Effect of Tripeptide Leu-Ile-Lys on the Course of Experimental Nephrolithiasis.

We studied the effect of Leu-Ile-Lys tripeptide on the course of experimental oxalate nephrolithiasis modeled in rats by administration of 1% ethylene glycol solution instead of drinking water for 6 weeks. The Leu-Ile-Lys tripeptide obtained by chemical synthesis (purity ≥98%) was administered through a gastric tube (11.5 mg/kg in 1 ml saline). Administration of Leu-Ile-Lys tripeptide against the background of experimental oxalate nephrolithiasis significantly alleviated the course of experimental pathology, which was confirmed by typical biochemical and morphological changes: decrease in urinary activity of γ-glutamyltransferase (by 2.1 times in comparison with the initial level) and intensity of oxidative stress (the content of TBA-reactive products decreased by 1.3 times in comparison with that in untreated animals) and increase in glutathione peroxidase activity by 1.8 times; no histological signs of nephrolithiasis were found in animals treated with the tripeptide.

[Free radical oxidation-antioxidant defense system upon exposure to industrial chemical pollutants].

The paper gives the results of studying the free radical oxidation-antioxidant defense (FRO-AOD) system in the blood, saliva, and urine of workers from the petrochemical industry OAO "Salavatnefteorgsintez". The FRO-AOD system has been ascertained to be considerably changed in the plasma, tear, and urine of persons contacting a mixture of petrol and Grade BP-1 solvent with organic solvents and aromatic hydrocarbons and a mixture of 1,2-dichloroethane with chlorinated hydrocarbons under industrial conditions.

Urinary biomarkers of oxidative status in a clinical model of oxidative assault.

BACKGROUND: We used doxorubicin-based chemotherapy as a clinical model of oxidative assault in humans. METHODS: The study recruited newly diagnosed breast cancer patients (n = 23). Urine samples were collected immediately before (T0) and at 1 hour (T1) and 24 hours (T24) after i.v. administration of treatment. Measurements included allantoin and the isoprostanes iPF(2alpha)-III, iPF(2alpha)-VI, and 8,12-iso-iPF(2alpha)-VI along with the prostaglandin 2,3-dinor-iPF(2alpha)-III, a metabolite of iPF(2alpha)-III. All biomarkers were quantified using liquid chromatography-tandem mass spectrometry. RESULTS: In all subjects, the levels of the biomarkers increased at T1: allantoin by 22% (P = 0.06), iPF(2alpha)-III by 62% (P < 0.05), iPF(2alpha)-VI by 41% (P < 0.05), 8,12-iso-iPF(2alpha)-VI by 58% (P < 0.05), and 2,3-dinor-iPF(2alpha)-III by 52% (P < 0.05). At T24, the F2-isoprostanes returned to their baseline levels; the levels of allantoin continued to increase, although the T24-T0 difference was not statistically significant. CONCLUSIONS: These results indicate that urinary F2-isoprostanes are valid biomarkers and allantoin is a promising biomarker of oxidative status in humans. IMPACT: The levels of biomarkers change quickly in response to oxidative assault and can be used to monitor oxidative status in humans in response to treatments related either to generation of free radicals (chemotherapy and radiation therapy) or to antioxidants (inborn metabolic diseases and Down syndrome).

[Free radical oxidation and antioxidant defense upon exposure to organic solvents during production].

The paper presents the results of studies of free radical oxidation (FRO) and antioxidant defense (AOD) in the blood, oral fluid, and urine of petrochemical industrial workers. The red blood cell, plasma, oral fluid, and urine values of FRO and AOD has been ascertained to be much pronounced in persons contacting chemical pollutants during production.

Reduction of ciclosporin and tacrolimus nephrotoxicity by plant polyphenols.

