Role of research in public health

Environmental health research is at a promising stage for more precisely identifying gene-environment components of disease. Simplistic models and reductionist approaches that have been the norm both in toxicology and in clinical medicine are beginning to be replaced with a more holistic or systems biology approach. We are slowly moving to an understanding that the time between an exposure and its consequence as a diagnosed disease is a time during which many different biochemical changes are occurring and a time during which many biomarkers of disease progression could be identified and used. With such information in hand, clinicians would be able to intervene early in disease progression. With such information, environmental health researchers and policy makers could more reliably identify which elements in our environment need to be controlled or reduced and which populations need the most protection. With such information, the incidence of many human diseases could be dramatically reduced.

Evaluating DNA methylation age on the Illumina MethylationEPIC Bead Chip

DNA methylation age (DNAm age) has become a widely utilized epigenetic biomarker for the aging process. The Horvath method for determining DNAm age is perhaps the most widely utilized and validated DNA methylation age assessment measure. Horvath DNAm age is calculated based on methylation measurements at 353 loci, present on Illumina's 450k and 27k DNA methylation microarrays. With increasing use of the more recently developed Illumina MethylationEPIC (850k) microarray, it is worth revisiting this aging measure to evaluate estimation differences due to array design. Of the requisite 353 loci, 17 are missing from the 850k microarray. Similarly, an alternate, 71 loci DNA methylation age assessment measure created by Hannum et al. is missing 6 requisite loci. Using 17 datasets with 27k, 450k, and/or 850k methylation data, we compared each sample's epigenetic age estimated from all 353 loci required by the Horvath DNAm age calculator, and using only the 336 loci available on the 850k array. In 450k/27k data, removing loci not on the 850k array resulted in underestimation of Horvath's DNAm age. Underestimation of Horvath DNAm age increased from ages 0 to ~20, remaining stable thereafter (mean deviation = -3.46 y, SD = 1.13 for individuals ≥20 years). Underestimation of Horvath's DNAm age by the reduced 450k/27k data was similar to the underestimation observed in the 850k data indicating it is driven by missing probes. In analogous examination of Hannum's DNAm age, the magnitude and direction of epigenetic age misestimation varied with chronological age. In conclusion, inter-array deviations in DNAm age estimations may be largely driven by missing probes between arrays, despite default probe imputation procedures. Though correlations and associations based on Horvath's DNAm age may be unaffected, researchers should exercise caution when interpreting results based on absolute differences in DNAm age or when mixing samples assayed on different arrays.

A novel approach for measuring residential socioeconomic factors associated with cardiovascular and metabolic health

Individual-level characteristics, including socioeconomic status, have been associated with poor metabolic and cardiovascular health; however, residential area-level characteristics may also independently contribute to health status. In the current study, we used hierarchical clustering to aggregate 444 US Census block groups in Durham, Orange, and Wake Counties, NC, USA into six homogeneous clusters of similar characteristics based on 12 demographic factors. We assigned 2254 cardiac catheterization patients to these clusters based on residence at first catheterization. After controlling for individual age, sex, smoking status, and race, there were elevated odds of patients being obese (odds ratio (OR)=1.92, 95% confidence intervals (CI)=1.39, 2.67), and having diabetes (OR=2.19, 95% CI=1.57, 3.04), congestive heart failure (OR=1.99, 95% CI=1.39, 2.83), and hypertension (OR=2.05, 95% CI=1.38, 3.11) in a cluster that was urban, impoverished, and unemployed, compared with a cluster that was urban with a low percentage of people that were impoverished or unemployed. Our findings demonstrate the feasibility of applying hierarchical clustering to an assessment of area-level characteristics and that living in impoverished, urban residential clusters may have an adverse impact on health.

Epigenome: A Biomarker or Screening Tool to Evaluate Health Impact of Cumulative Exposure to Chemical and Non-Chemical Stressors

Current risk assessment practices and toxicity information are hard to utilize for assessing the health impact of combined or cumulative exposure to multiple chemical and non-chemical stressors encountered in the “real world” environment. Non-chemical stressors such as heat, radiation, noise, humidity, bacterial and viral agents, and social factors, like stress related to violence and socioeconomic position generally cannot be currently incorporated into the risk assessment paradigm. The Science and Decisions report released by the National Research Council (NRC) in 2009 emphasized the need to characterize the effects of multiple stressors, both chemical and non-chemical exposures. One impediment to developing information relating such non-chemical stressors to health effects and incorporating them into cumulative assessment has been the lack of analytical tools to easily and quantitatively monitor the cumulative exposure to combined effects of stressors over the life course.

The Role of the Epigenome in Translating Neighborhood Disadvantage Into Health Disparities

The possible causal role of the environment in health disparities is not well understood, even though it has been a national priority for many years. Progress to investigate the relationship between genetics, environmental exposures, and health outcomes has been hampered by the lack of analytical tools to quantify the combined or cumulative effect of multiple chemical and non-chemical stressors on gene expression. The studies cited here provide a strong rationale for using epigenomic analysis to assess cumulative risk from multiple environmental exposures over the life course. The environment-specific "imprints" on the genome, coupled with transcriptomics and metabolomics, can be used to advance our understanding of the relationship between neighborhood disadvantage and health disparities.

Epigenome: biosensor of cumulative exposure to chemical and nonchemical stressors related to environmental justice

Understanding differential disease susceptibility requires new tools to quantify the cumulative effects of environmental stress. Evidence suggests that social, physical, and chemical stressors can influence disease through the accumulation of epigenetic modifications. Geographically stable epigenetic alterations could identify plausible mechanisms for health disparities among the disadvantaged and poor. Relations between neighborhood-specific epigenetic markers and disease would identify the most appropriate targets for medical and environmental intervention. Complex interactions among genes, the environment, and disease require the examination of how epigenetic changes regulate susceptibility to environmental stressors. Progress in understanding disparities in disease susceptibility may depend on assessing the cumulative effect of environmental stressors on genetic substrates. We highlight key concepts regarding the interface between environmental stress, epigenetics, and chronic disease.

