Showing papers by "University of Catania published in 1997"

Performance And Reliability Analysis Of Computer Systems (an Example-based Approach Using The Sharpe Software

Abstract: Performance and Reliability Analysis of Computer Systems: An Example-Based Approach Using the SHARPE Software Package provides a variety of probabilistic, discrete-state models used to assess the reliability and performance of computer and communication systems. The models included are combinatorial reliability models (reliability block diagrams, fault trees and reliability graphs), directed, acyclic task precedence graphs, Markov and semi-Markov models (including Markov reward models), product-form queueing networks and generalized stochastic Petri nets. A practical approach to system modeling is followed; all of the examples described are solved and analyzed using the SHARPE tool. In structuring the book, the authors have been careful to provide the reader with a methodological approach to analytical modeling techniques. These techniques are not seen as alternatives but rather as an integral part of a single process of assessment which, by hierarchically combining results from different kinds of models, makes it possible to use state-space methods for those parts of a system that require them and non-state-space methods for the more well-behaved parts of the system. The SHARPE (Symbolic Hierarchical Automated Reliability and Performance Evaluator) package is the `toolchest' that allows the authors to specify stochastic models easily and solve them quickly, adopting model hierarchies and very efficient solution techniques. All the models described in the book are specified and solved using the SHARPE language; its syntax is described and the source code of almost all the examples discussed is provided. Audience: Suitable for use in advanced level courses covering reliability and performance of computer and communications systems and by researchers and practicing engineers whose work involves modeling of system performance and reliability.

Identification and analysis of mutations in the Wilson disease gene (ATP7B): population frequencies, genotype-phenotype correlation, and functional analyses.

Abstract: Wilson disease (WD) is an autosomal recessive disorder characterized by toxic accumulation of copper in the liver and subsequently in the brain and other organs. On the basis of sequence homology to known genes, the WD gene (ATP7B) appears to be a copper-transporting P-type ATPase. A search for ATP7B mutations in WD patients from five population samples, including 109 North American patients, revealed 27 distinct mutations, 18 of which are novel. A composite of published findings shows missense mutations in all exons-except in exons 1-5, which encode the six copper-binding motifs, and in exon 21, which spans the carboxy-terminus and the poly(A) tail. Over one-half of all WD mutations occur only rarely in any population sample. A splice-site mutation in exon 12 accounts for 3% of the WD mutations in our sample and produces an in-frame, 39-bp insertion in mRNA of patients homozygous, but not heterozygous, for the mutation. The most common WD mutation (His1069Glu) was represented in approximately 38% of all the WD chromosomes from the North American, Russian, and Swedish samples. In several population cohorts, this mutation deviated from Hardy-Weinberg equilibrium, with an overrepresentation of homozygotes. We did not find a significant correlation between His1069Glu homozygosity and several clinical indices, including age of onset, clinical manifestation, ceruloplasmin activity, hepatic copper levels, and the presence of Kayser-Fleischer rings. Finally, lymphoblast cell lines from individuals homozygous for His1069Glu and 4 other mutations all demonstrated significantly decreased copper-stimulated ATPase activity.

Synthesis, Characterization, Optical Spectroscopic, Electronic Structure, and Second-Order Nonlinear Optical (NLO) Properties of a Novel Class of Donor−Acceptor Bis(salicylaldiminato)nickel(II) Schiff Base NLO Chromophores

Abstract: The synthesis, characterization, thermal stability, optical spectroscopic, electronic structure, and second-order nonlinear optical (NLO) response of a series of donor−acceptor bis(salicylaldiminato)nickel(II) Schiff base complexes and the free ligand precursors are reported The effect of the metal center in such complexes is manifold: it templates the formation of acentric molecular structures, imparts high thermal stability to the chelate ring, and both “switches on” and enhances NLO response Metal complexation imparts new linear optical spectroscopic features, having metal-to-ligand charge transfer character, which are responsible for the second-order nonlinearity Moreover, the present synthetic strategy represents a novel route to inorganic NLO chromophores Solution-phase hyperpolarizability values, deduced by electric field-induced second-harmonic-generation experiments are as high as −79 × 10-30 cm5 esu-1 (hω = 092 eV) Experimental linear and nonlinear optical features are fully consistent wi

Efficiency of Molecular Hydrogen Formation on Silicates

Abstract: We report on laboratory measurements of molecular hydrogen formation and recombination on an olivine slab as a function of surface temperature under conditions relevant to those encountered in the interstellar medium. On the basis of our experimental evidence, we recognize that there are two main regimes of H coverage that are of astrophysical importance; for each of them we provide an expression giving the production rate of molecular hydrogen in interstellar clouds.

