Emergent structure and dynamics of tropical forest-grassland landscapes.

Previous work indicates that tropical forest can exist as an alternative stable state to savanna. Therefore, perturbation by climate change or human impact may lead to crossing of a tipping point beyond which there is rapid forest dieback that is not easily reversed. A hypothesized mechanism for such bistability is feedback between fire and vegetation, where fire spreads as a contagion process on grass patches.

Mean-field models of dynamics on networks via moment closure: An automated procedure.

In the study of dynamics on networks, moment closure is a commonly used method to obtain low-dimensional evolution equations amenable to analysis. The variables in the evolution equations are mean counts of subgraph states and are referred to as moments. Due to interaction between neighbors, each moment equation is a function of higher-order moments, such that an infinite hierarchy of equations arises.

Tropical tree cover in a heterogeneous environment: A reaction-diffusion model.

Observed bimodal tree cover distributions at particular environmental conditions and theoretical models indicate that some areas in the tropics can be in either of the alternative stable vegetation states forest or savanna. However, when including spatial interaction in nonspatial differential equation models of a bistable quantity, only the state with the lowest potential energy remains stable. Our recent reaction-diffusion model of Amazonian tree cover confirmed this and was able to reproduce the observed spatial distribution of forest versus savanna satisfactorily when forced by heterogeneous environmental and anthropogenic variables, even though bistability was underestimated.

Author Correction: Amazonian forest-savanna bistability and human impact.

This corrects the article DOI: 10.1038/ncomms15519.

Amazonian forest-savanna bistability and human impact.

A bimodal distribution of tropical tree cover at intermediate precipitation levels has been presented as evidence of fire-induced bistability. Here we subdivide satellite vegetation data into those from human-unaffected areas and those from regions close to human-cultivated zones. Bimodality is found to be almost absent in the unaffected regions, whereas it is significantly enhanced close to cultivated zones.

Fermentable soluble fibres spare amino acids in healthy dogs fed a low-protein diet.

Background: Research in cats has shown that increased fermentation-derived propionic acid and its metabolites can be used as alternative substrates for gluconeogenesis, thus sparing amino acids for other purposes. This amino acid sparing effect could be of particular interest in patients with kidney or liver disease, where this could reduce the kidneys'/liver's burden of N-waste removal. Since dogs are known to have a different metabolism than the obligatory carnivorous cat, the main objective of this study was to assess the possibility of altering amino acid metabolism through intestinal fermentation in healthy dogs.

Does canine inflammatory bowel disease influence gut microbial profile and host metabolism?

Background: Inflammatory bowel disease (IBD) refers to a diverse group of chronic gastrointestinal diseases, and gut microbial dysbiosis has been proposed as a modulating factor in its pathogenesis. Several studies have investigated the gut microbial ecology of dogs with IBD but it is yet unclear if this microbial profile can alter the nutrient metabolism of the host. The aim of the present study was to characterize the faecal bacterial profile and functionality as well as to determine host metabolic changes in IBD dogs.

Choline supplementation restores substrate balance and alleviates complications of Pcyt2 deficiency.

Choline plays a critical role in systemic lipid metabolism and hepatic function. Here we conducted a series of experiments to investigate the effect of choline supplementation on metabolically altered Pcyt2(+/-) mice. In Pcyt2(+/-) mice, the membrane phosphatidylethanolamine (PE) turnover is reduced and the formation of fatty acids (FA) and triglycerides (TAG) increased, resulting in hypertriglyceridemia, liver steatosis and obesity.

In vitro disposition profiling of heterocyclic compounds.

Compound libraries that are screened for biological activity commonly contain heterocycles. Besides potency, drug-like properties need to be evaluated to ensure in vivo efficacy of test compounds. In this context, we determined hepatic and intestinal disposition profiles for 17 heterocyclic compounds.

β-Alanine does not act through branched-chain amino acid catabolism in carp, a species with low muscular carnosine storage.

This study was executed to investigate the effect of dietary β-alanine (BA) on amino acid (AA) metabolism and voluntary feed intake in carp (Cyprinus carpio) at mildly elevated temperature to exert AA catabolism. Twenty-four fish in 12 aquaria were randomly assigned to either a control diet or the same diet with 500 mg BA/kg. A 14-day period at an ideal temperature (23 °C) was followed by 15 days at chronic mildly elevated temperature (27 °C).

Evaluation of fasted and fed state simulated and human intestinal fluids as solvent system in the Ussing chambers model to explore food effects on intestinal permeability.

The Ussing chambers model is almost exclusively used in the presence of plain aqueous phosphate buffers as solvent system. In an attempt to further elucidate the effect of luminal ingredients and postprandial conditions on intestinal permeability, pooled fasted and fed state human intestinal fluids (FaHIFpool, FeHIFpool) were used. In addition, simulated intestinal fluids of both nutritional states (FaSSIF, FeSSIF) were evaluated as possible surrogate media for HIF.

Evaluation of fasted state human intestinal fluid as apical solvent system in the Caco-2 absorption model and comparison with FaSSIF.

To date, the Caco-2 model is considered as the gold standard to predict intestinal drug absorption. Often, aqueous phosphate buffers are used as apical medium. The purpose of this study was to use fasted state human intestinal fluid (FaHIF) as apical solvent system to generate biorelevant permeability values for a series of 16 model drugs that can be used as reference data to critically evaluate fasted state simulated intestinal fluid (FaSSIF) as possible substitute medium.

