Analysis of the Local Lymph Node Assay (LLNA) variability for assessing the prediction of skin sensitisation potential and potency of chemicals with non-animal approaches

The knowledge of the biological mechanisms leading to the induction of skin sensitisation has favoured in recent years the development of alternative non-animal methods. During the formal validation process, results from the Local Lymph Node Assay (LLNA) are generally used as reference data to assess the predictive capacity of the non-animal tests. This study reports an analysis of the variability of the LLNA for a set of chemicals for which multiple studies are available and considers three hazard classification schemes: POS/NEG, GHS/CLP and ECETOC. As the type of vehicle used in a LLNA study is known to influence to some extent the results, two analyses were performed: considering the solvent used to test the chemicals and without considering the solvent. The results show that the number of discordant classifications increases when a chemical is tested in more than one solvent. Moreover, it can be concluded that study results leading to classification in the strongest classes (1A and EXT) seem to be more reliable than those in the weakest classes. This study highlights the importance of considering the variability of the reference data when evaluating non-animal tests.     

Accounting for data variability,a key factor in in vivo/in vitro relationships: application to the skin sensitization potency (in vivo LLNA versus in vitro DPRA) example

When searching for alternative methods to animal testing, confidently rescaling an in vitro result to the corresponding in vivo classification is still a challenging problem. Although one of the most important factors affecting good correlation is sample characteristics, they are very rarely integrated into correlation studies. Usually, in these studies, it is implicitly assumed that both compared values are error‐free numbers, which they are not. In this work, we propose a general methodology to analyze and integrate data variability and thus confidence estimation when rescaling from one test to another. The methodology is demonstrated through the case study of rescaling the in vitro Direct Peptide Reactivity Assay (DPRA) reactivity to the in vivo Local Lymph Node Assay (LLNA) skin sensitization potency classifications. In a first step, a comprehensive statistical analysis evaluating the reliability and variability of LLNA and DPRA as such was done. These results allowed us to link the concept of gray zones and confidence probability, which in turn represents a new perspective for a more precise knowledge of the classification of chemicals within their in vivo OR in vitro test. Next, the novelty and practical value of our methodology introducing variability into the threshold optimization between the in vitro AND in vivo test resides in the fact that it attributes a confidence probability to the predicted classification. The methodology, classification and screening approach presented in this study are not restricted to skin sensitization only. They could be helpful also for fate, toxicity and health hazard assessment where plenty of in vitro and in chemico assays and/or QSARs models are available. Copyright © 2016 John Wiley & Sons, Ltd.     

ICCVAM Evaluation of the Murine Local Lymph Node Assay: I. The ICCVAM Review Process

New test methods are being developed to improve the prediction of human and environmental risks and to benefit animal welfare by reducing, refining, and replacing animal use. Regulatory adoption of new test methods is often a complex and protracted process, requiring test method validation, regulatory acceptance, and implementation. Assessments of new test methods have not always been uniform within or among regulatory agencies. Thus, there have been increased pressures for a harmonized approach to test method evaluation and acceptance. In 1997, in response to these pressures and to U.S. Public Law 103-43, the National Institute of Environmental Health Sciences (NIEHS) established the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) to coordinate interagency consideration of new and revised test methods. This article describes the validation and acceptance criteria and process used for the first test method evaluated by ICCVAM, the murine local lymph node assay (LLNA). Based on ICCVAM's conclusions and recommendations, the LLNA has been accepted by U.S. regulatory agencies as a stand-alone assay for allergic contact dermatitis. Two related articles in this series of three present the results of the independent peer review evaluation of the LLNA and summarize the performance characteristics of the database substantiating the validity of the LLNA.     

The regulatory use of the Local Lymph Node Assay for the notification of new chemicals in Europe

The regulatory use of the Local Lymph Node Assay (LLNA) for new chemicals registration was monitored by screening the New Chemicals Database (NCD), which was managed by the former European Chemicals Bureau (ECB) at the European Commission Joint Research Centre (JRC). The NCD centralised information for chemicals notified after 1981, where toxicological information has been generated predominantly according to approved test methods. The database was searched to extract notifications for which the information for skin sensitisation labelling was based on results derived with the LLNA. The details of these records were extracted and pooled, and evaluated with regard to the extent of use of the LLNA over time, as well as for analysing the information retrieved on critical aspects of the procedure e.g. strain and amount of animals used, lymph node processing, solvent and doses selected, stimulation indices, and for assessing their level of compliance to the OECD Test Guideline 429. In addition the accuracy of the reduced LLNA when applied to new chemicals was investigated.     

