Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis.

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.

Protein preservation and ruminal degradation of ensiled forage treated with heat, formic acid, ammonia, or microbial inoculant.

The objectives of this study were to determine whether treatment of forage with heat would reduce proteolysis during subsequent fermentation. In Experiment 1, direct-cut barley forage and alfalfa were untreated, microwaved, or steamed and then ensiled in laboratory silos as wilted forages. Silages of microwaved or steamed forage showed a marked increase in N bound to neutral detergent fiber and in the recovery of protein; however, alfalfa silages also had high pH values and concentrations of butyric acid. In Experiment 2, steam heating was compared with formic acid and NH3 treatments for the prevention of proteolysis in alfalfa silages. Silage of steamed alfalfa had a greater amount of N bound to neutral detergent fiber and greater recovery of protein than did control silage or silages of forage treated with formic acid or NH3. Silage of steamed forage had lower pH values than did silages of wilted, direct-cut, or control forage. Microbial innoculant added to steamed forage increased the recovery of protein. Silage of steamed forage had less aerobic stability than did silage of direct-cut forage. Ruminal degradability of crude protein (CP) and organic matter of silage from both experiments was evaluated. Degradability of CP was 8 to 26 percentage units lower in silages of microwaved or steamed forage in Experiment 1 than in silage of unheated forage because of slower degradation rates, but all had similar undegraded CP after incubation for 72 h. In Experiment 2, wilting, steam, formic acid, and NH3 treatments affected CP degradability similarly, but CP degradability was decreased when compared with silage of direct-cut forage without treatment.

Ornithine decarboxylase activity and actin polymerization in testosterone--stimulated mouse kidney.

Renal hypertrophy was induced in mice by injection of testosterone. Associated with an increase in renal tissue mass were increases in the concentrations of spermine and spermidine and in the activity of ornithine decarboxylase (ODC), the rate limiting enzyme in their synthesis. The increased activity of ODC was shown to be due to an increase in tissue ODC content. Total tissue actin was not altered by testosterone treatment although the proportion of unpolymerized (soluble) actin was increased significantly. These data are discussed in relation to the postulated mechanism of polyamine stimulation of actin polymerization.