Twenty-eight-day follow-up of patch test reactions to p-phenylenediamine and p-phenylenediamine dihydrochloride: A multicentre study on behalf of the European Environmental and Contact Dermatitis Research Group.

BACKGROUND: There is an ongoing discussion on whether routinely patch testing with p-phenylenediamine (PPD) 1.0% pet. is safe, owing to the risk of patch test sensitization. Late-appearing patch test reactions may reflect patch test sensitization, but may also be attributable to a low degree of pre-existing sensitization. OBJECTIVES: To follow the positive patch test reactions to PPD and its salt PPD dihydrochloride (PPD-DHC) in order to characterize reaction patterns concerning time and dose in PPD-sensitized individuals. METHODS: Volunteers with previous reactions to PPD 1.0% were included and patch tested with PPD and PPD-DHC in equimolar dilution series. There were then seven follow-up visits over a period of 28 days. RESULTS: Twenty-six volunteers completed the study, of whom 23 of 26 (88%) reacted to PPD 1.0%, and 69% reacted to PPD 0.32%. Altogether, 42% and 27% reacted to the corresponding equimolar concentrations of PPD-DHC. After day 7, no new reactions were observed to any concentration tested, either of PPD or of PPD-DHC. CONCLUSION: No late-appearing reactions to PPD or PPD-DHC were observed at any dose. There is a risk of missing contact allergy when the dose is decreased.

Low prevalence of oral and nasal human papillomavirus in employees performing CO2-laser evaporation of genital warts or loop electrode excision procedure of cervical dysplasia.

Risk of human papillomavirus (HPV) transmission during laser vaporisation of genital warts or loop electrode excision procedure is controversial. An oral rinse, a nasal swabs, history of HPV related diseases and data on HPV exposure were collected from 287 employees at departments of dermato-venerology and gynaecology in Denmark. A mucosal HPV type was found among 5.8% of employees with experience of laser treatment of genital warts as compared to 1.7% of those with no experience (p = 0.12). HPV prevalence was not higher in employees participating in electrosurgical treatment or cryotherapy of genital warts, or loop electrode excision procedure compared with those who did not. HPV 6 or 11 were not detected in any samples. Hand warts after the age of 24 years was more common among dermatology than among non-dermatology personnel (18% vs. 8.0%, p = 0.03). Mucosal HPV types are infrequent in the oral and nasal cavity of health care personnel, however, employees at departments of dermato-venereology are at risk of acquiring hand warts.

Outcome of a second patch test reading of TRUE Tests® on D6/7.

Background. Two readings of patch test reactions are recommended. Objectives. To evaluate the outcome of a second patch test reading of TRUE Test® allergens on D6/7 in relation to negative or doubtful reactions on D3/4. Methods. This was a retrospective investigation of patch test data from January 1992 to October 2011 from consecutive eczema patients tested with the TRUE Test® panels. Results. In the period of nearly 20 years, a total of 9997 patients were tested. The total number of positive reactions to the 29 allergens was 6509; 4.4% were positive on D6/7 and negative on D3/4; and 9.1% were positive on D6/7 after a doubtful (?+) reaction on D3/4. Neomycin was the most frequent allergen giving delayed positive reactions (57%), followed by budesonide (42%) and hydrocortisone-17-butyrate (31%). Conclusion. A total of 4.4% of positive TRUE Test® reactions would be missed, and 9.1% might be missed, if only one reading was performed on D3/4. The results emphasize that many doubtful reactions at D3/4 may develop into positive reactions at a later reading. This may have important implications for evaluation of the clinical relevance of the test result.

A study of the enhanced sensitizing capacity of a contact allergen in lipid vesicle formulations.

