Biomedical subjects

M Alessandri

Publications and source records attributed to M Alessandri.

At least 19 recordsLinked to original sources

PubMed2006

Plasma changes of calcitonin gene-related peptide and substance P in patients with dialysis headache.

Little is known of mechanism of dialysis headache (DH). As suggested for migraine, a role for neuropeptides has been investigated. Twenty-four patients under haemodialysis were studied. Twelve of them suffered from DH. The remaining patients were headache free. Blood samples for radioimmunoassay of calcitonin gene-related peptide (CGRP) and substance P (SP) were collected from the arteriovenous fistula before and after dialysis treatment. Basal plasma concentrations of CGRP were found to be higher in headache patients. Dialysis significantly decreased CGRP concentrations in both groups. No difference in basal plasma concentrations of SP was observed between groups. At the end of the treatment plasma SP concentrations were reduced in headache-free patients but increased in headache patients. Elevated plasma concentrations of CGRP in patients with DH could represent a biochemical factor contributing to susceptibility to headache. Because of the disputable role of SP in migraine, the significance of the increase of the peptide in plasma during DH remains to be elucidated.

Adult↗

PubMed2005

[Can we cure autism? From outcome to intervention].

Outcome in autism is variable but with a significant trend toward a poor prognosis and despite reports that outcome in individuals with autism may be improving secondary to early intensive interventions there is still much to be learned about the natural history and the effects of intervention in autism spectrum disorders. While there may not be a known cure for autism, there are a number of viable treatment options available. The primary models of treatment are non pharmacological interventions that include intervention models such as applied behavior analysis and developmental and structured teaching. The role of pharmacological interventions is limited to treating specific symptoms that may be interfering with a child's ability to learn or function within a particular environment. The question of whether or not we can cure autism needs to be discussed in terms of the need to overcome the as of yet poorly understood fundamental disturbance in autism and the need to develop treatment protocols specifically targeting social deficits. At the present time, it is more appropriate to speak of our quest to understand autism than it is to speak of a cure.

Autistic Disorder↗

PubMed2005

[The social deficit in autism: focus on joint attention].

INTRODUCTION AND DEVELOPMENT: Autism is best thought of as a spectrum disorder with the dimensional components of social cognition, communication and flexibility varying between individuals meeting the criteria of autism. The core clinical feature that defines autism is a disturbance in social interaction which is not absolute and differs depending on a child's cognitive level, developmental stage, and the type of social structure in which they are observed. Social skills are under strong genetic influence with a continuous distribution of social interaction deficits in the general population with arbitrary cutoffs defining who is and is not affected with an autism spectrum disorder; this is the result of a complex interplay between numerous biological and environmental factors. Joint attention refers to the capacity of individuals to coordinate attention with a social partner in relation to some object or event and a disturbance in this early skill and in particular impairment in the ability to initiate joint attention, is a central symptom of autism. CONCLUSIONS: There are data to suggest that dorso-medial frontal cortex and anterior cingulate contribute to the development of an infant's ability to maintain representations of self, a social partner and an interesting object. The ability to engage frequently in social orienting behaviors and ultimately in numerous episodes of social attention coordination, or joint attention, may be a critical experience during a particular developmental window that serves to organize social neurodevelopment. A neurodevelopmental model explaining how these early deficits in social cognition may lead to autism is reviewed.

Autistic Disorder↗

PubMed2002

Agonist-induced internalization and desensitization of the human nociceptin receptor expressed in CHO cells.

