New research in management and prevention allergies and asthma,
presented at the AAAAI Annual Meeting in San Diego, CA

SAN DIEGO- Moldy wall surfaces contain higher numbers of house-dust mites, compared to wall surfaces without mold, according to a study presented at the 2007 AAAAI Annual Meeting in San Diego, CA.

Previous research studying the distribution of house-dust mites (HDM), concluded that there are no HDM on the walls. Yaël Gernez, Hôpitaux de Marseille, Marseille, France, and colleagues, sought to determine if moldy dwellings may have house-dust mites (HDM) because of high humidity, favoring both mold and HDM development.

Researchers studied 50 residences with moldy wall surfaces at least equal to 50 cm². Dust was collected from both the moldy surface and 20 cm away from the mold. It was then observed for HDM.

Results showed that 54% of moldy wall surfaces contained HDM, compared to 6% of walls without mold. This shows that HDM avoidance programs should include elimination of moldy surfaces in the home.

Exposure to dogs during infancy reduces risk of asthma
Children exposed to dogs during infancy have a reduced risk of asthma at age six, according to a study presented at the 2007 AAAAI Annual Meeting in San Diego, CA.

Nicholas A. Hallett, University of Wisconsin School of Medicine and Public Health, Madison, WI, and colleagues, examined the relationship between pet ownership and asthma diagnosis in 253 children enrolled in the Childhood Origins of ASThma (COAST) study. Pet ownership was categorized in groups according to exposure at birth, age three years, both or neither. All statistical analyses compared exposure groups to non-exposed children.

Results showed that children who owned a dog at both birth and age three years were less likely to develop asthma at age six (18.3% vs. 33.6%). Cat ownership at birth and/or age three was not significantly related to asthma diagnosis at age six.

This concludes that exposure to dogs, but not cats, throughout infancy and early childhood is associated with a reduced risk of asthma at age six, suggesting that early, prolonged exposure may be a critical for environmental exposures to alter the risk of asthma.

Diesel Exposure Model Reduces Allergy Risk assessment errors
University of Cincinnati (UC) environmental health experts say their research improves prior methods of classifying exposure to diesel exhaust particulates that help minimize inaccuracies and better predict a child's risk for wheezing.

Many prior air pollution studies rely heavily on what are known as proximity (distance) exposure models, which assume all subjects in a given distance from an exposure source-for example, a major interstate highway-are equally exposed.

Pat Ryan, lead author of the UC study, says that isn't necessarily true in urban environments, where infants are exposed to a large number of pollutants, and he advocates using the so-called land-use regression model.

"Unlike proximity models," says Ryan, "land use regression lets us consider more complex exposure factors-like elevation and the type or number of passing vehicles-in our initial assessment. This allows us to create 'buffers' around specific sample sites and control for factors influencing that location's overall diesel exposure levels."

Specific models are needed for evaluating exposure levels in large cities to accurately determine exposure levels and identify populations at risk for high exposure to air pollutants, Ryan says.

He will present the UC team's findings at the annual meeting of the American Academy of Allergy, Asthma and Immunology in San Diego on Feb. 26.

Ryan and his coauthors analyzed data from 622 infants enrolled in the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) who were identified as being at greater risk for developing allergies because at least one of their parents had allergies.

Researchers found that infants who were exposed to the highest levels of elemental carbon-a marker of diesel exposure-were more than twice as likely to wheeze compared with the infants exposed to lower levels.

Research has shown that diesel exhaust particles (DEP), breathable particles able to absorb and transport proteins, aggravate rhinitis (hayfever) and asthma symptoms.

Exposure to tobacco smoke in early life decreases IgE at 18 years of age
Exposure to parental environmental tobacco smoke (ETS) in utero or through age two years is associated with lower IgE levels at age 18 years, with a greater effect in males, according to a study presented at the 2007 AAAAI Annual Meeting in San Diego, CA.

Kimberley J. Woodcroft, Henry Ford Health System, Detroit, MI, and colleagues, determined parental smoking by a predelivery questionnaire, and at one and two years. ETS exposure was determined by one parent smoking at least one cigarette daily. Total IgE was measured in blood collected from subjects at age 18 years.

Researchers found that IgE levels of male teens exposed during gestation were 11.9 kU/L, compared to 35.7 in male teens not exposed. IgE levels for male teens exposed through age two were 21.1 versus 35.3 in those not exposed.

This study shows that exposure to parental cigarette smoke in utero or through age two is associated with lower IgE levels at age 18 years. Elevated IgE levels are associated with development of allergic disease.

Children are more susceptible to pollution-induced airway diseases than adults
Children who are exposed to diesel exhaust particles (DEP) have a greater inflammatory response than adults, according to a study presented at the 2007 AAAAI Annual Meeting in San Diego, CA.

David Diaz Sanchez, PhD, University of California at Los Angeles, Los Angeles, CA, and colleagues, studied 20 adults and 15 children (10-15 years of age) who underwent randomized exposure to four DEP nasal challenges at increasing amounts. Gene expression level 24 hours after exposure, and cellular inflammation was measured and results in children and adults were compared.

Results showed that cell count and inflammation positively correlated with increasing DEP challenges in both adults and children. At the highest DEP concentration, children had increased cellular inflammation, compared to adults.

This study concludes that children have a greater inflammatory response with higher DEP exposure as compared to adults. Impaired antioxidant defenses in children may lead to increased vulnerability to pollution-induced airway diseases.

Cigarette smoke may exacerbate airway inflammation in pulmonary disease
Cigarette smoke may alter the function of mast cells and eosinophils in the course of other diseases, exacerbating airway inflammation in acute and chronic pulmonary disease, according to a study presented at the 2007 AAAAI Annual Meeting in San Diego, CA.

Philippe Hasgall and Ilham Orouk, two students working under the direction of Professors Francesca Levi-Shaffer and Leah H. Bellehsen, at The Hebrew University of Jerusalem, isolated human cord blood mast cells (CBMC) and human peripheral blood eosinophils (EOS) and exposed them to varying concentrations of cigarette smoke extract and examined the results.

Results show that in vitro exposure of human CBMC and EOS to components of cigarette smoke influenced several properties: survival, activation, mediator synthesis and release. These results show that cigarette smoke may change the function of mast cells and eosinophils in the course of other diseases, exacerbating airway inflammation in acute and chronic pulmonary disease.

These studies were presented at the 2007 Annual Meeting of the American Academy of Allergy, Asthma and Immunology (AAAAI). The AAAAI is the largest professional medical specialty organization in the United States representing allergists, asthma specialists, clinical immunologists, allied health professionals and others with special interest in the research and treatment of allergic disease.

Allergy/immunology specialists are pediatric or internal medicine physicians who have elected an additional two years of training to become specialized in the treatment of asthma, allergy and immunologic disease.

Established in 1943, the AAAAI has more than 6,000 members in the United States, Canada and 60 other countries. The AAAAI serves as an advocate for the public by providing educational information through its Web site www.aaaai.org, and its Physician Referral and Information Line at (800) 822-2762.

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