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Collection of house dust for analysis of mite allergens. Allergen-reducing effect of a self-administered procedure.

To assess allergen-reducing effect of dust collection from mattresses, patients were asked to vacuum clean the entire surface of their mattresses for 5 min with their household cleaners at specified intervals ranging from 1-21 days. Ten patients performed four collections, nine patients only two. Amounts of dust, concentrations and amounts of major allergens from Dermatophagoides pteronyssinus (Dp42), Dermatophagoides microceras (Dm6), and Dermatophagoides farinae (Df6) were determined. The first sampling caused a statistically significant reduction in the absolute amounts of allergens in a following sample. The same tendency was seen in dust weight but not in concentrations of allergens. At intervals of 1 or 3 weeks no consistent changes could be registered. Differences were small and good reproducibility of the sampling and analysing procedure could be assumed. Since the self-administered procedure is much cheaper and easier to handle than sampling done by technicians with special equipment, it can be recommended for sequential analysis of allergen exposure.

Allergens↗

Medication requirements and house dust mite exposure in mite-sensitive asthmatics.

To better understand the clinical consequences of exposure to house dust mites (HDM), we investigated the relationship between treatment requirements to control symptoms in mite-allergic asthmatic patients and HDM-allergenic levels in their mattresses. This study included 49 asthmatic subjects recruited from an outpatient clinic. The protocol consisted of a questionnaire about the number of asthma attacks and treatment requirements in the last 3 months. Patients provided a sample of house dust collected from their mattresses by a standardized vacuum cleaning procedure. Mean antigen P1 equivalent defined as the sum of major allergens Der pI and Der fI (Ag P1 Eq) level was 1.34 micrograms/g dust in patients who had no treatment, 5.4 micrograms/g dust in patients who took puffs of beta 2-agonists only when required and 17.8 micrograms/g dust in patients who required daily long-term treatment. Similar relationships were demonstrated between mean Ag P1 Eq levels and the number of asthma attacks. These data support the clinical role of allergenic exposure in HDM-allergic asthmatics.

Adolescent↗

Peak-flow variability in asthmatic children is not related to wall-to-wall carpeting on classroom floors.

The hypothesis was tested that wall-to-wall carpets on school classroom floors have a negative effect on the respiratory health of asthmatic children. Asthmatic patients (n = 98) were selected from the records of the Sophia Children's Hospital in Rotterdam. The patients were between 5 and 11 years old. All children had peak-flow measurements three times a day for a 1-month period. The parents of the children completed a diary in which respiratory symptoms and medication use were recorded daily for the same period. Dust samples were taken from classroom floors, living-room and bedroom floors, and mattresses of the children. The dust samples were analyzed for Der p I content, the major allergen of the house-dust mite Dermatophagoides pteronyssinus. The results of the study showed that there was no significant difference between children visiting schools with or without carpeted classroom floors in peak-flow variability, acute respiratory symptoms, or medication use. The Der p I content of dust collected from classroom floors was much lower than of dust collected from homes. There was a significant correlation between peak-flow variability and mattress dust Der p I content in asthmatic children sensitized to dust mites, but not between peak-flow variability and classroom floor dust Der p I content. We concluded that carpeted classroom floors do not contribute to asthma symptom severity, possibly because of the low levels of Der p I on them.

Allergens↗

Ventilation in homes infested by house-dust mites.

Thirty single-family homes with either high (> or = 2000 ng/g) or low (< or = 1000 ng/g) house-dust mite (HDM) allergen levels in mattress dust were examined for ventilation, thermal climate, and air quality (formaldehyde and total volatile organic compounds (TVOC). Elevated concentrations of HDM allergen in mattress and floor dust were associated with the difference in absolute humidity between indoor and outdoor air, as well as with low air-change rates of the home, particularly the bedroom. No correlation was found between concentration of TVOC or formaldehyde in bedroom air and HDM allergen concentration. In regions with a cold winter climate, the air-change rate of the home and the infiltration of outdoor air into the bedroom appear to be important for the infestation of HDM.