Laboratory to community: chemoprevention is the answer

In the current issue, Johnson and colleagues present exciting results, using biomarkers involved in aflatoxin B1 (AFB1)-induced hepatocarcinogenesis, as an example of a conceptual framework to target mechanisms of action in developing chemopreventive agents. Their innovative approach offers considerable promise for a field that has long been neglected. Proof-of-principle was demonstrated using a synthetic triterpenoid (CDDO-Im), which activates Nrf2 signal transduction pathway, inhibits formation of AFB1-induced DNA adducts and neoplastic hepatic foci, and alters the expression of genes associated with aflatoxin-mediated toxicity.

p38 mitogen-activated protein kinase interacts with vinculin at focal adhesions during fatty acid-stimulated cell adhesion

Arachidonic acid stimulates cell adhesion by activating α2β1 integrins in a process that depends on protein kinases, including p38 mitogen activated protein kinase. Here, we describe the interaction of cytoskeletal components with key signaling molecules that contribute to the spreading of, and morphological changes in, arachidonic acid-treated MDA-MB-435 human breast carcinoma cells. Arachidonic acid-treated cells showed increased attachment and spreading on collagen type IV, as measured by electric cell-substrate impedance sensing. Fatty acid-treated cells displayed short cortical actin filaments associated with an increased number of β1 integrin-containing pseudopodia, whereas untreated cells displayed elongated stress fibers and fewer clusters of β1 integrins. Confocal microscopy of arachidonic acid-treated cells showed that vinculin and phospho-p38 both appeared enriched in pseudopodia and at the tips of actin filaments, and fluorescence ratio imaging indicated the increase was specific for the phospho-(active) form of p38. Immunoprecipitates of phospho-p38 from extracts of arachidonic acid-treated cells contained vinculin, and GST-vinculin fusion proteins carrying the central region of vinculin bound phospho-p38, whereas fusion proteins expressing the terminal portions of vinculin did not. These data suggest that phospho-p38 associates with particular domains on critical focal adhesion proteins that are involved in tumor cell adhesion and spreading, and that this association can be regulated by factors in the tumor microenvironment.

Inhibition of transforming growth factor-β-activated kinase-1 blocks cancer cell adhesion, invasion, and metastasis

BACKGROUND

Tumour cell metastasis involves cell adhesion and invasion, processes that depend on signal transduction, which can be influenced by the tumour microenvironment. N-6 polyunsaturated fatty acids, found both in the diet and in response to inflammatory responses, are important components of this microenvironment.

METHODS

We used short hairpin RNA (shRNA) knockdown of TGF-β-activated kinase-1 (TAK1) in human tumour cells to examine its involvement in fatty acid-stimulated cell adhesion and invasion in vitro. An in vivo model of metastasis was developed in which cells, stably expressing firefly luciferase and either a control shRNA or a TAK1-specific shRNA, were injected into the mammary fat pads of mice fed diets, rich in n-6 polyunsaturated fatty acids. Tumour growth and spontaneous metastasis were monitored with in vivo and in situ imaging of bioluminescence.

RESULTS

Arachidonic acid activated TAK1 and downstream kinases in MDA-MB-435 breast cancer cells and led to increased adhesion and invasion. Knockdown of TAK1 blocked this activation and inhibited both cell adhesion and invasion in vitro. Tumour growth at the site of injection was not affected by TAK1 knockdown, but both the incidence and extent of metastasis to the lung were significantly reduced in mice injected with TAK1 knockdown cells compared with mice carrying control tumour cells.

CONCLUSION

These data demonstrate the importance of TAK1 signalling in tumour metastasis in vivo and suggest an opportunity for antimetastatic therapies.

Plasminogen activator inhibitor 1 RNAi suppresses gastric cancer metastasis in vivo

Cancer metastasis remains the primary cause of pain, suffering, and death in cancer patients, and even the most current therapeutic strategies have not been highly successful in preventing or inhibiting metastasis. In most patients with scirrhous gastric cancer (one of the most aggressive of diffuse-type gastric cancer), recurrence occurs even after potentially curative resection, most frequently in the form of peritoneal metastasis. Given that the occurrence of diffuse-type gastric cancers has been increasing, the development of new strategies to combat metastasis of this disease is critically important. Plasminogen activator inhibitor-1 (PAI-1) is a critical factor in cancer progression; thus, PAI-1 RNAi may be an effective therapy against cancer metastasis. In the present study, we used an RNAi technique to reduce PAI-1 expression in an in vivo model system for gastric cancer metastasis. Ex vivo plasmid transfection and adenovirus infection were tested as mechanisms to incorporate specific PAI-1 RNAi vectors into human gastric carcinoma cells. Both approaches significantly decreased peritoneal tumor growth and the formation of bloody ascites in the mouse model, suggesting that this approach may provide a new, effective strategy for inhibiting cancer metastasis.

Discovering how environmental exposures alter genes could lead to new treatments for chronic illnesses

Emerging research demonstrates that diet, pollution, and other environmental triggers can alter both the function and expression of human genes and lead to a heightened disease risk. These environment-gene interactions can cause so-called epigenetic changes in gene expression-patterns of which genes are switched "on" or "off"-that may account for the rising mortality from chronic diseases in industrialized nations. In this paper, we call for a new transdisciplinary approach to public health that would examine how environmental exposures, both physical and social, influence gene expression and a person's susceptibility to chronic disease. This initiative could lead to new ways to prevent and treat such illnesses.

Neighborhood-specific epigenome analysis: the pathway forward to understanding gene-environment interactions

Morbidity and mortality associated with complex diseases are expected to increase as the population ages and the number of Americans living in poverty continues to expand. Therefore, improved translation of research findings into clinical practice and public health policy must become a priority. This commentary emphasizes the need for a new research model that accommodates the complex nature of disease etiology.

Arachidonic acid stimulates formation of a novel complex containing nucleolin and RhoA

Arachidonic acid (AA) stimulates cell adhesion through a p38 mitogen activated protein kinase-mediated RhoA signaling pathway. Here we report that a proteomic screen following AA-treatment identified nucleolin, a multifunctional nucleolar protein, in a complex with the GTPase, RhoA, that also included the Rho kinase, ROCK. AA-stimulated cell adhesion was inhibited by expression of nucleolin-targeted shRNA and formation of the multiprotein complex was blocked by expression of dominant-negative RhoA. AA-treatment also induced ROCK-dependent serine phosphorylation of nucleolin and translocation of nucleolin from the nucleus to the cytoplasm, where it appeared to co-localize with RhoA. These data suggest the existence of a new signaling pathway through which the location and post-translational state of nucleolin are modulated.

