Academic literature on the topic 'Peptides – Effets du fer'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Peptides – Effets du fer.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Peptides – Effets du fer"
1
Arregui, Carlos, Purnima Pathre, Jack Lilien, and Janne Balsamo. "The Nonreceptor Tyrosine Kinase Fer Mediates Cross-Talk between N-Cadherin and β1-Integrins." Journal of Cell Biology 149, no. 6 (June 12, 2000): 1263–74. http://dx.doi.org/10.1083/jcb.149.6.1263.
Full textAbstract:
Cadherins and integrins must function in a coordinated manner to effectively mediate the cellular interactions essential for development. We hypothesized that exchange of proteins associated with their cytoplasmic domains may play a role in coordinating function. To test this idea, we used Trojan peptides to introduce into cells and tissues peptide sequences designed to compete for the interaction of specific effectors with the cytoplasmic domain of N-cadherin, and assayed their effect on cadherin- and integrin-mediated adhesion and neurite outgrowth. We show that a peptide mimicking the juxtamembrane (JMP) region of the cytoplasmic domain of N-cadherin results in inhibition of N-cadherin and β1-integrin function. The effect of JMP on β1-integrin function depends on the expression of N-cadherin and is independent of transcription or translation. Treatment of cells with JMP results in the release of the nonreceptor tyrosine kinase Fer from the cadherin complex and its accumulation in the integrin complex. A peptide that mimics the first coiled-coil domain of Fer prevents Fer accumulation in the integrin complex and reverses the inhibitory effect of JMP. These findings suggest a new mechanism through which N-cadherin and β1-integrins are coordinately regulated: loss of an effector from the cytoplasmic domain of N-cadherin and gain of that effector by the β1-integrin complex.
2
Ribeill, Georges. "Gestion et organisation du travail dans les compagnies de chemins de fer, des origines a 1860." Annales. Histoire, Sciences Sociales 42, no. 5 (October 1987): 999–1029. http://dx.doi.org/10.3406/ahess.1987.283434.
Full textAbstract:
L'importance de l'avènement des chemins de fer dans l'économie française est bien connue : son rôle décisif pour promouvoir ou susciter de multiples innovations depuis les questions de mobilisation financière jusqu'à celles de la politique de l'Etat en matière de service public, depuis ses effets sur les industries amont (du rail au combustible) ou les marchés aval des productions agricoles et industrielles, jusqu'à des effets structurants de géographie humaine, ont été plus ou moins fouillés. En particulier, depuis longtemps, de nombreux travaux ont été consacrés aux débats et tournants successifs de la politique publique des chemins de fer.
3
Ahrén, Bo. "Regulatory peptides in the thyroid gland — a review on their localization and function." Acta Endocrinologica 124, no. 3 (March 1991): 225–32. http://dx.doi.org/10.1530/acta.0.1240225.
Full textAbstract:
Abstract. It has been demonstrated that nerve fibres storing immunoreactivity of vasoactive intestinal polypeptide, peptide histidine iso-leucine, neuropeptide Y, substance P, calcitonin gene-related peptide, galanin, and cholecystokinin exists in the thyroid, though the content of these neuropeptides is lower in the thyroid than in other organs, like in the gut. Furthermore, the parafollicular C-cells have been shown to harbour several different peptides: calcitonin, somatostatin, calcitonin gene-related peptide, gastrin-releasing peptide, katacalcin and helodermin. In addition, other regulatory peptides like atrial natriuretic hormone, growth factors, and cytokines are also produced in the thyroid. This review summarizes today's knowledge on the effects of these peptides on thyroid hormone secretion and their possible role in thyroid physiology. So far, functional studies have failed to establish any convincing effect of substance P, calcitonin gene-related peptide, galanin and cholecystokinin on basal or TSH-stimulated thyroid hormone secretion. In contrast, vasoactive intestinal peptide has convincingly been demonstrated to stimulate thyroid hormone secretion, and neuropeptide Y to potentiate the inhibitory action of noradrenaline on TSH-induced thyroid hormone secretion. This suggests that these two neuropeptides are involved in the intrathyroidal neural regulation of thyroid function. Moreover, the C-cell peptides somatostatin, calcitonin, calcitonin gene-related peptide, and katacalcin seem to be involved as inhibitors of thyroid hormone secretion, whereas both gastrin-releasing peptide and helodermin stimulate thyroid hormone secretion. Atrial natriuretic hormone and growth factors, and cytokines seem to inhibit thyroid hormone secretion. Hence, studies undertaken so far suggest a local intrathyroidal peptidergic regulatory concept, the exact role of which remains to be established.
4
Casciaro, Bruno, Floriana Cappiello, Maria Rosa Loffredo, Francesca Ghirga, and Maria Luisa Mangoni. "The Potential of Frog Skin Peptides for Anti-Infective Therapies: The Case of Esculentin-1a(1-21)NH2." Current Medicinal Chemistry 27, no. 9 (March 27, 2020): 1405–19. http://dx.doi.org/10.2174/0929867326666190722095408.
Full textAbstract:
Antimicrobial Peptides (AMPs) are the key effectors of the innate immunity and represent promising molecules for the development of new antibacterial drugs. However, to achieve this goal, some problems need to be overcome: (i) the cytotoxic effects at high concentrations; (ii) the poor biostability and (iii) the difficulty in reaching the target site. Frog skin is one of the richest natural storehouses of AMPs, and over the years, many peptides have been isolated from it, characterized and classified into several families encompassing temporins, brevinins, nigrocins and esculentins. In this review, we summarized how the isolation/characterization of peptides belonging to the esculentin-1 family drove us to the design of an analogue, i.e. esculentin-1a(1-21)NH2, with a powerful antimicrobial action and immunomodulatory properties. The peptide had a wide spectrum of activity, especially against the opportunistic Gram-negative bacterium Pseudomonas aeruginosa. We described the structural features and the in vitro/in vivo biological characterization of this peptide as well as the strategies used to improve its biological properties. Among them: (i) the design of a diastereomer carrying Damino acids in order to reduce the peptide’s cytotoxicity and improve its half-life; (ii) the covalent conjugation of the peptide to gold nanoparticles or its encapsulation into poly(lactide- co-glycolide) nanoparticles; and (iii) the peptide immobilization to biomedical devices (such as silicon hydrogel contact lenses) to obtain an antibacterial surface able to reduce microbial growth and attachment. Summing up the best results obtained so far, this review traces all the steps that led these frog-skin AMPs to the direction of peptide-based drugs for clinical use.
5
Zhao, Chunzhao, Omar Zayed, Zheping Yu, Wei Jiang, Peipei Zhu, Chuan-Chih Hsu, Lingrui Zhang, W. Andy Tao, Rosa Lozano-Durán, and Jian-Kang Zhu. "Leucine-rich repeat extensin proteins regulate plant salt tolerance in Arabidopsis." Proceedings of the National Academy of Sciences 115, no. 51 (December 4, 2018): 13123–28. http://dx.doi.org/10.1073/pnas.1816991115.
Full textAbstract:
The perception and relay of cell-wall signals are critical for plants to regulate growth and stress responses, but the underlying mechanisms are poorly understood. We found that the cell-wall leucine-rich repeat extensins (LRX) 3/4/5 are critical for plant salt tolerance in Arabidopsis. The LRXs physically associate with the RAPID ALKALINIZATION FACTOR (RALF) peptides RALF22/23, which in turn interact with the plasma membrane-localized receptor-like protein kinase FERONIA (FER). The lrx345 triple mutant as well as fer mutant plants display retarded growth and salt hypersensitivity, which are mimicked by overexpression of RALF22/23. Salt stress promotes S1P protease-dependent release of mature RALF22 peptides. Treatment of roots with mature RALF22/23 peptides or salt stress causes the internalization of FER. Our results suggest that the LRXs, RALFs, and FER function as a module to transduce cell-wall signals to regulate plant growth and salt stress tolerance.
6
Mendez, Rufa, and Jung Kwon. "Pacific Dulse Protein: A Promising Source of Bioactive Peptides." Current Developments in Nutrition 5, Supplement_2 (June 2021): 597. http://dx.doi.org/10.1093/cdn/nzab044_028.
Full textAbstract:
Abstract Objectives Pacific dulse (Devaleraea mollis) is a protein-rich seaweed in the Pacific Northwest and increasingly being cultivated as food resource. Our previous work showed that dietary supplementation of dulse exerted beneficial metabolic effects to the high-fat fed mouse model. This study aims to evaluate the potential of the seaweed protein from dulse as a precursor for bioactive peptide (BAP) generation. Methods The potential of Pacific dulse protein as BAP precursor was assessed using in vitro and in silico approaches. Hydrolysates were prepared from the hydrated freeze-dried protein isolates which were digested using commercial proteases. These were used for the in vitro screening for antioxidant and anti-inflammatory activities as well as the inhibition of Angiotensin-converting enzyme 1 (ACE-1), Renin, and Dipeptidyl peptidase IV (DPPIV). Peptides in the hydrolysates that exhibit the highest activities were identified using de novo sequencing. Identified peptides were shortlisted based on their potential to be bioactive using Peptide Ranker and specific bioactivity scores were obtained using in silico platforms such as iDPPIV-SCM and PreAIP. To determine whether the consumption of the seaweed protein may help give rise to some bioactive peptides, annotated protein sequences of the seaweed material were obtained from UniProtKB and were subjected to in silico digestion using pepsin, chymotrypsin, and trypsin through BIOPEP. Bioactivity indices of the generated peptide fragments were recorded as predictive values. Results In silico digestion showed that dulse proteins can give rise to ACE-1, DPP-IV, and renin inhibitors, as well as antioxidant peptides. Hydrolysates exerted inhibitory effects on human ACE-1, DPPIV, and renin in vitro. ABTS radical scavenging assay and cellular antioxidant activity assay in human hepatocytes indicated the strong antioxidant potential of dulse BAP. Peptides identified through de novo sequencing had high predictive scores for DDPIV inhibition and anti-inflammatory potential. Conclusions Pacific dulse proteins is a promising precursor for the generation of BAPs that may exert beneficial health activities and support metabolic health improvement. Funding Sources Oregon State University Agricultural Research Foundation.
7
Fairlie, David P., Giovanni Abbenante, and Darren R. March. "Macrocyclic Peptidomimetics Forcing Peptides into Bioactive Conformations." Current Medicinal Chemistry 2, no. 2 (August 1995): 654–86. http://dx.doi.org/10.2174/0929867302666220218001506.
