Gamma radiation doses to people living in Western Sweden

Indoor environments contribute to gamma radiation in the general population. The aims of the present study were to investigate average gamma radiation doses in a rural and an urban area of Sweden, compare indoor dose rates with personal exposure, and study the effects of building characteristics on radiation levels. Radiation was measured with thermoluminescence dosimeters (TLDs). Repeated measurements were performed with TLDs worn by participants (n=46) and placed in their dwellings. Personal dose rates were 0.092microSv/h (rural) and 0.096microSv/h (urban). The mean effective gamma dose rates in dwellings were 0.091microSv/h (rural) and 0.11microSv/h (urban), which are higher than the world average. Dose rates in apartments were higher than in detached houses and higher for concrete than wooden dwellings. Personal dose rates were strongly associated with dwelling dose rates (r(p)=0.68, p<0.01) and could be modelled. Within-participant variability was low.

How to optimize patch testing with diphenylmethane diisocyanate

We have previously shown that patch test preparations of polymeric diphenylmethane diisocyanate (PMDI) are more stable than preparations of diphenylmethane-4,4'-diisocyanate (4,4'-MDI). This study was conducted to (i) investigate whether PMDIs yield as many positive reactions as 4,4'-MDI, (ii) study concurrent reactions to 4,4'-MDI and 4,4'-diaminodiphenylmethane (4,4'-MDA), and (iii) follow the course of positive reactions during 4 weeks. It was shown that PMDIs detect as many positive reactions as 4,4'-MDI. Thus, they are better patch test agents being more stable than preparations of 4,4'-MDI. We recommend that PMDIs with a monomer content of at least 35% is used in 2.0% petrolatum (pet.) (i.e. monomer patch test concentration approximately 0.7%). It was shown that reactions to 4,4'-MDI and PMDIs appear late and we recommend readings on both day (D) 3/4 and D7. 4,4'-MDA was shown to be a good marker for 4,4'-MDI and patch testing with 4,4'-MDA in 0.25% pet. can be used instead of PMDI. Concomitant reactions to 4,4'-MDI and 4,4'-MDA are probably not caused by conversion of 4,4'-MDI into 4,4'-MDA by reaction with water. Another explanation is a path of reactions leading to ureas and MDI conjugates with skin constituents, which are hydrolysed into 4,4'-MDA. This complex process depends upon several factors and might explain why positive MDI reactions appear after D7.

Which test chambers should be used for acetone, ethanol, and water solutions when patch testing?

For solutions, there is a generally accepted amount to be applied in a Finn Chamber and van der Bend chamber, that is, 15 and 20 microl, respectively. The objective of this study was to determine if the recommended volume is adequate. 12 volunteers were patch tested with green-coloured solutions of water, ethanol, and acetone in the Finn and van der Bend chambers on the back on 2 occasions. On D2 test sites were scored. A negative test equalled a test area not covered to 100%. A positive test meant a completely green-coloured test area. Minor and major spreading was noted. The appropriate amount equalled at the most 5% negative reactions. Major spreading was to be minimized to 5%. For ethanol, 100% positive reactions were noted in both test systems. Major spreading was seen in 23/24 Finn Chambers. No spreading (major or minor) was noted for van der Bend chambers with any of the 3 solutions. With acetone and water, negative reactions in 0-8% were noted both with Finn Chambers and van der Bend chambers. To conclude, water solutions should preferably be tested in Finn Chambers, while ethanol and acetone solutions are better tested in van der Bend chambers.

Risks and possibilities in patch testing with contaminated personal objects: usefulness of thin-layer chromatograms in a patient with acrylate contact allergy from a chemical burn

We report a case of a chemical burn from dipropylene glycol diacrylate (DPGDA) spilt on working shoes, followed by active sensitization, thus giving an occupational allergic contact dermatitis on the patient's dorsal feet. Diagnostic tests included patch testing with acetone extracts made from the different shoe layers and thin-layer chromatograms. An invisible spot on the thin-layer chromatography plate gave a test eczema and was further investigated with gas chromatography-mass spectrometry. DPGDA was detected in the spot.

