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Biomedical subjects

L Bergamasco

Publications and source records attributed to L Bergamasco.

10 recordsLinked to original sources
PubMed2005

Pathways of glomerular toxicity of cyclosporine-A: an "in vitro" study.

BACKGROUND/AIMS: Knowledge of renal toxicity of cyclosporine-A (CyA) is clouded by multiple effects on different glomerular and tubular cells and on kidney and systemic hemodynamics. To focus on glomerular action of CyA we used glomeruli isolated in vitro, with the aim of dissecting the effects on recruitment of glomerular vasoconstricting systems, like endothelin-1 (ET) and angiotensins (AI and AII). METHODS: We studied the pathways of CyA damage on pig glomeruli isolated in vitro with the technique of sieving through mesh filters of different sizes, and incubated in an appropriate culture medium. The supernatant was sampled at different time intervals to measure ET, AI and AII concentrations upon addition of ET 10(-12) or CyA 4x10(-7)M, with or without either selective endothelin receptor A (ETA) or B (ETB), or unselective ETA-ETB receptor inhibitors. RESULTS: CyA increased ET concentration (from 9.7+/-0.3 to 11.4+/-0.4 pgxml-1, p<0.002), and the added ET released AI in the medium (from 26.6+/-4.7 to 39.1+/-4.6 pgxml-1, p<0.05) when ETB receptors were blocked. In contrast, CyA stimulated angiotensins release independent of ET receptors blockade, hence, irrespective of ET concentration in the medium, from 26.6+/-4.7 to 38.0+/-2.1 pgxml-1 for AI, p<0.05, and from 12.3+/-1.0 to 14.8+/-0.9 pgxml-1 for AII, p<0.05. CONCLUSION: CyA releases ET and angiotensins independently by a direct action. Glomerular CyA toxicity might be mediated by recruitment of vasoconstricting peptides and modulated by relative ETA and ETB receptor occupancy.

Angiotensin I↗
PubMed2003

Quantitative electroencephalographic findings in beagles anaesthetized with propofol.

The purpose of this study was to assess quantitative electroencephalography (q-EEG) in 10 healthy beagle dogs under propofol anaesthesia in order to determine objective guidelines for diagnostic electroencephalographic (EEG) recordings and interpretation. The basic pattern after preliminary visual examination of EEG recordings was characterized by spindles, k-complexes, vertex sharp transients, and positive occipital transients that were superimposed on the slow background activity. The results of the q-EEG were characterized by the prevalence of slow rhythms delta and theta, both in absolute and relative power spectrum analysis, while fast rhythms (alpha and beta) were poorly represented. The distribution of single frequency bands was widespread for delta, focal for frontal and central for theta, as well as for most alpha and beta patterns. The present study has shown that the use of quantitative EEG gives information on the frequency content of the bio-electrical activity and defines the distribution of the single frequency bands under a standardized anaesthetic protocol.

Anesthesia, General↗
PubMed2000

Neuropsychological and neurophysiological evaluation after anterior communicating artery (ACoA) aneurysm surgery.

BACKGROUND: We evaluated high cerebral functions 6 months after surgery for bleeding ACoA aneurysms comparing neurophysiological and neuropsycological tests. METHODS: Twelve patients were chosen among a series of cases operated on in the first 48 hours after ACoA aneurysm bleeding. All of them were in Hunt-Hess grade I or II. We excluded patients over 65 years, or with intracranial haematomas, intraventricular haemorrhage, hydrocephalus, or with multiple or giant aneurysms. All of them underwent neurophysiological evaluation with recording and mapping of long latency (P300) auditory and visual event-related potentials (ERPs) and a neuropsychological assessment for memory, intelligence, frontal lobe functions and language. RESULTS: Neuropsychological assessment: All patients were severely damaged on phonemic fluency. In a first group (group A: 3 cases) tests were all in a normal range. In a second (group B: 3 cases) the tests showed severe impairment on learning and long term memory. In a third (group C: 6 cases) tests showed memory and "frontal lobe" deficits. Neurophysiological assessment: The whole group of patients showed significant delay in ERPs recordings compared to controls. ERPs of patients in group A and B showed no significant differences from controls, while being significantly delayed in 5 patients out of 6 of group C. CONCLUSIONS: All patients had difficulties in the phonemic task in which a notable cognitive effort is necessary, while intelligence, short term memory, attention and language were within normal limits. Patients in group C showed severe frontal lobe type cognitive impairment. Those ones in groups A and B did not present cognitive derangements (A) or only memory and learning impairment (B). ERPs may be an objective parameter in the follow-up of cases with cognitive impairment, even if neurophysiological tests cannot be replaced.

