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Biomedical subjects

E Pasini

Publications and source records attributed to E Pasini.

At least 73 records · Page 4Linked to original sources
PubMed1991

Role of timing of administration in the cardioprotective effect of iloprost, a stable prostacyclin mimetic.

We administered iloprost, a stable prostacyclin mimetic, 27 nM, to isolated and perfused rabbit hearts submitted, after 60 min of equilibration, to an ischaemic period (60 min at a coronary flow of 1 ml/min) followed by a period of reperfusion (30 min at a coronary flow of 25 ml/min). Iloprost was delivered at different times during the experimental protocol: 60 min before ischaemia, at the onset and after 30 min of ischaemia and only during reperfusion. The iloprost cardioprotective effect was evaluated in terms of recovery of left ventricular pressure developed during reperfusion, creatine phosphokinase (CPK) and noradrenaline release, mitochondrial function (expressed as yield, RCI (respiratory control index), QO2, ADP/O), ATP and creatine phosphate (CP) tissue contents, calcium homeostasis and by measuring several parameters of oxidative stress: reduced and oxidized glutathione release and tissue contents, Mn and Cu-Zn superoxide dismutase activities; glutathione reductase and peroxidase activities. Our data show that the cytoprotective action of iloprost is closely related to the time of administration. Optimal myocardial preservation was achieved when it was given before or at the onset of ischaemia. Iloprost administration 30 min after the onset of ischaemia was still beneficial, although to a lesser extent. Iloprost lost its protective effect when given only on reperfusion. The data suggest that the iloprost cardioprotective effect is related to maintainance of membrane integrity.

Adenosine Triphosphate↗
PubMed1991

The occurrence of oxidative stress during reperfusion in experimental animals and men.

Reperfusion is the prerequisite for the ischemic myocardium to recover its metabolic and mechanical function. However, reperfusion after a prolonged period of ischemia in the experimental animal may exacerbate, or at least accelerate, the occurrence of ischemic injury, whilst in humans at the least it is not beneficial. This entity has been called reperfusion damage, since much of the damage is believed to be caused by events occurring at the moment of reperfusion rather than by changes occurring during ischemia. The existence of reperfusion damage, however, has been questioned, and evidence in favour of the concept is sparse. At the moment the molecular events occurring at the time of reperfusion are not completely understood, and the relative importance of several proposed deleterious mechanisms is not yet established. One of the most fashionable ideas for the cause of reperfusion damage is that the function of cell membrane is modified by oxygen radicals generated at the moment of reperfusion. Evidence in favour of and against this hypothesis is described in detail in the present article.

Animals↗
PubMed1991

Effect of propionyl-L-carnitine on mechanical function of isolated rabbit heart.

We studied the acute and chronic effects of propionyl-L-carnitine (PLC) on mechanical function of isolated rabbit heart. Propionyl-L-carnitine was either directly delivered in the perfusate (10(-9) to 10(-3) M) or intraperitoneally injected (250 mg/kg) for 10 days to the animals. When added acutely, propionyl-L-carnitine had no effect on inotropism, heart rate, or coronary perfusion pressure. When added chronically, propionyl-L-carnitine induced a positive inotropic effect, with no changes in heart rate or in coronary perfusion pressure, and it ameliorated the pressure-volume relationship. This effect of propionyl-L-carnitine was independent of the calcium concentration of the perfusion medium, but it was correlated with an increase in the myocardial content of propionyl-L-carnitine. The effect was not apparent after 5 days of treatment, although the tissue content of propionyl-L-carnitine remained unchanged. These data suggest that propionyl-L-carnitine, when given chronically, exerts a positive inotropic effect.

Acetylcarnitine↗
PubMed1991

The effect of propionyl-L-carnitine on the ischemic and reperfused intact myocardium and on their derived mitochondria.

