Oxidative injury and survival during endotoxemia

Antioxidant Activity, Metabolism, and Bioavailability of Polyphenols in the Diet of Animals

As the world’s population grows, so does the need for more and more animal feed. In 2006, the EU banned the use of antibiotics and other chemicals in order to reduce chemical residues in food consumed by humans. It is well known that oxidative stress and inflammatory processes must be combated to achieve higher productivity. The adverse effects of the use of pharmaceuticals and other synthetic compounds on animal health and product quality and safety have increased interest in phytocompounds. With the use of plant polyphenols in animal nutrition, they are gaining more attention as a supplement to animal feed. Livestock feeding based on a sustainable, environmentally friendly approach (clean, safe, and green agriculture) would also be a win–win for farmers and society. There is an increasing interest in producing healthier products of animal origin with a higher ratio of polyunsaturated fatty acids (PUFAs) to saturated fatty acids by modulating animal nutrition. Secondary plant metabolites (polyphenols) are essential chemical compounds for plant physiology as they are involved in various functions such as growth, pigmentation, and resistance to pathogenic organisms. Polyphenols are exogenous antioxidants that act as one of the first lines of cell defense. Therefore, the discoveries on the intracellular antioxidant activity of polyphenols as a plant supplement have contributed significantly to the improvement of antioxidant activity, as polyphenols prevent oxidative stress damage and eliminate excessively produced free radicals. To achieve animal welfare, reduce stress and the need for medicines, and increase the quality of food of animal origin, the addition of polyphenols to research and breeding can be practised in part with a free-choice approach to animal nutrition.

Genistein attenuates neuroinflammation and oxidative stress and improves cognitive impairment in a rat model of sepsis-associated encephalopathy: potential role of the Nrf2 signaling pathway

Oxidative stress and inflammation seem to be the main factors responsible for cognitive impairment in sepsis. Genistein (GEN) is claimed to exert many beneficial effects on health, however, its possible effects on brain sepsis remains unclear. Here, we assess the influence and underling mechanisms of GEN on cognitive impairments in cecal ligation and puncture (CLP)-induced septic model. Rats were randomly divided into Sham, Sham + GEN, CLP, CLP + GEN gropus. Rats were treated with GEN (15 mg/kg at 0 and 12 h after CLP, i.p). Twenty-four hours after CLP, protein levels of cytokines, NF-kB and Nrf2, myeloperoxidase (MPO) activity, oxidative damage to lipids and proteins, the activities of antioxidant enzymes and the expression of Nrf2-target genes were evaluated in the hippocampus. At 10 days after sepsis induction, behavioral tests were conducted to evaluate cognitive impairment. The results indicate that GEN can enhance survival percentage and improve cognitive function. Genistein administration significantly reduced TNF-α and IL-1β levels, MPO activity and protein level of NF-kB in the hippocampus of septic rats. Genistein also decreased the levels of oxidative stress parameters (MDA and protein carbonyls) and elevated the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in septic rats. Furthermore, nuclear Nrf2 and the expression of HO-1 and NQO-1 were also elevated by GEN treatment. These findings suggest that GEN improves cognition impairment in septic rats via decreasing inflammatory responses and oxidative stress, and activation of the Nrf2 pathway.

Changes in Biomarkers of Redox Status in Saliva of Pigs after an Experimental Sepsis Induction

Saliva from pigs is gaining attention as an easy sample to obtain, being a source of biomarkers that can provide information on animal health and welfare. This study aimed to evaluate the changes that can occur in salivary biomarkers of the redox status of pigs with an experimentally induced sepsis. For that, the cupric reducing antioxidant capacity (CUPRAC), ferric reducing ability of saliva (FRAS), Trolox equivalent antioxidant capacity (TEAC), advanced oxidation protein products (AOPP), ferrous oxidation-xylenol orange (FOX), peroxide activity (POX-Act), and reactive oxygen-derived compounds (d-ROMs) were measured in the saliva of pigs with experimentally induced sepsis by endotoxin lipopolysaccharide (LPS), non-septic inflammation induced by turpentine, and in healthy individuals before and after 3 h, 6 h, 24 h, and 48 h. AOPP, POX-Act, and d-ROMs in the sepsis group were higher than in the control from 3 h to 24 h after the inoculation. CUPRAC, FRAS, and TEAC were higher in sepsis than the control group at 24 h. These changes were of higher magnitude than those that occurred in the turpentine group. In conclusion, our findings reveal that sepsis produces changes in salivary biomarkers of redox status, which opens the possibility of using them as potential biomarkers in this species.

The effect of epidermal growth factor on performance and oxidative stress in piglets challenged with enterotoxigenic Escherichia coli K88

This study evaluated the efficacy of epidermal growth factor (EGF) in piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). A total of 28 piglets were assigned to the following dietary treatments for 14 d: negative control (NC) (basal diet containing supernatant without EGF), PC (NC + 2.5 g antibiotic·kg−1 feed), EGF120 [basal diet + supernatant with 120 μg EGF·kg−1 body weight (BW)·d−1], and EGF180 (basal diet + supernatant with 180 μg EGF·kg−1 BW·d−1). After a 6 d acclimation period, each pig was gavaged with 6 mL (2.4 × 1013 cfu·mL−1) of ETEC on the morning of day 7. Overall, piglets fed the EGF and PC diets tended to have higher gain to feed ratio than those fed the NC diet (P = 0.063). Pigs fed EGF diets had lower rectal temperature than those fed the NC diet at 6 h after challenge (P < 0.05). Serum and ileal malondialdehyde concentrations were higher in piglets fed the NC diet compared with those fed EGF and PC diets on days 6 and 7 after challenge, respectively (P < 0.05). In conclusion, EGF has the potential to reduce oxidative stress and body temperature elevation in piglets exposed to ETEC while supporting better feed efficiency.

Maternal Urinary Metal and Metalloid Concentrations in Association with Oxidative Stress Biomarkers

Metal exposure has been associated with a wide range of adverse birth outcomes and oxidative stress is a leading hypothesis of the mechanism of action of metal toxicity. We assessed the relationship between maternal exposure to essential and non-essential metals and metalloids in pregnancy and oxidative stress markers, and sought to identify windows of vulnerability and effect modification by fetal sex. In our analysis of 215 women from the PROTECT birth cohort study, we measured 14 essential and non-essential metals in urine samples at three time points during pregnancy. The oxidative stress marker 8-iso-prostaglandin F2α (8-iso-PGF2α) and its metabolite 2,3-dinor-5,6-dihydro-15-15-F2t-IsoP, as well as prostaglandin F2α (PGF2α), were also measured in the same urine samples. Using linear mixed models, we examined the main effects of metals on markers of oxidative stress as well as the visit-specific and fetal sex-specific effects. After adjustment for covariates, we found that a few urinary metal concentrations, most notably cesium (Cs) and copper (Cu), were associated with higher 8-iso-PGF2α with effect estimates ranging from 7.3 to 14.9% for each interquartile range, increase in the metal concentration. The effect estimates were generally in the same direction at the three visits and a few were significant only among women carrying a male fetus. Our data show that higher urinary metal concentrations were associated with elevated biomarkers of oxidative stress. Our results also indicate a potential vulnerability of women carrying a male fetus.