Air Pollution, Indoor↗

Allergen avoidance in a day-care center.

The predominant sensitizing allergens in Swedish asthmatic children are furred pet animals. Poor ventilation and increased indoor humidity cause accumulation of pet allergens indoors. Indirect contacts with cats also increase pet allergen exposure. We investigated whether the concentration and the total amount of cat (Fel d I) and dog (Can f I) allergen in dust from various surfaces in a day-care center were influenced by extensive renovation, installation of a new ventilation system, ventilation of floors, and avoidance by families and personnel of direct and indirect contacts with pets. The cleaning routine in the day-care center was changed extensively after renovation. Old mattresses, pillowcases, curtains, sofas, and soft toys were removed, and new material were purchased. Dust was collected from various surfaces before and after renovation from table and chair surfaces, floors, curtains, mattresses, pillows, cushion-like toys, and sofas on five occasions during a 12-month period. Fel d I and Can f I allergen levels were determined by sandwich ELISA. The reduction in the total amount of both Fel d I and Can f I/sampling area was more pronounced than the reduction in the concentration of allergen/g of dust. After renovation, the mean cat and dog allergen concentration was decreased by six and 10 times, respectively. After 1 year, the total amount of cat allergen was lower in all areas (from 24 ng to < 1 ng/sampling area, P < 0.05). Already at the first sampling after renovation, the total amount of dog allergen had decreased more than 10 times. In a previous study, we found the median concentration of cat and dog allergen to be 10-30 times higher in ordinary day-care centers. Our present study demonstrates that children changing from a normal center to the renovated center would be exposed to much lower levels of cat and dog allergen. Combined measures such as installation of mechanical ventilation, ventilated floors, regular extensive cleaning, and, probably most important, avoidance of direct and indirect contacts with pets, should decrease cat and dog allergen exposure in day-care centers.

Adult↗

Sensitization to house dust mites in Reykjavik, Iceland, in the absence of domestic exposure to mites.

BACKGROUND: House dust mites are common sources of indoor allergens. In Reykjavik, Iceland, 9% of the young adult population had serum-specific IgE to Dermatophagoides pteronyssinus. Sensitization to mites is usually assumed to be due to exposure to house dust mites in the indoor environment. This investigation was carried out to measure the concentrations of house dust mite allergens and to investigate which species of mites were present in beds in Iceland. METHODS: A total of 197 randomly selected adults were visited at home using the European Community Respiratory Health Survey (ECRHS) II Indoor protocol. Dust samples were collected from mattresses for measurement of house dust mite allergen concentrations and to estimate the number and type of house dust mites. Additional samples from mattresses and floors were collected from the homes of 10 patients with positive skin prick tests (SPT) to D. pteronyssinus. House dust mite allergen concentrations were measured using ELISA and examination of mite species was carried out using microscopy. Climatic parameters were assessed using psychrometer readings in the bedrooms and outdoors. RESULTS: We found two single mite specimens, both D. pteronyssinus, in two dust samples. Mite allergen analyses indicated that two other dust samples had Der f 1 results close to the cut-off of 0.1 microg/g of dust. No samples were positive for Der p 1. In an additional collection of dust from the homes of 10 SPT-positive patients no Dermatophagoides spp. were found. CONCLUSIONS: Reykjavik citizens are exposed to extremely low amounts of house dust mite allergens in their homes. Possible alternative sources for sensitization are discussed, such as bird nests, exposure from travelling abroad, or other mites or invertebrates that cross-react with house dust mite allergens. Our findings suggest that exposures other than to house dust mites indoors are possible sources of mite allergen exposure.

Adult↗

Exposure to pets, and the association with hay fever, asthma, and atopic sensitization in rural children.

