Biomedical subjects

V Rizzo

Publications and source records attributed to V Rizzo.

At least 19 recordsLinked to original sources

PubMed2006

Involvement of nitric oxide-soluble guanylyl cyclase pathway in the control of maximal dentate gyrus activation in the rat.

Nitric oxide/soluble Guanylyl cyclase (NO/sGC) pathway on the maximal dentate gyrus activation (MDA) was studied in rats. The cerebral NO levels were modified by administrating 7-Nitroindazole (7-NI), a selective inhibitor of neuronal NOS, and L-arginine, a precursor of the synthesis of NO. 1H-[1,2,4]Oxadiazole[4,3-a]quinoxalin-1-one (ODQ), a specific inhibitor of the NO-sGC pathway, was administered to study the involvement of cGMP pathway. The epileptic activity of the dentate gyrus was obtained through the repetitive stimulation of the angular bundle; MDA parameters studied were: onset time, MDA duration and post-stimulus afterdischarge (AD) duration. 7-NI caused an increase of MDA onset time and a decrease of MDA and AD duration. L-arginine, induced an aggravation of the epileptiform phenomena. ODQ induced modifications of MDA parameters as those caused by 7-NI. Our results indicate that the nitrergic neurotransmission exerts a modulatory role in the proneness to the epileptogenic phenomena through the activation of sGC metabolic pathway.

Animals↗

PubMed2005

Transcranial magnetic stimulation as trigger of dystonic attacks in a patient affected by paroxysmal kinesigenic dyskinesia.

A 22-year-old patient presented with attacks of paroxysmal dystonia characterised by involuntary and uncontrollable movements affecting lower and upper limbs with sustained turning or twisting of the trunk. These motor paroxysms were induced by voluntary movements and lasted between 10 and 15 s with a frequency of 1-5 attacks per day. Transcranial magnetic stimulation of the motor cortex was found to induce motor paroxysms very similar to the spontaneous attacks. To evaluate motor cortex and brainstem excitability immediately after and between the attacks, a neurophysiological study was performed.

Adult↗

PubMed2004

One-hertz subthreshold rTMS increases the threshold for evoking inhibition in the human motor cortex.

Despite indisputable evidence that repetitive transcranial magnetic stimulation (rTMS) modulates motor cortical excitability, the effects of subthreshold low-frequency rTMS on intracortical inhibition (ICI) are controversial. In this paper we investigated whether increasing the level of baseline ICI increases the sensitivity of ICI for disclosing the after-effects of rTMS on cortical excitability. In experiment 1, we studied changes in ICI, tested at two different baseline levels, after a train of 900 subthreshold rTMS pulses delivered at 1 Hz. In experiment 2, we studied whether the same conditioning rTMS train changed the ICI threshold, and in experiment 3 whether it changed the facilitatory I-wave interaction. Conditioning rTMS reduced ICI tested at a baseline level of 75% but left ICI tested at a baseline level of 50% unchanged. It also increased the ICI threshold but left the facilitatory I-wave interaction unchanged. These findings suggest that conditioning rTMS selectively reduced ICI tested at a baseline level of 75% by increasing the threshold for evoking inhibition in the motor cortex. The inhibitory system mediating ICI may therefore be more efficient than other motor cortical systems in reducing high cortical excitability after external intervention. Hence studies investigating the after-effects of rTMS should standardize ICI levels at baseline.

Adult↗

PubMed2004

Integrin mechanotransduction stimulates caveolin-1 phosphorylation and recruitment of Csk to mediate actin reorganization.

