Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gallium arsenide is used primarily to make light- emitting diodes, lasers, laser windows, and photodetectors and in the photoelectronic transmission of data through optical fibers. Gallium arsenide was nominated for study because of its widespread use in the microelectronics industry, the potential for worker exposure, and the absence of chronic toxicity data. Male and female F344/N rats and B6C3F1 mice were exposed to gallium arsenide particles (greater than 98% pure; mass median aerodynamic diameter = 0.8 to 1.0 &mgr;m) by inhalation for 16 days, 14 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, and the frequency of micronuclei was determined in the peripheral blood of mice exposed to gallium arsenide for 14 weeks. 16-DAY STUDY IN RATS: Groups of five male and five female rats were exposed to particulate aerosols of gallium arsenide with a mass median aerodynamic diameter of approximately 1 &mgr;m at concentrations of 0, 1, 10, 37, 75, or 150 mg/m(3) by inhalation, 6 hours per day, 5 days per week, for 16 days. All rats survived to the end of the study. The final mean body weights of all exposed groups of males and females were similar to those of the chamber controls. Compared to chamber controls, the liver and lung weights of males exposed to 1 mg/m(3) or greater and females exposed to 10 mg/m(3) or greater were increased; the thymus weights of all exposed groups of males were decreased. Gallium arsenide particles were visible in the alveolar spaces and, to a lesser extent, within alveolar macrophages of exposed rats. Moderate proteinosis (surfactant mixed with small amounts of fibrin) and minimal histiocytic cellular infiltrate were observed in the alveoli of exposed males and females. Epithelial hyperplasia and squamous metaplasia of the larynx were observed primarily in males exposed to 150 mg/m(3). 16-DAY STUDY IN MICE: Groups of five male and four or five female mice were exposed to particulate aerosols of gallium arsenide with a mass median aerodynamic diameter of approximately 1 &mgr;m at concentrations of 0, 1, 10, 37, 75, or 150 mg/m(3) by inhalation, 6 hours per day, 5 days per week, for 16 days. The final mean body weights were similar among exposed and chamber control groups. Compared to chamber controls, the lung weights of males and females exposed to 10 mg/m(3) or greater were increased. Gallium ar senide particles were visible in alveolar spaces and macrophages in some mice exposed to 150 mg/m(3). Moderate proteinosis, mild epithelial hyperplasia, and histiocytic infiltration of the lung were observed in males and females exposed to 10 mg/m(3) or greater. In the larynx, mild squamous metaplasia was seen in mice exposed to 10 mg/m(3) or greater, and mild chronic inflammation occurred in mice exposed to 75 or 150 mg/m(3). 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed by inhalation to gallium arsenide particulate at concentrations of 0, 0.1, 1, 10, 37, or 75 mg/m(3), 6 hours per day, 5 days per week, for 14 weeks. All rats survived until the end of the study. The final mean body weight and body weight gain of males exposed to 75 mg/m(3) were significantly less than those of the chamber controls. Hematology and clinical chemistry results indicated that exposure to gallium arsenide induced a microcytic responsive anemia with an erythrocytosis and increased zinc protoporphyrin/heme ratios in exposed groups of rats. There were also increases in platelet and neutrophil counts, a transient decrease in leukocyte counts, and increases in the serum activities of alanine aminotransferase and sorbitol dehydrogenase. These changes were of greater magnitude in male rats. The lung weights of all exposed groups of rats were increased, while testis, cauda epididymis, and epididymis weights of males exposed to 37 or 75 mg/m(3) were generally less than those of chamber controls. Total spermatid heads and spermatid counts were significantly decreased in males exposed to 75 mg/m(3), while epididymal spermatozoa motility was significantly reduced in males ees exposed to 10 mg/m(3) or greater. Gallium arsenide particles were visible in alveolar spaces and macrophages in the lungs of exposed rats. Minimal to marked proteinosis and minimal histiocytic cellular infiltration of the alveoli were observed in all exposed groups; minimal squamous metaplasia in the larynx and lymphoid cell hyperplasia of the mediastinal lymph node were observed in some males and females exposed to 37 or 75 mg/m(3). Exposure-related increases in the incidences of plasma cell hyperplasia of the mandibular lymph node, testicular atrophy, epididymal hypospermia, bone marrow hyperplasia (males), and hemosiderosis in the liver were observed in the 37 and 75 mg/m(3) groups. