Immunogenicity and Efficacy of Live-Attenuated Salmonella Typhimurium Vaccine Candidate CVD 1926 in a Rhesus Macaque Model of Gastroenteritis.

Salmonella Typhimurium is a common cause of foodborne gastroenteritis and a less frequent but important cause of invasive disease, especially in developing countries. In our previous work, we showed that a live-attenuated S. Typhimurium vaccine (CVD 1921) was safe and immunogenic in rhesus macaques, although shed for an unacceptably long period (10 days) postimmunization. Consequently, we engineered a new strain, CVD 1926, which was shown to be safe and immunogenic in mice, as well as less reactogenic in mice and human cell-derived organoids than CVD 1921. In this study, we assessed the reactogenicity and efficacy of CVD 1926 in rhesus macaques. Animals were given two doses of either CVD 1926 or saline perorally. The vaccine was well-tolerated, with shedding in stool limited to a mean of 5 days. All CVD 1926-immunized animals had both a serological and a T cell response to vaccination. At 4 weeks postimmunization, animals were challenged with wild-type S. Typhimurium I77. Unvaccinated (saline) animals had severe diarrhea, with two animals succumbing to infection. Animals receiving CVD 1926 were largely protected, with only one animal having moderate diarrhea. Vaccine efficacy in this gastroenteritis model was 80%. S. Typhimurium vaccine strain CVD 1926 was safe and effective in rhesus macaques and shed for a shorter period than other previously tested live-attenuated vaccine strains. This strain could be combined with other live-attenuated Salmonella vaccine strains to create a pan-Salmonella vaccine.

Improved Tolerability of a Salmonella enterica Serovar Typhimurium Live-Attenuated Vaccine Strain Achieved by Balancing Inflammatory Potential with Immunogenicity.

A notable proportion of Salmonella-associated gastroenteritis in the United States is attributed to Salmonella enterica serovar Typhimurium. We have previously shown that live-attenuated S Typhimurium vaccine candidate CVD 1921 (I77 ΔguaBA ΔclpP) was safe and immunogenic in rhesus macaques but was shed for an undesirably long time postimmunization. In mice, occasional mortality postvaccination was also noted (approximately 1 in every 15 mice). Here we describe a further attenuated vaccine candidate strain harboring deletions in two additional genes, htrA and pipA We determined that S Typhimurium requires pipA to elicit fluid accumulation in a rabbit ileal loop model of gastroenteritis, as an S Typhimurium ΔpipA mutant induced significantly less fluid accumulation in rabbit loops than the wild-type strain. New vaccine strain CVD 1926 (I77 ΔguaBA ΔclpP ΔpipA ΔhtrA) was assessed for inflammatory potential in an organoid model of human intestinal mucosa, where it induced less inflammatory cytokine production than organoids exposed to the precursor vaccine, CVD 1921. To assess vaccine safety and efficacy, mice were given three doses of CVD 1926 (109 CFU/dose) by oral gavage, and at 1 or 3 months postimmunization, mice were challenged with 700 or 100 LD50 (50% lethal doses), respectively, of wild-type strain I77. CVD 1926 was well tolerated and exhibited 47% vaccine efficacy following challenge with a high inoculum and 60% efficacy after challenge with a low inoculum of virulent S Typhimurium. CVD 1926 is less reactogenic yet equally as immunogenic and protective as previous iterations in a mouse model.

Animal models that best reproduce the clinical manifestations of human intoxication with organophosphorus compounds.

The translational capacity of data generated in preclinical toxicological studies is contingent upon several factors, including the appropriateness of the animal model. The primary objectives of this article are: 1) to analyze the natural history of acute and delayed signs and symptoms that develop following an acute exposure of humans to organophosphorus (OP) compounds, with an emphasis on nerve agents; 2) to identify animal models of the clinical manifestations of human exposure to OPs; and 3) to review the mechanisms that contribute to the immediate and delayed OP neurotoxicity. As discussed in this study, clinical manifestations of an acute exposure of humans to OP compounds can be faithfully reproduced in rodents and nonhuman primates. These manifestations include an acute cholinergic crisis in addition to signs of neurotoxicity that develop long after the OP exposure, particularly chronic neurologic deficits consisting of anxiety-related behavior and cognitive deficits, structural brain damage, and increased slow electroencephalographic frequencies. Because guinea pigs and nonhuman primates, like humans, have low levels of circulating carboxylesterases-the enzymes that metabolize and inactivate OP compounds-they stand out as appropriate animal models for studies of OP intoxication. These are critical points for the development of safe and effective therapeutic interventions against OP poisoning because approval of such therapies by the Food and Drug Administration is likely to rely on the Animal Efficacy Rule, which allows exclusive use of animal data as evidence of the effectiveness of a drug against pathologic conditions that cannot be ethically or feasibly tested in humans.

