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Biomedical subjects

P Montagna

Publications and source records attributed to P Montagna.

At least 37 records · Page 2Linked to original sources
PubMed2005

New source of dense, cryogenic positron plasmas.

We have developed a new method, based on the ballistic transfer of preaccumulated plasmas, to obtain large and dense positron plasmas in a cryogenic environment. The method involves transferring plasmas emanating from a region with a low magnetic field (0.14 T) and relatively high pressure (10(-9) mbar) into a 15 K Penning-Malmberg trap immersed in a 3 T magnetic field with a base pressure better than 10(-13) mbar. The achieved positron accumulation rate in the high field cryogenic trap is more than one and a half orders of magnitude higher than the previous most efficient UHV compatible scheme. Subsequent stacking resulted in a plasma containing more than 1.2 x 10(9) positrons, which is a factor 4 higher than previously reported. Using a rotating wall electric field, plasmas containing about 20 x 10(6) positrons were compressed to a density of 2.6 x 10(10) cm(-3). This is a factor of 6 improvement over earlier measurements.

Journal Article↗
PubMed2005

Spatial distribution of cold antihydrogen formation.

Antihydrogen is formed when antiprotons are mixed with cold positrons in a nested Penning trap. We present experimental evidence, obtained using our antihydrogen annihilation detector, that the spatial distribution of the emerging antihydrogen atoms is independent of the positron temperature and axially enhanced. This indicates that antihydrogen is formed before the antiprotons are in thermal equilibrium with the positron plasma. This result has important implications for the trapping and spectroscopy of antihydrogen.

Journal Article↗
PubMed2005

Paroxysmal arousal in epilepsy associated with cingulate hyperperfusion.

A patient with nocturnal frontal lobe epilepsy characterized by paroxysmal motor attacks during sleep had brief paroxysmal arousals (PAs), complex episodes of nocturnal paroxysmal dystonia, and epileptic nocturnal wandering since childhood. Ictal SPECT during an episode of PA demonstrated increased blood flow in the right anterior cingulate gyrus and cerebellar cortex with hypoperfusion in the right temporal and frontal associative cortices.

Adult↗
PubMed2005

Pharmacogenetics of headache treatment.

Headaches and migraines are widely prevalent diseases causing relevant disability and worsened quality of life. Several pharmacological options are available for headache therapy, mostly however without firm rationales and all having high rates of non-responders and often serious side effects. Variability of therapeutic effect and adverse events depend at least in part upon genetic variability, but the genetic factors involved are mostly unknown. Pharmacogenetics, i. e., the application of the knowledge of genomic diversity to the analysis of the phenotypic traits involved in therapeutic response and adverse events, is still in its infancy, but represents a promising approach to therapy in migraine. The extant evidence is summarised here, with special attention to pain therapy and the pharmacogenetics of the serotonergic and the dopaminergic systems.

Dopamine↗
PubMed2005

Sleepwalking and other ambulatory behaviours during sleep.

Different pathological conditions may lead to somnambulic automatisms arising from nocturnal sleep. Video polysomnography represents the diagnostic tool but, due to the difficulty of capturing complex episodes in the sleep laboratory, audio-video recordings at home of the episodes may help in the differential diagnosis also. Sleepwalking is a disorder of arousal in which the subject arises from deep sleep, even displaying long complex behaviour, including leaving the bed and walking, with memory impairment of the event. Disordered arousal mechanisms with an inability of the brain to fully awaken from slow-wave sleep are thought to lead to these motor automatisms. REM sleep behaviour disorders begin during REM sleep and are accompanied by features of REM sleep. The motor behaviour may be violent and injurious to the patient and/or bed partner. In some patients, however, the behaviour may be similar to that observed in sleepwalking and some patients have an overlap syndrome. In nocturnal frontal lobe epilepsy in particular, and in complex partial seizures in general, stereotypic and repetitive motor attacks may recur, at any time, on the same night and on different nights, with a continuum between minimal or minor attacks and major or prolonged episodes up to agitated epileptic nocturnal wanderings.

Brain↗
PubMed2005

A pilot double-blind placebo-controlled trial of low-dose pramipexole in sleep-related eating disorder.

