Urinary excretion of 8-iso-PGF(2 alpha) in three patients during sepsis, recovery and state of health

F2-isoprostanes as markers of oxidant stress: an overview

The isoprostanes are a unique series of prostaglandin-like compounds formed in vivo via a non-enzymatic mechanism involving the free radical-initiated peroxidation of arachidonic acid. This unit summarizes selected aspects regarding current knowledge of these compounds and their value as markers of oxidative injury. Novel aspects related to the biochemistry of isoprostane formation are discussed and methods by which these compounds can be analyzed and quantified are summarized. A considerable portion of this unit examines the utility of F(2)-isoprostanes as markers of oxidant injury in vitro and in vivo. Numerous studies carried out over the past decade have shown that these compounds are extremely accurate measures of lipid peroxidation in animals and humans and have illuminated the role of oxidant injury in a number of human diseases.

Redox-generated isoprostanes are associated with residual platelet activity in aspirin-treated patients with stable coronary heart disease

AIM

Insufficient platelet inhibition by low-dose aspirin is associated with poor prognosis in patients with coronary heart disease (CHD). We sought to investigate the prevalence of this phenomenon in patients with stable CHD and to study whether oxidative stress plays a role in its pathogenesis.

METHODS AND RESULTS

We studied the platelet response to long-term (≥ 6 months) low-dose (100 mg per day) aspirin in 130 consecutive patients with stable CHD (age 66 ± 8 years, 83% male). Among a wide distribution of platelet responses to collagen, ADP, and arachidonic acid, the vast majority of patients in the highest tertile of residual platelet activity (defined as 'aspirin low-responders') were characterized by lack of platelet inhibition by aspirin in vitro, significantly although not completely suppressed platelet TXB₂ production and COX-1 activity, and significantly higher urinary 8-iso-prostaglandin F(2α) excretion [186 (147-230) vs. 230 (188-318) pg per mg creatinine; median (IQR), P < 0.001; measured by GC-MS].

CONCLUSION

A relevant proportion of patients with CHD show insufficient platelet inhibition by low-dose aspirin. Oxidative stress and lipid peroxidation causing isoprostane formation may underlie inadequate platelet inhibition in an aspirin-insensitive manner in patients with cardiovascular disease.

F2-isoprostanes as markers of oxidative stress in vivo: an overview

The isoprostanes are a unique series of prostaglandin-like compounds formed in vivo via a non-enzymatic mechanism involving the free radical-initiated peroxidation of arachidonic acid. This article summarizes selected aspects regarding current knowledge of these compounds and their value as markers of oxidative injury. Novel aspects related to the biochemistry of isoprostane formation are discussed and methods by which these compounds can be analysed and quantified are summarized. A considerable portion of this article examines the utility of F(2)-isoprostanes as markers of oxidant injury in vivo. Numerous studies carried out over the past decade have shown that these compounds are extremely accurate measures of lipid peroxidation and have illuminated the role of oxidant injury in a number of human diseases including atherosclerosis, Alzheimer's disease and pulmonary disorders.

Immunomodulatory intervention in sepsis by multidrug-resistant Pseudomonas aeruginosa with thalidomide: an experimental study

Background

Thalidomide is an inhibitor of tumour necrosis factor-alpha (TNFα) that has been proven effective for the treatment of experimental sepsis by Escherichia coli. It was tested whether it might behave as an effective immunomodulator in experimental sepsis by multidrug-resistant (MDR) Pseudomonas aeruginosa.

Methods

Sepsis was induced by the intraperitoneal injection of 1 × 10⁸ cfu/kg inoculum of the test isolate in a total of 109 Wistar rats divided in three groups as follows: group A controls; group B administered seed oil 30 minutes before bacterial challenge; and group C administered 50 mg/kg of thalidomide diluted in seed oil 30 minutes before bacterial challenge. Blood was sampled for estimation of endotoxins (LPS), TNFα, interferon-gamma (IFNγ), nitric oxide (NO) and malondialdehyde (MDA). LPS was measured by the QCL-1000 LAL assay, TNFα and IFNγ by ELISA, NO by a colorimetric assay and MDA by the thiobarbiturate assay.

Results

Mean (± SE) survival of groups A, B and C were 18.60 ± 1.84, 12.60 ± 0.60 and 30.50 ± 6.62 hours (p of comparisons A to C equal to 0.043 and B to C equal to 0.002). Decreased TNFα and NO levels were found in sera of animals of group C compared to group A. Plasma levels of LPS, MDA and IFNγ did not differ between groups.

Conclusion

Intake of thalidomide considerably prolonged survival in experimental sepsis by MDR P.aeruginosa an effect probably attributed to decrease of serum TNFα.

