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Biomedical subjects

L Muzio

Publications and source records attributed to L Muzio.

At least 19 recordsLinked to original sources
PubMed2005

A mutually stimulating loop involving emx2 and canonical wnt signalling specifically promotes expansion of occipital cortex and hippocampus.

The correct size of the different areas composing the mature cerebral cortex depends on the proper early allocation of cortical progenitors to their distinctive areal fates, as well as on appropriate subsequent tuning of their area-specific proliferation-differentiation profiles. Whereas much is known about the genetics of the former process, the molecular mechanisms regulating proliferation and differentiation rates within distinctive cortical proto-areas are still largely obscure. Here we show that a mutual stimulating loop, involving Emx2 and canonical Wnt signalling, specifically promotes expansion of the occipito-hippocampal anlage. Collapse of this loop occurring in Emx2-/- mutants leads progenitors within this region to slow down DNA synthesis and exit prematurely from the cell cycle, due to misregulation of cell cycle-, proneural- and lateral inhibition-molecular machineries, and eventually results in dramatic and selective size-reduction of occipital cortex and hippocampus. Reactivation of canonical Wnt signalling in the same mutants rescues a subset of molecular abnormalities and corrects differentiation rates of occipito-hippocampal progenitors.

Animals↗
PubMed2000

The lack of Emx2 causes impairment of Reelin signaling and defects of neuronal migration in the developing cerebral cortex.

Neocorticogenesis in mice homozygous for an Emx2 null allele is the topic of this article. The development of both main components of neocortex, primordial plexiform layer derivatives and cortical plate, was analyzed, paying special attention to radial migration of neurons forming the cortical plate. The products of the Reelin gene, normally playing a key role in orchestrating radial migration of these neurons, display normal distribution at the beginning of the cortical neuronogenesis but are absent in the neocortical marginal zone of the mutant mice at the time when the cortical plate is laid down. As a consequence, the development of radial glia is impaired, and neurons making up the cortical plate display abnormal migration patterns. In addition, restricted defects along the rostrocaudal and the mediolateral axes are present in the subplate, suggesting an Emx2-specific role in priming the proper development of this layer.

Animals↗
PubMed2000

Genetic control of regional identity in the developing vertebrate forebrain.

In the past we isolated and characterized a number of vertebrate homeobox genes expressed in the developing brain. In particular, Emx1 and Emx2 are expressed in the developing forebrain of mouse embryos, in a region including the presumptive cerebral cortex. In the developing cerebral cortex, Emx1 is expressed in most neuroblasts and neurons at all stages of development, whereas Exm2 expression is restricted to proliferating neuroblasts of the so-called ventricular zone and to Cajal-Retzius cells, but is undetectable in most postmitotic cortical neurons. It is conceivable to hypothesize that Emx2 plays a role in the control of proliferation of cortical neuroblasts and in the regulation of their subsequent migration. This latter process has been recently analysed in some detail in null mutant mice. The expression of these and other genes has also been analysed in the developing brain of different species of vertebrates. Homologies between forebrain subdivisions have been proposed based on the conservation and divergence of gene expression patterns.

Animals↗
PubMed2000

Area identity shifts in the early cerebral cortex of Emx2-/- mutant mice.

The specification of area identities in the cerebral cortex is a complex process, primed by intrinsic cortical cues and refined after the arrival of afferent fibers from the thalamus. Little is known about the genetic control of the early steps of this process, but the distinctive expression pattern of the homeogene Emx2 in the developing cortex has prompted suggestions that it is critical in this context. We tested this hypothesis using Emx2 -/- mice. We found that the normal spectrum of cortical areal identities was encoded in these mutants, but areas with caudal-medial identities were reduced and those with anterior-lateral identities were relatively expanded in the cortex.

Afferent Pathways↗
PubMed1992

An unusual cause of carotid sinus syndrome: multiple symmetric lipomatosis.

