Perioperative nutrition in abdominal surgery: recommendations and reality.

Introduction. Preoperative malnutrition is a major risk factor for increased postoperative morbidity and mortality. Definition and diagnosis of malnutrition and its treatment is still subject for controversy. Furthermore, practical implementation of nutrition-related guidelines is unknown. Methods. A review of the available literature and of current guidelines on perioperative nutrition was conducted. We focused on nutritional screening and perioperative nutrition in patients undergoing digestive surgery, and we assessed translation of recent guidelines in clinical practice. Results and Conclusions. Malnutrition is a well-recognized risk factor for poor postoperative outcome. The prevalence of malnutrition depends largely on its definition; about 40% of patients undergoing major surgery fulfil current diagnostic criteria of being at nutritional risk. The Nutritional Risk Score is a pragmatic and validated tool to identify patients who should benefit from nutritional support. Adequate nutritional intervention entails reduced (infectious) complications, hospital stay, and costs. Preoperative oral supplementation of a minimum of five days is preferable; depending on the patient and the type of surgery, immune-enhancing formulas are recommended. However, surgeons' compliance with evidence-based guidelines remains poor and efforts are necessary to implement routine nutritional screening and nutritional support.

Transgenic Arabidopsis plants can accumulate polyhydroxybutyrate to up to 4% of their fresh weight.

Transgenic Arabidopsis thaliana (L.) Heynh. plants expressing the three enzymes encoding the biosynthetic route to polyhydroxybutyrate (PHB) are described. These plants accumulated more than 4% of their fresh weight (approximately 40% of their dry weight) in the form of PHB in leaf chloroplasts. These very high producers were obtained and identified following a novel strategy consisting of a rapid GC-MS analysis of a large number of transgenic Arabidopsis plants generated using a triple construct, thus allowing the parallel transfer of all three genes necessary for PHB synthesis in a single transformation event. The level of PHB produced was 4-fold greater than previously published values, thus demonstrating the large potential of plants to produce this renewable resource. However, the high levels of the polymer produced had severe effects on both plant development and metabolism. Stunted growth and a loss of fertility were observed in the high-producing lines. Analysis of the metabolite composition of these lines using a GC-MS method that we have newly developed showed that the accumulation of high levels of PHB was not accompanied by an appreciable change in either the composition or the amount of fatty acids. Substantial changes were, however, observed in the levels of various organic acids, amino acids, sugars and sugar alcohols.

Does a shift in host plants trigger speciation in the Alpine leaf beetle Oreina speciosissima (Coleoptera, Chrysomelidae)?

Background: Within the Coleoptera, the largest order in the animal kingdom, the exclusively herbivorous Chrysomelidae are recognized as one of the most species rich beetle families. The evolutionary processes that have fueled radiation into the more than thirty-five thousand currently recognized leaf beetle species remain partly unresolved. The prominent role of leaf beetles in the insect world, their omnipresence across all terrestrial biomes and their economic importance as common agricultural pest organisms make this family particularly interesting for studying the mechanisms that drive diversification. Here we specifically focus on two ecotypes of the alpine leaf beetle Oreina speciosissima (Scop.), which have been shown to exhibit morphological differences in male genitalia roughly corresponding to the subspecies Oreina speciosissima sensu stricto and Oreina speciosissima troglodytes. In general the two ecotypes segregate along an elevation gradient and by host plants: Oreina speciosissima sensu stricto colonizes high forb vegetation at low altitude and Oreina speciosissima troglodytes is found in stone run vegetation at higher elevations. Both host plants and leaf beetles have a patchy geographical distribution. Through use of gene sequencing and genome fingerprinting (AFLP) we analyzed the genetic structure and habitat use of Oreina speciosissima populations from the Swiss Alps to examine whether the two ecotypes have a genetic basis. By investigating a wide range of altitudes and focusing on the structuring effect of habitat types, we aim to provide answers regarding the factors that drive adaptive radiation in this phytophagous leaf beetle.Results: While little phylogenetic resolution was observed based on the sequencing of four DNA regions, the topology and clustering resulting from AFLP genotyping grouped specimens according to their habitat, mostly defined by plant associations. A few specimens with intermediate morphologies clustered with one of the two ecotypes or formed separate clusters consistent with habitat differences. These results were discussed in an ecological speciation framework.Conclusions: The question of whether this case of ecological differentiation occurred in sympatry or allopatry remains open. Still, the observed pattern points towards ongoing divergence between the two ecotypes which is likely driven by a recent shift in host plant use.

