Maternal plasma cortisol's effect on offspring birth weight: a Mendelian Randomisation study

BACKGROUND

Observational studies and randomized controlled trials have found evidence that higher maternal circulating cortisol levels in pregnancy are associated with lower offspring birth weight. However, it is possible that the observational associations are due to residual confounding.

METHODS

We performed two-sample Mendelian Randomisation (MR) using a single genetic variant (rs9989237) associated with morning plasma cortisol (GWAS; sample 1; N = 25,314). The association between this maternal genetic variant and offspring birth weight, adjusted for fetal genotype, was obtained from the published EGG Consortium and UK Biobank meta-analysis (GWAS; sample 2; N = up to 406,063) and a Wald ratio was used to estimate the causal effect. We also performed an alternative analysis using all GWAS reported cortisol variants that takes account of linkage disequilibrium. We also tested the genetic variant's effect on pregnancy cortisol and performed PheWas to search for potential pleiotropic effects.

RESULTS

The estimated effect of maternal circulating cortisol on birth weight was a 50 gram (95% CI, -109 to 10) lower birth weight per 1 SD higher log-transformed maternal circulating cortisol levels, using a single variant. The alternative analysis gave similar results (-33 grams (95% CI, -77 to 11)). The effect of the cortisol variant on pregnancy cortisol was 2-fold weaker than in the original GWAS, and evidence was found of pleiotropy.

CONCLUSIONS

Our findings provide some evidence that higher maternal morning plasma cortisol causes lower birth weight. Identification of more independent genetic instruments for morning plasma cortisol are necessary to explore the potential bias identified.

Fibrin Gel Induces the Migration of Smooth Muscle Cells from Rabbit Aortic Explants

A major step in the pathogenesis of atherosclerosis is the vectorial migration of smooth muscle cells (SMCs) from the arterial media into the intima. Although subcultured SMCs usually show synthetic phenotype, the behaviour of contractile SMCs may be crucial for the subsequent migration of the cells. In the present study, we utilized an in vitro assay system to evaluate the effects of fibrin gels on the migration of SMCs from explants taken from rabbit aorta. After cultured for 5-7 days in a serum-free condition, SMCs appeared from explants covered with fibrin gel. The cells were positive on immunostaining for SMC specific α-actin. No migration of SMCs from the control explants without fibrin gel was observed. Then the percentage of explants showing cell migration and the number of migrating cells increased with time. The migration of SMCs into fibrin gels was not dependent on the concentration of fibrinogen used for the preparation of fibrin gel in the range of 1.5-3 mg/ml. Variations of thrombin concentration in the range of 0.25-1.25 U/ml had no significant effect. However, there was less migration of SMCs with higher concentrations of thrombin. Thrombin inhibitors, hirudin and PPACK had no significant effect on the migration of SMCs. An RGD-containing peptide, GRGDS inhibited the migration of SMCs although a control peptide GRGES at the same concentration had no significant effect. A monoclonal antibody to αvβ3, LM609, completely inhibited the migration of SMCs from the explants, suggesting that αvβ3 integrin is involved in the migration of SMCs into fibrin gels. SMCs which migrated from the explants showed the positive staining with the monoclonal antibodies against SMC myosin heavy chain isoforms, SMemb, SM1 and SM2, suggesting that they are in an intermediate state changing from contractile to synthetic state. In conclusion, the present study showed that fibrin gel induces the migration of SMCs from explants into itself and the process may not need other growth factors or cytokines.

Chromium Is Elevated in Fin Whale (Balaenoptera physalus) Skin Tissue and Is Genotoxic to Fin Whale Skin Cells

Hexavalent chromium (Cr(VI)) is present in the marine environment and is a known carcinogen and reproductive toxicant. Cr(VI) is the form of chromium that is well absorbed through the cell membrane. It is also the most prevalent form in seawater. We measured the total Cr levels in skin biopsies obtained from healthy free-ranging fin whales from the Gulf of Maine and found elevated levels relative to marine mammals in other parts of the world. The levels in fin whale biopsies ranged from 1.71 to 19.6 μg/g with an average level of 10.07 μg/g. We also measured the cytotoxicity and genotoxicity of Cr(VI) in fin whale skin cells. We found that particulate and soluble Cr(VI) are both cytotoxic and genotoxic to fin whale skin cells in a concentration-dependent manner. The concentration range used in our cell culture studies used environmentally relevant concentrations based on the biopsy measurements. These data suggest that Cr(VI) may be a concern for whales in the Gulf of Maine.

The association of PM(2.5) with full term low birth weight at different spatial scales

There is interest in determining the relationship between fine particulate matter air pollution and various health outcomes, including birth outcomes such as term low birth weight. Previous studies have come to different conclusions. In this study we consider whether the effect may vary by location and gestational period. We also compare results when using different spatial resolutions for the air concentration estimates. Among the seven states considered, New Jersey and New York had the highest PM2.5 levels (average full gestation period exposures of 13 µg/m(3)) and the largest rate of low birth weight births (2.6 and 2.8%, respectively); conversely Utah and Minnesota had the lowest PM2.5 levels (9 µg/m(3)) and the lowest rates of low birth weight births (2.1 and1.9%, respectively). There is an association between PM2.5 exposure and low birth weight in New York for the full gestation period and all three trimesters, in Minnesota for the full gestation period and the first and third trimesters, and in New Jersey for the full gestation period and the first trimester. When we pooled the data across states, the OR for the full gestation period was 1.030 (95% CI: 1.022-1.037) and it was highest for the first trimester (OR 1.018; CI: 1.013-1.022) and decreasing during the later trimesters. When we used a finer spatial resolution, the strengths of the associations tended to diminish and were no longer statistically significant. We consider reasons why these differences may occur and their implications for evaluating the effects of PM2.5 on birth outcomes.

Hexavalent chromium is cytotoxic and genotoxic to hawksbill sea turtle cells

Sea turtles are a charismatic and ancient ocean species and can serve as key indicators for ocean ecosystems, including coral reefs and sea grass beds as well as coastal beaches. Genotoxicity studies in the species are absent, limiting our understanding of the impact of environmental toxicants on sea turtles. Hexavalent chromium (Cr(VI)) is a ubiquitous environmental problem worldwide, and recent studies show it is a global marine pollutant of concern. Thus, we evaluated the cytotoxicity and genotoxicity of soluble and particulate Cr(VI) in hawksbill sea turtle cells. Particulate Cr(VI) was both cytotoxic and genotoxic to sea turtle cells. Concentrations of 0.1, 0.5, 1, and 5μg/cm(2) lead chromate induced 108, 79, 54, and 7% relative survival, respectively. Additionally, concentrations of 0, 0.1, 0.5, 1, and 5μg/cm(2) lead chromate induced damage in 4, 10, 15, 26, and 36% of cells and caused 4, 11, 17, 30, and 56 chromosome aberrations in 100 metaphases, respectively. For soluble Cr, concentrations of 0.25, 0.5, 1, 2.5, and 5μM sodium chromate induced 84, 69, 46, 25, and 3% relative survival, respectively. Sodium chromate induced 3, 9, 9, 14, 21, and 29% of metaphases with damage, and caused 3, 10, 10, 16, 26, and 39 damaged chromosomes in 100 metaphases at concentrations of 0, 0.25, 0.5, 1, 2.5, and 5μM sodium chromate, respectively. These data suggest that Cr(VI) may be a concern for hawksbill sea turtles and sea turtles in general.