A peptide antagonist of CD28 signaling attenuates toxic shock and necrotizing soft-tissue infection induced by Streptococcus pyogenes.

Staphylococcus aureus and group A Streptococcus pyogenes (GAS) express superantigen (SAg) exotoxin proteins capable of inducing lethal shock. To induce toxicity, SAgs must bind not only to the major histocompatibility complex II molecule of antigen-presenting cells and the variable ß chain of the T-cell receptor but also to the dimer interface of the T-cell costimulatory receptor CD28. Here, we show that the CD28-mimetic peptide AB103 (originally designated "p2TA") protects mice from lethal challenge with streptococcal exotoxin A, as well as from lethal GAS bacterial infection in a murine model of necrotizing soft-tissue infection. Administration of a single dose of AB103 increased survival when given up to 5 hours after infection, reduced inflammatory cytokine expression and bacterial burden at the site of infection, and improved muscle inflammation in a dose-dependent manner, without compromising cellular and humoral immunity. Thus, AB103 merits further investigation as a potential therapeutic in SAg-mediated necrotizing soft-tissue infection.

STAT6 expression in multiple cell types mediates the cooperative development of allergic airway disease.

Th2 cells induce asthma through the secretion of cytokines. Two such cytokines, IL-4 and IL-13, are critical mediators of many features of this disease. They both share a common receptor subunit, IL-4Rα, and signal through the STAT6 pathway. STAT6(-/-) mice have impaired Th2 differentiation and reduced airway response to allergen. Transferred Th2 cells were not able to elicit eosinophilia in response to OVA in STAT6(-/-) mice. To clarify the role of STAT6 in allergic airway inflammation, we generated mouse bone marrow (BM) chimeras. We observed little to no eosinophilia in OVA-treated STAT6(-/-) mice even when STAT6(+/+) BM or Th2 cells were provided. However, when Th2 cells were transferred to STAT6×Rag2(-/-) mice, we observed an eosinophilic response to OVA. Nevertheless, the expression of STAT6 on either BM-derived cells or lung resident cells enhanced the severity of OVA-induced eosinophilia. Moreover, when both the BM donor and recipient lacked lymphocytes, transferred Th2 cells were sufficient to induce the level of eosinophilia comparable with that of wild-type (WT) mice. The expression of STAT6 in BM-derived cells was more critical for the enhanced eosinophilic response. Furthermore, we found a significantly higher number of CD4(+)CD25(+)Foxp3(+) T cells (regulatory T cells [Tregs]) in PBS- and OVA-treated STAT6(-/-) mouse lungs compared with that in WT animals suggesting that STAT6 limits both naturally occurring and Ag-induced Tregs. Tregs obtained from either WT or STAT6(-/-) mice were equally efficient in suppressing CD4(+) T cell proliferation in vitro. Taken together, our studies demonstrate multiple STAT6-dependent and -independent features of allergic inflammation, which may impact treatments targeting STAT6.

Origins of US Government Principles for the Utilization and Care of Vertebrate Animals Used in Testing, Research, and Training.

The US Government Principles for the use of animals in research are a landmark statement of ethical values and guidance for the biomedical research community. However, when The Principles were introduced, a context was not provided for their source or foundation. The US Government Principles were formulated with input from the Council of Europe, World Health Organization, and US Interagency Research Animal Committee. The Principles continue to provide an ethical foundation for the biomedical research community.

The Evaluation of the Containment Efficacy of Semi-Rigid Isolators for Housing Cages of Laboratory Animals Infected With BSL-3 Agents.

