The development of adaptive skills in young people with Down syndrome.

BACKGROUND: To help children with Down syndrome reach optimum levels of adaptive behaviour, caretakers need to know how and to what extent children with Down syndrome acquire adaptive skills. METHOD: The adaptive levels of motor, daily living, communicative and social behavioural skills were determined in a group of 984 Dutch children with Down syndrome, aged between 0 and 12 years, and compared with the adaptive levels of typically developing children using a Dutch version of the Vineland Screener. RESULTS: Children with Down syndrome acquire their adaptive skills at a slower pace and reach their ceiling scores at about the age of 12 years, at a substantially lower level than a reference group of typically developing children. CONCLUSIONS: Down children seem to acquire skills in a similar sequence and according to a similar trajectory. Development of adaptive skills varies greatly between participants with Down syndrome. For that reason, cohort studies on the development of individuals with Down syndrome over a prolonged period of time are needed.

Concentrations of undeclared allergens in food products can reach levels that are relevant for public health.

Food products can become contaminated with food allergens due to cross-contact. Precautionary 'may contain' labelling may alert to the possible presence of an allergen, but guidance for such labelling is lacking. As a result, allergy information on the packaging may not be reliable and allergic consumers might be at risk of allergic reactions after consuming unlabelled, but indeed contaminated, products. Recently, a cow's milk protein allergic patient experienced a severe allergic reaction to a dark chocolate product containing undeclared milk proteins. This case induced the authors to investigate to what extent allergen concentrations of unlabelled products reach levels that are of public health relevance. The concentrations of milk proteins in the complaint sample and a collection of products of other batches and brands purchased from different stores were analysed. Together with appropriate threshold and food consumption data, the risks of allergic reactions and the severity of these reactions within the adult milk-allergic population were determined using probabilistic risk assessment techniques. The results show that milk protein concentrations in unlabelled products reach levels that may elicit allergic reactions in up to 68% of the adult allergic consumers. Therefore, concentrations of allergens in unlabelled products could reach levels that are of public health relevance. Application of probabilistic risk assessment can be an aid in revealing the public health consequences of undeclared allergens in food, in risk management decision-making and developing guidance in terms of risk-based concentration limits for precautionary labelling.

Foods with a high fat quality are essential for healthy diets.

Fat is generally a highly valued element of the diet to provide energy, palatability to dry foods or to serve as a cooking medium. However, some foods rich in fat have a low fat quality with respect to nutrition, i.e., a relative high content of saturated (SFA) as compared to unsaturated fatty acids, whereas others have a more desirable fat quality, i.e., a relative high content of unsaturated fatty acids as compared to SFA. High-fat dairy products and fatty meats are examples of foods with low fat quality, whereas vegetable oils (tropical oils such as palm and coconut oil excluded) are products with a generally high fat quality. The aim of this paper is to explore the nutritional impact of products made of vegetable oils, e.g. margarines and dressings, and how they can be designed to contribute to good health. Since their first industrial production, the food industry has endeavored to improve products like margarines, including their nutritional characteristics. With evolving nutrition science, margarines and cooking products, and to a lesser extent dressings, have been adapted to contain less trans fatty acids (TFA), less SFA and more essential (polyunsaturated, PUFA) fatty acids. This has been possible by using careful fat and oil selection and modification processes. By blending vegetable oils rich in the essential PUFAs alpha-linolenic acid (vegetable omega-3) or linoleic acid (omega-6), margarines and dressings with both essential fatty acids present in significant quantities can be realized. In addition, full hydrogenation and fat rearrangement have enabled the production of cost-effective margarines virtually devoid of TFA and low in SFA. Dietary surveys indicate that vegetable oils, soft margarines and dressings are indeed often important sources of essential fatty acids in people's diets, whilst providing negligible amounts of TFA and contributing modestly to SFA intakes. Based on empirical and epidemiological data, the public health benefit of switching from products with a low fat quality to products with a high fat quality can be predicted. For example, switching from butter or palm oil to a soft margarine shows a substantial improvement in the nutritional quality of the diet. These simple, practical dietary adaptations can be expected to contribute to the healthy growth and development of children and to reduce the burden of cardiovascular disease.

The ComFor: an instrument for the indication of augmentative communication in people with autism and intellectual disability.

