A hagyományos citogenetika és a FISH egymást jól kiegészítő vizsgálatok gyermekkori akut limfoid leukémiában

Primary genetic abnormalities of leukemia cells have important prognostic significance in childhood acute leukemia. In the last two years 30 newly diagnosed or recurrent childhood ALL bone marrow samples were analyzed for chromosomal abnormalities with conventional G-banding and interphase-fluorescence in situ hybridization (I-FISH) using probes to detect BCR/ABL fusions, cryptic TEL/AML1 and MLL rearrangements and p16(9p21) tumor suppressor gene deletions. G-banded karyotype analysis found clonal chromosomal aberrations in 50% of cases. With the use of complementary I-FISH techniques, ALL-specific structural and numerical changes could be identified in 70% of the patients. Nine cases (30%) had subtle chromosomal aberrations with prognostic importance that had not been detected in G-banded analysis. Conventional G-banding yielded additional information (rare and complex structural aberrations) in 19% of patients. The most common aberration (30%) was AML1 copy number increase present in G-banded hyperdiploid karyotype as a chromosome 21 tetrasomy in the majority of cases; one case displayed 5-6 copies and in another case amplification of AML1 gene on der(21) was combined with TEL/AML1 fusion of the homologue AML1 gene and deletion of the remaining TEL allele. High hiperdiploidy was detected in 6 cases, in one patient with normal G-banding karyotype. TEL/AML1 fusion signals were identified in four patients. Deletion of p16 locus was found in eight cases (23%), of which only two had cytogenetically visible rearrangements. G-banding in combination with I-FISH has produced major improvements in the sensitivity and accuracy of cytogenetic analysis of ALL patients and this method helps to achieve a more precise identification of different risk categories in order to choose the optimal treatment

Adaptation duration affects the spatial selectivity of facial aftereffects

AbstractAdaptation processes in human early visual cortical areas are sensitive to the exposure time of the adaptor stimulus. Here we investigated the effect of adaptation duration at the higher, shape-specific stages of visual processing using facial adaptation. It was found that long-term (5s) adaptation evokes facial aftereffects consisting of a position invariant as well as a position-specific component. As a result of adaptation to a female face, test faces were judged more masculine when they were displayed in the same location as the female adaptor face, as compared to that when they were presented in the opposite visual hemifield. However, aftereffects evoked by short-term (500ms) adaptation were found to be entirely position invariant. In accordance with these behavioral results, we found that the adaptation effects, measured on the amplitude of the N170 ERP component consisted of a position-specific component only after long-term, but not after short-term adaptation conditions. These results suggest that both short and long exposure to a face stimulus leads to adaptation of position invariant face-selective processes, whereas adaptation of position-specific neural mechanisms of face processing requires long-term adaptation. Our findings imply that manipulating adaptation duration provides an opportunity to specifically adapt different neural processes of shape-specific coding and to investigate their stimulus selectivity