1,974 research outputs found
Weekly variability of clupeoid eggs and larvae in the Benguela jet current: implications for recruitment
Weekly sampling of ichthyoplankton, current vectors and surface temperature along a 34-mile transect crossing the jet current off the Cape Peninsula was conducted from August 1995 to July 1996 as part of thethird phase of the South African Sardine and Anchovy Recruitment Programme, designed to investigate within-season variability in factors affecting sardine Sardinops sagax and anchovy Engraulis capensisrecruitment. Anchovy eggs and larvae were found from October 1995 to February 1996, with most intense spawning from mid-October to early December. Peak abundances of anchovy eggs (717.mâ2) and larvae(342.mâ2) were encountered during mid-November. Sardine eggs and larvae were found throughout the year, but were most abundant from August 1995 to February 1996. Numbers ere greatest during late September, reaching 630 eggs.mâ2 and 142 larvae.mâ2, with secondary peaks of >200 eggs.mâ2 during August, October and January. Spawning products were low from March onwards, but increased slightly during July 1996. Current vectors indicated that spawning prior to December was most favourable for transport of eggs and larvae to the West Coast nursery area. January and February were characterized by increasingly complexflow patterns, while the frontal jet current was positioned offshore of the transect for most of March and April as a result of prolonged periods of upwelling. Monthly length-frequency distributions of larvae indicatedspawning by both species farther east on the western Agulhas Bank later in the season, or more complex transport from that region to the sampling area. Mean monthly (AugustâMarch) anchovy and sardine (September â February) egg abundances were significantly correlated (p < 0.05) with the estimated birthdate distribution of recruits, suggesting that frequent monitoring of egg abundance along the transect may be usefulfor forecasting recruitment strength
Dynapenic obesity and the risk of incident Type 2 diabetes: the English Longitudinal Study of Ageing
Aim Obesity is a wellâestablished risk factor for developing Type 2 diabetes. Evidence suggests that sarcopenia, the ageârelated decline in muscle mass and strength, may exacerbate diabetes risk in obese individuals. The aim of this study was to determine the combined effect of obesity and low muscle strength, dynapenia, on the risk of incident Type 2 diabetes in older adults. Methods Participants were 5953 (1670 obese) men and women from the English Longitudinal Study of Ageing without known Type 2 diabetes at baseline and for whom handgrip strength, biochemical and other clinical data were collected. A diagnosis of Type 2 diabetes was recorded from selfâreported physician diagnosis over 6 years. Results For each unit increase in grip strength, there was a reduction in diabetes risk (ageâ, sexâ and BMI adjusted HR; 0.98; 95% CI 0.96â0.99). The risk of Type 2 diabetes was elevated in all obese participants, but was greatest in those with low handgrip strength (HR = 4.93, 95% CI 2.85, 8.53) compared with nonâobese individuals with high handgrip strength. Eleven per cent of the sample met the threshold for weakness (handgrip strength: men < 26 kg; women < 16 kg) that was associated with elevated Type 2 diabetes risk in obese (HR = 3.57, 95% CI 2.04, 6.24) but not in nonâobese (HR = 0.86, 95% CI, 0.44, 1.68) compared with normal/nonâobese participants. Conclusion Dynapenic obesity, determined by high BMI and low handgrip strength, is associated with increased risk of incident Type 2 diabetes in older people
The radiation of cynodonts and the ground plan of mammalian morphological diversity
Cynodont therapsids diversified extensively after the Permo-Triassic mass extinction event, and gave rise to mammals in the Jurassic. We use an enlarged and revised dataset of discrete skeletal characters to build a new phylogeny for all main cynodont clades from the Late Permian to the Early Jurassic, and we analyse models of morphological diversification in the group. Basal taxa and epicynodonts are paraphyletic relative to eucynodonts, and the latter are divided into cynognathians and probainognathians, with tritylodonts and mammals forming sister groups. Disparity analyses reveal a heterogeneous distribution of cynodonts in a morphospace derived from cladistic characters. Pairwise morphological distances are weakly correlated with phylogenetic distances. Comparisons of disparity by groups and through time are non-significant, especially after the data are rarefied. A disparity peak occurs in the Early/Middle Triassic, after which period the mean disparity fluctuates little. Cynognathians were characterized by high evolutionary rates and high diversity early in their history, whereas probainognathian rates were low. Community structure may have been instrumental in imposing different rates on the two clades
Physical Activity and Sedentary Time: Association with Metabolic Health and Liver Fat.
