Showing papers by "University of Milano-Bicocca published in 2003"

The role of age of acquisition and language usage in early, high-proficient bilinguals: an fMRI study during verbal fluency

Abstract: We assessed the effects of age of acquisition and language exposure on the cerebral correlates of lexical retrieval in high-proficient, early-acquisition bilinguals. Functional MRI was used to study Spanish-Catalan bilinguals who acquired either Spanish or Catalan as a first language in the first years of life. Subjects were exposed to the second language at 3 years of age, and have used both languages in daily life since then. Subjects had a comparable level of proficiency in the comprehension of both languages. Lexical retrieval with the verbal fluency task resulted in the well-established pattern of left hemispheric activation centered on the inferior frontal region. The effect of age of acquisition was assessed by dividing the subjects into two groups, on the basis of the language acquired first (Catalan-born or Spanish-born bilinguals). Functional comparisons indicated that less extensive brain activation was associated with lexical retrieval in the language acquired earlier in life. The two groups were also different in language usage/exposure, as assessed with a specific questionnaire; in particular, the exposure to the second language (Spanish) was less intensive in the case of Catalans. This was reflected in a significant interaction, indicating a more extensive activation in Catalans during production in Spanish. Overall, these results indicate that, during a production task, both age of acquisition and language exposure affect the pattern of brain activation in bilinguals, even if both languages are acquired early and with a comparable level of proficiency.

Image annotation using SVM

Abstract: The paper describes an innovative image annotation tool for classifying image regions in one of seven classes - sky, skin, vegetation, snow, water, ground, and buildings - or as unknown. This tool could be productively applied in the management of large image and video databases where a considerable volume of images/frames there must be automatically indexed. The annotation is performed by a classification system based on a multi-class Support Vector Machine. Experimental results on a test set of 200 images are reported and discussed.

A classification of metamorphic grains in sands based on their composition and grade

Abstract: An operational classification of metamorphic grains in sands and sandstones is proposed with the aim of enhancing data reproducibility among operators and the potential of high-resolution bulk petrography in provenance studies. For each of four protolith compositions (metapelite, metapsammite/metafelsite, metacarbonate, metabasite), six archetype grains displaying increasing degree of recrystallization and foliation development are illustrated. Such a classification grid is specifically devised as a subsidiary tool for point counting with the Gazzi-Dickinson method. Traditional QFR parameters can also be easily recalculated from the data set obtained, thus meeting all possible needs (Decker and Helmold 1985; Suttner and Basu 1985). An experiment shows that usage of visual-comparison standards effectively minimizes operator variation and allows retrieval of crucial information during point counting in a reproducible way. A petrogenetic grid is presented as a subsidiary tool for classifying grains that include index minerals and to help correlation with dense-mineral data. The "metamorphic index" (MI) is introduced as an estimator of average metamorphic grade of source rocks. Our classification, an extension of concepts used first in the study of arc-continent collision in Taiwan (Dorsey 1988) and successfully expanded to interpret the evolution of continent-continent collision in the Himalayas (Najman and Garzanti 2000; White et al. 2002), proves to be fruitful in provenance analysis of foreland-basin sediments shed from Alpine-type, thick-skinned collision orogens, particularly when integrated with dense-mineral, geochemical, and geochronological data.

Evidence of a secondary grapevine domestication centre detected by SSR analysis.

Abstract: The origin of the grapevine was investigated with archaeobotanical, cultural and historical data. A primary domestication centre was located in the Near East region but there is no agreement on the existence or role of secondary domestication centres. In this work, PCR-based microsatellite analysis has been applied to study the origin of some Italian cultivated grapevines from in situ direct domestication of the wild autoctonous grapevine. Three different Italian locations in Grosseto, Cosenza and Nuoro were identified for this study, and domesticated grapevine as well as wild local accessions growing in these location, were analysed by SSR markers. Cluster analysis performed on Cosenza and Grosseto samples showed a high value of genetic distance between domesticated and wild accessions. On the contrary two cultivars (Bovale Murru and Bovale Muristellu) recovered in Nuoro (in the Sardinia island) were very close to some wild varieties. This suggests that the latter two cultivars may have originated from wild grapevines and consequently that in this location a secondary grapevine domestication event occurred. Six Lambrusco varieties were also included in this analysis as ancient putative ancestors of the cultivated grapevines. The molecular analysis excluded this hypothesis and suggest Lambrusco as an independent Vitis taxon.