Early diagnosis by genetic analysis of differentiated thyroid cancer metastases in small lymph nodes

Abstract: We report a PCR-based technique for detecting thyroid cancer metastases in small nodes <1.5 cm diameter by the amplification of thyroid specific transcripts TSH-receptor and thyroglobulin. A 100% correspondence with the histopathological diagnosis was observed in the 41/46 nodes (89%) in which an adequate sample was obtained at fine needle aspiration. The genetic analysis resulted more sensitive and accurate than both the cytological analysis (28% inadequate samples, 17% false negative diagnoses) and the thyroglobulin measurement in the aspirates (39% false negatives). The PCR-based genetic analysis may provide a useful tool for diagnosis and follow-up of thyroid cancer.

Laboratory Synthesis of Molecular Hydrogen on Surfaces of Astrophysical Interest

Abstract: We report on the first results of experiments to measure the recombination rate of hydrogen on surfaces of astrophysical interest. Our measurements give lower values for the recombination efficiency (sticking probability S times the probability of recombination upon H-H encounter, ?) than model-based estimates. We propose that our results can be reconciled with average estimates of the recombination rate [(1/2)nHngvHAS?] from astronomical observations, if the actual surface of an average grain is rougher, and its area bigger, than the one considered in models.

Prevalence of chronic diseases in older Italians: Comparing self-reported and clinical diagnoses

Abstract: BACKGROUND The Italian Longitudinal Study on Aging (ILSA) evaluates the rates of diabetes, cardiovascular and neurological disorders in a random sample of 5632 Italians aged 65-84 years. METHODS The ILSA has two components: a first screening phase administered to all participants, that includes a personal interview, physician examination, laboratory and diagnostic tests, and a second phase, consisting of the clinical confirmation of suspected cases by a specialist. RESULTS Prevalence rates were significantly higher among men for myocardial infarction (10.7% versus 4.8%), cardiac arrhythmia (25.1% versus 20.3%) and peripheral artery disease (8.1% versus 5.2%), and among women for hypertension (67.3% versus 59.4%), heart failure (7.3% versus 5.4%) and dementia (7.2% versus 5.3%). No gender difference was found for stroke, angina, diabetes, Parkinsonism and distal symmetric neuropathy. Unreported diagnoses accounted for 85% of cases of distal symmetric neuropathy, for more than half the cases of cardiac failure, for 40% of cases of angina, and for more than one-third of cases arrhythmia, myocardial infarction, peripheral artery disease, hypertension, Parkinsonism. Data from the phase 1 interview showed substantial overreporting for myocardial infarction, peripheral artery disease, diabetes, and stroke. CONCLUSIONS The authors conclude that self-reported information would lead to inaccurate estimates of prevalence rates suggesting the need for including the clinical ascertainment in any population-based epidemiological study.

The Neuroprotective Activity of Group-II Metabotropic Glutamate Receptors Requires New Protein Synthesis and Involves a Glial–Neuronal Signaling

Abstract: The group-II metabotropic glutamate (mGlu) receptor agonists (2S,1′R,2′R,3′R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV), S-4-carboxy-3-hydroxyphenylglycine (4C3HPG), and (2S,1′S,2′S)-2-(carboxycyclopropyl)glycine (L-CCG-I) protected mouse cortical neurons grown in mixed cultures against excitotoxic degeneration induced by a 10 min pulse with NMDA. Protection was observed not only when agonists were added in combination with NMDA but also when they were transiently applied to cultures 6–20 hr before the NMDA pulse. In both cases, neuroprotection was reduced by the group-II mGlu receptor antagonist (2S,1′S,2′S,3′R)-2-(2′-carboxy-3′-phenylcyclopropyl)glycine (PCCG-IV), as well as by the protein synthesis inhibitor cycloheximide (CHX). Both neurons and astrocytes in mixed cultures were immunostained with an antibody that recognized mGlu2 and mGlu3 receptors in recombinant cells. To determine whether astrocytes played any role in the neuroprotection mediated by group-II mGlu receptors, we exposed pure cultures of cortical astrocytes to DCG-IV, 4C3HPG, or L-CCG-I for 10 min. The astrocyte medium collected 2–20 hr after the exposure to any of these drugs was highly neuroprotective when transferred to mixed cultures treated with NMDA. This protective activity was reduced when CHX was applied to astrocyte cultures immediately after the transient exposure to group-II mGlu receptor agonists. We conclude that neuroprotection mediated by group-II mGlu receptors in cultured cortical cells requires new protein synthesis and involves an interaction between neurons and astrocytes.

