Search

The propensity of malignant gliomas to invade surrounding brain tissue contributes to poor clinical outcome. Integrin-mediated adhesion to extracellular matrix regulates the migration and proliferation of many cell types, but its role in glioma progression is undefined. We investigated the role of the cytoplasmic tyrosine kinases FAK and Pyk2, potential integrin effectors, in the phenotypic determination of four different human glioblastoma cell lines. While FAK expression was similar between the four cell lines, increased FAK activity correlated with high proliferation and low migratory rates. In contrast, Pyk2 activity was significantly increased in migratory cell lines and depressed in proliferative cell lines. Overexpression of Pyk2 stimulated migration, whereas FAK overexpression inhibited cell migration and stimulated cellular proliferation. These data suggest that FAK and Pyk2 function as important signaling effectors in gliomas and indicate that their differential regulation may be determining factors in the temporal development of proliferative or migrational phenotypes.

Associated with the metastatic progression of epithelial tumors is the dynamic regulation of cadherins. Whereas E-cadherin is expressed in most epithelium and carcinomas, recent studies suggest that the up-regulation of other cadherin subtypes in carcinomas, such as N-cadherin, may function in cancer progression. We demonstrate that a signal transduction cascade links the N-cadherin.catenin adhesion complex to up-regulation of the anti-apoptotic protein Bcl-2. In suspension, aggregates of DU-145 cells, an E-cadherin expressing human prostate carcinoma line, survive loss of integrin-dependent adhesion by a different anti-apoptotic signaling pathway than the N-cadherin expressing lines PC3 and PC3N. N-cadherin intercellular adhesion mediates a 3.5-fold increase in Bcl-2 protein expression, whereas the level of the proapoptotic protein Bax remains constant. Only N-cadherin ligation in PC3 cells, which express both N-cadherin and E-cadherin, is sufficient to induce activation of Akt/protein kinase B. N-cadherin homophilic ligation initiates phosphatidylinositol 3-kinase-dependent activation of Akt resulting in Akt phosphorylation of Bad on serine 136. Following N-cadherin homophilic adhesion phosphatidylinositol 3-kinase was identified in immunoprecipitates of the N-cadherin.catenin complex. The recruitment of phosphatidylinositol 3-kinase to the adhesion complex is dependent on ligation of N-cadherin and an organized actin cytoskeleton because cytochalasin D blocks the recruitment. We propose that N-cadherin homophilic adhesion can initiate anti-apoptotic signaling, which enhances the Akt cell survival pathway in metastatic cancer.

Heterocylic amine (HA) compounds formed in the cooking of certain foods have been shown to be bacterial mutagens and animal carcinogens, and may be a risk factor for human cancer. To help explain the variation observed in HA formation under different cooking conditions, we have performed heat-flow simulations and experiments on the pan-frying of beef patties. The simulations involve modeling the heat flow within a meat patty using empirically derived thermal transport coefficients for the meat. The predicted temperature profiles are used to integrate the Arrhenius rate equation to estimate the concentration of HAs formed in the meat. We find that our simulations accurately model experimentally determined temperature profiles, cooking times, HA spatial distributions and total HA formation in patties that are flipped once during the pan-frying process. For patties flipped every 60 s, the simulations qualitatively agree with experiment in predicting reduced cooking times and HA formation relative to the singly-flipped patties. However, the simulations overestimate the effect of rapid flipping on cooking times and underestimate the effect of flipping on total HAs formed. These results suggest that the dramatic reductions in HA formation due to rapid flipping may be due to factors other than the heating process or that there is a critical feature of the flipping process that is not captured in our model.

Efforts to cope with the legacy of our industrial cities--blight, poverty, environmental degradation, ailing communities--have galvanized action across the public and private sectors to move vacant industrial land, also referred to as brownfields, to productive use; to curb sprawling development outside urban areas; and to reinvigorate urban communities. Such efforts, however, may be proceeding without thorough investigations into the environmental health and safety risks associated with industrial brownfields properties and the needs of affected neighborhoods. We describe an approach to characterize vacant and underused industrial and commercial properties in Southeast Baltimore and the health and well being of communities living near these properties. The screening algorithm developed to score and rank properties in Southeast Baltimore (n= 182) showed that these sites are not benign. The historical data revealed a range of hazardous operations, including metal smelting, oil refining, warehousing, and transportation, as well as paints, plastics, and metals manufacturing. The data also identified hazardous substances linked to these properties, including heavy metals, solvents, polycyclic aromatic hydrocarbons, plasticizers, and insecticides, all of which are suspected or recognized toxicants and many of which are persistent in the environment. The health analysis revealed disparities across Southeast Baltimore communities, including excess deaths from respiratory illness (lung cancer, chronic obstructive pulmonary disease, influenza, and pneumonia), total cancers, and a "leading cause of death" index and a spatial and statistical relationship between environmentally degraded brownfields areas and at-risk communities. Brownfields redevelopment is a key component of our national efforts to address environmental justice and health disparities across urban communities and is critical to urban revitalization. Incorporating public health into brownfields-related cleanup and land-use decisions will increase the odds for successful neighborhood redevelopment and long-term public health benefits.

