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M Brunelli

Publications and source records attributed to M Brunelli.

At least 37 records · Page 2Linked to original sources
PubMed1995

Repetitive treatment with serotonin modifies protein synthesis and protein phosphorylation in the central nervous system of Hirudo medicinalis.

Serotonin (5HT) is the neurotransmitter involved in some forms of short-term memory in the leech. Behavioral experiments have demonstrated that long-term memory requires new protein synthesis. With the aim of studying the molecular mechanism underlying memory processes in the leech, we have analyzed the effect of 5HT on protein synthesis and protein phosphorylation. Segmental ganglia of the leech central nervous system have been labeled, proteins have been separated by two-dimensional-electrophoresis and labeled proteins detected by autoradiography. Our findings indicate that repetitive treatment with 5HT produces either the persistence of phosphorylation or changes in protein synthesis in several proteins.

Alkaloids↗
PubMed1995

Octopamine and Leydig cell stimulation depress the afterhyperpolarization in touch sensory neurons of the leech.

In touch sensory neurons of the leech, a train of spikes evoked by intracellular electrical stimulation leads to an afterhyperpolarization, mainly due to the activation of the Na+/K+ electrogenic pump and partly to a Ca(2+)-activated K+ conductance. It has been found that serotonin is able to reduce the afterhyperpolarization through the inhibition of the Na+/K+ electrogenic pump. We have investigated the possible modulation of the afterhyperpolarization by other endogenous neurotransmitters and we have found that octopamine is also able to reduce its amplitude. The electrical stimulation of the octopaminergic Leydig neurons mimics this effect. We have compared the actions of the two amines and found that the effect of serotonin is blocked by methysergide but not by high [Mg2+] or by phentolamine, and it is still present in touch cells isolated in culture. On the contrary, the octopamine modulation of the afterhyperpolarization does not occur in single touch cells in culture and it is blocked by all these treatments. These data suggest that while serotonin should act monosynaptically, octopamine should act through a serotonergic pathway.

Animals↗
PubMed1994

Interleukin-1 and interleukin-6 modify protein phosphorylation in the central nervous system of Hirudo medicinalis.

Recent data suggest that IL-1-like molecules have been conserved during evolution. The signal transduction mechanism of IL-1 is not known, but kinase activation has been reported. With the aim of studying if human IL-1 has any effect on the leech nervous system, we have added this cytokine to segmental ganglia labeled with [32P]ortophosphoric acid; proteins have been separated by electrophoresis and phosphoproteins detected by autoradiography. In the present paper we show that human IL-1 and IL-6 are able to induce changes on protein phosphorylation in the leech central nervous system and that these changes are similar to those ones induced by the neurotransmitter serotonin.

Animals↗
PubMed1994

The beta-carboline derivative DMCM decreases gamma-aminobutyric acid responses and Ca(2+)-mediated K(+)-conductance in rat neocortical neurons in vitro.

Electrophysiological recordings from neurons of rat frontal neocortical slices have been used to investigate the action of the beta-carboline methyl-6,7-dimethoxy-4-ethyl-beta- carboline-3-carboxylate (DMCM), on responses to gamma-aminobutyric acid (GABA) and on the excitability of the neurons. Iontophoretic application of GABA close to the intracellularly recorded cells (resting membrane potential -74 +/- 0.9 mV) elicited a depolarization associated with a decrease of input resistance, mediated by GABAA receptors. Bath application of DMCM (0.1-1 microM) reduced these GABA responses decreasing the affinity of the receptors for GABA. This effect was blocked by the benzodiazepine receptor (BZR) antagonist ZK 93426 (1 microM). DMCM (0.1 microM) also decreased the hyperpolarization that followed a train of action potentials (AHP), mediated by Ca(2+)-dependent K+ conductance, and increased the duration of Ca(2+)-dependent action potentials recorded after blockade of Na+ and K+ conductances. Neither effect was blocked by BZR antagonists. These results indicate that DMCM increases the excitability of neurons not only by reducing the gain of the GABAA/BZR complex, but also by modulating intrinsic membrane mechanisms.

