Performance of a component-based allergen-microarray in the diagnosis of cow's milk and hen's egg allergy.

BACKGROUND: The food challenge test (FCT) is the gold standard for the diagnosis of food allergy. This procedure is time consuming, costly and can induce potentially severe symptoms. An ideal in vitro test should allow to avoid the FCT. Objective To assess the clinical performance of microarray for specific IgE (sIgE) detection in children with challenge-proven/excluded cow's milk (CM) or hen's egg (HE) allergy. METHODS: One-hundred and four children with suspected IgE-mediated hypersensitivity to CM or HE were studied. In all patients, skin prick test, ImmunoCAP, microarray and FCT were performed. RESULTS: The microarray components Bos d 8 for CM (27/58 patients) and Gal d 1 (20/46 patients) and Gal d 2 (24/46) for HE were the most frequently recognized allergens. Using the FCT results as the reference parameter, sIgE to Bos d 8 and Gal d 1 had the highest area under the curves. These were not significantly different from those obtained using the ImmunoCAP. Use of 95% clinical decision points (CDP) for sIgE to Bos d 8 and Gal d 1 resulted in higher negative predictive values (78% and 79%, respectively) than those obtained with the ImmunoCAP (57% and 59%). CONCLUSIONS: Our results show that in children with suspected CM or HE allergy, the microarray has a good ability to predict the FCT results. In a clinical application perspective, the microarray could be used as a second-level assay, if the ImmunoCAP sIgE is <95% CDP. This approach would lead to a decrease in the number of the FCT to be performed, as well as of positive FCTs with a subsequent decrease in severe reaction risk.

Chromosomal evolution in the Brazilian geckos of the genus Gymnodactylus (Squamata, Phyllodactylidae) from the biomes of Cerrado, Caatinga and Atlantic rain forest: evidence of Robertsonian fusion events and supernumerary chromosomes.

Chromosomes of the South American geckos Gymnodactylus amarali and G. geckoides from open and dry areas of the Cerrado and Caatinga biomes in Brazil, respectively, were studied for the first time, after conventional and AgNOR staining, CBG- and RBG-banding, and FISH with telomeric sequences. Comparative analyses between the karyotypes of open areas and the previously studied Atlantic forest species G. darwinii were also performed. The chromosomal polymorphisms detected in populations of G. amarali from the states of Goiás and Tocantins is the result of centric fusions (2n = 38, 39 and 40), suggesting a differentiation from a 2n = 40 ancestral karyotype and the presence of supernumerary chromosomes. The CBG- and RBG-banding patterns of the Bs are described. G. geckoides has 40 chromosomes with gradually decreasing sizes, but it is distinct from the 2n = 40 karyotypes of G. amarali and G. darwinii due to occurrence of pericentric inversions or centromere repositioning. NOR location seems to be a marker for Gymnodactylus, as G. amarali and G. geckoides share a medium-sized subtelocentric NOR-bearing pair, while G. darwinii has NORs at the secondary constriction of the long arm of pair 1. The comparative analyses indicate a non-random nature of the Robertsonian rearrangements in the genus Gymnodactylus.

Occurrence of B chromosomes in lizards: a review.

Although B chromosomes have been reported in many species of plants and animals, few studies have revealed the presence of these extra chromosomes in lizards. B chromosomes of lizards show different morphologies and sizes, from microchromosomes to macrochromosomes, or elements of intermediate size between smaller and larger A chromosomes, and number variability at intra- and inter-individual levels. In most cases, they are late-replicating and show either heterochromatic or no distinctive patterns after C-banding. The great majority of the publications about supernumerary chromosomes in this group have been based on conventional staining analyses, and there is no study designed to address questions related to their composition and structure or origin and evolution.

Chromosomal studies on sphaerodactyl lizards of genera Gonatodes and Coleodactylus (Squamata, Gekkonidae) using differential staining and fragile sites analyses.

