Biologic pollution in infant bedding in New Zealand: high allergen exposure during a vulnerable period

BACKGROUND: High exposure to house dust mite and cat allergens in early life predisposes to allergic sensitization and to the development and persistence of asthma. Prevalence and severity of asthma are high in New Zealand. OBJECTIVE: The objective of this study was to determine the concentrations of Der p 1 and Fel d 1 in infant bedding in Wellington, New Zealand. METHODS: Infants were visited at home at a mean age of 11 weeks and again at 15 months. The concentration (microgram/g fine dust) and content (microgram/m2) of Der p 1 (154 infants) and Fel d 1 (75 infants) were measured in dust samples taken from each infant's bed. RESULTS: At 11 weeks, geometric mean (95% confidence intervals) Der p 1 levels were 18.3 micrograms/g (13.8 to 24.1) and 3.51 micrograms/m2 (2.4 to 5.2). By 15 months, Der p 1 had risen significantly to 44.0 micrograms/g (35.0 to 55. 3) and 49.0 micrograms/m2 (36.0 to 66.8). Bedding that included a sheepskin was used by a third of the infants and contained higher concentrations (microgram/g) and content (microgram/m2) of Der p 1 than beds without sheepskins. Cat ownership was the major determinant of Fel d 1 levels, with 48% of infants living with cats. At the first visit, the mean concentration of Fel d 1 in bedding was 44.6 micrograms/g (23.5 to 84.9) for houses with cats and 3.0 micrograms/g (2.1 to 4.3) for those without cats, remaining essentially unchanged at the second visit. When expressed as micrograms per square meter, there was a significant increase between visits, from 8.1 (3.9 to 16. 6) to 39.6 (19.9 to 78.5) in the cat-inclusive households. CONCLUSIONS: Extremely high levels of house dust mite allergen have been found in these infants' environments, which, together with the high levels of cat allergen in almost half who kept cats, are likely to be a major determinant of asthma prevalence and severity in New Zealand.     

Expression of Msx-2 during development, regeneration, and wound healing in axolotl limbs

BACKGROUND: High exposure to house dust mite allergen during the first year of life has been found to increase the risk of subsequent asthma and mite sensitization. Environmental factors, home construction and cleaning methods used are associated with levels of dust mites in the home. OBJECTIVE: To investigate determinants of levels of Der p 1 and Der f 1 mite allergens in homes of infants in southern Tasmania. METHODS: Dust samples were collected from 72 homes of infants participating in the Tasmanian Infant Health Survey (TIHS). The Der p 1 and Der f 1 allergen concentrations in these samples were measured. The TIHS interviewers obtained information from the mothers of the infants via a questionnaire, observed specified aspects of the home environment, and took readings of bedroom temperature and humidity. The effect of each item on allergen concentration in dust from bedroom floors was examined in a variety of ways. Those items which in this study appeared to be significantly related to allergen concentrations plus items which in other studies have been found to be related to allergen concentrations were then investigated further in multivariate models. RESULTS: Der p 1 allergen concentration (microg/g) and density (microg/m2) in dust from bedroom floors were found to be related to several home environment factors. In the univariate analyses, indoor humidity, 24 h maximum temperature, number of residents and a combination of floor covering and cleaning methods appeared to have a significant effect on allergen levels. These factors remained important in the multivariate model except that indicators for mould in the bathroom and drying washing on an outside line replaced indoor humidity. CONCLUSION: Features related to home dampness, the number of residents and floor covering and cleaning were major determinants of Der p 1 levels in the bedrooms studied.     