Action Potentials↗
PubMed1994

The coronary subclavian steal syndrome: an uncommon sequel to internal mammary-coronary artery bypass surgery.

Coronary subclavian steal syndrome is a possible sequel in patients who have undergone myocardial revascularization with an internal mammary artery. We report a case of this syndrome in a 67-years-old man. In 1990 he underwent a quadruple bypass: aorta-obtuse margin, aorta-right coronary (two sequential), internal artery mammary-descending coronary artery. Three months later he started to have angina pectoris. In April 1992 an aortic arch angiography and a coronary angiography were performed. The examination showed an occlusion of the left subclavian artery at its origin. The artery was opacified countercurrently by the left vertebral artery but the left mammary artery was not opacified. Left coronary angiography showed a very severe disease of left anterior descending coronary artery and retrograde flow through the anastomosis in the left mammary artery. The patient underwent a left common carotid-subclavian artery bypass operation using a 6 mm vascutex graft. Eighteen months later the patient is doing well without angina pectoris and with very little alteration of the perfusion in the left frontal lobe observed by SPECT neuroimaging with a lipophilic tracer (99mTc-HMPAO). We think that the coronary-subclavian steal syndrome can be treated successfully with low risk by means of common carotid-subclavian artery bypass.

Aged↗
PubMed1993

Effect of serotonin on protein phosphorylation in the central nervous system of the leech Hirudo medicinalis.

1. Phosphoproteins of different regions of the Hirudo medicinalis central nervous system have been analysed by means of two-dimensional electrophoresis. 2. Serotonin, 8-Br-cAMP and phorbol 12,13-dibutyrate stimulate phosphorylation of a number of proteins whose isoelectric points and molecular weights are presented. 3. A group of proteins of 78 kDa and pI = 6-6.5, whose level of phosphorylation increases in the presence of serotonin, 8-Br-cAMP and phorbol ester, is observed only in segmental but not in cephalic or caudal ganglia. 4. The putative roles of these phosphoproteins are discussed.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

Cyclic AMP mediates inhibition of the Na(+)-K+ electrogenic pump by serotonin in tactile sensory neurones of the leech.

1. Serotonin (5-HT) reduced the after-hyperpolarization (AHP) amplitude in tactile sensory neurones (T) but not in pressor (P) or nociceptive (N) cells of the leech. 2. Adenylate cyclase activators, phosphodiesterase inhibitors and membrane permeant analogues of cyclic adenosine monophosphate (cyclic AMP) mimicked the effect of 5-HT in reducing the AHP amplitude in T neurones. 3. Ionophoretic injection of cyclic AMP in T cells reduced the AHP amplitude, while cyclic guanosine monophosphate (cyclic GMP) or adenosine-5'-monophosphate (AMP) were without effect. 4. Inhibition of adenylate cyclase by the drug RMI 12330A (also known as MDL 12330A) suggested that 5-HT reduced the AHP amplitude through cyclic AMP. 5. 8-Bromoadenosine-3'-5'-cyclic monophosphate (8-Br-cyclic AMP) was still able to reduce the AHP amplitude after blocking the Ca(2+)-activated K+ conductance with CdCl2 and converted the normal hyperpolarization which follows the intracellular injection of Na+ into a depolarization. In addition, the cyclic AMP analogue slowed down and reduced the repolarization usually induced by CsCl after perfusion with K(+)-free solution. It is proposed that, in T sensory neurones, cyclic AMP mediates the inhibition of the Na(+)-K+ electrogenic pump induced by 5-HT application.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Effect of phorbol ester on protein phosphorylation in the central nervous system of the leech Hirudo medicinalis: a two-dimensional electrophoretical analysis.