BACKGROUND: An increasing number of studies report pet exposure to be associated with lower risk of asthma and allergies. This 'protective pet effect' has been suggested to result from a modified T-helper (Th)2-cell response, or because of increased microbial load in homes where pets are kept. We examined the associations between pet contact and the occurrence of asthma and allergies in children of the rural Allergy and Endotoxin (ALEX) population, taking farm animal contact, endotoxin and cat allergen levels in mattress dust into account. METHODS: Information about contact with pets and farm animals, asthma and allergy were collected for 812 children by a standardized parents' questionnaire and an interview. Mattress dust endotoxin and cat allergen levels as well as specific IgE and IgG4 antibodies to Fel d1 were determined. RESULTS: Current contact with dogs was inversely associated with diagnosed hay fever (OR 0.26, 95% CI 0.11-0.57), diagnosed asthma (OR 0.29, 95% CI 0.12-0.71), sensitization to cat allergen (OR 0.48, 95% CI 0.23-0.99) and to grass pollen (OR 0.55, 95% CI 0.33-0.94), but not with increased IgG4 levels. Early and current contact with cats were associated with reduced risk of wheezing (OR 0.48, 95% CI 0.23-1.00, and OR 0.49, 95% CI 0.26-0.92, respectively) and grass pollen sensitization. Adjustment for farm animal contact but not for endotoxin and cat allergen exposure attenuated these associations and the effect of pet was stronger among farmers' children. CONCLUSION: Although pet exposure was very frequent in this rural population, the inverse relation between current dog contact, asthma and allergy was mostly explained by simultaneously occurring exposure to stable animals or was restricted to farm children. In addition, a subtle form of pet avoidance may contribute to the protective effect of pet.

Animals↗

House-dust mites and summer cottages.

BACKGROUND: Estimated indoor climate conditions in unheated summer cottages offers house-dust mites unfavorable temperature and feeding conditions while giving them optimum humidity conditions. We aimed to estimate the exposure level of house-dust mites in summer cottages. METHODS: A total of 37 summer cottages were sampled for house dust and storage mites in three locations and the results compared with samples from 33 patients suspected of house-dust mite allergy and living in ordinary houses. The processed dust samples were investigated by microscopy and exposure levels given as number of mites per 0.1 g dust. RESULTS: The summer cottages were without exception all heavily infested with threefold or higher concentrations of both house dust and storage mites in comparison with ordinary houses. In unheated summer cottages were found tropical high concentrations of house dust and storage mites with a median concentration of house-dust mites in mattress dust of 2000 house-dust mites/g of dust which corresponds to an average of 40 microg allergen/g of mattress dust. CONCLUSIONS: As a probable consequence of high indoor air humidity conditions in unheated summer cottages in winter, dust samples contained threefold or higher concentrations of house dust and storage mites. Indoor humidity conditions thus more than compensated for lack of continuous supply of skin scales from human beings and an unfavorable low indoor air temperature. The uniform high mite exposure in summer cottages is likely to imply disease deterioration in patients already allergic to mites.

Acaridae↗

Are house dust mite allergen levels influenced by cold winter weather?

BACKGROUND: Moisture is vitally important for house dust mites and they cannot survive in cold or hot-dry climates. AIMS OF THE STUDY: To investigate the influence of two extraordinarily cold and dry winters in 1995/1996 and 1996/1997 on house dust mite levels in German homes. METHODS: Dust samples were collected between June 1995 and December 2001 on the mattresses of 655 adults and 454 schoolchildren living in five different areas of Germany. We compared house dust mite allergen Dermatophagoides pteronyssinus (Der p 1) levels before and during the winters of 1995/1996 and 1996/1997 with levels after these winters. RESULTS: D. pteronyssinus (Der p 1) levels in samples taken after the cold winters of 1995/1996 and 1996/1997 were approximately two times lower than Der p 1 levels in dust samples collected before or during these respective winters (Geometric means: Erfurt 89 vs 33 ng/g; Hamburg 333 vs 219 ng/g; Bitterfeld, Hettstedt, and Zerbst 296 vs 180 ng/g). Except for Hamburg, the decrease in Der p 1 levels was statistically significant. D. pteronyssinus levels measured in dust samples collected in 2001 (i.e. 3 years after the two cold winters) show a statistically non-significant increase (Geometric means: Erfurt 33 vs 39 ng/g; Hamburg 219 vs 317 ng/g), suggesting that it may take a long time for mite allergen levels to increase again after a sudden decrease. CONCLUSION: We conclude that Der p 1 levels in German mattress dust samples have been approximately reduced by a factor of three to four by the two consecutive cold winters of 1995/1996 and 1996/1997.

