Diagnostic exercise: papulovesicular dermatitis in rhesus macaques (Macaca mulatta).

Eleven rhesus monkeys developed multifocal erythematous and a vesicular rash. Most recovered spontaneously, but a 21-year-old female became moribund and was euthanized. Findings were of vesicular dermatitis and widespread multifocal hemorrhagic necrosis of the lungs and other viscera, with intralesional intranuclear inclusions. Simian varicella virus was identified as the cause by polymerase chain reaction analysis and serologic testing.

Rodent carcinogenicity with the thiazolidinedione antidiabetic agent troglitazone.

Carcinogenic potential of the thiazolidinedione antidiabetic troglitazone was assessed in 104-week studies in mice and rats. Mice were given 50, 400, or 800 mg/kg, male rats 100, 400, or 800 mg/kg, and female rats 25, 50, or 200 mg/kg. Vehicle and placebo controls were included. Survival was significantly decreased in both sexes of both species at high doses, but was adequate for valid evaluation of carcinogenicity. Hypertrophy and hyperplasia of brown adipose tissue was observed in both species at all doses, and fatty change and hypocellularity of bone marrow was noted in mice at all doses and in female rats at 50 and 200 mg/kg. Hepatocellular vacuolation was observed in mice at 400 and 800 mg/kg, and centrilobular hepatocellular hypertrophy occurred in rats at > or = 200 mg/kg. Ventricular dilatation, myocardial fibrosis, and atrial myocyte karyomegaly in male rats at 400 and 800 mg/kg and female rats at all doses were morphologically similar to spontaneous lesions, but incidence and severity were increased compared with controls. In mice, the incidence of hemangiosarcoma was increased in females at 400 mg/kg and in both sexes at 800 mg/kg. The incidence of hepatocellular carcinoma was increased in female mice at 800 mg/kg. Troglitazone exposure [AUC((0-24))] at the lowest dose associated with increased tumor incidence in mice was 16 times human therapeutic exposure at 400 mg daily. No tumors of any type were increased in rats at exposures up to 47 times therapeutic exposure.

p53 is not inactivated in B6C3F1 mouse vascular tumors arising spontaneously or associated with long-term administration of the thiazolidinedione troglitazone.

Hemangiomas and hemangiosarcomas are uncommon in rodents and humans and, as such, the mechanisms giving rise to these tumors are poorly understood. Inactivating mutations in the p53 gene have been detected in sporadic and chemically induced human and rodent hemangiosarcomas. Additionally, experimental ablation of p53 function in mice by targeted gene disruption increases the incidence of both spontaneous and carcinogen-induced vascular tumors. These findings implicate p53 disruption in vascular tumor development. In this study, we characterized p53 inactivation immunocytochemically and by gene sequencing in a large number of vascular tumors that developed in B6C3F1 mice during a long-term (2-year) study of the thiazolidinedione troglitazone. For comparative purposes, a murine hemangiosarcoma induced by polyoma middle-T antigen, which transforms endothelial cells via a p53-independent mechanism, five spontaneous human hemangiosarcoma specimens, and species-specific positive control tissues were also evaluated by immunocytochemistry for p53 inactivation. While 20% of the human hemangiosarcomas and all positive control tissues expressed significant levels of nuclear p53, indicating functional inactivation of the protein, none of the 161 mouse vascular tumors studied expressed detectable p53 protein. The absence of inactivating mutations was confirmed in eight of the histologically most malignant mouse hemangiosarcomas by sequencing exons 5 to 8 of the p53 gene. These results demonstrate that p53 inactivation did not play a role in development of the vascular tumors seen in the long-term study of troglitazone, and they indicate that loss of p53 function is not essential for vascular tumor development in mice.

Necrotic oophoritis in gilts associated with experimental inoculation of a viral gene-deletion mutant pseudorabies vaccine.