局部淋巴结试验与局部封闭斑贴试验应用于化妆品皮肤变态反应评价的比较

目的 通过局部淋巴结试验法和局部封闭斑贴试验应用于化妆品皮肤变态反应的比较,探讨局部淋巴结试验应用于化妆品成品的可行性.方法 采用局部淋巴结试验与体内局部封闭斑贴试验对标准的阳性物以及市面上的2种染发剂进行评价.结果 局部淋巴结试验表明,2种染发剂的SI值＜1.8,均为阴性,判断结果与局部封闭斑贴试验结果一致.结论 局...     

Applicability of the proposed GHS subcategorization criterion for LLNA:BrdU-ELISA (OECD TG442B) to the CBA/J strain mouse

The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is a hazard classification and communication system for providing information on the safe handling of chemicals worldwide. In this study, we evaluated the applicability of the newly proposed GHS subcategorization criterion for murine local lymph node assay:2-bromodeoxyuridine enzyme-linked immunosorbent assay (LLNA:BrdU-ELISA), Category 1A:EC1.6 ≤6%, Category 1B:EC1.6 >6%, to data derived from LLNA:BrdU-ELISA performed in the CBA/J strain mouse. Fifteen chemicals categorized in GHS hazard Category 1 sensitizers listed in the LLNA performance standard were tested by LLNA:BrdU-ELISA in the CBA/J strain mouse and were classified according to the new criterion. The results revealed that all of the GHS 1A or 1B category chemicals classified according to the EC3 values derived from radioisotopic LLNA (LLNA-RI) could be correctly assigned into the respective 1A and 1B categories using the newly proposed GHS subclassification criterion. In addition, analysis of the correlation between the reported EC3 values and EC1.6 values derived from the LLNA:BrdU-ELISA performed in the CBA/J strain mouse confirmed the existence of a strong correlation (r = 0.9076, P < .0001). These findings suggest that the newly proposed GHS subcategorization criterion for LLNA:BrdU-ELISA is potentially applicable for practical use in GHS subcategorization.     

ICCVAM Evaluation of the Murine Local Lymph Node Assay: III. Data Analyses Completed by the National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods

To evaluate the reliability of the murine local lymph node assay (LLNA), a test for allergic contact dermatitis activity, the inter- and intralaboratory consistency statistics (h and k, respectively) were calculated for validation studies testing multiple chemicals. The analysis indicated the absence of excessive variability in the dose calculated to induce a threefold or greater increase in the stimulation index (SI). To assess the appropriateness of using an SI of 3 as the decision criteria for identifying a sensitizing compound, LLNA results based on SI values of 2.0, 2.5, 3.0, 3.5, and 4.0 were compared with guinea pig or human results. The results supported the use of an SI of 3 as the decision criteria. Assay performance was determined by comparing LLNA results to results obtained for guinea pigs or humans. The accuracy of the LLNA was 89% when compared with results from the guinea pig maximization test (GPMT)/Buehler assay (BA). The performance of the LLNA and the GPMT/BA was similar when each was compared to human maximization test results plus substances included as human patch test allergens. The LLNA offered advantages over the GPMT in respect to both the time required to conduct the test and the assay cost.     

Comparison of the skin sensitizing potential of unsaturated compounds as assessed by the murine local lymph node assay (LLNA) and the guinea pig maximization test (GPMT)

The skin sensitization potential of eight unsaturated and one saturated lipid (bio)chemicals was tested in both the LLNA and the GPMT to address the hypothesis that chemicals with unsaturated carbon–carbon double bonds may result in a higher number of unspecific (false positive) results in the LLNA compared to the GPMT. Seven substances (oleic acid, linoleic acid, linolenic acid, undecylenic acid, maleic acid, squalene and octinol) gave clear positive results in the LLNA (stimulation index (SI)  3) and thus would require labelling as skin sensitizer. Fumaric acid and succinic acid gave clearly negative results. In the GPMT, besides some sporadic skin reactions, reproducible skin reactions indicating an allergic response were found in a few animals for four test substances. Based on the GPMT results, only undecylenic acid would have to be classified and labelled as a skin sensitizer according to the European Dangerous Substance Directive (67/548/EEC) (results for linoleic acid were inconclusive), while the other seven test substances would not require labelling. Possible mechanisms for unspecific skin cell stimulation and lymph node responses are discussed. In conclusion, the suitability of the LLNA for unsaturated compounds bearing structural similarity to the tested substances should be carefully considered and the GPMT should remain available as an accepted test method for skin sensitization hazard identification.     

