Patch testing in Lao medical students

Background

Dermatological services in Laos, South East Asia are limited to the capital and patch testing is currently not available, so no data exists regarding the common cutaneous allergens in this population.

Objectives

The aim of this study was to document positive patch tests in medical students without evidence of contact dermatitis in Laos.

Patients/Materials/Methods

One hundred and fifty medical students were patch tested using TRUE Test^® panels 1 to 3 (35 allergens). Readings were taken at Days 2 and 4.

Results

Thirty-eight students (25.3%) had a positive reaction to at least one allergen, accounting for 52 reactions in total. The proportion of the students with positive patch test reading was significantly higher in the female [33/96 (34%)] than in the male [5/54 (9%)], p<0.001. The most common allergens were: nickel (10%), gold (6.6%), thiomersal (6.6%), cobalt dichloride (2%) and p-tert-Butylphenol formaldehyde resin (2%). Balsam of Peru (0.66%), black rubber mix (0.66%), Cl+Me-Isothiazolinone (0.66%), fragrance mix 1 (0.66%), quinolone mix (0.66%), methyldibromo glutaronitrile (0.66%), mercapto mix (0.66%), epoxy resin (0.66%), paraben mix (0.66%), thiuram (0.66%) and wool alcohols (0.66%) accounted for all of the other positive reactions.

Conclusion

This study represents the first documented patch test results in Lao medical students and in the adult Lao population. The results of this study will inform any future research into contact allergy in Laos and give an insight into the background level of contact sensitivity in this population.

Bile acid sequestrants for glycemic control in patients with type 2 diabetes: A systematic review with meta-analysis of randomized controlled trials

AIM

To evaluate the effects of bile acid sequestrants (BASs) versus placebo, no intervention or active comparators on glycemic control in type 2 diabetes.

METHODS

Data were retrieved and a systematic review with meta-analyses was performed. We evaluated bias control and subgroup and sensitivity analyses were performed to evaluate heterogeneity and bias.

RESULTS

We included 17 trials with a total of 2950 patients randomized to BASs (colesevelam or colestimide) versus placebo, no intervention, statins or sitagliptin. Random-effects meta-analysis showed that patients randomized to BASs had a lower hemoglobin A_1c at the end of treatment compared with the control group (mean difference-0.55%; 95% confidence interval-0.64 to -0.46). Analysis of trials with low risk of bias in all domains confirmed the findings. Data on adverse events were limited. There were no differences between trials stratified by the control group and no evidence of publication bias or small study effects.

CONCLUSIONS

Our analyses found that BAS treatment improves glycemic control. The size of the effect was clinically relevant and despite limited safety data, our findings support the inclusion of BASs in current diabetes management algorithms for type 2 diabetes.

Allergic contact dermatitis from formaldehyde textile resins

Formaldehyde-based resins have been used to create permanent-press finishes on fabrics since the 1920s. These resins have been shown to be potent sensitizers in some patients, leading to allergic contact dermatitis. This review summarizes the history of formaldehyde textile resin use, the diagnosis and management of allergic contact dermatitis from these resins, and current regulation of formaldehyde resins in textiles.

The risk of melamine-induced nephrolithiasis in young children starts at a lower intake level than recommended by the WHO

We investigated 683 children with nephrolithiasis and 6,498 children without nephrolithiasis aged <3 years. Nephrolithiasis was diagnosed by renal ultrasonography in hospitals in Beijing in September/October 2008. In addition, data was collected on current and past formula feeding and on other possible risk factors for nephrolithiasis. Daily intake of melamine per kilogram of body weight was calculated for each individual. In general, the adjusted odds ratios between melamine dose and nephrolithiasis increased with an increasing daily level of melamine intake per kilogram of body weight. The risk of nephrolithiasis also increased with the increasing duration of exposure. Preterm infants, urinary malformation, and parents with a history of urinary stones were independent risk factors. In children exposed to melamine levels <0.2 mg/kg per day, the adjusted odds ratio expressing the risk for nephrolithiasis was still 1.7 times higher than in those without melamine exposure. These findings suggest that the risk of melamine-induced nephrolithiasis in young children starts at a lower intake level than the levels recommended by the World Health Organization.

[Burning mouth caused by denture material]

A 60-year-old man with an edentulous maxilla was referred by his dentist to an allergy clinic with complaints of burning mouth and bad taste. In the majority of cases, it is hard or impossible to detect the cause of burning mouth. In this case, ultimately the complaint could be solved by eliminating exposure to possible allergenic components of denture base resins.

