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Biomedical subjects

S Fregert

Publications and source records attributed to S Fregert.

At least 19 recordsLinked to original sources
PubMed1990

Patch testing with cement containing iron sulfate.

Addition of iron sulfate to cement means transformation of water-soluble hexavalent chromium into nonwater-soluble trivalent chromium. This has been the basis for preventive measures concerning sensitization to hexavalent chromium (chromate) in cement. For some years, iron sulfate has been added to cement manufactured in the Scandinavian countries. In the present in vivo study, cements with and without iron sulfate were compared concerning their capacity to elicit allergic patch-test reactions in eight chromate-hypersensitive individuals. No patch-test reactions were obtained from a water extract of cement with iron sulfate when appropriately buffered.

Chromium↗
PubMed1988

Physicochemical methods for detection of contact allergens.

In the same way that it often is necessary to perform chemical and biological analysis of skin and body fluids in the management of skin disease, it may be necessary to analyze the chemical environment. Some analyses, such as those for nickel, chromate, and formaldehyde, require only simple tests. Others require complex and expensive equipment and specialized skills. In the future, it may become necessary to install some of this equipment for routine use in dermatology clinics. In the meantime, the dermatologist needs to be aware of the possibilities.

Acids↗
PubMed1987

Contact allergy to the active ingredients of Kathon CG.

The preservative Kathon CG is a commercial preparation, consisting of 2 active ingredients and other components. 28 patients with contact allergy to Kathon CG participated in a study in which patch testing was performed with serial dilutions, and with 5 chromatographically separated fractions. All reacted to fraction IV, and 2 patients also to fraction II. Mass spectrometry and nuclear magnetic resonance spectrometry identified fraction II and IV to be the active ingredients; 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one.

Dermatitis, Contact↗
PubMed1987

Contact allergy to the active ingredients of Kathon CG in the guinea pig.

Preservative Kathon CG (K-CG) is a commercial preparation, consisting of the two active ingredients (a.i.), 2-methyl-4-isothiazolin-3-one (243-K-CG) and 5-chloro-2-methyl-4-isothiazolin-3-one (5243-K-CG) and also of other components. Both a.i. are known contact sensitizers in humans. In this study guinea pig maximization tests were performed with the a.i. in order to assess and compare the degrees of the sensitizing capacities. The animals were also rechallenged with the sensitizer and 4 chemically related compounds, all being preservatives or known ingredients in preservatives, in order to study the cross-reaction patterns. 5243-K-CG was demonstrated to be a strong sensitizer and 243-K-CG a weak sensitizer. With 5243-K-CG as the sensitizer, 4.5-dichloro-2-methyl-4-isothiazolin-3-one was a possible cross-reacting compound. Possible cross-reactivity was indicated between the a.i. when 243-K-CG was the sensitizer.

Animals↗
PubMed1986

Contact allergy to 4,4'-dihydroxy-(hydroxymethyl)-diphenyl methanes: sensitizers in a phenol-formaldehyde resin.

A particular phenol-formaldehyde resin of the resol type (P-F-R-2) was shown in a previous study to be a good tracer of patients with contact allergy to phenol-formaldehyde resins. Eleven patients with sensitivity to P-F-R-2 participated in the study in which chromatographically separated fractions of P-F-R-2 were patch tested. This procedure was repeated until a positive reaction to a single substance was noted. In this study 3 new sensitizers are reported. Investigations by mass spectrometry and nuclear magnetic resonance spectrometry identified the compounds to be 4,4'-dihydroxy-3-(hydroxymethyl)-diphenyl methane (4,4'-H-3-HPM), 4,4'-dihydroxy-3,3'-di-(hydroxymethyl)-diphenyl methane (4,4'-H-3,3'-HPM), and 4,4'-dihydroxy-3,5-di-(hydroxymethyl)-diphenyl methane (4,4'-H-3,5-HPM). Six of the 11 patients reacted to at least one of these compounds. All 6 patients reacted to 4,4'-H-3,3'-HPM and 5 reacted simultaneously to 4,4'-H-3-HPM. Four patients reacted to all 3 compounds tested. By patch testing with serial dilutions (ethanol 99.5%) of the three 4,4'-H-HPM, positive reactions were noted down to 0.5 X 10(-6)%, 1.0 X 10(-6)%, and 1.3 X 10(-3)% w/v for 4,4'-H-3-HPM, 4,4'-H-3,3'-HPM, and 4,4'-H-3,5-HPM, respectively.

Allergens↗
PubMed1986

Contact allergy to the preservative Kathon CG.

