PBDE-47 and PBDE mixture (DE-71) toxicities and liver transcriptomic changes at PND 22 after in utero/postnatal exposure in the rat.

Pentabromodiphenyl ethers (PBDE) are found in human tissue, in household dust, and in the environment, and a particular concern is the potential for the induction of cancer pathways from these fat-soluble persistent organic pollutants. Only one PBDE cancer study has been conducted and that was for a PBDE mixture (DE-71). Because it is not feasible to test all PBDE congeners in the environment for cancer potential, it is important to develop a set of biological endpoints that can be used in short-term toxicity studies to predict disease outcome after long-term exposures. In this study, PBDE-47 was selected as the test PBDE congener to evaluate and compare toxicity to that of the carcinogenic PBDE mixture. The toxicities of PBDE-47 and the PBDE mixture were evaluated at PND 22 in Wistar Han rat (Crl: WI (Han)) pups after in utero/postnatal exposure (0, 0.1, 15, or 50 mg/kg; dams, GD6-21; pups, PND 12-PND 21; oral gavage daily dosing). By PND 22, PBDE-47 caused centrilobular hypertrophy and fatty change in liver, and reduced serum thyroxin (T4) levels; similar effects were also observed after PBDE mixture exposure. Transcriptomic changes in the liver included induction of cytochrome p450 transcripts and up-regulation of Nrf2 antioxidant pathway transcripts and ABC membrane transport transcripts. Decreases in other transport transcripts (ABCG5 & 8) provided a plausible mechanism for lipid accumulation, characterized by a treatment-related liver fatty change after PBDE-47 and PBDE mixture exposure. The benchmark dose calculation based on liver transcriptomic data was generally lower for PBDE-47 than for the PBDE mixture. The up-regulation of the Nrf2 antioxidant pathway and changes in metabolic transcripts after PBDE-47 and PBDE mixture exposure suggest that PBDE-47, like the PBDE mixture (NTP 2016, TR 589), could be a liver toxin/carcinogen after long-term exposure.

Immunohistochemical Expression of Cyclin D1, Cytokeratin 20, and Uroplakin III in Proliferative Urinary Bladder Lesions Induced by o-Nitroanisole in Fischer 344/N Rats.

o-Nitroanisole is an intermediate in the manufacture of azo dyes. In a National Toxicology Program stop-exposure study,o-nitroanisole induced hyperplasia, papillomas, and papillary carcinomas in the urinary bladder of Fischer 344/N rats.o-Nitroanisole was investigated since occupational or environmental exposure to aniline and azo dyes is a risk factor for urinary bladder cancer in humans. The current study describes the morphology of urinary bladder neoplasms seen in rats with respect to those observed in humans. This study also evaluated immunohistochemical expression of the cell cycle-related proteins cyclin D1 and p53 and the differentiation markers cytokeratin 20 and uroplakin III in hyperplastic (n= 11) and neoplastic (n= 6 papillomas,n= 11 carcinomas) lesions of the urinary bladder epithelium from rats treated with o-nitroanisole and in normal (n= 6) urinary bladders from untreated rats. The tumors observed were more similar to the papillary type rather than the muscle-invasive type of urinary bladder cancer in humans. The preneoplastic and neoplastic lesions observed suggest progression from hyperplasia to papilloma to papillary carcinoma. With neoplastic progression (hyperplasia to papilloma to carcinoma), cyclin D1 immunoreactivity progressively increased in intensity, percentage of cells staining, and distribution. Overexpression of p53 was not found. Cytokeratin 20 staining decreased in superficial cells, while uroplakin III staining increased in intermediate and basal cells with progression from hyperplasia to carcinoma. The results are consistent with increased cell cycle dysregulation or proliferation (cyclin D1), decreased differentiation (cytokeratin 20), and abnormal differentiation (uroplakin III) as lesions progress toward malignancy.

Environmental chemical exposure may contribute to uterine cancer development: studies with tetrabromobisphenol A.