BACKGROUND: The ComFor (Forerunners in Communication) is an instrument to explore underlying competence for augmentative communication. More specifically, it measures perception and sense-making of non-transient forms of communication at the levels of presentation and representation. The target group consists primarily of individuals with autism and intellectual disability (ID) without or with only limited verbal communication. The ComFor is suitable for children and adults with a developmental level between 12 and 60 months. This paper describes the theoretical framework and structure of the ComFor, the results of a study on its psychometric properties and its clinical uses. METHOD: The ComFor was tested on a sample of 623 children and adults from the Netherlands and Flanders: a group with autism and ID (n = 310); a group with ID without autism (n = 174); and a control group of typically developing children (n = 139). RESULTS: The data generally support the reliability and validity of the ComFor. Internal consistency, inter-rater and test-retest reliability were found to be good. Construct validity (internal structure, convergent and divergent patterns) was established in different ways. The criterion-related validity has yet to be established, as predictive data are not available at the moment. CONCLUSION: Taken together, the results indicate that the ComFor is a promising instrument to explore underlying competence for augmentative communication. Areas for future research are outlined and the clinical relevance is discussed.

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.

Differential Expression of Lipoxygenase Isoenzymes in Embryos of Germinating Barley.

Expression of lipoxygenase was studied in barley (Hordeum distichum L.) embryos during germination. Total lipoxygenase activity was high in quiescent grains, dropped during the 1st d of germination, and subsequently increased to a level similar to that in quiescent grains. The contribution of two isoenzymes, lipoxygenases 1 (LOX-1) and 2 (LOX-2), was studied at the activity, protein, and mRNA levels. Activity ratios of the two isoforms were determined via the ratio of 9- and 13-hydroperoxides, which are formed from linoleic acid. Isoenzyme protein levels were determined using specific monoclonal antibodies. mRNA levels were studied using the specific cDNA probes LoxA and LoxC, which correspond to LOX-1 and LOX-2, respectively. The major difference in temporal expression of LOX-1 and LOX-2 was observed in quiescent grains. At this stage, LOX-1 contributed almost exclusively to total lipoxygenase activity. LOX-2 activity rapidly increased until d 2 of germination. From this time point onward, LOX-1 and LOX-2 showed similar patterns at both activity and protein levels. The tissue distribution of the two isoenzymes in the germinating embryo was closely similar, with the highest expression levels in leaves and roots. The levels of LOX-1 and LOX-2 may be regulated mainly pretranslationally, as suggested by the similarity of the protein and mRNA patterns corresponding to the two isoforms.

A comparison between the handicaps behaviour and skills schedule and the psychoeducational profile.

Comparisons were made of developmental scores (administered with the Psychoeducational Profile [PEP] and the Handicaps Behaviour and Skills Schedule [HBS] for a group of 72 children ages 23 to 148 months. All children had been referred to the Centre of Autism in Leiden, the Netherlands. This Centre is a collaboration between the University clinic of special education and the regional health service. Forty-five children were diagnosed as autistic and 27 as nonautistic but suffering from another disorder. In this study, the correlation between the two instruments is higher than expected, in particular for the group of autistic children (.83). The internal consistency of the subscales of the PEP and the HBS are overall very satisfactory. The Cronbach's alphas of the PEP scales vary from .79 to .96 for the total group and from .77 to .95 for the autistic group. The alphas for the HBS vary from .74 to .92 for the total group and from .20 to .87 for the autistic group, there is one alpha at .20, the rest are .60 or higher.

The irrelevance of IQ to the definition of learning disabilities: some empirical evidence.

The relevance of IQ to the definition of learning disabilities is a much-debated issue. In this article, the effect of not using IQ in the identification of children with reading disabilities is demonstrated. Two classification procedures, differing in their use of IQ, are compared. The first conclusion is that abandoning IQ in classification has a very limited impact on the number of children identified as reading disordered. Our data demonstrate that, if IQ is used, more high IQ children are classified. Another finding pertains to the effect of a restriction of IQ range. The number of children classified as reading disordered is a function of the IQ range.

High yields of specific hybridomas obtained by electrofusion of murine lymphocytes immunized in vivo or in vitro.