Research animals models infected with Biosafety Level-3 (BSL-3) agents need to be housed in specialized biocontainment caging. Most of these specialized cages have input and exhaust that is high efficiency particulate air filtered and sealed to prevent escape of the BSL-3 agent. An alternative to the use of the above BSL-3 biocontainment caging is the use of a flexible film or modified semi-rigid plastic film isolator that has its own high efficiency particulate air-filtered input and exhaust and is sealed with respect to the animal room environment, thus preventing BSL-3 agent escape. Standard caging can be housed within such an isolator. Computational fluid dynamics was used to evaluate the integrity of modified semi-rigid isolators for containment of aerosolized BSL-3 agents. Three isolators were located inside an animal BSL-3 room to provide an extra tier of protection and to permit different infectious studies within the same room while reducing or eliminating the risk of cross-contamination. The isolators were sized to house caging for rabbits and smaller non-human primates such as marmosets, African greens, and macaques. Multiple case studies of failure scenarios were investigated, including isolator breaches through the plastic membrane seam separation and rips, and exhaust fan failure. Breaching the level of containment provided by the isolators required the improbable simultaneous event of a plastic membrane rip in addition to the rare malfunction of the back-up exhaust fans. Each isolator was equipped with 2 blower motors connected in parallel to a common exhaust plenum and a battery backup. Even with this rare double (simultaneous) event, the animal BSL-3 room air exhaust system was able to contain the few droplets released in the simulated computational fluid dynamics breach. The modified semi-rigid isolators with negative airflow proved safe and effective for aerosol studies using BSL-3 agents, even in the unlikely event of a breach in containment.

Expression of neuroimmune semaphorins 4A and 4D and their receptors in the lung is enhanced by allergen and vascular endothelial growth factor.

BACKGROUND: Semaphorins were originally identified as molecules regulating a functional activity of axons in the nervous system. Sema4A and Sema4D were the first semaphorins found to be expressed on immune cells and were termed "immune semaphorins". It is known that Sema4A and Sema4D bind Tim-2 and CD72 expressed on leukocytes and PlexinD1 and B1 present on non-immune cells. These neuroimmune semaphorins and their receptors have been shown to play critical roles in many physiological and pathological processes including neuronal development, immune response regulation, cancer, autoimmune, cardiovascular, renal, and infectious diseases. However, the expression and regulation of Sema4A, Sema4D, and their receptors in normal and allergic lungs is undefined. RESULTS: Allergen treatment and lung-specific vascular endothelial growth factor (VEGF) expression induced asthma-like pathologies in the murine lungs. These experimental models of allergic airway inflammation were used for the expression analysis of immune semaphorins and their receptors employing immunohistochemistry and flow cytometry techniques. We found that besides accessory-like cells, Sema4A was also detected on bronchial epithelial and smooth muscle cells, whereas Sema4D expression was high on immune cells such as T and B lymphocytes. Surprisingly, under inflammation various cell types including macrophages, lymphocytes, and granulocytes in the lung expressed Tim-2, a previously defined marker for Th2 cells. CD72 was found on lung immune, inflammatory, and epithelial cells. Bronchial epithelial cells were positive for both plexins, whereas some endothelial cells selectively expressed Plexin D1. Plexin B1 expression was also detected on lung DC. Both allergen and VEGF upregulated the expression of neuroimmune semaphorins and their receptors in the lung tissue. However, the lung tissue Sema4A-Tim2 expression was rather weak, whereas Sema4D-CD72 ligand-receptor pair was vastly upregulated by allergen. Soluble Sema4D protein was present in the lung lysates and a whole Sema4A protein plus its dimer were readily detected in the bronchoalveolar (BAL) fluids under inflammation. CONCLUSIONS: This study clearly shows that neuroimmune semaphorins Sema4A and Sema4D and their receptors might serve as potential markers for the allergic airway inflammatory diseases. Our current findings pave the way for further investigations of the role of immune semaphorins in inflammation and their use as potential therapeutic targets for the inflammatory lung conditions.

Unusual Myoid Differentiation in a Canine Benign Mixed Mammary Tumour.

