Biomedical subjects

G Bernardi

Publications and source records attributed to G Bernardi.

At least 55 records · Page 3Linked to original sources

PubMed2005

Measurement of inclusive differential cross sections for pp collisions at (square root)s = 1.96 TeV.

We present measurements of the inclusive production cross sections of the Gamma(1S) bottomonium state in pp collisions at (square root)s = 1.96 TeV. Using the Gamma(1S) --> mu(+)mu(-) decay mode for a data sample of 159 +/- 10 pb(-1) collected by the D0 detector at the Fermilab Tevatron collider, we determine the differential cross sections as a function of the Gamma(1S) transverse momentum for three ranges of the Gamma(1S) rapidity: 0 < y(Gamma) < or = 0.6, 0.6 < y(Gamma) < or = 1.2, and 1.2 < y(Gamma) < or = 1.8.

Journal Article↗

PubMed2005

Measurement of dijet azimuthal decorrelations at central rapidities in pp collisions at sqrt s =1.96 TeV.

Correlations in the azimuthal angle between the two largest transverse momentum jets have been measured using the D0 detector in p (-)p collisions at a center-of-mass energy sqrt[s]=1.96 TeV. The analysis is based on an inclusive dijet event sample in the central rapidity region corresponding to an integrated luminosity of 150 pb(-1). Azimuthal correlations are stronger at larger transverse momenta. These are well described in perturbative QCD at next-to-leading order in the strong coupling constant, except at large azimuthal differences where contributions with low transverse momentum are significant.

Journal Article↗

PubMed2005

Measurement of the ratio of B+ and B0 meson lifetimes.

The ratio of the B+ and B0 meson lifetimes was measured using data collected in 2002-2004 by the D0 experiment in Run II of the Fermilab Tevatron Collider. These mesons were reconstructed in B-->mu(+)nuD(*-)X decays, which are dominated by B0 and B-->mu(+)nuD 0X decays, which are dominated by B+. The ratio of lifetimes is measured to be tau(+)/tau(0)=1.080+/-0.016(stat)+/-0.014(syst).

Journal Article↗

PubMed2005

Measurement of the ratio of inclusive cross sections sigma(pp --> Z + b jet)/sigma(pp --> Z + jet) at square root(s) = 1.96 TeV.

Using the data collected with the D0 detector at square root(s) = 1.96 TeV, for integrated luminosities of about 180 pb(-1), we have measured the ratio of inclusive cross sections for pp --> Z + b jet to pp --> Z + jet production. The inclusive Z + b-jet reaction is an important background to searches for the Higgs boson in associated ZH production at the Fermilab Tevatron collider. Our measurement is the first of its kind, and relies on the Z --> e+ e- and Z --> mu+ mu- modes. The combined measurement of the ratio yields 0.021+/-0.005 for hadronic jets with transverse momenta pT > 20 GeV/c and pseudorapidities absolute value(eta) < 2.5, consistent with next-to-leading-order predictions of the standard model.

Journal Article↗

PubMed2005

Search for anomalous heavy-flavor quark production in association with W bosons.

We search for anomalous production of heavy-flavor quark jets in association with W bosons at the Fermilab Tevatron pp Collider in final states in which the heavy-flavor quark content is enhanced by requiring at least one tagged jet in an event. Jets are tagged using one algorithm based on semileptonic decays of b/c hadrons, and another on their lifetimes. We compare e+jets (164 pb(-1)) and mu+jets (145 pb(-1)) channels collected with the D0 detector at sqrt[s]=1.96 TeV to expectations from the standard model and set upper limits on anomalous production of such events.

Journal Article↗

PubMed2005

Measurement of the WW production cross section in pp collisions at square root[s]=1.96 TeV.

We present a measurement of the W boson pair-production cross section in pp collisions at a center-of-mass energy of sqrt[s]=1.96 TeV. The data, collected with the Run II D0 detector at Fermilab, correspond to an integrated luminosity of 224-252 pb(-1) depending on the final state (ee, emu, or mumu). We observe 25 candidates with a background expectation of 8.1+/-0.6(stat)+/-0.6(syst)+/-0.5(lum) events. The probability for an upward fluctuation of the background to produce the observed signal is 2.3x10(-7), equivalent to 5.2 standard deviations. The measurement yields a cross section of 13.8(+4.3)(-3.8)(stat)+1.2-0.9(syst)+/-0.9(lum) pb, in agreement with predictions from the standard model.

