Mechanisms of urethral continence and their clinical application

Controversy about the basic nature of urethral function does not preclude accurate clinical assessment of disorders of function. While the precise method of treatment of urethral continence dysfunction varies from institution to institution, the basic techniques are quite similar. It is the application of a treatment method to a particular case which causes difficulty. It is important, therefore, to have some understanding of the functional elements in the urethral continence mechanism to be able to determine which element does not function. Most cases of intractable incontinence are associated with poor function of the involuntary part of the sphincter. In general, peak urethral closing pressures are unrelated to continence function unless there is no pressure at all.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47059/1/345_2004_Article_BF00326702.pd

Route of tracer administration does not affect real endogenous nitrogen recovery measured with the N-15-isotope dilution technique in pigs fed rapidly digestible diets

The N-15-isotope dilution technique (N-15-IDT), with either pulse-dose oral administration or continuous i.v. administration of [N-15]-L-leucine (carotid artery), both at 5 mg/(kg body weight . d), was used to measure ileal (postvalve T-cecum cannula) endogenous nitrogen recovery (ENR) in pigs (9 +/- 0.6 kg). Diets were cornstarch, enzyme-hydrolyzed casein with no (control) or high (4%) content of quebracho extract (Schinopsis spp.) rich in condensed tannins. Blood was sampled from a catheter in the external jugular vein. Mean plasma N-15-enrichment at d 8-10 was higher (P = 0.0009) after i.v. than after oral administration [0.0356 vs. 0.0379 atom% excess (APE)]. Plasma 15N-enrichment for i.v. infused pigs was 0.01117 APE higher (P <0.0001) and for orally dosed pigs 0.0081 APE lower (P <0.0001) at 11 h postprandial compared with 1 h postprandial. Apparent ileal N digestibility was higher (P <0.0001) for the control (85.5%) than for the quebracho diet (69.5%). ENR was calculated from the ratio of N-15-enrichment of plasma and digesta. The ENR for the quebracho diet was similar to300% higher than for the control diet (6.03 vs. 1.94 g/kg dry matter intake, P <0.001). The real N digestibility (92.2 +/- 0.4%) was equal for both diets (P = 0.1030) and both tracer methods (P = 0.9730). We concluded that oral administration of [N-15]leucine provides reasonable estimates of ENR in pigs fed semipurified diets with high or low content of tannins; however, one must be careful in extrapolating this conclusion to studies with other protein sources or feeding frequencies