角质细胞生长因子－2（KGF－2）研究进展

角质细胞生长因子－2（KGF－2）能够特异性促进上皮细胞的增殖、分化和迁移,增强细胞合成的能力,因而在治疗皮肤损伤及溃疡、美容等方面有多重应用,为当前国际细胞因子药物开发的热点。本文对KGF－2的分子结构和性质、生物学功能、受体、表达及纯化条件优化、稳定性等方面进行综述。     

食管癌根治术后纵膈淋巴结转移三维适形小野放疗临床观察

目的探讨食管癌根治术后纵隔淋巴结转移三维适形放射治疗的临床疗效,分析治疗失败的原因及局部小野放疗的可行性。方法回顾性分析45例食管癌根治术后纵隔淋巴结转移的患者,采用三维适形小野放射治疗,GTV处方剂量64Gy,CTV处方剂量50Gy,常规分割;GTV外放1．0～1．5cm为CTV,其他无转移部位不予预防性照射。放疗后3个月行CT检查,按WHO实体瘤疗效评价标准评估临床疗效。结果治疗的总有效率为73．3％,完全缓解率为33．3％,中位生存时间为16．7月;治疗过程中无明显毒副反应。结论对于食管癌根治术后纵隔淋巴结转移的患者,三维适形放射治疗是较好的治疗手段。     

Air classifier technology (ACT) in dry powder inhalation. Part 2. The effect of lactose carrier surface properties on the drug-to-carrier interaction in adhesive mixtures for inhalation

The effect of carrier surface properties on drug particle detachment from carrier crystals during inhalation with a special test inhaler with basic air classifier has been studied for mixtures containing 0.4% budesonide. Carrier crystals were retained in the classifier during inhalation and subsequently examined for the amount of residual drug (carrier residue: CR). Carrier surface roughness and impurity were varied within the range of their appearance in standard grades of lactose (Pharmatose 80, 100, 110, 150 and 200 M) by making special sieve fractions. It was found that roughness and impurity, both per unit calculated surface area (CSA), tend to increase with increasing mean fraction diameter for the carrier. Drug re-distribution experiments with two different carrier sieve fractions with distinct mean diameters showed that the amount of drug per CSA (drug load) in the state of equilibrium is highest for the coarsest fraction. This seems to confirm that surface carrier irregularities are places where drug particles preferentially accumulate. However, a substantial increase in surface roughness and impurity appears to be necessary to cause only a minor increase in CR at an inspiratory flow rate of 30 l/min through a classifier. At 60 l/min, CR is practically independent of the carrier surface properties. From the difference in CR between 30 and 60 l/min, it has been concluded that particularly the highest adhesive forces (for the largest drug particles) in the mixture are increased when coarser carrier fractions (with higher rugosity) are used. Not only increased surface roughness and impurities may be responsible for an increase in the adhesive forces between drug and carrier particles when coarser carrier fractions are used, but also bulk properties may play a role. With increasing mean carrier diameter, inertial and frictional forces during mixing are increased too, resulting in higher press-on forces with which the drug particles are attached to carrier crystals and to each other.     

The STEP (Safety and Toxicity of Excipients for Paediatrics) database. Part 1-A need assessment study

Excipients that are commonly used in adult medicines have been associated with elevated toxicological risks and safety issues in children. However, the information available on their acceptability for paediatric age groups is sparse and distributed over various sources. Hence, European (Eu) and United States (US) Paediatric Formulation Initiatives (PFIs) are collaboratively creating a STEP database. Because the development of database is a costly and time consuming venture, it is important to capture the requirements from the potential users and identify at an early stage the content and features that will serve the specific needs so that they can incorporate into the databases as it is developed.     

Synthesis and SAR studies for the inhibition of TNF-alpha production. Part 2. 2-[3-(Cyclopentyloxy)-4-methoxyphenyl]-substituted-1-isoindolinone derivatives

This study describes the synthesis and in vitro evaluation of 2-[3-(cyclopentyloxy)-4-methoxyphenyl]-1-isoindolinone derivatives substituted on benzene moiety of isoindoline ring for the inhibition of TNF-alpha production. From this study, we have found the 6-C position on isoindolinone ring is an optimal derivatization site. Among the compounds synthesized, 6-amino-2-[3-(cyclopentyloxy)-4-methoxyphenyl]-1-isoindolinone (6) was the most potent in inhibitory activity of TNF-alpha production in LPS-stimulated RAW264.7 cells.     

Comparison of the potency of MDL 100,907 and SB 242084 in blocking the serotonin (5-HT)(2) receptor agonist-induced increases in rat serum corticosterone concentrations: evidence for 5-HT(2A) receptor mediation of the HPA axis.

