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G Toniolo

Publications and source records attributed to G Toniolo.

18 recordsLinked to original sources
PubMed1995

Impaired left ventricular filling in hypertensive left ventricular hypertrophy as a marker of the presence of an arrhythmogenic substrate.

OBJECTIVE: To assess the prevalence of ventricular late potentials and ventricular tachycardia in hypertensive subjects with left ventricular hypertrophy and to study their relation to clinical characteristics. SETTING: Teaching and general hospital in Padua. METHODS: 107 hypertensive subjects with echocardiographic signs of left ventricular hypertrophy were studied with signal averaged electrocardiography and 24 hour Holter monitoring. Signal averaged electrocardiogram analysis was performed with high pass filters of 25 Hz, 40 Hz, and 80 Hz. Ventricular late potentials were considered to be present if at least two determinants of the signal averaged electrocardiogram were abnormal in one of the three filters. 70 normotensive subjects served as age matched controls. RESULTS: 25% (27) of the hypertensive subjects and 6% (four) of the controls showed late potentials on signal averaged electrocardiography (P < 0.0001). The hypertensive subjects with late potentials had a higher prevalence of ventricular tachycardia (33%, 9/27) than those without late potentials (13%, 10/80; P = 0.035). Twenty nine per cent (31/107) of the hypertensive subjects had an inversion of the early to atrial filling velocity (E/A ratio < 1) on Doppler analysis of transmitral flow. Within this group the percentage of subjects with late potentials (55%, 17/31) and ventricular tachycardia (42%, 13/31) was much greater than that within the group of subjects without an inverted E/A ratio (13%, 10/76 (P < 0.0001) and 12%, 9/76 (P = 0.001) respectively). In a multivariate analysis only the E/A ratio was related to the presence or absence of either late potentials (P = 0.0001) or ventricular tachycardia (P = 0.0008). Both late potentials and ventricular tachycardia were unrelated to left ventricular mass, geometry, and systolic performance. CONCLUSIONS: A relation was found between the occurrence of ventricular tachycardia and the presence of late potentials in hypertensive subjects with left ventricular hypertrophy. Impaired left ventricular filling was the main marker for the arrhythmogenic substrate present in this disease.

Arrhythmias, Cardiac↗
PubMed1994

[Relations between ventricular late potentials and ventricular arrhythmias in mitral valve prolapse].

BACKGROUND: The aim of the present study was to assess the prevalence and the clinical significance of ventricular late potentials in mitral valve prolapse. METHODS: Two hundred subjects (126 women and 74 men) with mitral valve prolapse, and a mean age of 37 +/- 17 years, were studied. Fifty eight per cent of them exhibited signs of mitral regurgitation at Doppler analysis of mitral flow. A 24-hour Holter recording and a signal-averaged electrocardiogram were performed in all the patients. Late potentials were considered present if the filtered QRS complex was > 110 ms and the root-mean-square amplitude in the last 40 ms of the filtered QRS was < 25 microV after 25 Hz filtering and respectively > 114 ms and < 20 microV after 40 Hz filtering. The duration of low-amplitude signals < 40 mV had to be > 38 ms. RESULTS: Ventricular late potentials were detected in 45 patients (22.5%) and were unrelated to subjects age, sex and electrocardiographic ST-T changes. Fourty one per cent of the subjects exhibited lown class > or = 3 ventricular extrasystoles at Holter ECG monitoring, while the remaining subjects (59%) had Lown classes < 3 ventricular arrhythmias. Complex ventricular arrhythmias were more common in the subjects who exhibited late potentials (55.5%) than in the remaining population (36.7%) (p < 0.03). A higher frequency of late potentials was found in the patients with mitral regurgitation (34.7%) than in those without (5.8%) (p < 0.0001). In the 55 subjects who manifested mitral regurgitation and complex ventricular arrhythmias, the prevalence of late potentials was 43.6%, while in the 61 without complex arrhythmias the prevalence was 26.6% (p = 0.05). CONCLUSIONS: In subjects with mitral valve prolapse the signal-averaged electrocardiogram allows to identify a subgroup of patients with more serious ventricular arrhythmias. Mitral regurgitation seems to be the main determinant of the arrhythmogenic substrate present in these patients.

