Sleep, metabolism and aging

Aging is a multidimensional process of physical, psychological, and social changes. Understanding how we sleep and how this dynamic process evolves across life span will help to identify normal developmental aspects of sleep over time and to create strategies to increase awareness of sleep disturbances and their early management. In normal sleepers from HypnoLaus cohort, we evaluated the effects of age and gender on both subjective and objective sleep measurements. Our results indicate that normal aging is not accompanied by sleep complaints, and when they exist suggest the presence of underlying comorbidities. Polysomnographic data revealed that slow wave sleep was more affected with age in men, and age affected differently NREM and REM spectral power densities. Both sleep structure and spectral analysis profiles may constitute standards to delineate pathological changes in sleep, both for aging women and men. Another important aspect in the management of sleep and its disorders is a detailed characterization of sleep-inducing medications. Gamma-hydroxybutyrate (GHB) is an inhibitory neurotransmitter derivative of GABA, but its mode of action and the range of effects are not well understood. Several properties, as growth hormone stimulation in humans and the development of weight loss in treated patients suggest an unexplored metabolic effect. In different experiments we assessed the effects of acute, short term and chronic GHB administration on central (cerebral cortex) and peripheral (liver) biochemical processes involved in the metabolism of the drug, as well as the effects of the drug on metabolism in C57BL/6J, GABAB knock-out and obese (ob/ob) mice. We showed that GHB treatment affects weight gain in C57BL/6J and GABAB knock-out mice. Metabolomic analysis indicated large central and peripheral metabolic changes induced by GHB with important relevance to its therapeutic use. -- Le vieillissement est un processus multidimensionnel accompagné par de multiples changements dans les domaines physique, psychologique et social. Comprendre comment nous dormons et comment ce processus dynamique évolue sur la durée de vie nous aidera à identifier les aspects normaux du développement du sommeil au fil du temps, et à créer des stratégies pour accroître la connaissance et compréhension des troubles du sommeil et leur prise en charge précoce. Chez les sujets normaux de la cohorte HypnoLaus nous avons évalué les effets de l'âge et du sexe sur les mesures subjectives et objectives du sommeil. Nos résultats indiquent que le vieillissement normal ne s'accompagne pas de troubles du sommeil, et quand ils existent ceux-ci suggèrent la présence de comorbidités sous-jacentes. Les données polysomnographiques ont révélé que le sommeil profond était plus affecté avec l'âge chez les hommes. De plus, nous avons montré comment l'âge modifie la composition spectrale du sommeil lent et paradoxal. La structure du sommeil et les profils d'analyse spectrale peuvent donc constituer des standards permettant de définir les changements pathologiques du sommeil chez les personnes âgées. Parmi les aspects importants de la gestion du sommeil et de ses troubles, la caractérisation détaillée des médicaments hypnotiques utilisés est essentielle. L'acide gamma-hydroxybutyrique (GHB) est un acide gras à courte chaîne dérivé du GABA, principal neurotransmetteur inhibiteur du cerveau, mais son mode d'action et tous ses effets sont toujours largement méconnus. Plusieurs propriétés, comme la stimulation de la sécrétion de l'hormone de croissance chez l'homme et le développement d'une perte de poids chez les patients traités suggèrent un effet métabolique inexploré. Dans différentes expériences, nous avons évalué les effets d'une exposition aiguë, à court terme et chronique de GHB sur les processus biochimiques centraux (cortex cérébral) et périphériques (foie) impliqués dans le métabolisme du médicament. Nous avons aussi évalué les effets du médicament sur le métabolisme des souris C57BL/6J, GABAB KO et obèses (ob/ob). Nos résultats ont montré que le GHB diminue le gain de poids chez les souris C57BL/6J et GABAB KO. L'analyse métabolomique a indiqué des changements importants induits par GHB au niveau central et périphérique, et ces effets sont importants pour son utilisation thérapeutique.

Peroxisome proliferator-activated receptors and lipid metabolism.

PPARs are nuclear hormone receptors which, like the retinoid, thyroid hormone, vitamin D, and steroid hormone receptors, are ligand-activated transcription factors mediating the hormonal control of gene expression. Two lines of evidence indicate that PPARs have an important function in fatty acid metabolism. First, PPARs are activated by hypolipidemic drugs and physiological concentrations of fatty acids, and second, PPARs control the peroxisomal beta-oxidation pathway of fatty acids through transcriptional induction of the gene encoding the acyl-CoA oxidase (ACO), which is the rate-limiting enzyme of the pathway. Furthermore, the PPAR signaling pathway appears to converge with the 9-cis retinoic acid receptor (RXR) signaling pathway in the regulation of the ACO gene because heterodimerization between PPAR and RXR is essential for in vitro binding to the PPRE and because the strongest stimulation of this gene is observed when both receptors are exposed simultaneously to their activators. Thus, it appears that PPARs are involved in the 9-cis retinoic acid signaling pathway and that they play a pivotal role in the hormonal control of lipid metabolism.

