Showing papers by "Sapienza University of Rome published in 1993"

Preliminary criteria for the classification of Sjögren's syndrome. Results of a prospective concerted action supported by the European Community.

Abstract: Objective. Different sets of diagnostic criteria have been proposed for Sjogren's syndrome (SS), but none have been validated with a large series of patients or in a multicenter study. We conducted the present study involving 26 centers from 12 countries (11 in Europe, plus Israel), with the goals of reaching a consensus on the diagnostic procedures for SS and defining classification criteria to be used in epidemiologic surveys and adopted by the scientific community. Methods. The study protocol was subdivided into two parts. For part I, questionnaires regarding both ocular and oral involvement were developed; they included 13 questions and 7 questions, respectively. For part II a limited set of diagnostic tests was selected, and the exact procedure to be followed in performing these tests was defined. Part I of the study ipcluded 240 patients with primary SS and 240 age- and sex-matched controls. Two hundred forty-six patients with primary SS, 201 with secondary SS, 113 with connective tissue diseases but without associated SS, and 133 control patients were studied in part II. Results. The study resulted in (a) the validation of a simple 6-item questionnaire for determination of dry eyes and dry mouth, which showed good discriminant power between patients and controls, to be used in the initial screening for sicca syndrome; and (b) the definition of a new set of criteria for the classification of SS. The sensitivity and specificity of the criteria in correctly identifying patients with either the primary or the secondary variant of SS were also determined. Conclusion. Using the findings of this prospective multicenter European study, general agreement can be reached on the diagnostic procedures to be used for patients with SS. Final validation of the preliminary classification criteria for SS is underway.

Hoover NPT dynamics for systems varying in shape and size

Abstract: In this paper we write down equations of motion (following the approach pioneered by Hoover) for an exact isothermal-isobaric molecular dynamics simulation, and we extend them to multiple thermostating rates, to a shape-varying cell and to molecular systems, coherently with the previous ‘extended system method’. An integration scheme is proposed together with a numerical illustration of the method.

Analytical solution of the off-equilibrium dynamics of a long-range spin-glass model.

Abstract: We study the nonequilibrium relaxation of the spherical spin-glass model with p-spin interactions in the N\ensuremath{\rightarrow}\ensuremath{\infty} limit. We analytically solve the asymptotics of the magnetization and the correlation and response functions for long but finite times. Even in the thermodynamic limit the system exhibits ``weak'' (as well as ``true'') ergodicity breaking and aging effects. We determine a functional Parisi-like order parameter ${\mathit{P}}_{\mathit{d}}$(q) which plays a similar role for the dynamics to that played by the usual function for the statics.

Silent period evoked by transcranial stimulation of the human cortex and cervicomedullary junction.

Abstract: 1. The silent period evoked in the first dorsal interosseous (FDI) muscle after electrical and magnetic transcranial stimulation (TCS), electrical stimulation of the cervicomedullary junction and ulnar nerve stimulation was studied in ten healthy subjects. 2. With maximum-intensity shocks, the average duration of the silent period was 200 ms after electrical TCS, 300 ms after magnetic TCS, 43 ms after stimulation at the cervicomedullary junction and 100 ms after peripheral nerve stimulation. 3. The duration of the silent period, the amplitude of the motor-evoked potential, and the twitch force produced in the muscle were compared at increasing intensities of magnetic TCS. When the stimulus strength was increased from 30 to 70% of the stimulator output, the duration of the silent period lengthened as the amplitude of the motor potential and force of the muscle twitch increased. At 70 to 100% of the output, the amplitude of the motor potential and force of the muscle twitch saturated, whereas the duration of the silent period continued to increase. 4. Proximal arm muscle twitches induced by direct electrical stimulation of the biceps and extensor wrist muscles produced no inhibition of voluntary activity in the contracting FDI muscle. 5. The level of background activation had no effect on the duration of the silent period recorded in the FDI muscle after magnetic TCS. 6. Corticomotoneurone excitability after TCS was studied by means of a single magnetic conditioning shock and a test stimulus consisting either of one single magnetic shock or single and double electrical shocks (interstimulus interval 1.8 ms) in the relaxed muscle. A conditioning magnetic shock completely suppressed the response evoked by a second magnetic shock, reduced the size of the response evoked by a single electrical shock but did not affect the response evoked by double electrical shocks. Inhibition of the test magnetic shock was also present during muscle contraction. 7. Our findings indicate that the first 50 ms of the silent period after TCS are produced mainly by spinal mechanisms such as after-hyperpolarization and recurrent inhibition of the spinal motoneurones. If descending inhibitory fibres contribute, their contribution is small. Changes in proprioceptive input probably have a minor influence. From 50 ms onwards the silent period is produced mainly by cortical inhibitory mechanisms.