This report describes an unusual mesenchymal differentiation in a canine benign mixed mammary tumour. A 13-year-old crossbreed female dog was submitted to surgery to remove an inguinal mammary nodule. The tumour was composed of mammary epithelium and mesenchymal populations, not only of cartilage and bone but also of myoid cells. PTAH demonstrated cross striation of striated muscle, and immunohistochemistry highlighted striated muscle expressing desmin and calponin, and smooth muscle expressing desmin, SMA, and calponin. The tumour was diagnosed as a benign mixed tumour with leio- and rhabdomyoid differentiation. There was no tumour recurrence after one year of clinical follow-up. In conclusion, the well-differentiated features of leiomyocytes and rhabdomyocytes and the growth pattern define the benign origin of the mesenchymal component, which has been confirmed by a benign outcome; therefore, the knowledge of this kind of differentiation is helpful to avoid misdiagnoses.

Pathogenic, but Not Nonpathogenic, Rickettsia spp. Evade Inflammasome-Dependent IL-1 Responses To Establish an Intracytosolic Replication Niche.

Rickettsia species (spp.) are strict obligate intracellular bacteria, some of which are pathogenic in their mammalian host, including humans. One critical feature of these stealthy group of pathogens is their ability to manipulate hostile cytosolic environments to their benefits. Although our understanding of Rickettsia cell biology and pathogenesis is evolving, the mechanisms by which pathogenic Rickettsia spp. evade host innate immune detection remain elusive. Here, we show that disease severity in wild-type (WT) C57BL/6J mice infected with Rickettsia typhi (the etiologic agent of murine typhus) and Rickettsia rickettsii (the etiologic agent of Rocky Mountain spotted fever), but not with the nonpathogenic species Rickettsia montanensis, correlated with levels of bacterial burden as detected in the spleens of mice, as well as the serum concentrations of proinflammatory cytokine interleukin-1α (IL-1α) and, to a lesser extent, IL-1ß. Antibody-mediated neutralization of IL-1α confirmed a key role in controlling mortality rates and bacterial burdens of rickettsia-infected WT mice. As macrophages are a primary source of both IL-1α and IL-1ß cytokines, we determined the mechanism of the antirickettsial activities using bone marrow-derived macrophages. We found that pathogenic R. typhi and R. rickettsii, but not nonpathogenic R. montanensis, eluded pro-IL-1α induction and benefited predominantly from the reduced IL-1α secretion, via a caspase-11-gasdermin D (Gsdmd)-dependent pathway, to facilitate intracytosolic replication. Adoptive transfer experiments identified that IL-1α secretion by macrophages was critical for controlling rickettsiosis in WT mice. In sum, we identified a previously unappreciated pathway by which pathogenic, unlike nonpathogenic, rickettsiae preferentially target the caspase-11-Gsdmd-IL-1α signaling axis in macrophages, thus supporting their replication within the host. IMPORTANCE Currently, no vaccines are available to prevent rickettsioses, while vector-borne rickettsial infections in humans are on the rise globally. In fact, the insufficient understanding of how pathogenic Rickettsia species circumvent host immune defense mechanisms has significantly hindered the development of more effective therapeutics. Here, we identified a previously unappreciated role for the caspase-11-Gsdmd-IL-1α signaling axis in limiting the replication of pathogenic R. rickettsia and R. typhi species in murine macrophages and wild-type (WT) C57BL/6J mice. Adoptive transfer studies further identified IL-1α-secreting macrophages as critical mediators in controlling rickettsial infection in WT mice. Collectively, these findings provide insight into the potential mechanism of how pathogenic, but not nonpathogenic, Rickettsia spp. benefit from a reduction in the caspase-11-Gsdmd-mediated release of IL-1α to support host colonization.

Fit for Purpose Assessment: A New Direction for IACUCs.