Rapid development of allergic contact dermatitis from dicyclohexylmethane-4,4'-diisocyanate

Isocyanates are widely used in the manufacturing of rigid and flexible foams, fibers, and coatings such as paints, varnishes, and elastomers but are rarely reported as contact sensitizers. The aliphatic diisocyanate dicyclohexylmethane-4,4'-diisocyanate (DMDI) is known to be a strong cutaneous sensitizer. We report a 27-year-old woman who developed a severe eczematous eruption on the arms, trunk, and abdomen within 2 weeks of employment at a company using the product Chem-Dec 808 isocyanate (containing 40-70% weight per weight DMDI). Patch testing was performed with the North American screening series, an isocyanate series, and 1% Chem-Dec 808 isocyanate. At day 7, a +++ reaction to Chem-Dec 808 isocyanate and a ++ reaction to the aromatic isocyanate diphenylmethane-4,4'-diisocyanate were observed. DMDI has strong sensitizing potential and requires rigorous safety monitoring in the workplace.

In vitro evaluation of artificial ageing on surface properties and early Candida albicans adhesion to prosthetic resins

OBJECTIVE

The aim of this in vitro study was to examine potential changes and influences of prosthetic resin surface properties on Candida albicans adhesion after surface treatment or artificial ageing.

MATERIALS AND METHODS

Standardized specimens of a denture base resin and a veneering composite were prepared, polished, and randomly subjected to different surface roughness treatments or artificial ageing protocols (storage in ethanol or artificial saliva for 7/90 d, thermocycling). Surface roughness (Ra) and surface free energy were determined prior and after each treatment. Specimens were incubated with phosphate buffered saline or whole saliva for 2 h at 37 degrees C, and later with Candida albicans suspension (2.5 h, 37 degrees C). Adherent viable fungi were quantified using a bioluminescence assay.

RESULTS

Artifical ageing did not affect substratum surface roughness, yet slight increases in substratum surface free energy and significant increases in Candida albicans adhesion were observed. Saliva coating marginally influenced Candida albicans adherence to reference and surface treated specimens, yet more pronounced differences in Candida albicans adhesion between the various artificially aged specimens were found.

CONCLUSION

No correlation between substratum surface roughness or surface free energy and Candida albicans adhesion could be established.

Contact allergic dermatitis from melamine formaldehyde resins in a patient with a negative patch-test reaction to formaldehyde

Melamine paper is a basic material used in the furniture industry for home and office interiors. Contact allergic dermatitis from melamine formaldehyde resins (MFRs) should be considered in patients who work on melamine paper impregnation lines. We report a case of a 28-year-old female plywood worker who developed eczema on the dorsal side of her hands and wrists after 2 years of working on the melamine paper impregnation line. She had a relevant positive patch-test reaction to MFR, with a negative reaction to formaldehyde. Contact dermatitis due to MFR is not common, and it is usually related to products that are not fully cured or to close contact with intermediate products on the assembly line. Formaldehyde release from MFR can explain most of the positive responses. To our knowledge, this is the first report of MFR contact allergic dermatitis in a worker on a melamine paper impregnation line.

Contact allergy to p-tert-butylphenol formaldehyde resin and zinc diethyldithiocarbamate in a wet suit

Rubber materials are common causes of contact dermatitis. Neoprene is a special synthetic rubber used in many products (eg, wet suits, elastic supports, gloves, shoes, and orthopedic devices). A 31-year-old man was admitted to our dermatoallergologic clinic with the development of a generalized itching erythematovesicular eruption. He reported that clinical manifestations occurred after he wore a neoprene wet suit that he was used to wearing for water sports. Although allergic contact dermatitis from a wet suit is not uncommon, it is usually due to thiourea derivatives whereas our patient presented with contact allergy to p-tert-butylphenol formaldehyde resin and zinc diethyldithiocarbamate.

Assessment of biocompatibility of chronically implanted polyimide and platinum intrafascicular electrodes

Longitudinal intrafascicular electrodes (LIFEs) are electrodes designed to be placed inside the peripheral nerve to improve stimulation selectivity and to increase the recording signal-to-noise ratio. We evaluated the functional and morphological effects of either Pt wire LIFEs or polyimide-based thin-film LIFEs implanted in the rat sciatic nerve for 3 mo. The newly designed thin-film LIFEs are more flexible, can be micromachined and allow placement of more active electrode sites than conventional Pt LIFEs. Functional results at 1 mo indicated an initial decline in the nerve conduction velocity and in the amplitude of muscle responses, which recovered during the following 2 mo towards normal values. Morphological results showed that both types of LIFEs induced a mild scar response and a focal but chronic inflammatory reaction, which were limited to a small area around the electrode placed in the nerve. Both types of LIFEs can be considered biocompatible and cause reversible, minimal nerve damage.

