On the skin sensitisation potential of rosin and oxidised rosin

In the EU rosin is classified as a skin sensitiser, apparently on the basis of its oxidation to sensitising agents. Rosin (gum, tall oil or wood) is not a skin sensitiser when examined in the guinea pig maximisation test (GPMT). Oxidised rosins are sensitisers in the GPMT. Oxidised gum rosin was further tested in the mouse local lymph node assay (LLNA) and the Buehler test, but is not a sensitiser in either of these tests. Further, the outcome of the LLNA can be used to assess the potency of oxidised rosin as an inducing agent in humans, and oxidised rosin is, at most, a weak sensitiser in this test. Thus, oxidised rosin is not a potent inducing agent for skin sensitisation unless the dermal barrier is bypassed and/or there is deliberate use of Freund’s Complete Adjuvant to induce greater susceptibility.The material used for human patch testing (‘colophony’) is in oxidised form. A re-examination of epidemiological studies suggests that patients in dermatological clinics show higher response rates than do the general population or those occupationally exposed to presumably oxidised rosin. Thus, the differences seen in susceptibility in the regulatory tests may be reflected in the human population.These results are discussed in terms of possible testing and classification strategies for dealing with existing chemicals, with particular reference to the new European Union legislation.     

Assessing the potency of respiratory allergens: uncertainties and challenges

In contrast to skin sensitisation, there are no accepted tests for the identification of chemicals or proteins with the potential to cause sensitisation of the respiratory tract. Although progress has been made, the assessment of respiratory sensitisation potential remains associated with significant challenges and uncertainties. Nevertheless, there is interest in determining whether it is possible to assess the relative potency of respiratory sensitisers. The second Adaptation to Technical Progress (ATP) to the EU Classification, Labelling and Packaging (CLP) Regulation recently introduced changes to criteria for classification and labelling of chemicals and preparations, bringing it in line with the 3rd revision to the UN Globally Harmonised System of Classification and Labelling of Chemicals (GHS). Among other things, the second ATP introduces sub-categories for respiratory and skin sensitisers, discriminating between strong sensitisers and other sensitisers. Here we examine whether such categorisation of protein and/or chemical respiratory allergens is realistic and/or feasible. For this purpose comparisons have been drawn with skin sensitisation, where potency categorisation has now been widely accepted and successfully integrated into the regulatory process. The conclusion drawn is that, on the basis of the currently available information, potency categorisation for respiratory sensitisers is premature and could potentially be misleading.     

Categorisation of protein respiratory allergens: The case of Subtilisin

Characterisation of the relative sensitizing potency of protein and chemical allergens remains challenging, particularly for materials causing allergic sensitization of the respiratory tract. There nevertheless remains an appetite, for priority setting and risk management, to develop paradigms that distinguish between individual respiratory allergens according to perceptions of the hazards and risks posed to human health. One manifestation thereof is recent listing of certain respiratory allergens as Substances of Very High Concern (SVHC) under the provisions of REACH (Registration, Evaluation, Authorisation and restriction of Chemicals). Although priority setting is a laudable ambition, it is important the process is predicated on evidence-based criteria that are transparent, understood and owned. The danger is that in the absence of rigorous criteria unwanted precedents can be created, and confidence in the process is compromised. A default categorisation of sensitisers as SVHC requiring assessment under the authorisation process is not desirable. We therefore consider here the value and limitations of selective assignment of certain respiratory allergens as being SVHC. The difficulties of sustaining such designations in a sound and equitable way is discussed in the context of the challenges that exist with respect to assessment of potency, and information available regarding the effectiveness of exposure-based risk management.     