Indoor environmental factors associated with house-dust-mite allergen (Der p 1) levels in south-eastern Australian houses

BACKGROUND: Eighty households in the Latrobe Valley, Victoria, Australia, were sampled for house-dust-mite allergen (Der p 1). Allergen levels vary greatly between houses within climate regions. The reasons for this are not well understood. METHODS: House-dust-mite allergen samples were collected on six occasions between March 1994 and February 1995. All participating households contained at least one child between 7 and 14 years with a total of 148 subjects, 53 of whom were asthmatic. A detailed house survey was performed during every sampling visit, and a dwelling questionnaire was completed. Relative humidity was measured at the time of sample collection. RESULTS: The median bed allergen level was 30 microg/g during the first sampling period. Significantly higher allergen levels were associated with wool bedding and inner-spring mattresses (P < 0.001). As estimated from a multiple linear regression model, up to 70% reduction in bed allergen levels may be achieved by avoiding wool bedding and inner-spring mattresses. Other risk factors for high allergen levels included high indoor relative humidity, presence of substantial visible mould growth, brick cladding, and concrete slab foundation of the house. CONCLUSIONS: Avoiding wool bedding and replacing inner-spring mattresses with foam could substantially reduce bed allergen levels.     

Allergen-avoidance measures in homes of house-dust-mite-allergic asthmatic patients: effects of acaricides and mattress encasings

This double-blind, placebo-controlled study investigated whether the application of an acaricide (Acarosan) on mattresses and on textile floor coverings in living rooms and bedrooms can contribute to improvement in lung function and airway hyperresponsiveness in 40 adult asthmatic patients sensitized to house-dust mite. In a second group of 19 patients who refused chemical intervention, the clinical effects of application of allergen-impermeable mattress encasings were studied. In all three treatment groups, Der p 1 levels in mattress dust were statistically significantly decreased after 12 months. However, this decrease was much greater in the group who received mattress encasings (final mean level 430 ng/g) than in groups with acaricide- or placebo-treated mattresses (final mean levels 1730 and 2100 ng/g, respectively). Treatment of textile floors with either Acarosan or placebo chemical caused a statistically significant decrease in the level of the house-dust-mite allergen Der p1 in floor dust. In the group with mattress encasings, no significant changes of floor dust Der p 1 were found. Airway hyperresponsiveness (as measured by the PC20 histamine) improved significantly in the mattress cover group after 6 months. The Acarosan group also showed a small but statistically significant improvement after 12 months.     

House-dust-mite allergen (Der p 1) levels in university colleges

BACKGROUND: In coastal Australia, mean house-dust-mite allergen concentration is 20-40 times higher in homes than in public buildings. Allergen concentrations in university colleges, which share some characteristics of both homes and public buildings, are not known. The study aimed to compare bed mite-allergen concentration in colleges with local homes. METHODS: Mattress dust was collected from three colleges (n = 60 in each) and local homes (n = 68) during summer. Der p 1 was measured by ELISA. Information was collected on the floor plan of the colleges, cleaning practices, age of building, and orientation of room. RESULTS: Most college mattresses (94%) had Der p 1 concentrations less than the mean of homes in the same climate. The geometric means of Der p 1 in the mattresses of the colleges were as follows: A, 8.9 micrograms Der p 1/g fine dust (95% CI 6.9, 11.5); B, 1.9 (1.5, 2.3); and C, 1.5 (1.2, 2.0), compared to homes, 22.5 (17.6, 28.7). The percentages of college mattresses with less than 2 micrograms/g were 7%, 48%, and 58%, respectively, compared to 4% for homes. Higher Der p 1 concentrations were weakly associated with age of building in college A, and orientation in college B. Der p 1 concentrations were independent of floor level and age of mattress. CONCLUSIONS: These findings indicate that low allergen concentrations are achievable without extreme hygiene and cleaning measures in a climate which supports mite proliferation in homes.     