Adolescent↗
PubMed1988

Behavioral deficits after intrahippocampal fetal septal grafts in rats with selective fimbria-fornix lesions.

Fetal septal transplants have been shown to promote behavioral recovery in young adult rats with aspiration fimbria-fornix lesions, rats with septal lesions and in intact aged rats. The present study examined the behavioral impact of intrahippocampal septal cell suspension transplants (T) in young female rats that had received, 10 days earlier, either medial fimbria lesions (Group FI.T), dorsal (subcallosal) fornix lesions (Group FO.T) or these two lesions together (Group FIFO.T). Relative to rats with lesions only (groups FI, FO and FIFO), grafted rats, irrespective of lesion locus, displayed unexpected impairments in (i) a serial alternation learning task, 5 weeks and 6 months after transplantation, and (ii) in a radial maze, 7 months after transplantation. In the first alternation test, Group FIFO showed impaired performance relative to Groups FI, FO and the sham-operated controls (Group S). In the second alternation test, Groups FO.T and FO showed impaired performance relative to Groups FI.T and FI, and only the performance of Group FI did not differ from that of Group S. In the radial maze, Groups FI, FO and FIFO all showed impaired performance relative to Group S. By contrast, there were no deleterious effects of lesions or of grafts in the acquisition and retention of a step-through passive avoidance task, 10 weeks after transplantation. Our findings on the effects of selective fimbria-fornix lesions did not confirm the report that rats with FI lesions but not those with FO lesions are unable to learn a serial alternation task, nor the report that FO lesions impair passive avoidance retention. Acetylcholinesterase (AChE) histochemistry revealed that grafts were present but graft-derived innervation of the host hippocampus varied from extensive to almost non-existent in all transplant groups. AChE-positivity in the dorsal hippocampus (DH) was not related to behavioral performance. However, the grafts often grew to a considerable size within the host brain and in many rats, especially those in Group FI.T, produced moderate to extreme damage of the host DH. There was a significant positive correlation between errors in the radial maze and graft-induced DH damage but no relationship between errors and graft size. The results indicate that, after partial lesions of the fimbria-fornix, intrahippocampal septal grafts survive well but are likely to damage recipient structures and result in behavioral impairments.

Acetylcholinesterase↗
PubMed1988

Unilateral infusion of GABA and saline into the nucleus basalis of rats: 1. Effects on motor function and brain morphology.

Motor behavior was investigated in rats following acute and chronic gamma-aminobutyric acid (GABA) microinfusions into the nucleus basalis. For acute treatment, the rats received GABA (100 micrograms in 1 microliter), then saline, or these solutions in the reverse order, into the nucleus basalis contralateral to their preferred turning direction in a radial maze. For chronic treatment, half the rats received saline (1 microliter/h for 4 days), and than GABA (100 micrograms/microliters/h) for the same period of time ('saline-first' group). In the other half, this sequence was reversed ('GABA-first' group). Acute microinjections of GABA decreased turning towards the non-injected side; chronic treatment enhanced this effect by reversing the preferred turning direction. Return to initial turning direction was observed after acute GABA-injection in both experimental groups, but only in the 'saline-first' group after chronic treatment. The 'GABA-first' group showed gliosis in and around the nucleus basalis area and a reduction of cortical acetyl-cholinesterase-positivity which were significantly greater than in the 'saline-first' group. This, chronic saline pretreatment is associated with diminished neurotoxicity of chronic GABA infusion and with a reversibility of the drug-induced behavioral effects.

Animals↗
PubMed1986

Long-term effects of nerve growth factor and neural transplants on behavior of rats with medial septal lesions.