Full textAbstract:
Abstract: Cyclic peptides that are potent regulators of biological processes are rapidly emerging as important mechanistic probes and drug leads. Nature clearly uses macrocycles to. constrain peptides into conformations that can selectively bind proteins or. small molecules. Therapeutic effects of such macrocycles, often containing additional conformational constraints that fine tune structure (e.g. D-amino acids, N-methyl substituents, aromatic rings, to name a few), have so far been mainly discovered by accident. However it is now becoming possible to rationally design synthetic macrocycles to selectively recognize and inhibit a specific protein. A receptor-binding struc ture is more easily adopted by macrocyclic peptidomimetics than more flexible acyclic peptides because the former have less conformational entropy. Macrocycles are often stable to hydrolysis by peptidases that degrade acyclic peptides and hydrophobic side chains can protect peptide bonds in macrocycles from hydrolysis, as well as enhance lipophilicity, cell permeability and bioavailability. Synthetic efforts to obtain bioactive conformations of short peptides have so far been substrate-based, guided by molecular modelling predictions and structure-activity data for modified amino acid sequences of substrates. However, dramatic advances in molecular biology, X-ray crystallography, NMR spectroscopy and computing are rapidly producing three dimensional structures of proteins, promising direct observation of protein-bound conformations of small molecules and receptor-based design of peptidomimetics with surface complementarity for proteins. This perspective review highlights examples of both natural and synthetic bioactive macrocyclic peptides containing constraints that fix conformation, and briefly illustrates the promise that receptor-based design holds for structural and functional mimicry of peptides by macrocycles.
8
Zheng, Zihao, Aisha M. Mergaert, Irene M. Ong, Miriam A. Shelef, and Michael A. Newton. "MixTwice: large-scale hypothesis testing for peptide arrays by variance mixing." Bioinformatics 37, no. 17 (March 8, 2021): 2637–43. http://dx.doi.org/10.1093/bioinformatics/btab162.
Full textAbstract:
Abstract Summary Peptide microarrays have emerged as a powerful technology in immunoproteomics as they provide a tool to measure the abundance of different antibodies in patient serum samples. The high dimensionality and small sample size of many experiments challenge conventional statistical approaches, including those aiming to control the false discovery rate (FDR). Motivated by limitations in reproducibility and power of current methods, we advance an empirical Bayesian tool that computes local FDR statistics and local false sign rate statistics when provided with data on estimated effects and estimated standard errors from all the measured peptides. As the name suggests, the MixTwice tool involves the estimation of two mixing distributions, one on underlying effects and one on underlying variance parameters. Constrained optimization techniques provide for model fitting of mixing distributions under weak shape constraints (unimodality of the effect distribution). Numerical experiments show that MixTwice can accurately estimate generative parameters and powerfully identify non-null peptides. In a peptide array study of rheumatoid arthritis, MixTwice recovers meaningful peptide markers in one case where the signal is weak, and has strong reproducibility properties in one case where the signal is strong. Availabilityand implementation MixTwice is available as an R software package https://cran.r-project.org/web/packages/MixTwice/. Supplementary information Supplementary data are available at Bioinformatics online.
9
Yang, Xiao-Yue, Di-Ying Zhong, Guo-Liang Wang, Run-Guang Zhang, and You-Lin Zhang. "Effect of Walnut Meal Peptides on Hyperlipidemia and Hepatic Lipid Metabolism in Rats Fed a High-Fat Diet." Nutrients 13, no. 5 (April 22, 2021): 1410. http://dx.doi.org/10.3390/nu13051410.
Full textAbstract:
As a natural active substance that can effectively improve blood lipid balance in the body, hypolipidemic active peptides have attracted the attention of scholars. In this study, the effect of walnut meal peptides (WMP) on lipid metabolism was investigated in rats fed a high-fat diet (HFD). The experimental results show that feeding walnut meal peptides counteracted the high-fat diet-induced increase in body, liver and epididymal fat weight, and reduce the serum concentrations of total cholesterol, triglycerides, and LDL-cholesterol and hepatic cholesterol and triglyceride content. Walnut meal peptides also resulted in increased HDL-cholesterol while reducing the atherosclerosis index (AI). Additionally, the stained pathological sections of the liver showed that the walnut meal peptides reduced hepatic steatosis and damage caused by HFD. Furthermore, walnut meal peptide supplementation was associated with normalization of elevated apolipoprotein (Apo)-B and reduced Apo-A1 induced by the high-fat diet and with favorable changes in the expression of genes related to lipid metabolism (LCAT, CYP7A1, HMGR, FAS). The results indicate that walnut meal peptides can effectively prevent the harmful effects of a high-fat diet on body weight, lipid metabolism and liver fat content in rats, and provide, and provide a reference for the further development of walnut meal functional foods.
10
Moosavi, A. R. Heravi, and M. Danesh Mesgaran. "Ruminal peptide-N concentrations in Iranian Balochi lambs fed diets containing lucerne hay or silage." Proceedings of the British Society of Animal Science 2001 (2001): 145. http://dx.doi.org/10.1017/s1752756200005275.
Full textAbstract:
Peptides are intermediates in the conversion of ingested protein to ammonia in the rumen and their accumulation depends upon the nature of diet (Mesgaran & Parker, 1995). Transient accumulation of peptides occurs after feeding and then their concentrations declines. In addition, it suggests that the production of peptides in the rumen was not altered by the protein supplements when diets provided similar effective rumen degradable protein (ERDP)(Mesgaran & Moosavi, 1999). The objective of the present experiment was to investigate the effect of diets, with similar ERDP, containing lucerne hay or silage on the ruminal peptide-N concentrations.
Dissertations / Theses on the topic "Peptides – Effets du fer"
1
Le, Foll Nathalie. "Effets biologiques et mécanisme d'action du peptide FEE cyclique." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB101.
Full text
2
Vitale, Sylvia. "Inhibiteurs anti-Fur et caractérisation de Fur d’Helicobacter pylori." Grenoble 1, 2009. http://www.theses.fr/2009GRE10270.
Full textAbstract:
Le travail de thèse s'est articulé autour de deux axes : l'étude d'inhibiteurs peptidiques anti-Fur et la caractérisation de Fur d'Helicobacter pylori. Avec l'apparition de souches pathogènes multi résistantes, de nouveaux antibactériens doivent être développés. Le régulateur principal du transport du fer bactérien Fur (Ferric Uptake regulator) est une cible potentielle. En effet, il régule des fonctions essentielles et est spécifique des procaryotes. Quatre aptamères peptidiques (F1 à F4) dirigés contre Fur d'Escherichia coli ont été isolés précédemment au laboratoire. Les aptamères peptidiques sont des protéines combinatoires constituées d'une plate-forme protéique constante dans laquelle est insérée une boucle variable de 13 acides aminés qui constitue la partie active. Les peptides linéaires pF1 à pF4, correspondant aux parties variables de F1 à F4 ont été testés in vitro pour leur capacité à inhiber la liaison de Fur à l'ADN. Des variants mutés et/ou tronqués ont aussi été étudiés. Des tests double hybride chez la levure ont été réalisés afin d'étudier in vivo l'interaction de Fur avec les peptides pF1 à pF4, et l'interaction des aptamères F1 à F4 avec les protéines Fur d'autres souches pathogènes, dont Helicobacter pylori. H. Pylori est une bactérie qui colonise la muqueuse gastrique chez l'homme. La protéine Fur d'H. Pylori a été purifiée, elle est nativement un dimère contenant un zinc par sous-unité. Ses propriétés de métallation et de liaison à l'ADN ont été étudiées, et les cystéines impliquées dans la liaison du zinc ont été identifiées. La structure tridimensionnelle du double mutant C78S C150S a été résolue en collaboration avec l'ESRFThe thesis work consisted in two major axes : the study of anti-Fur peptidic inhibitors and characterization of Fur from Helicobacter pylori. To struggle against multiresistant strains, new antibiotics need to be found. The Ferric Uptake Regulator Fur is a potential target. Indeed, it regulates essential functions in bacteria and is specific for prokaryotes. Four peptide aptamers (F1 to F4) able to interact with the Fur protein from Escherichia coli were previously selected in our laboratory. Peptide aptamers are combinatorial proteins and consist in a constant protein scaffold and a 13 amino acids variable loop, which is the active part, inserted within the scaffold. Linear peptides pF1 to pF4, corresponding to the variable loops of peptide aptamers F1 to F4, were tested in vitro for their ability to inhibit Fur DNA-binding activity. Several mutated and/or truncated variants were also tested. Yeast two-hybrid assays were also performed in order to study the in vivo interaction between Fur and peptides pF1 to pF4, and between aptamers F1 to F4 and Fur proteins from other pathogenic strains, such as Helicobacter pylori. H. Pylori is a strain that colonizes human gastric mucosal. The Fur protein from H. Pylori was purified as a native dimer, containing one zinc per monomer. Its metal- and DNA-binding properties were studied. The cysteines bound to the zinc were identified. The crystal structure of C78S C150S double mutant was solved, in collaboration with ESRF
3
Demirdis, Sultan. "Effets du désordre dans les supraconducteurs à base de fer." Phd thesis, Ecole Polytechnique X, 2012. http://pastel.archives-ouvertes.fr/pastel-00778943.
Full textAbstract:
L'ancrage des vortex est utilisé comme une sonde pour l'identification du type de désordre et son effet sur la supraconductivité dans la famille 122 des supraconducteurs à base de fer. Une nouvelle technique d'analyse obtenue d'images de décoration de Bitter prenant en compte l'interaction de chaque vortex avec ses voisins, a permis d'obtenir l'énergie et la force de piégeage dans Ba(Fe1-xCox)2As2, dans le régime de bas champ magnétique. La corrélation avec des mesures de courant critique Jc a montré que le piégeage des vortex dans ce composé est due à l'hétérogénéité des propriétés supraconductrices sur une échelle de 20-100 nm. Application de la même méthode d'analyse pour les vortex dans le BaFe2(As1-xPx)2 a montré que l'énergie et la force d'ancrage dépendent du dopage x. Les mesures de Jc et de la distribution des forces de piégeage ont montré que la distance moyenne entre différents centres de piégeage est de l'ordre de 90 nm et que cette distance augmente quand on augmente le conteneur en P. La combinaison de ces résultats avec les mesures de Jc mène à la conclusion que l'ancrage fort des lignes de flux due à l'hétérogénéité des propriétés supraconductrice à l'échelle de nm est à l'origine de la constante observé à des champ faibles dans les courbes de Jc ainsi que la diminution en loi de puissance qui suit. On traite également la contribution d'ancrage faible collectif à Jc, qui se manifeste à des champs magnétiques plus importants, de l'ordre de 1 T. Cette contribution a été analysée en terme de la diffusion des quasiparticules et de la fluctuation spatiale du libre parcours moyen. Afin de tester l'hypothèse avancé ci-dessus, l'irradiation aux électrons d'énergie 2.5 MeV, sur les composés dopé au Co, Ni et P de la famille 122 a été réalisé à des différentes doses pour plusieurs dopage de ces matériaux. Ce type d'irradiation introduit des défauts ponctuels de taille atomique dans le matériau. La température critique Tc de tous les matériaux étudiés diminue après irradiation de façon similaire. Une claire augmentation de la contribution d'ancrage faible collectif à Jc dans le composé dopé au Co a été observée. De plus, cette contribution qui, avant irradiation, était absente dans tous les dopages du composé au P, apparait après irradiation. Les défauts ponctuels de taille atomique, diffuseur des quasiparticules, dans les supraconducteurs à base de fer sont donc à l'origine de la contribution d'ancrage faible collectif à Jc .