Possible pathogenic mechanism of propofol infusion syndrome involves coenzyme q.

Background: Propofol is a short-acting intravenous anesthetic agent. In rare conditions, a life-threatening complication known as propofol infusion syndrome can occur. The pathophysiologic mechanism is still unknown.

Dietary supplementation of propionylated starch to domestic cats provides propionic acid as gluconeogenic substrate potentially sparing the amino acid valine.

In strict carnivorous domestic cats, a metabolic competition arises between the need to use amino acids for gluconeogenesis and for protein synthesis both in health and disease. The present study investigated the amino acid-sparing potential of propionic acid in cats using dietary propionylated starch (HAMSP) supplementation. A total of thirty cats were fed a homemade diet, supplemented with either HAMSP, acetylated starch (HAMSA) or celite (Control) for three adaptation weeks.

Human and simulated intestinal fluids as solvent systems to explore food effects on intestinal solubility and permeability.

The mixed micelles and vesicles present in the intraluminal environment of the postprandial state exhibit suitable solubilizing capacities for lipophilic drugs. This increase in solubility, however, is accompanied by a decrease in the free fraction caused by micellar entrapment of these lipophilic compounds. In this study, both simulated and aspirated human intestinal fluids of fasted and fed state conditions were used to evaluate the influence of food on the intestinal disposition of a series of structurally related β-blockers, with varying logP values.

Straightforward entry to pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones and their ADME properties.

A straightforward synthesis of pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones was developed starting from 2-chloropyridine-3-carboxylic acid by esterification, nucleophilic aromatic substitution and amide formation in one step, and ring closure allowing their synthesis with two identical or two different group attached to nitrogen. The structural diversity of these [2,3-d]pyrimidine-2,4(1H,3H)-diones resulted in significant variation in the biopharmaceutical properties. This was reflected by the broad range in fasted state simulated intestinal fluid solubility values (12.

Effect of peripartal feeding strategy on colostrum yield and composition in sows.

Research showed a positive association between back fat (BF) change the week before farrowing and colostrum yield (CY). This study tested the causality of this association, hence to optimize CY by altering the sows' peripartal feeding strategy. Sows were randomly divided into 2 treatment groups at d 108 of gestation.

The effect of a 3-month prevention program on the jump-landing technique in basketball: a randomized controlled trial.

Context: In jump-landing sports, the injury mechanism that most frequently results in an injury is the jump-landing movement. Influencing the movement patterns and biomechanical predisposing factors are supposed to decrease injury occurrence.

Objectives: To evaluate the influence of a 3-mo coach-supervised jump-landing prevention program on jump-landing technique using the jump-landing scoring (JLS) system.

Changes in back fat thickness during late gestation predict colostrum yield in sows.

Directing protein and energy sources towards lactation is crucial to optimise milk production in sows but how this influences colostrum yield (CY) remains unknown. The aim of this study was to identify associations between CY and the sow's use of nutrient resources. We included 37 sows in the study that were all housed, fed and managed similarly.

A review of drug solubility in human intestinal fluids: implications for the prediction of oral absorption.

The purpose of this paper is to collate all recently published solubility data of orally administered drugs in human intestinal fluids (HIF) that were aspirated from the upper small intestine (duodenum and jejunum). The data set comprises in total 102 solubility values in fasted state HIF and 37 solubility values in fed state HIF, covering 59 different drugs. Despite differences in the protocol for HIF sampling and subsequent handling, this summary of HIF solubilities provides a critical reference data set to judge the value of simulated media for intestinal solubility estimation.

Solubility profiling of HIV protease inhibitors in human intestinal fluids.

The present study pursued to profile the intestinal solubility of nine HIV protease inhibitors (PIs) in fasted- and fed-state human intestinal fluids (FaHIF, FeHIF) aspirated from four volunteers. In addition, the ability of fasted- and fed-state simulated intestinal fluids (FaSSIF, FeSSIF) to predict the intestinal solubility was evaluated. All PIs were poorly soluble in FaHIF (from 7 μM for ritonavir to 327 μM for darunavir) and FeHIF (from 15 μM for atazanavir to 409μM for darunavir).

Biopharmaceutical profiling of a pyrido[4,3-d] pyrimidine compound library.

The pyrido-pyrimidine structure is associated with different biological activities, including kinase inhibition and antibacterial activity. However, drug-like properties of this scaffold have not been explored thoroughly. Therefore, the biopharmaceutical profile of ten pyrido[4,3-d]pyrimidines with different substitution pattern was determined at the intestinal and hepatic level.

Microheterogeneity of serum β-hexosaminidase in chronic alcohol abusers in a driver's license regranting program.

Background: Carbohydrate-deficient transferrin (CDT) is one of the best indicators for chronic alcohol abuse and detection of relapse. In this study, we explore the microheterogeneity of β-hexosaminidase (β-HEX) in chronic alcohol abusers in the framework of a driver's license regranting program. Studies have shown that increased serum activity of β-HEX B (isoforms P, I, and B) may be a sensitive marker for chronic alcohol abuse.