Damage and repair of bone marrow CFUf and CFUc at different times after whole body sublethal gamma-irradiation of animals

Cellularity and colony-forming ability of stromal (CFUf) and haemopoietic (CFUc) bone marrow stem cells have been studied at different times after irradiation. The results obtained are indicative of the similarity between the kinetics of the damage and repair of stromal and haemopoietic stem cells.     

Induction of stem cell cycling in mice increases their sensitivity to a chemical leukaemogen: implications for inherited genomic instability and the bystander effect

Preconception paternal irradiation (PPI) modifies haemopoietic and stromal tissues of offspring and increases risk of generating lympho-haemopopietic malignancy if those offspring are then exposed to a leukaemogen. We hypothesised that this increased risk was related to inherited damage which had caused increased stem cell proliferation rates. To test for this link, in vivo, rapid stem cell proliferation was established by giving sub-lethal irradiation (3Gy gamma-rays) and allowing 3 days recovery. At this stage, 60% of haemopoietic spleen colony-forming units (CFU-S) were in DNA-synthesis, compared to <10% in unirradiated controls. Two groups of mice, unirradiated controls and irradiated animals, were then injected with 50mg/kg methyl nitrosourea (MNU) and observed daily for onset of lympho-haemopoietic malignancy. In a further control group of 60 mice, irradiated but not injected with MNU, only one leukaemia developed. In unirradiated controls, 20% of the mice developed malignancies between 3 and 8 months later: in the irradiated, MNU-treated groups, 95% developed malignancies between 2 and 7 months later. Thus, at least one powerful potentiating mechanism for induction of lympho-haemopoietc malignancy following inherited damage can be related to haemopoietic stem cell proliferation. Genomic instability is exposed by cell proliferation and has been implicated in this type of damage. However, a regulatory stromal microenvironment plays a part in inducing that proliferation. Thus, the microenvironment is the effective "bystander" which is thought to promote and amplify genomic instability, and thereby influence the induction of malignancy both in PPI offspring and in mice with induced stem cell proliferation.     

The effect of diucifon on the hematopoietic and immune systems in normal and irradiated organisms

It was shown that irradiation of mice with the dose of 4 Gy affected the immune and haemopoietic systems. Diucyphone injected on days 6-8 after irradiation favoured the production of antibodies in the spleen, increased the yield of exogenous splenic colonies and corrected differentiation of the haemopoietic stem cells. In the normal body, diucyphone decreased the colony-forming activity and did not change the haemopoietic stem cell differentiation.     

Ncr1p, the yeast ortholog of mammalian Niemann Pick C1 protein, is dispensable for endocytic transport

The Niemann Pick C1 protein localizes to late endosomes and plays a key role in the intracellular transport of cholesterol in mammalian cells. Cholesterol and other lipids accumulate in a lysosomal or late endosomal compartment in cells lacking normal NPC1 function. Other than accumulation of lipids, defects in lysosomal retroendocytosis, sorting of a multifunctional receptor and endosomal movement have also been detected in NPC1 mutant cells. Ncr1p is an ortholog of NPC1 in the budding yeast Saccharomyces cerevisiae. In this study, we show that Ncr1p is a vacuolar membrane protein that transits through the biosynthetic vacuolar protein sorting pathway, and that it can be solubilized by Triton X-100 at 4 degrees C. Using well-established assays, we demonstrate that the absence of Ncr1p had no effect on fluid phase and receptor- mediated endocytosis, biosynthetic delivery to the vacuole, retrograde transport from endosome to Golgi and ubiquitin- and nonubiquitin-dependent multivesicular body sorting. We conclude that Ncr1p does not have an essential role in known endocytic transport pathways in yeast.     

Probability of self-renewing divisions of spermatogonial stem cells in colonies, formed after fission neutron irradiation

Abstract.
Repopulating spermatogenic colonies, found in the seminiferous epithelium after irradiation with fast-fission neutrons, were studied to determine the cha nce that a stem cellA_single (A_s spermatogonium would complete a self-renewing division (P). Mathematical formulas originally derived for such studies in haemopoietic colonies were employed, and a method specifically aimed at spermatogenic colonies was developed. The results showed that during the first division after irradiation, P is close to 1 -0. P decreases in later generations, but remains 0-7 or higher up to the 4th or 5th divisions. The mean value for P was over 0-8, which is higher than the value of 0-6-0-7 found for stem cells in haemopoietic colonies.     

