The social transition of risk factors for cardiovascular disease in the African region: evidence from three cross-sectional surveys in the Seychelles.

OBJECTIVES: To examine the association between socioeconomic status (SES) and several cardiovascular disease risk factors (CVRFs) and to assess whether this association has changed over a 15-year observation period. METHODS: Three independent population-based surveys of CVRFs were conducted in representative samples of all adults aged 25-64 years in the Seychelles, a small island state located east to Kenya, in 1989 (N=1081), 1994 (N=1067) and 2004 (N=1255). RESULTS: Among men, current smoking and heavy drinking were more prevalent in the low versus the high SES group, and obesity was less prevalent. The socioeconomic gradient in diabetes reversed over the study period from lower prevalence in the low versus the high SES group to higher prevalence in the low SES group. Hypercholesterolemia was less prevalent in the low versus the high SES group in 1989 but the prevalence was similar in the two groups in 2004. Hypertension showed no consistent socioeconomic pattern. Among women, the SES gradient in smoking tended to reverse over time from lower prevalence in the low SES group to lower prevalence in the high SES group. Obesity and diabetes were more common in the low versus the high SES group over the study period. Heavy drinking, hypertension and hypercholesterolemia were not socially patterned among women. CONCLUSION: The prevalence of several CVRFs was higher in low versus high SES groups in a rapidly developing country in the African region, and an increase of the burden of these CVRFs in the most disadvantaged groups of the population was observed over the 15 years study period.

Changes in the Sexual Dimorphism of Triatominae in the Transition from Natural to Artificial Habitats

A shift from large to small average sizes was observed in Triatoma infestans and Rhodnius domesticus between field and domestic (or laboratory) conditions of life. It was more pronounced in the female specimens, leading to a subsequent reduction of sexual size dimorphism. This feature is discussed in terms of genetic and populational changes occurring from natural to artificial habitats, in particular those related to population densities. Sexual size dimorphism is then recommended as a new character to be used in the study of species of Triatominae adapting to domestic ecotopes.

Spatio-temporal dynamics and transition from asymptotic equilibrium to bounded oscillations in Chrysomya albiceps (Diptera, Calliphoridae)

The sensitivity of parameters that govern the stability of population size in Chrysomya albiceps and describe its spatial dynamics was evaluated in this study. The dynamics was modeled using a density-dependent model of population growth. Our simulations show that variation in fecundity and mainly in survival has marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations. C. albiceps exhibits a two-point limit cycle, but the introduction of diffusive dispersal induces an evident qualitative shift from two-point limit cycle to a one fixed-point dynamics. Population dynamics of C. albiceps is here compared to dynamics of Cochliomyia macellaria, C. megacephala and C. putoria.

Environmental effects of Deccan volcanism across the Cretaceous-Tertiary transition in Meghalaya, India

The Urn Sohryngkew section of Meghalaya, NE India, located 800-1000 km from the Deccan volcanic province, is one of the most complete Cretaceous-Tertiary boundary (KTB) transitions worldwide with all defining and supporting criteria present: mass extinction of planktic foraminifera, first appearance of Danian species, delta(13)C shift, Ir anomaly (12 ppb) and KTB red layer. The geochemical signature of the KTB layer indicates not only an extraterrestrial signal (Ni and all Platinum Group Elements (PGEs)) of a second impact that postdates Chicxulub, but also a significant component resulting from condensed sedimentation (P), redox fluctuations (As, Co, Fe, Pb, Zn, and to a lesser extent Ni and Cu) and volcanism. From the late Maastrichtian C29r into the early Danian, a humid climate prevailed (kaolinite: 40-60%, detrital minerals: 50-80%). During the latest Maastrichtian, periodic acid rains (carbonate dissolution; CIA index: 70-80) associated with pulsed Deccan eruptions and strong continental weathering resulted in mesotrophic waters. The resulting super-stressed environmental conditions led to the demise of nearly all planktic foraminiferal species and blooms (>95%) of the disaster opportunist Guembelitria cretacea. These data reveal that detrimental marine conditions prevailed surrounding the Deccan volcanic province during the main phase of eruptions in C29r below the KTB. Ultimately these environmental conditions led to regionally early extinctions followed by global extinctions at the KTB. (C) 2011 Elsevier B.V. All rights reserved.