Lysine 63-linked ubiquitination is important for arachidonic acid-induced cellular adhesion and migration

Arachidonic acid, a dietary cis-polyunsaturated fatty acid, stimulates adhesion and migration of human cancer cells on the extracellular matrix by activation of intracellular signaling pathways. Polyubiquitin chains bearing linkages through different lysine residues convey distinct structural and functional information that is important for signal transduction. We investigated whether ubiquitination was required for arachidonic acid-induced cellular adhesion and migration of MDA-MB-435 cells on collagen type IV. An E1 (ubiquitin-activating enzyme) inhibitor, PYR-431, completely abrogated arachidonic acid-stimulated adhesion. Additionally, expression of a lysine null mutant ubiquitin prevented activation of cellular adhesion. Cells expressing ubiquitin in which lysine 63 (K63) was mutated to arginine (K63R) were unable to adhere to collagen upon exposure to arachidonic acid. When K63 was the only lysine present, the cells retained the ability to adhere, indicating that K63-linked ubiquitin is both necessary and sufficient. Moreover, K63-linked ubiquitin was required for the induction of cell migration by arachidonic acid. The ubiquitin mutants and PYR-431 did not prevent arachidonic acid-induced phosphorylation of TGF-β activated kinase-1 (TAK1) and p38 MAPK, suggesting K63-linked ubiquitination occurs downstream of MAPK. These novel findings are the first to demonstrate a role for K63-linked ubiquitination in promoting cell adhesion and migration.

Elevated dietary linoleic acid increases gastric carcinoma cell invasion and metastasis in mice

BACKGROUND

Dietary (n-6)-polyunsaturated fatty acids influence cancer development, but the mechanisms have not been well characterised in gastric carcinoma.

METHODS

We used two in vivo models to investigate the effects of these common dietary components on tumour metastasis. In a model of experimental metastasis, immunocompromised mice were fed diets containing linoleic acid (LA) at 2% (LLA), 8% (HLA) or 12% (VHLA) by weight and inoculated intraperitoneally (i.p.) with human gastric carcinoma cells (OCUM-2MD3). To model spontaneous metastasis, OCUM-2MD3 tumours were grafted onto the stomach walls of mice fed with the different diets. In in vitro assays, we investigated invasion and ERK phosphorylation of OCUM-2MD3 cells in the presence or absence of LA. Finally, we tested whether a cyclooxygenase (COX) inhibitor, indomethacin, could block peritoneal metastasis in vivo.

RESULTS

Both the HLA and VHLA groups showed increased incidence of tumour nodules (LA: 53%; HLA: 89%; VHLA: 100%; P<0.03); the VHLA group also displayed increased numbers of tumour nodules and higher total volume relative to LLA group in experimental metastasis model. Both liver invasion (78%) and metastasis to the peritoneal cavity (67%) were more frequent in VHLA group compared with the LLA group (22% and 11%, respectively; P<0.03) in spontaneous metastasis model. We also found that the invasive ability of these cells is greatly enhanced when exposed to LA in vitro. Linoleic acid also increased invasion of other scirrhous gastric carcinoma cells, OCUM-12, NUGC3 and MKN-45. Linoleic acid effect on OCUM-2MD3 cells seems to be dependent on phosphorylation of ERK. The data suggest that invasion and phosphorylation of ERK were dependent on COX. Indomethacin decreased the number of tumours and total tumour volume in both LLA and VHLA groups. Finally, COX-1, which is known to be an important enzyme in the generation of bioactive metabolites from dietary fatty acids, appears to be responsible for the increased metastatic behaviour of OCUM-2MD3 cells in the mouse model.

CONCLUSION

Dietary LA stimulates invasion and peritoneal metastasis of gastric carcinoma cells through COX-catalysed metabolism and activation of ERK, steps that compose pathway potentially amenable to therapeutic intervention.

Finding synergy: reducing disparities in health by modifying multiple determinants

Although researchers acknowledge that health disparities have multiple determinants, most recommendations for reducing inequities focus on a single approach. We suggest integrating 2 approaches for reducing disparities: improving access to primary care and updating and more vigorously enforcing consumer and environmental protection laws. This strategy could reduce the main causes of disparities, such as chronic diseases and injuries; win public and policymaker support; and provide a cost-effective start for achieving equity. Most of the scientific knowledge needed to implement this strategy exists, thus years of additional research would not be needed. Developing targeted regulatory and health care policies to reduce deaths from chronic diseases and injuries would be a major step forward in eliminating health disparities in the United States.

To reduce urban disparities in health, strengthen and enforce equitably environmental and consumer laws

While observers agree that reducing disparities in health is an important health priority for the USA, there is little agreement and no comprehensive plan to achieve this goal. In this commentary, we make the case for reducing the disproportionate exposure to environmental and consumer hazards as a promising strategy for reducing health disparities. Exposures to environmental risks such as air pollution, lead, and hazardous wastes and to consumer products such as tobacco, alcohol, and unhealthy food have been identified as significant threats to health and important contributors to disparities in health. Strengthening the regulations that prevent exposure to these harmful substances and enforcing these rules equitably could bring benefits to the population as a whole and especially to the disenfranchised, primarily urban, populations that are most exposed. The current policy environment may present a window of opportunity for pursuing this strategy.

Arachidonic acid stimulates cell adhesion through a novel p38 MAPK-RhoA signaling pathway that involves heat shock protein 27

Rho GTPases are critical components of cellular signal transduction pathways. Both hyperactivity and overexpression of these proteins have been observed in human cancers and have been implicated as important factors in metastasis. We previously showed that dietary n-6 fatty acids increase cancer cell adhesion to extracellular matrix proteins, such as type IV collagen. Here we report that in MDA-MB-435 human melanoma cells, arachidonic acid activates RhoA, and inhibition of RhoA signaling with either C3 exoenzyme or dominant negative Rho blocked arachidonic acid-induced cell adhesion. Inhibition of the Rho kinase (ROCK) with either small molecule inhibitors or ROCK II-specific small interfering RNA (siRNA) blocked the fatty acid-induced adhesion. However, unlike other systems, inhibition of ROCK did not block the activation of p38 mitogen-activated protein kinase (MAPK); instead, Rho activation depended on p38 MAPK activity and the presence of heat shock protein 27 (HSP27), which is phosphorylated downstream of p38 after arachidonic acid treatment. HSP27 associated with p115RhoGEF in fatty acid-treated cells, and this association was blocked when p38 was inhibited. Furthermore, siRNA knockdown of HSP27 blocked the fatty acid-stimulated Rho activity. Expression of dominant negative p115-RhoGEF or p115RhoGEF-specific siRNA inhibited both RhoA activation and adhesion on type IV collagen, whereas a constitutively active p115RhoGEF restored the arachidonic acid stimulation in cells in which the p38 MAPK had been inhibited. These data suggest that n-6 dietary fatty acids stimulate a set of interactions that regulates cell adhesion through RhoA and ROCK II via a p38 MAPK-dependent association of HSP27 and p115RhoGEF.

