A comparison of gross pathology, histopathology, and mycobacterial culture for the diagnosis of tuberculosis in elk (Cervus elaphus).

Using the isolation of Mycobacterium bovis as the reference standard, this study evaluated the sensitivity, specificity and kappa statistic of gross pathology (abattoir postmortem inspection), histopathology, and parallel or series combinations of the two for the diagnosis of tuberculosis in 430 elk and red deer. Two histopathology interpretations were evaluated: histopathology I, where the presence of lesions compatible with tuberculosis was considered positive, and histopathology II, where lesions compatible with tuberculosis or a select group of additional possible diagnoses were considered positive. In the 73 animals from which M. bovis was isolated, gross lesions of tuberculosis were most often in the lung (48), the retropharyngeal lymph nodes (36), the mesenteric lymph node (35), and the mediastinal lymph nodes (16). Other mycobacterial isolates included: 11 M. paratuberculosis, 11 M. avium, and 28 rapidly growing species or M. terrae complex. The sensitivity estimates of gross pathology and histopathology I were 93% (95% confidence limits [CL] 84.97%) and 88% [CL 77.94%], respectively, and the specificity of both was 89% [CL 85.92%]). The sensitivity and specificity of histopathology II were 89% (CL 79.95%) and 77% (CL 72.81%), respectively. The highest sensitivity estimates (93-95% [CL 84.98%]) were obtained by interpreting gross pathology and histopathology in parallel (where an animal had to be positive on at least one of the two, to be classified as combination positive). The highest specificity estimates (94-95% [CL 91-97%] were generated when the two tests were interpreted in series (an animal had to be positive on both tests to be classified as combination positive). The presence of gross or microscopic lesions showed moderate to good agreement with the isolation of M. bovis (Kappa = 65-69%). The results showed that post-mortem inspection, histopathology and culture do not necessarily recognize the same infected animals and that the spectra of animals identified by the tests overlaps.

Effects of dietary protein, energy and tyrosine on central and peripheral norepinephrine turnover in mice.

Norepinephrine (NE) turnover rate and tyrosine concentrations were assessed in several tissues of 5-wk-old female lean mice that were fed diets of 20% protein (1.2% tyrosine), 40% protein (2.4% tyrosine) or tyrosine-supplemented diets of 40% protein with 4 or 8% tyrosine or 20% protein with 4% tyrosine for 4 d. Mice fed the 40% protein diet had significantly lower NE turnover rates in interscapular brown adipose tissue, heart and kidney (66, 64 and 49%, respectively) and nonsignificantly lower (84%) turnover rate in brain than did mice fed the 20% protein diet, but plasma and tissue tyrosine concentrations did not differ. When energy intake of the 20% protein-fed mice was restricted to 92% of the 40% protein-fed mice, tyrosine concentration in plasma and tissues was lower by half, but NE turnover rate did not differ between the two groups. Supplementation of the 40 or 20% diets with tyrosine, resulting in twofold higher plasma and tissue tyrosine concentrations, had no effect on NE turnover rate in any organ examined. We conclude that both energy intake and dietary protein concentration affect sympathetic nervous system activity in young mice. Tyrosine does not mediate or alter these changes.