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Genetic engineering allows fine-tuning and controlling protein properties, thus exploiting the new derivatives to obtain novel materials and systems with improved capacity to actively interact with biological systems. The elastin-like polypeptides are tunable recombinant biopolymers that have proven to be ideal candidates for realizing bioactive interfaces that can interact with biological systems. They are characterized by a thermoresponsive behavior that is strictly related to their peculiar amino acid sequence. We describe here the rational design of a new biopolymer inspired by elastin and the comparison of its physicochemical properties with those of another already characterized member of the same protein class. To assess the cytocompatibility, the behavior of cells of different origins toward these components was evaluated. Our study shows that the biomimetic strategy adopted to design new elastin-based recombinant polypeptides represents a versatile and valuable tool for the development of protein-based materials with improved properties and advanced functionality.
Assuntos
Biomimética , Elastina , Elastina/química , Adesão Celular , Peptídeos/farmacologia , Peptídeos/química , Sequência de Aminoácidos , Biopolímeros/químicaRESUMO
Bilirubin is a toxicological biomarker for hemolysis and liver diseases. The current automated diazo method used in clinical chemistry has limited applicability in rodent models and cannot be used in small animals relevant to toxicology, microphysiological systems, cell cultures, and kinetic studies. Here, we present a versatile fluorometric method for nanoscale analysis of bilirubin based on its highly specific binding to the recombinant bifunctional protein HELP-UnaG (HUG). The assay is sensitive (LoQ = 1.1 nM), accurate (4.5% relative standard error), and remarkably robust, allowing analysis at pH 7.4-9.5, T = 25-37 °C, in various buffers, and in the presence of 0.4-4 mg × L-1 serum albumin or 30% DMSO. It allows repeated measurements of bilirubinemia in murine models and small animals, fostering the 3Rs principle. The assay determines bilirubin in human plasma with a relative standard error of 6.7% at values that correlate and agree with the standard diazo method. Furthermore, it detects differences in human bilirubinemia related to sex and UGT1A1 polymorphisms, thus demonstrating its suitability for the uniform assessment of bilirubin at the nanoscale in translational and precision medicine.
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Bilirrubina , Medicina de Precisão , Humanos , Camundongos , Animais , Bilirrubina/metabolismo , Cinética , Pesquisa Translacional Biomédica , Hiperbilirrubinemia , Proteínas RecombinantesRESUMO
The recombinant fusion protein HELP-UnaG (HUG) is a bifunctional product that exhibits human elastin-like polypeptide (HELP)-specific thermal behavior, defined as a reverse phase transition, and UnaG-specific bilirubin-dependent fluorescence emission. HUG provides an interesting model to understand how its two domains influence each other's properties. Turbidimetric, calorimetric, and light scattering measurements were used to determine different parameters for the reverse temperature transition and coacervation behavior. This shows that the UnaG domain has a measurable but limited effect on the thermal properties of HELP. Although the HELP domain decreased the affinity of UnaG for bilirubin, HUG retained the property of displacing bilirubin from bovine serum albumin and thus remains one of the strongest bilirubin-binding proteins known to date. These data demonstrate that HELP can be used to create new bifunctional fusion products that pave the way for expanded technological applications.
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Bilirrubina , Elastina , Elastina/química , Elastina/genética , Fluorescência , Humanos , Peptídeos/química , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genéticaRESUMO
The aim of this research work was to study the chemical characterisation, antioxidant and cytotoxic activity of ethanolic extracts of four commercial algae species Arame, Kombu, Hijiki and Wakame. The highest scavenging activity has been observed in Arame extract. Antioxidant potential of all extracts was in correlation with total phenol content (Arame extract: 319.15 ± 0.56 mg GAE/g d.w) and it was not in correlation with total carotenoids content (Wakame: 75.15 ± 0.20 mg/g). Polyphenols were quantified using LC-MS/MS technique. Baicalein and amentoflavone were identified in higher amount in relation to other phenols. Intracellular antioxidant activity and cytotoxicity of algae extracts were evaluated on the human prostate cancer cell line PC3. Although presented biomolecules in the extracts have demonstrated in vitro antioxidant activity, they did not show a significant effect on PC3 cells. However, this study opens up broad perspective for the further comprehensive investigation of these, commercial, seaweed's biopotential.