Adult↗

Nonlinear relations between house dust mite allergen levels and mite sensitization in farm and nonfarm children.

BACKGROUND: Low sensitization rates to common allergens have been observed in farm children, which might be due to high exposure to microbial agents. It is not known how microbial agents modify the association between specific allergen exposure and sensitization. OBJECTIVE: To examine the relations between house dust mite allergen exposure and mite sensitization in farm and nonfarm children and to assess the effects of microbial agents levels on this association. METHODS: Major mite allergens of Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1), endotoxin, beta(1,3)-glucans and fungal extracellular polysaccharides were measured in mattress dust of 402 children participating in a cross-sectional study in five European countries. Mite allergen (Der p 1 + Der f 1) levels were divided into tertiles with cut-offs 1.4 and 10.4 microg/g. Sensitization was assessed by measurement of allergen-specific immunoglobulin E against house dust mite. RESULTS: Prevalence ratios of mite sensitization for medium and high when compared with low mite allergen levels were 3.1 [1.7-5.7] and 1.4 [0.7-2.8] respectively. Highest mite sensitization rates at intermediate exposure levels were consistently observed across country (except for Sweden) and in both farm and nonfarm children. The shape of the dose-response curve was similar for above and below median mattress microbial agent levels, but the 'sensitization peak' appeared to be lower for above median levels. CONCLUSIONS: Our data suggest a bell-shaped dose-response relationship between mite allergen exposure and sensitization to mite allergens. In populations with high microbial agent levels and low sensitization rates, the curve is shifted down.

Adolescent↗

Prenatal exposure to mite and pet allergens and total serum IgE at birth in high-risk children.

To examine the relationship between prenatal exposure to mite, cat and dog allergens and total serum IgE at birth in newborns at high risk of asthma. In the homes of 221 newborns with at least one first-degree relative with asthma, concentrations (ng/g dust) of allergens of house dust mite (mite), cat and dog were measured at the fourth to sixth month of pregnancy in dust samples from the maternal mattress and living room. At day 3-5 after birth, total IgE was measured in capillary heel blood. A total number of 174 blood samples were available (11 mothers refused newborn's blood sampling, and in 36 cases the blood sample was too small for analysis). In 24% of the newborns, total IgE was elevated (cut-off value 0.5 IU/ml). A significant dose response relationship was found between increasing mite allergen levels [divided in quartiles ng/g dust (qrt)] and the percentage of elevated IgE: first qrt (0-85 ng/g) 13%; second qrt (86-381) 19%; third qrt (382-2371) 26%; fourth qrt (> or =2372) 42%, respectively, p=0.01. This relationship remained significant after adjusting for passive smoking, maternal and paternal mite allergy, socio-demographic factors, birth characteristics and (breast) feeding practice in the first week of life. In high-risk newborns, prenatal exposure to mite allergens, but not to cat and dog allergens from dust of the living room and of the maternal mattress was associated with total serum IgE at birth.

Allergens↗

A technique of anastomosing bowel ends with discrepancy in size.

There have been only a few methods devised to solve the problem of discrepancy in size of the bowel ends for anastomosis. We describe another method to overcome this problem by using a one-layer open technique. For the posterior wall the anastomosis consists of a horizontal mattress suture on the larger end and a vertical mattress suture on the smaller end. For the anterior wall the Gambee suture is used.