1. Proteins of different regions of the Hirudo medicinalis central nervous system have been analyzed by means of two-dimensional electrophoresis. 2. Subcellular distribution of phosphoproteins has been studied in leech segmental ganglia. 3. Phorbol 12,13-dibutyrate, a protein kinase C activator, stimulates the phosphorylation of a number of proteins whose isoelectric points and mol. wts are presented. 4. Putative roles for these phosphoproteins are discussed.

Animals↗
PubMed1991

Serotonin depresses the after-hyperpolarization through the inhibition of the Na+/K+ electrogenic pump in T sensory neurones of the leech.

In T sensory neurones of the leech, a train of impulses elicited by intracellular electrical stimulation leads to an after-hyperpolarization of up to 30 mV, mainly due to the activation of the electrogenic Na+/K(+)-ATPase but partly to a Ca2(+)-activated K+ conductance. It was found that serotonin reversibly reduced the amplitude of this after-hyperpolarization. We investigated the mechanism of action of serotonin and found: (1) after inhibition of the Ca2(+)-activated K+ conductance with BaCl2 or CdCl2, serotonin was still able to reduce the after-hyperpolarization; (2) when penetration of T cells with microelectrodes leaking sodium was preceded by serotonin perfusion of the ganglia, the normal hyperpolarization due to the activation of the electrogenic pump was converted to a depolarization; (3) after long-lasting perfusion with K(+)-free saline solution (which inhibits the Na+/K+ pump), the application of CsCl caused repolarization by reactivating the electrogenic ATPase; serotonin slowed and reduced this repolarization; (4) serotonin potentiated the depolarization of T neurones caused by the inhibition of the Na+/K+ pump following cooling of ganglia and depressed the hyperpolarization after rewarming to room temperature. These data taken together suggest that serotonin directly inhibits the Na+/K+ electrogenic pump.

Action Potentials↗
PubMed1990

Seasonal variation of serotonin content and nonassociative learning of swim induction in the leech Hirudo medicinalis.

It is possible to obtain habituation of swim induction by stimulating the leech with repetitive light electrical trains. After obtaining this simple form of non-associative learning, it is also possible to potentiate its response by a series of nociceptive skin brushings (dishabituation). Serotonin applied to the animal is the only neurotransmitter found to mimick dishabituation. We have observed that in the period April-June most animals did not exhibit potentiation of the swimming response after nociceptive stimulation while injection of serotonin mimicked dishabituation as in the animals treated in the period October-March. We have seen correlation between the changes in nonassociative learning and the seasonal variation of serotonin levels in segmental ganglia. This finding strengthens the hypothesis of serotonin as the neurotransmitter mediating dishabituation in swim induction of the leech.

Animals↗
PubMed1990

Effects of dopamine, D-1 and D-2 dopaminergic agonists on the excitability of hippocampal CA1 pyramidal cells in guinea pig.

In hippocampal pyramidal cells (HPCs), Dopamine (DA) application (1 microM) produced, in 50% of recorded cells, an hyperpolarization of the resting membrane potential (r.m.p.) and an increase of the afterhyperpolarization (AHP) amplitude and duration in 79% of recorded cells. DA-induced effects on both the r.m.p. and AHP were mimicked by bath application of a D-1 selective agonist, SKF 38393 (20 microM). In addition, we have observed that a D-1 selective antagonist such as SCH 23390 (1 microM) abolished the action of both DA and SKF 38393. In contrast, the activation of D-2 receptors through LY 171555 (10 microns) produced, in 50% of cells, a depolarization of the r.m.p. and a depression of the AHP in 67% of recorded cells. These results suggest that the effects observed in hippocampal pyramidal neurons after DA application of micromolar concentration are mediated by D-1 subtype of receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1989

Effects of cyclic nucleotides and calcium/calmodulin on protein phosphorylation in the CNS of Hirudo medicinalis.

