Multicellular spheroids: a three-dimensional in vitro culture system to study tumour biology

The growth of tumour cells as three-dimensional multicellular spheroids in vitro has led to important insights in tumour biology, since properties of the in vivo-tumour such as proliferation or nutrient gradients, can be studied under controlled conditions. While this review starts with an update of recent data on spheroid monocultures, especially concerning tumour microenvironment and therapeutic modalities, the main emphasis is put on the spectrum of heterologous cultures which have evolved in previous years. This type of culture includes tumour cell interaction with endothelial, fibroblast or immunocompetent cells. The relation of the spheroid culture model to other types of three-dimensional culture and our critical evaluation and presentation of the technical aspects of growing and analysing spheroids are included in the text. These topics are chosed to help the experimental pathologist design experiments with tumour spheroids and to stimulate discussion

Physical Chemistry of Milk Fat Globules

Many properties of milk and dairy products are determined by the behaviour and physical chemistry of milk fat globules. Allowed to stand, raw milk quickly separates into fat-enriched and fat-depleted phases, i.e. cream and skim milk, respectively. This is partly due to simple density differences between the emulsified fat globules and milk serum, but gravitational separation occurs at a rate ultimately determined by a complex series of colloidal interactions mediated by the milk fat globule membrane (MFGM) that lead to aggregation of fat globules, particularly at low temperatures (i.e. so-called cold agglutination). Creaming properties of milk differ between mammalian species, and processing of milk can profoundly alter the creaming properties of bovine milk, particularly homogenization and centrifugal separation, but also heat treatment. In this chapter, the principal physical properties of bovine milk fat globules are discussed, along with methods for their analysis and the impact of common dairy processes on their stability