No abstract

Findings of this study indicate that development of gastric mucosal ulcers and ulceration of the nonglandular pars esophagea in pigs may be associated with gastric colonization by swine-origin Helicobacter spp, which are similar to H pylori isolated from humans.

No abstract

␤-Carotene is a naturally occurring carotenoid reported to have health-promoting effects in several species. Advancing age is known to have a negative impact on various immune variables in several species. This study was conducted in order to assess the effect of age on immune response in dogs and to determine whether ␤-carotene is able to reverse this age-associated decline. To test this hypothesis, young and old dogs (n ϭ 36) were fed either a control diet or experimental diets containing supplemental ␤-carotene for 2-month periods. Age significantly (P Ͻ .05) lowered CD4ϩ T cell populations (47.2% versus 33.7%; young-control versus old-control, respectively) and ␤-carotene restored percent distributions in old dogs to nonsignificance versus younger controls (41.0%). T cell proliferation was lower in old dogs (30,254 Ϯ 2,248 versus 14,811 Ϯ 2,497 cCPM; young-control versus oldcontrol, respectively; P Ͻ .05), and ␤-carotene supplementation significantly improved responses in this age group (21,329 Ϯ 2,275 cCPM). Although B cell proliferation was depressed with age (17,967 Ϯ 1,384 versus 7,535 Ϯ 1,469 cCPM; young-control versus old-control, respectively; P Ͻ .05), ␤-carotene supplementation improved B cell proliferation in young dogs (23,500 Ϯ 1,339 cCPM). Old dogs displayed lower delayed-type hypersensitivity test (DTH) responses versus younger controls to both phytohemagglutinin-P (PHA; 11.1 Ϯ 0.95 versus 7.57 Ϯ 1.15 mm; young-control versus old-control, respectively; P Ͻ .05) and sheep red blood cell (RBC; 9.12 Ϯ 0.62 versus 8.08 Ϯ 0.75 mm; young-control versus old-control, respectively; P Ͻ .10). ␤-Carotene improved these responses, mostly within the first 24-48 hours after injection. In summary, older dogs have lower immunological responses compared with younger controls. ␤-Carotene supplementation significantly restored immune responses in older dogs when compared with their age-matched controls and younger counterparts.

In the mouse system, acquired resistance to Listeria monocytogenes can only be demonstrated after immunization with viable microorganisms. A successful state of immunity cannot be elicited with formalin-killed organisms or bacterial cell-derived products. Viable, serologically cross-reactive organisms (not mouse pathogenic) do not induce a state of immunity as measured by acquired resistance. The duration of immunity, once established, is dose independent, and the absolute interval of its existence is not extended by secondary challenge with large numbers of viable organisms. The decline of immunity in actively immunized animals is not altered by antigenic challenge with formalin-killed cells or cell products. This indicates that the cellular requirements for the development of host resistance are similar for induction as well as maintenance. In vitro measurements of cellular immunity by migration inhibition indicate that formalin-killed organisms as well as cell products were recognized by actively sensitized lymphocytes obtained from immune animals.