402 research outputs found
Effect of the Nature and Concentration of Phthalates on Their Migration from PVC Materials Under Dynamic Simulated Conditions of Mouthing
Polyvinylchloride (PVC) has been a very common material for the production of toys. It generally is manufactured with an addition of additives such as plasticisers to improve its functionality and facilitate its production process. PVC that can contain up to 50% by weight of plasticisers (Simoneau et al., 2001). Among plasticisers, 90% of the most commonly used to soften polymers for toys production are constituted by phthalates, such as diisononyl phthalate (DINP).
The purpose of this study was to investigate the influence of the relative concentration of percentage of phthalates and nature of phthalates on their release in standard conditions. To obtain a suitable but rapid method of analysis, experiments were performed to study the effects on the modification of a standard operation procedure (SOP) previously validated at the EU level by JRC Ispra. A single extraction with a sufficient large volume of cyclohexane thus could be used instead of two extractions with a smaller volume of cyclohexane and resulted in more rapid yet reliable method. The final method is described in Annex 1 of this report.
Samples of soft PVC were industrially produced especially for this study.
Standard PVC disks with various percentages of di-isononyl phthalate (DINP), di-isodecyl phthalate (DIDP), di-ethyl-hexyll phthalate (DEHP), benzylbutyl phthalate (BBP) dibutylphthalate (DBP) or a binary mixture DINP/DBP in various proportions were prepared. 30 different types of disk were produced and tested. The disks were analysed for contents, homogeneity and sets were subjected to migration experiments of the various phthalates under dynamic conditions using the previously validated SOP with some modifications.
The release from samples with a systematic manufacturing process and containing different phthalates at different concentrations showed correlations to their concentrations. Since previous studies using commercial toys had no showed such specific trends, these results suggest that the production process of toys may be an important issue with respect to release properties. The release of DEHP BBP and DBP tended to show a more linear correlation to the concentration, whereas for DINP, DIDP, DEHP and release the plasticiser showed non linear tendencies and saturation of release for high formulation contents.JRC.I.2-Chemical assessment and testin
Suitability of new sources of olive oil intended to be used as simulant D in migration testing
Regulation EC/882/2004 on Feed and Food Controls establishes the JRC as Community Reference Laboratory for Food Contact Materials (CRL-FCM). The Regulation requires a supporting network of European National Reference Laboratories (NRLs). This Regulation supports the harmonised enforcement of food legislation including food contact materials and the creation of a reference laboratory system operated by the JRC to systematically exchange and assess information on emerging issues related to chemicals released from food contact materials.
The Council Directive 85/572/EEC of 19 December 1985 lays down the list of simulants for overall and specific migration testing, to be used for testing migration of constituents of plastic materials and articles intended to come into contact with foodstuff.
This Directive lists the appropriate simulants to be used in migration tests with a particular foodstuff or group of foodstuffs. Within simulants, simulant D is rectified olive oil that has to satisfy characteristics such as acidity, peroxide index, iodine index, refractive index.
Until 2005 rectified olive oil with documented appropriate technical specifications was commercially available from the company Pira International (UK). However commercial production stopped, and other potential sources available (Korea Japan, Sigma) did not necessarily provide specifications documented specifically for use as ¿simulant D¿.
Since the oil specifications set in the EU legislation are crucial, both for compliance testing but also in the frame of an ISO accreditation for migration in oil, NRLs suggested the CRL-FCM to investigate specifications potential sources of olive oil to develop a source of simulant D for their purposes.
The purpose of this study was to:
¿ Find potential suppliers for rectified olive oil
¿ Evaluate characteristics of oil on batch samples
¿ Select one supplier to purchase a lot of adequate defined specifications
¿ Establish the adequacy and homogeneity of the oil of a 500L lot
¿ Confirm the evaluation by independent analyses and certification by a specialised accredited institution for those specifications.