Matrilysin is a matrix metalloprotease (MMP) overexpressed in a number of cancers including skin, head and neck squamous cell carcinomas, and prostate and colon adenocarcinomas. Matrilysin has been shown to play a role in the degradation of the basement membrane that separates epithelium from stroma allowing tumor cells to intravasate into the bloodstream and metastasize. Here, we show that an oral squamous cell carcinoma cell line (SCC-25) expresses low levels of promatrilysin when cultured alone. However, when SCC-25 cells are cocultured with human foreskin fibroblasts (HFF), there is a 40-fold induction of promatrilysin expression. We tested whether this induction of promatrilysin expression was due to the release of paracrine factors, cell-cell interactions, or cell-matrix interactions. Our results indicate induced promatrilysin expression is the result of both cell-cell and cell-matrix interactions. We demonstrate that beta1 integrins as well as cadherins, specifically N-cadherin and E-cadherin, are involved in the induction of promatrilysin expression. Our results are of general interest in relation to the regulation of MMP expression through cell surface receptor regulation. Further investigation may lead to the identification of novel targets for suppression of invasion and metastasis in oral tumors., (Copyright 2001 Academic Press.)

Driven by differing statutory mandates and programmatic separation of regulatory responsibilities between federal, state, and tribal agencies, distinct chemical and radiation risk management strategies have evolved. In the field this separation poses real challenges since many of the major environmental risk management decisions we face today require the evaluation of both types of risks. Over the last decade, federal, state, and tribal agencies have continued to discuss their different approaches and explore areas where their activities could be harmonized. The current framework for managing public exposures to chemical carcinogens has been referred to as a "bottom up approach." Risk between 10(-4) and 10(-6) is established as an upper bound goal. In contrast, a "top down" approach that sets an upper bound dose limit and couples with site specific As Low As Reasonably Achievable Principle (ALARA), is in place to manage individual exposure to radiation. While radiation risk are typically managed on a cumulative basis, exposure to chemicals is generally managed on a chemical-by-chemical, medium-by-medium basis. There are also differences in the nature and size of sites where chemical and radiation contamination is found. Such differences result in divergent management concerns. In spite of these differences, there are several common and practical concerns among radiation and chemical risk managers. They include 1) the issue of cost for site redevelopment and long-term stewardship, 2) public acceptance and involvement, and 3) the need for flexible risk management framework to address the first two issues. This article attempts to synthesize key differences, opportunities for harmonization, and challenges ahead.

In human prostate adenocarcinoma, an association between loss of E-cadherin, increased Gleason score, and extracapsular dissemination has been observed. Further characterization of the E-cadherin/catenin phenotype of human prostate carcinoma cell lines showed loss of E-cadherin and expression of N-cadherin in poorly differentiated prostate carcinoma cell lines (PC-3N derived from PC-3, PC-3, and JCA1). We showed that N-cadherin is concentrated at sites of cell-cell contact in PC-3N cellular extensions. N-cadherin was also expressed in prostate stromal fibroblasts both in vitro and in prostate tissue. Co-cultures of prostate stromal fibroblasts and PC-3N cells showed the immunolocalization of N-cadherin in intercellular contacts. In addition, the isoform expression of the cadherin binding protein p120(ctn) differed in relation to the expression of E- versus N-cadherin by the prostate carcinoma cell lines. The p100 isoform was more highly expressed in E-cadherin-positive carcinoma cell lines, whereas p120 was predominantly expressed only in N-cadherin-positive prostate carcinoma cell lines and prostate stromal fibroblasts. The N-cadherin-positive carcinoma cell line, PC-3N, displayed aggressive invasion into the surface of the diaphragm muscle after intraperitoneal injection of SCID mice. The gain of N-cadherin and loss of E-cadherin by invasive prostate carcinoma cell lines suggests a progression from an epithelial to a mesenchymal phenotype, which may allow for their interaction with surrounding stromal fibroblasts and facilitate metastasis.