Journal Article↗

PubMed2005

Measurement of the Lambda0b lifetime in the decay lambda0b--> J/psiLambda0 with the D0 detector.

We present measurements of the Lambda(0)(b) lifetime in the exclusive decay channel Lambda(0)(b)--> J/psiLambda(0), with J/psi--> mu(+)mu(-) and Lambda(0)--> ppi(-), the B0 lifetime in the decay B0-->J/psiK(0)(S) with J/psi--> mu(+)mu(-) and K(0)(S)-->pi(+)pi(-), and the ratio of these lifetimes. The analysis is based on approximately 250 pb(-1) of data recorded with the D0 detector in pp collisions at sqrt[s] = 1.96 TeV. The Lambda(0)(b) lifetime is determined to be tau(Lambda(0)(b)) = 1.22(+0.22)(-0.18)(stat) +/- 0.04(syst) ps, the B0 lifetime tau(B0) = 1.40(+0.11)(-0.10)(stat) +/- 0.03(syst) ps, and the ratio tau(Lambda(0)(b))/tau(B0) = 0.87(+0.17)(-0.14)(stat) +/- 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda(0)(b) lifetime based on a fully reconstructed decay channel.

Journal Article↗

PubMed2005

Search for Wbb and WH production in pp collisions at square root [s]=1.96 TeV.

We present a search for Wbb production in pp collisions at sqrt[s]=1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb(-1) of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on Wbb production of 6.6 pb for b quarks with transverse momenta p(b)(T)>20 GeV and bb separation in pseudorapidity-azimuth space DeltaR(bb)>0.75. Restricting the search to optimized bb mass intervals provides upper limits on WH production of 9.0-12.2 pb for Higgs-boson masses of 105-135 GeV.

Journal Article↗

PubMed2005

Search for the flavor-changing neutral current decay B0s--> mu(+) mu(-) in pp Collisions at sqrt[s] = 1.96 TeV with the D0 detector.

We present the results of a search for the flavor-changing neutral current decay B(0)(s)--> mu(+) mu(-) using a data set with integrated luminosity of 240 pb(-1) of pp collisions at sqrt[s] = 1.96 TeV collected with the D0 detector in run II of the Fermilab Tevatron collider. We find the upper limit on the branching fraction to be B(B(0)(s)--> mu(+) mu(-)) < or= 5.0 x 10(-7) at the 95% C.L. assuming no contributions from the decay B(0)(d)--> mu(+) mu(-) in the signal region. This limit is the most stringent upper bound on the branching fraction B(0)(s)--> mu(+) mu(-) to date.

Journal Article↗

PubMed2005

Measurement of the B0s lifetime in the exclusive decay channel B0s-->J/psiphi.

Using the exclusive decay B0s-->J/psi(mu+mu-)phi(K+K-), we report the most precise single measurement of the B0s lifetime. The data sample corresponds to an integrated luminosity of approximately 220 pb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2004. We reconstruct 337 signal candidates, from which we extract the B0s lifetime, tau(B0s)=1.444(+0.098)(-0.090)(stat)+/-0.020(sys) ps. We also report a measurement for the lifetime of the B0 meson using the exclusive decay B0-->J/psi(mu+mu-)K*0(892)(K+pi-). We reconstruct 1370 signal candidates, obtaining tau(B0)=1.473(+0.052)(-0.050)(stat)+/-0.023(sys) ps, and the ratio of lifetimes, tau(B0s)/tau(B0)=0.980(+0.076)(-0.071)(stat)+/-0.003(sys).

Journal Article↗

PubMed2005

Search for supersymmetry with gauge-mediated breaking in diphoton events at D0.

We report the results of a search for supersymmetry (SUSY) with gauge-mediated breaking in the missing transverse energy distribution of inclusive diphoton events using 263 pb(-1) of data collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2004. No excess is observed above the background expected from standard model processes, and lower limits on the masses of the lightest neutralino and chargino of about 108 and 195 GeV, respectively, are set at the 95% confidence level. These are the most stringent limits to date for models with gauge-mediated SUSY breaking with a short-lived neutralino as the next-to-lightest SUSY particle.

