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The ultrastructural features and the gene expression pattern of Kaposi's sarcoma (KS) spindle cells in vivo suggest that KS is a tumor of the mixed cell type. The expression pattern of cytokines and cytokine receptors in the tumor lesion, together with the results obtained from in vitro characterization of KS-derived cells, provide evidence that paracrine mechanisms of growth factor action are important for the maintenance of KS. The reports on virus infection of KS cells suggest an indirect role of virus infection in the induction of KS, most likely mediated by immunostimulation and subsequent production of cytokines.

Knowledge about metabolisable energy (ME) intake is crucial for various experimental settings in rodent studies. ME considers faecal and renal energy losses. In particular, faecal energy excretion can vary considerably between differentially composed diets. Thus determination of faecal energy losses, i.e. apparent energy digestibility, is the most important experimental approach to determine ME. Predictive equations for ME such as Atwater factors or an equation for pigs, which are frequently employed for rodent feed, consider an average energy digestibility for nutrients and average renal losses for protein. Both equations, however, were never validated for rat feed. We therefore determined experimentally the digestibility of energy (experimentally determined digestible energy 2 5·2 kJ/g digestible protein) and nutrients of eleven natural and five purified rat diets and compared the present results with the predicted values. Compared with natural diets, digestibility of gross energy (GE) and nutrients was higher by about 20 % in the purified diets (P, 0·0001). Mean GE digestibility in natural diets amounted to 71·4 % (range 53·3 -83·5 %; n 11). Atwater factors predicted ME with satisfactory accuracy in purified diets. In contrast, for natural diets, only the equation for pig feed gave acceptable estimates of ME. Choosing an inappropriate predictive equation for ME resulted in considerable error. For prediction of ME in mixed rat feed, we propose to use the equation for pig feed for natural diets and Atwater factors for purified diets. If the equation for pig feed cannot be applied we suggest using the lower modified Atwater factors instead of the 'original' Atwater factors to estimate the ME of a diet.Rodent feed: Commercial diets: Digestibility of energy: Digestibility of nutrients: Metabolisable energy: Rats Energy intake and utilisation are crucial preconditions for a variety of different experimental settings. In particular, rodent studies which are not focused on mainly nutritional aspects frequently declare energy contents of employed diets as gross energy (GE). The GE of rodent feed is routinely determined during the commercial production process and the food manufacturer usually provides this information along with the diet. However, for many studies more precise information about the actually 'available' energy would be desirable and expedient. This 'available' energy is termed digestible energy (DE) or metabolisable energy (ME). Subtraction of non-digested energy in faeces from the GE content of a diet gives diet-specific values for DE. Further subtraction of the remaining energy in urine or energy loss by microbial gas production from the DE value then provides the ME content. Of note, predictive equations for ME, such as the Atwater factors, usually neglect losses by microbial gas production.In general, rodent diets can be formulated as natural or as purified diets. Natural diets are composed of mixed ingredients such as different grains or soyabean meal. In contrast, purified diets use constant manu...

An expert Working Group was set up in December 2000 to develop recommendations for users and industry on the evaluation of proper function and operation of individually ventilated cage (IVC) systems. The full report of their recommendations is in two parts—'Part 1: Test Instructions' and 'Part 2: Evaluation Criteria'—both of which have been published in full on the Laboratory Animals Ltd website. They can be found at http://www.lal.org.uk/IVC/index.html. Evaluation of and feedback on the recommendations to further refine their use and scientific basis is encouraged. This Summary Report provides a brief overview of the background to the development of the full report and the issues it addresses.