In 2005, Calvert and Lindberg (Calvert, J. G.; Lindberg, S. E. Atmos. Environ. 2005, 39, 3355–3367) wrote that the use of laboratory-derived rate constants for OH + Hg(0) “...to determine the extent ...of Hg removal by OH in the troposphere will greatly overestimate the importance of Hg removal by this reaction.” The HOHg• intermediate formed from OH + Hg will mostly fall apart in the atmosphere before it can react. By contrast, in laboratory experiments, Calvert and Lindberg expected HOHg• to react with radicals (whose concentrations are much higher than in the atmosphere). Yet, almost all models of oxidation of Hg(0) ignore the argument of Calvert and Lindberg. We present a way for modelers to include the OH + Hg reaction while accounting quantitatively for the dissociation of HOHg•. We use high levels of quantum chemistry to establish the HO–Hg bond energy as 11.0 kcal/mol and calculate the equilibrium constant for OH + Hg = HOHg•. Using the measured rate constant for the association of OH with Hg, we determine the rate constant for HOHg• dissociation. Theory is also used to demonstrate that HOHg• forms stable compounds, HOHgY, with atmospheric radicals (Y = NO2, HOO•, CH3OO•, and BrO). We then present rate constants for use in modeling OH-initiated oxidation of Hg(0). We use this mechanism to model the global oxidation of Hg(0) in the period 2013–2015 using the GEOS-Chem 3D model of atmospheric chemistry. Because of the rapid dissociation of HOHg•, OH accounts for <1% of the global oxidation of Hg(0) to Hg(II), while Br atoms account for 97%.
Fluorescent nanosensors have revolutionized diagnostics and our ability to monitor cellular dynamics. Yet, distinguishing sensor signals from autofluorescence remains a challenge. Here, we merged ...optode-based sensing with near-infrared-emitting ZnGa2O4:Cr3+ persistent luminescence nanoparticles (PLNPs) to create nanocomposites for autofluorescence-free “glow-in-the-dark” sensing. Hydrophobic modification and incorporation of the persistent luminescence nanoparticles into an optode-based nanoparticle core yielded persistent luminescence nanosensors (PLNs) for five analytes (K+, Na+, Ca2+, pH, and O2) via two distinct mechanisms. We demonstrated the viability of the PLNs by quantifying K+ in fetal bovine serum, calibrating the pH PLNs in the same, and ratiometrically monitoring O2 metabolism in cultures of Saccharomyces cerevisiae, all the while overcoming their respective autofluorescence signatures. This highly modular platform allows for facile tuning of the sensing functionality, optical properties, and surface chemistry and promises high signal-to-noise ratios in complex optical environments.
Advanced reduction processes (ARPs) that generate hydrated electrons (eaq –; e.g., UV-sulfite) have emerged as a promising remediation technology for recalcitrant water contaminants, including per- ...and polyfluoroalkyl substances (PFASs). The effectiveness of ARPs in different natural water matrices is determined, in large part, by the presence of non-target water constituents that act to quench eaq – or shield incoming UV photons from the applied photosensitizer. This study examined the pH-dependent quenching of eaq – by ubiquitous dissolved carbonate species (H2CO3*, HCO3 –, and CO3 2–) and quantified the relative importance of carbonate species to other abundant quenching agents (e.g., H2O, H+, HSO3 –, and O2(aq)) during ARP applications. Analysis of laser flash photolysis kinetic data in relation to pH-dependent carbonate acid–base speciation yields species-specific bimolecular rate constants for eaq – quenching by H2CO3*, HCO3 –, and CO3 2– ( k H 2 C O 3 * = 2.23 ± 0.42 × 109 M–1 s–1, k H C O 3 − = 2.18 ± 0.73 × 106 M–1 s–1, and k C O 3 2 − = 1.05 ± 0.61 × 105 M–1 s–1), with quenching dominated by H2CO3* (which includes both CO2(aq) and H2CO3) at moderately alkaline pH conditions despite it being the minor species. Attempts to apply previously reported rate constants for eaq – quenching by CO2(aq), measured in acidic solutions equilibrated with CO2(g), overpredict quenching observed in this study at higher pH conditions typical of ARP applications. Moreover, kinetic simulations reveal that pH-dependent trends reported for UV-sulfite ARPs that have often been attributed to eaq – quenching by varying H+ can instead be ascribed to variable acid–base speciation of dissolved carbonate and the sulfite sensitizer.