Journal Article↗

PubMed2005

Starc II, a multicenter randomized placebo-controlled double-blind clinical trial of trapidil for 1-year clinical events and angiographic restenosis reduction after coronary angioplasty and stenting.

The objective of this study was to investigate the effect of trapidil 200 mg t.i.d. in preventing the occurrence of death, of myocardial infarction and the need for repeat revascularization at 12 months after balloon PTCA with or without stenting. Coronary restenosis after stenting is still a major drawback of percutaneous coronary interventions (PCI) for 30-40% of patients. Trapidil has been shown to prevent restenosis after PTCA. Eligible patients were randomized to placebo or oral trapidil 200 mg t.i.d. at least 48 hr before PCI and continuing 6 months after a successful balloon angioplasty or stent implantation. Aspirin was given to all patients, and ticlopidine 250 mg b.i.d. to those who received a stent for 4 weeks. In a randomized subgroup of 216 patients, quantitative coronary angiography was performed also at 6-month follow-up. Out of the 933 patients enrolled, primary endpoint incidence was 20.3% in trapidil and 18.0% in placebo (P = 0.37). When recurrence or deterioration of angina was added to the combined endpoint, incidence was 27.4% in trapidil and 23.0% in placebo (P = 0.12). Restenosis rate in patients with 6-month angiography was 25.0% in trapidil arm vs. 30.1% in placebo (P = 0.43). Stent restenosis rate was similar in patients randomized to trapidil or placebo (30.2% vs. 23.8%, respectively; P = 0.44), while in patients treated with balloon angioplasty, it was lower in trapidil (17.1%) than in placebo (40.0%; P = 0.03). Oral trapidil 200 mg t.i.d. for 6 months in addition to aspirin did not influence the occurrence of major cardiac events after coronary angioplasty with or without stenting. In a prespecified subgroup of 191 patients treated with balloon angioplasty only, trapidil reduced angiographic restenosis.

Angioplasty, Balloon, Coronary↗

PubMed2005

Subacute demyelinating polyneuropathy in B-cell lymphoma with IgM antibodies against glycolipid GD1b.

Peripheral neuropathy associated with IgM monoclonal gammopathy of unknown significance is a common disorder, while the association of paraproteinaemic neuropathies with haematological malignancies is far less frequent. We report a 76-year-old patient with a subacute and rapidly progressive sensorimotor demyelinating polyneuropathy causing sensory ataxia, painful paraesthesias and marked motor and sensory deficit in four limbs. Monoclonal gammopathy of IgM type associated with a rectal low-grade B-cell non-Hodgkin lymphoma was detected. Research for anti-MAG and antiganglioside autoantibodies including anti-GM1 and anti-GQ1b evidenced a high titre of IgM antibodies against the disialosyl group of GD1b. This is the first report on a paraproteinaemic polyneuropathy with IgM autoantibodies against glycolipid GD1b associated with B-cell lymphoma. The IgM type of these autoantibodies suggests that they represent all or part of the paraprotein produced by lymphoma cells.

Aged↗

PubMed2005

Modulatory action of metabotropic glutamate receptor (mGluR) 5 on mGluR1 function in striatal cholinergic interneurons.

Within basal ganglia, group I metabotropic glutamate receptor subtypes (mGluR1 and 5) frequently co-localize in the same neuron. However, little is known about how these receptors functionally interact. We addressed this issue by means of electrophysiological recordings of striatal cholinergic interneurons, a neuronal subtype that co-express both group I mGluRs. The group I non-selective agonist 3,5-DHPG induced a membrane depolarization/inward current that was prevented by co-application of LY 367385, a selective mGluR1 antagonist, and SIB 1757 or MPEP, blockers of mGluR5 subtype. The reversal potential for the response to 3,5-DHPG was close to the equilibrium potential for potassium channels. Repeated bath or focal applications of 3,5-DHPG induced a progressive decline in the amplitude of the membrane depolarization, suggesting that group I mGluRs undergo receptor desensitization. Interestingly, in the presence of the mGluR5 blocker, SIB 1757, this event was not observed, whereas it occurred in LY 367385. PKC blockers chelerythrine and calphostin C mimicked the inhibitory effect of SIB 1757. In a subset of interneurons, in MPEP or SIB 1757, 3,5-DHPG induced a 0.5-1 Hz oscillatory response, that was prevented by L-type Ca2+ channel blockers, and by the tyrosine kinase inhibitors genistein and lavendustin. Together, these data suggest that mGluR5 modulates mGluR1 activity to shape cell excitability.