Sleep-related eating disorder (SRED) is characterized by recurrent arousals from sleep associated with compulsive ingestion of food. No controlled therapeutic trials are available for SRED. We assessed the safety, tolerability and efficacy of pramipexole, a dopamine D3-receptor agonist, in the treatment of SRED. Eleven consecutive patients with SRED in the absence of concurrent daytime eating disorders underwent actigraphic recording and subjective sleep diary evaluation for a week before and every week for 2 weeks of treatment with pramipexole 0.18-0.36 mg or placebo, administered in a double-blind crossover randomized sequence. The primary outcomes of the trial were actigraphic measures of night sleep parameters (sleep efficiency, motor activity mean and median, number and duration of wake episodes), secondary outcomes were the number of good sleep nights/weekly, number and duration of nocturnal awakenings/night, and visual analogue preference score. Pramipexole was well tolerated without any patient withdrawing from the study. Pramipexole reduced night-time activity median (P = 0.02) and increased the number of nights of good sleep/week (P = 0.02). All other measurements remained unaffected. Pramipexole at low doses was well tolerated, improving some measures of sleep quality and reducing median night activity in SRED. Further studies with higher dosages and for longer time-periods are warranted.

Adult↗
PubMed2005

Circadian melatonin and cortisol levels in rheumatoid arthritis patients in winter time: a north and south Europe comparison.

BACKGROUND: Altered functioning of the hypothalamic-pituitary-adrenal axis and altered melatonin production might modulate the circadian symptoms in patients with rheumatoid arthritis. OBJECTIVE: To investigate the influence of different winter photoperiods on the circadian rhythms of serum melatonin, cortisol, tumour necrosis factor alpha (TNFalpha), and interleukin 6 (IL6) in patients with rheumatoid arthritis from a north Europe country (Estonia) and a south Europe country (Italy). METHODS: The patients from Estonia (n = 19) and Italy (n = 7) had similar disease severity and duration and were compared with healthy age and sex matched controls in the two countries. Blood samples were collected during the period January to February at 8 pm, 10 pm, midnight, 2 am, 4 am, 6 am, 8 am, and 3 pm. Melatonin was measured by radioimmunoassay using (125)I-melatonin. Serum cortisol, TNFalpha, and IL6 cytokines were assayed by standard methods. RESULTS: Higher circadian melatonin concentrations from 10 pm and an earlier peak were observed in Estonian patients than in their age and sex matched controls (p<0.01). Starting from midnight, melatonin concentrations were significantly higher in the Estonian patients than in the Italian patients. No significant differences were observed for serum cortisol. Serum TNFalpha was higher (p<0.05) in Estonian patients than in their controls and was correlated with the melatonin levels. CONCLUSIONS: In a north European country (Estonia), the circadian rhythm of serum concentrations of melatonin and TNFalpha in patients with rheumatoid arthritis were significantly higher than in matched controls or in rheumatoid patients from a south Europe country (Italy).

Adult↗
PubMed2005

Generalised anhidrosis: different lesion sites demonstrated by microneurography and skin biopsy.

Generalised anhidrosis (GA) shows a uniform clinical picture whether the pathogenesis involves intrinsic abnormalities of sweat glands or postganglionic sympathetic cholinergic nerve dysfunction. We describe two patients who presented intolerance to heat and anhidrosis. In the first patient, symptoms started at 33 years of age, and were associated with absent tendon reflexes and a mydriatic right pupil unreactive to light. The other patient had been unable to sweat since birth. GA was diagnosed on the basis of clinical findings and thermoregulatory tests. Microneurography and morphological analysis of the skin and its innervation disclosed a different lesion site underlying GA in the two patients, and distinguished between a postganglionic autonomic nerve fibre lesion and sweat gland dysfunction.

Adult↗
PubMed2004

In vivo evidence of neuronal loss in the hypothalamus of narcoleptic patients.

A dysfunction of the orexin (hypocretin) system in the hypothalamus has recently been linked to the pathogenesis of narcolepsy. The authors used in vivo proton MR spectroscopy to assess the N-acetylaspartate (NAA) content in the hypothalamus of narcoleptic patients. Hypothalamic NAA/creatine-phosphocreatine was reduced in narcoleptic patients compared with control subjects (p < 0.01). Hypothalamic neuronal loss/damage is a central pathogenetic feature in narcolepsy.

Adolescent↗
PubMed2004

Variability of familial hemiplegic migraine with novel A1A2 Na+/K+-ATPase variants.