Tetrabromobisphenol A (TBBPA), a widely used flame retardant, caused uterine tumors in rats. In this study, TBBPA was administered to male and female Wistar Han rats and B6C3F1/N mice by oral gavage in corn oil for 2 years at doses up to 1,000 mg/kg. TBBPA induced uterine epithelial tumors including adenomas, adenocarcinomas, and malignant mixed Müllerian tumors (MMMTs). In addition, endometrial epithelial atypical hyperplasia occurred in TBBPA-treated rats. Also found to be related to TBBPA treatment, but at lower incidence and at a lower statistical significance, were testicular tumors in rats, and hepatic tumors, hemangiosarcomas (all organs), and intestinal tumors in male mice. It is hypothesized that the TBBPA uterine tumor carcinogenic mechanisms involve altered estrogen levels and/or oxidative damage. TBBPA treatment may affect hydroxysteroid-dehydrogenase-17ß (HSD17ß) and/or sulfotransferases, enzymes involved in estrogen homeostasis. Metabolism of TBBPA may also result in the formation of free radicals. The finding of TBBPA-mediated uterine cancer in rats is of concern because TBBPA exposure is widespread and endometrial tumors are a common malignancy in women. Further work is needed to understand TBBPA cancer mechanisms.

Tubal ligation in relation to menopausal symptoms and breast cancer risk.

BACKGROUND: Local inflammation after tubal ligation may affect ovarian function and breast cancer risk. METHODS: We analysed tubal ligation, menopausal characteristics, and breast cancer risk in the Sister Study cohort (N=50,884 women). RESULTS: Tubal ligation was associated with hot flashes (hazard ratio (HR) 1.09; 95% confidence interval (CI): 1.06-1.12) but not menopausal age (HR 0.99; 95% CI: 0.96-1.02). Tubal ligation did not have an impact on breast cancer overall (HR 0.95; 95% CI: 0.85-1.06), but had a suggested inverse relation with oestrogen receptor+/progesterone receptor+ invasive tumours (HR 0.84; 95% CI: 0.70-1.01), possibly because of subsequent hysterectomy/bilateral oophorectomy. CONCLUSION: Tubal ligation does not influence overall breast cancer risk.

The concentration of bisphenol A in urine is affected by specimen collection, a preservative, and handling.

In urine specimens that were collected from pregnant women in a large cohort, 24% contained more than 10 ng/ml of total bisphenol A (BPA), suggesting external contamination. Therefore, we conducted an investigation of the source(s) of extraneous BPA in the specimens. We found that under the conditions used to collect urine specimens in the epidemiologic study, contamination with BPA occurred, and by two separate mechanisms.

Urethral carcinoma and hyperplasia in male and female B6C3F1 mice treated with 3,3',4,4'-tetrachloroazobenzene (TCAB).

B6C3F1 mice chronically exposed to 3,3',4,4'-tetrachloroazobenzene (TCAB), a contaminant of dichloroaniline-derived herbicides, developed a number of neoplastic and nonneoplastic lesions, including carcinoma of the urinary tract. Groups of fifty male and fifty female B6C3F1 mice were exposed by gavage to TCAB at dose levels of 0, 3, 10, and 30 mg/kg five days a week for two years. Control animals received corn oil:acetone (99:1) vehicle. Decreased survival of male mice in the mid-dose group and of male and female mice in the high-dose groups was related mainly to the occurrence of urethral transitional cell (urothelial) carcinoma and resulting urinary obstruction. Increased urethral transitional cell carcinomas were seen in all treated male groups in a dose-related manner as well as in the females treated with 30 mg/kg TCAB. Administration of TCAB was also associated with increased transitional cell hyperplasia of the urethra. Most nonneoplastic lesions of the urogenital tract were considered secondary to local invasion and urinary obstruction by the urethral transitional cell carcinomas. The mechanism of tumor induction is uncertain, but the high frequency of tumors in the proximal urethra of male mice suggests that the neoplasms result from the exposure of a susceptible population of urothelial cells to a carcinogenic metabolite of TCAB.

Carcinogenesis studies of cresols in rats and mice.