变应性鼻炎吸入物过敏原皮肤点刺试验结果分析

目的探讨过敏性鼻炎即变应性鼻炎即变应性鼻炎（AR）常见吸入物过敏原,为AR的特异性诊断、治疗和预防提供重要依据。方法应用北京新华联协和药业生产的过敏原点刺液,对156例AR患者实施18种吸入物过敏原皮肤点刺试验。结果单项吸入物过敏原阳性检出量共计504项次,其中,皮试阳性率最高的前8位过敏原依次是户尘螨、粉尘螨、室内尘土、荇草、大籽蒿、英国梧桐、蟑螂、豚草,其单项阳性检出量之和占吸入组过敏原总阳性检出量的90．2％。户尘螨阳性例数最多,阳性率80．8％;粉尘螨次之,阳性率78．2％;养麦壳阳性率最低,仅占1．3％。产黄青霉和圆柏花粉在本组患者中未检出阳性病例。尘螨过敏原皮试阳性率明显高于其它过敏原（x2检验,P〈0．01）。结论尘螨是AR最常见的过敏原,皮肤点刺试验（SPT）明确过敏原为AR特异性诊断、治疗和预防提供了有力证据。     

Induced changes in total serum IgE concentration in the Brown Norway rat: potential for identification of chemical respiratory allergens.

A variety of chemicals can cause sensitization of the respiratory tract and occupational asthma that may be associated with IgE antibody production. Topical exposure to chemical respiratory allergens such as trimellitic anhydride (TMA) has been shown previously to induce increases in the total serum concentration of IgE in BALB/c strain mice. Contact allergens such as 2,4-dinitrochlorobenzene (DNCB), which apparently lack respiratory sensitizing potential, fail to provoke similar changes. However, it became apparent with time that there was some inter-animal variation in constitutive and inducible IgE levels. We have now examined the influence of topical exposure to TMA and DNCB on serum IgE levels in the Brown Norway (BN) rat. Such animals can be bled serially and thus it is possible to perform longitudinal analyses of changes in serum IgE concentration. The kinetics of IgE responses therefore can be followed on an individual animal basis, allowing discrimination between transient and sustained increases in serum IgE concentration. Rats (n = 5) were exposed on shaved flanks to 50% TMA, to 1% DNCB (concentrations that elicit comparable immune activation with respect to draining lymph node cellularity and proliferation) or to vehicle alone. Total IgE was measured by enzyme-linked immunosorbent assay in serum samples taken prior to and 14-42 days following initial exposure. Those animals having high pre-existing IgE levels (>1.0 microg ml(-1)) were excluded from subsequent analyses. The levels of serum IgE in the majority of rats exposed to DNCB or vehicle alone remained relatively stable throughout the duration of all the experiments conducted, although some animals displayed transient increases in serum IgE. Only TMA treatment was associated with a significant and sustained increase in the level of serum IgE in the majority of experiments. The elevated concentrations of IgE induced by topical exposure to TMA are persistent, the results reported here demonstrating that induced changes in IgE are maximal or near maximal at approximately 35 days, with a significant increase in IgE demonstrable for at least 42 days following the initiation of exposure. Interestingly, although TMA and DNCB at the test concentrations used were found to be of comparable overall immunogenicity with regard to lymph node activation and the induction of lymph node cell proliferation, there were apparent differences in humoral immune responses. Thus, not only did exposure to TMA stimulate increases in total serum IgE concentration and the production of specific IgE antibody, but also a more vigorous IgG antibody response was provoked by TMA compared with DNCB. These data suggest that the measurement of induced changes in serum IgE concentration in the BN strain of rat is able to differentiate between different classes of chemical allergen. Given the inter-animal variation in IgE production, it would be prudent to incorporate a concurrent assessment of responses induced by treatment with TMA as a positive control against which to assess the activity of other test materials.     

Methods for the identification of chemical respiratory allergens in rodents: comparisons of cytokine profiling with induced changes in serum IgE

