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Biomedical subjects

M Palestini

Publications and source records attributed to M Palestini.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Overall biostatistical approach to the 24-h behavior of arterial blood pressure in chronic uremic normotensive patients].

The present study discusses the 24-h patterns of blood pressure in chronic uremic patients classified as normotensives by means of casual sphygmomanometric measurements. Data obtained enabled us to affirm that the blood pressure of normotensive chronic uremic patients is not normal due to a wider distribution, the occurrence of supraphysiologic values during day-night time and the absence of a circadian rhythm. The lack of a nocturnal decrease in blood pressure causes a hyperbaric impact on the arterial wall for "normotensive" chronic uremic patients.

Adolescent↗
PubMed1989

Effect of magnesium valproate on amygdala-kindled seizures in the rat: comparison with sodium valproate.

The anticonvulsant activity of a salt of valproic acid (VA), magnesium valproate (MgV), was assessed against amygdala-kindled seizures in rats. The anti-epileptic power of MgV was compared with that of sodium valproate (NaV). Kindling was obtained by delivering daily to one of the amygdala a 2 s train of monophasic square-wave pulses (1 ms, 60 c.p.s., 100-130 microA) via chronically implanted electrodes. Magnesium valproate and NaV were tested once kindling was stabilized and the post-kindling threshold for generalized convulsions was determined. The drugs were administered intraperitoneally in doses ranging from 25 to 200 mg/kg. The injection/test interval was 30 min. Each animal received a single dose every 24 h. Magnesium valproate exhibited an anticonvulsant activity qualitatively and quantitatively similar to that of NaV. Statistically significant differences were not found between the two drugs with respect to the reduction of seizure severity and afterdischarge (AD) duration. The calculated ED50's were 94.58 and 97.41 mg/kg for the suppression of generalized seizures, 176.96 and 129.26 mg/kg for the suppression of partial seizures, 275.96 and 224.13 mg/kg for the suppression of the local AD in the MgV and NaV treated groups, respectively.

Animals↗
PubMed1987

Medialis dorsalis thalamic unitary response to tooth pulp stimulation and its conditioning by brainstem and limbic activation.

In nembutalized cats tooth pulp stimulation (TPS) was effective in exciting 18% of medialis dorsalis (MD) thalamic units. Facilitation of spontaneous MD unitary discharge followed high frequency stimulation of the lateral amygdala (25%), dorsal hippocampus (22%), mesencephalic reticular formation (20%) and septal nuclei (17%). Conditioning high-frequency stimulation of limbic and reticular structures, strongly facilitated the MD unitary responses to TPS. None of the thalamic neurons involved in nociception seems to project to the cerebral cortex. The conditioning effect on MD response of limbic and reticular stimulation suggests that these central structures may be involved in the modulation of the nociceptive input.

Animals↗
PubMed1987

Radiological study of bone changes in the foot in chronic renal insufficiency.

The authors report the results of a radiological evaluation of the foot in 18 patients affected with chronic renal insufficiency (CRI). After discussing the bone changes considered to be "typical" of renal osteodystrophy, they analyse the trabecular system, in which they distinguish three degrees of change. If these finer changes are taken into account a high incidence of bony alteration is observed in CRI (84%). The biomechanics and static stresses of the foot are discussed, based on the presupposition that the anatomofunctional features of this part of the skeletal system could influence the grade and progression of the bony alterations. However, no such association was observed, nor was there any correlation between the radiographic changes and the clinical symptomatology.

Adolescent↗
PubMed1986

Electrophysiological projections of pulvinar-lateralis posterior complex (P-LP) upon superior colliculus units in the cat.

The effect of Pulvinar-Lateral Posterior (P-LP) electrical stimulation on superior colliculus unitary responses and eye movements is analyzed in 17 encéphale isolé cats. Twelve of them were curarized. Out of a total of 190 recorded units, 117 were localized in the superior colliculus and 73 units in the Mesencephalic Reticular Formation (MRF) below the superior colliculus. Thirty eight per cent (n = 45) of the collicular units modified their discharge frequency when the ipsilateral P-LP was electrically stimulated. The current intensity thresholds of transynaptic activation had a range between 0.5 and 2.0 mA. Most of the orthodromic responses were produced by ipsilateral P-LP stimulation and were localized in the intermediate and deep layers of the superior colliculus. Three types of responses were obtained: short latency responses between 2 and 10 ms (57%); intermediate latency responses between 15 and 40 ms (29%), and long latency responses between 50 and 200 ms (14%). Thirty one per cent (n = 18) of the units recorded in the MRF responded to P-LP stimulation with 10 ms pulse-trains duration. In the MRF 3 types of responses were observed: 1) a decrease or blockade in the resting discharge during 20 to 100 ms after stimulation (20%); simple responses with a latency between 25 and 150 ms (40%), and complex responses with an early response and a latency between 15-40 ms, and a late response with a latency between 150 and 200 ms (40%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Proximal arteriovenous fistulas for vascular access in periodic hemodialysis.

Six proximal arteriovenous fistulas were created in 6 uremic patients on periodic hemodialysis, in whom previous distal shunts or the interposition of heterologous materials had failed. The operations were performed with the vascularization of the upper limbs and a cutaneous incision at the bend of the arm. All patients were women. All the arteriovenous fistulas showed good functioning at the end of the procedure and follow-up from 0 to 45 months.

Adult↗
PubMed1983

Effects of cortical ablations on the turning response evoked by stimulation of the pulvinar-lateralis posterior nucleus complex in the cat.

