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Biomedical subjects

S Fregert

Publications and source records attributed to S Fregert.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1984

An attempt to isolate and identify allergens in lanolin.

One sensitizer, a sterol, has previously been reported to be present in lanolin. In this study, a related substance, a sterol, with a molecular weight of 424 has been isolated. A few sensitive subjects did not react to this substance. Lanolin probably contains several sensitizers. Sensitization to lanolin in guinea pigs seems previously to have failed. In this study, a methanol extract of a lanolin preparation containing large amounts of sterols sensitized guinea pigs.

Allergens↗
PubMed1984

Contact sensitivity to nickel in white gold.

Nickel release from white gold discs stored at room temperature for 1 week in synthetic sweat was analyzed. The nickel content of the discs was 2-15%. The nickel release from the discs was 0.09-0.82 microgram. Rhodium plating reduced the nickel release to 0.04-0.54 microgram. 18 nickel-sensitive women were patch tested with the white gold discs and all showed at least 1 positive patch test reaction. All the white gold discs gave a negative dimethylglyoxime test.

Dermatitis, Contact↗
PubMed1984

Nickel release from ear piercing kits and earrings.

Ear piercing with nickel-alloyed studs/clasps involves considerable risk of nickel sensitisation. Stainless steel studs/clasps for ear piercing and different types of earring were stored in synthetic sweat for 1 week. The nickel release was determined. One "hypoallergenic" stud/clasp released 0.005 microgram Ni; 21 unused studs/clasps and earrings released 0.05-3 microgram Ni, and 11 unused studs/clasps and earrings released 6-25 micrograms Ni. 6 earrings which caused dermatitis released 14-442 micrograms Ni. Thus, all studs/clasps and earrings released nickel. Neither gold nor silver plating prevented the nickel release. Nickel-sensitive women were asked to wear studs/clasps releasing various amounts of nickel. The most sensitive of them showed eczematous reactions to studs/clasps releasing nickel down to 0.05 micrograms. The dimethylglyoxime test was positive only when more than 10 micrograms Ni was released.

Alloys↗
PubMed1984

Contact allergy to styrene and related chemicals.

One patient, sensitive to styrene, cross-reacted at patch testing to 2-,3-and 4-vinyltoluene (2-,3-and 4-methylstyrene) and to the metabolites styrene epoxide and 4-vinylphenol (4-hydroxy-styrene). It is assumed that styrene is a prohapten metabolized in the skin by aryl hydrocarbon hydroxylase (AHH) to styrene epoxide acting as the true hapten. Styrene occurs in nature and as a synthetic product. Vinyltoluenes (methylstyrenes) occur as synthetic products in plastics. 4-vinylphenol (4-hydroxystyrene) occurs frequently in different ciders, wines, foods and berries, e.g. cloudberry.

Dermatitis, Atopic↗
PubMed1984

Contact dermatitis from the epoxy resins tetraglycidyl-4,4'-methylene dianiline and o-diglycidyl phthalate in composite material.

An outbreak of dermatitis occurred in an aircraft factory using epoxy resin composite material. Of 25 operatives, 14 gave positive patch test reactions to the composite material and/or diglycidylether of bisphenol A (DGEBA), tetraglycidyl-4,4'-methylene dianiline (TGMDA), and o-diglycidyl phthalate. This report seems to be the first to demonstrate contact allergy to the two last mentioned epoxy resins. The diglycidylether of bisphenol A used in routine test series picked up only 3 cases of 12 tested.

Aniline Compounds↗
PubMed1984

Patch testing with colophony.

Colophony (rosin) has been fractionated into 2 parts, an acidic and a neutral fraction. Routine patch testing with neutral components gives positive reactions at a 40% higher frequency than routine patch testing with colophony (20%) (w/w in pet.). A concentration of 60% colophony is suggested for routine patch testing.

Dermatitis, Contact↗
PubMed1984

Occurrence of para-aminobenzoic acid and benzocaine as contaminants in sunscreen agents of para-aminobenzoic acid type.

Para-aminobenzoic acid (PABA) and some of its esters, such as amyl para-dimethylaminobenzoate, ethyl 4-bis(hydroxypropyl)aminobenzoate, 2-ethylhexyl para-dimethylaminobenzoate and glyceryl para-aminobenzoate are used as sunscreen agents. Methods for separating PABA and the 5 mentioned PABA esters by thin layer chromatography and high pressure liquid chromatography (HPLC) are presented. Contamination with PABA and benzocaine were measured quantitatively by the HPLC technique in samples of the 4 PABA esters, using different brands and different batches of the same brand. PABA was detected in all 12 samples examined and benzocaine in 11. The degree of contamination was batch-dependent. Minimal amounts of PABA and benzocaine were found in most batches but in glyceryl para-aminobenzoate both substances were present at a level above 0.1% (w/w). High levels of benzocaine were also detected in batches of ethyl 4-bis(hydroxypropyl)-aminobenzoate.

4-Aminobenzoic Acid↗
PubMed1983

Contact allergy to trimethylolpropane triacrylate (TMPTA) in an aziridine plastic hardener.

4 workers developed hand and face dermatitis when exposed to a floor top coat. This contained a polyurethane and a polyfunctional aziridine hardener and additives. The aziridine hardener was made by reacting propyleneimine with a polyfunctional acrylate, trimethylolpropane triacrylate (TMPTA). All 4 reacted to the hardener and to TMPTA, which is present in excess. 2 of them also reacted to pentaerythritol triacrylate (PETA), which can be used in the production of aziridine hardeners. TMPTA and PETA cross-react, and are known sensitizers in UV-hardening acrylates. The present finding shows that well-known sensitizers can be found in hidden sources when used in a quite different chemical process.

Acrylates↗
PubMed1983

Nickel in tap water.

Nickel analyses of tap water from several sources in Copenhagen gave up to 490 X 10(-6) g X 1(-1) in the first 250 ml portions. Hot water gave higher values than cold water. After flushing for 5 min, low values were found. Considerable variation from time to time and from tap to tap was found. Drinking of only the first portion in the morning might have an influence on nickel hand eczema.

Adult↗