15-lipoxygenase-1 activates tumor suppressor p53 independent of enzymatic activity

15-LOX-1 and its metabolites are involved in colorectal cancer. Recently, we reported that 15-LOX-1 overexpression in HCT-116 human colorectal cancer cells inhibited cell growth by induction of p53 phosphorylation (4). To determine whether the 15-LOX-1 protein or its metabolites are responsible for phosphorylation of p53 in HCT-116 cells, we used HCT-116 cells that expressed a mutant 15-LOX-1. The mutant 15-LOX-1 enzyme, with a substitution of Leu at residue His361, was devoid of enzymatic activity. HCT-116 cells transiently transfected with either native or mutant 15-LOX-1 showed an increase in p53 phosphorylation and an increase in the expression of downstream genes. Thus, 15-LOX-1 induces p53 phosphorylation independent of enzymatic activity. Treatment of A549 human lung carcinoma cells with IL-4 increased the expression of 15-LOX-1 and also increased the expression of downstream targets of p53. This confirmed that the activation of p53 was also observed in wild-type cells expressing physiological 15-LOX-1. Immunoprecipitation experiments revealed that 15-LOX-1 interacts with, and binds to, DNA-dependent protein kinase (DNA-PK). The binding of 15-LOX-1 to DNA-PK caused an approximate 3.0-fold enhancement in kinase activity, resulting in increased p53 phosphorylation at Ser15. Knockdown of DNA-PK by small interfering RNA (siRNA) significantly reduced p53 phosphorylation. Furthermore, confocal microscopy demonstrated a colocalization of 15-LOX and DNA-PK in the cells. We propose that the 15-LOX-1 protein binds to DNA-PK, increasing its kinase activity and results in downstream activation of the tumor suppressor p53, thus revealing a new mechanism by which lipoxygenases (LOX) may influence the phenotype of tumor cells.

Community-based participatory research: a vehicle to promote public engagement for environmental health in China

BACKGROUND

In the past 25 years, China has experienced remarkable economic growth and rapid agricultural-to-industrial and rural-to-urban transitions. As a consequence, China now faces many daunting environmental challenges that are significantly affecting human health and quality of life, including indoor and outdoor air pollution, water pollution, deforestation, loss of agricultural land, and sustainability. Chinese government leaders have recently emphasized the need for better environmental protection practices along with interventions involving strong public participation.

OBJECTIVES

Community-based participatory research (CBPR) is a collaborative approach to research that involves community members, organizational representatives, and researchers as equal participants in all phases of the research process. Over the past 15 years, CBPR has gained recognition and acceptance and is now valued as a means to effect change and provide scientific knowledge relevant to human health and the environment. In this article we highlight the success of CBPR in the United States and suggest that it could be a useful model for addressing environmental health problems in the People's Republic of China.

DISCUSSION

CBPR can reduce the tension between science and society by promoting genuine communication, by enabling scientists and administrators to listen and respond to the public, by allowing communities to help shape the research agenda, and by increasing accountability of researchers and governments to the public.

CONCLUSIONS

CBPR can potentially help improve environmental health in China, but it is likely to take a different form than it has in the West because the government will be leading the way.

Gene-environment interactions in the development of complex disease phenotypes

The lack of knowledge about the earliest events in disease development is due to the multi-factorial nature of disease risk. This information gap is the consequence of the lack of appreciation for the fact that most diseases arise from the complex interactions between genes and the environment as a function of the age or stage of development of the individual. Whether an environmental exposure causes illness or not is dependent on the efficiency of the so-called “environmental response machinery” (i.e., the complex of metabolic pathways that can modulate response to environmental perturbations) that one has inherited. Thus, elucidating the causes of most chronic diseases will require an understanding of both the genetic and environmental contribution to their etiology. Unfortunately, the exploration of the relationship between genes and the environment has been hampered in the past by the limited knowledge of the human genome, and by the inclination of scientists to study disease development using experimental models that consider exposure to a single environmental agent. Rarely in the past were interactions between multiple genes or between genes and environmental agents considered in studies of human disease etiology. The most critical issue is how to relate exposure-disease association studies to pathways and mechanisms. To understand how genes and environmental factors interact to perturb biological pathways to cause injury or disease, scientists will need tools with the capacity to monitor the global expression of thousands of genes, proteins and metabolites simultaneously. The generation of such data in multiple species can be used to identify conserved and functionally significant genes and pathways involved in gene-environment interactions. Ultimately, it is this knowledge that will be used to guide agencies such as the U.S. Department of Health and Human Services in decisions regarding biomedical research funding and policy.

The prevalence of metabolic syndrome among US women of childbearing age

OBJECTIVES

We sought to determine whether the prevalence of metabolic syndrome among US women of childbearing age (18-44 years) has increased since 1988 and to estimate its current prevalence by race/ethnicity and risk that a maternal history of select metabolic syndrome characteristics imposes on offspring.

METHODS

We used survey-specific data analysis methods to examine data from the National Health and Nutrition Examination Surveys conducted from 1988 to 2004.

RESULTS

The prevalence of the metabolic syndrome phenotype and 2 of its clinical correlates significantly increased between 1988 and 2004 (increase for metabolic syndrome phenotype=7.6%, for obesity=13.3%, and for elevated C-reactive protein=10.6%; P < .001 for all 3). Hispanic women were more likely than were White women to possess the phenotype (P = .004). Women who reported that their mothers had been diagnosed with diabetes were more likely to possess the phenotype than those whose mothers had not been so diagnosed (odds ratio=1.9; 95% confidence interval=1.3, 2.8).

CONCLUSIONS

The current trends of metabolic syndrome among women of childbearing age demonstrate the need for additional rigorous investigations regarding its long-term effects in these women and their offspring.