The organization and function of the institutional animal care and use committee (IACUC) is the key component of government regulation and oversight of necessary scientific research using live animals and of AAALAC - International accreditation of animal care and use programs in the United States. The regulations, roles, and responsibilities of IACUCs have evolved since their inception 35 years ago from a limited focus on animal welfare and specific animal procedures to embracing scientific quality, data reproducibility and translation, and animal welfare as inextricably interdependent and critical components of generation of new scientific knowledge and medical treatments. A current challenge for IACUCs is in evaluating whether benefits to be derived (eg, new knowledge or treatments) justify any unavoidable pain, stress, or injury associated with proposed research protocols, because the former are long-term and at best speculative outcomes, whereas the latter are immediate and tangible for the study animals. Scientific consensus is that research most likely to generate significant new knowledge and medical treatments is that conducted to high scientific, technical, and quality standards and reported with full transparency to facilitate reproducibility. As an alternative to current benefits evaluations included in risk benefit and harm benefit constructs, the authors propose that IACUCs assess the proposed research for scientific quality and alignment of study elements with the study purpose (e.g., Fit for Purpose [FfP]), including justifications for study design components, selection of primary endpoints and technologies, rationale for data and statistical analyses, and research communication plans. Fit for Purpose endpoints are objective, immediate, and impactful as are the potential risks for study animals, and at the same time they are the best predictors for achievement of longer-term benefits. We propose that IACUCs and any revision of The ILAR Guide consider FfP concepts in place of traditional benefits assessment to accelerate the generation of new knowledge and treatments benefiting medical and veterinary patients and the environment through better science and animal welfare rather than to continue to rely on speculative future outcomes.

Effect of inositol hexaphosphate on the development of UVB-induced skin tumors in SKH1 hairless mice.

Inositol hexaphosphate (IP6) is a naturally occurring polyphosphorylated carbohydrate that is abundant in many plants and in various high-fiber foods, such as cereals and legumes. IP6 has a striking, broad-spectrum anticancer activity in various in vitro and animal models, in which it interferes with key pathways in malignancy to inhibit cell proliferation, cell-cycle progression, metastasis, invasion, and angiogenesis and to induce apoptosis. In this study, we investigated the protective effects of IP6 in drinking water on the incidence of UVB-induced skin cancer in the SKH1 (Crl: SKH1-hr) mouse model. One group of 15 mice received 2% IP6 in drinking water and UVB exposure, and the other group (n = 15) received UVB exposure only. All mice in both groups were fed an IP6-deficient diet (AIN 76A). The treatment group started receiving 2% IP6 in the drinking water 3 d before irradiation. Mice were irradiated 3 times each week, starting at a dose of 1.5 kJ/m2, with weekly increases in increments of 1.5 kJ/m2 to a final dose of 7.5 kJ/m2. Tumor formation was monitored until the week 31. IP6 in drinking water significantly decreased tumor incidence by 5-fold and tumor multiplicity by 4-fold. These results show that IP6 has an antiphotocarcinogenic effect and can protect against UVB-induced tumor formation.

Suspected Lonely Mouse Syndrome as a Cage Effect in a Drug Safety Study.

Studies have demonstrated that buprenorphine, a front line drug for veterinary analgesia, may alleviate symptoms of chronic pain. A cage side observation protocol was used to record behavioral signs in a mouse clinical trial of extended release buprenorphine. A retrospective review of the observations for signs of pain and stress revealed that mice given a fivefold overdose of buprenorphine (16.25 mg/kg) showed lethargy and facial signs associated with stress. However, similar signs were observed in the drug-free control mice as early as Day 3 of single-cage housing. This appears to be the first report of cage effects in a clinical trial for a veterinary drug.

Complete Genome Sequences of Mycobacterium kansasii Strains Isolated from Rhesus Macaques.

Mycobacterium kansasii is a nontuberculous mycobacterium. It causes opportunistic infections with pulmonary and extrapulmonary manifestations. We report here the complete genome sequences of two M. kansasii strains isolated from rhesus macaques. We performed genome comparisons with human and environmental isolates of M. kansasii to assess the genomic diversity of this species.

Virulence of invasive Salmonella Typhimurium ST313 in animal models of infection.