Allergic contact dermatitis from formaldehyde textile resins in surgical uniforms and nonwoven textile masks

Despite a trend for reduction in the concentration of free formaldehyde in textiles, formaldehyde textile resin (FTR) allergic contact dermatitis (ACD) remains an important clinical issue and is likely underdiagnosed. Patients with FTR ACD may react to formaldehyde released from the resin or to the resin itself. Screening with formaldehyde and ethyleneurea/melamine formaldehyde resin will uncover most cases. Patch testing with the suspected offending fabric most often leads to false-negative results. We present a case of a 49-year-old pediatrician who developed a severe widespread dermatitis caused by contact with FTRs from her hospital "greens" ("scrubs") and mask.

A method to automate probabilistic sensitivity analyses of misclassified binary variables

BACKGROUND

Misclassification bias is present in most studies, yet uncertainty about its magnitude or direction is rarely quantified.

METHODS

The authors present a method for probabilistic sensitivity analysis to quantify likely effects of misclassification of a dichotomous outcome, exposure or covariate. This method involves reconstructing the data that would have been observed had the misclassified variable been correctly classified, given the sensitivity and specificity of classification. The accompanying SAS macro implements the method and allows users to specify ranges of sensitivity and specificity of misclassification parameters to yield simulation intervals that incorporate both systematic and random error.

RESULTS

The authors illustrate the method and the accompanying SAS macro code by applying it to a study of the relation between occupational resin exposure and lung-cancer deaths. The authors compare the results using this method with the conventional result, which accounts for random error only, and with the original sensitivity analysis results.

CONCLUSION

By accounting for plausible degrees of misclassification, investigators can present study results in a way that incorporates uncertainty about the bias due to misclassification, and so avoid misleadingly precise-looking results.

Four years of clinical experience with an adverse reaction unit for dental biomaterials

OBJECTIVES

We describe the function of, and results from, the Norwegian National Dental Biomaterials Adverse Reaction Unit after 4 years of activity from 1993 to 1997.

METHODS

During this period of time, 296 patients were examined at the unit, which is located at the Dental School, University of Bergen. The most prevalent age group was 40-49 years, and 70% were women. Dental amalgam was the primary reason for referral to the unit for nearly 85% of the patients, followed by metals in crowns and bridges (11%). Materials in removable dentures, resin-based filling materials and cements, endodontic materials, and others, including temporary materials, were also involved. Nearly all (96%) patients reported general subjective symptoms, such as muscle and joint pain, fatigue, and memory problems. Complaints involving the orofacial region (lips, face, temporomandibular joint) and intraoral subjective symptoms were also common.

RESULTS

Of the patients who were patch tested with substances in dental materials, 23% were positive to gold, 28% to nickel, 14% to cobalt, 9% to palladium, 6% to mercury, and 8% to one or more components of resin-based materials. Mercury concentrations in blood and urine were statistically higher in the patients with amalgam fillings compared with those without.

CONCLUSIONS

Generally, we could not establish a straightforward cause-and-effect relationship between the presence of dental biomaterials and general symptoms. Twenty patients were advised to replace restorative materials because of contact lesions. Another 20 patients were recommended replacement of materials because of allergy verified with positive patch tests. The complex nature of most of the reactions requires a multidisciplinary approach to the care taking of patients who are concerned about reactions from dental materials, particularly amalgam.

Contact dermatitis to a limb prosthesis

PROSTHESIS USERS commonly develop various skin problems on the residual limb, directly under the prosthetic device when the device is in direct contact with the skin. Prolonged occlusion and humidity increase the likelihood of developing contact sensitivity to moisturizing creams, medicaments, and materials in the prosthesis itself.1 Allergic contact dermatitis to various prosthetic design materials is uncommon, and the relevance of positive patch-test results to chemicals present in prostheses may be difficult to establish. Most reports of allergic contact dermatitis to prostheses have been concerned with surgical amputees and not congenital amputees. We report a 5-year-old boy with a transverse partial hemimelia who developed allergic contact dermatitis to an adhesive used in his myoelectric prosthesis. Unlike most prostheses, myoelectric prostheses are worn directly against the skin, for surface electromyography electrode contact.