Prevalence and distribution of indoor allergens in Singapore

BACKGROUND AND AIMS: Immediate hypersensitivity to indoor allergens is known to be associated with allergic asthma. This study evaluated the prevalence and distribution of six indoor allergens in 956 dust samples obtained from homes, childcare centres, schools, and a hospital in tropical Singapore. Seasonality of mite allergens was also assessed. METHODS: The major allergens of the Dermatophagoides spp. dust mites, Der p 1 and Der f 1; major cat and dog allergens, Can f 1 (dog) and Fel d 1 (cat); and cockroach, Bla g 1, were measured by specific enzyme immunoassays. Allergen levels of the storage mite, Blomia tropicalis (Blo t), were measured by a fluorescent allergosorbent test (FAST) inhibition assay. RESULTS: Our results showed that homes had significantly higher concentrations and prevalence of allergens compared with the other locations, except for Bla g 1, where higher mean levels were found in schools. Within the homes, the highest concentrations of mite allergens were found in mattresses (geometric mean: 1.2 microg/g dust Der p 1; 2717 Allergen Units per gram dust [AU/g] Blo t), and carpets (1.5 microg/g Der p 1; 1620 AU/g Blo t), whilst Bla g 1 was mainly concentrated in the storerooms (geometric mean = 3.5 units/g) and kitchens (geometric mean = 5.1 units/g). The major cat and dog allergens were well distributed and not confined to homes with pets. Their highest levels were found in dust of soft furnishings, carpets and mattresses. There was an absence of significant seasonal variation in Der p 1, Der f 1 and Blo t levels in the homes over a 1 year period. CONCLUSION: The results indicate that compared with public places, the home consitutes a major reservior of indoor allergens. Allergens of the storage mite, B. tropicalis, should be considered as a major allergenic component of dust in Singapore.     

House dust mite allergens and mite allergy in Copenhagen dwellings. A cross-sectional study

The aim of the study was to investigate the influence of various environmental factors on occurrence of house dust mite allergens and the influence of allergen exposure on mite allergy. Ninety-two persons from a population study filled in a questionnaire, were skin prick and lung function tested and dust samples were collected from their mattresses for analyses. Two out of five patients with asthma had a positive skin reaction to house dust mite allergen in contrast to five out of 87 non-asthmatics. Fifty-nine per cent of the dust samples contained (group 1) mite allergen > 2 micrograms/g dust. Such mattresses were older (median 7 years, range 1-22) than mattresses with less allergen (median 4 years, range 1-20). In the six bedrooms reported to be humid or mouldy, mattresses contained high concentration of mite allergens. No other parameter investigated could predict the allergen contents. In almost all cases dust analyses are crucial to be able to advise patients with house dust mite allergy.     

Facial rehabilitation by the application of osseointegrated craniofacial implants

The prevalence of allergic disease is low in Eastern Europe for reasons that are poorly understood. Our study aimed to investigate the levels of exposure to indoor allergens and living conditions among Estonian infants in relation to sensitization. Dust samples were collected during four winter months in 1993/94 from the homes of 197 infants participating in a prospective study of sensitization. Information about living conditions was collected through a home visit and interviewing the mothers when the children were 6 weeks old. Three dust samples were collected from each home; i.e., from the infant's mattress, bedroom floor, and living-room carpet. The levels of allergens were determined by ELISA with monoclonal antibodies. The highest allergen level in a home was regarded as the peak value. The peak geometric mean values (+/-SD) of Der p 1 and Der f 1 were 0.3 (0.07-1.4) microg/g dust, of Can f 1, 0.86 (0.23-3.12) microg/g dust, and of Fel d 1, 0.1 (0.01-0.9) microg/g dust. In 12 homes (9%), the peak value of house-dust mite (HDM) allergens exceeded 2 microg/g dust, with Der p 1 as the dominating allergen. Multivariate analyses indicated that high levels of HDM allergens were more common in apartments that were on the ground floor or first floor, that were heated with stoves, and/or that had a dampness problem. The mean allergen levels at home were similar in children sensitized to HDM (n=17, 0.29 vs 0.3 microg/ g dust), dog (n=5, 0.55 vs 1.06 microg/g dust, and cat (n=18, 0.21 vs 0.09 microg/g dust) and in children who were not sensitized to these allergens. Most of the sensitized children were exposed to relatively low allergen levels at home; i.e., below 1 microg/g dust. This level was exceeded in the homes of 4/17 mite-, 5/18 cat-, and 0/5 dog-sensitized children. The similar levels of the major indoor allergens in Estonia and in Scandinavia indicate that the large differences in atopy prevalence among children and young adults in the two regions are not due to differences in allergen exposure. No allergen threshold level for sensitization was identified.     