To identify the role of caveolin-1 in integrin mechanotransduction, we exposed bovine aortic endothelial cells to 10 dyn/cm2 of laminar shear stress. Caveolin-1 was acutely and transiently phosphorylated with shear, occurring downstream of beta1-integrin activation as the beta1-integrin blocking antibody JB1A was inhibitory. In manipulating Src family kinase (SFK) activity with knockdown of Csk or type 1 protein phosphatase (PP1) treatment, we observed coordinate increase and decrease in shear-induced caveolin-1 phosphorylation, respectively. Hence, shear-stimulated caveolin-1 phosphorylation is regulated by SFKs. Shear-induced recruitment and phosphorylation of caveolin-1 occurred at beta1-integrin sites in a beta1-integrin- and SFK-dependent manner. Csk, described to interact with pY14-caveolin-1 and integrins, bound to an increased pool of phosphorylated caveolin-1 after shear corresponding with elevated Csk at beta1-integrin sites. Like caveolin-1, treatment with JB1A and PP1 attenuated shear-induced Csk association with beta1-integrins. Csk function was assayed with transfection of a caveolin-1 phosphorylation domain peptide. The peptide attenuated shear-induced association of Csk at beta1-integrin sites, as well as colocalization of Csk with paxillin and phosphorylated caveolin-1. Because integrin and Csk activity regulate cytoskeletal reorganization, we evaluated the role of this mechanism in shear-induced myosin light chain (MLC) phosphorylation. Knockdown of Csk expression was sufficient to reduce MLC diphosphorylation due to shear. Disruption of Csk-integrin association by peptide treatment was also inhibitory of the MLC diphosphorylation response. Together these data indicate that integrin activation with shear stress results in SFK-regulated caveolin-1 phosphorylation that, in turn, mediates Csk association at integrin sites, where it plays a role in downstream, shear-stimulated MLC diphosphorylation.

Actins↗

PubMed2004

Endoscopic selective sampling of human ventricular CSF: a new perspective.

Neuroendoscopy has achieved extensive acceptance among neurosurgeons as a minimally invasive technique for the treatment of patients affected by blocked hydrocephalus. During endoscopic procedures minimal CSF amounts from selected anatomic sites of the ventricles can be withdrawn. Steerable endoscopes are used and their flexibility facilitates the aspiration of CSF during the preliminary inspection through the ventricular cavities, without any interference with the surgical actions or additional risks for the patients. In this preliminary study the concentrations of melatonin and other related metabolites in the lateral ventricles, third ventricle, pineal recess and infundibular recess were examined. The data obtained from a patient affected by blocked hydrocephalus confirmed a constant and significant difference of concentration of these substances, for instance, melatonin levels were found to be much higher in the third ventricle (542 pg/mL in its centre) than in the lateral ventricle (172 pg/mL in the right ventricle). Nevertheless, instead of what we would expect, the highest melatonin concentrations were not found in the pineal recess (438 pg/mL). In the future, neuroendoscopy, beside its evident therapeutic efficacy, could open new perspectives in the study of both CSF biochemistry and physiology, allowing a highly selective approach to the various substances which are released and float in it.

Aged↗

PubMed2002

Soluble angiogenic factors: implications for chronic myeloproliferative disorders.

The role of angiogenesis for the progressive growth and metastatic process of tumours is well established. What is not clear, though, is the clinical prognostic significance of the angiogenic factors in malignant haematological diseases. In this study, we have assessed the plasma and serum levels of two major angiogenic factors, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF) in 55 patients affected by chronic myeloproliferative disorders (CMD). This series included 25 patients with essential thrombocythemia (ET), 10 patients with chronic myelocytic leukaemia (CML), 14 patients with polycythemia vera (PV), and 6 patients with primary myelofibrosis (MF), and they were compared to 20 healthy control subjects. In all patients the plasma VEGF concentration was significantly increased to the healthy control group (P < 0.004). The highest concentrations were found in the patients with ET (178.25 +/- 125.22 pg/ml). The VEGF levels were significantly higher in CMD patients with vascular complications than those in CMD patients without complications (P < 0.01). The b-FGF serum levels also appeared to be significantly higher in almost all the CMD patients compared to the control group (P < 0.07). A significant correlation was found between the VEGF levels and the platelet count in the ET patients and the spleen index in the CML patients. VEGF level, in this study, is associated with increased risk of thrombotic complications. There is evidence of increased levels of soluble angiogenic factors in malignant haematological disorders, but their contribution to the progression of diseases is yet unclear.

Case-Control Studies↗

PubMed2002

Different patterns of I-waves summation in ALS patients according to the central conduction time.