Contact dermatitis in adolescents

BACKGROUND

Adolescents between the ages of 10 and 19 are exposed to a series of substances capable of causing contact dermatitis.

OBJECTIVES

(1) To study the frequency and characteristics of allergic contact dermatitis in adolescents, (2) to characterize the group being studied, and (3) to verify the main sensitizing substances among this age group.

METHODS

From 1996 to 2001, 1,027 patients with a suspicion of contact dermatitis were analyzed, and patients between 10 and 19 years of age were selected. These patients were submitted to contact tests.

RESULTS

Among the 102 adolescents, 93 (91%) were female and 9 (9%) were male. The face was the area most affected by dermatosis. The contact tests were positive in 64 patients (56%), whereas in 45 (44%) they were negative. The main location of the contact dermatitis was the face (36%). The substances with higher frequencies of sensitization were nickel sulfate in 33 (31%) patients and tosylamide-formaldehyde resin in 13 (12%) patients.

CONCLUSION

Contact dermatitis in adolescents was more frequent in white girls and on the face. The substances with greater frequency of sensitization were nickel sulfate and tosylamide-formaldehyde resin. These two substances are related to adolescent habits and behavior.

[Allergies in orthodontics]

In contrast with work-related allergies amongst dentists and dental prosthetictists, allergies in patients followed in orthodontics concerning the materials placed in the mouth were rare. It may be a question of limited manifestations in the buccal cavity (urticaria, angio-oedema, stomatitis, chellitis), or more generalised manifestations (Quincke's oedema, eczema). The number of materials used in orthodontics is limited. The observations concerning metals are less numerous whilst those that concern the resins are exceptional. On the other hand, the risk linked to latex is very real. Allergy investigations require skin tests, sometimes to mucous tests and in some cases to provocation tests. Use of eviction measures may be not only the only diagnostic method but also a therapeutic method. Systematic search for an allergy to metal or a resin posed by the prosthetic material does not seem to be necessary. In the case of suspicion of latex, confirmed ultimately by an allergic history, this imposes start of the eviction measures.

Formaldehyde-negative allergic contact dermatitis from melamine-formaldehyde resin

Melamine-formaldehyde resin (MFR) is used as a textile finish, in tableware, in surface coatings, and in glues in the furniture and wood industry. MFR is considered to be an infrequent sensitizer. Contact allergy to MFR is often combined with formaldehyde allergy. Patients allergic to textile finish often react to MFR, although other finishes are nowadays more commonly used. Besides allergy to textile finish, allergic contact dermatitis from MFR has been described in workers in composite production and in an orthopaedic plaster technician. To our knowledge, there are no previous reports of contact allergy in the plywood industry from MFR. We describe 3 cases of occupational allergic contact dermatitis from MFR without contact allergy to formaldehyde, 1 in the plywood industry, 1 in the production of melamine-laminated chipboard and 1 in laboratory work.

Lymphomatoid contact dermatitis to para-tertyl-butyl phenol resin

Lymphomatoid contact dermatitis refers to the relatively little known phenomenon of allergic contact dermatitis producing histological features suggestive of cutaneous T-cell lymphoma. We report the first case of lymphomatoid contact dermatitis in response to para-tertyl-butyl phenol resin.

Sensitizing capacity of two monomeric aldehyde components in p-tert-butylphenol-formaldehyde resin

Contact allergy to p-tert-butylphenol-formaldehyde resin is not rare. This resin consists of a large number of substances, most of which are unknown. For diagnostic and preventive reasons, the chemical identity of the sensitizers should be known as well as their sensitizing capacities, cross-reaction patterns and presence in the environment. The aim of this study was to investigate the sensitizing capacities and cross-reaction patterns for 5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzaldehyde and 5-tert-butyl-2-hydroxy-benzaldehyde in the guinea pig maximization test. 2,6-Dimethylol p-tert-butylphenol, p-tert-butylcate chol, 2-methylol p-tert-butylphenol, p-tert-butylphenol, 4-tert-butyl-2-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-6-hydroxymethyl-phenol and 4-tert-butyl-2-(5-tert-butyl-2-hydroxy-benzyloxymethyl)-phenol were used as potential cross-reacting substances. 5-tert-Butyl-2-hydroxy-3-hydroxymethyl-benzaldehyde was shown to be a sensitizer (p = 0.041). In animals induced with this compound no cross-reactions to the putative cross-reacting substances were seen. In contrast, 5-tert-butyl-2-hydroxy-benzaldehyde failed to induce sensitization and no cross-reactions were detected.