In this study, we examined agonist-induced internalization, recycling and signalling (measure of cAMP levels) of the cloned human nociceptin receptor (hNOP) expressed in CHO-K1 cells. Internalization was proven by a receptor-binding assay on viable cells. The agonist nociceptin/orphanin FQ (NC) promoted rapid internalization of the hNOP receptor (approximately 78% of cell surface receptors were lost after 2 min exposure to 1 microM NC) in a clathrin- and ATP-dependent manner. Internalization was more rapid and marked in CHO-K1 cells than, as we previously reported, in SK-N-BE cells. This difference may be related to higher levels of beta-arrestin isoforms detected in CHO-K1 than in SK-N-BE cells. hNOP receptor internalization was partially reversible and recycling occurred in the presence of the agonist; receptor recycling was dependent on okadaic acid-sensitive phosphatases and was blocked by monensin. Confocal microscopy analysis confirmed the internalization and the recycling back to the plasma membrane of an epitope-tagged hNOP receptor expressed in CHO-K1 cells. These receptors underwent rapid desensitization upon agonist challenge: NC efficacy in inhibiting forskolin-stimulated cAMP production was significantly reduced 10 min after exposure and correlated with the rate of receptor internalization. Moreover, we observed that blockade of hNOP receptor recycling by monensin would cause a more prolonged and relevant desensitization of this receptor. Thus, the dynamic cycle between hNOP receptor activation, internalization and recycling determines the activity of this receptor on the cell surface.

Animals↗

PubMed2000

Nitridation of gate and tunnel oxides employed in CMOS-ULSI technology

Nitridation treatments are very important in CMOS technology because of their capability of improving the gate and tunnel oxide reliability. In this work we report on N2O and NO annealing of pre-oxidised samples showing physical and electrical characteristics of the thin oxides. The difference between the physical behaviours of N2O and NO oxides is evidenced and related to their different electrical properties.

Journal Article↗

PubMed2000

Dopamine involvement in the migraine attack.

Clinical evidence and recent genetic findings seem to indicate an involvement of dopamine in the pathophysiology of the migraine attack. Prodromal symptomatology (mood changes, yawning, drowsiness, food craving), accompanying symptoms (nausea, vomiting, hypotension) and postdromal symptoms (mood changes, drowsiness, tiredness) may be related to dopaminergic activation. The dopaminergic system could also play a role in the headache phase, either by taking part in nociception mechanisms, or by regulating cerebral blood flow. A body of pharmacological findings seems to support this involvement. Migraine patients, between attacks, show a higher responsiveness to acute administration of dopaminergic agents. Apomorphine administration induces in migraineurs more yawns as well other dopaminergic symptoms e.g. nausea, vomiting, dizziness. Migraine has been associated with hypotension and, occasionally, with syncope. Bromocriptine causes severe orthostatic syndrome in migraine patients. Both piribedil and apomorphine markedly increase cerebral blood flow of migraine patients, thus indicating enhanced responsiveness of dopamine receptors which are involved in cerebral blood flow regulation. Interictal dopaminergic hypersensitivity has also been demonstrated by means of neuroendocrine tests. Altered dopaminergic control of prolactin secretion exists in migrainous women. L-deprenyl, a MAO-B inhibitor, is significantly more effective in reducing prolactin levels in migraineurs than in controls. Taken together, these findings support the view that hypersensitivity of peripheral and central dopaminergic receptors is a specific migraine trait. Finally, a high density of lymphocytic D5 receptors has been found in migraine sufferers, thus suggesting their upregulation. Therefore, the hypothesis that dopaminergic activation is a primary pathophysiological component in certain subtypes of migraine, namely those characterised by marked dopaminergic symptomatology, has been advanced. From this perspective, a blockade of dopaminergic hyperresponsive receptors can be considered as a rationale for the therapy of migraine.

Dopamine↗

PubMed1999

A case of neurofibromatosis type 1 with an aldosterone-producing adenoma of the adrenal.

Neurofibromatosis type 1 is a phacomatosis. Neurofibromas are the most common tumours associated with the disease, and along with other tumours, make neurofibromatosis type 1 the most common tumour predisposing syndrome in humans. Hypertension may be coincidental, but at least two specific neurofibromatosis related causes must be considered, namely neurofibromatous involvement of the renal artery and pheochromocytoma. We have described the first known case of a patient with neurofibromatosis type 1 who developed hypertension due to an aldosterone-producing adenoma of the adrenal. The question of whether this association was coincidental or due to the tumour predisposition of neurofibromatosis type 1 was debated.

Adenoma↗

PubMed1998

Early dysfunction of iris sensory fibres in diabetic patients.