Increased cytokine production in mononuclear cells of healthy elderly people.

Abstract: The production of cytokines during aging, except interleukin (IL)-2, has been neglected in humans. We measured the in vitro production of IL-6, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and IL-1 beta by peripheral mononuclear cells from selected healthy young (mean age 26.8 years) and aged (mean age 80.2 years) subjects. Significant increases of IL-6, TNF-alpha and IL-1 beta levels were found in mitogen-stimulated cultures from aged donors, occurring at 24 to 72 h after stimulation. No significant differences were observed for IFN-gamma production. Proliferative capability of cells stimulated with PHA was not impaired in aged subjects. Since the amounts of all cytokines studied were similar in unstimulated cultures from young and aged subjects, and also serum levels of TNF-alpha did not differ, these data indicate that the cellular machinery for the production of these cytokines is well preserved in aging, and also that cells from old people are able to up-regulate their production in response to appropriate stimuli. The increases in cytokine synthesis were not dependent on changes in the number of monocytes, nor were they related to the significant rise of CD45RO+, and the concomitant decrease of CD45RA+, occurring in both CD4+ and CD8+ lymphocytes from aged subjects. The increased production of pro-inflammatory cytokines by stimulated mononuclear cells of healthy aged subjects may be relevant to several aspects of age-associated pathological events, including atherosclerosis, osteoporosis, fibrosis and dementia.

The European Cooperative Acute Stroke Study (ECASS)

Abstract: Stroke represents the third most common cause of death and is a major reason for hospitalization in the developed countries. It afflicts approximately 700000 Europeans annually. Stroke is a tragic occurrence to its victims and it also causes enormous financial costs. To date, no therapy is available to improve the outcome of patients with ischemic stroke. Stroke therapies have been aimed at the prevention of future cerebrovascular attacks. The significant mortality and morbidity associated with stroke necessitate development of acute therapeutic interventions to limit stroke mortality and morbidity.

Discrete time techniques for time delay estimation

Abstract: Basic aspects of time delay estimation (TDE) based on sampled signals are investigated. The direct cross-correlation method is analyzed and compared to the average square difference function (ASDF) and the (addition only based) average magnitude difference function (AMDF) estimators, Their relative accuracy is theoretically evaluated, and previous empirical results are explained. It is shown that both the ASDF- and the AMDF-based estimators outperform the direct cross-correlation based estimator for medium-high signal-to-noise ratios. Moreover, the AMDF-based estimator, which avoids any multiplications, significantly reduces the computational complexity of the estimation procedure while offering only a moderate performance loss with respect to the ASDF based estimator. >

Lightning-induced voltages on overhead lines

Abstract: A modeling procedure that permits calculation of lightning-induced voltages on overhead lines starting from the channel-base current is discussed. The procedure makes use of a coupling model already presented in the literature, based on transmission line theory, for field-to-overhead line coupling calculations. Both models are discussed and compared with experimental results. The hypothesis of perfect conducting ground, used to analyze the voltages induced on an overhead line by a nearby lightning return stroke with a striking point equidistant from the line terminations, and the limits of its validity are determined. A comparison shows that peak value and maximum front steepness of the induced voltages calculated using other lightning return-stroke models differ. It is also shown that another coupling model used in the power-lightning literature by several other authors may result in a less accurate estimation of the induced voltages. >