The growing focus on nanotechnology and the increased use of nano-sized structures, e.g. vesicles, in topical formulations has led to safety concerns. We have investigated the sensitizing capacity and penetration properties of a fluorescent model compound, rhodamine B isothiocyanate (RBITC), when administered in micro- and nano-scale vesicle formulations. The sensitizing capacity of RBITC was studied using the murine local lymph node assay (LLNA) and the skin penetration properties were compared using diffusion cells in combination with two-photon microscopy (TPM). The lymph node cell proliferation, an indicator of a compounds sensitizing capacity, increased when RBITC was applied in lipid vesicles as compared to an ethanol:water (Et:W) solution. Micro-scale vesicles showed a slightly higher cell proliferative response compared to nano-scale vesicles. TPM imaging revealed that the vesicle formulations improved the skin penetration of RBITC compared to the Et:W solution. A strong fluorescent region in the stratum corneum and upper epidermis implies elevated association of RBITC to these skin layers when formulated in lipid vesicles. In conclusion, the results indicate that there could be an elevated risk of sensitization when haptens are delivered in vehicles containing lipid vesicles. Although the size of the vesicles seems to be of minor importance, further studies are needed before a more generalized conclusion can be drawn. It is likely that the enhanced sensitizing capacity is a consequence of the improved penetration and increased formation of hapten-protein complexes in epidermis when RBITC is delivered in ethosomal formulations.

Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties.

Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens in ethanolic liposomes have been reported to enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present report includes data on more sensitization studies using the mouse local lymph node assay with three contact allergens encapsulated in different dermal drug-delivery systems: liposomes, ethosomes, and polycaprolactone particles. The results show that the drug-delivery systems are not sensitizers in themselves. Encapsulating the hydrophilic contact allergen potassium dichromate in all three drug-delivery systems did not affect the sensitizing capacity of potassium dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed for encapsulating isoeugenol in polycaprolactone (1100 ± 406) compared with a formulation in acetone:olive oil (4491 ± 819) and in liposomes (3668 ± 950). Further, the size of DNCB-loaded liposomes did not affect the sensitizing properties. These results suggest that modern dermal drug-delivery systems may in some cases magnify or decrease the sensitizing capacity of the encapsulated contact allergen.

Percutaneous penetration characteristics and release kinetics of contact allergens encapsulated in ethosomes.

BACKGROUND: Formulation of the contact allergens dinitrochlorobenzene and isoeugenol in ethanolic liposomes (ethosomes) increases their sensitizing properties in the local lymph node assay compared with an ethanol-water formulation of the allergens. Likewise, isoeugenol and methyldibromo-glutaronitrile formulated in ethosomes enhanced the patch test reactions in sensitized human volunteers. The relationship between the percutaneous penetration/absorption and sensitization/elicitation phases of contact allergy is not well elucidated. OBJECTIVE: The aim of this study was to investigate whether the observed increased sensitizing and elicitation properties following the formulation of selected contact allergens in ethosomes could be explained by a change in release kinetics of the allergens and their pattern of percutaneous penetration and absorption as well as allergen deposition in epidermis and dermis. METHODS: Release kinetics were studied using dialysis bags, and samples were taken at selected time points until equilibrium was reached. Percutaneous absorption and penetration were studied using human skin on Franz cells, and receptor fluid samples were taken at selected time points. Experiments were terminated after 24 hours, and deposition of allergen in epidermis and dermis was measured. Maximum flux and lag time were calculated. RESULTS: Ethosome formulation decreased the release of both allergens compared with the ethanol-water formulation. Ethosome formulation of dinitrochlorobenzene increased its percutaneous penetration but reduced the percutaneous penetration of isoeugenol compared with control formulations. Likewise, all other calculated parameters showed an opposite trend for the 2 allergens in ethosomes and ethanol-water. CONCLUSIONS: The present study demonstrates that identical ethosomes affect the percutaneous penetration characteristics of 2 allergens differently. Thus, our results indicate that each combination of an allergen and a vehicle needs to be evaluated separately. The exact mechanistic relationship between percutaneous penetration, release kinetics, and allergenicity of chemicals in various vehicles remains to be clarified.

Microvesicle formulations used in topical drugs and cosmetics affect product efficiency, performance and allergenicity.