Acetylcholine↗

PubMed2005

Long-term potentiation and memory processes in the psychological works of Sigmund Freud and in the formation of neuropsychiatric symptoms.

Far from disproving the model of mind functioning proposed by psychoanalysis, the recent advances in neuropsychiatrical research confirmed the crucial ideas of Sigmund Freud. The hypothesis that the origin of mental illnesses lies in the impossibility for a subject to erase the long-term effects of a remote adverse event is in tune with the view that several psychiatric disturbances reflect the activation of aberrant unconscious memory processes. Freud's insights did not stop here, but went on to describe in an extremely precise manner the neural mechanisms of memory formation almost a century before the description of long-term synaptic potentiation.

Humans↗

PubMed2005

Subthalamic nucleus lesion reverses motor abnormalities and striatal glutamatergic overactivity in experimental parkinsonism.

Subthalamic nucleus (STN) is a target of choice for the neurosurgical treatment of Parkinson's disease (PD). The therapeutic effect of STN lesion in PD is classically ascribed to the rescue of physiological activity in the output structures of the basal ganglia, and little is known about the possible involvement of the striatum. In the present study, therefore, we electrophysiologically recorded in vitro single striatal neurons of DA-depleted rats unilaterally lesioned by 6-hydroxydopamine, treated or not with therapeutic doses of levodopa (l-DOPA), or with a consecutive ipsilateral STN lesion. We show that the beneficial motor effects produced in parkinsonian rats by STN lesion or l-DOPA therapy were paralleled by the normalization of overactive frequency and amplitude of striatal glutamate-mediated spontaneous excitatory postsynaptic currents (sEPSCs). Since neither l-DOPA treatment nor STN lesion affected sEPSCs kinetic properties, the reversal of these abnormalities in striatal excitatory synaptic transmission can be attributable to the normalization of glutamate release.

Animals↗

PubMed2005

CSF from MS patients can induce acute conduction block in the isolated optic nerve.

In the present in vitro electrophysiological study, the acute effects of the cerebrospinal fluid (CSF) from multiple sclerosis (MS) and control subjects were measured on the axonal conduction of rat optic nerve, a central tract that is commonly affected in MS. Optic nerve compound action potential (CAP) amplitude was insensitive to the application of CSF obtained from the whole population of non-MS patients and from seven of 15 MS CSF. In the remaining eight MS cases, conversely, a time-dependent depression of CAP amplitude was observed. The reversible blockade of ion channels by soluble substances might account, at least in part, for the transient symptoms often seen in MS patients.

Adolescent↗

PubMed2005

Temporal lobe epileptic activity mimicking dementia: a case report.

Epileptic activity is an underdiagnosed cause that can determine a disruption of memory and cognitive performance, leading an incorrect diagnosis of dementia. We report a 68-year-old man, referred with a 5-year history of subtle behavioral changes and a subjective memory impairment, who was admitted to our department because of recurrent episodes of confusional state lasting from 1 week. Neuropsychological evaluation demonstrated a marked impairment of all cognitive domains examined. Electroencephalogram (EEG) recording showed frequent almost continuous sharp waves localized on the bilateral posterior temporal regions with mild right side predominance. Treatment with phenytoin reversed his cognitive dysfunction and behavioral disturbances. We presume that ictal temporal lobe epileptiform activity is the cause of his confusional episodes and cognitive dysfunction, showing an electroclinical picture of complex partial status epilepticus. However, we hypothesize that the interictal discharges and ictal and postictal effects of subclinical seizures could be involved in the behavioral changes and memory impairment complained by our patient in the last years.

Aged↗