DNA damage response and preleukemic fusion genes induced by ionizing radiation in umbilical cord blood hematopoietic stem cells.

There is clear evidence that ionizing radiation (IR) causes leukemia. For many types of leukemia, the preleukemic fusion genes (PFG), as consequences of DNA damage and chromosomal translocations, occur in hematopoietic stem and progenitor cells (HSPC) in utero and could be detected in umbilical cord blood (UCB) of newborns. However, relatively limited information is available about radiation-induced apoptosis, DNA damage and PFG formation in human HSPC. In this study we revealed that CD34+ HSPC compared to lymphocytes: (i) are extremely radio-resistant showing delayed time kinetics of apoptosis, (ii) accumulate lower level of endogenous DNA damage/early apoptotic γH2AX pan-stained cells, (iii) have higher level of radiation-induced 53BP1 and γH2AX/53BP1 co-localized DNA double stranded breaks, and (iv) after low dose of IR may form very low level of BCR-ABL PFG. Within CD34+ HSPC we identified CD34+CD38+ progenitor cells as a highly apoptosis-resistant population, while CD34+CD38- hematopoietic stem/multipotent progenitor cells (HSC/MPP) as a population very sensitive to radiation-induced apoptosis. Our study provides critical insights into how human HSPC respond to IR in the context of DNA damage, apoptosis and PFG.

Effectiveness of endothelial progenitor cell culture under microgravity for improved angiogenic potential.

Endothelial progenitor cell (EPC) transplantation is beneficial for ischemic diseases such as critical limb ischemia and ischemic heart disease. The scarcity of functional EPCs in adults is a limiting factor for EPC transplantation therapy. The quality and quantity culture (QQc) system is an effective ex vivo method for enhancing the number and angiogenic potential of EPCs. Further, microgravity environments have been shown to enhance the functional potential of stem cells. We therefore hypothesized that cells cultured with QQc under microgravity may have enhanced functionality. We cultured human peripheral blood mononuclear cells using QQc under normal (E), microgravity (MG), or microgravity followed by normal (ME) conditions and found that ME resulted in the most significant increase in CD34+ and double positive Dil-Ac-LDL-FITC-Ulex-Lectin cells, both EPC markers. Furthermore, angiogenic potential was determined by an EPC-colony forming assay. While numbers of primitive EPC-colony forming units (pEPC-CFU) did not change, numbers of definitive EPC-CFU colonies increased most under ME conditions. Gene-expression profiling also identified increases in angiogenic factors, including vascular endothelial growth factor, under MG and ME conditions. Thus, QQc along with ME conditions could be an efficient system for significantly enhancing the number and angiogenic potential of EPCs.

Effects of mobile phone exposure on biochemical parameters of cord blood: A preliminary study.

The purpose of this study is to investigate foetal impact of radiofrequencies (RFs) emitted from mobile phones in postnatal cord blood. The study carried on 149 pregnant women divided into four groups such as nonusers of mobile phone (n: 37; control group), 2-15 min/d (n: 39; group 1), 15-60 min/d (n: 37; group 2) and participants using mobile phone for more than 60 min/d (n: 36; group 3). Cord blood of the infants was taken in all groups for biochemical analyses immediately after birth. The results of the study showed that the biggest foetal impact was observed in the third study group which was pregnant exposed RFRs (RF radiation) more than 1 h/d (1 hour per day). AST (aspartat aminotransferaz), ALT (alanine aminotransferase), LDH (lactate dehydrogenase), CK (creatine kinase), CK-MB (creatine kinase-miyocardial band), CRP (c-reactive protein), PCT (procalcitonin), TnT (troponin T), uric acid and lactate levels of third group were found higher than the other groups (p < 0.001). However, Mean platelet volume values of third group were found lower than the other groups (p < 0.001). Finally, this is the first human study which was performed on pregnant and infants because there is no previous work in this area. However, the results of this study revealed that long-term RFR exposure of pregnant may result in some biochemical changes in the infants. Therefore, our suggestion to pregnant is to avoid from RFR exposure emitted from mobile phones at least during pregnancy.

