Cell-biological Effects

Berg, H. Bioelectrochemical Field Effects Electrostimulation of Biological Cells by Low Frequencies 24... 

Li, P. C. H., Harrison, D. J., Transport, manipulation, and reaction of biological cells on-chip using electrokinetic effects. Anal. Chem. 69, 8 (1997) 1564-1568. 

The benefit of the LbL technique is that the properties of the assemblies, such as thickness, composition, and function, can be tuned by varying the layer number, the species deposited, and the assembly conditions. Further, this technique can be readily transferred from planar substrates (e.g., silicon and quartz slides) [53,54] to three-dimensional substrates with various morphologies and structures, such as colloids [55] and biological cells [56]. Application of the LbL technique to colloids provides a simple and effective method to prepare core-shell particles, and hollow capsules, after removal of the sacrificial core template particles. The properties of the capsules prepared by the LbL procedure, such as diameter, shell thickness and permeability, can be readily adjusted through selection of the core size, the layer number, and the nature of the species deposited [57]. Such capsules are ideal candidates for applications in the areas of drug delivery, sensing, and catalysis [48-51,57]. 

No one interferon will display all of these biological activities. Effects are initiated by the binding of the interferon to its specific cell surface receptor present in the plasma membrane of sensitive cells. IFN-a and -P display significant amino acid sequence homology (30 per cent), bind to the same receptor, induce similar biological activities and are acid stable. For these reasons, IFN-a and IFN-P are sometimes collectively referred to as type I interferons, or acid-stable interferons. 

Maximum disruption is obtained in a zone close to the probe tip and the biological cells must be kept here for sufficient time to allow disruption to take place. A delicate balance must therefore be struck between the power of the probe and the disruption rate since power ultrasound, with its associated cavitational collapse energy and bulk heating effect, can denature the contents of the cell once released. Indeed for this type of usage it is important to keep the cell sample cool during sonication. The method is very effective and continues to be an important tool in microbiology and biochemistry research. 

No one IFN will display all of these biological activities. Effects are initiated by the binding of the IFN to its specific cell surface receptor present in the plasma membrane of sensitive cells. 

EFFECT ON BIOLOGICAL CELLS 7.1. Vacuum Ultraviolet Region... 

In conclusion, spectacular advances in the fields of flavonoid bioavailability and flavo-noid-mediated cell effects in relation to the development of new biological tools (e.g., proteomic analysis, reporter genes) have been achieved during the last decade. A more coherent picture of the ways flavonoids combine their redox properties and affinity to specific proteins is emerging. This wealth of new chemical and biological information suggests that the elucidation of in vivo molecular mechanisms and receptors involved in flavonoid health effects is at hand. 

Vesicles are commonly considered models for biological cells. This is due to the bilayer spherical structure which is also present in most biological cells, and to the fact that vesicles can incorporate biopolymers and host biological reactions. Self-reproduction, an autocatalytic reaction already illustrated in the chapters on self-reproduction and autopoiesis, also belongs to the field of reactivity of vesicles. Some additional aspects of this process will be considered here, together with some particular properties of the growth of vesicles - the so-called matrix effect. 

In the meantime, the intense study of the simpler vesicle systems has unravelled novel, unsuspected physicochemical aspects - for example growth, fusion and fission, the matrix effect, self-reproduction, the effect of osmotic pressure, competition, encapsulation of enzymes, and complex biochemical reactions, as will be seen in the next chapter. Of course the fact that vesicles are viewed under the perspective of biological cell models renders these findings of great interest. In particular, one tends immediately to ask the question, whether and to what extent they might be relevant for the origin of life and the development of the early cells. In fact, the basic studies outlined in this chapter can be seen as the prelude to the use of vesicles as cell models, an aspect that we will considered in more detail in the next chapter. 

Biological Methods Enzymatic digestion of the cell wall is a good example of biological cell disruption. It is an effective method that is also very selective and gentle, but its high cost makes it impractical to be used for large-scale operations. 

On the other hand, the established cell line must simulate, as closely as possible, the physical and biochemical properties of the buccal or sublingual tissues in vivo. These properties such as the growth, differentiation, biological barrier effectiveness, permeability levels, and metabolic pathways are crucial to the permeation studies. 

In general, adenoviral vectors are known to infect the target cells effectively, but it is noteworthy to keep in mind that safety always comes first because some adverse side effects could be critical to the health of patients. Other types of viral vectors, such as adeno-associated virus, also are used for gene therapy in many diseases, even though more studies on safety, as well as efficacy, still remain until successful human clinical use can be expected. As demonstrated by clinical reports, fusion of knowledge on the molecular biology of viral vectors and the diseases to be treated holds promises for the future of medicine. 

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