4
Loréal, Olivier. "Effets de la surcharge en fer sur la fibrogenese hepatique." Rennes 1, 1993. http://www.theses.fr/1993REN1B007.
Full text
5
Ferry-Dumazet, Hélène. "Chimiorésistance tumorale : actions du NO, du fer et du resveratrol." Bordeaux 2, 2001. http://www.theses.fr/2001BOR28857.
Full textAbstract:
Malgré les multiples protocoles thérapeutiques appliqués dans les cancers et les leucémies, un échappement est souvent observé, nécessitant ainsi une intensification de la chimiothérapie, avec des effets secondaires délétères chez les patients. La compréhension des mécanismes impliqués dans la chimiorésistance peut aider à mieux orienter les thérapeutiques des affections tumorales. Dans ce travail, nous avons étudié le mécanisme anti-prolifératif du monoxyde d'azote (NO), ainsi que les voies d'échappement de cellules tumorales à l'action du NO. Nous avons confirmé le rôle du NO dans l'inhibition de la prolifération et l'induction de l'apoptose de cellules tumorales. Ces résultats montrent également que le NO possède une action en tant que chélateur du fer, nécessaire à son activité anti-tumorale. Le NO chélate le fer de manière dose-dépendante et ce, dès la première heure post traitement. Une augmentation du fer intracellulaire rend les cellules tumorales résistantes à l'action du NO, alors que la chélation du fer augmente l'apoptose et la chimiosensibilité des cellules tumorales. En plus du NO, nous avons mis en évidence l'action anti-proliférative du Resvératrol, un polyphénol d'origine alimentaire, sur les cellules leucémiques humaines. L'étude de mécanisme d'action de cette molécule nous montre une action régulatrice de cette molécule sur le cycle cellulaire et les cyclines, aboutissant à l'arrêt de la prolifération. Cependant, cette molécule inhibe également la prolifération des cellules normales activées. Contrairement au NO, le Resvératrol reverse la chimiosensibilité des cellules leucémiques exprimant le gène MDR. En conclusion, nos résultats peuvent apporter un nouvel outil thérapeutique dans le traitement des cancers et des leucémiesThe wide range of therapeutic protocols in cancer or leukemia does not prevent the appearance of chemoresistance in some patients, which then requires the intensification of these protocols, together with the deleterious side effects for the patients. Understanding intracellular mechanism of chemoresistance may help better achievement of anti-tumor therapy. In the present work, we have investigated the mechanism of the anti-proliferation activity of nitric oxide (NO) and intracellular pathways involved in tumor cell rescue from NO-mediated apoptosis. We first showed thar appropriate formulation of exogenous NO was able to decrease the proliferation of tumor cells. We also evidenced the capacity of NO to chelate intracellular iron, a necessary metal for tumor cell proliferation. Iron chelation by NO wase dose-dependent and appeared early following cell incubation (1-4 hrs). Increased cellular levels of iron protected tumor cells from the proapoptotic effects of NO, while iron chelation increased chemosensitivity of these cells. In addition to NO, we have analysed the anti-tumoral activity of Resveratrol, a nutrient-derived polyphenol, in human leukemia cells. Resveratrol was shown to significantly modulate the cell cycle and the expression of regulatory cyclins, involved in cell cycle arrest and death. This molecule, however, induced the death of normal cycling cells as well. On interest, and contrast to NO, Resveratrol reversed the chemoresistance of leukemia cells expressing MDR gene. In conclusion, this work shows new data to understand NO-mediated apooptosis and provides new tools for the treatment of cancers and leukemia
6
Paris, Cédric. "Développement de nouvelles approches analytiques pour le criblage de peptides chélateurs de fer." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0088.
Full textAbstract:
Face au besoin croissant de nouvelles molécules bioactives d’origine naturelle, les coproduits de l’industrie alimentaire et de transformation d’agroressources constituent une ressource stratégique à exploiter. En effet, l’hydrolyse enzymatique de protéines végétales ou animales permet de générer une grande variété de séquences peptidiques avec des propriétés biologiques potentielles : antihypertensive, antithrombotique, anticancéreuse, opioïde, antimicrobienne. Malgré le potentiel bioactif de certains peptides, leur présence incertaine et leur faible concentration au sein d’un hydrolysat protéique (mélange complexe constitué d’une dizaine à parfois plus d’une centaine de peptides) limitent leur purification et leur exploitation. Aussi, les peptides bioactifs pourraient être criblés préalablement à toute phase séparative afin de n’engager l’étape de séparation qu’en cas d’activité avérée. Le pouvoir antioxydant est un terme générique qui regroupe divers mécanismes chimiques tels que l’activité anti-radicalaire, l’inhibition de la peroxydation des lipides, ou encore la chélation de métaux. En chélatant les métaux de transition naturellement présents in vivo (fer, cuivre), les peptides chélateurs pourraient être utilisés comme antioxydants indirects et agir ainsi contre le stress oxydant. L’objectif principal de cette thèse est de développer des méthodes originales de criblage à haut débit des peptides chélateurs de fer présents dans des hydrolysats peptidiques. A terme, ces méthodes pourraient être appliquées à tous types de mélanges peptidiques complexes. La première approche développée met en œuvre la chromatographie d'affinité pour ions métalliques immobilisés (IMAC). Cette technique est incontournable pour purifier des peptides chélateurs de métaux au sein des hydrolysats. Grâce à la spécificité d’interaction entre un métal donné – immobilisé sur la phase stationnaire IMAC – et des motifs complexants déterminés, il est possible d’identifier sélectivement les composés chélateurs présents dans des mélanges complexes. Notre objectif étant de parvenir à une détection rapide de ces molécules d’intérêt, nous avons réalisé un couplage en ligne avec la spectrométrie de masse (MS). La deuxième stratégie consiste à évaluer la formation des complexes fer-peptide en solution. Dans ce cas, tous les sites accepteurs d’électrons du métal sont accessibles (au contraire de la technique IMAC qui présente un biais potentiel de ce point de vue) et, d’autre part, les conditions de solubilisation peuvent simuler le milieu visé (i.e. le milieu intracellulaire). Par ailleurs, l’observation de la forme complexée avec le fer (FeII ou FeIII) fournit une preuve directe et irréfutable de la capacité de chélation d’un peptide. Ainsi, la mise en évidence d’un peptide chélateur peut être réalisée par détection concomitante de sa forme libre (peptide seul) et de sa forme complexée (fer-peptide). Dans cette approche, la spectrométrie de masse – de par sa sensibilité et sa spécificité – est une technique de choix pour réaliser le criblage souhaité. Après avoir été testés sur des peptides des synthèse (sous forme pure et en mélange), les deux protocoles ont été appliqués à un hydrolysat protéique réel. Les résultats préliminaires obtenus sont prometteurs et permettent d'envisager, à court terme, le criblage automatisé de divers hydrolysats réels, pour la recherche de peptides chélateurs du fer(II) et du fer(III)Faced with the growing need for new bioactive compounds of natural origin, by-products from the agro-food industry and the processing of agro-resources constitute a strategic resource to be exploited. In fact, the enzymatic hydrolysis of plant or animal proteins makes it possible to generate a wide variety of peptide sequences with potential biological properties: antihypertensive, antithrombotic, anticancer, opioid, antimicrobial. Despite the bioactive potential of certain peptides, their uncertain presence and their low concentration in a protein hydrolysate (a complex mixture sometimes made up of more than a hundred peptides) limit their purification and use. Also, bioactive peptides could be screened before their purification in order to initiate the separation step only if activity is proven. Antioxidant power is a generic term which groups together various chemical mechanisms such as anti-free radical activity, inhibition of lipid peroxidation, or even metal chelation. By chelating the transition metals naturally present in vivo (iron, copper), the chelating peptides could be used as indirect antioxidants and thus act against oxidative stress. The main objective of this PhD thesis is to develop original methods for high throughput screening of iron-chelating peptides present in protein hydrolysates. Ultimately, these methods could be applied to all types of complex peptide mixtures. The first approach is based on immobilized metal affinity chromatography (IMAC). IMAC is a reference technique for purifying metal-chelating peptides in hydrolysates. Thanks to the specificity of interaction between a given metal – immobilized on the stationary phase IMAC – and determined complexing groups, it is possible to selectively identify the chelators present in complex mixtures. Our objective being to achieve a rapid detection of these molecules of interest, we carried out an on-line coupling with mass spectrometry (MS). The second strategy consists of evaluating the formation of iron-peptide complexes in solution. In this case, all the electron acceptor sites of the metal are accessible (unlike the IMAC technique which presents a potential bias from this point of view) and, on the other hand, the solubilization conditions can simulate the target medium (i.e. the intracellular medium). In addition, the observation of the peptidic form complexed with iron (FeII or FeIII) provides direct and irrefutable proof of the chelating capacity of a peptide. Thus, the identification of a chelating peptide can be carried out by the concomitant detection of its free form (peptide) and of its complexed form (iron-peptide). In this approach, mass spectrometry – thanks to its sensitivity and its specificity - is a technique of choice for carrying out the desired screening. After having been tested on synthetic peptides (pure solutions and mixture), the two protocols were applied to a real protein hydrolysate. The preliminary results are promising and make it possible to envisage, in the short term, the automated screening of various real hydrolysates for the search for iron(II)- and iron(III)-chelating peptides
7
Nedjaoum, Fouzia. "Mise au point à partir de l'hémoglobine d'un procédé de préparation de complexes hème-peptides à destination d'une application diététique." Lille 1, 2003. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2003/50376-2003-235.pdf.
Full textAbstract:
La carence en fer est le problème nutritionnel mondial majoritaire. Une des stratégies mises en place pour la prévenir et la combattre est l'optimisation de l'utilisation de l'hémoglobine comme source de fer. Mais sa faible proportion en fer hémique (0,34%, p/p) limite son utilisation. L'objectif de ce travail était de mettre au point à partir de l'hémoglobine un procédé de préparation d'une fraction de peptides hémiques à haute teneur en fer soluble. Pour être potentiellement biodisponible, le fer hémique doit être complexé aux peptides qui permettent sa solubilisation au pH acide de l'estomac. Une étude systématique a montré que la composition des populations peptidiques est déterminante pour le transport du fer hémique. Seuls l'hémoglobine native et des peptides de grande taille sont capables de transporter 1'hème et de limiter son agrégation. En exploitant la capacité de ces populations peptidiques à transporter l'hème, nous avons mis au point un procédé de préparation d'une fraction de peptides hémiques riche en fer (2,1%, g/g) avec 80% de ce fer sous forme de complexes fer-peptide. Ce procédé est basé sur l'ultrafiltration d'un hydrolysat pepsique de faible degré d'hydrolyse (3%) préparé à pH 3 et sur l'apport d'hème extrinsèque préparé par hydrolyse pepsique à pH 2. Le procédé de séchage est déterminant pour l'obtention d'une poudre de peptides hémiques avec des propriétés d'écoulement favorables à une formulation sous fonne de gélules destinées à une application diététique.