We have studied the use of electrofusion to obtain hybridomas producing antigen-specific antibodies after immunization of murine lymphocytes in vitro. Under optimal conditions fusion frequencies of the order of magnitude of 10(-3) were obtained, which is approximately 80-fold higher than the mean value obtained with fusion induced by polyethylene glycol. The number of antigen-specific hybridomas was also increased in a comparable way. The high yields of specific hybridomas observed with electrofusion were independent of the immunization procedure, the antigen or the hapten of interest, or the sources of the lymphocytes. The data presented in this paper indicate that electrofusion may be an extremely attractive alternative method for immortalization of human lymphocytes following immunization in vitro.

Optimal conditions for the generation of monoclonal antibodies using primary immunisation of mouse splenocytes in vitro under serum-free conditions.

We have further optimised the serum-free in vitro immunisation system described by Ossendorp et al. (J. Immunol. Methods 91, 257, 1986) for the generation of hybridomas secreting specific antibodies. Thyroglobulin and the hapten 2-phenyl-5-oxazolone coupled to chicken serum albumin were used as antigens. For an optimal outgrowth of antigen-specific B cells the presence of T cells, thymocyte-conditioned medium and antigen are required. The addition of supernatant from EL-4 cells (stimulated by phorbolmyristate acetate) inhibits the outgrowth of antigen-specific B cells. Using six-well plates with a surface area of 10 cm2 per well, an optimal IgM response was obtained when 10(7) splenocytes in a total volume of 2 ml/well were cultured for 3 days in the presence of antigen and thymocyte-conditioned medium. Increasing the concentration of cells whilst maintaining a constant surface area resulted in a decreased response.

Requirements for the generation of memory B cells in vivo and their subsequent activation in vitro for the production of antigen-specific hybridomas.

We have studied the conditions required for the activation in vitro of memory B cells generated in vivo. BALB/c mice were immunised by a single injection of antigen emulsified in Freund's complete adjuvant. Splenocytes were isolated after different time intervals and cultured in a serum-free medium in the presence of antigen and thymocyte-conditioned medium. After 3 days the splenocytes were fused with myeloma cells. A minimum time interval of more than 2 weeks between priming in vivo and stimulation in vitro was required in order to obtain antigen-specific IgG-secreting hybridomas. After a time interval of 4 weeks or longer most of the antigen-specific hybridomas secreted IgGs. During stimulation in vitro the presence of antigen and of T cells was found to be essential for obtaining an antigen-specific IgG response. The addition of thymocyte-conditioned medium enhanced the IgG response.

Relation between lipid polymorphism and transbilayer movement of lipids in rat liver microsomes.

We have studied the effects of trinitrophenylation on the transbilayer movement of phosphatidylcholine and the macroscopic lipid structure in rat liver microsomal membranes. The transbilayer movement of phosphatidylcholine was investigated using the PC-specific transfer protein. 31P-NMR was employed to monitor the phospholipid organization in intact microsomal vesicles. The results indicate that modification of microsomes with trinitrobenzenesulfonic acid enhances the transbilayer movement of phosphatidylcholine at 4 degrees C. Furthermore, phosphatidylethanolamine headgroup trinitrophenylation in microsomes increases the isotropic component in the 31P-NMR spectra even at 4 degrees C, possibly representing the appearance of intermediate non-bilayer lipid structures. The observed parallel between these data suggests that phosphatidylethanolamine molecules in the microsomal membrane, probably in combination with a protein component, are able to destabilize the bilayer organization, thereby facilitating the transmembrane movement of phospholipids.

Dolichyl phosphate induces non-bilayer structures, vesicle fusion and transbilayer movement of lipids: a model membrane study.

The effect of dolichol and dolichyl phosphate on fusion between large unilamellar vesicles comprised of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) was studied using a fluorescence resonance energy transfer assay. The influence of dolichyl phosphate on the transbilayer movement of DOPC in multilamellar vesicles (MLV) and large unilamellar vesicles (LUV) composed of DOPC and DOPE (1:2) was investigated by using the phosphatidylcholine-specific transfer protein. 31P-NMR and freeze-fracture electron microscopy were employed to study the macroscopic organization of DOPC and DOPE containing model membranes in the absence or presence of dolichyl phosphate. The results indicate that both dolichol and dolichyl phosphate enhance vesicle fusion in a comparable and concentration-dependent way; the amount of exchangeable PC from MLVs is increased by dolichyl phosphate, probably as a result of fusion processes; dolichyl phosphate destabilizes the bilayer organization in MLVs comprised of DOPE and DOPC, resulting in the formation of hexagonal (HII) phase and 'lipidic' particles.