Expression and Coupling to Polyphosphoinositide Hydrolysis of Group I Metabotropic Glutamate Receptors in Early Postnatal and Adult Rat Brain

Abstract: We investigated the expression and coupling to the phospholipase C signal transduction pathway of metabotropic glutamate receptor (mGluR) subtypes by Western blot analysis and agonist-stimulated inositol monophosphate formation in several brain regions of postnatal day 9 (P9) and adult rats. In the cerebral cortex, hippocampus, corpus striatum, olfactory bulb, cerebellum and hypothalamus, the expression level of mGluR5 was greater at P9 than in adulthood. The mGluR5 signal was very low or absent in the adult cerebellum and hypothalamus. The expression of mGluR1a was slightly greater at P9 in the hypothalamus, hippocampus and olfactory bulb, whereas it substantially increased with age in the cerebellum, and did not change in the cerebral cortex and corpus striatum. mGluR1b and -1c were nearly undetectable by Western blot analysis. The expression level of mGluR5, but not that of mGluR1a, was significantly correlated with the extent of phosphoinositide hydrolysis stimulated by mGluR agonists in slices prepared from these brain regions. The mGluR antagonist cyclopropan[b]chromen-1a-carboxylic acid ethylester (CPCCOEt), potently antagonized responses mediated by mGluR1, but much less potently those mediated by mGluR5a in recombinant cells. CPCCOEt, at a concentration which efficiently blocks mGluR1 responses, did not substantially affect the polyphosphoinositide response in hippocampal or cerebellar slices from newborn animals, and antagonized only a minor component of the polyphosphoinositide response in adult hippocampal slices. CPCCOEt, however, prevented the small stimulation of polyphosphoinositide hydrolysis by mGluR agonists in adult cerebellar slices. We conclude that (i) the efficient mGluR-mediated polyphosphoinositide hydrolysis in 9-day-old rats is mediated by mGluR5; (ii) the increased expression of mGluR1 in the adult cerebellum does not substitute for the decline of mGluR5 expression in the ability to mediate polyphosphoinositide hydrolysis; and therefore (iii) mGluR1a might couple less efficiently than mGluR5 to polyphosphoinositide hydrolysis.

High Superoxide Dismutase Activity of a Novel, Intramolecularly Imidazolato-Bridged Asymmetric Dicopper(II) Species. Design, Synthesis, Structure, and Magnetism of Copper(II) Complexes with a Mixed Pyrazole-Imidazole Donor Set.

Abstract: A new dinucleating ligand, 1,5-bis(1-pyrazolyl)-3-[bis(2-imidazolyl)methyl] azapentane (Hbpzbiap), containing pyrazoles and imidazoles has been designed and synthesized. The synthesis and characterization of the copper complexes with the ligand Hbpzbiap and its dehydronated form are described. This study is aimed at modeling the active site of copper−zinc superoxide dismutase (SOD). Single crystals of the imidazolato-bridged complex [Cu2(bpzbiap)Cl3] (1) and non-imidazolato-bridged complex [Cu2(Hbpzbiap)Cl4] (2) were obtained and their structures determined by X-ray diffraction. Both structures show two copper centers in two different coordination environments: a distorted square pyramid and a distorted tetrahedron. The Cu−nitrogen bond lengths range from 1.919(4) to 2.039(3) A and are as expected. The copper−copper distances from 5.566(1) to 6.104(1) A being only slightly shorter than that found in bovine erythrocyte SOD. Temperature-dependent magnetic susceptibility study of 1 shows antiferromagnetic b...