8
Arafah, Sonia. "Induction par un stress de la résistance aux peptides antimicrobiens chez Yersinia." Lille 2, 2009. http://www.theses.fr/2009LIL2S008.
Full textAbstract:
Lorsque les bactéries colonisent un hôte, elles sont rapidement confrontées à l'activité d'effecteurs de l'immunité innée parmi lesquels figurent les peptides anti-microbiens. Produites par de nombreux organismes vivants, ces molécules sont pourvues de charges électro-positives et de domaines hydrophobes responsables de leur activité : leurs interactions avec les charges électro-négatives portées par des composés de la surface bactérienne est suivie d'une perméabilisation de la membrane cytoplasmique susceptible d'aboutir à la mort cellulaire. Cependant, au cours de leur évolution, les bactéries ont développé des mécanismes défensifs à l'égard des peptides anti-microbiens. Ainsi, lorsque Yersinia pseudotuberculosis - une bactérie pathogène pour le tractus digestif de l'homme et de nombreux animaux et choisie comme modèle pour cette étude- a poussé dans un milieu carencé en fer, sa survie est augmentée en présence d'un peptide anti-microbien particulier : la polymyxine B. A l'opposé, celle de Y. Enterocolitica, une espèce phylogénétiquement proche, reste inchangée dans les mêmes conditions expérimentales. Nous avons donc émis l'hypothèse que des gènes, présents uniquement chez Y. Pseudotuberculosis, conféreraient au microorganisme la capacité de résister à la polymyxine B. Afin de les caractériser, nous avons construit une banque constituée de dix mille fragments génomiques (obtenus aléatoirement) de Y. Pseudotuberculosis, puis recherché le(s)quel(s) d'entre eux permet(tent) l'induction d'une résistance à la polymyxine B chez Y. Enterocolitica privée de fer. Nous avons ainsi identifié deux régions chromosomiques distinctes de Y. Pseudotuberculosis qui sont impliquées dans le phénotype de résistance. La première comporte trois gènes, YPTB0331, YPTB0332 et YPTB0333, spécifiant respectivement un transporteur putatif, une protéine de fonction inconnue et un régulateur transcriptionnel de la famille LysR. La seconde région comprend deux gènes, YPTB2685 et YPTB2686, codant des produits de fonction inconnue. L'inactivation de l'un des gènes de chacune de ces régions, YPTB0333 et YPTB2686, altère la résistance de Y. Pseudotuberculosis à la polymyxine B mais également à des peptides anti-microbiens d'Invertébrés (dérivés de cécropines, polyphémusine). Elle est également associée à une diminution de la virulence bactérienne in vivo, qui est essentiellement due à une colonisation réduite des plaques de Peyer intestinales, étape déterminante du processus infectieux chez l'hôte. Le mécanisme de résistance mis en jeu par YPTB0331-0332-0333 est une modification de la surface bactérienne, responsable d'une réduction du contact des peptides avec la bactérie. Le rôle exercé par YPTB2685 et YPTB2686 serait d'inactiver (voire de dégrader) la polymyxine B
9
Maestre, Philippe. "Métaux redox (cuivre, fer) et production de radicaux hydroxyles. Application à la cytotoxicité des quinones." Toulouse 3, 1991. http://www.theses.fr/1991TOU30211.
Full textAbstract:
Hautement reactif, le radical hydroxyle est de plus en plus souvent considere comme la forme la plus pathogene de produits de reduction de l'oxygene moleculaire. Les radicaux hydroxyles sont produits par radiation ionisante, ou par la reduction catalysee par un metal redox du peroxyde d'hydrogene: le fe(ii) et le cu(i) jouent un role determinant in vivo. L'etude du role du cu(ii) sur la production de radicaux hydroxyl catalysee par le fe(ii) met en evidence un effet inhibiteur ph dependant pour un rapport cu(ii)/fe(ii) egal a un. Cet inhibiteur du cu(ii), retrouve quand le radical hydroxyle est genere a partir du complexe (fe-anthracycline), ouvre la voie a possible regulation de la cytotoxicite de ces agents anti-tumoraux
10
Nyassi, Abdelhamid. "Contribution à l'étude du comportement d'un alliage ferritique dans des milieux gazeux complexes (oxydant-sulfurant) à haute température." Dijon, 1985. http://www.theses.fr/1985DIJOS030.
Full textAbstract:
Analyse du comportement d'un alliage ferritique Fe-22,5 Cr-4,5 al dans différents milieux corrosifs à haute temperature. Etude cinétique et morphologique et détermination du mécanisme de corrosion en fonction de l'atmosphère gazeuse
Books on the topic "Peptides – Effets du fer"
1
Hubert, Vaudry, and Laburthe Marc, eds. VIP, PACAP, and related peptides: From gene to therapy. Boston, Mass: Published by Blackwell Pub. on behalf of the New York Academy of Sciences, 2006.
Find full text
2
NATO Advanced Research Workshop on the Role of Melatonin and Pineal Peptides in Neuroimmunomodulation (1990 Erice, Italy). Role of melatonin and pineal peptides in neuroimmunomodulation. New York: Plenum Press, 1991.
Find full text
3
Bureau de la sécurité des transports du Canada. CN Amérique du Nord train parti à la dérive point milliaire 175, subdivision Grande Cache Latornell (Alberta) 18 janvier 1994. Hull, Qué: Bureau de la sécurité des transports du Canada, 1995.
Find full text
4
Mielczarek, Eugenie V. Iron, nature's universal element: Why people need iron & animals make magnets. New Brunswick, N.J: Rutgers University Press, 2000.
Find full text
5
Chan, W., and Peter White, eds. Fmoc Solid Phase Peptide Synthesis. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780199637256.001.0001.
Full textAbstract:
In the years since the publication of Atherton and Sheppard's volume, the technique of Fmoc solid-phase peptide synthesis has matured considerably and is now the standard approach for the routine production of peptides. The basic problems outstanding at the time of publication of this earlier work have now been, for the most part, solved. As a result, innovators in the field have focussed their efforts to develop methodologies and chemistry for the synthesis of more complex structures. The focus of this new volume is much broader, and covers not only the essential procedures for the production of linear peptides but also more advanced techniques for preparing cyclic, side-chain modified, phospho- and glycopeptides. Many other methods also deserving attention have been included: convergent peptide synthesis; peptide-protein conjugation; chemoselective ligation; and chemoselective purification. The difficult preparation of cysteine and methionine-containing peptides is also covered, as well as methods for overcoming aggregation during peptide chain assembly and a survey of available automated instrumentation.
6
Bird, Mark F., and David G. Lambert. Deorphanization of ORL-1/LC132 by reverse pharmacology in two landmark studies. Edited by Paul Farquhar-Smith, Pierre Beaulieu, and Sian Jagger. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198834359.003.0026.
Full textAbstract:
Deorphanization of ORL-1/LC132 in 1995 by reverse pharmacology in two simultaneously published landmark studies added a new member to the opioid family of G-protein coupled receptors. Meunier and Reinscheid used cells expressing recombinant ORL-1 (human) or LC132 (rat) and the presumed intracellular inhibition of cyclic AMP formation to ‘fish’ for endogenous peptide ligands in rat whole-brain and pig hypothalamic extracts. Both studies reported the isolation of a 17-amino-acid peptide, which was named nociceptin and orphanin FQ by the two authors, respectively. The behaviour of the isolated peptide was a complete surprise, as a general hyperalgesia was observed when the peptide was administered at supraspinal sites. We now know that this peptide has, in fact, anti-opioid action, particularly in the medulla. The endogenous peptide exerts a multitude of effects both in the nervous system and, unlike classical opioids, has efficacy in neuropathic pain.
7
Wójcik-Gładysz, Anna. Ghrelin – hormone with many faces. Central regulation and therapy. The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 2020. http://dx.doi.org/10.22358/mono_awg_2020.
Full textAbstract:
Discovered in 1999, ghrelin, is one of the peptides co-creating the hypothalamicgastrointestinal axis, otherwise known as the brain-gut axis. Ghrelin participates in many physiological processes and spectrum of its activity is still being discovered. This 28 amino acid peptide ‒ a product of the ghrl gene, was found in all vertebrates and is synthesized and secreted mainly from enteroendocrine X/A cells located in the gastric mucosa of the stomach. Expression of the ghrelin receptor has been found in many nuclei of the hypothalamus involved in appetite regulation. Therefore it’s presumed that ghrelin is one of the crucial hormones deciphering the energy status required for the maintenance of organism homeostasis. Ghrelin acts as a signal of starvation or energy insufficiency and its level in plasma is reduced after the meal. Neuropeptide Y (NPY) and agouti-related peptide (AgRP; NPY/AgRP) neurons located in the arcuate nucleus (ARC) area are the main target of ghrelin in the hypothalamus. This subpopulation of neurons is indispensable for inducing orexigenic action of ghrelin. Moreover ghrelin acting as a neurohormone, mainly in the hypothalamus area, plays an important role in the regulation of growth and reproduction processes. Indeed, ghrelin action on reproductive processes has been observed in the systemic effects exerted at both hypothalamus-pituitary and gonadal levels. Similarly the GH-releasing ghrelin action was observed both on the hypothalamus level and directly on the somatotrophic cells in the pituitary and this dose-related GH releasing activity was found in in vitro as well as in in vivo experiments. In recent years, numerous studies revealed that ghrelin potentially takes part in the treatment of diseases associated with serious disturbances in the organism energy balance and/or functioning of the gastrointestinal tract. It was underlined that ghrelin may be a hormone with a broad spectrum of therapeutic effect on obesity and anorexia nervosa, as well as may also have protective effect on neurodegenerative diseases, inflammatory disorders or functional changes in the body caused by cancers. In overall, ghrelin treatment has been tested in over 100 preclinical studies with healthy volunteers as well as patients with various types of cancer, eating disorders such as anorexia nervosa and bulimia nervosa. It was observed that ghrelin has an excellent clinical safety profile and emerging side effects occurred only in 3–10% of patients and did not constitute a sufficient premise to discontinue the therapy. In general, it can be concluded that ghrelin may be sufficiently used as a prescription drug.
8
A new method of distinguishing between organic and inorganic compounds of iron. [S.l: s.n., 1985.