Cresols, monomethyl derivatives of phenol, are high production chemicals with potential for human exposure. The three isomeric forms of cresol are used individually or in mixtures as disinfectants, preservatives, and solvents or as intermediates in the production of antioxidants, fragrances, herbicides, insecticides, dyes, and explosives. Carcinogenesis studies were conducted in groups of 50 male F344/N rats and 50 female B6C3F1 mice exposed to a 60:40 mixture of m- and p-cresols (m-/p-cresol) in feed. Rats and mice were fed diets containing 0, 1500, 5000, or 15,000 ppm and 0, 1000, 3000, or 10,000 ppm, respectively. Survival of each exposed group was similar to that of their respective control group. Mean body weight gains were depressed in rats exposed to 15,000 ppm and in mice exposed to 3000 ppm and higher. A decrease of 25% over that of controls for the final mean body weight in mice exposed to 10,000 ppm appeared to be associated with lack of palatability of the feed. A marginally increased incidence of renal tubule adenoma was observed in the 15,000-ppm-exposed rats. The increased incidence was not statistically significant, but did exceed the range of historical controls. No increased incidence of hyperplasia of the renal tubules was observed; however, a significantly increased incidence of hyperplasia of the transitional epithelium associated with an increased incidence of nephropathy was observed at the high exposure concentration. The only significantly increased incidence of a neoplastic lesion related to cresol exposure observed in these studies was that of squamous cell papilloma in the forestomach of 10,000-ppm-exposed mice. A definitive association with irritation at the site-of-contact could not be made because of limited evidence of injury to the gastric mucosa at the time of necropsy. However, given the minimal chemical-related neoplastic response in these studies, it was concluded that there was no clear evidence of carcinogenicity in male rats or female mice exposed to the cresol mixture.

Genetic susceptibility to progressive massive fibrosis in coal miners.

Progressive massive fibrosis (PMF) is a chronic interstitial lung disease with a complex aetiology that can occur after cumulative dust exposure. A case-control study was conducted to test the hypothesis that single nucleotide polymorphisms (SNPs) within genes involved in inflammatory and fibrotic processes modulate the risk of PMF development. The study population consisted of 648 underground coal miners participating in the National Coal Workers Autopsy Study, of which 304 were diagnosed with PMF. SNPs that influence the regulation of interleukin (IL)-1, IL-6, tumour necrosis factor-alpha, transforming growth factor-beta1, vascular endothelial growth factor (VEGF), epidermal growth factor intercellular cell adhesion molecule (ICAM)-1 and matrix metalloproteinase-2 genes were determined using a 5'-nuclease real-time PCR assay. There were no significant differences in the distribution of any individual SNP or haplotype between the PMF and control groups. However, the polygenotype of VEGF +405/ICAM-1 +241/IL-6 -174 (C-A-G) conferred an increased risk for PMF (odds ratio 3.4, 95% confidence interval 1.3-8.8). The present study suggests that the examined genetic variations that help regulate inflammatory and fibrotic processes are unlikely to strongly influence susceptibility to this interstitial lung disease, although the role of vascular endothelial growth factor, intercellular cell adhesion molecule-1 and interleukin-6 polymorphisms in the development of progressive massive fibrosis may require further investigation.

Carcinogenic activity of pentabrominated diphenyl ether mixture (DE-71) in rats and mice.

Pentabrominated diphenyl ether (PBDE) flame retardants have been phased out in Europe and in the United States, but these lipid soluble chemicals persist in the environment and are found human and animal tissues. PBDEs have limited genotoxic activity. However, in a 2-year cancer study of a PBDE mixture (DE-71) (0, 3, 15, or 50 mg/kg (rats); 0, 3, 30, or 100 mg/kg (mice)) there were treatment-related liver tumors in male and female Wistar Han rats [Crl:WI(Han) after in utero/postnatal/adult exposure, and in male and female B6C3F1 mice, after adult exposure. In addition, there was evidence for a treatment-related carcinogenic effect in the thyroid and pituitary gland tumor in male rats, and in the uterus (stromal polyps/stromal sarcomas) in female rats. The treatment-related liver tumors in female rats were unrelated to the AhR genotype status, and occurred in animals with wild, mutant, or heterozygous Ah receptor. The liver tumors in rats and mice had treatment-related Hras and Ctnnb mutations, respectively. The PBDE carcinogenic activity could be related to oxidative damage, disruption of hormone homeostasis, and molecular and epigenetic changes in target tissue. Further work is needed to compare the PBDE toxic effects in rodents and humans.

Carcinogenesis studies of benzophenone in rats and mice.