MiRNA-142-3p increases radiosensitivity in human umbilical cord blood mononuclear cells by inhibiting the expression of CD133.

This study is to explore the molecular regulation mechanism of CD133 which is associated with malignancy and poor prognosis of blood system diseases. CD133+HUCB-MNC (human umbilical cord blood mononuclear cells) and CD133-HUCB-MNC were isolated and amplificated from umbilical cord blood, and then were exposed to different doses of radiation and subjected to a clonogenic assay. CCK-8 kit was used to detect cell viability, Annexin V-FITC/PI cell apoptosis detection kit was used for the detection of apoptotic cells and the BrdU assay was performed by flow cytometry. The expression of protein was analyzed by western blots. The profile of miRNA expression in response to radiation was examined and validated by RT-PCR. miR-142-3p inhibited the expression of CD133 in umbilical cord blood mononuclear cells to increase radiosensitivity. CD133+HUCB-MNC cells were more radioresistant compared with CD133-HUCB-MNC cells. CD133+HUCB-MNC cells showed higher p-AKT and p-ERK levels after radiation. And miR-142-3p acted on 3'UTR of CD133 mRNA to inhibit CD133 expression. Moreover, miRNA-142-3p mimic increased radiosensitivity in CD133+HUCB-MNC cells. Our results elucidated a novel regulation pathway in hematopoietic stem cells and suggested a potential therapeutic approach for blood system diseases therapy.

Concentraciones plasmáticas de 25-OH-Vitamina D en sangre de cordón umbilical tras los meses de verano / Plasma 25-OH Vitamin C concentrations in cord blood after summer months, Spain

Fundamentos: Los niveles de vitamina D (25(OH)D) del recién nacido dependen de los depósitos maternos. En los últimos años se han publicado estudios que muestran una elevada prevalencia de deficiencia de vitamina D en mujeres embarazadas, viéndose en algunos diferencias estacionales. El objetivo del presente estudio fue determinar los valores de 25(OH)D en sangre de cordón después de los meses de verano y determinar su relación con diferentes variables. Métodos: Se seleccionó a 103 mujeres en el momento del parto durante los meses de octubre, noviembre y principios de diciembre, cuyas gestaciones tuvieron lugar durante meses de máxima exposición solar. Se determinaron las concentraciones de 25(OH)D en sangre de cordón umbilical y se recogieron datos perinatales, ingesta de vitamina D y calcio y exposición solar mediante cuestionario. Se realizó el análisis estadístico mediante el programa SPSS. Las comparaciones se realizaron mediante test de Kruskal- Wallis y U de Mann-Whitney, aplicando corrección por comparaciones múltiples de Bonferroni. Se consideró estadísticamente significativa una p<0,05 y de 0,0083 para comparaciones múltiples. Resultados: El valor medio de 25(OH)D en sangre de cordón fue 12,36±7,2 ng/ml. El 83,4% de las mujeres presentaron niveles deficitarios. Se observó una correlación estadísticamente significativa entre los niveles bajos de vitamina D y la baja ingesta de vitamina D (coeficiente de correlación 0,29); la etnia, presentando el valor más alto la etnia caucásica (17,9 ± 5,83 ng/ml) y el menor la etnia indopakistaní (6,68 ± 4,2 ng/ml); el uso de indumentaria tradicional (5,64 ± 3,09 ng/ml); la baja exposición solar y el fototipo cutáneo oscuro con un coeficiente de correlación de 0,67 y -0,48 respectivamente. Conclusiones: Existe una elevada prevalencia de deficiencia de vitamina D en sangre de cordón umbilical independiente de la exposición solar.Se observó una correlación entre niveles bajos de vitamina D y etnia, indumentaria tradicional, baja exposición solar y fototipo de piel oscura. No se observaron diferencias estadísticamente significativas entre los niveles de vitamina D y las variables perinatales estudiadas (AU)

