Direct on air sampling filter quantification of cat allergen

Controlled antibody/(bio-) conjugation of inorganic nanoparticles for targeted delivery

Arguably targeting is one of the biggest problems for controlled drug delivery. In the case that drugs can be directed with high efficiency to the target tissue, side effects of medication are drastically reduced. Colloidal inorganic nanoparticles (NPs) have been proposed and described in the last 10years as new platforms for in vivo delivery. However, though NPs can introduce plentiful functional properties (such as controlled destruction of tissue by local heating or local generation of free radicals), targeting remains an issue of intense research efforts. While passive targeting of NPs has been reported (the so-called enhanced permeation and retention, EPR effect), still improved active targeting would be highly desirable. One classical approach for active targeting is mediated by molecular recognition via capture molecules, i.e. antibodies (Abs) specific for the target. In order to apply this strategy for NPs, they need to be conjugated with Abs against specific biomarkers. Though many approaches have been reported in this direction, the controlled bioconjugation of NPs is still a challenge. In this article the strategies of controlled bioconjugation of NPs will be reviewed giving particular emphasis to the following questions: 1) how can the number of capture molecules per NP be precisely adjusted, and 2) how can the Abs be attached to NP surfaces in an oriented way. Solution of both questions is a cornerstone in controlled targeting of the inorganic NPs bioconjugates.

Comparing mixing and displacement ventilation in classrooms: pupils' perception and health

Several studies have found that indoor air quality (IAQ) in schools is often poor and may affect the health of the pupils. Building ventilation is a means to reduce pollutants indoors, but different designs should be evaluated for their effectiveness in different environments. In a field experiment performed at four classrooms in one school building, air was supplied either in the mixing or in the displacement mode, and we collected information on exposures, pupils' perception of IAQ and climate, and health symptoms and performed clinical examinations. The room temperature, relative humidity, concentration of CO₂, and cat allergen were measured at the breathing height and were similar during each ventilation mode. The children perceived IAQ were similar in the two ventilation regimes, and there were few differences in symptom reports or clinical parameters. However, the pupils reported more eye symptoms during displacement ventilation.

PRACTICAL IMPLICATIONS

Both mixing and displacement ventilation may be appropriate in school classrooms as long as the overall design, ventilation rates, and maintenance of systems are satisfactory.

Focus on cat allergen (Fel d 1): immunological and aerodynamic characteristics, modality of airway sensitization and avoidance strategies

The increasing frequency of pet ownership (especially cats) in many industrialized countries has raised the level of exposure to the allergens produced by these animals. Moreover, it is likely that modern energy-saving systems and the wide use of upholstered furniture has resulted in closer contact between cats (and their allergens) and humans. Many different methods have been developed to quantify the main cat allergen (Fel d 1) in settled dust and in ambient air. The threshold levels of cat allergen inducing sensitization or triggering respiratory symptoms in sensitized patients have been calculated in settled dust, but airborne amounts of Fel d 1 probably represent a more reliable index of allergen exposure. Noticeably, the amount of Fel d 1 may be relatively high also in confined environments where cats have never been kept. It has been demonstrated that clothes of cat owners are the main source for dispersal of allergens in cat-free environments. This fact may be of relevance, because recent studies have shown that allergic sensitization to cats is more likely to develop in children exposed to moderate levels of this allergen than in children exposed to high amounts of Fel d 1. The ubiquity of cat allergen may justify the common observation that allergen avoidance is often insufficient to reduce the risk of developing allergic sensitization and/or symptom exacerbation in highly susceptible patients. Further efforts are needed to improve the efficacy of Fel d 1 avoidance strategies to try to reduce the risk of allergic sensitization to this allergen.

Immunochromatographic direct on sampling filter test for aeroallergens

An immunochromatographic method for qualitative and quantitative determination of aeroallergens direct on sampling (ADOS) filters has been developed. In this method, a porous polytetrafluoroethylene filter carrying adsorbed allergens is fixed by double-coated adhesive tape to a supporting filter paper matrix. Following addition of antibodies specific for the relevant allergens and washing and staining reagents via a reagent applicator an immunochromatogram is developed resulting in a 5-10 mm wide area of the sample filter covered with blue-violet-stained spots appearing on a faintly pink or white background. The method takes 30 to 90 min, depending on the nominal porosity (1.2-5 microm) and the defined reaction area (5-10 mm) of the sample filter. Application experiments with birch and grass pollen, soluble Bet v 1, Phl p 5 and mould allergens as well as cat allergen carried by airborne dust revealed a limit of detection of a few picograms of allergen as stained spots. The specificity of the new method to evaluate the type of allergen is a function of the selected antibodies. The concentrations of the allergen in an air sample are related to the number and intensity of stained spots.