The IFIH1-A946T risk variant promotes diabetes in a sex-dependent manner

Type 1 diabetes (T1D) is an autoimmune disease in which pancreatic islet β-cells are attacked by the immune system, resulting in insulin deficiency and hyperglycemia. One of the top non-synonymous single-nucleotide polymorphisms (SNP) associated with T1D is in the interferon-induced helicase C domain-containing protein 1 (IFIH1), which encodes an anti-viral cytosolic RNA sensor. This SNP results in an alanine to threonine substitution at amino acid 946 (IFIH1A946T) and confers an increased risk for several autoimmune diseases, including T1D. We hypothesized that the IFIH1A946T risk variant, (IFIH1R) would promote T1D pathogenesis by stimulating type I interferon (IFN I) signaling leading to immune cell alterations. To test this, we developed Ifih1R knock-in mice on the non-obese diabetic (NOD) mouse background, a spontaneous T1D model. Our results revealed a modest increase in diabetes incidence and insulitis in Ifih1R compared to non-risk Ifih1 (Ifih1NR) mice and a significant acceleration of diabetes onset in Ifih1R females. Ifih1R mice exhibited a significantly enhanced interferon stimulated gene (ISG) signature compared to Ifih1NR, indicative of increased IFN I signaling. Ifih1R mice exhibited an increased frequency of plasma cells as well as tissue-dependent changes in the frequency and activation of CD8+ T cells. Our results indicate that IFIH1R may contribute to T1D pathogenesis by altering the frequency and activation of immune cells. These findings advance our knowledge on the connection between the rs1990760 variant and T1D. Further, these data are the first to demonstrate effects of Ifih1R in NOD mice, which will be important to consider for the development of therapeutics for T1D.

The IFIH1-A946T risk variant promotes diabetes in a sex-dependent manner

Type 1 diabetes (T1D) is an autoimmune disease in which pancreatic islet β-cells are attacked by the immune system, resulting in insulin deficiency and hyperglycemia. One of the top non-synonymous single-nucleotide polymorphisms (SNP) associated with T1D is in the interferon-induced helicase C domain-containing protein 1 ( IFIH1 ), which encodes an anti-viral cytosolic RNA sensor. This SNP results in an alanine to threonine substitution at amino acid 946 (IFIH1 A946T ) and confers an increased risk for several autoimmune diseases, including T1D. We hypothesized that the IFIH1 A946T risk variant, ( IFIH1 R ) would promote T1D pathogenesis by stimulating type I interferon (IFN I) signaling leading to immune cell alterations. To test this, we developed Ifih1 R knock-in mice on the non-obese diabetic (NOD) mouse background, a spontaneous T1D model. Our results revealed a modest increase in diabetes incidence and insulitis in Ifih1 R compared to non-risk Ifih1 ( Ifih1 NR ) mice and a significant acceleration of diabetes onset in Ifih1 R females. Ifih1 R mice exhibited a significantly enhanced interferon stimulated gene (ISG) signature compared to Ifih1 NR , indicative of increased IFN I signaling. Ifih1 R mice exhibited an increased frequency of plasma cells as well as tissue-dependent changes in the frequency and activation of CD8 + T cells. Our results indicate that IFIH1 R may contribute to T1D pathogenesis by altering the frequency and activation of immune cells. These findings advance our knowledge on the connection between the rs1990760 variant and T1D. Further, these data are the first to demonstrate effects of Ifih1 R in NOD mice, which will be important to consider for the development of therapeutics for T1D.

Vaginal Suppositories Containing SHetA2 to Treat Cervical Dysplasia: Pharmacokinetics of Daily Doses and Preliminary Safety Profile

SHetA2 is a new drug with potential to treat cervical dysplasia, but only 0.02% of the dose is absorbed into the cervix after oral administration. By contrast, 23.9% of the dose is absorbed into the cervix after vaginal administration. This study determines the pharmacokinetic and pharmacodynamic parameters after daily vaginal doses of SHetA2 in suppositories and assesses its safety. Daily dosed mice maintained therapeutic concentrations of SHetA2 in the cervix for 65 h. The steady-state area under the curve concentration versus time (AUC_cervix) after the last dose was similar to that after a single dose indicating that there was no drug accumulation in the cervix. By contrast, the maximum drug concentration (C_max-cervix) was smaller in the daily dosed group (52.19 μg/g) than after a single dose (121.84 μg/g), whereas the half-life (t_1/2-cervix) was also shorter in the daily dosed group (9.94 h) than after a single dose (23.32 h). Notably, daily vaginal doses of SHetA2 reduced the levels of cyclin D1 (the pharmacodynamic endpoint) to a larger extent (∼45%) than after the administration of a single dose (∼26%). No adverse effects were observed in the mice for the duration of the study; thus, daily vaginal doses of SHetA2 appear to be safe.

Influence of the estrus cycle of the mouse on the disposition of SHetA2 after vaginal administration

SHetA2 is a novel compound with the potential to treat cervical dysplasia, but has poor water solubility. A vaginal suppository formulation was able to achieve therapeutic concentrations in the cervix of mice, but these concentrations were variable. Histological analysis indicated that mice in the same group were in different stages of their estrous cycle, which is known to induce anatomical changes in their gynecological tissues. We investigated the effects of these changes on the pharmacokinetics and pharmacodynamics of SHetA2 when administered vaginally. Mice were synchronized to be either in estrous or diestrus stage for administration of the SHetA2 suppository. Pharmacokinetic parameters were calculated from the SHetA2 concentrations vs. time data. The reduction in the expression of cyclin D1 protein in the cervix was used as pharmacodynamic endpoint. Mice dosed during diestrus had a larger AUC_cervix (335 μg mL h^-1), higher C_max (121.8 ± 38.7 µg/g) and longer t_1/2-cervix (30.3 h) compared to mice dosed during estrus (120 μg mL h^-1, 44.6 ± 29.5 µg/g and 3.6 h respectively). Therapeutic concentrations of SHetA2 were maintained for 48 h in the cervix of mice dosed during diestrus and for only 12 h in the estrus group. The treatment reduced the expression of cyclin D1 protein in the cervix of mice in the estrus to a larger extent. These results indicate that the estrous cycle of mice influences significantly the disposition of SHetA2 after vaginal administration and may also influence its efficacy.

DMBA promotes ErbB2‑mediated carcinogenesis via ErbB2 and estrogen receptor pathway activation and genomic instability

Environmental factors, including 7,12‑dimethylbenz[a]anthracene (DMBA) exposure, and genetic predisposition, including ErbB2 overexpression/amplification, have been demonstrated to increase breast cancer susceptibility. Although DMBA‑ and ErbB2‑mediated breast cancers are well‑studied in their respective models, key interactions between environmental and genetic factors on breast cancer risk remain unclear. Therefore, the present study aimed to investigate the effect of DMBA exposure on ErbB2‑mediated mammary tumorigenesis. MMTV‑ErbB2 transgenic mice exposed to DMBA (1 mg) via weekly oral gavage for 6 weeks exhibited significantly enhanced mammary tumor development, as indicated by reduced tumor latency and increased tumor multiplicity compared with control mice. Whole mount analysis of premalignant mammary tissues from 15‑week‑old mice revealed increased ductal elongation and proliferative index in DMBA‑exposed mice. Molecular analyses of premalignant mammary tissues further indicated that DMBA exposure enhanced epidermal growth factor receptor (EGFR)/ErbB2 and estrogen receptor (ER) signaling, which was associated with increased mRNA levels of EGFR/ErbB2 family members and ER‑targeted genes. Furthermore, analysis of tumor karyotypes revealed that DMBA‑exposed tumors displayed more chromosomal alterations compared with control tumors, implicating DMBA‑induced chromosomal instability in tumor promotion in this model. Together, the data suggested that DMBA‑induced deregulation of EGFR/ErbB2‑ER pathways plays a critical role in the enhanced chromosomal instability and promotion of ErbB2‑mediated mammary tumorigenesis. The study highlighted gene‑environment interactions that may increase risk of breast cancer, which is a critical clinical issue.