Differential expression of notch signaling-related transcripts accompanies Pro-thymocyte proliferation and phenotype transition induced by epidermal growth factor plus insulin in fetal thymus organ cultures

Thymus regression upon stressing stimuli, such as infectious diseases, is followed by organ reconstitution, paralleling its development in ontogeny. A narrow window of thymus development was here studied, encompassing the pro-T lymphoid precursor expansion during specification stages, by the use of epidermal growth factor plus insulin (INS) in murine fetal thymus organ cultures. Aiming to disclose signaling pathways related to these stages, cultured thymus lobes had their RNA extracted, for the search of transcripts differentially expressed using RNAse protection assays and reverse transcriptase-polymerase chain reactions. We found no difference that could explain INS-driven thymocyte growth, in the pattern of transcripts for death/proliferation mediators, or for a series of growth factor receptors and transcriptional regulators known as essential for thymus development. Thymocyte suspensions from cultured lobes, stained for phenotype analysis by fluorescence activated cell sorting, showed a decreased staining for Notch1 protein at cell surfaces upon INS addition. We analyzed the expression of Notch-related elements, and observed the recruitment of a specific set of transcripts simultaneous and compatible with INS-driven thymocyte growth, namely, transcripts for Notch3, for its ligand Jagged2, and for Deltex1, a mediator of a poorly characterized alternative pathway downstream of the Notch receptor.

Quantification of the genetic change in the transition of Rhodnius pallescens Barber, 1932 (Hemiptera: Reduviidae) from field to laboratory

Previous studies have reported genetic differences between wild-caught sylvatic, domestic and laboratory pop-ulations of several Triatominae species. The differences between sylvatic and laboratory colonies parallel are similar to the differences observed between sylvatic and domestic populations. Laboratory colonies are frequently used as references for field populations, but the consequences of founder events on the genetic makeup of laboratory or domestic populations are rarely quantified. Our goal was to quantify the genetic change in Rhodnius pallescens populations artificially submitted to founder effects via laboratory colonization. We compared the genetic makeup of two sylvatic populations and their laboratory descendants using a panel of 10 microsatellite markers. Both sylvatic populations were initially collected from palm trees, but the colonies differed in the number of founder insects and amount of time kept in the laboratory. We evaluated allelic polymorphism, differences between expected and observed heterozygosity, estimates of population differentiation (Fst) and inbreeding (Fis, Fit) and cluster analyses based on Nei's distances. We found a unique genetic structure for each sample population, with significant differentiation between the field insects and each of the laboratory generations. These analyses showed strong founder effects and showed that genetic drift had led to a genetic equilibrium over several generations of isolation. Our results suggest that laboratory colonies of R. pallescens have a different genetic structure than their wild relatives and similar processes likely affect other Triatominae laboratory stocks.

Reliability and validity of physiological data obtained within a cycle-run transition test in age-group triathletes.

This study examined the validity and reliability of a sequential "Run-Bike-Run" test (RBR) in age-group triathletes. Eight Olympic distance (OD) specialists (age 30.0 ± 2.0 years, mass 75.6 ± 1.6 kg, run VO2max 63.8 ± 1.9 ml· kg(-1)· min(-1), cycle VO2peak 56.7 ± 5.1 ml· kg(-1)· min(-1)) performed four trials over 10 days. Trial 1 (TRVO2max) was an incremental treadmill running test. Trials 2 and 3 (RBR1 and RBR2) involved: 1) a 7-min run at 15 km· h(-1) (R1) plus a 1-min transition to 2) cycling to fatigue (2 W· kg(-1) body mass then 30 W each 3 min); 3) 10-min cycling at 3 W· kg(-1) (Bsubmax); another 1-min transition and 4) a second 7-min run at 15 km· h(-1) (R2). Trial 4 (TT) was a 30-min cycle - 20-min run time trial. No significant differences in absolute oxygen uptake (VO2), heart rate (HR), or blood lactate concentration ([BLA]) were evidenced between RBR1 and RBR2. For all measured physiological variables, the limits of agreement were similar, and the mean differences were physiologically unimportant, between trials. Low levels of test-retest error (i.e. ICC <0.8, CV<10%) were observed for most (logged) measurements. However [BLA] post R1 (ICC 0.87, CV 25.1%), [BLA] post Bsubmax (ICC 0.99, CV 16.31) and [BLA] post R2 (ICC 0.51, CV 22.9%) were least reliable. These error ranges may help coaches detect real changes in training status over time. Moreover, RBR test variables can be used to predict discipline specific and overall TT performance. Cycle VO2peak, cycle peak power output, and the change between R1 and R2 (deltaR1R2) in [BLA] were most highly related to overall TT distance (r = 0.89, p < 0. 01; r = 0.94, p < 0.02; r = 0.86, p < 0.05, respectively). The percentage of TR VO2max at 15 km· h(-1), and deltaR1R2 HR, were also related to run TT distance (r = -0.83 and 0.86, both p < 0.05).

