Structure-activity relationships in allergic contact dermatitis

Primin (2-methoxy-6-pentyl-1,4-benzoquinone)is a naturally-occurring strong sensitizer from Primula obconica (Primulaceae), To determine the effect of side-chain length on senstizing potency 15 analogues with linear side chains from to from C₁, to C₁₅ and 4 C₆- analogues with branched side chains were prepared synthetically and devoted to experimental sensitization in guinea pigs The results showed an increase of the sensitizing capacity with increasing length of the alkyl side chain from C₁ to C₁₀, reaching a maximum at C₁₁ and C₁₂. On further elongation the senstizing potency decreased beyond C₁₃ reaching values which finally were as low as those of the C₁ and C₃ derivatives. The results mirror finding which finally were as low as those of the C₁ and C₃ derivatives. The results mirror findings which formerly have been obtained with other non-quinonoid compounds like catechols, phenols hydroquinones and gallates. In the plant kingdom. Compound approximating an "ideal allergen" consisting of a quinonoid ring with a 10 or 11 carbon-remarkably strong sensitizer found in Wigandia caracasana (Hydrophyllaceae)     

A case of contact dermatitis due to impurities of cetyl alcohol

A 29-year-old man being treated for itchy lesions on the amputation stump of the thigh became allergic to betamethasone valerate and gentamicin sulfate cream (Rinderon VG®. Closed patch tests with all the ingredients of the cream revealed positive reactions to cetyl alcohol 30% to 5% pet. Gas chromatographic analysis of the cetyl alcohol in the cream base detected stearyl alcohol (C₁₈), myristyl alcohol (C₁₄) and lauryl alcohol (C₁₂) in addition to the main component of cetyl alcohol (C₁₆). Patch testing with 99% pure analytical reagent grade saturated alcohols. (C₁₀, C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, C₁₉, C₂₀) showed negative reactions. Thus, it is concluded that some minor impurities in cetyl alcohol not detected by gas chromatography might be the cause of this dermatitis.     

Structure-activity relationships in allergic contact dermatitis induced by methacrylates

Some methacrylates are known to be strong contact sensitizers. To determine the effect of side-chain length on sensitizing potential, we examined 11 derivatives with linear side chains from C₁ to C₁₈ in an experimental sensitization test in guinea pigs. The results showed an increase in the sensitizing potential with increasing length of the alkyl side chain from Q to C₁₂. The C₁₂ derivative, lauryl methacrylate, showed the strongest sensitizing potential. Further elongation of the alkyl side chain of methacrylates resulted in a decrease in the potential. With respect to the side-chain-length-dependent sensitizing potential, the present results correspond well with the findings obtained with other compounds like primin, catechols, phenols, hydroquinones, and gallates.     

Cytokeratins in human basal and squamous cell carcinomas: biochemical, immunohistological findings and comparisons with normal epithelia

The nature of epithelial cell cytokeratins from epidermal basal cell carcinomas (BCC) (8 cases) and squamous cell carcinomas (SCC) (5 cases) was investigated by biochemical and immunological analysis. Cytokeratin proteins were extracted with high salt buffer and triton X 100 and were comparatively analyzed by SDS (sodium dodecyl sulphate) polyacrylamide gel electrophoresis. Both types of tumor showed either an absence or a very low amount (5% of the total protein) of the major protein band (MW 67000) present in normal human epidermis. This correlated well with results of immunolabelling showing that 67000 keratin antisera, only reacted with some dyskeratotic cells in sections of these tumors. Gel electrophoresis showed in BCC and SCC, three distinct groups of predominant polypeptide bands of apparent relative MW: (1) 60–62000 (2) 54–56000 and (3) 49000, representing respectively about 43.0%, 31.0% and 20.4% of the total proteins.
Antibodies raised in animals against polypeptide bands C₁ (MW 62000), C₂ (MW 56000) and C₃ (MW 49000) from SCC, strongly labelled (indirect immunofluorescence) all malignant cells present in the 2 kinds of tumors. These antisera showed a preferential reaction with the basal epithelial cells, in sections of human and animal epidermis and mucosa thus, suggesting numerous common antigenic determinants between epithelial cells from diverse origins. On the other hand, strong differences between mucosal and epidermal upper layers were noted with C₁ C₂, C₃, and 67000 antisera. These results are further evidence for the existence of different pathways of keratinization in epidermis and mucosa.     