Find full text
9
Peptide Hormones: Effects and Mechanisms of Action (Peptide Hormones). CRC, 1988.
Find full text
10
Tracy, Derek K., and Fiona Gaughran. Treatment with medication: Side effects, adherence, and risk. Edited by Alec Buchanan and Lisa Wootton. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198738664.003.0009.
Full textAbstract:
Antipsychotic medications revolutionized the care of psychosis, but they have brought with them significant side effects and issues around adherence; these latter factors, and informed co-working with patients, are primary drivers for specific medication choices. The data remain limited for polypharmacy and above-maximum dose prescribing, though there may be individuals for whom this is considered. Long-acting injectables (LAIs or ‘depots’) have a good evidence base, and are probably underutilized, though clozapine remains our drug of choice in refractory illness. Forensic-population data show that medications significantly reduce recidivism, including of violent crime. Whilst side effect data are disheartening for both patient and clinician, there are rational management strategies for them all. Novel future therapies being evaluated include acetylcholinergic and glutamatergic enhancers, anti-inflammatory drugs, and the neural peptide oxytocin, to improve negative and cognitive functioning; neuromodulation through rTMS and tDCS are also showing early promise.
Book chapters on the topic "Peptides – Effets du fer"
1
Pontiroli, A. E., M. Alberetto, A. Calderara, E. Pajetta, and G. Pozza. "Metabolic Effects of Intranasally Administered Insulin and Glucagon in Man." In Delivery Systems for Peptide Drugs, 243–48. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4757-9960-6_20.
Full text
2
Ramachandran, Saravanan, and Senthilkumar Rajagopal. "Protective Effect of Marine Peptides/Toxins in CVD Using Zebrafish Model." In Zebrafish: A Model for Marine Peptide Based Drug Screening, 55–73. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7844-7_5.
Full text
3
Wen-Yih, Chen, Shu Ching-Gji, and Chen Jw-Yann. "The Effect of Amino Acid Sequence on the Separation of Peptides in an Aqueous Two- Phase System." In Biochemical Engineering for 2001, 590–92. Tokyo: Springer Japan, 1992. http://dx.doi.org/10.1007/978-4-431-68180-9_159.
Full text
4
Quan, C. P., E. Canova-Davis, and A. B. Chen. "Effects of the Solution Environment on the Resolution of Recombinant Human Deoxyribonuclease Variants in Capillary Zone Electrophoresis." In CE in Biotechnology: Practical Applications for Protein and Peptide Analyses, 39–44. Wiesbaden: Vieweg+Teubner Verlag, 2001. http://dx.doi.org/10.1007/978-3-322-83021-0_5.
Full text
5
Maurice, Donald H. "Adaptive and Mal-Adaptive Signaling in Cells of the Cardiovascular System: Effect of Obesity-Associated Peptides on Human Blood Platelet Activation." In NATO Science for Peace and Security Series A: Chemistry and Biology, 185–89. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6513-9_15.
Full text
6
Chabannon, Christian, and Chiara Bonini. "Structure of and Signalling Through Chimeric Antigen Receptor." In The EBMT/EHA CAR-T Cell Handbook, 3–5. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94353-0_1.
Full textAbstract:
AbstractChimeric antigen receptor (CAR) is a synthetic transmembrane protein expressed at the surface of immune effector cells (IECs) that are reprogrammed either in vitro or in vivo (June et al. 2018; June and Sadelain 2018). Techniques for genetic engineering of autologous or allogeneic IECs are described in the next chapter. The synthetic CAR incorporates several functional domains. The extracellular domain is composed of a single chain variable fragment (ScFV) of immunoglobulin and recognizes the “tumour” antigen. The clinical relevance of the selected tumour antigen—with a view to minimize “on-target/off-tumour” side effects—is discussed in the third chapter of this section. Bispecific and trispecific CARs are currently being evaluated in preclinical and early clinical trials (Bielamowicz et al. 2018; Shah et al. 2020). The use of an immunoglobulin domain as the ligand of the target antigen means that recognition is not restricted to HLA antigens and that CAR-T cells are universally applicable as opposed to T cell receptor (TCR) transgenic T cells that recognize antigenic peptides presented in the context of a defined major histocompatibility complex (MHC), limiting clinical applications to subsets of patients with defined HLA typing. The intracellular domain is composed of the intracellular domain of the zeta chain of the CD3 component of the TCR, which will trigger signalling when the CAR engages the targeted ligand. The transmembrane region links the two extracellular and intracellular domains through the cell membrane and plays an important role in determining the conformation and flexibility of the CAR and its ability to efficiently bind the targeted antigen/epitope. Association of only these three functional domains characterized first generation CARs, as described in the original publications (Kuwana et al. 1987; Eshhar et al. 1993). However, full activation of T cells requires the addition of one (second generation CARs) or two (third generation CARs) domains from costimulatory molecules, such as CD28, 4-1BB/CD137, or OX40/CD134, that provide the T cell costimulatory signal. Currently approved CAR-T cells are second generation CAR-T cells; as an illustration, the CAR in tisagenlecleucel contains a 4-1BB domain, while the CAR in axicabtagene ciloleucel contains a CD28 domain. The nature of the costimulatory domain influences the ability of CAR-T cells to expand or persist (limit T cell exhaustion) in vivo after infusion into the patient, although it is unclear how this translates clinically and affects disease control, occurrence of adverse events, and overall survival due to the lack of head-to-head comparison between approved products. Finally, fourth generation CAR-T cells have been developed for preclinical projects. These cells, named armoured CAR cells or T cells redirected for universal cytokine-mediated killing (TRUCKS), encode not only a CAR (usually with one costimulatory domain, such as in second generation CARs) but also a cytokine, interleukin, pro-inflammatory ligand, or chemokine that will counteract the immune suppressive microenvironment that prevails in most solid tumours (Eshhar et al. 1993; Chmielewski and Abken 2015).
7
Štěpánová, Sille, and Václav Kašička. "Analysis of Peptides by Capillary Electromigration Methods." In Current and Future Developments in Food Science, 109–46. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815036152122020007.
Full textAbstract:
These peptides themselves and especially as products of enzymatic or chemical cleavage of parental proteins, belong to the important components of foodstuffs. They significantly influence their nutritional, biological, technological, and functional properties. Some of these peptides were found to have effects on human health and nutrition, e.g., by affecting human digestive, endocrine, cardiovascular, immune, and nervous systems. Hence, qualitative and quantitative analysis of peptides in foods is of great importance. For the separation and quantification of peptides in foods, capillary electromigration methods represent one of the most suitable analytical methods. This chapter presents a comprehensive overview of the developments and applications of high performance capillary and microchip electromigration methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography and electrochromatography) for separation and analysis of peptides in foods and food products in the time period since 2010 up to the middle of 2020. Various aspects of the application of capillary electromigration methods for peptide analysis in foods, such as sample preparation, peptide preseparation, preconcentration, derivatization, adsorption suppression, and detection, are described and discussed. Several particular applications of capillary electromigration methods for separation and analysis of peptides in various food samples of animal, plant, and microbial origin are demonstrated.
8
MARCOS-MÉNDEZ, Dora Alicia, Abril RAMIREZ-HIGUERA, Rosa Marí OLIART-ROS, and Andrea Yazmín GUADARRAMA-LEZAMA. "The relevance of the source of animal or vegetable proteins on the metabolic syndrome and its comorbidities." In CIERMMI Women in Science Biology, Chemistry and Life Sciences Handbook T-XIV, 30–38. ECORFAN-Mexico, S.C., 2021. http://dx.doi.org/10.35429/h.2021.14.30.38.
Full textAbstract:
Metabolic Syndrome (MS) is one of the most serious health problems worldwide since 25% of the population suffers from it and 80% of these are at risk of cardiovascular diseases and diabetes mellitus. MS is defined as a series of metabolic abnormalities constituted by arterial hypertension (HTN), abdominal obesity, dyslipidemias, glucose intolerance and/or insulin resistance (IR). Proteins are long chains of amino acids and have a characteristic three-dimensional structure that is essential for their specific function. These are a source of bioactive peptides that can have beneficial effects on health. Bioactive peptides are small peptide chains composed of 2 to 15 amino acid residues, obtained by industrial food processing or during gastrointestinal digestion; after oral administration, they exert their beneficial effect on the cardiovascular, digestive, immune, and nervous systems. Therefore, the objective of this review is to describe investigations about the positive effects of different kinds and sources of protein, fractions, or peptides in MS.
9
Mathews, Jennifer L., and Anne Schweighardt. "The Role of Natriuretic Peptides in the Pathophysiology and Treatment of Heart Failure." In Emerging Applications, Perspectives, and Discoveries in Cardiovascular Research, 1–16. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-2092-4.ch001.
Full textAbstract:
The pathophysiology of heart failure is due in part to compensatory mechanisms utilized to maintain cardiac output. Neurohormonal responses include activation of the renin-angiotensin-aldosterone and sympathetic nervous systems leading to vasoconstriction, increased blood volume through reabsorption of sodium and water, and increased myocardial contractility and heart rate. Prolonged activation of these systems often results in a maladaptive response and a further reduction in cardiac output (Colucci, 2015). Natriuretic peptides counterbalance the neurohormonal systems by antagonizing the actions of renin-angiotensin-aldosterone, promoting vasodilation and natriuresis. In hypervolemic states atrial myocytes are stretched resulting in the release of atrial natriuretic peptide (ANP). Ventricular cells secrete brain-type natriuretic peptide (BNP) in response to the high ventricular filling pressures (de Sa, 2008). The natriuretic peptides are degraded enzymatically by neprilysin. Plasma concentrations of ANP and BNP can be used as markers for the diagnosis of heart failure (Grewal, 2004). The kidneys also produce a natriuretic peptide, urodilatin, and new studies suggest a role for this peptide in the pathophysiology and treatment of heart failure (Anker, 2015). The natriuretic peptides can be targeted therapeutically for the treatment of heart failure. Nesiritide, a recombinant preparation of human B-type natriuretic peptide (BNP), is FDA approved and has been available for several years for treatment of acute decompensations of heart failure, but has received limited use due to cost and adverse effect profile. Ularatide, a synthetic analog of urodilatin, is currently in phase three clinical trials. In addition, the FDA has recently approved an angiotensin receptor blocker-neprilysin inhibitor that has shown mortality benefit.
10
White, Peter D., and Weng C. Chan. "Basic principles." In Fmoc Solid Phase Peptide Synthesis. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780199637256.003.0006.