Contact dermatitis from electrocardiograph-monitoring electrodes: role of p-tert-butylphenol-formaldehyde resin

Three cases of allergic contact dermatitis localized to the sites of electrocardiograph-monitoring electrodes are reported. All patients had positive patch tests to both the gel and the adhesive part of the Red Dot 2239 3M monitoring electrode used and to the p-tert-butylphenol-formaldehyde resin (PTBP-F-R) of the standard series. Two patients had a history of possible exposition to the resin previously but there was no explanation for the third. No information about the presence of PTBP-F-R in the electrodes could be obtained from the manufacturers. Chemical analysis of samples of the electrode, using a gas chromatography-mass spectrometry (GC-MS) and high pressure liquid chromatography (HPLC) analytical system, demonstrated the presence of several PTBP-F-R derivatives in both the gel and the adhesive part.

Influence of hyperbranched multi-methacrylates for dental neat resins on proliferation of human gingival fibroblasts

We have previously shown that hyperbranched multi-methacrylate (H-MMA)-modified dental resins have VLC activities, lower polymerization shrinkage, and improved mechanical properties, compared to the 2,2-bis[4-(2-hydroxy-3-methacryloyolxypropoxy)phenyl]propane/triethyleneglycol dimethacrylate (BisGMA/TEGDMA) neat resin. The results are due to the unique molecular structure and high molecular weight of H-MMA intermediates. The purpose of this study was to evaluate the biocompatibility of H-MMA-modified dental neat resins. The cell proliferation of three human gingival fibroblast strains on either H-MMA, BisGMA/TEGDMA, or a polystyrene disk was examined. Following 10 days of cell proliferation, there was no statistical difference in cell number between H-MMA-modified and unmodified resin disks. H-MMA-modified resins had less free monomer leaching than the unmodified resin but showed similar properties in water sorption and contact angle values. All these results suggest that the biocompatibility of H-MMA-modified dental neat resins is as good as that of commercially used BisGMA/TEGDMA resin and H-MMA has potential applications in dental composites.

Low-molecular-weight contact allergens in p-tert-butylphenol-formaldehyde resin

BACKGROUND

p-tert-Butylphenol-formaldehyde resin (PTBPFR) is a contact allergen that is included in most standard patch test series. This resin consists of a large number of substances most of which are unknown.

OBJECTIVE

The aim of this study was to investigate if allergens in PTBPFR are molecules mainly of low (MW < 250), medium, or high molecular weight (MW > 1,000); to isolate and identify some of the low molecular weight components of the resin; and for new substances to determine if these were allergens.

METHODS

Gel permeation chromatography, patch testing, high-pressure liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectrometry were used.

RESULTS

Patch test reactions indicated allergens in low-, medium-, and high-molecular-weights fractions. The strongest patch test reactivity was seen to a medium molecular weight fraction constituting only 6% wt/wt of the resin for 4 of the patients. Two patients reacted positively to low molecular weight fractions, and one of these patients reacted only to these fractions. The following substances were isolated: 4-tert-butyl-[1,2]benzoquinone, 4-tert-butyl-2,6-bis-hydroxymethyl-phenol, 4-tert-butylbenzene-1,2-diol, 4-tert-butyl-2-hydroxymethyl-phenol, 5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzaldehyde, 4-tert-butyl-2-hydroxymethyl-6-methoxymethyl-phenol, and p-tert-butylphenol. Patients reacted positively to 5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzaldehyde and 4-tert-butyl-2-hydroxymethyl-6-methoxymethyl-phenol but not to 4-tert-butyl-[1,2]benzoquinone.

CONCLUSION

Two new allergens in PTBPFR were found: 5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzaldehyde and 4-tert-butyl-2-hydroxymethyl-6-methoxymethyl-phenol.

Contact allergy to the monomers in p-tert-butylphenol-formaldehyde resin

In many adhesive formulations p-tert-butylphenol-formaldehyde resin (PTBP-F-R) is used as a binder. Contact allergy to this resin is not rare. In patients hypersensitive to PTBP-F-R, and butylphenol derivatives therein, it is for diagnostic and preventive reasons necessary to know the nature of the primary sensitizing substances, as well as the cross-reaction patterns for these. The aim of this study was to investigate contact allergy to monomers in PTBP-F-R and potential cross-reacting substances. 12 patients hypersensitive to PTBP-F-R were patch tested with 2 monomers, the raw materials formaldehyde and p-tert-butylphenol, and 3 closely related substances. High pressure liquid chromatography (HPLC) was used to investigate the purity of the test substances. It was shown that the monomers 2-methylol p-tert-butylphenol and 2,6-dimethylol p-tert-butylphenol could elicit allergic reactions in humans hypersensitive to PTBP-F-R. No simultaneous reactions or cross-reactions were shown to formaldehyde, p-tert-butylphenol, p-tert-butylcatechol, 2(3)-tert-butyl-4-hydroxyanisole (BHA) or 3,5-di-tert-butyl-4-hydroxytoluene (BHT). It was also shown that low amounts of contaminants in the test substances, if not taken into account, could influence the conclusions drawn from the test results obtained.