A compensation strategy for two-stage CMOS opamps based on current buffer

Abstract: The compensation with current buffer overcomes the typical drawbacks of the compensations based on nulling resistor or voltage buffer, but it is not as straightforward as the other two approaches. Indeed, a constraint on the current-buffer input resistance has to be met in order to achieve frequency compensation, since complex conjugate poles arise in the loop transfer function. Design equations for an optimized compensation strategy with current buffer are determined. They allow a high gain-bandwidth product to be achieved avoiding the drawbacks which arises with voltage buffer and nulling resistor approaches.

UV‐curable systems containing perfluoropolyether structures: Synthesis and characterisation

Abstract: The synthesis of new functionalised macromers containing perfluoropolyether structures (PFPE) is reported. They are obtained by reaction of bis-CH 2 OH terminated PFPE with isocyanato-ethyl methacrylate (EIM). giving rise to the formation of perfluoropolyether bisurethane methacrylate (PFEUMA) oligomers. The products are characterised by NMR and FTIR analyses. The thermal behaviour reveals two amorphous phases, corresponding to the fluorinated and the hydrogenated moieties, while a crystalline phase can be present depending on the macromer structure. The functionalised macromers are UV-cured in the presence of a photoinitiator and the complete disappearance of the double bonds is obtained. The cured films are characterised by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) confirming the presence of a multiphasic structure. Moreover the optical properties and the surface properties of the cured systems are investigated and discussed.

Detection of an activating mutation of the thyrotropin receptor in a case of an autonomously hyperfunctioning thyroid insular carcinoma

Abstract: Thyroid carcinomas, even when well differentiated, usually appear as hypofunctioning at scintigraphy We report a case of an aggressive insular thyroid carcinoma presenting as an autonomously functioning thyroid nodule and causing severe thyrotoxicosis The tumor was metastatic to a cervical lymph node and both lungs An activating mutation of the TSH receptor gene in both the primary tumor and the lymph node metastasis was found, due to a base substitution at codon 633 (normal guanine at position 1896 replaced by cytosine CAC for GAC causing aspartic acid substitution by histidine) Other known oncogenes (gsp, ras, PTC/ret, trk, met, and p53) were not involved This is the first description of an activating TSH receptor mutation in a thyroid hyperfunctioning carcinoma in which an aggressive malignant phenotype coexisted with activation of the cAMP cascade and differentiated thyroid functions

Switching-behavior improvement of insulated gate-controlled devices

Abstract: MOSFETs and insulated gate bipolar transistor (IGBT) devices are increasingly used in electronic circuits due to both their easy driving and ability to handle high currents and voltages at high-switching frequencies. This paper deals with a new driver technique that allows optimization of the switching speed, reduction of the energy losses during the switching time, and limitation of the electromagnetic interference (EMI). First, an analysis of voltage- and current-switching waveforms of gate-insulated devices is performed. Then, a method of controlling voltage and current slopes independently is shown using the "one-cycle" method or a suitable adaptive-driving technique based on a phase-locked loop (PLL) approach. These techniques were adopted in order to allow correct generation of the gate signals regardless of the operating conditions. Finally, practical results of the proposed driving circuit obtained using a single IGBT switch chopper are presented.

Increased adipose tissue PC-1 protein content, but not tumour necrosis factor-a gene expression, is associated with a reduction of both whole body insulin sensitivity and insulin receptor tyrosine-kinase activity

Abstract: In the present study we measured PC-1 content, tumour necrosis factor (TNF)-α gene expression, and insulin stimulation of insulin receptor tyrosine-kinase activity in adipose tissue from non-obese, non-diabetic subjects These parameters were correlated with in vivo insulin action as measured by the intravenous insulin tolerance test (Kitt values) PC-1 content was negatively correlated with Kitt values (r = –05, p = 004) and positively with plasma insulin levels both fasting (r = 058, p = 0009) and after 120 min during oral glucose tolerance test (OGTT) (r = 067, p = 0002) Moreover, adipose tissue PC-1 content was higher in relatively insulin-resistant subjects (Kitt values lower than 6) than in relatively insulin-sensitive subjects (Kitt values higher than 6) (525 ± 49 ng/mg protein vs 336 ± 45, respectively, p = 0012) Adipose tissue insulin receptor tyrosine-kinase activity in response to insulin was significantly lower at all insulin concentrations tested (p = 0017, by two-way analysis of variance test) in insulin-resistant than in insulin-sensitive subjects (Kitt values lower or higher than 6, respectively) In contrast to PC-1, no significant correlation was observed between adipose tissue TNF-α mRNA content and Kitt values, and plasma insulin levels, both fasting and at after 120 min during OGTT Also, no difference was observed in TNF-α mRNA content between subjects with Kitt values higher or lower than 6 These studies in adipose tissue, together with our previous studies in skeletal muscle raise the possibility that PC-1, by regulating insulin receptor function, may play a role in the degree of insulin sensitivity in non-obese, non-diabetic subjects [Diabetologia (1997) 40: 282–289]