Safety assessment of the dietary supplement OxyELITE™ Pro (New Formula) in inbred and outbred mouse strains

Herbal dietary supplements have gained wide acceptance as alternatives to conventional therapeutic agents despite concerns regarding their efficacy and safety. In 2013, a spate of severe liver injuries across the United States was linked to the dietary supplement OxyELITE Pro-New Formula (OEP-NF), a multi-ingredient product marketed for weight loss and exercise performance enhancement. The principal goal of this study was to assess the hepatotoxic potential of OEP-NF in outbred and inbred mouse models. In an acute toxicity study, significant mortality was observed after administering 10X and 3X mouse-equivalent doses (MED) of OEP-NF, respectively. Increases in liver/body weight ratio, ALT and AST were observed in female B6C3F₁ mice after gavaging 2X and 1.5X MED of OEP-NF. Similar findings were observed in a 90-day feeding study. These alterations were paralleled by altered expression of gene- and microRNA-signatures of hepatotoxicity, including Cd36, Nqo1, Aldoa, Txnrd1, Scd1 and Ccng1, as well as miR-192, miR-193a and miR-125b and were most pronounced in female B6C3F₁ mice. Body weight loss, observed at week 1, was followed by weight gain throughout the feeding studies. These findings bolster safety and efficacy concerns for OEP-NF, and argue strongly for implementation of pre-market toxicity studies within the dietary supplement industry.

Short-term early exposure to lapatinib confers lifelong protection from mammary tumor development in MMTV-erbB-2 transgenic mice

BACKGROUND

Although chemopreventative agents targeting the estrogen/estrogen receptor (ER) pathway have been effective for ER⁺ breast cancers, prevention of hormone receptor-negative breast cancers, such as Her2/erbB-2⁺ breast cancers, remains a significant issue. Previous studies have demonstrated that administration of EGFR/erbB-2-targeting lapatinib to MMTV-erbB-2 transgenic mice inhibited mammary tumor development. The prevention, however, was achieved by prolonged high dose exposure. The tolerance to high dose/long-term drug administration may hinder its potential in clinical settings. Therefore, we aimed to test a novel, short-term chemopreventative strategy using lapatinib during the premalignant risk window in MMTV-erbB-2 mice.

METHODS

We initially treated cultured cells with lapatinib to explore the anti-proliferative effects of lapatinib in vitro. We used a syngeneic tumor graft model to begin exploring the in vivo anti-tumorigenic effects of lapatinib in MMTV-erbB-2 mice. Then, we tested the efficacy of brief exposure to lapatinib (100 mg/kg/day for 8 weeks), beginning at 16 weeks of age, in the prevention of mammary tumor development in MMTV-erbB-2 mice.

RESULTS

In the syngeneic tumor transplant model, we determined that lapatinib significantly inhibited tumor cell proliferation. Furthermore, we demonstrated that short-term lapatinib exposure resulted in life-long protective effects, as supported by increased tumor latency in lapatinib-treated mice compared to the control mice. We further established that delayed tumor development in the treated mice was preceded by decreased BrdU nuclear incorporation and inhibited mammary morphogenesis. Molecular analysis indicated that lapatinib inhibited phosphorylation and expression of EGFR, erbB-3, erbB-2, Akt1, and Erk1/2 in premalignant mammary tissues. Also, lapatinib drastically inhibited the phosphorylation and expression of ERα and the transcription of ER target genes in premalignant mammary tissues. We also determined that lapatinib suppressed the stemness of breast cancer cell lines, as evidenced by decreased tumorsphere formation and ALDH⁺ cell populations.

CONCLUSIONS

Taken together, these data demonstrate that brief treatment with EGFR/erbB-2-targeting agents before the onset of tumors may provide lifelong protection from mammary tumors, through the concurrent inhibition of erbB-2 and ER signaling pathways and consequential reprogramming. Our findings support further clinical testing to explore the benefit of shorter lapatinib exposure in the prevention of erbB-2-mediated carcinogenesis.

Cardiac myosin-Th17 responses promote heart failure in human myocarditis

In human myocarditis and its sequela dilated cardiomyopathy (DCM), the mechanisms and immune phenotype governing disease and subsequent heart failure are not known. Here, we identified a Th17 cell immunophenotype of human myocarditis/DCM with elevated CD4⁺IL17⁺ T cells and Th17-promoting cytokines IL-6, TGF-β, and IL-23 as well as GM-CSF-secreting CD4⁺ T cells. The Th17 phenotype was linked with the effects of cardiac myosin on CD14⁺ monocytes, TLR2, and heart failure. Persistent heart failure was associated with high percentages of IL-17-producing T cells and IL-17-promoting cytokines, and the myocarditis/DCM phenotype included significantly low percentages of FOXP3⁺ Tregs, which may contribute to disease severity. We demonstrate a potentially novel mechanism in human myocarditis/DCM in which TLR2 peptide ligands from human cardiac myosin stimulated exaggerated Th17-related cytokines including TGF-β, IL-6, and IL-23 from myocarditic CD14⁺ monocytes in vitro, and an anti-TLR2 antibody abrogated the cytokine response. Our translational study explains how an immune phenotype may be initiated by cardiac myosin TLR ligand stimulation of monocytes to generate Th17-promoting cytokines and development of pathogenic Th17 cells in human myocarditis and heart failure, and provides a rationale for targeting IL-17A as a therapeutic option.

Defective selection of thymic regulatory T cells accompanies autoimmunity and pulmonary infiltrates in Tcra-deficient mice double transgenic for human La/Sjögren's syndrome-B and human La-specific TCR

A human La/Sjögren's syndrome-B (hLa)-specific TCR/hLa neo-self-Ag double-transgenic (Tg) mouse model was developed and used to investigate cellular tolerance and autoimmunity to the ubiquitous RNA-binding La Ag often targeted in systemic lupus erythematosus and Sjögren's syndrome. Extensive thymic clonal deletion of CD4(+) T cells occurred in H-2(k/k) double-Tg mice presenting high levels of the I-E(k)-restricted hLa T cell epitope. In contrast, deletion was less extensive in H-2(k/b) double-Tg mice presenting lower levels of the epitope, and some surviving thymocytes were positively selected as thymic regulatory T cells (tTreg). These mice remained serologically tolerant to hLa and healthy. H-2(k/b) double-Tg mice deficient of all endogenous Tcra genes, a deficiency known to impair Treg development and function, produced IgG anti-hLa autoantibodies and displayed defective tTreg development. These autoimmune mice had interstitial lung disease characterized by lymphocytic aggregates containing Tg T cells with an activated, effector memory phenotype. Salivary gland infiltrates were notably absent. Thus, expression of nuclear hLa Ag induces thymic clonal deletion and tTreg selection, and lymphocytic infiltration of the lung is a consequence of La-specific CD4(+) T cell autoimmunity.

Simian T-lymphotropic Virus-associated lymphoma in 2 naturally infected baboons: T-cell clonal expansion and immune response during tumor development

Two young female baboons naturally infected with simian T-lymphotropic virus type 1 (STLV1) were euthanized due to chronic respiratory disease that was unresponsive to treatment. Massive lymphocytic infiltration of the lung interstitium suggested a diagnosis of STLV-associated lymphoma. In each case, the diagnosis was confirmed through inverse PCR (IPCR) that detected monoclonally integrated STLV1 provirus in cellular DNA extracted from lymphoma tissue and peripheral blood cells (PBC). One dominant STLV1-infected T-cell clone and 3 minor clones were detected in PBC from each baboon. Using archived PBC DNA and primers within the proviral genome and chromosomal DNA flanking the STLV1 integration sites in PCR analyses, we determined that the dominant clone in one baboon had first appeared approximately 8 mo after infection and had circulated for 4 y before clinical disease developed. ELISA testing of archived serum revealed that both baboons seroconverted to the p19 and p24 gag proteins and the envelope gp46 protein but not to the viral tax protein. Titers to p24 and gp46 rose significantly after infection and remained relatively constant until death, whereas titers to p19 increased with time. Although spontaneous STLV1-associated lymphomas have been described in baboons, the STLV1-associated lymphomas described here occurred in 2 relatively young baboons, both of whom had become infected with STLV at 3 to 4 y of age and developed lymphoma within 5 y of infection.

