Death of Mycobacterium lepraemurium after multiplication in CBA, BALB/c and nude mice.

The unexpected death of Mycobacterium lepraemurium in the course of systemic infection of mice, previously noted in the spleens of CBA mice, has been demonstrated in the spleens of BALB/c nu/+ and BALB/c nu/nu mice and also in the livers and other organs of mice of all three strains. That the same phenomenon was observed in nu/nu mice indicates that the mechanism of bacterial death does not involve a T-lymphocyte-mediated cellular immune response on the part of the mice.

Respiratory disease in animal house workers.

A cross-sectional survey was made to determine the prevalence of respiratory disorders, and the association between symptoms and workplace exposure, in 90 animal-house workers (AHW) and 100 controls (C) without occupational exposure to laboratory animals. Each subject provided a detailed history and serum for radioimmunoassays, and underwent: physical examination, skin testing with common inhalant and animal-derived antigens, and pulmonary function studies. Both groups were comparable with respect to age, sex, smoking habits, and atopy. Rhinitis occurred with similar frequency in each group. However, a more frequent occurrence of asthma (p less than 0.05, non-specific infectious respiratory disease (p less than 0.005), and impaired pulmonary functions (p less than 0.001) was found among AHW. An atopic background was a predisposing factor for the development of laboratory-animal-related respiratory symptoms. These findings imply an increased vulnerability to respiratory disease related to workplace exposure to laboratory animals in atopic individuals.

Occupational respiratory disease in veterinarians.

In order to determine the effect of occupational animal exposure on the occurrence of respiratory disease, we studied 257 active veterinarians and 100 control subjects who had not had occupational animal contact. All participants provided a detailed medical history and underwent spirometry, skin tests, and determination of total serum IgE levels. Asthma was significantly more prevalent in veterinarians (16.3%) than in controls (6%), (P less than .05), as was infectious/obstructive respiratory disease, 10.5% in veterinarians, 3% in controls (P less than .025). Only 13 of 257 veterinarians had respiratory symptoms related to animal contact; of these, seven experienced only allergic rhinitis while six reported both asthma and rhinitis. Animal-related allergic rhinitis was found more frequently in laboratory animal veterinarians than among veterinarians in farm, pet, or poultry practice. No symptoms typical of hypersensitivity pneumonitis were reported in veterinarians, nor were precipitins to animal antigens demonstrable.

A dual effect of tilorone on multiplication of Mycobacterium leprae in mice.

Tilorone, a synthetic inducer of interferon found earlier to inhibit multiplication of Mycobacterium leprae in the foot pad of the mouse while it enhanced infections of mice by M. lepraemurium and M. marinum, has been shown to exert a dual effect on M. leprae infection of the mouse. When administered continuously, incorporated into the mouse diet in a concentration of 0.015 g per 100 g diet, the drug was usually immunosuppressive, permitting enhanced multiplication of the organisms. When administered in a 3-fold larger concentration beginning during the lag phase or early during logarithmic multiplication, tilorone was antimicrobial; however, when administered in the larger concentration beginning after logarithmic multiplication had been well established, the drug was immunosuppressive. The antimicrobial action of tilorone against M. leprae appears to be a direct action that is weak and slow in onset. The mechanism of the immunosuppressive action remains to be elucidated.

Experimental mycobacterial infections of CBA/N mice.

In an effort to assess the contribution of B-lymphocyte-mediated mechanisms to the immune responses to several mycobacteria, responses to these intracellular pathogens were compared in immunologically normal CBA/CaHN mice and in histocompatible CBA/N (Xid) mice, which exhibit abnormalities of B-lymphocyte function. Swelling in response to local inoculation with Mycobacterium marinum was significantly greater in the hind feet of CBA/CaHN mice than in those of CBA/N mice, but the difference was very small. Survival of mice of both strains after i.v. challenge with M. marinum or i.p. challenge with M. leprae-murium did not differ significantly. Finally, multiplication of M. leprae in the footpads of mice of both strains did not differ significantly. Thus, B-lymphocyte-mediated mechanisms do not appear to be important in the immune responses of mice in experimental infections with these mycobacterial species.

The Sabra rat: definition of a laboratory animal.

Study objectives were to provide investigators of the biomedical research community with comprehensive and reliable baseline data for the Sabra rat strain. In addition to a physiological, developmental, hematological and biochemical definition of this laboratory rat, widely used at the Hebrew University and other research laboratories in Israel, a historical insight offers some understanding of the origin and development of this strain. Data collected from 331 male and female rats over a 2-year period characterize the Sabra rat as a useful, stable, economical laboratory animal with good viability under conventional conditions.