Model prediction and validation of an order mechanism controlling the spatio-temporal phenotype of early hepatocellular carcinoma

The aggressiveness of a tumor may be reflected by its micro-architecture. To gain a deeper understanding of the mechanisms controlling spatial organization of tumors at early stages after tumor initiation, we used an agent-based spatio-temporal model previously established to simulate features of liver regeneration. Here, this model was further developed to simulate scenarios in early tumor development, when individual initiated hepatocytes gain increased proliferation capacity. The model simulations were performed in realistic liver microarchitectures obtained from 3D reconstruction of confocal laser scanning micrographs. Interestingly, the here established model predicted that initially initiated hepatocytes arrange in elongated patterns. Only when the tumor progresses to cell numbers of approximately 4,000, it adopts spherical structures. This model prediction was validated by the analysis of initiated cells in a rat liver tumor initiation study using single doses of 250 mg/kg of the genotoxic carcinogen Nnitrosomorpholine (NNM). Indeed, small clusters of GST-P positive cells induced by NNM were elongated, almost columnar, while larger GDT-P positive foci of approximately the size of liver lobuli, adopted spherical shapes. Simulation of numerous possible mechanisms demonstrated that only hepatocyte-sinusoidal-alignment (HSA), a previously discovered order mechanism involved in coordination of liver tissue architecture, could explain the experimentally observed initial deviation from sphericalshape. The present study demonstrates that the architecture of small hepatocellular tumor cell clusters early after initiation is still controlled by physiological control mechanisms. However, this coordinating influence is lost when the tumor grows to approximately 4,000 cells, leading to further growth in spherical shape. Our findings stress the potential importance of organ micro-architecture in understanding tumor phenotypes

Regulated mitochondrial DNA replication during oocyte maturation is essential for successful porcine embryonic development.

Cellular ATP is mainly generated through mitochondrial oxidative phosphorylation, which is dependent on mitochondrial DNA (mtDNA). We have previously demonstrated the importance of oocyte mtDNA for porcine and human fertilization. However, the role of nuclear-encoded mitochondrial replication factors during oocyte and embryo development is not yet understood. We have analyzed two key factors, mitochondrial transcription factor A (TFAM) and polymerase gamma (POLG), to determine their role in oocyte and early embryo development. Competent and incompetent oocytes, as determined by brilliant cresyl blue (BCB) dye, were assessed intermittently during the maturation process for TFAM and POLG mRNA using real-time RT-PCR, for TFAM and POLG protein using immunocytochemistry, and for mtDNA copy number using real-time PCR. Analysis was also carried out following treatment of maturing oocytes with the mtDNA replication inhibitor, 2',3'-dideoxycytidine (ddC). Following in vitro fertilization, preimplantation embryos were also analyzed. Despite increased levels of TFAM and POLG mRNA and protein at the four-cell stage, no increase in mtDNA copy number was observed in early preimplantation development. To compensate for this, mtDNA appeared to be replicated during oocyte maturation. However, significant differences in nuclear-encoded regulatory protein expression were observed between BCB(+) and BCB(-) oocytes and between untreated oocytes and those treated with ddC. These changes resulted in delayed mtDNA replication, which correlated to reduced fertilization and embryonic development. We therefore conclude that adherence to the regulation of the timing of mtDNA replication during oocyte maturation is essential for successful embryonic development

Systemic PFOS and PFOA exposure and disturbed lipid homeostasis in humans: what do we know and what not?

Associations between per- and polyfluoroalkyl substances (PFASs) and increased blood lipids have been repeatedly observed in humans, but a causal relation has been debated. Rodent studies show reverse effects, i.e. decreased blood cholesterol and triglycerides, occurring however at PFAS serum levels at least 100-fold higher than those in humans. This paper aims to present the main issues regarding the modulation of lipid homeostasis by the two most common PFASs, PFOS and PFOA, with emphasis on the underlying mechanisms relevant for humans. Overall, the apparent contrast between human and animal data may be an artifact of dose, with different molecular pathways coming into play upon exposure to PFASs at very low versus high levels. Altogether, the interpretation of existing rodent data on PFOS/PFOA-induced lipid perturbations with respect to the human situation is complex. From a mechanistic perspective, research on human liver cells shows that PFOS/PFOA activate the PPARα pathway, whereas studies on the involvement of other nuclear receptors, like PXR, are less conclusive. Other data indicate that suppression of the nuclear receptor HNF4α signaling pathway, as well as perturbations of bile acid metabolism and transport might be important cellular events that require further investigation. Future studies with human-relevant test systems would help to obtain more insight into the mechanistic pathways pertinent for humans. These studies shall be designed with a careful consideration of appropriate dosing and toxicokinetics, so as to enable biologically plausible quantitative extrapolations. Such research will increase the understanding of possible perturbed lipid homeostasis related to PFOS/ PFOA exposure and the potential implications for human health