BACKGROUND: The present study was designed to propose transcutaneous electrical nerve stimulation (TENS) of the infratrochlear nerve as a noninvasive test useful in the detection of early iris small nerve fibre dysfunction in patients with diabetes mellitus. METHODS: A total of 32 diabetic patients with no symptoms or signs of diabetic neuropathy were enrolled from a clinical practice. Sixteen of them, 6 women and 10 men, ranging in age from 19 to 53 years, had been affected by IDDM for 13 +/- 2 years. The remainder, 6 women and 10 men, age range 32 to 58 years, were suffering from NIDDM (duration of manifestation 5 +/- 1 years). Twenty-six healthy individuals, 11 women and 15 men, ranging in age from 21 to 47 years, served as controls. Pupil area changes induced by TENS of the infratrochlear nerve were investigated. The electrical stimulus was not painful and consisted of a single square wave pulse of 40 mA intensity and 0.8 ms duration. Measurements were carried out by means of a TV monocular electronic pupillometer. RESULTS: A clear-cut miosis was provoked in controls (p < 0.01 versus basal values 100 sec to 220 sec from stimulation). NIDDM patients also showed a miotic response, but it was slower in onset (p < 0.05 versus basal values 140 sec after stimulation) and shorter (p < 0.01 at 180 sec from stimulation) in duration. No pupillary changes were registered in IDDM patients. CONCLUSIONS: An abnormality of iris sensory nerve fibres in inducing pupillary constriction was detected in both diabetic groups. The differences in the severity of the dysfunction could be related to the differences in duration of the disease among the diabetic patients in the two groups. In conclusion, TENS of the infratrochlear nerve could represent an original noninvasive method in detecting early iris sensory alterations in diabetic patients.

Adult↗

PubMed1997

Responsiveness of the trigeminovascular system to nitroglycerine in cluster headache patients.

Nitroglycerine is known to induce a headache attack in cluster headache patients, which is indistinguishable from a spontaneous attack. It has recently been suggested that a release of calcitonin gene-related peptide (CGRP) from peripheral terminals of trigeminal nociceptive neurons, which supply cephalic blood vessels, underlies symptoms of cluster headache. The aim of this study was to investigate whether the provocative action of nitroglycerine in cluster headache is due, at least in part, to activation of the trigeminovascular system. Nineteen subjects suffering from episodic cluster headache participated in the study. Eleven of them were in an active period, whilst the others were in remission at the time of the study. CGRP-like immunoreactivity (CGRP-LI) was measured in blood samples from the extracerebral circulation before and after the sublingual administration of nitroglycerine. Baseline CGRP-LI plasma levels were higher (P < 0.05) in the patients who were in an active period. Only in these patients did nitroglycerine induce an attack, which was preceded by a latent period with a mean duration of 27 +/- 3 min. When compared with the baseline, a significant (P < 0.01) increase in plasma CGRP-LI was detected at the peak of the provoked attack; no such increase was detected during the latent period, or at the onset of the attack. The results of this study suggests that the provocative action of nitroglycerine in cluster headache is due, at least in part, to activation of the trigeminovascular system. This mechanism seems to be slow and unrelated to the well-known rapidly occurring vasodilator effects of the drug. Finally, activation of the trigeminovascular system only occurs in those patients already in an active cluster headache period who also have high basal CGRP-LI plasma levels. This suggests that a hyperactivity of trigeminal nociceptive fibres could make the trigeminovascular system of these patients sensitive to the triggering action of nitroglycerine.

Adult↗

PubMed1995

Buspirone, but not sumatriptan, induces miosis in humans: relevance for a serotoninergic pupil control.