The results demonstrated the feasibility of at least one source of olive oil, which was then provided to the National Reference Laboratories as a deliverable of the workprogramme 2007.JRC.I.5-Physical and chemical exposure
Evolution of energy metabolism and its compartmentation in Kinetoplastida
Kinetoplastida are protozoan organisms that probably diverged early in evolution from other eukaryotes. They are characterized by a number of unique features with respect to their energy and carbohydrate metabolism. These organisms possess peculiar peroxisomes, called glycosomes, which play a central role in this metabolism; the organelles harbour enzymes of several catabolic and anabolic routes, including major parts of the glycolytic and pentosephosphate pathways. The kinetoplastid mitochondrion is also unusual with regard to both its structural and functional properties. In this review, we describe the unique compartmentation of metabolism in Kinetoplastida and the metabolic properties resulting from this compartmentation. We discuss the evidence for our recently proposed hypothesis that a common ancestor of Kinetoplastida and Euglenida acquired a photosynthetic alga as an endosymbiont, contrary to the earlier notion that this event occurred at a later stage of evolution, in the Euglenida lineage alone. The endosymbiont was subsequently lost from the kinetoplastid lineage but, during that process, some of its pathways of energy and carbohydrate metabolism were sequestered in the kinetoplastid peroxisomes, which consequently became glycosomes. The evolution of the kinetoplastid glycosomes and the possible selective advantages of these organelles for Kinetoplastida are discussed. We propose that the possession of glycosomes provided metabolic flexibility that has been important for the organisms to adapt easily to changing environmental conditions. It is likely that metabolic flexibility has been an important selective advantage for many kinetoplastid species during their evolution into the highly successful parasites today found in many divergent taxonomic groups. Also addressed is the evolution of the kinetoplastid mitochondrion, from a supposedly pluripotent organelle, attributed to a single endosymbiotic event that resulted in all mitochondria and hydrogenosomes of extant eukaryotes. Furthermore, indications are presented that Kinetoplastida may have acquired other enzymes of energy and carbohydrate metabolism by various lateral gene transfer events different from those that involved the algal- and α-proteobacterial-like endosymbionts responsible for the respective formation of the glycosomes and mitochondria
Report of the interlaboratory comparison organized by the Community Reference Laboratory Food Contact Material: Plasticisers in Gaskets and Oil
The Institute for Health and Consumer Protection (IHCP) of the European Commission¿s Directorate-General Joint Research Centre hosts the Community Reference Laboratory for Food Contact Materials (CRL-FCM). One of its core tasks is to organize interlaboratory comparisons (ILCs) among appointed National Reference Laboratories (NRLs). This report presents the results of the first ILC of the CRL-FCM which focused on the determination of Plasticisers content in PVC Gasket and in Oil matrix.
The test materials used in this exercise were virgin gasket lids coming from industrial sources for the proficiency exercise part A. For the second part of the exercise an industrial source of sunflower oil was used and spiked with several plasticisers by the CRL-FCM.
There were 41 participants to whom samples were dispatched 34 of which submitted results for at least 1 analyte-material. 21 laboratories reported results for more than 10 analyte-material combination out of 14 required.
The homogeneity studies were performed by the CRL-FCM laboratory.
The assigned value and its uncertainty for part A, virgin gaskets, were obtained after applying the robust statistics to the results obtained from the participants. The assigned values for part B, oil samples, were those obtained based on formulation, from the gravimetric measurements used to spike the material. The uncertainty of the assigned values for oil samples was calculated combining the uncertainty of the spiking procedure with a contribution for the between-bottle homogeneity.
Participants were invited to report four replicates measurements. This was done by most of the participants.
Laboratory results were rated with z and z¿ scores in accordance with ISO 13528 [1] Standard deviations for proficiency assessment (also called target standard deviations) were set based on Horwitz equation for substances in the two oil samples. For the plasticisers in the two gasket samples the target standard deviation was set by the organizers to 15% in order to fulfil the required criteria for sufficient homogeneity of the sample within the lots.JRC.I.2-Chemical assessment and testin
Enolase: A Key Player in the Metabolism and a Probable Virulence Factor of Trypanosomatid Parasites—Perspectives for Its Use as a Therapeutic Target
Glycolysis and glyconeogenesis play crucial roles in the ATP supply and synthesis of glycoconjugates, important for the viability and virulence, respectively, of the human-pathogenic stages of Trypanosoma brucei, Trypanosoma cruzi, and Leishmania spp. These pathways are, therefore, candidate targets for antiparasite drugs. The glycolytic/gluconeogenic enzyme enolase is generally highly conserved, with similar overall fold and identical catalytic residues in all organisms. Nonetheless, potentially important differences exist between the trypanosomatid and host enzymes, with three unique, reactive residues close to the active site of the former that might be exploited for the development of new drugs. In addition, enolase is found both in the secretome and in association with the surface of Leishmania spp. where it probably functions as plasminogen receptor, playing a role in the parasite's invasiveness and virulence, a function possibly also present in the other trypanosomatids. This location and possible function of enolase offer additional perspectives for both drug discovery and vaccination