OBJECTIVES: To study facilitatory I-waves interaction, using two near threshold stimuli, to test both excitability and conductivity changes related to cortico-motoneuronal involvement in amyotrophic lateral sclerosis (ALS) patients in different stages of the disease. METHODS: Pairs of threshold magnetic stimuli were applied over the motor cortex at inter-stimulus intervals (ISI) ranging from 1-1.5 to 2.5-3 ms and from 4 to 4.5ms. The electromyogram responses were recorded from relaxed first dorsal interosseus (FDI). RESULTS: The data of I-waves summation were distributed according to the central conduction time (CCT) and all 3 peaks of facilitation were considered for statistical analysis. Patients with normal CCT showed a normal I-waves summation for the first peak, whilst patients with abnormal CCT had a significant reduction in facilitation (P<0.02). Six out of 11 patients with normal CCT had facilitation in the first peak, which exceeded 2 SD of normal values. CONCLUSIONS: In conclusion ALS patients showed two different and opposite patterns of I-waves summation which could be related to different stages of the disease.

Adolescent↗

PubMed2001

Modification of cortical excitability induced by gabapentin: a study by transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) was employed before and after a single dose of gabapentin to evaluate how this drug affects the activity of excitatory and inhibitory circuits within the motor cortex. Eleven healthy volunteers were studied. For the evaluation of cortical excitability, the following parameters were taken into account: resting and active motor threshold (RMT, AMT); cortical silent period (CSP); and intracortical inhibition (ICI) and facilitation (ICF). Peripheral silent period (PSP) was also detected. All parameters were measured before and 3 and 24 hours after 800 mg gabapentin was administered in a single oral dose. Gabapentin deepened the ICI and suppressed the ICF at 3 h but not at 5 h after dosing. We conclude that, in the normal human brain, gabapentin may act on intracortical excitability by shifting the balance towards less excitation and more inhibition.

Acetates↗

PubMed2001

Segmental myoclonus in a patient affected by syringomyelia.

We describe a patient who has been complaining of brief jerk-like, rhythmic, involuntary movements involving the second digit of the left hand for the last three months. These involuntary jerks produced an adduction movement of the second digit and were unaffected by peripheral sensory stimuli. In addition, the patient experienced loss of dexterity in the left hand. On examination the patient showed hypotrophy of the first dorsal interosseous (FDI) muscle of the left hand and a dissociated sensory loss involving the C8-T1 dermatomes. Magnetic resonance imaging of the brain and spinal cord revealed a tonsilar hemiation characteristic of the Chiari I malformation associated with a syrinx extending from C4 to D5 that did not communicate with the fourth ventricle. The electrophysiological evaluation indicated the presence of a focal myoclonus of spinal origin that is likely to be caused by the syrinx.

Arnold-Chiari Malformation↗

PubMed2001

Growth hormone treatment does not alter lower limb asymmetry in children with Russell-Silver syndrome.

BACKGROUND: Growth hormone (GH) treatment has been proven to have a beneficial effect on growth in children with Russell-Silver syndrome (RSS). METHODS: We describe 7 prepubertal children with RSS and lower limb asymmetry treated with GH for 3 years. RESULTS: There was a significant increase in height without any significant change in the asymmetry. CONCLUSIONS: We conclude that the rapid growth acceleration to GH treatment does not alter the lower limb asymmetry in children with RSS.

Child↗

PubMed2001

Effects of cardiac rehabilitation on atrial wave in patients after myocardial infarction.

