The endeavor to study desensitization in kidney transplantation has not been matched by an effort to investigate strategies to prevent sensitization. In this study ( NCT 02437422), we investigated the safety, impact on sensitization, and pharmacokinetics of SANGUINATE ( SG ), a hemoglobin‐based oxygen carrier, as a potential alternative to packed red blood cells ( PRBC ) in transplant candidates with end‐stage renal disease ( ESRD ). Ten ESRD subjects meeting inclusion/exclusion (I/E) criteria were planned to receive three weekly infusions of SG (320 mg/kg). The study was stopped after five subjects were enrolled, and their data were analyzed after completing a follow‐up period of 90 days. Two subjects had elevated troponin I levels in setting of SG infusion, one of which was interpreted as a non‐ ST elevation myocardial infarction. All other adverse events were transient. SG pharmacokinetic analysis showed mean (SD) C max , T max , AUC , and half‐life of 4.39 (0.69) mg/mL, 2.42 (0.91) hours, 171.86 (52.35) mg h/mL, and 40.60 (11.96) hours, respectively. None of the subjects developed new anti‐ HLA antibodies following SG infusion and throughout the study period. In conclusion, SG is a potential alternative to PRBC s in ESRD patients considered for kidney transplantation as it was not associated with humoral sensitization. Larger studies in highly sensitized patients are required to further evaluate for potential safety signals.

This study investigated the hypothesis that acetaminophen at pharmacologically relevant concentrations may act as a protector against peroxynitrite toxicity.  Our results showed that acetaminophen inhibited SIN-1 (a peroxynitrite generator)-induced DNA cleavage in a concentration-dependent manner in an in vitro model. With bicarbonate-enhanced luminol-dependent chemiluminometry, we further showed a nearly complete blockage of peroxynitrite-derived chemiluminescence by acetaminophen at 25‒100 µM with minimal effects on SIN-1-mediated oxygen consumption, suggesting acetaminophen as a potent scavenger of peroxynitrite. Electron spin resonance spectrometry in combination with 5,5-dimethyl-1-pyrroline N -oxide (DMPO)-spin-trapping supported the ability of acetaminophen at high concentrations to diminish the production of a free radical species (likely hydroxyl radical) from SIN-1. Fenton chemistry-based DMPO-spin trapping further demonstrated the hydroxyl radical-scavenging capacity of acetaminophen. Collectively, the results of this study for the first time revealed the potential of acetaminophen to protect against peroxyitrite toxicity, which may have important implications in neuroprotection associated with the use of this popular analgesic and antipyretic drug.

BACKGROUND:Obstructive sleep apnea (OSA) is a common disorder resulting in a myriad of adverse vascular risks, including altered inflammatory/anti-inflammatory adipokine balance. Recent studies are yet to agree on how this balance responds to the OSA severity. As it is customary in these studies to obtain a single blood sample in participants after completion of the nocturnal polysomnogram (PSG), we hypothesized that these adipokines' early ultradian pulsatility might contribute to the reported contradictory results.METHODS:Fasting serum leptin and adiponectin were measured every 15 minutes for one hour in the morning after the diagnostic PSG for 13 adults recruited consecutively from the Salem VAMC Sleep Clinic between September 2006 and October 2007.RESULTS:No differences in the timed paired samples of leptin (P = 0.30) and adiponectin (P = 0.28) were found in OSA participants (mean apnea-hypopnea index 21.1).CONCLUSION:Customary protocol of obtaining a single blood sample for leptin and adiponectin after nocturnal PSG seems appropriate.