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were exposed by inhalation to gallium arsenide particulate at concentrations of 0, 0.1, 1, 10, 37, or 75 mg/m(3), 6 hours per day, 5 days per week, for 14 weeks. One female mouse exposed to 75 mg/m(3) died before the end of the study. Final mean body weights and body weight gains of males in the 75 mg/m(3) group were signifi cantly less than the chamber controls. Hematology and clinical chemistry results indicated that exposure to gallium arsenide affected the circulating erythroid mass and induced a microcytic responsive anemia with an erythrocytosis and increased zinc protoporphyrin/heme ratios in male and female mice. There were also increases in platelet and neutrophil counts. Compared to the chamber controls, the lung weights of males exposed to 1 mg/m(3) or greater and females exposed to 10 mg/m(3) or greater were increased. Testis, cauda epididymis, and epididymis weights, total spermatid heads, spermatid counts, and concentration and motility of epididymal spermatozoa were generally decreased. Gallium arsenide particles were visible in alveolar spaces and macrophages in the lungs of mice exposed to 1 mg/m(3) or greater. Mild to marked proteinosis, histiocytic infiltration, and epithelial hyperplasia were observed in the alveoli of males and females exposed to 1 mg/m(3) or greater. Minimal to mild suppurative inflammation and granuloma in the lung and squamous metaplasia in the larynx were present in males and females exposed to 10 mg/m(3) or greater. Min imal hyperplasia was observed in the tracheobronchial lymph node of males exposed to 10 mg/m(3) or greater and females exposed to 37 or 75 mg/m(3). Exposure- related increases in the incidences of testicular atrophy, epididymal hypospermia, hematopoietic cell proliferation of the spleen, and hemosiderosis of the liver and spleen were observed in groups of male and female mice exposed to 10 mg/m(3) or greater. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed by inhalation to gallium arsenide particulate at concentrations of 0, 0.01, 0.1, or 1.0 mg/m(3), 6 hours per day, 5 days per week, for 105 weeks. Survival and Body Weights: Survival of exposed male and female rats was similar to the chamber controls. Mean body weights of males exposed to 1.0 mg/m(3) were generally less than those of the chamber controls throughout the study; females exposed to 1.0 mg/m(3) had slightly lower mean body weights during the second year. Pathology Findings: Compared to the chamber controls, the incidences of alveolar/bronchiolar neoplasms were significantly increased in females exposed to 1.0 mg/m(3) and exceeded the historical control ranges. Exposure-related nonneoplastic lesions in the lungs of male and female rats included atypical hyperplasia, alveolar epithelial hyperplasia, chronic active inflammation, proteinosis, and alveolar epithelial metaplasia. In the larynx of males exposed to 1.0 mg/m(3), the incidences of hyperplasia, chronic active inflammation, squamous metaplasia, and hyperplasia of the epiglottis were significantly increased. The incidences of benign pheochromocytoma of the adrenal medulla occurred with a positive trend in female rats, and the incidence was significantly increased in the 1.0 mg/m(3) group and exceeded the historical control range. The incidence of mononuclear cell leukemia was significantly increased in females exposed to 1.0 mg/m(3) and exceeded the historical control range. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed by inhalation to gallium arsenide particulate at concentrations of 0, 0.1, 0.5, or 1.0 mg/m(3), 6 hours per day, 5 days per week, for 105 (males) or 106 (females) weeks. Survival and Body Weights: Survival of male and female mice was similar to the chamber controls. Mean body weights of exposed groups of males were similar to those of the chamber controls throughout the study; mean body weights of exposed groups of females were greater than those of the chamber controls from week 13 until the end of the study. Pathology Findings: Exposure-related nonneoplastic lesions in the lung of all groups of exposed mice included suppurative focal inflammation, chronic focal inflammation, histiocyte cellular infiltration, alveolar epithelial hyperplasia, and proteinosis. Increased incidences of minimal lymphoid hyperplasia of the tracheobronchial lymph node occurred in mice exposed to 1.0 mg/m(3) and in 0.5 mg/m(3)mg/m(3) males. GENETIC TOXICOLOGY: Gallium arsenide was not mutagenic in several strains of Salmonella typhimurium, with or without S9 metabolic activation enzymes, and no increase in the frequency of micronucleated erythrocytes was observed in peripheral blood of male or female mice exposed to gallium arsenide by inhalation for 14 weeks. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of gallium arsenide in male F344/N rats exposed to 0.01, 0.1, or 1.0 mg/m(3). There was clear evidence of carcinogenic activity in female F344/N rats based on increased incidences of benign and malignant neoplasms in the lung. Increased incidences of benign neoplasms of the adrenal medulla and increased incidences of mononuclear cell leukemia were also considered to be exposure related. There was no evidence of carcinogenic activity in male or female B6C3F1 mice exposed to 0.1, 0.5, or 1.0 mg/m(3). Exposure to gallium arsenide caused a spectrum of nonneoplastic lesions in the lung of rats and mice, the larynx of male rats and hyperplasia of the tracheobronchial lymph node in mice. Synonym: Gallium monoarsenide.