Induction of apoptosis by synthetic ceramide analogues in the human keratinocyte cell line HaCaT

Abstract: In contrast to extracellular, long chain ceramides which comprise a structural component of the epidermal water barrier, intracellular ceramides originating from sphingomyelin hydrolysis have been shown to inhibit proliferation and to induce apoptosis in different cell populations. To further elucidate the possible role of intracellular ceramides in human epidermis, two new cell-permeable ceramide analogues, N -thioacetylsphingosine (C₂-Cer=S) and 4-dodecanoylamino-decan-5-ol (FS-5), were synthesized and tested for their ability to suppress cell growth and to induce apoptosis in immortalized human keratinocytes. It was shown that the well-investigated ceramide analogue N -acetylsphingosine (C₂-Cer=O), as well as the new compound C₂-Cer=S inhibited proliferation of HaCaT cells with half-inhibitory concentrations (IC₅₀) of 20 μg/ml and 10 μg/ml, respectively, whereas FS-5 has been potent with an IC₅₀>40 μg/ml. Overall, all three ceramide analogues induced apoptosis in HaCaT cells as assessed by DNA-fragmentation using ELISA technique and in situ nick end labelling, thereby confirming the importance of ceramide signalling in keratinocytes.     

Conjunctival involvement in the autoimmune blistering dermatoses: a clinical and histopathological study

The conjunctiva was examined by slit lamp microscopy and biopsy for direct immunofluorescence (IF) in patients with cicatricial pemphigoid (CP), bullous pemphigoid (BP), pemphigoid gestationes (PG), linear IgA dermatosis (LAD), pemphigus and dermatitis herpetiformis (DH).
In CP, five of 13 patients had definite scarring, seven equivocal, and one no signs. IF showed linear deposition of IgG and/or C₃ along the BMZ in 45%.
In BP, six of 18 patients had fine conjunctival scarring. IF showed linear IgG IgA and/or C₃ in 73 %. Scarring was not observed in one PG patient.
In LAD, three of seven patients had conjunctival scarring, one with marked symblepharon. IF in five patients showed linear IgG without IgA in three.
In pemphigus, neither of two patients had scarring. IF in both showed IgG and/or C3 between epithelial cells.
In DH, one of three patients had fine scarring.
These findings demonstrate that conjunctival involvement may occur in autoimmune bullous dermatoses other than CP and LAD.     

Interaction of metals in nickel-sensitive patients

Nickel (Ni) dermatitis is, thought to involve the formation of complexes between Ni ions and suitable proteins. 4 groups of 30 subjects who gave positive patch test responses to NiSO₄ 2.9% aq. were each retested to 1 of 4 different solutions containing equimolar (0.1 M) amounts of NiSO₄ plus MgSO₄. NiSO₄ plus CuSO₄, NiSO₄plus ZnSO₄. and NiSO₄ plus Li₂SO₄, respectively. The results, evaluated at 2 days by visual scoring only, demonstrated that the 4 metals exerted a different influence on the nickel reactions, perhaps interfering with one or more factors affecting the formation of Ni++ complexes.     

Sodium tetrachloropalladate (Na2[PdCl4]) as an improved test salt for palladium allergy patch testing

Background:  In the last decades, palladium is widely used in dentistry. Allergic reactions to palladium are rarely diagnosed with patch testing, even when positive results would be expected. Palladium tends to cross-react with nickel, which should give rise to more positive reactions to palladium dichloride (standard test salt).
Objective:  The aim of the study was to test whether or not mono-nuclear sodium tetrachloropalladate (Na₂[PdCl₄]) in petrolatum is a better test salt for diagnosing palladium allergy. Positive reactions to the investigated test salt are compared not only with PdCl_2(aq.), but also to NiSO_4(aq.) and NiSO_4(pet.).
Patients/Methods:  Concentration series of Na₂[PdCl₄] were carried out. 164 consecutive patients were patch tested.
Results:  3% of Na₂[PdCl₄]_(pet.) was found to be the highest non-irritative concentration. The results show ( n  = 164) that Na₂[PdCl₄] covers all reactions to PdCl₂ (1.8%) and provokes more positive reactions (14%). From the 164 patients, 18.3% reacted positively to at least 1 of the nickel salts.
Conclusion:  The sensitivity of patch testing with Na₂[PdCl₄] is increased compared with the PdCl₂ salt. Therefore, it can be concluded that Na₂[PdCl₄] is to be a better test salt for diagnosing palladium allergy with patch testing.     

