Molecular-biological approaches to studying gene expression during regeneration

This paper constitutes a review of the methodical approaches allowing analysis of the mechanisms underlying development and differentiation. Progress in investigation of the mechanisms underlying embryogenesis is related to the discovery of genic families in the Drosophila genome, which are responsible for different periods of embryogenesis. The true revolution in studies of developmental mechanisms began with the application of molecular-genetic methods for analysis of Drosophila mutant lines. The clarification and analysis of the genes controlling regeneration is one of the most effective paths toward an understanding of the mechanisms underlying regeneration. No mutations affecting regeneration are, and the development of alternative (i.e., not based on mutation analysis) methods of discovery of the genes controlling regeneration is necessary for investigation of the genetic mechanisms of regeneration. The advantages and drawbacks of the two main approaches for discovery of the genes controlling regeneration are considered. The first approach is based on the production of a bank of sequences expressed in the regenerating structures and subsequent screening of the bank by the known probes. This approach also involves analysis of the structure, function, and expression pattern of the obtained homologs. The second approach is based on subtractive hybridization, which allows identification of the genes specifically expressed in the regenerating structures. This approach was made it possible to identify, for the first time, new genes specifically expressed during lens and retina regeneration in amphibians.     

The application of intraarterial chemotherapy for the treatment of osteogenic sarcoma in children

In 55 patients of infantile age with osteogenic sarcoma the method of combined intravenous and intraarterial chemotherapy, using cisplatinum, doxorubicin and methatrexate was applied. For a period of two years among the patients survived 55.4% were free of recurrence of the disease.     

The primary zone in the combustion of solid propellants containing catalysts

Using a scanning electron microscope and an x-ray microprobe analyzer, we investigated the structure and composition of the combustion surface of the N propellant containing catalysts (PbO₂, CuO, PbO₂+CuO) which was extinguished at various pressures. Based on the obtained results, the heat-transfer coefficient was calculated for the layer above the catalyzed propellant combustion surface and found to be greater than that of the gas by factors ranging from 1.5 to 15. The calculation of the C-phase heat balance for the N propellant with additives showed that the rise in the combustion rate is caused by the increased quantity of heat entering into the C-phase from the zone above the combustion surface. Thus, the driving stage in the combustion of catalyzed propellants is the zone above the combustion surface and not the C-phase reaction layer, as in the case of the propellants without any catalysts.D. I. Mendeleev Russian Chemical Methodology University, 125190 Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 2, pp. 32–40, March–April, 1995.     

Changes in the chemotherapy sensitivity of leukemia L1210 cells during the development of diazan resistance

L 1210 leukemia strain resistant to diazan (L 1210/D1) was studied for its drug sensitivity in comparison with the parent strain. The resistant strain exhibited significantly higher sensitivity to nine drugs: dopan, sarcolysine, apirazidin, cyclophosphane, 6-mercaptopurine, thiophosphamide, rubomycin, vinblastine and vincristine. L 1210/D1 gained cross resistance to four drugs: 1-(2-chloroethyl)-3-(2, 6-dioxy-3-piperidyl)-1-nitrosourea, methotrexate, 5-fluorouracil and ftorafur. The resistant strain sensitivity remained unchanged (in comparison with the parent strain) to seven drugs: degranol, prospidin, nitrosomethylurea, chlorozotocin, deazauridine, bleomycin and L-asparaginase (crasnitine).     

The clinical significance of MDR-1 gene expression in the hemopoietic cells of patients with acute leukemias in different phases of the disease

AIM: Analysis of cytostatic therapy effects on expression of gene MDR-1 in hemopoietic cells of patients with acute leukemia (AL) in complete clinicohematological remission (CCHR). MATERIALS AND METHODS: The study included 48 AL patients. 27 of them were untreated, 25 were resistant to or had recurrent AL. 4 patients were followed up. Bone marrow mononuclear fraction was investigated. Expression of MDR-1 gene in the cells was evaluated at hybridization. RESULTS: High expression of MDR-1 gene occurred in leukemic blast cells either upon achievement of CCHR or at least 6 months after its onset. When using schemes of chemotherapy containing two potential inductors of gene MDR-1, expression of this gene was registered significantly more frequently than in using schemes based on one inducing drug (p < 0.05). Frequency of occurrence of enhanced expression of gene MDR-1 in leukemic blasts significantly correlated with frequency of CCHR (p < 0.05). Correlation between occurrence of the gene's expression in normal hemopoietic cells in CCHR and occurrence of early AL recurrences was not found. CONCLUSION: The findings may facilitate design of new AL treatment programs.