Colon↗

Indoor air quality risk factors for severe lower respiratory tract infections in Inuit infants in Baffin Region, Nunavut: a pilot study.

Inuit infants have extremely high rates of lower respiratory tract infection (LRTI), but the causes for this are unclear. The aims of this study were to assess, in young Inuit children in Baffin Region, Nunavut, the feasibility of an epidemiologic study of the association between indoor air quality (IAQ) and respiratory health; to obtain data on IAQ in their housing; and to identify and classify risk factors for LRTI. Twenty houses in Cape Dorset, Nunavut with children below 2 years of age, were evaluated using a structured housing inspection and measurement of IAQ parameters, and a respiratory health questionnaire was administered. Twenty-five percent of the children had, at some time, been hospitalized for chest illness. Houses were very small, and had a median of six occupants per house. Forty-one percent of the houses had a calculated natural air change rate <0.35 air changes per hour. NO(2) concentrations were within the acceptable range. Smokers were present in at least 90% of the households, and nicotine concentrations exceeded 1.5 microg/m(3) in 25% of the dwellings. Particulates were found to be correlated closely with nicotine but not with NO(2) concentrations, suggesting that their main source was cigarette smoking rather than leakage from furnaces. Mattress fungal levels were markedly increased, although building fungal concentrations were low. Dust-mites were virtually non-existent. Potential risk factors related to IAQ for viral LRTI in Inuit infants were observed in this study, including reduced air exchange and environmental tobacco smoke exposure. Severe lower respiratory tract infection is common in Inuit infants. We found reduced air change rates and high occupancy levels in houses in Cape Dorset, which may increase the risk of respiratory infections. This suggests the measures to promote better ventilation or more housing may be beneficial. Further health benefits may be obtained by reducing bed sharing by infants and greater turnover of mattresses, which were found to have high levels of fungi.

Air Pollutants↗

Sensitization of children in the Stockholm area to house dust mites.

Atopic sensitization of children in the Stockholm area to house dust mites (HDM) was investigated in a case-control study. Sixty children with and 60 without positive skin prick tests for HDM were matched for age and sex. HDM-sensitized children had previously more often lived in other areas known to be mite infested than the control children. Sensitization to mites was related to dampness in the homes, but no significant relationship was found to the type of residence, frequent visits to a summer house in the archipelago or parental smoking. Dust samples from mattresses of the children with the strongest positive reactions to mites in skin prick tests and the respective controls were subjected to an enzyme immunoassay, to measure the content of the major allergens of the Dermatophagoides (D.) species D. pterinyssinus, D. farinae and D. microceras. Mattress dust samples from the beds of HDM-sensitized children contained significantly higher HDM antigen concentrations than those from the beds of controls. Private houses contained significantly more HDM antigens than flats and 10 of 11 homes in which a dampness problem was recognized contained mite antigens. It is postulated that mite infestation is increasing in the area, energy-saving measures creating improved conditions for HDM survival.

Adolescent↗

The total thermal insulation of the new-born baby.