Cardiac rehabilitation (CR) can improve cardiac hemodynamic performance in patients after myocardial infarction (MI). Little evidence is provided concerning the consequences of CR on atrial wave duration, and less is known about the link between pre-arrhythmogenic patterns and the cardiovascular performance improvement in these subjects. Twenty-six patients, post-MI 0 to 7 days, underwent a complete CR cycle and a signal-averaged electrocardiogram (SAECG) for the evaluation of atrial activation parameters (group 1) to appreciate if physical training can promote parallel improvement in cardiovascular and intra-atrial conduction parameters. A control group of 24 well-matched nonischemic subjects (group 2) was chosen for data comparison. Resting heart rate (p < 0.01) and resting double product (p < 0.01) decreased after CR in groups 1 and 2, while diastolic blood pressure at maximal stress was decreased in group 1 (p < 0.01) with a parallel increase in the time of physical training (p < 0.05). SAECG parameters of atrial activation were unchanged in group 1 after the comparison and only total atrial duration activation (dA) reached statistical significance (113.3 +/- 17.2 msec vs 120.8 +/- 14.2 msec, subjects after CR vs before CR, p < 0.01). CR could improve intra-atrial activation in subjects after MI, but the consequences of hemodynamic adjustment of the trained heart must undergo a more accurate evaluation to verify if CR can prevent adverse arrhythmogenic complications of MI through cardiovascular performance improvement.

Blood Pressure↗

PubMed2000

Influence of different anaesthetics on extracellular aminoacids in rat brain.

We used different anaesthetic procedures to study the possible effects of anaesthesia on extracellular aminoacid concentration in rat brain. Glutamate, aspartate and glycine concentrations were determined by HPLC in samples collected from the right fronto-parietal region of the rat brain cortex by transcerebral microdialysis before and up to 2 h following anaesthesia induction. Anaesthesia induced by ketamine, alone or in association with xylazine, caused a significant decrease in the levels of glutamate, aspartate and glycine, compared to before anaesthesia values (range: 27-72% according to the time of sampling and to the anaesthetic used). Inhalation anaesthesia with halothane (3%) in N2O/O2 mixture produced no significant effects on aminoacid levels. Equitensine (pentobarbital in association with chloral hydrate and ethanol) and pentobarbital also had no significant effect on glutamate, aspartate and glycine levels during anaesthesia. This demonstrates that some anaesthetics alter excitatory aminoacid release and suggests that Equitensine may represent an easy and reliable method to induce a long lasting anaesthesia associated without changes in excitatory aminoacid extracellular concentration.

Amino Acids↗

PubMed2000

Left ventricular function, cardiac dysrhythmias, atrial activation, and volumes in nondipper hypertensive individuals with left ventricular hypertrophy.

BACKGROUND: Arrhythmic patterns and left ventricular geometric adaptations to pressure overload were investigated in 76 patients with untreated borderline-to-moderate sustained essential hypertension studied by 2-dimensional and M-mode echocardiography, 12-lead, Holter, and signal-averaged electrocardiography, and ambulatory blood pressure monitoring. METHODS AND RESULTS: Sixty-two age- and sex-matched normal adults were chosen for data comparison. Hypertrophic hypertensive patients were subdivided into 2 subgroups: 44 patients with nocturnal blood pressure reduction (dippers) and 32 patients without it (nondippers). Common afterload and diastolic function indexes were found to be lower in combined nondipper and dipper groups, but only fractional shortening decreased in nondippers. The number of premature atrial and ventricular contractions per hour was high in dippers and nondippers, with no statistically significant differences between them; atrial and ventricular complex dysrhythmias were similar. Signal-averaged electrocardiography showed a prolonged P-wave duration in dipper and nondipper patients with high atrial volumes but no late ventricular potentials and no difference in quantitative P-wave analysis. Left atrial volumes, P-wave duration, and premature atrial contractions were found to be positively linked to left ventricular hypertrophy. In nondipper patients a linear correlation was observed between left atrial volume and P-wave duration, although supraventricular ectopic activity was connected to left atrial volume enlargement both in dipper and nondipper patients. CONCLUSIONS: These data suggest that the nondipper pattern is not linked to a worse arrhythmogenic substrate; only atrial volume increase may be related to significant supraventricular activity and prolonged atrial activation in nondipper patients, but late ventricular potentials are uncommon in hypertrophic hypertensive patients.

Arrhythmias, Cardiac↗

PubMed2000

Effect of trimetazidine on 99Tcm-tetrofosmin uptake in patients with coronary artery disease.

