Reaction coordinates and the transition-vector approximation to the IRC

The appearance of a reaction profile or potential energy surface (PES) associated with the reaction path (defined as the path of steepest descent from the saddle point) depends on the choice of reaction coordinate onto which the intrinsic reaction coordinate is projected. This provides one with the freedom, but also the problem, of choosing the optimal perspective (i.e., the optimal reaction coordinate) for revealing what is essential for understanding the reaction. Here, we address this issue by analyzing a number of different reaction coordinates for the same set of model reactions, namely, prototypical oxidative addition reactions of C-X bonds to palladium. We show how different choices affect the appearance of the PES, and we discuss which qualities make a particular reaction coordinate most suitable for comparing and analyzing the reactions. Furthermore, we show how the transition vector (i.e., the normal mode associated with a negative force constant that leads from the saddle point to the steepest descent paths) can serve as a useful and computationally much more efficient approximation (designated TV-IRC) for full IRC computations, in the decisive region around the transition state. © 2008 American Chemical Society

Clinical improvement after unusual avoidance measures in the home of an atopic dermatitis patient

A 27-year-old female office clerk with widespread atopic dermatitis (AD) since infancy appeared to be highly sensitized and exposed to molds, storage mites, and chicken feathers and moderately sensitized to house-dust mites and grass and birch pollens. Hardly any textiles were present in her home; that is, only 28 m2, which is less than 25% of the Dutch national average. The causal relationship between eczema and molds plus storage mites in this case of AD was strengthened by the positive effect of an unusual, multidisciplinary home-sanitation program involving cleaning of mineral surfaces and ventilation improvement. This home-sanitation program led to a gradual drop of total IgE and clinical symptom scores to 21% and 13%, respectively, of the original values

Clinical improvement after unusual avoidance measures in the home of an atopic dermatitis patient

A 27-year-old female office clerk with widespread atopic dermatitis (AD) since infancy appeared to be highly sensitized and exposed to molds, storage mites, and chicken feathers and moderately sensitized to house-dust mites and grass and birch pollens. Hardly any textiles were present in her home; that is, only 28 m2, which is less than 25% of the Dutch national average. The causal relationship between eczema and molds plus storage mites in this case of AD was strengthened by the positive effect of an unusual, multidisciplinary home-sanitation program involving cleaning of mineral surfaces and ventilation improvement. This home-sanitation program led to a gradual drop of total IgE and clinical symptom scores to 21% and 13%, respectively, of the original values

Comparison of different immunochemical methods for the detection and quantification of hazelnut proteins in food products

Hazelnuts are widely used in the food industry owing to their nutritive value and taste. The amount of hazelnut present in a recipe is usually considered as a mark of quality. On the other hand, contamination of foods that normally do not contain hazelnuts is a threat for patients with a hazelnut allergy. For this reason, the availability of a method for the detection and quantification of hazelnuts in foods would be desirable. The objective of this study was to develop a method for the detection and quantification of minor amounts of hazelnut protein in food products that is potentially applicable for the food industry. Several immunochemical methods, e.g., immunoblotting and enzyme-linked immunosorbent assay (ELISA), were developed with antibodies from both hazelnut-sensitized patient sera and the sera of rabbits hyperimmunized with hazelnut protein. Immunoblotting appeared to be non-specific when the sera of patients were used as a source of antibodies. Using immunopurified antibodies from rabbits immunized with hazelnuts, immunoblotting became specific, but the sensitivity of this method was limited. Inhibition of IgE binding is a generally used test in clinical laboratories to establish contamination with hazelnuts. This approach is sensitive and specific, but not readily accessible for the food industry since patient serum is needed. Similar results in terms of sensitivity and specificity were obtained with a sandwich ELISA constructed with an immunopurified antibody from rabbits sensitized to hazelnuts. No substantial cross-reactivity with other nuts, legumes or other food constituents was observed, and concentrations as low as 5 ng/ml, corresponding to 1 ppm in food products, were detected. In a field test, several consumer products regarded to be free of hazelnuts were shown to contain traces of hazelnut. This sandwich ELISA constructed with immunopurified antibodies from rabbits sensitized with hazelnut protein is a sensitive and specific method to detect and quantify hazelnut and is useful in detecting trace contamination with hazelnut in various consumer products. Since this test does not require serum from patients, it is appropriate for use in the food industry. Copyright (C) 1999 Elsevier Science B.V.Chemicals/CAS: Allergens; Immunoglobulin E, 37341-29-0; Plant Protein

Clinical evaluation of a double-blind dust mite avoidance trial with mite-allergic rhinitic patients

Inheritance and allergen exposure are key factors in the development and the course of atopic allergy, expressed as conjunctivitis, rhinitis, asthma or dermatitis. This study concerns the clinical significance of mite and mite-allergen avoidance measures based on intensive cleaning with acaricide (solidified benzylbenzoate) added (10 dwellings), and without biocidal activity (10 other homes) as a control in a double-blind trial with matched pairs. Twenty subjects with persisting rhinitic complaints were selected. They lived in 20 different dwellings and were ail sensitized to pyroglyphid mites; 12 of them were also sensitized to stored product miles (Acari). Daily symptoms and medication score, guanine and dust exposure, total and mite-specific IgE in serum, eosinophilia in the blood and in the nasal smear, intracutaneous tests with house dust mite and storage mite extracts were compared in both pairs and groups. Acarological data, physiochemical aspects and exposure assessment are discussed in detail elsewhere. Symptom scores dropped significantly, as did the total IgE and exposure to dust and mite products in the acaricidal cleaner treatment group. After 1 year, the daily symptoms median was 47% (P= 0.025), total IgE was 38% (P=0.0049), and exposure to dust and mite products (guanine exposure) was 53% (P= 0.0449) better or lower than in the controls. Intensive cleaning, without acaricidal treatment performed twice a year, resulted in clinical improvement in four out of 10 subjects, of whom none became free of complaints. In the Acarosan treatment group (cleaning+ benzylbenzoate) eight out of 10 subjcets improved, in three cases subjective symptoms disappeared. The conclusion is that mite avoidance in homes can be carried out successfully with a special acaricidal cleaning formulation Acarosan