Sensitizing capacity of some trimers in p-tert-butylphenol-formaldehyde resin

Contact allergy to p-tert-butylphenol formaldehyde resin (PTBP-F-R) is not rare. This resin consists of a large number of substances, most of which are still unknown. For diagnostic and preventive reasons the chemical identity of the sensitizers should be known, as well as their sensitizing capacities, cross-reaction patterns and presence in the environment. The aims of this study were to investigate the sensitizing capacities and potential cross-reacting patterns for 4-tert-butyl- 2,6-bis-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-phenol (XIII), 4-tert-butyl-2- (5 - tert - butyl - 2 - hydroxy-benzyloxymethyl) - 6 - (5 - tert - butyl - 2 - hydroxy - 3 - hydroxymethyl-benzyloxy methyl)-phenol (XIVa) and 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix(3)arene (XVIII) by the guinea pig maximization test. 4-tert-Butyl-2,6-bis-hydroxymethyl-phenol, 4-tert-butylbenzene-1,2-diol, 4-tert-butyl-2-hydroxymethyl-phenol, 4-tert-butyl-phenol, 4-tert-butyl-2-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-6-hydroxymethyl-phenol, 4-tert-butyl-2-[5-tert-butyl-3-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl) - 2 -hydroxy-benzyloxymethyl] - 6 - (5 - tert-butyl- 2 -hydroxy- 3 -hydroxymethyl-benzyloxymethyl)- phenol and were used as potential cross-reacting substances. In this study it is strongly indicated that the linear trimer XIII has a sensitizing capacity in the guinea pig which was significant when compared to the controls (p = 0.024). No cross-reactions were detected in animals induced with the linear trimer XIII. The linear trimer XIVa and the cyclic trimer XVIII failed to induce sensitization.

Occupational dermatoses among fibreglass-reinforced plastics factory workers

Fibreglass-reinforced plastics (FRP) factory workers are at high risk of developing occupational dermatoses because of their exposure to many chemicals used in the manufacture of plastics as well as to glass fibre or dust. Patch tests were carried out on 29 workers involved in FRP manufacturing processes where unsaturated polyester (UP) resin was used, to investigate the causes of their skin problems. Of the 22 workers who reported experiencing skin problems, 16 showed positive results to at least 1 chemical, including 6 cases of multiple sensitivity. 2 showed positive reactions to UP base resin, 6 to cobalt chloride, 5 to benzoyl peroxide (BPO), 4 to methyl ethyl ketone peroxide (MEKPO), 2 to para-tertiary butyl catechol (PTBC), 1 to styrene and 1 to formaldehyde. After taking into account their exposures and reported causes by questionnaires and their patch test results, 7 cases were diagnosed as allergic contact dermatitis (ACD) due to chemicals, 3 as irritant contact dermatitis (ICD) due to chemicals, and 3 as dermatitis due to mechanical irritation (MI) from glass fibre or dust, as well as 9 as ACD and/or MI. 18 of the total of 29 subjects (62.1%), including 2 workers without a history of skin problems, were sensitized to at least 1 chemical. Cobalt, peroxides, PTBC and UP base resin were the common causes of ACD.

Patch testing for permanent-press allergic contact dermatitis

During the decade of the 90s, 24 cases of permanent-press textile-resin contact dermatitis were identified. The most common allergen associated with these cases was dimethylol propylene urea (DMPU). Although previous reports had suggested ethylene urea melamine formaldehyde resin (EUMF) or dimethylol dihydroxy ethylene urea (DMDHEU) as the most appropriate test materials for this type of contact dermatitis, we could not confirm EUMF as appropriate but, with some limitations, can support DMDHEU due to its widespread and continued use. DMPU has been withdrawn from the marketplace and replaced with what may be less reactive materials. In this study, we also observed discordance between EUMF patch tests in the range of 30%, which is consistent with previous reports about the biovariability of patch test results.