Previous work on the reproductive effects of various herpesviruses has demonstrated adverse effects on reproductive function in several host species. Although herpesviral vaccines are used in several species to ameliorate the clinical effects of infection, pathogenicity for reproductive tissue, associated with diminished reproductive efficiency, has been reported to be retained in a live-attenuated vaccine strain of the herpesvirus, bovine herpesvirus-1. The objective of this study was to determine if a gene-deletion mutant, thymidine kinase negative, pseudorabies virus retained acute pathogenicity for the reproductive tract of swine following intravenous inoculation during estrus. Estrous cycles of nulliparous gilts were synchronized by administration of a gonadotropin and daily exposure to a boar. During estrus, six gilts were inoculated intravenously with twice the recommended intramuscular dose of a commercially available viral gene-deletion mutant pseudorabies vaccine. Six control gilts in estrus were sham inoculated intravenously with vaccine diluent during estrus. All animals were euthanatized 10 days postinoculation, and the ovaries and uterus were collected for histopathology following gross examination. All reproductive tracts were grossly normal. Histologically, four of six treated gilts had a mild to moderate, multifocal, necrotizing oophoritis, with the lesions limited to corpora lutea and the adjacent stroma. Ovaries of control gilts exhibited to necrotizing lesions. Both control and pseudorabies vaccine-inoculated gilts had occasional minimal focal mononuclear infiltrates in the ovaries. These data show that live attenuated viral gene-deletion mutant pseudorabies vaccine administered to swine during estrus can result in acute pathogenicity in ovarian corpora lutea. No endocrinologic data is available in these pigs, so the impact on pregnancy maintenance is unknown.

Repression of SV40 T oncoprotein expression by DMSO.

SV40 large T oncoprotein-transformed murine mesenchymal 3T3 T stem cells (CSV3 cells) can be induced to growth arrest and then differentiate into adipocytes. When differentiation occurs, SV40 T oncoprotein expression is repressed (Estervig et al., J Virol 63:2718, 1989). To determine if repression of T oncoprotein expression can also be induced pharmacologically, the effect of a variety of agents that have been reported to effect differentiation in various cell types but not in 3T3 T or CSV3 cells was tested. This rationale suggests that if any of these agents repress T oncoprotein expression in CSV3 cells, then the results would establish that repression of T oncoprotein expression can be mediated by mechanisms independent of overt differentiation. The results show that dimethylsulfoxide (DMSO) is the only agent tested that represses T oncoprotein expression in CSV3 cells. Repression occurs in a dosage-dependent manner within 24-96 hours after exposure to DMSO. The effect of DMSO on T oncoprotein expression is mediated by posttranslational mechanisms that decrease the stability of the T oncoprotein. DMSO-induced repression of T oncoprotein expression is also associated with reversion of the transformed phenotype in CSV3 cells as demonstrated by the loss of responsiveness to a specific transformation-associated mitogen. These data support the conclusion that the pharmacological repression of T oncoprotein expression represents a form of cancer suppressor activity that can be mediated by a distinct molecular mechanism.

Pathophysiologic correlates of experimental trypanosomiasis in rabbits.

Rabbits inoculated subcutaneously with Trypanosoma brucei brucei developed parasitemia, fever, and reduced food and water intake within 4 to 6 days postinoculation. Subsequent alterations in clinicopathologic parameters included anemia and increased circulating nucleated red blood cells, fibrinogenemia, hypertriglyceridemia, and hyperproteinemia. Transient alterations in the numbers of neutrophils and lymphocytes were detected sporadically; however, leukocytosis was not a characteristic of this chronic infectious condition in rabbits.

Pharmacologic rationale for intravesical N-trifluoroacetyladriamycin-14-valerate (AD 32): a preclinical study.

Based on previous clinical findings following systemic administration, as well as appropriate laboratory evidence, the novel lipophilic anthracycline analogue N-Trifluoroacetyladriamycin-14-valerate (AD 32) has been identified as an agent of potential value in the intravesical therapy of superficial bladder carcinoma. Toward this end, using a rat model, the present study was designed to evaluate the potential for toxicity of a therapeutic dose of AD 32 given intravesically. With regard to systemic toxicity, following a single intravesical dose of AD 32 (20 mg/kg), the total systemic drug exposure (O-6 h), expressed as the area under the plasma concentration-time curve, was 14.2 micrograms min ml-1, or less than 1% of the corresponding value obtained when the identical dose was injected intravenously (2,392 micrograms min ml-1). In separate studies, a single intravenous dose of AD 32 (20 mg/kg) given to normal animals produced only a 20% reduction in white blood cell counts as compared with a 60% reduction following the administration of a therapeutic dose of Adriamycin (5 mg/kg); no effect was seen for either drug on red blood cell production. Taken together, these results imply that systemic drug exposure following the intravesical instillation of a therapeutic dose of AD 32 would result in negligible (approximately 0.2%) hematotoxic potential. Furthermore, intravesical instillation of AD 32 (20 mg/kg) at a concentration (10 mg/ml) greater than that projected for use in humans resulted in no evidence of contact toxicity to the rat bladder urothelium. Thus, based on experimental and clinical consideration of safety and efficacy, AD 32 appears to be an excellent candidate for the intravesical treatment of superficial bladder cancer.

