Peptides reactivity

Bronchial Asthma. Figure 2 Mechanisms of bronchial hyperresponsiveness. Toxic products from eosinophils [cationic peptides, reactive oxygen species (ROS)] cause epithelial injury. Nerve endings become easily accessible to mediators from mast cells, eosinophils [eosinophil-derived neurotoxin (EDN)], and neutrophils, and to airborne toxicants such as S02. Activation of nerve endings stimulates effector cells like mucosal glands and airway smooth muscle either directly or by cholinergic reflexes. 

M. F. Powell, Peptide Stability in Drug Development In vitro Peptide Degradation in Plasma and Serum , Annu. Rep. Med. Chem. 1993, 28, 285-294 M. F. Powell, H. Grey, F. Gaeta, A. Sette, S. Colon, Peptide Stability in Drug Development a Comparison of Peptide Reactivity in Different Biological Media , J. Pharm. Sci. 1992, 81, 731-735. 

Gerberick, G.F., Vassallo, J.D., Foertsch, L.M., Price, B.B., Chaney, J.G. and Lepoittevin, J.P. (2007) Quantification of chemical peptide reactivity for screening contact allergens a classification tree model approach. Toocicological Sciences, 97, 417 27. 

Powell, M.F., Stewart, T., Otvos, L., Jr., et al. (1993) Peptide stability in drug development. II. Effect of single amino acid substitution and glycosylation on peptide reactivity in human serum. Pharmacol. Res. 10, 1268-1273. 

Reverse Prediction of antigen structure based on peptide reactivity with cytotoxic... 

Effects of interferon-a on cytokine profile, T cell receptor repertoire and peptide reactivity of human allergen-specific T cells. Eur J Immuno 1996 26 697-703. 

Hoekstra JB, Van Rijn HJ, Thijssen JH, Erkelens DW. C-peptide reactivity as a measure of msulin dependency in obese diabetic patients treated with insuhn. Diabetes Care 1982 5 585-91. 

In this procedure, a set of four isobaric amine-specific labeling reagents (114, 115, 116, or 117), consisting of a reporter group, a balance group, and a peptide-reactive group (e.g., N-hydroxy succinimide) are used to label... 

A prevalidation study carried out by Cosmetics Europe on this optimized protocol showed that the SkinEthic HCE method consistently discriminated UN GHS classified from non-classified test substances within and between laboratories [47]. A combination of the two exposure times in a testing strategy that allocates test substances to the short or long exposure time depending on their intrinsic chemical reactivity increased the overall accuracy under GHS. The chemical reactivity, i.e., electrophilic potential to react with cysteine- or lysine-containing peptides, was measured by the direct peptide reactivity assay (DPRA) [48]. Reactive substances (peptide depletion is >5.95 % relative to the control) were allocated to the short exposure time, whereas non-reactive substances (depletion <5.95 %) are allocated to the long exposure time. 

Advances in the understanding of the immunobiology of skin sensitization have led to the establishment of predictive in vivo tests which not only identify sensitizing hazards but also characterize their potency. Recently, appreciation of the underlying biology has also resulted in the development of mechanistically based in vitro alternatives which offer the prospect of the replacement of current in vivo methods. Assays under active validation include the Direct Peptide Reactivity Assay (DPRA), the human Cell Line Activation Test (h-CLAT), and KeratinoSens. None of the methods have a sufficient level of accuracy or freedom from applicability domain limitations to allow them to act as a standalone replacement. Consequently, it will be necessary to consider how to deploy these assays, perhaps in combination and/or in a structured assessment of skin sensitization hazard, to ensure at least the same level of predictive accuracy as the in vivo methods. However, a challenge remains the capacity of these methods to provide potency information on skin-sensitizing chemicals has yet to be assessed. This is an essential requirement for future risk assessment without use of animal models if we are to retain the same level of human health protection that is currently delivered. 

Key words Skin sensitization, Contact allergy, Allergic contact dermatitis, Local lymph node assay, In vitro alternatives, Direct peptide reactivity assay, KeratinoSens, Human cell line activation test... 

Extensive reviews concerning the opportunities for the development of in vitro sensitization methods already exist [41-44], These reviews show that essentially all of the methods address one or other of the key mechanistic steps in the induction of skin sensitization—and these are nicely represented in the OECD adverse outcome pathway description [45], From this large body of work, three methods have emerged whose initial promise has been substantiated by demonstration not only of their predictive merits but also by verification of their robustness in terms of inter-laboratory transferability and within and between laboratory reproducibility [46]. The three methods are the direct peptide reactivity assay (DPRA) [47, 48], KeratinoSens [49, 50], and the human Cell Line Activation Test (h-CLAT) [51-53]. The first of these, the DPRA, addresses the question of chemical reactivity, the second investigates an aspect of keratinocyte activation... 

Gerberick GF, Vassallo JD, Bailey RE, Chaney JG, Morrall SW, Lepoittevin JP (2004) Development of a peptide reactivity assay for screening contact allergens. Toxicol Sci 81 332-343... 

Jeong YH, An S, Shin K, Lee TR (2013) Peptide reactivity assay using spectrophoto-metric method for high-throughput screening of skin sensitization potential of chemical haptens. Toxicol In Vitro 27(1) 264-271... 

Gerberick GF, Troutman JA, Foertsch LM, Vassallo JD, Quijano M, Dobson RL, Goebel C, Lepoittevin JP (2009) Investigation of peptide reactivity of pro-hapten skin sensitizers using a peroxidase-peroxide oxidation system. Toxicol Sci 112 164-174... 

Troutman JA, Foertsch LM, Kern PS, Dai HJ, Quijano M, Dobson RL, Lalko JF, Lepoittevin JP, Gerberick GF (2011) The incorporation of lysine into the peroxidase peptide reactivity assay for skin sensitization assessments. Toxicol Sci 122 422-436... 

ECVAM (2015b) https //eurl-ecvam.jrc.ec.europa.eu/eurl-ecvam-recommendations/eurl-ecvam-recommendation-on-the-direct-peptide-reactivity-assay-dpra (accessed on October 14, 2015). 

Besides the discovery of new peptides, the routine investigation of peptide influence and metabolism requires a separations-based techifique. Biologically active peptides are numerous. They are all synthesized in the same general way. Transcription and translation leads to prepropeptides [3]. These proteins may be the source of several different active peptides. Specific enzymes are nsed to create first the propeptide and then active peptides. Active peptides are then inactivated, usually by a peptidase that hydrolyses an amide bond in the peptide [4]. It is therefore certain that a large number of different molecules share the same primary sequence, and it is likely that a large number of molecules may cross-react with a peptide-reactive antibody. Thus, any immunoassay is bedeviled by selectivity issues. If a perfectly selective antibody were available, it would be useful. However, it is undeniable that ultimately a complete understanding of, for example, the action of peptides in the brain [3-5] will only come about when the dynamics of all of the relevant processes are understood. This can only be done with chemical analytical techniques that can track the concentrations of all of the peptides relevant to a particular process. 

To improve statistics, in both length of time and system size, the QM part can be treated by employing semi-empirical HamiltCMiians. In this way, it was possible to study peptide reactivity, as done by Hase and co-workers for reactivity of N-protonated glycine [186] in both CID and SID, suggesting that nraistatistical fragmentation dynamics may be important in the collisional dissociation of protonated amino acids and peptides. In this study the CID impact parameter was set to... 

Natsch, A. Gfeller, H. LC-MS-based characterization of the peptide reactivity of chemicals to improve the in vitro prediction of the skin sensitization potential. Toxicol. Sci. 2008, 106,464-478. 

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