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Papers by Mark Dominick

Avian colibacillosis 3 Organism 4 Histology of the avian intestine 10 Intestinal colonization 11 ... more Avian colibacillosis 3 Organism 4 Histology of the avian intestine 10 Intestinal colonization 11 Bursal anatomy 12 Bursal functions 13 Peripheral lymphoid tissue of the intestine 15 COLONIZATION AND PERSISTENCE OF ESCHERICHIA COLI

Toxicol Sci, 2007

The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-a... more The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-activated receptor (PPAR) a/g agonist, was evaluated in a comprehensive nonclinical toxicology program that included single-dose oral toxicity studies in mice, rats, and monkeys; repeat-dose toxicity studies in rats, dogs, and monkeys; a battery of in vitro and in vivo genetic toxicity studies; carcinogenicity studies in mice and rats; reproductive and developmental toxicity studies in rats and rabbits; and studies to investigate species-specific findings. Pharmacologically mediated changes, similar to those observed with other PPARg agonists, were observed following chronic administration and included subcutaneous edema, hematologic/hematopoietic and serum chemistry alterations, and morphologic findings in the heart and adipose tissue in rats and monkeys. In dogs, a species highly sensitive to PPARg agonists, muraglitazar caused pronounced species-specific clinical toxicity and degenerative changes in the brain, spinal cord, and testes at high doses and exposures. Muraglitazar was nongenotoxic in the standard battery of genotoxicity studies. Gallbladder adenomas in male mice and adipocyte neoplasms in male and female rats were seen at suprapharmacologic exposures, whereas urinary bladder tumors occurred in male rats at lower exposures. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Muraglitazar had no effects on reproductive function in male and female rats at high systemic exposures, was not teratogenic in rats or rabbits, and demonstrated no selective developmental toxicity. Overall, there were no nonclinical findings that precluded the safe administration of muraglitazar to humans.

Toxicologic pathology, 1993

PD 132301-2, a novel inhibitor of acyl-CoA:cholesterol acyltransferase, is adrenotoxic to several... more PD 132301-2, a novel inhibitor of acyl-CoA:cholesterol acyltransferase, is adrenotoxic to several laboratory animal species. Morphogenesis of a zona fasciculata-specific cytotoxicity was evaluated in male Hartley guinea pigs administered 100 mg/kg of PD 132301-2 for up to 7 days. Reversibility of adrenal effects was assessed after a 14-day drug withdrawal period (day 21). Serum cortisol concentrations were determined under basal conditions and after administration of adrenocorticotrophic hormone (ACTH) on days 1, 2, 4, 7, and 21. Isolated foci of cortical cell degeneration and necrosis were apparent in outer zona fasciculata by 2 hr and throughout the zona fasciculata at 6 hr. Early degenerative ultrastructural changes included aggregation of smooth endoplasmic reticulum (SER), variable condensation of mitochondrial matrices and swelling of cristae, partitioning of organelles, autophagosome formation, and disruption of lipid globules. Lesions progressed to locally extensive or diffu...

ChemInform, 1997

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Journal of Cardiovascular Pharmacology, 1992

Toxicologic Pathology, 1994

PD 132301-2, an acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor, was administered orally t... more PD 132301-2, an acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor, was administered orally to cynomolgus monkeys for 2 wk at doses of 25, 50, 100, and 200 mg/kg to assess potential subacute toxicity. Sporadic episodes of soft feces and diarrhea increased in incidence from 100 to 200 mg/kg. Histopathologic alterations in adrenocortical cells of treated monkeys consisted of a dose-related decrease in cytoplasmic fine vacuolation and an increase in cytoplasmic eosinophilia most conspicuous in the zona fasciculata and reticularis. At 50, 100, and 200 mg/kg, a narrow discontinuous zone of cytotoxic cortical cell degeneration occurred in the outer zona fasciculata. Decreased fine vacuolation of cortical cells correlated ultrastructurally with reduced size and number of intracellular lipid vacuoles and biochemically with a dose-related decrease in adrenal total cholesterol (from 56 to 13% of control) and cholesteryl ester (from 51 to 3% of control) concentrations. Other ultrastructura...

Journal of the American Association for Laboratory Animal Science : JAALAS, 2009

A novel therapeutic compound was found to induce bladder tumors in male rats. Given the location ... more A novel therapeutic compound was found to induce bladder tumors in male rats. Given the location of the tumors and the increased amounts of calcium- and magnesium-containing solids found in the urine of treated animals, we hypothesized that tumorigenesis was secondary to urine crystal formation rather than a direct effect of the drug on urothelium. To investigate the basis for the response, a method of acidifying rodent urine was needed. This study tested the efficacy of 1% dietary NH(4)Cl in reducing the urinary pH of male mice. After 1 wk, urinary pH (mean +/- SD) at 1 h after light onset was 7.51 +/- 0.32 among controls compared with 6.21 +/- 0.31 for the NH(4)Cl-fed group. After 2 wk of supplementation, urinary pH was 7.78 +/- 0.41 for controls and 6.20 +/- 0.30 for the NH(4)Cl-fed group. To investigate whether the time of collection altered urinary pH, samples also were collected 8 h after the start of the light cycle on the day of the 2-wk collection. Urinary pH was 7.12 +/- 0...