The immunosuppressants ciclosporin (cyclosporin A, CsA) and tacrolimus can cause severe nephrotoxicity. Since CsA increases free radical formation, this study investigated whether an extract from Camellia sinensis, which contains several polyphenolic free radical scavengers, could prevent nephrotoxicity caused by CsA and tacrolimus. Rats were fed powdered diet containing polyphenolic extract (0-0.1%) starting 3 days before CsA or tacrolimus. Free radicals were trapped with alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) and measured using an electron spin resonance spectrometer. Both CsA and tacrolimus decreased glomerular filtration rates (GFR) and caused tubular atrophy, vacuolization and calcification and arteriolar hyalinosis, effects that were blunted by treatment with dietary polyphenols. Moreover, CsA and tacrolimus increased POBN/radical adducts in urine nearly 3.5 fold. Hydroxyl radicals attack dimethyl sulfoxide (DMSO) to produce a methyl radical fragment. Administration of CsA or tacrolimus with (12)C-DMSO produced a 6-line spectrum, while CsA or tacrolimus given with (13)C-DMSO produced a 12-line ESR spectrum, confirming formation of hydroxyl radicals. 4-Hydroxynonenal (4-HNE), a product of lipid peroxidation, accumulated in proximal and distal tubules after CsA or tacrolimus treatment. ESR changes and 4-HNE formation were largely blocked by polyphenols. Taken together, these results demonstrate that both CsA and tacrolimus stimulate free radical production in the kidney, most likely in tubular cells, and that polyphenols minimize nephrotoxicity by scavenging free radicals.

Acute encephalopathy with refractory status epilepticus: bilateral mesial temporal and claustral lesions, associated with a peripheral marker of oxidative DNA damage.

We describe a 12-year-old girl, who had been medicated with theophylline for bronchial asthma and developed acute encephalopathy with refractory status epilepticus, showing bilateral mesial temporal and claustral lesions, which were evident on fluid-attenuated inversion recovery images, obtained with 1.5 T magnetic resonance imaging. To date, oxidative stress has been implicated in aging or various disorders, including inflammatory or degenerative neurological disorders. One of the oxidative stress markers, 8-hydroxydeoxyguanosine, was increased in our patient's cerebro-spinal fluid, plasma and urine. We speculate that augmented oxidative stress was associated with refractory status epilepticus in our patient, accompanying bilateral mesial temporal, claustral lesions and severe neuronal damage. Serial measurements of oxidative stress markers in acute encephalitis, encephalopathy, or status epilepticus could clarify the relationships between acute brain damage and free radicals.

Correlative studies of urine fluorescence and free radical indicators.

AIMS: Inflammation results in the production of free radicals which damage proteins, lipids, and nucleic acids. The products of these reactions are cleared, in part, by the kidney and appear in the urine. In this study, urine fluorescence was measured in individuals with various nephropathies to determine the value of these assays for detecting the excretion of end products of radical-mediated chemical reactions. METHODS: Urine fluorescence was quantified at wavelengths which correspond to the presence of advanced glycosylation endproducts (AGE) and dityrosine (di-TYR). The samples were also tested for isoprostanes, nitrite/nitrate, hydrogen peroxide, and thiobarbituric acid reactive substances (TBARS). RESULTS: Fluorescence values, expressed per ml urine or per mg creatinine (crt), were not normally distributed and covered a wide range. There were significant differences in fluorescence among groups of patients classified by diagnosis, but the differences did not allow sharp distinction of diagnostic categories. Fluorescence assays correlated significantly with TBARS but not with isoprostanes, nitrite/nitrate, or hydrogen peroxide. Fluorescence tended to increase with age. Gender and race did not affect the results. CONCLUSIONS: Because of the many factors which can affect free radical production and tissue injury, the value of urine fluorescence assays to screen for radical-mediated toxicity appears to be limited. Serial studies of patients will be needed to determine whether urine fluorescence will be useful to monitor responses to treatment or be predictive of progression vs. remission of renal disease.

Xanthine oxidase activation in mild gestational hypertension.