Infant respiratory symptoms in relation to mite allergen exposure

The relationship between the Dermatophagoides pteronyssinus (Der p) I content of house dust and the respiratory symptoms reported for young infants was studied. One hundred and four infants, aged 3-15 months, were selected during July-September 1993 through the Dutch postnatal health care service, using a short screening questionnaire to identify mothers with respiratory allergy to house dust and/or pets. Forty-eight were selected from this group of mothers ("high risk" infants) and 56 infants were selected when neither of the parents reported allergy or chronic respiratory symptoms ("low risk" infants). All homes were visited in October 1993. Dust samples were collected from the infant's mattress and from other places in the home, and the Der p I content was measured in dust extracts. The results indicate that on more than half of the mattresses, the Der p I level was over 2,000 ng.g-1, the level suggested to be associated with an increased risk of sensitization. Information on respiratory symptoms ("wheeze" and "prolonged cough") experienced since birth was obtained by questionnaire from one of the parents on the dust sampling day. The occurrence of respiratory symptoms in the infants appeared to be positively related to the Der p I concentration of the dust. Although no objective measurements of respiratory symptoms were available, the results of this study suggest that exposure to mite allergen in early life may lead to respiratory symptoms that are suggestive of airway obstruction in the first year of life.     

Allergen content in dust from homes and schools in northern Norway in relation to sensitization and allergy symptoms in schoolchildren

BACKGROUND: Previous studies have shown a high prevalence of atopic diseases among school children in the community of S?r-Varanger. Moreover, animal dander followed by pollen and house dust mite, were the most common allergens in skin prick tests. OBJECTIVE: To assess the allergen content in homes (living-rooms and mattresses) and classrooms of children living in an arctic area at 70 degrees. The presence of allergens in homes and schools and their relationship to atopy was of particular interest. METHODS: Dust samples from 38 homes and seven schools in northern Norway were collected by vacuum cleaning. The presence of allergens of dog, birch, timothy, Cladosporium herbarum, codfish and hen egg-white was investigated by radio-allergosorbent test (RAST) inhibition and the presence of major allergens of cat Felis domesticus (Fel d I) and house dust mites (HDM) Dermatophagoides pteronyssinus (Der p I) and Dermatophagoides farinae (Der f I) by enzyme-linked immunosorbent assay (ELISA). RESULTS: Mattresses contained significantly more dust per unit area than living-rooms and classrooms. No statistically significant differences in allergen content for dog, birch, timothy. Cladosporium, codfish and hen egg-white were seen between HDM-sensitized and non-atopic children. Most dust samples contained dog allergens with the highest allergenic activity found in living-rooms of those keeping dogs. An increased level of Fel d I was detected in only one of 38 samples from living-rooms (this family kept a cat) and in 25 of 38 samples from mattresses with ranges from 24 to 84 ng/m2. The highest concentrations were found in mattresses of children keeping cats. Increased levels (> or = 25 ng/m2) of Der p I were found only in homes and virtually only in mattresses of HDM-sensitized children. An increased level of Der f I was found in only one case, i.e. in the mattress of an HDM-sensitized child where additionally Der p I and HDMs were demonstrated microscopically. When relating Der p I to HDM-sensitization an odds ratio of more than 16 (95% CI: 1.6-394.3) was found. All extracts from living-rooms included codfish allergens. Low RAST inhibition values were detected for hen egg-white. Cladosporium, birch and timothy pollen in most samples. Furthermore, the study demonstrated that dust from schools was relatively free of allergens. CONCLUSION: Previous findings indicating that the main allergen exposure problem in this geographical area is that of pet allergens were confirmed.     