The present experiment investigated the interaction between exogenous nerve growth factor (NGF) and intrahippocampal septal grafts on the behavior of rats after a medial septum lesion. Young female rats received a bilateral injection of a fetal septal cell suspension into the dorsal hippocampus either immediately (immediate grafts) or 8 days after the lesion (delayed grafts). For delayed grafts, a higher concentration of endogenous neurotrophic factors can be assumed to be present in the deafferentated host tissue at the time of transplantation. One group of rats with lesions received NGF with the immediate grafts, another group received NGF alone. A sham-operated group and 3 groups with lesions (and given either immediate or delayed intrahippocampal saline injections, or no other treatment) constituted controls. The animals were tested for spontaneous alternation and for performance in a radial 8-arm maze, 1, 5 and 9 months postoperatively. Medial septal lesions reduced spontaneous alternation but, 9 months after surgery, recovery was observed in both lesion-control rats and in rats with delayed grafts (but not with immediate grafts). In the radial maze task, lesions produced a persistent impairment, although both immediate and delayed grafts reduced this deficit several months after surgery (more markedly and rapidly in the case of delayed grafts). NGF, however, increased the maze learning deficit especially 5 months postoperatively. These latter results are in contrast to findings of earlier studies showing transient beneficial effects of NGF administration. It is suggested that the effects of NGF in the present study might be due to an enhanced sprouting of sympathetic fibers into the hippocampal formation.

Animals↗
PubMed1986

Unilateral fimbria/fornix lesions attenuate behavioral symptoms induced by subsequent dorsal hippocampal lesions in rats.

Adult rats were given a unilateral fimbria-fornix (5, 10, 15 micrograms colchicine or electrolytic) lesion 30 days before a restricted bilateral dorsal hippocampal lesion to assess the behavioral effects of temporally and structurally spaced lesions. The rats were tested 30 days after the second-stage surgery in the Hebb-Williams maze learning task. All rats with lesions were impaired in comparison with sham-operated control rats. However, those which sustained electrolytic or 5 micrograms colchicine fimbria-fornix lesions before hippocampal lesions were less impaired than rats which received hippocampal lesions alone or hippocampal lesions preceded by fimbria-fornix lesions with larger doses of colchicine.

Acetylcholinesterase↗
PubMed1986

The effects of postoperative physical environment on novelty seeking behaviour and maze learning in rats with hippocampal lesions.

The effects of different postoperative physical environments on novelty seeking and maze learning were tested in rats that sustained dorsal hippocampal lesions at 30 days. After surgery, rats were isolated for one month, either with objects or without objects in their cages. All rats were moved daily to new cages and observed during the first 5 min; during these periods, sham-operated rats and rats with lesions interacted similarly with their environment. At the end of the differential housing period, rats were tested for their reactions towards a novel object introduced to their familiar environment (test 1) and towards a novel environment they were free to explore or to avoid (test 2). In test 1, rats with lesions made more contacts with the novel object than did intact rats, and rats previously housed with objects, whether they sustained lesions or not, climbed on the novel object more often than rats reared without objects. In test 2, rats with lesions made no clear distinction between the novel and familiar environments irrespective of their postoperative treatment; in contrast, intact rats housed with objects differed from intact rats housed without objects in their preference for the novel and familiar environments and in the locomotor activity they displayed in these environments. Following these two tests, learning performance was assessed in an 8-arm radial maze. Rats with lesions made more errors than the intact rats, and within the rats with lesions those reared with objects tended to make fewer errors than those reared without objects.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Acetylcholine-rich transplants in the hippocampus: influence of intrinsic growth factors and application of nerve growth factor on choline acetyltransferase activity.