Chemical dispersants used in the Gulf of Mexico oil crisis are cytotoxic and genotoxic to sperm whale skin cells

The 2010 Deepwater Horizon oil rig explosion in the Gulf of Mexico drew attention to the need for toxicological studies of chemical dispersants. We are still learning the effects these spills had on wildlife. Little is known about the toxicity of these substances in marine mammals. The objective of this study was to determine the toxicity of the two dispersants (Corexit 9500 and 9527). Corexit 9500 and 9527 were both cytotoxic to sperm whale skin fibroblasts. Corexit 9527 was less cytotoxic than 9500. S9 mediated metabolism did not alter cytotoxicity of either dispersant. Both dispersants were genotoxic to sperm whale skin fibroblasts; S9 mediated metabolism increased Corexit 9527 genotoxicity.

Global assessment of arsenic pollution using sperm whales (Physeter macrocephalus) as an emerging aquatic model organism

Arsenic is an oceanic pollutant of global concern due to its toxicity, ability to bioaccumulate and continued input into the environment by anthropogenic activities. The sperm whale (Physeter macrocephalus) is an emerging aquatic model for both human disease and ocean health having global distribution and high trophic level. The aim of this study was to establish global and regional baselines of total arsenic concentrations using free-ranging sperm whales. Skin biopsies (n=342) were collected during the voyage of the Odyssey (2000-2005) from 17 regions considering gender and age in males. Arsenic was detectable in 99% of samples with a global mean of 1.9μg/g ww ranging from 0.1 to 15.6μg/g ww. Previous work in toothed whale skin found mean concentrations 3 fold lower with 0.6μg/g ww. A significant gender-related effect was found with males having higher mean arsenic concentrations than females. There was no significant age-related effect between adult and subadult males. Arsenic concentrations in sloughed skin samples were similar to levels in skin biopsies indicating that arsenic excretion can occur by skin sloughing. Regional mean concentrations were highest in the Maldives, Seychelles and Sri Lanka with 3.5, 2.5, and 2.4μg/g ww, respectively, raising concern for arsenic pollution in the Indian Ocean. Literature suggests that arsenic exposure is emitted from natural sources and the heavy use of arsenic-containing pesticides and herbicides in this region. These data suggest that research is needed in determining the extent and source of arsenic pollution in the Indian Ocean.

Concentrations of the genotoxic metals, chromium and nickel, in whales, tar balls, oil slicks, and released oil from the gulf of Mexico in the immediate aftermath of the deepwater horizon oil crisis: is genotoxic metal exposure part of the deepwater horizon legacy?

Concern regarding the Deepwater Horizon oil crisis has largely focused on oil and dispersants while the threat of genotoxic metals in the oil has gone largely overlooked. Genotoxic metals, such as chromium and nickel, damage DNA and bioaccumulate in organisms, resulting in persistent exposures. We found chromium and nickel concentrations ranged from 0.24 to 8.46 ppm in crude oil from the riser, oil from slicks on surface waters and tar balls from Gulf of Mexico beaches. We found nickel concentrations ranged from 1.7 to 94.6 ppm wet weight with a mean of 15.9 ± 3.5 ppm and chromium concentrations ranged from 2.0 to 73.6 ppm wet weight with a mean of 12.8 ± 2.6 ppm in tissue collected from Gulf of Mexico whales in the wake of the crisis. Mean tissue concentrations were significantly higher than those found in whales collected around the world prior to the spill. Given the capacity of these metals to damage DNA, their presence in the oil, and their elevated concentrations in whales, we suggest that metal exposure is an important understudied concern for the Deepwater Horizon oil disaster.

Global assessment of oceanic lead pollution using sperm whales (Physeter macrocephalus) as an indicator species

Lead (Pb) is an oceanic pollutant of global concern. Anthropogenic activities are increasing oceanic levels, but to an unknown extent. The sperm whale (Physeter macrocephalus) has a global distribution and high trophic level. The aim of this study was to establish a global baseline of oceanic Pb concentrations using free-ranging sperm whales as an indicator species. Skin biopsies (n=337) were collected during the voyage of the Odyssey (2000-2005) from 17 regions considering gender and age. Pb was detectable in 315 samples with a global mean of 1.6 ug/gww ranging from 0.1 to 129.6 ug/gww. Papua New Guinea, Bahamas and Australia had the highest regional mean with 6.1, 3.4, and 3.1 ug/gww, respectively. Pb concentrations were not significantly different between sex and age in males. This is the first global toxicological dataset for Pb in a marine mammal and confirms Pb is widely distributed with hotspots in some regions.

Global mercury and selenium concentrations in skin from free-ranging sperm whales (Physeter macrocephalus)

Pollution of the ocean by mercury (Hg) is a global concern. Hg persists, bioaccumulates and is toxic putting high trophic consumers at risk. The sperm whale (Physeter macrocephalus), is a sentinel of ocean health due to its wide distribution, longevity and high trophic level. Our aim was to survey Hg concentrations worldwide in the skin of free-ranging sperm whales considering region, gender and age. Samples were collected from 343 whales in 17 regions during the voyage of the research vessel, Odyssey, between 1999 and 2005. Skin was analyzed for total Hg and detected in all but three samples with a global mean of 2.5±0.1 μg g(-1) ranging from 0.1 to 16.0 μg g(-1). The Mediterranean Sea had the highest regional mean with 6.1 μg g(-1) followed by Australia with 3.5 μg g(-1). Considering gender, females and males did not have significantly different global Hg concentrations. The variation among regions for females was significantly different with highest levels in the Mediterranean and lowest in Sri Lanka; however, males were not significantly different among regions. Considering age in males, adults and subadults did not have significantly different Hg concentrations, and were not significantly different among regions. The toxic effects of these Hg concentrations are uncertain. Selenium (Se), an essential element, antagonizes Hg at equimolar amounts. We measured total Se concentrations and found detectable levels in all samples with a global mean of 33.1±1.1 μg g(-1) ranging from 2.5 to 179 μg g(-1). Se concentrations were found to be several fold higher than Hg concentrations with the average Se:Hg molar ratio being 59:1 and no correlation between the two elements. It is possible Hg is being detoxified in the skin by another mechanism. These data provide the first global analysis of Hg and Se concentrations in a free-ranging cetacean.

Excising squamous cell carcinomas: comparing the performance of GPs, hospital skin specialists and other hospital specialists

BACKGROUND

GPs have no defined role in the excision of squamous cell carcinomas (SCCs). Current guidelines recommend that all skin lesions suspicious of SCC should be referred urgently to secondary care. Evidence regarding current management of SCC in primary care is limited. Existing audit data suggest that up to 10% of SCCs may be excised in primary care. GPs may be able to have a greater role in the management of SCC but more evidence is required before this can be advocated.

OBJECTIVE

To compare the practice of GPs, skin specialists (dermatologists and plastic surgeons) and other hospital specialists in excising SCCs. Methods . A retrospective analysis of all SCCs excised in the Grampian region between 1 January and 31 December 2005. A total of 1184 reports were rated for source and adequacy of excision.

RESULTS

GPs excised 23.7% of all SCC-positive biopsies. Whether the biopsy had been performed by a GP or a hospital skin specialist made no significant difference to excision adequacy. However, GPs were significantly more likely to excise adequately than hospital non-specialists (P < 0.001). Infrequent GP excisers appear to perform as well as frequent excisers in adequately excising SCCs.

CONCLUSIONS

GPs excise a considerable number of SCCs in primary care. GPs compare favourably to skin specialists in excising SCCs. The performance of infrequent GP excisers does not appear to differ significantly from that of frequent GP excisers. Further work is required to define more clearly the role of GPs in the management of SCCs.