Contact allergy to acrylates/methacrylates in the acrylate and nail acrylics series in southern Sweden: simultaneous positive patch test reaction patterns and possible screening allergens

In a recent study we showed that all our dental personnel/patients were detected with 2-hydroxyethyl methacrylate (2-HEMA) and 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bis-GMA). We studied 90 patients tested to the acrylate and nail acrylics series at our department over a 10 year period to see whether screening allergens could be found. Patch testing with an acrylate and nail acrylics series was performed. Among the 10 acrylate/methacrylate-allergic occupational dermatitis patients tested to the acrylate series, the most common allergens were triethyleneglycol diacrylate (TREGDA, 8), diethyleneglycol diacrylate (5), and 1,4-butanediol diacrylate (BUDA, 5). All 10 of these patients would have been picked up by a short screening series combining TREGDA, 2-hydroxypropyl methacrylate (2-HPMA), and BUDA or 1,6-hexanediol diacrylate (HDDA). Among the 14 acrylate/methacrylate-allergic nail patients, the most common allergens were ethylene glycol dimethacrylate (EGDMA, 11), 2-HEMA, (9), and triethyleneglycol dimethacrylate (9). Screening for 3 allergens i.e. 2-HEMA plus EGDMA plus TREGDA, would have detected all 14 nail patients. A short screening series combining 2-HEMA, EGDMA, TREGDA, 2-HPMA, bis-GMA, and BUDA or HDDA would have picked up all our past study patients (dental, industrial, and nail) with suspected allergy to acrylate/methacrylate allergens.

Recommendation of appropriate amounts of petrolatum preparation to be applied at patch testing

BACKGROUND

No recommendation exists on the amount of petrolatum (pet.) preparation to be applied in a Finn Chamber or van der Bend Chamber.

OBJECTIVES

The aim of this study was to determine the appropriate amount of pet. preparation to apply in the Finn and van der Bend chambers.

METHODS

12 volunteers were patch tested with green-coloured pet. in Finn and van der Bend chambers on the back on 3 occasions. Doses were 10, 15, 20, 25, and 30 mg initially and on second and third occasion, 10 mg was removed in van der Bend Chambers and 35 mg was added. On day 2, the test sites were scored. A negative test equalled a test area not covered to 100%. A positive test meant a completely green-coloured test area. Minor and major spreading was noted. The amount of pet. preparation yielding at most 5% negative reactions and having the least number of reactions with major spreading equalled the appropriate amount.

RESULTS

For van der Bend Chambers, all doses yielded more than 5% negative reactions. For the Finn Chamber, 30, 25, and 20 mg pet. yielded less than 5% negative reactions and with major spreading in 60%, 40%, and 25% of test sites.

CONCLUSIONS

20 mg pet. preparation was the optimal dose for the Finn Chambers.

Characterization of divergent and atypical canine coronaviruses from Sweden

Field canine coronaviruses (CCVs) identified during a series of outbreaks of gastroenteritis in Swedish dogs were subjected to genetic analysis involving the open reading frame 1b (ORF1b) and the membrane (M) and spike (S) protein genes. Four field viruses originating from the Stockholm region presented identical sequences and segregated separately from other CCVs characterized so far and from GOT/05, the variant recovered in Western Sweden. A recombinant origin of the fifth virus identified in the Stockholm region is suggested. In addition, the five viruses originating from the same geographical area displayed atypical 5′ S gene sequences.

Is it possible to improve the patch-test diagnostics for isocyanates? A stability study of petrolatum preparations of diphenylmethane-4,4'-diisocyanate and polymeric diphenylmethane diisocyanate