Background: Plasma vitamin D (25(OH)D) levels in the newborn are dependent on maternal stores. Several studies showing a high prevalence of vitamin D deficiency in pregnant women have been published last years. The aim of the study was to analyze 25(OH)D levels in cord blood after summer month, determine whether there is a relation with different variables. Methods: 103 pregnant women were recruited between October and early December 2014, whose gestations took place during month of maximum sun exposure. Plasmatic 25(OH)D values were measured in cord blood at birth. Clinical record data were collected and a nutritional survey was made on maternal vitamin D and calcium intake and sun exposure. Statistical analysis was performed using SPSS. Comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests, and correction for multiple comparisons using Bonferroni. P value <0.05 and <0.0083 for multiple comparisons were considered statistically significant. Results: Mean 25(OH)D value in cord blood was 12.36± 7.2 ng/ml. Vitamin D deficiency was present in 83.4% of women. A statistically significant correlation was observed between lowvitamin D levels and low vitamin D intake (correlation coefficient 0.29); Ethnic group, with the highest level in caucasic group (17.9 ± 5.83 ng/ml) and the lowest in indopakistani group (6.68 ± 4.2 ng/ml); the use of traditional clothing (5.64 ± 3.09 ng/ml); low sun exposure and dark skin phototype with a correlation coefficient of 0.67 and -0.48, respectively. Conclusions: There is a high prevalence of vitamin D deficiency in pregnant women regardless of the season and increased sun exposure. Low vitamin D levels in cord blood were significantly related to ethnicity (Indopakistan and Maghreb), low sun exposure and dark skin phototype. No statistically significant differences were found between vitamin D levels and perinatal variables studied (AU)

γ-Irradiated cord blood MNCs: different paracrine effects on mature and progenitor endothelial cells.

Cell-based therapies have been employed to promote neovascularization mainly through the release of paracrine factors inhibiting apoptosis and supporting migration and proliferation of resident differentiated cells. We tested in vitro pro-angiogenic effects of apoptotic cord blood-derived mononuclear cells (CB-MNCs) and their conditioned medium (CM) on mature endothelial cells (HUVECs) and peripheral blood-derived endothelial progenitor cells (ECFCs). CB-MNCs were γ-irradiated to induce apoptosis and cultured for 72 h to obtain the release of CM. MNCs viability, evaluated by flow cytometry, decreased progressively after γ-irradiation reaching 41% at 72 h. γ-Irradiated MNCs (γMNCs) released increasing amounts of EGF, PDGF-AB and VEGF in their CM over time, as assessed by ELISA. γ-MNCs and their CM enhanced capillary-like network formation (in a dose-dependent and time-persistent manner), proliferation and migration of HUVECs in vitro, while they primed capillary-like network formation (dose-independent and not time-persistent) and induced migration but did not support proliferation of ECFCs. Our data support the hypothesis of paracrine mechanism as prevalent in regenerative medicine and demonstrate the efficacy of MNCs secretome in inducing neovascularization. To our knowledge, this is the first paper highlighting differential pro-angiogenic effects of CM on mature and progenitor endothelial cells, adding a tile in the understanding of mechanisms involved in neovascularization.

Characterization of DNA damage-induced cellular senescence by ionizing radiation in endothelial cells.

PURPOSE: Inhibition of growth in mammalian cells in response to damage or stress is known as cellular senescence. Increasing evidence suggests that double-strand breaks (DSB) commonly mediate cellular senescence. Recently, radiation exposure has been reported to induce premature senescence. MATERIALS AND METHODS: We investigated whether ionizing radiation (IR) at 4 Gy induces cellular senescence with DNA damage response in human umbilical vein endothelial cells (HUVEC). To determine alterations in gene expression on IR exposure, we have developed a DNA microarray analysis system that contains genes known to be involved in replicative senescence. RESULTS: The damage by IR exposure is shown to result in a variety of senescence-like phenotypes such as changes in cell morphology, decrease in cell proliferation, increase in senescence- associated ß-galactosidase (SA-ß-gal) staining, and suppression of angiogenic activity. Moreover, the expression levels of several genes associated with cell cycle regulation are remarkably increased in IR-exposed endothelial cells. We found that IGFBP5 (insulin-like growth factor binding protein 5), PLAT (plasminogen activator), SNAI2 (snail homolog 2), JAG1 (jagged 1), SPRY4 (Sprouty homolog 4), and CD44 were upregulated, whereas CFB (complement factor B), VCAM1 (vascular cell adhesion molecule 1), AQP1 (aquaporin 1), LOXL1 (lysyl oxidase-like 1), and RBPMS (RNA-binding protein with multiple splicing) were down- regulated in both radiation-damaged and old cells. CONCLUSIONS: These results imply that the IR-induced phenotype may be enhanced by alterations in genes associated with senescence.