Early emotional instability, prosocial behaviour, and aggression: some methodological aspects

Abstract: The internal consistency of Emotional Instability, Prosocial Behaviour, and Aggression scales was examined in elementary school children aged between 7 and 10 years. Multiple informants (self-report, teacher rating, mother rating, and peer nomination) were obtained on the above three dimensions. Relationships between the scales were first examined within the single informant frame of reference and then between informants. The concurrent validity was assessed using sociometric measures (popularity, rejection, social impact, and social preference) and the Achenbach and Edelbrock Child Behavior Checklist (teacher and parent form). The results confirm the internal validity of the three scales measuring emotional instability, prosocial behaviour, and aggression in child self-report, teacher rating, and mother rating. The use of self-report measures seems promising within the multiple informant strategy of research on child behaviour. Correlational results show satisfactory concurrent validity for the three scales, especially for teacher rating and peer nomination. The strict relation between emotional instability and aggression poses problems of discriminant validity which need to be further investi gated.

The Athb-1 and -2 HD-Zip domains homodimerize forming complexes of different DNA binding specificities.

Abstract: The Arabidopsis Athb-1 and -2 proteins are characterized by the presence of a homeodomain (HD) with a closely linked leucine zipper motif (Zip). We have suggested that the HD-Zip motif could, via dimerization of the leucine zippers, recognize dyad-symmetric DNA sequences. Here we report an analysis of the DNA binding properties of the Athb-1 homeodomain-leucine zipper (HD-Zip-1) domain in vitro. DNA binding analysis performed using random-sequence DNA templates showed that the HD-Zip-1 domain, but not the Athb-1 HD alone, binds to DNA. The HD-Zip-1 domain recognizes a 9 bp dyad-symmetric sequence [CAAT(A/T)ATTG], as determined by selecting high-affinity binding sites from random-sequence DNA. Gel retardation assays demonstrated that the HD-Zip-1 domain binds to DNA as a dimer. Moreover, the analysis of the DNA binding activity of Athb-1 derivatives indicated that a correct spatial relationship between the HD and the Zip is essential for DNA binding. Finally, we determined that the Athb-2 HD-Zip domain recognizes a distinct 9 bp dyad-symmetric sequence [CAAT(G/C)ATTG]. A model of DNA binding by the HD-Zip proteins is proposed.

Placebo-controlled, double-blind, cross-over trial of glutathione therapy in male infertility.

Abstract: Glutathione therapy was used for 2 months in a placebo-controlled double-blind cross-over trial of 20 infertile patients with dyspermia associated with unilateral varicocele (VAR) or germ-free genital tract inflammation (INF). The patients received either glutathione (group 1) or placebo (group 2) for 2 months, then they crossed over to the alternative treatment for a further 2 months. The patients were randomly and blindly assigned to treatment (one i.m. injection every other day of either 600 mg glutathione or an equal volume of a placebo preparation). The standard semen analysis and the computer-assisted sperm motility analyses were carried out before treatment and during the trial. Statistical cross-over analysis, case-control study and treatment efficacy test were carried out on groups 1 and 2 and differences in the effects of therapy between VAR and INF patients with varicocele or inflammation were tested. Glutathione therapy demonstrated a statistically significant positive effect on sperm motility, in particular on the percentage of forward motility, the kinetic parameters of the computerized analysis and on sperm morphology. The findings of this study indicate that glutathione therapy could represent a possible therapeutical tool for both of the selected andrological pathologies.

The sphericalp-spin interaction spin-glass model

Abstract: The relaxational dynamics for local spin autocorrelations of the sphericalp-spin interaction spin-glass model is studied in the mean field limit. In the high temperature and high external field regime, the dynamics is ergodic and similar to the behaviour in known liquid-glass transition models. In the static limit, we recover the replica symmetric solution for the long time correlation. This phase becomes unstable on a critical line in the (T, h) plane, where critical slowing down is observed with a cross-over to power law decay of the correlation function ∝t−ν, with an exponent ν varying along the critical line. For low temperatures and low fields, ergodicity in phase space is broken. For small fields the transition is discontinuous, and approaching this transition from above, two long time scales are seen to emerge. This dynamical transition lies at a somewhat higher temperature than the one obtained within replica theory. For larger fields the transition becomes continuous at some tricritical point. The low temperature phase with broken ergodicity is studied within a modified equilibrium theory and alternatively for adiabatic cooling across the transition line. This latter scheme yields rather detailed insight into the formation and structure of the ergodic components.