OBJECTIVE: We hypothesized that activation of the xanthine oxidase (XO) enzyme system is a potential source of free radicals in pregnancy-induced hypertension (PIH). METHODS: A prospective observational study was carried out on 16 pregnant women who met the criteria of gestational hypertension [rise in blood pressure (BP) of 30 mm Hg systolic or 15 mm Hg diastolic after 20 weeks gestation or BP>140/90 mm Hg if earlier pressure is unknown] without proteinuria or any signs of renal impairment. Fourteen women with a clinically normal pregnancy matched for maternal age, parity, and gestational age acted as pregnant controls. Nonpregnant control women were members of the laboratory staff ( n=15). MAIN OUTCOME MEASURES: Concentrations of free sulfhydryl (SH) groups, purine catabolites, lipid peroxidation products in plasma, and blood carboxyhemoglobin levels were used to follow oxidative stress and potential hemolysis. A noninvasive measurement of functional XO activity was carried out (i.e., the urinary ratio of the two metabolites of caffeine was estimated). RESULTS: A pronounced oxidative stress was demonstrated in plasma samples of patients with hypertension by the elevated concentrations of uric acid and lipid peroxidation products. A reduced level of free sulfhydryl groups and an increased concentration of hypoxanthine (HX) were shown in normotensive pregnant individuals. The XO activity index was substantially higher in overweight pregnant subjects with mild hypertension [0.849+/-0.096 ( p<0.01)] than in normotensive pregnant women or in age-matched nonpregnant subjects [0.596+/-0.105, 0.542+/-0.049 (means+/-SD), respectively]. CONCLUSIONS: Our study of mildly hypertensive pregnant subjects provides additional evidence of the putative role of XO activation as a source of free radicals in the early stage of endothelial dysfunction.

Protective effect of glycine on renal injury induced by ischemia-reperfusion in vivo.

Although glycine prevents renal tubular cell injury in vitro, its effect in vivo is not clear. The purpose of this study was to investigate whether a bolus injection of glycine given before reperfusion plus continuous dietary supplementation afterward would reduce renal injury caused by ischemia-reperfusion. Female Sprague-Dawley rats received a semisynthetic powdered diet containing 5% glycine and 15% casein (glycine group) or 20% casein (control group). Two days later, renal ischemia was produced by cross-clamping the left renal vessels for 15 min, followed by reperfusion. The right kidney was removed before reperfusion. The postischemic glomerular filtration rate (GFR) showed that renal function was less impaired and recovered more quickly in rats receiving glycine. For example, at day 7, GFR in controls (0.31 +/- 0.03 ml x min(-1) x 100 g(-1)) was about one-half that of glycine-treated rats (0.61 +/- 0.06 ml x min(-1) x 100 g(-1), P < 0.05). Furthermore, tubular injury and cast formation observed in controls was minimized by glycine (pathology score, 3.2 +/- 0.4 vs. 1.0 +/- 0.4, P < 0.05). Urinary lactate dehydrogenase (LDH) concentration was elevated by ischemia-reperfusion in the control group (260 +/- 22 U/l), but values were significantly lower by about fourfold (60 +/- 30 U/l) in glycine-fed rats. Similarly, free radical production in urine was significantly lower in glycine-treated animals. Importantly, on postischemic day 1, binding of pimonidazole, an in vivo hypoxia marker, was increased in the outer medulla in controls; however, this phenomenon was prevented by glycine. Two weeks later, mild leukocyte infiltration and interstitial fibrosis were still observed in controls, but not in kidneys from glycine-treated rats. In conclusion, these results indicate that administration of glycine indeed reduces mild ischemia-reperfusion injury in the kidney in vivo, in part by decreasing initial damage and preventing chronic hypoxia.

[The state of free-radical oxidation in workers engaged in oil-processing industry]. / Sostsoianie svobodno-radikal'nogo okisleniia u rabochikh neftepererabatyvaiushchei promyshlennosti.

The author represent evaluation of free-radical oxidation in RBC, serum and urine among workers engaged into pyromellitic dianhydride. Individuals contacting chemical pollutants during pyromellitic dianhydride production de monstrate significant changes in free-radical oxidation parameters of RBC, serum and urine.