Influence of phospholipid peroxidation on the phase behavior of phosphatidylcholine and phosphatidylethanolamine in aqueous dispersions.

The influence of oxygen-induced phospholipid peroxidation on the phase behavior of aqueous dispersions of both egg phosphatidylcholine (egg-PC) and egg phosphatidylethanolamine (egg-PE) has been investigated. Phospholipid peroxidation was followed via malondialdehyde formation and analyses of acyl chain compositions. 13C nuclear magnetic resonance spectroscopy (NMR) and the amino-indicating probe trinitrobenzenesulfonic acid were used to study the effect of peroxidation on the chemical structure of hydrated egg-PE. The macroscopic organization of the phospholipids was monitored by 31P NMR and small-angle X-ray diffraction. Differential scanning calorimetry was employed to study the influence of peroxidation on the thermotropic behavior of egg-PE. The results show that egg-PE is more sensitive to the effects of peroxidation than egg-PC. In the latter, no changes in the macromolecular organization were observed. However, peroxidation strongly influenced the polymorphic phase behavior of PE. Initial peroxidation stabilized hydrated egg-PE in a lamellar system up to 70 degrees C, presumably by modification of the head group. Such modifications were confirmed by 13C NMR experiments, which indicated the formation of Schiff bases between PE head groups and aldehydes. Furthermore, quantitative analyses of trinitrobenzenesulfonic acid reactable egg-PE and the corresponding fatty acid compositions revealed the presence of cross-links between the ethanolamine head groups, likely involving the bifunctional malondialdehyde. Prolonged peroxidation of egg-PE resulted in a loss of order in the system, possibly by the formation of intermediate nonbilayer structures.

The anion permeability of vesicles reconstituted with intrinsic proteins from the human erythrocyte membrane.

Band 3 protein was reconstituted with lipid vesicles consisting of 94:6 (molar ratio) egg phosphatidylcholine-bovine heart phosphatidylserine in a 2500:1 phospholipid:protein molar ratio by means of a Triton X-100/beads method. The SO2-4 permeability of the resulting vesicles was measured using an influx assay procedure in which the vesicles were sampled and subsequently eluted over Sephadex columns at appropriate time intervals. The accuracy of the assay was greatly increased by using an internal standard in order to correct for vesicle recovery. In agreement with previous work, it could be demonstrated that incorporation of band 3 in the vesicles caused an increase in SO2-4 permeability, which could be (partially) inhibited by high concentrations of DIDS or a competitive anion such as thiocyanate. However, the magnitude of the increased SO2-4 permeability was highly variable, even when vesicles were reconstituted using band 3 isolated from one batch of ghosts. In addition, the SO2-4 influx curves showed complex kinetics. These results are related to the existence of vesicle heterogeneity with respect to protein content and vesicle size as revealed by stractan density gradient centrifugation and freeze-fracture electron microscopy. Band 3 incorporation also increased the L-glucose permeability of the vesicles which could also be inhibited by DIDS. Glycophorin, which has no known transport function, reconstituted with lipid vesicles consisting of 94:6 (molar ratio) egg phosphatidylcholine-bovine heart phosphatidylserine in a 400:1 phospholipid:protein molar ration increased the bilayer permeability towards SO2-4 as well as towards L-glucose. Surprisingly, the SO2-4 permeability in the vesicles could also be inhibited by DIDS and thiocyanate. It is concluded that the use of DIDS and a competitive anion, thiocyanate, in order to prove that band 3 is functionally reconstituted, is highly questionable. The increased SO2-4 and L-glucose permeability of band 3-lipid as well as glycophorin-lipid vesicles and the inhibitory action of DIDS are discussed in the light of the presence of defects at the lipid/protein interface and protein aggregation, which may induce the formation of pores. Since the band 3-lipid vesicles are more permeable for SO2-4 than for L-glucose, in contrast to the glycophorin-containing vesicles, it is suggested that some anion specificity of the increased bilayer permeability in the band 3-lipid vesicles is still preserved.