Effect of Topical Prostaglandin F2α Analogs on Selected Oxidative Stress Parameters in the Tear Film

Background and Objectives: Topically administered antiglaucoma medications, especially those containing benzalkonium chloride (BAC), may cause local adverse effects and compromise ocular surface. The aim of the study was to assess the effect of topical prostaglandin F2α analogs (PGAs): preservative-free latanoprost, BAC-preserved latanoprost, preservative-free tafluprost, and BAC-preserved bimatoprost, on selected oxidative stress parameters in the tear film. Materials and Methods: The patients were divided into five groups: group C (n = 25) control group—subjects who did not use topical antiglaucoma medications, group L (n = 22)—patients using topical preservative-free latanoprost, group L+BAC (n = 25)—patients using topical BAC-preserved latanoprost, group T (n = 19)—patients using topical preservative-free tafluprost, and group B+BAC (n = 17)—patients using topical BAC-preserved bimatoprost. The oxidative stress markers in the tear film samples were evaluated: total protein (TP) concentration, advanced oxidation protein products (AOPP) content, total sulfhydryl (-SH) groups content, the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as Total Oxidant Status (TOS), Total Antioxidant Response (TAR), and Oxidative Stress Index (OSI). Results: The TP concentrations in the groups L, L+BAC, and B+BAC were statistically significantly higher in comparison with group C. The SOD and CAT activities in the groups L+BAC and B+BAC were statistically significantly higher when compared to group C. As compared to group C, AOPP and TOS were statistically significantly higher in all the study groups. OSI was found to be statistically significantly higher in the groups L+BAC, T, and B+BAC in comparison with group C. Conclusion: Use of topical PGAs by the patients with ocular hypertension or primary open-angle glaucoma is associated with increased oxidative stress in the tear film which is additionally exacerbated by the presence of BAC in the formulation.

Propofol post-conditioning after temporary clipping reverses oxidative stress in aneurysm surgery

PURPOSE

Animal studies have demonstrated that propofol post-conditioning produces long-term neuroprotection in focal cerebral ischemia-reperfusion injury. However, whether propofol post-conditioning provides neuroprotection in human beings has never been explored. The aim of this study was to evaluate the role of propofol post-conditioning on oxidative stress and post-operative cognitive function following aneurysm clipping.

MATERIALS AND METHODS

Sixty patients undergoing intracranial aneurysm clipping were randomized into a propofol post-conditioning group or a sevoflurane group. Sevoflurane (0.5-2%) was used for maintenance anesthesia in both groups. In the propofol post-conditioning group, the inhaled concentration of sevoflurane was reduced after temporary clip removal to keep the bispectral index (BIS) value between 40 and 60, and propofol (Cp 1.2 µg/mL) was subsequently started. Blood samples were drawn at six time points: before induction, immediately after clip removal, at the end of the operation, 24-h post-surgery, 3 days post-surgery, and 7 days post-surgery. Oxidative stress and cognitive function were measured.

RESULTS

Between the conclusion of the operation to 7 days after surgery, propofol post-conditioning decreased the serum concentration of •OH and 8-isoprostane and increased γ-tocopherol and SOD. Reduced micronuclei and nucleoplasmic bridges were observed in the propofol post-conditioning group. Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores were improved by propofol post-conditioning compared to the group that received no propofol.

CONCLUSIONS

Together, our data suggest that propofol post-conditioning (Cp 1.2 µg/mL) may protect the brain from oxidative stress injury up to 7 days post-surgery after temporary parent artery clipping. Furthermore, the neuroprotection induced by propofol post-conditioning may contribute to improvement in cognitive function.

Ozone exposure effect on systemic prostaglandin F2α in rat plasma and urine may not reveal pulmonary damage through inflammation

The acute ozone induced lung injury model has been widely used to explore injury and repair processes induced by oxidant overload. The current study evaluated acute ozone exposure effects on prostaglandin F_2α (PGF_2α) in male Fischer rat plasma and urine with the hypothesis that ozone may induce an inflammatory response in the body that can be measured by the induction of PGF_2α. That might then lead to the identification of potential marker for acute lung injury through systemic inflammation. The time and dose-dependent effects of ozone exposure on the plasma and urinary levels of a major PGF_2α metabolite15-keto-dihydro-PGF_2α were determined using a radioimmunoassay. No statistically significant differences in the PGF_2α metabolite were found between the control and the experimental groups at either ozone exposure dose (2ppm and 5ppm) or any time point (2h, 7h and 16h) post exposure for plasma and at 7 different post exposure time points (between 2 and 80h) for urine. It is concluded that acute ozone exposure does not cause changes in plasma and urinary PGF_2α, and therefore their measurement in plasma and urine may not be used to reveal pulmonary inflammation and damage by ozone.

Reinterpreting the best biomarker of oxidative stress: The 8-iso-prostaglandin F2α/prostaglandin F2α ratio shows complex origins of lipid peroxidation biomarkers in animal models

Oxidative stress is elevated in numerous environmental exposures and diseases. Millions of dollars have been spent to try to ameliorate this damaging process using anti-oxidant therapies. Currently, the best accepted biomarker of oxidative stress is the lipid oxidation product 8-iso-prostaglandin F2α (8-iso-PGF2α), which has been measured in over a thousand human and animal studies. 8-iso-PGF2α generation has been exclusively attributed to nonenzymatic chemical lipid peroxidation (CLP). However, 8-iso-PGF2α can also be produced enzymatically by prostaglandin-endoperoxide synthases (PGHS) in vivo. When failing to account for PGHS-dependent generation, 8-iso-PGF2α cannot be interpreted as a selective biomarker of oxidative stress. We investigated the formation of 8-iso-PGF2α in rats exposed to carbon tetrachloride (CCl4) or lipopolysaccharide (LPS) using the 8-iso-PGF2α/PGF2α ratio to quantitatively determine the source(s) of 8-iso-PGF2α. Upon exposure to a 120mg/kg dose of CCl4, the contribution of CLP accounted for only 55.6±19.4% of measured 8-iso-PGF2α, whereas in the 1200mg/kg dose, CLP was the predominant source of 8-iso-PGF2α (86.6±8.0% of total). In contrast to CCl4, exposure to 0.5mg/kg LPS was characterized by a significant increase in both the contribution of PGHS (59.5±7.0) and CLP (40.5±14.0%). In conclusion, significant generation of 8-iso-PGF2α occurs through enzymatic as well as chemical lipid peroxidation. The distribution of the contribution is dependent on the exposure agent as well as the dose. The 8-iso-PGF2α/PGF2α ratio accurately determines the source of 8-iso-PGF2α and provides an absolute measure of oxidative stress in vivo.

Reinterpreting the best biomarker of oxidative stress: The 8-iso-PGF(2α)/PGF(2α) ratio distinguishes chemical from enzymatic lipid peroxidation

The biomarker 8-iso-prostaglandin F2α (8-iso-PGF2α) is regarded as the gold standard for detection of excessive chemical lipid peroxidation in humans. However, biosynthesis of 8-iso-PGF2α via enzymatic lipid peroxidation by prostaglandin-endoperoxide synthases (PGHSs), which are significantly induced in inflammation, could lead to incorrect biomarker interpretation. To resolve the ambiguity with this biomarker, the ratio of 8-iso-PGF2α to prostaglandin F2α (PGF2α) is established as a quantitative measure to distinguish enzymatic from chemical lipid peroxidation in vitro, in animal models, and in humans. Using this method, we find that chemical lipid peroxidation contributes only 3% to the total 8-iso-PGF2α in the plasma of rats. In contrast, the 8-iso-PGF2α levels in plasma of human males are generated >99% by chemical lipid peroxidation. This establishes the potential for an alternate pathway of biomarker synthesis, and draws into question the source of increases in 8-iso-PGF2α seen in many human diseases. In conclusion, increases in 8-iso-PGF2α do not necessarily reflect increases in oxidative stress; therefore, past studies using 8-iso-PGF2α as a marker of oxidative stress may have been misinterpreted. The 8-iso-PGF2α/PGF2α ratio can be used to distinguish biomarker synthesis pathways and thus confirm the potential change in oxidative stress in the myriad of disease and chemical exposures known to induce 8-iso-PGF2α.

Biomarkers of oxidative stress study VI. Endogenous plasma antioxidants fail as useful biomarkers of endotoxin-induced oxidative stress

This is the newest report in a series of publications aiming to identify a blood-based antioxidant biomarker that could serve as an in vivo indicator of oxidative stress. The goal of the study was to test whether acutely exposing Göttingen mini pigs to the endotoxin lipopolysaccharide (LPS) results in a loss of antioxidants from plasma. We set as a criterion that a significant effect should be measured in plasma and seen at both doses and at more than one time point. Animals were injected with two doses of LPS at 2.5 and 5 µg/kg iv. Control plasma was collected from each animal before the LPS injection. After the LPS injection, plasma samples were collected at 2, 16, 48, and 72 h. Compared with the controls at the same time point, statistically significant losses were not found for either dose at multiple time points in any of the following potential markers: ascorbic acid, tocopherols (α, δ, γ), ratios of GSH/GSSG and cysteine/cystine, mixed disulfides, and total antioxidant capacity. However, uric acid, total GSH, and total Cys were significantly increased, probably because LPS had a harmful effect on the liver. The leakage of substances from damaged cells into the plasma may have increased plasma antioxidant concentrations, making changes difficult to interpret. Although this study used a mini-pig animal model of LPS-induced oxidative stress, it confirmed our previous findings in different rat models that measurement of antioxidants in plasma is not useful for the assessment of oxidative damage in vivo.