Direct-acting serotonin (5-HT) receptor agonists increase serum corticosterone in rats by activating receptors of the 5-HT(1A) or the 5-HT(2A/2C) subtypes. While involvement of 5-HT(1A) receptors in activation of the hypothalamic-pituitary-adrenocortical (HPA) axis is clear, the 5-HT(2) receptor subtype--5-HT(2A) or 5-HT(2C)--responsible for activation of the HPA axis by direct-acting 5-HT(2) receptor agonists has been difficult to determine due to the lack of selective pharmacologic agents. Recently, however, 5-HT(2) receptor antagonists with high selectivity for 5-HT(2A) and 5-HT(2C) receptor subtypes have been discovered. The selective 5-HT(2A) receptor antagonist MDL 100,907 and the selective 5-HT(2C) receptor antagonist SB 242084 were used to block the increases in rat serum corticosterone elicited by 5-HT(2) receptor agonists with varying degrees of affinity for 5-HT(2A) and 5-HT(2C) receptors. MDL 100,907 was fully effective in blocking the increases in corticosterone concentrations produced by quipazine, DOI, m-CPP and Ro 60-0175, whereas SB 242084 was ineffective or was only marginally effective. Our findings implicate 5-HT(2A) receptors rather than 5-HT(2C) receptors in mediating increases in rat serum corticosterone produced by direct-acting 5-HT(2) receptor agonists in vivo.     

Relationships Between the Chemical Structure of Antimycobacterial Substances and Their Activity Against Atypical Strains. Part 14: 3-Aryl-6,8-dihalogeno-2H-1,3-benzoxazine-2,4(3H)-diones

A set of eight derivatives of 6,8-dichloro-3-phenyl-2H-benzoxazine-2,4(3H)-dione and nine derivatives of 6,8-dibromo-3-phenyl-2H-1,3-benzoxazine-2,4(3H)-dione, substituted on the phenyl ring, was prepared by the reaction of the corresponding salicylanilides with ethyl chloroformate. The compounds were evaluated in vitro for antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium kansasii, and Mycobacterium avium. Their activity increases with increasing hydrophobicity and electron-withdrawing ability of the substituents on the phenyl ring.     

The selectivity of the (-)-and (+)-forms of hyoscine methiodide and of hyoscyamine camphorsulphonate for muscarinic (M2) receptors.

The affinities of (-)-S-hyoscyamine (+)-camphorsulphonate, (+)-R-hyoscyamine (-)-camphorsulphonate, (-)-S-hyoscine methiodide and (+)-R-hyoscine methiodide for muscarinic acetylcholine receptors in guinea-pig atria and ileum at 30 degrees C and in ileum at 37 degrees C have been measured in dose-ratio experiments. The agonists were carbachol, arecaidine propargyl ester (APE) and ethoxyethyl trimethylammonium iodide (EOE). The effects produced by the agonists confirmed that, relative to carbachol, arecaidine propargyl ester is more active on atria than on ileum whereas ethoxyethyl trimethylammonium iodide is more active on ileum than on atria. There was no striking difference between estimates of affinity based on the effects of agonists on atrial size and the effects on atrial rate nor was there any striking difference between the affinities measured with the different agonists. With the isomers of hyoscyamine there was no striking difference between the affinity for receptors in atria and those in ileum, which is consistent with the low selectivity reported for atropine (racemic hyoscyamine). (-)-S-Hyoscine methiodide had greater affinity for muscarinic receptors in ileum than for those in atria, though the difference is smaller than has been previously observed. (+)-R-Hyoscine methiodide had no detectable selectivity. The phenomenon of selectivity cannot be wholly ascribed to differences in physiochemical properties of the antagonists: the three-dimensional structures with which the antagonists interact cannot be identical.     

Chiral Amines Derived from 2-Arylpropionic Acids: Novel Reagents for the Liquid Chromatographic (LC) Fluorescence Assay of Optically Active Carboxylic Acid Xenobiotics

For the enantiospecific analysis of optically active carboxylic acids, the availability of readily detectable coupling components is desirable, but highly fluorescent chiral amines are rare. From activated enantiomers of fluorescent 2-arylpropionic acids fluorescent chiral amines were synthesized via Curtius degradation, i.e., under formation of the acyl azide, the isocyanate, and finally, the amine. The formation of isocyanates and of amine hydrochlorides led to an inversion of the direction of rotation of polarized light. Amines derived from R- and S-flunoxaprofen, R- and S-naproxen, and R/S-benoxaprofen were characterized. The amines were found to be applicable for the chiral separation of carboxylic acids (such as 2-arylpropionic acids) as diastereomeric derivatives via high-performance liquid-chromatographic (normal and reversed-phase) and thin-layer chromatographic techniques.