1. Discuss your understanding of interaction and how it applies in an epidemiological study.
"Biological interaction occurs" when the effect of one risk factor is different within strata defined by the other" (Kanchanaraksa, 2008, p.3). There is no biological interaction between two risk factors if the two groups under study have the same risk, and there is a biological interaction if the risk is different (Kanchanaraksa, 2008).
On the other hand, "statistical interaction occurs when the incidence of disease in the presence of two or more risk factors differs from the incidence expected to result from their individual effects" (Kanchanaraksa, 2008, p.6). Statistical interaction is measured based on risk calculations, where risks act multiplicatively when ratios are used and act additively when differences are used. Although this may not reflect the actual biological relationship, it is assumed to be interactive on a measurement basis. We can also assess these interactions using risk ratios or risk differences in epidemiological studies.
Epidemiologically, synergistic interactions increase the likelihood of disease, and antagonistic interactions decrease the possibility of disease (Kanchanaraksa, 2008).
These interacting concepts can help identify disease causes, hazards, transmission routes, risk factors, mortality rates, etc., and contribute to managing and controlling all diseases. It also contributes to the prevention of future diseases and the sustainability of society.
2. Provide an example of a synergistic interaction and an example of an antagonistic interaction.
A synergistic interaction implies that a given exposure makes a person more susceptible to further/other exposures, resulting in increased disease risk.
Chloroform is a substance mainly used as a raw material in manufacturing chemicals and is also frequently used as a pharmaceutical disinfectant and solvent. Also, carbon tetrachloride is a substance produced when chloroform and chlorine react and is used for experimental research and analysis. Ethanol is frequently used as an antiseptic solution, and is also used to disinfect skin and surgical sites, as well as for cleaning and disinfecting medical /experimental instruments. Chloroform, carbon tetrachloride, and ethanol are all toxic to the liver, but when mixed, the effects on the liver are even more severe, causing many liver disorders (Teschke & Gellert, 1984).
Factories that process wastewater/waste from research institutions and medical institutions handle many of these dangerous substances. When these substances are mistakenly mixed, their synergistic interactions can seriously affect the human body.
An antagonistic interaction means that a particular exposure makes a person less susceptible to further/other exposures, thus reducing the risk of disease.
Breast cancer cells have estrogen receptors, and the action of estrogen on these receptors activates breast cancer cells, making breast cancer more likely to progress. Hormone therapy for breast cancer takes advantage of the fact that breast cancer proliferates under the influence of estrogen and suppresses the production of estrogen or blocks the binding of estrogen to its receptors, thereby suppressing the growth of cancer cells (Mayo Clinic Staff, 2022).
Administrating an estrogen receptor antagonist such as Letrozole and Anastrozole etc. (DrugBank Online, n.d.) blocks the action of estrogen at estrogen receptors and consequently slows breast cancer progression.
Thank you, professor. (504 words)
References
DrugBank Online. (n.d.). Estrogen antagonists. Estrogen Antagonists | DrugBank Online. Retrieved December 23, 2022, from https://go.drugbank.com/categories/DBCAT000786
Kanchanaraksa, S. (2008). Bias and confounding [PowerPoint file]. John Hopkins University. Retrieved from https://my.uopeople.edu/pluginfile.php/1635156/mod_book/chapter/380251/Lecture20.pdf
Mayo Clinic Staff. (2022). Breast cancer - Diagnosis & treatment. Mayo Clinic. Retrieved from https://www.mayoclinic.org/diseases-conditions/breast-cancer/diagnosis-treatment/drc-20352475
Teschke, R., Vierke, W., & Gellert, J. (1984). Effect of ethanol on carbon tetrachloride levels and hepatotoxicity after acute carbon tetrachloride poisoning. Archives of toxicology, 56(2), 78–82. https://doi.org/10.1007/BF00349075 Retrieved from https://pubmed.ncbi.nlm.nih.gov/6532381/
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