Characteristics of myeloid differentiation and maturation pathway derived from human hematopoietic stem cells exposed to different linear energy transfer radiation types.

Exposure of hematopoietic stem/progenitor cells (HSPCs) to ionizing radiation causes a marked suppression of mature functional blood cell production in a linear energy transfer (LET)- and/or dose-dependent manner. However, little information about LET effects on the proliferation and differentiation of HSPCs has been reported. With the aim of characterizing the effects of different types of LET radiations on human myeloid hematopoiesis, in vitro hematopoiesis in Human CD34(+) cells exposed to carbon-ion beams or X-rays was compared. Highly purified CD34(+) cells exposed to each form of radiation were plated onto semi-solid culture for a myeloid progenitor assay. The surviving fractions of total myeloid progenitors, colony-forming cells (CFC), exposed to carbon-ion beams were significantly lower than of those exposed to X-rays, indicating that CFCs are more sensitive to carbon-ion beams (D(0) = 0.65) than to X-rays (D(0) = 1.07). Similar sensitivities were observed in granulocyte-macrophage and erythroid progenitors, respectively. However, the sensitivities of mixed-type progenitors to both radiation types were similar. In liquid culture for 14 days, no significant difference in total numbers of mononuclear cells was observed between non-irradiated control culture and cells exposed to 0.5 Gy X-rays, whereas 0.5 Gy carbon-ion beams suppressed cell proliferation to 4.9% of the control, a level similar to that for cells exposed to 1.5 Gy X-rays. Cell surface antigens associated with terminal maturation, such as CD13, CD14, and CD15, on harvest from the culture of X-ray-exposed cells were almost the same as those from the non-irradiated control culture. X-rays increased the CD235a(+) erythroid-related fraction, whereas carbon-ion beams increased the CD34(+)CD38(-) primitive cell fraction and the CD13(+)CD14(+/-)CD15(-) fraction. These results suggest that carbon-ion beams inflict severe damage on the clonal growth of myeloid HSPCs, although the intensity of cell surface antigen expression by mature myeloid cells derived from HSPCs exposed to each type of radiation was similar to that by controls.

Relative biological efficiency of protons at low and therapeutic doses in induction of 53BP1/γH2AX foci in lymphocytes from umbilical cord blood.

PURPOSE: In order to evaluate DNA damage induced by protons at low and radiotherapeutic doses at the therapeutic proton complex at Ruzomberok, Slovak Republic, lymphocytes from umbilical cord blood (UCB) of the same four probands were irradiated in the dose range of 1-200 cGy with γ-rays and protons (200 MeV, irradiation in the Bragg peak). MATERIALS AND METHODS: DNA repair γH2AX/53BP1 foci were analyzed by fluorescent microscopy and flow cytometry. RESULTS: Statistically significant effects of radiations were detected by fluorescent microscopy at all doses higher 1 cGy. Almost all distributions of foci in irradiated cells fitted to the Poisson distribution. In general, there was no difference in the levels of γH2AX and 53BP1 foci in irradiated cells. Flow cytometry was less sensitive and detected radiation induced effects at doses of 50 cGy and higher. Factorial analysis of variance in the whole studied dose range has shown no significant effect of radiation quality on number of γH2AX and 53BP1 foci. The ratio of proton-induced foci to γ-ray-induced foci was 0.86 ± 0.16 (53BP1) and 0.99 ± 0.34 (γH2AX) as measured by fluorescent microscopy and 0.99 ± 0.16 (γH2AX) as measured by flow cytometry at the radiotherapeutic dose of 2 Gy. CONCLUSIONS: Both flow cytometry and fluorescent microscopy indicated that the average value of relative biological efficiency (RBE) at radiation doses ≥ 20 cGy was about 1.0. Our data that RBE increased at low doses ≤ 20 cGy are relevant both to the development of treatment modalities and exposures that take place during space exploration and should be verified by further studies.