Individual variability in tail tendon fiber break time in three age cohorts of different strains of mice.

Individual variability in mouse tail tendon fiber denaturation in urea was investigated. Differences in break time between fibers within tendons and between tendon groups were examined. Mean break times for each strain increased with age with the shorter-lived DBA/2 mice exhibiting higher break times within age cohorts than the C57BL/6 animals. Fibers from the two ventral tendon groups had consistently higher break times than those from the two dorsal groups, implying differential rates of collagen maturation between these two areas within the tail. Histological examination revealed conspicuous morphological dorsal/ventral differences in tendon number, proximity to a major blood vessel, and the amount of surrounding muscle tissue. These findings have methodological and experimental design implications for the use of tail tendon break time (TTBT) as a biomarker of aging. Furthermore, they suggest possible physiological mechanisms for differential rates of collagen aging.

Short-term exposure to nitrogen dioxide enhances susceptibility to murine respiratory mycoplasmosis and decreases intrapulmonary killing of Mycoplasma pulmonis.

In C57BL/6N and C3H/HeN mice known to be free of all murine pathogens and matched for age, sex, microbiologic, and environmental factors, exposure to NO2 for 4 h prior to exposure to infectious aerosols of Mycoplasma pulmonis resulted in potentiation of murine respiratory mycoplasmosis (MRM). In the C57BL/6N mice, NO2 increased the incidence of death, incidence of gross lung lesions, and incidence of microscopic lung lesions, but did not increase the incidence of infection in the lungs. Nitrogen dioxide affected the C3H/HeN mice (a strain known to be more susceptible than the C57BL/6N strain to MRM) similarly, with the exception that the incidence of death and microscopic lesions were not affected in this strain at the concentrations of M. pulmonis used. Exposure to the oxidant also increased the severity of microscopic lesions and the numbers of Mycoplasma organisms in the lungs of both mouse strains. Thus, NO2 appeared to affect host lung defense mechanisms responsible for limiting the extent of infection. The NO2 exposure level required to produce potentiation varied with the genetic background of the host, the number of Mycoplasma organisms administered, and the end point measured. In further experiments in C57BL/6N mice, exposure to 5 or 10 ppm of NO2 for 4 h prior to infection with aerosolized, radiolabeled M. pulmonis reduced clearance of these organisms from the lungs over a 72-h time period. Nitrogen dioxide exposure did not change the rate of physical removal of Mycoplasma organisms from the lung. Reduced clearance was due to impaired intrapulmonary killing of Mycoplasma organisms in NO2-exposed mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in virulence for mice among strains of Mycoplasma pulmonis.

The mouse model of acute murine respiratory mycoplasmosis was used to screen 18 strains of Mycoplasma pulmonis for their ability to establish respiratory infections and produce gross lung lesions in the susceptible C3H/HeN mouse strain. All experiments were designed to minimize host, environmental, and microbial differences to ensure that experimental results would reflect differences in mycoplasmal virulence. There were differences in the 50% infectious dose (range, 3 X 10(2) to greater than 10(7) CFU) and the 50% gross pneumonia dose (range, 10(3) to greater than 10(7) CFU) among the 18 mycoplasmal strains. Only 10 strains (UAB CT, M1, UAB 5782C, UAB 6510, 66, UAB T, UAB 8145D, Nelson C, Peter C, and Negroni) established respiratory infections, and only 2 of the 10 strains (UAB CT and M1) produced gross lung lesions. Strains UAB CT, UAB T, M1, UAB 5782C, and PG34(ASH) were chosen for qualitative and quantitative evaluation of lung lesions in C3H/HeN and C57BL/6N mice. Lesion incidence and severity was dependent on the mycoplasmal strain and the mouse strain. Microscopic lesions varied among mycoplasmal strains and mouse strains in the amount of lymphoid infiltrate, neutrophilic exudate, and consolidation, as well as overall severity. The most virulent strain, UAB CT, produced acute pneumonitis in the 10(7) CFU dosage group and required a threshold dose of 10(3) CFU to consistently produce microscopic lung lesions. These results suggest that M. pulmonis virulence is multifactorial and different strains of mycoplasmas yield disease expressions that differ both qualitatively and quantitatively.

Pulmonary clearance of Mycoplasma pulmonis in C57BL/6N and C3H/HeN mice.