Myocardial uptake of 99Tcm-tetrofosmin in vivo is determined by a combination of flow and metabolic status of myocytes. The accumulation of tetrofosmin in the mitochondria is related to their ability to transduce metabolic energy into electronegative membrane potential. Trimetazidine (TMZ), an anti-ischaemic drug, appears to have a metabolic cytoprotective effect related to mitochondrial function, since it does not induce systemic or coronary haemodynamic changes. In this study, we evaluated the effects of TMZ on tetrofosmin uptake in hypoperfused myocardial regions in patients with coronary artery disease (CAD). Twenty-two patients, 14 with previous myocardial infarction (group A) and eight with a history of angina (group B), with angiographically documented CAD were studied. All patients underwent two tetrofosmin SPET studies at rest, before (baseline) and 1 week after TMZ administration (post-TMZ). On quantitative analysis, 131 segments showed less tetrofosmin uptake at baseline. In these segments, tetrofosmin uptake was 51 +/- 13% at baseline and 55 +/- 15% post-TMZ (P < 0.001 vs control). In the 86 hypoperfused segments of group A, tetrofosmin uptake was 48 +/- 14% at baseline and 52 +/- 17% post-TMZ (P < 0.001 vs control). In the 45 hypoperfused segments of group B, tetrofosmin uptake was 56 +/- 9% at baseline and 60 +/- 10% post-TMZ (P < 0.001 vs control). In the remaining 309 segments, no significant difference in tetrofosmin uptake before and after TMZ was observed. In conclusion, our results suggest that TMZ administration may increase myocardial uptake of tetrofosmin in hypoperfused regions at rest in patients with CAD, based on its metabolic effect.

Aged↗

PubMed2000

Etiology of central precocious puberty in males: the results of the Italian Study Group for Physiopathology of Puberty.

We reviewed the hospital records of 45 boys, followed in 13 pediatric departments throughout Italy, who had undergone computed tomography and/or magnetic resonance imaging for central precocious puberty (CPP). Twenty-seven patients (60%) had idiopathic CPP and 18 (40%) neurogenic CPP. A hamartoma of the tuber cinereum was found in six patients (33%). All patients with hypothalamic hamartoma had earlier onset of symptoms than patients with idiopathic CPP. Five patients (27%) were affected by type 1 neurofibromatosis, two had ependymoma and five patients had an intracranial anomaly. Basal LH and basal and peak LH/FSH ratio were greater, but not significantly, in boys with neurogenic CPP than in boys with idiopathic CPP. The highest LH peak levels were observed in patients with hamartoma; however, no correlation was observed between LH peak and the size of the hamartomas. In addition, bone age at diagnosis was more advanced in patients with hamartoma than in patients with other conditions. In conclusion, gonadotrophin-dependent precocious puberty may be of idiopathic origin or may occur in association with any CNS disorder. Further studies are needed in order to evaluate the effects of nutritional, environmental and psychosocial factors on the timing of sexual maturation, to explain the high incidence of idiopathic CPP in our male patients.

Brain Diseases↗

PubMed2000

Factors influencing final/near-final height in 12 boys with central precocious puberty treated with gonadotrophin-releasing hormone agonists. Italian Study Group of Physiopathology of Puberty.

Gonadotrophin-releasing hormone agonists (GnRHa) have been demonstrated as the therapy of choice for central precocious puberty (CPP). Few studies have provided male patients' adult height data. In our multicenter study we evaluated long-term effects of different GnRHa preparations and final/near-final height (FH) in 12 boys with CPP and analyzed the factors influencing FH. Patients' mean chronological age at the time of diagnosis was 7.6 +/- 0.9 yr. Three patients were treated only with triptorelin at a mean dose of 90 microg/kg i.m. every 28 days. Nine patients initially received buserelin (at a mean initial dose of 53.4 microg/kg/day i.n. divided into 3-6 equal doses) or buserelin (at a mean dose of 36.7 microg/kg/day s.c.) and were subsequently switched to triptorelin. The GnRHa therapy was continued for 4.1 +/- 0.6 yr (range 2.9-5.4). The mean predicted adult height increased from 169.9 +/- 4.2 cm at diagnosis to 180.7 +/- 6.0 cm at the end of treatment. Mean FH was 176.1 +/- 6.1 cm (170.1-190.7), corresponding to mean SDS(CA) 0.4 +/- 0.8 (-0.6/2.5), mean SDSBA 0.2 +/- 0.9 (-0.6/2.4) and mean corrected SDS for target height of 0.4 +/- 0.6 (-0.8/1.2). Multiple regression analysis revealed that FH was mainly influenced by target height and height at discontinuation of GnRHa therapy. The present data indicate that GnRHa therapy significantly improves growth prognosis in boys with CPP and fully restores genetic height potential.

