Thermal ablation of the goat mammary gland as a model for post-lumpectomy treatment of breast cancer: preliminary observations.

BACKGROUND: Partial breast irradiation post-lumpectomy, with a balloon bearing a radioactive source in its center, is practiced as an alternative to whole breast irradiation in the treatment of breast cancer. The goal is to ablate residual malignant cells within 1 cm radius of the resected lumpectomy margin. We hypothesize that this goal may be achieved with a fluid-filled heated balloon. METHODS: Nubian-cross goats were treated under general anesthesia. The two mammary glands were sequentially bisected and a non-inflated balloon with a heating element was placed in the center of the gland which was re-sutured. Two series of experiments were conducted. In the first 22 goats (44 glands), the balloon was inflated with 5% dextrose to a pressure of 150 mmHg and heated at 87 degrees C over selected time intervals of 1-24 minutes. In the second series (16 glands), the re-programmed device operated at 50-80 mmHg over selected time intervals of 5-20 minutes. The depth of necrosis was histologically determined after sacrificing the goats and excising the glands. RESULTS: In the first series, glandular necrosis was noted to extend to a depth of 3.2-9.6 mm for the above heating cycles. Corresponding figures for the second series ranged from 4.7-8.6 mm for treatment times of one minute 'warm up' to 20 minutes of heating at 90 degrees C. The animals exhibited no systemic side effects post-treatment. CONCLUSION: An experimental model describing a thermal technique causing necrosis of the goat mammary gland is described.

Opsonization of Staphylococcus aureus by bovine immunoglobulin isotypes.

The ability of specific bovine Ig isotypes to enhance phagocytosis of Staphylococcus aureus by polymorphonuclear neutrophils was studied. Polymorphonuclear neutrophils were isolated from the blood of 14 lactating Holstein cows. Antibodies against S. aureus M10 were produced by two Holstein cows immunized via intramuscular injections and injections in the area of the supramammary lymph node with M10 emulsified in dextran sulfate. The IgG1, IgG2, and IgM were prepared from immune sera. Fluorescein-labeled, formalin-killed S. aureus M10 were opsonized with the respective isotypes prior to incubation with polymorphonuclear neutrophils. Percentage of polymorphonuclear neutrophils phagocytosing averaged 37.4, 1.1, 15.9, and 9.4% for immune sera, IgG1, IgG2, and IgM, using a M10: polymorphonuclear neutrophils ratio of 10:1; and 77.1, 1.8, 32.1, and 57.9 using a 40:1 ratio. When IgG1 was incubated with either IgG2 or IgM, phagocytosis was reduced to 10.0 and 5.0%, respectively, using the 10:1 ratio and 24.2 and 44.7%, respectively, using the 40:1 ratio. Significant variation occurred among cows in the ability of polymorphonuclear neutrophils to undergo phagocytosis independent of isotype and S. aureus M10: polymorphonuclear neutrophil ratio. These data show that IgG2 and IgM are opsonic for bovine polymorphonuclear neutrophils and that IgG1 inhibits the activity of both. These results will be helpful to determine immunization protocols to solicit synthesis of bovine IgM and IgG2 specific for S. aureus.

Immunoglobulins, lysozyme and lactoferrin in the teat and udder of the dry cow during endotoxin-induced inflammation.

Immunoglobulins (Ig) and antibacterial proteins like lysozyme and lactoferrin are components of the humoral defence against infections. Changes in Ig, lysozyme and lactoferrin concentrations during endotoxin-induced inflammation in the test cistern and udder quarter of the dry cow were studied. Surgical closure of the passage between teat and udder cisterns enabled studies of reactions in the teat cistern without interference of the mammary gland. After endotoxin infusion, IgG1, IgG2, lysozyme, and to some extent IgM, increased in the teats and udder quarters, and were positively correlated with changes in somatic cell counts. No significant changes were observed in IgA or lactoferrin. The origin and significance of Ig, lysozyme and lactoferrin in the bovine teat and udder are discussed. Ig probably originated both from serum and from local plasma cells, while leukocytes appeared to be the source of lysozyme during inflammation. Secretory epithelium appeared to be the source of lactoferrin. Support for this theory was the almost total absence of lactoferrin in teat cistern samples.

Effect of anticapsular antibodies on neutrophil phagocytosis of Staphylococcus aureus.

One of the major virulence factors of Staphylococcus aureus is development of an exopolysaccharide capsule in vivo, which inhibits recognition of antibodies to highly antigenic cell wall by neutrophils. To circumvent this inhibition, an attempt was made to produce anticapsular antibodies. Three cows per group were immunized in midlactation by injections in the area of the supramammary lymph node and intramuscularly and were boosted on d 14, 42, and 70 with three variants of Smith S. aureus: compact, unencapsulated; diffuse, rigid capsule; and diffuse large clearing, exceptionally large flaccid capsule using dextran sulfate as adjuvant. Serum agglutination and ELISA titers of cows immunized with diffuse and diffuse large clearing increased after immunization and after each boost and remained elevated to the end of the experiment at 112 d. Phagocytosis of diffuse and diffuse large clearing, measured by flow cytometry, was enhanced by immunization with either organism. No antibody response to capsule or enhanced phagocytosis of diffuse developed in cows immunized with compact. However, anticompact antibodies were opsonic for diffuse large clearing. These data show that bovine antibodies to S. aureus capsule are opsonic for bovine neutrophils and that capsule plays a role in inhibition of cell-wall opsonization of S. aureus.