[Driver Mutations in Acute Myeloid Leukemia with Inversion of Chromosome 16].

Certain subtypes of acute myeloid leukemia occur as a result of the cooperation of several events these are, the formation of fusion genes as a result of chromosomal rearrangements, which leads to the disruption of cell differentiation, and the emergence of mutations that enhance cellular proliferation by activating intracellular signaling pathways. High-throughput sequencing methods reveal characteristic mutation spectra in leukemia associated with different chromosomal disorders. However, the role of mutation events in malignant cell transformation processes remains obscure. We searched for driver mutation events in leukemic cells containing the chimeric CBFB-MYH11 gene, which results from inversion of chromosome 16. Using target enrichment, the coding regions of 84 genes in genomes of 12 children with acute myeloid leukemia with inv(16) were investigated. Somatic mutations have been found in the genes of the proteins of intracellular signaling cascades mediated by receptor tyrosine kinases, such as KIT (41%), NRAS (25%), KRAS (17%), and FLT3 (8.3%). Comparative analysis of samples at the time of diagnosis and during remission was used to assess the role of mutations in the pathogenesis of the disease. Previously undescribed mutations in the KDM6A, NOTCH1, and IDH1 genes, which may be involved in leukemogenesis processes have been identified.

[Mutational Profiling of Pediatric Myeloid Leukemia Subtypes without Clinically Significant Chromosomal Aberrations].

The discovery of novel significant molecular and genetic markers is important for the diagnostics, prognosis, and therapy selection in hematological malignancies. Distinct cytogenetic aberrations leading to the formation of fusion genes are found in more than 40% of pediactric cases of acute myeloid leukemia (AML); however, the tumor cells in approximately 20% of these patients display cytogenetically normal karyotype (NK-AML). Here we present the analysis of the mutational profiles of leukemic cells collected from pediatric AML cases without known clinically significant chromosomal aberrations aimed at identifying AML specific markers. In 34 pediatric cases of different AML types, the coding regions of 26 genes involved in the AML pathogenesis were analyzed by massive parallel sequencing. Sequencing revealed the somatic mutations in genes that are involved in various intracellular signaling pathways, including the CEBPA, ETV, IDH1, JAK2, and NRAS genes. In addition, rare genetic variants were found in CUX1, FLT3, TET2, PTPN11, and NUP98 genes. This data may contribute to the understanding of the mechanisms of malignant cell transformation in the case of leukemogenesis.

[Age-related characteristics of the efficacy of different glucocorticosteroids in the therapy of acute lymphoblastic leukemia].

AIM: To determine predictors for decision-making on a differential approach to choosing glucocorticosteroids (GCS) for children and adolescents with acute lymphoblastic leukemia (ALL). SUBJECTS AND METHODS: The analysis covered 1064 primary patients aged to 1 to 18 years with ALL who had been registered at the clinics of Russia and Belorussia in April 2002 to November 2006. Before induction therapy, the patients were randomized into a dexamethasone (DEXA) 6 mg/m2 group (n=539) and a methylprednisolone (MePRED) 60 mg/m2 one (n=525). RESULTS: The entire group showed no statistically significant differences in survival rates between the patients receiving DEXA or MePRED. However, an analysis of age groups revealed the benefits of DEXA in children younger than 14 years (the event-free survival (EFS) was 76±2 and 71±2%, respectively (p=0.048); the overall survival (OS) was 81±2 and 77±2%, respectively (p=0.046); therapy-induced mortality was 6.4% (DEXA) andl 1.1% (MePRED) (p=0.01 4); the rate of isolated extramedullary relapses was 1.5% (DEXA) and 4.4% (MePRED) (p=0.009). At the same time, EFS and OS in 14-to-18-year-old adolescents were statistically significantly higher than in those who used MePRED (EFS, 65±6 and 52±6%, respectively (p=0.087); OS, 72±6 and 61±6%, respectively; (p=0.l 7). CONCLUSION: The findings suggest that it is possible that the choice of a GCS for ALL therapy must be also based on a patient's age. There is a need for further studies of this matter in prospective randomized multicenter trials in children and adolescents.

[The role of Mac-1 and ICAM-1 molecules in adhesion of cells on fibronogen and its degradation products]. / Uchastie molekul Mac-1 i ICAM-1 v adgezii kletok na fibrinogene i produktakh ego degradatsii.

Monocytic cell adhesion to immobilized fibrinogen and fibrinogen degradation products, and involvement of integrins Mac-1 and immunoglobulin-like ICAM-1 adhesion molecules in these processes were investigated. Fibrinogen cleavage with plasmin down-regulated adhesion of cells with predominant Mac-1 expression; in contrast, the attachment of ICAM-1-expressing was up-regulated. By means of function-blocking anti-Mac-1 and anti-ICAM-1 antibodies, and immobilization of known fibrinogen degradation products, it was shown that Mac-1 molecules mediated cell adhesion predominantly to fibrinogen, and its early degradation products, fragments X and Y, while ICAM-1 participated in cell attachment to X- and Y-fragments, rather than to intact fibrinogen or late degradation products, fragments D and E.

