Multipotentiality

A large number of cells are involved in the immune response and all are derived fiom the multipotential stem cells of the bone marrow. The predominant cell is the lymphocyte but monocytes-macrophages, endothelial cells, eosinophils and mast cells are also involved with certain immune responses. The two types of immunity (humoral and cell-mediated) are dependent on two distinct populations of lymphocytes, the B cells and the T cells respectively. Both the humoral and the cell-mediated systems interact to achieve an effective immune response. 

Kondo T, Raff M 2000b Oligodendrocyte precursor cells reprogrammed to become multipotential CNS stem cells. Science 289 1754-1757 Lane ME, Sauer K, Wallace K, Jan YN, Lehner CF, Vaessin H 1996 Dacapo, a cyclin-dependent kinase inhibitor, stops cell proliferation during Drosophila development. Cell 87 1225-1235... 

Raff I don t know the answer to the second question. I suspect that the timer starts ticking when the precursors first arise from multipotential CNS stem cells, but we don t know. 

The related dynamic structure factor directly reveals this time dependence and exhibits a multipotential time behavior with a fast initial decay followed by a slowly relaxing tail over longer time periods. 

The FGFs stimulate the proliferation of mesodermally and ectodermally-derived cells and play central roles in mammalian development. Members of the FGF family are expressed in the embryonic period and are required for several critical events in neural development and specifically for neural induction. FGF-8 is necessary for positional identity required for axial specification and patterning of limb development. FGF-2 stimulates the proliferation of multipotential stem cells that subsequently give rise to neurons of the cortex and other brain regions. 

Nunes, M. C., Roy, N. S., Keyoung, H. M. et al. Identification and isolation of multipotential neural progenitor cells from the subcortical white matter of the adult human brain. Nat. Med. 9 439-447,2003. 

The development of mature neutrophils in the bone marrow occurs via the differentiation of multipotential stem cells into progenitor cells that are committed to neutrophilic lineages. As this process proceeds the ability of... 

Ikebuchi K, Clark SC, Ihle JN et al. Granuloc 4e colony-stimulating factor enhances interleukin 3 dependent proliferation of multipotential hemopoietic progenitors. Proc Natl AcadSciUSA. 1988 85 3445 3449. 

According to the accepted definition SC, resulting in only one type of the differentiated cells, are named unipotential (or monopotential), two - bipotential. Those cells which give the beginning to a few types of different specialized cells are named pluripotential or multipotential. Totipotential is the ability of cell to differentiate in all the types of cells and tissues of organism (in any of 350 specialized lines derivative of ectoderm, mesoderm and endoderm). 

Maltoni C et al Benzene A multipotential carcinogen. Results of long-term bioassays performed at the Bologna Institute of Oncology. AmJ Ind Med 4 589-630, 1983... 

Newer strategies for stem cell identification have been developed based on the knowledge of cell functions. A primitive and multipotential subpopulation of bone marrow mononuclear cells has been identified on the basis of the intracellular presence of aldehyde dehydrogenase (ALDH). Those cells can be marked on the basis of the presence of ALDH and are called aldehyde dehydrogenase-bright cells (ALDH cells), allowing for their separation from a bone marrow aspiration mononuclear subpopulation under fluorescence-activated cell sorter (FACS) analysis. 

Although the major physiological role of EPO is certainly to promote red blood cell production, EPO mRNA has also been detected in bone marrow macrophages, as well as some multipotential haemopoietic stem cells. Although the physiological relevance is unclear, it is possible that EPO produced by such sources may play a localized paracrine (or autocrine) role in promoting erythroid differentiation. 

Colter, D. C., Sekiya, I., and Prockop, D. J. (2001), Identification of a subpopulation of rapidly self-renewing and multipotential adult stem cells in colonies of human marrow stromal cells, Proc. Nat. Acad. Sci. USA, 98(14), 7841-7845. 

Gritti, A., Parati, E.A., Cova, L., Frolichsthal, P., Galli, R., Wanke, E., Faravelli, L., Morassutti, D.J., Roisen, F., Nickel, D.D., Vescovi, A.L. (1996). Multipotential stem cells from the adult mouse brain proliferate and self-renew in response to basic fibroblast growth factor. JNeurosci, 16, 1091-100. 

Every second of life a human must produce about 2.5 million red blood cells, about 2 million granulocytes, and many lymphocytes as well as other less numerous leukocytes. All of these arise from multipotential stem cells found in the bone marrow.376-379 Each of these stem cells divides to form one daughter stem cell and one progenitor cell.380 The progenitor cells are also stem cells but have differentiated into myeloid,381 erythroid, and lymphoid382 383 cells. 

Once the differences between both types of potential perturbation are clarified, a question arises about the nature of potential-controlled techniques attending to the nature of the perturbation, are they pulse potential or step potential techniques If the pulse definition is applied in a strict sense, only Single Pulse Voltammetry is a true pulse technique (see Scheme 2.1), whereas the rest of double and multipotential techniques are indeed multistep techniques (see Sects. 4.1, 5.1 and 7.1). 

A complete comprehension of Single Pulse electrochemical techniques is fundamental for the study of more complex techniques that will be analyzed in the following chapters. Hence, the concept of half-wave potential, for example, will be defined here and then characterized in all electrochemical techniques [1, 3, 8]. Moreover, when very small electrodes are used, a stationary current-potential response is reached. This is independent of the conditions of the system prior to each potential step and even of the way the current-potential was obtained (i.e., by means of a controlled potential technique or a controlled current one) [9, 10]. So, the stationary solutions deduced in this chapter for the current-potential curves for single potential step techniques are applicable to any multipotential step or sweep technique such as Staircase Voltammetry or Cyclic Voltammetry. Moreover, many of the functional dependences shown in this chapter for different diffusion fields are maintained in the following chapters when multipulse techniques are described if the superposition principle can be applied. 

In this section, we will show that the stationary responses obtained at microelectrodes are independent of whether the electrochemical technique employed was under controlled potential conditions or under controlled current conditions, and therefore, they show a universal behavior. In other words, the time independence of the I/E curves yields unique responses independently of whether they were obtained from a voltammetric experiment (by applying any variable on time potential), or from chronopotentiometry (by applying any variable on time current). Hence, the equations presented in this section are applicable to any multipotential step or sweep technique such as Staircase Voltammetry or Cyclic Voltammetry. 

This chapter addresses more complex electrode processes than one-electron reversible electrochemical reactions in single potential pulse techniques. The concepts given here set the basis for tackling the current-potential response in multipotential pulse electrochemical techniques (see Chaps. 4—7), which are more powerful, but also present greater theoretical complexity. 

All general typical variables considered in this chapter for a particular reaction scheme, for example the half-wave potential, are of fundamental interest for its characterization in any electrochemical technique. Moreover, as indicated in the previous chapter, all the current-potential expressions deduced here under stationary conditions (when microelectrodes are used) are applicable to any multipotential step or sweep electrochemical techniques like Staircase Voltammetry or Cyclic Voltammetry. 

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