Prevalence and determinants of house dust mite allergen in East German homes

BACKGROUND: In 1990/91, allergic sensitization to house dust mites (HDM) and other allergens was more prevalent in children from West Germany than from East Germany. OBJECTIVE: To test the hypothesis that low indoor exposure to HDM allergen in East Germany has contributed to this difference. METHODS: HDM allergen concentrations were determined in 634 East German dwellings shortly after the German reunification. RESULTS: HDM group I allergen (Der p 1 + Der f 1) levels in mattresses (median 2.16, geometric mean 2.07, maximum 278.9 microg/g dust) and carpets (median 0.41, geometric mean 0.48, maximum 96.3 microg/g dust) were within the range of levels determined in West Germany in other studies. One particular East German type of dwelling (light concrete buildings) was associated with lower mite allergen exposure, but only a minority of the population lived there. Coal heating, installed in the majority of dwellings before 1989, was associated with higher allergen exposure. Higher relative humidity (RH) was a main risk factor for higher Der p 1 exposure (odds ratio [OR] for exposure to > 0.05 microg/g dust on carpets: 1.4 [95% confidence interval (CI) 1.2-1.8] for + 10% RH) but not for higher Der f 1 exposure. Higher temperature was associated with a lower risk for elevated Der p 1 levels (> 0.05 microg/g dust on carpets): OR 0.6 (95% CI 0.5-0.8) for + 2 degrees C. CONCLUSION: Mite allergen exposure is not lower in East Germany than in West Germany. The data does not support the hypothesis, that low HDM allergen exposure in East Germany is a cause for the lower prevalence of HDM sensitization in East German children.     

Intrathecal administration of p-hydroxymercuribenzoate or phosphoramidon/bestatin-combined induces antinociceptive effects through different opioid mechanisms

BACKGROUND: House dust mite is an important cause of bronchial asthma. Seasonal variation of environmental house dust mite allergen levels and the specific IgE antibody to house dust mite have been reported. OBJECTIVE: We studied the changes in IgG subclass antibodies to house dust mite associated with seasonal variation of house dust mite allergen levels in houses of mite-sensitive asthmatic patients. METHODS: In 14 mite-sensitive asthmatic patients, house dust mite allergen (Der f 1) contents in bedding were measured monthly, and IgG subclass antibodies to house dust mite, Dermatophagoides farinae (D. farinae), were determined by enzyme-linked immunosorbent assay (ELISA) every 3 months from July to December. RESULTS: The concentration of Der f 1 in dust from bedding reached maximum levels in August and September, and significantly decreased in November and December compared with August and September (P < .05). Levels of D. farinae-specific IgG4 antibodies significantly decreased in December compared with September (P < .05) with no statistically significant change between September and June (P > .05). Levels of D. farinae-specific IgG2 antibodies decreased significantly in December compared with June (P < .05). The levels of IgG1 and IgG3 antibodies to D. farinae showed no significant differences during the study period. CONCLUSION: These findings suggest that seasonal changes in natural exposure to house dust mite allergen might lead to concurrent changes in specific IgG4 antibodies to house dust mite in mite-sensitive asthmatic patients and each IgG subclass antibodies to house dust mite might have a different kinetics.     

Effect of a bed covering system in children with asthma and house dust mite hypersensitivity