Salmonella Typhimurium sequence type (ST) 313 produces septicemia in infants in sub-Saharan Africa. Although there are known genetic and phenotypic differences between ST313 strains and gastroenteritis-associated ST19 strains, conflicting data about the in vivo virulence of ST313 strains have been reported. To resolve these differences, we tested clinical Salmonella Typhimurium ST313 and ST19 strains in murine and rhesus macaque infection models. The 50% lethal dose (LD50) was determined for three Salmonella Typhimurium ST19 and ST313 strains in mice. For dissemination studies, bacterial burden in organs was determined at various time-points post-challenge. Indian rhesus macaques were infected with one ST19 and one ST313 strain. Animals were monitored for clinical signs and bacterial burden and pathology were determined. The LD50 values for ST19 and ST313 infected mice were not significantly different. However, ST313-infected BALB/c mice had significantly higher bacterial numbers in blood at 24 h than ST19-infected mice. ST19-infected rhesus macaques exhibited moderate-to-severe diarrhea while ST313-infected monkeys showed no-to-mild diarrhea. ST19-infected monkeys had higher bacterial burden and increased inflammation in tissues. Our data suggest that Salmonella Typhimurium ST313 invasiveness may be investigated using mice. The non-human primate results are consistent with clinical data, suggesting that ST313 strains do not cause diarrhea.

Mycobacterium kansasii Isolated from Tuberculinpositive Rhesus Macaques (Macaca mulatta) in the Absence of Disease.

Mycobacterial infections are of primary health concern in NHP colonies in biomedical research. NHP are constantly monitored and screened for Mycobacterium spp. We report 6 Chinese-origin rhesus macaques infected with Mycobacterium kansasii that exhibited positive tuberculin skin tests in the absence of disease. Two of these macaques were being used for research purposes; the remaining 4 macaques were residing at the contract quarantine company. Histopathology and acid-fast staining of fixed tissues from all macaques showed that all were free of disease. Thoracic radiographs were negative for any signs of disease or infection. Samples from bronchial lavage and tissues including lung, spleen, hilar and mesenteric lymph nodes tested negative by PCR assay for Mycobacterium spp. One of the research macaques tested culture-positive for M. kansasii and a poorly characterized M. avium complex organism. One macaque from the contract quarantine facility tested culture positive for M. kansasii. Genomic testing and target gene RNA expression analysis of the 2 M. kansasii isolates were performed to evaluate possible kinship and affected genes that might contribute to susceptibility to mycobacterial infection. Genotyping of the 2 isolates revealed 2 genetically distinct strains (strains 1 and 4). The presence of positive tuberculin skin tests in the absence of disease raises serious concerns regarding diagnostic methods used for infected NHP.

Chronic ingestion of (3R,3'R,6'R)-lutein and (3R,3'R)-zeaxanthin in the female rhesus macaque.

PURPOSE: To investigate how supplementation of the monkey's diet with high doses of lutein (L), zeaxanthin (Z), or a combination of the two affects the plasma levels and ocular tissue deposition of these carotenoids and their metabolites over time and to determine whether these high doses can cause ocular toxicity. METHODS: Eighteen female rhesus monkeys were divided into groups of control (n = 3 control), L-treated (n = 5, 9.34 mg lutein/kg and 0.66 mg zeaxanthin/kg), Z-treated (n = 5, 10 mg zeaxanthin/kg), and L/Z-treated (n = 5, lutein and zeaxanthin, each 0.5 mg/kg). After 12 months of daily supplementation, one control animal, two L-treated animals, two Z-treated animals, and all the L/Z-treated animals were killed. The rest of the monkeys were killed after an additional six months without supplementation. Plasma and ocular tissue carotenoid analyses, fundus photography, and retina histopathology were performed on the animals. RESULTS: Supplementation of monkeys with L and/or Z increased the mean plasma and ocular tissue concentrations of these carotenoids and their metabolites. The mean levels of L and Z in the retinas of the L- and Z-treated animals after 1 year increased significantly over baseline. High dose supplementation of monkeys with L or Z did not cause ocular toxicity and had no effect on biomarkers associated with kidney toxicity. CONCLUSIONS: The mean levels of L and Z in plasma and ocular tissues of the rhesus monkeys increase with supplementation and in most cases correlate with the levels of their metabolites. Supplementation of monkeys with L or Z at high doses, or their combination does not cause ocular toxicity.

Clinical Trypanosoma cruzi Disease after Cardiac Transplantation in a Cynomolgus Macaque (Macaca fascicularis).

