Occupational allergic contact dermatitis and composition of acrylates in dentin bonding systems

Background Dentin-bonding systems contain sensitizing acrylates. They are increasingly used in dentistry, but only few cases of allergy have been encountered. Objective This study reports observations on eleven patients sensitized by acrylates in dentin-bonding compounds. Furthermore, the composition of dentin-bonding products was analysed and compared with the information given in the material safety data sheets. Methods Patch testing was performed to reveal allergic contact dermatitis, and chamber provocation tests to reveal possible respiratory sensitivity. Gas chromatography/mass spectrometry was used to analyse the chemical composition of the bonding products. Results The most common sensitizer in our material of eleven patients was 2-hydroxyethyl methacrylate (2-HEMA). Another putative sensitizer, BIS-GMA, used in dentin adhesives, did not cause sensitization. The typical allergic dermatitis localized to the fingertips (pulpitis). Seven of the eleven patients also developed paresthesia of the fingertips. One patient with positive patch test reactions to (meth)acrylates had pharyngitis hut no skin symptoms. One patient was sensitized because she had been patch tested with too high a concentration (undiluted) of dentin-bonding components. Material safety sheets gave inaccurate or wrong information about the contents. Conclusion Dentin-bonding acrylates are strong sensitizers, and even a single exposure may sensitize.     

Immunohistochemistry of lymphocytes and Langerhans' cells in long-lasting allergic patch tests

A long-lasting allergic patch test is a "normal" allergic patch test that remains positive for weeks or months. An immunohistochemical study of immunocompetent cells in the skin in this rare type of patch tests was performed. Most inflammatory cells were T11 positive T-lymphocytes. The majority of these cells were of the helper/inducer phenotype (T4+), but a relative increase of T8+ cells as compared to the initial (1-2d) stages of allergic patch tests was observed. T6+ Langerhans' cells (LCs) were normal or increased in number in the epidermis, while very few dendritic cells displayed Ial antigen in the epidermis, indicating loss of Ial-staining of LCs. High to very high numbers of T6+ cells were found in the dermis. An inflammatory reaction of hair follicles with moderate numbers of T6+ cells in the peribulbar infiltrate was observed indicating that hair follicles might act as shunt pathways for allergens. A defect in down regulation of the contact hypersensitivity reaction and/or a constant antigen stimulation could be responsible for the long-lasting allergic patch tests.     

Estrogen receptor genotype modulates myocardial perfusion in young men

Most of the effects of estrogens are mediated by estrogen receptors. Vascular endothelial cells and smooth muscle cells express estrogen receptor (ESR1) in both genders. A long genotype group of a common thymine-adenine (TA) dinucleotide repeat polymorphism in the regulatory region of this gene has previously been related to coronary artery disease. The present study examined whether coronary blood flow is affected by this genotype. A total of 49 healthy men were genotyped by PCR and divided into three groups according to median number of the ESR1 promoter TA repeat (=19), i.e., in the short allele genotype group both alleles were of fewer than 19 repeats whereas in the long allele group both alleles were 19 repeats or more. The intermediate group comprised men who had one short and one long allele. Myocardial blood flow was measured by positron emission tomography using [¹⁵O]water, performed at rest and during adenosine stimulation. Men with long alleles had lower adenosine-stimulated coronary flow than those with short alleles and those with one short and one long allelle. Our results suggest that adenosine-stimulated myocardial perfusion is lower in subjects with ESR1 long alleles than the other TA repeat genotypes.     

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the in vivo and in vitro dechlorination of pentachlorophenol

The metabolism of pentachlorophenol has been studied in the rat after pretreatments with phenobarbital, 3-methyl-cholanthrene or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In addition to the previously identified metabolite, tetrachloro-p-hydroquinone, trichloro-p-hydroquinone has been identified in urine as a metabolite. The formation of the latter represents a type of dechlorination different from that of the formation of tetrachlorohydroquinone. The inducing agents, 3-methylcholanthrene and TCDD have similar effects on the dechlorination and increase the formation of tetrachloro-p-hydroquinone more pronounced than does phenobarbital. In contrast to phenobarbital they also increase the formation of trichloro-p-hydroquinone and the total elimination of pentachlorophenol and its metabolites. The in vivo findings are supported by in vitro studies with microsomes from rats pretreated with phenobarbital or TCDD. Use of the inhibitor -diethylaminoethyl-diphenyl propylacetate (SKF 525-A) in vitro showed a more pronounced inhibition on microsomes from phenobarbital-treated rats than on microsomes from untreated or TCDD-treated rats.Gas chromatography-mass spectrometry have been used for the identification and quantification of pentachlorophenol and its metabolites.

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Zusammenfassung Der Metabolismus von Pentachlorphenol nach Vorbehandlung der Versuchstiere (Ratten) mit phenobarbital, 3-Methylcholantren oder 2,3,7,8-Tetrachlordibenzo-p-Dioxin (TCDD) ist untersucht worden. Zu dem schon früher nachgewiesenen Metaboliten Tetrachlor-p-Hydrochinon wurde nun auch Trichlor-p-Hydrochinon als Harnmetabolit festgestellt. Die Bildung des letzteren stellt eine andere Art von Dechlorierung dar als diejenige die bei der Entstehung von Tetrachlor-p-Hydrochinon vorliegt. 3-Methylcholantren und TCDD haben ähnlichen Einfluß auf die Dechlorierung und steigern die Bildung von Tetrachlor-p-Hydrochinon mehr ausgeprägt als es bei phenobarbital der Fall ist. Im Gegensatz zu phenobarbital steigern sie auch die Bildung von Tri-chlor-p-Hydrochinon sowie die totale Eliminierung von Pentachlorphenol und von Metaboliten. Die in vivo-Befunde werden von in vitro-Studien mit Mikrosomen von mit phenobarbital oder TCDD vorbehandelten Ratten gestützt. Anwendung des Inhibitors -Diethylaminoethyl-Diphenyl-Propylacetat (SKF 525-A) zeigte in vitro eine ausgeprägtere Inhibition der Mikrosomen von mit phenobarbital behandelten Ratten als der Mikrosomen von unbehandelten oder TCDD-behandelten Ratten. Nachweis und Bestimmung von Pentachlorphenol und seinen Metaboliten wurden gaschromatographisch-massenspektrometrisch durchgeführt.