No validated or widely recognized test methods are currently available for the prospective identification of chemicals with the potential to cause respiratory allergy. The cellular and molecular mechanisms that result in the induction of chemical sensitization of the respiratory tract are unclear, although there is evidence for the selective development of T helper 2 (Th2)-type responses and, in some cases, the production of IgE antibody. We have therefore examined the utility of cytokine profiling using BALB/c mice, together with the measurement of induced increases in the total serum concentration of IgE in the Brown Norway (BN) rat, as markers for the prospective identification of chemical respiratory allergens. Responses provoked by the reference respiratory allergen trimellitic anhydride (TMA) have been compared with those stimulated by the respiratory sensitizing diisocyanates toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) and by the acid anhydride hexahydrophthalic anhydride (HHPA). Topical exposure of BN rats to TMA, TDI and HHPA each provoked marked immune activation (increases in lymph node cellularity and proliferation). However, only treatment with TMA stimulated vigorous increases in the total serum concentration of IgE. In contrast, exposure to HHPA, TDI or HDI failed to provoke significant changes in serum IgE concentration or induced only transient and relatively weak increases in serum IgE levels. In parallel experiments using BALB/c strain mice, however, topical application of all four chemical respiratory allergens provoked a marked Th2-type cytokine secretion profile in draining lymph node cells. These data suggest that the measurement of induced changes in serum IgE is not sufficiently sensitive for the robust identification of chemical respiratory allergens. Furthermore, irrespective of the reasons for variations in TMA-induced IgE production among BN rats, doubts remain regarding the utility of these animals for the characterization of immune responses to chemical allergens. Cytokine profiling using the BALB/c strain mouse apparently provides a more robust method for the hazard assessment of chemical respiratory allergens.     

Guinea pig maximisation test for skin sensitisation: the use of fewer test animals

Current European Community (Annex V) guidelines recommend the use of 20 test animals in the guinea pig maximisation test for skin sensitisation. The suitability, for classification and labelling purposes, of reducing the number of test animals has been examined by analysing the results of 40 studies submitted to the Health and Safety Executive, and by the use of a mathematical model. Our results suggest that in most cases an experiment with ten test animals can be used to determine satisfactorily whether a substance should be labelled with the risk phrase may cause sensitisation by skin contact. However, serious consideration should be given to the need for additional investigation if two or three of the ten test animals show a sensitisation response. The highest nonirritant concentration of a substance should be used at challenge. Clearer guidance in Annex V on evaluating challenge responses would be beneficial.     

Efficacy of predictive modeling as a scientific criterion in dermal hazard identification for assignment of skin notations

Skin notations (SNs) represent a hazard characterization tool for alerting workers of health hazards associated with dermal contact with chemicals. This study evaluated the efficacy of a predictive model utilized by the National Institute for Occupational Safety and Health to identify dermal hazards based on potential of systemic absorption compared to hazard assignments based on dermal lethal dose 50% or logarithm of octanol-water partition coefficient. A total of 480 chemicals assigned an SN from at least one of seven institutes were selected and partitioned into seven hazard categories by frequency of SN assignment to provide a basis of evaluation for the predictivity of the examined criteria. We find that all three properties serve as a qualitative indicator in support of a dichotomous decision on dermal hazard; the predictive modeling was identified from a multiple regression analysis as the most significant indicator. The model generated estimates that corresponded to anticipated hazard potentials, suggesting a role of the model to further serve as a hazard-ranking tool. The hazard-ranking capability of the model was consistent with the scheme of acute toxicity classification in the Globally Harmonized System of Classification and Labeling of Chemicals.     

Application of a weight of evidence approach to assessing discordant sensitisation datasets: Implications for REACH

The local lymph node assay (LLNA) is the assay of choice in European regulatory toxicology. As with other toxicology/sensitisation assays, it has a potential for false results, the anionic surfactant sodium lauryl sulphate (SLS) representing a classic example. In the work reported here, examples of false positives in the LLNA are compared to published “benchmarks” such as SLS. Clear false positives (e.g. oleic acid) are also contrasted with examples where data interpretation is more challenging. As the LLNA will be applicable to >30,000 chemicals under REACH, and in the light of animal welfare considerations to do no more than the absolute minimum of animal testing, results from a single LLNA often represent the only available data on sensitisation. This reinforces the need to ensure data from this assay are interpreted intelligently, using scientific analysis of results and considering the weight of evidence, before decisions are made on which substances should be classified as representing a skin sensitisation hazard. In chemical classes where the LLNA has been shown to be an inappropriate assay other standardised methods (e.g. the Buehler or Magnusson and Kligman guinea pig tests [OECD 406]) should be employed as the first choice assays.     

