A mathematical model of the ascending colon of the horse

Prediction of in vivo short-chain fatty acid production in hindgut fermenting mammals: problems and pitfalls

Short-chain fatty acids (SCFA) are considered to have important physiological functions. However, to prove this, SCFA must be determined, which is rather difficult as a lot of factors interfere with their production. This review focuses on the factors that influence the prediction of short-chain fatty acid formation in the large intestine of monogastric mammals. To mimic the in vivo situation, when predicting the amount of short-chain fatty acids produced from a certain substrate based on in vitro models, one has to estimate the amount of this substrate entering the large intestine, the retention time in the different parts of the large intestine, and the substrate fermentability. Instead of in vitro models, direct and indirect techniques may be used to measure short-chain fatty acid production in vivo. Direct techniques include the measurement of input and output or measuring differences in SCFA between portal and venous blood whereas indirect techniques measure the end products of fermentation. In this case, other factors have to be taken into account, including technical limitations and ethical considerations. In this review it is concluded that the choice for a method will rely on the purpose of the study taking into account the (dis)advantages of every method.

A geometric description of the urinary bladder of Turkish Shepherd dog (Karabaş)

In this study, a geometric and experimental work of the urinary bladder of a dog is presented. Experimentally, the diameters on the neck (collum vesicae region), the body (corpus vesicae region), the bottom (apex region) and the longitudinal length of the urinary bladder were measured. Geometrically it was shown that the urinary bladder is comparable with a surface of revolution of a planar (profile) curve. On the same regions of the modelled surface the diameters of the horizontal sections have been measured. It was found that the geometric and the experimental values were closely related. Further the Gaussian curvature K at certain points on the same regions of the modelled surface was calculated. The quadratic approximations of the urinary bladder surface was described with the sign of K at those points.