Suppression and activation of the malignant phenotype by extracellular matrix in xenograft models of bladder cancer: a model for tumor cell "dormancy"

A major problem in cancer research is the lack of a tractable model for delayed metastasis. Herein we show that cancer cells suppressed by SISgel, a gel-forming normal ECM material derived from Small Intestine Submucosa (SIS), in flank xenografts show properties of suppression and re-activation that are very similar to normal delayed metastasis and suggest these suppressed cells can serve as a novel model for developing therapeutics to target micrometastases or suppressed cancer cells. Co-injection with SISgel suppressed the malignant phenotype of highly invasive J82 bladder cancer cells and highly metastatic JB-V bladder cancer cells in nude mouse flank xenografts. Cells could remain viable up to 120 days without forming tumors and appeared much more highly differentiated and less atypical than tumors from cells co-injected with Matrigel. In 40% of SISgel xenografts, growth resumed in the malignant phenotype after a period of suppression or dormancy for at least 30 days and was more likely with implantation of 3 million or more cells. Ordinary Type I collagen did not suppress malignant growth, and tumors developed about as well with collagen as with Matrigel. A clear signal in gene expression over different cell lines was not seen by transcriptome microarray analysis, but in contrast, Reverse Phase Protein Analysis of 250 proteins across 4 cell lines identified Integrin Linked Kinase (ILK) signaling that was functionally confirmed by an ILK inhibitor. We suggest that cancer cells suppressed on SISgel could serve as a model for dormancy and re-awakening to allow for the identification of therapeutic targets for treating micrometastases.

Infant baboons infected with respiratory syncytial virus develop clinical and pathological changes that parallel those of human infants

Respiratory syncytial virus (RSV) infection of the lower respiratory tract is the leading cause of respiratory failure among infants in the United States of America and annually results in >300,000 deaths worldwide. Despite the importance of RSV, there is no licensed vaccine, and no specific form of therapy. This is largely due to the absence of an appropriate animal model for the evaluation of vaccines and therapeutic agents. We inoculated anesthetized infant (4 wk) baboons (Papio anubis) with a human strain of RSV intranasally or intratracheally. Baboons were monitored daily for clinical changes. Anesthetized baboons were intubated at various intervals, and bronchoalveolar lavage (BAL) was performed for viral culture and determination of leukocyte counts. Sham-infected baboons served as controls. Necropsies were performed on infected baboons on days 1, 3, 5, 8, or 13 after inoculation, with pathological analysis and immunohistochemical staining of lung tissues to detect RSV antigen. Infected baboons developed tachypnea and reduced oxygenation peaking from 4 to 8 days after infection and persisting for ≥14 days. Virus was recoverable in BAL fluid up to 8 days following infection. Necropsy revealed intense interstitial pneumonia, sloughing of the bronchiolar epithelium, and obstruction of the bronchiolar lumen with inflammatory cells and sloughed epithelial cells. RSV antigen was identified in bronchiolar and alveolar epithelium. We conclude that RSV-infected infant baboons develop clinical and pathological changes that parallel those observed in human infants with RSV infection. The infant baboon represents a much-needed model for studying the pathogenesis of RSV infection and evaluating antivirals and vaccines.

Efficacy of a Gal-lectin subunit vaccine against experimental Entamoeba histolytica infection and colitis in baboons (Papio sp.)

To determine the efficacy of a Gal-lectin based intranasal synthetic peptide vaccine, we developed a new experimental primate model of Entamoeba histolytica intestinal infection. Release of xenic E. histolytica trophozoites (5×10(6)) into the small bowel of baboons (Papio sp.) resulted in a rapid intestinal anti-amebic antibody response and a brief infection; however, release of trophozoites directly into the cecum (5 baboons) elicited a sustained E. histolytica infection, as determined by quantitative fecal PCR, and an ulcerative, inflammatory colitis observed on colonoscopy and histopathology. In three controlled experiments, baboons received four immunizations at seven day intervals of 1600 μg of the vaccine/nostril, with Cholera toxin, 20 μg/nostril as adjuvant; vaccinated (n=6) and control baboons (n=6) baboons were then challenged via colonoscopy with xenic trophozoites (5×10(6)). During 90 days of follow up, 250 of 415 (60.24%) fecal samples in control baboons had a (+) PCR for E. histolytica, compared to only 36 of 423 (8.51%) samples from vaccinated baboons (P<0.001). All 6 vaccinated baboons were free of infection by the 51st day after challenge, 5 of 6 controls positive had (+) fecal PCRs for up to 126 days post-challenge (P=0.019). Inflammatory colitis developed in 4 of 6 control baboons post-challenge, with invasive E. histolytica trophozoites present in 2 of the 4 on histopathology. There was no evidence of inflammatory colitis or parasite invasion in any of the vaccinated baboons; there was a strong inverse correlation between positive ELISA OD value indicating the presence of intestinal anti-peptide IgA antibodies and baboons having a positive fecal PCR CT value, P<0.001. In conclusion, we developed a novel primate model of E. histolytica intestinal infection and demonstrated that a Gal-lectin-based intranasal synthetic peptide vaccine was highly efficacious in preventing experimental E. histolytica infection and colitis in baboons.

Abstract 2838: Brief exposure to gefitinib/Iressa during premalignant risk window provides lifelong protection from mammary tumor development in MMTV-erbB-2 transgenic mice

Although chemopreventive agents targeting estrogen/estrogen receptor (ER) pathway have been effective for ER+ breast cancer, hormonal resistance associated with increased receptor tyrosine kinase activities, such as erbB-2 and/or EGFR, remains a significant issue in beast cancer prevention. Previous studies demonstrated that administration of gefitinib, an orally active EGFR tyrosine kinase inhibitor, to MMTV-erbB-2 transgenic mice inhibited mammary tumor development in these mice, suggesting that gefitinib is a promising agent for the prevention of ER-negative breast cancer. However, the prevention was achieved by high dose (100 mg/kg) and prolonged drug exposure (from 12 to 50 weeks). The tolerance to high dose/long-term of drug administration for the prevention regimens raised concerns in clinical application. In this study, we tested the efficacy of brief exposure to gefitinib during the high risk window in the prevention of mammary tumor development in the MMTV-erbB-2 transgenic mice and studied the underlying mechanisms. We found that brief exposure of gefitinib to these mice at a dosage of 100 mg/kg/day from 16 to 23 weeks (total 8 wks) resulted in significant chemopreventive effects. In contrast to no tumor-free animals in the control group by 52 weeks, mice in gefitinib treated group remained 65% tumor-free at the same age, which was comparable to the results from a previous report that mice with lifelong gefitinib were 75% tumor-free by 45 weeks. We further demonstrated that delayed tumor development in the treated mice was preceded with decreased mammary epithelial density. Molecular analysis indicated that gefitinib inhibited phosphorylation and expression of EGFR, erbB-3 and endogenous erbB-2 in premalignant mammary tissues. Phosphorylation of Akt1 and Erk1/2 was also significantly downregulated. Importantly, although tumors developed from this model were ER-, mammary tissues in the premalignant stage were ERα+; and gefitinib treatment drastically inhibited the phosphorylation and expression of ERα and the transcription of ER target genes, including EGF, EGFR, ESR1, Bcl-2, cyclin D1 and c-myc. Moreover, BrdU incorporation analysis demonstrates that cell proliferation in the mammary glands in gefitinib treated mice was significantly inhibited. Taken together, these data demonstrate that brief treatment with EGFR/erbB-2 targeting agents at the appropriate risk window may provide lifelong protection from mammary tumors, and inhibition of ER-erbB-2 crosstalk may play a critical role in this long lasting preventive process. Given the concerns associated with high dose/long-term gefitinib treatment, our findings are of great significance in directing clinical application of EGFR/erbB-2 targeting agents as chemopreventive agents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2838. doi:10.1158/1538-7445.AM2011-2838

Effects of leukotriene inhibition on pulmonary morphology in rat pup lungs exposed to hyperoxia

Assisted ventilation is necessary for treating preterm infants with respiratory distress syndrome. Unfortunately, high and prolonged concentrations of oxygen associated with assisted ventilation often lead to pulmonary changes, such as hemorrhage and inflammation. The resulting chronic pulmonary condition is known as bronchopulmonary dysplasia. Pulmonary changes characteristic of this syndrome can be produced in rat pups exposed to high oxygen levels. We exposed 21-d-old rats to room air or continuous 95% oxygen for 7 d and then allocated them into 6 groups to evaluate whether treatment with zileuton and zafirlukast, 2 agents which decrease the effects of leukotrienes, lessened the pulmonary effects of short-term hyperoxia. After 7 d, lung tissue was collected for light and electron microscopy. Pulmonary changes including edema, hemorrhage, alveolar macrophage influx, and Type II pneumocyte proliferation were graded on a numerical scoring system. Compared with controls exposed to hyperoxia [corrected] and saline, rats exposed to hyperoxia and treated with zileuton had significantly reduced levels of alveolar macrophage influx and Type II pneumocyte proliferation, but those exposed to hyperoxia [corrected] and treated with zafirlukast showed no significant reduction in any pulmonary changes. This study helps define pulmonary changes induced secondary to hyperoxia in rat pups and presents new information on the mechanisms of leukotriene inhibition in decreasing the severity of hyperoxic lung injury.

