Ovarian differentiation and development in cachara Pseudoplatystoma fasciatum.

One thousand five hundred cachara or tiger shovelnose catfish Pseudoplatystoma fasciatum, obtained from induced reproduction, were used to determine the onset of ovarian differentiation and development and to record the main characteristics of this process. Samples were collected from 0 to 240 days post-fertilization (dpf) and the results classified into stages I-XII. Ovarian formation was histologically detected for the first time when juveniles measured mean ± s.d. 51·5 ± 8·3 mm total length (LT ) at 39-45 dpf (stages I-V), with intense somatic cell proliferation originating in the ovarian cavity. Both LT and age of fish had a positive correlation (P < 0·001) with ovarian differentiation, but LT showed a greater correlation (r(2) = 0·95) than age (r(2) = 0·85), especially during the initial stages of development. From stages VI to VII, the ovarian cavity was enlarged and undifferentiated oogonia were present. At stage VIII, small projections formed in the ovarian stroma towards the ventral region of the gonad (future ovarian lamellae) and the basal membrane and differentiated oogonia nests could be seen. At stages IX and X, the germ cells entered meiosis and folliculogenesis was completed by stages XI and XII, which can be considered late in comparison to other Siluriformes. This study has demonstrated that ovarian differentiation in P. fasciatum begins with an intense proliferation of squamous epithelial cells (somatic cells) during the early stages of development and that sex inversion protocols could, thus, be applied successfully before this period. Furthermore, the results have demonstrated that both size and age can influence gonad differentiation and development in this species.

Patch testing with nickel sulfate: comparison between 2 nickel sulfate preparations and 2 different test sites on the back.

Among patients routinely undergoing patch testing for suspected allergic contact dermatitis (ACD), nickel is the most frequently sensitizing hapten, with a clear predominance in the female population. However, some patients who report the appearance of dermatitis upon exposure to metal objects show negative patch test results to a nickel sulfate 5% pet. application. In some cases, a positive response to nickel can be observed simply by repeating the patch test. The objective of our study was to assess if, during routine patch testing, positive responses to nickel sulfate are missed owing to contingent problems, referring to application site, patch test execution or variations in skin reactivity. To this end, we applied 2 different patch test materials containing nickel sulfate 5% pet. to 3040 consecutive patients, undergoing patch testing for suspected allergic contact dermatitis, during the same session. The rôle of the test site was also investigated by applying the preparation on 2 different sites of the back in 30 patients. Of the whole, 612 patients (20%) showed positive patch test responses. The 2 nickel materials were almost equivalent: 78% of nickel-sensitive patients had positive reactions to both, whereas 11% showed a positive response to 1 preparation alone. No variations in patch test responses in relation to application site were observed. Our data show that false-negative patch test responses to nickel are frequent. The use of 2 different preparations during the same patch test session increases the response rate by 10%.

Contact sensitization in children.

Our study concerns contact sensitization in children, the frequency of which is still debated in the literature, even though specific reports are increasing. During a 7 year period (1988-1994) 670 patients, 6 months to 12 years of age, were patch tested with the European standard series, integrated with 24 haptens, at the same concentrations as for adults. We observed positive results in 42% of our patients. Thimerosal, nickel sulfate, Kathon CG, fragrance mix, neomycin, wool alcohols, and ammoniated mercury induced most of the positive responses. The highest sensitization rate was found in children from 0 to 3 years of age. Comments on main positive haptens are reported. Seventy-seven percent of our sensitized patients were atopics, suggesting that atopy represents a predisposing factor for contact hypersensitivity. Patch testing represents a useful diagnostic procedure for the definition of childhood eczematous dermatitis and for the identification of agents inducing contact sensitization which is frequently associated with atopic dermatitis.

Cross-sensitizations between azo dyes and para-amino compound. A study of 236 azo-dye-sensitive subjects.

Combined sensitizations to different azo dyes, probably based both on true cross-sensitization and on simultaneous positive reactions, have frequently been described. However, since azo dyes are included in the standard series in a minority of countries, the case studies considered comprise, with few exceptions, a small number of subjects. The aim of our study was to investigate cross-reactions between different azo dyes and para-amino compounds in azo-dye-sensitive subjects, to study the clinical aspects of azo dye dermatitis, to assess the relevance of sensitization to azo dyes, and to relate the pattern of cross-sensitizations to the chemical structure of the different dyes. Out of 6203 consecutively tested patients, 236 were sensitized to at least 1 of 6 azo compounds employed as textile dyes, included in our standard series. 107 subjects reacted to Disperse Orange 3 (DO3), 104 to Disperse Blue 124 (DB124), 76 to p-aminoazobenzene (PAB), 67 to Disperse Red 1 (DR1), 42 to Disperse Yellow 3 (DY3), and 31 to p-dimethylaminoazobenzene (PDAAB). Co-sensitizations to para-phenylenediamine were present in most subjects sensitized to DO3 (66%) and PAAB (75%), in 27% and 36% of DR1 and DY3-sensitive subjects, and only in 16% of subjects sensitized to DB124. Apart from the hands and the face, the neck and the axillae were the most frequently involved skin sites. Whereas the involvement of flexural areas was mainly connected with sensitization to DB124, in patients with hand dermatitis and in those working as hairdressers, sensitization to DO3 and PAAB was more frequent. Moreover, in the former patient group, a history of textile dye allergy was most frequently obtained. Out of 33 patients tested with an additional textile dye series, only 5 subjects reacted to anthraquinone dyes. Cross-sensitizations between azo dyes and para-amino compounds can partially be explained on the basis of structural affinities.