Asthmagenicity of coal mine roof-bolting resins: an assessment using inhalation provocation tests

Inhalation provocation tests were used to assess whether the volatile products of an activated resin had caused occupational asthma in a non-random sample of six asthmatic coal miners. The resin system uses the polymerization of polyester and styrene under the influence of the cross-linking agent dibenzoyl peroxide to secure roof, wall and floor bolts in mine tunnels. The tests were conducted sequentially in a double-blind fashion over a 'dose' range which extended just beyond the maximum likely to have been experienced occupationally during a single day's work. The tests were monitored by symptoms, changes in the forced expiratory volume in 1 s (FEV1) and changes in airway responsiveness. All subjects completed the series of tests without any significant decrements in FEV1 or significant increases in airway responsiveness. We conclude that the use of this resin system is not likely to have been the cause of the asthma in the test subjects, nor in the larger group of miners of which they were a sample, but neither possibility is fully excluded and the participants may not have been adequately representative of other asthmatic coal miners.

Sensitizing capacity of 5,5'-di-tert-butyl-2,2'-dihydorxy-(hydroxymethyl)-dibenzyl ethers in the guinea pig

In patients hypersensitive to p-tert-butylphenol-formaldehyde resin (PTBP-F-R), it is for diagnostic, therapeutic and preventive reasons necessary to know the identity of the primary sensitizing substances, their sensitizing capacities as well as their cross-reaction patterns. We have recently shown that the 2 dimers in PTBP-F-R, 5,5'-di-tert-butyl-2,2'-dihydroxy-3-hydroxymethyl-dibenzyl ether (X) and 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-dihydroxymethyl-dibenzyl ether (IX) are contact sensitizers in man. The aim of this study was to investigate the sensitizing capacities of these dimers in PTBP-F-R and potential cross-reacting substances in the guinea pig with the guinea pig maximization test. IX, X, 2,6-dimethylol-p-tert-butylphenol (2,6-MPTBP), 2-methylol-p-tert-butylphenol (2-MPTBP), p-tert-butylcatechol (PTBC), 5,5'-di-tert-butyl-2,2'-dihydroxy-dibenzyl ether (XI) were used as possible cross reacting substances. IX and X were shown to be sensitizers. When compared to the sensitizers in phenol-formaldehyde resin, IX is a strong sensitizer (p= 0.00052) and X a moderate sensitizer (p=0.0053). Animals sensitized to IX showed cross-reactions to X (p=0.010), 2,6-MPTBP (p=0.0011) and PTBC (p=0.0498). Animals sensitized to X showed no cross-reactions to the substances that were tested. The results indicate that IX is a main allergen in PTBP-F-R, with possibly also X.

The osmotic swelling characteristics of cardiac valve prostheses

Several types of mechanical cardiac prostheses have been constructed with Delrin occluders, a material that is subject to osmotic swelling. The leaftets are designed to expand to specific tolerances when immersed in blood. The synthetic blood analogs commonly used in vitro contain hydrophilic compounds that can alter the osmotic expansion of the Delrin occluders. A static leak test chamber was employed to illustrate the effects of various test fluids on the sustained regurgitation phase of Delrin valves.

Contact allergy to 5,5'-di-tert-butyl-2,2'-dihydroxy-(hydroxymethyl)-dibenzyl ethers, sensitizers, in p-tert-butylphenol-formaldehyde resin

Allergy to p-tert-butylphenol-formaldehyde resin (PTBP-F-R) is not rare. This resin consists of a large number of substances, most of which are still unknown. More knowledge about the sensitizers in the resin is a good basis for development of diagnosis, treatment and prevention. The aim of this investigation was to study allergens in PTBP-F-R by isolation of some medium molecular weight substances from the resin and patch testing these in individuals hypersensitive to PTBP-F-R. 2 isolated substances were shown to be allergens in PTBP-F-R, 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-dihydroxymethyl-dibenzyl ether and 5,5'-di-tert-butyl-2,2'-dihydroxy-3-hydroxymethyl-dibenzyl ether. 13 patients hypersensitive to PTBP-F-R were patch tested with serial dilutions of 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-dihydroxymethyl-dibenzyl ether and 12 of them reacted positively. 12 patients hypersensitive to PTBP-F-R were patch tested with serial dilutions of 5,5'-di-tert-butyl-2,2'-dihydroxy-3-hydroxymethyl-dibenzyl ether and 11 of them reacted positively. Positive patch test reactions were seen down to 0.0000025 mmole x 1(-1) (approximately 0.01 ppm) for both 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-dihydroxymethyl-dibenzyl ether and 5,5'-di-tert-butyl-2,2'-dihydroxy-3-hydroxymethyl-dibenzyl ether in the most sensitive patient. HPLC analysis of 2 PTBP-F-Rs showed the presence of 1.0-1.7% w/w 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-dihydroxymethyl-dibenzyl ether and 0.75-0.90% w/w 5,5'-di-tert-butyl-2,2'-dihydroxy-3-hydroxymethyl-dibenzyl ether in the resins.