Abstract 3102: Hexavalent chromium induces chromosome instability leading to DNA double strand break repair deficiency and neoplastic transformation

Chromosome instability (CIN) is a hallmark of lung cancer with cells exhibiting both translocations and aneuploidy. Hexavalent chromium (Cr(VI)) is a well known respiratory carcinogen. The ability of Cr(VI) to induce chromosomal translocations is unknown. We exposed human lung cells to lead chromate for three sequential 24 h periods, each separated by about a month. After each treatment, cells were seeded at colony forming density, cloned, expanded and retreated. Each generation of clones was tested for chromium sensitivity, chromosome complement, ability to repair DNA double strand breaks (DSB), and growth in soft agar. We found that after the first treatment, lead chromate-treated cells exhibited a normal chromosome complement though a few clones showed a decrease in cell survival. After the second exposure, more than half of the clones acquired an abnormal karyotype including numerical and structural changes. The third treatment resulted in additional abnormal clones as well as previously abnormal clones acquiring more abnormalities. Clones were treated with soluble Cr(VI) for 24 h followed by a 24 h recovery period to measure DNA DSB repair. Abnormal clones showed persistent H2A.X and 53BP1 foci formation after 24 h recovery suggesting that these clones had acquired a DNA DSB repair-deficient phenotype. In addition, clones from the third generation were able to form colonies in soft agar suggesting that the cells have neoplastically transformed. This work was supported by NIEHS grant ES016893 (J.P.W.) and the Maine Center for Toxicology and Environmental Health.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3102. doi:1538-7445.AM2012-3102

Comparative cytotoxicity and genotoxicity of particulate and soluble hexavalent chromium in human and sperm whale (Physeter macrocephalus) skin cells

Chromium (Cr) is a global marine pollutant, present in marine mammal tissues. Hexavalent chromium [Cr(VI)] is a known human carcinogen. In this study, we compare the cytotoxic and clastogenic effects of Cr(VI) in human (Homo sapiens) and sperm whale (Physeter macrocephalus) skin fibroblasts. Our data show that increasing concentrations of both particulate and soluble Cr(VI) induce increasing amounts of cytotoxicity and clastogenicity in human and sperm whale skin cells. Furthermore, the data show that sperm whale cells are resistant to these effects exhibiting less cytotoxicity and genotoxicity than the human cells. Differences in Cr uptake accounted for some but not all of the differences in particulate and soluble Cr(VI) genotoxicity, although it did explain the differences in particulate Cr(VI) cytotoxicity. Altogether, the data indicate that Cr(VI) is a genotoxic threat to whales, but also suggest that whales have evolved cellular mechanisms to protect them against the genotoxicity of environmental agents such as Cr(VI).

Risk factors by molecular subtypes of breast cancer across a population-based study of women 56 years or younger

Differences in incidence, prognosis, and treatment response suggest gene expression patterns may discern breast cancer subtypes with unique risk factor profiles; however, previous results were based predominantly on older women. In this study, we examined similar relationships in women ≤ 56 years, classified by immunohistochemical staining for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 for 890 breast cancer cases and 3,432 frequency-matched population-based controls. Odds ratios (OR) and 95% confidence intervals (CI) for tumor subtypes were calculated using multivariate polytomous regression models. A total of 455 (51.1%) tumors were considered luminal A, 72 (8.1%) luminal B, 117 (13.1%) non-luminal HER-2/neu+, and 246 (27.6%) triple negative. Triple negative tumors were associated with breast feeding duration (per 6 months: OR = 0.76, 95% CI 0.64-0.90). Among premenopausal women, increasing body size was more strongly associated with luminal B (OR = 1.73, 95% CI 1.07-2.77) and triple negative tumors (OR = 1.67, 95% CI 1.22-2.28). A history of benign breast disease was associated only with increased risk of luminal A tumors (OR = 1.89, 95% CI 1.43-2.50). A family history of breast cancer was a risk factor for luminal A tumors (OR = 1.93, 95% CI 1.38-2.70) regardless of age, and triple negative tumors with higher risks for women <45 (OR = 5.02, 95% CI 2.82-8.92; P for age interaction = 0.005). We found that little-to-no breastfeeding and high BMI were associated with increased risk of triple negative breast cancer. That some risk factors differ by molecular subtypes suggests etiologic heterogeneity in breast carcinogenesis among young women.

Depleted uranium induces neoplastic transformation in human lung epithelial cells

Depleted uranium (DU) is commonly used in military armor and munitions, and thus, exposure of soldiers and noncombatants is frequent and widespread. Previous studies have shown that DU has both chemical and radiological toxicity and that the primary route of exposure of DU to humans is through inhalation and ingestion. However, there is limited research information on the potential carcinogenicity of DU in human bronchial cells. Accordingly, we determined the neoplastic transforming ability of particulate DU to human bronchial epithelial cells (BEP2D). We observed the loss of contact inhibition and anchorage independent growth in cells exposed to DU after 24 h. We also characterized these DU-induced transformed cell lines and found that 40% of the cell lines exhibit alterations in plating efficiency and no significant changes in the cytotoxic response to DU. Cytogenetic analyses showed that 53% of the DU-transformed cell lines possess a hypodiploid phenotype. These data indicate that human bronchial cells are transformed by DU and exhibit significant chromosome instability consistent with a neoplastic phenotype.

Comparative genotoxicity and cytotoxicity of four hexavalent chromium compounds in human bronchial cells

Hexavalent chromium (Cr(VI)) compounds are well-established human lung carcinogens. Solubility plays an important role in their carcinogenicity with the particulate Cr(VI) compounds being the most carcinogenic. Epidemiology and animal studies suggest that zinc chromate is the most potent particulate Cr(VI) compound; however, there are few comparative data to support these observations. The purpose of this study was to compare the genotoxicity of zinc chromate with two other particulate Cr(VI) compounds, barium chromate and lead chromate, and one soluble Cr(VI) compound, sodium chromate. The clastogenic effects of barium chromate and zinc chromate were similar, but lead chromate induced significantly less damage. The levels of DNA damage measured by gamma-H2A.X foci formation were similar for the three particulate chromium compounds. Corrected for chromium uptake differences, we found that zinc chromate and barium chromate were the most cytotoxic, and lead chromate and sodium chromate were less cytotoxic. Zinc chromate was more clastogenic than all other chromium compounds, and lead chromate was the least clastogenic. There was no significant difference between any of the compounds for the induction of DNA double strand breaks. All together, these data suggest that the difference in the carcinogenic potency of zinc chromate over the other chromium compounds is not due solely to a difference in chromium ion uptake and that the zinc cation may in fact have an important role in its carcinogenicity.

Abstract 3467: Repeated particulate chromate exposure induces chromosome instability and a DNA double strand break repair-deficient phenotype in human lung cells

Particulate hexavalent chromium (Cr(VI)) is a potent respiratory carcinogen with widespread human exposure. The particulate form, for example lead chromate, has been determined to be the most toxic and carcinogenic form. These particles impact at bifurcation sites of the lung and persist in the respiratory tract. Chromosome instability (CIN) is a hallmark of lung cancer with cells exhibiting both translocations and severe aneuploidy. However, the ability of Cr(VI) to induce translocations is unknown. We exposed human lung cells to lead chromate for three sequential 24 h periods, each separated by about a month. After each treatment, cells were seeded at colony forming density, cloned, expanded and retreated. Each generation of clones were tested for their chromium sensitivity, chromosome complement and DNA repair capacity. We found that after the first treatment, lead chromate-treated cells exhibited a normal chromosome complement though a few clones showed an increase in relative survival. After the second exposure, more than half of the clones acquired an abnormal karyotype including numerical and structural alterations. The third treatment resulted in more abnormal clones as well as previously abnormal clones acquiring additional abnormalities. Clones were also treated with soluble Cr(VI) for 24 h followed by a 24 h recovery period to measure DNA double strand break repair. Abnormal clones showed little or no reduction in H2A. X foci formation after 24 h recovery suggesting that these clones had acquired a DNA double strand break repair- deficient phenotype. This work was supported by NIEHS grant ES016893 (J.P.W.).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3467.