The nitrogen mustard based DNA alkylating agents were the first effective anticancer agents and remain important drugs against many forms of cancer. More than fifty years of research on the nitrogen mustards has yielded a broad range of therapeutically useful compounds and a detailed knowledge of the biochemical mechanism of these drugs. Nevertheless, there is much ongoing research on the phosphosphoramidic and other nitrogen mustards to increase their potency and reduce their toxic and mutagenic side effects. To understand the existing nitrogen mustards, and to design the next generation of these drugs, more knowledge is needed about the effects of chemical modifications on their activation and selectivity. Because of the existing knowledge of these drugs, atomic-level chemical modeling can play an important role in the understanding of the phosphoramidic mustard compounds; however, it has not proved straight forward to directly relate the activity of these mustards with simple chemical properties such as bond lengths or atomic charges. Instead, quantum chemical simulations will be required to simulate the activation and alkylation reactions of these compounds, which will require the newest generation of quantum chemical and solvent modeling methods. Additionally, molecular dynamics simulations of the adducted DNA can provide data on the factors favoring crosslinking and its structural consequences. This review summarizes the extensive literature on the metabolism, activation, and action of the phosphoramidic mustards, with an emphasis on the roles that chemical modeling has and will play in the development of this important class of drugs.

The success of our national environmental policies depends upon the capacity of states to implement them. This article presents the findings of an examination of the state level organization of environmental health and protection services. The goals of the project were to conduct a descriptive analysis of the structure, functions, and funding of state environmental health and protection services, and to examine the impact of the major federal environmental statutes on the organization of the state infrastructure. Future environmental progress will depend upon an improved understanding of the relationship between human health and the environment. This will require a commitment to improving the public health training of environmental professionals, and improved cooperation between health and environmental agencies to assure that they do not lose sight of their fundamental mission--the protection of public health.

The Dietary Exposure Potential Model (DEPM) is a computer-based model developed for estimating dietary exposure to chemical residues in food. The DEPM is based on food consumption data from the 1987-1988 Nationwide Food Consumption Survey (NFCS) administered by the United States Department of Agriculture (USDA) and on residue data from government-sponsored monitoring programs. Foods reported in the NFCS were categorized into exposure core foods (ECFs). A computer program for DOS-based personal computers was developed to link consumption of the ECFs with residue values observed in the foods. The data files utilized by the DEPM were designed in dBASE IV with FoxPro for Windows applications programs for queries and reporting. The program calculates exposure estimates for categories of core foods, such as grain dishes, fruits, or vegetables; for individual core foods, such as wheat and apple combination dishes; and for individual foods, such as apples or carrots. The program, residue summary databases, and core food consumption database permit the analyst to evaluate potential exposure of several population groups to various chemicals via the diet. The DEPM is not intended for risk assessments, but is a suitable tool for identifying data gaps and establishing priorities for research, and for identifying potentially significant foods for human exposure monitoring.

Purpose: The purpose of this study were to evaluate the use of individual compartmental and population compartmental methods for bioequivalence determination, and to determine their utility as adjuncts to the current methods used for bioequivalence assessment., Methods: Data from three bioequivalence studies of chlorthalidone were analyzed with PCNONLIN using individual compartmental modeling and NONMEM for population analyses. These results were compared with results obtained from the traditional noncompartmental or SHAM (slopes, heights, areas, and moments) approach for bioequivalence assessment and the 90% confidence interval procedure., Results: Individual compartmental modeling and population compartmental modeling techniques performed well on this routine set of bioequivalence data which displayed simple pharmacokinetic properties. A direct assessment of the analysis methods was made by comparing the final estimates and 90% confidence intervals for the test to reference ratios (T/R) of AUC and CMAX. The final estimates and 90% confidence intervals for AUC T/R and CMAX T/R were similar and suggest consistency of results, independent of the method used., Conclusions: These results demonstrate the utility of modeling techniques as adjuncts to the traditional noncompartmental approach for bioequivalence determination.

Attachment sites and biological functions of laminin isolated from murine EHS sarcoma have been well studied. Recently several variants of laminin including human placental laminin have been shown to be distinct from EHS-laminin. This study was undertaken to determine attachment, proliferation, and migration phenomena of human astrocytoma cell lines to human and murine sarcoma EHS-laminin. Using short-term attachment assays human placental laminin was shown to be the better substrate for cell adhesion. EHS-laminin mediated approximately 30-50% of the effect observed on human laminin. The astrocytoma cells expressed beta 1, beta 3, and beta 4 subunit mRNA as determined by RT-PCR. Anti-beta 1 antibodies blocked adhesion to EHS-laminin, but antibodies against beta 1, beta 4, and alpha v subunits were all ineffective in blocking adhesion to human laminin. A migration assay showed that astrocytoma cells on human laminin dispersed from a central seeding area, while cells on EHS-laminin remained where they were seeded. The pattern of dispersion could not be accounted for by changes in growth rates of astrocytoma cells on the different proteins, since both cell lines grew equally well on the two laminins. We conclude that unique epitopes on human laminin are recognized by novel receptors on human astrocytoma cells which confer a migratory phenotype to the cells.