Cyclic vomiting syndrome in adults

Cyclic vomiting syndrome (CVS) was initially described in children but can occur in all age groups. Cyclic vomiting syndrome is increasingly recognized in adults. However, the lack of awareness of CVS in adults has led to small numbers of diagnosed patients and a paucity of published data on the causes, diagnosis and management of CVS in adults. This article is a state-of-knowledge overview on CVS in adults and is intended to provide a framework for management and further investigations into CVS in adults.

The Environmental Genome Project: phase I and beyond

Human illness is caused by many interrelated factors including aging, inherited genetic predispositions, and a variety of environmental exposures. There is increasing awareness of the role of genetics as a factor that can dramatically alter susceptibility to all disease, especially environmentally induced chronic disease, such as cancer, asthma, diabetes, cardiovascular disease, and neurodegenerative disorders. In some cases, a genetic factor influences disease susceptibility in a small fraction of the population because it occurs at a low frequency or involves a relatively low-incidence disease; however, in other cases, a genetic factor increases susceptibility in a large number of individuals and involves a disease that occurs at high incidence, creating a large public health burden.

The cell interaction sites of fibronectin in tumour metastasis

Adhesion to specific extracellular matrix molecules appears to be an important prerequisite for successful target organ colonization by metastasizing tumour cells. Interference in the adhesive function of malignant cells with antiadhesive agents is therefore one potential approach for preventing metastasis. Recently, synthetic peptides taken from the cell interaction sites of fibronectin have been characterized as inhibitors of cellular adhesion in vitro. Using these antiadhesive probes we have examined the role of cell adhesion to fibronectin in tumour metastasis using the B16-F10 murine melanoma model system. Two sequences from the IIICS cell-binding domain, the 25-mer CS1 peptide and the tetrapeptide Arg-Glu-Asp-Val (REDV), had no detectable activity, but the pentapeptide Gly-Arg-Gly-Asp-Ser (GRGDS), an active sequence from the central cell-binding domain, exhibited potent, dose-dependent inhibition, indicating a role for this cell recognition determinant in tumour metastasis. Under appropriate conditions GRGDS treatment afforded remarkable protection to the host; mice injected with melanoma cells and peptide were still alive 15 months after injection whereas mice injected with melanoma cells alone died within six weeks. Kinetic analyses of the retention of tumour cells in the lungs and of the vascular clearance rate of labelled GRGDS predict an early time frame of activity for the peptide. From the results of a variety of in vitro invasion and migration assays it appears that GRGDS may interfere with multiple, fibronectin-mediated adhesive and migratory events at different points of the metastatic cascade. In preliminary studies designed to optimize the therapeutic usefulness of GRGDS-like agents, peptide conjugates have been found to possess enhanced antiadhesive activity as well as an extended vascular clearance rate. In the future, therefore, these or related peptide derivatives may be potentially useful agents for the prevention of tumour metastasis.

Toxicogenomics--a new systems toxicology approach to understanding of gene-environment interactions

Toxicogenomics is a new interdisciplinary area of research being developed to monitor the expression of multiple genes, proteins, and metabolites simultaneously. It combines new technologies in genomics, proteomics, and metabolomics with traditional tools of pathology and toxicology to study biological response to drugs and other environmental xenobiotics. The biological response to environmental exposure is so complex and involves so many interactive factors that the use of a systems biology analytical approach is required. In my opinion, the development of the field of toxicogenomics will provide powerful and relatively inexpensive tools to identify biomarkers and to relate exposure and biological events during disease progression.

The second National Institutes of Health International Congress on advances in uterine leiomyoma research: conference summary and future recommendations

OBJECTIVE

To summarize the proceedings of the Advances in Uterine Leiomyoma Research: 2nd NIH International Congress, which was convened on February 24-25, 2005 by the Department of Health and Human Services (DHHS), National Institutes of Health (NIH) in Bethesda, Maryland.

DESIGN

Scientific information was presented at a 2-day conference, which was a collaborative effort of agencies across the DHHS and members of the academic, clinical, and medical communities involved in uterine leiomyoma research.

CONCLUSION(S)

The conference brought together scientists in biomedicine, epidemiology, basic research, therapeutics, and translational medicine and fostered an exchange of scientific information among members of the uterine leiomyoma research and health care communities. This document summarizes this exchange and outlines research needs and recommendations for future research directions.

15(S)-Lipoxygenase-2 Mediates Arachidonic Acid-stimulated Adhesion of Human Breast Carcinoma Cells through the Activation of TAK1, MKK6, and p38 MAPK

The dietary cis-polyunsaturated fatty acid, arachidonic acid, stimulates adhesion of metastatic human breast carcinoma cells (MDA-MB-435) to the extracellular matrix, but the molecular mechanisms by which fatty acids modify the behavior of these cells are unclear. Exposure to arachidonic acid activates multiple signaling pathways. Activation of p38 mitogen-activated protein kinase (p38 MAPK) is required for increased cell adhesion to type IV collagen, and this activation is sensitive to inhibitors of lipoxygenases, suggesting a requirement for arachidonic acid metabolism. The goals of the current study were to identify the one or more key metabolites of arachidonic acid that are responsible for activation of p38 MAPK and to elucidate the upstream kinases that lead to p38 MAPK activation. High performance liquid chromatographic analysis revealed that MDA-MB-435 cells metabolize exogenous arachidonic acid predominantly to 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE). Immunoblot analysis with antibodies specific to 15(S)-lipoxygenase-1 (LOX-1) and 15(S)-lipoxygenase-2 (LOX-2) demonstrated the expression of 15-LOX-2, but not 15-LOX-1, in these tumor cells. A LOX inhibitor, nordihydroguaiaretic acid, attenuated production of 15(S)-HETE and inhibited the phosphorylation of p38 MAPK following exposure to arachidonic acid. In contrast, overexpression of LOX-2 sensitized the cells to the addition of arachidonic acid, leading to increased activation of p38 MAPK. Addition of exogenous 15(S)-HETE to MDA-MB-435 cells stimulated cell adhesion to type IV collagen and activated the p38 MAPK pathway, including the upstream kinases transforming growth factor-beta1-activated protein kinase-1 (TAK1) and MAPK kinase 6. Transfection of these cells with a dominant negative form of TAK1 blocked arachidonic acid-stimulated p38 MAPK phosphorylation. These data demonstrate that 15(S)-LOX-2 generation of 15(S)-HETE activates specific growth factor receptor-related signaling pathways, thereby initiating signal transduction events leading to increased cell adhesion to the extracellular matrix.