Prostaglandin F₂α modulates atrial chronotropic hyporesponsiveness to cholinergic stimulation in endotoxemic rats

Endotoxemia induces various physiological adaptive responses such as tachycardia. There is evidence to show that inflammatory tachycardia might be linked to a direct action of prostanoids on the cardiac pacemaker cells. Recent reports have indicated that systemic inflammation may uncouple of cardiac pacemaker from cholinergic neural control in experimental animals; however, the exact mechanism of this phenomenon is uncertain. This study was aimed to explore the hypothesis that prostanoids modulate atrial chronotropic hyporesponsiveness to cholinergic stimulation in endotoxemic rats. Male albino rats were given intraperitoneal injection of either saline or lipopolysaccharide (LPS, 1 mg/kg). 3 h after saline or LPS injection, the atria were isolated and chronotropic responsiveness to cholinergic stimulation was evaluated in an organ bath. The expression of atrial cyclooxygenases (COX)-1, COX-2 and COX-3 mRNA was assessed by quantitative real-time RT-PCR and cytosocalcium-dependent phospholipase A₂ (cPLA₂) activity was measured in the atria. The expression of atrial COX-2 mRNA and cPLA₂ activity increased significantly in endotoxemic atria (P<0.05). Incubation with prostaglandin F₂α (PGF₂α, 100 pM) could significantly decrease chronotropic response to cholinergic stimulation in vitro. Likewise, LPS injection could induce a significant hyporesponsiveness to cholinergic stimulation, and incubation of isolated atria with either indomethacin (5 µM) or AL-8810 (a PGF₂α antagonist, 10 µM) could reverse it (P<0.01, P<0.05, respectively), while SQ29548 (a thromboxane A₂ antagonist, 10 nM) was failed (P>0.05). Our data showed that PGF₂α may contribute to the atrial chronotropic hyporesponsiveness to cholinergic stimulation in endotoxemic rats.

Positive and negative effects of prostaglandins in Alzheimer's disease

The aim of this review was to clarify the role of prostaglandins and prostaglandin receptors in the immunopathology of Alzheimer's disease. A PubMed search was done using the key word, 'Alzheimer's disease' in combination with the term 'prostaglandins'. Articles from the past 10 years were preferentially selected but important ones from the past 20 years were also included according to the authors' judgment. Alzheimer's disease is characterized by pathological hallmarks such as extracellular deposition of the amyloid β-peptide, the appearance of intracellular neurofibrillary tangles, extensive neuronal loss and synaptic changes in the cerebral cortex and hippocampus. These processes induce inflammatory pathways by activating microglia, astrocytes and infiltrating leukocytes that produce inflammatory mediators including cytokines and prostaglandins.Prostaglandins are small lipid mediators derived from arachidonic acid by multi-enzymatic pathways in which cyclooxygenases and phospholipases are the rate-limiting enzymes. In the central nervous system, prostaglandins exhibit either neurotoxic or neuroprotective effects by acting on specific G-protein-coupled receptors that have different subfamilies and differences in their selective agonists, tissue distribution and signal transduction cascades. Further studies on the role of prostaglandins in Alzheimer's disease may contribute to clarification of their neuroprotective actions, which may lead to the development of successful therapeutic strategies.

Joint effects of serum ferritin and body mass index on the risk of coronary artery disease: a case-control study

OBJECTIVES

Serum ferritin and body mass index (BMI) have been reportedly associated with coronary artery disease (CAD) risk. The aim of the present study was to explore the interaction between serum ferritin and BMI on CAD risk.

DESIGN

Hospital-based case-control study.

SETTING

Patients with CAD and the controls were recruited from Qilu Hospital, Shandong University.

PARTICIPANTS

258 CAD cases and 282 healthy controls.

METHODS

Multiplicative interaction was assessed through a cross-product interaction term in a multivariate logistic regression model. The effect of serum ferritin and BMI were evaluated per 50 µg/L and per 2 kg/m(2), respectively. The presence of additive interaction between serum ferritin and BMI was evaluated by calculation of the relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP) and synergy index (S).

RESULTS

The ORs and 95% CI of the serum ferritin-BMI product term on a multiplicative scale in the univariate and multivariate models were 0.943 (0.904 to 0.984) and 1.004 (0.951 to 1.059), respectively. There was also evidence for interaction on an additive scale; the RERI (95% CI), AP (95% CI) and S (95% CI) in the univariate model were 0.314 (0.026 to 1.506), 0.107 (0.017 to 0.241) and 1.194 (1.053 to 1.406), respectively. After adjusting for the potential confounders, the estimates and 95% CIs for the aforementioned three measures were 0.004 (-0.016 to 0.311), 0.004 (-0.016 to 0.191) and 1.039 (0.774 to 1.285), respectively.

CONCLUSIONS

Serum ferritin and BMI had an additive interaction on the risk of CAD in Chinese population. Further investigations with big sample size are necessary for confirming this additive interaction.

Prostaglandins and rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, autoimmune, and complex inflammatory disease leading to bone and cartilage destruction, whose cause remains obscure. Accumulation of genetic susceptibility, environmental factors, and dysregulated immune responses are necessary for mounting this self-reacting disease. Inflamed joints are infiltrated by a heterogeneous population of cellular and soluble mediators of the immune system, such as T cells, B cells, macrophages, cytokines, and prostaglandins (PGs). Prostaglandins are lipid inflammatory mediators derived from the arachidonic acid by multienzymatic reactions. They both sustain homeostatic mechanisms and mediate pathogenic processes, including the inflammatory reaction. They play both beneficial and harmful roles during inflammation, according to their site of action and the etiology of the inflammatory response. With respect to the role of PGs in inflammation, they can be effective mediators in the pathophysiology of RA. Thus the use of agonists or antagonists of PG receptors may be considered as a new therapeutic protocol in RA. In this paper, we try to elucidate the role of PGs in the immunopathology of RA.

Comparison of carbamylated erythropoietin-FC fusion protein and recombinant human erythropoietin during porcine aortic balloon occlusion-induced spinal cord ischemia/reperfusion injury

PURPOSE

Recombinant human erythropoietin (rhEPO) attenuated ischemia/reperfusion (I/R) injury-induced spinal cord damage. Since carbamylated EPO derivatives are stated to be devoid of rhEPO side effects, we tested the hypothesis that a newly developed carbamylated EPO-FC fusion protein (cEPO-FC) would compare favorably with rhEPO.

METHODS

Anesthetized and mechanically ventilated pigs randomly received cEPO-FC (50 μg kg(-1)), rhEPO (5,000 IU kg(-1)) or vehicle (n = 9 per group) 30 min prior to 30 min of aortic occlusion and over the 4 h of reperfusion. During aortic occlusion, mean arterial pressure (MAP) was maintained at 80-120% of baseline values by esmolol, nitroglycerin, and adenosine-5'-triphosphate (ATP). During reperfusion, noradrenaline was titrated to keep MAP at pre-ischemic levels. Spinal cord function was assessed by motor evoked potentials (MEP) and lower limb reflexes. Tissue damage was evaluated using hematoxylin and eosin, Nissl, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. Plasma levels of interleukin-6, tumor necrosis factor-α, and 8-isoprostanes were measured as markers of systemic inflammation and oxidative stress.

RESULTS

While only cEPO-FC restored MEP amplitude to values close to pre-occlusion levels, both cEPO-FC and rhEPO comparably restored lower limb reflexes and reduced the percentage of damaged neurons. Infiltration of mononuclear inflammatory cells was moderate without intergroup difference; positive TUNEL staining was barely detectable in any group. I/R injury increased blood cytokine levels without intergroup difference, whereas both cEPO-FC and rhEPO significantly lowered 8-isoprostane levels.

