891 research outputs found
Increased left atrial size in obese children and its association with insulin resistance: a pilot study
No full textSubclinical cardiac abnormalities represent predisposing factors for cardiovascular disease (CVD) in obese subjects. The aim of this study was to evaluate early cardiac abnormalities in obese youth and the potential association with insulin resistance (IR). Thirty obese (12 males (M)/18 females (F); age = 11.5 ± 2.4 years; body mass index (BMI)-standard deviation score (SDS) = +2.1 ± 0.5) and 15 normal weight (10 M/5 F; age = 12.8 ± 3.1 years; BMI-SDS = +0.3 ± 0.9) children and adolescents underwent Doppler two-dimensional echocardiographic assessments of left atrial (LA) and ventricular (LV) geometry and LV diastolic function (peak early [E] and late waves, E wave deceleration time, myocardial flow velocities). Homeostasis model assessment of IR (HOMA-IR) was used as an IR index. LA size was increased in obese children, as indicated by higher LA diameter (4.9 ± 0.5 vs 4.1 ± 0.4 cm, p < 0.001), area (14.3 ± 2.5 vs 10.7 ± 2.0 cm(2), p < 0.001), and volume (33.8 ± 10.6 vs 23.7 ± 6.4 ml, p = 0.003). LV mass was also increased in obese children (87.0 ± 16.6 vs 68.8 ± 13.2 g, p = 0.003), who also showed subtle diastolic dysfunctions, as indicated by higher values of E (97.1 ± 14.3 vs 86.2 ± 11.9 cm/s, p = 0.02). All the above parameters were significantly associated with BMI-SDS (p < 0.05). In addition, HOMA-IR was independently associated with LA diameter, area, and volume (β = 0.314, p = 0.040; β = 0.415, p = 0.008; β = 0.535, p = 0.001).
Obese children feature increased LA size, which emerged to be mainly correlated to, and possibly driven by IR, suggesting an increased CVD risk
Joint analysis of macrofaunal and meiofaunal assemblages improves the assessment of lagoonal environmental heterogeneity
No full textMatching datasets of macrofaunal and meiofaunal assemblages were jointly analyzed for the first time in a
coastal lagoon (Cabras Lagoon, Sardinia) in relation to the lagoonal environmental heterogeneity. Within the
common faunal list, indicator species/taxa for different environmental conditions were found evenly for both
assemblages, with the two faunal components responding distinctly to the putative environmental gradients
according to their autecology. The relationship between the number of individuals and species/taxa richness of
both assemblages showed an exponential increase at increasing salinity and DO concentrations in water as expected
basing on the confinement theory. Along the trophic gradient, the two metrics of both macrofaunal and
meiofaunal assemblages showed a similar belt-shaped curve in agreement with theoretical predictions and
quantitative field studies, with a peak at intermediate OM values followed by a sharp decrease at OM above 12%
at the most confined site. While not a causality measure, our results indicate that these simple benthic-OM relationships
applied to both faunal components represent a valuable screening-level indicator for evaluating the
likelihood of reduced sediment quality and associated bioeffects in eutrophic lagoons. The present study demonstrates
that macrofaunal and meiofaunal assemblages in coastal lagoons, as commonly shown in marine waters,
are coherent and distinct entities and that their joint use represents a more comprehensive and robust tool to
assess the environmental heterogeneity and quality of these highly variable systems
Meiofaunal Dynamics and Heterogeneity along Salinity and Trophic Gradients in a Mediterranean Transitional System
No full textThe spatiotemporal variation in meiofaunal assemblages were investigated for the first
time in the Cabras Lagoon, the largest transitional system in the Sardinian Island (W-Mediterranean
Sea). Two main environmental (salinity and trophic) gradients highlighted a significant separation
of the three study sites across the lagoon, which were consistent through time. The environmental
variability and habitat heterogeneity of the Cabras Lagoon influenced the meiofauna. In particular,
salinity and dissolved oxygen, primarily, shaped the meiofaunal assemblage structure at the seaward
site which was significantly dierent from both the riverine and the organically enriched sites. On the
other hand, the trophic components (e.g., organic matter, Chlorophyll-a, and phaeopigments) and the
dierent degrees of confinement and saprobity among sites were the secondary factors contributing
mostly to the separation between the latter two sites. The lack of significant dierences in the
temporal comparison of the meiofaunal assemblage structure along with the very low contribution
of temperature to the meiofaunal ordination indicated that this assemblage was more aected by
spatial rather than by temporal variation. This pattern was also supported by significant dierences
between the three sites in several univariate measures, including total number of individuals,
number of taxa, Pielou’s evenness, and the ratio between nematodes and copepods. Thus, the present
study corroborates the hypothesis that meiofaunal organisms are good indicators of the spatial
heterogeneity in transitional waters (TWs) and could have a greater species richness than that
expected. Indeed, the Cabras Lagoon overall showed one of the highest meiofaunal richness values
found from both Mediterranean and European TWs
Long-term changes in the structure of a polychaete community on artificial habitats
No full textA mediterranean polychaete community was studied for 10 years since the first settlement to examine community dynamics and to compare it with the model proposed by Hughes (1984) for benthic invertebrates. Cluster analysis (Q-mode) pointed out the presence of four main periods during the colonization process in agreement with edaphic changes produced by the colonization and disappearance of mussels. During this time the pattern of species abundance changed from a log series distribution (with few dominant species) towards a truncated log normal distribution (with many rare species) characteristic of a more complex community structure
Paradigm shifts in community ecology: Open versus closed units, challenges and limits of connectivity studies
No full textDue to the presence of the complex life cycles involving a benthic adult and a pelagic larval phase, the study of benthic community dynamics cannot ignore investigations of the processes occurring in the water column. Current investigations focus mainly on larval dispersal from an evolutionary and a biogeographic perspective, taking into account also population connectivity, conservation planning and coastal management. In the present paper we underline the need to improve knowledge of the main traits of marine invertebrate life cycles, highlighting the limits and challenges of current approaches. Firstly, we summarized the changing approaches within community studies, following the paradigm shifts found in recent marine ecological research, from supply-side ecology to connectivity, and involving the concepts of open and closed populations. Secondly, we analysed the main larval traits influencing dispersal, paying particular attention to pelagic larval duration in light of the few available data for connectivity studies. The difficulty in estimating many of the main traits of larval ecology make numerical simulation fundamental for a better understanding of the relationship between propagule dispersal and seawater dynamics, both being highly variable. We conclude that some essential biological information is still lacking for the proper integration of the modeling approaches. Thus it is necessary to further investigate the life-cycle traits and physiological and ecological characteristics of each species, an approach known as autecology or natural history. All too frequently modern ecologists ignore such reductionist approaches, although they are essential for a full understanding of processes, such as connectivity and metapopulation dynamics
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