Health-related disparities: influence of environmental factors

Racial disparities in health cannot be explained solely on the basis of poverty, access to health care, behavior, or environmental factors. Their complex etiology is dependent on interactions between all these factors plus genetics. Scientists have been slow to consider genetics as a risk factor because genetic polymorphisms tend to be more variable within a race than between races. Now that studies are demonstrating the existence of racial differences in allelic frequencies for multiple genes affecting a single biologic mechanism, the present argument for a significant genetic role in contributing to health disparities is gaining support. Individuals vary, often significantly, in their response to environmental agents. This variability provides a high "background noise" when scientists examine human populations to identify environmental links to disease. This variability often masks important environmental contributors to disease risk and is a major impediment to efforts to investigate the causes of diseases.Fortunately, investments in the various genome projects have led to the development of tools and databases that can be used to help identify the genetic variations in environmental response genes that can lead to such wide differences in disease susceptibility. NIEHS developed the environ-mental genome project to catalog these genetic variants (polymorphisms)and to identify the ones that play a major role in human susceptibility to environmental agents. This information is being used in epidemiologic studies to pinpoint environmental contributors to disease better. The research summarized in this article is critically important for tying genetics and the environment to health disparities, and for the development of a rational approach to gauge environmental threats. Common variants in genes play pivotal roles in determining if or when illness or death result from exposure to drugs or environmental xenobiotics. Most common variants exist in all human populations, but their frequency can vary substantially,rendering individuals or groups more or less susceptible to particular environmental exposures. Such findings are consistent with the highly publicized analogy, "genetics loads the gun, but the environment pulls the trigger." That is, one can inherit the genetic predisposition to develop a disease but will do so only if or when exposed to the environmental trigger. Poor people have approximately the same genetic makeup as everyone else,but they have the unfortunate experience of living and working in environments containing multiple and high levels of carcinogens or other toxicants capable of interacting with susceptibility genes to cause disease.Furthermore, certain disadvantaged ethnic groups may have a higher incidence of certain susceptible genes that render them more vulnerable to adverse effects of the environments they inhabit. For both of these reasons,much of the nation's disease burden could likely be reduced through better environmental protection practices, especially in low-income and minority communities. Of the many implications of polymorphisms and frequency variations for public health and the practice of medicine, however, none is more urgent than the choice of drugs in therapy. Using such knowledge,randomized trials have identified race-specific drug response differences between blacks and whites [42].To date, most knowledge of the health effects of environmental factors is derived from studies of single agents. The reality, though, is that environmental contributions to health disparities are mostly from multiple agents. These simultaneous exposures to multiple risk factors, which may accumulate or interact synergistically, remain to be fully explained and defined.Finally, health disparity is a significant public health problem that cannot be solved using "business as usual" approaches for funding and priority setting. The current emphasis on basic and clinical research at the exclusion of public health and the social sciences does not provide the interdisciplinary research teams necessary to address such a complex problem as health disparities. Although the poor will always be with us, their health could be greatly improved if social, environmental, and genetic scientists could find ways to collaborate and develop more insightful and relevant ways to address the health of disadvantaged communities.

Genomics in environmental health research--opportunities and challenges

Environmental health research impacts both environmental health regulatory policy and the practice of medicine. However, this area of medical research has not garnered public support and attention of medical researchers because of its emphasis on prevention and public health. Also, the pervasiveness of a scientific culture wedded to old problems and outdated technologies and models systems has not been helpful in generating enthusiasm for the field. While the emphasis on prevention is both laudable and appropriate, the adoption of cutting-edge technologies to exploit the new scientific opportunities, made possible by the nation's investment in genomics, is essential if the discipline expects to be competitive with other highly deserving programs. The new 'omics' era of environmental health research, ushered in over the past decade, characterized by the linkage of genomics, proteomics and metabolomics to conventional toxicology and pathology databases, holds great promise for elucidating mechanisms of gene-environment interaction in human health and disease. These combined approaches will allow one to monitor multiple molecular events, pathways and interactive networks simultaneously-a requirement for elucidating toxic mechanisms. But, before embracing the 'omics' technologies as the 'be all-end all;' they need to be validated for their predictive capacities in large-scale multi-institutional studies, such as those described in this article.

Toxicogenomics through the eyes of informatics: conference overview and recommendations

Virginia Bioinformatics Institute, in conjunction with National Institutes of Environmental Health Sciences, hosted a conference, "Toxicogenomics through the Eyes of Informatics," in Bethesda, Maryland, USA, on 12-13 May 2003. Researchers around the world met to discuss how the application of bioinformatics tools, methodologies, and technologies will enhance our understanding of how cells and organisms respond to toxins. Conference topics included statistical methods, quantitative molecular data sets, computational algorithms for data analysis, computational modeling and simulation, challenges and opportunities in computational biology, and information technology infrastructure for data and tool management. This meeting report is a summary of conference presentations, survey results, current toxicogenomics concerns, and future directions of the toxicogenomics community. In conclusion this report discusses toxicogenomics as related to environmental agents, cell-chemical reactions, and gene-environment interactions.

Multidisciplinary research: strategies for assessing chemical mixtures to reduce risk of exposure and disease

The Precautionary Principle is founded on the use of comprehensive, coordinated research to protect human health in the face of uncertain risks. Research directed at key data gaps may significantly reduce the uncertainty underlying the complexities of assessing risk to mixtures. The National Institute of Environmental Health Sciences (NIEHS) has taken a leadership role in building the scientific infrastructure to address these uncertainties. The challenge is to incorporate the objectives as defined by the Precautionary Principle with the knowledge gained in understanding the multifactorial nature of gene-environment interactions. Through efforts such as the National Center for Toxicogenomics, the National Toxicology Program, and the Superfund Basic Research Program, NIEHS is translating research findings into public health prevention strategies using a 3-pronged approach: 1) identify/evaluate key deviations from additivity for mixtures; 2) develop/apply/link advanced technologies and bioinformatics to quantitative tools for an integrated science-based approach to chemical mixtures; 3) translate/disseminate these technologies into useable, practical means to reduce exposure and the risk of disease. Preventing adverse health effects from environmental exposures requires translation of research findings to affected communities and must include a high level of public involvement. Integrating these approaches are necessary to advance understanding of the health relevance of exposure to mixtures.