Generation of the primary hair follicle pattern.

Hair follicles are spaced apart from one another at regular intervals through the skin. Although follicles are predominantly epidermal structures, classical tissue recombination experiments indicated that the underlying dermis defines their location during development. Although many molecules involved in hair follicle formation have been identified, the molecular interactions that determine the emergent property of pattern formation have remained elusive. We have used embryonic skin cultures to dissect signaling responses and patterning outcomes as the skin spatially organizes itself. We find that ectodysplasin receptor (Edar)-bone morphogenetic protein (BMP) signaling and transcriptional interactions are central to generation of the primary hair follicle pattern, with restriction of responsiveness, rather than localization of an inducing ligand, being the key driver in this process. The crux of this patterning mechanism is rapid Edar-positive feedback in the epidermis coupled with induction of dermal BMP4/7. The BMPs in turn repress epidermal Edar and hence follicle fate. Edar activation also induces connective tissue growth factor, an inhibitor of BMP signaling, allowing BMP action only at a distance from their site of synthesis. Consistent with this model, transgenic hyperactivation of Edar signaling leads to widespread overproduction of hair follicles. This Edar-BMP activation-inhibition mechanism appears to operate alongside a labile prepattern, suggesting that Edar-mediated stabilization of beta-catenin active foci is a key event in determining definitive follicle locations.

Three small RNAs jointly ensure secondary metabolism and biocontrol in Pseudomonas fluorescens CHA0.

In many Gram-negative bacteria, the GacS/GacA two-component system positively controls the expression of extracellular products or storage compounds. In the plant-beneficial rhizosphere bacterium Pseudomonas fluorescens CHA0, the GacS/GacA system is essential for the production of antibiotic compounds and hence for biological control of root-pathogenic fungi. The small (119-nt) RNA RsmX discovered in this study, together with RsmY and RsmZ, forms a triad of GacA-dependent small RNAs, which sequester the RNA-binding proteins RsmA and RsmE and thereby antagonize translational repression exerted by these proteins in strain CHA0. This small RNA triad was found to be both necessary and sufficient for posttranscriptional derepression of biocontrol factors and for protection of cucumber from Pythium ultimum. The same three small RNAs also positively regulated swarming motility and the synthesis of a quorum-sensing signal, which is unrelated to N-acyl-homoserine lactones, and which autoinduces the Gac/Rsm cascade. Expression of RsmX and RsmY increased in parallel throughout cell growth, whereas RsmZ was produced during the late growth phase. This differential expression is assumed to facilitate fine tuning of GacS/A-controlled cell population density-dependent regulation in P. fluorescens.

Retention half times in the skeleton of plutonium and 90Sr from above-ground nuclear tests: a retrospective study of the Swiss population.

Plutonium and (90)Sr are considered to be among the most radiotoxic nuclides produced by the nuclear fission process. In spite of numerous studies on mammals and humans there is still no general agreement on the retention half time of both radionuclides in the skeleton in the general population. Here we determined plutonium and (90)Sr in human vertebrae in individuals deceased between 1960 and 2004 in Switzerland. Plutonium was measured by sensitive SF-ICP-MS techniques and (90)Sr by radiometric methods. We compared our results to the ones obtained for other environmental compartments to reveal the retention half time of NBT fallout (239)Pu and (90)Sr in trabecular bones of the Swiss population. Results show that plutonium has a retention half time of 40+/-14 years. In contrast (90)Sr has a shorter retention half time of 13.5+/-1.0 years. Moreover (90)Sr retention half time in vertebrae is shown to be linked to the retention half time in food and other environmental compartments. These findings demonstrate that the renewal of the vertebrae through calcium homeostatic control is faster for (90)Sr excretion than for plutonium excretion. The precise determination of the retention half time of plutonium in the skeleton will improve the biokinetic model of plutonium metabolism in humans.

