Alessandro Napolitano

Clinical outcome and magnetic resonance imaging of carbon monoxide intoxication. A long-term follow-up study.

Abstract The clinical and neuroradiological outcome of carbon monoxide (CO) intoxication was evaluated prospectively in 30 patients over a follow-up period of 3 years. Among the patients studied, 22 had been acutely exposed to CO while 8 were chronically exposed.One month after CO poisoning, 12 of the 22 patients with acute intoxication showed magnetic resonance imaging (MRI) abnormalities: 6 also had neurological sequelae and 6 were asymptomatic. The remaining 10 patients showed neither MRI abnormalities nor neurological sequelae. During the 3-year follow-up, 4 of the patients with both MRI abnormalities and neurological sequelae improved in both clinical features and MRI findings. One of the 6 asymptomatic patients with MRI abnormalities developed a progressive cognitive impairment 2 months after acute intoxication, with a concomitant severe worsening of the MRI lesions. Among the 10 patients with neither MRI abnormalities nor neurological sequelae, only 1 developed neurological sequelae after a clear period of 4 months.In the group of patients who experienced chronic CO intoxication, only 1 presented with a neuropsychiatric syndrome which improved at follow-up. Brain MRI showed white matter lesions which remained unchanged at control scan after 1 year.In conclusion, we observed that some patients with severe CO poisoning and neurological sequelae may fully regain normal functions after approximately 1 year. The presence of MRI lesions 1 month after CO poisoning did not accurately predict the subsequent outcome. The observation of a clear period longer than the usual 2–40 day interval in 2 patients should be considered for careful planning of follow-up and for prognosis in CO-poisoned patients.

Effects of peripheral and central catechol-O-methyltransferase inhibition on striatal extracellular levels of dopamine: a microdialysis study in freely moving rats

Tolcapone is a mixed (peripheral and central) catechol-O-methyltransferase (COMT) inhibitor, whereas entacapone is a preferential peripheral COMT inhibitor. Both drugs are able to decrease the peripheral conversion of L-DOPA into 3-O-methyl-DOPA and thereby increase plasma and cerebral levels of L-DOPA, the precursor of dopamine (DA). Tolcapone may also impair the extraneuronal catabolism of DA by inhibiting COMT activity in the brain. To evaluate the role played by peripheral and central COMT inhibition, we compared the effects of tolcapone and entacapone on COMT activity in peripheral tissues, and on striatal extracellular levels of L-DOPA and DA in rats. Tolcapone and entacapone, at the dose of 15 mg/kg p.o., were almost equally effective in inhibiting COMT activity in duodenum and liver. Tolcapone decreased striatal extracellular levels of homovanillic acid (HVA), thus confirming its central COMT inhibitory effect, whereas entacapone did not alter HVA efflux. Following L-DOPA/benserazide administration (50/15 mg/kg p.o.), both COMT inhibitors significantly increased striatal levels of L-DOPA and DA compared with saline. The levels of L-DOPA were similar after treatment with either COMT inhibitors, whereas the increase in DA output was significantly greater in rats given tolcapone compared to those given entacapone. We conclude that the blockade of central DA catabolism by tolcapone contributes to the greater increase in striatal DA levels achieved with this drug.

The validity and reliability of the Italian Olfactory Identification Test (IOIT) in healthy subjects and in Parkinson's disease patients.

BACKGROUND Olfactory function can be rapidly evaluated by means of standardized olfactory tests. Multiple-choice smell identification tests can be conditioned by cultural background. To investigate a new tool for detecting olfactory deficit in Italian subjects we developed a multiple-choice identification test prepared with odorants belonging to the Italian culture. METHODS The Italian Olfactory Identification Test (IOIT) was developed with 33 microencapsulated odorants with intensity of odors and headspace Gas Chromatography being tested. Test-retest reliability of the IOIT was evaluated. The IOIT was administered to 511 controls and 133 Parkinsons patients. RESULTS In healthy subjects the number of IOIT errors increased with age for both females (p < 0.0001) and males (p < 0.0001), while in the Parkinsons disease group the number of IOIT errors was significantly greater where compared to healthy subjects (p < 0.0001 in all age groups). The reference limits applied to all age groups revealed an IOIT sensitivity of 93% and a specificity of 99%. The test-retest reliability was excellent. CONCLUSION The IOIT is highly reliable, disposable, easy to administer, not fragile, and has a long shelf-life. All these features make the IOIT suitable for clinical use as well as for population screening and to discriminate Parkinsons patients from healthy subjects.

Different Effects of Levodopa and Apomorphine on Blink Reflex Recovery Cycle in Essential Blepharospasm

With the aim of assessing dopaminergic responsiveness in essential blepharospasm, we investigated the effects of oral levodopa and subcutaneous apomorphine on blink reflex recovery cycle in 7 blepharospasm patients. We found that in blepharospasm the excitability of the blink reflex recovery cycle was increased compared with control subjects. The oral administration of levodopa/carbidopa (500/50 mg) did not significantly modify the blink reflex recovery cycle. The 50 micrograms/kg dose of apomorphine decreased the amplitude of conditioned responses at 300 and 500 ms, whereas the 10 micrograms/kg dose was ineffective. We conclude that the excitability of the blink reflex recovery cycle in blepharospasm is partly under dopaminergic control. The partial normalization of the blink reflex recovery cycle excitability observed with 50 micrograms/kg apomorphine is consistent with the reported clinical efficacy of the drug in this condition.

