Substratum

Maroudas N G 1977 Sulphonated polystyrene as an optimal substratum for the adhesion and spreading of mesenohymal sells in monovalent and divalent saline solutions J. Cell. Physiol. 90 511-20... 

Lakes. Lakes are a special kind of color additive prepared by precipitating a soluble dye onto an approved iasoluble base or substratum. In the case of D C and Ext. D C lakes, this substratum may be alumina, blanc fixe, gloss white, clay, titanium dioxide, 2iac oxide, talc, rosia, aluminum ben2oate, calcium carbonate, or any combination of two or more of these materials. Currentiy, alumina is the only substratum approved for manufactuting FD C lakes. 

In order to study the influence of surface disorder in the MM reaction, Frachenbourg et al. [91] have considered a substratum which has two types of randomly distributed sites with different adsorption rates. It is found that such a kind of disorder can sustain a reactive steady state, in contrast to the standard MM process on homogeneous surfaces. 

Unter gruppe, /. subgroup subordinate group, -guss, m. (Photog.) substratum. 

What I hope to have added to the discussion has been a philosophical reflection on the nature of the concept of element and in particular an emphasis on elements in the sense of basic substances rather than just simple substances. The view of elements as basic substances, is one with a long history. The term is due to Fritz Paneth, the prominent twentieth century radio-chemist. This sense of the term element refers to the underlying reality that supports element-hood or is prior to the more familiar sense of an element as a simple substance. Elements as basic substances are said to have no properties as such although they act as the bearers of properties. I suppose one can think of it as a substratum for the elements. Moreover, as Paneth and before him Mendeleev among others stressed, it is elements as basic substances rather than as simple substances that are summarized by the periodic table of the elements. This notion can easily be appreciated when it is realized that carbon, for example, occurs in three main allotropes of diamond, graphite and buckminsterfullenes. But the element carbon, which takes its place in the periodic system, is none of these three simple substances but the more abstract concept of carbon as a basic substance. 

A factor known as scatter factor has been characterized which causes the break up and stimulates motility of epithelial cell clumps (Stoker et al., 1987). This factor is identical to hepatocyte growth factor and increases the rate of locomotion of several other cell types. Motility factors elaborated from tumor cells are considered to play an important role in metastasis (see later). Guidance of cells by the physical topography of the substratum is another factor that profoundly affects the behavior of cells. 

When animal cells are removed from the body, the cells can be maintained (or cultured) for prolonged periods, provided the cells are in an appropriate alternative environment. Environmental factors of importance for animal cell culture include the culture medium, substratum (or surface of the culture vessel), and temperature. The substratum (or surface) is a significant factor for those animal cells which grow attached to the surface of the culture container. A number of types of animal cells (such as lymphoid cells) grow in suspension. 

Altered cell morphology Increased growth rate Increased saturation density Formation of multilayers Reduced adhesion to substratum Colony formation in soft agar Reduced serum requirement Altered growth factor requirement Tumor formation in athymic nude mice... 

Like sulforaphane, however, PEITC-NAC (N-acetylcysteine) conjugate appears to block in Gl. Studies by Lund et al. show that in the case of the colorectal cell line HT29, which lacks wild type p53, treatment with AITC causes the cells to detach from the substratum but, at least in the short-term, they do not then enter apoptosis . Where it does occur, induction of apoptosis by isothiocyanate appears to be a p53-dependent process. However, this statement must also be qualified, because the effect appears to depend on which metabolite is considered. For example, sulforaphane does appear to be able to induce apoptosis in HT29 cells, which express a mutated form of the protein. 

In some studies it has been shown that ITCs can cause increases in the pro-apoptotic caspase enzymes, caspase 3, caspase 8 or caspase However, in other work, specific caspase inhibitors failed to block cell death or cell detachment from the substratum . This suggests that caspase-activation may only be a bystander event, or may only occur after the initiating event of a block in the cell cycle. Indeed, although expression of c-Jun amino-terminal kinase (INK) in response to ITCs has been linked to the pro-apoptotic process, it remains entirely possible that this is a parallel signalling pathway, more closely related to the induction of Phase 1 or Phase 2 enzymes than to the... 

Microbial cells transported with the stream of fluid above the surface interact with conditioning films. Immediately after attachment, microorganisms initiate production of slimy adhesive substances, predominantly exopolysaccharides (EPS) that assist the formation of microcolonies and microbial films. EPS create bridges for microbial cells to the substratum and permit negatively charged bacteria to adhere to both negatively and positively charged surfaces. EPS may also control interfacial chemistry at the mineral/biofilm interface. 

Dickinson et al. also used microelectrodes to measure dissolved oxygen (DO), H2O2, and local within biofouling deposits on stainless steel surfaces exposed to river water to further resolve the interfacial chemistry that resulted in ennoblement. Data were then compared with those from similar measurements as close as possible to the environment of a non-fouled substratum. 

In the Dickinson et al. studies, the results of microelectrode measurements indicated that eimohlement was not caused by elevated levels of dissolved oxidants. Measurements at various heights above the substratum and at numerous sites over the coupon surface showed HjOj concentrations < 2 pM and no significant variation in for the stainless steel microelectrode at any site. DO profiles in the same regions showed saturation levels at all sites. Representative profiles are shown in Fig. 11. 

Rhizodeposition in nutrient solution culture is relatively easy to measure and readily altered. It may not reflect what happens in vivo due to the absence of a solid substratum for root growth. Simply including glass beads in nutrient solution can significantly increase rhizodeposition in maize (16), and such an effect must be considered when estimating rhizodeposition in relation to the natural environment. Consequently, a range of systems using various solid supports have been developed. Rhizodeposition in soil is considered in Sect. II.C. 

The simplest system devised comprises a microcosm where seedlings with roots sandwiched between Millipore membranes are in contact with agar containing plant nutrients (25). The shoots can be exposed to CO, and the loss of C into the agar via the roots is then monitored. The design enables the effect of microorganisms on rhizodeposition to be examined easily (26) but really lacks the complexity of substratum to allow data obtained to be related to rhizodeposition in soil. 

The information obtained has made it possible to propose a mechanism of interaction between RGMAs and Au/ZnO structures based on the concept of some change in the nature of the interaction between the metal microcrystal applied and the substratum as its size increases. 

Polyamines and their ammonium salts have been of interest because they are known to have potential applications as chelating agents (1-3), ion exchange resins (4-6), flocculants (7,8), and other industrial uses (9). Recent biomedical applications have constituted another important use of polymeric amines they have been investigated for use as biocompatable materials, polymeric drugs, immobilization of enzymes, cell-culture substratum and cancer chemotherapeutic agents (10-12). 

Levin E. G., Santell L. Association of a plasminogen activator inhibitor (PAI-1) with the growth substratum and membrane of human endothelial cells. J Cell Biol 1987 105, 2543-9. 

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