Effect of Glycine, Pyruvate, and Resveratrol on the Regeneration Process of Postischemic Intestinal Mucosa.

BACKGROUND: Intestinal ischemia is often caused by a malperfusion of the upper mesenteric artery. Since the intestinal mucosa is one of the most rapidly proliferating organs in human body, this tissue can partly regenerate itself after the onset of ischemia and reperfusion (I/R). Therefore, we investigated whether glycine, sodium pyruvate, and resveratrol can either support or potentially harm regeneration when applied therapeutically after reperfusion injury. METHODS: I/R of the small intestine was initiated by occluding and reopening the upper mesenteric artery in rats. After 60 min of ischemia and 300 min of reperfusion, glycine, sodium pyruvate, or resveratrol was administered intravenously. Small intestine regeneration was analyzed regarding tissue damage, activity of saccharase, and Ki-67 positive cells. Additionally, systemic parameters and metabolic ones were obtained at selected periods. RESULTS: Resveratrol failed in improving the outcome after I/R, while glycine showed a partial beneficial effect. Sodium pyruvate ameliorated metabolic acidosis, diminished histopathologic tissue injury, and increased cell proliferation in the small intestine. CONCLUSION: While glycine could improve in part regeneration but not proliferation, sodium pyruvate seems to be a possible therapeutic agent to facilitate proliferation and to support mucosal regeneration after I/R injury to the small intestine.

Immune stimulation by exogenous melatonin during experimental endotoxemia.

Melatonin has been shown to enhance the immune response under immune-compromised conditions. However, its immune-modulatory effects under inflammatory conditions are unclear at present. Both pro- and anti-inflammation has been reported. To study time-dependent effects of melatonin on the general immune response during endotoxemia in more detail, we used two models in male rats: per-acute endotoxemia was induced by lipopolysaccharide (LPS) bolus injection (2.5 mg/kg), sub-acute endotoxemia by LPS infusion (2.5 mg/kg × h). Melatonin was applied directly before and 2 h after LPS administration (3 mg/kg, each). The LPS-induced formation of the pro-inflammatory cytokines tumor necrosis factor alpha, interferon-gamma, interleukin (IL)-1α/ß, IL-5, and IL-6 and of the anti-inflammatory cytokine IL-10 was further amplified by melatonin, although it was only significant during per-acute endotoxemia. In both models, melatonin had no effect on the LPS-induced nitric oxide release. These findings show that exogenous melatonin is capable of enhancing the general immune response under inflammatory conditions.

Effects of glycine, pyruvate, resveratrol, and nitrite on tissue injury and cytokine response in endotoxemic rats.

BACKGROUND: Glycine, pyruvate, resveratrol, and nitrite are well-known protective compounds among others in ischemic tissue injury. Here, we compared their effects in acute lipopolysaccharide (LPS)-induced shock in rats to assess whether inhibition of the proinflammatory cytokine response is a prerequisite for their protective actions. MATERIALS AND METHODS: Rats (six or eight per group) were anesthetized, received LPS as an intravenous bolus (2.5 mg/kg), and were observed for 5 h. Glycine, sodium pyruvate, resveratrol, and sodium nitrite were continuously infused starting 30 min before LPS administration. Parameters included histopathologic changes, organ-specific cytokine levels, plasma nitrite and nitrate concentrations, and time courses of biomonitoring parameters, marker enzyme activities, and plasma cytokine concentrations. RESULTS: Glycine, pyruvate, resveratrol, and nitrite enhanced arterial blood pressure after LPS-induced shock. Also, parameters reflecting tissue ischemia were significantly improved and plasma markers of organ injury ameliorated by all substances. Of the plasma cytokine concentrations increased by LPS, some were differently decreased or even further increased by the substances. None of them reduced the elevated plasma nitrite and nitrate concentration. Glycine diminished the increases in tissue cytokine levels organ specifically, pyruvate decreased some cytokine concentrations in all organs, and nitrite significantly affected only a few cytokine concentrations in some organs, whereas the levels of many cytokines were raised by resveratrol. All substances except resveratrol decreased granulocyte infiltrates in the liver. CONCLUSIONS: The present results demonstrate that glycine, pyruvate, resveratrol, and nitrite protect against LPS-induced shock and tissue injury (cell death) in rats and suggest that inhibition of the proinflammatory cytokine response is not mandatory for their protective actions.