Three groups of rats received either unilateral fimbria-fornix lesions by aspiration through the overlying cingulate cortex (group I), a fimbria-fornix lesion followed by an intrahippocampal transplant of acetylcholine (ACh)-rich embryonic septal tissue (group II), or a similar septal transplant placed into the intact hippocampus, in the absence of the denervating lesion (group III). The 3 groups were subdivided into equal subgroups receiving 6 intrahippocampal injections of nerve growth factor (NGF) at 4-day intervals, control injections of cytochrome c, or no injections. On the 28th day all animals were sacrificed and the majority taken for biochemical analysis of hippocampal choline acetyltransferase (ChAT). The animals with intact hippocampi (group III) were given a denervating fimbria-fornix lesion 3 days prior to sacrifice in order to reveal graft-derived ChAT activity from intrinsic ChAT activity. The fimbria-fornix lesions (group I) depleted hippocampal ChAT activity to 15-20% of normal, which was not influenced by NGF injections. The ACh-rich grafts placed in the denervated hippocampus (group II) restored hippocampal ChAT activity to approximately 60% of the normal level, and this was promoted to approximately 84% of NGF, but not cytochrome c, injections into the hippocampus. Grafts placed into the intact hippocampus (group III) did not raise ChAT activity above the lesion-alone level, and this was not influenced by NGF injections. Acetylcholinesterase (AChE) histochemistry showed no difference in outgrowth from the grafts in the denervated hippocampus with or without NGF injections. The results are interpreted, in agreement with observations in tissue culture, as indicating that NGF enhances ChAT activity in grafted neurons, rather than promoting survival and growth per se.

Animals↗
PubMed1985

Transplantation of embryonic ventral forebrain neurons to the neocortex of rats with lesions of nucleus basalis magnocellularis--II. Sensorimotor and learning impairments.

The cholinergic projection from the nucleus basalis magnocellularis to the neocortex has been implicated in normal memory function and in the dementia of Alzheimer's disease. In order to investigate functions of this cholinergic system of the forebrain, rats with unilateral ibotenic acid lesions of the nucleus basalis magnocellularis have been compared with normal animals and with rats given cortically-placed transplants, either of cholinergic-rich embryonic ventral forebrain cells or of control noncholinergic cells taken from embryonic hippocampus. In the first experiment, lesions of the nucleus basalis magnocellularis led to impairments in step-through passive avoidance and Morris' water-maze tasks, and to locomotor hyperactivity attributable to a reduction in within-trial habituation. The ventral forebrain grafts, but not the noncholinergic hippocampal grafts, significantly ameliorated the deficits of passive avoidance retention, and of water-maze spatial accuracy, but had no effect on the acquisition impairments in either task, nor on the habituation deficit in locomotor activity of the nucleus basalis magnocellularis lesioned rats. In the second experiment, the lesions induced contralateral sensory neglect and ipsilateral turning biases, which were also partially ameliorated by the ventral forebrain grafts. The results support the hypothesis that the basal forebrain-neocortical cholinergic system contributes to certain memory processes, but suggest a more general role for this system in other cortical functions also.

Animals↗
PubMed1984

Working memory theory of hippocampal function needs qualification.

To compare the predictive value of "cognitive map" and "working memory" theories of hippocampal function, the performance of rats with dorsal hippocampal lesions was compared to that of control rats in a series of experiments. In Experiment I, experimental rats learned a spatial alternation task with normal ease, but in Experiment II, they were significantly impaired on an elevated 8-arm radial maze. In Experiment III, the performance of the same experimental and control rats was compared on two versions of a 16-arm enclosed radial maze. In the first version, carpet inserts served as cues to mark eight unbaited arms and each of the remaining arms contained one food pellet. While both experimental and control rats successfully avoided the set of cued arms, experimental rats reentered uncued baited arms more frequently than did control rats. In the second version no intramaze cues were provided, but the spatial distribution of baited and unbaited arms remained the same as that used in the first version. In this uncued version, experimental rats both entered unbaited arms and reentered baited arms more frequently than did control rats, i.e., they were impaired in both "reference" and "working" memory. These findings are compatible with the hypothesis that hippocampal lesions result in an impaired capacity to form cognitive maps but they are not compatible with the working memory hypothesis. Furthermore, twelve separate evaluators classed experimental rats as using fewer mapping and more orientation strategies than control rats in the 8-arm maze.

Animals↗
PubMed1980

Adverse reactions to contrast media: a report from the Committee on Safety of Contrast Media of the International Society of Radiology.

More than 300,000 case reports have been collected in a prospective survey of adverse reactions to intravascular contrast media. The reports were provided by radiologists in the United States, Canada, Europe, and Australia and represent the largest survey of its type to date. The overall incidence of reactions was about 5%, lower than any rate reported in the recent literature, and was strikingly similar in all participating countries.

Age Factors↗