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Antioxidantes , Extratos Vegetais , Alga Marinha , Antioxidantes/farmacologia , Linhagem Celular Tumoral , Cromatografia Líquida , Humanos , Fenóis/análise , Fenóis/farmacologia , Extratos Vegetais/farmacologia , Espectrometria de Massas em TandemRESUMO
A new, bifunctional recombinant protein was expressed as the fusion product of human elastin-like polypeptide (HELP) and the bilirubin-binding protein UnaG. The engineered product displays both the HELP-specific property of forming a functional hydrogel matrix and the UnaG-specific capacity of emitting green fluorescence upon ligand binding. The new fusion protein has been proven to be effective at detecting bilirubin in complex environments with high background noise. A cell culture model of the stress response, consisting of bilirubin released in the cell culture medium, was set up to assess the bilirubin-sensing properties of the functional matrix obtained by cross-linking the HELP moiety. Our engineered protein allowed us to monitor cell induction by the release of bilirubin in the culture medium on a nanomolar scale. This study shows that elastin-like protein fusion represents a versatile platform for the development of novel and commercially viable analytical and biosensing devices.
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Bilirrubina/análise , Proteínas de Transporte/química , Elastina/química , Corantes Fluorescentes/química , Proteínas Recombinantes de Fusão/química , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Linhagem Celular , Elastina/genética , Elastina/metabolismo , Corantes Fluorescentes/análise , Corantes Fluorescentes/metabolismo , Heme Oxigenase (Desciclizante)/metabolismo , Humanos , Engenharia de Proteínas/métodos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
Anthocyanins are water-soluble pigments providing certain color for various plant parts, especially in edible berries. Earlier these compounds were only known as natural food colorants, the stability of which depended on pH, light, storage temperature and chemical structure. However, due to the increase of the in vitro, in vivo experimental data, as well as of the epidemiological studies, today anthocyanins and their metabolites are also regarded as potential pharmaceutical compounds providing various beneficial health effects on either human or animal cardiovascular system, brain, liver, pancreas and kidney. Many of these effects are shown to be related to the free-radical scavenging and antioxidant properties of anthocyanins, or to their ability to modulate the intracellular antioxidant systems. However, it is generally overlooked that instead of acting exclusively as antioxidants certain anthocyanins affect the activity of mitochondria that are the main source of energy in cells. Therefore, the aim of the present review is to summarize the major knowledge about the chemistry and regulation of biosynthesis of anthocyanins in plants, to overview the facts on bioavailability, and to discuss the most recent experimental findings related to the beneficial health effects emphasizing mitochondria.
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Antocianinas , Frutas , Animais , Antioxidantes/farmacologia , Humanos , Mitocôndrias , PigmentaçãoRESUMO
In the present study, an antibody raised against a peptide sequence of rat bilitranslocase (anti-peptide Ab) was tested on microsomal proteins obtained from red grape berry skin. Previously, this antibody had demonstrated to recognize plant membrane proteins associated with flavonoid binding and transport. Immuno-proteomic assays identified a number of proteins reacting with this particular antibody, suggesting that the flavonoid binding and interaction may be extended not only to carriers of these molecules, but also to enzymes with very different functions. One of these proteins is a pathogenesis-related (PR) class IV chitinase, whose in vitro chitinolytic activity was modulated by two of the most representative flavonoids of grape, quercetin and catechin, as assessed by both spectrophotometric and fluorimetric assays in grape microsomes and commercial enzyme preparations. The effect of these flavonoids on the catalysis and its kinetic parameters was also evaluated, evidencing that they determine a hormetic dose-dependent response. These results highlight the importance of flavonoids not only as antioxidants or antimicrobial effectors, but also as modulators of plant growth and stress response. Implications of the present suggestion are here discussed in the light of environment and pesticide-reduction concerns.