Mimicry and Antibody-Mediated Cell Signaling in Autoimmune Myocarditis

The mechanisms by which autoantibodies against cardiac myosin (CM) may lead to heart dysfunction is unknown. We show that autoantibodies to CM in anti-CM sera and mAbs derived from experimental autoimmune myocarditis targeted the heart cell surface and induced Ab-mediated cAMP-dependent protein kinase A activity. Ab-mediated cell signaling of protein kinase A was blocked by CM, anti-IgG, or by specific inhibitors of the beta-adrenergic receptor (beta-AR) pathway. mAbs confirmed mimicry between CM and the beta-AR. Passive transfer of purified Ab (IgG) from CM-immunized rats resulted in IgG deposition and apoptosis in the heart, leading to a cardiomyopathic heart disease phenotype in recipients. Our novel findings link anti-CM Ab with the beta-AR and subsequent Ab-mediated cell signaling in the heart.

Complex role of hemoglobin and hemoglobin-haptoglobin binding proteins in Haemophilus influenzae virulence in the infant rat model of invasive infection

Haemophilus influenzae requires an exogenous heme source for aerobic growth in vitro. Hemoglobin or hemoglobin-haptoglobin satisfies this requirement. Heme acquisition from hemoglobin-haptoglobin is mediated by proteins encoded by hgp genes. Both Hgps and additional proteins, including those encoded by the hxu operon, provide independent pathways for hemoglobin utilization. Recently we showed that deletion of the set of three hgp genes from a nontypeable strain (86-028NP) of H. influenzae attenuated virulence in the chinchilla otitis media model of noninvasive disease. The present study was undertaken to investigate the role of the hgp genes in virulence of the wild-type serotype b clinical isolate HI689 in the infant rat model of hematogenous meningitis, an established model of invasive disease requiring aerobic growth. Bacteremia of high titer and long duration (>14 days) and histopathologically confirmed meningitis occurred in >95% of infant rats challenged at 5 days of age with strain HI689. While mutations disrupting either the Hgp- or Hxu-mediated pathway of heme acquisition had no effect on virulence in infant rats, an isogenic mutant deficient for both pathways was unable to sustain bacteremia or produce meningitis. In contrast, mutations disrupting either pathway decreased the limited ability of H. influenzae to initiate and sustain bacteremia in weanling rats. Biochemical and growth studies also indicated that infant rat plasma contains multiple heme sources that change with age. Taken together, these data indicate that both the hgp genes and the hxuC gene are virulence determinants in the rat model of human invasive disease.

Jejunal intussusception and small bowel transmural infarction in a baboon (Papio hamadryas anubis)

A 4.3-y-old, colony-bred female baboon (Papio hamadryas anubis) of low social rank and exhibiting no clinically significant signs of illness or distress was found dead at the Oklahoma University Health Sciences Center baboon breeding facility at El Reno, OK. Prior to death she exhibited excessive grooming behavior both toward herself and other baboons. In addition, she was consistently shy, timid, reclusive, and prone to minimal sustained movement (that is, generally lethargic behavior). Animals of low social rank typically exhibit some degree of these behaviors in order to avoid surplus interactions with other animals within their groups, which can lead to conflict and injury. Accordingly, her death was surprising in view of the apparent lack of clinical signs. Necropsy established the cause for death as systemic shock with resultant cardiovascular collapse resulting from a massive jejunal intussusception. This intussusception and resulting entrapment of the jejunal mesenteric vasculature caused total occlusion of the small bowel blood supply, with resulting hemorrhage and ischemic necrosis (small bowel infarction). Jejunal intussusceptions generally are considered to be uncommon and therefore are rarely reported in either the veterinary or human literature. Of special interest was the cause for this intussusception, determined to have been a large hairball located at the most proximal portion of the jejunum. Extending from this hairball and traversing essentially the entire length of the jejunum was a braided strand of hair acting as a string foreign body about which the intussusception formed. In light of our findings we suggest that animals of low social rank exhibiting excessive grooming behavior and lethargy might merit clinical evaluation to rule out possible abdominal disorders.

A naturally occurring fatal case of Herpesvirus papio 2 pneumonia in an infant baboon (Papio hamadryas anubis)

Here we describe the unusual finding of herpesvirus pneumonia in a 7-d-old infant baboon (Papio hamadryas anubis). This animal had been separated from its dam the morning of its birth and was being hand-reared for inclusion in a specific pathogen-free colony. The baboon was presented for anorexia and depression of 2 d duration. Physical examination revealed a slightly decreased body temperature, lethargy, and dyspnea. The baboon was placed on a warm-water blanket and was given amoxicillin-clavulanate orally and fluids subcutaneously. The animal's clinical condition continued to deteriorate despite tube feeding, subcutaneous fluid administration, and antibiotic therapy, and it died 2 d later. Gross necropsy revealed a thin carcass and severe bilateral diffuse pulmonary consolidation. Histopathology of the lung revealed severe diffuse necrotizing pneumonia. Numerous epithelial and endothelial cells contained prominent intranuclear herpetic inclusion bodies. Virus isolated from lung tissue in cell culture was suspected to be Herpesvirus papio 2 (HVP2) in light of the viral cytopathic effect. Real-time polymerase chain reaction (PCR) analysis and DNA sequencing of PCR products both confirmed that the virus was HVP2. This case is interesting because the age at onset suggests perinatal transmission at or immediately after birth, and the disease course suggests inoculation of the virus into the respiratory tract.

Protection against experimental autoimmune myocarditis is mediated by interleukin-10-producing T cells that are controlled by dendritic cells

Experimental autoimmune myocarditis (EAM) can be induced in the Lewis rat by cardiac myosin or its cryptic S2-16 peptide epitope (amino acids 1052 to 1076). To investigate cellular mechanisms and the role of antigen-presenting cells in regulation of myocarditis, we induced protection against EAM in Lewis rats by administration of S2-16 peptide in incomplete Freund's adjuvant (IFA). Protection to EAM was associated with activation of S2-16-reactive splenocytes secreting high levels of interleukin (IL)-10 and reduced levels of interferon-gamma and IL-2. Adoptive transfer of S2-16:IFA-induced splenocytes producing IL-10 suppressed myocarditis induction in syngeneic recipients, suggesting their regulatory cell nature. However, exposure of S2-16:IFA-induced cells to inflammatory cytokine IL-12 converted them to Th1 effectors that transferred EAM. Differentiated function of S2-16-reactive T cells in protected rats resulted from increased IL-10 production by dendritic cells (DCs). Purified DCs from S2-16:IFA-treated rats promoted S2-16-reactive CD4+ T cells to produce increased IL-10 and reduced interferon-gamma. In addition, adoptive transfer of IL-10-producing DCs from S2-16:IFA-treated rats also induced protection to EAM in recipient rats. These studies demonstrated DCs and key cytokines, such as IL-10 and IL-12, regulated the fate of T cells in myocarditis development in the Lewis rat.

Cryptic epitope identified in rat and human cardiac myosin S2 region induces myocarditis in the Lewis rat

Myocarditis is a common cause of dilated cardiomyopathy leading to heart failure. Chronic stages of myocarditis may be initiated by autoimmune responses to exposed cardiac Ags after myocyte damage. Cardiac myosin, a heart autoantigen, induced experimental autoimmune myocarditis (EAM) in susceptible animals. Although cardiac myosin-induced myocarditis has been reported in Lewis rats, the main pathogenic epitope has not been identified. Using overlapping synthetic peptides of the S2 region of human cardiac myosin, we identified an amino acid sequence, S2-16 (residues 1052-1076), that induced severe myocarditis in Lewis rats. The myocarditic epitope was localized to a truncated S2-16 peptide (residues 1052-1073), which contained a sequence identical in human and rat cardiac myosin. The S2-16 peptide was not myocarditic for three other strains of rats, in which the lack of myocarditis was accompanied by the absence of strong S2-16-specific lymphocyte responses in vitro. For Lewis rats, S2-16 was characterized as a cryptic epitope of cardiac myosin because it did not recall lymphocyte and Ab responses after immunization with cardiac myosin. Lymphocytes from S2-16 immunized rats recognized not only S2-16, but also peptides in the S2-28 region. Furthermore, peptide S2-28 was the dominant epitope recognized by T cells from cardiac myosin immunized rats. S2-16 was presented by Lewis rat MHC class II molecules, and myocarditis induction was associated with an up-regulation of inflammatory cytokine production. S2-16-induced EAM provides a defined animal model to investigate mechanisms of EAM and modulation of immune responses to prevent autoimmune myocarditis.

