The use of 212Pb-labeled monoclonal antibody in the treatment of murine erythroleukemia.

PURPOSE: The goals of this study were to learn whether the DOTA chelator was useful for targeting lead radionuclides (203,212 Pb) to cells and tissues invaded by the Rauscher leukemia virus (RVB3) and to investigate the therapeutic efficacy of targeted 212Pb in treating the murine leukemia. METHODS AND MATERIALS: Five to 6-week-old BALB/c mice were inoculated i.v. with RVB3. This virus causes marked splenomegaly and death by day 13 and day 70 postinfection, respectively. Biodistribution, tumor targeting, and toxicity studies were performed using varying doses of 212Pb-DOTA-103A. A heavy metal chelator, DMPS, was administered orally and parenterally in two phases of the toxicity study. RESULTS: Biodistribution studies showed marked tumor targeting (58% ID/g spleen) in mice treated with 203Pb-103A as compared with mice treated with control antibody B3 (4.6% ID/g spleen). Histologic cure was achieved in all leukemic mice treated with 20 muCi212Pb-103A; however, all of the mice died with leukopenia and secondary++ bacterial infections due to severe bone marrow toxicity. Nonleukemic mice and mice treated with 20 muCi212Pb-B3 experienced less marrow toxicity and longer survival. Coadministration of the heavy metal chelator did not diminish the bone marrow toxicity. CONCLUSION: An effective, nonlethal dose could not be established to treat this tumor. The severe bone marrow toxicity associated with this radionuclide may limit its usefulness in systemic radioimmunotherapy.

Effects of buprenorphine on immunogenicity and protective efficacy in the guinea pig keratoconjunctivitis model (Sereny test).

Shigellosis is a disease of global proportions, with an estimated 164.7 million episodes annually throughout the world as well as an estimated 1.1 million associated mortalities in developing countries. Due to increasing incidence, and continued emergence of multi-drug resistant strains, Shigella vaccine development is considered a top public health priority. The guinea pig keratoconjunctivitis model, the basis for the Sereny test, remains the most reliable in vivo indicator of virulence of Shigella strains and immunogenicity and protective efficacy of Shigella vaccine candidates. The model is effective in evaluating the ability of Shigella strains to invade the corneal epithelia of guinea pigs and spread to contiguous cells, with the more virulent strains causing ulcerative keratoconjunctivitis. However, analgesia is not routinely used to relieve this painful condition because of potential immunomodulation and confounding of experimental results. The objective of the study reported here was to evaluate use of buprenorphine hydrochloride as an analgesic during the Sereny test. Local and systemic immune responses were measured in guinea pigs given buprenorphine versus those responses in controls. Results of this study suggest that buprenorphine, administered at an analgesic dose of 0.05 mg/kg of body weight twice daily, can be successfully used with the model without significantly affecting immunologic evaluation of Shigella vaccine candidates. However, in buprenorphine-treated animals, there was a significant increase in the amount of mucopurulent ocular discharge, requiring frequent cleaning of the affected eyes. Additionally, animals treated with buprenorphine had significant reduction in body weight, in comparison with saline controls.

Evaluation of objects and food for environmental enrichment of NZW rabbits.

The Guide for the Care and Use of Laboratory Animals states that both structural and social environments should be considered when addressing the husbandry needs of laboratory animals. The purpose of this study was to investigate environmental enrichment strategies that could potentially enhance the well-being of rabbits. Male and female 6-week old New Zealand White rabbits were divided into three groups: food-enriched (Bunny Stix, Bunny Blocks, or celery), non-food enriched (Jingle Ball, Kong toy, or Nylabone), and not enriched. Animals were given a particular enrichment for 1 h daily for 15 days. Home cages were fitted with specially designed plexiglass doors, which allowed the animals' interactions with the objects to be videotaped. The amount of time the animal interacted with each object and the total activity during the 1-h taped session were recorded for each rabbit. Rabbits were weighed weekly. Rabbits spent significantly more time interacting with the Bunny Stix than any other food item or non-food object. In addition, total activity time was significantly greater for all rabbits enriched with food versus any of the non-food items. Weight gains after 15 days did not differ significantly, but there was a trend towards increased weight gains in food-enriched rabbits. In this study, food was a stronger, more sustained enrichment device than were non-food objects.

Evaluation of surrogate markers of impending death in the galactosamine-sensitized murine model of bacterial endotoxemia.

BACKGROUND AND PURPOSE: When evaluating vaccines for efficacy against gram-negative endotoxemia, the challenge has historically required death of a large percentage of test subjects. We attempted to identify surrogate markers of impending death to allow for early euthanasia without interfering with experimental data collection. METHODS: Galactosamine-sensitized mice (n = 140) were inoculated intraperitoneally with various dosages of endotoxin, and development of clinical signs of disease--body temperature, body weight, hunched posture, ruffled coat, inability to ambulate, and loss of consciousness--was evaluated. RESULTS: Wide fluctuations in body temperature (+/- 4 degrees C) were observed in survivors and nonsurvivors. Posture, coat, and body weight were not accurate predictors of death. Only inability to ambulate, with a positive predictive value of 100% (11 of 11), accurately predicted death in the experimental mice of this study. CONCLUSION: Using this surrogate marker, loss of ability to ambulate, 11 of 13 mice that developed this sign could have been euthanized early, preventing anywhere from 2 to 22 h of potential distress prior to death.

Comparison of adjuvants with Leishmania antigens in a guinea pig model to induce delayed-type hypersensitivity responses.

BACKGROUND AND PURPOSE: Guinea pigs have been a traditional model for studies of delayed-type hypersensitivity. They are the natural host of Leishmania enriettii and have been experimentally infected with other species of Leishmania. They have been used as a skin-test model to screen potential antigens for use in diagnostic tests for Leishmania. Use of complete Freund's adjuvant (CFA), along with whole promastigote Leishmania antigen, was necessary to sensitize guinea pigs to invoke a sufficient cell-mediated immune response. However, use of CFA has come under scrutiny by Animal Care and Use Committees due to the pathologic changes associated with its use. METHODS: Thirty-two specific-pathogen-free male Hartley guinea pigs were inoculated with Leishmania antigens alone or mixed with one of three adjuvants (CFA, TiterMax, and liposomes), and were skin tested 2 weeks later. RESULTS: For the Leishmania antigens tested, guinea pigs that received liposomes as an adjuvant had skin-test responses comparable to those of guinea pigs that received CFA. TiterMax was also tested, but cellular responses at antigen test sites were poor. CONCLUSIONS: Liposomes can be used in this model as a safe, effective adjuvant.