidy population, strong frequency-dependent mating will lead to the elimination of the less common cytotype, unless prezygotic barriers enhance assortative mating. However, such barriers favouring cytotype coexistence have only rarely been explored. Here, an assessment is made of the mechanisms involved in formation of mixed-ploidy populations and coexistence of diploid plants and their closely related allotetraploid derivates from the Centaurea stoebe complex (Asteraceae). METHODS: An investigation was made of microspatial and microhabitat distribution, life-history and fitness traits, flowering phenology, genetic relatedness of cytotypes and intercytotype gene flow (cpDNA and microsatellites) in six mixed-ploidy populations in Central Europe. KEY RESULTS: Diploids and tetraploids were genetically differentiated, thus corroborating the secondary origin of contact zones. The cytotypes were spatially segregated at all sites studied, with tetraploids colonizing preferentially drier and open microhabitats created by human-induced disturbances. Conversely, they were rare in more natural microsites and microsites with denser vegetation despite their superior persistence ability (polycarpic life cycle). The seed set of tetraploid plants was strongly influenced by their frequency in mixed-ploidy populations. Triploid hybrids originated from bidirectional hybridizations were extremely rare and almost completely sterile, indicating a strong postzygotic barrier between cytotypes. CONCLUSIONS: The findings suggest that tetraploids are later immigrants into already established diploid populations and that anthropogenic activities creating open niches favouring propagule introductions were the major factor shaping the non-random distribution and habitat segregation of cytotypes at fine spatial scale. Establishment and spread of tetraploids was further facilitated by their superior persistence through the perennial life cycle. The results highlight the importance of non-adaptive spatio-temporal processes in explaining microhabitat and microspatial segregation of cytotypes.