Microenvironment characterization

The sp values of most perfumery ingredients fall between ca. 16 MPa0,5 (non-polar materials such as terpene hydrocarbons) and ca. 25 MPa0,5 (polar materials such as alcohols). In general, we expect materials to have lower activity coefficients in microenvironments characterized by similar values of sp. For instance, limonene (sp value of 16.5) is expected to be compatible with plastics such as polyethylene... 

Vaupel P, Jain RK (eds) (1991) Tumor blood supply and metabolic microenvironment. Characterization and implications for therapy. Gustav Fischer, Stuttgart, New York Vaupel P Kallinowski F (1987) Hemoconcentration of blood flowing through human tumor xenografts. Int J Microcirc Clin Exp 6 72... 

Antoine, E.E., Vlachos, P.P., Rylander, M.N., 2014. Review of collagen I hydrogels for bioengineered tissue microenvironments characterization of mechanics, structure, and transport. Tissue Eng. Part B Rev. 20, 683—696. 

In its natural environment, hematopoiesis resides in a well-defined microenvironment characterized by local geometry (structure and vasculature), by stromal cells (accessory cells of mixed origin), and by an extracellular matrix composed of coUagen-like molecules and proteoglycans, produced by stromal cells (Nielsen, 1999). Thus, it is bkely that hematopoietic stem and progenitor cells (HSPCs) are influenced by accessory cells and the microenvironment they create in several ways. 

Initial efforts gave rise to well-characterized dendritic macromolecules, but applications remained limited because of the lack of specific functionalities. An exponential increase of publication volume observed for about 15 years testified the growing interest for dendrimers and has led to versatile and powerful iterative methodologies for systematically and expeditiously accessing complex dendritic structures. The perfect control of tridimensional parameters (size, shape, geometry) and the covalent introduction of functionalities in the core, the branches, or the high number extremities, or by physical encapsulation in the microenvironment created by cavities confer such desired properties as solubility, and hydrophilic/hydrophobic balance. Thus, creativity has allowed these structures to become integrated with nearly all contemporary scientific disciplines. 

The pyrene-like aromatic chromophore of BaPDE is characterized by a prominent and characteristic absorption spectrum in the A 310-360 nm spectral region, and a fluorescence emission in the X 370-460 nm range. These properties are sensitive to the local microenvironment of the pyrenyl chromophore, and spectroscopic techniques are thus useful in studies of the structures of the DNA adducts and in monitoring the reaction pathways of BaPDE and its hydrolysis products in DNA solutions. 

Although most often connected with investigations of solid dosage forms, diffuse reflectance spectroscopy can also be used to characterize alternative formulations. Through the use of a special sample cell, the technique has been used to study the stability of emulsions [37]. In this work, it was found that information could be obtained that pointed toward subtle changes in the emulsion microenvironment. 

After these preliminary remarks, the term polarity appears to be used loosely to express the complex interplay of all types of solute-solvent interactions, i.e. nonspecific dielectric solute-solvent interactions and possible specific interactions such as hydrogen bonding. Therefore, polarity cannot be characterized by a single parameter, although the polarity of a solvent (or a microenvironment) is often associated with the static dielectric constant e (macroscopic quantity) or the dipole moment p of the solvent molecules (microscopic quantity). Such an oversimplification is unsatisfactory. 

The concept of polarity covers all types of solute-solvent interactions (including hydrogen bonding). Therefore, polarity cannot be characterized by a single parameter. Erroneous interpretation may arise from misunderstandings of basic phenomena. For example, a polarity-dependent probe does not unequivocally indicate a hydrophobic environment whenever a blue-shift of the fluorescence spectrum is observed. It should be emphasized again that solvent (or microenvironment) relaxation should be completed during the lifetime of the excited state for a correct interpretation of the shift in the fluorescence spectrum in terms of polarity. 

We should first emphasize that viscosity is a macroscopic parameter which loses its physical meaning on a molecular scale. Therefore, the term microviscosity should be used with caution, and the term fluidity can be alternatively used to characterize, in a very general way, the effects of viscous drag and cohesion of the probed microenvironment (polymers, micelles, gels, lipid bilayers of vesicles or biological membranes, etc.). 

We currently established cultural system (amphycultural diffusion capsules) that allowed for conditions favorable for stem cell expansion in vitro. Many cell types and culture protocols and their combination with cytokines, growth factors, feeder layers can be implemented with ADC. Capsules are characterized by high perfusion rates that ensure that allow dilution of inhibitory autocrine factors and support long-term cell expansion. We have shown that ADC in vitro provides optimal cellular microenvironment that supports long term hematopoiesis (Bilko et al. 2005). 

The term responsive (elsewhere indicated as smart ) refers to diagnostic agents whose contrasting properties are sensitive to a given physicochemical variable that characterizes the microenvironment in which the probe is distributed (116-117). Typical parameters of primary diagnostic relevance include pH, temperature, enzymatic activity, redox potential and the concentration of specific ions, and low-weight metabolites. 

A Cell Culture System That Mimics Chronic Lymphocytic Leukemia Cells Microenvironment for Drug Screening and Characterization... 

A suitable fiuorescent probe is an organic molecule, which must change its characteristic parameters with changes in its microenvironment and the parameter must be measurable when the probe is added to the system [54]. The fluorescent probes are categorized as either extrinsic, intrinsic, or covalently bound probes. The intrinsic probes allow a system to be observed without any chemical perturbation. This occurs when the system to be characterized has an in-built fluorescent chromophore unit like tryptophan, tyrosine and phenyl alanine in protein. In some cases the fluorophore is covalently... 

Celis, J.E., et al. (2004) Proteomic characterization of the interstitial fluid perfusing the breast tumor microenvironment a novel resource for biomarker and therapeutic target discovery. Mol Cell Proteomics. 3, 327 4. 

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