The frequency response of renal blood flow was estimated to test our suggestion that autoregulation had one fast and one slow component. Arterial pressure was varied periodically by a pump connected to the distal aorta or aperiodically by stimulating atrial fibrillation. There was only one regulatory mechanism, corresponding to the slow component seen earlier. Two apparent regulators were seen when pressure was measured far from the renal artery (right common carotid), rather than near (superior mesenteric). Simultaneous measurements of pressure in both arteries showed interference of the pressure wave from the heart with pressure waves from the pump in the distal aorta at frequencies near that of the heart rate. Measurements made in the superior mesenteric artery were likely to be correct. The earlier results were in error, and frequency response methods detect only one regulator. Animals made acutely hypertensive behaved similarly. The effect of the regulator appears as a phase shift at frequencies of 0.25 Hz and below and an attenuated flow magnitude at frequencies below 0.1 Hz. This frequency response is consistent with the flow propagation time to the macula densa. We conclude that macula densa feedback was the only flow-regulating mechanism detected.

No abstract

TCEP is an organophosphorus flame-retardant (OPFR) that is used widely in polyurethane foams, furniture, and household products. From these products, TCEP has significant emission into its surrounding environment. Inhalation and dermal absorption are the most common routes of human exposure to OPFRs, which have been measured in human hair, breast milk, and urine. Previous studies of OPFRs have shown their endocrine disrupting actions that have influence on diseases such as cancer. Breast cancer is the second most common cancer among women in the United States, and because of this prevalence, it is imperative to investigate possible causes and treatments for this disease. Due to the endocrine disrupting nature of OPFRs, we are investigating the effects of TCEP on hormone dependent breast cancer cell lines MCF-7 and T-47D. Our study examines the effects of TCEP, alone and in combination with hormones and anti-hormones, on ERα and BRCA1 expression in MCF-7 and T-47D breast cancer cells by utilizing western blot analyses, cellular viability assays, confocal microscopy, apoptosis assays and RT-qPCR analyses. In order to deplete any endogenous steroids or effectors, breast cancer cells were cultured in a medium containing 5% charcoal-stripped fetal bovine serum for six days. Western blot analysis revealed alterations in the expression of ER-alpha after 24 hours of treatment with varying concentrations of TCEP (1µM-2mM). A concentration-dependent decrease of ERα protein levels was noted in the T-47D cell line when compared to the control. BRCA1 protein levels also displayed an altered expression compared to the control through the various concentrations of TCEP. Through our concentration studies, optimum concentrations of TCEP were found to be 100 µM for T-47D and 2mM for MCF-7. For our hormone studies, cell lines were treated with their respective optimum concentration of TCEP as well with combinations of hormones and anti-hormones. After 24-hour treatment of E 2, TCEP, and a combination of E2 with TCEP, a decrease in ERα expression was observed when compared to the control in both MCF-7 and T-47D cell lines. A combination of TCEP with ICI treatment revealed a significant down regulation of ERα expression level compared to the control. The same treatment conditions exhibited an increase with BRCA1 expression compared to the control and these effects were sensitive to the presence of antiestrogens in both cell lines. For cell viability studies, cells were treated for 6 days with TCEP concentrations ranging from 10nm-2µM which displayed an increase (40-50%) in cell proliferation compared to the control in both cell lines. Cytolocalization of ERα remained unaltered with the above treatment conditions. Our studies provide interesting findings about the molecular mechanisms of TECP as a potential endocrine disrupting compound on the steroid receptors and tumor suppressor genes in breast cancer cells. Presentation: No date and time listed