To assess whether propionyl-L-carnitine protects rabbit heart against the deterioration caused by ischemia and reperfusion, isolated hearts were infused with a medium containing it in different concentrations. During control, normoxic perfusion, and 60 minutes of low-flow ischemia (37 degrees C) followed by 30 minutes of reperfusion, diastolic, and developed pressures were monitored; coronary effluent was collected and assayed for lactate and creatine phosphokinase (CPK); mitochondria were harvested and assayed for oxidative phosphorylation and calcium content; and tissues for concentration of adenosine triphosphate (ATP) and creatine phosphate. Propionyl-L-carnitine reduced the ischemic deterioration of mitochondrial function and the depletion of tissue stores of ATP. On reperfusion, hearts treated with it recovered better than the untreated hearts with respect to left ventricular performance, replenishment of ATP and CP stores, and mitochondrial function. The reperfusion-induced mitochondrial calcium overload and release of CPK were also reduced. The effect of propionyl-L-carnitine was dose dependent. At 10(-8) M it failed to modify ischemic and reperfusion damage but protected well at 10(-7) M. No further protection was obtained at 10(-6) M. Propionyl-L-carnitine thus protects the myocardium against some of the deleterious effects of ischemia and reperfusion. In particular it protects mitochondrial function, perhaps partly by preventing mitochondrial calcium overload. Because this protection occurs in the absence of a negative inotropic effect during normoxia or of a coronary dilatatory effect during ischemia, it cannot be attributed to an energy-sparing effect or to the improvement of oxygen delivery.

Adenosine Triphosphate↗
PubMed1991

Role of oxygen free radicals in ischemic and reperfused myocardium.

In recent years there has been considerable interest concerning the role of oxygen radicals in myocardial ischemia and reperfusion injury. The sequential univalent reduction of oxygen gives rise to very reactive intermediate products. Normally, the tissue concentration of these intermediate products of oxygen is limited and the aerobic myocardium survives because of the existence of a delicate balance between the generation of the various oxidants and the maintenance of the antioxidant defense mechanism. Several possible sources have been identified for the production of active oxygen species after ischemia and reperfusion and these sources may be mutually interactive. The ability of scavengers of oxygen free radicals, including vitamin E, to improve mechanical, mitochondrial, and sarcoplasmic reticulum function in animal models of ischemic-reperfusion injury also suggests that oxygen free radicals are partly responsible for myocardial damage in these models, although caution in the interpretation of these data is necessary.

Animals↗
PubMed1991

Evaluation of phospholipid peroxidation as malondialdehyde during myocardial ischemia and reperfusion injury.

Peroxidation of membrane phospholipid polyunsaturated fatty acids is considered a major mechanism of the damage occurring on reperfusion of the myocardium after a prolonged period of ischemia. The evidence in support of this mechanism of damage is based on tissue malondialdehyde quantitation by the thiobarbituric acid test (TBA test). In an attempt to verify this topic, we have subjected isolated and Langendorff-perfused rabbit hearts to a period of 60 min of severe ischemia plus 30 min of reperfusion. At appropriate time points, malondialdehyde was determined in the tissue by means of TBA test and directly by reversed-phase, high-pressure liquid chromatography (HPLC). We have found no correlation between the two compared assays. During reperfusion, there was the formation of non-lipid-related, malondialdehyde-like, TBA-reactive substance that leads to overestimation of the extent of lipid peroxidation. On the contrary, by direct HPLC quantitation, there was a decrease of tissue malondialdehyde during ischemia and during the early phases of reperfusion. Our results demonstrate that TBA test is not a reliable index of lipid peroxidation in organ systems.

Animals↗
PubMed1991

[Is lipid peroxidation responsible for the damage caused by postischemic reperfusion?].

Peroxidation of membrane phospholipid polyunsaturated fatty acids is considered a major mechanism of the damage occurring during post-ischemic reperfusion. The evidences in support for this mechanism of damage are based on tissue malondialdehyde (MDA) quantitation by the thiobarbituric acid test (TBA-test). In an attempt to verify this topic we have subjected isolated and Langendorff perfused rabbit hearts to a period of 60 min of severe ischemia plus 30 min of reperfusion. At appropriate time points MDA was determined in the tissue by means of TBA-test and directly by reversed phase, high pressure, liquid chromatography (HPLC). We have found no correlation between the 2 compared assays. During reperfusion, there was the formation of non-lipid related, MDA like, TBA-reactive substance which leads to overestimation of the extent of lipid peroxidation. On the contrary, by direct HPLC quantitation, there was a decrease of tissue MDA during ischemia and during the early phases of reperfusion. Our results demonstrate that TBA-test is not a reliable index of lipid peroxidation in organ systems and that MDA accumulation does not precede the evidence of the functional alterations occurring on reperfusion of the previously ischemic myocardium. These results are of relevance in the understanding of the exact mechanism of reperfusion damage as, in the same experimental model, oxy radicals have been shown to be generated and antioxidants are protective.