Effect of hand dermatitis on the total body burden of chromium after ferrous sulfate application in cement among cement workers

Background:  Ferrous sulfate (FeSO₄) added to cement has been used to reduce the prevalence of dermatitis in workers. However, the effect of dermatitis on the total uptake of chromium in cement with or without FeSO₄ has not been previously explored.
Objective:  The objective of this study was to compare the urinary chromium levels before and after FeSO₄ addition among cement workers with or without hand dermatitis.
Methods:  Thirty-five male workers were recruited in this study for two consecutive years: 2003 without using FeSO₄ and 2004 after adding FeSO₄. Urinary chromium was used as a biomarker to estimate the total body burden of chromium.
Results:  Urinary chromium concentration showed significant decreases after FeSO₄ was used, and a larger decrease of urinary chromium was observed in workers with hand dermatitis than for those without hand dermatitis. Moreover, a significant decrease of urinary chromium was observed in workers with hand dermatitis in both 2003 and 2004.
Conclusion:  FeSO₄ decreases the total body burden of chromium, especially in workers with severe and continuous hand dermatitis.     

Pemphigus vegetans of Hallopeau following pemphigus foliaceus

A 69-year-old woman previously affected with pemphigus foliaceus developed pustular lesions followed by verrucous vegetations, localized in the left sub-mammary fold. Histological examination of vegetating lesions showed consistent acanthosis and papillomatosis with intraepidermal microabscesses containing eosinophils. Direct immunofluorescent examination evidenced intraepithelial IgG and C₃ deposits. Circulating pemphigus antibodies were positive at titre 1: 160. This case suggests a clinical link between pemphigus vegetans and pemphigus foliaceus.     

Enhanced synthesis of cysteinyl leukotrienes in atopic dermatitis

Synthesis of cysteinyl leukotrienes was assessed in patients with atopic dermatitis (AD; n =8) and healthy volunteers ( n =8) by measuring urinary excretion of leukotriene E₄ (LTE₄), the main index metabolite of cysteinyl leukotrienes in man.
Using this non-invasive method we demonstrated a significant ( P <0.05) 4.5-fold increase in excretion of LTE₄ compared with healthy volunteers. The identity of LTE₄ was unequivocally demonstrated by gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS). LTE₄ was routinely measured by radioimmunoassay (RIA), and quantitative measurement of LTE₄ by RIA was validated by GC-MS/MS. There was a linear correlation between LTE₄ measured by RIA and by GC-MS/MS (r=0.994). Tn representative samples, LTE₄ was also quantitatively assessed by GC-MS/MS. In these samples, LTE₄ values obtained by GC-MS/MS differed <10% from those obtained by RIA. The present findings suggest that cysteinyl leukotrienes play a role in AD.     

Red hair, fair skin and melanoma – melanocortin 1 receptor

POMC processing in human melanocytes has been widely documented, and the α-MSH/MC1R/cAMP cascade has been implicated in the control of pigmentation. Only very recently, a role of β-endorphin, one cleavage product of β-LPH, has been demonstrated to influence melanocyte growth, dendricity and melanin biosynthesis via the µ-opiate receptor. However, much earlier, it was shown that β-MSH, the other cleavage product of β-LPH, controls melanogenesis and melanin transfer in amphibians. To date, a specific receptor for β-MSH has not been identified. Earlier POMC processing has been found in melanosomes. Therefore, an MC1R-independent role of α-MSH was postulated and demonstrated in control of 6-tetrahydrobiopterin (6BH₄)-inhibited tyrosinase. Utilizing the depigmentation disorder vitiligo, we were now able to follow the fate of epidermal POMC processing in the presence of mM levels of hydrogen peroxide (H₂O₂). In vitiligo epidermal PC2 and 7B2 protein expression is increased, whereas α-MSH, β-MSH and β-endorphin are significantly decreased. Analysis of the peptide sequences revealed in all three cases H₂O₂ oxidation targets such as methionine and tryptophan yielding significant structural alterations. Moreover, we have identified a new function of β-MSH due to its capacity to bind the important cofactor 6BH₄ as well as its isomer 7BH₄. Hence, we propose for the first time that β-MSH can control both the supply of l -tyrosine from l -phenylalanine via phenylalanine hydroxylase and l -Dopa synthesis via tyrosinase hydroxylase in melanocytes and keratinocytes. Therefore, both melanogenesis and catecholamine synthesis could be regulated by this peptide.     