Evidence for supernova signatures in the spectrum of the late-time bump of the optical afterglow of GRB 021211

Abstract: We present photometric and spectroscopic observations of the gamma-ray burst GRB 021211 obtained during the late stages of its afterglow. The light curve shows a rebrightening occurring ∼25 days after the GRB. The analysis of a VLT spectrum obtained during the bump (27 days after the GRB) reveals a suggestive resemblance with the spectrum of the prototypical type-Ic SN 1994I, obtained ∼10 days past maximum light. Particularly we have measured a strong, broad absorption feature at 3770 A, which we have identified with Ca II blueshifted by ∼14 400 km s −1 , thus indicating that a supernova (SN) component is indeed powering the "bump" in the afterglow decay. Assuming SN 1994I as a template, the spectroscopic and photometric data together indicate that the SN and GRB explosions were at most separated by a few days. Our results suggest that GRBs might be associated also to standard type-Ic supernovae.

The cognitive electrophysiology of mind and brain

Abstract: Publisher Summary The event-related potentials (ERPs) of the brain are wave forms reflecting brain voltage fluctuations in time. This chapter highlights cognitive electrophysiology as a well-established field of science. The main assumption of cognitively oriented electrophysiological research is that cognition is implemented in the brain through physiological changes. Traditionally, for more than 100 years, cognitive and neurophysiological processes in humans have been studied by psychophysical and behavioral methods. The difficulty in differentiating cognition from brain localization is not, however, unique to neuroimaging and electrophysiological studies.

Early IL-2 Production by Mouse Dendritic Cells Is the Result of Microbial-Induced Priming

Abstract: Dendritic cells (DCs) are professional APCs able to initiate innate and adaptive immune responses against invading pathogens Different properties such as the efficient Ag processing machinery, the high levels of expression of costimulatory molecules and peptide-MHC complexes, and the production of cytokines contribute in making DCs potent stimulators of naive T cell responses Recently we have observed that DCs are able to produce IL-2 following bacterial stimulation, and we have demonstrated that this particular cytokine is a key molecule conferring to early bacterial activated DCs unique T cell priming capacity In the present study we show that many different microbial stimuli, but not inflammatory cytokines, are able to stimulate DCs to produce IL-2, indicating that DCs can distinguish a cytokine-mediated inflammatory process from the actual presence of an infection The capacity to produce IL-2 following a microbial stimuli encounter is a feature shared by diverse DC subtypes in vivo, such as CD8α + and CD8α − splenic DCs and epidermal Langerhans cells When early activated DCs interact with T cells, IL-2 produced by DCs is enriched at the site of cell-cell contact, confirming the importance of DCs-derived IL-2 in T cell activation

A distinctive example of the cooperative interplay of structure and environment in tuning of intramolecular charge transfer in second-order nonlinear optical chromophores.