Risk assessment of local dermal effects and skin sensitisation under the EU Chemicals Regulation REACH: a proposal for a qualitative, exposure scenario specific, approach

Within the framework of REACH, an assessment regarding local dermal effects and skin sensitisation should be performed for substances. Quantitative hazard information for these effects is often not available. Furthermore, it is difficult to relate the way in which animals are exposed in dermal toxicity studies directly to dermal exposure in practice. In the absence of quantitative information, a qualitative assessment for dermal effects is the most reasonable option. The qualitative approach as proposed in the REACH guidance recommends only general risk management measures (RMM) for three categories with a low, moderate and high identified hazard, without specifying which RMM are needed for a specific exposure scenario. We propose to differentiate frequency of exposure based on differences in activities and to compare measured and estimated local skin exposure levels with rules of thumb for evaluation of control of risks per hazard category. For workers, specific RMM regimes are assigned to each combination of hazard category and process category (PROC). For consumers, a strategy in which RMM are arranged from product-integrated measures to the use of personal protective equipment (PPE) is presented. Our approach may be transferred into automated assessment tools like Chesar and CEFIC GES.     

Inter‐relationships between different classes of chemical allergens

Although allergic sensitization of the respiratory tract induced by chemicals is not as common as skin sensitization, it is nevertheless an important occupational health issue. Respiratory allergy to chemicals, characterized typically by rhinitis and asthma, is associated with considerable morbidity and with related socioeconomic costs. Several experimental approaches have been proposed for the prospective identification of chemical respiratory allergens, but none of these has yet been validated formally. In the absence of a widely accepted method for respiratory allergen identification, it is appropriate and relevant to explore their relationship with skin‐sensitizing chemicals. A series of chemicals known to cause immune‐mediated respiratory allergy in humans has been examined. The majority of the respiratory allergens tested were found to elicit positive responses in one or more standard tests used for the identification of skin‐sensitizing potential (guinea pig maximization test, the Buehler test and/or the local lymph node assay). We suggest that this observation might form the basis of a potentially useful paradigm for initial characterization of the respiratory‐sensitizing potential of chemicals. Specifically, chemicals that fail to elicit positive responses in accepted skin‐sensitization test methods might also be regarded as lacking the inherent potential to cause allergic sensitization of the respiratory tract. Copyright © 2012 John Wiley & Sons, Ltd.     

变应性疾病患者变应原皮试诊断价值研究

目的 探讨变应性疾病患者吸人性变应原皮试诊断价值.方法 采用变应原浸液对1 434例变应性疾病患者分别进行20种吸人性变应原皮内试验,将4～18岁患者设为儿童组(318例),19～80岁患者设为成人组(1 116例).对两组变应原阳性检出率及分布情况进行比较.结果 检测出变应性疾病有8种,其中变应性鼻炎患病人数位居第一位(1 130例,78.80%);前9位的变应原分别为:夏秋花粉Ⅰ(51.05%),屋尘(48.81%)、混合吸入变应原(48.61%)、蒿属花粉(46.86%)、尘螨(45.19%)、多价昆虫(36.82%)、春季花粉Ⅰ(33.99%)、豚草花粉(31.24%)、春季花粉Ⅱ(30.68%).变应原皮内试验有一项以上阳性者达1 289例(89.89%).19～40岁患病人数最多(53.91%).不同季度间的皮试阳性检出率差异有统计学意义(P<0.01).结论 青壮年是变应性疾病的高发人群,变应性鼻炎是最常见的变应性疾病,尘螨(屋尘、尘螨)、夏秋花粉(夏秋花粉Ⅰ、蒿属及豚草花粉)是引起变应性疾病最主要的变应原.     

Determination of protein allergenicity: studies in mice

There is a need to identify and characterize the allergenic potential of novel proteins introduced into genetically-modified crop plants. Although several approaches have already been described, none of these measures directly the ability of proteins to cause allergic sensitization. For this reason there has been a growing interest in the development of suitable animal models. This article describes experience to date with a method based upon assessment of serological (IgG and IgE antibody) responses induced in BALB/c strain mice by proteins. Comparisons have been made between intraperitoneal (i.p.) administration and exposure by gavage using both allergenic and non-allergenic proteins. The available data indicate that responses provoked by i.p. exposure permit the identification of proteins that have the inherent potential to induce IgE antibody production and allergic sensitization. Moreover, this approach also provides a rank order of proteins with respect to allergenic potency that apparently reflects what is known of their relative sensitizing activity in humans. By comparison, oral exposure of mice by gavage is somewhat less sensitive. On this basis it is proposed that the inherent sensitizing potential of novel proteins can be evaluated as a function of IgE antibody responses stimulated by parenteral (i.p.) exposure of BALB/c mice.     