Hormonal and dietary modulation of mammary carcinogenesis in mouse mammary tumor virus-c-erbB-2 transgenic mice

Exogenous and dietary estrogens have been associated with modification of breast cancer risk. Mammary cancer model systems can be used to explore interactions between specific transgenes, and hormonal and dietary factors. Transgenic mice bearing the rat wild-type erbB-2 gene were used to study the effects of short-term hormonal exposure [17beta-estradiol (E2) or tamoxifen] or a soy meal diet on mammary carcinogenesis. In mice fed a casein diet, mammary tumors developed at an earlier age after short-term E2 exposure during the early reproductive period. The median mammary tumor latency was shortest (29 weeks) for the high-dose estrogen as compared with the lowest dose of E2 treated or placebo control mice (33 and 37 weeks, respectively). The timing of short-term E2 exposure was also important, with the most significant changes observed in mice exposed to E2 between 8 and 18 weeks of age. E2 exposure was associated with the subsequent development of more aggressive tumors as determined by histologic grade, multifocal tumor development, stromal invasion, and pulmonary metastasis. In contrast, short-term tamoxifen-exposed mice generally failed to develop mammary tumors by 60 weeks of age. Mice fed a soy meal diet developed mammary tumors at a later age than casein-fed animals treated with E2 or placebo, whereas no differences were observed by diet for the tamoxifen-treated mice. Mammary tumor prevention was >80% in tamoxifen-treated mice on either diet. Novel histologic tumor types were identified, suggesting greater phenotypic diversity than described previously. Benign mammary gland morphogenesis was also significantly altered by short-term hormonal exposure or dietary factors, consistent with the modification of mammary tumor risk in specific treatment groups. Estrogenic modulation of the mammary tumor phenotype in wild-type erbB-2 transgenic mice was observed. Histologic tumor types and clinical aggressivity not reported previously in this transgenic model were noted, suggesting greater biologic heterogeneity than reported previously. In addition, dietary phytoestrogens modified mammary development and tumor latency, suggesting a need for greater stringency in dietary assignment for transgenic mouse models of mammary neoplasia.

Induction of myocarditis and valvulitis in lewis rats by different epitopes of cardiac myosin and its implications in rheumatic carditis

Immune responses against cardiac myosin and group A streptococcal M protein have been implicated in the pathogenesis of rheumatic heart disease. Although cardiac myosin is known to produce myocarditis in susceptible animals, it has never been investigated for its role in production of valvular heart disease, the most serious sequelae of group A streptococcal infection in acute rheumatic fever. In our study, cardiac myosin induced valvulitis in the Lewis rat, and epitopes responsible for production of valvulitis were located in the rod region. Human and rat cardiac myosins induced severe myocarditis in the Lewis rats as expected. A purified S2 fragment (amino acid sequences 842 to 1295) produced the most severe myocarditis as well as valvulitis. Different regions of light meromyosin produced valvulitis (residues 1685 to 1936) or myocarditis (residues 1529 to 1611). Because streptococcal M proteins produced valvular heart disease in Lewis rats and have been linked to anti-cardiac myosin responses, we reacted myosin-sensitized lymphocytes isolated from the hearts of Lewis rats with peptides of streptococcal M5 protein in tritiated thymidine assays. Infiltrating lymphocytes responded most strongly to peptides within the B repeat region of streptococcal M protein. These data show direct evidence that immune responses against cardiac myosin lead to valvular heart disease and the infiltration of the heart by streptococcal M protein reactive T lymphocytes.

Attenuation of cadmium-induced liver injury in senescent male fischer 344 rats: role of metallothionein and glutathione

The influence of aging on the sensitivity of the liver to the acute toxicity of cadmium has not been studied previously in adult rats. In this study hepatotoxicity caused by a single sc injection of CdCl(2) was compared in 5-, 18-, and 28-month-old male Fischer 344 rats. Doses of Cd were adjusted on the basis of the mean lean body mass for each age group of rats, and liver injury was evaluated 24 h after treatment. Cd treatment produced substantial increases in serum alanine aminotransferase (ALT) and sorbitol dehydrogenase (SDH) activities in 5- and 18-month-old rats, whereas no significant increases were observed in 28-month-old rats. Histologic examination of representative livers from each age group confirmed the findings for serum enzyme activity; hepatocellular necrosis was observed only in livers from 5- and 18-month-old rats. The attenuation of Cd hepatotoxicity in senescent rats did not appear to be related to pretreatment levels of metallothionein or glutathione. Likewise, resistance to Cd could not be explained on the basis of metallothionein induction, which decreased as a function of aging. Thus, the mechanisms that account for the postmaturational decline in sensitivity to Cd do not appear to be associated with alterations in levels of the major factors that protect against Cd-induced hepatotoxicity.

Staging of the baboon response to group A streptococci administered intramuscularly: a descriptive study of the clinical symptoms and clinical chemical response patterns

Group A streptococcal infections, ranging from necrotizing fasciitis and myositis to toxic shock syndrome, have increased over the last 10 years. We developed the first primate model of necrotizing fasciitis and myositis. Thirteen baboons were inoculated intramuscularly with group A streptococci (GAS). Eleven animals survived for > or = 11 days before sacrifice, and two animals died within 2 days. The site of inoculation of the survivors exhibited an intense neutrophilic influx (stage I), followed by a lymphoplasmacytic influx (stages II and III). This was accompanied by the appearance of markers of an acute and then a chronic systemic inflammatory response. In contrast, the site of inoculation of the two nonsurvivors exhibited intravascular aggregates of neutrophils at its margin with no influx of neutrophils and with extensive bacterial colonization. We conclude that GAS inoculation induces a local and systemic acute neutrophilia followed by a chronic lymphoplasmacytic response; failure, initially, of neutrophilic influx into the site of inoculation predisposes to systemic GAS sepsis and death; and this three-stage primate model approximates the human disease.

Characterization of the baboon responses to Shiga-like toxin: descriptive study of a new primate model of toxic responses to Stx-1

The baboon response to intravenous infusion of Shiga toxin 1 (Stx-1) varied from acute renal failure, proteinuria, hyperkalemia, and melena with minimal perturbation of host inflammatory and hemostatic systems (high-dose group, 2.0 microg/kg; n = 5) to renal failure with hematuria, proteinuria, thrombocytopenia, schistocytosis, anemia, and melena (low-dose group, 0.05 to 0.2 microg/kg; n = 8). Both groups exhibited renal shutdown and died in 57 hours or less. Both groups produced urine that was positive for tumor necrosis factor and interleukin-6 although neither of these cytokines was detectable (</=5 ng/ml) in the general circulation. Light and electron microscopy showed organelle disintegration and necrosis of the renal proximal tubular epithelium and of the intestinal mucosal epithelium at the tips of the microvilli, both of which were previously shown to bear Gb3 receptors. The renal distal tubular epithelium was spared. The renal proximal tubular epithelial changes were accompanied by swelling of visceral epithelial cells (podocytes) and by swelling and detachment of endothelial cells of the glomerular capillaries. In addition, all of the animals receiving low-dose Stx-1 showed microvascular fibrin deposition and thrombosis in renal glomerular and peritubular capillaries in association with a fall in hematocrit and platelet count and a rise in schistocyte count. The gastrointestinal villous tip lesions were accompanied by varying degrees of mucosal and submucosal congestion, hemorrhage, or necrosis. Electron microscopic images of cerebral cortex and cerebellum showed diffuse unraveling of myelin sheaths with occasional disintegration of neuronal cell bodies. In contrast to the gastrointestinal mucosal and renal proximal tubular epithelium, the Gb3 receptor glycolipid of the renal glomerular and neuronal tissues as determined using toxin overlay thin-layer chromatography plates was below the limit of detection (<13 pM/g wet tissue). We conclude that, depending on the status of the host and amount of toxin infused, Stx-1 can produce a variety of responses ranging from damage to cells carrying the Gb3 receptor (renal proximal tubular epithelial cells and gastrointestinal mucosa) to damage to renal glomerular tissues with microvascular thrombosis as a result of the host's inflammatory response localized to the kidney. We conclude that this thrombotic coagulopathy arises from local changes in the kidney because the appearance of host inflammatory mediators was limited to the urine. This suggests that the initial host response is localized in the kidney, and that the systemic thrombocytopenia, anemia, and schistocytosis may arise secondarily.