Strategies for setting a national research agenda that is responsive to community needs

Setting a national environmental health research agenda requires broad public input, including that from leading scientists, health care professionals, and communities. Contributions from these diverse constituencies are essential to formulating a research and education strategy that both advances our understanding of the causes and mechanisms of environmentally related diseases and translates such findings into effective prevention and clinical applications to protect those most affected by adverse environmental exposures. Given the increasing number of individual researchers working with communities to address environmental health needs during the past decade, it is also essential for research institutions to foster relationships with communities to understand and respond to their unique public health needs, as well as to communicate research advances in a manner that is both understandable and culturally appropriate. To achieve broad public input and to foster community-university partnerships, the National Institute of Environmental Health Sciences (NIEHS) supports various workshops, roundtables, and advisory groups. In particular, the NIEHS finds Town Meetings to be a successful model for bringing academic researchers together with community residents, state and local departments of health, and community-based organizations to foster greater awareness of community needs, public health needs, and environmental health science research. Since 1998, the NIEHS has supported 16 Town Meetings across the country. In this article we highlight the major outcomes of these meetings to demonstrate the effectiveness of this mechanism for enhancing cooperation among researchers, community residents, and public health officials with the goal of improving public health and setting a national research agenda.

Requirement of protein kinase C micro activation and calpain-mediated proteolysis for arachidonic acid-stimulated adhesion of MDA-MB-435 human mammary carcinoma cells to collagen type IV

Arachidonic acid (AA) stimulation of adhesion of human metastatic breast carcinoma cells to collagen type IV depends on the protein kinase C (PKC) pathway(s) and is associated with the translocation of PKC mu from the cytoplasm to the membrane. In the present study, we have further explored the role of PKC mu in AA-stimulated adhesion. PKC mu activation site serines 738/742 and autophosphorylation site serine 910 are rapidly phosphorylated, and in vitro PKC mu kinase activity is enhanced in response to AA treatment. Inhibition of PKC mu activation blocks AA-stimulated adhesion. A phosphorylated, truncated species of PKC mu was detected in AA-treated cells. This 77-kDa protein contains the kinase domain but lacks a significant portion of the regulatory domains. Inhibition of calpain protease activity blocks generation of the truncated protein, promotes accumulation of the activated, full-length protein in the membrane, and blocks the AA-mediated increase in adhesion. p38 MAPK activity is also required for AA-stimulated adhesion. Activation of PKC mu and p38 are independent events. However, inhibition of p38 activity reduces calpain-mediated proteolysis of PKC mu and in vivo calpain activity, suggesting a role for p38 in regulation of calpain activity and a point for cross-talk between the PKC and MAPK pathways. These results support the hypothesis that AA stimulates activation of PKC mu, which is cleaved by calpain at the cell membrane. The resulting truncated kinase, as well as the full-length kinase, may be required for increased cell adhesion to collagen type IV. Additionally, these studies present the first evidence for calpain cleavage of a non-structural protein leading to the promotion of tumor cell adhesion.

Toxicogenomic approach for assessing toxicant-related disease

The problems of identifying environmental factors involved in the etiology of human disease and performing safety and risk assessments of drugs and chemicals have long been formidable issues. Three principal components for predicting potential human health risks are: (1) the diverse structure and properties of thousands of chemicals and other stressors in the environment; (2) the time and dose parameters that define the relationship between exposure and disease; and (3) the genetic diversity of organisms used as surrogates to determine adverse chemical effects. The global techniques evolving from successful genomics efforts are providing new exciting tools with which to address these intractable problems of environmental health and toxicology. In order to exploit the scientific opportunities, the National Institute of Environmental Health Sciences has created the National Center for Toxicogenomics (NCT). The primary mission of the NCT is to use gene expression technology, proteomics and metabolite profiling to create a reference knowledge base that will allow scientists to understand mechanisms of toxicity and to be able to predict the potential toxicity of new chemical entities and drugs. A principal scientific objective underpinning the use of microarray analysis of chemical exposures is to demonstrate the utility of signature profiling of the action of drugs or chemicals and to utilize microarray methodologies to determine biomarkers of exposure and potential adverse effects. The initial approach of the NCT is to utilize proof-of-principle experiments in an effort to "phenotypically anchor" the altered patterns of gene expression to conventional parameters of toxicity and to define dose and time relationships in which the expression of such signature genes may precede the development of overt toxicity. The microarray approach is used in conjunction with proteomic techniques to identify specific proteins that may serve as signature biomarkers. The longer-range goal of these efforts is to develop a reference relational database of chemical effects in biological systems (CEBS) that can be used to define common mechanisms of toxicity, chemical and drug actions, to define cellular pathways of response, injury and, ultimately, disease. In order to implement this strategy, the NCT has created a consortium of research organizations and private sector companies to actively collaborative in populating the database with high quality primary data. The evolution of discrete databases to a knowledge base of toxicogenomics will be accomplished through establishing relational interfaces with other sources of information on the structure and activity of chemicals such as that of the National Toxicology Program (NTP) and with databases annotating gene identity, sequence, and function.