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Putative pea bilin and cyclic tetrapyrrole transporter proteins were identified by means of an antibody raised against a bilirubin-interacting aminoacidic sequence of mammalian bilitranslocase (TC No. 2.A.65.1.1). The immunochemical approach showed the presence of several proteins mostly in leaf microsomal, chloroplast and tonoplast vesicles. In these membrane fractions, electrogenic bromosulfalein transport activity was also monitored, being specifically inhibited by anti-bilitranslocase sequence antibody. Moreover, the inhibition of transport activity in pea leaf chloroplast vesicles, by both the synthetic cyclic tetrapyrrole chlorophyllin and the heme catabolite biliverdin, supports the involvement of some of these proteins in the transport of linear/cyclic tetrapyrroles during chlorophyll metabolism. Immunochemical localization in chloroplast sub-compartments revealed that these putative bilitranslocase-like transporters are restricted to the thylakoids only, suggesting their preferential implication in the uptake of cyclic tetrapyrrolic intermediates from the stroma during chlorophyll biosynthesis. Finally, the presence of a conserved bilin-binding sequence in different proteins (enzymes and transporters) from divergent species is discussed in an evolutionary context.
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Clorofila/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Pisum sativum/metabolismo , Animais , Transporte Biológico Ativo , CeruloplasminaRESUMO
Diabetes mellitus (DM) is associated with brain alterations that may contribute to cognitive dysfunctions. Chlorogenic acid (CGA) and caffeine (CA), abundant in coffee (CF), are natural compounds that have showed important actions in the brain. The present study aimed to evaluate the effect of CGA, CA, and CF on acetylcholinesterase (AChE), Na(+), K(+)-ATPase, aminolevulinate dehydratase (δ-ALA-D) activities and TBARS levels from cerebral cortex, as well as memory and anxiety in streptozotocin-induced diabetic rats. Animals were divided into eight groups (n = 5-10): control; control/CGA 5 mg/kg; control/CA 15 mg/kg; control/CF 0.5 g/kg; diabetic; diabetic/CGA 5 mg/kg; diabetic/CA 15 mg/kg; and diabetic/CF 0.5 g/kg. Our results demonstrated an increase in AChE activity and TBARS levels in cerebral cortex, while δ-ALA-D and Na(+), K(+)-ATPase activities were decreased in the diabetic rats when compared to control water group. Furthermore, a memory deficit and an increase in anxiety in diabetic rats were observed. The treatment with CGA and CA prevented the increase in AChE activity in diabetic rats when compared to the diabetic water group. CGA, CA, and CF intake partially prevented cerebral δ-ALA-D and Na(+), K(+)-ATPase activity decrease due to diabetes. Moreover, CGA prevented diabetes-induced TBARS production, improved memory, and decreased anxiety. In conclusion, among the compounds studied CGA proved to be a compound which acts better in the prevention of brain disorders promoted by DM.
Assuntos
Comportamento Animal/efeitos dos fármacos , Cafeína/farmacologia , Ácido Clorogênico/farmacologia , Café , Diabetes Mellitus Experimental/tratamento farmacológico , Acetilcolinesterase/biossíntese , Animais , Ansiedade/tratamento farmacológico , Peso Corporal/efeitos dos fármacos , Córtex Cerebral/metabolismo , Masculino , Memória/efeitos dos fármacos , Transtornos da Memória/tratamento farmacológico , Sintase do Porfobilinogênio/biossíntese , Ratos , Ratos Wistar , ATPase Trocadora de Sódio-Potássio/biossíntese , Estreptozocina , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
Circulating metabolites resulting from colonic metabolism of dietary (poly)phenols are highly abundant in the bloodstream, though still marginally explored, particularly concerning their brain accessibility. Our goal is to disclose (poly)phenol metabolites' blood-brain barrier (BBB) transport, in vivo and in vitro, as well as their role at BBB level. For three selected metabolites, benzene-1,2-diol-3-sulfate/benzene-1,3-diol-2-sulfate (pyrogallol-sulfate - Pyr-sulf), benzene-1,3-diol-6-sulfate (phloroglucinol-sulfate - Phlo-sulf), and phenol-3-sulfate (resorcinol-sulfate - Res-sulf), BBB transport was assessed in human brain microvascular endothelial cells (HBMEC). Their potential in modulating in vitro BBB properties at circulating concentrations was also studied. Metabolites' fate towards the brain, liver, kidney, urine, and blood was disclosed in Wistar rats upon injection. Transport kinetics in HBMEC highlighted different BBB permeability rates, where Pyr-sulf emerged as the most in vitro BBB permeable metabolite. Pyr-sulf was also the most potent regarding BBB properties improvement, namely increased beta(ß)-catenin membrane expression and reduction of zonula occludens-1 membrane gaps. Whereas no differences were observed for transferrin, increased expression of caveolin-1 upon Pyr-sulf and Res-sulf treatments was found. Pyr-sulf was also capable of modulating gene and protein expression of some solute carrier transporters. Notably, each of the injected metabolites exhibited a unique tissue distribution in vivo, with the remarkable ability to almost immediately reach the brain.