In C57BL/6N and C3H/HeN mice known to be free of all murine pathogens and matched for age, sex, and environmental factors, pulmonary clearance was measured over a 72-h time period after exposure to infectious aerosols of 35S-labeled Mycoplasma pulmonis. Reduced clearance of M. pulmonis in C3H/HeN mice relative to C57BL/6N mice was primarily due to impaired mycoplasmacidal activity in the lungs of the C3H/HeN mice. The C3H/HeN mice also had a slightly slower rate of mechanical transport of radiolabel from the lungs in the first 4 h after infection relative to the C57BL/6N mice but not at any later times. By 72 h after infection (relative to 0 h, C3H/HeN mice had an over 4,000% (1.75 X 10(7) versus 4.30 X 10(5] increase in neutrophils and an over 18,000% (more than 2 orders of magnitude) increase in numbers of M. pulmonis recovered from mechanically disaggregated lungs. In contrast, C57BL/6N mice reduced the number of M. pulmonis present by over 83% (nearly 2 orders of magnitude) before any increase in inflammatory cells, which was only a slight increase in lymphocytes and macrophages at 24 h after infection. These results directly link decreased mycoplasmal pulmonary clearance in C3H/HeN mice with the increased susceptibility to, and severity of, murine respiratory mycoplasmosis observed in this strain. The resistance of C57BL/6N mice appears to be related to nonspecific host defense mechanisms responsible for limiting the extent of infection.

Development of an aerosol model of murine respiratory mycoplasmosis in mice.

Animal models of murine respiratory mycoplasmosis due to Mycoplasma pulmonis provide excellent opportunities to study respiratory disease due to an infectious agent. The purpose of the present study was to develop and characterize an aerosol model for the production of murine respiratory mycoplasmosis in mice. The exposure of mice for 30 min to aerosols generated with a DeVilbiss 45 nebulizer in a nose-only inhalation chamber consistently reproduced typical lesions. The chamber was operated with a nebulizer air flow of 5.3 liters/min at 5.0 lb/in and a diluting air flow of 20 liters/min, with the nebulizer containing 5 ml of a suspension of viable M. pulmonis organisms (a concentration between 6 X 10(5) to 6 X 10(10) CFU/ml). Infective aerosol particles of less than a 4.0-micron median aerodynamic diameter with a geometric standard deviation of approximately 2.0 reached the lungs and were evenly distributed among the different lung lobes. A minimum 1.5-log loss of viability in the M. pulmonis suspension was demonstrated. With the exception of the 50% lethal dose, all of the parameters previously established by intranasal inoculation could be examined with the aerosol model. The major advantages of the aerosol model were excellent reproducibility of exposure (both between different experiments and between animals in a given experiment), the avoidance of anesthetization, and the ability to immediately deposit the majority of the organisms in the lung. The only disadvantage was the requirement for large volumes of mycoplasmal cultures.

Strain differences in susceptibility to murine respiratory mycoplasmosis in C57BL/6 and C3H/HeN mice.

Not only is murine respiratory mycoplasmosis, due to Mycoplasma pulmonis, a complication of biomedical research, it provides excellent animal models to study the development of a naturally occurring respiratory disease induced by an infectious agent. The understanding of pathogenic mechanisms of disease can be greatly facilitated by studying genetic differences in susceptibility. Five strains of mice with various H-2K haplotypes were examined for their susceptibility to murine respiratory mycoplasmosis; of these, C57BL/6 and C3H/HeN mice were chosen for additional study. There were no significant differences in the incidence of infection in either the upper or lower respiratory tract or in the severity of upper respiratory tract lesions in the two strains as determined at 14 days postinfection. In striking contrast, the C57BL/6 mice were significantly more resistant to the development of gross and microscopic lung lesions and to death due to pneumonia as shown by an almost 100-fold difference in the 50% lethal dose, 50% gross pneumonia dose, and 50% microscopic lesion dose. The most apparent differences in lung lesions between the two strains were in the severity of acute lesions of the bronchial epithelium, the amount of mixed inflammatory response in the alveoli, and the amount of lymphoid infiltrates. All were significantly more severe in C3H/HeN mice. In addition, more C3H/HeN mice developed antibody responses to M. pulmonis. The amount of antibody correlated with lesion severity in both strains.

Endometriosis with bacterial peritonitis in a baboon.

An adult female Papio hamadryas being used in reproductive studies was found moribund unexpectedly. Palpation revealed acute abdominal pain and a pelvic mass. A tentative diagnosis of endometriosis and shock was made. Necropsy and histological examination confirmed the diagnosis of endometriosis and identified an associated bacterial peritonitis.