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Biomedical subjects

R Ferrari

Publications and source records attributed to R Ferrari.

At least 289 records · Page 16Linked to original sources
PubMed1992

Glutamate and GABA levels in CSF from patients affected by dementia and olivo-ponto-cerebellar atrophy.

The modifications in the CSF content of glutamate and GABA in patients afflicted with primary degenerative dementia (PDD) and olivo-ponto-cerebellar atrophy (OPCA) have been evaluated. Control subjects (with disk herniation) were also included in the study. The amino-acids assays were carried out utilizing enzymatic-bioluminescence technique. GABA levels in controls were 803 +/- 98 (n = 7) and in demented patients 702 +/- 98 (n = 7) pmol/ml. Glutamate levels were 2067 +/- 244 (n = 10) in controls, 1190 +/- 81 (n = 16) pmol/ml (vs controls p less than 0.01) in demented patients, and 1116 +/- 146 (vs controls p less than 0.01) in OPCA patients. These results suggest that CSF glutamate levels in severely demented patients might be a result of generalized neuronal loss in the brain with a reactive gliosis.

Age Factors↗
PubMed1992

Isoproterenol induces release of atrial natriuretic peptide from rat atrium in vitro.

To investigate the mechanism underlying the release of atrial natriuretic peptide (ANP) in in vitro condition, isolated, superfused rat atria were subjected to adrenergic, chronotropic, and mechanical stimulation. First administration of isoproterenol (Iso; either 10(-9) or 10(-6) M) caused a release of ANP, which was transient. Subsequent increments in concentration of Iso always resulted in a much lower release of ANP, despite the increased effects on the mechanical function of the atria. Stretching of the atria resulted in a transient release of ANP. Subsequent increments in stretching were followed by decreasing release of ANP. The total score of ANP in atrial tissue after Iso and stretching was not measurably depleted. Pacing the atria with increasing frequency did not induce release of ANP. Depolarization with 40 mM KCl abolished the release of ANP in response to Iso but not the release induced by stretch. In the presence of low external Ca2+, which abolished mechanical activity, both Iso and stretch could still induce release of ANP. Propranolol abolished the release of ANP by Iso but not that induced by stretching. Prazosin did not affect the release by either stretch or Iso. Stretching the atria 20 min after administration of Iso did not cause any further release of ANP. On the other hand, adding Iso 20 min after stretching induced a release of ANP. It is concluded that Iso and stretch cause a transient release from isolated strips of atria. The amount of ANP released is not related to the dose of Iso or to the load applied. Mechanisms involved in the release mediated by the two stimuli are different.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

PEG-SOD improves postischemic functional recovery and antioxidant status in blood-perfused rabbit hearts.

The isolated blood-perfused rabbit heart, subjected to 60 min of cardioplegic arrest and 60 min of reperfusion, was used to assess the effects of polyethylene glycol-conjugated superoxide dismutase (PEG-SOD) on postischemic recovery of left ventricular developed pressure (LVDP), the tissue activity of SOD, and tissue redox state. The five groups studied were the following: PEG-SOD-free control (group A), PEG-SOD as a pretreatment and as an additive during cardioplegia and reperfusion (group B), PEG-SOD as a pretreatment and a cardioplegic additive (group C), PEG-SOD in cardioplegia alone (group D), and PEG-SOD in reperfusion alone (group E). The results show that pretreatment with PEG-SOD improves postischemic recovery of LVDP (72 +/- 2% and 66 +/- 7 vs. 47 +/- 4% in groups B, C, and A, respectively). This protection was associated with an improved tissue redox state. Thus the ischemia-induced rise in oxidized glutathione was reduced from 313 +/- 26% (group A) to 162 +/- 15 and 138 +/- 14% (groups B and C, respectively), and the fall in reduced glutathione was attenuated from 51 +/- 5% to 35 +/- 6 and 13 +/- 5%, respectively. Tissue Mn-SOD activity was also conserved from 36 +/- 4% (group A) to 71 +/- 6 and 94 +/- 4% (groups B and C, respectively). No significant effect was seen when PEG-SOD was applied in cardioplegia or during reperfusion alone.

Animals↗
PubMed1992

Pathogenesis of congestive state in chronic obstructive pulmonary disease. Studies of body water and sodium, renal function, hemodynamics, and plasma hormones during edema and after recovery.