Privacy versus public health: the impact of current confidentiality rules

Public health research and practice often have been facilitated through the evaluation and study of population-based data collected by local, state, and federal governments. However, recent concerns about identify theft, confidentiality, and patient privacy have led to increasingly restrictive policies on data access, often preventing researchers from using these valuable data. We believe that these restrictions, and the research impeded or precluded by their implementation and enforcement, have had a significant negative impact on important public health research. Members of the public health community should challenge these policies through their professional societies and by lobbying legislators and health officials to advocate for changes that establish a more appropriate balance between privacy concerns and the protection of public health.

Behavioral changes in aging but not young mice after neonatal exposure to the polybrominated flame retardant decaBDE

BACKGROUND

After several decades of commercial use, the flame-retardant chemicals polybrominated diphenyl ethers (PBDEs) and their metabolites are pervasive environmental contaminants and are detected in the human body. Decabrominated diphenyl ether (decaBDE) is currently the only PBDE in production in the United States.

OBJECTIVES

Little is known about the health effects of decaBDE. In the present study we examined the effects of neonatal decaBDE exposure on behavior in mice at two ages.

METHODS

Neonatal male and female C57BL6/J mice were exposed to a daily oral dose of 0, 6, or 20 mg/kg decaBDE from postnatal days 2 through 15. Two age groups were examined: a cohort that began training during young adulthood and an aging cohort of littermates that began training at 16 months of age. Both cohorts were tested on a series of operant procedures that included a fixed-ratio 1 schedule of reinforcement, a fixed-interval (FI) 2-min schedule, and a light-dark visual discrimination.

RESULTS

We observed minimal effects on the light-dark discrimination in the young cohort, with no effects on the other tasks. The performance of the aging cohort was significantly affected by decaBDE. On the FI schedule, decaBDE exposure increased the overall response rate. On the light-dark discrimination, older treated mice learned the task more slowly, made fewer errors on the first-response choice of a trial but more perseverative errors after an initial error, and had lower latencies to respond compared with controls. Effects were observed in both dose groups and sexes on various measures.

CONCLUSIONS

These findings suggest that neonatal decaBDE exposure produces effects on behavioral tasks in older but not younger animals. The behavioral mechanisms responsible for the pattern of observed effects may include increased impulsivity, although further research is required.

Cytotoxicity and genotoxicity of hexavalent chromium in human and North Atlantic right whale (Eubalaena glacialis) lung cells

Humans and cetaceans are exposed to a wide range of contaminants. In this study, we compared the cytotoxic and genotoxic effects of a metal pollutant, hexavalent chromium [Cr(VI)], which has been shown to cause damage in lung cells from both humans and North Atlantic right whales. Our results show that Cr induces increased cell death and chromosome damage in lung cells from both species with increasing intracellular Cr ion levels. Soluble Cr(VI) induced less of a cytotoxic and genotoxic effect based on administered dose in right whale (Eubalaena glacialis) cells than in human (Homo sapiens) cells. Whereas, particulate Cr(VI) induced a similar cytotoxic effect but less of a genotoxic effect based on administered dose in right whale cells than in human cells. Differences in chromium ion uptake explained soluble chromate-induced cell death but not all of the soluble chromate-induced chromosome damage. Uptake differences of lead ions could explain the differences in particulate chromate-induced toxicity. The data show that both forms of Cr(VI) are less genotoxic to right whale than human lung cells, and that soluble Cr(VI) induces a similar cytotoxic effect in both right whale and human cells, while particulate Cr(VI) is more cytotoxic to right whale lung cells.

Birth and fetal death records and environmental exposures: promising data elements for environmental public health tracking of reproductive outcomes

OBJECTIVES

We inventoried and reviewed the birth and fetal death certificates of all 50 U.S. states to identify nonstandard data items that are environmentally relevant, inexpensive to collect, and might enhance environmental public health tracking.

METHODS

We obtained online or requested by mail or telephone the birth certificate and fetal death record forms or formats from each state. Every state data element was compared to the 2003 standards promulgated by the National Center for Health Statistics to identify any items that are not included on the standard. We then evaluated these items for their utility in environmentally related analyses.

RESULTS

We found three data fields of potential interest. First, although every state included residence of mother at time of delivery on the birth certificate, only four states collected information on how long the mother had lived there. This item may be useful in that it could be used to assess and reduce misclassification of environmental exposures among women during pregnancy. Second, we found that father's address was listed on the birth certificates of eight states. This data field may be useful for defining paternal environmental exposures, especially in cases where the parents do not live together. Third, parental occupation was listed on the birth certificates of 15 states and may be useful for defining parental workplace exposures. Our findings were similar for fetal death records.

CONCLUSION

If these data elements are accurate and well-reported, their addition to birth, fetal death, and other health records may aid in environmental public health tracking.

A global assessment of chromium pollution using sperm whales (Physeter macrocephalus) as an indicator species

Chromium (Cr) is a well-known human carcinogen and a potential reproductive toxicant, but its contribution to ocean pollution is poorly understood. The aim of this study was to provide a global baseline for Cr as a marine pollutant using the sperm whale (Physeter macrocephalus) as an indicator species. Biopsies were collected from free-ranging whales around the globe during the voyage of the research vessel The Odyssey. Total Cr levels were measured in 361 sperm whales collected from 16 regions around the globe detectable levels ranged from 0.9 to 122.6 microg Cr g tissue(-1) with a global mean of 8.8+/-0.9 microg g(-1). Two whales had undetectable levels. The highest levels were found in sperm whales sampled in the waters near the Islands of Kiribati in the Pacific (mean=44.3+/-14.4) and the Seychelles in the Indian Ocean (mean=19.5+/-5.4 microg g(-1)). The lowest mean levels were found in whales near the Canary Islands (mean=3.7+/-0.8 microg g(-1)) and off of the coast of Sri Lanka (mean=3.3+/-0.4 microg g(-1)). The global mean Cr level in whale skin was 28-times higher than mean Cr skin levels in humans without occupational exposure. The whale levels were more similar to levels only observed previously in human lung tissue from workers who died of Cr-induced lung cancer. We conclude that Cr pollution in the marine environment is significant and that further study is urgently needed.

Particulate hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and skin fibroblasts

Hexavalent chromium compounds are present in the atmosphere and oceans and are established mutagens and carcinogens in human and terrestrial mammals. However, the adverse effects of these toxicants in marine mammals are uncertain. Previously, we reported that North Atlantic right whales, one of the most endangered great whales, have tissue chromium levels that are high, levels that may pose a risk to the whale's health. Furthermore, the study suggested that inhalation may be an important exposure route. Exposure to chromium through inhalation is mainly because of particulate compounds. However, the toxicity of particulate chromium compounds in marine mammal cells is unknown. Accordingly, in this study, we tested the cytotoxic and genotoxic effects of particulate hexavalent chromium in primary cultured lung and skin fibroblasts from the endangered North Atlantic right whale. Cytotoxicity was measured by clonogenic survival assay, and genotoxicity was measured as production of chromosome aberrations. Particulate hexavalent chromium induced cytotoxicity and genotoxicity in a concentration-dependent manner in both right whale lung and skin fibroblasts. Lung fibroblasts were more resistant to chromium cytotoxicity, but presented with more chromosome damage than skin fibroblasts. These data further support the hypothesis that chromium may be a health concern for the endangered North Atlantic right whale.