CONCLUSIONS

In a porcine model of aortic balloon occlusion-induced spinal cord I/R injury, cEPO-FC and rhEPO comparably protected against ischemic spinal cord dysfunction and neuronal damage. This effect coincided with attenuated oxidative stress.

Prostaglandins and inflammation

Prostaglandins are lipid autacoids derived from arachidonic acid. They both sustain homeostatic functions and mediate pathogenic mechanisms, including the inflammatory response. They are generated from arachidonate by the action of cyclooxygenase isoenzymes, and their biosynthesis is blocked by nonsteroidal antiinflammatory drugs, including those selective for inhibition of cyclooxygenase-2. Despite the clinical efficacy of nonsteroidal antiinflammatory drugs, prostaglandins may function in both the promotion and resolution of inflammation. This review summarizes insights into the mechanisms of prostaglandin generation and the roles of individual mediators and their receptors in modulating the inflammatory response. Prostaglandin biology has potential clinical relevance for atherosclerosis, the response to vascular injury and aortic aneurysm.

Effects of caffeic acid phenethyl ester on endotoxin-induced cardiac stress in rats: a possible mechanism of protection

Endotoxins (lipopolysaccharides; LPS) are known to cause multiple organ failure, including myocardial dysfunction. The present study aimed to investigate the mechanism of caffeic acid phenethyl ester (CAPE) protection against LPS-induced cardiac stress. Rats were allocated into three groups; group 1 served as a normal control group, group 2 (LPS) received a single intraperitoneal injection of LPS (10 mg/kg), group 3 (LPS + CAPE) was injected intraperitoneally with CAPE (10 mg/kg/day; solubilized in saline containing 20% tween 20) throughout a period of 10 days prior to LPS injection. Rats were maintained 4 h before sacrifice. Caffeic acid phenethyl ester pretreatment normalized LPS-enhanced activities of serum creatine kinase (CK) and lactate dehydrogenase (LDH) as well as glutathione peroxidase (GPx), and myeloperoxidase (MPO) in cardiac tissue. A significant reduction of the elevated levels of serum tumor necrosis factor-alpha (TNF-α) as well as serum and cardiac nitrite/nitrate (NOx) ) was achieved after CAPE pretreatment. CAPE also restored malondialdelyde (MDA), reduced glutathione (GSH), and cytosolic calcium (Ca2+ ) levels in the heart. A marked induction of cardiac heme oxygenase-1 (HO-1) protein level was detected in CAPE-pretreated group. Whereas, LPS-induced reduction of adenosine triphosphate (ATP) and phosphocreatine (PCr) levels was insignificantly changed. Conclusively, the early treatment with CAPE maintained antioxidant defences, reduced oxidative injury, cytokine damage, and inflammation but did not markedly improve energy status in cardiac tissue. The beneficial effect of CAPE might be mediated, at least in part, by the superinduction of HO-1.

The relationship between serum biotin and oxidant/antioxidant activities in bovine lameness

Serum biotin concentrations, erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), reduced glutathione (GSH) and plasma thiobarbituric acid reactive substances (TBARS) were measured in 36 dairy cows, 18 of them were healthy and served as control. In the 18 cows with lameness problems, there were 5 cows with interdigital necrobacillosis, 5 cows with subsolar abscessation, 2 cows with solar ulcers, 2 cows with white line disease, 2 cows with chronic laminitis and 2 cows with septic arthritis. The degree of lameness was estimated to be slight in 3 cows, moderate in 11 cows and severe in 4 cows. Plasma fibrinogen levels and TBARS concentrations were increased significantly (P≤0.05) in lame cows compared to control group. The antioxidant enzymes GSH-Px, and CAT concentrations were increased significantly (P≤0.05) in lame cows. The level of reduced glutathione and the activity of SOD were significantly decreased in affected cows compared to healthy ones. Serum biotin levels in healthy cows ranged from 2.25 to 3.5ng/ml while in lame cows, biotin levels ranged from 1.17 to 2.3ng/ml. Biotin levels correlated positively with blood GSH (r=0.870, P≤0.05), (r=0.735, P≤0.05) and with GSH-Px (r=0.539, P≤0.05), (r=0.637, P≤0.05) and with SOD (r=0.637, P≤0.05), (r=0.449, P≤0.05) and with catalase (r=0.533, P≤0.05), (r=0.585, P≤0.05) in both healthy and lameness affected subjects, respectively.

Association of systemic oxidative stress with suppressed serum IgG to commensal oral biofilm and modulation by periodontal infection

To assess the impact of systemic oxidative stress on humoral immune responses, we examined the relation between levels of serum 8-isoprostane and serum IgG antibodies against 17 microorganisms in the commensal oral biofilm among the ARIC population of community-dwelling adults (n = 4,717). Bivariately, serum 8-isoprostane was associated with age, race/center, education, smoking, serum triglycerides, and the extent of periodontal disease severity. Total IgG antibody directed to the oral biofilm was significantly associated with race/center, hypertension, triglycerides, periodontal disease severity, plaque, and serum 8-isoprostane. In multivariate models, the highest quartile of increased 8-isoprostane displayed marked reductions (44%) in biofilm IgG antibody in contrast to small increases in total IgG antibody level for the highest quartiles of oral bacterial burden or periodontal disease severity (19 and 12%, respectively; p < 0.0001). Increased 8-isoprostane was associated with decreased total IgG antibody (p < 0.0001) in subjects with or without extensive periodontal disease and/or biofilm and with suppression of IgG responses across the entire biofilm composition. Increased systemic oxidative stress is associated with a generalized decrease of serum IgG antibody responses to the oral biofilm. Levels of oral microbial burden, periodontitis severity, and smoking are, by comparison, minor modifiers of serum IgG responses to the commensal oral biofilm.

Serum selenium predicts levels of F2-isoprostanes and prostaglandin F2αin a 27 year follow-up study of Swedish men

Low concentrations of selenium (Se) predict mortality and cardiovascular diseases in some populations. The effect of Se on in vivo indicators of oxidative stress and inflammation, two important features of atherosclerosis, in human populations is largely unexplored. This study investigated the longitudinal association between serum selenium (s-Se) and a golden standard indicator of oxidative stress in vivo (8-iso-prostaglandin F2alpha, a major F2-isoprostane), an indicator of cyclooxygenase (COX)-mediated inflammation (prostaglandin F2alpha), high sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6) and serum amyloid A protein (SAA) in a follow-up study of 27 years. The s-Se was measured in 615 Swedish men at 50 years of age in a health investigation. The status of oxidative stress and inflammation was evaluated in a re-investigation 27 years later by quantification of urinary 8-iso-PGF2alpha and 15-keto-dihydro-PGF2alpha (a major metabolite of PGF2alpha) and serum hsCRP, SAA and IL-6. Men in the highest quartile of s-Se at age 50 had decreased levels of 8-iso-PGF2alpha compared to all lower quartiles and decreased levels of PGF2alpha compared to all lower quartiles at follow-up. These associations were independent of BMI, diabetes, hyperlipidemia, hypertension, smoking, alpha-tocopherol and beta-carotene at baseline. The s-Se was not associated with hsCRP, SAA or IL-6 at follow-up. In conclusion, high concentrations of s-Se predict reduced levels of oxidative stress and subclinical COX-mediated (but not cytokine-mediated) inflammation in a male population. The associations between Se, oxidative stress and inflammation, respectively, might be related to the proposed cardiovascular protective property of Se.

