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S Serra

Publications and source records attributed to S Serra.

At least 19 recordsLinked to original sources
PubMed2001

Surface states and negative electron affinity in polyethylene.

First-principles calculations are used to investigate the electronic properties of the surfaces of polyethylene. The calculations support the experimental evidence of a negative electron affinity, with calculated values of -0.17 eV and -0.10 eV for surfaces with chains perpendicular and parallel to the surface normal, respectively. Both surfaces exhibit a surface state with binding energy -1.2 +/- 0.5 eV with respect to the bulk polyethylene conduction band minimum. Implications of these findings on spectroscopy, as well as on the transport and aging properties of polyethylene for high-voltage applications, are discussed.

Journal Article↗
PubMed2001

Selective breeding of two rat lines differing in sensitivity to GHB and baclofen.

Two Wistar-derived rat lines, one sensitive (GHB-S) and the other resistant (GHB-R) to the anesthetic effect of gamma-hydroxybutyric acid (GHB), have been selectively bred. GHB-S and GHB-R rats were also sensitive and resistant, respectively, to the anesthetic effect of baclofen, the prototype GABA(B) receptor agonist, suggesting that they may be useful to elucidate not only the role of endogenous GHB but also that of GABA(B) receptors in sleep and anesthesia.

Anesthesia Recovery Period↗
PubMed2001

delta(13)C- and delta(18)O-values of glycerol of food fats.

The average values of carbon and oxygen isotopic contents (delta(13)C and delta(18)O) of 36 glycerol samples from fats have been determined. The examined samples arise from many fats of animal and plant origin, as well as from the three Italian hard cheeses Parmigiano-Reggiano, Grana Padano and Trentingrana. The total (13)C content allows one to distinguish between glycerol from plants with the C-4 carbon fixation pathway (maize, mean delta(13)C = -14.4 per thousand) and that from plants with the C-3 pathway (mean delta(13)C = -30.7 per thousand). The delta(13)C-values of glycerols of animal origin seem to depend on the diet of the animal, as suggested by the mean values -29.6, -29.0 and -25.1 per thousand, respectively, observed for Parmigiano-Reggiano, Trentingrana and Grana Padano. Additionally, the mean total (18)O content of glycerol samples of vegetable origin is approximately 23.8 per thousand, while that from animal fat is 15.1 per thousand. However, the delta(18)O mean values relative to Parmigiano-Reggiano, Grana Padano and Trentingrana are 11.8, 16.0 and 13.8 per thousand, respectively. The combination of the (13)C and (18)O measurements relative to the fat glycerol of the three cheeses might be considered a potential criterion of authentication.

Animals↗
PubMed2001

Procedure of bidirectional selective outbreeding for production of two rat lines differing in sensitivity to the sedative/hypnotic effect of gamma-hydroxybutyric acid.

The exogenous administration of gamma-hydroxybutyric acid (GHB), a constituent of the mammalian brain where it likely functions as a neurotransmitter or a neuromodulator, exerts a number of pharmacological effects, including sedation and hypnosis. The present paper describes a procedure for selective breeding of two rat lines which markedly differ in sensitivity to the sedative/hypnotic effect of GHB. Selective breeding originated from Wistar rats showing opposite sensitivity to the sedative/hypnotic effect of 1 g/kg GHB (i.p.). 'Sensitive' Wistar rats, defined as those individuals displaying values of r = sleep time/onset greater than the upper 15th percentile, were mated to generate the GHB-sensitive (GHB-S) line; conversely, 'resistant' Wistar rats (r-values lower than the lower 15th percentile) were mated to generate the GHB-resistant (GHB-R) line. Upper and lower 15th percentiles were also used to establish the selection cut-offs and criteria for rats of subsequent generations. Specifically, r-values of GHB-S rats were required to be r > or =8 on two separate tests with GHB; r-values of GHB-R rats were required to be r < or =2 on two separate tests with GHB. In each of the three generations produced to date, GHB-S rats showed significantly shorter onset, longer sleep times and greater r-scores than GHB-R rats. The selective breeding of GHB-S and GHB-R rats: (a) suggests that sensitivity to GHB is under genetic control, and (b) may constitute a unique model for investigation of the physiological function of GHB.