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PMID:NTP Toxicology and Carcinogenesis Studies of Gallium Arsenide (CAS No. 1303-00-0) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). 1256 48

1-Chloro-2-propanol and its positional isomer, 2-chloro-1-propanol, are used as chemical intermediates for the manufacture of propylene oxide, a starting material for production of polyurethane polyols and propylene glycol. The National Cancer Institute nominated 1-chloro-2-propanol for study because of potential for human exposure due to its residues in various foods that are fumigated with ethylene oxide or propylene oxide. Male and female F344/N rats and B6C3F1 mice were exposed to technical grade 1-chloro-2-propanol (75% to 76%% 1-chloro-2-propanol; 24% to 25%% 2-chloro-1-propanol) in drinking water for 14 days, 14 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, Drosophila melanogaster, and mouse peripheral blood erythrocytes. Continuous breeding studies were conducted in Sprague-Dawley rats. 14-DAY STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were administered 1-chloro-2-propanol in drinking water at concentrations of 0, 100, 330, 1,000, 3,300, or 10,000 ppm for 14 days. Two 10,000 ppm females died before the end of the study. The final mean body weights and body weight gains of 3,300 and 10,000 ppm rats were significantly less than those of the controls; rats in the 10,000 ppm groups lost weight. Water consumption by the 3,300 and 10,000 ppm groups was significantly less than that by the controls throughout the study. The thymus weights of 10,000 ppm rats were significantly less than those of the controls. Exposure to 1-chloro-2-propanol caused cytoplasmic alteration and degeneration of the acinar cells and fatty change in the pancreas, atrophy of the bone marrow, and atrophy and hematopoiesis of the spleen in males and females. 14-DAY STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were administered 1-chloro-2-propanol in drinking water at concentrations of 0, 100, 330, 1,000, 3,300, or 10,000 ppm for 14 days. One male mouse in the 10,000 ppm group died before the end of the study. Mean body weight gains of 10,000 ppm mice were significantly less than those of the controls. Water consumption by 3,300 and 10,000 ppm males and females was significantly less than that by the controls throughout the study. Liver weights of 1,000, 3,300, or 10,000 ppm males and females were significantly greater and thymus weights of 10,000 ppm mice were significantly less than those of the controls. Exposure to 1-chloro-2-propanol caused hepatocellular vacuolization, cytoplasmic alteration and degeneration of the pancreas acinar cells, and atrophy of the spleen in males and females. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were administered 1-chloro-2-propanol at concentrations of 0, 33, 100, 330, 1,000, or 3,300 ppm (equivalent to average daily doses of approximately 5, 10, 35, 100, or 220 mg/kg) for 14 weeks. All rats survived to the end of the study. Mean body weight gains of 3,300 ppm rats were significantly less than those of the controls. Water consumption by the 3,300 ppm male and female rats was significantly less than that by the controls. A minimal to mild anemia was observed in exposed female rats. The cauda epididymis and epididymis weights of 3,300 ppm males were significantly less than those of the controls. The percentage of abnormal sperm in 3,300 ppm males and the concentration of epididymal sperm in 330 ppm males were significantly increased compared to the controls. Kidney and liver weights of males and females exposed to 100 ppm or more were generally greater than those of the controls. The incidences of acinar cell degeneration and fatty change of the pancreas in 1,000 and 3,300 ppm rats, hepatocytic metaplasia of the pancreatic islets in 3,300 ppm females, cytoplasmic vacuolization of the liver in 100, 1,000 and 3,300 ppm males, and renal tubule epithelium regeneration in 3,300 ppm females were increased compared to the controls. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were administered 1-chloro-2-propanol in drinking water at concentrations of 0, 33, 100, 33entrations of 0, 33, 100, 330, 1,000, or 3,300 ppm (equivalent to average daily doses of approximately 5, 15, 50, 170, or 340 mg/kg to males and 7, 20, 70, 260, or 420 mg/kg to females) for 14 weeks. One 330 ppm male died before the end of the study. Mean body weight gains of exposed groups were similar to those of the controls. A minimal anemia was observed in 3,300 ppm males. The right epididymis weight of 3,300 ppm males was significantly greater than that of the controls. Kidney weights of 3,300 ppm mice, liver weights of 1,000 ppm males and of all exposed groups of females, and thymus weights of 1,000 and 3,300 ppm females were greater than those of the controls. The incidences of pancreatic acinar cell degeneration and fatty change in 3,300 ppm males and females and cytoplasmic vacuolization of the liver in all groups of exposed females were significantly increased compared to the controls. The severities of renal tubule cytoplasmic vacuolization were greater in 1,000 and 3,300 ppm males than in the controls. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were administered drinking water containing 0, 150, 325, or 650 ppm 1-chloro-2-propanol (equivalent to average daily doses of approximately 15, 30, or 65 mg/kg during the first several months of the study and 8, 17, or 34 mg/kg for the remainder of the 2-year study) for up to 105 weeks. Survival of all exposed groups was similar to that of the controls. Mean body weights of exposed rats were generally similar to those of the controls throughout most of the study. Water consumption by all exposed groups was similar to that by the controls. No treatment-related neoplasms or nonneoplastic lesions were observed in this study. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F1 mice were administered drinking water containing 0, 250, 500, or 1,000 ppm 1-chloro-2-propanol (equivalent to average daily doses of approximately 45, 75, or 150 mg/kg to males and 60, 105, or 210 mg/kg to females during the first several months of the study and 25, 50, or 100 mg/kg for the remainder of the 2-year study) for up to 105 weeks. Survival of all exposed groups was similar to that of the controls. The mean body weights of all exposed mice were generally similar to those of the controls throughout the study. Water consumption by all exposed groups was similar to that by the controls. No treatment- related neoplasms or nonneoplastic lesions were observed in this study. GENETIC TOXICOLOGY: 1-Chloro-2-propanol is a demonstrated mutagen in vitro. It was weakly mutagenic in S. typhimurium strain TA100 in the presence of hamster or rat liver S9 activation enzymes and was positive, with and without S9, in TA1535. No mutagenic activity was detected in strains TA97, TA98, and TA1537, with or without S9. In cytogenetic tests with Chinese hamster ovary cells, 1-chloro-2-propanol induced high levels of sister chromatid exchanges and chromosomal aberrations in the presence and the absence of S9. The marked ability of 1-chloro-2-propanol to induce chromosomal effects in vitro was not seen in vivo. Positive results were obtained in a test in D. melanogaster for induction of sex-linked recessive lethal mutations in germ cells of males administered 1-chloro-2-propanol via injection; however, negative results were obtained when males were administered 1-chloro-2-propanol in feed. A subsequent germ cell reciprocal translocation test in D. melanogaster yielded negative results. Further, no induction of micronucleated erythrocytes was observed in peripheral blood of male and female mice administered 1-chloro-2-propanol via drinking water for 14 weeks. CONCLUSIONS: Under the conditions of these 2-year drinking water studies, there was no evidence of carcinogenic activity of technical grade 1-chloro-2-propanol in male or female F344/N rats exposed to 150, 325, or 650 ppm. There was no evidence of carcinogenic activity of technical grade 1-chloro-2-propanol in male or female B6C3F1 mice exposed to 250, 500, or 1,000 ppm. Synonyms: 1-Chloro-2-hydroxypropane, 1-chloroisopropyl alcohol, propylene-α-chlorohydrin, sec-propylene chlorohydrin
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PMID:NTP Toxicology and Carcinogenesis Studies of 1-Chloro-2-propanol (Technical Grade) (CAS NO. 127-00-4) in F344/N Rats and B6C3F1 Mice (Drinking Water Studies. 1257 86

Oxazepam is one of a number of benzodiazepines used therapeutically as a sedative-hypnotic and antianxiety agent. Toxicology and carcinogenesis studies were performed by administering oxazepam (greater than 99% pure) in feed to male and female Swiss-Webster and B6C3F1 mice for 14 weeks, 57 weeks (Swiss-Webster), or 2 years (B6C3F1). Neurobehavioral assessments were performed during the studies. Genetic toxicology studies were conducted in Salmonella typhimurium and cultured Chinese hamster ovary cells, and peripheral blood samples were analyzed for frequency of micronucleated normochromatic erythrocytes. Supplemental studies were performed to compare the metabolism and toxicokinetics of oxazepam in the two mouse strains, to evaluate the effect on liver cell replication rates, to perform clinical pathology assessments, and to examine the mutation spectrum and frequency of activated H-ras oncogenes in liver neoplasms from the 2-year study with B6C3F1 mice. 14-WEEK STUDY IN SWISS-WEBSTER MICE: Groups of 10 male and 10 female Swiss-Webster mice received oxazepam in feed at concentrations of 0, 625, 1,250, 5,000, 10,000 ppm for 14 weeks. One 625 ppm male and one 10,000 female were killed moribund before the end of the study, and the condition of the female mouse was attributed to oxazepam exposure. Mean body weight gains of exposed groups were similar to those of the controls. Exposed mice displayed chemical-related sedation and lethargy during the first study week, but appeared normal thereafter. In the neurobehavioral studies, reductions in grip strength were evident