Attenuation of tissue thrombosis and hemorrhage by ala-TFPI does not account for its protection against E. coli--a comparative study of treated and untreated non-surviving baboons challenged with LD100 E. coli

This study was designed to determine the effect of a delayed infusion (T+120 min) of alanyl tissue factor pathway inhibitor (ala-TFPI) on the response to LD100 E. coli. We hypothesized that baboons treated with a low dose of TFPI (5 mg/kg) which did not survive would exhibit thrombosis, infarction and hemorrhage of target tissues such as that seen in untreated animals infused with LD100 E. coli. Eight baboons were infused with 5 mg/kg of ala-TFPI over a 10 h period beginning immediately after a 2 h infusion of LD100 E. coli (experimental group). Four baboons were infused with E. coli followed by a 10 h infusion of saline (control group). Of the 12 baboons, the 11 non-survivors (TFPI = 7 out of 8; controls = 4 out of 4) were evaluated for the extent of thrombosis, necrosis, hemorrhage, and congestion of target tissues and for changes in clinical chemical parameters. We expected that failure to protect would correlate with failure to inhibit thrombosis of target tissue (8). Surprisingly ala-TFPI significantly inhibited thrombosis, hemorrhage and necrosis of adrenal and renal tissues and attenuated the rise in creatinine in the 7 treated non-survivors. The lungs of these non-survivors, however, exhibited intra-alveolar fibrin and a mild degree of hemorrhage and edema. We concluded that low doses of ala-TFPI begun as late as T+120 in minutes failed to protect against the lethal effects of LD100 E. coli in spite of completely preventing thrombosis and hemorrhage in target organs, and that thrombosis, infarction and hemorrhage of adrenal and renal tissue are not part of the lethal chain of events in this IV model of E. coli sepsis.

Blood chemistry changes in the rat induced by high doses of nitronyl free radical spin traps

For greatest efficacy, it is desirable to use spin trapping agents in the highest concentrations possible. Fifty-four male Sprague-Dawley rats were used to explore the relative toxicity of four representative nitronyl spin traps at doses chosen on the basis of earlier lethality studies. Most studies were confined to the 3- to 6-h period following drug injection, because the behavioral signs of toxicity are most evident early after injection and because spin trapping studies would typically be performed within this time frame. Doses of spin trap were dissolved in a corn oil/buffer vehicle and injected intraperitoneally (i.p.). Toxic signs were recorded periodically, and at the time of euthanasia or spontaneous death a blood sample was collected by cardiac puncture for clinical chemistry analysis and a necropsy was performed. Both gross pathology and histopathological examination of the major organs were essentially negative in all cases, with no obvious evidence of cellular damage being observed. Neither DMPO (232 mg/100 g b.wt.) nor PBN (100 mg/100 g b.wt.) were lethal in the present study, while both M4PO (20 and 40 mg/ 100 g b.wt.) and PyOBN (100 and 200 mg/100 g b.wt.) were lethal. Abnormal clinical chemistry findings were generally confined to those animals that died spontaneously or were euthanized early for humane reasons. In most cases, death was associated with marked seizure activity and impaired respiration, and deaths occurred within a few min to a few hours. The mechanism of toxicity was unclear due to the lack of histopathological evidence and the wide range of abnormal serum analytes in those rats killed by either M4PO or PyOBN. In conclusion, during the first 6 h after IP administration there is little indication of tissue damage by the nitrone spin traps until the dose is increased to a lethal level, at which point an acute, rapidly occurring, wide-spread disruption of tissue integrity seems to occur.

Evidence of two separate mechanisms for the decrease in aryl sulfotransferase activity in rat liver during early stages of 2-acetylaminofluorene-induced hepatocarcinogenesis

Enzymatic and immunohistochemical experiments were conducted to evaluate the mechanistic basis for the downregulation of the important detoxication/bioactivation enzyme aryl sulfotransferase IV (AST IV) during 2-acetylaminofluorene (2AAF)-induced hepatocarcinogenesis. To distinguish between possible genotoxic and cytotoxic actions of 2AAF, three different dietary protocols were used in these experiments: group 1 received 2AAF for 12 wk, group 2 received 2AAF for 3 or 6 wk and then a control diet lacking xenobiotics for 3 or 6 wk, and group 3 received 2AAF for 3 or 6 wk and then phenobarbital for 3 or 6 wk. When hepatic AST IV activity was assessed, N-hydroxy-2AAF sulfotransferase activity was found to decrease 80-90% in response to 2AAF feeding, but activity recovered to essentially normal levels in the livers of rats subsequently placed on either control diets or diets with phenobarbital, suggesting a reversible cytotoxic mechanism for loss of AST IV activity. However, when liver sections from the rats were evaluated immunohistochemically, two distinct patterns were detected for the downregulation of AST IV activity. In the livers of rats administered only 2AAF (group 1), a general pattern of overall downregulation of AST IV expression was observed throughout the liver and among most but not all newly developed nodules. In tissue sections from rats initially fed 2AAF and then placed on a control diet (group 2) or a diet with phenobarbital (group 3), the nodules continued to show low levels of AST IV expression, while expression in the areas surrounding nodules returned to the normal, high levels. In addition, among those rats fed 2AAF for just 3 wk and then control diet or diet containing phenobarbital for 6 wk, only rats fed phenobarbital developed altered foci that stained weakly for AST IV expression. These results show that there were two kinds of 2AAF-mediated decrease in hepatic AST IV activity: a general overall loss of AST IV expression dependent on administration of 2AAF and reversible upon removal of 2AAF from the diet and a loss of AST IV expression among newly developed liver foci and nodules that persisted in the absence of 2AAF administration and appeared to be a property of 2AAF-induced subpopulations of cells. These patterns may correspond, respectively, to cytotoxic and genotoxic mechanisms of 2AAF action.

Aged mice are resistant to the hepatotoxic effects of endotoxin and galactosamine

The ability of concurrent intraperitoneal injections of endotoxin (0.1 micrograms/kg) and galactosamine (700 mg/kg) to produce liver damage was determined in fasted C57Bl/6 mice of different ages: 2 months (young), 6 months (mature), and 24 months (aged). Liver damage was assessed after 6 hr by measurement of plasma alanine aminotransferase activity (ALAT, mumole/liter/min) and by histological examination for mature and aged mice. Control mice, those treated with saline, galactosamine, endotoxin, or hydrazine alone, had ALAT activities which ranged from 13 to 72 (n = 21). Plasma ALAT activities were increased to hepatotoxic values in some, but not all, mice injected with both endotoxin and galactosamine. For young mice, 7/11 had increased plasma ALAT activities; for mature mice, 5/8 had increased plasma ALAT activities and substantial centrilobular necrosis, whereas for aged mice, 0/7 had increased ALAT activities and none had centrilobular necrosis. Basophilic staining of the cytoplasm was increased by administration of endotoxin and/or galactosamine in both mature and aged mice whether or not necrosis was present. A 5-hr pretreatment with hydrazine sulfate (80 mg/kg) substantially decreased the ALAT release caused by endotoxin and galactosamine in mature mice. Hydrazine pretreatment prevented centrilobular necrosis in mature mice and decreased basophilic cytoplasmic staining in aged mice. The results demonstrate that aged mice are resistant to the hepatotoxic effects of endotoxin and galactosamine which were observed in both young mice and mature mice. Also, hydrazine sulfate pretreatment will protect against the hepatotoxic effects as well as the lethal actions of endotoxin and galactosamine.

Redox cycling and hepatotoxicity of diquat in aging male Fischer 344 rats

The aim of this study was to determine the influence of aging on diquat-induced redox cycling in liver microsomes and diquat hepatotoxicity in rats. Diquat-stimulated production of superoxide anion radical and NADPH-cytochrome c (P-450) reductase activity were measured in liver microsomes prepared from male Fischer 344 rats at ages representing young adulthood (5-6 months), middle age (15-16 months), and old age (24-27 months). Both activities were decreased substantially (40%) in old rats. Diquat-induced liver damage was assessed 6 hr after the administration of diquat (0.1 mmol/kg, ip) on the basis of serum ALT and sorbitol dehydrogenase activities, hepatic microsomal cytochrome P-450 loss, and histological evaluation. The classical manifestations of hepatotoxicity in diquat-treated rats were as severe in old rats as in young-adult ones, despite the age-associated drop in redox cycling capacity. Diquat treatment also resulted in decreased concentrations of hepatic glutathione and ascorbic acid, increased concentrations of hepatic nonheme iron, and decreased liver weights. The changes in glutathione, nonheme iron, and liver weight were more pronounced in livers of middle-aged and old rats than in those of young-adult rats. These age-dependent differences could not be explained on the basis of plasma diquat concentrations, which were similar in the three age groups of rats. The absence of an effect of aging on the hepatotoxic effects of diquat indicates that redox cycling capacity is not limiting for the development of liver damage. Other effects of diquat were influenced by aging, but their relevancy to the hepatotoxicity is uncertain.