Elucidating the mechanisms of influenza virus recognition by Ncr1

Natural killer (NK) cells are innate cytotoxic lymphocytes that specialize in the defense against viral infection and oncogenic transformation. Their action is tightly regulated by signals derived from inhibitory and activating receptors; the later include proteins such as the Natural Cytotoxicity Receptors (NCRs: NKp46, NKp44 and NKp30). Among the NCRs, NKp46 is the only receptor that has a mouse orthologue named Ncr1. NKp46/Ncr1 is also a unique marker expressed on NK and on Lymphoid tissue inducer (LTI) cells and it was implicated in the control of various viral infections, cancer and diabetes. We have previously shown that human NKp46 recognizes viral hemagglutinin (HA) in a sialic acid-dependent manner and that the O-glycosylation is essential for the NKp46 binding to viral HA. Here we studied the molecular interactions between Ncr1 and influenza viruses. We show that Ncr1 recognizes influenza virus in a sialic acid dependent manner and that N-glycosylation is important for this binding. Surprisingly we demonstrate that none of the predicted N-glycosilated residues of Ncr1 are essential for its binding to influenza virus and we thus conclude that other, yet unidentified N-glycosilated residues are responsible for its recognition. We have demonstrated that N glycosylation play little role in the recognition of mouse tumor cell lines and also showed the in-vivo importance of Ncr1 in the control of influenza virus infection by infecting C57BL/6 and BALB/c mice knockout for Ncr1 with influenza.     

Ⅱ型限制性核酸内切酶NcrⅠ的研究

 在肉色诺卡氏菌C-212株Nocardia carnea C-212中筛选到一种Ⅱ型限制性核酸内切酶NcrⅠ,经与BglⅡ的λDNA降解物的酶谱比较,以及酶识别特异性和切割位点的检测,证明了NcrⅠ是已知的限制酶BglⅡ的同切限制酶,而且其切割位点也与BglⅡ相同,其为:     

Renal haemopoietic tissue of the mudskipper Periopthalmus koelreuteri (Pallas)

The renal haemopoietic tissue of the mudskipper Periophthalmus koelreuteri was examined by light and electron microscopy. Leukopoietic zone surrounding melanomacrophage center and erythropoietic zone were differentiated. The ultrastructural features of the cellular components of the haemopoietic compartments are similar to those described in other fishes. Despite the presence of lymphoid cells, this tissue is mainly myeloid, and active granulopoiesis and erythropoiesis occur, as in the red bone marrow of higher vertebrates. © 1992 Wiley-Liss, Inc.     

Estimates of the efficacy of the local protection of dogs against ionizing radiation

The possibility of prognosis of survival of dogs subjected to acute nonuniform irradiation leading to haemopoietic radiation sickness has been demonstrated. The prognosis is based on the "equal dose" concept that is implemented together with the dose dependence of the bone marrow haemopoiesis activity. The estimates of the consequences of irradiation of dogs, with certain body parts being shielded, have shown a good correlation between the calculation results and the experimental data.     

A two compartment model for cell survival after irradiation with ionizing radiation

A theory of cell survival after irradiation has been developed, considering the cell as composed of two compartments with different sensitivities and taking into account recovery phenomena. Expressions are obtained for the probabilities that the cell will be in a survival state or damaged state or will function with reduced efficiency.     

The effect of autoblood in a hyposmotic state on the colony-forming activity of hematopoietic stem cells]

It has been shown that hypoosmotic autoblood injected sub- or intracutaneously stimulates the colony-forming activity of haemopoietic stem cells in mice. Autoblood injected to animals immediately after their irradiation stimulates haemopoiesis even after a single dose. When mice are injected with autoblood prior to irradiation, the time between the first injection and the day of irradiation is critical for manifestation of the immunomodulating effect. Autoblood infusions immediately before, the day before, or two days before irradiation markedly deteriorate the clinical status of experimental animals and cause death in some of them. It is suggested that stimulation of haemopoiesis is associated with the appearance in the blood stream of a population of radiosensitive cells, apparently T-cell precursors.     

Radiosensitivity of cells-precursors of hemopoietic stroma (CFU-F) in the rat bone marrow under the effect of 60Co gamma irradiation in various conditions]

Conditions have been developed for cloning cells-precursors of rat bone marrow haemopoietic stroma, that form in culture dense and sparse fibroblast colonies (CFU-F) at a plating efficiency of 10(-4). Radiosensitivity of rat bone marrow CFU-F, with 60Co-gamma-irradiation in vitro, is characterized by the values of Do and n of 1.87 Gy and 1.4 respectively for all clones; 0.65 Gy and 6.7 for dense clones, and 4.27 Gy and 1.0 for sparse clones. This confirms the observed heterogeneity of CFU-F population consisting of highly radiosensitive and radioresistant subpopulations. The parameters of rat bone marrow CFU-F are nearly the same with irradiation both in vivo and in vitro; with in situ irradiation, the oxygen effect comes into play in a radiosensitive subpopulation of CFU-F; the OER values are 1.6, 2.6 and 0.9 for all, dense and sparse clones respectively.     