in both male and female mice at week 2 and persisted in males through week 11. An antianxiety effect was detected in exposed mice in measures of motor activity, startle response, and reactions to thermal stimulus. At necropsy, absolute and relative liver weights were increased in an exposure-related manner and were approximately two-fold greater in 10,000 ppm mice than in controls. Centrilobular hepatocellular hypertrophy was present only in exposed mice, and the severity increased with dose. 14-WEEK STUDY IN B6C3F1 MICE: Groups of 10 male and 10 female B6C3F1 mice received oxazepam in feed at concentrations of 0, Groups of 10 male and 10 female Swiss-Webster mice 625, 1,250, 2,500, 5,000, or 10,000 ppm for 14 weeks. received oxazepam in feed at concentrations of 0, There were no deaths that were clearly related to 625,1,250, 2,500, 5,000, or 10,000 ppm for 14 weeks. oxazepam exposure. Mean body weight gains of One 625 ppm male and one 10,000 ppm female were exposed groups were similar to those of the controls. Exposed mice displayed chemical-related sedation and lethargy during only the first study week. In neurobehavioral studies, reductions in grip strength were evident in males at week 2 but were no longer observed at week 12. An antianxiety effect was noted in exposed mice in measures of motor activity, startle response, and reactions to a thermal stimulus (females). At necropsy, absolute and relative liver weights were increased in an exposure-related manner and were approximately two-fold greater in 10,000 ppm mice than in controls. Centrilobular hepatocellular hypertrophy was present only in exposed mice, and the severity increased with dose. CHRONIC STUDIES: Groups of 60 male and 60 female Swiss-Webster and B6C3F1 mice received oxazepam in feed at concentrations of 0, 2,500, or 5,000 ppm. Additional groups of 60 male and 60 female B6C3F1 mice received 125 ppm in feed to allow for study of a group with projected serum concentrations of oxazepam similar to those achieved in humans taking a therapeutic dose. Ten male and 10 female B6C3F1 mice per group were evaluated at 15 months. Average daily oxazepam consumption varied throughout the studies, and the overall daily average ranged from 10 to 29 mg/kg body weight for the 125 ppm groups, 234 to 512 mg/kg for the 2,500 ppm groups, and 444 to 1,085 mg/kg for the 5,000 ppm groups. Serum oxazepam concentrations determined at 57 weeks in Swiss-Webster mice and at the 15-month interim evaluation of B6C3F1 mice 1 mice were approximately 1 ug/mL in the 125 ppm groups, 4 to 7 μg/mL in the 2,500 ppm groups, and 7 to 10 μg/mL in the 5,000 ppm groups. Neurobehavioral assessments during the chronic studies of each strain of mice were confounded by the poor survival and deteriorating condition of mice with hepatic neoplasia. However, within the limitations of the studies, there were no notable changes in the types of behaviors observed compared to those observed in the 14-week studies, nor was there an enhancement in the degree to which they were exhibited. 57-Week Study in Swiss-Webster Mice: Survival, Body Weights, Feed and Compound Consumption, and Clinical Findings: At 57 weeks, survival of exposed mice was significantly lower than that of controls (males: O ppm, 45/60; 2,500 ppm, 19/60; 5,000 ppm, 10/60; females: 47/60, 28/59, 17/59), causing the study to be terminated. Mean body weights of exposed males were similar to controls until week 17; afterwards, mean body weights of exposed male groups were lower than those of controls. Final mean body weights of exposed males were 9% lower than that of the controls. The mean body weight of 2,500 ppm females was greater than that of the controls throughout the study. Females receiving 5,000 ppm had a mean body weight greater than that of the controls early in the study; after week 29, the mean body weight of this group was similar to that of the controls. Feed consumption by exposed males and females was slightly lower than that by the controls, and females in all groups, including controls, consumed slightly more feed than males throughout the study. Dietary levels of 2,500 and 5,000 ppm oxazepam resulted in average daily compound consumption levels of 270 and 570 mg/kg for males and 320 and 670 mg/kg for females. Hypoactivity and sedation were observed in exposed mice during the first week of the study. There were no other clinical findings associated with oxazepam exposure. Pathology Findings: Systemic amyloidosis was the principal cause of death in mice dying before the study was terminated. The lower survival of mice receiving oxazepam was attributed to an increase in the extent and severity of amyloid deposits in many organs, including the heart and kidney. Atrial thrombosis and pulmonary lesions consistent with chronic heart failure occurred at higher incidences and with greater severity in exposed mice. The incidence of hepatocellular adenomas (males: 1/60, 35/60, 50/60; females: 0/60, 22/59, 47/59) and carcinomas (males: 0/60, 5/60,19/60; females: 1/60, 1/59, 11/59) were increased in exposed mice. The incidences of eosinophilic foci were also increased in exposed mice (males: 0/60, 22/60, 22/60; females: 0/60, 20/59, 14/59), and there was evidence of increased centrilobular hepatocyte hypertrophy (males: 12/60, 46/60, 47/60; females: 3/60, 51/59, 53/59). 