Cytogenetic studies on newborns from high and normal level natural radiation areas of Kerala in southwest coast of India.

PURPOSE: To study, characterize and compare chromosome aberrations and karyotype anomalies among newborns from high (> 1.5 mGy/y) and normal (≤ 1.5 mGy/y) level natural radiation areas of monazite-sand bearing southwest coast of Kerala in India. MATERIALS AND METHODS: Cord blood samples from newborns were collected from selected Government hospitals in heparinized vials and cultures were set up employing standard microculture techniques, slides were prepared, coded and stained with giemsa. Well spread metaphases were analyzed for chromosome aberrations and karyotype anomalies. RESULTS: A total of 1,267,788 metaphases from 27,295 newborns of mothers aged 17-45 years (17,298 from high and 9,997 from normal level radiation areas) were analyzed during 1986-2007. Frequencies of dicentrics in high and normal level radiation areas were 1.90 ± 0.14 and 2.01 ± 0.26 per 10,000 cells, respectively (Relative frequency [RF] = 0.94; 95% CI: 0.71-1.26). Karyotype anomalies had a frequency of 5.49‰ and 6.7‰, respectively (RF = 0.82; 95% CI: 0.60-1.12). No dose-related trend was observed in chromosome aberrations or karyotype anomalies. CONCLUSION: Frequencies of chromosomal aberration and karyotype anomalies between the newborns from the high level natural radiation area (HLNRA) and normal level natural radiation areas (NLNRA) were very similar.

Irradiated allogeneic cells enhance umbilical cord blood stem cell engraftment in immunodeficient mice.

Umbilical cord blood (UCB) is a readily available source of hematopoietic stem cells for transplantation. UCB hematopoietic SCT for average- and large-sized patients is often limited by the number of cells available in a single unit. To address this limitation, we performed experiments to determine if adjunctive therapy with third-party human allogeneic cells enhances the engraftment of human UCB in immunodeficient mice. UCB cells with or without sequential infusion of irradiated third-party allogeneic cells were used in transplantation studies of NOD/SCID and NOD/SCID-IL2Rγ null mice. We studied the impact of irradiated allogeneic cells on colony formation in vitro using long-term culture assays also. Our studies demonstrate that short- and long-term UCB engraftment of immunodeficient mice is enhanced by irradiated allogeneic cells. Secondary transplants demonstrate the durability of engraftment. These preclinical studies support the further development of irradiated allogeneic cells as an adjunct to single UCB transplantation when limiting numbers of cells are available.

Testing genotoxicity and cytotoxicity strategies for the evaluation of commercial radiosterilized fetal calf sera.

Effects of 18 commercial lots of fetal calf serum (FCS) after gamma-irradiation and their non-irradiated counterparts were comparatively analyzed on CHO-K1 and MDBK MDL1 cells for genotoxicity [sister chromatid exchange (SCE), micronuclei (MNi), and single cell gel electrophoresis (SCGE)], cytotoxicity [cell-cycle progression (CCP), proliferative replication index (PRI), mitotic index (MI), growth promotion (GP), and plating efficiency (PE)], and microbiological properties (mycoplasma and bovine viral diarrhea virus contamination). SCE and SCGE were the most informative end-points for genotoxicity since significant differences were found in 44.4% (P<0.05-0.001, Student's t-test) and 61.1% (P<0.05-0.001, chi(2) test) samples, respectively. MI was the cytotoxicity assay revealing the greatest variation, showing differences in 66.7% (P<0.05-0.001, chi(2) test) samples. Thus, these three end-points for screening bioproducts such as FCS were found most suitable for detecting potential geno-cytotoxicants in biological samples; their simultaneous use could be strongly recommended.

Photodynamic treatment with mono-phenyl-tri-(N-methyl-4-pyridyl)-porphyrin for pathogen inactivation in cord blood stem cell products.