The cytotoxicity and genotoxicity of hexavalent chromium in medaka (Oryzias latipes) cells

Chromium is an increasing health concern for aquatic environments, however, the mechanism of chromium toxicity in aquatic species is yet unknown. We used a medaka (Oryzias latipes) fin cell line to investigate the cytotoxicity and genotoxicity of sodium chromate, a soluble form of hexavalent chromium. We used a clonogenic cytotoxicity assay to measure sodium chromate cytotoxicity, gamma-H2A.X immunofluoresence to measure DNA double-strand breaks, and chromosome damage to measure clastogenicity. We found that sodium chromate is cytotoxic to medaka fin cells, with toxicity increasing in a concentration-dependent manner. Treatments of 0.5, 1, 5, 10, 25, 50 and 100 microM sodium chromate caused 100, 103.5, 87.8, 77.5, 40.9, 15 and 2.7% survival, respectively, relative to the control. We visualized DNA double-strand breaks in medaka cells through the formation of gamma-H2A.X foci. Breaks could be detected at concentrations as low as 1 microM. We also found that sodium chromate induces chromosomal aberrations, causing chromatid lesions and exchanges that increase with concentration. Treatments of 0, 1, 5, 10 and 25 microM sodium chromate damaged 10.3, 17, 32.3, 43 and 51.6% of metaphases and induced 13, 23, 44, 69 and 118 total aberrations in 100 metaphases, respectively. These data show that hexavalent chromium is both cytotoxic and genotoxic to fish cells. Our results set the context for future work in the medaka cell culture model and provide important tools for investigating mechanisms of toxicity in aquatic organisms.

Excising basal cell carcinomas: comparing the performance of general practitioners, hospital skin specialists and other hospital specialists

BACKGROUND

General practitioners (GPs) are not encouraged to excise basal cell carcinomas (BCCs). Despite this, as many of 10% of BCCs may be excised by GPs. GPs may be able to have a greater role in the diagnosis and management of BCC, but much needs to be learnt before this can be advocated.

OBJECTIVE

To compare the practice of GPs, skin specialists (dermatologists and plastic surgeons) and other hospital specialists in excising BCCs.

METHODS

A retrospective analysis of all BCCs excised in the Grampian region between 1 January and 31 December 2005 was carried out In total, 1087 reports were rated for source, quality of clinical information provided and extent of excision.

RESULTS

GPs perform significantly less well than skin specialists when diagnosing and excising BCCs, but appear equal in diagnostic skill and better at excision than other hospital specialists. Non-specialized GPs appear to perform as well as GPs with special interest (GPwSI) in adequately excising BCCs. In 18.7% of all cases, the information supplied to the pathologist with the biopsy sample was inadequate to draw a conclusion.

CONCLUSIONS

GPs compare unfavourably with skin specialists in diagnosing and excising BCCs. The performance of nonspecialized GPs does not appear to differ markedly from that of GPwSI. There is considerable room to optimize current GP performance, particularly with lesions of the head and neck, and it may be that novel approaches to GP training are required to achieve this. Structured request forms may improve the quality of clinical information provided when skin biopsies are submitted for pathological examination.

Similar asthma prevalence estimates obtained from preadolescent and parent survey responses

OBJECTIVE

We compared agreement between child and parent responses to questions assessing prevalence of asthma and other severe respiratory symptoms.

STUDY DESIGN AND SETTING

Fifth-grade children enrolled in public schools and their parents separately completed a health survey, which included respiratory symptom questions from the International Study of Asthma and Allergies in Childhood (ISAAC). Agreement on respiratory symptom questions was assessed with Cohen's Kappa coefficient. Asthma prevalence estimates based on responses to several questions were also compared using child and parent data. The analysis was based on a study sample size of 230 matched parent and child questionnaires.

RESULTS

High levels of agreement (Kappa: 0.76 and 0.79) between child and parent responses were observed for current and lifetime asthma, and similar asthma prevalence estimates were obtained from child and parent response data. Five of the questions on potentially severe respiratory symptoms had low to fair levels of agreement (Kappa: -0.01 to 0.38), resulting in statistically significantly different prevalence estimates in three of the five symptoms.

CONCLUSIONS

Separate parent and child responses to a series of respiratory symptom and asthma questions yielded similar estimates for asthma prevalence but different estimates for the prevalence of several severe respiratory symptoms.

Developmental delays and locomotor activity in the C57BL6/J mouse following neonatal exposure to the fully-brominated PBDE, decabromodiphenyl ether

After several decades of commercial use, the flame retardant chemicals polybrominated diphenyl ethers (PBDEs) and their metabolites have become pervasive environmental contaminants with a global distribution. PBDEs have entered the food chain and increasing levels can be detected in the human body. Decabrominated diphenyl ether (decaBDE) is currently the most widely used of the PBDEs in the United States. Despite its widespread use, little is known about the health effects of decaBDE. The current study examined the effects of neonatal exposure to decaBDE in the inbred C57BL6/J mouse. Neonatal male and female mice were exposed to a daily oral dose of 0, 6, or 20 mg/kg decaBDE from postnatal day 2 to 15. Three groups of endpoints were examined: the ontogeny of sensorimotor responses and serum thyroxine levels in immature animals, and locomotor activity in adult animals. In immature animals, 20 mg/kg/day produced developmental delays in the acquisition of the palpebral reflex. At this age, exposed males also showed a dose-related reduction of serum thyroxine levels. As adults, decaBDE exposure altered the normal sex- and age-specific characteristics of spontaneous locomotor activity. The most striking effect was an increase of activity during the first 1.5 h of the 2 h assessment in males exposed to 20 mg/kg/day decaBDE. These effects suggest that decaBDE is a developmental neurotoxicant that can produce long-term behavioral changes following a discrete period of neonatal exposure.

Homologous recombination repair protects against particulate chromate-induced chromosome instability in Chinese hamster cells

Particulate hexavalent chromium [Cr(VI)] compounds are well-established human carcinogens. Cr(VI)-induced tumors are characterized by chromosomal instability (CIN); however, the mechanisms of this effect are unknown. We investigated the hypothesis that homologous recombination (HR) repair of DNA double-strand breaks protect cells from Cr(VI)-induced CIN by focusing on the XRCC3 and RAD51C genes, which play an important role in cellular resistance to DNA double-strand breaks. We used Chinese hamster cells defective in each HR gene (irs3 for RAD51C and irs1SF for XRCC3) and compared with their wildtype parental and cDNA-complemented controls. We found that the intracellular Cr ion levels varied among the cell lines after particulate chromate treatment. Importantly, accounting for differences in Cr ion levels, we discovered that XRCC3 and RAD51C cells treated with lead chromate had increased cytotoxicity and chromosomal aberrations, relative to wildtype and cDNA-complimented cells. We also observed the emergence of high levels of chromatid exchanges in the two mutant cell lines. For example, 1microg/cm(2) lead chromate induced 20 and 32 exchanges in XRCC3- and RAD51C-deficient cells, respectively, whereas no exchanges were detected in the wildtype and cDNA-complemented cells. These observations suggest that HR protects cells from Cr(VI)-induced CIN, consistent with the ability of particulate Cr(VI) to induce double-strand breaks.

