Cell number

Log phase Period of bacterial growth with logarithmic increase in cell number. 

Once there is an appreciable amount of cells and they are growing very rapidly, the cell number exponentially increases. The optical cell density of a culture can then be easily detected that phase is known as the exponential growth phase. The rate of cell synthesis sharply increases the linear increase is shown in the semi-log graph with a constant slope representing a constant rate of cell population. At this stage carbon sources are utilised and products are formed. Finally, rapid utilisation of substrate and accumulation of products may lead to stationary phase where the cell density remains constant. In this phase, cell may start to die as the cell growth rate balances the death rate. It is well known that the biocatalytic activities of the cell may gradually decrease as they age, and finally autolysis may take place. The dead cells and cell metabolites in the fermentation broth may create... 

Antineoplastic Agents. Figure 1 Relationship of cell number, number of cell divisions, and corresponding weight. 

Glucocorticoids. Figure 2 Cellular effect of glucocorticoids. Glucocorticoids can affect the activation of most resident and infiltrating cells with the airway suppressing either cell number or mediator release or both. In addition, glucocorticoids are able to decrease vascular permeablility (leak) within the airways that causes oedema and increase the expression of (32-receptors in smooth muscle cells. 

Strictly speaking, growth refers specifically to an increase in mass. In biological contexts, and increase in mass is often coupled to (and is indeed often a prerequisite for) proliferation (an increase in cell number). Importantly, growth and proliferation are distinct processes that can be both physiologically and experimentally uncoupled. 

The literature is less extensive on the use of protoplasts in stress-tolerance investigations however, some applications have been attempted. For example, in one study protoplasts were isolated from the leaves of a wild relative of tomato shown to be salt tolerant and from a salt-sensitive, cultivated species (Rosen Tal, 1981). In the presence of NaCI the plating efficiency (number of surviving cells/number of cells applied to the plate) of the wild relative was greater than the cultivated, sensitive cultivar. Proline, when added to the culture media, was found to enhance the plating efficiency of the salt-sensitive cultivar but not the wild, salt-tolerant relative. These results suggest that traits related to salt tolerance are expressed by the isolated protoplasts and that the response of protoplasts to environmental stress can be manipulated, i.e. the proline response. 

Mast cells express high-affinity IgE Fc receptors (FceRI) on their surface, contain cytoplasmic granules which are major sources of histamine and other inflammatory mediators, and are activated to release and generate these mediators by IgE-dependent and non-IgE-dependent mechanisms [1]. Disturbances either in the release of mast cell mediators or in mast cell proliferation are associated with clonal mast cell disorders including monoclonal mast cell activation syndrome (MMAS) and mastocytosis respectively, which are in turn associated with some cases of anaphylaxis [2], Molecular mechanisms have been identified which may link increased releasability of mast cell mediators and conditions leading to increased mast cell numbers [3]. Patients with mastocytosis have an increased risk to develop anaphylaxis [4, 5] and those with anaphylaxis may suffer from unrecognized mastocytosis or may display incomplete features of the disease [6-8]. 

Patients in the more aggressive categories are less likely to exhibit involvement of the skin and have a less favorable prognosis [10]. Those patients may have a definable hematological disorder such as a myelodysplastic syndrome, myeloproliferative disorder, acute leukemia, or a malignant lymphoma. In aggressive mastocytosis and mast cell leukemia, the clinical course is determined by the rapidity of the increase in mast cell numbers. 

The effect of a particular cultivation environment on a system can be evaluated in terms of biomass (fresh/dry weight, cell number), secondary metabolite production [51,75,89,102,103,106,107] or substrate consumption (e.g. carbon source [57] or oxygen [53,108]). Using the Evan s Blue method to identify non-viable cells. Ho et al. [108] used viable cell density measurements to determine variations in specific growth rate attributable to hydrodynamic stress. 

Daucus carota Couette viscometer laminar regrowth mitochondrial activity membrane integrity cell lysis (cell number) non-growth (sterile) [57, 69]... 

Many in vitro studies have been undertaken to explore the relative effectiveness of isothiocyanates, and associated compounds, as inhibitors of cell growth and inducers of apoptosis in cell lines, and some of these are summarised in Table 4.2. Clonal survival studies are often used to determine whether isothiocyanates inhibit initial cell anchorage and subsequent growth of sparsely seeded cells. However, differences in cell number following challenge with the isothiocyanate could be due either to decreased cell division or increased cell loss, and the authors of some in vitro studies have failed to recognise this. Other studies have, however, considered the interacting... 

In addition, a recent primate study reported that dietary consumption of soy infant formula reduced the neonatal testosterone surge and increased Leydig cell numbers in the testes of male marmosets. However, the longterm effects on the fertility of the animals has not been determined, and the health implications of these findings for humans are unclear (Sharpe et al,... 

Weinkove D, Neufeld TP, Twardzik T, Waterfield MD, Leevers SJ 1999 Regulation of imaginal disc cell size, cell number and organ size by Drosophila class IA phosphoinositide 3-kinase and its adaptor. Curr Biol 9 1019-1029... 

Growth at the level of the organism is an increase in cell number, cell mass, extracellular mass, fluid content and other components of the body that result in an increase of body mass. The mammalian body has very different growth phases with different functions. The pre-implantation embryo does not grow, but only divides, fuelled by materials that were deposited in the egg before fertilization. After implantation there is very rapid cell division which is tightly coupled to cell differentiation in the process of gastrulation — the creation of the different lineages... 

Nurse Martin Raff has set up two general questions that I think we should try to address in this discussion. One concerns the nature of this timer (and we could add to this, why is the timer needed). The second is this relationship between stem cells and progenitors, and what we mean by this. But I ll start with a specific question. If it is only 6-7% of the cells that undergo one or two more extra divisions, is that sufficient to account for the p27 l mutant phenotype with respect to cell number ... 

---