Body Height↗

PubMed1999

Equilibrium and kinetics of rotamer interconversion in immunosuppressant prodigiosin derivatives in solution.

The equilibrium and relative rate of rotamer interconversion around the bond joining the 2,2'-bipyrrolyl and pyrromethene moieties in a synthetic analogue of immunosuppressant prodigiosin are investigated as a function of pHapp in a water/acetonitrile mixture (1/1 by volume). Two chromatographically separable isomeric forms are obtained in acid solutions (pHapp < 4), whereas rapid interconversion occurs above neutrality. Furthermore, pH modulates the conformational preference of the molecule according to nitrogen protonation on the three pyrrole rings system (pKa = 7.2). At high pHapp (neutral form), the same conformer that is observed in pure acetonitrile prevails, whereas the other one is preferred by the protonated form. The nuclear magnetic resonance data indicate that the structures of the two conformers mainly differ in the value of the torsion angle around the aforementioned C-C bond. Kinetic and equilibrium data are quantitatively interpreted with a cyclic mechanism including two protonation (pKa1 = 8.23 +/- 0.03, pKa2 = 5. 4 +/- 0.2) and two conformational rearrangement steps. A molecular interpretation of the observed behavior includes, for the preferred conformer at low pH, formation of a new hydrogen bond between the exocyclic oxygen and the neighboring pyrrole NH upon protonation of the three pyrrole rings system.

Chromatography, High Pressure Liquid↗

PubMed1999

Spectral analysis of heart rate variability in elderly non-dipper hypertensive patients.

To assess by autoregressive model the frequency domain heart rate variability (HRV) during clinostatism and after passive orthostatic load (head-up tilt), 81 hypertensive and normotensive subjects (42 men and 39 women) were subdivided into four groups: 20 adult normotensive subjects (Group 1); 21 elderly normotensive subjects (Group 2); 20 elderly hypertensive subjects with nocturnal blood pressure (BP) falls (Group 3); and 20 elderly hypertensive subjects without nocturnal BP falls (Group 4). They were chosen to assess the influence of aging and arterial hypertension on sympathetic-parasympathetic balance. The age-related decrease observed in nearly all HRV spectral frequency components (normalised units [NUs], high frequency [HF] and low frequency [LF]) was reported in elderly patients in rest conditions. LF indexes resulted in decreases in Group 3 and these data seemed to be emphasised in Group 4. After passive tilt, spectral data were recorded as follows: 25.3+/-1.8 vs 17.8+/-2.2 HF, Group 2 vs Group 1, P<0.001; 72.5+/-0.8 vs 75.6+/-1.8 LF, P< 0.001, Group 2 vs Group 1. Both sympathetic and parasympathetic indexes were lower in Group 3 (44.6+/-1.1 vs 72.5+/-0.8 LF, P< 0.001, Group 3 vs Group 2; 9.9+/-1.8 vs 25.3+/-1.8 HF, P < 0.001, Group 3 vs Group 2) and data became clearer in Group 4 (8.5 2.1 vs 9.9+/-1.8 HF, P< 0.001; 40.4+/-1.5 vs 44.6+/-1.1 LF, Group 4 vs Group 3). The established influence of aging on autonomic nervous system activity appears to be increased by arterial hypertension due to worsening of the sympathetic-parasympathetic response to standardised stimulation. The loss of nocturnal BP declines in arterial hypertension was found to occur in association with a decrease in autonomic nervous system activity.

Adult↗