Showing papers by "University of Naples Federico II published in 1988"
01 Aug 1988
TL;DR: Based on a recently proposed algorithmic solution technique, the inverse kinematic problem for redundant manipulators is solved and the kinematics of the manipulator is appropriately augmented to include mentioned constraints; the result is an efficient, fast, closed-loop algorithm.
Abstract: Based on a recently proposed algorithmic solution technique, the inverse kinematic problem for redundant manipulators is solved. The kinematics of the manipulator is appropriately augmented to include mentioned constraints; the result is an efficient, fast, closed-loop algorithm which only makes use of the direct kinematics of the manipulator. Simulation results illustrate the tracking performance for a given trajectory in the Cartesian space, while guaranteeing a collision-free trajectory and/or not violating a mechanical joint limit. >
369 citations
356 citations
259 citations
TL;DR: In this paper, a patient who had made a partial recovery from herpes simplex encephalitis was observed to have similar characteristics both with verbal and pictorial material, and a significant degree of consistency was observed between repeated presentations and across various modalities of administration of the same stimuli.
Abstract: A category-specific semantic disorder, selectively affecting Living things and food and sparing inanimate objects, was observed in a patient (LA) who had made a partial recovery from herpes simplex encephalitis. This impairment was observed to have similar characteristics both with verbal and pictorial material, and a significant degree of consistency was observed between repeated presentations and across various modalities of administration of the same stimuli. In order to study the possible role of interactions between verbal-semantic and visual-semantic impairment, we constructed a test of “naming animals by definitions”, in which two sorts of definitions were contrasted: (1) those stressing visual perceptual features; and (2) those using verbal metaphorical expressions, or a description of the function accomplished by that animal for man, to allow identification. LA performed much better in the second than in the first condition. On the grounds of these results, the following hypotheses were ...
257 citations
TL;DR: The hormonal alterations observed in the patients with normal menstrual cycles seem to support the hypothesis that a neurotransmitter dysfunction might be the common pathogenetic mechanism resulting in both REDs and PGE.
Abstract: It is known that women suffering from temporal lobe epilepsy may frequently present reproductive endocrine disorders (REDs). We hypothesized that a high occurrence of REDs could be found also in primary generalized epilepsy (PGE), and therefore investigated the hormonal and ovarian echographic profiles in 20 PGE female patients of reproductive age. Fourteen reported normal menstrual cycles, while 6 complained of longstanding menstrual irregularities. All but three patients were receiving antiepileptic drug (AED) therapy. In all subjects, the basal levels of gonadotropins, prolactin, and gonadal steroids were assayed. The response of luteinizing hormone (LH) to gonadotropin-releasing hormone was also investigated and ovarian ultrasonographic findings were evaluated. In five of six patients with menstrual problems (25% of the group), a well-defined RED was diagnosed (polycystic ovarian disease in three cases and hypothalamic ovarian failure in two). The 14 patients with normal menstrual cycles showed an elevation of mean basal follicle-stimulating hormone and prolactin, and a blunting of mean LH response. Our results suggest that a high occurrence of REDs may be found also in PGE. We hypothesize that a neurotransmitter dysfunction might be the common pathogenetic mechanism resulting in both REDs and PGE. The hormonal alterations observed in the patients with normal menstrual cycles seem to support our hypothesis. Previous data seem to rule out a possible AED effect accounting for the hormonal findings observed in our series. However, further studies are needed to confirm our preliminary results.
160 citations
TL;DR: Biopsy of the ischemic muscle, carried out before and after 15 days of L-carnitine administration in four additional patients, showed that treatment significantly increased total carnitine levels and induced a more rapid recovery of the lactate/pyruvate ratio.