Benzophenone, an aryl ketone, is used primarily as a photoinitiator and fragrance enhancer. Groups of 50 male and 50 female F344 rats and B6C3 F1 mice were fed diets containing 0, 312, 625, and 1250 ppm benzophenone for 105 weeks. Survival of males exposed to 1250 ppm benzophenone was significantly less than that of controls. There was a positive trend in the incidence of renal tubule adenoma in male rats; these neoplasms were accompanied by significantly increased incidences of renal tubule hyperplasia. Increased incidences of mononuclear cell leukemia were observed in male rats exposed to 312 or 625 ppm benzophenone and in female rats exposed to 625 ppm benzophenone. Liver lesions observed included significantly increased incidences of hepatocytic centrilobular hypertrophy in all exposed groups of rats. In mice, survival of all exposed groups was generally similar to that of the control groups. In male mice, there were significantly increased incidences of hepatocellular adenoma in the 625 and 1250 ppm groups. In female mice, the incidences of hepatocellular adenoma in the 625 and 1250 ppm groups were higher than expected after adjusting for the lower body weights in these groups. The incidences of kidney nephropathy in exposed groups of female mice, as well as the severity of nephropathy in exposed groups of males, were significantly increased. The incidences of metaplasia of the olfactory epithelium were significantly increased in 1250 ppm mice. Rare histiocytic sarcomas were observed in female rats and mice in the 625 and 1250 ppm groups. Under the conditions of these 2-year studies, there was some evidence of carcinogenic activity of benzophenone in male F344/N rats based on increased incidences of renal tubule adenoma. There was equivocal evidence of carcinogenic activity of benzophenone in female F344/N rats based on the marginal increased incidences of mononuclear cell leukemia and histiocytic sarcoma. There was some evidence of carcinogenic activity of benzophenone in male B6C3F(1) mice based on increased incidences of hepatocellular neoplasms, primarily adenoma. There was some evidence of carcinogenic activity of benzophenone in female B6C3F(1) mice based on increased incidences of histiocytic sarcoma; the incidences of hepatocellular adenoma in female B6C3F(1) mice may have been related to benzophenone exposure.

Absence of acrylamide-induced genotoxicity in CYP2E1-null mice: evidence consistent with a glycidamide-mediated effect.

Acrylamide, an animal carcinogen and germ cell mutagen present at low (ppm) levels in heated carbohydrate-containing foodstuffs, is oxidized by cytochrome P4502E1 (CYP2E1) to the epoxide glycidamide, which is believed to be responsible for the mutagenic and carcinogenic activity of acrylamide. We recently reported a comparison of the effects of acrylamide on the genetic integrity of germ cells of male wild-type and CYP2E1-null mice [B.I. Ghanayem, K.L. Witt, L. El-Hadri, U. Hoffler, G.E. Kissling, M.D. Shelby, J.B. Bishop, Comparison of germ-cell mutagenicity in male CYP2E1-null and wild-type mice treated with acrylamide: evidence supporting a glycidamide-mediated effect, Biol. Reprod. 72 (2005) 157-163]. In those experiments, dose-related increases in dominant lethal mutations were detected in uterine contents of female mice mated to acrylamide-treated wild-type males but not CYP2E1-null males, clearly implicating CYP2E1-mediated formation of glycidamide in the induction of genetic damage in male germ cells. We hypothesized that acrylamide-induced somatic cell damage is also caused by glycidamide. Therefore, to examine this hypothesis, female wild-type and CYP2E1-null mice were administered acrylamide (0, 25, 50mg/kg) by intraperitoneal injection once daily for 5 consecutive days. Twenty-four hours after the final treatment, blood and tissue samples were collected. Erythrocyte micronucleus frequencies were determined using flow cytometry and DNA damage was assessed in leukocytes, liver, and lung using the alkaline (pH>13) single cell gel electrophoresis (Comet) assay. Results were consistent with the earlier observations in male germ cells: significant dose-related increases in micronucleated erythrocytes and DNA damage in somatic cells were induced in acrylamide-treated wild-type but not in the CYP2E1-null mice. These results support the hypothesis that genetic damage in somatic and germ cells of mice-treated with acrylamide is dependent upon metabolism of the parent compound by CYP2E1. This dependency on metabolism has implications for the assessment of human risks resulting from occupational or dietary exposure to acrylamide. CYP2E1 polymorphisms and variability in CYP2E1 activity associated with, for example, diabetes, obesity, starvation, and alcohol consumption, may result in altered metabolic efficiencies leading to differential susceptibilities to acrylamide toxicities in humans.