(Young Investigator Award) Trabecular Bone Score Helps Classifying Women At Risk Of Fracture Prospectively In The Ofely Study

Introduction: To determine the metabolic effect of teriparatide (TPTD) on bone, 99mTc-MDP skeletal plasma clearance was measured in postmenopausal women with osteoporosis treated with TPTD 20 μg/day. Methods: Ten postmenopausal women with osteoporosis had radionuclide bone scans at baseline, 3, and 18 months after starting TPTD 20 μg/day and after 6 months off therapy. Participants were injected with 600 MBq 99mTc- MDP and whole body bone scans acquired at 10 min, 1, 2, 3, and 4 h. Multiple blood samples were taken between 5 min and 4 h and free 99mTc-MDP measured using ultrafiltration. 99mTc-MDP plasma clearance (Kbone) was evaluated using the Patlak plot method. Regional differences in Kbone were studied by measuring the whole skeleton and subregions. Serum procollagen type I Nterminal propeptide (PINP), bone-specific alkaline phosphatase (BSAP), and urinary N-terminal telopeptide (NTX) were measured at each visit.Discussion: The median increase from baseline in whole skeleton Kbone was 22% (P=0.004) at 3 months and 34% (P= 0.002) at 18 months, decreasing to 0.7% after 6 months off therapy. In subregions, Kbone value increases were statistically significant at 3 months and in all subregions except the pelvis at 18 months. After 6 months off therapy, subregional Kbone values also returned toward baseline. Bone markers increases from baseline were statistically significant at 3 and 18 months (BSAP, 15% and 36%; PINP, 137% and 192%; NTX, 109% and 125%). After 6 months off therapy, PINP and NTX values had declined, though remained above baseline (BSAP, −3%; PINP, 43%; NTX, 56%). Increased Kbone values in the whole body and lower extremities were correlated with increases in most bone markers at 3 and 18 months. Increased skeletal uptake of 99mTc-MDP during treatment with TPTD is indicative of increased bone formation and is supported by increases in bone turnover markers.Conclusion: Changes in Kbone and skeletal uptake measured by radionuclide bone scans in patients taking TPTD are the result of metabolic activity of the drug. These data may provide physicians with useful insights when interpreting bone scan results in this population.

Molecular characterization of HLA-C incompatibilities in HLA-ABDR-matched unrelated bone marrow donor-recipient pairs. Sequence of two new Cw alleles (Cw*02023 and Cw*0707) and recognition by cytotoxic T lymphocytes.

While the influence of HLA-AB and -DRB1 matching on the outcome of bone marrow transplantation (BMT) with unrelated donors is clear, the evaluation of HLA-C has been hampered by its poor serological definition. Because the low resolution of standard HLA-C typing could explain the significant number of positive cytotoxic T lymphocyte precursor frequency (CTLpf) tests found among HLA-AB-subtype, DRB1/B3/B5-subtype matched patient/donor pairs, we have identified by sequencing the incompatibilities recognized by CD8+ CTL clones obtained from such positive CTLpf tests. In most cases the target molecules were HLA-C antigens that had escaped detection by serology (e.g. Cw*1601, 1502 or 0702). Direct recognition of HLA-C by a CTL clone was demonstrated by lysis of the HLA class I-negative 721.221 cell line transfected with Cw*1601 cDNA. Because of the functional importance of Cw polymorphism, a PCR-SSO oligotyping procedure was set up allowing the resolution of 29 Cw alleles. Oligotyping of a panel of 382 individuals (including 101 patients and their 272 potential unrelated donors, 5 related donors and 4 platelet donors) allowed to determine HLA-C and HLA A-B-Cw-DRB1 allelic frequencies, as well as a number of A-Cw, B-Cw, and DRB1-Cw associations. Two new HLA-Cw alleles (Cw*02023 and Cw*0707) were identified by DNA sequencing of PCR-amplified exon 2-intron 2-exon 3 amplicons. Furthermore, we determined the degree of HLA-C compatibility in 287 matched pairs that could be formed from 73 patients and their 184 potential unrelated donors compatible for HLA-AB by serology and for HLA-DRB1/ B3/B5 by oligotyping. Cw mismatches were identified in 42.1% of these pairs, and AB-subtype oligotyping showed that 30% of these Cw-incompatible pairs were also mismatched for A or B-locus subtype. The degree of HLA-C incompatibility was strongly influenced by the linkage with B alleles and by the ABDR haplotypes. Cw alleles linked with B*4403, B*5101, B18, and B62 haplotypes were frequently mismatched. Apparently high resolution DNA typing for HLA-AB does not result in full matching at locus C. Since HLA-C polymorphism is recognized by alloreactive CTLs, such incompatibilities might be as relevant as AB-subtype mismatches in clinical transplantation.