We have previously shown that the concentration of diphenylmethane-4,4'-diisocyanate (4,4'-MDI) in commercial test preparations was so low that patch testing with the same was not reliable. The stability of 4,4'-MDI in petrolatum (pet.) was compared with pet. preparations of polymeric diphenylmethane diisocyanate (PMDI), which consists of a complex mixture of monomeric isomers and oligomers of MDI. Preparations of 4,4'-MDI and PMDI were stored under 3 different conditions, i.e. at room temperature, refrigerated and frozen. They were analysed continuously during 1 year with regard to the content of 4,4'-MDI, 3-ring oligomers and 4-ring oligomers using liquid chromatography-mass spectrometry. PMDI preparations kept frozen were stable for a year. All other preparations failed to fulfil the requirements of stability, i.e. +/-20% of the initial concentration. Storage in a freezer prolonged the lifetime for 4,4'-MDI. The decrease in concentration for preparations kept at room temperature and refrigerated was less rapid in PMDI preparations than in 4,4'-MDI preparations. PMDI preparations are better suited for patch testing patients exposed to MDI because they are more stable and homogeneous than 4,4'-MDI preparations. They better reflect possible allergens that workers are exposed to because products used in industry contain both monomers and oligomers.

Variation in the amount of petrolatum preparation applied at patch testing

The elicitation of a positive patch test reaction in a given individual depends upon the dose of the sensitizer applied, the patch test technique and the occlusion time. The dose is determined by the concentration and volume/amount of test preparation applied. If the same amount/volume of a test preparation is applied all the time with the same test technique (same area of skin) and occlusion time, it is appropriate to use concentration as a dose parameter. Most contact sensitizers are incorporated in petrolatum (pet.). With pet. as vehicle, it is impossible to repeatedly apply an exact volume/amount. This study was performed to investigate the inter- and intra-individual variation of pet. preparation applied at patch testing by 3 technicians. Weighing demonstrated that the 3 technicians had about the same precision in their pet. application. The investigation demonstrates that there is both an inter-individual (statistically significant) and intra-individual variation in the amounts of pet. applied at patch testing for the 3 technicians. Presently, there is no recommendation on what amount of pet. preparation to apply, which merits a decision to be taken based on thorough investigations on the appropriate volumes of pet. preparation to be applied in various patch test systems.

The validity of a questionnaire-based epidemiological study of occupational dermatosis

The aim of this study was to evaluate the validity of a questionnaire and medical anamnesis to identify persons with dermatitis in an occupational setting. The design was a clinical epidemiological cross-sectional study. The study was performed between the second and fourth week of January 2001. A questionnaire was followed a week later by a medical occupational interview and a clinical dermatological examination, including a comprehensive patch test with potential workplace chemicals. The anamnesis and the clinical examination were made independently by occupational and dermatological physicians, and the skin examination was performed blinded to anamnestic data. The setting was the mother plants of a Danish-based international company producing wind turbine systems. The study population was a workplace cohort, highly exposed to epoxy resin systems and other chemicals, and totalled 724 production workers at 4 facilities. The rate of participation was 84.7%. Using enquete questions of current skin rash against the clinical presence of dermatitis, we found a sensitivity of 22% and a specificity of 89%, compared to 45% and 87%, respectively, when the anamnestic work history, taken by an occupational physician, was the screening parameter. Using 'workplace periodic prevalence' of dermatitis, we found sensitivities in the range of 63-76% by a questionnaire and 70-83% by medical anamnesis. Questionnaire screening by skin symptoms gave the highest values for redness, a sensitivity of 33% and a specificity of 76%, and decreasing validity parameters as more symptoms were added to the list of screening questions. We found that the use of a questionnaire and medical anamnesis were problematic, when the purpose was screening for contact dermatitis and allergy, in this industrial cohort manufacturing reinforced plastic products. But these instruments might be useful for epidemiological surveillance, when the questionnaire has been validated in the given occupational setting.

Contact allergy to (meth)acrylates in the dental series in southern Sweden: simultaneous positive patch test reaction patterns and possible screening allergens