Veterinary Pathology, 1988

Turbinate osteoporosis, induced by intranasal inoculation of purified toxin isolated from serotyp... more Turbinate osteoporosis, induced by intranasal inoculation of purified toxin isolated from serotype D Pasteurella multocida, was investigated in 3- to 5-week-old, caesarean-derived, colostrum-deprived, isolation-reared pigs. Marked bilateral reduction in relative volume of trabecular bone occurred in osseous cores of turbinates of toxin-treated pigs relative to control pigs on post-inoculation day (p.i.d.) 3, 6, 9, 12, and 15. The fractional resorptive surface along turbinate bone was greater in toxin-treated pigs when compared to controls on p.i.d. 3 and 6. A significant decrease in resorptive surface occurred over time in toxin-treated pigs, whereas the fractional resorptive surface was constant over time in control pigs. Osteoclasts in medullary spaces separating bony trabeculae of turbinates were abundant in toxin-treated pigs and scant in controls on p.i.d. 3, 6, and 9. Degeneration and necrosis of bone forming cells, principally osteoblasts, were progressively more extensive wi...

Toxicology and Applied Pharmacology, 1991

111,375-387. ocz,-Globulin (0~~") nephropathy is a male rat-specific condition caused by a divers... more 111,375-387. ocz,-Globulin (0~~") nephropathy is a male rat-specific condition caused by a diverse group of xenobiotics. Features of this nephropathy include hyaline droplet accumulation in proximal tubules, tubular epithelial necrosis and regeneration, exacerbation of spontaneous renal disease, and induction of renal epithelial tumors. Nephrocarcinogenicity of compounds that cause= this nephropathy may be a consequence of increased proximal tubular proliferation resulting from cell injury. These studies document (Y*" nephropathy without primary renal epithelial tumors in male Wistar rats administered 1-(aminomethyl)cyclohexaneacetic acid (gabapentin), a therapeutic agent with antiepileptic/anticonvulsant properties. In a series of preclinical studies gabapentin was administered to rats at the following doses and durations: 50 and 2000 mg/kg for 2 weeks; 250, 1000,2000, and 3000 mg/kg for I3 weeks; 250, 1000, and 2000 mg/kg for 52 and 104 weeks. Renal effects were evaluated by biochemical, immunocytochemical, histopathologic, and ultrastructural techniques. Reversible increases in size and distribution of hyaline droplets within proximal tubular epithelium occurred through I year of treatment at a severity that was dosedependent. In males given 2000 mg/kg, CQ" accumulation, degeneration, and necrosis of the P2 segment and intraluminal cellular casts were seen after 2 days of treatment. In the 2-week study, the size and number of phagolysosomes containing crZU and the renal tissue 01~" increased with increasing dose and time. By Day 7, polymorphic crystalline inclusions were abundant in phagolysosomes of 2000 mg/kg males. In subchronic and chronic studies, spontaneous glomerulonephrosis was exacerbated in males given 2000 mg/kg, and, interestingly, no drug-related effect on renal tumor incidence was observed. To the best of our knowledge, this is the first documentation of the absence of nephrocarcinogenic effect in male rats treated for up to 104 weeks with a compound that causes acute and chronic lesions of DLZ" nephropathy. 0 1991 Academic PESS. IX. A male rat-specific a*,,-globulin (arZU) ne-and outer stripe of the outer medulla (Alden phropathy has been described in toxicity stud-et al., 1984). Male rats chronically exposed to ies with a number of structurally diverse xe-these compounds develop more severe chronic nobiotics (

Toxicology and Applied Pharmacology, 2007

We previously reported prevention of urolithiasis and associated rat urinary bladder tumors by ur... more We previously reported prevention of urolithiasis and associated rat urinary bladder tumors by urine acidification (via diet acidification) in male rats treated with the dual peroxisome proliferator-activated receptor (PPAR)alpha/gamma agonist muraglitazar. Because urine acidification could potentially alter PPAR signaling and/or cellular proliferation in urothelium, we evaluated urothelial cell PPARalpha, PPARdelta, PPARgamma, and epidermal growth factor receptor (EGFR) expression, PPAR signaling, and urothelial cell proliferation in rats fed either a normal or an acidified diet for 5, 18, or 33 days. A subset of rats in the 18-day study also received 63 mg/kg of the PPARgamma agonist pioglitazone daily for the final 3 days to directly assess the effects of diet acidification on responsiveness to PPARgamma agonism. Urothelial cell PPARalpha and gamma expression and signaling were evaluated in the 18- and 33-day studies by immunohistochemical assessment of PPAR protein (33-day study only) and quantitative real-time polymerase chain reaction (qRT-PCR) measurement of PPAR-regulated gene expression. In the 5-day study, EGFR expression and phosphorylation status were evaluated by immunohistochemical staining and egfr and akt2 mRNA levels were assessed by qRT-PCR. Diet acidification did not alter PPARalpha, delta, or gamma mRNA or protein expression, PPARalpha- or gamma-regulated gene expression, total or phosphorylated EGFR protein, egfr or akt2 gene expression, or proliferation in urothelium. Moreover, diet acidification had no effect on pioglitazone-induced changes in urothelial PPARgamma-regulated gene expression. These results support the contention that urine acidification does not prevent PPARgamma agonist-induced bladder tumors by altering PPARalpha, gamma, or EGFR expression or PPAR signaling in rat bladder urothelium.