A cynomolgus macaque received a heterotopic cardiac allograft as part of a transplant study, with monoclonal antibodies targeted to specific immune costimulation molecules (CD154, CD28) but no traditional immunosuppressive therapy after surgery. Clinical anemia was detected on postoperative day (POD) 35 and had worsened (Hgb, 2.3 g/dL; Hct = 7.3%) by POD 47, despite type-matched whole-blood transfusions. After a total of 4 blood transfusions, hematologic parameters were improved (Hgb, 5.9 g/dL; Hct, 18.7%). On POD 50, a peripheral blood smear revealed trypomastigotes, and qualitative RT-PCR of whole blood identified the organism as Trypanosoma cruzi. Although clinically stable initially, the macaque soon developed sufficient weight loss to necessitate euthanasia on POD 64. The final diagnosis was clinical anemia due to T. cruzi infection. This study represents the first reported case of Chagas disease after heart transplant in a NHP.

Spatial learning impairment in prepubertal guinea pigs prenatally exposed to the organophosphorus pesticide chlorpyrifos: Toxicological implications.

Exposure of the developing brain to chlorpyrifos (CPF), an organophosphorus (OP) pesticide used extensively in agriculture worldwide, has been associated with increased prevalence of cognitive deficits in children, particularly boys. The present study was designed to test the hypothesis that cognitive deficits induced by prenatal exposure to sub-acute doses of CPF can be reproduced in precocial small species. To address this hypothesis, pregnant guinea pigs were injected daily with CPF (25mg/kg,s.c.) or vehicle (peanut oil) for 10days starting on presumed gestation day (GD) 53-55. Offspring were born around GD 65, weaned on postnatal day (PND) 20, and subjected to behavioral tests starting around PND 30. On the day of birth, butyrylcholinesterase (BuChE), an OP bioscavenger used as a biomarker of OP exposures, and acetylcholinesterase (AChE), a major molecular target of OP compounds, were significantly inhibited in the blood of CPF-exposed offspring. In their brains, BuChE, but not AChE, was significantly inhibited. Prenatal CPF exposure had no significant effect on locomotor activity or on locomotor habituation, a form of non-associative memory assessed in open fields. Spatial navigation in the Morris water maze (MWM) was found to be sexually dimorphic among guinea pigs, with males outperforming females. Prenatal CPF exposure impaired spatial learning more significantly among male than female guinea pigs and, consequently, reduced the sexual dimorphism of the task. The results presented here, which strongly support the test hypothesis, reveal that the guinea pig is a valuable animal model for preclinical assessment of the developmental neurotoxicity of OP pesticides. These findings are far reaching as they lay the groundwork for future studies aimed at identifying therapeutic interventions to treat and/or prevent the neurotoxic effects of CPF in the developing brain.

Mammary ductal carcinoma with comedo pattern in a rhesus macaque.

A 23-year-old female rhesus macaque presented with a 2.5-cm diameter, firm, moveable, lobulated subcutaneous mass associated with a supranummary teat on the right side of the chest. This animal was a retired breeder, currently in an aging study. No exogenous hormone treatments were noted in the animal's history. Chest radiographs were within normal limits. Blood screens showed no noteworthy variations from normal. Needle aspirate cytology showed clusters of neoplastic cells. Grossly the mass was well circumscribed, firm, and homogeneously tan, with a glandular appearance. Differential diagnoses included sebaceous or mammary adenoma, carcinoma in situ, and lobular or ductular carcinoma. Histopathology was consistent with a mammary ductal carcinoma with comedo pattern. Subsequent needle aspirate cytology from an adjacent right axillary lymph node showed tumor cells with a few lymphoid cells, interpreted as lymphatic spread. Chest radiographs 2 and 6 weeks postbiopsy showed no evidence of pulmonary metastasis. After 1 year, there was no marked change on chest radiographs, but a small cluster of new nodules was palpable in the right axillary region. Histopathology of an excisional biopsy of the new nodules indicated tumor growth subjacent to regional lymph nodes. Further treatment was not performed and the animal remained clinically normal five years after the initial diagnosis. Spontaneous mammary neoplasia is a major concern in human medicine, yet it rarely has been reported to occur in nonhuman primates. This case is important in documenting an additional case of spontaneous mammary tumor development.