Noninvasive determination of perfused artery dimensions ex vivo using a pressure-diameter relationship.

Based on the decisive effects of the hemodynamic and mechanical environments on the development and remodeling of arteries in vivo, several groups have cultured tissue-engineered vessels and excised vessels in various mechanically active perfusion systems. To facilitate the interpretation and design of such studies, accurate estimates of the applied forces and resulting stresses are required, which in turn require an accurate estimate of vessel dimensions. The measured pressure drop along the length of the vessel could be used to calculate the average inner diameter, but practical considerations, including the modest accuracy of many pressure transducers, limit this approach. Using nine porcine arteries harvested from pigs weighing between 25 and 100 kg, we show that when real-time measurements of the pressure drop and the outer diameter during a vasoactive event are fit to a theoretical model, offset errors in the pressure measurement can be compensated for and estimates of vessel wall transverse area with an average error of 4.1% (not exceeding 8.3%) are achieved.

A meatworks survey of bovine hydatidosis in southern Queensland.

A meatworks survey was undertaken in 1981-82 to define the distribution and prevalence of hydatidosis in beef cattle in southern Queensland. Hydatid cysts, mostly degenerate, were found in 14.6% of the 22,916 animals examined. The endemic area was to the east of a line approximating the 500 mm isohyet. Prevalence varied with age and origin of cattle, but not sex. Prevalence increased linearly with age, at least up to 4 years. Prevalence on the east coast ranged from 4.3% in yearlings to 52.2% in 4-year-old cattle. At the western limit of the endemic area, the prevalence ranged from 1.4% in yearlings to 10.8% in 4-year-olds. On the Darling Downs, prevalence was highest in areas where cattle raising is the main industry. On the south western Downs, where sheep-farming predominates, the prevalence in cattle was much lower, probably because of fewer dingoes. Livers only were affected in 46.5% of infected cattle, lungs only in 17.7%, and 35.8% of infected animals had both organs affected. Infection in other organs was uncommon. A detailed study of 133 infected cattle showed that 3.8% had lesions misdiagnosed as hydatid cysts at slaughter.