F344/NTac Rats Chronically Exposed to Bromodichloroacetic Acid Develop Mammary Adenocarcinomas With Mixed Luminal/Basal Phenotype and Tgfß Dysregulation.

Breast cancer is the most common cancer and the second-leading cause of cancer mortality in women in the United States. A recent 2-year National Toxicology Program carcinogenicity study showed an increased incidence of proliferative mammary lesions (hyperplasia, fibroadenoma, adenocarcinoma) in F344/NTac rats exposed to bromodichloroacetic acid (BDCA), a disinfection by-product in finished drinking water with widespread human exposure. We hypothesized that the increase in mammary tumors observed in BDCA-exposed F344/NTac rats may be due to underlying molecular changes relevant for human breast cancer. The objective of the study was to compare (1) gene and protein expression and (2) mutation spectra of relevant human breast cancer genes between normal untreated mammary gland and mammary tumors from control and BDCA-exposed animals to identify molecular changes relevant for human cancer. Histologically, adenocarcinomas from control and BDCA-exposed animals were morphologically very similar, were estrogen/progesterone receptor positive, and displayed a mixed luminal/basal phenotype. Gene expression analysis showed a positive trend in the number of genes associated with human breast cancer, with proportionally more genes represented in the BDCA-treated tumor group. Additionally, a 5-gene signature representing possible Tgfß pathway activation in BDCA-treated adenocarcinomas was observed, suggesting that this pathway may be involved in the increased incidence of mammary tumors in BDCA-exposed animals.

Genetic pathways and mutation profiles of human cancers: site- and exposure-specific patterns.

Cancer is a complex disease that involves the accumulation of both genetic and epigenetic alterations of numerous genes. Data in the Genetic Alterations in Cancer database for gene mutations and allelic loss [loss of heterozygosity (LOH)] in human tumors (e.g. lung, oral, esophagus, stomach and colon/rectum) were reviewed. Results for the genes and pathways implicated in tumor development at these sites are presented. Mutation incidence, spectra and codon specificity are described for lung, larynx and oral tumors. LOH occurred more frequently than gene mutations in tumors from all sites examined. The cell cycle gene, TP53 (all sites), and cell signaling gene, APC (colorectal and gastric cancers), were the only genes with similar incidences of LOH and mutation. Alterations of one or more cell cycle and cell signaling genes were reported for tumors from each site. Site-specific activation was apparent in the cell signaling mitogen-activated protein kinase oncogenes (KRAS in lung, HRAS in oral cancers and BRAF in esophageal and colorectal cancers). Analysis of genetic changes in lung tumors showed that the incidence of mutations in the TP53 and KRAS genes and the incidence of LOH in the FHIT gene were significantly greater in smokers versus non-smokers (P < 0.01). In lung and oral cancers, the TP53 GC --> TA transversion frequency increased with tobacco smoke exposure (P < 0.05). Furthermore, the TP53 mutational hot spots for lung and laryngeal cancers from smokers included codons 157, 245 and 273, whereas for oral tumors included codons 280 and 281.

ORIOGEN: order restricted inference for ordered gene expression data.

UNLABELLED: ORIOGEN is a user-friendly Java-based software package for selecting and clustering genes according to their profiles across various treatment groups. In particular, ORIOGEN is useful for analyzing data obtained from time-course or dose-response type experiments. AVAILABILITY: The ORIOGEN software can be downloaded freely from http://dir.niehs.nih.gov/dirbb/oriogen/index.cfm CONTACT: peddada@niehs.nih.gov (for statistical questions) and oriogen@constellagroup.com (for software support) SUPPLEMENTARY INFORMATION: ORIOGEN has a full set of help files. Also, an example input file is provided with the download.

Osteonecrosis in a chemically induced rat model of human hemolytic disorders associated with thrombosis--a new model for avascular necrosis of bone.

Bone injury occurs in human hemolytic disorders associated with thrombosis, such as beta-thalassemia and sickle cell disease. Exposure of rats to 2-butoxyethanol (BE) has been associated with hemolytic anemia, disseminated thrombosis, and infarction in multiple organs including bone. This rat model apparently mimics acute hemolysis and thrombosis in humans. To elucidate the extent of bone injury, male and female Fischer F344 rats were given 4 daily doses of 250 mg BE/5 ml water/kg of body weight. Tail vertebrae were studied by histopathology and magnetic resonance imaging (MRI). Thrombosis and infarction were seen in both sexes, but females were more severely affected. Lesions were characterized by extensive medullary fat necrosis, granulomatous inflammation, fibroplasia, growth plate degeneration, and new woven bone formation adjacent to necrotic bone trabeculae. MRI mean and standard deviation tissue-density data for both sexes indicated a significant (P < or = 0.05) decrease following 4-days treatment and a significant increase (P < or = 0.05) following an additional 24 days without treatment. Thus, MRI was useful in revealing BE-induced bone injury, which was predominantly necrotic initially and subsequently regenerative with proliferation of connective tissue and bone following postischemia recovery.

The role of oxidative stress in indium phosphide-induced lung carcinogenesis in rats.

