Radiosensitivity and postirradiation dynamics of granulocyte-macrophage precursors (CFU-DC) in the bone marrow of 2 lines of mice--CBA and BALB/c

CFU-DC in the bone marrow of CBA and BALB/c mice, which are contrast in total radiosensitivity, have close characteristics: D0 is 1.35 and 1.32 Gy, respectively. The proliferation rate of CFU-DC after single exposure to a non-lethal dose of 4 Gy is higher in CBA than in BALB/c mice. The time of doubling the CFU-DC population during the period of exponential growth after irradiation is 40 and 72 h for CBA and BALB/c mice, respectively.     

Radiosensitivity of clonogenic granulocytic macrophage cell precursors in the bone marrow and spleen of tumor-bearing mice

Clonogenic granulocytic macrophagal cells-precursors (CFU-DC) of bone marrow and spleen of intact C57Bl/6 mice and those inoculated subcutaneously with LLC tumor cells do not substantially differ in their radiosensitivity; the concentration of CFU-DC in the spleen markedly varies as tumor grows. The values of Do and extrapolation number n for CFU-DC of the bone marrow are 0.9-1.4 and 1.5-3.0 Gy, and of the spleen, 0.8-1.6 and 1.0-2.6 Gy, respectively.     

Radiosensitivity of mouse bone marrow and spleen CFUdc during gamma-irradiation in different oxygenation conditions

After exposure in vitro and in situ CFUdc of CBA mouse bone marrow and spleen were characterized by the comparable parameters of radiosensitivity and oxygen-dependent modification: the values of D0 for bone marrow and spleen cells were 1.31 and 1.35 Gy (in vitro) and 1.36 and 1.37 Gy (in situ), and the values of the oxygen effect were 2.3 and 2.5, respectively.     

Radiosensitizing and damaging effect of hyperthermia on different biological systems. Radiosensitizing and damaging effect of hyperthermia on cells of mouse La leukemia

When mouse leukosis cell suspensions were subjected to heating the survival rate of animals decreased exponentially with increasing time of heating. It is shown that the increase of temperature for 1 degree C in the range 40-45 degrees C is equivalent to a decrease in the heating time by a factor of approximately 2. The hyperthermia-induced increase in the radiosensitivity of leukosis cells was dependent upon a medium in which heating was performed.     

Dna comets as markers of cells death]

Unstimulated human peripheral blood lymphocytes gradually underwent death during incubation in vitro. According to morphological criteria, the type of death was identified as apoptosis. After immobilization in agarose, lysis, and electrophoresis, these lymphocytes formed DNA comets, which differed in DNA content, tail length, tail moment, and the fraction of DNA migrating in the comet tail. We classified the comets in 3 groups in accordance with the values of these parameters. There was a good correlation between the fraction of apoptotic cells (morphological data) and the fraction of "apoptotic" DNA comets. The results showed that DNA comets may be adequate markers of cell death (including apoptosis). The use of DNA comets as markers of spontaneous death made it possible to reveal an increased level of apoptosis in vitro lymphocytes from patients with systemic lupus erythematosus.     

NO-inhibiting activity of radioprotectors

The effect of radioprotectors of different structure on the syntheses of nitric oxide induced by endotoxin in mice was studied. Using ESR-spectroscopy and spin trap techniques, it was shown that compounds of different chemical structure, such as aminothiols, isothiuronium derivatives, thiazolines, indolylalkylamines and others, suppressed the nitric oxide production in a whole body. The analysis of the relevant literature has confirmed the phenomenon described by the authors: radioprotectors show NO-inhibiting activity.     

The influence of some retarding agents NOS of dihydrothiazine-thiazoline rank on postradiational of recovery endogenous CFU-S-8 of mice

In this work the attempt to estimate a nitric oxide (NO*) role in regulation of the number of pool haemopoietic stem cells at the irradiated mice was made. With this purpose the number of new compounds from dihydrothiazine-thiazoline line was synthesized, their NO-inhibiting activity was investigated in vivo by the method of ESR-spectroscopy of spin trap and their influence on an output endogenous spleen colonies (CFU-S-8) after the total sublethal y-irradiation of mice in a doze of 6 Gy was also investigated. Was shown, that the tested compounds reduced the contents of NO* in a liver tissue of mice which have received an injection of nitric oxide synthesis inductor - lipopolysaccharide, and also increased an output CFU-S-8 forming endogenous colonies in the spleen of the irradiated mice. Received data testify to perceptivity of search radioprotective agents among NO* synthesis inhibitors.     

<i>Streptomyces</i> PRIO41 as plant growth promoter of jalapeño pepper plants and as biocontrol agent of <i>Fusarium</i>

Chili pepper is one of the main crops of economic importance in Mexico, and Fusarium wilting is a disease that limits its production. In addition, the inappropriate use of agrochemicals in farming activities generate environmental and health problems. Therefore, in this study the effectiveness of Streptomyces sp PRIO41 was evaluated as a (1) biocontrol agent of Fusarium spp and (2) plant growth promoter bacteria. Assays of pathogenicity and virulence of Fusarium spp. in jalapeño pepper seeds, and interactions of these pathogens with Streptomyces PRIO41 were evaluated under two nutritional conditions. In the greenhouse, the effectiveness of Streptomyces sp. PRIO41 was determined as a (1) biocontrol of Fusarium, and (2) plant growth promoter of wilt of pepper plants. The results showed that all fungal isolates caused symptoms in pepper seeds and seedlings with different degrees of virulence. Interactions in vitro showed that Streptomyces showed the most effective range of virulence against Fusarium isolates in the poor medium (37.6%-100%), with fungicidal effects in some cases. In the greenhouse, Streptomyces PRIO41 reduced Fusarium wilting up to a 40%, and positively affected all vegetative growth parameters, particularly plant height, leaf area, root length, and leaf and root dry biomasses. This study showed the potential of Streptomyces PRIO41 as a biocontrol agent of Fusarium spp., and as a biofertilizer of pepper plants.