Toxicological Sciences, 1994

Toxicological Sciences, 2007

The carcinogenic potential of muraglitazar, a dual human peroxisome proliferator-activated recept... more The carcinogenic potential of muraglitazar, a dual human peroxisome proliferator-activated receptor a/g agonist, was evaluated in 2-year studies in mice (1, 5, 20, and 40 mg/kg) and rats (1, 5, 30, and 50 mg/kg). Benign gallbladder adenomas occurred at low incidences in male mice at 20 and 40 mg/kg (area under the curve [AUC] exposures ! 62 times human exposure at 5 mg/day) and were considered drug related due to an increased incidence of gallbladder mucosal hyperplasia at these doses. There was a dose-related increased incidence of transitional cell papilloma and carcinoma of the urinary bladder in male rats at 5, 30, and 50 mg/kg (AUC exposures ! 8 times human exposure at 5 mg/day). At 30 and 50 mg/kg, the urinary bladder tumors were accompanied by evidence of increased urine solids. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Incidences of subcutaneous liposarcoma in male rats and subcutaneous lipoma in female rats were increased at 50 mg/kg (AUC exposures ! 48 times human exposure at 5 mg/day) and attributed, in part, to persistent pharmacologic stimulation of preadipocytes. Toxicologically relevant nonneoplastic changes in target tissues included thinning of cortical bone in mice and hyperplastic and metaplastic adipocyte changes in mice and rats. Considering that muraglitazar is nongenotoxic, the observed tumorigenic effects in mice and rats have no established clinical relevance since they occurred at either clinically nonrelevant exposures (gallbladder and adipose tumors) or by a species-specific mechanism (urinary bladder tumors).

Toxicological Sciences, 2006

Muraglitazar, a PPARa/g dual agonist, was dosed orally to rats once daily for 13 weeks to evaluat... more Muraglitazar, a PPARa/g dual agonist, was dosed orally to rats once daily for 13 weeks to evaluate urinary and urothelial changes of potential relevance to urinary bladder tumorigenesis. Groups of 17 young or aged rats per sex were fed a normal or 1% NH 4 Clsupplemented diet and were dosed with 0, 1, or 50 mg/kg muraglitazar. Lithogenic ions and sediment were profiled from freshly voided urine samples collected 24 h after dosing, and drug exposures were measured. Urinary citrate, oxalate, and epidermal growth factor (EGF) were assayed from 18-h urine collections. Urothelium was assessed by light microscopy, scanning electron microscopy, and BrdU and TUNEL immunohistochemistry. When fed a normal diet, urine pH was higher in males (above 6.5). Urine volume/body weight was greater in females. Urine soluble/total calcium and magnesium and phosphorus/creatinine ratios were lower in male rats fed a normal diet. Urine citrate levels were decreased and oxalate was increased in young male rats treated with 50 mg/kg muraglitazar compared to age/sex/diet-matched controls. No changes in urine sediment were detected 24 h after dosing. In young male rats treated with 50 mg/kg on normal diet, multifocal urothelial necrosis and proliferation were observed, whereas urothelial apoptosis and urine EGF levels were unchanged compared to age/sex/diet-matched controls. Urothelial necrosis and proliferation were not correlated to systemic or urinary drug exposures and were prevented by dietary acidification. These data suggest that muraglitazar-associated changes in urine composition predispose to urothelial cytotoxicity and proliferation in the urinary bladder of young male rats and that urine sediment must be profiled at multiple daily timepoints to fully qualify drug-induced changes in urine composition.

Toxicological Sciences, 1993

CI-986 (5-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1,3,4-thiadiazole-2(3H)- thione-2-hydroxy-... more CI-986 (5-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1,3,4-thiadiazole-2(3H)- thione-2-hydroxy-N,N,N-trimethylethanaminium salt) is a novel anti-inflammatory compound classified as a dual inhibitor of cyclooxygenase and 5-lipoxygenase. Studies were undertaken to characterize the preclinical toxicology of the compound. CI-986 was administered to rats for 2 weeks (0, 50, 250, 750, and 1500 mg/kg) or 13 weeks (0, 20, 250, 500, and 1000 mg/kg), dogs for 2 weeks (0, 50, 150, and 500 mg/kg) or 13 weeks (0, 20, 100, and 200 mg/kg), and to monkeys for 2 weeks (0, 50, 250, and 1000 mg/kg). No drug-related deaths resulted. Mild clinical signs of toxicity were noted in rats given doses of 250 mg/kg and above. Drug-related emesis and diarrhea were absent at the low dose in the dog and monkey but increased in incidence and severity at higher doses. Severe clinical signs in monkeys (emesis and diarrhea) necessitated the lowering of the top dose to 500 mg/kg/day (administered b.i.d.) during the second week of the monkey study. Slight decreases (< 23%) in serum protein and/or albumin were noted in all studies at the higher doses. A dose-related increase in alkaline phosphatase was noted in both dog studies, with no other drug-related effect on clinical pathology parameters. A gastric ulcer occurred in one rat administered 500 mg/kg CI-986 for 13 weeks. Gastrointestinal ulcers were not noted at any other dose in rats or at any dose in dogs or monkeys. A dose-related eosinophilia of glandular stomach submucosa was noted in rats after 2 and 13 weeks of drug administration but not in dogs or monkeys. In the 2-week rat study, mean combined sex plasma drug concentrations monitored 2 hr after dose on Day 14 were 0.59, 1.10, 2.64, and 3.43 micrograms/ml for the 50, 250, 750, and 1,500 mg/kg dose groups, respectively. In the 2-week dog studies, maximum plasma drug concentrations on Day 10 or Day 11 were achieved within 2 hr of dose with mean combined sex Cmax values of 0.73, 2.05, and 2.62 micrograms/ml for the 50, 250, and 750 mg/kg groups, respectively. Hepatic microsomal induction characterized by increased microsomal protein, increased microsomal cytochrome P450 content, and increased p-nitroanisole O-demethylation activity was noted in dogs and monkeys but not rats. CI-986 was well tolerated in rats and dogs at the doses employed and in monkeys at doses up to 500 mg/kg (b.i.d.).(ABSTRACT TRUNCATED AT 250 WORDS)