Animals↗
PubMed1991

[Toxicity of fatty acids during myocardial reperfusion: a new possible mechanism of action].

To assess the value of myocardial substrate in the occurrence of ischemic-reperfusion damage, isolated, electrically paced rabbit hearts were perfused for 60 min under aerobic condition (25 ml/min with oxygenated Krebs-Henseleit solution containing glucose 11 mM). Thereafter the hearts were made ischemic for 30 min by reducing coronary flow to 3 ml/min. During ischemia, 3 different substrates were used glucose 11 mM (Group I), palmitate 1.2 mM (Group II) and palmitate 1.2 mM + glucose 11 mM (Group III). The hearts were then reperfused (25 ml/min) for 30 min under aerobic condition using glucose 11 mM as the only substrate. In the presence of glucose with or without palmitate (Group I and III) ischemic damage was mild. Recovery of the developed pressure was 95% and there was no contracture during ischemia and or reperfusion. During ischemia and reperfusion there was a small release of CPK, GSSG and GSH. In the presence of palmitate (Group II) ischemic and reperfusion damage was profound. Recovery of developed pressure was reduced (25%) and diastolic pressure significantly increased (68 +/- 5.1 vs 3 +/- 1.5, 5 +/- 1.8 mmHg). These mechanical data were concomitant with an important release of CPK (580 +/- 50 vs 180 +/- 35, 210 +/- 48 mU/min/gww) and oxidised glutathione (0.38 +/- 0.3 vs 0.05 +/- 0.001, 0.09 +/- 0.003 nmoles/min/gww). In addition the redox state of the cells of the Group II was significantly shifted through the oxidative state at the end of ischemia and of reperfusion. These results indicate that palmitate as substrate increases the deleterious effects of ischemia; glucose is able to overcome the negative effects of palmitate.

Aerobiosis↗
PubMed1990

Effects of anipamil on myocardial sarcolemmal and mitochondrial calcium transport, comparison with verapamil and nifedipine.

The calcium antagonists anipamil, verapamil and nifedipine inhibited, dose dependently, passive and ATP-driven 45Ca2(+)-uptake in purified rabbit ventricular sarcolemmal vesicles exposed to a wide range of free calcium concentration (from 0 to 200 microM). The IC50 values for passive binding were virtually identical for all calcium antagonists and the inhibition was relatively independent of the amount of free calcium employed. On the contrary, the order of potency for inhibition of the ATP-driven calcium uptake was: anipamil greater than verapamil greater than nifedipine. The inhibition of nifedipine, at free calcium concentrations lower than 80 microM, was preceded by a slight stimulation. The inhibitory effects of anipamil and verapamil, but not those of nifedipine, on the ATP-driven calcium uptake were more evident with increasing external calcium concentration. Verapamil and nifedipine failed to modify the initial rate of mitochondrial calcium transport either in the presence or in the absence of ADP; on the contrary, anipamil induced a dose-dependent inhibition of mitochondrial calcium transport. The inhibition occurred over the whole range of calcium concentrations tested, independent of the presence of ADP. The effects of anipamil, but not those of verapamil and nifedipine, on sarcolemmal and mitochondrial calcium transport were long lasting and survived membrane isolation.

Adenosine Triphosphate↗
PubMed1989

Oxygen free radical-mediated heart injury in animal models and during bypass surgery in humans. Effects of alpha-tocopherol.