Oxidative Stress and Myocardial Damage during Elective Percutaneous Coronary Interventions and Coronary AngiographyA Comparison of Blood-borne Isoprostane and Troponin Release

The role of oxidative stress in clinical cardiology is still controversial. The aims of the present study were to examine if minor ischaemic episodes as may occur during elective percutaneous coronary intervention (PCI) induce oxidative stress and, eventually, if oxygen stress correlates with myocardial injury. Thirty eight and nine patients underwent PCI and diagnostic coronary angiography, respectively. Peripheral blood was sampled at different time points for plasma analyses of: 8-iso-PGF2alpha (free radical-mediated oxidative stress); 15-keto-dihydro-PGF2alpha (cyclooxygenase-mediated inflammation); troponin-T (myocardial injury); hsCRP, vitamin A and vitamin E; and, total antioxidants status (TAS). In both groups 8-iso-PGF2alpha increased transiently by approximately 80% (p < 0.001) during the procedure. There was a minor troponin-T release (p < 0.001) after PCI, but no correlation with 8-iso-PGF2alpha. Troponin-T did not increase after angiography. 15-keto-dihydro-PGF2alpha decreased by 50% after ended procedure, but increased by 100% after 24 h compared to baseline. hsCRP increased significantly (p < 0.001) from baseline to the next day in the PCI-group, but not in the angiography group. Vitamins and TAS decreased slightly after the procedures. It is concluded that a moderate oxidative stress was induced by both elective PCI and coronary angiography but that no correlation was found between oxidative stress and myocardial injury in this setting. This indicates that other mechanisms than ischaemia-reperfusion episodes caused an elevation in plasma isoprostane such like the injury at a vascular site mutual for both procedures. A secondary finding from the study was elevated markers of early inflammatory response, not only after PCI, but also after angiography.

F2-isoprostane induced prostaglandin formation in the rabbit

F(2)-isoprostanes, non-enzymatic free radical mediated products of arachidonic acid, have shown to form during various oxidant stress status and have potent biological effects. This study investigates to what extent 8-iso-PGF(2alpha) (a major F(2)-isoprostane), a bioactive product of lipid peroxidation can modify endogenous prostaglandin F(2alpha) (PGF(2alpha)) formation since prostaglandins are inflammatory as well as potent vasoregulatory substances that modulate diverse important physiological functions, and also form during acute and chronic inflammation. An immediate appearance and disappearance of 8-iso-PGF(2alpha) was seen in both plasma and urine within a short interval after i.v. administration of 43 microg/kg of 8-iso-PGF(2alpha) to the rabbits. A successive but differential formation of PGF(2alpha) resulted in a rapid and pulsatile increase of plasma 15-keto-dihydro-PGF(2alpha), a major metabolite of primary PGF(2alpha). Later, this compound was excreted efficiently as intact compound into the urine during the 3 h of experiment. A 8-fold increase of PGF(2alpha) metabolite in plasma at 10 min and 12-fold increase in the urine at 30-60 after the i.v. administration of 8-iso-PGF(2alpha) was observed which continued throughout the 3 h of experiment. This observation suggests that pharmacologically administered or endogenously produced 8-iso-PGF(2alpha) during oxidant stress induces prostaglandin formation presumably through the classical cyclooxygenase-catalysed arachidonic acid oxidation which might be inflammatory itself to the cells and exerts further vasoconstrictive effects.

Genetic deficiency of NADPH oxidase does not diminish, but rather enhances, LPS-induced acute inflammatory responses in vivo

Reactive oxygen species (ROS) and oxidative stress are thought to play a central role in the etiology of cell dysfunction and tissue damage in sepsis. However, there is limited and controversial evidence from in vivo studies that ROS mediate cell signaling processes that elicit acute inflammatory responses during sepsis. Because NADPH oxidase is one of the main cellular sources of ROS, we investigated the role of this enzyme in lipopolysaccharide (LPS)-induced acute inflammation in vivo, utilizing mice deficient in the gp91(phox) or p47(phox) subunits of NADPH oxidase. Age-and body weight-matched C57BL/6J wild-type (WT) and gp91(phox-/-) and p47(phox-/-) mice were injected ip with 50 microg LPS or saline vehicle and sacrificed at various time points up to 24 h. We found that LPS-induced acute inflammatory responses in serum and tissues were not significantly diminished in gp91(phox-/-) and p47(phox-/-) mice compared to WT mice. Rather, genetic deficiency of NADPH oxidase was associated with enhanced gene expression of inflammatory mediators and increased neutrophil recruitment to lung and heart. Furthermore, no protection from LPS-induced septic death was observed in either knockout strain. Our findings suggest that NADPH oxidase-mediated ROS production and cellular redox signaling do not promote, but instead limit, LPS-induced acute inflammatory responses in vivo.

A polymorphism in the cyclooxygenase 1 gene is associated with decreased inflammatory prostaglandin F2alpha formation and lower risk of cardiovascular disease

This study investigates the impact of genetic variation in the cyclooxygenase-1 (COX-1) gene on formation of the vasoconstrictive, pro-inflammatory prostaglandin F(2)(alpha) (PGF(2)(alpha)) and development of cardiovascular disease (CVD). We determined COX-1 genotypes, PGF(2)(alpha) formation and CVD prevalence in a Swedish cohort of 809 men at age 77 years. Of these, 237 had a history of CVD according to the registry data. Four of nine COX-1 single nucleotide polymorphisms were associated with altered formation of PGF(2)(alpha) (P<0.05). Two COX-1 gene variants (rs10306135 and rs883484) remained significantly associated with altered PGF(2)(alpha) formation after adjusted significance level for multiple testing (alpha-level=0.0059). Furthermore, individuals homozygote for the variant allele rs10306135 had lower prevalence of CVD, compared to the common allele (0% versus 30%, P=0.0047). In conclusion, subjects homozygote for the variant allele of a COX-1 gene polymorphism represent a subpopulation of men with decreased PGF(2)(alpha) formation and lower prevalence of CVD.

Low dietary intake of β-carotene, α-tocopherol and ascorbic acid is associated with increased inflammatory and oxidative stress status in a Swedish cohort

Fruit and vegetable consumption has been associated with a reduced risk of several diseases including CVD. A part of these effects seen could be linked to anti-inflammatory and antioxidative effects, although this has not been thoroughly investigated. The present study was designed to investigate the effects of the dietary intake of β-carotene, α-tocopherol and ascorbic acid on in vivo biomarkers of inflammation (PGF2α, high-sensitive C-reactive protein (hsCRP) and IL-6 formation) and oxidative stress (F2-isoprostane formation), the two important factors associated with accelerated atherosclerosis. The dietary intake of 704 participants in the Uppsala Longitudinal Study of Adult Men (ULSAM) at age 70 years was registered and inflammatory and oxidative stress biomarkers were quantified 7 years later. The registered dietary intakes of ascorbic acid and α-tocopherol were negatively associated linearly and in quartiles with both PGF2α, hsCRP, IL-6 and F2-isoprostanes, where ascorbic acid intake generally was more strongly associated. Dietary intake of β-carotene was only significantly negatively associated with F2-isoprostanes. In conclusion, the present study is the first to suggest that the intake of food rich in antioxidants is associated with reduced cyclo-oxygenase- and cytokine-mediated inflammation and oxidative stress at 7 years of follow-up. These associations could be linked to the beneficial effects of fruit and vegetables observed on CVD.

Hemodynamic and metabolic effects of hydrogen sulfide during porcine ischemia/reperfusion injury

In awake spontaneously breathing mice, inhaling gaseous hydrogen sulfide (H2S) produced a "suspended animation-like" metabolic status with hypothermia and reduced O2 demand, thus protecting from lethal hypoxia. Murine models may be questioned, however, because due to their large surface area/mass ratio, rodents can rapidly drop their core temperature. Therefore, we investigated whether intravenous H2S (Na2S, sodium sulfide) would induce a comparable metabolic response in anesthetized and mechanically ventilated pigs. Because H2S was reported to improve heart function after myocardial ischemia, we also investigated whether sulfide would influence the noradrenaline responsiveness during reperfusion after aortic occlusion. After 2 h of i.v. sulfide (0.2 mg.kg followed by 2 mg.kg.per h; n=8) or vehicle (n=8), animals underwent 30 minutes of aortic occlusion with nitroglycerine, esmolol, and adenosine-5'-triphosphate adjusted to maintain MAP at 80% to 120% of baseline. During reperfusion, noradrenaline was titrated to keep MAP greater than or equal to 80% of this level. Sulfide reduced heart rate and cardiac output without affecting stroke volume, markedly decreased the time and dose of noradrenaline required to maintain hemodynamic targets, and caused a drop in core temperature concomitant with lower O2 uptake and CO2 production. Although arterial PCO2 and acid-base status were comparable, arterial PO2 was lower in the sulfide group at the end of the experiment. Sulfide attenuated the reperfusion-related hyperlactatemia, although glycemia was higher at the end of the experiment. The parameters of inflammation and oxidative stress did not differ. Intravenous sulfide allowed reducing energy expenditure in an anesthetized large-animal model and improved the noradrenaline responsiveness during reperfusion after aortic occlusion. Investigations are warranted, hence, whether it may also protect other organs after I/R injury.