Assuntos
Barreira Hematoencefálica , Encéfalo , Células Endoteliais , Ratos Wistar , Barreira Hematoencefálica/metabolismo , Animais , Humanos , Ratos , Encéfalo/metabolismo , Masculino , Células Endoteliais/metabolismo , Transporte Biológico , Polifenóis/metabolismo , Peso MolecularRESUMO
Uveal melanoma (UM) is an ocular cancer, with propensity for lethal liver metastases. When metastatic UM (MUM) occurs, as few as 8% of patients survive beyond two years. Efficacious treatments for MUM are urgently needed. 1,4-dihydroxy quininib, a cysteinyl leukotriene receptor 1 (CysLT1) antagonist, alters UM cancer hallmarks in vitro, ex vivo and in vivo. Here, we investigated the 1,4-dihydroxy quininib mechanism of action and its translational potential in MUM. Proteomic profiling of OMM2.5 cells identified proteins differentially expressed after 1,4-dihydroxy quininib treatment. Glutathione peroxidase 4 (GPX4), glutamate-cysteine ligase modifier subunit (GCLM), heme oxygenase 1 (HO-1) and 4 hydroxynonenal (4-HNE) expression were assessed by immunoblots. Biliverdin, glutathione and lipid hydroperoxide were measured biochemically. Association between the expression of a specific ferroptosis signature and UM patient survival was performed using public databases. Our data revealed that 1,4-dihydroxy quininib modulates the expression of ferroptosis markers in OMM2.5 cells. Biochemical assays validated that GPX4, biliverdin, GCLM, glutathione and lipid hydroperoxide were significantly altered. HO-1 and 4-HNE levels were significantly increased in MUM tumor explants from orthotopic patient-derived xenografts (OPDX). Expression of genes inhibiting ferroptosis is significantly increased in UM patients with chromosome 3 monosomy. We identified IFerr, a novel ferroptosis signature correlating with UM patient survival. Altogether, we demontrated that in MUM cells and tissues, 1,4-dihydroxy quininib modulates key markers that induce ferroptosis, a relatively new type of cell death driven by iron-dependent peroxidation of phospholipids. Furthermore, we showed that high expression of specific genes inhibiting ferroptosis is associated with a worse UM prognosis, thus, the IFerr signature is a potential prognosticator for which patients develop MUM. All in all, ferroptosis has potential as a clinical biomarker and therapeutic target for MUM.
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Guar gum (E 412) was re-evaluated in 2017 by the former EFSA Panel on Food Additives and Nutrient sources added to Food (ANS). As a follow-up to this assessment, the Panel on Food Additives and Flavourings (FAF) was requested to assess the safety of guar gum (E 412) for its uses as food additive in food for infants below 16 weeks of age belonging to food categories 13.1.1 (Infant formulae) and 13.1.5.1 (Dietary foods for infants for special medical purposes and special formulae for infants). In addition, the FAF Panel was requested to address the issues already identified during the re-evaluation of the food additive when used in food for the general population. The process involved the publication of a call for data to allow the interested business operators to provide the requested information to complete the risk assessment. In the response to EFSA requests, one IBO stated that E 412 is not used in food categories 13.1.1 and 13.1.5.1, but it is present in products under food category 13.1.5.2. The Panel concluded that the submitted data are not sufficient to support the safe use of guar gum (E 412) in food for infants (below and above 16 weeks of age) and young children under FC 13.1.1, 13.1.5.1 and 13.1.5.2. Additionally, the Panel concluded that the technical data provided by the IBO support further amendments of the specifications for E 412 laid down in Commission Regulation (EU) No 231/2012.