Abstract: A double-blind, cross-over study was designed to evaluate the effects of L-carnitine in patients with peripheral vascular disease. After drug washout, 20 patients were randomly assigned to receive placebo or L-carnitine (2 g bid, orally) for a period of 3 weeks and were then crossed over to the other treatment for an additional 3 weeks. The effect on walking distance at the end of each treatment period was measured by treadmill test. Absolute walking distance rose from 174 +/- 63 m with placebo to 306 +/- 122 m (p less than .01) with carnitine. Biopsy of the ischemic muscle, carried out before and after 15 days of L-carnitine administration in four additional patients, showed that treatment significantly increased total carnitine levels. An additional goal of this study was to ascertain the effects of L-carnitine on the metabolic changes induced by exercise in the affected limb. In six patients under control conditions, arterial and popliteal venous lactate and pyruvate concentrations were determined at rest, when the maximal walking distance was reached, and 5 min after the walking test. Twenty-four hours later, L-carnitine was administered intravenously (3 g as a bolus followed by an infusion of 2 mg/kg/min for 30 min) and metabolic assessments were repeated. Five minutes after the walking test, popliteal venous lactate concentration increased by 107 +/- 16% before treatment and by only 54 +/- 32% (p less than .01) after carnitine. Furthermore, carnitine induced a more rapid recovery to the resting value of the lactate/pyruvate ratio.(ABSTRACT TRUNCATED AT 250 WORDS)
157 citations
TL;DR: The complete nucleotide sequence of the histidine operons of Escherichia coli and Salmonella typhimurium is determined and a comparative analysis of the different transcriptional and translational control elements within the two operons reveals a remarkable preservation.
150 citations
TL;DR: Bottled children had an earlier introduction of gluten to the diet than did controls, but when early gluten introduction was analyzed across strata of breast-fed or bottle-fed children, no risk was attributed to it.
Abstract: This study explored whether risk or protective nutritional factors have a role in childhood celiac disease. The effect of bottle feeding and early introduction of gluten to the diet was evaluated in a case control study. For each case, about 10 controls were recruited: sample size was determined as required for the evaluation of the study hypothesis. Patients were significantly less breast fed than were controls. Bottle-fed children had an earlier introduction of gluten to the diet than did controls, but when early gluten introduction was analyzed across strata of breast-fed or bottle-fed children, no risk was attributed to it. Bottle feeding appeared to be a significant risk factor in children who received gluten early as well as in those who received gluten later. Breast-feeding rates for patients and controls were equal at birth, but lower for patients by the age of 1 month: from then onward, there was a constant difference between patients and controls regarding the percentage still at breast. Interruption of breast feeding was a risk factor in celiac disease, but early gluten introduction did not appear to be a similar risk factor in the present study.
114 citations
TL;DR: In this article, two isoforms of methionine adenosyltransferase (S-adenosylmethionine synthetase), A and B, have been partially purified from Sulfolobus solfataricus, a thermophilic archaebacterium optimally growing at 87°C.
Abstract: Two isoforms of methionine adenosyltransferase (S-adenosylmethionine synthetase), A and B, have been partially purified from Sulfolobus solfataricus, a thermophilic archaebacterium optimally growing at 87°C. The chromatographic procedure, involving hydrophobic chromatography on a phenyl-Sepharose column as a major step. results in 330-fold and 150-fold purification of adenosylmethionine synthetase A and B respectively. The apparent molecular masses, estimated by gel filtration, are 180 kDa for A and 75 kDa for B.
The A and B isoforms follow Michaelis-Menten kinetics with apparent Km values of 10 μM nd 20 μM for L-methionine and of 50 μM and 150 μM for ATP respectively. Adenosylmethionine, a product of the reaction, acts as a powerful non-competitive inhibitor (Ki= 50 μM) of the A isoform while it inhibits only slightly the B isoform. Both isozymes exhibit tripolyphosphatase activity but only that associated with the form A is stimulated by 5 μM adenosylmethionine concentration. The two enzymes absolutely require a divalent cation for the activity, but are not affected by monovalent ions and reducing agents.
The optimum temperature is 90°C and no significant loss of activity is observable after incubation of the two isoforms at 100°C in the presence of ATP. The Arrhenius plots observed for both isozymes are biphasic, indicating different activation energies below and above 75°C.