Sensitization to reactive textile dyes in patients with contact dermatitis.

Reactive dyes are used especially for colouring natural fibres (cotton, silk and wool) that are widely used in Western countries, particularly Italy, in the production of clothes. The aim of our study was to investigate sensitization to the most commonly used reactive textile dyes in patients undergoing patch tests, and to assess the clinical relevance of contact sensitization to these dyes. 1813 consecutive patients underwent patch tests with the GIRDCA standard series and an additional textile series of 12 reactive dyes. 18 of these patients were sensitized to reactive dyes (0.99%) (4 only to reactive dyes). The dyes most frequently responsible for positive patch tests were Red Cibacron CR and Violet Remazol 5R (respectively, 8 and 5 positivities). In 5 cases only was a history of intolerance to particular garments given; of 4 patch tests performed with pieces of garment, 2 were positive. In 1 occupationally-exposed patient, airborne contact dermatitis was suspected. Owing to the lack of up-to-date patch test series, some cases of allergic contact dermatitis from textile dyes are probably misdiagnosed: new colouring agents are continuously introduced to the market, so that a close relationship with textile industry is necessary to improve our diagnostic tools.

Contact allergy to Dermatophagoides in atopic dermatitis patients and healthy subjects.

To compare different house-dust-mite-derived allergenic materials and to correlate the presence of IgE to Dermatophagoides with patch test results, 313 atopic dermatitis (AD) patients and 100 healthy volunteers (HV) underwent patch tests with: Dermatophagoides pteronyssinus (DPT) lyophilized purified alpha fraction in buffered saline/glycerol 50% and/or in petrolatum (Bayropharm); 50% DPT and 50% Dermatophagoides farinae (DF) whole bodies in petrolatum and petrolatum oil (Allergopharma-Bracco); DPT and DF whole bodies in petrolatum and petrolatum oil (Lofarma). We found 39% positive reactions among AD subjects and 13% in HV. The presence of serum-specific IgE did not influence the patch test results. 38% of AD patch-test-positive patients and 4 of 13 HV, respectively, showed a positive prick test and/or RAST to Dermatophagoides. Similar sensitization rates were observed with the allergenic material from Bayropharm (54% positives) and Allergopharma-Bracco (51% positives), whereas the preparations from Lofarma gave a 20% response rate.

Pretreatment of the test area with 1-day occlusion improves the response rate to NiSO4 5% pet. patch tests in subjects with a positive history of nickel allergy.

A group of 58 women, aged 18 to 51 years, with a clinical history of nickel allergy, who exhibited equivocal or negative reactions to nickel sulfate 5% pet. patch tests performed on the skin of the back, were recruited consecutively from the patch test clinic from September 1993 to June 1994. In order to improve the response rate to NiSO4 5% pet. patch tests, a testing procedure utilizing pretreatment of the test area by 1-day (24-h) occlusion was introduced. Patients underwent 2 patch tests on adjacent sites of the volar surface of both forearms. 3 of the patch tests were performed with 40 mg nickel sulfate 5% pet., whereas a control test was carried out by occluding with an empty chamber. 2 of the nickel sulfate test sites were pretreated with 1-day occlusion performed with an empty chamber. A visual grading system and echographic measurement were used to quantify the responses 30-40 min after patch test removal. Echographic evaluations were carried out using a 20 MHz B-scanner. Measurement of skin thickness and determination of the hypoechogenic dermal area, both considered to be parameters of inflammation, were used to evaluate the intensity of the allergic reaction. At the 3-day (72-h) evaluation, 19 subjects out of 58 clearly showed positive reactions to nickel sulfate 5% pet. at pre-occluded skin sites. Moreover, values of skin thickness and of 0-30 areas at positive pre-occluded nickel test areas were higher in respect to control test areas, confirming clinical evidence of increased response to NiSO4 after occlusion.

Prevalence of contact allergy to non-disperse azo dyes for natural fibers: a study in 1814 consecutive patients.

5 non-disperse azo dyes, used for colouring natural fibers, were added to the standard patch test series, as 5% pet. preparations. 1814 consecutive patients attending the patch test clinic were patch tested, of whom 16 (0.88%) reacted to the newly added dyes: 8 to Direct Orange 34, 5 to Acid Yellow 61, 2 to Acid Red 359 and 1 to Acid Red 118. On the basis of clinical history and results of patch tests with pieces of fabrics, contact sensitization to non-disperse azo dyes seemed to be related to the appearance of skin lesions at least in 8 subjects. We conclude that systematic exploration of the sensitizing potential of textile dyes, selected after careful investigation, can provide additional information on the frequency of occurrence of textile dye dermatitis, supporting individual investigation in sensitized subjects.