Possible Involvement of Dopaminergic Mechanisms in the Antimigraine Action of Flunarizine

Flunarizine, a calcium antagonist widely used in the prophylactic treatment of migraine, may interfere with dopaminergic systems. Flunarizine therapy can in fact induce extrapyramidal side effects and can increase basal as well as stimulated prolactin levels. To better define the mechanism of flunarizine action in migraine, we studied prolactin and growth hormone responses to thyrotropin releasing hormone and sulpiride in 13 female migraineurs before and after 60 days of flunarizine therapy. The treatment did not modify basal prolactin and growth hormone levels, but prolactin response to thyrotropin releasing hormone was enhanced. A paradoxical increase of growth hormone to thyrotropin releasing hormone observed before therapy was blunted after flunarizine treatment. These data indicate a modulatory action of flunarizine on dopaminergic systems which might to some extent explain the antimigraine action of this drug.

Effect of naloxone on body temperature in postmenopausal women with Parkinson's disease

The role exerted by the endogenous opioid system on thermoregulation has been studied in six postmenopausal women affected by Parkinsons disease and in 6 age-matched, normal postmenopausal women, as controls. The women randomly received an infusion of the opioid antagonist naloxone (1.6 mg/h for 4 h) or of saline on two consecutive days. Body temperature, as evaluated by rectal temperature, was significantly lower (p less than 0.05) in Parkinsonian than in normal women, and it did not vary during saline infusion, in either groups. Naloxone infusion significantly reduced (p less than 0.01) body temperature in normal postmenopausal women, but it was unable to modify body temperature in women affected by Parkinsons disease. The low basal body temperature values and the inability of naloxone to exert a hypothermic effect in women suffering from Parkinsons disease seem to constitute further evidence for an impaired regulation of body temperature and impaired activity of the endogenous opioid system in this pathology.

Reduced luteinizing hormone secretion in women with Parkinson's disease.

SummaryPlasma luteinizing hormone (LH) levels were significantly lower in 10 postmenopausal women with Parkinsons disease (PD) compared to agematched controls. The remaining hypophyseal hormones and gonadal steroids were similar in PD patients and in controls, suggesting a selective alteration of hypothalamic dopaminergic mechanisms which regulate LH secretion.

Altered Neuroendocrine Regulation of Luteinizing Hormone Secretion in Postmenopausal Women with Parkinson’s Disease

The secretion of gonadotropins and the role exerted by the endogenous opioid system on luteinizing hormone (LH) secretion were investigated in 6 postmenopausal women affected by idiopathic Parkinsons disease (PD) as well as in 6 age- and weight-matched normal postmenopausal women as controls. The mean plasma follicle-stimulating hormone (FSH) and LH levels were evaluated both under basal conditions and after 20 days of conjugated estrogen administration (1.25 mg/day). At the same time, the activity of the endogenous opioid system was evaluated, as well as the LH response to the 4-hour infusion of the opioid antagonist naloxone (1.6 mg i.v. bolus followed by 1.6 mg/h). Both before and during estrogen administration, plasma FSH levels were similar in the two groups of subjects, whereas plasma LH levels were significantly lower (p less than 0.01) in parkinsonian than in control women. In each subject estrogen administration significantly blunted (p less than 0.01) plasma FSH levels. Plasma LH levels were reduced only in controls (p less than 0.05), but not in women with PD. In each subject, before estrogen administration, the plasma LH levels did not vary during naloxone infusion. In control women after 20 days of estrogen administration, the plasma LH levels significantly increased during naloxone infusion (p less than 0.01). By contrast, in women with PD, conjugated estrogens failed to restore the LH response to naloxone. The present results suggest that the neurotransmitter mechanisms, which regulate LH secretion, are altered, and, in particular, the activity of the endogenous opioid system is deficient in women with PD.

Motor response to apomorphine in patients with Parkinson's disease with long-duration response to levodopa.

The authors studied the motor response to apomorphine before and 1 year after levodopa therapy in 12 patients with Parkinsons disease. At the 1-year evaluation, the basal tapping score, recorded after a 12-hour levodopa withdrawal, was higher compared with the test performed while patients were de novo, indicating the presence of a long-duration response to levodopa. The amplitude (net increase) of the motor response to apomorphine was similar before and during levodopa therapy. However, because of the better baseline, the maximal tapping score was higher during levodopa therapy. The duration and the latency of the motor response to apomorphine did not change. The presence of a short-duration response to apomorphine, in the presence of a long-duration response to levodopa, may imply that either different compartment (i.e., postsynaptic versus presynaptic) or transduction pathways are involved in such responses.

Abstracts Third congress of the european society for clinical neuropharmacology: Rome, October 28?30, 1996

Third Congress of the European Society for Clinical Neuropharmacology Rome, October 28-30, 1996 U. Bonuecelli, R. Ceravolo, A. Napolitano, and N. Pavese (eds.) Department of Neurosciences, University of Pisa, Italy