Abstract: The strongly enhanced coop- erative influence of medium polarity and organic structural design on the first hyperpolarizability of a novel family of highly polarizable azinium-(CHCH- thienyl)-dicyanomethanido chromo- phores 1 ± 3 is described. The dyes can be efficiently synthesized by regioselec- tive protonation/alkylation of the corre- sponding bidentate anion precursors. Consecutive annelation of the pyridyl ring of 1 (pyridine quinoline acri- dine) and medium polarity effects are responsible for an extraordinarily varia- ble range of intramolecular charge transfer (ICT), leading to a large set of -electron distribution patterns. Ac- cordingly, systems with remarkably dif- ferent zwitterionic/quinoid character in the ground and excited states present values in a broad range, eventually switching from negative to positive. Our investigation is based on a combi- nation of experimental (UV/Vis spec- troscopy, multinuclear NMR spectrosco- py, and electrooptical absorption meas- urements) and computational (ab initio) approaches. It is shown that: 1) and are dramatically influenced, even by orders of magnitude, by a complex, non-monotonic interplay of structure and medium action, which in turn affects molecular ICT and bond length alterna- tion (BLA), 2) the computations, vali- dated by different experimental data, are to be recommended as an extremely useful tool in the search for a greatly improved set of molecular nonlinear optical (NLO) responses (in the case of 1 ± 3 they show that such conditions may be attained only in a narrow and limited range of dielectric constants in which the annelation effect operates most effi- ciently), and 3) the search for the most favorable molecular NLO response of a highly polarizable chromophore both in solution and in solid matrices should simultaneously take into account not only the molecular design supplemented by annelation effects but also the polar- ity of the medium.

Heavy metal tolerance and accumulation of Cd, Cr and Ni by Cannabis sativa L

Abstract: Experiments in semi-natural conditions were undertaken to assess hemp metal tolerance and its ability to accumulate cadmium, nickel and chromium Cannabis sativa was grown in two soils, S1 and S2, containing 27, 74, 126 and 82, 115, 139 μg g−1 of Cd, Ni and Cr, respectively After two months from germination and at ripeness, no significant alteration in plant growth or morphology was detected On the contrary, a high hemp reactivity to heavy metal stress with an increase in phytochelatin and DNA content was observed during development, suggesting the Cannabis sativa ability to avoid cell damage by activating different molecular mechanisms Metals were preferentially accumulated in the roots and only partially translocated to the above-ground tissues The mean shoot Cd content was 14 and 66 μg g−1 for S1 and S2 soil, respectively Although not negligible concentrations they were about 100 times lower than those calculated for the hyperaccumulator Thlaspi caerulescens Similarly Ni uptake was limited if compared with that of the Ni-hyperaccumulator Alyssum murale Chromium uptake was negligible As expected on the base of the metal concentration detected in ripe plants, no statistically significant variation in soil metal content was detected after one crop of hemp Nevertheless, a consistent amount (g) of Cd and Ni is expected to be extracted by 1 ha biomass of hemp (about 10 t) per year and along the time a slow restoration of deeper soil portions can be obtained by its wide root system (at least 0,5 m deep) In addition, the possibilities of growing hemp easily in different climates and using its biomass in non-food industries can make heavy metal contaminated soils productive This means economical advantage along with a better quality of soil

High-Density Lipoproteins Protect Isolated Rat Hearts From Ischemia-Reperfusion Injury by Reducing Cardiac Tumor Necrosis Factor-α Content and Enhancing Prostaglandin Release

Abstract: The incidence and severity of primary cardiac events are inversely related to the plasma concentration of high-density lipoproteins (HDLs). We investigated whether HDLs may exert a direct cardioprotection in buffer-perfused isolated rat hearts, which underwent a 20-minute low-flow ischemia followed by a 30-minute reperfusion. The administration of HDLs at physiological concentrations (0.5 and 1.0 mg/mL) during the 10 minutes immediately before ischemia rapidly and remarkably improved postischemic functional recovery and decreased creatine kinase release in the coronary effluent. Reconstituted HDLs containing apolipoprotein A-I (apoA-I) and phosphatidylcholine, but not lipid-free apoA-I or phosphatidylcholine liposomes, were also effective in protecting the heart from ischemia-reperfusion injury. HDLs at reperfusion were less effective than when given before ischemia. HDLs caused a dose-dependent reduction of ischemia-induced cardiac tumor necrosis factor-alpha (TNF-alpha) expression and content, which correlated with the improved functional recovery. A parallel increase of TNF-alpha release in the coronary effluent was observed, due to a direct binding of cardiac TNF-alpha to HDLs. Taken together, these findings argue for a cause-effect relationship between the HDL-mediated removal of TNF-alpha from the ischemic myocardium and the HDL-induced cardioprotection. Indeed, etanercept, a recombinant TNF-alpha-blocking protein, caused a dose-dependent improvement of postischemic functional recovery. HDLs also enhanced ischemia-induced prostaglandin release, which may contribute to the cardioprotective effect. A low plasma HDL level may expose the heart to excessive ischemia-reperfusion damage, and HDL-targeted therapies may be helpful to induce immediate or delayed myocardial protection from ischemia-reperfusion injury.

