Plant cell walls: impact on nutrient bioaccessibility and digestibility

Cell walls are important structural components of plants, affecting both the bioaccessibility and subsequent digestibility of the nutrients that plant-based foods contain. These supramolecular structures are composed of complex heterogeneous networks primarily consisting of cellulose, and hemicellulosic and pectic polysaccharides. The composition and organization of these different polysaccharides vary depending on the type of plant tissue, imparting them with specific physicochemical properties. These properties dictate how the cell walls behave in the human gastrointestinal tract, and how amenable they are to digestion, thereby modulating nutrient release from the plant tissue. This short narrative review presents an overview of our current knowledge on cell walls and how they impact nutrient bioaccessibility and digestibility. Some of the most relevant methods currently used to characterize the food matrix and the cell walls are also described

Back Matter

Back Matte

The metabolic syndrome - What is it and how should it be managed?

A cluster of metabolic factors have been merged into an entity named the metabolic syndrome. Although the characteristics of this syndrome have varied over time the presently used definition was established in 2009. The presence of three abnormal findings out of five components qualifies a person for the metabolic syndrome: elevated waist circumference, elevated triglycerides, reduced high-density lipoprotein cholesterol, elevated blood pressure and elevated fasting plasma glucose. Cut points have been defined for all components apart from waist circumference, for which national or regional values are used. The metabolic syndrome predicts cardiovascular disease and type 2 diabetes. This associated risk does not exceed its components whereof elevated blood pressure is the most frequent. A successful management should, however, address all factors involved. The management is always based on healthy lifestyle choices but has not infrequently to be supported by pharmacological treatment, especially blood pressure lowering drugs. The metabolic syndrome is a useful example of the importance of multiple targets for preventive interventions. To be successful management has to be individualized not the least when it comes to pharmacological therapy. Frail elderly people should not be over-treated. Knowledge transfer of how risk factors act should be accompanied by continuous trust building and motivation. In complex situations with a mix of biological risk factors, adverse social conditions and unhealthy lifestyle, everything cannot be changed at once. It is better to aim for small steps that are lasting than large, unsustainable steps with relapses to unhealthy behaviours. A person with the metabolic syndrome will always be afflicted by its components, which is the reason that management has to be sustained over a very long time. This review summarizes the knowledge on the metabolic syndrome and its management according to present state of the art.Peer reviewe

FAM13A and POM121C are candidate genes for fasting insulin: functional follow-up analysis of a genome-wide association study

Aims/hypothesis: By genome-wide association meta-analysis, 17 genetic loci associated with fasting serum insulin (FSI), a marker of systemic insulin resistance, have been identified. To define potential culprit genes in these loci, in a cross-sectional study we analysed white adipose tissue (WAT) expression of 120 genes in these loci in relation to systemic and adipose tissue variables, and functionally evaluated genes demonstrating genotype-specific expression in WAT (eQTLs). Methods: Abdominal subcutaneous adipose tissue biopsies were obtained from 114 women. Basal lipolytic activity was measured as glycerol release from adipose tissue explants. Adipocytes were isolated and insulin-stimulated incorporation of radiolabelled glucose into lipids was used to quantify adipocyte insulin sensitivity. Small interfering RNA-mediated knockout in human mesenchymal stem cells was used for functional evaluation of genes. Results: Adipose expression of 48 of the studied candidate genes associated significantly with FSI, whereas expression of 24, 17 and 2 genes, respectively, associated with adipocyte insulin sensitivity, lipolysis and/or WAT morphology (i.e. fat cell size relative to total body fat mass). Four genetic loci contained eQTLs. In one chromosome 4 locus (rs3822072), the FSI-increasing allele associated with lower FAM13A expression and FAM13A expression associated with a beneficial metabolic profile including decreased WAT lipolysis (regression coefficient, R = −0.50, p = 5.6 × 10−7). Knockdown of FAM13A increased lipolysis by ~1.5- fold and the expression of LIPE (encoding hormone-sensitive lipase, a rate-limiting enzyme in lipolysis). At the chromosome 7 locus (rs1167800), the FSI-increasing allele associated with lower POM121C expression. Consistent with an insulin-sensitising function, POM121C expression associated with systemic insulin sensitivity (R = −0.22, p = 2.0 × 10−2), adipocyte insulin sensitivity (R = 0.28, p = 3.4 × 10−3) and adipose hyperplasia (R = −0.29, p = 2.6 × 10−2). POM121C knockdown decreased expression of all adipocyte-specific markers by 25–50%, suggesting that POM121C is necessary for adipogenesis. Conclusions/interpretation: Gene expression and adipocyte functional studies support the notion that FAM13A and POM121C control adipocyte lipolysis and adipogenesis, respectively, and might thereby be involved in genetic control of systemic insulin sensitivity

Return mapping of phases and the analysis of the gravitational clustering hierarchy

In the standard paradigm for cosmological structure formation, clustering develops from initially random-phase (Gaussian) density fluctuations in the early Universe by a process of gravitational instability. The later, non-linear stages of this process involve Fourier mode-mode interactions that result in a complex pattern of non-random phases. We present a novel mapping technique that reveals mode coupling induced by this form of nonlinear interaction and allows it to be quantified statistically. The phase mapping technique circumvents the difficulty of the circular characteristic of phi_k and illustrates the statistical significance of phase difference at the same time. This generalized method on phases allows us to detect weak coupling of phases on any Delta k scales.Comment: 7 pages, minor changes, MNRAS accepte