The interatomic structure of water at supercritical temperatures

Abstract: LIQUID water, the medium in which life both began and persists, is in many ways a most unusual fluid. Much is known about the macroscopic properties of the condensed and gaseous states of water, but our understanding of the microscopic forces that define water structure remains incomplete1. This structure, described in terms of correlations between the pairs of atoms O–H, O–O and H–H (ref. 2), can be studied by neutron diffraction techniques involving isotopic substitution3. In particular, the signature of hydrogen bonding is apparent in neutron diffraction experiments as a peak in the pair correlation function of O and H (gOH (r)) at about 1.9 A (refs 3, 4). Here we extend such studies into the supercritical regime of water, in which there is no longer any distinction between the liquid and vapour phases. We find that at the supercritical temperature of 400 °C almost all hydrogen bonding is broken down, even though the thermal energy kBT is considerably less than the energy of the hydrogen bond. Our results are markedly different from the predictions of computer simulations under comparable conditions5 using a common model of water5–7. Our results provide a sensitive test of models of water structure more generally, and give some indication of the environment that solute molecules will experience in extraction and reaction processes that employ supercritical water as a solvent8.

House Mice as Models in Systematic Biology

Abstract: We evaluated the house mouse (Mus musculus species complex) and its laboratory descendents as models for three aspects of systematic biology: hybrid zone biology, chromosomal evolution and speciation, and tests for methods of phylogenetic reconstruction. The taxonomy and genetic relationships of the species in the complex are summarized. The comparative phylogenetic method was used to illucidate biogeographical, ecological, and chromosomal events in the group. Hybridization in house mice was evaluated with respect to the emerging discipline of hybrid zone biology. Inter- and intraspecific contact zones are described and compared. Zone- specific electrophoretic alleles, new metacentric chromosomes, and increased levels of parasitism are explained as consequences of genome disruption

Decidable reasoning in terminological knowledge representation systems

Abstract: Terminological knowledge representation systems (TKRSs) are tools for designing and using knowledge bases that make use of terminological languages (or concept languages). We analyze from a theoretical point of view a TKRS whose capabilities go beyond the ones of presently available TKRSs. The new features studied, often required in practical applications, can be summarized in three main points. First, we consider a highly expressive terminological language, called ALCNR, including general complements of concepts, number restrictions and role conjunction. Second, we allow to express inclusion statements between general concepts, and terminological cycles as a particular case. Third, we prove the decidability of a number of desirable TKRS-deduction services (like satisfiability, subsumption and instance checking) through a sound, complete and terminating calculus for reasoning in ALCNR-knowledge bases. Our calculus extends the general technique of constraint systems. As a byproduct of the proof, we get also the result that inclusion statements in ALCNR can be simulated by terminological cycles, if descriptive semantics is adopted.

Unilateral neglect restricted to visual imagery

Abstract: Disorders in perceiving and exploring the visual space contralateral to a brain lesion have been frequently described. Many patients with hemi-neglect for extrapersonal space also show neglect in a representational domain when the task requires imagining a well-known piazza from a given vantage point or comparing two visual images. Cognitive and psychophysiological studies show a functional parallelism between the perceptual and imaginative domain, indicating that spatial perception and imagery share the same neural substrata. Here we describe a patient with a persistent disorder in visual imagery for familiar piazzas in the absence of any neglect for stimuli located in a far or near space or on his own body. Contrary to previous cases involving imagery disorders, computerized tomography scans showed a lesion confined to the right frontal lobe, suggesting the role of the frontal lobe in some specific types of mental imagery.

Therapy of human hydatid disease with mebendazole and albendazole.