Toxicological Sciences, 1993

PD 132301-2 is a substituted urea hypolipidemic and antiatherosclerotic agent that is a potent in... more PD 132301-2 is a substituted urea hypolipidemic and antiatherosclerotic agent that is a potent inhibitor of acyl-CoA:cholesterol acyltransferase (ACAT). To determine its subacute toxicity, PD 132301-2 was administered orally to beagle dogs at 0, 6, 12, 25, 50, 200, 400, or 800 mg/kg/day for 2 weeks. Clinico-pathologic evaluations were completed on all dogs. Liver and adrenal total and esterified cholesterol concentrations, adrenocorticotrophic hormone (ACTH) responsiveness, and adrenal ultrastructure were determined at 0, 6, 12, and 25 mg/kg. At 12 mg/kg or greater, salivation, epiphora, conjunctivitis, emesis, anorexia or decreased food consumption, and soft to mucoid feces and/or diarrhea were noted. Suppression of ACTH response occurred by Day 6 at all doses. Adrenocortical degeneration and/or necrosis in zona fasciculata and reticularis was seen at all doses; adrenal free and esterified cholesterol were normal at 6 mg/kg and decreased at 12 and 25 mg/kg. Increases in serum alanine aminotransferase (2- to 15-fold), aspartate aminotransferase (2- to 12-fold), and alkaline phosphatase (2- to 7-fold) were noted at 50 mg/kg or greater. Periportal hepatocellular hypertrophy and hypereosinophilia occurred at 50 mg/kg or greater; hepatic cholesterol values were not significantly affected by treatment. Dose-dependent ultrastructural alterations in adrenocortical cells included decreased numbers of mitochondria and smooth endoplasmic reticulum profiles, qualitative and quantitative changes in lipid globules, and increased numbers of autolysosomes. PD 132301-2 or one of its metabolites has potent adrenocorticolytic properties and limited hepatotoxic properties by mechanism(s) that are likely independent of systemic ACAT inhibition.

Toxicological Sciences, 2007

The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-a... more The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-activated receptor (PPAR) a/g agonist, was evaluated in a comprehensive nonclinical toxicology program that included single-dose oral toxicity studies in mice, rats, and monkeys; repeat-dose toxicity studies in rats, dogs, and monkeys; a battery of in vitro and in vivo genetic toxicity studies; carcinogenicity studies in mice and rats; reproductive and developmental toxicity studies in rats and rabbits; and studies to investigate species-specific findings. Pharmacologically mediated changes, similar to those observed with other PPARg agonists, were observed following chronic administration and included subcutaneous edema, hematologic/hematopoietic and serum chemistry alterations, and morphologic findings in the heart and adipose tissue in rats and monkeys. In dogs, a species highly sensitive to PPARg agonists, muraglitazar caused pronounced species-specific clinical toxicity and degenerative changes in the brain, spinal cord, and testes at high doses and exposures. Muraglitazar was nongenotoxic in the standard battery of genotoxicity studies. Gallbladder adenomas in male mice and adipocyte neoplasms in male and female rats were seen at suprapharmacologic exposures, whereas urinary bladder tumors occurred in male rats at lower exposures. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Muraglitazar had no effects on reproductive function in male and female rats at high systemic exposures, was not teratogenic in rats or rabbits, and demonstrated no selective developmental toxicity. Overall, there were no nonclinical findings that precluded the safe administration of muraglitazar to humans.

Toxicologic Pathology, 2009

In carcinogenicity studies with PPAR gamma and alpha/gamma agonists, urinary bladder tumors have ... more In carcinogenicity studies with PPAR gamma and alpha/gamma agonists, urinary bladder tumors have been reported in Harlan Sprague-Dawley (HSD) and Charles River Sprague-Dawley (SD) but not Wistar (WI) rats, with urolithiasis purported to be the inciting event. In two 3-month studies, the authors investigated strain-related differences in urine composition by sampling urine multiple times daily. Urine pH, electrolytes, creatinine, protein, citrate and oxalate levels, and serum citrate were assessed; urine sediment was analyzed by scanning electron microscopy and energy dispersive x-ray spectroscopy. HSD rats had significantly higher urine calcium than SD or WI rats, primarily as calcium phosphate-containing precipitate. When compared to SD rats, HSD rats had lower urine volume, higher urine protein, and a comparable (week 4) to lower (week 13) burden of MgNH(4)PO(4) aggregates. Relative to WI rats, HSD rats had higher urine protein and magnesium and lower serum and urine citrate. Overall, the susceptibility to urolithiasis in male rats was HSD > SD > WI; this was likely due to strain-related differences in the amount of urine protein (a nidus for crystal formation), lithogenic ions, citrate (an inhibitor of lithogenesis), and/or volume. Strain-related differences in urine composition need to be considered when interpreting the outcome of studies with compounds that alter urine composition.