The medical profession, industry and continuing medical education:finding the balance that's right for patients

Provision and participation in formal external continuing medical education (CME) is costly. Employer or state support of CME is the exception rather than the rule. The medical industry has supported both providers and consumers of educational activities, leading to concerns of commercial bias. Recent medical industry initiatives in Europe to improve the transparency of the relationship between industry and the profession, including the field of medical education, have had the paradoxical effect of the industry playing an increasingly direct role in the provision of physician education. Funding of medical professional society annual congresses has been directly and indirectly jeopardized. Acknowledging that there are areas of cooperation in the field of education between the medical profession and the medical industry from which both can benefit, we argue that medical education requires an objective approach that the primary fiduciary duty of medical industry companies precludes. Medical professional societies, as not-for-profit organizations whose core mission is the development and promotion of best practice, are best placed to guide and deliver medical education to their members. (C) 2019 Published by Elsevier Inc

Identification of furfural resistant strains of Saccharomyces cerevisiae and Saccharomyces paradoxus from a collection of environmental and industrial isolates

Background Fermentation of bioethanol using lignocellulosic biomass as a raw material provides a sustainable alternative to current biofuel production methods by utilising waste food streams as raw material. Before lignocellulose can be fermented it requires physical, chemical and enzymatic treatment in order to release monosaccharides, a process that causes the chemical transformation of glucose and xylose into the cyclic aldehydes furfural and hydroxyfurfural. These furan compounds are potent inhibitors of Saccharomyces fermentation, and consequently furfural tolerant strains of Saccharomyces are required for lignocellulosic fermentation. Results This study investigated yeast tolerance to furfural and hydroxyfurfural using a collection of 71 environmental and industrial isolates of the baker’s yeast Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus. The Saccharomyces strains were initially screened for growth on media containing 100 mM glucose and 1.5 mg ml-1 furfural. Five strains were identified that showed a significant tolerance to growth in the presence of furfural and these were then screened for growth and ethanol production in the presence of increasing amounts (0.1-4 mg ml-1) of furfural. Conclusions Of the five furfural tolerant strains S. cerevisiae NCYC 3451 displayed the greatest furfural resistance, and was able to grow in the presence of up to 3.0 mg ml-1 furfural. Furthermore, ethanol production in this strain did not appear to be inhibited by furfural, with the highest ethanol yield observed at 3.0 mg ml-1 furfural. Although furfural resistance was not found to be a trait specific to any one particular lineage or population, three of the strains were isolated from environments where they might be continually exposed to low levels of furfural through the on-going natural degradation of lignocelluloses, and would therefore develop elevated levels of resistance to these furan compounds. Thus these strains represent good candidates for future studies of genetic variation relevant to understanding and manipulating furfural resistance and in the development of tolerant ethanologenic yeast strains for use in bioethanol production from lignocellulose processing

Comparison of the behavior of fungal and plant cell wall during gastrointestinal digestion and resulting health effects: A review

Background; The structure of many plant- and fungal-based foods is determined by cell walls which are the primary source of dietary fiber. Several studies have shown that consumption of cell wall fibers from plants and fungi can modulate digestion leading to health-promoting effects such as increasing satiety and reducing the risk of cardiovascular diseases and type-2 diabetes. Scope and Approach; We focus on the impact of the food structure determined by plant and fungal cell walls on digestion and subsequent physiological responses. The underlying mechanisms promoting health effects may differ between plant and fungal cell walls, considering their different structural and biochemical organizations. Fungal cell walls have been vastly understudied compared to plant cell walls in this regard. Therefore, we highlight differences and similarities of plant- and fungal-based foods that may underlie the observed health benefits. Key Findings and Conclusions; The ability of the plant cell walls in our diet to influence digestion and improve human health has been intensely investigated over many years. The health outcomes observed following plants and fungi consumption appear similar, despite fundamental differences between the two kingdoms of life. The possible mechanisms underlying the health effects are the control of nutrient bioaccessibility, binding and sequestration of digestive components, increasing viscosity, and colonic fermentation. Mechanisms by which cell walls influence bioaccessibility of nutrients from fungal and plant cell walls are discussed. Moreover, consistent evidence for the fungal counterpart is still lacking, and further studies focusing on the whole structure of fungi are required

Phase Correlations in Cosmic Microwave Background Temperature Maps

We study the statistical properties of spherical harmonic modes of temperature maps of the cosmic microwave background. Unlike other studies, which focus mainly on properties of the amplitudes of these modes, we look instead at their phases. In particular, we present a simple measure of phase correlation that can be diagnostic of departures from the standard assumption that primordial density fluctuations constitute a statistically homogeneous and isotropic Gaussian random field, which should possess phases that are uniformly random on the unit circle. The method we discuss checks for the uniformity of the distribution of phase angles using a non-parametric descriptor based on the use order statistics, which is known as Kuiper's statistic. The particular advantage of the method we present is that, when coupled to the judicious use of Monte Carlo simulations, it can deliver very interesting results from small data samples. In particular, it is useful for studying the properties of spherical harmonics at low l for which there are only small number of independent values of m and which therefore furnish only a small number of phases for analysis. We apply the method to the COBE-DMR and WMAP sky maps, and find departures from uniformity in both. In the case of WMAP, our results probably reflect Galactic contamination or the known variation of signal-to-noise across the sky rather than primordial non-Gaussianity.Comment: 18 pages, 4 figures, accepted for publication in MNRA