Attempts to improve the formulations of topical products are continuing processes (ie, to increase cosmetic performance, enhance effects, and protect ingredients from degradation). The development of micro- and nanovesicular systems has led to the marketing of topical drugs and cosmetics that use these technologies. Several articles have reported improved clinical efficacy by the encapsulation of pharmaceuticals in vesicular systems, and the numbers of publications and patents are rising. Some vesicular systems may deliver the drug deeper in the skin as compared to conventional vehicles, or even make transdermal delivery more efficient for a number of drugs. Vesicular systems may also allow a more precise drug delivery to the site of action (ie, the hair follicles) and thereby minimize the applied drug concentration, reducing potential side effects. On the other hand, this may increase the risk of other side effects. Few case reports have suggested that microvesicle formulations may affect the allergenicity of topical products. This article gives an overview of the current knowledge about the topical use of microvesicular systems and the dermatoallergologic aspects.

Ethosome formulation of contact allergens may enhance patch test reactions in patients.

BACKGROUND: Ethosomes and liposomes are ultra-small vesicles capable of encapsulating drugs and cosmetic ingredients for topical use, thereby potentially increasing bioavailability and clinical efficacy. So far, few reports have suggested that formulation of cosmetic ingredients in vesicular carrier systems may increase the allergenicity potential. OBJECTIVES: To investigate the effect of ethosome formulation of isoeugenol and methyldibromo glutaronitrile on the elicitation response under patch test conditions and by repeated open applications. PATIENTS/MATERIALS/METHODS: A total of 27 volunteer patients with a previous positive patch test reaction to either isoeugenol or methyldibromo glutaronitrile were included in the study. In all patients, a serial dilution patch test was performed with the allergen in question formulated in ethosomes and in an ethanol/water solution. In addition, a repeated open application test (ROAT) was performed in a subset of 16 patients, and lag time until a positive response was recorded. RESULTS: Both contact allergens encapsulated in ethosomes showed significantly enhanced patch test reactions as compared with the allergen preparation in ethanol/water without ethosomes. No significant difference in the median lag time was recorded between preparations in the ROAT. CONCLUSIONS: Encapsulating potential contact allergens in ethosomes may increase the challenge response as compared with the same concentrations in an ethanol/water base without ethosomes.

Pyoderma gangraenosum as a complication to knee arthroscopy.

Pyoderma gangraenosum (PG) is a rare immunologic ulcerative disease, which sometimes develop as a complication to surgery. PG is often misdiagnosed as an infected wound, but treatment is completely different. We report a case of PG as a complication to arthroscopic partial meniscectomy that resulted in arthrodesis of the knee. We discuss the differential diagnosis and treatment options.

Tetrahydrobiopterin precursor sepiapterin provides protection against neurotoxicity of 1-methyl-4-phenylpyridinium in nigral slice cultures.

Complex-I inhibition and oxidative processes have been implicated in the loss of nigral dopamine neurones in Parkinson's disease and the toxicity of MPTP and its metabolite MPP+. Tetrahydrobiopterin, an essential cofactor for tyrosine hydroxylase, may act as an antioxidant in dopaminergic neurones and protects against the toxic consequences of glutathione depletion. Here we studied the effects of manipulating tetrahydrobiopterin levels on MPP+ toxicity in organotypic, rat ventral mesencephalic slice cultures. In cultures exposed to 30 micro m MPP+ for 2 days, followed by 8 days 'recovery' in control medium, we measured dopamine and its metabolites in the tissue and culture medium by HPLC, lactate dehydrogenase release to the culture medium, cellular uptake of propidium iodide and counted the tyrosine hydroxylase-immunoreactive neurones. Inhibition of tetrahydrobiopterin synthesis by 2,4-diamino-6-hydroxypyrimidine had no significant synergistic effect on MPP+ toxicity. In contrast, the tetrahydrobiopterin precursor l-sepiapterin attenuated the MPP+-induced dopamine depletion and loss of tyrosine hydroxylase-positive cells in a dose-dependent manner with 40 micro m l-sepiapterin providing maximal protection. Accordingly, increasing intracellular tetrahydrobiopterin levels may protect against oxidative stress by complex-I inhibition.