The cytoplasmic levels of ATP, methionine and adenosylmethionine are evaluated.
100 citations
TL;DR: It is suggested that sclerotherapy was more efficient in preventing first bleeding in patients with decompensated disease than in those in good condition (Child A), however, the 2‐year cumulative bleeding rate of untreated Child A patients was only 19%, showing how in this group the endoscopic findings were unreliable in selecting high‐risk varices and explaining why after a 2-year follow-up prophylactic sclerosis did not show any benefit.
96 citations
TL;DR: In this article, conformational energy computations on a derivative and a homo-dipeptide of Cα,α-diethylglycine were performed and it was found that the residues are conformationally restricted and that the minimum energy conformation corresponds to the fully extended C5 structure when the NCαC′ bond angle is smaller than 108° (as experimentally observed).
Abstract: Conformational energy computations on a derivative and a homo-dipeptide of Cα,α-diethylglycine were performed. In both cases the N- and C-terminal groups are blocked as acetamido and methylamido moieties, respectively. It was found that the Cα,α-diethylglycine residues are conformationally restricted and that the minimum energy conformation corresponds to the fully extended C5 structure when the NCαC′ bond angle is smaller than 108° (as experimentally observed). The results of the theoretical analysis are in agreement with the crystal-state structural propensity of the complete series of N-trifluoroacetylated homo-peptides of this Cα,α-dialkylated residue from monomer to pentamer, determined by x-ray diffraction and also described in this work. Interestingly, for the first time, a crystallographically planar peptide backbone was observed (in the protected tripeptide). A comparison with peptides of Cα,α-dimethylglycine, Cα-methyl, Cα-ethylglycine, and Cα,α-di-n-propylglycine indicates that the fully extended conformation becomes more stable than the helical structures when both amino acid side-chain Cβ atoms are substituted.
TL;DR: In this paper, a series of fine-needle aspiration biopsies (FNAB) of breast masses is described, and the diagnostic accuracy of this series (sensitivity, 95.7%; specificity, 89.6%; predictive value of positivity, 95; and efficiency, 94.0%) is compared with that published in the literature.
Abstract: A series of 1956 fine-needle aspiration biopsies (FNAB) of breast masses is described. The diagnostic accuracy of this series (sensitivity, 95.7%; specificity, 89.6%; predictive value of positivity, 95.9%; and efficiency, 94.0%) was compared with that published in the literature. Statistically significant differences were found between the level of diagnostic accuracy in series published by pathologists who diagnosed smears prepared by clinicians and surgeons (Group A), and those published by pathologists who performed palpation and aspiration, and made the cytologic diagnosis by themselves (Group B). These differences mainly consisted of a lower number of false-positives and "unsatisfactory" samples in Group B series.
TL;DR: An ethanolic extract of the flowers of Calotropis procera was investigated for anti-inflammatory, antipyretic, analgesic and antimicrobial activities and showed some weak effect in rats on the writhing induced by acetic acid.
TL;DR: In this article, the optimal amount of tax evasion for each firm depends not only on the degree of collusion in the market, but also on the relative market shares of the firms.
TL;DR: Supernormal inotropic state could be considered one form of primary adaptation to high wall stress that serves to maintain systolic ventricular performance.
Abstract: Forty-three subjects with uncomplicated primary hypertension and without echocardiographic left ventricular hypertrophy and 54 normotensive volunteers were studied by two-dimensional targeted M-mode echocardiography to evaluate systolic function and contractility before the development of compensatory hypertrophy. The ratio of peak systolic pressure to end-systolic dimension was used to assess left ventricular performance and was divided for either posterior wall thickness or cross-sectional area to generate hypertrophy-independent indices of inotropic state. Fractional shortening was normal in the hypertensive group, despite the increase in end-systolic stress. Systolic pressure/dimension ratio was higher in hypertensive subjects (p less than 0.001), as were hypertrophy-independent indices of inotropic state (p less than 0.005), which were inversely correlated to left ventricular mass (p less than 0.001). Values in 11 hypertensive subjects were above the upper confidence limit of the normal shortening/stress relation, which provides a load-independent measure of inotropic state. They showed high hypertrophy-independent indices of inotropic state (p less than 0.01), while the other hypertensive subjects did not. High fractional shortening, wall stress, and systolic pressure (p less than 0.01) were found in the subgroup with supernormal performance, while left ventricular mass was not different from that of other subgroups, depicting inadequate left ventricular hypertrophy. The duration of hypertension was the same in the subgroups. Supernormal inotropic state could be considered one form of primary adaptation to high wall stress that serves to maintain systolic ventricular performance.