Avian colibacillosis 3 Organism 4 Histology of the avian intestine 10 Intestinal colonization 11 ... more Avian colibacillosis 3 Organism 4 Histology of the avian intestine 10 Intestinal colonization 11 Bursal anatomy 12 Bursal functions 13 Peripheral lymphoid tissue of the intestine 15 COLONIZATION AND PERSISTENCE OF ESCHERICHIA COLI

Toxicol Sci, 2007

The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-a... more The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-activated receptor (PPAR) a/g agonist, was evaluated in a comprehensive nonclinical toxicology program that included single-dose oral toxicity studies in mice, rats, and monkeys; repeat-dose toxicity studies in rats, dogs, and monkeys; a battery of in vitro and in vivo genetic toxicity studies; carcinogenicity studies in mice and rats; reproductive and developmental toxicity studies in rats and rabbits; and studies to investigate species-specific findings. Pharmacologically mediated changes, similar to those observed with other PPARg agonists, were observed following chronic administration and included subcutaneous edema, hematologic/hematopoietic and serum chemistry alterations, and morphologic findings in the heart and adipose tissue in rats and monkeys. In dogs, a species highly sensitive to PPARg agonists, muraglitazar caused pronounced species-specific clinical toxicity and degenerative changes in the brain, spinal cord, and testes at high doses and exposures. Muraglitazar was nongenotoxic in the standard battery of genotoxicity studies. Gallbladder adenomas in male mice and adipocyte neoplasms in male and female rats were seen at suprapharmacologic exposures, whereas urinary bladder tumors occurred in male rats at lower exposures. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Muraglitazar had no effects on reproductive function in male and female rats at high systemic exposures, was not teratogenic in rats or rabbits, and demonstrated no selective developmental toxicity. Overall, there were no nonclinical findings that precluded the safe administration of muraglitazar to humans.

Toxicologic pathology, 1993

PD 132301-2, a novel inhibitor of acyl-CoA:cholesterol acyltransferase, is adrenotoxic to several... more PD 132301-2, a novel inhibitor of acyl-CoA:cholesterol acyltransferase, is adrenotoxic to several laboratory animal species. Morphogenesis of a zona fasciculata-specific cytotoxicity was evaluated in male Hartley guinea pigs administered 100 mg/kg of PD 132301-2 for up to 7 days. Reversibility of adrenal effects was assessed after a 14-day drug withdrawal period (day 21). Serum cortisol concentrations were determined under basal conditions and after administration of adrenocorticotrophic hormone (ACTH) on days 1, 2, 4, 7, and 21. Isolated foci of cortical cell degeneration and necrosis were apparent in outer zona fasciculata by 2 hr and throughout the zona fasciculata at 6 hr. Early degenerative ultrastructural changes included aggregation of smooth endoplasmic reticulum (SER), variable condensation of mitochondrial matrices and swelling of cristae, partitioning of organelles, autophagosome formation, and disruption of lipid globules. Lesions progressed to locally extensive or diffu...

ChemInform, 1997

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Journal of Cardiovascular Pharmacology, 1992

Toxicologic Pathology, 1994

PD 132301-2, an acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor, was administered orally t... more PD 132301-2, an acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor, was administered orally to cynomolgus monkeys for 2 wk at doses of 25, 50, 100, and 200 mg/kg to assess potential subacute toxicity. Sporadic episodes of soft feces and diarrhea increased in incidence from 100 to 200 mg/kg. Histopathologic alterations in adrenocortical cells of treated monkeys consisted of a dose-related decrease in cytoplasmic fine vacuolation and an increase in cytoplasmic eosinophilia most conspicuous in the zona fasciculata and reticularis. At 50, 100, and 200 mg/kg, a narrow discontinuous zone of cytotoxic cortical cell degeneration occurred in the outer zona fasciculata. Decreased fine vacuolation of cortical cells correlated ultrastructurally with reduced size and number of intracellular lipid vacuoles and biochemically with a dose-related decrease in adrenal total cholesterol (from 56 to 13% of control) and cholesteryl ester (from 51 to 3% of control) concentrations. Other ultrastructura...

Journal of the American Association for Laboratory Animal Science : JAALAS, 2009

A novel therapeutic compound was found to induce bladder tumors in male rats. Given the location ... more A novel therapeutic compound was found to induce bladder tumors in male rats. Given the location of the tumors and the increased amounts of calcium- and magnesium-containing solids found in the urine of treated animals, we hypothesized that tumorigenesis was secondary to urine crystal formation rather than a direct effect of the drug on urothelium. To investigate the basis for the response, a method of acidifying rodent urine was needed. This study tested the efficacy of 1% dietary NH(4)Cl in reducing the urinary pH of male mice. After 1 wk, urinary pH (mean +/- SD) at 1 h after light onset was 7.51 +/- 0.32 among controls compared with 6.21 +/- 0.31 for the NH(4)Cl-fed group. After 2 wk of supplementation, urinary pH was 7.78 +/- 0.41 for controls and 6.20 +/- 0.30 for the NH(4)Cl-fed group. To investigate whether the time of collection altered urinary pH, samples also were collected 8 h after the start of the light cycle on the day of the 2-wk collection. Urinary pH was 7.12 +/- 0...

