The digestion of yeast cell wall polysaccharides in veal calves

1. The digestibility of the cell wall polysaccharides of an alkane-grown yeast in different parts of the digestive tract of two veal calves fitted with re-entrant cannulas at the end of the ileum was studied by replacing part of the skim-milk powder of their ‘normal’, milk-substitute (all-milk-protein) diet by yeast (yeast diet). 2. The lactose and glucose of both the all-milk-protein diet and the yeast diet were almost completely digested before the end of the ileum. During this digestion a small amount of oligosaccharides composed of galactose and glucose was synthesized. These oligosaccharides were digested again in the large intestine. 3. The constituent sugars of the water-soluble fraction of the yeast cell wall carbohydrates were glucose and mannose. The 0.5 m-sulphuric acid-hydrolysate of the water-insoluble fraction contained glucose and mannose and the 12 m-H2SO4-hydrolysate only glucose. 4. Digestibilities of these fractions over the whole gastrointestinal tract ranged from 0.77 to 0.90. Digestibilities measured at the end of the ileum varied considerably between the two animals and averaged only about 0.40. 5. These findings suggest that the cell wall polysaccharides of yeast are digested very little by the normal digestive enzymes of the calf's small intestine, but are used as a substrate by the bacterial flora which are mainly concentrated in the large intestine

Over de osmotische waarde en de gehalten aan enige opgeloste bestanddelen van de darminhoud en de mest bij het rund, in verband gebracht met de resorptie der mineralen

Osmotic pressure of the contents from various parts of the gut was related to the concentrations of Ca, Mg, NH 4+, Na, K, Cl, total carbonic acid, inorganic phosphate, sulphate and steam-volatile fatty acids in press-juice of gut contents and faeces of 16 cows.Abomasal contents were slightly hypotonic to the blood. The most important osmotically-active elements were Na and Cl.In the upper ileum the chyme was strongly hypertonic largely through organic non-electrolytes but also Na and Cl.Distally in the small intestine osmotic pressure gradually decreased and in the caecum they were almost isotonic with the blood, largely through Na and, to a lesser extent, K and NH 4+.Strong selective absorption of Na against a concentration gradient caused the hypotony of colonic contents and faeces. Re-absorption from the large intestine was important in the Na metabolism of the cow

Capturing complex tumour biology in vitro: Histological and molecular characterisation of precision cut slices

Precision-cut slices of in vivo tumours permit interrogation in vitro of heterogeneous cells from solid tumours together with their native microenvironment. They offer a low throughput but high content in vitro experimental platform. Using mouse models as surrogates for three common human solid tumours, we describe a standardised workflow for systematic comparison of tumour slice cultivation methods and a tissue microarray-based method to archive them. Cultivated slices were compared to their in vivo source tissue using immunohistochemical and transcriptional biomarkers, particularly of cellular stress. Mechanical slicing induced minimal stress. Cultivation of tumour slices required organotypic support materials and atmospheric oxygen for maintenance of integrity and was associated with significant temporal and loco-regional changes in protein expression, for example HIF-1α. We recommend adherence to the robust workflow described, with recognition of temporal-spatial changes in protein expression before interrogation of tumour slices by pharmacological or other means