The evolution of skin notations for occupational risk assessment: a new NIOSH strategy

This article presents an overview of a strategy for assignment of hazard-specific skin notations (SK), developed by the National Institute for Occupational Safety and Health (NIOSH). This health hazard characterization strategy relies on multiple SKs capable of delineating systemic (SYS), direct (DIR), and immune-mediated (SEN) adverse effects caused by dermal exposures to chemicals. One advantage of the NIOSH strategy is the ability to combine SKs when it is determined that a chemical may cause multiple adverse effects following dermal contact (e.g., SK: SYS-DIR-SEN). Assignment of the SKs is based on a weight-of-evidence (WOE) approach, which refers to the critical examination of all available data from diverse lines of evidence and the derivation of a scientific interpretation based on the collective body of data including its relevance, quality, and reported results. Numeric cutoff values, based on indices of toxic potency, serve as guidelines to aid in consistently determining a chemical’s relative toxicity and hazard potential. The NIOSH strategy documents the scientific rationale for determination of the hazard potential of a chemical and the subsequent assignment of SKs. A case study of acrylamide is presented as an application of the NIOSH strategy.     

Dendritic cells and skin sensitization: biological roles and uses in hazard identification

Recent advances have been made in our understanding of the roles played by cutaneous dendritic cells (DCs) in the induction of contact allergy. A number of associated changes in epidermal Langerhans cell phenotype and function required for effective skin sensitization are providing the foundations for the development of cellular assays (using DC and DC-like cells) for skin sensitization hazard identification. These alternative approaches to the identification and characterization of skin sensitizing chemicals were the focus of a Workshop entitled "Dendritic Cells and Skin Sensitization: Biological Roles and Uses in Hazard Identification" that was given at the annual Society of Toxicology meeting held March 6-9, 2006 in San Diego, California. This paper reports information that was presented during the Workshop.     

Cytokine profiling of chemical allergens in mice: impact of mitogen on selectivity of response

A major constraint in the development of methods for the identification of chemical respiratory allergens is the continuing uncertainty regarding the mechanisms of this disease and in particular the role of IgE antibody. There is, however, increasing evidence that respiratory sensitization is favoured by the induction of a selective type 2 cytokine response. The current investigations focus on the potential application of cytokine profiling to the identification of chemical respiratory sensitizers. The objective is to determine the optimal configuration of the method for discrimination between chemical contact and respiratory sensitizers. The reference contact sensitizer 2,4‐dinitrochlorobenzene (DNCB) and reference respiratory sensitizer trimellitic anhydride (TMA), which have been shown to induce type 1 and type 2 cytokine profiles, respectively, were utilized. Variables investigated included cell concentration, time in culture, dosing regimens (a 13 day and a truncated 8 day protocol) and the impact of restimulation in vitro with T cell mitogens. Cell culture conditions were critical for the selectivity of the response, with the addition of mitogen resulting in a less discriminatory pattern of cytokine expression, particularly for the type 1 cytokine interferon γ (IFN‐γ). Furthermore, a 13 day exposure period was required for vigorous expression of IFN‐γ by DNCB‐activated cells, whereas type 2 cytokine expression by TMA‐stimulated cells was recorded after 8 days. These data demonstrate that the most optimal method for cytokine profiling is a chronic (13 day) exposure regime followed by culture of lymph node cells at 10⁷ cells ml^?1 for120 h in the absence of mitogen. Copyright © 2008 John Wiley & Sons, Ltd.     