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The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of 2-methyl-1-(2-(5-(p-tolyl)-1H-imidazol-2-yl)piperidin-1-yl)butan-1-one [FL-no: 16.134] as a new flavouring substance, in accordance with Regulation (EC) No 1331/2008. The substance has not been reported to occur naturally and is chemically synthesised. In food, it is intended to be used as a flavouring substance only in chewing gum. The chronic dietary exposure to [FL-no: 16.134] was estimated to be 45 µg/person per day for a 60-kg adult and 28.4 µg/person per day for a 15-kg 3-year-old child. [FL-no: 16.134] did not show genotoxicity in a bacterial reverse mutation test and an in vitro mammalian cell micronucleus assay. Based on the submitted toxicokinetic and metabolism data, it can be predicted that the flavouring substance is metabolised to innocuous products only. The Panel derived a lower confidence limit of the benchmark dose (BMDL) of 0.71 mg/kg bw per day for a 20% increase in the relative thyroid (including parathyroid) weight observed in a 90-day toxicity study in rats. Based on this BMDL, adequate margins of exposure of 887 and 374 could be calculated for adults and children, respectively. The Panel concluded that there is no safety concern for [FL-no: 16.134], when used as a flavouring substance at the estimated level of dietary exposure, based on the intended use and use levels as specified in Appendix B. The Panel further concluded that the combined exposure to [FL-no: 16.134] from its use as a food flavouring substance and from its presence in toothpaste and mouthwash is also not of safety concern.
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The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of naringenin [FL-no: 16.132] as a new flavouring substance, in accordance with Regulation (EC) No 1331/2008. No other substances with sufficient structural similarity have been identified in existing FGEs that could be used to support a read-across approach. The information provided on the manufacturing process, the composition and the stability of [FL-no: 16.132] was considered sufficient. From studies carried out with naringenin, the Panel concluded that there is no concern with respect to genotoxicity. The use of naringenin as a flavouring substance at added portions exposure technique (APET) exposure levels is unlikely to pose a risk for drug interaction. For the toxicological evaluation of naringenin, the Panel requested an extended one-generation toxicity study on naringenin, in line with the requirements of the Procedure and to investigate the consequence of a possible endocrine-disrupting activity. The Panel considered that changes in thymus weight, litter size, post-implantation loss and a consistent reduced pup weight in the high-dose F2 generation could not be dismissed and selected therefore, the mid-dose of 1320 mg/kg body weight (bw) per day for the parental males as the no observed adverse effect level (NOAEL) of the study. The exposure estimates for [FL-no: 16.132] (31,500 and 50,000 µg/person per day for children and adults, respectively) were above the threshold of toxicological of concern (TTC) for its structural class (III). Using the NOAEL of 1320 mg/kg bw per day at step A4 of the procedure, margins of exposure (MoE) of 1590 and 630 could be calculated for adults and children, respectively. Based on the calculated MoEs, the Panel concluded that the use of naringenin as a flavouring substance does not raise a safety concern.
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Quillaia extract (E 999) was re-evaluated in 2019 by the EFSA Panel on Food Additives and Flavourings (FAF). EFSA derived an acceptable daily intake (ADI) of 3 mg saponins/kg bw per day for E 999. Following a European Commission call for data to submit data to fill the data gaps, the present follow-up opinion assesses data provided by interested business operators (IBOs) to support an amendment of the EU specifications for E 999. Additionally, this opinion deals with the assessment of the proposed extension of use for E 999 in food supplements supplied in a solid and liquid form, excluding food supplements for infants and young children and, as a carrier in botanical nutrients. The Panel concluded that the proposed extension of use, if authorised, could result in an exceedance of the ADI at the maximum of the ranges of the mean for children, adolescents and the elderly, and for all populations at the 95th percentile. An additional proposed extension of use for E 999 to be used as a carrier for glazing agents on entire fresh fruits and vegetables has been received. Since no information on the proposed use levels of E 999 on a saponins content basis has been provided by this applicant, the Panel was not able to evaluate the safety of this extension of use. Considering the technical data submitted, the Panel recommended some modifications of the existing EU specifications for E 999, mainly to lower the limits for lead, mercury and arsenic and to include a maximum limit for cadmium and for calcium oxalate. The Panel also recommended that the limits would be expressed on a saponins basis. The Panel proposed to revise the definition of E 999 to better describe the composition in a qualitative way.