GLUT3 is induced during epithelial-mesenchymal transition and promotes tumor cell proliferation in non-small cell lung cancer.

BACKGROUND: Alterations in glucose metabolism and epithelial-mesenchymal transition (EMT) constitute two important characteristics of carcinoma progression toward invasive cancer. Despite an extensive characterization of each of them separately, the links between EMT and glucose metabolism of tumor cells remain elusive. Here we show that the neuronal glucose transporter GLUT3 contributes to glucose uptake and proliferation of lung tumor cells that have undergone an EMT. RESULTS: Using a panel of human non-small cell lung cancer (NSCLC) cell lines, we demonstrate that GLUT3 is strongly expressed in mesenchymal, but not epithelial cells, a finding corroborated in hepatoma cells. Furthermore, we identify that ZEB1 binds to the GLUT3 gene to activate transcription. Importantly, inhibiting GLUT3 expression reduces glucose import and the proliferation of mesenchymal lung tumor cells, whereas ectopic expression in epithelial cells sustains proliferation in low glucose. Using a large microarray data collection of human NSCLCs, we determine that GLUT3 expression correlates with EMT markers and is prognostic of poor overall survival. CONCLUSIONS: Altogether, our results reveal that GLUT3 is a transcriptional target of ZEB1 and that this glucose transporter plays an important role in lung cancer, when tumor cells loose their epithelial characteristics to become more invasive. Moreover, these findings emphasize the development of GLUT3 inhibitory drugs as a targeted therapy for the treatment of patients with poorly differentiated tumors.

zyg-11and cul-2 promote the metaphase to anaphase transition and M phase exit of meiosis II and prevent polarity establishment in C.elegans