Chemical reactivity measurements: Potential for characterization of respiratory chemical allergens

Allergic diseases of the skin and respiratory tract resulting from exposure to low molecular weight chemicals remain important issues for consumer product development and occupational/environmental health. Widespread opportunities for exposure to chemical allergens require that there are available effective methods for hazard identification and risk assessment. In the search for new tools for hazard identification/characterization there has been interest in developing alternative methods that will reduce, refine or replace the need for animals. One approach that shows promise is based on the measurement of the peptide reactivity of chemicals; the potential to form stable associations with protein/peptide being a key requirement for the induction of sensitization. Recent investigations using these systems have focused primarily on skin sensitizing chemicals. However, there is interest in the possibility of exploiting these same experimental approaches to distinguish between different forms of chemical allergens - as individual materials are primarily associated with one or the other form of sensitization in humans. These investigations may also provide insight into why chemical sensitizers can differ in the form of allergic disease they will preferentially induce. These opportunities are surveyed here against a background of the immunobiology of allergic sensitization and current state-of-the-art approaches to measurement of peptide/protein reactivity.     

Delafloxacin for the treatment of respiratory and skin infections

Introduction: There has been a striking increase in the emergence of multidrug-resistant pathogens in recent times. Delafloxacin is a novel, broad-spectrum fluoroquinolone with antimicrobial activity against resistant Gram-positive, Gram-negative and anaerobic organisms. It has the potential to treat a variety of infections including complicated skin and skin structure infections and respiratory tract infections.

Areas covered: In this review, the authors report the microbiological spectrum of activity of delafloxacin as well as its pharmacokinetic characteristics. They also report the results of recent studies investigating its safety and efficacy.

Expert opinion: The profile of delafloxacin offers several advantages. Delafloxacin presents a broad spectrum of activity against pathogens involved in respiratory infections and complicated skin and skin structure infections (SSSIs), including methicillin-resistant Staphylococcus aureus. It has also shown activity against Gram-negative pathogens, such as quinolone-susceptible and -resistant strains of Escherichia coli and Klebsiella pneumoniae and quinolone-susceptible Pseudomonas aeruginosa. The availability of an oral formulation supports its use in sequential therapy. The efficacy and tolerability of delafloxacin have been demonstrated in Phase II clinical trials in comparison with moxifloxacin for respiratory infections and linezolid and vancomycin in SSSIs. Compared with other quinolones such as moxifloxacin, delafloxacin showed comparable efficacy and a lower rate of adverse effects. The results of new Phase III studies are awaited to confirm delafloxacin’s future applications in the treatment of SSSIs.     

Double-blind comparison of the respiratory effects of parenteral lorazepam and diazepam in patients with chronic obstructive lung disease

Summary

The effects on the respiratory function of two tranquillising drugs, lorazepam and diazepam, have been compared in 20 patients with chronic obstructive lung disease. Both drugs induce a respiratory depression (decrease in tidal volume and minute ventilation with acceleration of the respiratory frequency) with slight respiratory acidosis, but lorazepam causes no significant hypoxemia and has a shorter duration of action than diazepam. Nevertheless, if tranquillisers are indicated in such patients, they have to be used with care.     

Different approaches for improving skin accumulation of topical corticosteroids

The aim of this paper was to evaluate the effect of vehicle, chemical enhancer and iontophoresis on the skin accumulation of clobetasol propionate (CP) and mometasone furoate (MF). In vitro permeation experiments were performed using pig ear skin as barrier and HPLC as quantification method. The formulations tested were chitosan gels, sodium-deoxycholate gels and commercial creams of CP and MF. The results obtained indicate that Na-DOC gel had an enhancing effect on the skin accumulation of both active agents. This effect was more evident with CP especially in the stratum corneum and epidermis which are the target sites of topical steroidal treatment. Two terpene derivatives (d-limonene and nerolidol) and Transcutol^® P were evaluated as chemical penetration enhancers. Nerolidol produced considerable increase in the amount of CP and MF accumulated without any permeation across the skin. The application of electric current (anodal iontophoresis) to the gels improved the accumulation of MF while it did not effect the accumulation of CP. Due to the best accumulation results of nerolidol, the enhancement effect in combination with iontophoresis was also investigated. It was shown that, the combination of anodal iontophoresis and chemical enhancer (nerolidol) produced no further enhancement for both active agents.