Chronic exposure to particulate chromate induces spindle assembly checkpoint bypass in human lung cells

One of the hallmarks of lung cancer is chromosome instability (CIN), particularly a tetraploid phenotype, which is normally prevented by the spindle assembly checkpoint. Hexavalent chromium Cr(VI) is an established human lung carcinogen, and Cr(VI) induces tumors at lung bifurcation sites where Cr(VI) particles impact and persist. However, the effects of Cr(VI) on the spindle assembly checkpoint are unknown and little is known about prolonged exposure to particulate Cr(VI). Accordingly, we investigated particulate Cr(VI)-induced bypass of the spindle assembly checkpoint after several days of exposure in WHTBF-6 cells. We found that lead chromate indeed induces spindle assembly checkpoint bypass in human lung cells, as 72, 96, and 120 h treatments with 0.5 or 1 microg/cm2 lead chromate induced significant increases in the percentage of cells with aberrant mitotic figures. For example, treatment with 1 microg/cm2 lead chromate for 96 h induced 11, 12.3, and 14% of cells with premature anaphase, centromere spreading and premature centromere division, respectively. In addition, we found a disruption of mitosis with more cells accumulating in anaphase; cells treated for 96 h increased from 18% in controls to 31% in cells treated with lead chromate. To confirm involvement of the spindle assembly checkpoint, Mad2 expression was used as a marker. Mad2 expression was decreased in cells exposed to chronic treatments of lead chromate, consistent with disruption of the checkpoint. We also found concentration- and time-dependent increases in tetraploid cells, which continued to grow and form colonies. When cells were treated with chronic lead alone there was no increase in aberrant mitotic cells or polyploidy; however, chronic exposure to a soluble Cr(VI) showed an increase in aberrant mitotic cells and polyploidy. These data suggest that lead chromate does induce CIN and may be one mechanism in the development of Cr(VI)-induced lung cancer.

Particulate depleted uranium is cytotoxic and clastogenic to human lung cells

Depleted uranium (DU) is commonly used in military armor and munitions, and thus, exposure of soldiers and non-combatants is potentially frequent and widespread. DU is considered a suspected human carcinogen, affecting the bronchial cells of the lung. However, few investigations have studied DU in human bronchial cells. Accordingly, we determined the cytotoxicity and clastogenicity of both particulate (water-insoluble) and soluble DU in human bronchial fibroblasts (WTHBF-6 cells). We used uranium trioxide (UO3) and uranyl acetate (UA) as prototypical particulate and soluble DU salts, respectively. After a 24 h exposure, both UO3 and UA induced concentration-dependent cytotoxicity in WTHBF-6 cells. Specifically, 0.1, 0.5, 1, and 5 microg/cm2 UO3 induced 99, 57, 32, and 1% relative survival, respectively. Similarly, 100, 200, 400, and 800 microM UA induced 98, 92, 70, and 56% relative survival, respectively. When treated with chronic exposure, up to 72 h, of either UO3 or UA, there was an increased degree of cytotoxicity. We assessed the clastogenicity of these compounds and found that at concentrations of 0, 0.5, 1, and 5 microg/cm2 UO3, 5, 6, 10, and 15% of metaphase cells exhibit some form of chromosome damage. UA did not induce chromosome damage above background levels. There were slight increases in chromosome damage induced when we extended the UO3 treatment time to 48 or 72 h, but no meaningful increase in chromosome damage was observed with chronic exposure to UA.

Role of the Fancg gene in protecting cells from particulate chromate-induced chromosome instability

Particulate hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Cr(VI)-induced tumors exhibit chromosome instability (CIN), but the mechanisms underlying these effects are unknown. We investigated a possible role for the Fanconi anemia (FA) pathway in particulate Cr(VI)-induced chromosomal damage by focusing on the Fancg gene, which plays an important role in cellular resistance to DNA interstrand crosslinks. We used the isogenic Chinese hamster ovary (CHO) KO40 fancg mutant compared with parental and gene-complemented cells. We found that fancg cells treated with lead chromate had lower intracellular Cr ion levels than control cell lines. Accounting for differences of Cr ion levels between cell lines, we discovered that fancg cells treated with lead chromate had increased cytotoxicity and chromosomal aberrations, which was not observed after restoring the Fancg gene. Chromosomal damage was manifest as increased total chromosome damage and percent metaphases with damage, specifically an increase in chromatid and isochromatid breaks. We conclude that Fancg protects cells from particulate Cr(VI)-induced cytotoxicity and chromosome damage, which is consistent with the known sensitivity of fancg cells to crosslinking damage and the ability of Cr(VI) to produce crosslinks.

XRCC1 protects cells from chromate-induced chromosome damage, but does not affect cytotoxicity

Hexavalent chromium Cr(VI) is a well known human carcinogen. This genotoxic metal induces DNA strand breaks and chromosome damage. However, the relationship between these lesions is uncertain. Our study focused on examining the role of XRCC1 in sodium chromate-induced cytotoxicity and chromosomal aberrations in Chinese Hamster Ovary (CHO) cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant) and H9T3 (EM9 complemented with human XRCC1 gene). Results show that concentration-dependent decreases in relative survival are similar in all three cell lines, indicating that XRCC1 is not crucial for protecting cells from sodium chromate-induced cytotoxicity. Similarly the frequency of damaged metaphase cells was not affected by XRCC1 deficiency. However, the total number of Cr(VI)-induced chromosome aberrations was exacerbated by XRCC1 deficiency and the spectrum of chromosome damage changed dramatically. Specifically, chromatid and isochromatid lesions were the most prominent aberrations induced in the cell lines and XRCC1 was essential to reduce the formation of chromatid lesions. In addition, XRCC1 deficiency caused a dramatic increase in the number of chromatid exchanges indicating that it is involved in protection from Cr(VI)-induced chromosome instability.

XRCC1 protects against particulate chromate-induced chromosome damage and cytotoxicity in Chinese hamster ovary cells

Water-insoluble hexavalent chromium compounds are well-established human lung carcinogens. Lead chromate, a model insoluble Cr(VI) compound, induces DNA damage, chromosome aberrations, and dose-dependent cell death in human and Chinese hamster ovary (CHO) cells. The relationship between lead chromate-induced DNA damage and chromosome aberrations is unknown. Our study focus was on examining the role of XRCC1 in lead chromate-induced cytotoxicity and structural chromosomal aberrations in CHO cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant), and H9T3 (EM9 complemented with human XRCC1 gene). Cytotoxicity was significantly higher in EM9 cells when compared to AA8 and H9T3 cells, indicating that XRCC1 is important for protecting cells from lead chromate particles-induced cell death. The frequency of damaged metaphase cells was not affected by XRCC1 deficiency. However, the total amount of Cr(VI)-induced chromosome damage was exacerbated by XRCC1 deficiency, and the spectrum of damage changed dramatically. Chromatid and isochromatid lesions were the most prominent aberrations induced in all cell lines. XRCC1 was essential to reduce the formation of chromatid lesions but not for isochromatid lesions. In addition, XRCC1 deficiency resulted in a dramatic increase in the number of chromatid exchanges, indicating that XRCC1 is involved in protection from lead chromate-induced chromosome instability.

Chronic Exposure to Lead Chromate Causes Centrosome Abnormalities and Aneuploidy in Human Lung Cells

Hexavalent chromium [Cr(VI)] compounds are established human lung carcinogens. The carcinogenicity of Cr(VI) is related to its solubility, with the most potent carcinogens being the insoluble particulate Cr(VI) compounds. However, it remains unknown why particulate Cr(VI) is more carcinogenic than soluble Cr(VI). One possible explanation is that particulates may provide more chronic exposures to chromate over time. We found that aneuploid cells increased in a concentration- and time-dependent manner after chronic exposure to lead chromate. Specifically, a 24-hour lead chromate exposure induced no aneugenic effect, whereas a 120-hour exposure to 0.5 and 1 microg/cm2 lead chromate induced 55% and 60% aneuploid metaphases, respectively. We also found that many of these aneuploid cells were able to continue to grow and form colonies. Centrosome defects are known to induce aneuploidy; therefore, we investigated the effects of chronic lead chromate exposure on centrosomes. We found that centrosome amplification in interphase and mitotic cells increased in a concentration- and time-dependent manner with 0.5 and 1 microg/cm2 lead chromate for 120 hours, inducing aberrant centrosomes in 18% and 21% of interphase cells and 32% and 69% of mitotic cells, respectively; however, lead oxide did not induce centrosome amplification in interphase or mitotic cells. There was also an increase in aberrant mitosis after chronic exposure to lead chromate with the emergence of disorganized anaphase and mitotic catastrophe. These data suggest that one possible mechanism for lead chromate-induced carcinogenesis is through centrosome dysfunction, leading to the induction of aneuploidy.