Animal Husbandry↗
PubMed1999

Pressure-induced solid carbonates from molecular CO2 by computer simulation

A combination of ab initio molecular dynamic simulations and fully relaxed total energy calculations is used to predict that molecular CO2 should transform to nonmolecular carbonate phases based on CO4 tetrahedra at pressures in the range of 35 to 60 gigapascals. The simulation suggests a variety of competing phases, with a more facile transformation of the molecular phase at high temperatures. Thermodynamically, the most stable carbonate phase at high pressure is predicted to be isostructural to SiO2 alpha-quartz (low quartz). A class of carbonates, involving special arrangements of CO4 tetrahedra, is found to be more stable than all the other silica-like polymorphs.

Journal Article↗
PubMed1999

Stable isotope characterization of raspberry ketone extracted from Taxus baccata and obtained by oxidation of the accompanying alcohol (Betuligenol).

The natural abundance (2)H NMR characterization of raspberry ketone 1 extracted from himalayan Taxus baccata and of the accompanying (R) carbinol 2 is performed and compared with that of samples of 1 obtained from 2 by oxidation with Candida boidinii and CrO(3), respectively. The determination of the delta((13)C) and/or delta((18)O) values of the above extractive products and of benzoic acid (6) and 4-butylphenol (10), obtained from natural of synthetic 1, and of 4-phenylbutan-2-ol (8), prepared from extractive 2, allows a description of the labeling pattern of this set of products. A graph of (D/H)(3)/(D/H)(2) vs (D/H)(5)/(D/H)(4) (Figure 3) of the presently examined samples and of those previously characterized in the laboratory, including three commercial samples sold as natural, defines three areas, containing (a) the material of botanical origin and that produced from extractive 2 by biooxidation, (b) those produced by bioreduction of the unsaturated ketone 3, and (c) the synthetic samples.

Butanones↗
PubMed1997

[Stress test in the elderly. Clinical, hemodynamic, metabolic and electrocardiographic variables].

PURPOSE: To identify in the elderly adaptations imposed by exercise in both sexes. METHODS: 1528 stress tests were performed on subjects divided in: group I (GI) (90%) between 65 to 75 years old, and group II (GII) more than 75 years old. Protocols applied were Bruce (72%), and modified Naughton (28%). Clinical, hemodynamic and electrocardiographic variables were estimated as recommended by the World Health Organization, and the metabolic variables in the adapted Naughton protocols by the American College of Sports Medicine standards. RESULTS: Analysis of GI and GII, respectively disclosed: 1) stress electrocardiogram (ECG): normal, 36 and 35%; ST depression, 20 and 22%; ST elevation, 6 and 1%; ventricular ectopic beats, 11 and 14%; supra ventricular ectopic beats, 5 and 6%; 2) metabolic and hemodynamic variables: the double-product: 26636 (+/-1539) and 23133 (+/-3218) mmHg X bpm (p < 0.0001). Maximum oxygen uptake measured in METS: GI, men, 7.7 (+/-1.9), women 5.4 (+/-0.8) (p < 0.0001); GII, NS, curve of systolic blood pressure: GI, men, 8.4 +/- (0.5), women, 10.6 (+/-1.8) mmHg/Met (p = 0.03); GII- NS. Difference of diastolic blood pressure and heart rate during exercise were similar between the two groups; 3) chest pain was the main clinical variable. CONCLUSION: The more frequent indication for stress testing to evaluate chest pain in GI, did not correspond to a predominance of this symptom in this group, during exercise; in GI, in contrast to what is seen in the young, the curve of systolic blood pressure was greater in women; despite the greater prevalence of coronary artery disease in aged subjects, it was not observed significative differences between the two groups, to ischaemic ST depression.

Aged↗
PubMed1997

[Ergospirometry].

Explore the source record for details and available documents.

Ergometry↗
PubMed1995

Sleep features in Tourette's syndrome, neuroacanthocytosis and Huntington's chorea.