Changes in levels of ADP-ribose polymers in rat liver during 2-acetylaminofluorene-induced hepatocarcinogenesis

The exposure of rats to the carcinogen 2-acetylaminofluorene (2-AAF) results in the accumulation of DNA-damaging adducts. The inability of cells to repair such damage adequately is a putative causal event in chemical carcinogenesis. It has been shown that one cellular response to DNA damage that leads to DNA repair is poly(ADP-ribosyl)ation of nuclear proteins. To examine the possible existence of an altered poly(ADP-ribosyl)ation response to 2-AAF-mediated damage of rat liver DNA, tissue ADP-ribose polymer levels were determined during various stages of 2-AAF-mediated carcinogenesis. 2-AAF was administered to rats in a discontinuous feeding regimen comprised of five consecutive cycles, each cycle consisting of 3 weeks on 2-AAF diet followed by 1 week of recovery on a control diet without 2-AAF. During cycle one of 2-AAF administration, rat liver ADP-ribose polymer levels increased 3-fold over that found in livers of rats fed only the control diet. In contrast, when rats were administered the non-genotoxic liver mitogen 4-AAF for one cycle, no significant elevation occurred in ADP-ribose polymer levels. Elevated ADP-ribose polymer production was also observed during cycles two and three of 2-AAF administration. However, during cycles four and five of 2-AAF administration, a period when rats administered 2-AAF acquire a high risk for hepatocarcinogenesis, an altered pattern of ADP-ribose polymer production occurred in rat livers. ADP-ribose polymer levels in these rat livers remained low, similar to levels found in control rat livers, despite the administration of 2-AAF. When the livers from rats fed either one or five cycles of 2-AAF were analyzed for possible decreases in the levels of tissue NAD+, the substrate for poly(ADP-ribose) polymerase, no changes in relative abundance were found. In addition, analysis of poly(ADP-ribose) polymerase activity showed no decrease at five cycles of 2-AAF administration. These results indicated that at late stages of 2-AAF-induced hepatocarcinogenesis, 2-AAF does not induce an expected increase in ADP-ribose polymer levels, and suggested that significant changes in DNA repair may occur at a time just preceding an increased risk for developing liver cancer.

Lethal Staphylococcus aureus-induced shock in primates: prevention of death with anti-TNF antibody

A successful experimental treatment for gram-positive sepsis to our knowledge has not been achieved. The objectives of this study were to develop a nonhuman primate model of lethal gram-positive sepsis employing the micro-organism Staphylococcus aureus and to determine the efficacy of treatment using monoclonal antibody (MAb) to tumor necrosis factor alpha (TNF). The antibody was administered intravenously, 15 mg/kg, 30 minutes after the beginning of a 2-hour infusion of S. aureus, 4 x 10(10) colony forming units/kilogram. The baboons infused with S. aureus demonstrated the release of the cytokines TNF and interleukin-6 (IL-6), but endotoxin was not observed in the plasma at any time. Treatment with antibody to TNF abolished the rise in serum TNF levels and reduced the increased levels of IL-6. Treatment with MAb to TNF prevented multiple organ failure and achieved permanent (> 7 day) survival of all baboons.

Effects of rapid pulsed CO2 laser beam on cortical bone in vivo

Twenty rabbit femurs were used to study the effect of CO2 laser on cortical bone. Sixteen femurs were treated with 20 watts, 3 mm defocused beam, 2 KHZ spike pulse mode CO2 laser for 10 seconds through a circular window in the metaphysis. In four control femurs, the inner cortex was exposed without laser treatment. The animals were killed at 4 and 6 weeks and the specimens studied histologically. All laser-treated specimens showed thermal changes. Three histological zones were observed. A superficial zone of inner cortex close to the beam consisted mainly of carbonization or carbon ash during resorption. An intermediate zone consisted of bone necrosis and healing with associated areas of new bone formation. The deep zone of outer cortex had normal bone with no cellular damage. No such changes were observed in the control specimens. The CO2 laser can be used to generate a controlled zone of tissue ablation, which may make it a potentially useful tool for tumor margin cauterization.

Staphylococcus aureus-induced shock: a pathophysiologic study

The purpose of the present study was to determine the effects of lethal intravenous infusions of Staphylococcus aureus (SA) in adult dogs. Animals were maintained under anesthesia for 6 hr and observed until death following the 1-hr infusions of SA organisms. Findings unique to SA administration compared to those with Escherichia coli were the absence of significant necrosis of the mucosal intestinal glands of the small and large intestines; widespread intravascular colonization of bacteria in lung, heart, kidney and adrenal tissues often associated with neutrophil sequestration, microabscess formation, and necrosis; relative constant blood pressure, fibrinogen, fibrin degradation products (FDP), serum glutamic pyruvic transaminase (SGPT), blood (serum) urea nitrogen (BUN), creatinine, pH, and PO2, all of which remained relatively unchanged for 6 hr. Rapid early increases were observed in temperature, respiration rate, lactate, and hematocrit, while PCO2, platelet and white blood cell concentrations decreased. Results suggest unique qualitative differences in responses to Staphylococcal-induced shock compared to those caused by gram-negative bacteria.

Pneumocystis carinii antigen detection in rat serum and lung lavage

We developed a modified double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) that detected relatively low concentrations of known Pneumocystis carinii antigen added to buffer or rat sera. Artificial immunization-derived polyclonal rabbit anti-P. carinii antibody was used on the solid phase to capture the antigen. Infection-derived (after P. carinii pneumonia) polyclonal rat anti-P. carinii antibody or a mixture of five murine monoclonal antibodies was used as the antigen detector antibody. Rabbit anti-rat immunoglobulin G antibody or goat anti-mouse immunoglobulin G antibody conjugated to alkaline phosphatase was used as the final antibody. After standardization and optimization of the various reactants in this ELISA system, approximately 53 ng of known P. carinii antigen per ml suspended in phosphate-buffered saline-Tween 20 buffer or 210 ng of antigen per ml suspended in normal rat serum diluted 1:4 could be detected. In addition, an indirect ELISA for P. carinii antibody measurement was developed, using as the antigen a soluble supernatant from a sonicated preparation of Percoll-purified whole cysts and trophozoites to coat the solid phase. Limited studies with sera from a small number of caesarian-obtained, barrier-sustained rats from Charles River Breeding Laboratories, Inc., and the National Institutes of Health and sera from normal and heavily infected rats indicated that the caesarian-obtained, barrier-sustained rats had negligible levels of antibody. The normal and heavily infected rats had variable antibody titers. A significantly high level of P. carinii antigenemia was detected in only 2 (11%) of 18 heavily infected rats. Extensive studies of the P. carinii pneumonia rat model with the ELISA did not reveal significant serum P. carinii antigenemia during the acute stage of infection. However, soluble P. carinii antigen was detected by the ELISA and Western blot assays in the supernatant of lavage fluid after centrifugation to sediment intact organisms. As expected, P. carinii antigens were detected by these assays in the lavage pellet recovered after centrifugation. In conclusion, the antigen assay used in this study detected P. carinii antigen in lung lavage but failed to detect P. carinii antigen in rat serum during the acute phase of infection.

Biological evaluation of novel cyclopropyl analogues of stilbene, stilbenediol, and phenanthrene for estrogenic and antiestrogenic activity

The triphenylethylene-type antiestrogens, such as tamoxifen, are known to be useful in the treatment of estrogen-dependent tumors. However, these compounds display mixed estrogen agonist/antagonist activity which may limit their therapeutic effectiveness. This problem of mixed activity led to the synthesis and identification of a cyclopropyl derivative of cis-stilbene which we have named Analog I. This compound (1,1-dichloro-cis-2,3-diphenylcyclopropane) displayed only antiestrogenic activity in the mouse. The present study was designed to evaluate cyclopropyl derivatives of Analog II for estrogenic and antiestrogenic activity in the rat using the standard 3-d uterotropic assay and the uterine cytoplasmic estrogen receptor assay. Five compounds (B-F) which are cyclopropyl derivatives of stilbene, stilbenediol, and phenanthrene were evaluated in this study. Three of the compounds (B-D) displayed neither estrogenic nor antiestrogenic activity in the rat. The relative estrogenic activities of E and F were 11.3 and 1.5%, respectively, of diethylstilbestrol in the uterotropic assay, and 39 and 6.2%, respectively, of estradiol in the estrogen receptor assay. Neither E nor F was found to display antiestrogenic activity in the rat. The results indicate that the relative estrogenic and receptor binding activities of E and F are similar to those previously observed in the mouse, while B-D appear to be inactive in both species.