A1A2 Na+/K+-ATPase mutations cause familial hemiplegic migraine type 2 (FHM2). The authors identified three putative A1A2 mutations (D718N, R763H, P979L) and three that await validation (P796R, E902K, X1021R). Ten to 20% of FHM cases may be FHM2. A1A2 mutations have a penetrance of about 87%. D718N causes frequent, long-lasting HM, and P979L may cause recurrent coma. D718N and P979L may predispose to seizures and mental retardation. A1A2 does not play a major role in sporadic HM; only one variant, R383H, occurred in 1 of 24 cases.

Adolescent↗
PubMed2004

Three-dimensional annihilation imaging of trapped antiprotons.

We demonstrate three-dimensional imaging of antiprotons in a Penning trap, by reconstructing annihilation vertices from the trajectories of the charged annihilation products. The unique capability of antiparticle imaging has allowed, for the first time, the observation of the spatial distribution of the particle loss in a Penning trap. The radial loss of antiprotons on the trap wall is localized to small spots, strongly breaking the azimuthal symmetry expected for an ideal trap. Our observations have important implications for detection of antihydrogen annihilations.

Journal Article↗
PubMed2004

POLG mutations causing ophthalmoplegia, sensorimotor polyneuropathy, ataxia, and deafness.

The authors identified two novel heterozygous missense transitions in the gene for the mitochondrial polymerase gammaA subunit (POLG) in a family with an autosomal recessive syndrome comprising progressive external ophthalmoplegia (PEO), polyneuropathy, ataxia, sensorineural hearing loss, and affective disorders. These mutations were not detected in 120 healthy control subjects.

Adult↗
PubMed2004

The physiopathology of migraine: the contribution of genetics.

Recent advances in the studies of the genetic liability to migraine include the discovery of two genes responsible for familial hemiplegic migraine (FHM) and the analysis of several sites of linkage or genetic association for the so-called typical migraines, e. g., migraine with (MA) and without aura (MO). The 2 genes implicated in the genetics of FHM are CACNA1A for FHM1 and ATP1A2 for FHM2. It is still unclear how dysfunction in these genes may trigger attacks of migraine with hemiplegic features and, in at least part of the families with FHM, also paroxysmal or progressive ataxia and epileptic seizures. It appears that mutations in CACNA1A responsible for FHM1 alter calcium influx and calcium currents in neurons, possible factors of spreading depression like events. On the other hand, abnormal regulation of intracellular calcium concentrations could alter neurotransmitter release and other cellular functions. In the case of ATP1A2 mutations, haplo-insufficiency of the gene has been hypothesised to result in abnormal potassium level regulation because of faulty Na/K exchange with subsequent depolarisation and increased liability to spreading depression, or/and in abnormal calcium levels because of the concomitant activation of the Na/Ca exchanger, with a mechanism therefore comparable to that at work in FHM1. Much more work is clearly necessary to elucidate these pathophysiological mechanisms; advances in genetics however may represent important steps in the clarification of the physiopathology of the migraine attack.

Humans↗
PubMed2004

The role of cardiac diseases in the comorbidity between migraine and stroke.

Several case-control and cohort studies have suggested an association between migraine and stroke. A significantly higher risk for stroke was found in women under the age of 45 years and for the subgroup with migraine with aura, the posterior circulation being significantly more frequently involved. The link between cardiac diseases and the comorbidity migraine-stroke has been evaluated considering both possible relationships: a higher prevalence of a vascular disease involving both heart and brain in migraineurs, or a cardiac disorder, more prevalent in migraineurs, with a possible aetiological role in migraine attacks.

Aortic Aneurysm↗
PubMed2004

Analytical and diagnostic accuracy of "second generation" assays for thyrotrophin receptor antibodies with radioactive and chemiluminescent tracers.