Effects of Oxygen During Long-term Hypothermic Machine Perfusion in a Porcine Model of Kidney Donation After Circulatory Death
International audienceBackground:Hypothermic machine perfusion (HMP) has become standard care in many center’s to preserve kidneys donated after circulatory death (DCD). Despite a significant reduction in metabolism at low temperatures, remaining cellular activity requires oxygen. Since the role and safety of oxygen during HMP has not been fully clarified, its supply during HMP is not standard yet. This study investigates the effect of administering oxygen during HMP on renal function in a porcine DCD model.Methods: After 30 minutes of warm ischemia, porcine slaughterhouse kidneys were preserved for 24 hours by means of cold storage (CS), or HMP with Belzer Machine Perfusion Solution (UW- MPS) supplemented with no oxygen, 21% or 100% oxygen. Next, kidneys were reperfused for 4 hours in a normothermic machine perfusion (NMP) setup.Results:HMP resulted in significantly better kidney function during NMP. Thiobarbituric acid-reactive substances (TBARS), markers of oxidative stress, were significantly lower in HMP preserved kidneys. HMP preserved kidneys showed significantly lower ASAT and LDH levels compared to kidneys preserved by CS. No differences were found between the HMP groups subjected to different oxygen concentrations. ATP levels significantly improved during HMP when active oxygenation was applied.Conclusion:This study showed that preservation of DCD kidneys with HMP is superior to CS. Although the addition of oxygen to HMP did not result in significantly improved renal function, beneficial effects were found in terms of reduced oxidative stress and energy status. Oxygen addition proofed to be safe and did not show detrimental effects
Impact of Red Blood Cells on Function and Metabolism of Porcine Deceased Donor Kidneys During Normothermic Machine Perfusion
Background. Normothermic machine perfusion (NMP) protocols using blood-based solutions are commonly used in the assessment of kidneys before transplantation. This procedure is, nevertheless, limited by blood availability and warrants the search for alternatives. We compared a blood-based solution with a serum-like preservation solution (Aqix) enriched with colloids with and without red blood cells (RBCs). Methods. Porcine kidneys retrieved from an abattoir were subjected to 30min of warm ischemia, followed by 3h of hypothermic oxygenated machine perfusion at 4 degrees C. Subsequently, kidneys (n=6 per group) were evaluated with NMP for 4h with 5 different solutions: diluted blood, Aqix with BSARBCs, or Aqix with dextran 40RBCs. Results. Throughout NMP, markers of renal function and tubular metabolism were favorable in groups with RBCs. The addition of RBCs resulted in 4- to 6-fold higher oxygen consumption rates. Controls had significantly higher ATP levels post-NMP, exhibited decreased production of oxidative stress markers, and had the highest creatinine clearance. In conclusion, this study shows that the addition of RBCs during NMP reduced renal injury, improved function, and was associated with increased renal metabolism. Conclusions. Although the RBC-BSA-supplemented Aqix solution was also able to support metabolism and renal function, a blood-based perfusion solution remains superior
SAPHIR - a multi-scale, multi-resolution modeling environment targeting blood pressure regulation and fluid homeostasis.
International audienceWe present progress on a comprehensive, modular, interactive modeling environment centered on overall regulation of blood pressure and body fluid homeostasis. We call the project SAPHIR, for "a Systems Approach for PHysiological Integration of Renal, cardiac, and respiratory functions". The project uses state-of-the-art multi-scale simulation methods. The basic core model will give succinct input-output (reduced-dimension) descriptions of all relevant organ systems and regulatory processes, and it will be modular, multi-resolution, and extensible, in the sense that detailed submodules of any process(es) can be "plugged-in" to the basic model in order to explore, eg. system-level implications of local perturbations. The goal is to keep the basic core model compact enough to insure fast execution time (in view of eventual use in the clinic) and yet to allow elaborate detailed modules of target tissues or organs in order to focus on the problem area while maintaining the system-level regulatory compensations
Controlled oxygenated rewarming up to normothermia for pretransplant reconditioning of liver grafts
Controlled oxygenated rewarming (COR) up to 20 degrees C during ex vivo machine perfusion limits reperfusion-induced tissue injury upon graft implantation. Rewarming up to normothermia might add further benefits and provide better prediction of post-transplantation organ function. The effect of 90 minutes of oxygenated machine perfusion with Aqix RS-I after cold storage combined with gentle rewarming up to 20 degrees C (COR20) or 35 degrees C (COR35) was studied in rat livers and compared with cold storage alone (CS, n = 6, resp). Postpreservation recovery was evaluated upon warm reperfusion using an established in vitro system. COR generally resulted in significantly improved energetic recovery, increased bile flow, less activities alanine aminotransferase (ALT) release, and improved histopathology upon reperfusion as compared to only cold-stored livers, without significant differences between COR20 and COR35. Parameters obtained during COR, especially during COR35, also allowed for prediction of hepatic recovery upon reperfusion. For instance, ulterior bile production upon reperfusion was found closely correlated to bile flow observed already during COR35 (R-2=0.91). COR significantly improved liver quality after static cold storage. Elevation of machine perfusion temperature up to 35 degrees C may prove promising to refine ex vivo evaluation of the graft prior to transplantation
- …