Cross-reactivity between sesquiterpene lactones related to parthenin in parthenin-sensitized guinea pigs

The naturally-occurring sesquiterpene lactone, parthenin, is responsible for a high incidence of allergic contact dermatitis in India. Cross-sensitivity tests on guinea pigs sensitized to parthenin indicate a relatively high immunological specificity for this low molecular weight hapten. Coronopilin and damsin, sesquiterpene lactones most similar to parthenin, gave positive reactions but other structurally related lactones such as dihydroisoparthenin, tetra-hydroparthenin, tetraneurin-A, hysterin, helenalin, and tenulin, or hymenin, a diastereoisomer of parthenin, were negative.     

Cross-reactivity between sensitivity to thimerosal and photosensitivity to piroxicam in guinea pigs

Guinea pigs were sensitized to dinitrochlorobenzene (DNCB) by the intracutaneous route and challenged epicutaneously on the flanks. The intensity of the allergic contact dermatitis was evaluated by inspection and palpation as well as by wet weight determination. With the purpose of diminishing tissue neuropeptides, and substance P in particular, the animals were treated with capsaicin either between induction and challenge, or before sensitization. In comparison with controls, the contact dermatitis was enhanced in both groups of animals treated with capsaicin.     

UVB serum factor: suppression of allergic contact dermatitis in guinea pigs

Serum from guinea pigs exposed to a single high dose of UVB and from controls was injected into the spleen of normal animals 5 days prior to sensitization. When 1.0 ml was transferred 4.5 h after irradiation, immunosuppression was obtained. Transfer of 1.5 ml of serum 2.5 h after irradiation failed to induce immunosuppression. This experimental model in guinea pigs might be valuable in further studies investigating the effect of other modalities of ultraviolet exposure (e.g., PUVA or high-dose UVA) on the release of soluble serum factor(s) inducing immunosuppression in allergic contact dermatitis.     

Contact allergy to a cyclohexanone resin in humans and guinea pigs

5 patients with allergic contact dermatitis caused by various paints were demonstrated to be sensitive to a cyclohexanone resin (C-R) present in the paints. Sensitization studies in guinea pigs with C-R and cyclohexanone showed one batch of C-R to be a sensitizer.     

Cutaneous sensitization to some polyisocyanate prepolymers in guinea pigs

Isocyanates are used extensively in the polyurethane industry. Pulmonary and dermal sensitization resulting from exposure to diisocyanates has frequently been reported, but the potential effects of polyisocyanates on health are less well known. Thus, since 1978, occupational exposure limits have been established for diisocyanates only. Nevertheless, respiratory diseases and dermatitis have been reported in the polyurethane industry after accidental isocyanate contact during spills or splashes. The aim of this experimental work was to assess the dermal hypersensitivity of guinea pigs to some polyisocyanate prepolymers by means of a well-conducted standard predictive Buehler test. Our results showed that dicyclohexylmethane 4,4'-diisocyanate (HMDI), toluylene 2,4-diisocyanate (TDI), TDI adduct triol, TDI isocyanurate, 1,6-hexamethylene diisocyanate (HDI), HDI isocyanurate, HDI biuret and isophorone diisocyanate (IPDI) induced dermal sensitization while IPDI isocyanurate did not. In conclusion, the dermal hypersensitivity of guinea pigs to some polyisocyanates was similar to those of their corresponding monomers except for IPDI isocyanurate, suggesting that the results from diisocyanate monomers could not be a valuable approach for the detection of the sensitization potency of the corresponding prepolymers.     

Contact dermatitis from acrylate and methacrylate compounds in Lowicryl® embedding media for electron microscopy

This report is about occupational contact dermatitis found in 3 out of 6 workers of a chemistry laboratory using Lowicryl embedding media, which contain (meth)acrylate monomer mixtures of known composition. The notation (meth)acrylates is used to refer to both acrylates and methacrylates. (Meth)acrylate monomers will polymerize in the absence of oxygen when induced by metal ions, peroxides, heat or ultraviolet light. The monomers are of low viscosity and remain in the liquid state at temperatures far below 0 degree C. The volatile compounds, some of which exhibit a most pungent odour, have a tendency to penetrate all tissue and to permeate into the finest fissures, a property which makes them suitable as sealants, glues, embedding material, etc. This and their toxicity may represent a danger to the health of individuals who need to work with them, especially if no precautions are taken. We show with patch testing that one patient reacted strongly to the compound 2-hydroxyethyl acrylate at the dilutions tested (0.5 and 1% v/v), but not at all to 10 other (meth)acrylates. In the same test, 3 volunteer controls were negative to 2-hydroxyethyl acrylate. We demonstrate that at maximum working concentration, 2-hydroxyethyl acrylate penetrates both latex and vinyl gloves and elicits irritant/allergic reactions on the patient and irritant reactions on a control. Finally, we discuss the necessary protective measures.     