2-Year Study in B6C3F1 Mice: Survival, Body Weights, Feed and Compound Consumption, and Clinical Findings: Survival of mice receiving 2,500 and 5,000 ppm was significantly lower than that of controls (males: O ppm, 45/50; 125 ppm, 44/50; 2,500 ppm, 15/50; 5,000 ppm, 0/50; females: 39/50, 41/50, 2/50, 0/50). Mean body weight gains of exposed male and female mice were similar to controls until about week 15 when weight gains for mice exposed to 2,500 or 5,000 ppm slowed in relation to controls, resulting in weight gains approximately 30% to 40% lower than those of the controls throughout the remainder of the study. Mean body weight gain of male mice exposed to 125 ppm was similar to that of the controls, while that of female mice receiving 125 ppm was 10% to 15% lower than that of the controls after about week 45. Feed consumption by exposed males and females was similar to that by controls. Dietary levels of 125, 2,500, and 5,000 ppm resulted in average daily oxazepam consumption levels of 12, 310, and 690 mg/kg body weight for males and 15, 350, and 780 mg/kg for females. In the 5,000 ppm groups, lethargy and sedation were observed in a few mice during the first week of study. Pathology Findings: The early deaths of many of the B6C3F1 mice exposed to oxazepam were attributed to a marked increase in the incidences of hepatoblastoma (males: 0/49, 2/50, 21/50, 13/50; females: 0/50, 1/50, 8/50, 8/50), hepatocellular adenoma (males: 17/49,18/50, 34/50, 32/50; females: 25/50, 35/50, 35/50, 36/50), and hepatocellular carcinoma (males: 9/49, 5/50, 45/50, 50/50; females: 9/50, 5/50, 49/50, 44/50). Moderate hypertrophy of centrilobular hepatocytes occurred in mice receiving 2,500 and 5,000 ppm (males: 0/49, 2/50, 26/50, 43/50; females: 0/50, 2/50,11/50, 29/50). An increase in the incidence of follicular cell hyperplasia of the thyroid gland occurred in all exposed groups of mice (males: 4/49, 22/50, 49/50, 47/50; females: 16/50, 34/50, 49/50, 44/50), and thyroid gland follicular cell adenoma was increased in exposed females (0/50, 4/50, 5/50, 6/50). Testicular atrophy occurred in the 2,500 and 5,000 ppm groups (1/50, 0/50, 25/50, 38/50), and the incidence of epididymal Iymphocyte infiltration was increased in all exposed groups (2/50,14/50, 33/50, 21/50). The frequency of hepatocellular neoplasms with an activated H-ras oncogene in the B6C3F1 mice and the mutation spectrum of the H-ras gene were determined. The mutation spectrum of the H-ras genes in the relatively few neoplasms from exposed mice that did have an activated H-ras did not differ from the spectrum of mutations observed in neoplasms from controls, but the proportion of neoplasms with an activated H-ras gene decreased with increasing oxazepam dose. While 11 of 19 (58%) neoplasms from control mice had an activated H-ras gene, only 1 of 40 neoplasms from mice receiving 2,500 or 5,000 ppm oxazepam exhibited a similar molecular lesion. Thirteen of 37 (35%) neoplasms from mice in the 125 ppm group had an activated H-ras oncogene, suggesting that, although the incidence of all liver neoplasms was not statistically increased compared to controls, there was an increase in a similar subset of neoplasms (lacking an activated H-ras) that occurred with increased incidence at higher doses. SUPPLEMENTAL STUDIES: Because exposure to oxazepam caused increased incidences of liver neoplasms, supplemental short-term studies were performed. Oxazepam given in feed to male B6C3F1 mice at 25, 125, 2,500, or 5,000 ppm for up to 13 weeks was found to cause a dose-related increase in nuclear labeling index in studies measuring the incorporation of bromodeoxyuridine into replicating liver cells. This increase was statistically significant at all but the 25 ppm exposure level and was limited to mice evaluated at 15 days. Cell replication rates in most groups evaluated at 30 days and after were similar to control rates. There was minimal evidence suggestive of hepatocyte necrosis either by light microscopy or in clinical chemistry measures. There was, however, evidence of cholestasis, likely due to physical obstruction of bile canaliculi by swollen hepatocytes. The metabolic fate and toxicokinetics of oxazepam were evaluated in each strain of mice and were compared to published data from human studies. Both mice and humans form glucuronides of oxazepam and form 3- and 4-hydroxy and methoxy derivatives of the phenyl group. Oxidative metabolism of the phenyl group appears to be more prevalent in mice than is reported for humans. Elimination half-lives of parent compound do not differ between Swiss-Webster and B6C3F1 mice and are similar to values reported for humans. GENETIC TOXICOLOGY: Oxazepam was not mutagenic in any of several strains of Salmonella typhimurium, nor did it induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells. These in vitro tests were performed with and without S9 metabolic activation. Results from an in vivo mouse peripheral blood micronucleus test performed on the B6C3F1 mice used in the 14-week study were also negative. CONCLUSIONS: Under the conditions of these feed studies, there was clear evidence of carcinogenic activity of oxazepam in male and female Swiss-Webster mice based on increased incidences of hepatocellular adenoma and carcinoma. There was clear evidence of carcinogenic activity of oxazepam in male and female B6C3F1 mice based on increased incidences of hepatoblastoma and hepatocellular adenoma and carcinoma. Increased incidences of hyperplasia of thyroid gland follicular cells in male and female B6C3F1 mice and of follicular cell adenomas in female B6C3F1 mice were also related to oxazepam exposure. Administration of oxazepam to Swiss-Webster mice resulted in centrilobular hepatocellular hypertrophy and increased incidences and severity of systemic amyloidosis. Administration of oxazepam to B6C3F1 mice also resulted in centrilobular hepatocellular hypertrophy. Synonyms: 7-Chloro-1,3-dihydro-3-hydroxy-5-phenyl-2 H - 1,4-benzodiazepin-2-one Trade Names: Tazepam, Wy-3498, Serax
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PMID:NTP Toxicology and Carcinogenesis Studies of Oxazepam (CAS No. 604-75-1) in Swiss-Webster and B6C3F1 Mice (Feed Studies). 1259 20

Dicyclohexylcarbodiimide is used in industry as a stabilizing agent, coupling agent, and condensing agent. Its widespread use during protein synthesis in the recombinant DNA industry and in the synthesis of polypeptides in the chemical and pharmaceutical industries provides an increasing potential for low-level human exposure. Dicyclohexylcarbodiimide was nominated for study by The National Cancer Institute as a key representative of the carbodiimide chemical class because of its acute toxicity and the absence of data on potential health effects. Male and female F344/N rats and B6C3F 1 mice were administered dicyclohexylcarbodiimide (greater than 98% pure) dermally for 3 or 13 weeks. Female Tg.AC hemizygous and p53 haploinsufficient mice were administered dicyclohexylcarbodiimide dermally for 20 or 27 weeks, respectively. Genetic toxicology studies were conducted in Salmonella typhimurium, male F344/N rat bone marrow cells, and B6C3F 1 mouse peripheral blood erythrocytes. 3-WEEK STUDY IN F344/N RATS Groups of five male and five female rats were dermally administered 0.3 mL ethanol containing 0, 0.6, 1.8, 5.1, 15, or 45 mg dicyclohexylcarbodiimide, 5 days per week for 3 weeks. All males and females in the 15 and 45 mg groups, four 5.1 mg males, and all 5.1 mg females died before the end of the study. Of the surviving groups, final mean body weights were similar to those of the vehicle controls, although the one surviving 5.1 mg male rat lost weight during the study. Histopathologic examination of rats dosed with 5.1 mg dicyclohexylcarbodiimide or less revealed treatment-related lesions of the skin at the site of application including epidermal hyperplasia, epidermal necrosis, or chronic active inflammation in the dermis. 3-WEEK STUDY IN B6C3F 1 MICE Groups of five male and five female mice were dermally administered 0.1 mL of ethanol containing 0, 0.2, 0.6, 1.7, 5, or 15 mg dicyclohexylcarbodiimide, 5 days per week for 3 weeks. One 0.6 mg female mouse and all mice in the 1.7, 5, and 15 mg groups died before the end of the study. Final mean body weights of the 0.6 mg groups were significantly less than those of the vehicle controls, and animals in these groups generally lost weight during the study. Histopathologic examination of mice dosed with 1.7 mg dicyclohexylcarbodiimide or less revealed treatment-related lesions of the skin at the site of application including epidermal hyperplasia, epidermal necrosis, and acute or chronic active dermal inflammation. 13-WEEK STUDY IN F344/N RATS Groups of 10 male and 10 female core study rats were dermally administered 0, 0.75, 1.5, 3, 6, or 12 mg dicyclohexylcarbodiimide/kg body weight in ethanol, 5 days per week for 13 weeks; groups of 10 male and 10 female clinical pathology study rats were administered the same doses for 22 days. All 12 mg/kg male and female core study rats died or were found moribund and sacrificed prior to day 45. Final mean body weight and body weight gain of 6 mg/kg males were significantly less than those of the vehicle controls. The predominant clinical pathology changes suggest a secondary, treatment-related inflammatory leukogram and minimal decreased erythron of chronic inflammation that would be consistent with necrosis and chronic active inflammation of the skin. Significantly increased incidences of skin lesions at the site of application included epidermal hyperplasia in 3 mg/kg or greater males and 1.5 mg/kg or greater females, chronic active inflammation in 6 and 12 mg/kg males and 1.5 mg/kg or greater females, and epidermal necrosis in 12 mg/kg males. The incidences