Impaired regeneration of the peripheral B cell repertoire from bone marrow following lymphopenia in old mice
ABSTRACT Aging is associated with a decreased production of B cells by the bone marrow and an increased life-span of peripheral B cells. To determine whether the decreased bone marrow B cell production is linked to the increased life-span of B cells in old mice, B cell regeneration following lymphopenia was studied in young and old mice. The rate of bone marrow pre-B cell and of splenic B cell regeneration is slower in irradiated, old compared to irradiated, young recipients of young, congeneic bone marrow. This finding reflects an age-associated defect in the bone marrow microenvironment. As the bone marrow is the only source of a diverse population of B cells, we measured the diversity of the splenic B cell repertoire regenerated following drug-induced lymphopenia in old and young mice. The heterogeneity of mRNA size from IgH complementarity determining region 3 (CDR3) was more restricted in splenic B cells from old compared to young mice providing additional evidence for an age-associated impairment in B cell production by the bone marrow.
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ABSTRACT: In this paper, the characteristics of dust-acoustic solitary waves in dusty plasma are studied. Dust charge and temperature are treated as variables. The authors have used the pseudopotential method to investigate the possibility of compressive as well as rarefactive solitons. An expression for the pseudopotential has been derived. The pseudopotential is a function of the Mach number, the relative temperature of low and high ion components, the relative ion concentration of dust charge and the temperature. Numerical computation shows that for the chosen set of parameters, only compressive solitons exist and their amplitudes increase with increasing Mach number. An increase in the dust temperature results in the disappearance of the compressive soliton. It is the only small parameter regime where compressive as well rarefactive solitons coexist. The effect of the relative ion temperature on solitons is also investigated. In the small amplitude limit, an increase in the dust temperature leads to a transition from compressive to rarefactive solitons.Journal of Plasma Physics 07/2004; 70(04):481 - 495. DOI:10.1017/S0022377803002733 · 0.74 Impact Factor
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ABSTRACT: Mesenchymal stem cells (MSCs) are known to have many notable features, especially their multiple differentiation ability and immunoregulatory capacity. MSCs are important stem cells in the bone marrow (BM), and their characteristics are affected by the BM microenvironment. However, effects of the BM microenvironment on the properties of MSCs are not well understood. In this study, we found that BM from aged mice decreased MSC colony formation. Flow cytometry data showed that the proportion of B220(+) cells in BM from aged mice was significantly lower than that in BM from young mice, while the proportion of CD11b(+), CD3(+), Gr-1(+), or F4/80(+) cells are on the contrary. CD11b(+), B220(+), and Ter119(+) cells from aged mice were not the subsets that decreased MSC colony formation. We further demonstrated that both BM from aged mice and young mice exhibited similar effects on the proliferation of murine MSC cell line C3H10T1/2. However, when cocultured with BM from aged mice, C3H10T1/2 showed slower migration ability. In addition, we found that phosphorylation of JNK (c-Jun N-terminal kinases) in C3H10T1/2 cocultured with BM from aged mice was lower than that in C3H10T1/2 cocultured with BM from young mice. Collectively, our data revealed that BM from aged mice could decrease the migration of MSCs from their niche through regulating the JNK pathway.Journal of the American Aging Association 04/2015; 37(2):9743. DOI:10.1007/s11357-014-9743-z · 3.45 Impact Factor
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ABSTRACT: Homeostasis of the hematopoietic system has its roots in the maintenance of hematopoietic stem cells (HSCs) in the bone marrow (BM). HSCs change both phenotypically and functionally with physiological age. The alterations noted in aged HSCs are thought to be a consequence of both cell-intrinsic and extrinsic changes. We review here the age-related changes that the BM microenvironment exerts on HSCs.International Journal of Hematology 08/2014; 100(4). DOI:10.1007/s12185-014-1641-8 · 1.68 Impact Factor