Full textAbstract:
Construction of a peptide chain on an insoluble solid support has obvious benefits: separation of the intermediate peptides from soluble reagents and solvents can be effected simply by filtration and washing with consequent savings in time and labour over the corresponding operations in solution synthesis; many of the operations are amenable to automation; excess reagents can be employed to help to drive reactions to completion; and physical losses can be minimized as the peptide remains attached to the support throughout the synthesis. This approach does, however, have its attendant limitations. By-products arising from either incomplete reactions, side reactions, or impure reagents will accumulate on the resin during chain assembly and contaminate the final product. The effects on product purity of achieving less than 100% chemical efficiency in every step are illustrated dramatically in Table 1. This has serious implications with regard to product purification as the impurities generated will, by their nature, be very similar to the desired peptide and therefore extremely difficult to remove. Furthermore, the analytical techniques employed for following the progress of reactions in solution are generally not applicable, and recourse must generally be made to simple qualitative colour tests to detect the presence of residual amines on the solid phase. The principles of solid phase synthesis are illustrated in Figure 1. The C-terminal amino acid residue of the target peptide is attached to an insoluble support via its carboxyl group. Any functional groups in amino acid side chains must be masked with permanent protecting groups that are not affected by the reactions conditions employed during peptide chain assembly. The temporary protecting group masking the α-amino group during the initial resin loading is removed. An excess of the second amino acid is introduced, with the carboxy group of this amino acid being activated for amide bond formation through generation of an activated ester or by reaction with a coupling reagent. After coupling, excess reagents are removed by washing and the protecting group removed from the N-terminus of the dipeptide, prior to addition of the third amino acid residue.
Conference papers on the topic "Peptides – Effets du fer"
1
Nesher, E., A. Pinhasov, M. Becker, R. Cohen-Harazi, S. Yakobovich, I. Gitlin, K. Leonova, K. Gurova, A. Gudkov, and I. Koman. "PO-459 Systemic anti-inflammatory effect of a new anticancer cyclic peptide ALOS4." In Abstracts of the 25th Biennial Congress of the European Association for Cancer Research, Amsterdam, The Netherlands, 30 June – 3 July 2018. BMJ Publishing Group Ltd, 2018. http://dx.doi.org/10.1136/esmoopen-2018-eacr25.480.
Full text
2
Behr, J., M. Kolb, H. Olschewski, JW Song, F. Luppi, B. Schinzel, S. Stowasser, M. Quaresma, and FJ Martinez. "Does brain natriuretic peptide (BNP) at baseline influence the effects of nintedanib plus sildenafil in patients with IPF?" In 61. Kongress der Deutschen Gesellschaft für Pneumologie und Beatmungsmedizin e.V. Georg Thieme Verlag KG, 2020. http://dx.doi.org/10.1055/s-0039-3403296.
Full text
3
Kuninty, PR, R. Bansal, TN Satav, MF Bijlsma, HV Laarhoven, A. Östman, and J. Prakash. "PO-009 A novel integrin alpha 5 binding peptide potentiates effects of chemotherapy in pancreatic cancer." In Abstracts of the 25th Biennial Congress of the European Association for Cancer Research, Amsterdam, The Netherlands, 30 June – 3 July 2018. BMJ Publishing Group Ltd, 2018. http://dx.doi.org/10.1136/esmoopen-2018-eacr25.544.
Full text
4
Kadymova, Solmaz. "EFFECT OF A LONG-TERM LOW PROTEIN DIET ON THE LEVEL OF MEDIUM MOLECULAR PEPTIDES IN THE LIVER OF WHITE RAT." In XVII INTERNATIONAL INTERDISCIPLINARY CONGRESS NEUROSCIENCE FOR MEDICINE AND PSYCHOLOGY. LCC MAKS Press, 2021. http://dx.doi.org/10.29003/m2147.sudak.ns2021-17/174-175.
Full text
5
Pomytkin, N. S., M. E. Pak, E. A. Rogozhin, and N. A. Gaevsky. "The effect of antimicrobial peptides of plant origin on the photosynthesis of larch regenerants obtained by somatic embryogenesis." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-360.
Full text
6
Neumann, Laurie. "Synthesis of 5,15-A2BC-Type Porphyrins to Modify a Field-Effect Transistor for Detection of Gram-Negative Bacteria." In SurfCoat Korea and Graphene Korea 2021 International Joint Virtual Conferences. Setcor Conferences and Events, 2021. http://dx.doi.org/10.26799/cp-surfcoat-graphene-korea-2021/2.
Full textAbstract:
Current biological sensing technologies of bacteria are time consuming, labor intensive and thus expensive. Furthermore, their accuracy and reproducibility could be improved. Conventional electrical measurement methods might combine high sensitive sensing systems with biological requirements. A promising approach is the trapping of bacteria on the surface of the gate-electrode of a modified field-effect transistor (FET) using porphyin based self-assembled monolayers (SAMs). 5,15-A2BC-type porphyrins were synthesized originating from a 5,15-diphenylporphyrin with the functionality to connect to a gold surface. The SAM formation on the surface of the gold electrode was proven by well-established analytical methods. In this work a synthesis route is presented for a linker which is attached to a peptide or cysteine group for trapping of Gram-negative bacteria. Fluorescence lifetime imaging microscopy (FLIM) measurements of porphyrin-stained bacteria were performed to verify the linkage ability.
7
Sultanly, Maya, and Fakhreddin Askerov. "THE EFFECT OF CARBOHYDRATE DEFICIENCY IN THE DIET OF WHITE RATS ON THE CONTENT OF TRYPTOPHAN AND TYROSINE PEPTIDES IN THE BLOOD." In XVIII INTERNATIONAL INTERDISCIPLINARY CONGRESS NEUROSCIENCE FOR MEDICINE AND PSYCHOLOGY. LCC MAKS Press, 2022. http://dx.doi.org/10.29003/m2946.sudak.ns2022-18/331-332.
Full text
8
Ibragimova, Samira. "EFFECT OF E LONG PROTEIN DIET ON THE AMOUNT OF MEDIUM MOLEKULAR PEPTIDES IN DIFFERENT AREAS OF THE BRAIN CORTEX OF WHITE RAT." In XVII INTERNATIONAL INTERDISCIPLINARY CONGRESS NEUROSCIENCE FOR MEDICINE AND PSYCHOLOGY. LCC MAKS Press, 2021. http://dx.doi.org/10.29003/m2136.sudak.ns2021-17/160-161.
Full text
9
Kadimova, Solmaz, Armilla Azimova, and Vafa Yunusova. "THE EFFECT OF FORTY-DAY CARBOHYDRATE DEFICIENCY IN FOOD ON THE CONTENT OF MEDIUM MOLECULAR WEIGHT PEPTIDES IN THE LIVER OF WHITE RATS." In XVIII INTERNATIONAL INTERDISCIPLINARY CONGRESS NEUROSCIENCE FOR MEDICINE AND PSYCHOLOGY. LCC MAKS Press, 2022. http://dx.doi.org/10.29003/m2775.sudak.ns2022-18/153-154.
Full text
10
Sadeghipour, Keyanoush, Wenhai Wang, and George Baran. "Toward Improving Fracture Toughness of Particle-Reinforced Polymer Matrix Composites." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-66221.
Full textAbstract:
Experimental results have shown that polymer composites that have high fracture toughness tend to have high fatigue wear resistance. The work of fracture found in nacre (mother of pearl) is several orders of magnitude larger than the ceramic (aragonite) it is made of. The organic protein layers in the composite play a significant role in the mechanical response of nacre to stress. In this study, we hope to understand if an energy absorbing interphase similar to that found in nacre could have potential for toughening traditional, glass-particle-reinforced polymer composites. A multi-scale finite element model (FEM) has been developed to study the interaction between the crack and the reinforced particles. In this model, crack nucleation and propagation and the effect of particle/matrix/interphase material properties can all be characterized by the cohesive element and its traction-separation behavior. Loss of load carrying capacity begins when local deformation reaches a certain value, leading to the degradation of the material. Completely degraded elements form a traction-free crack surface. The most important advantage of this methodology for modeling fracture behavior is that macroscopic fracture criteria are not needed. 3-point bending macro-scale FEM serves to calibrate the deformation gradient of the study zone in front of the crack tip. A microscopic unit cell model was used to simulate the crack propagation. Three types of interphase were compared: (1) matrix and particle bonded without interphase, (2) matrix and particle bonded with silane interphase, and (3) matrix and particle bonded with beta-peptide (highly stretchable) interphase. Results show that the stress distribution around the filler and the bulk mechanical properties of the composite can be affected by changes in interfacial properties. Particle-reinforced polymer composites with a more compliant and stretchable interphase (e.g. beta-peptide) will help absorb local strain energy while remaining intact, allowing less damage within the matrix. This type of interphase decreases crack propagation speed and results in an increase of fracture toughness.
Reports on the topic "Peptides – Effets du fer"
1
Wong, Eric A., and Zehava Uni. Nutrition of the Developing Chick Embryo: Nutrient Uptake Systems of the Yolk Sac Membrane and Embryonic Intestine. United States Department of Agriculture, June 2012. http://dx.doi.org/10.32747/2012.7697119.bard.
Full textAbstract:
We have examined the developmental changes in composition, amount, and uptake of yolk nutrients (fat, protein, water and carbohydrates) and the expression ofnutrient transporters in the yolk sac membrane (YSM) from embryonic day 11 (Ell) to 21 (E21) and small intestine from embryonic day 15 (E15) to E21 in embryos from young (22-25 wk) and old (45-50 wk) Cobb and Leghorn breeder flocks. The developmental expression profiles for the peptide transporter 1 (PepTl), the amino acid transporters, EAAT3, CAT-1 and BOAT, the sodium glucose transporter (SGLTl), the fructose transporter (GLUT5), the digestive enzymes aminopeptidase N (APN) and sucraseisomaltase (SI) were assayed by the absolute quantification real time PCR method in the YSM and embryonic intestine. Different temporal patterns of expression were observed for these genes. The effect of in ovo injection of peptides (the dipeptide Gly-Sar, purified peptides, trypsin hydrolysate) on transporter gene expression has been examined in the embryonic intestine. Injection of a partial protein hydrolysate resulted in an increase in expression of the peptide transporter PepT2. We have initiated a transcriptome analysis of genes expressed in the YSM at different developmental ages to better understand the function of the YSM.
2
Altstein, Miriam, and Ronald J. Nachman. Rational Design of Insect Control Agent Prototypes Based on Pyrokinin/PBAN Neuropeptide Antagonists. United States Department of Agriculture, August 2013. http://dx.doi.org/10.32747/2013.7593398.bard.