Beta-lapachone (beta-Lp) derived from the Lapacho tree is a potentially novel anticancer agent currently under clinical trials. Previous studies suggested that redox activation of beta-Lp catalyzed by NAD(P)H:quinone oxidoreductase 1 (NQO1) accounted for its killing of cancer cells. However, the exact mechanisms of this effect remain largely unknown. Using chemiluminescence and electron paramagnetic resonance (EPR) spin-trapping techniques, this study for the first time demonstrated the real-time formation of ROS in the redox activation of beta-lapachone from cancer cells mediated by mitochondria and NQO1 in melanoma B16–F10 and hepatocellular carcinoma HepG2 cancer cells. ES936, a highly selective NQO1 inhibitor, and rotenone, a selective inhibitor of mitochondrial electron transport chain (METC) complex I were found to significantly block beta-Lp meditated redox activation in B16–F10 cells. In HepG2 cells ES936 inhibited beta-Lp-mediated oxygen radical formation by ~80% while rotenone exerted no significant effect. These results revealed the differential contribution of METC and NQO1 to beta-lapachone-induced ROS formation and cancer cell killing. In melanoma B16–F10 cells that do not express high NQO1 activity, both NOQ1 and METC play a critical role in beta-Lp redox activation. In contrast, in hepatocellular carcinoma HepG2 cells expressing extremely high NQO1 activity, redox activation of beta-Lp is primarily mediated by NQO1 (METC plays a minor role). These findings will contribute to our understanding of how cancer cells are selectively killed by beta-lapachone and increase our ability to devise strategies to enhance the anticancer efficacy of this potentially novel drug while minimizing its possible adverse effects on normal cells.

Paraoxonase (PON) refers to a family of three enzymes, namely PON1, PON2, and PON3. PON1 and PON3 are found in circulation bound to high-density lipoprotein, whereas PON2 is an intracellular protein. PON1 was first discovered as an enzyme to hydrolyze the organophosphate pesticide paraoxon, an activity that both PON2 and PON3 lack. All three PON enzymes are able to degrade oxidized lipids and protect against oxidative stress. PON enzymes also act to suppress inflammation. Animal studies show a critical role for PON enzymes, especially PON1 in protecting against cardiovascular diseases and related disorders, including diabetes and metabolic syndrome. In line with the findings in experimental animals, accumulating evidence from clinical research also indicates that PON enzymes function as potential protectors in human cardiovascular diseases and related disorders. Identification of PON enzymes as important players in cardiovascular health will facilitate the development of novel preventive and therapeutic modalities targeting PON enzymes to combat cardiovascular diseases and related disorders, which collectively constitute the chief contributors to the global burden of disease. This review describes the biochemical properties and molecular regulation of PON and summarizes the major recent findings on the functions of PON in protecting against cardiovascular diseases and related disorders.

Objective . To evaluate the potential protective effects of extracts from Fructus rhodomyrti (FR) against oxidative DNA damage using a cellular system and the antioxidant ability on potassium bromate- (KBrO 3 -) mediated oxidative stress in rats. Methods . The effects of FR on DNA damage induced by hydrogen peroxide (H 2 O 2 ) were evaluated by comet assay in primary spleen lymphocytes cultures. The effects of FR on the activities of SOD, CAT, and GPx and the levels of GSH, hydroperoxides, and 8-OHdG were determined in the plasma and tissues of rats treated with KBrO 3 . Results . FR was shown to effectively protect against DNA damage induced by H 2 O 2 in vitro , and the maximum protective effect was observed when FR was diluted 20 times. Endogenous antioxidant status, namely, the activities of SOD, CAT, and GPx and the levels of GSH were significantly decreased in the plasma, the liver, and the kidney of the KBrO 3 -treated rats, while the pretreatment of FR prevented the decreases of these parameters. In addition, the pretreatment of FR was also able to prevent KBrO 3 -induced increases in the levels of hydroperoxides and 8-OHdG in the plasma, the liver, and the kidney in rats. Conclusions . Our findings suggested that FR might act as a chemopreventive agent with antioxidant properties offering effective protection against oxidative DNA damage in a concentration-dependent manner in vitro and in vivo .

As in obstructive sleep apnea (OSA), the chronic cycles of hypoxia and reoxygenation are thought to be conducive of oxidative stress (OS) with generation of reactive oxygen species, identifying effective mechanisms of protection against oxidant-mediated tissue damage becomes of outmost importance. Leptin’s role had been recently extended into that of participant to OS; while its exact role in this process is yet to be defined, elevated leptin levels correlate significantly with several indices of OSA disease severity such as nocturnal hypoxemia, possibly acting as a counteractive mechanism against the chronic intermittent hypoxia-related OS and serving as a marker of future risk of atherosclerotic disease. We therefore investigated leptin’s antioxidant mechanism on superoxide (O 2 −• ) anions using spectrophotometry and electron paramagnetic resonance (EPR).