Allergen avoidance is regarded as an important approach to management of atopic asthma. The effect of Intervent bed covering systems on house dust mite (HDM) allergen exposure, asthma symptoms and markers of inflammation was investigated in 31 HDM sensitive asthmatic children. Dust concentrations of Dermatophagoides pteronyssinus allergen 1 (Der p 1) were monitored before and after covering the mattress, duvet and pillow with active and placebo covers for 3 months, in a single-blind, cross-over trial. Twice daily peak expiratory flow rate (PEFR), daily symptom scores and treatment schedule were recorded. Bronchial hyperresponsiveness was monitored by histamine challenge (provocative concentration of histamine causing a 20% fall in forced expiratory volume in one second (PC20)), and inflammation by measuring eosinophil cationic protein (ECP), eosinophil protein X (EPX), eosinophil peroxidase (EPO), and soluble interleukin-2 receptor (sIL-2R) in serum. There was a significant reduction in Der p 1 when the mattress, duvet and pillow were covered with the active bedding. There was no significant improvement in symptoms of asthma, PEFR, bronchodilator usage of PC20. Also, ECP, EPX, sIL-2R concentrations did not change for either treatment. EPO concentrations were significantly lower in the active compared to the placebo period. The active bed covers reduced retrievable Dermatophagoides pteronyssinus allergen 1 (Der p 1) from the bedding, with short term clinical benefit.     

Comparison of lithium dosage methods for preschool- and early school-age children

BACKGROUND: Allergens produced by mites are one of the principal causes of allergic disease. House dust mites can be found in significant numbers living in textile garments, and therefore development of optimal washing conditions for delicate textiles represents an important aim for domestic mite control. OBJECTIVES: Investigation of methods to eliminate house dust mites from clothing under low temperature washing conditions. METHODS: Domestic house dust mites Dermatophagoides farinae were cultured on garments under favourable conditions. The breeding success was monitored in terms of population and distribution using the free-mite Mobility Test. The mite containing garments were washed at low temperature with different commercial detergents in the presence or absence of a mite control additive containing 0.03% benzyl benzoate, and the numbers of mites surviving the washing process were assessed using the Heat Escape Method. RESULTS: The successful culture of mites in textile garments led to mite numbers of a total of at least 9000 to 10000 mites in 10 garments (Mobility Test). After washing in a domestic washing machine with detergents alone approximately 6000 remaining mites were detected in 10 garment halfs (Heat Escape Method). In contrast, mite control by the application of the same detergents together with an additive achieved a reduction to almost 50 mites. This is an additional reduction in mite numbers of 99.2%. CONCLUSIONS: It is possible to achieve mite control in delicate garments by washing at low temperature in the presence of a mite control additive providing a final concentration of 0.03% benzyl benzoate.     

Effects of Microstop-treated anti-mite bedding on children with mite-sensitive asthma

Seventy-one children with mite-sensitive asthma were randomly divided into three groups. Group 1 was comprised of 28 patients who were provided with new Microstop-treated bedding including matresses, quilts, pillows, bed linens and quilt covers. The Microstop mattresses and pillows were made of impermeable Polyurethane coated nylon ticking. Group 2 included 28 patients who were provided with new, conventional, mat Polyurethane mattresses, quilts, pillows, bed linens and quilt covers made of cotton and polyester which had not been Microstop treated. Group 3 included 15 patients who used their old bedding. Mite counts were performed on samples of dust collected from the old mattresses, pillows and quilts before the bedding was changed. After changing the bedding, mite counts were performed on dust from the same three bed sites at the end of months 1, 2, 3, 6, 9, and 12. Morning and evening peak expiratory flow, asthma symptom scores, were recorded by each patient at least 1 month before entering the study and every month during the one-year study period. Mattress mite counts were significantly reduced in Group 1 but not in Groups 2 or 3. However, quilt mite counts were significantly reduced in both Group 1 and Group 2 throughout the 12-monthstudy while mite counts in Group 3 quilts remained unchanged. The results provide evidence that the PU-coated nylon material was effective in reducing house dust mites, but do not demonstrate that the Microstop treatment had an obvious anti-mite effect. One-year follow-up of asthma symptom scores showed significant improvement in Group 1, but not in Groups 2 or 3. This suggests that the Microstop-treated bedding, as a system, was effective in asthma prevention.     