Endothelial damage in monkeys after radial keratotomy performed with a diamond blade.

Anterior radial keratotomy was performed with a diamond blade in ten rhesus monkey eyes. Results were compared with those of a previous study in which a metal blade was used. Histologic assessment showed endothelial degeneration, but fewer edematous endothelial cells, than in the previous study. Specular microscopy demonstrated statistically significant endothelial cell losses (7.99%), when preoperative and three-month postoperative values were compared. Autoradiography showed little cell division in the endothelial cell layer. Cell loss seemed to be repaired mainly by the spreading of neighboring cells. Endothelial cell division is also limited in humans, and the cumulative loss of cells due to surgical trauma combined with continuous damage-related losses and later age-related reductions in cell numbers could produce corneal decompensation in some patients years after radial keratotomy.

Topical application of hyaluronic acid and chondroitin sulfate in the treatment of dry eyes.

Twenty patients with keratoconjunctivitis sicca used three different viscoelastic tear formulations and a polyvinyl alcohol artificial tear for two weeks each. Each formulation was used once every two waking hours in a controlled double-masked study. Eighteen patients reported marked improvement over the course of the study, in terms of the severity of itching, burning, and foreign body sensation. Corneal staining and mucous strand formation were also reduced in patients with these manifestations. No formulation was preferred by a majority of patients or proved superior in treating signs of keratoconjunctivitis sicca. However, patients with low Schirmer test scores uniformly preferred a solution containing chondroitin sulfate, while patients with moderate Schirmer test scores tended to prefer a solution of polyvinyl alcohol or hyaluronic acid.

Effect of the herpes simplex virus genome on the response of infection to corticosteroids.

The type and severity of ocular herpetic disease, as well as the pattern of recurrence, have been shown to be determined by the virus genome. We infected rabbit eyes with two closely related recombinant strains of herpes simplex virus type 1 and treated one half of the eyes in each group with corticosteroids before or immediately after virus inoculation. The severity of disease in the first week was similar in the treated and untreated eyes infected with the F(MP)F strain; however, with F(MP)E infection, the disease in the treated eyes was significantly worse than the disease in the untreated eyes. Cultures of corneal virus showed similar titers in all of the groups, but cultures of trigeminal ganglia indicated that increased severity of disease did not result in an increased tendency toward ganglionic colonization. The results suggest that the response to corticosteroids is another factor that is determined by the genetics of the infecting virus, but that there is no correlation between worsening of disease with corticosteroid treatment and the establishment of virus latency.

Corticosteroid therapy after anterior radial keratotomy in Primates.

Anterior radial keratotomy was performed on nine Green monkey eyes. Four of these eyes received subconjunctival corticosteroid injections immediately after surgery and three times thereafter at three-week intervals. Two eyes received subconjunctival physiologic salt solution injections on the same schedule. Three eyes received no injections after surgery. Although endothelial cell loss in the first week after surgery was reduced in the drug-treated eyes, there were no statistically significant differences in cell densities at nine months after surgery. Corticosteroid therapy after anterior radial keratotomy appeared to confer no long-range benefits in terms of the numbers of corneal endothelial cells in these primate eyes.

Acyclovir in the treatment of herpetic stromal disease.

Seventeen patients (ten women and seven men, 23 to 72 years old) with stromal herpetic disease were treated with topical and oral acyclovir for 14 days. Of the 12 patients with disciform edema, five showed minimal improvement, four showed no change, and three showed worsening of their disease. Of the five patients with necrotizing stromal keratitis, one improved, one showed no change, and three became worse. The patients who had been treated with corticosteroids previously had a statistically significantly worse outcome than those who had not been so treated. One patient with necrotizing stromal keratitis showed virus particles in tissue specimens obtained by superficial lamellar keratectomy. Thus, acyclovir was not effective in the treatment of disciform edema or necrotizing stromal keratitis. Further studies are needed to ascertain whether the drug is therapeutically ineffective or whether acyclovir did not reach the stroma in amounts sufficient to affect the course of stromal disease in the human eye.