BACKGROUND: The pathogenesis of salt and water accumulation in patients with chronic obstructive pulmonary disease is unclear and may differ from that in patients with congestive heart failure due to myocardial disease. This study was undertaken to investigate some of the mechanisms involved. METHODS AND RESULTS: Hemodynamics, water and electrolyte spaces, renal function, and plasma hormone concentrations were measured in nine patients with edema due to chronic obstructive pulmonary disease and in six patients after recovery. Mean cardiac output (3.8 +/- 0.26 l/min.m2) was normal, but right atrial (11 +/- 1 mm Hg) and mean pulmonary arterial (41 +/- 3 mm Hg) pressures were increased. Mean pulmonary arterial wedge pressure (11 +/- 1 mm Hg) was normal. Pulmonary vascular resistance (8.6 +/- 1.3 mm Hg.min.m2/l) was increased, but systemic vascular resistance (19.3 +/- 1.3 mm Hg.min.m2/l) and mean arterial pressure (83 +/- 4 mm Hg) were low. All patients were hypoxemic (PaO2, 40 +/- 2 mm Hg) and hypercapnic (PaCO2, 60 +/- 2 mm Hg). There was a significant increase in total body water (+21%), extracellular volume (+45%), plasma volume (+45%), blood volume (+88%), and exchangeable sodium (+38.2%). Renal plasma flow was severely reduced (-63.2%), but glomerular filtration rate was only mildly decreased (-32%). Significant increases were seen in plasma norepinephrine (3.5-fold normal), renin activity (7.6-fold normal), vasopressin (twice normal), atrial natriuretic peptide (9.4-fold normal), growth hormone (10.7-fold normal), and cortisol (1.9-fold normal). After recovery, the PaO2 increased (50 +/- 3 mm Hg) and PaCO2 fell (45 +/- 4 mm Hg), and the patients became free from edema. All the body compartments returned toward normal, although they did not entirely reach normal values. Renal plasma flow increased significantly, and glomerular filtration became normal. Right atrial and pulmonary arterial pressures and pulmonary vascular resistance decreased (p less than 0.01). Cardiac output decreased but not significantly. Blood pressure increased but not significantly. However, systemic vascular resistance increased significantly to a normal value. CONCLUSIONS: We conclude that patients with edema due to chronic obstructive pulmonary disease have severe retention of salt and water, reduction in renal blood flow and glomerular filtration, and neurohormonal activation similar to that seen in patients with edema due to myocardial disease. However, unlike the latter, in chronic obstructive pulmonary disease cardiac output is normal, and systemic vascular resistance and arterial blood pressure are low. This probably is due to the vasodilator properties of hypercapnia. The consequent low arterial blood pressure may be the stimulus for the neurohormonal activation and retention of salt and water.

Adult↗
PubMed1992

Protection of the ischemic myocardium by the converting-enzyme inhibitor zofenopril: insight into its mechanism of action.

We assessed whether local inhibition of myocardial converting enzyme by captopril and zofenopril reduces the functional and metabolic damage caused by ischemia and reperfusion. First we investigated the effects of zofenopril and captopril on the mechanical function, cellular redox state, and norepinephrine (NE) content of isolated and aerobically perfused rabbit hearts. Both drugs failed to modify the myocardial redox state. At concentrations > 10(-6) M, zofenopril, but not captopril, caused a reduction in myocardial NE content. At 10(-4) M, both drugs caused a reduction in developed pressure and an increase in diastolic pressure and release of creatine phosphokinase (CPK). Second we investigated their effects on ischemic and reperfused myocardium. Both drugs exerted a cardioprotection; zofenopril was always more potent than captopril. Recovery of developed pressure on reperfusion improved, and peak release of NE was reduced, as was release of CPK. Calcium homeostasis and mitochondrial function were maintained. Captopril had no effect on occurrence of oxidative stress during reperfusion, whereas zofenopril reduced it. In hearts treated with the converting enzyme inhibitors, peak release of NE was correlated to mitochondrial calcium content, production of ATP, and recovery of mechanical function on reperfusion. These data suggest that the cardioprotective effect of zofenopril and captopril is independent of hemodynamic changes or reduction of the toxicity of oxygen free radicals and that it could be related to a reduction in release of NE.

Adenosine Triphosphate↗
PubMed1992

Stunned and hibernating myocardium: possibility of intervention.