Abstract: We report our experience in the treatment with benzoimidazole carbamates (mebendazole and albendazole) of 337 patients affected by hydatid cysts with different localizations. The treated cysts showed degenerative modifications in 50.6% of the cases after mebendazole treatment and in about 80% after albendazole treatment. Relapses after therapy were observed in 30% of the cases; about 95% of the recurring cysts showed good susceptibility to a further cycle of therapy with benzoimidazole carbamates. Side effects observed with either drug were not severe and always reversible, consisting mainly of abdominal pains and increased levels of transaminases in serum. Among the factors that may influence the therapeutic results are the drug employed, the age of the cysts, the age of the patient, and the localization of the cysts and their morphological characteristics. Moreover, it can be hypothesized that each hydatid cyst has an intrinsic sensitivity to benzoimidazole carbamates.

Thrombospondin related anonymous protein (TRAP) of Plasmodium falciparum binds specifically to sulfated glycoconjugates and to HepG2 hepatoma cells suggesting a role for this molecule in sporozoite invasion of hepatocytes.

Abstract: Thrombospondin related anonymous protein (TRAP) of Plasmodium falciparum contains an amino acid motif based around the sequence WSPCSVTCG which is also found in region II of the circumsporozoite (CS) proteins of different species of Plasmodium. This amino acid motif confers on the CS protein the ability to bind specifically to sulfated glycoconjugates and to hepatocytes. This suggests that the interaction of CS protein with sulfated glycoconjugates on the surface of the hepatocytes may represent the first molecular event of sporozoite invasion of liver cells. Experimental evidence indicates that TRAP is localized both on the micronemes and on the surface of P. falciparum sporozoites implying that TRAP with its putative sulfated glycoconjugate binding motif may also be involved in recognition and/or entry of hepatocytes by the sporozoite. We show here that different TRAP constructs expressed in Escherichia coli bind to sulfogalactosyl-cerebrosides (sulfatides) and to the surface of HepG2 cells. These interactions are dependent on the presence of the conserved amino acid motif WSPCSVTCG within the sequences of the constructs and are completely inhibited by several sulfated glycoconjugates as well as by suramin, a polysulfonated drug with anti-protozoan activity. Moreover, sporozoite invasion of HepG2 cells is inhibited by antisera raised against these different TRAP constructs and by the presence of low concentrations of suramin. We concluded that TRAP may be one of the parasite encoded molecules in the host-parasite interaction that results in sporozoite invasion of hepatocytes.

Representing and using interschema knowledge in cooperative information systems

Abstract: Managing interschema knowledge is an essential task when dealing with cooperative information systems. We propose a logical approach to the problem of both expressing interschema knowledge, and reasoning about it. In particular, we set up a structured representation language for expressing semantic interdependencies between classes belonging to different database schemas, and present a method for reasoning over such. interdependencies. The language and the associated reasoning technique makes it possible to build a logic-based module that can draw useful inferences whenever the need arises of both comparing and combining the knowledge represented in the various schemas. Notable examples of such inferences include checking the coherence of interschema knowledge, and providing integrated access to a cooperative information system.

Ultrastructure of human ovarian primordial follicles after combination chemotherapy for Hodgkin's disease.

Abstract: Ovarian damage, with consequent permanent infertility, is one of the more common side-effects which occurs during chemotherapeutic treatment of patients affected by Hodgkin's disease. This damage is morphologically represented by a marked loss of primordial and primary follicles. The administration of contraceptive drugs before starting chemotherapy enhances survival of a greater number of ovarian follicles, as revealed by morphometric analyses, nevertheless, total ovarian protection is not assured. This study evaluated the number and the morphology of ovarian follicles, by means of transmission electron microscopy, in patients with Hodgkin's disease treated with multi-drug chemotherapeutic protocols following the administration of medroxyprogesterone acetate. Ovarian biopsies were performed prior to any pharmacological treatment, after medroxyprogesterone therapy, and after this therapy plus chemotherapy. Particular attention was given to the ultrastructure of primordial follicles. After morphometric evaluation, primordial follicles were numerous in controls and medroxyprogesterone therapy (28.55 +/- 6.59/mm3 of ovarian cortex). After chemotherapy and medroxyprogesterone acetate, the number of follicles was slightly reduced (19.37 +/- 3.41/mm3 of ovarian cortex) in contrast to the dramatic loss usually observed when protection is not given, although more follicles were atretic. Medroxyprogesterone may protect follicles only from acute, toxic effects of chemotherapy, which dramatically reduce their number and lead to sterility. Nevertheless, the quality of follicles is still impaired, and many undergo atresia, resulting in a shortened fertility period.