Can the trabecular bone score (TBS) be considered as a major clinical risk factor (CRF) of osteoporotic fractures? A meta-like analysis

Abstract: To have an added value over BMD, a CRF of osteoporotic fracture must be predictable of the fracture, independent of BMD, reversible and quantifiable. Many major recognized CRF exist.Out of these factorsmany of themare indirect factor of bone quality. TBS predicts fracture independently of BMD as demonstrated from previous studies. The aim of the study is to verify if TBS can be considered as a major CRF of osteoporotic fracture. Existing validated datasets of Caucasian women were analyzed. These datasets stem from different studies performed by the authors of this report or provided to our group. However, the level of evidence of these studies will vary. Thus, the different datasets were weighted differently according to their design. This meta-like analysis involves more than 32000 women (≥50 years) with 2000 osteoporotic fractures from two prospective studies (OFELY&MANITOBA) and 7 crosssectional studies. Weighted relative risk (RR) for TBS was expressed for each decrease of one standard deviation as well as per tertile difference (TBS=1.300 and 1.200) and compared with those obtained for the major CRF included in FRAX®. Overall TBS RR obtained (adjusted for age) was 1.79 [95%CI-1.37-2.37]. For all women combined, RR for fracture for the lowest comparedwith themiddle TBS tertilewas 1.55[1.46- 1.68] and for the lowest compared with the highest TBS tertile was 2.8[2.70-3.00]. TBS is comparable to most of the major CRF (Fig 1) and thus could be used as one of them. Further studies have to be conducted to confirm these first findings.

The predictive value of trabecular bone score (TBS) on whole lumbar vertebrae mechanics: an ex vivo study.

We investigated the association of trabecular bone score (TBS) with microarchitecture and mechanical behavior of human lumbar vertebrae. We found that TBS reflects vertebral trabecular microarchitecture and is an independent predictor of vertebral mechanics. However, the addition of TBS to areal BMD (aBMD) did not significantly improve prediction of vertebral strength. INTRODUCTION: The trabecular bone score (TBS) is a gray-level measure of texture using a modified experimental variogram which can be extracted from dual-energy X-ray absorptiometry (DXA) images. The current study aimed to confirm whether TBS is associated with trabecular microarchitecture and mechanics of human lumbar vertebrae, and if its combination with BMD improves prediction of fracture risk. METHODS: Lumbar vertebrae (L3) were harvested fresh from 16 donors. The anteroposterior and lateral bone mineral content (BMC) and areal BMD (aBMD) of the vertebral body were measured using DXA; then, the TBS was extracted using TBS iNsight software (Medimaps SA, France). The trabecular bone volume (Tb.BV/tissue volume, TV), trabecular thickness (Tb.Th), degree of anisotropy, and structure model index (SMI) were measured using microcomputed tomography. Quasi-static uniaxial compressive testing was performed on L3 vertebral bodies to assess failure load and stiffness. RESULTS: The TBS was significantly correlated to Tb.BV/TV and SMI (râeuro0/00=âeuro0/000.58 and -0.62; pâeuro0/00=âeuro0/000.02, 0.01), but not related to BMC and BMD. TBS was significantly correlated with stiffness (râeuro0/00=âeuro0/000.64; pâeuro0/00=âeuro0/000.007), independently of bone mass. Using stepwise multiple regression models, we failed to demonstrate that the combination of BMD and TBS was better at explaining mechanical behavior than either variable alone. However, the combination TBS, Tb.Th, and BMC did perform better than each parameter alone, explaining 79 % of the variability in stiffness. CONCLUSIONS: In our study, TBS was associated with microarchitecture parameters and with vertebral mechanical behavior, but TBS did not improve prediction of vertebral biomechanical properties in addition to aBMD.

In-vitro testing of biofilm formation on infected bone grafts and bone substitutes

Background: Bacteria form biofilms on the surface of orthopaedic devices, causing persistent infections. Monitoring biofilm formation on bone grafts and bone substitutes is challenging due to heterogeneous surface characteristics. We analyzed various bone grafts and bone substitutes regarding their propensity for in-vitro biofilm formation caused by S. aureus and S. epidermidis. Methods: Beta-tricalciumphosphate (b-TCP, ChronOsTM), processed human spongiosa (TutoplastTM) and PMMA (PalacosTM) were investigated. PE was added as a growth control. As test strains S. aureus (ATCC 29213) and S. epidermidis RP62A (ATCC 35984) were used. Test materials were incubated with 105 cfu/ml. After 24 h, test materials were removed and washed, followed by a standardised sonication protocol. The resulting sonication fluid was plated and bacterial counts were enumerated and expressed as cfu/sample. Sonicated samples were transferred to a microcalorimeter (TA Instrument) and heat flow monitored over a 24 h period with a precision of 0.0001°C and a sensitiviy of 200 μW. Experiments were performed in triplicates to calculate the mean ± SD. One-way ANOVA analysis was used for statistical analysis. Results: Bacterial counts (log10 cfu/sample) were highest on b-TCP (S. aureus 7.67 ± 0.17; S. epidermidis 8.14 ± 0.05) while bacterial density (log10 cfu/surface) was highest on PMMA (S. aureus 6.12 ± 0.2, S. epidermidis 7.65 ± 0.13). Detection time for S. aureus biofilms was shorter for the porous materials (b-TCP and Tutoplast, p <0.001) compared to the smooth materials (PMMA and PE) with no differences between b-TCP and TutoplastTM (p >0.05) or PMMA and PE (p >0.05). In contrast, for S. epidermidis biofilms the detection time was different (p <0.001) between all materials except between Tutoplast and PE (p >0.05). Conclusion: Our results demonstrate biofilm formation with both strains on all tested materials. Microcalorimetry was able to detect quantitatively the amount of biofilm. Further studies are needed to see whether calorimetry is a suitable tool also to monitor approaches to prevent and treat infections associated with bone grafts and bone substitutes.

