The impact of nonalcoholic fatty liver disease on renal function in children with overweight/obesity

The association between nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease has attracted interest and attention over recent years. However, no data are available in children. We determined whether children with NAFLD show signs of renal functional alterations, as determined by estimated glomerular filtration rate (eGFR) and urinary albumin excretion. We studied 596 children with overweight/obesity, 268 with NAFLD (hepatic fat fraction >= 5% on magnetic resonance imaging) and 328 without NAFLD, and 130 healthy normal-weight controls. Decreased GFR was defined as eGFR < 90 mL/min/1.73 m(2). Abnormal albuminuria was defined as urinary excretion of >= 30 mg/24 h of albumin. A greater prevalence of eGFR < 90 mL/min/1.73 m2 was observed in patients with NAFLD compared to those without liver involvement and healthy subjects (17.5% vs. 6.7% vs. 0.77%; p < 0.0001). The proportion of children with abnormal albuminuria was also higher in the NAFLD group compared to those without NAFLD, and controls (9.3% vs. 4.0% vs. 0; p < 0.0001). Multivariate logistic regression analysis revealed that NAFLD was associated with decreased eGFR and/or microalbuminuria (odds ratio, 2.54 (confidence interval, 1.16-5.57); p < 0.05) independently of anthropometric and clinical variables. Children with NAFLD are at risk for early renal dysfunction. Recognition of this abnormality in the young may help to prevent the ongoing development of the disease

An improved methodology for the recovery of Zea mays and other large crop pollen, with implications for environmental archaeology in the Neotropics

We present a simple sieving methodology to aid the recovery of large cultigen pollen grains, such as maize (Zea mays L.), manioc (Manihot esculenta Crantz), and sweet potato (Ipomoea batatas L.), among others, for the detection of food production using fossil pollen analysis of lake sediments in the tropical Americas. The new methodology was tested on three large study lakes located next to known and/or excavated pre-Columbian archaeological sites in South and Central America. Five paired samples, one treated by sieving, the other prepared using standard methodology, were compared for each of the three sites. Using the new methodology, chemically digested sediment samples were passed through a 53 µm sieve, and the residue was retained, mounted in silicone oil, and counted for large cultigen pollen grains. The filtrate was mounted and analysed for pollen according to standard palynological procedures. Zea mays (L.) was recovered from the sediments of all three study lakes using the sieving technique, where no cultigen pollen had been previously recorded using the standard methodology. Confidence intervals demonstrate there is no significant difference in pollen assemblages between the sieved versus unsieved samples. Equal numbers of exotic Lycopodium spores added to both the filtrate and residue of the sieved samples allow for direct comparison of cultigen pollen abundance with the standard terrestrial pollen count. Our technique enables the isolation and rapid scanning for maize and other cultigen pollen in lake sediments, which, in conjunction with charcoal and pollen records, is key to determining land-use patterns and the environmental impact of pre-Columbian societies

A 2000-year history of forest disturbance in southern Pacific Costa Rica: pollen, spore, and charcoal evidence from Laguna Santa Elena

Paleoecological records reveal information about past changes in vegetation composition and disturbance in tropical ecosystems. These environmental histories have direct bearing on modem ecological studies and the management of protected areas, and provide information about the interaction between prehistoric peoples and their environment. In this study, I reconstruct prehistoric and historic forest disturbance and vegetation change from southern Pacific Costa Rica, in the vicinity of the Las Cruces Biological Station and the La Amistad International Park and Biosphere Reserve. Pollen and charcoal in sediments from Laguna Santa Elena reveal a nearly continuous record of human alteration of these tropical forests over the past two millennia. The basal portion of the core shows nearly intact premontane forests approximately 1800 cal. yr. BP, although there is evidence of human presence on the landscape in the form of maize pollen and charcoal. Clearing for agriculture resulted in the dominance of disturbance taxa in the watershed beginning at least 1400 cal. yr. BP. The pollen record reveals only one possible, brief hiatus from human occupation of the watershed, although secondary succession began to occur in the Laguna Santa Elena watershed prior to that time, starting about 700 cal. yr. BP. Three eruptions of nearby Volcan Bani at approximately 580, 1080, and 1440 cal. yr. BP apparently had little effect on the prehistoric populations in the immediate vicinity of the lake. Historic and modem land clearance has perpetuated a vegetation assemblage of disturbance and successional taxa. The pollen and charcoal records from Laguna Santa Elena demonstrate that this region of Costa Rica has a long history of forest clearance, which has implications for science and conservation in nearby ecological reserves and research stations, as well as for ongoing archaeological investigations in the region