1. One hundred and seventeen healthy new-born babies weighing between 0.9 and 4.8 kg at delivery have been studied during the first ten days of life, and sixteen of these babies have been studied serially for 6 weeks after birth. The babies lay supine in a draught-free environment (air speed 4-5 cm/sec) of moderate humidity. The operative temperature was between 26 and 38 degrees C for the babies who were studied naked.2. Total non-evaporative heat loss was calculated from simultaneous measurements of oxygen consumption, evaporative water loss and the concomitant change in mean body temperature.3. Approximately 10% of the total body surface area was in contact with the mattress or floor. Conductive heat loss accounted for only about 5% of all non-evaporative heat loss when the naked baby was lying on a thick foam mattress, but for as much as 25% when the baby was lying in a water-jacketed chamber with a floor of clear plastic approximately 5 mm thick.4. Insulation to heat loss by convection and radiation varied with environmental temperature. Total specific insulation was low in a warm environment when the naked baby vasodilated, and rose by between 16 and 25% to a maximum in an environment of 31 degrees C. It decreased significantly when the baby became physically active in environments with a temperature less than this.5. Total specific insulation in an environment of 31 degrees C varied with body size: it averaged 0.156 degrees C.m(2).hr/kcal in seven naked babies weighing 0.9-1.2 kg, rose to 0.190 degrees C.m(2).hr/kcal in twelve babies weighing 1.8-2.2 kg, and averaged 0.201 degrees C.m(2).hr/kcal in the thirty-four babies who weighed over 3 kg. Tissue insulation accounted for 23% of this total specific insulation in the smaller babies, and about 28% of the total in babies weighing over 3 kg.6. Clothing ten babies in a vest, napkin and long cotton nightdress increased the total specific insulation by an average of 0.23 degrees C.m(2).hr/kcal.

Birth Weight↗

Reduction of exposure of newborns and caregivers to very high electromagnetic fields produced by incubators.

The aims of this paper is to measure whether ferromagnetic panels sufficiently reduce the high electromagnetic fields (EMF) to which newborns are exposed in incubators and to which caregivers are exposed when working near the incubators. We measured EMF at mattress level in three neonatal incubators with and without ferromagnetic panels between the electric motor and the mattress. We then measured the EMF at the level of the maximum emission point for caregivers, i.e., near the display panel. The ferromagnetic panels were (a) 5 mm thick iron, (b), (c), (d) respectively, one, two, and three sheets of 0.3 mm thick mu-metal. The weight of iron sheet was 4 g/cm2, and mu-metal 0.2 g/cm2. The use of the ferromagnetic panels significantly reduced the EMF. No significant difference in attenuation was recorded using one, two, or, three sheets of mu-metal, or a single sheet of iron. One, two, and three sheets of mu-metal reduced EMFs by 77%, 82%, and 84.3%, respectively; the reduction with iron was 80%. EMF values measured in incubators were higher than those to which the general population is exposed. The use of ferromagnetic panels significantly reduces the level of EMFs to which neonates and caregivers are exposed.

Caregivers↗

Thermal energy deposition from a single-loop rf whole-body applicator.

Whole-body hyperthermia at moderate temperatures (40.0 +/- 0.5 degrees C) is currently being investigated to assess its effectiveness as an adjuvant to other cancer therapies. At our institution, the whole-body heating is achieved by a combination of hot air circulation and rf inductive heating at 27.1 MHz. This paper reports the results of a study of the thermal energy deposition pattern associated with the rf applicator. The applicator consists of a single loop of nearly elliptical shape with dimensions 20 x 46 cm. The loop is embedded in a mattress and is fed by lead wires entering the side of the mattress. Temperature mapping in a heated gelatin phantom placed just above the rf loop showed maximum heating near the lead wires and a cool region above the center of the loop. Calculations of the magnetically induced and capacitive contributions to the electric field near the applicator indicate that the heating near the lead wires is largely capacitive in nature. This feature of the rf heating is of interest because capacitive fields result in preferential heating of fatty tissues. Further calculations showed that the capacitive heating contribution falls away much more rapidly than the induced field contribution with increasing distance from the plane of the rf loop.

Diathermy↗

MICROVIBRATIONS IN MAN AND DOLPHIN.

Microvibrations were recorded from the dorsal body surface of a bottle-nosed dolphin (Tursiops truncatus) while it swam in water and while it lay on a foam rubber mattress in an air environment. Unlike poikilothermic water-living animals which do not manifest microvibrations, this homeothermic mammal has 13-cycle per second microvibrations similar to those of man and other homeotherms. For comparative purposes, microvibrations of 11 cycles per second were recorded from the arm of a man while lying on the same mattress. The nature and origin of these microvibrations is discussed in relation to physiological tremors and shivering.

Animals↗