Oxytocin receptor elicits different EGFR/MAPK activation patterns depending on its localization in caveolin-1 enriched domains.

Abstract: We have recently shown that oxytocin inhibits cell proliferation when the vast majority of oxytocin receptors are excluded from caveolin-1-enriched microdomains, and that, on the contrary, it has a mitogenic effect when the receptors are targeted to these plasma membrane domains. In this study, we investigated whether the receptors located inside and outside caveolar microdomains initiate different signalling pathways and how this may lead to opposite effects on cell proliferation. Our data indicate that, depending on their localization, oxytocin receptors transactivate EGFR and activate ERK1/2 using different signalling intermediates. The final outcome is a different temporal pattern of EGFR and ERK1/2 phosphorylation, which is more persistent when the receptors are located outside caveolar microdomains and inhibit cell growth, and very transient when they are located in caveolar microdomains and stimulate cell growth. Finally, only the activation of receptors located outside caveolar microdomains correlates with the activation of the cell cycle inhibitor p21(WAF1/CIP1), thus suggesting that the antiproliferative OTR effects may, in this case, be achieved by a sustained activation of EGFR and MAPK leading to the induction of this cell cycle regulator.

A critical role for Syk protein tyrosine kinase in Fc receptor-mediated antigen presentation and induction of dendritic cell maturation.

Abstract: Dendritic cells (DCs) are the only APCs capable of initiating adaptive immune responses. The initiation of immune responses requires that DCs 1) internalize and present Ags; and 2) undergo a differentiation process, called "maturation", which transforms DCs into efficient APCs. DC maturation may be initiated by the engagement of different surface receptors, including certain cytokine receptors (such as TNFR), Toll-like receptors, CD40, and FcRs. The early activation events that link receptor engagement and DC maturation are not well characterized. We found that FcR engagement by immune complexes induced the phosphorylation of Syk, a protein tyrosine kinase acting immediately downstream of FcRs. Syk was dispensable for DC differentiation in vitro and in vivo, but was strictly required for immune complexes internalization and subsequent Ag presentation to T lymphocytes. Importantly, Syk was also required for the induction of DC maturation and IL-12 production after FcR engagement, but not after engagement of other surface receptors, such as TNFR or Toll-like receptors. Therefore, protein tyrosine phosphorylation by Syk represents a novel pathway for the induction of DC maturation.

The role of blood pressure variability in end-organ damage.

Abstract: The ultimate goal when treating high blood pressure is to reduce the incidence of end-organ damage and prevent cardiovascular disease, and thus reduce the incidence of premature death. Cuff blood pressure measurements have some prognostic value and have traditionally been used to predict the risk of end-organ damage. Such measurements, however, do not reflect accurately the 24-h mean blood pressure and hourly variations. For any value of cuff blood pressure, a lower 24-h mean blood pressure was associated with a lower prevalence and severity of end-organ damage. In the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study, data from 24-h ambulatory blood pressure monitoring (ABPM) were more strongly associated with prognosis than other blood pressure data. Longitudinal evidence of the clinical relevance of 24-h ABPM data in predicting cardiovascular risk is less extensive. However, results from the Study on Ambulatory Monitoring of Pressure and Lisinopril Evaluation (SAMPLE) trial show the superiority of mean 24-h, daytime and night-time blood pressures over clinic readings in predicting the regression of left ventricular mass index in treated hypertensive patients. Furthermore, a direct, positive relationship has been established between 24-h blood pressure variability and the severity and rate of progression of end-organ damage. In addition, ABPM data demonstrate that hypertensive patients who do not exhibit a nocturnal reduction in blood pressure have a higher incidence of end-organ damage. Future directions for research and treatment of hypertension will need to consider the circadian cycle of blood pressure, the effect of treatment on blood pressure variability, and the magnitude of blood pressure changes in daily life.