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The EFSA Panel on Food Additive and Flavourings (FAF Panel) provides a scientific opinion on the safety of soy leghemoglobin from genetically modified Komagataella phaffii as a food additive in accordance with Regulation (EC) No 1331/2008. The proposed food additive, LegH Prep, is intended to be used as a colour in meat analogue products. The yeast Komagataella phaffii strain MXY0541 has been genetically modified to produce soy leghemoglobin; the safety of the genetic modification is under assessment by the EFSA GMO Panel (EFSA-GMO-NL-2019-162). The amount of haem iron provided by soy leghemoglobin from its proposed uses in meat analogue products is comparable to that provided by similar amounts of different types of meat. The exposure to iron from the proposed food additive, both at the mean and 95th percentile exposure, will be below the 'safe levels of intake' established by the NDA Panel for all population groups. Considering that the components of the proposed food additive will be digested to small peptide, amino acids and haem B; the recipient (non GM) strain qualifies for qualified presumption of safety status; no genotoxicity concern has been identified and no adverse effects have been identified at the highest dose tested in the available toxicological studies, the Panel concluded that there was no need to set a numerical acceptable daily intake (ADI) and that the food additive does not raise a safety concern at the proposed use in food category 12.9 and maximum use level. The Panel concluded that the use of soy leghemoglobin from genetically modified Komagataella phaffii MXY0541 as a new food additive does not raise a safety concern at the proposed use and use level. This safety evaluation of the proposed food additive remains provisional subject to the ongoing safety assessment of the genetic modification of the production strain by the GMO Panel (EFSA-GMO-NL-2019-162).
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The EFSA Panel on Food Additives and Flavourings was requested to evaluate 14 flavouring substances assigned to the Flavouring Group Evaluation 80 (FGE.80), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Thirteen substances have already been considered in FGE.80 and its revision and in FGE.96 [FL-no: 10.005, 10.024, 10.025, 10.050, 10.061, 10.069, 10.070, 10.072, 10.169, 13.009, 13.012, 13.161 and 16.055]. The remaining flavouring substance 3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3H)-one [FL-no: 10.057] has been cleared with respect to genotoxicity in FGE.217Rev3 and it is considered in this revision 2 of FGE.80. The substance [FL-no: 10.057] was evaluated through a stepwise approach that integrates information on the structure-activity relationships, intake from current uses, threshold of toxicological concern (TTC) and available data on metabolism and toxicity. The Panel concluded that [FL-no: 10.057] does not give rise to safety concerns at its levels of dietary intake, when estimated on the basis of the 'Maximised Survey-derived Daily Intake' (MSDI) approach. Besides the safety assessment of the flavouring substance, the specifications for the material of commerce have also been considered and the information provided was complete for [FL-no: 10.057]. However, for the flavouring substance [FL-no: 10.057] in the present revision and for eight substances evaluated in previous revisions, the 'modified Theoretical Added Maximum Daily Intakes' (mTAMDIs) values are above the TTC for their structural class (III). For four substances previously evaluated in FGE.80Rev1 and in FGE.96, use levels are still needed to calculate the mTAMDI estimates. Therefore, in total for 13 flavouring substances, data on uses and use levels should be provided to finalise their safety evaluations. For [FL-no: 10.050, 10.069 and 13.161], information on the composition of stereoisomeric mixtures is needed.