Full textAbstract:
The general objective of this study was to develop rationally designed mimetic antagonists (and agonists) of the PK/PBAN Np class with enhanced bio-stability and bioavailability as prototypes for effective and environmentally friendly pest insect management agents. The PK/PBAN family is a multifunctional group of Nps that mediates key functions in insects (sex pheromone biosynthesis, cuticular melanization, myotropic activity, diapause and pupal development) and is, therefore, of high scientific and applied interest. The objectives of the current study were: (i) to identify an antagonist biophores (ii) to develop an arsenal of amphiphilic topically active PK/PBAN antagonists with an array of different time-release profiles based on the previously developed prototype analog; (iii) to develop rationally designed non-peptide SMLs based on the antagonist biophore determined in (i) and evaluate them in cloned receptor microplate binding assays and by pheromonotropic, melanotropic and pupariation in vivo assays. (iv) to clone PK/PBAN receptors (PK/PBAN-Rs) for further understanding of receptor-ligand interactions; (v) to develop microplate binding assays for screening the above SMLs. In the course of the granting period A series of amphiphilic PK/PBAN analogs based on a linear lead antagonist from the previous BARD grant was synthesized that incorporated a diverse array of hydrophobic groups (HR-Suc-A[dF]PRLa). Others were synthesized via the attachment of polyethylene glycol (PEG) polymers. A hydrophobic, biostablePK/PBAN/DH analog DH-2Abf-K prevented the onset of the protective state of diapause in H. zea pupae [EC50=7 pmol/larva] following injection into the preceding larval stage. It effectively induces the crop pest to commit a form of ‘ecological suicide’. Evaluation of a set of amphiphilic PK analogs with a diverse array of hydrophobic groups of the formula HR-Suc-FTPRLa led to the identification of analog T-63 (HR=Decyl) that increased the extent of diapause termination by a factor of 70% when applied topically to newly emerged pupae. Another biostablePK analog PK-Oic-1 featured anti-feedant and aphicidal properties that matched the potency of some commercial aphicides. Native PK showed no significant activity. The aphicidal effects were blocked by a new PEGylated PK antagonist analog PK-dF-PEG4, suggesting that the activity is mediated by a PK/PBAN receptor and therefore indicative of a novel and selective mode-of-action. Using a novel transPro mimetic motif (dihydroimidazole; ‘Jones’) developed in previous BARD-sponsored work, the first antagonist for the diapause hormone (DH), DH-Jo, was developed and shown to block over 50% of H. zea pupal diapause termination activity of native DH. This novel antagonist development strategy may be applicable to other invertebrate and vertebrate hormones that feature a transPro in the active core. The research identifies a critical component of the antagonist biophore for this PK/PBAN receptor subtype, i.e. a trans-oriented Pro. Additional work led to the molecular cloning and functional characterization of the DH receptor from H. zea, allowing for the discovery of three other DH antagonist analogs: Drosophila ETH, a β-AA analog, and a dF analog. The receptor experiments identified an agonist (DH-2Abf-dA) with a maximal response greater than native DH. ‘Deconvolution’ of a rationally-designed nonpeptide heterocyclic combinatorial library with a cyclic bis-guanidino (BG) scaffold led to discovery of several members that elicited activity in a pupariation acceleration assay, and one that also showed activity in an H. zea diapause termination assay, eliciting a maximal response of 90%. Molecular cloning and functional characterization of a CAP2b antidiuretic receptor from the kissing bug (R. prolixus) as well as the first CAP2b and PK receptors from a tick was also achieved. Notably, the PK/PBAN-like receptor from the cattle fever tick is unique among known PK/PBAN and CAP2b receptors in that it can interact with both ligand types, providing further evidence for an evolutionary relationship between these two NP families. In the course of the granting period we also managed to clone the PK/PBAN-R of H. peltigera, to express it and the S. littoralis-R Sf-9 cells and to evaluate their interaction with a variety of PK/PBAN ligands. In addition, three functional microplate assays in a HTS format have been developed: a cell-membrane competitive ligand binding assay; a Ca flux assay and a whole cell cAMP ELISA. The Ca flux assay has been used for receptor characterization due to its extremely high sensitivity. Computer homology studies were carried out to predict both receptor’s SAR and based on this analysis 8 mutants have been generated. The bioavailability of small linear antagonistic peptides has been evaluated and was found to be highly effective as sex pheromone biosynthesis inhibitors. The activity of 11 new amphiphilic analogs has also been evaluated. Unfortunately, due to a problem with the Heliothis moth colony we were unable to select those with pheromonotropic antagonistic activity and further check their bioavailability. Six peptides exhibited some melanotropic antagonistic activity but due to the low inhibitory effect the peptides were not further tested for bioavailability in S. littoralis larvae. Despite the fact that no new antagonistic peptides were discovered in the course of this granting period the results contribute to a better understanding of the interaction of the PK/PBAN family of Nps with their receptors, provided several HT assays for screening of libraries of various origin for presence of PK/PBAN-Ragonists and antagonists and provided important practical information for the further design of new, peptide-based insecticide prototypes aimed at the disruption of key neuroendocrine physiological functions in pest insects.
3
Noga, Edward J., Angelo Colorni, Michael G. Levy, and Ramy Avtalion. Importance of Endobiotics in Defense against Protozoan Ectoparasites of Fish. United States Department of Agriculture, September 2003. http://dx.doi.org/10.32747/2003.7586463.bard.
Full textAbstract:
Infectious disease is one of the most serious causes of economic loss in all sectors of aquaculture. There is a critical need to understand the molecular basis for protection against infectious disease so that safer, more reliable and more cost-effective strategies can be designed for their control. As part of this effort, the major goal of our BARD project was to determine the importance of endobiotics as a defense against protozoan ectoparasites in fish. Endobiotics, or antimicrobial polypeptides, are peptides and small proteins that are increasingly recognized as having a vital role in the innate defense of virtually all animals. One objective of our BARD project was to determine the antiparasitic potency of one specific group of endobiotics that were isolated from hybrid striped bass (Morone saxatilis x M chrysops). We found that these endobiotics, which we had previously named histone-like proteins (HLPs), exhibited potent activity against Amyloodinium and that the putative levels of HLPs in the skin were well within the levels that we found to be lethal to the parasite in vitro. We also found evidence for the presence of similar antibiotics in sea bream (Sparus aurata) and Mediterranean sea bass (Dicentrarchus labrax). We also examined the effect of chronic stress on the expression of HLP in fish and found that HLP levels were dramatically decreased after only one week of a crowding/high ammonia sublethal stress. We also began to explore the feasibility of upregulating endobiotics via immunostimulation. However, we did not pursue this objective as fully as we originally intended because we spent a much larger effort than originally anticipated on the last objective, the attempted isolation of novel endobiotics from hybrid striped bass. In this regard, we purified and identified four new peptide endobiotics. These endobiotics, which we have named piscidins (from "Pisces" meaning fish), have potent, broad-spectrum activity against a number of both fish and human pathogens. This includes not only parasites but also bacteria. We also demonstrated that these peptides are present in the mast cell. This was the first time that the mast cell, the most common tissue granulocyte in vertebrates, was shown to possess any type of endobiotic. This finding has important implications in explaining the possible function of mast cells in the immune response of vertebrates. In summary, the research we have accomplished in this BARD project has demonstrated that endobiotics in fish have potent activity against many serious pathogens in aquaculture and that there is considerable potential to use these compounds as stress indicators in aquaculture. There is also considerable potential to use some of these compounds in other areas of medicine, including treatment of serious infectious diseases of humans and animals.
4
Luan, Sisi, Wenke Cheng, Chenglong Wang, Hongjian Gong, and Jianbo Zhou. Impact of glucagon-like peptide 1 analogs on cognitive function among patients with type 2 diabetes mellitus. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, June 2022. http://dx.doi.org/10.37766/inplasy2022.6.0015.
Full textAbstract:
Review question / Objective: Diabetes is an independent risk factor for cognitive impairment. Little is known regarding the neuroprotective effects of glucagon-like peptide 1 (GLP-1) analogs on type 2 diabetes mellitus (T2DM).Here, the study aim to assess the impact of GLP-1 on general cognition function among patients with T2DM. Eligibility criteria: Inclusion criteria were as follows: (1) an original article was recently published in English, (2) the population included subjects diagnosed with diabetes at baseline, (3) GLP-1 analogs is a single formulation rather than a fixed dose combination, (4) GLP-1 analogs were compared with no GLP-1 use or placebo or self-control before treatment, (5) the duration of antidiabetic agent use was 12 weeks or more, and (6) it provided quantitative measures of general cognitive function assessed by MMSE or MoCA. Exclusion criteria were as follows: (1) the publication was a review, case report, animal study, or letter to the editor, (2) the study did not clearly define clinical outcomes, (3) the authors could not provide valid data after being contacted, (4) duplicated data.
5
El Halawani, Mohamed, and Israel Rozenboim. Environmental factors affecting the decline in reproductive efficiency of turkey hens: Mediation by vasoactive intestinal peptide. United States Department of Agriculture, January 2007. http://dx.doi.org/10.32747/2007.7696508.bard.
Full textAbstract:
Reproductive failure associated with heat stress is a well known phenomenon in avian species. Increased prolactin (PRL) levels in response to heat stress have been suggested as a mechanism involved in this reproductive malfunction. To test this hypothesis, laying female turkeys were subjected to 40°C for 12 h during the photo-phase daily or maintained at 24–26°C. Birds in each group received oral treatment with parachlorophenyalanine (PCPA; 50 mg/kg BW/day for 3 days), an inhibitor of serotonin (5-HT) biosynthesis; or immunized against vasoactive intestinal peptide (VIP). Both treatments are known to reduce circulating PRL levels. Non treated birds were included as controls. In the control group, high ambient temperature terminated egg laying, induced ovarian regression, reduced plasma luteinizing hormone (LH) and ovarian steroids (progesterone, testosterone, estradiol) levels, and increased plasma PRL levels and the incidence of incubation behavior. Pretreatment with PCPA reduced (P< 0.05) heat stress-induced decline in egg production, increase in PRL levels, and expression of incubation behavior. Plasma LH and ovarian steroid levels of heat stressed birds were restored to that of controls by PCPA treatment. As in PCPA-treated birds, VIP immunoneutralization of heat-stressed turkeys reduced (P< 0.05) circulating PRL levels and prevented the expression of incubation behavior. But it did not restore the decline in LH, ovarian steroids, and egg production (P> 0.05). The present findings indicate that the detrimental effect of high temperature on reproductive performance may not be related to the elevated PRL levels in heat-stressed birds but to mechanism(s) that involve 5-HT neurotransmission and the induction of hyperthermia.
6
Matthew, Gray. Data from "Winter is Coming – Temperature Affects Immune Defenses and Susceptibility to Batrachochytrium salamandrivorans". University of Tennessee, Knoxville Libraries, January 2021. http://dx.doi.org/10.7290/t7sallfxxe.