CaF2:Dy and CaF2 crystal-based UV dosimeters

Background/aims: Monitoring of ultraviolet (UV) exposure in humans is important, since UV has been implicated in the pathogenesis of skin cancer, skin ageing and immunosuppression. Biological and physical dosimeters are being developed to measure occupational and environmental UV radiation exposure. We studied the UV-dependent thermoluminescence in CaF₂:Dy and CaF₂ crystals and report on the development of a small personal UV dosimeter based on the thermoluminescent phenomenon.
Methods: CaF₂:Dy or CaF₂ was sensitized to UV by heating for 1-3 h to 750-950^oC on different supports (porcelain, steel, preheated steel, silicon, chromium, manganese, iron, cobalt, nickel, copper, Fe₂O₃, Fe₃O₄). Sensitized crystals were irradiated with UV of different energies and wavelengths. Thermoluminescence of irradiated crystals was measured at different temperatures.
Results: Maximal sensitivity of the crystals to UV was obtained after preheating to 900^oC on steel and manganese supports. Sensitivity could be improved further by prolonging heating time. CaF₂:Dy and CaF₂ were most sensitive to short-wave UVC and UVB radiation. Based on these findings we have constructed personal UVB and UVC dosimeters.
Conclusion: Development of personal UVC and UVB dosimeters based on UV-induced thermoluminescence in CaF₂:Dy and CaF₂ crystals is feasible. CaF₂:Dy and CaF₂ crystals are not sensitive enough to long-wave UV radiation to be used for construction of UVA dosimeters.     

Imaging of melanin distribution using multiphoton autofluorescence decay curves

Background/purpose: Multiphoton fluorescence lifetime imaging (FLIM) is a technique that produces an image based on differences in the decay rate of fluorescence from a sample. Based on this method, the DermaInspect was developed to observe human skin components non-invasively. In this study, we used the DermaInspect to study melanin in skin.
Methods: A human three-dimensional skin model containing melanocytes was embedded in an OCT compound, frozen and sectioned at 10 μm. The melanin distribution in each section was visualized by the DermaInspect using time-resolved single-photon counting and near-infrared femtosecond laser pulse excitation. The melanin distribution of the same sections was then visualized using the Fontana-Masson staining method.
Results: High-resolution images were generated from the ratio of a ₁/ a ₂ ( a ₁e^{− t /120}+ a ₂e^{− t /1100} was chosen to express the exponential fluorescent decay curve) obtained using the DermaInspect. Granules with a high a ₁/ a ₂ ratio, approximately 1 μm in diameter, were observed. Fontana-Masson staining identified these granules as melanin. This new technique was then applied for in vivo observation of melanin in human skin. 'Melanin caps' were visualized in the basal cell layer around the nuclei in images derived from the a ₁/ a ₂ ratio.
Conclusion: Our study confirms that FLIM can non-invasively provide data of the melanin distribution with almost the same quality as the conventional Fontana-Masson staining method, and demonstrates that FLIM is useful for in vivo observation of melanin granules in human skin.     

Adverse skin reactions to vitamin K1: report of 2 cases

Vitamin K is essential to the biosynthesis of prothrombin and other clotting factors (VII, IX and X), and is mostly used for the prophylaxis of bleeding disorders, mainly in patients with hepatic disfunction (1). 4 different pharmacological forms exist: the natural form K1 (phytomenadione); K₂ (menaquinone), which is derived from intestinal bacterial action; K₃ (menadione); and K₄ (menadiol). The latter 2 are synthetic products. In Italy, only vitamin K1 is marketed (2).
Adverse cutaneous reactions to vitamin K are rare; 2 are mainly reported: an erythematous plaque (3, 4) or pseudo-scleroderma (5) at the injection site. Contact dermatitis and localized urticarial lesions have also been described (2).     

Erythema-multiforme-like, urticarial papular and plaque eruptions from bufexamac: report of 4 cases