Long-term intracoronary ethanol administration electrophysiologic and morphologic effects

The long-term intracoronary infusion of ethanol was used to evaluate the potential of ethanol to produce myocardial injury and cardiac rhythm disturbances. In 22 dogs, electrophysiologic testing was performed 48 hr after cessation of alcohol administration. Multiple premature ventricular beats occurred spontaneously in 3 dogs with spontaneous sustained monomorphic ventricular tachycardia observed in 1 dog. Provocative ventricular pacing produced ventricular tachycardia lasting 20 or more beats in 13 animals with sustained tachycardia observed in 3 animals. Provocative ventricular pacing in the presence of lidocaine or epinephrine produced sustained ventricular tachycardia in an additional 4 dogs. The electrophysiologic properties of Purkinje fibers from the zone receiving ethanol were altered when compared to the control zone. The resting membrane potential was decreased (-76 +/- 2 mV vs. -85 +/- mV, p less than 0.001) with a decrease in action potential amplitude (91 +/- 4 vs. 109 +/- 2 mV, p less than 0.001) and phase 0 upstroke (231 +/- 27 vs. 456 +/- 25 V/sec, p less than 0.02). Prolonged refractoriness was observed in the ethanol zone without a prolongation of action potential duration. Intramural lesions observed within the left circumflex distribution varied from focal acute myofibrillar degeneration and necrosis to severe local scarring. The data suggest that intracoronary ethanol administration at human abuse levels of blood alcohol concentrations produces histologic and electrophysiologic injury in the canine heart. The electrophysiologic ch changes provide a substrate sufficient for the induction and maintenance of ventricular arrhythmia.

Effect of aging on liver glutathione levels and hepatocellular injury from carbon tetrachloride, allyl alcohol or galactosamine

Severity of liver damage 24 hr after i.p. administration of carbon tetrachloride (0.2 ml/kg), allyl alcohol (0.036 ml/kg) or galactosamine (400 mg/kg) was evaluated in male rats at 4-5, 14-15 or 24-25 months of age. Allyl alcohol hepatotoxicity, as judged by light microscopy and serum alanine aminotransferase levels, increased markedly as a function of age. In contrast, carbon tetrachloride and galactosamine toxicities were unchanged or slightly diminished in old rats. Hepatic glutathione (GSH) concentrations were unaffected by aging; thus, the age-dependent increase in susceptibility to allyl alcohol toxicity was not a result of diminished GSH availability in old age. Hepatotoxicant-induced changes in GSH were observed in allyl alcohol-treated old rats (20% increase) and in galactosamine-treated young-adult and middle-aged rats (30% decrease).

Influence of dietary fat and indomethacin on the growth of transplantable mammary tumors in rats

Studies were designed to determine if treatment with indomethacin influenced the growth of a transplantable, metastatic, rat mammary tumor. Female, Wistar-Furth inbred rats were fed either a standard chow diet or a semipurified diet containing 2, 5, 10, or 20% stripped corn oil. Indomethacin was given in drinking water, and rats consumed between 2.5 and 3.0 mg indomethacin/kg body weight/day. Feeding of diets and initiation of treatment with indomethacin were started when rats were weaned (21 days old) and continued until they were killed. Approximately 5 X 10(3) mammary tumor cells (DMBA-4) were injected into the fat pad of the sixth mammary gland which is adjacent to the right inguinal lymph node. Each dietary/treatment group consisted of at least 10 rats. Since indomethacin inhibits prostaglandin synthesis, two other groups of non-tumor-bearing rats were used to determine if dietary fat and treatment with indomethacin either influenced prostaglandin E2 production (in vitro) by mononuclear cells from the spleen or altered serum levels of fatty acids. Results indicated that: (a) the rate of tumor growth in untreated rats was significantly greater when the dietary fat content was either 10 or 20% compared to diets containing either 2 or 5% fat; (b) the tumor growth-promoting effects of 10 and 20% fat diets were completely abrogated in rats treated with indomethacin; (c) treatment with indomethacin also inhibited tumor growth in rats fed diets containing either 2 or 5% fat; (d) synthesis of prostaglandin E2 by mononuclear cells from the spleens of untreated rats increased as the dietary fat content increased; (e) in indomethacin-treated rats, prostaglandin E2 synthesis was inhibited in all dietary groups and was not dependent on dietary fat; and (f) in both untreated and indomethacin-treated rats, the serum concentrations of oleic and linoleic acids were influenced to the same extent by dietary fat.

Prevention or amelioration of morphologic lesions in LD100 E coli-shocked baboons with steroid/antibiotic therapy

We have documented the effectiveness of methylprednisolone sodium succinate (MPSS) and gentamicin sulfate (GS) therapy for LD100 E coli-induced shock in the baboon. We sequentially delayed initiation of MPSS infusion from 30 to 120 min and then to 240 min after onset of a 2-h E coli infusion. Treatment resulted in 100%, 85%, and 65% survival respectively. In this study we evaluated tissue taken at autopsy in the three MPSS/GS treatment studies including untreated baboons and those treated with GS only. When animals died (3-49 h) or were sacrificed (7-71 days), tissues were removed, coded, and prepared for histopathologic evaluation by light microscopy. On the basis of morphologic changes animals split into two groups: baboons with little or no tissue alterations (survivors), and those with multiple organ damage (nonsurvivors). Combinations of mild to massive congestion, edema, hemorrhage, fibrin thrombi, increased numbers of polymorphonuclear leukocytes (PMNs), and necrosis of the adrenal glands, liver, kidneys, lungs, and spleen of nonsurvivors were prevented or ameliorated in the MPSS/GS-treated surviving baboons. Data demonstrate the MPSS/GS therapy prevents or reverses the multiple organ damage and increases survival in lethal septic shock.

Comparison of the effect of butylated hydroxytoluene on N-nitrosomethylurea and 7,12-dimethylbenz[a]-anthracene-induced mammary tumors

The antioxidant butylated hydroxytoluene (BHT) when fed at a level of 0.3% in a defined semi-purified diet was found to decrease mammary tumor incidence in female Sprague-Dawley rats induced by 7,12-dimethylbenz[a]-anthracene (DMBA). however, no effect of BHT on tumor incidence was seen in animals consuming the same diet, under identical experimental conditions, but treated with the carcinogen nitrosomethylurea (NMU). Differences in effectiveness of BHT as a tumor inhibitor in the 2 model systems, and thoughts as to a possible mechanism of action with regard to BHT are discussed.

Disseminated staphylococcal infection in a colony of captive ground squirrels (Citellus lateralis)

Purulent cutaneous and visceral lesions were observed in a colony of 68 golden-mantled ground squirrels, Citellus (Spermophilus) lateralis, used in a hibernation study. The squirrels had been purchased from a commercial supplier. Beginning approximately three weeks after their purchase and during the following five weeks, 21 squirrels died. The predominate gross and histologic findings consisted of multifocal suppurative lesions involving the skin, brain and numerous visceral organs. Staphylococcus aureus was consistently found to be associated with the disease.

Fatal Beauveria bassiana infection in a captive American alligator

The entomopathogenic fungus, Beauveria bassiana, was isolated from pulmonary lesions of a dead American alligator (Alligator mississipiensis) at the Oklahoma City Zoo. Colonies of the fungus, which had sporulated in vivo, were found in the thoracic air spaces. Septate, branching hyphae and fungal spores were seen in stained histologic sections of pleura and lung. Dissemination to other viscera had not occurred. This case indicated that B bassiana, a rare vertebrate pathogen, may be a fatal mycotic agent in captive reptiles.

Extracorporeal perfusion without anticoagulation and the response to endotoxin

The results of this study show that an extracorporeal perfusion system without anticoagulation can be established in the dog under certain conditions. The exact mechanisms merit further investigation. It also points to a model to study the effects of endotoxin without heparin interference and as another model for studying the canine blood coagulation system.