INTRODUCTION/PURPOSE: To investigate whether a) lower levels of daily physical activity (PA) and greater sedentary time accounted for contrasting metabolic phenotypes (higher liver fat/presence of metabolic syndrome [MetS+] vs lower liver fat/absence of metabolic syndrome [MetS-]) in individuals of similar BMI and b) the association of sedentary time on metabolic health and liver fat. METHODS: Ninety-eight habitually active participants (53 female, 45 male; age 39±13 years; BMI 26.9±5.1 kg/m), underwent assessments of PA (SenseWear armband; wear time ~98%), cardio-respiratory fitness (V[Combining Dot Above]O2 peak), body composition (MRI and MRS) and multi-organ insulin sensitivity (OGTT). We undertook a) cross-sectional analysis comparing four groups: non-obese or obese, with and without metabolic syndrome (MetS+ vs MetS-) and b) univariate and multivariate regression for sedentary time and other levels of PA in relation to liver fat. RESULTS: Light, moderate and vigorous PA did not account for differences in metabolic health between individuals, whether non-obese or obese, although MetS+ individuals were more sedentary, with a higher number, and prolonged bouts (~1-2 hours). Overall, sedentary time, average daily METS and V[Combining Dot Above]O2 peak were each independently associated with liver fat percentage. Each additional hour of daily sedentary time was associated with a 1.15% (95% CI, 1.14-1.50%) higher liver fat content. CONCLUSIONS: Greater sedentary time, independent of other levels of PA, is associated with being metabolically unhealthy; even in habitually active people, lesser sedentary time, and higher cardio-respiratory fitness and average daily METS is associated with lower liver fat.This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Female preference for blue in Japan blue guppies (Poecilia reticulata)
Guppies (Poecilia reticulata) are widely used as a model species in mate choice studies. Although native to South America, guppies have been introduced to natural water bodies in disparate regions of the globe. Here, for the first time, we examine guppies from one such introduced population in Japan where males have evolved a predominantly blue color pattern. Previous studies of wild-type guppies have shown blue to play a relatively minor role in the mate choice decisions of females compared to other traits, such as orange, and the importance of blue is not universally supported by all studies. The Japanese population therefore presents an ideal opportunity to re-examine the potential significance of blue as a mate choice cue in guppies. Mate choice experiments, in which female Japan blue guppies were given a choice between pairs of males that differed in their area of blue coloration but were matched for other traits, revealed that females prefer males with proportionately larger amounts of blue in their color patterns. We discuss possible factors, including sexual and ecological selection, which may have led to the evolution of unusually large areas of blue at the expense of other colors in Japan blue guppies. However, further studies are needed to distinguish between these scenarios.Web of Scienc
Compensatory changes in energy balance during dapagliflozin treatment in type 2 diabetes mellitus: a randomised double-blind, placebo-controlled, cross-over trial (ENERGIZE)-study protocol.