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The present opinion deals with the re-evaluation of shellac (E 904) when used as a food additive and with the new application on the extension of use of shellac (E 904) in dietary foods for special medical purposes. The Panel derived an acceptable daily intake (ADI) of 4 mg/kg body weight (bw) per day for wax-free shellac (E 904) produced by physical decolouring, based on a NOAEL of 400 mg/kg bw per day and applying an uncertainty factor of 100. The Panel concluded that the ADI of 4 mg/kg bw per day should be considered temporary for wax-free shellac (E 904) produced by chemical bleaching, while new data are generated on the identity and levels of the organochlorine impurities in E 904. This ADI is not applicable for wax-containing shellac as a food additive. For several age groups, the ADI was exceeded at the 95th percentile in the non-brand-loyal exposure assessment scenario and maximum level exposure assessment scenario. Considering the low exceedance and the fact that both the exposure estimation and the toxicological evaluation of shellac were conservative, the panel concluded that the calculated exceedance of the ADI does not indicate a safety concern. The Panel recommended to the European Commission separating specifications for E 904 depending on the manufacturing process, chemical bleaching and physical decolouring, because they result in different impurities; revising the definition of the food additive to include a description of each manufacturing process; deleting information on wax-containing shellac from the EU specifications; revising the acid value for wax-free shellac produced by chemical bleaching; lowering the maximum limit for lead; to consider introducing limits for other toxic elements potentially present in shellac; including a maximum limit for chloroform and total inorganic chloride in the EU specification for shellac produced by chemical bleaching.
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The mitochondrial permeability transition (PT) is a well-recognized phenomenon that allows mitochondria to undergo a sudden increase of permeability to solutes with molecular mass ≤ 1500Da, leading to organelle swelling and structural modifications. The relevance of PT relies on its master role in the manifestation of programmed cell death (PCD). This function is performed by a mega-channel (in some cases inhibited by cyclosporin A) named permeability transition pore (PTP), whose function could derive from the assembly of different mitochondrial proteins. In this paper we examine the distribution and characteristics of PTP in mitochondria of eukaryotic organisms so far investigated in order to draw a hypothesis on the mechanism of its evolution. As a result, we suggest that PTP may have arisen as a new function linked to a multiple molecular exaptation of different mitochondrial proteins, even though they could nevertheless still play their original role. Furthermore, we suggest that the early appearance of PTP could have had a crucial role in the establishment of endosymbiosis in eukaryotic cells, by the coordinated balancing of ATP production by glycolysis (performed by the primary phagocyte) and oxidative phosphorylation (accomplished by the endosymbiont). Indeed, we argue on the possibility that this new energetic equilibrium could have opened the way to the subsequent evolution toward metazoans.
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Proteínas de Transporte da Membrana Mitocondrial/fisiologia , Animais , Cálcio/metabolismo , Evolução Molecular , Humanos , Proteínas de Transporte da Membrana Mitocondrial/genética , Poro de Transição de Permeabilidade Mitocondrial , Filogenia , Canais de Potássio/fisiologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
BACKGROUND: Bilitranslocase (TC 2.A.65.1.1) is a bilirubin-specific membrane transporter, found on absorptive (stomach and intestine) and excretory (kidney and liver) epithelia and in vascular endothelium. Polyclonal antibodies have been raised in rabbits in the past, using a synthetic peptide corresponding to AA65-77 of rat liver bilitranslocase, as an antigen. Affinity-purified antibodies from immune sera have been found to inhibit various membrane transport functions, including the bilirubin uptake into human hepatocytes and the uptake of some flavonoids into human vascular endothelial cells. It was described by means of immunohistochemistry using polyclonal antibodies that bilitranslocase expression is severely down-regulated in clear cell renal carcinoma. The aim of our work was development and characterization of high-affinity, specific mAbs against bilitranslocase, which can be used as a potential diagnostic tool in renal cell carcinoma as well as in a wide variety of biological assays on different human tissues. MATERIALS AND METHODS: Mice were immunized with a multi-antigen peptide corresponding to segment 65-75 of predicted primary structure of the bilitranslocase protein. By a sequence of cloning, immune- and functional tests, we aimed at obtaining a specific monoclonal antibody which recognizes a 37 kDa membrane protein, and influences the transport activity of bilitranslocase. RESULTS: On the basis of previous results, specific IgM monoclonal antibodies were produced in BALB/c mice, in order to further improve and extend the immunological approach to the study of bilitranslocase in renal cancer cells as well as to develop its potential diagnostics use. CONCLUSIONS: In this article we show an immunological approach, based on newly developed monoclonal antibodies, to a detailed biochemical and functional characterization of a protein whose gene and protein structure is still unknown. We were able to demonstrate our novel mAb as a tumor marker candidate of renal cell carcinoma, which may prove useful in the diagnostic procedures.