Event-Related Potentials, P300↗
PubMed1999

Canine dilated cardiomyopathy: lymphocyte and cardiac alpha(1)- and beta-adrenoceptor concentrations in normal and affected great danes.

Serum catecholamine levels and myocardial and lymphocyte adrenergic receptor (AR) concentrations were measured in adult great danes affected by canine dilated cardiomyopathy (DCM) and compared to those of healthy animals. A non-homogeneous population of beta -AR, consisting of beta(1)-AR and beta(2)-AR, was observed in healthy (41 and 59%, respectively) and affected (17 and 83%, respectively) dog lymphocytes. Binding assays revealed that total beta -AR, beta(1)-AR and alpha(1)-AR were significantly downregulated (P<0.05;P<0.01;P<0. 001), both in lymphocyte and myocardial cell membranes of affected dogs. beta(2)-Adrenergic receptor concentrations were significantly reduced only in lymphocyte and right atrium cell membranes (P<0.05). Downregulation was not associated with alterations in receptor binding characteristics, as no significant differences in K(d)values were found. Mean plasma catecholamine levels were significantly higher (P<0.01) in DCM dogs (939+/-41) than in normal subjects (348+/-32), thus suggesting a sympathetic activation. The present study indicates a condition similar to that observed in human patients affected by DCM and that adrenergic receptors in canine lymphocytes reflect the fluctuation of adrenergic receptor concentrations in the myocardium.

Adrenergic alpha-Antagonists↗
PubMed1999

Lymphocyte beta -adrenoceptor downregulation in great danes with occult dilated cardiomyopathy (DCM) and with DCM and heart failure.

The importance of the adrenergic nervous system in supporting the failing heart has long been known. The adrenergic drive on cardiac structure and function has however some adverse effects, which include myocardial beta-adrenoceptor (beta-AR) downregulation and decreased beta-adrenergic responsiveness to cathecolamines. In dog lymphocytes, beta(1)-AR and beta(2)-AR populations are almost equally represented (with a slight prevalence of beta(2)) and a significant correlation between cardiac and lymphocytic adrenoceptors has been found. The aim of the present study was to investigate possible differences between the concentration of lymphocytic beta-AR in healthy dogs, dogs with dilated cardiomyopathy (DCM) and dogs with occult DCM. Three groups of great danes were considered: a control group (n =10), dogs with DCM (n =9) and dogs with occult DCM (n =4). Lymphocytic beta-AR populations were determined in all dogs. A substantial and significant decrease (P<0.05) in total-AR, beta(1)-AR and beta(2)-AR concentrations in the lymphocytes of dogs with symptomatic DCM and occult DCM compared to the control group was found. Although the mean value of the lymphocyte beta(1)-AR number in the asymptomatic group was double compared to the DCM group, this difference was not statistically significant. We conclude that in dogs beta-AR downregulation occurs early in the course of dilated cardiomyopathy. This finding may suggest the value of early use of a beta-blocker in the therapeutic regimen. Moreover, the continuous monitoring of lymphocytic beta-AR may represent a useful tool for the development of a more effective individual therapy.