The high road and the low road: trafficking choices in plants.

Polar transport of the signaling molecule auxin is critical for plant development and depends on both the polar distribution of auxin efflux carriers, which pump auxin out of the cell and the alignment of these polarized cells. Two papers in this issue of Cell (Michniewicz et al., 2007; Jaillais et al., 2007) address how polar transport of these carriers occurs and describe the endosomal pathways involved.

Production of new polymeric compounds in plants.

Plant metabolic engineering has recently enabled the synthesis of a range of polyhydroxyalkanoates as well as a protein-based polymer. These novel compounds can be harvested from plants as a renewable source of environmentally friendly polymers or can be used to change the physical properties of plant products, such as fibres.

Prevention and treatment of protein energy wasting in chronic kidney disease patients: a consensus statement by the International Society of Renal Nutrition and Metabolism.

Protein energy wasting (PEW) is common in patients with chronic kidney disease (CKD) and is associated with adverse clinical outcomes, especially in individuals receiving maintenance dialysis therapy. A multitude of factors can affect the nutritional and metabolic status of CKD patients requiring a combination of therapeutic maneuvers to prevent or reverse protein and energy depletion. These include optimizing dietary nutrient intake, appropriate treatment of metabolic disturbances such as metabolic acidosis, systemic inflammation, and hormonal deficiencies, and prescribing optimized dialytic regimens. In patients where oral dietary intake from regular meals cannot maintain adequate nutritional status, nutritional supplementation, administered orally, enterally, or parenterally, is shown to be effective in replenishing protein and energy stores. In clinical practice, the advantages of oral nutritional supplements include proven efficacy, safety, and compliance. Anabolic strategies such as anabolic steroids, growth hormone, and exercise, in combination with nutritional supplementation or alone, have been shown to improve protein stores and represent potential additional approaches for the treatment of PEW. Appetite stimulants, anti-inflammatory interventions, and newer anabolic agents are emerging as novel therapies. While numerous epidemiological data suggest that an improvement in biomarkers of nutritional status is associated with improved survival, there are no large randomized clinical trials that have tested the effectiveness of nutritional interventions on mortality and morbidity.

Effects of L-carnitine supplemented total parenteral nutrition on lipid and energy metabolism in postoperative stress.

During episodes of trauma carnitine-free total parenteral nutrition (TPN) may result in a reduction of the total body carnitine pool, leading to a diminished rate of fat oxidation. Sixteen patients undergoing esophagectomy were divided randomly in two equal isonitrogenous groups (0.2 g/kg.day). Both received TPN (35 kcal/kg.day; equally provided as long-chain triglycerides and glucose) over 11 days without (group A) and with (group B) L-carnitine supplementation (12 mg/kg.day = 75 mumol/kg.day). Compared with healthy controls, the total body carnitine pool prior to the operation was significantly reduced in both groups, suggesting a state of semistarvation and muscle wasting. In group A the plasma levels of total carnitine and its subfractions (free carnitine, short- and long-chain acylcarnitine) remained stable during the study whereas in group B the total plasma carnitine concentration rose mainly due to an increase in free carnitine. In group A the cumulative urinary carnitine losses were 11.5 +/- 2.6 mmol (= 15.5 +/- 3.1% of the estimated total body carnitine pool). In group B 3.1 +/- 1.9 mmol (= 11.1 +/- 7.6%) of the infused carnitine was retained in the immediate postoperative phase until day 6, but this amount was completely lost at completion of the study period. No significant differences in the respiratory quotient or in the plasma levels of triglycerides, free fatty acids, and ketone bodies were observed, between or within the groups, before the operation and after 11 days of treatment. It is concluded that the usefulness of carnitine supplementation during postoperative TPN was not apparent in the present patient material.