BACKGROUND AND OBJECTIVE: Drugs that act on the serotoninergic system have been shown to influence the pupil size. However, the 5-hydroxytryptamine (5-HT) receptor type or subtype that affects pupil diameter has not been defined in humans. With a placebo-controlled, double-blind randomized design, we investigated in healthy volunteers the effect on pupil size of buspirone and sumatriptan, which mainly act on 5-HT1A- and the 5-HT1-like receptors, respectively. METHODS: The pupil area was measured by means of a videopupillometer before and after a single oral administration of placebo or of three different doses of active drugs. Heart rate and arterial blood pressure were recorded after pupil area measurement. RESULTS: Buspirone (5, 10, and 20 mg) caused a dose-dependent miosis. Sumatriptan (50, 100, and 200 mg) did not affect the pupil size. Twenty milligrams of buspirone reduced the mydriasis induced by pretreatment with homatropine eyedrops. A 20 mg dose of buspirone reduced blood pressure without change in heart rate, whereas buspirone, at doses lower than 20 mg, and sumatriptan did not affect heart rate and blood pressure. CONCLUSIONS: This study suggests that buspirone, but not sumatriptan, the selective agonist of 5-HT1-like receptors, causes miosis in humans by activation of 5-HT1A receptors, possibly located in the central nervous system where they inhibit iris sympathetic pathways. Measurement of pupil size seems to provide a valuable and sensitive index of 5-HT1A receptor function in humans.

Administration, Oral↗

PubMed1993

Substance P-induced fibrinolysis in the forearm of healthy humans.

Physiological saline with or without substance P (50 ng/ml) was infused into the humeral artery in 6 healthy males. Indices of fibrinolytic activity (whole blood diluted lysis time, euglobulin lysis time, lysis areas in non-heated fibrin plates produced by plasma or euglobulin precipitate, plasminogen plasma levels, alpha 2-macroglobulin, C1-inhibitor, and alpha 2-antiplasmin) were evaluated in the homolateral antecubital vein before and after 5 min of substance P or saline infusion. After substance P the fibrinolytic activity increased, as can be seen from the shortening of lysis times (p < 0.01) and enlargement of the lysis areas (p < 0.01). A reduction of plasminogen plasma levels (p < 0.01), associated with a decrease in alpha 2-antiplasmin (p < 0.01), was also found. Alpha 2-macroglobulin and C1-inhibitor were instead unaltered by the peptide. The saline infusion, on the other hand, was unable to modify any of the examined indices. We concluded that exogenous substance P given intra-arterially increases fibrinolytic activity in locally-sampled venous blood through a mechanism which remains to be elucidated.

Adult↗

PubMed1993

Possible long-lasting inhibition of converting enzyme by enalapril in human cerebrospinal fluid.

1. Converting enzyme and neutral endopeptidase activities were both measured every 3 h by a fluorimetric method in plasma and cerebrospinal fluid of patients diagnosed as migraineurs with aura after lumbar puncture, which was performed 9 h after an acute oral dose of enalapril or placebo. 2. A reduced converting enzyme activity, as compared with placebo, was observed in patients who were given enalapril. On the other hand, neutral endopeptidase activity detected after enalapril did not differ from that measured after placebo. 3. The results seem to indicate that enalapril penetrates the blood-brain barrier in sufficient amounts to reduce converting enzyme activity. Moreover, neutral endopeptidase was not affected by enalapril. Therefore, those clinical effects of the drug which have been attributed to the involvement of central opioid mechanisms may depend on the inhibition of brain converting enzyme but not the inhibition of brain neutral endopeptidase.

Adult↗

PubMed1992

Long-term ergotamine abuse: effect on adrenergically induced mydriasis.

The mydriatic action of sympathomimetic eyedrops after a therapeutic dose of ergotamine was measured in migraine patients with and without histories of long-term ergotamine abuse. Mydriasis induced by the postsynaptic alpha 1-agonist phenylephrine was similar in both groups of patients tested, whereas pupillary dilation caused by the release of noradrenaline tyramine was markedly greater in patients with histories of ergotamine abuse. The enhanced response to tyramine disappeared after drug withdrawal. These findings indicate that continuous ergotamine medication causes a reversible alterations in iris sympathetic transmission. This manifestation may reflect a central inhibition of pupillary sympathetic activity.

Adult↗

PubMed1992

Action of nimodipine on sympathomimetic mydriatics in humans.