Animals↗
PubMed1998

Neurophysiologic assessment of nerve impairment in posterolateral and muscle-sparing thoracotomy.

OBJECTIVE: This study was aimed at analyzing the degree of intercostal nerve impairment in posterolateral and muscle-sparing thoracotomy and at correlating the nerve damage to the severity of long-lasting postthoracotomy pain. METHODS: Neurophysiologic recordings were performed 1 month after either posterolateral or muscle-sparing thoracotomy to assess the presence of the superficial abdominal reflexes (mediated in part by the intercostal nerves), the somatosensory-evoked responses after electrical stimulation of the surgical scar, and the electrical thresholds for tactile and pain sensations of the surgical incision. RESULTS: The patients who underwent a posterolateral thoracotomy showed a higher degree of intercostal nerve impairment than the muscle-sparing thoracotomy patients as revealed by the disappearance of the abdominal reflexes, a larger reduction in amplitude of the somatosensory-evoked potentials, and a larger increase of the sensory thresholds to electrical stimulation for both tactile perception and pain. In addition, these neurophysiologic parameters were highly correlated to the postthoracotomy pain experienced by the patients 1 month after surgery, indicating a causal role for nerve impairment in the long-lasting postoperative pain. CONCLUSIONS: This study shows for the first time the pathophysiologic differences between posterolateral and muscle-sparing thoracotomy and suggests that the minor long-lasting postthoracotomy pain in muscle-sparing thoracotomy patients is partly due to a minor nerve damage. In addition, because nerve impairment is responsible for the long-lasting neuropathic component of postoperative pain, it is necessary to match specific treatments to the neuropathic pain-generating mechanisms.

Case-Control Studies↗
PubMed1997

Chronic triventricular hydrocephalus: morphological and functional study before and after ventriculoperitoneal shunting.

We have neuroradiologically and neuropsycho-physiologically studied a case of chronic hydrocephalus due to congenital acqueductal stenosis, before and after ventriculoperitoneal shunting. The aims of the study were: 1) to point out the correlation between neuroimaging (Computerized Tomography/Magnetic Resonance Imaging) and mapping of Computerized Spectral Analysis EEG (CSA-EEG); 2) to monitor evoked bioelectrical activity by neurophysiological evaluation of acoustic and visual N1 and P3. Both bioelectrical activity and neuroimaging evaluation showed a considerable recovery of the neurobiological substratum after neurosurgical shunting, while neuropsychological investigation showed a slight improvement in all cognitive tasks.

Adult↗
PubMedDate not supplied

Lack of association between vigabatrin and impaired cognition.

Of 14 patients with a history of partial epilepsy who received vigabatrin 2 g daily for 6 months, eight were newly diagnosed and received vigabatrin as monotherapy, while the remaining six received vigabatrin in addition to pre-existing treatment with phenobarbitone. Neurophysiological and neuropsychological evaluations, done before and after the therapeutic period, included the Luria-Nebraska neuropsychological battery (LNNB), electroencephalograms (EEGs) and evoked potentials. The results for each item of the test battery at baseline were compared with those after 6 months' treatment. There were no statistically significant differences on the functional scales of the LNNB, the EEG or the evoked potentials. There was a significant improvement (P = 0.01) in the LNNB topographic scales for the right frontal lobe and the motor-sensory area following treatment. These results indicate that vigabatrin has no detrimental effects on cognitive function and may improve function.

Adolescent↗
PubMedDate not supplied

Time information in Poggendorff visual illusion: visual evoked potentials.

Using the component sets of the Poggendorff visual illusion as optical stimuli (comprising two horizontal and parallel segments intersected by two oblique segments), we recorded the respective visual evoked potentials (VEPs). Depending on the different delta t passing between the constitutive elements of the Poggendorff illusion, it was found that there was a greater latency of VEP components for the visual stimulus presentation sequence in which oblique segments are projected before horizontal segments.

Adult↗