The impact of new technologies on human population studies

Human population studies involve clinical or epidemiological observations that associate environmental exposures with health endpoints and disease. Clearly, these are the most sought after data to support assessments of human health risk from environmental exposures. However, the foundations of many health risk assessments rest on experimental studies in rodents performed at high doses that elicit adverse outcomes, such as organ toxicity or tumors. Using the results of human studies and animal data, risk assessors define the levels of environmental exposures that may lead to disease in a portion of the population. These decisions on potential health risks are frequently based on the use of default assumptions that reflect limitations in our scientific knowledge. An important immediate goal of toxicogenomics, including proteomics and metabonomics, is to offer the possibility of making decisions affecting public health and public based on detailed toxicity, mechanistic, and exposure data in which many of the uncertainties have been eliminated. Ultimately, these global technologies will dramatically impact the practice of public health and risk assessment as applied to environmental health protection. The impact is already being felt in the practice of toxicology where animal experimentation using highly controlled dose-time parameters is possible. It is also being seen in human population studies where understanding human genetic variation and genomic reactions to specific environmental exposures is enhancing our ability to uncover the causes of variations in human response to environmental exposures. These new disciplines hold the promise of reducing the costs and time lines associated with animal and human studies designed to assess both the toxicity of environmental pollutants and efficacy of therapeutic drugs. However, as with any new science, experience must be gained before the promise can be fulfilled. Given the numbers and diversity of drugs, chemicals and environmental agents; the various species in which they are studied and the time and dose factors that are critical to the induction of beneficial and adverse effects, it is only through the development of a profound knowledge base that toxicology and environmental health can rapidly advance. The National Institute of Environmental Health Sciences (NIEHS), National Center for Toxicogenomics and its university-based Toxicogenomics Research Consortium (TRC), and resource contracts, are engaged in the development, application and standardization of the science upon which to the build such a knowledge base on Chemical Effects in Biological Systems (CEBS). In addition, the NIEHS Environmental Genome Project (EGP) is working to systematically identify and characterize common sequence polymorphisms in many genes with suspected roles in determining chemical sensitivity. The rationale of the EGP is that certain genes have a greater than average influence over human susceptibility to environmental agents. If we identify and characterize the polymorphism in those genes, we will increase our understanding of human disease susceptibility. This knowledge can be used to protect susceptible individuals from disease and to reduce adverse exposure and environmentally induced disease.

Environmental health moves into the 21st century

Over the past half century, environmental health research has branched from a descriptive, observational process into one of hypothesis driven and mechanistically based science. Nevertheless, the meaning of observed effects of exposures in experimental systems to human public health remains elusive. Recent advances in genetics and "omics" hold great promise to further our abilities to assess potential human health effects and to manage exposures properly. But the comfort of 100% certainty will not be available in the foreseeable future, leaving us with the challenge of designing relevant experiments and test systems upon which to base "logical" policy in risk management.

Enhanced proliferation of functionally competent bone marrow cells in different strains of mice treated with swainsonine

The immunomodulatory alkaloid swainsonine (8alphabeta-indolizidine-1alpha,2alpha,8beta-triol) has potential for overcoming the bone marrow suppressive effects of cancer chemotherapy and radiotherapy. An earlier study showed that multiple doses of swainsonine enhanced bone marrow cellularity in four different strains (C57BL/6; C3H-HEN; Balb/C and DBA-2 mice) of inbred mice which were not exposed to any chemotherapeutic agents or radiation. In vitro assessment of total colony formation capacity of bone marrow cells (BM CFUs) showed a 2- to 8-fold increase in swainsonine-treated mice compared to control mice that were given sham injections of physiological saline. In the current study, we have evaluated the functional competence of the bone marrow cells produced in response to swainsonine treatment of normal healthy mice. In particular, colony forming units-granulocyte-macrophage (CFU-GM), erythroid-burst forming units (BFUe) and CFU-Mix (or CFU-granulocyte-erythrocyte-monocyte-megakaryocyte (CFU-GEMM)) levels, were determined using in vitro assays. The time course of the changes in CFU-GM, BFUe and CFU-Mix (CFU-GEMM) were also followed. Our results demonstrate that swainsonine bolsters the CFU capacity of BM cells without loss of function to levels which are several folds higher than in sham-treated control mice. Swainsonine treatment caused an increase in all lineages of marrow cells without loss of function. This effect was reproduced in all four strains of inbred mice in this investigation. Examination of the peripheral blood did not reveal increase in white blood cells or changes in the hematocrit levels. The long-term effects of swainsonine treatment are not known at present. Nonetheless, swainsonine-induced increase in CFU capacity of bone marrow cells and related cells along the different differentiation paths should find clinical application in cancer treatment with chemotherapeutic agents and/or radiation.

Systems toxicology and the Chemical Effects in Biological Systems (CEBS) knowledge base

The National Center for Toxicogenomics is developing the first public toxicogenomics knowledge base that combines molecular expression data sets from transcriptomics, proteomics, metabonomics, and conventional toxicology with metabolic, toxicologcal pathway, and gene regulatory network information relevant to environmental toxicology and human disease. It is called the Chemical Effects in Biological Systems (CEBS) knowledge base and is designed to meet the information needs of "systems toxicology," involving the study of perturbation by chemicals and stressors, monitoring changes in molecular expression and conventional toxicological parameters, and iteratively integrating biological response data to describe the functioning organism. Based upon functional genomics approaches used successfully in analyzing yeast gene expression data sets, relational and descriptive compendia will be assembled for toxicologically important genes, groups of genes, single nucleotide polymorphisms (SNPs), and mutant and knockout phenotypes. CEBS data sets will be fully documented in the experimental protocol and therefore searchable by compound, structure, toxicity end point, pathology and point, gene, gene group, SNP, pathway, and network as a function of dose, time, and the phenotype of the target tissue. A knowledge base is being developed by assimilating toxicological, biological, and chemical information from multiple public domain databases and by progressively refining that information about gene, protein, and metabolite expression for classes of chemicals and their biological effects in various species. By analogy to the GenBank database for genome sequences, researchers will globally query (or BLAST) CEBS using a transcriptome of a tissue of interest (or a list of outliers) to have the knowledge base return information on genes, groups of genes, metabolic and toxicological pathways, and contextually associated phenotypic information for compounds that display similar response profiles. With high-quality data content, CEBS will ultimately become a resource to support hypothesis-driven and discovery research that contributes effectively to drug safety and the improvement of risk assessments for chemicals in the environment. The CEBS development effort will span a decade or more.

Swainsonine stimulates bone marrow cell proliferation and differentiation in different strains of inbred mice

The immunomodulatory alkaloid swainsonine (8alphabeta-indolizidine-1alpha,2alpha,8beta-triol) has potential for overcoming the bone marrow suppressive effects of cancer chemotherapeutic drugs and radiation. The effect of swainsonine on bone marrow cellularity was evaluated in four different strains (C57BL/6; C3H-HEN; Balb/C and DBA-2 mice) of inbred mice subjected to multiple doses of the alkaloid. Swainsonine treatment stimulated bone marrow cell proliferation in all strains of mice. Examination of the peripheral blood did not reveal any increase in total leukocyte count. In vitro assessment of total colony-forming unit (CFU) capacity of bone marrow cells showed a two- to eight-fold increase in swainsonine treated mice of different strains compared to their corresponding controls given sham injections of physiological saline. Swainsonine induced increase in CFU capacity of bone marrow cells should find clinical application in cancer treatment with chemotherapeutic agents and radiation.