A complex systems model of breast cancer etiology: The Paradigm II Model

BACKGROUND: Complex systems models of breast cancer have previously focused on prediction of prognosis and clinical events for individual women. There is a need for understanding breast cancer at the population level for public health decision-making, for identifying gaps in epidemiologic knowledge and for the education of the public as to the complexity of this most common of cancers. METHODS AND FINDINGS: We developed an agent-based model of breast cancer for the women of the state of California using data from the U.S. Census, the California Health Interview Survey, the California Cancer Registry, the National Health and Nutrition Examination Survey and the literature. The model was implemented in the Julia programming language and R computing environment. The Paradigm II model development followed a transdisciplinary process with expertise from multiple relevant disciplinary experts from genetics to epidemiology and sociology with the goal of exploring both upstream determinants at the population level and pathophysiologic etiologic factors at the biologic level. The resulting model reproduces in a reasonable manner the overall age-specific incidence curve for the years 2008-2012 and incidence and relative risks due to specific risk factors such as BRCA1, polygenic risk, alcohol consumption, hormone therapy, breastfeeding, oral contraceptive use and scenarios for environmental toxin exposures. CONCLUSIONS: The Paradigm II model illustrates the role of multiple etiologic factors in breast cancer from domains of biology, behavior and the environment. The value of the model is in providing a virtual laboratory to evaluate a wide range of potential interventions into the social, environmental and behavioral determinants of breast cancer at the population level. Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose

Egg excretion in the initial phase of experimental murine schistosomiasis mansoni: stability and association with worm burden Esquistossomose mansoni experimental murina: estabilidade da eliminação dos ovos nas fezes e sua associação com a carga parasitária na fase inicial da infecção

Stability of faecal egg excretion and correlation with results related to worm burden at the initial phase of schistosomiasis mansoni were observed in two groups of mice infected with different Schistosoma mansoni cercarial burdens, by means of analysis of quantitative parasitological studies and schistosome counts after perfusion. Thus, it may be stated that few quantitative parasitological stool examinations could be sufficient to express the infection intensity at the initial phase, on the same grounds that it was already demonstrated at the chronic phase. Furthermore, it is confirmed that the use of the number of eggs passed in the faeces as a tool to estimate the worm burden at the initial phase of schistosome infection is adequate.<br>Através da análise de exames parasitológicos quantitativos seriados e da contagem de esquistossomos após perfusão em dois grupos de camundongos infectados com diferentes cargas de cercárias de Schistosoma mansoni, verificou-se a existência da estabilidade da eliminação de ovos e sua correlação com a carga parasitária na fase inicial da esquistossomose mansoni. Deste modo, pode-se afirmar que poucos exames parasitológicos de fezes quantitativos podem ser suficientes para traduzir a intensidade da infecção também na fase inicial , à semelhança do já demonstrado para a crônica. Além disto, comprova-se a adequação do uso do número de ovos eliminados nas fezes como expressão da carga parasitária na fase inicial da infecção esquistossomótica