Veterinary Pathology, 1988

Turbinate osteoporosis, induced by intranasal inoculation of purified toxin isolated from serotyp... more Turbinate osteoporosis, induced by intranasal inoculation of purified toxin isolated from serotype D Pasteurella multocida, was investigated in 3- to 5-week-old, caesarean-derived, colostrum-deprived, isolation-reared pigs. Marked bilateral reduction in relative volume of trabecular bone occurred in osseous cores of turbinates of toxin-treated pigs relative to control pigs on post-inoculation day (p.i.d.) 3, 6, 9, 12, and 15. The fractional resorptive surface along turbinate bone was greater in toxin-treated pigs when compared to controls on p.i.d. 3 and 6. A significant decrease in resorptive surface occurred over time in toxin-treated pigs, whereas the fractional resorptive surface was constant over time in control pigs. Osteoclasts in medullary spaces separating bony trabeculae of turbinates were abundant in toxin-treated pigs and scant in controls on p.i.d. 3, 6, and 9. Degeneration and necrosis of bone forming cells, principally osteoblasts, were progressively more extensive wi...

Toxicology and Applied Pharmacology, 1991

111,375-387. ocz,-Globulin (0~~") nephropathy is a male rat-specific condition caused by a divers... more 111,375-387. ocz,-Globulin (0~~") nephropathy is a male rat-specific condition caused by a diverse group of xenobiotics. Features of this nephropathy include hyaline droplet accumulation in proximal tubules, tubular epithelial necrosis and regeneration, exacerbation of spontaneous renal disease, and induction of renal epithelial tumors. Nephrocarcinogenicity of compounds that cause= this nephropathy may be a consequence of increased proximal tubular proliferation resulting from cell injury. These studies document (Y*" nephropathy without primary renal epithelial tumors in male Wistar rats administered 1-(aminomethyl)cyclohexaneacetic acid (gabapentin), a therapeutic agent with antiepileptic/anticonvulsant properties. In a series of preclinical studies gabapentin was administered to rats at the following doses and durations: 50 and 2000 mg/kg for 2 weeks; 250, 1000,2000, and 3000 mg/kg for I3 weeks; 250, 1000, and 2000 mg/kg for 52 and 104 weeks. Renal effects were evaluated by biochemical, immunocytochemical, histopathologic, and ultrastructural techniques. Reversible increases in size and distribution of hyaline droplets within proximal tubular epithelium occurred through I year of treatment at a severity that was dosedependent. In males given 2000 mg/kg, CQ" accumulation, degeneration, and necrosis of the P2 segment and intraluminal cellular casts were seen after 2 days of treatment. In the 2-week study, the size and number of phagolysosomes containing crZU and the renal tissue 01~" increased with increasing dose and time. By Day 7, polymorphic crystalline inclusions were abundant in phagolysosomes of 2000 mg/kg males. In subchronic and chronic studies, spontaneous glomerulonephrosis was exacerbated in males given 2000 mg/kg, and, interestingly, no drug-related effect on renal tumor incidence was observed. To the best of our knowledge, this is the first documentation of the absence of nephrocarcinogenic effect in male rats treated for up to 104 weeks with a compound that causes acute and chronic lesions of DLZ" nephropathy. 0 1991 Academic PESS. IX. A male rat-specific a*,,-globulin (arZU) ne-and outer stripe of the outer medulla (Alden phropathy has been described in toxicity stud-et al., 1984). Male rats chronically exposed to ies with a number of structurally diverse xe-these compounds develop more severe chronic nobiotics (

Toxicology and Applied Pharmacology, 2007

We previously reported prevention of urolithiasis and associated rat urinary bladder tumors by ur... more We previously reported prevention of urolithiasis and associated rat urinary bladder tumors by urine acidification (via diet acidification) in male rats treated with the dual peroxisome proliferator-activated receptor (PPAR)alpha/gamma agonist muraglitazar. Because urine acidification could potentially alter PPAR signaling and/or cellular proliferation in urothelium, we evaluated urothelial cell PPARalpha, PPARdelta, PPARgamma, and epidermal growth factor receptor (EGFR) expression, PPAR signaling, and urothelial cell proliferation in rats fed either a normal or an acidified diet for 5, 18, or 33 days. A subset of rats in the 18-day study also received 63 mg/kg of the PPARgamma agonist pioglitazone daily for the final 3 days to directly assess the effects of diet acidification on responsiveness to PPARgamma agonism. Urothelial cell PPARalpha and gamma expression and signaling were evaluated in the 18- and 33-day studies by immunohistochemical assessment of PPAR protein (33-day study only) and quantitative real-time polymerase chain reaction (qRT-PCR) measurement of PPAR-regulated gene expression. In the 5-day study, EGFR expression and phosphorylation status were evaluated by immunohistochemical staining and egfr and akt2 mRNA levels were assessed by qRT-PCR. Diet acidification did not alter PPARalpha, delta, or gamma mRNA or protein expression, PPARalpha- or gamma-regulated gene expression, total or phosphorylated EGFR protein, egfr or akt2 gene expression, or proliferation in urothelium. Moreover, diet acidification had no effect on pioglitazone-induced changes in urothelial PPARgamma-regulated gene expression. These results support the contention that urine acidification does not prevent PPARgamma agonist-induced bladder tumors by altering PPARalpha, gamma, or EGFR expression or PPAR signaling in rat bladder urothelium.