A 45-year-old man with multiple symmetric lipomatosis suffered recurrent syncope attributed to carotid sinus syndrome caused by extrinsic compression of the carotid body by the lipomatous masses. Surgical removal reduced but did not stop syncope, which was then controlled by implantation of a DDD pacemaker.

Carotid Sinus↗
PubMed1991

[Delayed-action disopyramide in the treatment of hyperkinetic ventricular arrhythmia. A randomized clinical comparative study vs immediate-action disopyramide].

The authors report the results of an open randomized study to compare the efficacy of oral slow-release and immediate-release disopyramide, in the treatment of patients with chronic stable ventricular arrhythmias, evaluated with two Holter recordings. Twelve patients, selected after positive acute intravenous test, had been randomly assigned to slow-release (500 mg/day) and immediate-release (400 mg/day) disopyramide. Ten days later, a Holter recording was performed and then all patients were treated with slow-release disopyramide (500 mg/day); After one month drug efficacy has been evaluated by Holter recording. Total ectopic beats and arrhythmic Lown modified score were the end points. Immediate-release disopyramide significantly reduced both total beats and arrhythmic score; the slow-release formulation did not modify total beats and reduced the arrhythmic score, but only at the first Holter control. One month later there was no significant difference in arrhythmic score either. Low plasma drug levels could explain these results in some patients.

Aged↗
PubMed1991

[Syncope due to sinus arrest secondary to marked vagal hypertonus. The role of permanent atrial stimulation in revealing associated atrioventricular node involvement].

The authors report a case of a 42-year-old man, with relapsing syncope, related to sinus arrest, documented by Holter recording. The clinical investigation, the electrophysiological study with autonomic blockade included, have proved normal and then an AAI pacemaker has been implanted. Some weeks later, the patient reported a lipothymic episode; a Holter recording showed a second degree AV block, with normal pacemaker function. A DDD pacemaker has been implanted and in the next ten months the patient felt well. The sinus arrest physiopathology, the role of the autonomic nervous system and the correct electrostimulation mode have been discussed.

Adult↗
PubMed1987

[Pulmonary and systemic embolism in a case of biatrial thrombosis. Role of two-dimensional echocardiography].

The authors describe the case of a 61-year-old woman affected with pulmonary embolism, in whom the presence of masses in both atria has been detected by two-dimensional echocardiography. The event of a systemic embolism and the dissolution of both masses after an anticoagulant therapy, has induced the authors to diagnose a biatrial thromboembolism propagating from the venous system and passage of thromboembolic material through a patent foramen ovale. These findings are, therefore, in differential diagnosis compared with other biatrial intracavitary masses.

Diagnosis, Differential↗
PubMed1987

[Efficacy and tolerance of diltiazem in primary pulmonary hypertension. Apropos of a case].

The Authors report a case of a serious and symptomatic primary pulmonary hypertension, where the intravenous administration of Diltiazem, at a dosage of 0.3 mg/kg, resulted in an important improvement of haemodynamic parameters. This improvement was confirmed 4 months later on chronic oral therapy with Diltiazem, at a dosage of 180 mg per day. Six months after the beginning of therapy, the patient is totally asymptomatic. Even though further controls are needed, Diltiazem may represent an active drug in the treatment of primary pulmonary hypertension.

Administration, Oral↗
PubMed1983

[Treatment of essential arterial hypertension with a single daily dose of acebutolol].

25 patients with essential arterial hypertension were treated with single daily doses of 400 g acebutolol administered for EIGHT weeks in outpatients' departments. The drug proved to be extremely effective in reducing PAS and PAD values in both lying and standing positions. No undesirable side effects were observed except in one case where cardiac insufficiency was controlled by digitalis. It can therefore be concluded that acebutolol is a beta-adrenolytic drug which is reliably effective in the treatment of essential arterial hypertension, well tolerated and easily administered.

Acebutolol↗