BACKGROUND: Hematopoietic stem cell transplants and culture of hematopoietic progenitor cells require pathogen-free conditions. The application of a method of pathogen inactivation in red blood cells using photodynamic treatment (PDT) was investigated for the decontamination of cord blood stem cell (CBSC) products. STUDY DESIGN AND METHODS: CBSC products, spiked with Gram-positive and Gram-negative bacteria, were treated with PDT using mono-phenyl-tri-(N-methyl-4-pyridyl)-porphyrin (Tri-P(4)) and red light. After PDT, in vitro and in vivo evaluation of the CBSC functions were performed. RESULTS: PDT of CBSC products resulted in the inactivation of the bacteria, with Staphylococcus aureus being the most resistant. Complete decontamination was achieved when CBSC products were contaminated with low titers of bacteria. PDT had no effect on white blood cell viability, the ex vivo expansion potential of the progenitor cells, and their capacity to differentiate to various hematopoietic cell lineages. However, PDT reduced the engraftment of human CBSCs in NOD/SCID mice, particularly affecting the B-cell lineage engraftment. CONCLUSION: Pathogen inactivation of CBSC with Tri-P(4)-mediated PDT is feasible at contamination level up to 10 to 20 colony-forming units per mL and can be considered when ex vivo expansion culture is anticipated. However, this treatment is not recommended for transplantation purposes at this time. Further investigations may elucidate why engraftment is diminished.

Ultraviolet B irradiation selectively increases the production of interleukin-8 in human cord blood-derived mast cells.

UVB irradiation modulates immune responses in the skin and is a major cause of sunburn, during which neutrophils accumulate in the skin. Because of their abundance in skin and ability to produce a variety of proinflammatory mediators, we propose that mast cells may play a key role in ultraviolet B (UVB)-induced skin inflammation. Cord blood-derived human mast cells were treated in vitro with varying doses of UVB and production of multiple cytokines was measured in culture supernatants. UVB exposure significantly increased the release of interleukin (IL)-8 and modestly increased IL-1alpha production, but cytokines such as IL-2, IL-4, IL-6, IL-10, IL-12, IL-13, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma were unaffected. Cycloheximide reduced the UVB-mediated induction of IL-8 by 30-40%, suggesting that new protein synthesis contributed to IL-8 production. In line with this, UVB treatment of mast cells significantly increased IL-8 mRNA. In contrast to its effect on IL-8 production, optimal doses of UVB did not provoke histamine or tryptase release, indicating little effect on degranulation. Our data suggest that mast cells may play a major role during UVB-induced acute inflammation by selectively inducing cytokines involved in neutrophil recruitment.

[Examination of low temperature effect on cord blood serum by microwave dielectric method].

The influence of the freezing velocities and final temperatures of storage on the complex dielectric permittivity of cord blood serum have been studied. On the temperature dependences of the dielectric permittivity the non-monotonous changes at the characteristic temperatures accompanying with the change of the activation energy of the water molecules dielectric relaxation were found out. The drastic deflection of the temperature dependence of ?' from the monotone curve at 15 degrees C region correlates with the fracture of Arrhenius plots of the dielectric relaxation time and viscosity at the same temperature. Slow freezing (1-2 degrees C/min) of cord blood serum results in ?' diminution in comparison with control, that testifies an increase of bound water amount because of loosening in this case the surface of biomacromolecule polypeptide chains. Rapid freezing (300-400 degrees C/min) results in ?' increase of serum, that is caused, apparently, by the cryoaggregation of biomacro-molecules, which can thus happen.

Protective effects of thrombopoietin and stem cell factor on X-irradiated CD34+ megakaryocytic progenitor cells from human placental and umbilical cord blood.