Of 976 patients routinely patch tested with Kathon CG (Rohm & Haas), 300 ppm, 43 (4.4%) gave a positive reaction. Of 170 patients routinely tested with Kathon CG 250 ppm, 10 (5.9%) gave a positive reaction. Out of 34 patients tested with serial dilutions of Kathon CG, 17 (50%) reacted to 100 ppm, 8 to 30 ppm and 2 to 10 ppm. The concentration of 1000 ppm of Kathon CG was irritant in some cases, but 300 ppm was not irritant. Of the 976 patients tested with Kathon CG 300 ppm, 8 (0.8%) showed a "flare-up" reaction, indicating patch test sensitization. Of the 170 tested with Kathon CG 250 ppm, 2 (1.2%) were sensitized. When the patch-test-sensitized patients were retested with serial dilutions, they showed the same pattern as the other patients. 13 sensitized patients were use tested and 7 (54%) gave responses. In the literature, Kathon CG 100 ppm is recommended as the routine patch test concentration. However, 50% of the sensitive persons may then be overlooked. In our clinics, Kathon CG has become the second most common contact sensitizer, but the sensitivity cannot be traced in all patients with clinically relevant allergy without an unacceptable risk of patch test sensitization.

Biopsy↗
PubMed1986

Demonstration of Kathon CG in some commercial products.

The preservative Kathon CG has become one of the most common sensitizers. It has, however, been difficult to explain the sensitization and to assess the clinical relevance of the contact allergy, partly due to lack of specification of the preservative in products. A high-performance liquid chromatography method was used to demonstrate Kathon CG in 123 commercial products of both "leave on" and "rinse off" types. 38 of these contained Kathon CG in the range of 1-15 ppm of active ingredients. There were no differences between "leave on" and "rinse off" products concerning the relative number of products containing Kathon CG and the concentrations of the preservative.

Allergens↗
PubMed1985

Occupational health reporting systems in Sweden.

Legislation covering worker's compensation influences occupational health reporting and data gathering. Five programs recently enacted in Sweden are outlined and discussed. These include: 1) Labour Market No-Fault Liability Insurance, 1974; 2) The National Sickness Insurance Act, 1977; 3) The Work Injury Insurance Act, 1977; 4) The Work Environment Act, 1977; 5) The Occupational Injury Information System, 1979.

Humans↗
PubMed1985

Allergic contact dermatitis to epoxy resin in ostomy bags.

Six ostomy patients presenting with peristomal rashes have been shown to be allergic to their ostomy bags and to epoxy resin. Subsequent investigation confirmed the presence in the bags of low molecular weight epoxy resin oligomers, which are known as potent contact sensitizers.

Colostomy↗
PubMed1985

Contact allergy to phenol-formaldehyde resins.

Adverse reactions to phenol-formaldehyde resins include depigmentation, irritant dermatitis, chemical burns and allergic contact dermatitis. Allergic contact dermatitis from phenol-formaldehyde resin has mainly been ascribed to resins based on paratertiary-butyl phenol and formaldehyde, and such a resin is included in the ICDRG standard patch test series. When 1220 patients were patch tested with this resin as well as with 2 other phenol-formaldehyde resins, based on phenol and formaldehyde, 26 patients were positive to at least 1 resin. The figures for positive reactions to paratertiary-butyl phenol-formaldehyde resin and the 2 other resins were 0.8%, 1.0% and 3.0% (440 tested subjects), respectively. Therefore, a battery of phenol-formaldehyde resins should be used for screening purposes, since patch testing with the paratertiary-butyl phenol-formaldehyde resin is not sufficient to identify patients with contact allergy to phenol-formaldehyde resins. Several of the 26 patients were patch tested with the basic substances phenol, formaldehyde and paratertiary-butyl phenol, but only 1 positive reaction to formaldehyde was noted. The sensitizing capacity of 2-methylol phenol, 4-methylol phenol and 2,4,6-trimethylol phenol, all 3 compounds being possible ingredients of resins based on phenol and formaldehyde, was demonstrated; 5 of 14 resin positive patients reacted to at least 1 of these methylol phenols.

Chemical Phenomena↗
PubMed1985

Effect of ultraviolet irradiation of photopatch test substances in vitro.

The mechanisms behind allergic photocontact reactions are not clear. For certain photoactive substances the generation of photoproducts may be one step in the sequence of events inducing photoallergy. 26 photoactive substances were studied by thin layer chromatography (TLC) before and after long-wave or medium-wave ultraviolet irradiation for 1, 3 and 5 h (10.8, 32.4, 54 J/cm2 and 1.1, 3.2, 5.4 J/cm2). The formation of photoproducts was demonstrated for 13 substances. For 8 of these, photoproducts were formed regardless of type of ultraviolet exposure while for 5 compounds photoproducts were demonstrated only after long-wave ultraviolet irradiation. All photoactive compounds forming photoproducts did so after UVA irradiation which is in accordance with the finding of action spectra for photoallergic reactions in human skin within this region. No photoproducts were demonstrated for 13 of the tested substances.

Allergens↗
PubMed1984

A simple method for the detection of formaldehyde.

The commonly used chromotropic acid method for the determination of formaldehyde sometimes produces a masking discolouration. We have therefore evaluated a complementary method in which acetylacetone is used as the reagent. By a combination of the 2 methods, formaldehyde can be traced in most products.

Cosmetics↗