Free hemoglobin concentration in severe sepsis: methods of measurement and prediction of outcome.

INTRODUCTION: Hemolysis can be induced in sepsis via various mechanisms, its pathophysiological importance has been demonstrated in experimental sepsis. However, no data on free hemoglobin concentrations in human sepsis are available. In the present study we measured free hemoglobin in patients with severe sepsis as well as in postoperative patients using four methods. It was our aim to determine the potential value of free hemoglobin as a biomarker for diagnosis and outcome of severe sepsis in critical illness. METHODS: Plasma concentration of free hemoglobin was determined in patients with severe sepsis (n = 161) and postoperative patients (n = 136) on day 1 of diagnosis and surgery. For the measurement of free hemoglobin, an enzyme linked immunosorbent assay and three spectrophotometric algorithms were used. Moreover, SAPS II- and SOFA scores as well as procalcitonin concentration and outcome were determined. Kaplan-Meier analysis was performed and odds ratios were determined after classification of free hemoglobin concentrations in a high and low concentration group according to the median. For statistical evaluation the Mann-Whitney test and logistic regression analysis were used. RESULTS: In non-survivors of severe sepsis, free hemoglobin concentration was twice the concentration compared to survivors. Thirty-day survival of patients, as evidenced by Kaplan-Meier analysis, was markedly lower in patients with high free hemoglobin concentration than in patients with low free hemoglobin concentration. Best discrimination of outcome was achieved with the spectrophotometric method of Harboe (51.3% vs. 86.4% survival, p < 0.001; odds ratio 6.1). Multivariate analysis including free hemoglobin, age, SAPS II- and SOFA-score and procalcitonin demonstrated that free hemoglobin, as determined by all 4 methods, was the best and an independent predictor for death in severe sepsis (p = 0.022 to p < 0.001). Free hemoglobin concentrations were not significantly different in postoperative and septic patients in three of four assays. Thus, free hemoglobin can not be used to diagnose severe sepsis in critical illness. CONCLUSIONS: Free hemoglobin is an important new predictor of survival in severe sepsis.

Toluidine blue for the intraoperative staining of the ureters. Studies on the safe administration in rats.

PURPOSE: Acute cardiovascular events have repeatedly been reported to occur during the intraoperative presentation of the urinary tract with toluidine blue (TB). We here assessed the minimum TB dose required, and its safest and most suitable form of intravenous administration for the intraoperative staining of the ureters in rats. METHODS: TB (0.13, 0.4, 1.3, or 4.0 mg/kg) was administered to anesthetized rats either by intravenous injection within 1 min or by infusion within 10 min. During the experiments,biomonitoring parameters such as electrocardiograms (ECGs)and mean arterial blood pressure (MAP) were recorded,blood gas analysis was performed, and methemoglobin measured. Tissue injury was assessed from released plasma enzyme activities and histopathologically. The intraoperative staining of the ureters was documented photographically,and total urinary excretion and final urine/plasma TB concentrations were determined. RESULTS: Parameters of blood gas analysis, methemoglobin concentrations, and markers of tissue injury were slightly affected by the two highest TB doses but not at all by the lower ones. At doses of ≥0.4 mg/kg, ureters were stained sufficiently. Staining was more intense, and urine excretion of TB higher on average when the dye was injected.The 1-min injection of ≥1.3 mg TB/kg strongly and temporarily decreased the MAP, while the infusions caused lesser effects. Mean ECG parameters were not affected by any TB administration, but one animal developed a temporary bundle branch block after the 1-min injection of 4.0 mg/kg. CONCLUSIONS: In rats, intravenous injection of 0.4 mg TB/kg was sufficient for the intraoperative staining of the urinary tract without the risk of severe cardiovascular and hemodynamic side effects. Provided our results are transferable to humans, the administration of low TB doses could allow its safer clinical use for the intraoperative visualization of the ureters.