XRCC1 protects against particulate chromate-induced chromosome damage and cytotoxicity in Chinese hamster ovary cells

Water-insoluble hexavalent chromium compounds are well-established human lung carcinogens. Lead chromate, a model insoluble Cr(VI) compound, induces DNA damage, chromosome aberrations, and dose-dependent cell death in human and Chinese hamster ovary (CHO) cells. The relationship between lead chromate-induced DNA damage and chromosome aberrations is unknown. Our study focus was on examining the role of XRCC1 in lead chromate-induced cytotoxicity and structural chromosomal aberrations in CHO cells. Three different cell lines were used: AA8 (parental), EM9 (XRCC1 mutant), and H9T3 (EM9 complemented with human XRCC1 gene). Cytotoxicity was significantly higher in EM9 cells when compared to AA8 and H9T3 cells, indicating that XRCC1 is important for protecting cells from lead chromate particles-induced cell death. The frequency of damaged metaphase cells was not affected by XRCC1 deficiency. However, the total amount of Cr(VI)-induced chromosome damage was exacerbated by XRCC1 deficiency, and the spectrum of damage changed dramatically. Chromatid and isochromatid lesions were the most prominent aberrations induced in all cell lines. XRCC1 was essential to reduce the formation of chromatid lesions, but not for isochromatid lesions. In addition, XRCC1 deficiency resulted in a dramatic increase in the number of chromatid exchanges, indicating that XRCC1 is involved in protection from lead chromate-induced chromosome instability.

Microvessel density for melanoma prognosis

AIMS

Two-hundred and four accessible cases of malignant melanoma from the Grampian region of Scotland, collected over a period of 4 years, were studied for standard prognostic indicators for comparison with microvessel density.

METHODS AND RESULTS

The range of tumour thickness varied from in-situ melanoma to 14.8 mm. Microvessel density was assessed using the Chalkley technique on sections immunostained with CD31 antibody to identify endothelium. Vessel counts were performed in the peritumoral host tissue of all specimens. Strong correlation was observed between microvessel density at the tumour edge and tumour thickness (P < 0.001). Multifactorial regression analysis confirms Chalkley estimation as a reliable predictor of the risk of recurrence of melanoma (P < 0.005). The predictive value was found to be superior to the Breslow score, for tumours more than 2 mm thick.

CONCLUSIONS

Microvessel assessment of primary melanoma using the Chalkley score technique provides reliable prognostic information on the risk of recurrence of the tumour, particularly for melanomas deeper than 2 mm. It remains to be seen whether this methodology can predict response to novel anti-angiogenic therapies currently entering trials.

Lead ions do not cause human lung cells to escape chromate-induced cytotoxicity

Hexavalent chromium (Cr (VI)) compounds are established human lung carcinogens. Solubility plays a key role in Cr (VI) carcinogenicity, with the most potent carcinogens being water-insoluble or 'particulate'. Lead chromate is used as the prototypical particulate Cr (VI) compound since it is the most insoluble of these compounds. Previous work in our laboratory showed that lead chromate particles dissolve outside cells to produce chromium (Cr) and lead (Pb) ions and that the Cr ions were genotoxic. Pb has been hypothesized to play an epigenetic role in the carcinogenic activity of lead chromate, perhaps by allowing Cr-damaged cells to survive, however, this possibility has not been investigated. Accordingly, we determined the functional role of Pb and Cr ions in lead chromate-induced clonogenic survival. We found that vitamin C co-treatment eliminated Cr ion uptake, had only a slight effect on Pb ion levels, and eliminated lead chromate cytotoxicity. These data indicate that Cr ions caused the cytotoxicity. We found that lead chromate and soluble Cr (VI) induced similar amounts of cytotoxicity indicating that Pb does not play an epigenetic role and cause Cr-damaged cells to survive.

Chromium is the proximate clastogenic species for lead chromate-induced clastogenicity in human bronchial cells

Hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen with potentially widespread exposure. Solubility is a key factor in the carcinogenicity of Cr(VI), with the water-insoluble or 'particulate' compounds being the more potent carcinogens. Studies have indicated that the component ions are responsible for their clastogenicity, but it is uncertain whether chromium (Cr), lead (Pb) or some combination of the two is responsible for the clastogenic effects. Accordingly, we compared the clastogenicity of lead chromate (LC) with soluble sodium chromate (SC) and lead glutamate (LG) in WTHBF-6 human lung cells. We found that 1436microM was the maximal intracellular level of Pb after exposure to clastogenic concentrations of LC. However, clastogenesis was not observed after exposure to LG, even when intracellular Pb concentrations reached 13,347microM, indicating that intracellular Pb levels did not reach clastogenic levels in WTHBF-6 cells after LC treatment. By contrast, SC was clastogenic damaging 16 and 44% of metaphase cells at intracellular Cr doses of 312 and 1262microM respectively, which was comparable to the clastogenesis observed after LC treatment. LC damaged 10, 27 and 37% of metaphases at intracellular Cr doses of 288, 926 and 1644microM, respectively. These data indicate that with respect to LC-induced clastogenicity, Cr and not Pb is the proximate clastogenic species in human lung cells.

Thrombosis and Neointima Formation in Vein Grafts Are Inhibited by Locally Applied Aspirin Through Endothelial Protection

Vein graft failure within the first month after bypass surgery is largely because of thrombosis. However, systemic study of thrombus formation in vein grafts is still lacking, and few effective techniques are available to prevent this event. Herein, we analyzed the kinetics of thrombosis and tested the effectiveness of locally applied aspirin on prevention of the disease in a mouse model. En face analysis of vein grafts revealed that 67±12% and 54±17% of the surface areas were covered by microthrombi at 1 and 3 days, respectively. Thrombus generation was also identified by labeling of platelets and fibrin, which occurred in 35 grafts examined at 1 and 3 days and 1, 2, 4, and 8 weeks. In a fifth of grafts, the thrombus occluded the vessel lumen by ≥1/4. Furthermore, a significant loss of endothelial cells was evidenced by β-gal staining for vein grafts in transgenic mice expressing LacZ gene controlled by TIE2-endothelial specific gene promoter. Following thrombosis, neointimal lesions were significantly increased by 4-fold 2 weeks after the operation. When vein grafts were treated locally with aspirin in pluronic gel-127, the thrombus area was significantly reduced ( P <0.005) at 1, 4, and 8 weeks. Interestingly, neointimal lesions were markedly reduced in the local, but not oral, aspirin-treated group at 4 and 8 weeks by 50% to 70% ( P <0.005). The mechanism of reduced lesions by locally applied aspirin involved the protection of vein graft endothelium. Thus, we provide strong evidence that thrombus formation occurs before the development of neointimal lesions in vein grafts and that local aspirin treatment successfully reduces vein graft arteriosclerosis through endothelial protection, resulting in reduction of thrombosis.