Toxicological Sciences, 1994

Toxicological Sciences, 2007

The carcinogenic potential of muraglitazar, a dual human peroxisome proliferator-activated recept... more The carcinogenic potential of muraglitazar, a dual human peroxisome proliferator-activated receptor a/g agonist, was evaluated in 2-year studies in mice (1, 5, 20, and 40 mg/kg) and rats (1, 5, 30, and 50 mg/kg). Benign gallbladder adenomas occurred at low incidences in male mice at 20 and 40 mg/kg (area under the curve [AUC] exposures ! 62 times human exposure at 5 mg/day) and were considered drug related due to an increased incidence of gallbladder mucosal hyperplasia at these doses. There was a dose-related increased incidence of transitional cell papilloma and carcinoma of the urinary bladder in male rats at 5, 30, and 50 mg/kg (AUC exposures ! 8 times human exposure at 5 mg/day). At 30 and 50 mg/kg, the urinary bladder tumors were accompanied by evidence of increased urine solids. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Incidences of subcutaneous liposarcoma in male rats and subcutaneous lipoma in female rats were increased at 50 mg/kg (AUC exposures ! 48 times human exposure at 5 mg/day) and attributed, in part, to persistent pharmacologic stimulation of preadipocytes. Toxicologically relevant nonneoplastic changes in target tissues included thinning of cortical bone in mice and hyperplastic and metaplastic adipocyte changes in mice and rats. Considering that muraglitazar is nongenotoxic, the observed tumorigenic effects in mice and rats have no established clinical relevance since they occurred at either clinically nonrelevant exposures (gallbladder and adipose tumors) or by a species-specific mechanism (urinary bladder tumors).

Toxicological Sciences, 2006

Muraglitazar, a PPARa/g dual agonist, was dosed orally to rats once daily for 13 weeks to evaluat... more Muraglitazar, a PPARa/g dual agonist, was dosed orally to rats once daily for 13 weeks to evaluate urinary and urothelial changes of potential relevance to urinary bladder tumorigenesis. Groups of 17 young or aged rats per sex were fed a normal or 1% NH 4 Clsupplemented diet and were dosed with 0, 1, or 50 mg/kg muraglitazar. Lithogenic ions and sediment were profiled from freshly voided urine samples collected 24 h after dosing, and drug exposures were measured. Urinary citrate, oxalate, and epidermal growth factor (EGF) were assayed from 18-h urine collections. Urothelium was assessed by light microscopy, scanning electron microscopy, and BrdU and TUNEL immunohistochemistry. When fed a normal diet, urine pH was higher in males (above 6.5). Urine volume/body weight was greater in females. Urine soluble/total calcium and magnesium and phosphorus/creatinine ratios were lower in male rats fed a normal diet. Urine citrate levels were decreased and oxalate was increased in young male rats treated with 50 mg/kg muraglitazar compared to age/sex/diet-matched controls. No changes in urine sediment were detected 24 h after dosing. In young male rats treated with 50 mg/kg on normal diet, multifocal urothelial necrosis and proliferation were observed, whereas urothelial apoptosis and urine EGF levels were unchanged compared to age/sex/diet-matched controls. Urothelial necrosis and proliferation were not correlated to systemic or urinary drug exposures and were prevented by dietary acidification. These data suggest that muraglitazar-associated changes in urine composition predispose to urothelial cytotoxicity and proliferation in the urinary bladder of young male rats and that urine sediment must be profiled at multiple daily timepoints to fully qualify drug-induced changes in urine composition.

Toxicological Sciences, 1993

CI-986 (5-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1,3,4-thiadiazole-2(3H)- thione-2-hydroxy-... more CI-986 (5-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1,3,4-thiadiazole-2(3H)- thione-2-hydroxy-N,N,N-trimethylethanaminium salt) is a novel anti-inflammatory compound classified as a dual inhibitor of cyclooxygenase and 5-lipoxygenase. Studies were undertaken to characterize the preclinical toxicology of the compound. CI-986 was administered to rats for 2 weeks (0, 50, 250, 750, and 1500 mg/kg) or 13 weeks (0, 20, 250, 500, and 1000 mg/kg), dogs for 2 weeks (0, 50, 150, and 500 mg/kg) or 13 weeks (0, 20, 100, and 200 mg/kg), and to monkeys for 2 weeks (0, 50, 250, and 1000 mg/kg). No drug-related deaths resulted. Mild clinical signs of toxicity were noted in rats given doses of 250 mg/kg and above. Drug-related emesis and diarrhea were absent at the low dose in the dog and monkey but increased in incidence and severity at higher doses. Severe clinical signs in monkeys (emesis and diarrhea) necessitated the lowering of the top dose to 500 mg/kg/day (administered b.i.d.) during the second week of the monkey study. Slight decreases (< 23%) in serum protein and/or albumin were noted in all studies at the higher doses. A dose-related increase in alkaline phosphatase was noted in both dog studies, with no other drug-related effect on clinical pathology parameters. A gastric ulcer occurred in one rat administered 500 mg/kg CI-986 for 13 weeks. Gastrointestinal ulcers were not noted at any other dose in rats or at any dose in dogs or monkeys. A dose-related eosinophilia of glandular stomach submucosa was noted in rats after 2 and 13 weeks of drug administration but not in dogs or monkeys. In the 2-week rat study, mean combined sex plasma drug concentrations monitored 2 hr after dose on Day 14 were 0.59, 1.10, 2.64, and 3.43 micrograms/ml for the 50, 250, 750, and 1,500 mg/kg dose groups, respectively. In the 2-week dog studies, maximum plasma drug concentrations on Day 10 or Day 11 were achieved within 2 hr of dose with mean combined sex Cmax values of 0.73, 2.05, and 2.62 micrograms/ml for the 50, 250, and 750 mg/kg groups, respectively. Hepatic microsomal induction characterized by increased microsomal protein, increased microsomal cytochrome P450 content, and increased p-nitroanisole O-demethylation activity was noted in dogs and monkeys but not rats. CI-986 was well tolerated in rats and dogs at the doses employed and in monkeys at doses up to 500 mg/kg (b.i.d.).(ABSTRACT TRUNCATED AT 250 WORDS)