Ethylene glycol generates free radical metabolites in rats: an ESR in vivo spin trapping investigation.

Ethylene glycol, best known as antifreeze, is most often ingested accidentally or as a substitute for alcochol by chronic alcohol abusers. The toxicity of ethylene glycol poisoning is due to its toxic metabolites rather than to ethylene glycol itself. In this study, electron spin resonance (ESR) spectroscopy has been used to study free radical generation in rats by acute ethylene glycol poisoning. The radical spin trapping technique was applied where the spin trapping agent alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) reacted with free radical metabolites to form radical adducts in vivo. The radical adducts from ethylene glycol intoxication were detected in both the bile and urine samples of male Sprague-Dawley rats. The identification of the POBN-(.)[(13)C]ethylene glycol radical adduct provides for the first time direct ESR evidence for the generation of the ethylene glycol-derived radicals during acute intoxication by ethylene glycol, suggesting a new metabolic pathway. Simultaneous administration of alcohol dehydrogenase inhibitor 4-methylpyrazole with ethylene glycol resulted in an enhanced free radical generation in the bile. This report is the first evidence of ethylene glycol free radical metabolism in rats with acute ethylene glycol intoxication.

[Energy metabolism of free-radical and microsomal oxidation in workers engaged into oil-processing industry]. / Energeticheskii obmen cvobodnoradikal'nogo i mikrosomal'nogo okisleniia v organizme rabotnikov neftgepererabatyvaiushchei promyshlennosti.

The authors present data on disorders of energy metabolism in erythrocytes, of microsomal monooxygenases and of free-radical oxidation in blood and urine of workers engaged into oil-processing industry. Studies revealed considerable changes in RBC adenyl system parameters, in chemiluminescence of blood and urine, in monooxygenase system. Nonspecific therapy in sanatorium appears to better these aspects.

Dietary glycine and renal denervation prevents cyclosporin A-induced hydroxyl radical production in rat kidney.

Cyclosporin A (CsA) nephrotoxicity is associated with renal hypoxia and increases in free radicals in the urine. This study was designed to elucidate the mechanism of radical production caused by CsA. Pretreatment of rats with CsA (25 mg/kg, i.g.) for 5 days decreased glomerular filtration rates by 65%, an effect largely prevented by both dietary glycine (5%) or renal denervation. CsA dissolved in olive oil produced a 6-line alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN)/free radical signal in the urine, which partitioned predominantly into the aqueous phase after chloroform extraction (i.e., it is water soluble). Dimethyl sulfoxide (DMSO) is attacked by the hydroxyl radical to produce a methyl radical; administration of CsA with [(12)C]DMSO produced two radical species in urine, one with hyperfine coupling constants similar to the 4-POBN/methyl radical adduct found in aqueous solution. CsA given with [(13)C]DMSO produced a 12-line spectrum, confirming the formation of hydroxyl radicals. The methyl radical produced by the hydroxyl radical represented 62% of radicals detected in urine but only 15% in bile. Therefore, hydroxyl radicals are produced largely in the kidney. Free radicals in urine were increased about 5-fold by CsA, an effect completely blocked by the inhibitory neurotransmitter, glycine, or by renal denervation. CsA infusion for 30 min increased efferent renal nerve activity 2-fold, and dietary glycine (5%) totally blocked this phenomenon. Taken together, these data are consistent with the hypothesis that CsA increases hydroxyl radical formation by increasing renal nerve activity resulting in vasoconstriction and hypoxia-reoxygenation. Glycine blunts the effect of CsA on the renal nerve, which explains, in part, prevention of nephrotoxicity.

Comparison of urinary and plasma malondialdehyde in preterm infants.