Study design: evaluating gene-environment interactions in the etiology of breast cancer - the WECARE study

INTRODUCTION

Deficiencies in cellular responses to DNA damage can predispose to cancer. Ionizing radiation can cause cluster damage and double-strand breaks (DSBs) that pose problems for cellular repair processes. Three genes (ATM, BRCA1, and BRCA2) encode products that are essential for the normal cellular response to DSBs, but predispose to breast cancer when mutated.

DESIGN

To examine the joint roles of radiation exposure and genetic susceptibility in the etiology of breast cancer, we designed a case-control study nested within five population-based cancer registries. We hypothesized that a woman carrying a mutant allele in one of these genes is more susceptible to radiation-induced breast cancer than is a non-carrier. In our study, 700 women with asynchronous bilateral breast cancer were individually matched to 1400 controls with unilateral breast cancer on date and age at diagnosis of the first breast cancer, race, and registry region, and counter-matched on radiation therapy. Each triplet comprised two women who received radiation therapy and one woman who did not. Radiation absorbed dose to the contralateral breast after initial treatment was estimated with a comprehensive dose reconstruction approach that included experimental measurements in anthropomorphic and water phantoms applying patient treatment parameters. Blood samples were collected from all participants for genetic analyses.

CONCLUSIONS

Our study design improves the potential for detecting gene-environment interactions for diseases when both gene mutations and the environmental exposures of interest are rare in the general population. This is particularly applicable to the study of bilateral breast cancer because both radiation dose and genetic susceptibility have important etiologic roles, possibly by interactive mechanisms. By using counter-matching, we optimized the informativeness of the collected dosimetry data by increasing the variability of radiation dose within the case-control sets and enhanced our ability to detect radiation-genotype interactions.

ATM variants 7271T>G and IVS10-6T>G among women with unilateral and bilateral breast cancer

Recent reports suggest that two ATM gene mutations, 7271T>G and IVS10-6T>G, are associated with a high risk of breast cancer among multiple-case families. To assess the importance of these two mutations in another ‘high-risk’ group, young women (under age 51) with multiple primaries, we screened a large population-based series of young women with bilateral breast cancer and compared the frequency of these mutations among similar women diagnosed with unilateral breast cancer. The 1149 women included were enrolled in an ongoing population-based case–control study of the genetic factors that contribute to bilateral breast cancer; they were not selected on the basis of family history of cancer. Screening for 7271T>G and IVS10-6T>G ATM gene mutations was conducted using DHPLC followed by direct sequencing. The 7271T>G mutation was detected in one out of 638 (0.2%) women with unilateral breast cancer and in none of the bilateral cases, and the IVS10-6T>G mutation in one out of 511 (0.2%) bilateral and in eight out of 638 (1.3%) unilateral breast cancer cases. Carriers of either mutation were not limited to women with a family history. Given the likelihood that young women with bilateral breast cancer have a genetic predisposition, the observed mutation distribution is contrary to that expected if these two mutations were to play an important role in breast carcinogenesis among individuals at high risk.

The Descriptive Epidemiology of Second Primary Breast Cancer

BACKGROUND

It is well established that the incidence rates of first primary breast cancer have been increasing over time. In contrast, the incidence rates of second primary breast cancer are largely undocumented. This study describes the epidemiology of second primary breast cancer among a population-based cohort of 305,533 U.S. women diagnosed with breast cancer between 1973 and 1998.

METHODS

We compared age-specific incidence rates for overall and second primary breast cancer according to year of diagnosis and demographic and tumor characteristics.

RESULTS

Overall, age-specific rates of breast cancer increased with increasing age and year of diagnosis, whereas incidence of second primary breast cancer peaked among young women and declined after 1988. Consistent with what is known about genetic susceptibility to breast cancer, at every age the rate of second primaries was greater than the overall rate; among women age 20 to 29 years the rate of second primary was more than 100 times greater. Although overall age-specific rates of breast cancer for African-American women were lower than for whites, rates of second primaries were higher. Women with a first primary that was either lobular or medullary had a greater likelihood of developing a second primary, although, there were relatively few with these histologic types.

CONCLUSIONS

The pattern of incidence rates for first and second primary breast cancer differ markedly over time and by age.

Infection of chick chorioallantoic membrane (CAM) as a model for invasive hyphal growth and pathogenesis of Candida albicans

We report the development of a simple model for assessing the ability of the fungal pathogen Candida albicans to invade the chorioallantoic membrane (CAM) of fertilized hens' eggs. Wild-type and mutant strains of C. albicans were inoculated onto CAM surfaces either as a liquid suspension or on a sterile filter disc. Invasion of the membrane led to death of the embryo due to damage of the CAM, which could be examined histologically to show cell distribution and morphology, and by RT-PCR for assessment of patterns of fungal gene expression in vivo. Prophylactic or co-administration of fluconazole with the inoculum protected the embryo from infection. Secretory aspartyl protease (Sap) mutant strains with reported attenuation of virulence were virulent in the CAM model. However, a C. albicans strain with mutations in two transcription factors Efg1 and Cph1 was unable to form hyphae on the CAM or to penetrate it. The chick CAM, therefore, represents an experimentally tractable and inexpensive alternative to rodent or tissue culture-based invasion models, and can be used to investigate fungal pathogenesis and the genetic regulation of infection and membrane penetration of C. albicans.

Designing and implementing quality control for multi-center screening of mutations in the ATM gene among women with breast cancer

Epidemiologic studies of breast and other cancers are increasingly turning toward large, multi-center designs in order to obtain adequate power to detect low-penetrance susceptibility alleles. The size of such studies often makes it necessary to distribute the genetic screening efforts to multiple sites. Careful standardization of screening methodology and quality control across sites is required for such multi-center screening designs to be efficient. In this report, we illustrate our approach to these challenges in the context of the WECARE (Women's Environment, Cancer and Radiation Epidemiology) Study, a multi-center population-based genetic epidemiologic study of women with unilateral and bilateral breast cancer. We provide optimized conditions for screening the ataxia-telangiectasia gene (ATM) for variation by denaturing high-performance liquid chromatography (DHPLC) and describe the results of two independent quality control studies at four international centers employing these conditions. Finally, we report novel mutations in the ATM gene identified both in patients with ataxia-telangiectasia and in patients with unilateral or bilateral breast cancer.

Does screen-detected breast cancer have better survival than symptomatic breast cancer?

OBJECTIVES

Evidence obtained from several randomized control trials suggest that mortality from breast cancer could be reduced by mammographic screening. However, a recent meta-analysis questioned the general acceptance that screening for breast cancer is beneficial. The purpose of the study was to analyze prospectively collected data from our unit and produce overall and comparative 5-year survival rates for screen-detected and symptomatic breast cancer.

METHODS

Prospectively collected data on all patients diagnosed with invasive breast cancer between January 1993 and December 1994 (24 months), and monitored until the end of 1999, were collated and analyzed. Five-year survival was estimated and broken down by age at diagnosis, tumour size, grade and nodal status. The overall 5-year survival for women with screen-detected cancers was compared with that for women with symptomatically presenting cancers.

RESULTS

Between January 1993 and December 1994, 308 patients with invasive breast cancer were referred to the unit (162 via the breast screening programme and 146 presenting symptomatically). The overall 5-year survival was 85.5% (confidence interval [CI], 80.8-89.1). Small tumour size, low grade and negative nodal status were associated with higher survival rates. Five-year survival of the screen-detected cancer patients (91.7%; CI, 85.8-95.2) was higher than that of patients presenting symptomatically (78.6%; CI, 70.6-84.6; p < 0.001).

CONCLUSIONS

These findings suggest that patients with screen-detected breast cancer may have better survival compared to those with symptomatically detected breast cancer. The results support the argument in favour of a beneficial impact of breast screening programmes on patients' survival.