Acute abdomen with colonic necrosis induced by Kayexalate-sorbitol

Colonic necrosis is an unusual complication after treatment of hyperkalemia with sodium polystyrene sulfonate (SPS, Kayexalate) in sorbitol. To increase awareness of this complication, we report a case of necrosis of the transverse colon in a patient given oral and rectal SPS-sorbitol for hyperkalemia. Colonic necrosis was manifested as an acute abdomen within 24 hours of initial administration. Prompt surgical resection of the necrotic transverse colon permitted rapid recovery of bowel function. Although SPS crystals are seen microscopically in the necrotic bowel, experimental evidence implicates the sorbitol component of the SPS-sorbitol in the pathogenesis of colonic necrosis. A high index of suspicion for the unusual complication of colonic necrosis after oral or rectal administration of SPS-sorbitol may allow prompt recognition and surgical cure.

Allergic contact dermatitis in dentistry

Allergic contact dermatitis (ACD) in dentistry may affect dentists and orthodontists, technicians, nurses and patients. Changes to dental practice in recent years have altered the reported frequencies of allergens causing ACD in both dental personnel and patients. Allergic contact dermatitis to medicaments, metals and glutaraldehyde were previously common allergens in dentistry; however, widespread adoption of rubber gloves by staff has resulted in a significant increase in ACD to glove allergens in both dental staff and their patients, while affording protection against the traditional allergens. Both public concerns about potential toxicity of metals in oral restorations and a greater demand for cosmetic dentistry, have resulted in greater use of acrylics and resins by dental personnel, exposing them to highly allergenic materials. Dermatologists need to be aware of the newer allergenic materials used in dentistry in order to correctly manage skin diseases in this high-risk group.

Occupational dermatoses in composite production

In a plant that produces fiber-resin composite by impregnation of cellulose fibers with phenol-formaldehyde and melamine-formaldehyde resins, a new technique was introduced that resulted in problems in the handling of uncured products. Many workers suffered dermatitis on areas of exposed skin. A primary investigation found that some workers had an occupationally related skin disease with contact allergy to work materials. We undertook a survey of occupational dermatoses, based on a questionnaire, clinical examination, and patch test with a standard series and a series of products and chemicals representing the work environment. Eighty-eight workers participated in the clinical investigation. In six workers, contact allergy to phenol-formaldehyde resin was seen, and in five workers, contact allergy to melamine-formaldehyde resin was noted. Two workers were allergic to both resins. Occupational dermatitis was diagnosed in nine of 88 (10.2%) workers. In this article, we discuss possible preventive measures for avoiding occupational dermatitis.

Cytocompatibility of periodontal dressing materials in fibroblast and primary human osteoblast-like cultures

Purpose of this investigation was to determine the cytocompatibility of various periodontal dressing materials by means of human primary gingival fibroblasts (HGF), human osteoblast-like cells (HObl) derived from the alveolar bone, and permanent 3T3 mouse fibroblasts (3T3). Cell culture medium extracts (time periods of extraction: day 1 and between day 2 and day 8 after setting) as well as solid specimens of the following materials were investigated: Coe-pak, Voco pac, Peripac, and Barricaid. Responses of cultures exposed for 24 h and 48 h to these materials were monitored by the fluorescent dyes H33342 and sulforhodamin 101 as well as by light microscopy. It was found that most extracts of Voco pac, Peripac, and Barricaid did not inhibit growth of HGF. Coe-Pak, however, clearly reduced the proliferation of HGF compared to untreated controls. Peripac decreased growth of HObl whereas Coe-Pak, Voco pac, and Barricaid caused no cytotoxic alterations in any of the test assays. Contrary to HGF and HObl, 3T3 cells were much more irritated by the test materials. But the light-curing resinous material Barricaid reduced proliferation of 3T3-fibroblasts only slightly. Our data indicate that Barricaid is exceedingly cytocompatible, whereas all other materials revealed moderate or severe cytotoxic effects according to the cell type.