There are several potential outcomes of myocardial ischemia. When ischemia is severe and prolonged, irreversible damage occurs and there is no recovery of contractile function. When myocardial ischemia is less severe but still prolonged, myocytes may remain viable but exhibit depressed contractile function. Under these conditions, reperfusion restores complete contractile performance. This type of ischemia, leading to a reversible, chronic left ventricular dysfunction, has been termed hibernating myocardium. The difference between this condition and that described before, i.e., prolonged ischemia, which results in further damage on reperfusion, is, most likely, related to residual coronary flow. In the hibernating myocardium, which is always supplied by a narrow coronary artery, blood flow is not low enough to cause progression toward tissue necrosis, but it is low enough to cause pH changes that, in turn, are responsible for the downregulation of myocardial contractility. The level of underperfusion is sufficient to maintain aerobic metabolism of the quiescient myocardium as demonstrated by the absence of lactate and creatine phosphokinase release. There are no doubts that revascularization is essential for hibernated myocardium, and the clinical goal to achieve is the possibility of accurately distinguishing viable from infarcted tissue. A third possible outcome of myocardial ischemia is a postischemic ventricular dysfunction or myocardial stunning. This term describes a transient mechanical dysfunction that persists on reperfusion after a short period of ischemia, despite the absence of irreversible damage. There are numerous clinical conditions in which stunning might manifest.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Hemodynamic and neuroendocrine profile of 2 different cardiovascular responses in vasodepressor syncope induced by the head-up tilt test].

BACKGROUND: Syncope in apparently healthy subjects is usually attributed to a vasovagal reaction. However, a vagal cardio-inhibitory component is not always associated with a vasodepressor component in causing syncope: in fact, increases in heart rate, arterial pressure and plasmatic levels of catecholamines frequently precede loss of consciousness. METHODS: Prolonged 60 degrees head-up tilt table test (HUTT) was performed in 50 healthy subjects (27 male, 23 female - mean age 37.2 years) with recurrent syncope of vasodepressor or unknown origin. The upright-tilt test lasted 45 minutes: every minute of HUTT we measured heart rate (HR) and systolic (SBP) and diastolic blood pressure (DBP); at set intervals we took a blood sample to determine epinephrine (EP) and norepinephrine (NEP) levels. RESULTS: In patients with positive HUTT (42%) we observed a vaso-vagal response (10 patients) characterized by a sharp drop in SBP and DBP (> 50% of the basal values) and bradycardia (< 40 bpm) and/or sinus node arrests, and a hyperchronotropic-vasodepressor response (11 patients) characterized by a considerable increase in HR (> 60%) and simultaneous drop in SBP and DBP (> 30% of the basal values), and a large increase in plasmal EP (+881.9%). CONCLUSIONS: According to the Authors, vasovagal response is mainly due to a reflex reaction originating from the cardiac stretch-receptors, whereas hyperchronotropic-vasodepressor response is mainly due to psychic stress and anxiety provoked by prolonged and forced posture during HUTT. The high levels of adrenergic activity and plasmal EP cause the excessive chronotropic response and the vasal effects of the syndrome. Due to the induction of a state of anxiety and its postural effects, HUTT is a useful provocative tool for complete evaluation of young patients with syncope of vasodepressor origin. We treated the patients differently, depending on how they responded to HUTT. Those with a vaso-vagal response were treated with alpha-sympathomimetic agents (ethylephrine or mydodrine) and those with a hyperchronotropic-vasodepressor response received non-selective beta-blockers. None of our patients had syncope recurrences during a mean follow-up of 12.3 months. Only two patients complained of dizziness; in one of them, symptomatology was abolished by an alpha-sympathomimetic beta-blocker association.

Adolescent↗
PubMed1992

Effect of propionyl-L-carnitine on experimental induced cardiomyopathy in rats.

The purpose of this study is to evaluate the ability of propionyl-L-carnitine, a carnitine derivative to prevent cardiac dysfunction induced by erucic acid and streptozotocin treatment in rats. Rats were fed for 10 days with normal or 10% erucic-acid-enriched diet with or without propionyl-L-carnitine injected intraperitoneally (1 mM/kg daily). Another group of rats was injected for 8-10 weeks with streptozotocin (65 mg/kg) with or without propionyl-L-carnitine intraperitoneally injected at the same dosage. Thereafter the animals were sacrificed and the hearts isolated and perfused aerobically. When isovolumic measurements of left ventricular function were applied, there was no difference in mechanical activity between treated and control hearts. On the contrary, when pressure-volume curves were determined in the paced hearts, the pressure developed by hearts from erucic acid-treated or diabetic rats was reduced. Propionyl-L-carnitine always produced positive inotropy. This was true for the control-saline treated rats that received the drug, as well as for the hearts isolated from cardiomyopathic animals. These data suggest that propionyl-L-carnitine, when given chronically, is able to overcome myocardial dysfunction caused either from erucic acid treatment or diabetes.