Protein phosphorylation plays an important role in the regulation of neural functions. We have studied the phosphorylation of proteins in homogenates of segmental ganglia of the leech Hirudo medicinalis. We describe a number of proteins whose phosphorylation is dependent on calcium/calmodulin or cyclic nucleotides. Most of the proteins whose phosphorylation is increased in the presence of calcium seem to be substrates for cyclic nucleotide-dependent protein kinases. Only two of the phosphoproteins described appear to be specific substrates for calcium/calmodulin protein kinase(s), and at least six phosphoproteins appear to be specific substrates for cyclic nucleotide-dependent kinase(s). The leech nervous system, with large and identifiable neurons, provides a good tool for studies of neural functions, such as learning. The results are discussed in the context of the role of protein phosphorylation on learning processes.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Neurotransmitter-induced modulation of an electrotonic synapse in the CNS of Hirudo medicinalis.

An identified pair of electrically coupled neurons, present in each segmental ganglion of the leech Hirudo medicinalis, was chosen as an experimental model of electrotonic synaptic transmission. We have found that the transfer of electrical signals between these coupled cells is reduced by perfusing the preparation with either one of the two endogenous neurotransmitters, serotonin and dopamine. The action of both serotonin and dopamine on the electrical coupling is reproduced by the iontophoretic injection of cyclic adenosine monophosphate (cAMP) into one of the coupled neurons. We propose that the two endogenous neurotransmitters modulate the transfer properties of this electrical synapse by increasing the intracellular levels of cAMP, possibly by activating the adenylate cyclase system.

Animals↗
PubMed1987

Two-dimensional echocardiography in the diagnosis of intracardiac masses: a prospective study with anatomic validation.

The accuracy of two-dimensional echocardiography in the detection of intracardiac masses was verified in 334 patients who underwent cardiac catheterization in our laboratory over 21 consecutive months. A complete two-dimensional echocardiographic (2DE) examination was performed a day before catheterization. The presence or absence of a mass was verified at surgery in 77 patients who successively underwent mitral or aortic valve replacement (51), left ventricular aneurysmectomy with or without myocardial revascularization (25), and resection of atrial myxoma (2). In 32 patients 2DE revealed the presence of a mass-left or right atrial thrombi in 12, left atrial myxoma in 2, left ventricular thrombi in 16, and endocardial vegetations in 2. The other 45 patients were free of intracardiac masses on 2DE. Anatomic verification at surgery revealed the presence of an intracardiac mass in 34 patients. In 30 (true positives) of these, 2DE revealed the mass as well, and in 4 (false negatives) the presence of a mass had not been identified by 2DE. In 2 patients (false positives) the predicted mass was not found at surgery. Absence of a mass was correctly predicted by 2DE in 41 patients (true negatives). Thus 2DE detected intracardiac masses with sensitivity of 88.2% and a specificity of 95.3%. We recommend that 2DE be performed in all patients prior to hemodynamic study and/or cardiac surgery to enable safer management of patients with intracardiac masses during cardiac catheterization and/or cardiac surgery.

Adult↗
PubMed1987

[Late aortic dissection after aortic valve substitution. Considerations on 5 operative cases].

This study analyses the clinical course of five patients who developed acute ascending aortic dissection 45.8 months (17-87 months) after aortic valve replacement (AVR) and underwent reoperation in our Department. All except one had aortic insufficiency with mild dilatation of the ascending aorta. No evidence of aortic wall degeneration was present at the time of AVR. Prostheses implanted were: Hancock 2, St. Jude 2, Bjork-Shiley 1. Associated procedures (coartectomy, coronary artery by-pass) were carried out in two patients. The dilated aorta was managed at the first operation by longitudinal resection in 3 of them. Emergent aortic dissection repair was performed: in 3 cases with composite graft according to the Bentall procedure, in one case with non valved dacron conduit and in the last case with teflon patch. Histological examination of the dissected aortic wall showed elastic fiber degeneration like cystic medial necrosis. Three patients survived surgical repair and are doing well at 22.4 months of mean post-operative follow-up. Surgical strategy of this complication is discussed; particular emphasis is given to the method of treatment of ascending aorta dilatation during AVR.

Adult↗