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.     

Laccase from the white-rot fungus Trametes versicolor: cDNA cloning of lcc1 and expression in Pichia pastoris

A cDNA coding for laccase was isolated from the ligninolytic fungus Trametes versicolor by RNA-PCR. The cDNA corresponds to the gene lcc1, which encodes a laccase isoenzyme of 498 amino-acid residues preceded by a 22-residue signal peptide. The lcc1 cDNA was cloned into the vector pHIL-D2 for expression in Pichia pastoris under the control of the AOX1 promoter. Transformants were found to secrete active recombinant enzyme after induction with methanol. The use of growth medium buffered to pH 6.0 and control of pH during cultivation were found to be important, or even necessary, for obtaining activity in liquid cultures. The effect of exchanging the native secretion signal for the Saccharomyces cerevisiae α-factor pre-pro secretion signal was studied by cloning the portion encoding the mature enzyme into the vector pPIC9. The activity obtained for the construct encoding the native laccase signal sequence was found to be seven-fold higher than for the construct encoding the α-factor secretion signal. Utilisation of the P. pastoris pep4 mutant strain SMD1168 was found to provide a two-fold higher level of activity compared with P. pastoris GS115. Received: 16 May / 8 August 1997     

Isolation of a Trichoderma reesei cDNA encoding GTP: a-d-mannose-1-phosphate guanyltransferase involved in early steps of protein glycosylation

A cDNA coding for GTP: α-d-mannose-1-phosphate guanyltransferase (MPG1 transferase) (EC 2.7.7.13) was isolated from a cDNA library of the Trichoderma reesei RutC-30 strain by suppression of the yeast Saccharomyces cerevisiae mutation in the DPM1gene encoding mannosylphosphodolichol (MPD) synthase. The nucleotide sequence of the 1.6 kb-long cDNA revealed an ORF which encodes a protein of 364 amino acids. Sequence comparisons demonstrate 70% identity with the S. cerevisiae guanyl transferase gene (MPG1) and 75% identity with the Schizosaccharomyces pombe homologue. No similarity was found with the MPD synthase encoded by the S. cerevisiae DPM1 gene. The possibility that cloned cDNA encodes a product with a MPD synthase activity was also excluded by transforming a heterozygous S. cerevisiae dpm1::LEU2/DPM1 diploid, which did not lead to the restoration of viability of the dpm1 spores. Simultaneously, a significant increase in MPG transferase activity, as compared with the wild-type yeast, was observed in cellular extracts when the mpg1 cDNA from Trichoderma was expressed in the S. cerevisiae dpm1-6 mutant. Received: 21 July 1997 / 24 April 1998     

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.     

Myocardial metabolism and hemodynamics during coronary surgery without cardiopulmonary bypass

BACKGROUND: Although renewed interest has recently been shown in coronary artery bypass grafting without cardiopulmonary bypass, no reports are available on myocardial metabolism and hemodynamics during temporary coronary occlusion and rotation of the contracting heart. METHODS: Changes in myocardial energy metabolism and hemodynamics were monitored in 12 patients undergoing elective coronary artery bypass grafting without cardiopulmonary bypass, and the postoperative efflux of creatine kinase-MB mass and troponin T were also determined. RESULTS: There was a significant increase in myocardial production of ATP degradation products (p = 0.026) and lactate (p = 0.004) during the operation. Myocardial oxygen extraction decreased (p = 0.012) in correlation with use of the short-acting beta-blocker, esmolol (r = -0.71). Apart from a decrease in mean arterial blood pressure (p = 0.002), there were no significant hemodynamic changes during the operation. The overall postoperative troponin T and creatine kinase-MB mass changes remained nonsignificant during the first two postoperative days. One patient had a myocardial infarction, diagnosed by electrocardiography, on the second postoperative day, but otherwise there were no major complications. CONCLUSIONS: Coronary artery bypass grafting without cardiopulmonary bypass seems to be well tolerated as only minor changes in myocardial energy metabolism and hemodynamics are observed during the operation.     

Immunohistochemical identification of syncytiotrophoblastic cells and megakaryocytes in pulmonary vessels in a fatal case of amniotic fluid embolism

The histological diagnosis of amniotic fluid embolism (AFE) is based on finding amniotic fluid components in the pulmonary microvasculature. In addition to the distinctive constituents of AFE, placental and decidual tissue fragments as well as isolated trophoblastic cells and megakaryocytes are potentially detectable within pulmonary vessels. The identification of single syncytiotrophoblastic cells (STC), and their differentiation from circulating megakaryocytes (MK) within the lumen of small and medium-sized pulmonary vessels is difficult by classical morphological methods. In a fatal case of AFE, we have successfully detected the simultaneous presence of STC and MK in the pulmonary microvasculature by means of a panel of specific monoclonal (CD61-GpIIIa, -hCG) and polyclonal (FVIII-vW hPL) antibodies. The immunohistochemical analysis for identification of STC and MK should provide more precise data on their incidence and distribution in physiological and pathological conditions as well providing new insights into their physiopathological implications and their correlation with AFE and other gynaecological complications.     

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.

---

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.