Cytotoxicity of sera from rats with puromycin aminonucleoside nephrosis

BACKGROUND: Sensitization to allergens has been shown to be a risk factor for adults with acute asthma first seen in the emergency department. OBJECTIVE: The purpose of this study was to evaluate the prevalence of specific IgE to common aeroallergens in children with asthma first seen in the emergency department and in control subjects. METHODS: Fifty-four children, aged 3 to 16 years (mean age, 8.34 years) who visited the emergency department for treatment of acute bronchospasm or other illness, were evaluated. Specific IgE to seven common aeroallergens and four common storage mites was determined. Group I consisted of 29 patients who had acute bronchospasm and histories of recurrent asthma. Group II consisted of 25 control subjects who had no clinical history of atopic disease. Group I and II were compared for differences in the prevalence of positive RAST responses to the 11 allergens tested. Dust samples were collected from 17 homes of subjects in group I and from 13 homes of subjects in group II and were analyzed for levels of Der p 1 and Der f 1. RESULTS: Statistically significant differences in the prevalence of positive RAST results between groups I and II were found in response to: Dermatophagoides pteronyssinus, 89.6% versus 36% (p = 0.0001); Blattella germanica, 45.8% versus 9.5% (p = 0.018); Alternaria tenuis, 44.8% versus 4% (p = 0.001); and the storage mites Aleuroglyphus ovatus, 39.2% versus 4% (p = 0.002); Blomia tropicalis, 42.8% versus 0% (p = 0.0002); Chortoglyphus arcuatus, 46.4% versus 0% (p = 0.0001); and Lepidoglyphus destructor, 32.1% versus 0% (p = 0.0019). Mean specific IgE levels, expressed as percent of the total counts bound, were significantly higher in group I compared with group II only in response to D. pteronyssinus, 21.9% versus 2.1% (mean percent of total counts bound) (p = 0.0001). Analysis of dust samples revealed no significant differences between the two groups, except for a higher concentration of Der f 1 in the sofas of subjects in group II. CONCLUSION: Sensitization to D. pteronyssinus, storage mites, and, to a lesser extent, to A. tenuis and B. germanica is associated with acute childhood asthma that requires emergency treatment in Florida.     

Progression of permanent atrial fibrillation after atrioventricular junction ablation and dual-chamber pacemaker implantation in patients with paroxysmal atrial tachyarrhythmias

Control of the house dust mite allergen has received considerable attention owing to its importance in some allergic diseases. One aspect of dust mites and their allergen-carrying faecal particles that has not been reported on, which may have allergen control applications, is the electrostatic charge they carry in the natural environment. To promote tribo-electric charging, household dust containing dust mite allergen and live house dust mites are separately agitated while in contact with either polypropylene, nylon or earthed metal. The charged dust and mites are subsequently subjected to electrostatic separation and collection. Results for concentrations of the house dust mite allergen, Der p1, indicate that, when subjected to nylon, Der p1 carrier particles appear to be predominantly positively charged. Similarly, when subjected to polypropylene, Der p1 carrier particles also appear to be positively charged. Reduction of excess free charge by agitation against earthed metal does not appear to affect the observed charging characteristics, indicating that the positive charge may be bound or inherent in the Der p1 carrier particles. In contrast, house dust mites exposed to nylon appear to be generally charging negative, whereas mites exposed to polypropylene appear to be charging positive. The observed electrostatic characteristics of the mites and Der p1 carrying particles will be useful in the future development of electrostatic allergen control methods.     

Heparan sulfate staining of the glomerular basement membrane in relation to circulating anti-DNA and anti-heparan sulfate reactivity: a longitudinal study in NZB/W F1 mice