INTRODUCTION: Sodium glucose cotransporter 2 (SGLT2) inhibitors are effective blood-glucose-lowering medications with beneficial effects on body weight in patients with type 2 diabetes mellitus (T2DM). However, observed weight loss is less than that predicted from quantified glycosuria, suggesting a compensatory increase in energy intake or a decrease in energy expenditure. Studies using dual-energy X-ray absorptiometry (DEXA) have suggested most body weight change is due to loss of adipose tissue, but organ-specific changes in fat content (eg, liver, skeletal muscle) have not been determined. In this randomised, double-blind, placebo-controlled crossover study, we aim to study the compensatory changes in energy intake, eating behaviour and energy expenditure accompanying use of the SGLT2 inhibitor, dapagliflozin. Additionally, we aim to quantify changes in fat distribution using MRI, in liver fat using proton magnetic resonance spectroscopy ((1)H-MRS) and in central nervous system (CNS) responses to food images using blood oxygen level dependent (BOLD) functional MRI (fMRI). METHODS AND ANALYSIS: This outpatient study will evaluate the effect of dapagliflozin (10â
mg), compared with placebo, on food intake and energy expenditure at 7â
days and 12â
weeks. 52 patients with T2DM will be randomised to dapagliflozin or placebo for short-term and long-term trial interventions in a within participants, crossover design. The primary outcome is the difference in energy intake during a test meal between dapagliflozin and placebo. Intake data are collected automatically using a customised programme operating a universal eating monitor (UEM). Secondary outcomes include (1) measures of appetite regulation including rate of eating, satiety quotient, appetite ratings (between and within meals), changes in CNS responses to food images measured using BOLD-fMRI, (2) measures of energy expenditure and (3) changes in body composition including changes in liver fat and abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). ETHICAL APPROVAL: This study has been approved by the North West Liverpool Central Research Ethics Committee (14/NW/0340) and is conducted in accordance with the Declaration of Helsinki and the Good Clinical Practice (GCP). TRIAL REGISTRATION NUMBER: ISRCTN14818531. EUDRACT number 2013-004264-60
International standards for fetal brain structures based on serial ultrasound measurements from the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project.
OBJECTIVE: To create prescriptive growth standards for five fetal brain structures, measured by ultrasound, from healthy, well-nourished women, at low risk of impaired fetal growth and poor perinatal outcomes, taking part in the Fetal Growth Longitudinal Study (FGLS) of the INTERGROWTH-21st Project. METHODS: This was a complementary analysis of a large, population-based, multicentre, longitudinal study. We measured, in planes reconstructed from 3-dimensional (3D) ultrasound volumes of the fetal head at different time points in pregnancy, the size of the parieto-occipital fissure (POF), Sylvian fissure (SF), anterior horn of the lateral ventricle (AV), atrium of the posterior ventricle (PV) and cisterna magna (CM). The sample analysed was randomly selected from the overall FGLS population, ensuring an equal distribution amongst the eight diverse participating sites and of 3D ultrasound volumes across pregnancy (range: 15 - 36âweeks' gestation). Fractional polynomials were used to the construct standards. Growth and development of the infants were assessed at 1 and 2âyears of age to confirm their adequacy for constructing international standards. RESULTS: From the entire FGLS cohort of 4321 women, 451 (10.4%) were randomly selected. After exclusions, 3D ultrasound volumes from 442 fetuses born without congenital malformations were used to create the charts. The fetal brain structures of interest were identified in 90% of cases. All structures showed increasing size with gestation and increasing variability for the POF, SF, PV and CM. The 3rd , 5th , 50th , 95th and 97th smoothed centile are presented. The 5th centile of POF and SF were 2.8 and 4.3 at 22âweeks and 4.2 and 9.4mm at 32âweeks respectively. The 95th centile of PV and CM were 8.5 and 7.4 at 22âweeks and 8.5 and 9.4mm at 32âweeks respectively. CONCLUSIONS: We have produced prescriptive size standards for fetal brain structures based on prospectively enrolled pregnancies at low risk of abnormal outcomes. We recommend these as international standards for the assessment of measurements obtained by ultrasound from fetal brain structures