Epigenetics and neonatal nutrition.

Epigenetic changes have long-lasting effects on gene expression and are related to, and often induced by, the environment in which early development takes place. In particular, the period of development that extends from pre-conception to early infancy is the period of life during which epigenetic DNA imprinting activity is the most active. Epigenetic changes have been associated with modification of the risk for developing a wide range of adulthood, non-communicable diseases (including cardiovascular diseases, metabolic diseases, diseases of the reproductive system, etc.). This paper reviews the molecular basis of epigenetics, and addresses the issues related to the process of developmental programming of the various areas of human health.

Generation of cell polarity in plants links endocytosis, auxin distribution and cell fate decisions.

Dynamically polarized membrane proteins define different cell boundaries and have an important role in intercellular communication-a vital feature of multicellular development. Efflux carriers for the signalling molecule auxin from the PIN family are landmarks of cell polarity in plants and have a crucial involvement in auxin distribution-dependent development including embryo patterning, organogenesis and tropisms. Polar PIN localization determines the direction of intercellular auxin flow, yet the mechanisms generating PIN polarity remain unclear. Here we identify an endocytosis-dependent mechanism of PIN polarity generation and analyse its developmental implications. Real-time PIN tracking showed that after synthesis, PINs are initially delivered to the plasma membrane in a non-polar manner and their polarity is established by subsequent endocytic recycling. Interference with PIN endocytosis either by auxin or by manipulation of the Arabidopsis Rab5 GTPase pathway prevents PIN polarization. Failure of PIN polarization transiently alters asymmetric auxin distribution during embryogenesis and increases the local auxin response in apical embryo regions. This results in ectopic expression of auxin pathway-associated root-forming master regulators in embryonic leaves and promotes homeotic transformation of leaves to roots. Our results indicate a two-step mechanism for the generation of PIN polar localization and the essential role of endocytosis in this process. It also highlights the link between endocytosis-dependent polarity of individual cells and auxin distribution-dependent cell fate establishment for multicellular patterning.

Forecasting changes in population genetic structure of alpine plants in response to global warming.

Species range shifts in response to climate and land use change are commonly forecasted with species distribution models based on species occurrence or abundance data. Although appealing, these models ignore the genetic structure of species, and the fact that different populations might respond in different ways because of adaptation to their environment. Here, we introduced ancestry distribution models, that is, statistical models of the spatial distribution of ancestry proportions, for forecasting intra-specific changes based on genetic admixture instead of species occurrence data. Using multi-locus genotypes and extensive geographic coverage of distribution data across the European Alps, we applied this approach to 20 alpine plant species considering a global increase in temperature from 0.25 to 4 °C. We forecasted the magnitudes of displacement of contact zones between plant populations potentially adapted to warmer environments and other populations. While a global trend of movement in a north-east direction was predicted, the magnitude of displacement was species-specific. For a temperature increase of 2 °C, contact zones were predicted to move by 92 km on average (minimum of 5 km, maximum of 212 km) and by 188 km for an increase of 4 °C (minimum of 11 km, maximum of 393 km). Intra-specific turnover-measuring the extent of change in global population genetic structure-was generally found to be moderate for 2 °C of temperature warming. For 4 °C of warming, however, the models indicated substantial intra-specific turnover for ten species. These results illustrate that, in spite of unavoidable simplifications, ancestry distribution models open new perspectives to forecast population genetic changes within species and complement more traditional distribution-based approaches.