The karyotypes of three species of sphaerodactyl gekkonid lizards are described after conventional and differential staining. Karyotypes of Gonatodeshumeralis and G. hasemani are formed by a gradual series of 32 acrocentric chromosomes, similar to those already published for other species of the genus. G. humeralis shows multiple Ag-NORs with intra-individual variability, and positive C-bands located at centromeric and telomeric regions of several chromosome pairs. Coleodactylus amazonicus, the first non-Gonatodes sphaerodactyl studied so far karyologically, exhibits 36 acrocentric/subtelocentric chromosomes and a single pair of Ag- NORs. Fragile sites were detected on two medium-sized chromosome pairs in the karyotype of G. humeralis, most of them obtained in BrdU-treated culture preparations. These sites may represent a putative fission/fusion spot involved in the differentiation of G. humeralis-like 2n = 32 and C. amazonicus-like 2n = 36 karyotypes. Our results, especially on the location of Ag-NORs and the description of fragile sites, are relevant in improving our knowledge about the events of chromosome evolution in this extremely variable and poorly known group of lizards.

Chromosomal polymorphisms due to supernumerary chromosomes and pericentric inversions in the eyelidless microteiid lizard Nothobachia ablephara (Squamata, Gymnophthalmidae).

Cytogenetic studies were performed on eight specimens of the monotypic microteiid lizard Nothobachia ablephara, endemic of the sand dunes of the middle São Francisco river, in the semiarid caatinga, State of Bahia, Brazil. Chromosomes from fibroblast cultures were analysed after conventional, Ag-NOR staining, C-, and replication R- banding. A basic karyotype of 2n = 62, consisting mostly of subtelocentric and acrocentric chromosomes of decreasing size, was found in five specimens. Diploid number variation (2n = 63 and 2n = 64) occurred in two specimens due to the presence of one and two medium-sized subtelocentric supernumerary chromosomes (Bs). The Bs were not clearly distinguishable from the autosomes in Giemsa-stained metaphases and C-banding, but showed late replication after R-banding. Polymorphisms of pairs 1 and 5, observed in three different combinations, including acrocentrics, subtelocentrics, submetacentrics and metacentrics, were interpreted as the result of small pericentric inversions. Variation in the number of Ag-NORs was also reported. A chromosomal mechanism of sex determination of the XX:XY type is present in this species. Our data add more evidence to confirm the remarkable chromosomal variability that has been found in Gymnophthalmidae.

Chromosomal evolution in the Brazilian lizards of genus Leposoma (Squamata, Gymnophthalmidae) from Amazon and Atlantic rain forests: banding patterns and FISH of telomeric sequences.

An extensive karyotype differentiation was found among three species of gymnophthalmid lizard genus Leposoma which occur in the tropical forest areas of Brazil. We examined the chromosomes of the Amazonic species L. guianense (LOU) and L. oswaldoi (LOS) and the Atlantic forest species L. scincoides (LSC) after conventional and differential staining, and FISH of telomeric sequences. Both Amazonic species shared very similar 2n = 44 karyotypes, including 20 biarmed macrochromosomes and 24 microchromosomes (20 M + 24 m). However, the location of Ag-NORs and the amount of constitutive heterochromatin differed in these karyotypes. The Atlantic forest species L. scincoides has a very distinct karyotype with 52 acrocentric and subtelocentric chromosomes of decreasing size. Comparative R-banding analysis revealed complete homeology of the macrochromosomes of LGU and LOS and correspondence of banding patterns between LSC acrocentrics and subtelocentrics and some arms of biarmed LGU and LOS chromosomes. Pair 1 had similar banding patterns in the three species, implying the occurrence of a pericentric inversion. Interstitial telomeric bands (ITBs) detected by FISH at the pericentromeric region of some biarmed LGU and LOS chromosomes could be remnants of chromosomal rearrangements occurred during the differentiation of the karyotypes. Robertsonian rearrangements as well as pericentric inversions events probable were involved in the karyotype evolution of these Amazon and Atlantic forests species of Leposoma.