Physical activity is associated with decreased breast cancer risk. The underlying biological mechanisms could include the reduction of the local inflammation in the breast tissue. We conducted a ...cross-sectional study to assess the association between the physical activity and the protein expression levels of eleven mediators of inflammation in normal breast tissue of 164 women having breast cancer. Information on total physical activity (household, occupational and recreational) performed during a one-year period was collected using a questionnaire. Normal breast tissue was obtained from mastectomy blocks distant from the tumor. The expression of the mediators of inflammation in normal breast tissue was visually evaluated by immunohistochemistry. Multivariate linear regression analyses were used to assess the prevalence ratios (PR) and 95% confidence intervals (CI) for higher protein expression levels of the mediators of inflammation in normal breast tissue across quartiles of physical activity. Higher total physical activity was associated with lower expression levels of the pro-inflammatory mediator TNF-α in normal breast epithelial tissue among all (PR=0.64, 95% CI=0.44–0.93 for the fourth quartile; Ptrend=0.013), premenopausal (PR=0.61, 95% CI=0.41–0.91 for the fourth quartile; Ptrend=0.014) and postmenopausal women (PR=0.45, 95% CI=0.21–0.96 for the fourth quartile; Ptrend=0.022). Conversely, higher total physical activity was associated with higher expression levels of the anti-inflammatory mediator IL-10 in normal breast epithelial tissue among all (PR=1.66, 95% CI=0.97–2.85 for the fourth quartile; Ptrend=0.071) and postmenopausal women (PR=4.69, 95% CI=1.26–17.43 for the fourth quartile; Ptrend=0.010). Our findings suggest a beneficial effect of physical activity on the local inflammatory profile in the breast tissue.
Increased levels of pro-inflammatory markers and decreased levels of anti-inflammatory markers in the breast tissue can result in local inflammation. We aimed to investigate whether local ...inflammation in the breast tissue is associated with age-related lobular involution, a process inversely related to breast cancer risk. Levels of eleven pro- and anti-inflammatory markers were assessed by immunohistochemistry in normal breast tissue obtained from 164 pre- and postmenopausal breast cancer patients. Involution status of the breast (degree of lobular involution and the predominant lobule type) was microscopically assessed in normal breast tissue on hematoxylin-eosin stained mastectomy slides. Multivariate generalized linear models were used to assess the associations. In age-adjusted analyses, higher levels of pro-inflammatory markers IL-6, TNF-α, CRP, COX-2, leptin, SAA1 and IL-8; and anti-inflammatory marker IL-10, were inversely associated with the prevalence of complete lobular involution (all P≤0.04). Higher levels of the pro-inflammatory marker COX-2 were also associated with lower prevalence of predominant type 1/no type 3 lobules in the breast, an indicator of complete involution, in age-adjusted analysis (P = 0.017). Higher tissue levels of inflammatory markers, mainly the pro-inflammatory ones, are associated with less involuted breasts and may consequently be associated with an increased risk of developing breast cancer.
Physical activity may protect against breast cancer by modulating breast tissue composition. We evaluated the association of physical activity with two visual assessments of breast tissue ...composition-percentage of mammographic density (a radiologic observation) and age-related lobular involution (a histologic assessment).
Among 164 premenopausal and postmenopausal women with breast cancer, physical activity (household, occupational, and recreational) performed during the year preceding the diagnosis was evaluated using a validated questionnaire. Percentage of mammographic density was assessed in the contralateral breast by a computer-assisted method. Age-related lobular involution was assessed in normal breast tissue on H&E-stained slides. Multivariate generalized linear models were used to assess associations by quartiles of physical activity.
Overall, we observed no significant association between total physical activity and percentage of mammographic density or degree of lobular involution. However, occupational physical activity was significantly positively associated with the predominant type I/no type III lobules among premenopausal women (last quartile: prevalence ratio PR, 5.92; P(trend )= 0.04). Although total physical activity was positively associated with the predominant type I/no type III lobules among premenopausal women (last quartile: PR, 2.61; P(trend) = 0.08), an inverse association was observed among postmenopausal women (last quartile: PR, 0.44; P(trend) = 0.01). Higher levels of household physical activity were significantly associated with higher prevalence of lower mammographic density and complete involution among postmenopausal women (last quartile: PR, 1.21; P(trend) = 0.01).