In previous studies we characterized the radiosensitivity of CFU-megakaryocytes from human placental and umbilical cord blood and the effects of various early-acting cytokines. We found that the maximal clonal growth of CFU-megakaryocytes in vitro and maximal protection against X-ray damage were supported by a combination of thrombopoietin and stem cell factor. However, the mechanism by which the two cytokines exert a synergistic effect remained unclear, so we extended these studies to investigate the radioprotective action of synergistic thrombopoietin and stem cell factor on the survival of X-irradiated CD34(+) CFU-megakaryocytes. A combination of thrombopoietin and stem cell factor led to activation of mitogen-activated protein kinase and extracellular signal-regulated protein kinase and to suppression of caspase 3 in X-irradiated CD34(+) cells. When PD98059 and various synthetic substrates-specific inhibitors of these proteins-were used, the combination had less effect on the clonal growth of X-irradiated CD34(+) CFU-megakaryocytes. However, the addition of wortmannin, a specific inhibitor of the phosphatidylinositol-3 kinase pathway, did not alter the synergistic action of thrombopoietin plus stem cell factor. We suggest that part of this synergistic effect can be explained by activation of mitogen-activated protein kinase and extracellular signal-regulated protein kinase and by suppression of the caspase cascade.

Effects of amifostine on the proliferation and differentiation of megakaryocytic progenitor cells.

This study investigated the effects of amifostine, a clinically usable radioprotector or chemoprotector, on the proliferation and differentiation of normal and X-irradiated cluster of differentiation 34 positive (CD34+) megakaryocytic progenitor cells (colony-forming unit in megakaryocytes, CFU-Meg) from human placental and umbilical cord blood (CB) in vitro. Amifostine significantly accelerated megakaryocyte colony formation in a plasma clot culture supplemented with recombinant human thrombopoietin because of an increase in immature CFU-Meg-derived large megakaryocyte colony formation. An analysis of the cells that were harvested from the culture showed that amifostine induced a 70- and an 83-fold increase in the total cell and CFU-Meg numbers, respectively, and produced hyperploid megakaryocytes of more than 8 N ploidy. The radioprotective effect of amifostine on the clonal growth of X-irradiated CD34+ CFU-Meg was observed by treatment before or after irradiation. These findings suggest that the action of amifostine extends from immature CFU-Meg to the terminal differentiation of megakaryopoiesis, and its radioprotective effect is shown in megakaryopoiesis and thrombopoiesis.

Extended exposure of adult and fetal mice to 50 Hz magnetic field does not increase the incidence of micronuclei in erythrocytes.

The flow cytometer-based micronucleus assay was used to study the effects on chromosomes in erythroid cells of CBA/Ca mice after extended exposure to 50 Hz magnetic field (MF), 14 microT, peak-to-peak (p-p). The study included two different experiments: (a) mice exposed in utero during 18 days of their prenatal stage, and (b) adult mice exposed for 18 days. In experiment (a) 35 days after exposure was terminated, peripheral blood was drawn from the mice exposed in utero to determine whether the exposure had a genotoxic effect on the pluripotent erythroid stem cells. About 200000 polychromatic erythrocytes (PCE) and 200000 normochromatic erythrocytes (NCE) were analysed from each of 20 exposed mice. The EMF exposure did not significantly change the frequency of micronucleated PCE or NCE in comparison with 20 sham-irradiated mice. There was no difference in the proportion of PCE between exposed and unexposed animals. Similarly, in experiment (b) no differences were seen between EMF exposed and unexposed adult mice when samples of peripheral blood were taken at the end of exposure and analyzed for micronuclei in PCE and NCE. The proportion of PCE was the same in both groups. The results indicate that exposure to EMF does not induce direct or indirect effects on chromosomes in erythroid cells expressed as increased levels of micronucleated erythrocytes of mice. No indications of delayed genetic effects were found.

[The indices of free-radical oxidation in the umbilical cord blood and placenta of inhabitants of the Altai Territory]. / Pokazateli svobodnoradikal'nogo okisleniia v plazme pupovinnoi krovi i platsente zhitel'nits Altaiskogo kraia.

Free-radical processes were studied in the umbilical blood and placenta of women from the regions of the Altai Territory, which were affected to different extents by nuclear tests on the Semipalatinsk grounds in 1949-1965. The data was obtained, which suggest changes of free-radical processes, from studied materials from women in labor in the regions most affected by the consequences of tests. The activity of erythrocytic superoxide dismutase was decreased, thus suggesting the formation of structural-functional defects of the erythrocytes. The data corresponds to the results obtained earlier when studying free-radical processes in the venous blood samples from female residents of the Altai Territory.