An overview of the kinetic parameters of class B beta-lactamases.

Abstract: The catalytic properties of three class B beta-lactamases (from Pseudomonas maltophilia, Aeromonas hydrophila and Bacillus cereus) were studied and compared with those of the Bacteroides fragilis enzyme. The A. hydrophila beta-lactamase exhibited a unique specificity profile and could be considered as a rather specific 'carbapenemase'. No relationships were found between sequence similarities and catalytic properties. The problem of the repartition of class B beta-lactamases into sub-classes is discussed. Improved purification methods were devised for the P. maltophilia and A. hydrophila beta-lactamases including, for the latter enzyme, a very efficient affinity chromatography step on a Zn(2+)-chelate column.

Decidable Reasoning in Terminological Knowledge Representation Systems

Abstract: Terminological knowledge representation systems (TKRSs) are tools for designing and using knowledge bases that make use of terminological languages (or concept languages). We analyze from a theoretical point of view a TKRS whose capabilities go beyond the ones of presently available TKRSs. The new features studied, often required in practical applications, can be summarized in three main points. First, we consider a highly expressive terminological language, called ALCNR, including general complements of concepts, number restrictions and role conjunction. Second, we allow to express inclusion statements between general concepts, and terminological cycles as a particular case. Third, we prove the decidability of a number of desirable TKRS-deduction services (like satisfiability, subsumption and instance checking) through a sound, complete and terminating calculus for reasoning in ALCNR-knowledge bases. Our calculus extends the general technique of constraint systems. As a byproduct of the proof, we get also the result that inclusion statements in ALCNR can be simulated by terminological cycles, if descriptive semantics is adopted.

Left/right and cortical/subcortical dichotomies in the neuropsychological study of human emotions

Abstract: Two main dichotomies have been put forth in the study of the anatomical substrates of emotional behaviour. The first, more classical and more firmly established, claims that the basic brain mechanisms for emotions are located in subcortical rather than in cortical structures. The second, more recent and still more hypothetical dichotomy, maintains that the right and the left hemispheres are not equally involved in emotional behaviour and that the right hemisphere plays a critical role in this regard. It is not clear, however, if these two dichotomies are independent or are somehow interconnected. The aim of this article is to discuss some aspects of the neuropsychology of human emotions, taking into account both the cortical/subcortical and the left/right dichotomy. First, we will review some well-established facts and some more recent models and data concerning the role played by cortical and subcortical structures in various aspects of emotional behaviour. Secondly, we will present a short summ...

The Arabidopsis Athb‐2 and ‐4 genes are strongly induced by far‐red‐rich light

Abstract: The isolation and characterization of the Athb-2 gene, which codes for a HD-Zip protein in Arabidopsis thaliana is reported. Interestingly, Southern analysis has established that the Arabidopsis genome contains sequences which are highly related to the Athb-2 HD-Zip coding region. One of these genes, designated Athb-4, has been cloned and partially sequenced. Amino acid sequence comparison revealed that Athb-2 and -4 are members of a small family of HD-Zip related proteins. Athb-2 mRNA analysis showed that this gene is expressed during the vegetative and reproductive phases of plant growth. A significant increment in the amount of Athb-2 transcripts was observed in flowering plants. A higher steady-state level of the Athb-2 mRNA was also found in dark-adapted plants. Remarkably, far-red-rich light treatment of Arabidopsis plants results in a rapid and strong induction of the Athb-2 expression. This light treatment also induces the accumulation of Athb-4 transcripts, suggesting a similar role for the two members of this HD-Zip family.