Toxicological Sciences, 1993

PD 132301-2 is a substituted urea hypolipidemic and antiatherosclerotic agent that is a potent in... more PD 132301-2 is a substituted urea hypolipidemic and antiatherosclerotic agent that is a potent inhibitor of acyl-CoA:cholesterol acyltransferase (ACAT). To determine its subacute toxicity, PD 132301-2 was administered orally to beagle dogs at 0, 6, 12, 25, 50, 200, 400, or 800 mg/kg/day for 2 weeks. Clinico-pathologic evaluations were completed on all dogs. Liver and adrenal total and esterified cholesterol concentrations, adrenocorticotrophic hormone (ACTH) responsiveness, and adrenal ultrastructure were determined at 0, 6, 12, and 25 mg/kg. At 12 mg/kg or greater, salivation, epiphora, conjunctivitis, emesis, anorexia or decreased food consumption, and soft to mucoid feces and/or diarrhea were noted. Suppression of ACTH response occurred by Day 6 at all doses. Adrenocortical degeneration and/or necrosis in zona fasciculata and reticularis was seen at all doses; adrenal free and esterified cholesterol were normal at 6 mg/kg and decreased at 12 and 25 mg/kg. Increases in serum alanine aminotransferase (2- to 15-fold), aspartate aminotransferase (2- to 12-fold), and alkaline phosphatase (2- to 7-fold) were noted at 50 mg/kg or greater. Periportal hepatocellular hypertrophy and hypereosinophilia occurred at 50 mg/kg or greater; hepatic cholesterol values were not significantly affected by treatment. Dose-dependent ultrastructural alterations in adrenocortical cells included decreased numbers of mitochondria and smooth endoplasmic reticulum profiles, qualitative and quantitative changes in lipid globules, and increased numbers of autolysosomes. PD 132301-2 or one of its metabolites has potent adrenocorticolytic properties and limited hepatotoxic properties by mechanism(s) that are likely independent of systemic ACAT inhibition.

Toxicological Sciences, 2007

The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-a... more The toxicity of muraglitazar, an oxybenzylglycine, nonthiazolidinedione peroxisome proliferator-activated receptor (PPAR) a/g agonist, was evaluated in a comprehensive nonclinical toxicology program that included single-dose oral toxicity studies in mice, rats, and monkeys; repeat-dose toxicity studies in rats, dogs, and monkeys; a battery of in vitro and in vivo genetic toxicity studies; carcinogenicity studies in mice and rats; reproductive and developmental toxicity studies in rats and rabbits; and studies to investigate species-specific findings. Pharmacologically mediated changes, similar to those observed with other PPARg agonists, were observed following chronic administration and included subcutaneous edema, hematologic/hematopoietic and serum chemistry alterations, and morphologic findings in the heart and adipose tissue in rats and monkeys. In dogs, a species highly sensitive to PPARg agonists, muraglitazar caused pronounced species-specific clinical toxicity and degenerative changes in the brain, spinal cord, and testes at high doses and exposures. Muraglitazar was nongenotoxic in the standard battery of genotoxicity studies. Gallbladder adenomas in male mice and adipocyte neoplasms in male and female rats were seen at suprapharmacologic exposures, whereas urinary bladder tumors occurred in male rats at lower exposures. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Muraglitazar had no effects on reproductive function in male and female rats at high systemic exposures, was not teratogenic in rats or rabbits, and demonstrated no selective developmental toxicity. Overall, there were no nonclinical findings that precluded the safe administration of muraglitazar to humans.

Toxicologic Pathology, 2009

In carcinogenicity studies with PPAR gamma and alpha/gamma agonists, urinary bladder tumors have ... more In carcinogenicity studies with PPAR gamma and alpha/gamma agonists, urinary bladder tumors have been reported in Harlan Sprague-Dawley (HSD) and Charles River Sprague-Dawley (SD) but not Wistar (WI) rats, with urolithiasis purported to be the inciting event. In two 3-month studies, the authors investigated strain-related differences in urine composition by sampling urine multiple times daily. Urine pH, electrolytes, creatinine, protein, citrate and oxalate levels, and serum citrate were assessed; urine sediment was analyzed by scanning electron microscopy and energy dispersive x-ray spectroscopy. HSD rats had significantly higher urine calcium than SD or WI rats, primarily as calcium phosphate-containing precipitate. When compared to SD rats, HSD rats had lower urine volume, higher urine protein, and a comparable (week 4) to lower (week 13) burden of MgNH(4)PO(4) aggregates. Relative to WI rats, HSD rats had higher urine protein and magnesium and lower serum and urine citrate. Overall, the susceptibility to urolithiasis in male rats was HSD > SD > WI; this was likely due to strain-related differences in the amount of urine protein (a nidus for crystal formation), lithogenic ions, citrate (an inhibitor of lithogenesis), and/or volume. Strain-related differences in urine composition need to be considered when interpreting the outcome of studies with compounds that alter urine composition.