Comparison of pivot profile© to frequency of attribute citation: Analysis of complex products with trained assessors

Pivot© profile (PP), a method which compares samples to a reference (pivot), has shown profiling potential for complex matrices. However, various aspects require further investigation. This study’s aim was to compare PP to frequency of attribute citation (FC) considering individual judges’ data and sample set complexity. A trained panel analysed three wine sets with different within-set product similarity levels. The stability of the PP sensory space was tested by changing the pivot. PP and FC results were compared using RV coefficients. Confidence ellipses on correspondence analysis (CA) plots were constructed to consider individual judges’ data. CA plots constructed from different pivot PP data sets, were less similar to each other, than to CA plots of FC data, for the set with medium and the set with high within-set variation. The most profound differences were observed for the set with the high within-set variation. PP configurations of the set with low within-set variation, were more similar to each other than to FC configurations. Higher explained variance was obtained with PP than FC, but confidence ellipses overlapped more frequently indicating fewer significant differences between samples. PP and FC data were comparable for the set with medium within-set variation. From this study’s results PP is recommended for wine profiling if medium within-set variation between samples exist but not when sample sets with low or high within-set variation are profiled. PP is recommended over FC for comparative studies where a reference sample is required for example during benchmarking or for aging and shelf-life studies.acceptedVersio

Identification of proliferating cells in chicken embryos using 5-bromo- 2'-deoxyuridine immunohistochemical detection

Chicken embryos were incubated with BrdU, embedded in plastic resin, sectioned and screened immunohistochemically to identify proliferating cells in the neural tube and somites. Fixation in 4% paraformaldehyde for 1 h was essential for detecting specific colorimetric signals of BrdU incorporation into cells during the S phase of the cell cycle. Transverse sections of the neural tube showed that the nuclei of proliferating cells (BrdU positive) had a uniform and centralized distribution, whereas unstained nuclei were found only along the extremities of the neural tube. Transverse sections of differentiated somites showed proliferating cells in the scleratome and dermatome. However, no incorporation of BrdU was observed in myotomic cells, which give rise to axial skeletal muscle. In spite of their proximity, the dermatome and myotome showed marked differences in cell proliferation. The excellent preservation of morphological characteristics in the embryonic tissues facilitated identification of variations in BrdU incorporation.<br>Embriões de frango foram incubados na presença de BrdU e montados em resina plástica. A detecção de células em proliferação nos somitos e tubo neural foi feita através de anticorpos contra BrdU. Um ponto essencial para a otimização do método foi a fixação dos embriões por apenas uma hora em paraformaldeído a 4%. Análise de cortes transversais revelou que no tubo neural os núcleos marcados se posicionavam na região central. Cortes transversais em somitos diferenciados revelaram a presença de células em proliferação no dermátomo e esclerótomo, no entanto não foi observado nenhum sinal no miótomo. A metodologia aqui apresentada permitiu identificar com clareza e boa resolução as células em proliferação presentes em tecidos embrionários