Twenty-one patients affected by extrapyramidal disorders were polygraphically recorded during spontaneous nocturnal sleep for two consecutive nights to assess their sleep and movement patterns. The patients (pts) sample included: Gilles de La Tourette syndrome (TS, nine pts), neuroacanthocytosis (NA, six pts) and Hungtington's chorea (HC, six pts). Sleep recording included C3/A2, 01/A2, ROC/LOC, submental EMG, EKG, nasal airflow thoracoabdominal respirogram, bilateral anterior tibialis and other EMGs, in relation to the individual distribution of the abnormal movements. According to our observations, abnormal movements always decreased but never ceased completely during sleep. Sleep efficiency (SE) was nearly always poor with a high percentage of wakefulness after sleep onset (WASO) and increased number of arousals. REM sleep was often reduced and in some cases (3 TS pts) incompletely defined as far as its microstructural aspects. Slow wave sleep (SWS) was reduced in HC, normal in NA, and increased in all TS patients with the exception of the two adult subjects more severely affected, while the percentage of stage 2 was not affected. Spindling was increased in NA, HC and in the two most severely affected adult TS patients.

Acanthocytes↗
PubMed1993

Amyotrophic choreo-acanthocytosis: a neuropathological and immunocytochemical study.

A 47 year old man, one of a sibship affected by amyotrophic choreo-acanthocytosis was studied neuropathologically after some years of clinical observation. Besides the classic optical findings (neuronal loss, astrocytic gliosis and "status spongiosus" in the basal ganglia, namely in the caudate nucleus) a few MEnk+ and NPY+ neurons were observed immunocytochemically in the striatum. In the spinal cord also, while no neuronal loss was perceivable, both mild demyelination and interfibrillary astrocytic hyperplasia of the long tracts were present. On the other hand, microscopic findings of muscle and peripheral nerve showed no differences from what was previously intra-vitam appreciated in the same patient. The neuropathological and immunocytochemical findings of this case are discussed in relation to the differential diagnosis between amyotrophic choreo-acanthocytosis and Huntington's disease.

Atrophy↗
PubMed1990

[A rare complication in total gastrectomies].

The authors describe a rare complication following total gastrectomy or reconstruction using a Roux-en-Y loop: the presence of a metal mandrel used to insert the nasogastric tube in the end tract was discovered during esophagojejunal anastomosis. The object was extracted by esophagoscopy without damage to the patient.

Aged↗
PubMed1990

The effect of nocturnal physiological sleep on various movement disorders.

Thirty-one subjects affected by different movement disorders underwent polygraphic and videotape monitoring during nocturnal sleep, to assess movement patterns during the night. It was possible to distinguish two categories of disorders according to their pattern of movements. In the largest group (Meige's syndrome, blepharospasm, amyotrophic choreoacanthocytosis, Tourette syndrome, tonic foot, hemiballism) abnormal movements were still present during sleep, but decreased in frequency and amplitude in all stages. The second group presented three syndromes (nocturnal paroxysmal dystonia, nocturnal myoclonus, restless legs syndrome), in which light non-rapid-eye-movement sleep induced a strong activation of abnormal movements, whereas rapid-eye-movement sleep suppressed them.

Adult↗
PubMed1989

Peripheral neuropathy in amyotrophic chorea-acanthocytosis.

We investigated involvement of the peripheral nervous system in 6 patients with amyotrophic chorea-acanthocytosis. Electromyographic and neurographic findings, and pathological changes as demonstrated by examination of biopsy specimens of muscle and sural nerve indicate that most patients had an axonal sensorimotor polyneuropathy with more pronounced involvement of the distal portion of the nerves. Results obtained in one patient raised the question of an anterior horn cell disorder.

Acanthocytes↗
PubMed1988

Tuberculous meningitis: a retrospective survey of 22 cases.

Clinical and biological findings likely to constitute prognostic factors were analyzed in a retrospective survey of 22 cases of tuberculous meningitis. In particular, associations between clinical and biological findings (clinical grade on admission, normal and abnormal CSF protein and glucose values) and outcome of illness were sought. On admission 16 patients had altered consciousness, 11 hemiparesis and 7 sixth cranial nerve paresis. Meningeal signs were present in all subjects. 7 had a positive culture for Mycobacterium tuberculosis. 9 patients recovered completely, 7 had serious late sequelae, 6 died. Prognosis appeared to be correlated to neurological status at admission.

Adolescent↗