F2-isoprostanes in human health and diseases: from molecular mechanisms to clinical implications

Oxidative stress is implicated as one of the major underlying mechanisms behind many acute and chronic diseases, and involved in normal aging. However, the measurement of free radicals or their end products is complicated. Thus, proof of association of free radicals in pathologic conditions has been absent. Isoprostanes are prostaglandin-like bioactive compounds that are biosynthesized in vivo independent of cyclooxygenases, principally through free-radical catalyzation of arachidonic acid. Isoprostanes are now considered to be reliable biomarkers of oxidative stress, as evidenced by an autonomous study organized recently by the National Institutes of Health (NIH) in the United States. A number of these compounds have potent biologic activities such as vasoconstrictive and certain inflammatory properties. Isoprostanes are involved in many human diseases. Additionally, elevated levels of F(2)-isoprostanes have been seen in normal human pregnancy and after intake of some fatty acids, but their physiologic assignments have not yet been distinctive. This evidence indicates that measurement of bioactive F(2)-isoprostanes in body fluids offers a unique noninvasive analytic utensil to study the role of free radicals in physiology, oxidative stress-related diseases, experimental acute or chronic inflammatory conditions, and also in the assessment of various antioxidants, radical scavengers, and drugs.

Erythropoietin during porcine aortic balloon occlusion-induced ischemia/reperfusion injury

BACKGROUND

Aortic occlusion causes ischemia/reperfusion injury, kidney and spinal cord being the most vulnerable organs. Erythropoietin improved ischemia/reperfusion injury in rodents, which, however, better tolerate ischemia/reperfusion than larger species. Therefore, we investigated whether erythropoietin attenuates porcine aortic occlusion ischemia/reperfusion injury.

MATERIALS AND METHODS

Before occluding the aorta for 45 mins by inflating intravascular balloons, we randomly infused either erythropoietin (n = 8; 300 IU/kg each over 30 mins before and during the first 4 hrs of reperfusion) or vehicle (n = 6). During aortic occlusion, mean arterial pressure was maintained at 80% to 120% of baseline by esmolol, nitroglycerine, and adenosine 5'-triphosphate. During reperfusion, noradrenaline was titrated to keep mean arterial pressure >80% of baseline. Kidney perfusion and function were assessed by fractional Na-excretion, p-aminohippuric acid and creatinine clearance, spinal cord function by lower extremity reflexes and motor evoked potentials. Blood isoprostane levels as well as blood and tissue catalase and superoxide dismutase activities allowed evaluation of oxidative stress. After 8 hrs of reperfusion, kidney and spinal cord specimens were taken for histology (hematoxylin-eosin, Nissl staining) and immunohistochemistry (TUNEL assay for apoptosis).

RESULTS

Parameters of oxidative stress and antioxidative activity were comparable. Erythropoietin reduced the noradrenaline requirements to achieve the hemodynamic targets and may improve kidney function despite similar organ blood flow, histology, and TUNEL staining. Neuronal damage and apoptosis was attenuated in the thoracic spinal cord segments without improvement of its function.

CONCLUSION

During porcine aortic occlusion-induced ischemia/reperfusion erythropoietin improved kidney function and spinal cord integrity. The lacking effect on spinal cord function was most likely the result of the pronounced neuronal damage associated with the longlasting ischemia.

Antioxidant treatment reverses mitochondrial dysfunction in a sepsis animal model

Evidence from the literature has demonstrated that reactive oxygen species (ROS) play an important role in the development of multiple organ failure and septic shock. In addition, mitochondrial dysfunction has been implicated in the pathogenesis of multiple organ dysfunction syndrome (MODS). The hypothesis of cytopathic hypoxia postulates that impairment in mitochondrial oxidative phosphorylation reduces aerobic adenosine triphosphate (ATP) production and potentially induces MODS. In this work, our aim was to evaluate the effects of antioxidants on oxidative damage and energy metabolism parameters in liver of rats submitted to a cecal ligation puncture (CLP) model of sepsis. We speculate that CLP induces a sequence of events that culminate with liver cells death. We propose that mitochondrial superoxide production induces mitochondrial oxidative damage, leading to mitochondrial dysfunction, swelling and release of cytochrome c. These events occur in early sepsis development, as reported in the present work. Liver cells necrosis only occurs 24 h after CLP, but all other events occur earlier (6-12 h). Moreover, we showed that antioxidants may prevent oxidative damage and mitochondrial dysfunction in liver of rats after CLP. In another set of experiments, we verified that L-NAME administration did not reverse increase of superoxide anion production, TBARS formation, protein carbonylation, mitochondrial swelling, increased serum AST or inhibition on complex IV activity caused by CLP. Considering that this drug inhibits nitric oxide synthase and that no parameter was reversed by its administration, we suggest that all the events reported in this study are not mediated by nitric oxide. In conclusion, although it is difficult to extrapolate our findings to human, it is tempting to speculate that antioxidants may be used in the future in the treatment of this disease.

F2-isoprostane, inflammation, cardiac function and oxygenation in the endotoxaemic pig

Prostaglandins are profoundly involved in endotoxaemic shock. Twenty pigs were given endotoxin at various doses (0.063-16 microg kg(-1) h(-1)). Three non-endotoxaemic pigs served as controls. Two eicosanoids were measured in plasma (8-iso-PGF(2alpha), a free radical-mediated lipid peroxidation product, and 15-keto-dihydro-PGF(2alpha) a major metabolite of COX activity) and evaluated against the pathophysiological responses that occur during endotoxaemic shock. Endotoxin mediates an increase in both 8-iso-PGF(2alpha) and 15-keto-dihydro-PGF(2alpha). An increase in the endotoxin dose induced significant log-linear responses in 8-iso-PGF(2alpha) and 15-keto-dihydro-PGF(2alpha). Oxidative injury correlated to the TNF-alpha, IL-6, reductions in cardiac performance and to oxygen delivery and utilisation. COX-mediated inflammatory responses correlated to TNF-alpha, IL-6 and to reductions in arterial oxygen tension. Thus, oxidative injury and COX-mediated inflammation play a central role in the manifestation of endotoxaemic shock. Furthermore, formation of these eicosanoids on endotoxin-mediated alterations in pulmonary hypertension, oxygen delivery and oxygen utilisation seems to be independent of the administered endotoxin dose.

Novel cyclooxygenase-catalyzed bioactive prostaglandin F2alpha from physiology to new principles in inflammation

Prostaglandin F2alpha (PGF2alpha), a foremost stable vasoactive cyclooxygenase (COX)-catalyzed prostaglandin, regulates a number of key physiological functions such as luteolysis, ovarian function, luteal maintenance of pregnancy, and parturition as a constitutive part of ongoing reproductive processes of the body. It has recently been implicated in the regulation of intricate pathophysiological processes, such as acute and chronic inflammation, cardiovascular and rheumatic diseases. Since the discovery of a second isoform of COXs, it has been shown that PGF2alpha can be formed in vivo from arachidonic acid through both isoforms of COXs, namely cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Being synthesized in various parts of the body, it metabolizes instantly to a number of rather inactive metabolites mainly in the lungs, liver, kidney, and efficiently excretes into the urine. 15-Keto-dihydro-PGF2alpha, a major stable metabolite of PGF2alpha that reflects in vivo PGF2alpha biosynthesis, is found in larger quantities than its parent compound in the circulation and urine in basal physiological conditions, with short-lived pulses during luteolysis, induced termination of pregnancy and parturition, and is increased in tissues and various body fluids during acute, sub-chronic, and severe chronic inflammation. Further, the close relationship of PGF2alpha with a number of risk factors for atherosclerosis indicates its major role in inflammation pathology. This review addresses multiple aspects of PGF2alpha in addition to its emerging role in physiology to inflammation.