AIMS: To investigate the analytical and diagnostic accuracy of thyrotrophin (TSH) receptor antibody assays using recombinant human TSH receptors. METHODS: Sera from 68 patients with Graves' disease, 23 patients with autoimmune thyroiditis, and 119 healthy controls were evaluated in four different laboratories using both radioactive and chemiluminescent tracers. Functional sensitivity, interlaboratory precision, optimal cutoff values for Graves' disease, and the correlation between the two methods were evaluated. RESULTS: Functional sensitivity was 0.98 IU/litre for both assays. Interlaboratory precision, expressed as per cent coefficient of variation over a wide range of antibody concentrations, varied from 5.7% to 15.1% for the radioligand, and from 6.6% to 19.9% for the chemiluminescence assay. The two methods (radioactive and chemiluminescent) were closely correlated. All the sera from untreated or relapsing patients with Graves' disease gave TSH receptor antibody values above 2.1 IU/litre, whereas in none of the healthy controls did values exceed 2.5 IU/litre. Receiver operating curve analysis allowed an optimal cutoff point to be defined at 1.99 IU/litre, according to a sensitivity of 100% and specificity of 99.1%. CONCLUSIONS: These data show the high analytical and diagnostic accuracy of the human TSH receptor assays, both with radioactive and chemiluminescent tracers, when both functional sensitivity and interlaboratory reproducibility are considered. These two methods could be proposed as first line diagnostic markers for Graves' disease.

Adult↗
PubMed2004

Sex hormones influence on the immune system: basic and clinical aspects in autoimmunity.

Sex hormones seem to play an important role as modulators of the autoimmune disease onset/perpetuation. Generally, steroid hormones are implicated in the immune response, with estrogens as enhancers at least of the humoral immunity and androgens and progesterone (and glucocorticoids) as natural immunosuppressors. Synovial fluid levels (SF) of proinflammatory estrogens relative to androgens are significantly elevated in both male and female rheumatoid arthritis (RA) patients, as compared to controls, which is most probably due to increase of local enzymatic aromatase activity. Serum levels of estrogens have been found altered in RA patients, particularly estradiol in man. Thus, available steroid prehormones are rapidly converted to proinflammatory estrogens in the synovial tissue in the presence of inflammatory cytokines (i.e., TNFalpha, IL-1, IL-6). The increased estrogen concentrations observed in RA SF of both sexes are characterized mainly by the hydroxylated forms, in particular, 16alpha-hydroxyestrone, showing a mitogenic tumor growth stimulating role. Altered serum hydroxylated estrogens have been found also in serum of systemic lupus erythematosus (SLE) patients. As a matter of fact, our recent studies indicate that 17-beta estradiol (E2) clearly enhanced the expression of markers of cell growth and proliferation, whereas testosterone (T) induced an increase of markers indicating DNA damage and apoptosis. In particular, our data further shows that the enhancing role of estrogens on immune/inflammatory response is exerted by activating the NFkB complex pathway. In conclusion, locally increased estrogens (i.e., synovial tissue in RA or skin in SLE) might exert activating effects on cell proliferation, including macrophages and fibroblasts, suggesting new roles for estrogens in autoimmunity.

Androgens↗
PubMed2004

Ropinirole in the treatment of restless legs syndrome: results from the TREAT RLS 1 study, a 12 week, randomised, placebo controlled study in 10 European countries.

OBJECTIVE: To assess the efficacy, safety, and tolerability of ropinirole in the treatment of patients with restless legs syndrome. METHODS: A 12 week, prospective, double blind, randomised comparison involving 284 patients from 10 European countries. All participants had a score of > or =15 on the international restless legs scale (IRLS). Patients were randomised (1:1) to receive either ropinirole 0.25-4.0 mg once daily or placebo. The primary efficacy end point was mean change from baseline to week 12 in total IRLS score. Global improvements (clinical global impression (CGI) scale) and improvements in sleep, health related quality of life (QoL; using generic and disease specific measures), work, and other activities were also assessed. RESULTS: 112/146 patients (76.7%) taking ropinirole and 109/138 (79.0%) taking placebo completed the study. Improvement in IRLS at week 12 with ropinirole (mean (SD) dose, 1.90 (1.13) mg/day) was greater than with placebo (mean (SE): -11.04 (0.719) v -8.03 (0.738) points; adjusted difference = -3.01 (95% confidence interval (CI), -5.03 to -0.99); p = 0.0036). More patients in the ropinirole group (53.4%) showed improvement on the CGI scale at week 12 than in the placebo group (40.9%; adjusted odds ratio = 1.7 (1.02 to 2.69); p = 0.0416). Significant differences on both IRLS and CGI scales favouring ropinirole were apparent by week 1. Ropinirole was also associated with significantly greater improvements in sleep and QoL end points. The most common adverse events were nausea and headache. CONCLUSIONS: Ropinirole improves restless legs syndrome compared with placebo, with benefits apparent by week 1. It is generally well tolerated.

Adult↗