TL;DR: In this article, a simple one-parameter thermal model, predicting the maximum feed rate still resulting in a through cut as a function of beam power, focal spot diameter and thickness of worked material is presented and discussed for CO 2 laser cutting of composites.
Abstract: A simple one-parameter thermal model, predicting the maximum feed rate still resulting in a through cut as a function of beam power, focal spot diameter and thickness of worked material is presented and discussed for CO 2 laser cutting of composites. An extensive experimental program, including glass, carbon and aramide fabric reinforced polyester resin was carried out by varying all the parameters involved in the model. An excellent agreement is shown between experimental data and theoretical predictions. In addition, a criterion for cut quality classification, based on kerf geometry and heat affected zone size is formulated to help in selecting the optimum cutting conditions in order to obtain the best cut quality.
TL;DR: In this paper, the entire thermo-fluid-dynamic field resulting from the coupling of natural convection along and conduction inside a heated flat plate is studied by means of two expansions.
TL;DR: Immunohistochemical study demonstrated the polyclonal nature of the plasma cells and characterized the stromal cells as myofibroblasts as well as the nature of these cells was confirmed ultrastructurally.
Abstract: The first case of plasma cell granuloma (PCG) of the breast is presented. The lesion was seen as a circumscribed firm mass in the right breast of a 29-year-old woman. Histologically, a prominent plasma cell infiltrate was seen in a fibrous hyalinized stroma that contained spindle- and large stellate-shaped stromal cells with bizarre nuclei. Immunohistochemical study demonstrated the polyclonal nature of the plasma cells and characterized the stromal cells as myofibroblasts. The nature of these cells was confirmed ultrastructurally. PCG of the breast should be considered analogous to inflammatory pseudotumors of the lung and extrapulmonary sites.
TL;DR: It is demonstrated that insulin-induced erythrocyte magnesium accumulation is impaired in patients with Type 2 diabetes and that such defect is correlated to impaired insulin-mediated glucose disposal in these patients.
Abstract: Plasma and erythrocyte magnesium levels were measured by atomic absorption spectrometry in 12 healthy subjects and 12 moderately obese patients with Type 2 (non-insulin-dependent) diabetes mellitus. Basal plasma and erythrocyte magnesium levels were significantly lower in diabetic patients than in control subjects. In vitro incubation in the presence of 100 mU/l insulin significantly increased magnesium erythrocyte levels in both control subjects (p less than 0.001) and patients with diabetes (p less than 0.001). However, even in the presence of 100 mU/l insulin, the erythrocyte magnesium content of patients with Type 2 diabetes was lower than that of control subjects. The in vitro dose-response curve of the effect of insulin on magnesium erythrocyte accumulation was shifted to the right when red cells of diabetic patients were used, with a highly significant reduction of the maximal effect. Such reduction of the maximal effect of insulin suggests that the impairment of insulin-induced erythrocyte magnesium accumulation observed in Type 2 diabetic patients results essentially from a post-receptor defect.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Data support the concept that insulin per se is a potent physiological modulator of islet A- and B-cell function and suggest that these effects of insulin are reinforced when the hormone is administered in an intermittent manner in an attempt to reproduce the pulsatile physiological release of insulin.