The role played by the cerebral cortex on turning responses elicited by electrical stimulation of P-LP was studied in 9 chronic cats. In three animals the sensorimotor cortex was bilaterally ablated and the threshold values for inducing a turning response were determined. None of the cats showed abnormal threshold values. In six cats the cerebral cortical area known to have reciprocal anatomical connections with P-LP was unilaterally removed. Seven days after surgery, 50% of the electrodes gave no responses; 25% evoked responses with high thresholds and 25% with normal thresholds. One month after surgery the percentages were: 14, 18 and 68 respectively. Histological findings show important fiber and neuronal degeneration in P-LP. It is postulated that this area of the cerebral cortex plays, a facilitatory role on the P-LP ability to induce turning response and that the recovery of this ability can be explained by the development of P-LP denervation supersensitivity.

Animals↗
PubMed1982

The inhibitory effect of the olivocerebellar input on the cerebellar Purkinje cells in the rat.

1. In rats under Nembutal anaesthesia the inferior olive region has been reversibly inactivated by applying a cooling probe to the ventral surface of the medulla. Simple and complex spike activity has been recorded from Purkinje cells of the cerebellar cortex.2. Following cooling of the inferior olive of one side we have observed a remarkable increase of the simple spike activity in all the twenty-two Purkinje cells, showing a disappearance of the complex spike activity.3. In some rats two Purkinje cells were recorded simultaneously from each side of the cerebellar cortex. Following cooling of the left inferior olive the effect on the Purkinje cell was observed only or predominantly on the contralateral cerebellar cortex.4. In a group of animals the inferior olive has been destroyed by 3-acetylpyridine 4-221 days before the recording session. Cooling of the inferior olive region was not accompanied by any significant and consistent increase in the spike activity of presumed Purkinje cells of the contralateral cerebellar cortex.5. These results indicate that the remarkable increase of the simple spike frequency following cooling of the inferior olive region is due specifically to the suppression of the activity of the olivocerebellar neurones.6. Only a small amount of the simple spike frequency increase is attributable to the removal of the post-climbing fibre pause.7. In some lesioned rats recording was made from Purkinje cells, which showed complex spikes due to the few surviving inferior olive cells. In these Purkinje cells cooling of the inferior olive region was accompanied by a disappearance of the complex spike and by a small increase of the simple spike frequency of discharge. Such an increase is mainly attributable to the removal of the post-climbing fibre pause.8. These results suggest that a given Purkinje cell is not only under the inhibitory influence of its own climbing fibre, but also of other olivocerebellar neurones, probably through climbing fibre collaterals to the cerebellar cortical interneurones.9. It is suggested that one role of the olivocerebellar system is to exert a powerful tonic inhibitory action on the Purkinje cells and consequently to exert a significant control on the excitability of the subcerebellar centres.

Action Potentials↗
PubMed1982

The integrative sensorimotor function of the LP-pulvinar complex.

An important number of studies have paid attention to the sensorial function of the LP-pulvinar complex and its probable polisensorial integrative role. In the present review, on the basis of some experimental results, we have tried to emphasize the importance of the LP-pulvinar complex in the motor function. In this sense, this thalamic complex appears as a probable sensorimotor integrative structure. Considering the behavior elicited by electrical as well as chemical stimulation of the LP-pulvinar complex, it would seem that this structure is related to the type of behavior that researches and examines the environment, mainly, by internal motivation. Furthermore, the possible role of the LP-pulvinar complex in the sleep and wakefulness mechanism and in the epileptic phenomena, is mentioned.

Animals↗
PubMed1982

Effects of subcortical electrolytic lesions on the head-eye turning response induced by electrical stimulation of the cat's pulvinar-lateralis posterior nucleus complex.

The relations between three subcortical structures and P-LP, all of them capable of inducing contralateral head-eye turning responses when electrically stimulated, were studied in three groups of cats. In all the experiments stainless steel electrodes were chronically implanted in P-LP and in each group of five cats. Electrodes were also placed respectively in the caudate nucleus, superior colliculus and nucleus centralis lateralis. Series of current intensity threshold values for evoking head-eye turning responses were determined in each group, before and after electrolytic lesion of these three subcortical structures. The total observation period was approximately 30 days. Only the destruction of the superior colliculus produced the loss of the ability of the ipsilateral P-LP to evoke turning response. According to these results it is postulated that the efferent pathway that carries the information for turning response from P-LP runs through the ipsilateral superior colliculus.

Animals↗
PubMed1980

[Urinary excretion of arylsulfatases A and B in patients with renal transplants].

Arylsulfatase A and B activities have been determined in urine samples from four patients who received a Kidney allograft from living donors as a treatment for terminal uraemia. The values have been compared with those obtained in the urine of the respective donors. Two patients, with optimal renal functionality, the enzymatic activities were in the order of that observed in the urine of the donor in one case and lower than that of the donor in the other case. A patient showing kidney rejection episodes, reversed by the specific therapy, had the enzymatic activities higher than those shown by the donor. Another patient who suffered for two rejections, the last one irreversible, showed a constant higher value of the two enzymatic activities compared with those of the donor and a further increase during the rejection period. In the light of these preliminary results it seems that the determination of the arylsulfatase activities in the urine of transplanted subjects could contribute to establishing the functional activity of the transplanted kidney and also in establishing the tendency of the kidney to undergo rejection.

Adolescent↗
PubMed1980

[Esterification of cholesterol in patients with renal transplants. Determination of lecithin:cholesterol-acyl-transferase (LCAT) activity].

In man, cholesterol esterification is controlled by lecithin:cholesterol-acyl-transferase (LCAT), which is a key-role enzyme of lipid metabolism. Though LCAT is synthesized by the hepatocytes, its activity seems to be linked to the kidney: in fact, LCAT activity is lowered in uremic and anephric subjects, and probably also in long-term haemodialysis patients. On the contrary, in successfull renal allografts we found fully restored LCAT activity. But physiopathological mechanisms underlying relationships between LCAT and kidney are still unclarified.

Cholesterol↗