8 nickel-sensitive subjects were given a gradually increasing daily oral intake of NiSO₄ in water. The exposure lasted from between 91 and 178 days and the total intake ranged from between 113 and 278 mg of Ni⁺⁺. While 6 subjects were continuously exposed over the entire period, the other 2 were exposed for 2 shorter periods with an interval between the 2 exposures of 84 and 63 days, respectively. Nickel exposure was well tolerated by all subjects, and there was no worsening of the cutaneous manifestations. Ni⁺⁺ serum and urine concentrations were repeatedly assayed. A reduction of intestinal adsorption and an activation of the renal excretion were shown through an evaluation of the ratios of Ni⁺⁺ serum concentration/Nr + cumulative oral intake, Ni⁺⁺ urinary amount/nickel cumulative oral intake and Ni⁺⁺ serum amount/Ni⁺⁺ urine amount, The course of Ni⁺⁺ faecal amounts, calculated indirectly, increased rapidly in time and was consistent with the other courses. In many subjects, the decrease in serum concentrations was followed by a slight increase. It is likely that this phenomenon is due to the release of epidermally stored nickel. These data seem to indicate that in some sensitive subjects, prolonged oral exposure to NiSO₄ in water reduces the intestinal adsorption of nickel and activates its renal excretion, also promoting the mobilization of accumulated element.     

Prostanoid receptors in anagen human hair follicles

Abstract:  Prostanoid pathway in hair follicle gained closer attention since trichogenic side-effects on hair growth has been observed concomitantly with prostaglandin F_2α receptor (FP) agonist treatment of intraocular pressure. We thus investigated prostanoid receptor distribution in anagen hair follicle and different cell types from hair and skin. Using RT-PCR, Western blot and immunohistochemistry (IHC), we found that all receptors were present in hair follicle. This data shed new light on an underestimated complex network involved in hair growth control. Indeed most of these receptors showed a wide spectrum of expression in cultured cells and the whole hair follicle. Using IHC, we observed that expression of prostaglandin E₂ receptors (EP₂, EP₃, EP₄), prostaglandin D₂ receptor (DP₂), prostanoid thromboxane A₂ receptor (TP) and to a lesser extent EP₁ involved several hair follicle compartments. On the opposite, Prostaglandin I₂ receptor (IP) and DP₁ were more specifically expressed in hair cuticle layer and outer root sheath (ORS) basal layer, respectively. FP expression was essentially restricted to ORS companion layer and dermal papilla ( DP ). Although extracting a clear functional significance from this intricate network remains open challenge, FP labelling, i.e. could explain the biological effect of PGF_{2 α} on hair regrowth, by directly modulating DP function.     

Allergen-sensitive atopic dermatitis is improved by injections of allergen combined with F(ab')2 fragments of specific antibodies

Summary Symptoms of atopic dermatitis (AD) can be provoked by exposure to airborne allergens. We have previously shown that patients hypersensitive to D. pteronyssinus (Dpt) allergens were improved by administration of complexes composed of specific antibodies and allergen, which reduce the allergen-specific immune response. We now report that similar results can be achieved by using F(ab')₂ fragments of specific antibodies instead of whole antibody molecules. Eight adult patients with severe AD were included in a single-blind study. During the first 11 months patients were maintained on injections of carrier buffer alone, in an effort to evaluate the extent of spontaneous improvement. They were then treated with intradermal injections of allergen-F(ab')₂ complexes made from autologous specific antibodies and Dpt allergens. The majority of the patients improved spontaneously during the summer months, with an average 30% reduction of symptoms. However, a much more pronounced improvement was observed after 3 months on active therapy, corresponding to a cumulative amount of 60 μg F(ab')₂ and 15 μg allergens. The patients continued to improve over the next 5 months, showing an average 83% reduction of severity scores. The use of F(ab')₂ antibody fragments reduces the risk of inducing an anti-allotypic immune response, and raises the possibility of adding adjuvants to allergen-antibody complexes and/or using specific antibodies isolated from pooled gammaglobulins.     

Sensitivity and specificity of eicosanoid radioimmunoassays: new strategy

In radioimmunoassays (RIAs) the limit of detection of the unknown (ligand, competitor) depends first on the affinity of antibody populations engaged in the immunological reaction at a given dilution of the antiserum, second on the specific radioactivity of the tracer or inhibitor, and third on the degree of structural homology of both components (unknown and tracer) of the competition. The commercially available tritiated eicosanoids have up to eight atoms of tritiu incorporated into their molecules, allowing RIAs with convenient sensitivities to be developed. Often, however, a higher sensitivity is needed in several studies. First attempts (Dray et al . 1972) using PGF_2x covalently bound to bacteriophage T₄ as a tracer yielded a highly sensitive viroimmunoassay (limit of detection, less than i pg per tube), but its wider application requires further studies, particularly to reduce the non-specific binding (Andrieu, Mamas & Dray, 1974; Mamas & Dray, 1979).
On the other hand, we succeeded in developing very sensitive and reliable RIAs using iodinated derivatives, which could be applied to any eicosanoid.