Benefits of computerized outcome analysis in diabetes management.

OBJECTIVE: To observe the effects of a computerized relational database designed to measure outcomes and enhance adherence to recommended diabetes management guidelines in a specialty private practice setting. METHODS: DiaTrends, a software program specifically designed to monitor the processes and outcomes of diabetes care, was introduced in a private endocrinology practice in 1996. Information on all patients with diabetes (N = 1,096) was recorded in the database. Reports ("queries") were developed to monitor the adherence to recommended guidelines and to assess the outcomes of care for patients with diabetes treated with glucose-lowering medications. Glycosylated hemoglobin (HbA(1c)) and lipid control were selected from the many outcomes and processes of care monitored as the basis of this report. RESULTS: Data were collected on 1,096 patients between 1996 and 1998. We were able to monitor adherence to published diabetes guidelines and to document the outcomes. Parallel trends toward improvement were noted in both HbA(1c) and lipid variables. The average HbA(1c) achieved for the entire patient population was 7.3%. CONCLUSION: Using a computerized database to monitor glycemic control and lipid management is effective in evaluating the outcomes of care and provides a focused approach that enhances diabetes care. These improvements in metabolic outcomes likely reflect a change in the practice patterns of the physicians as a consequence of using this computerized database system.

Age and fibroplasia as preconditions for atheronecrosis in human coronary arteries.

The first 8 cm of the left circumflex, anterior descending, and right coronary arteries in 173 autopsies of men and women aged 15 to 69 years were examined in hematoxylineosin-stained, paraffin-embedded sections. With increasing age, the intima thickened with fibroproliferative tissue, approaching a threshold of about 150 micron, beyond which atheronecrosis became likely. Compared with the lateral thoracic aorta, the coronaries revealed (1) lower threshold for atheronecrosis, (2) thinner nonnecrotic intima, (3) fewer smooth-muscle cells present at lower densities, (4) less extensive foam cell infiltration in non-atherosclerosis-related cause-of-death cases, and (5) a prominent association of foam cell infiltration with atherosclerosis-related causes of death, which was lacking in the aorta. It is suggested that the lower threshold for atheronecrosis in the coronaries compared with the aorta might be related to the relative deficiency of smooth-muscle cells and foam cells.

Comparisons of human populations for histologic features of atherosclerosis. A summary of questions and methods for geographic studies.

Aortas and coronary arteries from six populations were studied histologically. Two kinds of fibrous plaques could be defined morphometrically, a fibroplastic and an atheronecrotic kind. These two kinds of abnormality were quantitated, the percentage of the specimen affected by atheronecrosis being one quantity, and the average fibroplastic thickness of nonnecrotic intima being the other. These two quantities were found to be correlated with each other, showing that aortas or coronary arteries severely affected by one of these processes tended to be seriously affected also by the other process. This correlation persisted after age adjustment. The two processes, however, failed to parallel each other across population boundaries. Moreover, some of the subjects with coronary heart disease had excessive fibroplasia with minimal atheronecrosis, while others had excessive atheronecrosis with minimal fibroplasia, as if an excess of only one or the other can be fatal. A novel theory is proposed to explain these and other results. It is proposed that the arterial intima undergoes fibroplastic thickening under the time-dependent action of one set of hypothetical causes and that another set of hypothetical causes promotes the emergence of atheronecrosis in the most thickened and aged places. These two sets of causes appear to be independent of each other in their distribution among human populations.

Age and fibroplasia as preconditions for atheronecrosis in the human thoracic aorta.

The atheronecrotic core of an aortic plaque is an easily recognized structural feature when present in histologic sections. This feature tends to be associated with other characteristics of the aorta, chief among these being old age, marked intimal fibroplasia, and diminished numbers of intimal smooth-muscle cells. The statistical relationships among these aortic characteristics were examined in a series of 356 autopsies. Intimal fibroplasia tended to be directly proportional to age. The density of smooth-muscle cells tended to be inversely proportional to intimal fibroplasia. The total cellularity of the intima was almost constant without regard to age or intimal thickness. The probability of finding atheronecrosis in a randomly chosen sample from the lateral thoracic aorta was directly proportional to age and to intimal thickness after appropriate mathematical transformations. Against this background of what is usual, two atypical kinds of lesion were identified.