Narrow Results

Polarimetry is a powerful optical tool in the biomedical field, providing more comprehensive information on the sub-wavelength micro-physical structure of a sample than traditional light intensity measurement techniques. This review summarizes the concepts and techniques of polarization and its biomedical applications. Specifically, we first briefly describe the basic principles of polarized light and the Mueller matrix (MM) decomposition method, followed by some research progress of polarimetric measurement techniques in recent years. Finally, we introduce some studies on biological tissues and cells, and then illustrate the application value of polarization optical method.

The United Kingdom regulatory landscape as it applies to cell-based therapies is rapidly evolving and constantly produces new information for researchers. This chapter brings together the plethora of information in the form of a process map of the key stages in the life cycle of a cell-based product, from cell/tissue procurement, processing and manufacture, through pre-clinical trials, clinical trials and on to commercialisation and post-launch activities. The critical components of each stage are described, and key issues which are pertinent to the UK researcher are discussed, for example, use of pre-clinical models, documentation requirements for clinical trials. The text goes on to identify which regulations, codes of practice and standards are already available for use in the UK and links them to the life cycle stages. The most recent regulation to be agreed in 2007 in Europe is also discussed. EC 1394/2007 is an amendment of EU Directive 2001/83/EC, and describes overarching regulations of advanced therapy medicinal products (which encompasses cell-based therapeutics).

This information is taken from a Publicly Available Specification (No. 83) which was written by the authors of this chapter and published by the British Standards Institution (BSI) in 2006. It is intended that this PAS acts as a quick reference source to increase clarity for users on the requirements needed for exploitation of a cell-based therapy in the UK, rather than an in-depth examination of the supporting literature.

In this paper, the compression of an isolated cell by two rigid indenters is analyzed. The neo-Hookean model is employed to characterize the hyperelastic behavior of biological cells. Owing to the greatly increased ratio between surface energy density and elastic modulus, surface energy plays important roles in the mechanical performance of biological cells. Using the dimensional analysis method and a finite element approach incorporating surface energy, we study the elastic compression of hyperelastic cells at finite deformation and give the explicit relations of contact radius and indent depth depending on compressive load. Our results reveal that surface energy obviously influences both the local deformation and the overall responses of hyperelastic cells at finite deformation. The obtained results are useful to determine the elastic properties of biological cells from indent-depth curves accurately.

The relationship between the organism's growth and its geometrical form was suggested by many ancient and modern thinkers. Many other factors influence growth and replication. All these numerous factors, such as biochemical, physical, work in cooperation. In this paper, we consider the impact of geometrical and physical characteristics of organisms, such as surface, volume and geometrical form, on organisms' growth and replication. The mathematical basis of our study is the growth equation, which describes growth from the physical perspective. First, we model the growth of cells by different shapes, and compare theoretical results to experimental data. We discover that the growth dependencies produced by the growth equation fit experimental data very accurately if we take into account two considerations. First, the cell, or a multicellular growing object, can switch into a replication phase before its physical growth potential is exhausted. Second, the inflow of substance through a unit of the membrane's surface increases during growth, because the cell's growing volume allows it to process more nutrients. Then, we consider overgrowth from the physical perspective, introduce the notion of a growth ratio as an important geometrical characteristic of the growth and overgrowth processes, and generalize our findings.

We present significantly advanced studies of the previously introduced physical growth mechanism and unite it with biochemical growth factors. Obtained results allowed formulation of the general growth law which governs growth and evolutional development of all living organisms, their organs and systems. It was discovered that the growth cycle is predefined by the distribution of nutritional resources between maintenance needs and biomass production. This distribution is quantitatively defined by the growth ratio parameter, which depends on the geometry of an organism, phase of growth and, indirectly, the organism's biochemical machinery. The amount of produced biomass, in turn, defines the composition of biochemical reactions. Changing amount of nutrients diverted to biomass production is what forces organisms to proceed through the whole growth and replication cycle. The growth law can be formulated as follows: the rate of growth is proportional to influx of nutrients and growth ratio. Considering specific biochemical components of different organisms, we find influxes of required nutrients and substitute them into the growth equation; then, we compute growth curves for amoeba, wild type fission yeast, and fission yeast's mutant. In all cases, predicted growth curves correspond very well to experimental data. Obtained results prove validity and fundamental scientific value of the discovery.

The article introduces a mathematical model of the physical growth mechanism which is based on the relationships of the physical and geometrical parameters of the growing object, in particular its surface and volume. This growth mechanism works in cooperation with the biochemical and other growth factors. We use the growth equation, which mathematically describes this mechanism, and study its adequacy to real growth phenomena. The growth model very accurately fits experimental data on growth of Amoeba, Schizosaccharomyces pombe, E.coli. Study discovered a new growth suppression mechanism created by certain geometry of the growing object. This result was proved by experimental data. The existence of the growth suppression phenomenon confirms the real workings and universality of the growth mechanism and the adequacy of its mathematical description. The introduced equation is also applicable to the growth of multicellular organisms and tumors. Another important result is that the growth equation introduces mathematical characterization of geometrical forms that can biologically grow. The material is supported by software application, which is released to public domain.