Risks for human and animal health related to the presence of phorbol esters in Jatropha kernel meal

The Panel wishes to thank the members of the Working Group on Phorbol Esters: Bruce Cottrill, Stefano Dall'Acqua, Johanna Fink-Gremmels, Harinder P.S. Makkar and Manfred Metzler for the preparatory work on this scientific opinion, and EFSA staff: Marco Binaglia, Karen Mackay and Rositsa Serafimova for the support provided to this scientific opinion.Peer reviewedPublisher PD

Presence of microplastics and nanoplastics in food, with particular focus on seafood

The Panel wishes to thank the members of the Working Group on the presence of microplastics and nanoplastics in food, with particular focus on seafood: Francesco Cubadda, Christer Hogstrand, Peter Hollman, Hendrik Van Loveren, Anne-Katrine Lundebye and Annette Petersen for the preparatory work on this statement, the hearing expert: Stephanie Wright and EFSA staff member: Karen Mackay for the support provided to this statement.Peer reviewedPublisher PD

Acute health risks related to the presence of cyanogenic glycosides in raw apricot kernels and products derived from raw apricot kernels

Peer reviewedPublisher PD

Malachite green in food

The Panel wishes to thank the members of the Standing Working Group on non-allowed pharmacologically active substances in food and feed and their reference points for action (2015–2018): Metka Filipič, Peter Fürst, Laurentius (Ron) Hoogenboom, Anne-Katrine Lundebye, Carlo Stefano Nebbia, Michael O'Keeffe and Rolaf Van Leeuwen for the preparatory work on this scientific output, the hearing expert: Eva Persson, and EFSA staff members: Katleen Baert and Sofia Ioannidou for the support provided to this scientific opinion. The CONTAM Panel acknowledges all European competent institutions and other stakeholders that provided occurrence data on malachite green and leucomalachite green in food, and supported the data collection for the Comprehensive European Food Consumption Database.Peer reviewedPublisher PD

Risk assessment of chlorinated paraffins in feed and food

The Panel wishes to thank the hearing expert: Kerstin Krätschmer and EFSA staff member: Kelly Niermans for the support provided to this scientific output. The CONTAM Panel acknowledges all European competent institutions and other stakeholders that provided occurrence data in food and human milk and data on the toxicity of CPs, and supported the data collection for the Comprehensive European Food Consumption Database.Peer reviewedPublisher PD

Assessment of an application on a detoxification process of groundnut press cake for aflatoxins by ammoniation

12 p.-2 fig.-2 tab.Following a request from the European Commission, the EFSA Panel on Contaminants in the Food Chain (CONTAM) provided a scientific opinion on an application for a detoxification process of groundnut press cake for aflatoxins by ammoniation. Specifically, it is required that the feed decontamination process is compliant with the acceptability criteria specified in the Commission Regulation (EU) 2015/786 of 19 May 2015. The CONTAM Panel assessed the data provided by the feed business operator with respect to the efficacy of the process to remove the contaminant from groundnut press cake batches and on information demonstrating that the process does not adversely affect the characteristics and the nature of the product. Although according to the literature the process may be able to reduce aflatoxin levels below the legal limits, the Panel concluded that the proposed decontamination process, on the basis of the experimental data submitted by the feed business operator, cannot be confirmed for compliance with the acceptability criteria provided for in Commission Regulation (EU) 2015/786 of 19 May 2015. The Panel recommended sufficient sample testing before and after the process, under the selected conditions, to ensure that the process is reproducible and reliable and to demonstrate that the detoxification is not reversible. In addition, genotoxicity testing of extracts of the treated feedingstuff and of the identified degradation products would be necessary. Finally, information on the transfer rate of AFB1 to AFM1 excretion in milk for animals fed the ammoniated product, in comparison to the starting material and on the ammoniation process changes of the nutritional values of the feed material should be provided.The Panel wishes to thank Federico Cruciani and Carina Wenger for the support provided to this scientific output, and the hearing expert Professor Dr Wayne L Bryden, for the overview on aflatoxin inactivation by ammoniation.Peer reviewe