Low malathion concentrations influence metabolism in Chironomus sancticaroli (Diptera, Chironomidae) in acute and chronic toxicity tests

Low malathion concentrations influence metabolism in Chironomus sancticaroli (Diptera, Chironomidae) in acute and chronic toxicity tests. Organophosphate compounds are used in agro-systems, and in programs to control pathogen vectors. Because they are continuously applied, organophosphates often reach water sources and may have an impact on aquatic life. The effects of acute and chronic exposure to the organophosphate insecticide malathion on the midge Chironomus sancticaroli are evaluated. To that end, three biochemical biomarkers, acetylcholinesterase (AChE), alpha (EST-α) and beta (EST-β) esterase were used. Acute bioassays with five concentrations of malathion, and chronic bioassays with two concentrations of malathion were carried out. In the acute exposure test, AChE, EST-α and EST-β activities declined by 66, 40 and 37%, respectively, at 0.251 µg L-1 and more than 80% at 1.37, 1.96 and 2.51 µg L-1. In chronic exposure tests, AChE and EST-α activities declined by 28 and 15% at 0.251 µg L-1. Results of the present study show that low concentrations of malathion can influence larval metabolism, indicating high toxicity for Chironomus sancticaroli and environmental risk associated with the use of organophosphates.

LRF-mediated Dll4 repression in erythroblasts is necessary for hematopoietic stem cell maintenance.

Hematopoietic stem cells (HSCs) are the most primitive cells in the hematopoietic system and are under tight regulation for self-renewal and differentiation. Notch signals are essential for the emergence of definitive hematopoiesis in mouse embryos and are critical regulators of lymphoid lineage fate determination. However, it remains unclear how Notch regulates the balance between HSC self-renewal and differentiation in the adult bone marrow (BM). Here we report a novel mechanism that prevents HSCs from undergoing premature lymphoid differentiation in BM. Using a series of in vivo mouse models and functional HSC assays, we show that leukemia/lymphoma related factor (LRF) is necessary for HSC maintenance by functioning as an erythroid-specific repressor of Delta-like 4 (Dll4) expression. Lrf deletion in erythroblasts promoted up-regulation of Dll4 in erythroblasts, sensitizing HSCs to T-cell instructive signals in the BM. Our study reveals novel cross-talk between HSCs and erythroblasts, and sheds a new light on the regulatory mechanisms regulating the balance between HSC self-renewal and differentiation.

The Energy metabolism of China and India between 1971-2010: studying the bifurcation

This paper presents a comparison of the changes in the energetic metabolic pattern of China and India, the two most populated countries in the world, with two economies undergoing an important economic transition. The comparison of the changes in the energetic metabolic pattern has the scope to characterize and explain a bifurcation in their evolutionary path in the recent years, using the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) approach. The analysis shows an impressive transformation of China’s energy metabolism determined by the joining of the WTO in 2001. Since then, China became the largest factory of the world with a generalized capitalization of all sectors ―especially the industrial sector― boosting economic labor productivity as well as total energy consumption. India, on the contrary, lags behind when considering these factors. Looking at changes in the household sector (energy metabolism associated with final consumption) in the case of China, the energetic metabolic rate (EMR) soared in the last decade, also thanks to a reduced growth of population, whereas in India it remained stagnant for the last 40 years. This analysis indicates a big challenge for India for the next decade. In the light of the data analyzed both countries will continue to require strong injections of technical capital requiring a continuous increase in their total energy consumption. When considering the size of these economies it is easy to guess that this may induce a dramatic increase in the price of energy, an event that at the moment will penalize much more the chance of a quick economic development of India.