自制防晒乳膏体外及豚鼠在体防晒性能的评价

目的 观察自制防晒乳膏的防晒指数SPF值和PFA值。 方法 体外法测定样品防晒指数：将样品以2 μl/cm2的剂量涂抹于仿生皮肤3M膜上,然后用防晒指数测定仪测定样品的防晒指数。豚鼠在体防晒指数的测定：白化豚鼠48只,随机分为8组,其中4组不涂防晒样品,4组分别涂布自制防晒乳膏和对照样品（某市售防晒制剂）,使用SUV-1000型日光紫外线模拟器模拟紫外线照射,测定样品防晒指数。结果 体外法检测自制防晒乳膏和某市售制剂的SPF值分别为32.26 ± 2.42和30.87 ± 2.57,PFA值分别是24.28 ± 2.44和17.53 ± 2.28,两种制剂SPF相比,t = 0.94,P ＞ 0.05（n = 5）;但自制防晒乳膏对UVA的防护效果优于某市售制剂,t = 4.52,P ＜ 0.01（n = 5）。豚鼠在体法检测自制防晒乳膏和某市售制剂的SPF值分别为30.39 ± 6.65和28.79 ± 7.36,PFA ＞ 8.91和 ＞ 8.93,两种制剂SPF值比较,t = 0.38,P ＞ 0.05（n = 12）。结论 自制防晒乳膏和某市售制剂相比,对紫外线的防护效果相当。     

Contact photoallergy testing of sunscreens in guinea pigs

The potential of 3 sunscreens (p-aminobenzoic acid, 4-isopropyldibenzoylmethane and homosalate) and 2 known human photoallergens (musk ambrette and tetrachlorosalicylanilide) to cause photoallergy, phototoxicity, and/or contact sensitization was determined using a guinea pig photoallergy model, as previously described by Harber and associates. The model was slightly modified by employing 6 exposures over 2 weeks and using Hill Top Chambers for application of the test material. Contact photoallergy was detected in guinea pigs treated with musk ambrette or tetrachlorosalicylanilide (TCSA), although with TCSA, a lower incidence of contact sensitivity and phototoxicity was also detected. The results of studies conducted with sunscreens showed that p-aminobenzoic acid was photoallergenic, whereas homosalate and 4-isopropyl-dibenzoylmethane (Eusolex 8020) were not. However, contact sensitization, and to a lesser degree primary irritation, was detected with Eusolex 8020 at the concentrations employed in this study. The results of these studies suggest that this guinea pig model is a suitable model for assessing the photoallergic potential of various compounds, including the sunscreens tested in this study.     

Inhibitory effect of 8-methoxysporalen plus UVA (PUVA) on the systemic induction of contact sensitivity to dinitrochlorbenzene (DNCB) in guinea pigs

Summary To investigate the influence of 8-MOP and UVA on the induction of cell-mediated immunity, guinea pigs, sensitized with a single injection of dinitrofluorbenzene (DNFB) in Freund's complete adjuvant (FCA) in all footpads and the nuchal skin, were treated with 8-MOP, UVA, or 8-MOP+ UVA on days 0, 2, and 5 and tested with dinitrochlorbenzene (DNCB) on day 14 after sensitization. Two control groups, exposed in a covered condition to the PUVA 4000 lamp, to observe the heat effect, showed a slightly enhanced contact sensitivity in comparison to the only sensitized control group. No altered reactivity was observed after irradiation with longwave UV light alone, whereas a statistically significant enhanced resp. reduced contact sensitivity was obtained after the treatment with 8-MOP alone and the combined action of 8-MOP +UVA, respectively.Dedicated to Prof. Dr. P. Laugier, Chairman of the Department of Dermatology, University of Geneva, Switzerland, on the occasion of his 70th anniversary     

Method for assessment of experimental allergy in guinea pigs adapted to cosmetic ingredients

2 protocols are presented to predict and assess allergic reactions after application of chemicals or cosmetic products, either raw materials or finished products. The first is an open epidermal induction and challenge, the intensity of the reaction being maximized by injecting Freund's complete adjuvant into the foot pad. The second allows detection of weaker allergens and is a quasi-intradermal induction: both the adjuvant and test substance are injected into the foot pad. In both protocols, the challenge consisted of a single topical application in the lumbar region of 10 microliter of test substance and components, allowing study of cross-sensitization, the large surface available permitting 6 different contacts.     