Ibuprofen use during extreme exercise: effects on oxidative stress and PGE2

PURPOSE

Oxidative stress was examined with use (N = 29) or nonuse (N = 25) of ibuprofen in ultramarathoners after the Western States Endurance Run.

METHODS

Oxidative stress was assessed by measuring plasma and urinary F2-isoprostanes, plasma nitrite, and plasma urate. A urinary prostaglandin E2 metabolite (PGE-M) was used as an end point to assess ibuprofen use. Ibuprofen users consumed 600 and 1200 mg of ibuprofen the day before and on race day, respectively, and nonusers avoided all antiinflammatory medications. Blood and urine were collected in the morning before the race and immediately after the race.

RESULTS

Use compared with nonuse of ibuprofen significantly increased plasma (P <or= 0.001) and urinary (P <or= 0.01) F2-isoprostanes after the race. Ibuprofen use was associated with reduced PGE-M (P = 0.016). Ibuprofen was not associated with changes in any other variables.

CONCLUSION

Ibuprofen use compared with nonuse by athletes competing in a 160-km race was associated with significantly increased oxidative stress.

Maintaining nitric oxide-induced airway relaxation with superoxide dismutase

BACKGROUND

We have previously shown that the protective effect of inhaled nitric oxide (iNO) against methacholine-induced bronchoconstriction is negated in airways subjected to hyperosmotic stress. In this study, hypothesizing that the impaired efficiency of iNO was caused by release of reactive oxygen radicals, we examined the effect of the radical scavenging enzyme superoxide dismutase (SOD).

METHODS

Hemodynamic and respiratory measurements were performed on anesthetized rabbits after (1) inhalation of methacholine (MCh), (2) iNO (80ppm), followed by MCh, (3) inhalation of hypertonic saline (HS), followed by iNO and MCh and (4) pre-treatment with inhalation of SOD, followed by HS, iNO and MCh. We analyzed plasma for a marker of oxidative stress, 8-iso-prostaglandin (PG)F(2alpha) and for a marker of activation of COX-mediated inflammatory cascades, PGF(2alpha) metabolite.

RESULTS

Pre-treatment with SOD restored the bronchoprotective response to iNO in hyperosmotic airways. No direct effect was seen by SOD treatment on levels of 8-iso-PGF(2alpha), but this marker of oxidative stress correlated positively with increased bronchoconstriction. Hyperosmotic challenge elevated levels of PGF(2alpha) metabolite, and pre-treatment with SOD protected against this activation of the inflammatory cascade.

CONCLUSION

SOD pre-treatment restores the relaxant effects of iNO in hyperosmotically challenged airways by attenuating oxidative stress and activation of COX-mediated inflammatory cascades.

Increased isoprostane and prostaglandin are prominent in neurons in Alzheimer disease

BACKGROUND

Inflammation and oxidative stress are both involved in the pathogenesis of Alzheimer disease and have been shown to be reciprocally linked. One group of molecules that have been directly associated with inflammation and the production of free radicals are the prostaglandin 13,14-dihydro 15-keto PGF2alpha and the isoprostane 8-iso-PGF2alpha.

RESULTS

To further delineate the role of inflammatory and oxidative parameters in Alzheimer disease, in this study we evaluated the amount and localization of 13,14-dihydro 15-keto PGF2alpha and 8-iso-PGF2alpha in hippocampal post mortem tissue samples from age-matched Alzheimer disease and control patients. Our results demonstrate increased levels of 13,14-dihydro 15-keto PGF2alpha and 8-iso-PGF2alpha in the hippocampal pyramidal neurons of Alzheimer disease patients when compared to control patients.

CONCLUSION

These data not only support the shared mechanistic involvement of free radical damage and inflammation in Alzheimer disease, but also indicate that multiple pathogenic "hits" are likely necessary for both the development and propagation of Alzheimer disease.

Effects of a cantaloupe melon extract/wheat gliadin biopolymer during aortic cross-clamping

OBJECTIVE

We previously reported in healthy volunteers that a cantaloupe melon extract chemically combined with wheat gliadin (melon extract/gliadin) and containing SOD, catalase and residual glutathione peroxidase (GPx), protected against DNA strand-break damage induced by hyperbaric oxygen (HBO), a well-established model of DNA damage resulting from oxidative stress. Aortic cross-clamping is a typical example of ischemia/reperfusion injury-related oxidative stress, and therefore we investigated whether this melon extract/gliadin would also reduce DNA damage after aortic cross-clamping and reperfusion.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

Animal laboratory.

PATIENTS AND PARTICIPANTS

18 anesthetized, mechanically ventilated and instrumented pigs.

INTERVENTIONS

After 14 days of oral administration of 1250 mg of the melon extract/gliadin (n=9) or vehicle (n=9), animals underwent 30 min of thoracic aortic cross-clamping and 4 h of reperfusion.

MEASUREMENTS AND RESULTS

Before clamping, immediately before declamping, and at 2 and 4 h of reperfusion, we measured blood isoprostane (immunoassay) and malondialdehyde concentrations (fluorimetric thiobarbituric acid test), SOD, catalase and GPx activities (spectrophotometric kits), NO formation (nitrate+nitrite; chemoluminescence), DNA damage in whole blood samples and isolated lymphocytes exposed to hyperbaric oxygen (comet assay). Organ function was also evaluated. Kidney and spinal cord specimen were analysed for apoptosis (TUNEL assay). The melon extract/gliadin blunted the DNA damage, reduced spinal cord apoptosis and attenuated NO release, however, without any effect on lipid peroxidation and organ function.

CONCLUSIONS

Pre-treatment with the oral melon extract/gliadin may be a therapeutic option to reduce oxidative cell injury affiliated with aortic cross-clamping.

Oxidants and antioxidants in disease: oxidative stress in farm animals

Important infectious diseases in farm animals, such as pneumonia and enteritis, are thought to be associated with the so-called oxidative stress, i.e. a chemical phenomenon involving an imbalance in the redox status of the individual animal. The specifics of oxidative stress and how it may result in disease or be prevented are complex questions with no simple answers. However, the considerable literature on the subject suggests that many researchers consider oxidative stress-related mechanisms to be important early events in disease development. A particularly intriguing aspect is that, at least theoretically, oxidative stress should be easily prevented with antioxidants yet the use of antioxidants as therapy remains controversial. The present knowledge on oxidative stress in farm animals is the topic of this review.

Intra-day variation of in vivo prostaglandin F2α formation in healthy subjects

Prostaglandin F(2alpha) (PGF(2alpha)) is a major stable prostaglandin formed in vivo in physiological and pathophysiological situations and has mainly potent vasoconstrictive and pro-inflammatory properties. PGF(2alpha) is now used as an indicator of acute and chronic inflammation in human clinical settings but the extent of daily variation of PGF(2alpha)in vivo in healthy humans is unknown. We quantified levels of the PGF(2alpha) metabolite 15-keto-dihydro-PGF(2alpha) in 10 healthy males and females in spot urine samples during the day (including morning urine sample) and in 24-h urine during the same day. The intra-day coefficient of variation was 20.9%. However, the total mean value of 15-keto-dihydro-PGF(2alpha) in urine collected in the morning did not significantly differ from the mean level of 15-keto-dihydro-PGF(2alpha) in the 24-h urine samples in the 10 subjects. 15-Keto-dihydro-PGF(2alpha) levels in morning urine showed a positive linear correlation with levels of 15-keto-dihydro-PGF(2alpha) in 24-h urine (R=0.72, P<0.05). In conclusion, formation of PGF(2alpha) shows a biological variation within the day in healthy humans which should not be overlooked when planning a clinical study. Single morning urine samples can be used as an alternative to 24-h urine collections for quantification of PGF(2alpha) formation to simplify the sampling regime in larger clinical studies.