Abstract: The respective modulating effects of continuous and intermittent insulin delivery on pancreatic islet cell function were studied in seven normal men and nine insulin-dependent (type 1) diabetic patients. In the normal men, saline or continuous (0.8 mU kg−1 min−1) or pulsatile (5.2 mU kg−1 min−1, with a switching on/off length of 2/11 min) human insulin were delivered on different days and in random order. Despite hyper-insulinemia, blood glucose was kept close to its basal value by the glucose clamp technique. The diabetic patients also were infused in random order and on different days with either saline or a smaller amount of insulin delivered continuously (0.15 mU kg−1 min−1) or in a pulsatile manner (0.97 mU kg−1 min−1 for 2 min, followed by 11 min during which no insulin was infused). In all experiments, 5 g arginine were given iv as a bolus dose 30 min before the end of the study, and plasma C-peptide and glucagon levels were determined to assess islet cell function. In the normal men, insulin admin...
Journal Article•
TL;DR: Intracranial lipomas are rare lesions of developmental origin, which mainly occur in the region of the corpus callosum, more rarely in the ambient, interpeduncular, cerebellopontine angle and sylvian cisterns and can sometimes show neurological symptoms, mainly epileptic seizures.
Abstract: Fourteen cases of intracranial lipomas are reported and 200 cases from the literature are reviewed. Intracranial lipomas are rare lesions of developmental origin, which mainly occur in the region of the corpus callosum, more rarely in the ambient, interpeduncular, cerebellopontine angle and sylvian cisterns. Although they are usually asymptomatic, they can sometimes show neurological symptoms, mainly epileptic seizures. Computerized tomography and magnetic resonance imaging usually lead to the diagnosis, because of the very low-density attenuation values of lipomas on CT scan and the short T1 and T2 on magnetic resonance. A direct surgical approach is only rarely indicated, whereas cases associated to hydrocephalus require a CSF shunt. The anticonvulsivant therapy usually results in remission of the seizures.
TL;DR: The conformational preferences of the N-trifluoroacetylated homo-peptides of Cα,α-diethylglycine from monomer to pentamer in chloroform solution were determined by using ir absorption and 1H-nmr as discussed by the authors.
Abstract: The conformational preferences of the N-trifluoroacetylated homo-peptides of Cα,α-diethylglycine from monomer to pentamer in chloroform solution were determined by using ir absorption and 1H-nmr. Intramolecular hydrogen bonding was found to be the dominant factor for all NH groups. The likely absence of a conformational transition upon increasing main-chain length, and the remarkable stability to dilution, heating, and addition of perturbing agents, are additional relevant findings of this study. These results are in agreement with those of the fully extended, C5-conformation-forming homo-peptides from the higher homolog Cα,α-di-n-propylglycine, but contrast dramatically to those of the homo-peptides from the lower homolog Cα,α-dimethylglycine, which have been shown to adopt the 310-helical structure.
TL;DR: LV hypertrophy attenuates the influence of changes in afterload on LV function and restores a fractional shortening end-systolic stress relation quite comparable to that found both in normotensives and in hypertensives before the development of LVhypertrophy.
Abstract: In 3 age- and sex-matched groups of subjects—15 normotensives, 15 hypertensives without left ventricular (LV) hypertrophy and 15 hypertensives with LV hypertrophy—the slopes of the regression line obtained by plotting the individual values of LV fractional shortening against the corresponding values of echocardiographic end-systolic stress were compared. The first 2 groups were studied only in control conditions while the third group was restudied after a 20% reduction in LV mass index induced by a long-term antihypertensive treatment and after a 3-week washout period. A significant relation between fractional shortening and end-systolic stress was found in all instances. The slope of this correlation was higher in normotensives (−0.251) and in hypertensives without LV hypertrophy (−0.232) (both p
TL;DR: The data support the sequential hypothesis and provide evidence for a primary role of SS in brain information processing and the structure of sleep was different in NL rats in comparison to C rats, chiefly because SS episodes were markedly longer in the former group.
TL;DR: Tests assessing the permeability of the small intestine and the blood levels of antigliadin antibodies have recently gained success as noninvasive tools for the diagnosis of the GSE.