Postradiation recovery of hemopoietic and stromal precursor cells in mice preinjected with prodigiozan]

Injection of prodigiozan to mice 24 h before irradiation caused, by the time of the radiation effect, a decrease in the number of haemopoietic cells-precursors (CFUs and CFU-HM) in the bone marrow and an increase in the functional activity of stromal cell-precursors--the haemopoietic microenvironment of transfer units (HMTU); in the spleen, the number of CFUs decreased, but the number of CFU-HM increased considerably. During the postirradiation period, the haemopoietic and stromal precursors were damaged to a lesser extent, and CFUs, CFU-HM and HMTU recovered more readily in prodigiozan-protected animals than in unprotected mice; the HMTU restoration preceded the increase in CFUs and CFU-HM levels.     

STEM CELL KINETICS IN THE L 5222 RAT LEUKAEMIA

The behaviour of normal haemopoietic stem cells of the bone marrow during the development of the acute transferable rat leukaemia, L 5222, has been investigated. The granulopoietic committed stem cells, measured by the in vitro colony technique, showed a marked decrease to less than half normal levels. Pluripotent stem cells included in the small lymphocytes of the bone marrow, and labelled with ³H-thymidine by the complete labelling method, showed only a modest decrease in number and an unchanged labelling intensity. The results suggest that in this leukaemia the pluripotent stem cells may be affected in such a way that they are unable to react by proliferation to the depletion of the succeeding cell compartments. This might be due to inhibition by leukaemic cells or to a disturbed feedback regulation between the committed and pluripotent stem cell compartments.     

Effect of co-polymer 2-methyl-5-vinylpyridine and 2-methyl-5- vinylpyridinium-n-oxide radiation induced myelodepression in mice

On the model of cytopenia induced in mice by irradiation with a dose of 4.0 Gy it was shown that injection of examined copolymer (400 mg/kg) 3 h after irradiation exerts positive effect on haemopoietic system: the decrease of damage and acceleration of repair processes.     

Stem cell (CFU-s) proliferation in sublethally irradiated mice

Abstract. The proliferation rate of haemopoietic stem cells (CFU-s) was followed after sublethal total body irradiation with 1.5 Gy. The [³H]-thymidine suicide technique was used to measure the CFU-s proliferation rate. The measurements extended from 10 min after irradiation up to 21 days. The CFU-s did not enter the DNA synthesis period (S-phase) shortly after irradiation, as had been previously suggested, but did so only with a delay of 14–16 hr. A large scatter of results was explained by an oscillatory pattern in CFU-s proliferation. The CFU-s prepared for cell division in synchronized waves, with a period of 20–22 hr.     

Regeneration of hematopoietic stromal progenitor cells following irradiation

A high but limited capacity of haemopoietic stroma precursors to regenerate after irradiation and curettage was shown by the method of bone marrow implantation under the renal capsule of the syngeneic mice.     

Modifying effect of deep hypoxia on neutron-irradiated mice

Deep hypoxia was shown to influence the survival of animals, the state of the small intestine mucosa and the haemopoietic system. DMF (LD50/30) was 2.49 and 1.66 with X- and neutron radiation, respectively. As to haemopoietic stem cells X-irradiated in vivo, D0 was 0.96 +/- 0.04 Gy (control) and 2.82 +/- 0.14 Gy (anoxia). With neutron irradiation, D0 was 0.44 +/- 0.01 Gy and 0.8 +/- 0.03 for the control and experimental animals respectively.     

The role of the hemopoietic microenvironment on the hemopoiesis-stimulating effect of cystamine

The influence of cystamine delivered in a radioprotective dose before and after irradiation of mouse-recipients (8 Gy) on the effectiveness of exogenous bone marrow cloning has been investigated. Cystamine administered prior to irradiation exerts a protective effect on CFUs and also causes an increase in the number of splenic colonies grown from CFUs of the transplanted bone marrow. With cystamine administered after irradiation the protective effect is absent, but the CFUs number in the femur increases in recipients transplanted with intact bone marrow in comparison with those transplanted without cystamine. It is believed, that in addition to the specific protective mechanism of action of radioprotectors, there is a nonspecific mechanism of increasing the proliferation of protected stem cells that is connected with the stimulatory effect of radioprotective agents on the haemopoietic stroma elements.