Positive patch tests to whole mite culture and purified mite extracts in patients with atopic dermatitis, asthma, and rhinitis.

Patch tests with Dermatophagoides were carried out by different authors on patients with atopic dermatitis (AD) employing methods varying both in the type of allergen and in the way of performing the test. In order to examine and compare different methods and various allergenic materials and to define better the indications for this test, we performed patch tests with whole mite culture or purified mite extracts on 72 patients with AD, 40 subjects with mucosal atopy, and 32 healthy volunteers, employing different techniques of application. Positive results were obtained in 51.5% of patients with AD with specific IgE to Dermatophagoides, in 43.6% of patients with AD without this specific IgE and in 40% of subjects affected by mucosal atopy and having specific IgE to Dermatophagoides. From a technical point of view the simple application of the allergenic material on healthy skin gave the best results. Our data show that patch tests with Dermatophagoides extracts could contribute to a better immunoallergologic characterization both of patients with AD and patients with mucosal atopy.

Contact sensitization to textile dyes: description of 100 subjects.

We have described 100 subjects sensitized to textile dyes. Of these, 16 had clinically been suspected of having a textile dermatitis from among 1145 patients referred for patch testing. 41 patients were identified from among 861 consecutive subjects tested with the GIRDCA (Italian Research Group on Contact and Environmental Dermatitis) standard series supplemented with 4 disperse dyes (Disperse Blue 124, Disperse Red 1, Disperse Yellow 3, Disperse Orange 3). The remaining 43 patients were identified from among 746 subjects tested with the GIRDCA standard series, supplemented with the 4 disperse dyes mentioned above and a further series of 12 other textile dyes. The clinical picture was extremely variable: most patients had a typical eczematous dermatitis, but we also observed persistent erythematous-wheal-type reactions, a transient urticarial dermatitis and an erythema-multiforme-like eruption. Among these textile dyes, Disperse Blue 124 caused most reactions. With the addition of the 4 disperse dyes to the GIRDCA standard series, we identified 4.8% sensitized to textile dyes, a much higher figure than the 1.4% observed among patients being patch tested on the basis of their history and the clinical findings; the addition of a further 12 textile dyes to the series further increased the detection rate to 5.8%. We stress the importance of routinely patch testing with textile dyes, which can help to elucidate the cause of certain kinds of atypical dermatitis.

Patch and prick test study of 593 healthy subjects.

593 recruits selected by the Military Health Service as being healthy and without a history of present or previous dermatitis, or ocular refraction defects, were patch tested with the GIRDCA (Italian Research Group on Contact and Environmental Dermatitis) standard series. Of these, 336 were also patch tested with substances used in the processing and dyeing of textiles and prick tested with 8 major allergens. 74 (12.5%) reacted to 1 or more substances. The most frequent sensitizers were: thimerosal (28 cases), ammoniated mercury (7 cases), phenol-formaldehyde resin (6 cases), parabens, nickel and Disperse Red 17 (4 cases each). 113 recruits reacted to 1 or more prick test allergens. We have demonstrated the importance of establishing such reference values in healthy groups for the correct evaluation of data collected from selected groups.

Contact sensitization among ceramics workers.

139 workers from 3 ceramics factories underwent dermatological and allergological examination, using standard and occupational patch test series, in order to evaluate the prevalence of dermatitis and contact sensitization, to identify the most important sensitizing substances in the ceramics industry, and to correlate the results with possible risk factors such as atopy. Hand dermatitis had affected 37% of the subjects examined. 27% of the workers were sensitized to 1 or more allergens. Of 52 subjects with dermatitis, 37% had allergic contact dermatitis and 63% irritant contact dermatitis. 18 subjects were found to be sensitized without showing any previous or present clinical symptoms. Atopy tended towards correlation with the overall incidence of dermatitis, though not with the prevalence of sensitization.

[Contact sensitization to thimerosal in healthy subjects]. / Sensibilizzazione per contatto al thimerosal nella popolazione sana.

The aim of our study was to evaluate the prevalence of thimerosal allergy in subjects free of dermatitis. 256 recruits, selected by the Military Health Authorities as healthy subjects, without dermatitis or ocular defects, underwent allergological examination. The percentage of sensitization observed (6.25%) was compared to that found among 2150 patients, consecutively admitted to the Allergological Service of our Department, with suspected allergic dermatitis. Here we found 76 positivities (3.53%). Contact sensitization to ammoniated-mercury is lower among thimerosal-negative subjects (1.88%) than among both the healthy group of thimerosal-positive subjects (12.5%) and thimerosal-positive patients (11.84%). In the group of 76 positive patients it was not possible to relate the sensitization to thimerosal to either a particular clinical dermatological picture or to a specific exposure.