Head helmet versus face mask for non-invasive continuous positive airway pressure: a physiological study

Abstract: To assess selected physiological effects of non-invasive continuous positive airway pressure delivered by head helmet (CPAPH), a special interface device designed to completely contain the head of the patient, compared to face mask (CPAPM). Randomized physiological study. University research laboratory. Eight healthy volunteers. Continuous positive airway pressure delivered by face mask and CPAPH in random order. Three gas flow rates (20-30-40 l/min and 30-45-60 l/min, respectively, for CPAPM and CPAPH) and four CPAP levels (0-5-10-15 cmH2O) were employed in a randomized sequence. In each patient we monitored airway pressure, esophageal pressure, expiratory flow, and inspiratory and expiratory CO2 concentration. End-expiratory lung volume changes from CPAP 0 were measured by inductance plethysmography. The application of increased levels of CPAP resulted in a significant increase in end-expiratory lung volume, similar for CPAPH and CPAPM. Inspiratory changes of airway pressure were comparable for the two CPAP modes. Inspiratory CO2 concentration was higher during CPAPH (significantly decreased at increased gas flow rates), compared to CPAPM. Continuous positive airway pressure delivered by head helmet is as effective as CPAPM in increasing end-expiratory lung volume and in compensating for airway pressure changes without the need of a reservoir bag. Higher gas flow rates are necessary to maintain a relatively low inspiratory CO2 concentration.

The Haplotyping problem: an overview of computational models and solutions

Abstract: The investigation of genetic differences among humans has given evidence that mutations in DNA sequences are responsible for some genetic diseases. The most common mutation is the one that involves only a single nucleotide of the DNA sequence, which is called a single nucleotide polymorphism (SNP). As a consequence, computing a complete map of all SNPs occurring in the human populations is one of the primary goals of recent studies in human genomics. The construction of such a map requires to determine the DNA sequences that from all chromosomes. In diploid organisms like humans, each chromosome consists of two sequences called haplotypes. Distinguishing the information contained in both haplotypes when analyzing chromosome sequences poses several new computational issues which collectively form a new emerging topic of Computational Biology known as Haplotyping.This paper is a comprehensive study of some new combinatorial approaches proposed in this research area and it mainly focuses on the formulations and algorithmic solutions of some basic biological problems. Three statistical approaches are briefly discussed at the end of the paper.

'Advanced' generation lentiviruses as efficient vectors for cardiomyocyte gene transduction in vitro and in vivo.

Abstract: Efficient gene transduction in cardiomyocytes is a task that can be accomplished only by viral vectors. Up to now, the most commonly used vectors for this purpose have been adenoviral-derived ones. Recently, it has been demonstrated that lentiviral vectors can transduce growth-arrested cells, such as hematopoietic stem cells. Moreover, a modified form of lentiviral vector (the 'advanced' generation), containing an mRNA-stabilizer sequence and a nuclear import sequence, has been shown to significantly improve gene transduction in growth-arrested cells as compared to the third-generation vector. Therefore, we tested whether the 'advanced' generation lentivirus is capable of infecting and transducing cardiomyocytes both in vitro and in vivo, comparing efficacy in vitro against the third-generation of the same vector. Here we report that 'advanced' generation lentiviral vectors infected most (>80%) cardiomyocytes in culture, as demonstrated by immunofluorescence and FACS analyses: in contrast the percentage of cardiomyocytes infected by third-generation lentivirus was three- to four-fold lower. Moreover, 'advanced' generation lentivirus was also capable of infecting and inducing stable gene expression in adult myocardium in vivo. Thus, 'advanced' generation lentiviral vectors can be used for both in vitro and in vivo gene expression studies in the cardiomyocyte.