Résumé Les mécanismes qui coordonnent la progression du cycle cellulaire lors de la méiose avec les événements du développement embryonnaire précoce, y compris la formation des axes de polarité embryonnaire, sont peu compris. Dans le zygote du vers Caenorhabditis elegans, les premiers signes de polarité Antéro-Postérieur (A-P) embryonnaire apparaissent après que la méiose soit terminée. La nature des protéines et des mécanismes moléculaires qui cassent la symétrie du zygote n'est pas connue. Nous démontrons que zyg-11 et cul-2 promeuvent la transition métaphase - anaphase et la sortie de la phase M lors de la seconde division méiotique. Nos résultats indiquent que ZYG-11 agit comme unité recrutant le substrat d'une ligase E3 comprennant CUL-2. Nos résultats montrent aussi que le délai de sortie de la phase M dépend de l'accumulation de la Cyclin B, CYB-3. Nous démontrons que dans des embryons zyg-11(RNAi) ou cul-2(RNAi), une polarité inversée est établie lors du délai de méiosis II. Enfin nous montrons que les défauts de cycle cellulaire et ceux de polarité peuvent être séparés. De plus, nous faisons apparaitre que l'établissement d'une polarité inversée pendant le délai de méiose II des embryons zyg-11(RNAi), comme l'établissement de la A-P polarité des embryons sauvage ne semblent pas requérir les microtubules. Nous montrons également les premiers résultats d'un crible deux hybrides ainsi qu'un crible génomique qui vise à identifier des gènes dont l'inactivation augmente ou supprime les défauts de mutants pour le gène zyg-11, afin d'identifier les gènes qui intéragissent avec ZYG-11 pour assumer ses deux fonctions séparables. Par conséquent, nos trouvailles suggèrent un modèle selon lequel ZYG-11 est une sous-unité qui recrute les substrats d'une ligase E3 basée sur CUL-2 qui promeut la progression du cycle cellulaire et empêche l'établissement de la polarité pendant la méiose II, et où le centrosome agit comme la clé qui polarise l'embryon à la fin de la méiose. Summary The mechanisms that couple meiotic cell cycle progression to subsequent developmental events, including specification of embryonic axes, are poorly understood. In the one cell stage embryos of Caenorhabditis elegans, the first signs of Antero-Posterior (A-P) polarity appear after meiosis completion. A centrosome ¬derived component breaks symmetry of the embryo, but the molecular nature of this polarity signal is not known. We established that zyg-11 and cul-2 promote the metaphase to anaphase transition and M phase exit at meiosis II. Our results indicate that ZYG-11 acts as a substrate recruitment subunit of a CUL-2-based E3 ligase. Moreover, we find that the delayed meiosis II exit of embryos lacking zyg-11 is caused by accumulation of the B-type cyclin, CYB-3. We demonstrate that inverted A-P polarity is established during the meiosis II delay in zyg-11(RNAi) and cul¬2(RNAi) embryos. Importantly, we demonstrate that the polarity defects following zyg-11 or cul-2 inactivation can be uncoupled from the cell cycle defects. Furthermore, we found that microtubules appear dispensable for inverted polarity during the meiosis II delay in zyg-11(RNAi) embryos, as well as for A-P polarity during the first mitotic cell cycle in wild-type embryos. We also show the initial results from a comprehensive yeast two hybrid, as well as an RNAi-based functional genomic enhancer and suppressor screen, that may lead to identification of proteins that interact with zyg-11 to ensure the two functions. Our findings suggest a model in which ZYG-11 is a substrate recruitment subunit of an CUL-2-based E3 ligase that promotes cell cycle progression and prevents polarity establishment during meiosis II, and in which the centrosome acts as a cue to polarize the embryo along the AP axis after exit from the meiotic cell cycle.

Devenir parent : divergences et convergences interindividuelles dans une transition de vie

RésuméLa naissance du premier enfant est un événement normatif à l'origine de nombreux changements dans le parcours de vie des hommes et des femmes. La présente recherche s'intéresse à la transition à la parentalité en tant que moment à l'origine d'un processus de stratification sociale. Trois dimensions dépendantes sont étudiées du point de vue de leur changement: l'insertion professionnelle, le travail domestique et la qualité de la relation conjugale. Les concepts de divergence et de convergence interindividuelle, élaborés à partir de l'hypothèse des dés/avantages cumulatifs et de l'hypothèse alternative des effets compensatoires, sont utilisés pour opérationnaliser le changement qui se produit dans ces trois dimensions lors de la naissance du premier enfant.Les résultats montrent, dans un premier moment, la présence de divergences entre les hommes et les femmes dans chacune de ces trois dimensions. Ces divergences inter-sexe sont associées à des convergences entre les individus de même sexe. Les analyses se focalisent dans un deuxième moment, sur les divergences et convergences ultérieures qui se produisent entre individus du même sexe en fonction des ressources sociales, culturelles et économiques initiales. Quelles sont ainsi, par exemple, les mères qui ne diminuent pas leur taux d'occupation initial? Quels sont les pères qui réduisent moins que les autres leur investissement dans le travail domestique? Quels sont les parents qui connaissent une moindre diminution de la qualité de leur relation conjugale? Les réponses données à ces questions montrent comment le processus de stratification sociale au sein d'une cohorte doit être expliqué en relation avec le changement qui se produit lors d'une transition spécifique et non seulement en tant que résultat du simple passage du temps.AbstractThe birth of the first child is a normative event creating important changes in the life course of men and women. This research analyzes the transition to parenthood as a moment creating social stratification. Three dependent dimensions are studied in their change: the occupational career, the domestic labour and the conjugal relationship's quality. The concepts of interindividual divergences and convergence, conceived from the cumulative dis/advantage hypothesis and the alternative hypothesis of compensatory effects, are used to operationalize the change in these three dimensions after the birth of the first child.Results show that, firstly, divergences take place between men and women becoming parents in the three dependent dimensions. Inter-sex divergences are associated to convergence between same-sex individuals. Secondly, the analyses focus on further di/convergences taking place between same-sex individuals, in relation with the initial social, cultural and economical resources. Who are the mothers who will not reduce their initial occupational rates? Who are the fathers who will reduce less than the others their involvement in the domestic tasks? Who are the parents who will experience a less important reduction in their conjugal relationship's quality? The answers to these questions show how the process of social stratification within a cohort has to be explained in relation with the change taking place during a specific transition and not only as a result of the simple passage of time.