Perfluoroctanesulfonic Acid (PFOS) is a perfluorinated chemical (PFC) and endocrine-disrupting compound (EDC) found in fire-extinguishing foams, food packing, and commonly used household products such as nonstick cookware and cleaning products. PFOS is also an environmental toxicant that has polluted air, soil, and water in past years. Few studies have suggested PFOS may cause endocrine-disrupting effects, therefore it is critical to explore the effects of PFOS on breast cancer cells. This study examined the estrogenic-like effects of PFOS, alone and in combination with hormones and antihormones, on the expression of ERα and BRCA1 in T-47D and MCF-7 breast cancer cell lines by utilizing western blot analyses, cellular viability assays, confocal microscopy, apoptosis assay and RT-qPCR analyses. The cells were cultured with 5% charcoal-stripped fetal bovine serum (FBS) for six days to deplete endogenous steroids or growth factors. In the concentration-dependency study, cells were treated with various concentrations of PFOS (300µM-800µM) for 24 hours. Western blot analysis revealed alterations in the expression of ERα and BRCA1 related with these varying concentrations of PFOS (300 µM-800µM). In comparison to the control, a concentration-dependent decrease of ERα expression levels were seen in both cell lines. A concentration-dependent increase of BRCA1 was seen in both cells. Western blot analysis revealed the optimal concentration of PFOS to be 700 µM in cells, which exhibited the maximal estrogenic-like effect. To further examine the effects of PFOS on breast cancer cells, the optimal concentration (700 µM PFOS) was then used alone and in combination with hormones and anti-hormones in T-47D cells. Treatment with PFOS, E2and the combination of PFOS and E2 for 24 hours showed a significant down-regulation of ERα in T-47D cells when compared to the control. Treatment of PFOS with antiestrogen ICI revealed a significant down-regulation of ERα (approximately 50%) in T-47D cells. Image cytometric analysis with propidium iodide staining was utilized to examine the effects of PFOS on cellular viability in T-47D cells. PFOS alone and in combination with E2 revealed an increase in cellular proliferation compared to the control in T-47D cells and these effects were sensitive to the presence of antiestrogens. RT-qPCR studies revealed a transcriptional expression of ESR1 and BRCA-1 mRNA levels that correlate with the translational data obtained via western blot analyses. Cytolocalization experiments and effects of PFOS with hormones and antihormones on MCF-7 cells studies are in progress. Our studies provide exciting leads to clearly delineate the molecular mechanisms of PFOS as an EDC on the steroid receptors and tumor suppressor gene in breast cancer cells. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Tert-butyl hydroquinone (TBHQ) is an aromatic compound that is commonly used as a preservative in processed food to prevent rancidity and lengthen shelf life. TBHQ is known to act as an antioxidant by protecting cells from radical oxygen species and thus preventing DNA damage. Although previous studies have found TBHQ to cause cancer cell death at high concentrations, they have also contrastingly found TBHQ, when studied in animal models, to enhance carcinogenic effects. However, the effect of TBHQ on breast cancer has not been thoroughly explored. With the prevalence of breast cancer and the wide use of TBHQ in processed food items, it is imperative that we explore their possible relationship. This study examined the effects of TBHQ, alone and in combination with hormones and anti-hormones, on ERα and p53 expression in both MCF-7 and T-47D breast cancer cell lines. To ensure treatment conditions without the presence of endogenous steroids or growth factors, the cells were cultured with a 5% charcoal-stripped fetal bovine serum (FBS) for six days. Western blot analysis revealed alterations in the expression of ERα and p53 protein levels after 24 hours of treatment with varying concentrations of TBHQ (0.005 to 1 mM). A concentration-dependent decrease of ERα protein levels was observed in both cell lines, with a 49% reduction occurring with 100 µM TBHQ as compared to the control. P53 levels portray a continued increase of expression through concentrations of TBHQ (0.005 to 1 mM), found similarly in both cell lines. To gain further insight into possible similarities between BPS and other known effectors of ERα, the optimal concentration of TBHQ (100 μM) was used in combination with hormones and anti-hormones. Down-regulation of ERα protein levels was observed after 24-hour co-treatment of T-47D & MCF-7 cells with a combination of TBHQ and E2. Antiestrogen ICI with TBHQ showed a significant down-regulation as compared to TBHQ alone, and TBHQ with TAM portrayed no significant differences. A similar trend in the effects on p53 expression was depicted in T-47D and MCF-7 cells. Image cytometric analysis with propidium iodide staining was utilized to quantify cell values and viability changes to further portray the effects of TBHQ on T-47D and MCF-7 cellular growth. The viability assay shows a biphasic effect with increasing concentrations of TBHQ, with a maximum decrease in proliferation seen at a concentration of 100 uM TBHQ. TBHQ alone and in combination with E2 and antiestrogens showed a decreased proliferation compared to the control in T-47D cells. However, cytolocalization of ERα upon treatment with estradiol and TBHQ remained unaltered. Our studies offer a unique perspective on the effects of TBHQ on two different breast cancer cell lines, and provide valuable insight for further exploration of the mechanism of action of TBHQ on tumor suppressor gene and steroid receptors.