Contact allergy to dental allergens is a well-studied subject, more so among dental professionals than dental patients. 1632 subjects had been patch tested to either the dental patient series or dental personnel series at the department of Occupational and Environmental Dermatology, Malmö, Sweden. Positive patch tests to (meth)acrylate allergens were seen in 2.3% (30/1322) of the dental patients and 5.8% (18/310) of the dental personnel. The most common allergen for both groups was 2-hydroxyethyl methacrylate (2-HEMA), followed by ethyleneglycol dimethacrylate (EGDMA), triethyleneglycol dimethacrylate, and methyl methacrylate. 47 (29 dental patients and 18 dental personnel) out of these 48 had positive patch tests to 2-HEMA. All 30 subjects who had a positive reaction to EGDMA had a simultaneous positive reaction to 2-HEMA. One dental patient reacted only to 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (bis-GMA). From our data, screening for (meth)acrylate contact allergy with 2-HEMA alone would have picked up 96.7% (29/30) of our (meth)acrylate-allergic dental patients and 100% (18/18) of our (meth)acrylate-allergic dental personnel. The addition of bis-GMA in dental patients would increase the pick-up rate to 100%.

SYBR Green real-time reverse transcription-polymerase chain reaction assay for the generic detection of coronaviruses

Coronaviruses are etiologic agents of respiratory and enteric diseases in humans and in animals. In this study, a one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) assay based on SYBR Green chemistry and degenerate primers was developed for the generic detection of coronaviruses. The primers, designed in the open reading frame 1b, enabled the detection of 32 animal coronaviruses including strains of canine coronavirus, feline coronavirus, transmissible gastroenteritis virus (TGEV), bovine coronavirus (BCoV), murine hepatitis virus (MHV) and infectious bronchitis virus (IBV). A specific amplification was also observed with the human coronaviruses (HCoV) HCoV-NL63, HCoV-OC43, HCoV-229E and severe acute respiratory syndrome coronavirus (SARS-CoV). The real-time RT-PCR detected down to 10 cRNA copies from TGEV, BCoV, SARS-CoV and IBV. In addition, the assay exhibited a high sensitivity and specificity on clinical samples from different animal species. The developed assay represents a potential tool for laboratory diagnostics and for detecting still uncharacterized coronaviruses.

GABA-site antagonism and pentobarbital actions do not depend on the alpha-subunit type in the recombinant rat GABA receptor

AIM

The roles of alpha-subunits on the gamma-aminobutyric acid (GABA)-site antagonism and pentobarbital actions were examined in rat recombinant GABA(A) receptors in Xenopus oocytes.

METHODS

Experiments were performed with binary and ternary GABA(A) receptors containing alpha1-, alpha4- or alpha5-subunit by the two-electrode voltage-clamp technique.

RESULTS

The potency of GABA was significantly higher in the alpha1beta2, alpha4beta2 and alpha5beta2 receptors compared with the alpha1beta2gamma2L, alpha4beta2gamma2L and alpha5beta2gamma2L receptors. However, the alpha5beta2 receptor possessed significantly lower GABA efficacy compared with the alpha5beta2gamma2L receptor. While the gamma2-subunit was essential to the potency of GABA, its influence on the apparent GABA-site antagonism was less profound. The antagonist affinity constants (K(B)) of bicuculline inhibition and slopes of Schild plots were similar between all types of ternary and binary receptors except alpha5beta2 receptor which was not tested. The pK(B)s and IC(50)s of the GABA-site antagonism were not significantly different between the alpha1beta2gamma2L, alpha4beta2gamma2L and alpha5beta2gamma2L receptors. Bicuculline blocked pentobarbital-activated currents in a reversible and non-competitive manner with the alpha1beta2gamma2L, alpha4beta2gamma2L, and alpha5beta2gamma2L receptors, indicating an allosteric inhibition of the GABA-site. No significant difference of bicuculline potencies in inhibiting GABA- and pentobarbital-activated currents was found between the alpha1beta2gamma2L, alpha4beta2gamma2L and alpha5beta2gamma2L receptors.

CONCLUSION

The GABA-site antagonism does not depend on the subtype of alpha-subunits. Similarly, pentobarbital activates ternary receptors composed of different alpha-subunits in a bicuculline-sensitive manner. The potencies of bicuculline to inhibit pentobarbital-activated currents are identical with receptors containing alpha1, alpha4 or alpha5-subunit. The alpha1beta2 and alpha4beta2 receptors possess higher GABA potencies compared with the alpha1beta2gamma2L and alpha4beta2gamma2L receptors.