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S Pietri

Publications and source records attributed to S Pietri.

26 records · Page 2Linked to original sources
PubMed1990

Ascorbyl free radical as a reliable indicator of free-radical-mediated myocardial ischemic and post-ischemic injury. A real-time continuous-flow ESR study.

The real-time kinetics of the release of ascorbyl free radicals in the coronary perfusate from isolated rat hearts submitted to an ischemia/reperfusion sequence has been achieved by continuous-flow ESR using high-speed acquisition techniques. Enhanced ESR detection of ascorbyl free radicals was obtained by addition of dimethyl sulfoxide (Me2SO), a strong cation chelator and oxidizing agent. A continuous-flow device allowed a direct monitoring of the ascorbyl free radical and/or ascorbate leakage in coronary perfusate by observation of the ascorbyl radical doublet (aH = 0.188 mT and g = 2.0054). 1. The results showed that ascorbyl free radical release occurred mainly during sequences of low-flow ischemia (90 min) coupled or not with 30 min of zero-flow ischemia followed by reperfusion (60 min). The kinetic profiles of ascorbyl-free-radical detection confirm in quantitative terms the expected correlation between the duration of the ischemic insult and the magnitude of ascorbate extracellular release upon reperfusion. There is indication that ascorbyl free radical depletion could be secondary to oxygen-derived-free-radical-induced cellular damage. 2. The amount of residual ascorbic acid was quantitated on myocardial tissue at the end of reperfusion using Me2SO as extracting solvent. Intense oxidation of ascorbate and chemical stabilization of the resulting free radical species provided by Me2SO allowed ESR measurement of a marked tissue ascorbate depletion related to the duration of ischemia. 3. Perfusion of superoxide dismutase during low-flow ischemia and the first 10 min of reperfusion greatly inhibited both extracellular release and endogenous ascorbate depletion. These results suggest that the ascorbate redox system constitutes a major protective mechanism against free-radical-induced myocardial injury. 4. The proposed direct ESR detection of ascorbyl free radicals in the coronary perfusates or in tissue extracts does not require extensive chemical preparation and conditioning of effluent or tissue samples. It provides an interesting straightforward alternative to the evaluation of detrimental free radical processes affecting the myocardium during ischemia and reperfusion.

Animals↗
PubMed1989

Real-time continuous-flow spin trapping of hydroxyl free radical in the ischemic and post-ischemic myocardium.

Real-time monitoring of spin-trapped oxygen-derived free radicals released by the isolated ischemic and reperfused rat heart has been achieved by ESR analysis of the coronary effluents using continuous flow detection and high-speed acquisition techniques. Two nitrone spin traps 5,5-dimethyl pyrroline 1-oxide (Me2PnO) and 3,3,5,5-tetramethyl pyrroline 1-oxide (MePnO) have been separately perfused at a concentration of 40 mM during a sequence of 50 min of low-flow ischemia (1 ml/min) followed by 30 min of global ischemia and subsequent reperfusion at the control flow rate (14 ml/min). ESR spectra were sequentially obtained in 5-min or 30-s blocks during low-flow ischemia and reperfusion, respectively. 1. The results show the formation of OH. free radicals in the ischemic and reperfused heart, as demonstrated by the observation of Me2PnO-OH (aN = aH = 14.9 G; g = 2.0053) and Me4PnO-OH (aN = 15.2 G, aH = 16.8 G; g = 2.0055) spin adducts. There is no evidence of significant biological carbon-centered or peroxyl free radicals spin-adduct formation in the coronary effluents or in lipid extracts analyzed after reflow. 2. The OH. generation began 15-20 min after the onset of ischemia and was moderate, peaking at 30-40 min. During reperfusion, an intense formation of OH. spin adducts was observed, with a maximum at 30-60 s and a further gradual decrease over the following 2 min. 3. Cumulative integrated values of the amount of spin adducts released during the ischemic period show a Me2PnO-OH level fourfold greater than that of Me4PnO-OH. It was 2.5 times greater during reflow, reflecting slower kinetics with the more stable Me4PnO. 4. The original ESR detection technique developed in this study allows accurate real-time quantitative monitoring of the oxygen-derived free radicals generated during myocardial injury. It might provide a quick and reliable new means for assessing the efficacy of free-radical inhibitors.

Animals↗
PubMed1989

Use of 3,3,5,5-tetramethyl-1-pyrroline-1-oxide spin trap for the continuous flow ESR monitoring of hydroxyl radical generation in the ischemic and reperfused myocardium.

A new approach for in vivo spin trapping and quantitation of oxygen-derived free radicals has been developed using a continuous flow high speed ESR detection system. Spin adducts of OH. were detected as 1:1:1:1:1:1 sextets (aN=15.2 G, aH=16.8 G, g=2.0055) in the isolated rat heart when perfused with 3,3,5,5-tetramethyl-1-pyrroline-1-oxide (40 mM) during a 10-min control pretreatment (14 ml/min) followed by 50 min of low-flow ischemia (1 ml/min), 30 min of global ischemia and subsequent reperfusion at 14 ml/min. The ESR signals appeared within 15-20 min of low-flow ischemia and grew moderately during the remaining 30 min at a rate of 2-6 nmoles of spin adduct released per minute. Post-ischemic reperfusion was characterized by a burst of spin adduct formation at 30 s-1 min, corresponding to 51.8 nmoles of spin adduct released between 30 s and 1 min.

Animals↗
PubMed1984

Antenatal diagnosis of haemoglobinopathies by improved method of isoelectric focusing of haemoglobins.

An improved method of isoelectric focusing (IEF) of haemoglobins, utilizing a spacer molecule to increase the separation between HbA and acetylated HbF, was carried out in parallel with carboxymethylcellulose (CMC) chromatography in 85 antenatal diagnoses for haemoglobinopathies (mainly thalassaemia). In 19 of 21 affected fetuses no HbA band was detectable on IEF while in two a very faint band was observed; in heterozygotes or normal fetuses a more obvious HbA band was present. Moreover, IEF was useful for the demonstration of HbLepore in two cases at risk for beta-thalassaemia/ HbLepore and for interpreting a radioactive pre-beta globin peak on CMC chromatography. Pure fetal blood is needed for IEF. It can therefore be used for most cases in centres using fetoscopy for fetal blood sampling. About 80% of antenatal diagnosis of haemoglobinopathies may be carried out by IEF which is a very simple, rapid and inexpensive method.

Female↗
PubMedDate not supplied

[Prenatal diagnosis of hemoglobinopathies in the 1st and 2nd pregnancy trimesters].

Fetal diagnosis of haemoglobinopathies, mainly thalassaemia, is widely used for the prevention of these diseases. Since 1975 fetal diagnosis has been carried out in the second trimester of pregnancy (18th - 22th week) on fetal blood samples obtained by fetoscopy or placentocentesis. The biochemical technique most commonly employed has been represented by carboxymethylcellulose chromatography and more recently in our center by isoelectric focusing of haemoglobins which is a faster and cheaper technique. First-trimester fetal diagnosis is now feasible by DNA analysis on chorionic villi. The Milan center experience in second trimester fetal diagnosis of haemoglobinopathies on more than 300 cases and the preliminary data on first trimester diagnosis are reported.

Blood Specimen Collection↗