A functional-anatomical model for lipreading.

Abstract: Regional cerebral blood flow (rCBF) PET scans were used to study the physiological bases of lipreading, a natural skill of extracting language from mouth movements, which contributes to speech perception in everyday life. Viewing connected mouth movements that could not be lexically identified and that evoke perception of isolated speech sounds (nonlexical lipreading) was associated with bilateral activation of the auditory association cortex around Wernicke's area, of left dorsal premotor cortex, and left opercular-premotor division of the left inferior frontal gyrus (Broca's area). The supplementary motor area was active as well. These areas have all been implicated in phonological processing, speech and mouth motor planning, and execution. In addition, nonlexical lipreading also differentially activated visual motion areas. Lexical access through lipreading was associated with a similar pattern of activation and with additional foci in ventral- and dorsolateral prefrontal cortex bilaterally and in left inferior parietal cortex. Linear regression analysis of cerebral blood flow and proficiency for lexical lipreading further clarified the role of these areas in gaining access to language through lipreading. The results suggest cortical activation circuits for lipreading from action representations that may differentiate lexical access from nonlexical processes.

Prosodic structure and syntactic acquisition: the case of the head-direction parameter

Abstract: We propose that infants may learn about the relative order of heads and complements in their language before they know many words, on the basis of prosodic information (relative prominence within phonological phrases). We present experimental evidence that 6‐12-week-old infants can discriminate two languages that differ in their head direction and its prosodic correlate, but have otherwise similar phonological properties (i.e. French and Turkish). This result supports the hypothesis that infants may use this kind of prosodic information to bootstrap their acquisition of word order.

Monitoring of apoptosis of HL60 cells by Fourier-transform infrared spectroscopy

Abstract: Fourier-transform infrared (FTIR) spectroscopy is a vibrational technique that gives information on the chemical composition of a sample, providing a "molecular fingerprint" of it. It is a powerful approach to study intact cells. The aim of the present study was to analyse and quantify apoptotic cells by using a FTIR approach based on attenuated total reflection (ATR). We incubated human HL60 leukaemic cells with camptothecin, a cytotoxic drug, and monitored apoptosis induction over a period of time. Several ATR-FTIR spectral changes occurred during the apoptotic process. In particular, we observed that the apoptotic index was inversely correlated with the spectral area in the region 1200-900 cm(-1), assigned to the absorption of nucleic acids. We therefore propose that ATR-FTIR spectral features may be used as a diagnostic marker of apoptotic cells.

Hypersaline nasal irrigation in children with symptomatic seasonal allergic rhinitis: a randomized study.

Abstract: Recent evidence suggests that nasal irrigation with hypertonic saline may be useful as an adjunctive treatment modality in the management of many sinonasal diseases. However, no previous studies have investigated the efficacy of this regimen in the prevention of seasonal allergic rhinitis-related symptoms in the pediatric patient. Twenty children with seasonal allergic rhinitis to Parietaria were enrolled in the study. Ten children were randomized to receive three-times daily nasal irrigation with hypertonic saline for the entire pollen season, which had lasted 6 weeks. Ten patients were allocated to receive no nasal irrigation and were used as controls. A mean daily rhinitis score based on the presence of nasal itching, rhinorrea, nasal obstruction and sneezing was calculated for each week of the pollen season. Moreover, patients were allowed to use oral antihistamines when required and the mean number of drug assumption per week was also calculated. In patients allocated to nasal irrigation, the mean daily rhinitis score was reduced during 5 weeks of the study period. This reduction was statistically significantly different in the 3th, 4th and 5th week of therapy. Moreover, a decreased consumption of oral antihistamines was observed in these patients. This effect became evident after the second week of treatment and resulted in statistically significant differences during the 3th, 4th and 6th week. This study supports the use of nasal irrigation with hypertonic saline in the pediatric patient with seasonal allergic rhinitis during the pollen season. This treatment was tolerable, inexpensive and effective.