The significance of oxidant/antioxidant balance for the pathogenesis of experimental sepsis by multidrug-resistant Pseudomonas aeruginosa

OBJECTIVE

The significance of lipid peroxidation as an independent factor leading to sepsis by multidrug-resistant Pseudomonas aeruginosa. Design experimental study.

METHODS

Twenty-six rabbits were applied. They were divided into two groups; A (n=6) comprising controls, and B (n=20) comprising animals infected by the injection of 1x10(8) cfu/kg inoculum of the test pathogen into the left inner jugular vein. Six rabbits of group B were followed-up to estimate survival; all of the remaining were sacrificed. Blood was sampled for the determination of serum malondialdehyde (MDA) by the thiobarbiturate assay, total antioxidant status (TAS) by a chromogenic assay, tumor necrosis factor alpha by a bioassay on fibrosarcoma L929 cell line, and endotoxins (LPS) by the QCL-1000 LAL assay.

RESULTS

Mean survival of group B was 60.0+/-15.8 h. MDA was significantly higher in group B compared to group A at 30, 60, 120 and 150 min. TAS was statistically decreased in group B compared to group A at 30 and 60 min. Increases of MDA in group B were followed by reciprocal decreases of TAS (P of correlation <0.001). Hemodynamic instability was recorded in group B compared to group A 160 min after bacterial challenge.

CONCLUSIONS

Early alterations of oxidant/antioxidant balance occur in experimental sepsis by multidrug-resistant P. aeruginosa followed by hemodynamic instability. Results highlight the perspective of the administration of antioxidants as immunomodulatory treatment of sepsis in animal studies.

Molecular pharmacology of isoprostanes in vascular smooth muscle

Isoprostanes are marker of lipid peroxidation and are produced after free-radical attack of membrane lipids. In addition, they are biologically active and are essentially vaso- and broncho-constrictor. Their smooth muscle constrictor actions are closely linked to the activation of the thromboxane A(2) receptor, but also involve a distinct receptor not yet identified. The response of vascular smooth muscle to isoprostanes is subclass-specific (F-series versus E-series isoprostanes) and cell- and species-related. In this review, we will address the vascular actions of isoprostanes and their possible role in vascular physiology and pathophysiology.

Iloprost inhibits superoxide formation and gp91phox expression induced by the thromboxane A2 analogue U46619, 8-isoprostane F2alpha, prostaglandin F2alpha, cytokines and endotoxin in the pig pulmonary artery

Since the roles of thromboxane A2 (TXA2), prostacyclin (PGI2) and 8-isoprostane F2alpha in mediating vascular O2*- formation and its relation to adult respiratory distress syndrome (ARDS) is unknown, the effects of these eicosanoids on the expression of gp91phox (catalytic subunit of NADPH oxidase) and O2*- release from cultured pig pulmonary artery (PA) segments, PA vascular smooth muscle cells (PAVSMCs) and PA endothelial cells (PAECs) were investigated. PA segments, PAVSMCs and PAECs were incubated with the TXA2 analogue, U46619, (+/-LPS, tumour necrosing factor-alpha (TNF-alpha) or IL-1alpha), 8-isoprostane F2alpha and+/-iloprost (a stable PGI2 analogue) for 16 h. The formation of superoxide dismutase-inhibitable O2*- was then measured spectrophotometrically and gp91phox expression assessed using Western blotting. In parallel experiments, whole PA segments were treated with LPS, TNF-alpha and IL-alpha after which time TXA2, PGI2, PGF2alpha and 8-isoprostane F2alpha formation was measured using enzyme-linked immunoassays. U46619, PGF2alpha and 8-isoprostane F2alpha promoted the formation of O2*- in PA segments, PAVSMCs and PAECs, an effect inhibited by diphenyleneiodonium and apocynin (both NADPH oxidase inhibitors) and upregulated the expression of gp91phox in PAECs and PAVSMCs. These effects were augmented by LPS, TNF-alpha and IL-1alpha but inhibited by iloprost. Under identical incubation conditions, IL-1alpha, LPS and TNF-alpha all induced an increase in the formation of TXA2, PGF2alpha and 8-isoprostane F2alpha but reduced the concomitant formation of PGI2. These data demonstrate that LPS and cytokines influence the relative balance of TXA2, PGI2, PGF2alpha and 8-isoprostane F2alpha in pig PA, which in turn alter NADPH oxidase expression and O2*- formation. These novel findings have implications in devising effective strategies for treating ARDS.British Journal of Pharmacology (2004) 141, 488-496. doi:10.1038/sj.bjp.0705626