Animals↗
PubMed1992

The effects of L-arginine mono(2-mercaptoethanesulfonate) on the ischemic and reperfused heart.

We evaluated the effectiveness of L-arginine mono(2-mercaptoethanesulfonate) (argimesna) to limit the extent of myocardial damage resulting from 60 minutes of severe ischemia followed by 30 minutes of reperfusion in the Langendorff-perfused rabbit heart. Argimesna is a sulfhydryl group containing molecule which has no effect on glutathione status or on the total thiol pool. The effects of 10(-6) M argimesna were compared with those of 10(-6) M L-arginine and of 10(-6) M sodium salt of 2-mercaptoethanesulfonate (mesna). Pretreatment of the hearts with 10(-6) M argimesna resulted in marked myocardial protection, measured in terms of improved recovery of developed pressure (p less than 0.01), reduced release of creatine kinase (p less than 0.01), maintenance of mitochondrial function and increased stores of ATP on reperfusion (p less than 0.01). On reperfusion less oxidative stress developed, as indicated by less accumulation of oxidized glutathione (p less than 0.01). These effects were specific for argimesna; no significant protection could be found for mesna and L-arginine. The beneficial effects of argimesna could not be explained by hemodynamic differences or effects on anaerobic metabolism. Neither is it likely that argimesna acts as a free radical scavenger at the concentrations employed. The protection may be achieved by maintenance of -SH groups during ischemia and reperfusion.

Adenosine Triphosphate↗
PubMed1992

Importance of oxygen free radicals during ischemia and reperfusion in the experimental and clinical setting. Oxygen free radicals and the heart.

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 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. Evidence in favour of and against this hypothesis is described in detail in the present article.

Animals↗
PubMed1992

Effects of monocarboxylic and dicarboxylic acids on myosin ATPase activity tested by luminometric procedure.

L(+)Lactic acid enhances myosin ATPase in vitro. Different organic acids were tested for activation of myosin ATPase activity. L(+)Lactic is more effective in stimulating ATPase than D(-)Lactic. D(+) and L(-)Malic acids were also effective at the concentration of 2.5 x 10(-2)-5.0 x 10(-2) mmoles/l. At 3.0 x 10(-2) mmoles/l concentration the following acids are activators: acetic, oxalic, malonic, oxaloacetic, pyruvic, glyoxylic, glycolic; succinic is an inhibitor and acetoacetic is without effect. The activation is not in relation with the pKa of these acids. The inhibitory effects of organic acids are evident at the concentration of 5.0 x 10(-2) mmoles/l. This inhibitory effect is linearly increasing with their pKa. The results are discussed in connection with the possible role of these metabolites in controlling not only ATPase activity towards splitting of ATP, but also in controlling the removal of its hydrolytic products.

Animals↗
PubMed1992

Possible mechanisms of the protective effect of pretreatment with anipamil in ischemic-reperfused isolated rat hearts.

Rats were given anipamil (5 mg/kg) or glucose, intraperitoneally twice daily for 5 days. During this period the mean arterial blood pressure and heart rate were measured daily. The heart was then isolated and perfused. Energy metabolism and intracellular pH were monitored by 31P nuclear magnetic resonance spectroscopy during 30 minutes of ischemia followed by 30 minutes of reperfusion, with a simultaneous isovolumetric measurement of left ventricular contraction. Myocardial norepinephrine and glycogen were assayed immediately after excision of the heart, after 15 minutes oxygenated perfusion, at the end of ischemia and at the end of reperfusion. Metabolic and functional recovery during reperfusion were significantly better in hearts pretreated with anipamil (p less than 0.0005 vs controls). However, protection was not preceded by an effect on mean arterial pressure or heart rate in vivo, or a negative inotropic effect during control perfusion of the isolated hearts. There was no energy sparing effect during ischemia; but intracellular pH during ischemia stabilized at a higher level (p less than 0.0005 vs controls). Myocardial norepinephrine and glycogen stores were not decreased by pretreatment with anipamil, and their release or degradation due to ischemia and reperfusion were also not different from controls. Commonly known mechanisms of myocardial protection by calcium antagonists fail to explain the protection by pretreatment with anipamil as observed in our experiments, and alternative mechanisms are to be considered.

Animals↗
PubMed1992

Temporal relations of the endocrine response to hypotension with sodium nitroprusside.