BACKGROUND: Pyroglyphid mites are considered a major cause of house dust allergy. The occurrence and possible pathogenic role of other biologic components of house dust, in particular bacteria, has received less attention. OBJECTIVE: The aim of this study was to examine bacteria present in the samples of house dust from beds, in comparison to fungi and mites recovery. METHODS: Samples of bed dust were collected from 40 homes in Upper Silesia (Poland). Of these, 19 came from the homes of people with asthma caused by house dust and 21 from the homes of people without allergy. The concentrations of bacteria, fungi, mites, and endotoxin and species composition of microflora and acarofauna were determined. RESULTS: The overall mean concentrations of mesophilic bacteria, thermophilic bacteria and fungi, including yeasts, were, respectively, 1.6 x 10(6), 1.7 x 10(3), and 1.6 x 10(4) CFU/g. Samples contained an average of 8.4 mites/g and the ten samples assayed for bacterial endotoxin averaged 80.4 ng/mg. A total of 55 species of bacteria, 40 of fungi and 13 of mites were found. Gram-positive cocci (mostly Staphylococcus spp.) were the predominant mesophilic bacteria, followed by corynebacteria and Bacillus spp. Thermophilic bacteria were represented only by actinomycetes, with Thermoactinomyces vulgaris predominant. The most numerous fungi were Penicillium spp. and Aspergillus spp. followed by yeasts. The most abundant mites were Dermatophagoides spp. which formed > 85% of the total count. There were no significant differences between the homes of allergic and nonallergic people in the concentrations of total bacteria, fungi, and mites. Bacillus, Aspergillus and total filamentous fungi (molds), but not yeasts, were significantly more numerous in the homes of people with asthma caused by house dust. CONCLUSION: The results suggest that some species of bacteria and filamentous fungi should be considered potential causes of house dust allergy.     

Kinetics of allergen expression in cultures of house dust mites, Dermatophagoides pteronyssinus and D. farinae (Acari: Pyroglyphidae)

Laboratory cultures of house dust mites Dermatophagoides pteronyssinus (Trouessart, 1897) and Dermatophagoides farinae Hughes, 1961 were used to study the population dynamics of the mites and the kinetics of antigen appearance. The analysis of extracts obtained after different incubation periods, carried out by SDS-PAGE, immunoblotting, and enzyme-linked immunosorbent assay, allows for the definition of 3 different growth phases: the latency phase (F1); the exponential growth phase (F2) during which the allergenic proteins, including the Der 1 and Der 2 major allergens, were expressed more intensely and in larger quantities; and a final phase (F3), death, in which the lowest rates of allergenic components with a clearly different pattern were seen. The data obtained from this work demonstrates that mite cultures during the maximum growth phase (F2) contain the largest amount of allergenic components as well as the highest major allergen concentrations.     

Transient sensitization to house-dust mites: a study on the influence of mite exposure and sex

This study aimed to evaluate the prognosis of a previous positive skin test to house-dust mites (HDM) in relation to environmental exposure. A total of 115 children, 50 from Stockholm and 65 from northern Sweden, all with a previous (average 2.5 years) positive Phazet (Pharmacia AB, Uppsala, Sweden) skin prick test (SPT) to extracts of Dermatophagoides pteronyssinus (Dpt) and/or D. farinae (Df) were included. Dust samples were collected from the children's mattresses, and the total (Dpt, Df, and D. microceras [Dm]) amount of major mite allergen was measured by ELISA (50 children) and expressed as microgram allergen per gram of dust, or was measured by microscopy (65 children). The results of microscopic mite counts were transformed to approximate allergen levels as 2 micrograms equals 100 mites per gram of dust. Of 115 originally SPT-positive children, only 48 (48%) remained positive at retest, while the majority (58%) were SPT negative after 2 years. Among the 67 converted children, 11 were still exposed to mite allergen, but only to low concentrations (only one converted child being exposed above the suggested threshold level [TLV] of 2 micrograms/g), compared to 15/48 children still SPT positive who were exposed above the TLV. This shows that continued mite exposure is a major risk factor (OR = 30, CI 4.8-184) for continued positive SPT to HDM. A minor risk factor for continued sensitization was sex, boys having a higher risk than girls (OR = 2.2, CI 1.0-4.8). In conclusion, a surprisingly high rate of SPT conversion occurred, mainly as a result of a favorable indoor environment with low exposure to HDM and, to a lesser degree, as a result of sex. The present results support the view that the risk level of exposure is 2 micrograms mite allergen per gram of dust.