In 12 healthy volunteers, the effects of a single oral dose of nimodipine (40 mg) on pupil size and on the mydriasis induced by conjunctival instillation of tyramine and phenylephrine were studied by using a TV monocular infrared pupillometer. Nimodipine alone was unable to modify the pupil area. When compared with placebo, the Ca2+ entry blocker reduced the pupil dilation caused by tyramine, whereas it did not affect the phenylephrine-induced mydriasis. Since tyramine provokes mydriasis by releasing neuronal norepinephrine, a full adrenoceptor agonist, whereas phenylephrine acts only on alpha 1-adrenoceptors insensitive of extracellular Ca2+, the hypothesis may be advanced that a heterogeneous population of alpha-adrenoceptors, located in the human iris dilator muscle and differently sensitive to Ca2+ entry blockade, is responsible for the reduction of the tyramine-induced mydriasis. Apart from this putative mechanism, the results suggest that nimodipine reduces the pupillary response to adrenergic activation in the human eye.

Administration, Oral↗

PubMed1992

Analgesic effect of capsaicin in idiopathic trigeminal neuralgia.

Twelve informed and consenting patients were studied to determine the influence of capsaicin, the pungent component of the red pepper, on trigeminal neuralgia. All of these patients had idiopathic trigeminal neuralgia. These patients were followed up for 1 yr after the topical application over the painful area of 1.0 g of capsaicin three times a day for several days. Six patients had complete and four patients had partial relief of pain; the remaining two patients had no relief of pain. Of the 10 patients who were responsive to therapy, four had relapses of pain in 95-149 days. There were no relapses following the second therapy for the remainder of the year. We conclude that the topical application of capsaicin is frequently successful in relieving the pain from trigeminal neuralgia.

Analgesia↗

PubMed1991

Kallidin applied to the human nasal mucosa produces algesic response not blocked by capsaicin desensitization.

Various kinins (dissolved in 50 microliters) were applied to the nasal mucosa of healthy human volunteers to test the algesic and proinflammatory effects of these peptides in an intact human tissue. [des-Arg9]-bradykinin (0.5 mumol) was found to be inactive, while bradykinin (0.05-0.5 mumol) and especially kallidin (0.005-0.5 mumol) induced: (a) a mild painful sensation described as burning and pricking (latency 30 s, duration 3-5 min), (b) perception of pulsatility and obstruction in the nasal cavity (onset 1 min, duration 6-8 min). Substance P (0.5 mumol) and neurokinin A (0.5 mumol) produced slight obstruction and weak pulsatile sensation but not pain. Capsaicin (0.05 nmol) produced pain and secretion of fluid, but not pulsatile sensation. The effects of kallidin were not affected by repeated (to induce desensitization) applications of capsaicin (0.5 mumol). Likewise, ipratropium bromide (80 mg in 100 microliters) did not affect responses to kallidin. In an intact human tissue, kallidin produces various effects, including an algesic response, that are apparently independent from activation of B1 receptors and from desensitization of capsaicin-sensitive primary afferents.

Adult↗

PubMed1991

Hypertonic media produce Ca(2+)-dependent release of calcitonin gene-related peptide from capsaicin-sensitive nerve fibres in the rat urinary bladder.

Superfusion of slices of the rat urinary bladder with hypertonic NaCl produced a remarkable and concentration-dependent (150-280 mM) increase in the outflow of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI). This effect was completely abolished by pre-exposure of the tissue to capsaicin (10 microM for 20 min) or by superfusion with a Ca(2+)-free medium. Capsaicin (10 microM) was still able to release a consistent amount of CGRP-LI from tissue pre-exposed (20 min) to 280 mM NaCl. Similarly, hypertonic sucrose (160 mM added to the physiological salt solution) induced a consistent release of CGRP-LI that was abolished by capsaicin-pretreatment or in a Ca(2+)-free medium. The experiments demonstrate that hypertonic solutions activate the efferent function of capsaicin-sensitive neurons and suggest that this event may have some relevance in pathophysiological conditions of the lower urinary tract in which hypertonic urine may diffuse to submucosal layers.

Animals↗

PubMed1991

Social policy on the use of aversive interventions: empirical, ethical, and legal considerations.

In an effort to address the controversy regarding the use of aversive interventions in the treatment of individuals with developmental disabilities, this paper presents a review of the literature on the efficacy of such interventions, along with brief reviews of the ethical and legal issues involved. In general, there appears to be empirical, ethical, and legal support for the continued availability of aversive interventions as treatment options, but only if sufficient safeguards are in place.

Autistic Disorder↗