Contact sensitivity to preservatives in Turkey

This study was designed to evaluate the frequency of contact sensitivity to 14 common preservatives among patients with contact dermatitis in Turkey. From 2000 to 2004, 308 patients with the diagnosis of contact dermatitis were patch tested in the Department of Dermatology, Ankara University School of Medicine. All patients were patch tested with European standard series. In addition to the four preservatives included in the standard series, patients were also tested with DMDM hydantoin, imidazolidinyl urea, bromonitropropane diol, diazolidinyl urea, thimerosal, propylene glycol, chlorocresol, chloroxylenol, methyldibromoglutaronitrile/phenoxyethanol (MDBGN/PE) and benzalkonium chloride. Out of the 308 patients suspected of having contact dermatitis, 23 patients were found to have positive reactions to one or more preservatives. Preservatives that were the most frequent cause of positive reactions were thimerosal (1.6%), benzalkonium chloride (1.6%), formaldehyde (1.3%) and MDBGN/PE (0.9%). In our study, 65% of the positive reactions were caused by allergens not present in the standard series, such as thimerosal, benzalkonium chloride and MDBGN/PE. Although thimerosal caused a high rate of contact sensitivity, it may not be considered as an important allergen, because clinical relevance could not be found in any of the patients.     

Contact sensitivity in atopic dermatitis

With the exception of certain drugs, some contactants give positive patch test reactions less frequently in patients with atopic dermatitis than in all patients with dermatitis. Both among atopics and other dermatitis patients, women reacted positively to most drugs more frequently than men did. In Poland, positive patch tests to balsams are rare in atopics.     

Patch testing with beryllium alloy samples in guinea pigs

An experimental study was conducted in guinea pigs for the predictive assessment of the beryllium alloy hazard in occupational exposure of the skin to beryllium compounds. Guinea pigs were sensitized to beryllium sulfate according to the maximized Magnusson and Kligman test, and challenged with beryllium alloys and metallic copper, beryllium and aluminum samples. Results showed a delayed skin hypersensitivity reaction in 30 to 60% of pre-sensitized guinea pigs challenged with copper-beryllium alloys and aluminum-beryllium alloy. An inflammatory follicular reaction was induced by copper in both controls and pre-sensitized guinea pigs.     

3种中草药单体治疗豚鼠皮肤马拉色菌感染的实验研究

目的:筛选出有效的抗马拉色菌的中草药单体.方法:采用连续7 d涂菌法诱导豚鼠皮肤感染马拉色菌,并将苦参碱、柠檬醛、丁香酚3种中草药单体参考品及酮康唑粉制成2%凡士林霜剂,采用自身对照法观察治疗后培养皿中的真菌菌落数、真菌转阴率.结果:连续用药4 d后,柠檬醛、丁香酚组菌落数明显少于阴性及空白对照组,并且柠檬醛组真菌转阴率与酮康唑组差异无统计学意义;连续用药7d后,3种实验药物组的菌落数及真菌转阴率均明显低于阴性对照组及空白对照组,而与酮康唑组差异无统计学意义.结论:苦参碱、柠檬醛、丁香酚在体内具有较强的抗马拉色菌作用.皮肤菌落计数是定量指标,更能反应药物的短期疗效.     

Topical cyclosporine: effects on allergic contact dermatitis in guinea pigs

Cyclosporine (CSA) is an effective immunosuppressive agent and is used in tissue transplantation. The present investigation was undertaken to determine the effect of topical delivery of CSA on allergic contact dermatitis in guinea pigs. Topical 15% CSA in an azone (1-dodecylazacycloheptan-2-one)-containing vehicle blocked local elicitation in previously dinitrochlorobenzene (DNCB) sensitized animals that received a single topical application just prior to elicitation. Elicitation was not blocked at a distant site, indicating a local effect of topical CSA. In contrast, topical CSA when applied twice daily for a total of 5 applications during sensitization only, did not block subsequent elicitation. These experiments suggest that cyclosporine may be beneficial in the therapy of human contact dermatitis, as well as other T cell mediated dermatoses.