ROS generation can be from the mitochondria and a variety of enzymes including the xanthine- and NADPH-oxidases,5,6 and the cytochrome P450s.7 These enzymes specialize in the professional generation of ROS or produce these toxic metabolites as an inadvertent consequence of their biochemical activity. In addition to the effects of the endogenous sex hormone, exogenous hormone therapy promotes antioxidants and anti-inflammatory processes via the enhancement of the HO enzymes. In summary, we can conclude that the HO system is involved in testosterone-mediated mechanisms in both young and aged animals. Exercise modalities included elliptical, stationary bike, treadmill or outdoor walking, running, and load carriage (weighted backpack ~30% of body mass). Energy intake was adjusted when necessary to maintain body weight within ±2% during the balance phase. Participants provided written informed consent and completed the study between April 2016 and September 2017. This study was approved by the Pennington Biomedical Research Center (PBRC; Baton Rouge, LA) Institutional Review Board and the Human Research Protection Office of the US Army Medical Research and Development Command. Rested/fasting blood samples were collected on study days 14 (balance) and 42 (deficit). During deficit, participants completed multiple exercise sessions on a cycle ergometer to maintain the increase in total daily energy expenditure prescribed during this phase of the study. Fasted blood samples were collected on study days 14 (balance) and 42 (deficit) after an overnight fast. During deficit, daily energy expenditure was increased by 3–4 sessions of varied-intensity (40%–85% of predetermined V̇O2peak) aerobic exercise per day. Diet and physical activity adherence during balance were verified by research dietitians, accelerometer data, and daily measurements of metabolic body weight on a calibrated digital scale (GSE Inc. model 450; GSE Scale Systems, Novi, MI) after an overnight fast and morning void. During balance, participants were free-living and maintained their normal physical activity levels. The FeO2– intermediate is excluded, based on the formic acid 18O labeling results. The identity of the mono-oxygenated aldehyde productis unknown; like the 19-oic acid, it appears to be an end product(Figure S8, Supporting Information). The 19-oic acid had been reported to be presentin hog follicles27 but had not actuallybeen demonstrated to be an aromatase product. The diazo reagent (2) had reacted with the carboxylicacid group of 19-oic androstenedione (5b) to afford theester (6b) and also reacted with the phenol moiety ofestrone (4A) to furnish a phenolic ether (Figure S11, Supporting Information). From the knowledge of this novel 19-oic acid aromatase product, aCompound I mechanism suggests a distribution of products arising froma 1β-hydrogen atom abstraction or a 19-hydrogen atom abstractionof the 19-oxo androgen substrate to yield either the estrogen or carboxylicacid, respectively, in the incubation with P450 19A1. One product is the 19-CO2H (19-oic acid) derivative,and this assignment was confirmed by coincident chromatography withan authentic sample in the case of androstenedione 19-oic acid, aswell as by MS analysis of the propylpyridine ester derivatives (6a and 6b, Figure 3 andFigure S6 of Supporting Information). However, testosterone-treated rats possessed lower values compared to the untreated counterparts. (B) The effects of aging, surgical castration, and testosterone replacement therapy on the cardiac cyclic guanosine monophosphate level (cGMP; expressed as nmol/mg protein). (A) The effects of aging, surgical castration, and testosterone replacement therapy on the ratio of the reduced/oxidized glutathione content (GSH + GSSG; expressed as nmol/mg protein). The highest OBS group exhibited a 38% reduction in the risk of testosterone deficiency compared to the lowest OBS group. This study further investigated the relationship between lifestyle OBS/dietary OBS and testosterone deficiency. Total testosterone levels in serum were measured using isotope dilution liquid chromatography tandem mass spectrometry (ID-LC–MS/MS). Given the increased exposure to secondhand smoke, this study measured smoking utilized serum cotinine levels, a metabolite of cigarette smoke. In addition, participants with missing data on PIR (497), educational background (1), energy intake (240), females (2,961), and sleep disorder (0) were also excluded. Then, participants with missing data on testosterone level (77) were excluded. Second, participants with missing data on physical activities (1,351), alcohol consumption (16,062), serum cotinine (352), and body mass index (BMI) (17) were excluded. These cycles were selected because they contain complete data necessary for calculating the OBS as well as testosterone measurements. This study analyzed data from three NHANES survey cycles (2011–2012, 2013–2014, and 2015–2016).