There is evidence that oxygen free radicals play a role in myocardial ischemic and reperfusion injury. We investigated the effect of ischemia and reperfusion on glutathione status. Reperfusion after prolonged ischemia (60 min) induced an important release of reduced (GSH) and oxidized (GSSG) glutathione, concomitant with an increase of tissue GSSG and no recovery of mechanical function, indicating that reperfusion results in oxidative stress. These alterations are associated with tissue and mitochondrial calcium accumulation, loss of mitochondrial function, and membrane damage. We also determined the arteriocoronary sinus difference for GSH and GSSG of 16 CAD patients undergoing coronary artery bypass. Patients were divided in two groups according to the length of clamping period: 25 +/- 2 min (group 1), and 55 +/- 6 min (group 2). In group 1, reperfusion resulted in a transient release of GSH, GSSG, CPK, and lactate, with return to preclamping values in 10 minutes. In group 2, reperfusion determined a sustained and pronounced release of GSH, GSSG, CPK, and lactate during declamping, suggesting the occurrence of an oxidative stress. Using an in vitro model, administration of alpha-tocopherol bound with albumin showed protection of mitochondrial function, improved recovery of contraction, and reduced oxidative stress during reperfusion.

Animals↗
PubMed1989

Protective effects of gallopamil against ischemia and reperfusion damage.

To establish if the administration of gallopamil, a derivative of verapamil, protects heart muscle against the deleterious effect of ischemia and subsequent reperfusion, rabbits were injected subcutaneously twice daily with 2 mg/kg of Gallopamil for 5-6 days. The hearts were isolated and perfused with aerobic Krebs-Henseleit buffer solution by the Langendorff method. The hearts were paced (180 b/min) and wall temperature was controlled. Ischemia was induced by reducing coronary flow from 25 ml/min to 1 ml/min for 90 min and then the hearts were reperfused for 30 min. At the end of either the ischemic period or reperfusion, the hearts were assayed for ATP, CP, and calcium. Others were homogenized, their mitochondria harvested and monitored for oxidative phosphorylating and ATP generating activity as well as calcium content and uptake. The mechanical function of the hearts and noradrenaline release was also measured. Hearts that were made ischemic gained calcium, their endogenous stores of ATP and CP were depleted, their mitochondria had reduced RCI and state 3 respiration and increased calcium concentrations. During reperfusion tissue and mitochondrial calcium was significantly increased, the capacity of mitochondria to use oxygen for state 3 respiration was further impaired and their ATP generating capacity reduced. Diastolic pressure increased and there was no recovery of developed pressure and important noradrenaline release. Pretreatment with gallopamil protected the mitochondria against the ischemically induced changes in RCI, state 3 respiration. There was also a less marked rise in tissue and mitochondrial calcium and a reduced increase of diastolic pressure. Gallopamil also diminished the effect of reperfusion on the calcium accumulating activity of mitochondria and on the decline in the ATP generating and oxygen utilizing capacity of the mitochondria. The tissue levels of ATP and CP were better maintained, and noradrenaline release was reduced, the systolic pressure generating capacity was enhanced by the treatment with gallopamil. These results are discussed in accordance with the hypothesis that this drug protects heart muscle against the deleterious effects of ischemia and reperfusion by ensuring that sufficient ATP remains available to maintain homeostasis with respect to calcium.

Adenosine Triphosphate↗
PubMed1981

Results of combined chemosurgical therapy for pulmonary metastases.

The authors study the results of the combined surgery and postoperative chemotherapy, for treatment of pulmonary metastases. At Léon-Bérard Center, 50 patients have been operated on since 1963. The sites and histologies of the primitive cancers are varied, corresponding to 12 epidermoid cancers, 12 adenocarcinomas, 10 osteogenic sarcomas, 1 Ewing's tumor, 3 malignant melanomas, 6 testicular tumors, and 4 others. The total survival rate is 30% in 4 years. The prognosis is influenced by different factors, which are studied. It depends on the histology of the primitive cancer and the type of the pulmonary excision. It is suggested that postoperative chemotherapy improves the results. It appears that the longer the free interval is between the treatment of the primitive cancer and the discovery of the pulmonary metastasis, the better the prognosis. The correlation between the time lapse of the free interval and the survey after pulmonary excision is studied. The conclusions of the authors are: The association of surgery and chemotherapy improves the results and enforces the indications for surgical excision of pulmonary metastases.

Adenocarcinoma↗