The measurement of malondialdehyde (MDA) in biological fluids remains a popular method for the quantification of free radical damage to lipids in vivo. Several diseases of prematurity are thought to be related to oxidative injury and previous studies have found elevated MDA in plasma and urine in preterm infants. Our aim was to investigate the relationship between plasma and urinary MDA levels in preterm infants during the first week of life using a high-performance liquid chromatography (HPLC) based, thiobarbituric acid (TBA) assay with paired plasma and urine samples. We obtained 50 paired samples, and were unable to demonstrate a relationship between the two parameters after the first day of life. In 18 cases a further urine sample was collected 24 h later. There was a positive correlation (r = 0.54, P = 0.02) between plasma MDA and urinary MDA 24 h later. The finding that plasma changes in MDA are reflected in urine 24 h later validates the use of urinary MDA as a marker of whole body lipid peroxidation in populations without renal disease.

Pharmacokinetic analysis of free radicals by in vivo BCM (Blood Circulation Monitoring)-ESR method.

In pharmacokinetic studies, a variety of analytical method including radioisotopic detection and HPLC (high performance liquid chromatography) has been used. In the present investigation, we developed in vivo BCM (Blood Circulation Monitoring)-ESR method, which is a new technique with a conventional X-band ESR spectrometer for observing stable free radicals in the circulating blood of living rats under anaesthesia. Both 5-(PROXYL derivatives) and 6-(TEMPO d derivatives) membered nitroxide spin probes with various types of substituent functional group were used. After physico-chemical properties of the spin probes such as hyperfine coupling constant (A-value), g-value and partition coefficient as well as chemical stability of the compounds in the fresh blood were obtained, the in vivo BCM-ESR method was performed in normal rats. Several pharmacokinetic parameters such as half-life of the probes, distribution volume, total body clearance and mean residence time were obtained and discussed in terms of their chemical structures. In addition, clearance of a spin probe was related to the urine concentration. The BCM-ESR method was found to be very useful to observe free radicals at the real time. By time-dependent ESR signal decay of spin probes, pharmacokinetic parameters were obtained.

Increased levels of malondialdehyde in urine and plasma from diabetic patients and smokers: evidence for free radical damage - abstract

Malondialdehyde [MDA] is a major end product of lipid peroxidation which causes tissue damage and its presence is often used as an indicator for free radical damage in tissues. MDA was therefore measured in the urine and plasma of 15 non-insulin dependent diabetics (NIDDM) between the ages of 33 and 67 (mean 52) years, 10 chronic smokers 29 - 33 years old and control group of 14 healthy individuals 17 to52 years old. The average age of both the normal controls and smokers was 32 years with an average Body Metabolic Index (BMI) of 24 in both groups and 26 in the diabetic group. (A table showing mean + SEM values for urinary and plasma malondialdehyde is shown in abstract). We conclude that diabetics and smokers have significantly (p<0.008) higher levels of urinary MDA than the controls. Plasma MDA levels were only significantly higher for the diabetic group. When corrected for muscle mass and BMI, urinary MDA levels for the two test groups were sigificantly (p<0.001) higher than normal. There was a good correlation between urinary MDA and plasma MDA (r=0.74), p<0.001, df= 21. These data suggest (1) NIDM and smokers have increased exposure to free radical damage (2) urinary MDA provides a good indicator of lipid peroxidation. (AU)

[Urinary tests for inflammation in glomerulonephritis]. / Mochevye testy vospaleniia pri glomerulonefrite.

Boyden camera tests, chemiluminescence of urinary supernatant, passive hemagglutination tests were used in measuring chemotactic properties of the urine, intensity of free-radical processes, fibronectin urine concentrations, respectively, in 31 glomerulonephritis (GN) patients. The above parameters were closely related to nephritis activity. These were much lower in patients with nephritis remission, than in subjects with nephrotic syndrome or exacerbation of latent nephritis. Chemotactic activity and intensity of free-radical processes were unrelated to protein urea which, however, correlated with fibronectin concentrations (r = 0.35, p < 0.05). The authors discuss the role of the mediators' values in evaluation of local renal inflammation and feasibility of their use as criteria of nephritis activity and prognosis.