Sodium nitroprusside was infused intravenously for 10 minutes in normal men, reclining at 45 degrees, in a dose sufficient to decrease the arterial pressure by 10 mmHg. The effect on a variety of plasma hormones was measured during the infusion and for 20 minutes afterwards. The heart rate increased to a maximum of 149%. Norepinephrine rose to a maximum of 196% in 5 minutes. Epinephrine reached a peak of 207% after 10 minutes. Plasma renin activity reached a peak of 449% at 10 minutes. Aldosterone did not change during the infusion, but increased to a maximum of 145% 10 minutes later. Vasopressin increased sharply at the end of the infusion to 893% and then rapidly decreased. Corticotropin, prolactin and growth hormone started to increase toward the end of the infusion, but reached their maxima during recovery. Corticotropin (225%) and prolactin (288%) peaked 10 minutes after the infusion, while growth hormone (414%) appeared still to be rising 20 minutes after the end of the infusion. Cortisol also rose progressively during recovery to a level of 138%. No significant changes were seen in the concentrations of insulin, glucagon, atrial natriuretic peptide, bombesin or neurotensin.

Adult↗
PubMed1991

Correlation between amount of retinal afferents to the pretectal nucleus of the optic tract and dorsal terminal accessory optic nucleus and performance of horizontal optokinetic reflex in rat.

Intraocular kainic acid injection in Long-Evans rats induces loss of retinal afferents to subcortical visual centers as assessed by the axoplasmic transport of [14C]valine. The optical terminal fields of the pretectal nucleus of the optic tract (NOT), superior colliculus and accessory optic system (AOS) nuclei appear particularly affected. Since NOT and the AOS dorsal terminal nucleus (DTN) represent the first relay station of the visuomotor pathway mediating horizontal optokinetic nystagmus (HOKR), we have studied the characteristics of HOKR after various degrees of retinal deafferentation of these nuclei induced by intraocular KA injection. Taking advantage of the arrangement of the primary optic projections to NOT-DTN, that in rats are almost entirely crossed, in each animal, monocular HOKR induced by stimulation of the injected eye was compared to monocular HOKR elicited by stimulation of the intact, ipsilateral eye. Following NOT-DTN optic denervation, HOKR gain always worsened, and in a way, that the greater the deficits of retinal afferents, the greater the HOKR inability to compensate for visual motion. Furthermore, for any given retinal denervation the higher the stimulus velocity, the greater the HOKR deficit. While the correlation between HOKR gain and the amount of retinal afferents to NOT-DTN would seem to indicate a functional homogeneity of the retinal ganglion cells sending axons to these nuclei, the finding that the extent of HOKR impairment also varied with velocity might not support the above view.

Animals↗
PubMed1991

Oxygen free radicals and myocardial damage: protective role of thiol-containing agents.

It has been suggested that the sudden presence of oxygen during reperfusion after a period of ischemia may be toxic for the myocardial cell. The oxygen molecule is capable of producing reactions in the cell, forming highly reactive free radicals, and inducing lipid peroxidation of membranes, altering their integrity and increasing their fluidity and permeability. The ischemic and reperfused cardiac cell is the prime candidate for this reaction sequence and may explain the molecular mechanism underlying the pathologic events related to membrane dysfunction and calcium homeostasis. However, the myocardium has a series of defense mechanisms including the enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase plus other endogenous antioxidants such as vitamin E, ascorbic acid, and cysteine to protect the cell against the cytotoxic oxygen metabolites. The prerequisite for oxygen free radical involvement in ischemia and reperfusion damage is that ischemia alters the defense mechanisms against oxygen toxicity. It is known that ischemia may impair mitochondrial SOD and, with reperfusion, oxidative stress may occur as shown by tissue accumulation and release of oxidized glutathione. This tripeptide molecule in the cofactor of glutathione peroxidase, the enzyme that removes hydrogen and lipid peroxides. Its formation and subsequent release is a reliable index of oxidative damage. In our study, we investigated the effects of N-acetylcysteine on oxidative damage in the isolated rabbit heart. N-acetylcysteine increases, in a dose-dependent manner (from 10(-7) to 10(-5) M), the myocardial glutathione content and provides an important degree of protection against ischemia and reperfusion. Oxidative stress does not occur, mitochondrial function is maintained, enzyme release is reduced, and contractile recovery is increased. Similarly, we administered N-acetylcysteine in the pulmonary artery of coronary artery disease patients undergoing coronary bypass grafting (150 mg/kg in 1 hour followed by 150 mg/kg in 4 hours). The degree of oxidative stress on reperfusion was reduced and recovery of cardiac function improved. In this article, we review the cardioprotective role of thiol-containing agents.

Animals↗