Functional and molecular evolutionary analysis of the "Brevix Radix" gene family in mono-and dicotyledonous plants

ABSTRACTIn contrast to animals, plants cannot move from their place of birth and, therefore, need to adapt to their particular habitat in order to survive. Thus, plant development is remarkably plastic, making plants an ideal system for the isolation of genes that account for intraspecific natural variation and possibly environmental adaptation. However, to date, this approach mostly identified null alleles and missed mutations with subtle effects. For instance, BREVIS RADIX (BRX) has been isolated as a key regulator of root growth through a naturally occurring loss-of-function allele in the Arabidopsis thaliana accession Uk-1 and is the founding member of a highly-conserved plant-specific gene family.In this work, we show that a strong selective pressure is acting on the BRX gene family and dates back before the monocot-dicot divergence. However, functional diversification is observed mainly in dicotyledon BRX family genes and is correlated with acceleration in the evolutionary rates in the N-terminal regions. Population genetic data revealed that BRX is highly conserved across Arabidopsis accessions and presents signatures of adaptation. Interestingly, a seven amino acid deletion polymorphism in BRX sequence was found in a few accessions, which seems to be responsible for their enhanced primary root growth. Nevertheless, BRX might not only be active in the root, as suggested by its expression in the shoot. Indeed, leaves and cotyledons of brx mutants are significantly smaller than wild- type. This phenotype is a direct consequence of the absence of BRX function in the shoot rather than an indirect effect of an altered root system growth. Interestingly, cotyledons of brx plants reflect the same physiological defects as the root. Moreover, phenotypes in BRX gain-of-function plants, such as epinastic leaves and increased epidermal cell size, could be associated with an increase in leaf brassinosteroid content.Collectively, these results indicate that BRX contributes to local adaptation by ubiquitously regulating plant growth, probably through the modulation of brassinosteroid biosynthesis.RÉSUMÉContrairement à la plupart des animaux, les plantes ne peuvent se mouvoir et doivent ainsi s'adapter à leur environnement pour survivre. Pour cette raison, elles représentent un système idéal pour l'identification de gènes contribuant à la variation naturelle intra- spécifique, ainsi qu'à l'adaptation. Cependant, cette approche a, jusqu'à présent, surtout permis d'isoler des allèles nuls et non des mutations conférant des effets plus subtiles. C'est le cas du gène Β REVIS RADIX (BRX), un régulateur clé de la croissance racinaire, qui a été identifié grâce à un allèle non-fonctionnel présent dans l'accession naturelle d'Arabidopsis thaliana Uk-1. BRX et ses homologues des plantes mono- et dicotylédones forment une famille très conservée et spécifique aux plantes.Dans ce travail, nous démontrons que la famille de gènes BRX est soumise à une forte pression de sélection qui remonte avant la divergence entre mono- et dicotylédones. Cependant, une diversification fonctionnelle a été observée chez les gènes des dicotylédones et corrèle avec une accélération de la vitesse d'évolution dans leur région N- terminale. Une analyse génétique de différentes accessions naturelles d'Arabidopsis a révélé que BRX est hautement conservé et présente des signatures d'adaptation. Remarquablement, un polymorphisme de délétion de sept acides aminés a été détecté dans quelques accessions et a pour conséquence une plus forte croissance de la racine primaire. Néanmoins, il semble que le rôle de BRX ne se limite pas qu'à la racine, comme indiqué par son expression dans les parties aériennes de la plante. En effet, les mutants brx présentent des cotylédons et des feuilles significativement plus petits que le type sauvage, une conséquence directe de l'absence d'activité de BRX dans ces organes. Nous avons aussi noté que les cotylédons des mutants brx, à l'instar des racines, ont une perception altérée de l'auxine et peuvent être complémentés par l'application exogène de brassinostéroïdes. De plus, dans des plantes présentant un gain de fonction BRX, les feuilles sont épinastiques et les cellules de leur épiderme plus grandes. Ces phénotypes sont accompagnés d'une augmentation de la concentration de brassinostéroïdes dans les feuilles. Conjointement, ces résultats démontrent que BRX contribue à une adaptation locale de la plante par la régulation générale de sa croissance, probablement en modulant la biosynthèse des brassinostéroïdes.