Changes in cell size

A cytostatic effect will result in a reduction in the number of cell doublings in a given time and thus a reduction in the number of cells within a colony. There are several ways of quantifying a cytostatic effect. The most direct method is to count the number of cells in 50 representative colonies per dish. Alternatively, it can be estimated by measuring the diameter of the colony and thus calculating the area of the colony. This method assumes that there is no change in cell size. 

B. Mostajir, T. Sime-Ngando, S. Demers, C. Belzile, S. Roy, M. Gosselin, J.P. Chanut, S. de Mora, J. Fauchot, F. Vidussi, M. Levasseur (1999). Ecological implications of changes in cell size and photosynthetic capacity of marine Prymnesiophyceae induced by ultraviolet-B radiation. Mar. Ecol. Progr. Ser., 187, 89-100. 

Intermittent sprays, such as those encountered in engine applications, are transient processes whose computations require a tracking of the time variable. The complexity of the solution algorithm outlined above requires that the time steps are determined from accuracy and stability criteria that include the change in cell size and the cell distortion as well as the strength of the chemical and liquid source terms. 

Woodruff PG, Dolganov GM, Ferrando RE, Donnelly S, Hays SR, Solberg OD, Carter R, Wong HH, Cadbury PS, Fahy JV. Hyperplasia of smooth muscle in mild/moderate asthma without changes in cell size or gene expression. Am J Respir Crit Care Med 2004 169(9) 1001-1006. 

The expansion index [51,102,103], defined as the ratio of cell fresh weight to dry weight evaluated at the time of maximum fresh weight, is a more qualitative indicator of changes in cell/aggregate size, under various cultivation conditions. Wongsamuth and Doran [58] identified the filtration characteristics of suspensions of Atropa belladonna, specifically cake permeability, which is at least partially related to morphology, as a useful indicator of shear effects. 

However, in the case of multimetallic catalysts, the problem of the stability of the surface layer is cmcial. Preferential dissolution of one metal is possible, leading to a modification of the nature and therefore the properties of the electrocatalyst. Changes in the size and crystal structure of nanoparticles are also possible, and should be checked. All these problems of ageing are crucial for applications in fuel cells. 

Precancerous cells have cellular changes that are abnormal but not yet malignant and may be described as hyperplastic or dysplastic. Hyperplasia occurs when a stimulus is introduced and reverses when the stimulus is removed. Dysplasia is an abnormal change in the size, shape, or organization of cells or tissues. 

Variations in cell size with age are due to a variety of factors. The major causes appear to be changes in the environment with the accumulation of waste products. An increase in the osmotic pressure of the medium will also cause a decrease in cell size and may very well be the most important factor. 

An important point to note here and elsewhere in the description of cell activity is that the particular nature of calcium biochemistry, including the availability of the element and its necessary rejection from the prokaryote cell, when linked to stimulated input and interaction with specific internal proteins of selected properties, made it uniquely suitable for the function as an elementary ionic fast in/out messenger. It was then capable of signalling to cell changes once cell size and organisation increased beyond the elementary level of a cell with one small, rapidly... 

CCD detectors use a phosphor to convert the incoming X-ray to visible light, which is in turn detected by the CCD chip. During this conversion process, the apparent size of an X-ray reflection increases, a phenomenon known as the point-spread factor. Typically, this change in reflection size does not present a significant challenge. In extreme cases (i.e. large unit cell dimensions or a very short sample to detector distance), however, it can lead to overlaps between adjacent reflections. When overlaps do occur, diffraction data can be recorded... 

When an excitatory pathway is stimulated, a small depolarization or excitatory postsynaptic potential (EPSP) is recorded. This potential is due to the excitatory transmitter acting on an ionotropic receptor, causing an increase in cation permeability. Changing the stimulus intensity to the pathway, and therefore the number of presynaptic fibers activated, results in a graded change in the size of the depolarization. When a sufficient number of excitatory fibers are activated, the excitatory postsynaptic potential depolarizes the postsynaptic cell to threshold, and an all-or-none action potential is generated. 

The growth of animals can be defined as an increase in mass of whole body, tissue(s), organ(s), or cell(s) with time. This type of growth can be characterized by morphometric measurements eg, skeletal muscle or adipose tissue growth can be described by observing temporal changes in cell number, ie, hyperplasia, and cell size, ie, hypertrophy. Growth also includes developmental aspects of function and metabolism of cells and tissues from conception to maturity. 

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