Opposite influence of the metabotropic glutamate receptor subtypes mGlu3 and -5 on astrocyte proliferation in culture.

Abstract: In non-synchronized, subconfluent secondary cultures of rat cortical astrocytes, the selective group-I metabotropic glutamate (mGlu) receptor agonist 3,5-dihydroxyphenylglycine (DHPG) increased [methyl-3H]-thymidine incorporation. This effect was mediated by the activation of the mGlu5 receptor, which was shown to be present by either RT-PCR or Western blot analysis. The mixed mGlu receptor antagonist (+)-α-methyl-4-carboxyphenylglycine reduced the increase in both intracellular Ca2+ and [methyl-3H]-thymidine incorporation produced by DHPG. In contrast, (2S,1′R,2′R,3′R)-2-(2,3-dicarboxycylopropyl)glycine (DCG-IV), a potent and selective agonist of group-II mGlu receptors, reduced [methyl-3H]-thymidine incorporation in non-synchronized astrocyte cultures. The antiproliferative effect of DCG-IV was prevented by the selective group-II mGlu receptor antagonist (2S,1′S,2′S,3′R)-2-(2′-carboxy-3′-phenylcyclopropyl)glycine (PCCG-IV). The opposite effect of DHPG and DCG-IV on astrocyte proliferation was confirmed in cultures deprived of serum for 48 hours and then stimulated to proliferate with either epidermal growth factor (EGF) or the metabolically stable ATP analogue adenosine 5′-(β,γ-imido)-triphosphate (AMP-PNP). We conclude that activation of mGlu5 receptors enhances proliferation in cultured astrocytes, whereas activation of a receptor with pharmacological characteristics similar to those of mGlu2/3 receptors reduces proliferation. GLIA 21:390–398, 1997. © 1997 Wiley-Liss, Inc.

ASPB10 insulin induction of increased mitogenic responses and phenotypic changes in human breast epithelial cells: evidence for enhanced interactions with the insulin-like growth factor-I receptor.

Abstract: The human insulin analogue ASPB10 has been reported to have increased affinity for the insulin receptor and to cause breast cancer in female rats. In the study reported here, we investigated whether ASPB10 has an increased mitogenic potency and induces a transformed phenotype in cultured human breast cells. In both MCF-10 cells (a non-malignant human breast line) and MCF-7 cells (a human breast cancer cell line), ASPB10 was approximately twofold more potent than insulin in competing for 125I-insulin binding but sevenfold to tenfold more potent than insulin in competing for 125I-insulin-like growth factor (IGF)-I binding. In addition, ASPB10 was twofold more potent than insulin in stimulating insulin receptor autophosphorylation but significantly more potent in stimulating IGF-I receptor autophosphorylation in both cell lines. Moreover, ASPB10 was approximately sevenfold more potent than insulin in stimulating the growth of MCF-10 and MCF-7 cells. This increased mitogenic effect of ASPB10 was significantly inhibited (but not abolished) when cells were cultured in the presence of α-IR3, a monoclonal antibody to the IGF-I receptor. ASPB10, but not insulin, caused phenotypic changes (focus formation) in MCF-10 cells. Neither agent caused colony formation in soft agar in MCF-10 cells, but ASPB10 was more potent than insulin in stimulating colony formation in MCF-7 cells. These observations indicate that in human breast cells, ASPB10 has enhanced mitogenic effects and induces phenotypic changes as a consequence of its activation of both insulin and IGF-I receptors. Mol. Carcinog. 18:19–25, 1997. © 1997 Wiley-Liss, Inc.