Indium phosphide (IP), widely used in the microelectronics industry, was tested for potential carcinogenicity. Sixty male and 60 female Fischer 344 rats were exposed by aerosol for 6 h/day, 5 days/week, for 21 weeks (0.1 or 0.3 mg/m(3); stop exposure groups) or 105 weeks (0 or 0.03 mg/m(3) groups) with interim groups (10 animals/group/sex) evaluated at 3 months. After 3-month exposure, severe pulmonary inflammation with numerous infiltrating macrophages and alveolar proteinosis appeared. After 2 years, dose-dependent high incidences of alveolar/bronchiolar adenomas and carcinomas occurred in both sexes; four cases of squamous cell carcinomas appeared in males (0.3 mg/m(3)), and a variety of non-neoplastic lung lesions, including simple and atypical hyperplasia, chronic active inflammation, and squamous cyst, occurred in both sexes. To investigate whether inflammation-related oxidative stress functioned in the pathogenesis of IP-related pulmonary lesions, we stained lungs of control and high-dose animals immunohistochemically for four markers indicative of oxidative stress: inducible nitric oxide synthase (i-NOS), cyclooxygenase-2 (COX-2), glutathione-S-transferase Pi (GST-Pi), and 8-hydroxydeoxyguanosine (8-OHdG). Paraffin-embedded samples from the 3-month and 2-year control and treated females were used. i-NOS and COX-2 were highly expressed in inflammatory foci after 3 months; at 2 years, all four markers were expressed in non-neoplastic and neoplastic lesions. Most i-NOS staining, mainly in macrophages, occurred in chronic inflammatory and atypical hyperplastic lesions. GST-Pi and 8-OHdG expression occurred in cells of carcinoma epithelium, atypical hyperplasia, and squamous cysts. These findings suggest that IP inhalation causes pulmonary inflammation associated with oxidative stress, resulting in progression to atypical hyperplasia and neoplasia.

Tests for order restrictions in binary data.

In this article, a general procedure is presented for testing for equality of k independent binary response probabilities against any given ordered alternative. The proposed methodology is based on an estimation procedure developed in Hwang and Peddada (1994, Annals of Statistics 22, 67-93) and can be used for a very broad class of order restrictions. The procedure is illustrated through application to two data sets that correspond to three commonly encountered order restrictions: simple tree order, simple order, and down turn order.

Longitudinal assessment of hormonal and physical alterations during normal puberty in boys. VI. Modeling of growth velocity, mean growth hormone (GH mean), and serum testosterone (T) concentrations.

The growth and hormonal status of 23 prepubertal and early pubertal normally growing boys were evaluated for at least 6 years as they entered and progressed through puberty. Each subject was observed during a 24-hr hospital admission approximately every 4 months. Standing height was measured upon arising. At the same time an early morning (0600hr) serum level of testosterone was obtained. A mean growth hormone level was determined from a pool of equal quantities of serum from 72 samples obtained every 20 min for 24 hr. The early morning testosterone level was used as an index of pubertal status. The effect of the chronological age, mean growth hormone, and testosterone levels on the growth velocity was investigated. In addition to age, the interaction between the mean growth hormone level and testosterone concentration has a significant effect on the velocity of growth. Several nonlinear models were explored to describe growth velocity, mean growth hormone level, and testosterone concentration in terms of chronological age of each subject. Models used were chosen for simplicity, interpretability of the model itself and its parameters, and the ability to estimate (and then test) the parameters. Unknown parameters of the model were estimated using ordinary least squares (OLS), which minimizes the L(2) norm of the observed and the predicted values. The L(2) norm may be unduly influenced by outlying observations which commonly occur in many biological data sets. Hence, in addition to the OLS estimators, the least absolute deviation (LAD) estimator which minimizes the L(1) norm of the observed and the predicted values was also considered. Typically, the LAD estimators are more robust than OLS estimators. From a clinical point of view it may be important to know the "normal" values of growth velocity, mean growth hormone level, and testosterone at a given age during puberty. For this reason population models for each of these variables along with their 90% confidence regions were developed. These will permit identification of those children who are outside the boundaries of normal growth for the purpose of evaluation for the etiology of the deviation. Am. J. Hum. Biol. 12:814-824, 2000. Copyright 2000 Wiley-Liss, Inc.

Factors affecting the thickness of the cervical prevertebral soft tissues.

Lateral cervical spine films of 227 patients examined over 2 years were analyzed to determine the thickness of the soft tissues anterior to C2 through C4. These measurements were correlated with patient age, sex, weight, shoulder width, neck width, and calculated radiographic magnification. We found that only patient weight and age had any statistically significant effect on the soft tissue thickness. A stepwise regression model produced a simple equation for predicting the mean value of the soft tissue thickness (specifically at C3) using the patient's age and weight: C3 width = 3.7 mm-0.02 x age (years) + 0.01 x weight (pounds). Using this formula we determined that weight and age account for 28% of the observed variability in the soft tissue measurements at C3. These relationships were similar at C2 and C4. Interestingly, patient sex and radiographic magnification had no detectable effect on the measured widths.