New marker of colon cancer risk associated with heme intake: 1,4-dihydroxynonane mercapturic acid.

BACKGROUND: Red meat consumption is associated with an increased risk of colon cancer. Animal studies show that heme, found in red meat, promotes preneoplastic lesions in the colon, probably due to the oxidative properties of this compound. End products of lipid peroxidation, such as 4-hydroxynonenal metabolites or 8-iso-prostaglandin-F(2)alpha (8-iso-PGF(2)alpha), could reflect this oxidative process and could be used as biomarkers of colon cancer risk associated with heme intake. METHODS: We measured urinary excretion of 8-iso-PGF(2)alpha and 1,4-dihydroxynonane mercapturic acid (DHN-MA), the major urinary metabolite of 4-hydroxynonenal, in three studies. In a short-term and a carcinogenesis long-term animal study, we fed rats four different diets (control, chicken, beef, and blood sausage as a high heme diet). In a randomized crossover human study, four different diets were fed (a 60 g/d red meat baseline diet, 120 g/d red meat, baseline diet supplemented with heme iron, and baseline diet supplemented with non-heme iron). RESULTS: DHN-MA excretion increased dramatically in rats fed high heme diets, and the excretion paralleled the number of preneoplastic lesions in azoxymethane initiated rats (P < 0.0001). In the human study, the heme supplemented diet resulted in a 2-fold increase in DHN-MA (P < 0.001). Urinary 8-iso-PGF(2)alpha increased moderately in rats fed a high heme diet (P < 0.0001), but not in humans. CONCLUSION: Urinary DHN-MA is a useful noninvasive biomarker for determining the risk of preneoplastic lesions associated with heme iron consumption and should be further investigated as a potential biomarker of colon cancer risk.

Enzyme immunoassay for a urinary metabolite of 4-hydroxynonenal as a marker of lipid peroxidation.

Free radical reactions are involved in the pathogenesis of numerous diseases, so there is a real need to develop biomarkers that reflect these reactions in vivo. 4-Hydroxy-2-nonenal (HNE) is a major product of the lipid peroxidation process that is a consequence of free radical reactions. We present here the development and validation of an enzyme immunoassay (EIA) of the major urinary metabolite of HNE, namely 1,4-dihydroxynonane-mercapturic acid (DHN-MA). EIA allowed direct measurement of DHN-MA in rat urine with good sensitivity (0.02 ng/ml) and precision (intraassay CV = 5.7%). Recovery was complete (99-102%). Cross-reactivity was very low with 1,4-dihydroxynonene and with different mercapturic acids except with one other HNE urinary metabolite. Good correlation (EIA = 0.79 x LC/MS + 14.03, r = 0.877, p < 10(-8)) was obtained between EIA and liquid chromatography/mass spectrometry (LC/MS) quantitation when analyzing urine samples of rats with different oxidative status, due to treatment with either BrCCl(3) or trinitrobenzene sulfonic acid, which are known to induce hepatic lipid peroxidation or colon inflammation, respectively.

Dihydroxynonene mercapturic acid, a urinary metabolite of 4-hydroxynonenal, as a biomarker of lipid peroxidation.

The objective of our study was to compare the information obtained through the use of three different urinary biomarkers of lipoperoxidation during the time course of a bromotrichloromethane (BrCCl3) induced oxidative stress in rats. These biomarkers were malondialdehyde (MDA) measured by LC/MS after derivatization, the isoprostane 8-iso-PGF2alpha measured by enzyme immunoassay and 1,4-dihydroxynonene mercapturic acid (DHN-MA), the major 4-hydroxynonenal urinary metabolite [1], measured by LC-MS. Male Wistar rats received a single dose of 100 microL/kg BrCCl3 per os and lipid peroxidation was estimated every day for a 4-day-period after treatment. MDA, 8-iso-PGF2alpha and DHN-MA significantly increased in response to BrCCl3 treatment for this period of time, and DHN-MA showed the main increase during the 24-48 h period after treatment.

Role of capsaicin-sensitive afferent nerves in different models of gastric inflammation in rats.

Capsaicin-sensitive afferent nerves are described as being protective against gastric inflammation; their destruction leads to an exacerbation of inflammatory processes. However, these nerves have been shown to exert a pro-inflammatory action on stress-induced gastritis in rats. Our study aimed to investigate the role of capsaicin-sensitive afferent nerves in different experimental models of gastritis in rats. Functional ablation of sensory nerves was achieved by systemic capsaicin treatment (100 mg/kg). Gastritis was induced by mild (iodoacetamide, diquat, surgical duodeno-gastric reflux [DGR]) and strong (70% ethanol, indomethacin) inflammatory agents. Antagonists of the CGRP1 and NK1 receptors, hCGRP8-37 and SR140333, were administered in rats treated with iodoacetamide and ethanol. Macroscopic damage scores (MDS), myeloperoxidase (MPO) activity and malondialdehyde (MDA) concentration were evaluated after sacrifice. Macroscopic lesions appeared only in ethanol and indomethacin gastritis and were enhanced by capsaicin treatment. Gastric MPO activity was significantly increased by all agents compared to controls. Capsaicin treatment did not have any effect on MPO activity in indomethacin-treated rats or in rats submitted to surgery for duodeno-gastric reflux. However, it abolished the increase in MPO induced by iodoacetamide and diquat, and significantly enhanced that induced by ethanol. hCGRP8-37 and SR140333 abolished the increase in MPO activity and MDA concentration in iodoacetamide treated rats. In ethanol-treated rats, SR140333 diminished MPO activity. These results indicate that, depending upon the nature and duration of the experimental inflammation, capsaicin-sensitive afferent nerves may act differently to control gastric inflammatory processes, suggesting the involvement of a neurogenic component in some forms of gastric inflammation.