Oxidative stress and inflammatory response during and following coronary interventions for acute myocardial infarction

BACKGROUND

In acute myocardial infarction (AMI) treated with percutaneous coronary intervention (PCI), myocardial injury results from complex processes during both ischemia and reperfusion. Release of reactive oxygen species (ROS) may contribute to the accumulated myocardial damage.

AIMS

To examine by frequent sampling of peripheral blood oxidative stress and early inflammation in patients undergoing primary PCI for AMI. Secondly, to assess whether a correlation exists between these parameters and the extent of myocardial damage.

METHODS

Sixteen patients undergoing primary PCI within 6 h of AMI onset were included. Peripheral blood was sampled at start of procedure (t0) and repeatedly over 24 h following reperfusion. Main plasma analyses were: 8-iso-PGF2alpha (oxidative stress), 15-keto-dihydro-PGF2alpha (cyclooxygenase-mediated inflammation); and troponin-T (myocardial injury). Additional analyses included: total antioxidant status (TAS); vitamins; hsCRP and lipids.

RESULTS

8-Iso-PGF2alpha increased following restoration of blood flow, returned to t0 values after 3 h and was reduced below t0 the following day. TAS decreased significantly from t0 to the next day. There was no significant correlation between 8-iso-PGF2alpha and troponin T values. 15-Keto-dihydro-PGF2alpha was elevated during the first hour. There was a major rise in hsCRP after 24 h.

CONCLUSION

Following reperfusion by primary PCI in AMI, oxidative stress and an inflammatory response are induced immediately. A rise in 8-iso-PGF2a during ischemia indicate that ROS generation may also take place during severely reduced coronary blood flow and hypoxia. No direct relationship between 8-iso-PGF2alpha or 15-keto-dihydro-PGF2alpha and troponin T was evident. The present study adds to the increasingly complex pathophysiological roles of ROS acting both as signal molecules and as mediators of tissue injury.

Dietary (n-3) fatty acids reduce plasma F2-isoprostanes but not prostaglandin F2alpha in healthy humans

(n-3) Fatty acids are unsaturated and are therefore easily subject to oxidization; however, they have several beneficial health effects, which include protection against cardiovascular diseases. The aim of this study was to investigate whether (n-3) fatty acids, with a controlled fat quality in the background diet, affect nonenzymatic and enzymatic lipid peroxidation and antioxidant status in humans. A total of 162 men and women in a multicenter study (The KANWU study) were randomly assigned to a diet containing a high proportion of saturated fatty acids or monounsaturated fatty acids (MUFA) for 3 mo. Within each diet group, there was a second random assignment to supplementation with fish-oil capsules [3.6 g (n-3) fatty acids/d] or placebo. Biomarkers of nonenzymatic and enzymatic lipid peroxidation in vivo were determined by measuring 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) and prostaglandin F(2alpha) (PGF(2alpha)) concentrations in plasma at baseline and after 3 mo. Antioxidant status was determined by measuring plasma antioxidant capacity with an enhanced chemiluminescence assay. The plasma 8-iso-PGF(2alpha) concentration was significantly decreased after 3 mo of supplementation with (n-3) fatty acids (P = 0.015), whereas the PGF(2alpha) concentration was not affected. The antioxidant status was not affected by supplementation of (n-3) fatty acids, but was improved by the background diet with a high proportion of MUFA. We conclude that supplementation with (n-3) fatty acids decreases nonenzymatic free radical-catalyzed isoprostane formation, but does not affect cyclooxygenase-mediated prostaglandin formation.

Ropivacaine may have advantages compared to bupivacaine in porcine endotoxemic shock

Patients that undergo major abdominal surgery often receive epidural postoperative analgesia. Septic complications are frequently seen in this cohort. In a porcine model of endotoxemic shock, resembling human gram-negative septic shock, we evaluated the effects of two widely used local anaesthetics, bupivacaine and ropivacaine given intravenously. In the endotoxin-ropivacaine group mixed venous saturation and platelet count were higher as compared to endotoxemic controls. Mean arterial blood pressure and platelet count were higher in ropivacaine-endotoxin pigs than in bupivacaine-endotoxin ones. Bupivacaine augmented endotoxin-mediated decrease in left ventricular stroke work index. Ropivacaine displays pathophysiological advantages compared to bupivacaine in septic shock, which may be explained by improved tissue perfusion by ropivacaine.

Ethyl pyruvate improves systemic and hepatosplanchnic hemodynamics and prevents lipid peroxidation in a porcine model of resuscitated hyperdynamic endotoxemia

OBJECTIVE

To investigate the systemic, pulmonary, and hepatosplanchnic hemodynamic and metabolic effects of delayed treatment with ethyl pyruvate in a long-term porcine model of hyperdynamic endotoxemia.

DESIGN

Prospective, randomized, controlled experimental study with repeated measures.

SETTING

Investigational animal laboratory.

SUBJECTS

Anesthetized, mechanically ventilated, and instrumented pigs.

INTERVENTIONS

After 12 hrs of continuous infusion of lipopolysaccharide and hydroxyethyl starch to keep mean arterial pressure >60 mm Hg, swine randomly received placebo (Ringer's solution; control group, n = 11) or ethyl pyruvate in lactated Ringer's solution (n = 8; 0.03 g.kg(-1) loading dose over 10 mins, thereafter 0.03 g.kg(-1)hr(-1) for 12 hrs).

MEASUREMENTS AND MAIN RESULTS

Whereas mean arterial pressure significantly decreased in control animals, mean arterial pressure was maintained at the baseline level in pigs treated with ethyl pyruvate. Global oxygen uptake was comparable, so that the trend toward a higher oxygen transport and the significantly higher mixed venous hemoglobin oxygen saturation resulted in a significantly lower oxygen extraction in the ethyl pyruvate group. Ethyl pyruvate reduced intrapulmonary venous admixture and resulted in significantly greater Pa(O2)/F(IO2) ratios. Despite comparable urine production in the two groups during the first 18 hrs of endotoxemia, ethyl pyruvate significantly increased diuresis during the last 6 hrs of the study. Lipopolysaccharide-induced systemic and regional venous metabolic acidosis was significantly ameliorated by ethyl pyruvate. Endotoxemia increased both blood nitrate + nitrite and isoprostane concentrations, and ethyl pyruvate attenuated the response of these markers of nitric oxide production and lipid peroxidation.

CONCLUSIONS

Ethyl pyruvate infusion resulted in improved hemodynamic stability and ameliorated acid-base derangements induced by chronic endotoxemia in pigs. Reduced oxidative stress and an decreased nitric oxide release probably contributed to these effects.

Isoprostanes, prostaglandins and tocopherols in pre-eclampsia, normal pregnancy and non-pregnancy

This study is designed to evaluate whether oxidative stress and inflammation are involved in severe pre-eclampsia compared to normal pregnancy and non-pregnancy. We have measured plasma and urinary levels of 8-iso-PGF2alpha, a major isoprostane as an indicator of oxidative stress; plasma and urinary 15-keto-dihydro-PGF2alpha, a major metabolite of cyclooxygenase-catalysed PGF2alpha as an indicator of inflammatory response, and plasma -alpha-and -gamma-tocopherol in 18 pre-eclamptic, 19 normal pregnancy and 20 non-pregnant women. Pregnant women had significantly higher levels of 8-iso-PGF2alpha and PGF2alpha metabolite as compared to the non-pregnancy. Levels of 8-iso-PGF2alpha in the pre-eclamptic women did not differ from the normal pregnancy but PGF2alpha metabolite levels were significantly higher in normal pregnancy. On the other hand, gamma-tocopherol levels were significantly lower in pre-eclampsia than normal pregnancy. In contrast, the concentration of alpha-tocopherol was very similar between the groups. alpha-and gamma-tocopherol levels were significantly lower in pregnancy compared to non-pregnancy. Although no direct evidence of oxidative stress and inflammatory response was observed in severe pre-eclampsia, a reduction of gamma-tocopherol suggests the possible precedence of oxidative stress in this condition. Higher levels of isoprostanes and prostaglandin metabolite in late pregnancy suggest the importance of both free radicals and cyclooxygenase-catalysed oxidation products in normal biological processes of pregnancy.