The effect of environmental chemicals on the tumor microenvironment

Potentially carcinogenic compounds may cause cancer through direct DNA damage or through indirect cellular or physiological effects. To study possible carcinogens, the fields of endocrinology, genetics, epigenetics, medicine, environmental health, toxicology, pharmacology and oncology must be considered. Disruptive chemicals may also contribute to multiple stages of tumor development through effects on the tumor microenvironment. In turn, the tumor microenvironment consists of a complex interaction among blood vessels that feed the tumor, the extracellular matrix that provides structural and biochemical support, signaling molecules that send messages and soluble factors such as cytokines. The tumor microenvironment also consists of many host cellular effectors including multipotent stromal cells/mesenchymal stem cells, fibroblasts, endothelial cell precursors, antigen-presenting cells, lymphocytes and innate immune cells. Carcinogens can influence the tumor microenvironment through effects on epithelial cells, the most common origin of cancer, as well as on stromal cells, extracellular matrix components and immune cells. Here, we review how environmental exposures can perturb the tumor microenvironment. We suggest a role for disrupting chemicals such as nickel chloride, Bisphenol A, butyltins, methylmercury and paraquat as well as more traditional carcinogens, such as radiation, and pharmaceuticals, such as diabetes medications, in the disruption of the tumor microenvironment. Further studies interrogating the role of chemicals and their mixtures in dose-dependent effects on the tumor microenvironment could have important general mechanistic implications for the etiology and prevention of tumorigenesis

The couple as context: Latino gay male couples and HIV

HIV-prevention efforts with gay men in relationships frequently omit primary partners. When they are considered, examinations of race/ethnicity are often overlooked despite higher infection rates among gay men of colour. Acknowledging both the need to contextualise the behaviours that may affect HIV risk for gay men of colour and the disproportionate impact of HIV on Latino gay men, the present study utilised semi-structured, qualitative interviews to explore relationship dynamics, sexual agreements and behaviours, safer sex choices and HIV risk among nine Latino gay male couples. All participants were HIV-negative and in concordant negative relationships. Additionally, nearly all reported closed agreements. Analysis revealed participants engaging in four behaviours that may actively reduce their HIV risk: approaching sexual agreements from a practical standpoint, maintaining a high literacy around HIV, having exposure to social support groups for Latino gay men and finding support in their relationship with another Latino gay man. Additional issues are raised where long-term HIV prevention is concerned. Intimate relationships are an important context for understanding both HIV risk and prevention among Latino gay men. Likewise, race/ethnicity provides an indispensable perspective on all research with gay couples. Future prevention efforts with gay men must strive to include both

Relationship dynamics as predictors of broken agreements about outside sexual partners: implications for HIV prevention among gay couples.

Agreements about sex with outside partners are common among gay couples, and breaks in these agreements can be indicative of HIV risk. Using longitudinal survey data from both partners in 263 HIV-negative and -discordant gay couples, we investigate whether relationship dynamics are associated with broken agreements. Twenty-three percent of respondents reported broken agreements. Partners with higher levels of trust, communication, commitment, and social support were significantly less likely to report breaking their agreement. Promoting positive relationship dynamics as part of HIV prevention interventions for gay couples provides the opportunity to minimize the occurrence of broken agreements and, ultimately, reduce HIV risk

Relationship dynamics as predictors of broken agreements about outside sexual partners: implications for HIV prevention among gay couples.

Agreements about sex with outside partners are common among gay couples, and breaks in these agreements can be indicative of HIV risk. Using longitudinal survey data from both partners in 263 HIV-negative and -discordant gay couples, we investigate whether relationship dynamics are associated with broken agreements. Twenty-three percent of respondents reported broken agreements. Partners with higher levels of trust, communication, commitment, and social support were significantly less likely to report breaking their agreement. Promoting positive relationship dynamics as part of HIV prevention interventions for gay couples provides the opportunity to minimize the occurrence of broken agreements and, ultimately, reduce HIV risk