Raising argument strength using negative evidence: A constraint on models of induction
Both intuitively, and according to similarity-based theories of induction, relevant evidence raises argument strength when it is positive and lowers it when it is negative. In three experiments, we tested the hypothesis that argument strength can actually increase when negative evidence is introduced. Two kinds of argument were compared through forced choice or sequential evaluation: single positive arguments (e.g., âShostakovichâs music causes alpha waves in the brain; therefore, Bachâs music causes alpha waves in the brainâ) and double mixed arguments (e.g., âShostakovichâs music causes alpha waves in the brain, Xâs music DOES NOT; therefore, Bachâs music causes alpha waves in the brainâ). Negative evidence in the second premise lowered credence when it applied to an item X from the same subcategory (e.g., Haydn) and raised it when it applied to a different subcategory (e.g., AC/DC). The results constitute a new constraint on models of induction
Prediction of Muscle Energy States at Low Metabolic Rates Requires Feedback Control of Mitochondrial Respiratory Chain Activity by Inorganic Phosphate
The regulation of the 100-fold dynamic range of mitochondrial ATP synthesis flux in skeletal muscle was investigated. Hypotheses of key control mechanisms were included in a biophysical model of oxidative phosphorylation and tested against metabolite dynamics recorded by 31P nuclear magnetic resonance spectroscopy (31P MRS). Simulations of the initial model featuring only ADP and Pi feedback control of flux failed in reproducing the experimentally sampled relation between myoplasmic free energy of ATP hydrolysis (ÎGpâ=âÎGpoâČ+RT ln ([ADP][Pi]/[ATP]) and the rate of mitochondrial ATP synthesis at low fluxes (<0.2 mM/s). Model analyses including Monte Carlo simulation approaches and metabolic control analysis (MCA) showed that this problem could not be amended by model re-parameterization, but instead required reformulation of ADP and Pi feedback control or introduction of additional control mechanisms (feed forward activation), specifically at respiratory Complex III. Both hypotheses were implemented and tested against time course data of phosphocreatine (PCr), Pi and ATP dynamics during post-exercise recovery and validation data obtained by 31P MRS of sedentary subjects and track athletes. The results rejected the hypothesis of regulation by feed forward activation. Instead, it was concluded that feedback control of respiratory chain complexes by inorganic phosphate is essential to explain the regulation of mitochondrial ATP synthesis flux in skeletal muscle throughout its full dynamic range
Short-Term Physical Inactivity Induces Endothelial Dysfunction
Objective: This study examined the effects of a short-term reduction in physical activity, and subsequent resumption, on metabolic profiles, body composition and cardiovascular (endothelial) function.
Design: Twenty-eight habitually active (â„10,000 steps/day) participants (18 female, 10 male; age 32 ± 11 years; BMI 24.3 ± 2.5 kg/m2) were assessed at baseline, following 14 days of step-reduction and 14 days after resuming habitual activity.
Methods: Physical activity was monitored throughout (SenseWear Armband). Endothelial function (flow mediated dilation; FMD), cardiorespiratory fitness (V.O2 peak) and body composition including liver fat (dual-energy x-ray absorptiometry and magnetic resonance spectroscopy) were determined at each assessment. Statistical analysis was performed using one-way within subjectâs ANOVA; data presented as mean (95% CI).
Results: Participants decreased their step count from baseline by 10,111 steps/day (8949, 11,274; P < 0.001), increasing sedentary time by 103 min/day (29, 177; P < 0.001). Following 14 days of step-reduction, endothelial function was reduced by a 1.8% (0.4, 3.3; P = 0.01) decrease in FMD. Following resumption of habitual activity, FMD increased by 1.4%, comparable to the baseline level 0.4% (â1.8, 2.6; P = 1.00). Total body fat, waist circumference, liver fat, whole body insulin sensitivity and cardiorespiratory fitness were all adversely affected by 14 days step-reduction (P < 0.05) but returned to baseline levels following resumption of activity.
Conclusion: This data shows for the first time that whilst a decline in endothelial function is observed following short-term physical inactivity, this is reversed on resumption of habitual activity. The findings highlight the need for public health interventions that focus on minimizing time spent in sedentary behavior
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