Full textAbstract:
Environmental temperature is a key factor driving various biological processes, including immune defenses and host-pathogen interactions. Here, we evaluated the effects of environmental temperature on the pathogenicity of the emerging fungus, Batrachochytrium salamandrivorans (Bsal), using controlled laboratory experiments, and measured components of host immune defense to identify regulating mechanisms. We found that adult and juvenile Notophthalmus viridescens died faster due to Bsal chytridiomycosis at 14 ºC than at 6 and 22 ºC. Pathogen replication rates, total available proteins on the skin, and microbiome composition likely drove these relationships. Temperature-dependent skin microbiome composition in our laboratory experiments matched seasonal trends in wild N. viridescens, adding validity to these results. We also found that hydrophobic peptide production after two months post-exposure to Bsal was reduced in infected animals compared to controls, perhaps due to peptide release earlier in infection or impaired granular gland function in diseased animals. Using our temperature-dependent infection results, we performed a geographic analysis that suggested that N. viridescens populations in the northeastern United States and southeastern Canada are at greatest risk for Bsal invasion. Our results indicate that environmental temperature will play a key role in the epidemiology of Bsal and provide evidence that temperature manipulations may be a viable Bsal management strategy.
7
Shai, Yechiel, Arthur Aronson, Aviah Zilberstein, and Baruch Sneh. Study of the Basis for Toxicity and Specificity of Bacillus thuringiensis d-Endotoxins. United States Department of Agriculture, January 1996. http://dx.doi.org/10.32747/1996.7573995.bard.
Full textAbstract:
The report contains three parts which summarizes the three years achievements of the three participating research groups; The Weizmann group, Tel-Aviv group and Purdue group. The firs part describes the achievements obtained by Shai's group toward the elucidation of the mechanism of membrane insertion and the structural organization of the pores formed by the Cry3A and Cry1Ac B. thuringiensis d-endotoxins. For that purpose Shai's group synthesized, fluorescently labeled and structurally and functionally characterized peptides corresponding to the seven helices that compose the pore-forming domain of Cry3A toxin, including mutants peptides and the hairpin a4G-a5 of both Cry3A and Cry 1Ac toxins composed of a4, a5 and the loop connecting a4-a5. Among the synthesized peptides were three mutated a4 helices based on site directed mutagenesis done at Aronson's group that decreased or increased Cry 1Ac toxicity. The results of these studies are consistent with a situation in which only helices a4 anda5 insert into the membrane as a helical hairpin in an antiparallel manner, while the other helices lie on the membrane surface like ribs of an umbrella (the "umbrella model"). In order to test this model Shai's group synthesized the helical hairpin a4<-->a5 of both Cry3A and Cry 1 Ac toxins, as well. Initial functional and structural studies showed direct correlation between the properties of the mutated helices and the mutated Cry1Ac. Based on Shai's findings that a4 is the second helix besides a5 that insert into the membrane, Aronson and colleagues performed extensive mutation on this helix in the CrylAc toxin, as well as in the loop connecting helices 4 and 5, and helix 3 (part two of the report). In addition, Aronson performed studies on the effect of mutations or type of insect which influence the oligomerization either the Cry 1Ab or Cry 1Ac toxins with vesicles prepared from BBMV. In the third part of the report Zilberstein's and Sneh's groups describe their studies on the three domains of Cry 1C, Cry 1E and crylAc and their interaction with the epithelial membrane of the larval midgut. In these studies they cloned all three domains and combinations of two domains, as well as cloning of the pore forming domain alone and studying its interaction with BBMV. In addition they investigated binding of Cry1E toxin and Cry1E domains to BBMV prepared from resistant (R) or sensitive larvae. Finally they initiated expression of the loop a4G<-->a5 Cry3A in E. coli to be compared with the synthetic one done by Shai's group as a basis to develop a system to express all possible pairs for structural and functional studies by Shai's group (together with Y. Shai).
8
Eyal, Yoram, and Sheila McCormick. Molecular Mechanisms of Pollen-Pistil Interactions in Interspecific Crossing Barriers in the Tomato Family. United States Department of Agriculture, May 2000. http://dx.doi.org/10.32747/2000.7573076.bard.
Full textAbstract:
During the evolutionary process of speciation in plants, naturally occurring barriers to reproduction have developed that affect the transfer of genes within and between related species. These barriers can occur at several different levels beginning with pollination-barriers and ending with hybrid-breakdown. The interaction between pollen and pistils presents one of the major barriers to intra- and inter-specific crosses and is the focus of this research project. Our long-term goal in this research proposal was defined to resolve questions on recognition and communication during pollen-pistil interactions in the extended tomato family. In this context, this work was initiated and planned to study the potential involvement of tomato pollen-specific receptor-like kinases (RLK's) in the interaction between pollen and pistils. By special permission from BARD the objectives of this research were extended to include studies on pollen-pistil interactions and pollination barriers in horticultural crops with an emphasis on citrus. Functional characterization of 2 pollen-specific RLK's from tomato was carried out. The data shows that both encode functional kinases that were active as recombinant proteins. One of the kinases was shown to accumulate mainly after pollen germination and to be phosphorylated in-vitro in pollen membranes as well as in-vivo. The presence of style extract resulted in dephosphorylation of the RLK, although no species specificity was observed. This data implies a role for at least one RLK in pollination events following pollen germination. However, a transgenic plant analysis of the RLK's comprising overexpression, dominant-negative and anti-sense constructs failed to provide answers on their role in pollination. While genetic effects on some of the plants were observed in both the Israeli and American labs, no clear functional answers were obtained. An alternative approach to addressing function was pursued by screening for an artificial ligand for the receptor domain using a peptide phage display library. An enriched peptide sequence was obtained and will be used to design a peptide-ligand to be tested for its effect o pollen germination and tube growth. Self-incompatibility (SI) in citrus was studied on 3 varieties of pummelo. SI was observed using fluorescence microscopy in each of the 3 varieties and compatibility relations between varieties was determined. An initial screen for an S-RNase SI mechanism yielded only a cDNA homologous to the group of S-like RNases, suggesting that SI results from an as yet unknown mechanism. 2D gel electrophoresis was applied to compare pollen and style profiles of different compatibility groups. A "polymorphic" protein band from style extracts was observed, isolated and micro-sequenced. Degenerate primers designed based on the peptide sequence date will be used to isolate the relevant genes i order to study their potential involvement in SI. A study on SI in the apple cultivar Top red was initiated. SI was found, as previously shown, to be complete thus requiring a compatible pollinator variety. A new S-RNase allele was discovered fro Top red styles and was found to be highly homologous to pear S-RNases, suggesting that evolution of these genes pre-dated speciation into apples and pears but not to other Rosaceae species. The new allele provides molecular-genetic tools to determine potential pollinators for the variety Top red as well as a tool to break-down SI in this important variety.
9
Rafaeli, Ada, and Russell Jurenka. Molecular Characterization of PBAN G-protein Coupled Receptors in Moth Pest Species: Design of Antagonists. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7593390.bard.
Full textAbstract:
The proposed research was directed at determining the activation/binding domains and gene regulation of the PBAN-R’s thereby providing information for the design and screening of potential PBAN-R-blockers and to indicate possible ways of preventing the process from proceeding to its completion. Our specific aims included: (1) The identification of the PBAN-R binding domain by a combination of: (a) in silico modeling studies for identifying specific amino-acid side chains that are likely to be involved in binding PBAN with the receptor and; (b) bioassays to verify the modeling studies using mutant receptors, cell lines and pheromone glands (at tissue and organism levels) against selected, designed compounds to confirm if compounds are agonists or antagonists. (2) The elucidation ofthemolecular regulationmechanisms of PBAN-R by:(a) age-dependence of gene expression; (b) the effect of hormones and; (c) PBAN-R characterization in male hair-pencil complexes. Background to the topic Insects have several closely related G protein-coupled receptors (GPCRs) belonging to the pyrokinin/PBAN family, one with the ligand pheromone biosynthesis activating neuropeptide or pyrokinin-2 and another with diapause hormone or pyrokinin-1 as a ligand. We were unable to identify the diapause hormone receptor from Helicoverpa zea despite considerable effort. A third, related receptor is activated by a product of the capa gene, periviscerokinins. The pyrokinin/PBAN family of GPCRs and their ligands has been identified in various insects, such as Drosophila, several moth species, mosquitoes, Triboliumcastaneum, Apis mellifera, Nasoniavitripennis, and Acyrthosiphon pisum. Physiological functions of pyrokinin peptides include muscle contraction, whereas PBAN regulates pheromone production in moths plus other functions indicating the pleiotropic nature of these ligands. Based on the alignment of annotated genomic sequences, the primary and secondary structures of the pyrokinin/PBAN family of receptors have similarity with the corresponding structures of the capa or periviscerokinin receptors of insects and the neuromedin U receptors found in vertebrates. Major conclusions, solutions, achievements Evolutionary trace analysisof receptor extracellular domains exhibited several class-specific amino acid residues, which could indicate putative domains for activation of these receptors by ligand recognition and binding. Through site-directed point mutations, the 3rd extracellular domain of PBAN-R was shown to be critical for ligand selection. We identified three receptors that belong to the PBAN family of GPCRs and a partial sequence for the periviscerokinin receptor from the European corn borer, Ostrinianubilalis. Functional expression studies confirmed that only the C-variant of the PBAN-R is active. We identified a non-peptide agonist that will activate the PBAN-receptor from H. zea. We determined that there is transcriptional control of the PBAN-R in two moth species during the development of the pupa to adult, and we demonstrated that this transcriptional regulation is independent of juvenile hormone biosynthesis. This transcriptional control also occurs in male hair-pencil gland complexes of both moth species indicating a regulatory role for PBAN in males. Ultimate confirmation for PBAN's function in the male tissue was revealed through knockdown of the PBAN-R using RNAi-mediated gene-silencing. Implications, both scientific and agricultural The identification of a non-peptide agonist can be exploited in the future for the design of additional compounds that will activate the receptor and to elucidate the binding properties of this receptor. The increase in expression levels of the PBAN-R transcript was delineated to occur at a critical period of 5 hours post-eclosion and its regulation can now be studied. The mysterious role of PBAN in the males was elucidated by using a combination of physiological, biochemical and molecular genetics techniques.
10
Xie, Yunhui, and Peng Pang. A Systematic Review and Network Meta-Analysis: Effect of of GLP-1 drugs on weight loss in obese people. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, June 2022. http://dx.doi.org/10.37766/inplasy2022.6.0074.
Full textAbstract:
Review question / Objective: 1、Whether GLP-1 drugs have weight loss effect on obese people ? 2、Which GLP-1 drugs are most effective in weight loss among obese people ? Condition being studied: Obesity is an important public health issue that has been on the rise over the last decades. It calls for effective prevention and treatment. Bariatric surgery is the most effective medical therapy for weight loss in morbid obesity, but we are in need for less aggressive treatments. Glucagon-like-peptide-1 receptor agonists are a group of incretin-based drugs that have proven to be productive for obesity treatment. Through activation of the GLP-1 receptor they not only have an important role stimulating insulin secretion after meals, but with their extrapancreatic actions, both peripheral and central, they also help reduce body weight by promoting satiety and delaying gastric emptying.