In silico trials of food digestion and absorption: how far are we?

In recent years, experimental research on the mechanisms of food digestion in the gastrointestinal tract has strengthened our knowledge on the effect of food on human health. A number of mathematical models have been proposed to rationalize our understanding on the related mechanisms. One common suggestion is that in silico models could be interconnected and used in the future to predict the effect of food systems (liquid or solid, inner microstructure, state of nutrients…) on various metabolic responses. This paper aims to provide a brief overview of the latest developments in this young but promising field of research

A standardised static in vitro digestion method suitable for food – an international consensus

peer-reviewedSimulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.COST action FA1005 Infogest22 (http://www.cost-infogest.eu/) is acknowledged for providing funding for travel, meetings and conferences

The subpopulation pattern of eel sperm is affected by post-activation time, hormonal treatment and thermal regime

[EN] There has been a marked reduction in natural stocks of eels (genus Anguilla) over the past 60 years, and the culture of eels is still based on the capture of very large quantities of juveniles. It is necessary to close the life cycle in captivity in order to ease the pressure on wild populations. The aims of the present study were to evaluate sperm subpopulations (through cluster analysis of computer-aided sperm analysis data) in the European eel (Anguilla anguilla) and to assess the effects of motility acquisition time after activation (i.e. at 30, 60 and 90 s), the thermal regimen (i.e. 10 degrees C (T10) or 15 degrees C (T15) and up to 20 degrees C, or constant at 20 degrees C (T20)) and hormonal treatments (i.e. human chorionic gonadotropin (hCG), recombinant (r) hCG or pregnant mare serum gonadotropin (PMSG)) on these subpopulations. In all cases, we obtained three subpopulations of spermatozoa: low velocity and linear (S1); high velocity with low linearity (S2); and high velocity and linear (S3; considered high quality). Total motility and S1 were affected by acquisition time; thus, 30 s is recommended as the standard time for motility acquisition. When eels were kept at 20 degrees C (T20), motility data fitted quadratic models, with the highest motility and proportion of S3 between Weeks 8 and 12 after the first injection. Lower temperatures (T10, T15) delayed spermiation and the obtaining of high-quality spermatozoa (S3), but did not seem to alter the spermiation process (similar subpopulation pattern). Conversely, the hormonal treatments altered both the dynamics of the subpopulation pattern and the onset of spermiation (with PMSG delaying it). Total motility and the yield of S3 with the widely used hCG treatment varied throughout the spermiation period. However, using rhCG allowed us to obtain high-quality and constant motility for most of the study (Weeks 7-20), and the S3 yield was also higher overall (61.8 +/- 1.3%; mean +/- s.e.m.) and more stable over time than the other hormonal treatments (averaging 53.0 +/- 1.4%). Using T20 and rhCG would be more economical and practical, allowing us to obtain a higher number of S3 spermatozoa over an extended time.This study was funded by the European Community's 7th Framework Program under the Theme 2 'Food, Agriculture and Fisheries, and Bio-technology', grant agreement no. 245257 (PRO-EEL) and Generalitat Valenciana (ACOMP/2012/086). VG and MCV have predoctoral grants from the Spanish Ministry of Economy and Competitiveness (AGL2010-16009) and Universitat Politecnica de Valencia (UPV) PAID Program (2011-S2-02-6521), respectively. DSP was supported by a contract cofinanced by Ministry of Science and Innovation (MICINN) and UPV (PTA2011-4948-I). FM-P was supported by the Ramon y Cajal program (MICINN, RYC-2008-02560).Gallego Albiach, V.; Vilchez Olivencia, MC.; Peñaranda, D.; Pérez Igualada, LM.; Herraez, MP.; Asturiano Nemesio, JF.; Martinez-Pastor, F. (2015). The subpopulation pattern of eel sperm is affected by post-activation time, hormonal treatment and thermal regime. Reproduction, Fertility and Development. 27(3):529-543. https://doi.org/10.1071/RD13198S52954327

The harmonized INFOGEST in vitro digestion method: From knowledge to action

Within the active field of in vitro digestion in food research, the COST Action INFOGEST aimed to harmonize in vitro protocols simulating human digestion on the basis of physiologically inferred conditions. A harmonized static in vitro digestion (IVD) method was recently published as a primary output from this network. To validate this protocol, inter-laboratory trials were conducted within the INFOGEST network. A first study was performed using skim milk powder (SMP) as a model food and served to compare the different in-house digestion protocols used among the INFOGEST members. In a second inter-laboratory study applying the harmonized protocol, the degree of consistency in protein hydrolysis was investigated. Analysis of the hydrolyzed proteins, after the gastric and intestinal phases, showed that caseins were mainly hydrolyzed during the gastric phase, whereas β-lactoglobulin was, as previously shown, resistant to pepsin. Moreover, generation of free amino acids occurred mainly during the intestinal phase.The study also showed that a few critical steps were responsible for the remaining inter-laboratory variability. The largest deviations arose from the determination of pepsin activity. Therefore, this step was further clarified, harmonized, and implemented in a third inter-laboratory study.The present work gives an overview of all three inter-laboratory studies, showing that the IVD INFOGEST method has led to an increased consistency that enables a better comparability of in vitro digestion studies in the future

Toward an integrated modeling of the dairy product transformations, a review of the existing mathematical models

The large diversity of dairy products is the consequence of complex processes involving series of unit operations with a wide range of controls that makes the completemodeling awkward. Due to the variety of milk components and process conditions, a generic model describing the milk processing can only be achieved by the integration of various models into a generic modeling framework. Moreover, the building of such an approach involves the coupling of transformation models describing each unit operation. In this scope, the present work aims to review existing mathematical models of the dairy products processing with a special focus on some main process units: thermal treatment, homogenization and coagulation. For each unit operation, several transformation models are investigated according to their complexities, relevance to depict actual phenomena and ability to be integrated with others models to represent complex transformations. As a first step for the integration of models, a focus on their input parameters and predicted variables is achieved

A standardised static in vitro digestion method suitable for food – an international consensus

Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.COST action FA1005 Infogest22 (http://www.cost-infogest.eu/) is acknowledged for providing funding for travel, meetings and conferences

Genetic evidence of a precisely tuned dysregulation in the hypoxia signaling pathway during oncogenesis.

The classic model of tumor suppression implies that malignant transformation requires full "two-hit" inactivation of a tumor-suppressor gene. However, more recent work in mice has led to the proposal of a "continuum" model that involves more fluid concepts such as gene dosage-sensitivity and tissue specificity. Mutations in the tumor-suppressor gene von Hippel-Lindau (VHL) are associated with a complex spectrum of conditions. Homozygotes or compound heterozygotes for the R200W germline mutation in VHL have Chuvash polycythemia, whereas heterozygous carriers are free of disease. Individuals with classic, heterozygous VHL mutations have VHL disease and are at high risk of multiple tumors (e.g., CNS hemangioblastomas, pheochromocytoma, and renal cell carcinoma). We report here an atypical family bearing two VHL gene mutations in cis (R200W and R161Q), together with phenotypic analysis, structural modeling, functional, and transcriptomic studies of these mutants in comparison with classical mutants involved in the different VHL phenotypes. We demonstrate that the complex pattern of disease manifestations observed in VHL syndrome is perfectly correlated with a gradient of VHL protein (pVHL) dysfunction in hypoxia signaling pathways. Thus, by studying naturally occurring familial mutations, our work validates in humans the "continuum" model of tumor suppression