Positive feedback in the transition from sexual reproduction to parthenogenesis.

Understanding how new phenotypes evolve is challenging because intermediate stages in transitions from ancestral to derived phenotypes often remain elusive. Here we describe and evaluate a new mechanism facilitating the transition from sexual reproduction to parthenogenesis. In many sexually reproducing species, a small proportion of unfertilized eggs can hatch spontaneously ('tychoparthenogenesis') and develop into females. Using an analytical model, we show that if females are mate-limited, tychoparthenogenesis can result in the loss of males through a positive feedback mechanism whereby tychoparthenogenesis generates female-biased sex ratios and increasing mate limitation. As a result, the strength of selection for tychoparthenogenesis increases in concert with the proportion of tychoparthenogenetic offspring in the sexual population. We then tested the hypothesis that mate limitation selects for tychoparthenogenesis and generates female-biased sex ratios, using data from natural populations of sexually reproducing Timema stick insects. Across 41 populations, both the tychoparthenogenesis rates and the proportions of females increased exponentially as the density of individuals decreased, consistent with the idea that low densities of individuals result in mate limitation and selection for reproductive insurance through tychoparthenogenesis. Our model and data from Timema populations provide evidence for a simple mechanism through which parthenogenesis can evolve rapidly in a sexual population.

Protocol for the modeling the epidemiologic transition study: a longitudinal observational study of energy balance and change in body weight, diabetes and cardiovascular disease risk.

ABSTRACT: BACKGROUND: The prevalence of obesity has increased in societies of all socio-cultural backgrounds. To date, guidelines set forward to prevent obesity have universally emphasized optimal levels of physical activity. However there are few empirical data to support the assertion that low levels of energy expenditure in activity is a causal factor in the current obesity epidemic are very limited. METHODS: The Modeling the Epidemiologic Transition Study (METS) is a cohort study designed to assess the association between physical activity levels and relative weight, weight gain and diabetes and cardiovascular disease risk in five population-based samples at different stages of economic development. Twenty-five hundred young adults, ages 25-45, were enrolled in the study; 500 from sites in Ghana, South Africa, Seychelles, Jamaica and the United States. At baseline, physical activity levels were assessed using accelerometry and a questionnaire in all participants and by doubly labeled water in a subsample of 75 per site. We assessed dietary intake using two separate 24-h recalls, body composition using bioelectrical impedance analysis, and health history, social and economic indicators by questionnaire. Blood pressure was measured and blood samples collected for measurement of lipids, glucose, insulin and adipokines. Full examination including physical activity using accelerometry, anthropometric data and fasting glucose will take place at 12 and 24 months. The distribution of the main variables and the associations between physical activity, independent of energy intake, glucose metabolism and anthropometric measures will be assessed using cross-section and longitudinal analysis within and between sites. DISCUSSION: METS will provide insight on the relative contribution of physical activity and diet to excess weight, age-related weight gain and incident glucose impairment in five populations' samples of young adults at different stages of economic development. These data should be useful for the development of empirically-based public health policy aimed at the prevention of obesity and associated chronic diseases.

Reaction-diffusion waves of advance in the transition to agricultural economics

In a previous paper [J.Fort and V.Méndez, Phys. Rev. Lett. 82, 867 (1999)], the possible importance of higher-order terms in a human population wave of advance has been studied. However, only a few such terms were considered. Here we develop a theory including all higher-order terms. Results are in good agreement with the experimental evidence involving the expansion of agriculture in Europe