and severities of epidermal hyperplasia increased in a dose-related manner in both sexes of rats 13-WEEK STUDY IN B6C3F 1 MICE Groups of 10 male and 10 female mice were dermally administered 0, 1.5, 3, 6, 12, or 24 mg dicyclohexylcarbodiimide/kg body weight in ethanol, 5 days per week for 13 weeks. All 24 mg/kg male and female mice died or were found moribund and sacrificed prior to day 16. Final mean body weights of 6 and 12 mg/kg males and mean body weight gains of 6 and 12 mg/kg males and females were significantly less than those of the vehicle controls. The predominant clinical pathology changes suggest a secondary, treatment-related inflammatory leukogram and minimal decreased erythron of chronic inflammation that would be consistent with necrosis and chronic active inflammation of the skin. Dermal administration of dicyclohexylcarbodiimide significantly decreased the weight of the epididymis in 6 and 12 mg/kg males and significantly decreased epididymal spermatozoal motility in 6 mg/kg males. Significantly increased incidences of skin lesions at the site of application included epidermal hyperplasia in all dosed groups except those administered 24 mg/kg, chronic active inflammation in all dosed groups except 1.5 mg/kg females, and epidermal necrosis in 24 mg/kg males and females. 20-WEEK STUDY IN FEMALE TG.AC HEMIZYGOUS MICE Groups of 10 female Tg.AC hemizygous mice were dermally administered 0, 0.75, 1.5, 3, 6, or 12 mg dicyclohexylcarbodiimide/kg body weight in ethanol, 5 days per week for up to 20 weeks. Due to the severity of skin lesions observed in 12 mg/kg animals, the application of dicyclohexylcarbodiimide was discontinued after eight dermal applications in this group. There were no deaths considered related to dicyclohexylcarbodiimide administration, although 13 animals died or were sacrificed moribund prior to the end of the study: three each from the vehicle control and 0.75 mg/kg groups, four from the 3 mg/kg group, two from the 6 mg/kg group, and one from the 12 mg/kg group. Overall, the survival was within the range known for the Tg.AC hemizygous mouse. Mean body weights of dosed groups of mice were similar to those of the vehicle controls. At the site of application, the incidences of squamous cell papilloma were increased in a dose-related manner. The incidences of chronic active inflammation of the dermis and epidermal hyperplasia were significantly increased in mice administered 3 or 6 mg/kg. 27-WEEK STUDY IN FEMALE p53 HAPLOINSUFFICIENT MICE Groups of 15 female mice were dermally administered 0, 0.75, 1.5, 3, 6, or 12 mg dicyclohexylcarbodiimide/kg body weight in ethanol, 5 days per week for up to 27 weeks. Dosing of the 6 and 12 mg/kg groups was discontinued after 11 and 8 days, respectively, because of the severity of skin lesions at the site of application. Twelve animals died or were sacrificed moribund prior to the end of the study: three from the 3 mg/kg group, one from the 6 mg/kg group, and eight from the 12 mg/kg group. Mean body weights of dosed groups of mice were similar to those of the vehicle controls. No neoplasms were attributed to administration of dicyclohexylcarbodiimide. At the site of application, the incidences of focal epidermal hyperplasia were significantly increased in 1.5, 3, and 12 mg/kg mice, the incidences of focal chronic active inflammation of the dermis were increased in groups administered 3 or 12 mg/kg, and the incidences of focal ulcer and focal chronic active inflammation of the subcutaneous tissue were increased in the 12 mg/kg group. GENETIC TOXICOLOGY Dicyclohexylcarbodiimide was not mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, or TA1535, with or without rat or hamster liver S9 activation enzymes. In vivo, there was a small but significant increase in the frequency of micronucleated normochromatic erythrocytes in male and female B6C3F 1 mice after 13 weeks of dermal exposure to dicyclohexylcarbodiimide. Negative results were obtained, however, in an acute three-injection micronucleus study in bone marrow of male F344/N rats. CONCLUSIONS Under the conditions of this 27-week dermal study, there was no evidence of carcinogenic activity* of dicyclohexylcarbodiimide in female p53 haploinsufficient mice administered 0.75, 1.5, 3, 6, or 12 mg/kg in ethanol. Female Tg.AC hemizygous mice dermally dosed with dicyclohexylcarbodiimide for 20 weeks had significantly increased incidences of squamous cell papilloma of the skin at the site of application. Nonneoplastic lesions noted at the site of application included chronic active inflammation and epidermal hyperplasia in female p53 haploinsufficient mice and female Tg.AC hemizygous mice.
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PMID:NTP report on the toxicology studies of dicyclohexylcarbodiimide (CAS No. 538-75-0) in F344/N rats, B6C3F 1 mice, and genetically modified (FVB Tg.AC hemizygous) mice and carcinogenicity study of dicyclohexylcarbodiimide in genetically modified [B6.129-Trp53 tm1Brd (N5) haploinsufficient] mice (dermal studies). 1878 65