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity, whereas the underlying mechanism is still eluding, the thought participants are chronic intermittent hypoxia with consequent increase in the reactive oxygen species, leading to endothelial cell damage and dysfunction in these patients. As the hydroxyl radical (·OH) mediates the vascular smooth muscle relaxation, identification of its scavengers might reveal sentinel markers of decreased vascular responsiveness and worse long-term comorbid outcome. We therefore assessed leptin’s scavenger effect on ∙OH using the electronic paramagnetic resonance (EPR) method.

Mesalamine (5-aminosalicylic acid, 5-ASA) is known to be the first-line medication for treatment of patients with ulcerative colitis. Studies have demonstrated that ulcerative colitis patients treated with 5-ASA have an overall decrease in the risk of developing colorectal carcinoma. However, the mechanisms underlying 5-ASA-mediated anti-inflammatory and anti-cancer effects are yet to be elucidated. Because peroxynitrite has been critically involved in inflammatory stress and carcinogenesis, this study was undertaken to investigate the effects of 5-ASA in peroxynitrite-induced DNA strand breaks, an important event leading to peroxynitrite-elicited cytotoxicity. Incubation of φX-174 plasmid DNA with the peroxynitrite generator 3-morpholinosydnonimine (SIN-1) led to the formation of both single- and double-stranded DNA breaks in a concentration-dependent manner. The presence of 5-ASA at 0.1 and 1.0 mM was found to significantly inhibit SIN-1-induced DNA strand breaks in a concentration-dependent manner. The consumption of oxygen induced by SIN-1 was found to not be affected by 5-ASA at 0.1-50 mM, indicating that 5-ASA at these concentrations is not involved in the auto-oxidation of SIN-1 to form peroxynitrite. It is observed that 5-ASA at 0.1-1 mM showed considerable inhibition of peroxynitrite-mediated luminol chemiluminescence in a dose-dependent fashion, suggesting that 5-ASA is able to directly scavenge the peroxynitrite. Electron paramagnetic resonance (EPR) spectroscopy in combination with spin-trapping experiments, using 5,5-dimethylpyrroline-N-oxide (DMPO) as spin trap resulting in the formation of DMPO-hydroxyl radical adduct from peroxynitrite, and 5-ASA only at higher concentration (1 mM) inhibited the hydroxyl radical adduct while shifting EPR spectra, indicating that 5-ASA at higher concentrations may generate a more stable free radical species rather than acting purely as a hydroxyl radical scavenger. Taken together, these studies demonstrate for the first time that 5-ASA can potently inhibit peroxynitrite-mediated DNA strand breakage, scavenge peroxynitrite, and affect peroxynitrite-mediated radical formation, which may be responsible, at least partially, for its anti-inflammatory and anti-cancer effects.

Genistein, a soy isoflavone, has received wide attention for its potential to improve vascular function, but the mechanism of this effect is unclear. Here, we report that genistein at physiological concentrations (0.1 μM-5 μM) significantly inhibited TNF-α-induced adhesion of monocytes to human umbilical vein endothelial cells, a key event in the pathogenesis of atherosclerosis. Genistein also significantly suppressed TNF-α-induced production of adhesion molecules and chemokines such as sICAM-1, sVCAM-1, sE-Selectin, MCP-1 and IL-8, which play key role in the firm adhesion of monocytes to activated endothelial cells (ECs). Genistein at physiologically relevant concentrations didn't significantly induce antioxidant enzyme activities or scavenge free radicals. Further, blocking the estrogen receptors (ERs) in ECs didn't alter the preventive effect of genistein on endothelial inflammation. However, inhibition of protein kinase A (PKA) significantly attenuated the inhibitory effects of genistein on TNF-α-induced monocyte adhesion to ECs as well as the production of MCP-1 and IL-8. In animal study, dietary genistein significantly suppressed TNF-α-induced increase in circulating chemokines and adhesion molecules in C57BL/6 mice. Genistein treatment also reduced VCAM-1 and monocytes-derived F4/80-positive macrophages in the aorta of TNF-α-treated mice. In conclusion, genistein protects against TNF-α-induced vascular endothelial inflammation both in vitro and in vivo models. This anti-inflammatory effect of genistein is independent of the ER-mediated signaling machinery or antioxidant activity, but mediated via the PKA signaling pathway.