On the taxonomic resolution of pollen and spore records of Earth’s vegetation

Premise of research. Pollen and spores (sporomorphs) are a valuable record of plant life and have provided information on subjects ranging from the nature and timing of evolutionary events to the relationship between vegetation and climate. However, sporomorphs can be morphologically similar at the species, genus, or family level. Studies of extinct plant groups in pre-Quaternary time often include dispersed sporomorph taxa whose parent plant is known only to the class level. Consequently, sporomorph records of vegetation suffer from limited taxonomic resolution and typically record information about plant life at a taxonomic rank above species.Methodology. In this article, we review the causes of low taxonomic resolution, highlight examples where this has hampered the study of vegetation, and discuss the strategies researchers have developed to overcome the low taxonomic resolution of the sporomorph record. Based on this review, we offer our views on how greater taxonomic precision might be attained in future work. Pivotal results. Low taxonomic resolution results from a combination of several factors, including inadequate reference collections, the absence of sporomorphs in situ in fossilized reproductive structures, and damage following fossilization. A primary cause is the difficulty of accurately describing the very small morphological differences between species using descriptive terminology, which results in palynologists classifying sporomorphs conservatively at the genus or family level to ensure that classifications are reproducible between samples and between researchers. Conclusions. In our view, the most promising approach to the problem of low taxonomic resolution is a combination of high-resolution imaging and computational image analysis. In particular, we encourage palynologists to explore the utility of microscopy techniques that aim to recover morphological information from below the diffraction limit of light and to employ computational image analyses to consistently quantify small morphological differences between species

Spatial Variation in Organic Carbon and Stable Isotope Composition of Lake Sediments at Laguna Zoncho, Costa Rica

Lake sediments are valuable paleoenvironmental archives that provide information on past climate and land-use change. Most lake sediment studies rely on a single core, usually recovered from the center of a lake, and do not consider spatial variability in the lake basin. My dissertation presents a spatially-explicit record of prehistoric agriculture from Laguna Zoncho, Costa Rica and evaluates spatial variability in lake sediment proxies based on a network of five sediment cores. Results extend earlier proxy analyses of a single core collected near the center of the lake, which documented prehistoric agriculture and forest clearance from 3000 to about 500 years ago, followed by strong forest recovery at the time of the Spanish Conquest. Analyses of the new suite of cores show that agricultural activities increased erosion in the watershed, which lowered organic content from 16% to 5%, and resulted in a shift in bulk sediment stable carbon isotope values from –27 ‰ to –23 ‰ VPDB due to forest clearance. Agriculture made the lake slightly more productive, shown by a decrease in carbon/nitrogen ratios from 16 to 13 and an increase in stable nitrogen ratios from 1 to 3 ‰. Basinwide trends in organic matter and stable carbon isotopes ratios show two distinct periods of agricultural decline (1150–960 and 840–650 cal yr BP) that coincide with intervals of drought detected in regional paleoclimate records. This finding suggests that climate change, not the Spanish Conquest, was the driving force of site abandonment at Laguna Zoncho, and by extension throughout the region. Inter-core variability in proxies for agricultural activity reveals that crop cultivation may have continued longer in some portions of the watershed, and highlights the influence of sediment-focusing processes on proxy signatures of agriculture in lake basins. Maize pollen concentrations in the sediment cores did not correspond to geochemical and isotopic agricultural indicators, suggesting a need for caution in using the abundance of maize pollen to infer the scale of agriculture in neotropical watersheds

Brazilian montane rainforest expansion induced by Heinrich Stadial 1 event

The origin of modern disjunct plant distributions in the Brazilian Highlands with strong floristic affinities to distant montane rainforests of isolated mountaintops in the northeast and northern Amazonia and the Guyana Shield remains unknown. We tested the hypothesis that these unexplained biogeographical patterns reflect former ecosystem rearrangements sustained by widespread plant migrations possibly due to climatic patterns that are very dissimilar from present-day conditions. To address this issue, we mapped the presence of the montane arboreal taxa Araucaria, Podocarpus, Drimys, Hedyosmum, Ilex, Myrsine, Symplocos, and Weinmannia, and cool-adapted plants in the families Myrtaceae, Ericaceae, and Arecaceae (palms) in 29 palynological records during Heinrich Stadial 1 Event, encompassing a latitudinal range of 30°S to 0°S. In addition, Principal Component Analysis and Species Distribution Modelling were used to represent past and modern habitat suitability for Podocarpus and Araucaria. The data reveals two long-distance patterns of plant migration connecting south/southeast to northeastern Brazil and Amazonia with a third short route extending from one of them. Their paleofloristic compositions suggest a climatic scenario of abundant rainfall and relative lower continental surface temperatures, possibly intensified by the effects of polar air incursions forming cold fronts into the Brazilian Highlands. Although these taxa are sensitive to changes in temperature, the combined pollen and speleothems proxy data indicate that this montane rainforest expansion during Heinrich Stadial 1 Event was triggered mainly by a less seasonal rainfall regime from the subtropics to the equatorial region.This work was funded by FAPESP research grant 2015/50683-2 to P.E. De Oliveira, VULPES Project, Belmount Forum