Cell dispersion

Table 3.1 summarizes the details of typical sources, absorption cells, dispersing elements and detectors used in different regions of the electromagnetic spectrum. 

A plastic that suffers a density decrease by the presence of numerous cells dispersed throughout the material. 

No spectrum given but notes that with wide slit widths, cells disperse from this region.(see Note 6). 

In general, it can be said that, often of necessity, the detector cell may be relative large with a low aspect ratio and thus, would theoretically produce serious band dispersion. In practice the predicted dispersion is reduced by deign of the inlet and outlet tubes, as discussed above, to ensure maximum secondary flow in the cell and thus, minimize dispersion. The success of the procedure to reduce detector cell dispersion depends on the type of detector and the principle of detection. For example.it is far easier to design a low dispersion electrical conductivity cell than a low dispersion UV absorption cell. 

The cellular and molecular events involved in the dopamine-stimulated release of PTH can be clarified in experiments utilizing bovine parathyroid cells dispersed with collagenase and DNase (ft). This dispersion procedure yields parenchymal cells with only a slight contamination by red blood cells. The parenchymal cells exclude trypan blue and appear normal by light and electron microscopy (ft). These cells release PTH in a linear fashion for several hours the release is inhibited by calcium and stimulated by dopamine and beta-adrenergic agonists at concentrations comparable to those used to elicit physiological responses in vivo (ft,ft). 

Figure 3. Effect of certain drugs on IR-aMSH release from rat cells. Dispersed rat 1L cells were exposed to isoproterenol, lisuride, or no drug (control) for the indicated periods of time. Isoproterenol enhances the release of IR-aMSH while lisuride inhibits the release of IR-aMSH. (Data are from Reference 12.)...

Apply 1 m/s as flow velocity so that the total contact time in the channel is 500 seconds. The modeling should be done as Id transport model with 10 cells (dispersivity 0.1 m) and last over 750 seconds. Also take into account the contact with the atmosphere. Therefore, ran the model once with a C02 partial pressure of 0.03 Vol% and a second time with 1 Vol%, both times assuming an oxygen partial pressure of 21 Vol% 02. The latter case corresponds rather to a closed carbonate channel. 

Since protein complex formation and Ca2+ are critical to cell fixation within a tissue, dissociation media usually contain some type of proteolytic enzyme and the Ca2+ chelator, EDTA. The proteolytic enzyme can be of general specificity, such as trypsin, or can be a more targeted enzyme, such as a collagenase selective for the collagen-type characteristic of the tissue of interest. Hyaluronidase has been also used with matrix rich in hyaluronic acid, such as for isolation of duodenal entero-cytes. In all cases, the appropriate incubation times and concentrations to achieve cell dispersal, but retain high viability, need to be determined empirically. One factor... 

The optimum pH levels are between 5 to 9. The cells grow in the medium containing NaCl at up to 2% with relatively slower rate, but do not grow at 3%. The cells disperse easily in a culture medium and do not adhere to culture vessel indicating the advantage in mass culture. Furthermore, scum formation is rarely observed during the culture. 

Figure 4.2 The release of H from human mast cells dispersed from different tissues (shaded bars) and the time taken for that H to be released (open bars). This figure was constructed using data from Benyon et af. (1987), Lowman et af. (198c), Rees et af. (1988) and Lau et af. (1995).

The final example of functional heterogeneity which we will illustrate relates to drug modulation of mediator release. Using mast cells dispersed from human lung, skin, adenoids, tonsils and colon, we have shown each to be similarly sensitive to /3-stimulants and theophyllinelike drugs, concentrations of 10 M and 5 x lO M,... 

Lowman, M.A., Rees, P.H., Benyon, R.C. and Church, M.K. (1988c). Human mast cell hetert neity Histamine release from mast cells dispersed from skin, lung, adenoids, tonsils and intestinal mucosa in response to IgE-dependent and non-immunological stimuli. J. Allergy Clin. Immunol. 81, 590-597. 

High-power ultrasound has been used to disrupt cells, disperse aggregates, and modify food texture and crystallization (Knorr et ah, 2004). The ultrasonic wave causes intense localized heating and this generates gas bubbles which cavitate and result in intense pressure and shear (Povey and Mason, 1998). It is the high pressure and shear which cause physical disruption of food components and materials and can change the rate of chemical reactions. Kentish et ah (2008) used a flow-through power ultrasound systems at 20-24 kHz to produce an oil-in-water emulsion with... 

Reese BE, Necessary BD, Tam PP, Faulkner- Jones B, Tan SS. 1999. Clonal expansion and cell dispersion in the developing mouse retina. Eur J Neurosci 11 2965-2978. 

One of the first papers on the potential role of NO in the ovary demonstrated that cells dispersed from immature rat ovaries synthesized NO in response to IL-ip (Ellman et al., 1993). As IL-lp is known to play a significant role in the ovulatory process (Kol and Adashi, 1995) and has been shown in other cells to transcriptionally induce iNOS (Perrella et al., 1994 Kunzet al., 1994), these authors speculated that ILl p-induced NO functioned as a cytotoxic agent in the rupture of the follicular wall during ovulation (Figure 2). Several investigators have shown that NO mediates several but not all of IL-1 P s functions in the ovulatory process (Ben-Shlomo... 

Cytokinesis - The cell divides. After division, the chromosomes of the daughter cells disperse, and a new G1 phase begins. 

These experiments clearly point to changes in local microenvironment, presumably ECM, as triggering crest cell dispersal in the axolotl, even though the molecules responsible are not known. Moreover, avian migratory stage crest cells do not migrate into early somitic tissue that is hetero-chronically transplanted, in contrast to their response to older somites (Bronner-Fraser and Stem,... 

Erickson, C.A. (1985) Control of neural crest cell dispersion... 

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