Physical activity may be associated with less dense and more involuted breasts. Physical activity's effect on mammographic density or age-related lobular involution may mediate, in part, its protective effect against breast cancer.
Inflammatory markers may be associated with breast cancer risk. We assessed the association between expression levels of proinflammatory (interleukin 6, tumor necrosis factor-α, C-reactive protein, ...cyclooxygenase 2, leptin, serum amyloid A1, interleukin 8, and signal transducer and activator of transcription 3) and anti-inflammatory markers (transforming growth factor-β, interleukin 10, and lactoferrin) in normal breast tissue with mammographic density, a strong breast cancer risk indicator, among 163 breast cancer patients.
The expression of inflammatory markers was visually evaluated on immunohistochemistry stained slides. The percent mammographic density (PMD) was estimated by a computer-assisted method in the contralateral cancer-free breast. We used generalized linear models to estimate means of PMD by median expression levels of the inflammatory markers while adjusting for age and waist circumference.
Higher expression levels (above median) of the proinflammatory marker interleukin 6 were associated with higher PMD among all women (24.1% vs 18.5%, P = 0.007). Similarly, higher expression levels (above median) of the proinflammatory markers (interleukin 6, tumor necrosis factor-α, C-reactive protein, and interleukin 8) were associated with higher PMD among premenopausal women (absolute difference in the PMD of 8.8% P = 0.006, 7.7% P = 0.022, 6.7% P = 0.037, and 16.5% P = 0.032, respectively). Higher expression levels (above median) of the anti-inflammatory marker transforming growth factor-β were associated with lower PMD among all (18.8% vs 24.3%, P = 0.005) and postmenopausal women (14.5% vs 20.7%, P = 0.013).
Our results provide support for the hypothesized role of inflammatory markers in breast carcinogenesis through their effects on mammographic density. Inflammatory markers could be targeted in future breast cancer prevention interventions.
Chronic inflammation may be a causative factor in breast cancer. One possible underlying mechanism is the generation of oxidative stress, which may favor tumorigenic processes. Antioxidant ...consumption may, therefore, help reduce tissue inflammation levels. However, few studies have explored this relation in breast tissue. We aimed to evaluate correlations between antioxidant (vitamin A/retinol, vitamin C, vitamin E, β-carotene, α-carotene, lycopene, lutein/zeaxanthin, β-cryptoxanthin, selenium, and zinc) intakes and protein expression levels of interleukin (IL)-6, tumor necrosis factor-α, C-reactive protein, cyclooxygenase-2, leptin, serum amyloid A1, signal transducer and activator of transcription 3, IL-8, IL-10, lactoferrin, and transforming growth factor-β measured in the normal breast tissue of 160 women diagnosed with breast cancer. Antioxidant intakes were collected using a self-administered food frequency questionnaire. Inflammation marker expression was assessed by immunohistochemistry. Correlations between antioxidant intakes and inflammatory marker expression were evaluated using Spearman’s partial correlation coefficients (r) for all women and for premenopausal and postmenopausal women separately. After Bonferroni correction, negative correlations were observed between dietary β-tocopherol and IL-10 expression in all women combined (r = −0.26, P = .003) and among postmenopausal women (r = −0.39, P = .003). For all women, a negative correlation was found between total zinc intakes and IL-10 (r = −0.26, P = .002). Among postmenopausal women, dietary selenium intake was negatively correlated with the expression of lactoferrin (r = −0.39, P = .003). No associations were observed in premenopausal women. Our findings suggest that consumption of specific antioxidants, including β-tocopherol, zinc, and selenium, may act on the breast tissue through mechanisms affecting the expression of some inflammation markers, particularly among postmenopausal women.
Testing for HER2/neu in breast cancer at the time of primary diagnosis is now the standard of care. Accurate and standardized testing methods are of prime importance to ensure the proper ...classification of the patient's HER2/neu status. A meeting of pathologists from across Canada was convened to update the Canadian HER2/neu testing guidelines. This National HER2/neu Testing Committee reviewed the recently published American Society of Clinical Oncology/ College of American Pathologists (ASCO/CAP) guidelines for HER2/neu testing in breast cancer. The updated Canadian HER2/neu testing guidelines are based primarily on the ASCO/CAP guidelines, with some modifications. It is anticipated that widespread adoption of these guidelines will further improve the accuracy of HER2/neu testing in Canada.
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