[Increased expression of monocytic cell adhesion molecules and formation of monocyte-thrombocyte aggregates in coronary restenosis]. / Uvelichenie ékspressii monotsitarnykh molekul adgezii i obrazovaniia monotsit-trombotsitarnykh agregatov v krovi pri koronarnom restenoze.

AIM: To examine expression of superficial antigens by blood monocytes and granulocytes as well as the number of leukocyte-platelet complexes forming in in vitro activation in patients subjected to coronary angioplasty; to analyse changes in these parameters in coronary restenosis. MATERIAL AND METHODS: Membrane expression of leukocytic antigens and the number of leukocyte-platelet complexes after activation in the whole blood were measured by direct immunofluorescence and flow cytometry in 24 patients who have undergone stenting of coronary arteries. 14 of them had angiographically confirmed restenosis. RESULTS: The tests discovered high expression of integrins Mac-1 and VLA-4 by monocytes and elevated relative number of monocyte-platelet complexes in patients with restenosis vs those free of stenosis (1425 +/- 76 and 1195 +/- 71 r.u. for Mac-1, 87 +/- 7 and 65 +/- 6 r.u. for VLA-4, 47 +/- 4 and 29 +/- 3%, respectively, for monocyte-platelet complexes; p < 0.05 for all the indices). CONCLUSION: Coronary restenosis may result from elevated expression of adhesion molecules by monocytes manifest in activation of the cells in vitro.

[Evaluation of the pool of mature circulating lymphocytes in children with acute leukemia]. / Otsenka pula zrelykh tsirkuliruiushchikh limfotsitov pri ostrom leikoze u detei.

In children with acute leukemia, at the initial period of the disease the absolute number of T-lymphocytes is within the normal range, when the values of the total number of leucocytes is low or normal, and it is increased in cases with high initial leucocytosis. Dissociation of T-cell marker signs in the lymphocyte population has been revealed that evidences the presence of functionally defective T-cells in the circulation. The value of the relative content of E+ T-cells over 10% in the circulation is of prognostic significance.

[Automatic erythrocytometry in a robotized microscope MEKOS-Ts1]. / Avtomaticheskaia éritrotsitometriia v robotizirovannom mikroskope MEKOS-Ts1.

Measurements of the form and size of erythrocytes are needed in the diagnosis of a number of diseases. However, such measurements, if made manually, are a labor-consuming and often inaccurate method, which ensures the determination of a very limited number of parameters. Hardware/software unit MEKOS-C1 enables an automated examination of blood smear, thus speeding up significantly the analysis and ensuring a more complete and accurate information. The possibilities of unit MEKOS-C1 were evaluated for the diagnosis of ovalocytosis. Blood smears of 19 patients from the Russian Pediatric Clinical Hospital, including 8 patients with inherited ovalocytosis, 1 patient with spherocytic ovalocytosis and 10 patients without the disease, were made use of Erythrocytes were isolated in the images of preparations and the contour of each cell was approximated by ellipse. The ratio between ellipse semi-axes served as a measure of erythrocytes' ovality. The mean ratio of semi-axes (RS) and the index of ovalocytosis (IO), i.e. a ratio of the mean maximum diameter to the mean minimal diameter, were calculated for each smear. Manual IO measurements were made in all preparations as a control. Since an additional error can enter the result because of the irregular smear nature and impossibility to standardize completely the technology of smear preparation, the data, obtained from two different smear parts and from parallel preparations, were compared. The reliability, stability and good reproducibility of the automated measurement results were demonstrated. The mean erythrocytes' RS correlated well with IO, obtained manually, and did not virtually differ from RS, measured in the automated manner. The mean RS value of erythrocytes, obtained from patients with inherited ovalocytosis, significantly differed from the control values, which is indicative of a high information density of the discussed parameter. Therefore, RS, when measured automatically, is a reliable and convenient characteristic of erythrocytes' ovality under the conditions of using the ordinary technique of smear preparation.

[State of nucleolus-forming regions in bone marrow and blood cells in acute leukemia in children]. / Sostoianie iadryshkoobrazuiushchikh raionov v kletkakh kostnogo mozga i krovi pri ostromm leikoze u detei.

The study of the activity of nucleolus-forming areas in bone marrow and blood cells in 67 children with acute leukemia has shown the parameter variability depending on histogenetic affiliation, differentiation degree and on the proliferative activity of the cells.

[Results of treatment of acute leukemia in children using intensive therapy programs]. / Rezul'taty lecheniia ostrykh leikozov u detei s ispol'zovaniem programm intensivnoi terapii.

The authors report the results of the treatment according to the programs BFM-ALL-90 and BFM-AML-83 and 87. A total of 110 children with acute lymphoblastic leukemia (ALL) and 35 with acute myeloblastic leukemia (AML) were treated with remission rate 94.5% and 74.5%, respectively. Under programmed treatment of ALL the recurrences occurred in 12.2% against 46% of the cases in nonprogrammed treatment. 2-year survival made up 75% and 47.3%, respectively. Among AML cases there were frequently prognostically unfavorable ones and patients with neuroleukemia this dictating the necessity of the treatment intensification and irradiation of the skull in AML. Improvement of adjuvant therapy is a must in advance of acute leukemia treatment.