TL;DR: Quantitative data obtained with PET seems to provide further insight into the study of BBB function in multiple sclerosis.
Abstract: Fifteen patients with definite multiple sclerosis were examined with high volume delayed (HVD) CT scan and positron emission tomography (PET) using 68-Ga-EDTA as a tracer. The passage of 68-Ga-EDTA across the blood-brain barrier (BBB) was measured by using multiple graphical analysis. This method permits the simultaneous calculation of a blood to brain influx constant Ki (ml/g-1 min-1) and of the plasma volume Vp (ml/g-1). Focal areas of abnormal CT enhancement and pathological accumulation of 68-Ga-EDTA were visualised in four patients who were all examined during a clinical exacerbation of the disease. The mean Ki value measured in these areas was 12.5, SD 3.4 indicating a moderate but significant increase of BBB permeability compared with the value found in normal tissue (3.2, SD 0.9). No parallel increase in Vp values was found in these pathological areas. Quantitative data obtained with PET seems to provide further insight into the study of BBB function in multiple sclerosis.
TL;DR: In this article, a stochastic model for single neuron's activity is constructed as the continuous limit of a birth-and-death process in the presence of a reversal hyperpolarization potential.
Abstract: A stochastic model for single neuron's activity is constructed as the continuous limit of a birth-and-death process in the presence of a reversal hyperpolarization potential. The resulting process is a one dimensional diffusion with linear drift and infinitesimal variance, somewhat different from that proposed by Lanský and Lanska in a previous paper. A detailed study is performed for both the discrete process and its continuous approximation. In particular, the neuronal firing time problem is discussed and the moments of the firing time are explicitly obtained. Use of a new computation method is then made to obtain the firing p.d.f. The behaviour of mean, variance and coefficient of variation of the firing time and of its p.d.f. is analysed to pinpoint the role played by the parameters of the model. A mathematical description of the return process for this neuronal diffusion model is finally provided to obtain closed form expressions for the asymptotic moments and steady state p.d.f. of the neuron's membrane potential.
TL;DR: In this paper, the sorption behavior of water molecules in epoxy-based thermosetting networks is discussed and related to the modifications of the polymer properties, and the hypothesized sorption modes and the corresponding mechanisms of plasticization are discussed on the basis of experimental liquid-sorption tests, differential scanning calorimetry (DSC), and electrical analyses.
Abstract: The sorption behaviour of water molecules in epoxy-based thermosetting networks is discussed and related to the modifications of the polymer properties. The hypothesized sorption modes and the corresponding mechanisms of plasticization are discussed on the basis of experimental liquid-sorption tests, differential scanning calorimetry (DSC), and electrical analyses. Two modes of moisture sorption are assumed: a sorption leading to an increase in the free volume of the system, and adsorption of the water molecules due to hydrogen bonding to hydrophilic groups present in the network and to the surfaces of “holes” which make up the excess free volume of the glassy polymer. Electrical investigation improved the understanding of the hygrothermal ageing phenomena. Water conditioning of the composites modified the surface and bulk resistivities as a consequence of microstructural damage and plasticization.
TL;DR: The prevalence of a positive history for urinary stone (radiographic and/or surgical evidence, and/ or stone excretion) was increased by over 50% in treated and untreated hypertensives, and none of the 136 subjects with a positive urinary stone history were hypercalcaemic and none had renal failure.
Abstract: Mild hypercalciuria has been observed in hypertension, but it is not yet established whether the prevalence of urinary stone disease is increased as well. Data from the cross-sectional phase of the Gubbio Study--a population-based survey on hypertension involving 5376 subjects (84% response rate)--have been analysed to address this issue, defining as hypertensive those subjects with diastolic pressure falling within the fifth quintile for each sex- and age-specific category, and/or under regular antihypertensive treatment. The prevalence of a positive history for urinary stone (radiographic and/or surgical evidence, and/or stone excretion) was increased by over 50% (P less than 0.01) in treated and untreated hypertensives. None of the 136 subjects with a positive urinary stone history were hypercalcaemic and none had renal failure.