107 research outputs found
Different Allele Frequency between Males and Females of a SNP of the Human Beta T Cell Receptor
We studied a single nucleotide polymorphism (SNP) located in the human beta T-cell
receptor, in association studies and different allele frequency in the two sexes. Here we
report a new series of 200 subjects (100 males and 100 females) in a restricted age
range, 20-30 years.
We found the following results: in males 57/100 (57%) were heterozygous, 26/100
(26%) were homozygous for the two digestion fragments and 17/100 (17%) were
homozygous for the 603bp fragment. Females were 44/100 (44%) heterozygous, 24/100
(24%) homozygous for the two digestion fragments and 32/100 (32%) homozygous for
the 603bp fragment. The allele frequency was significantly different according to chi
square analysis (X square statistic (df = 2) = 7.412; p = 0.025). Our study shows that in females, but not in males , there is a significant increase of CC homozygous status and a
proportionate decrease of heterozygous status compared with Hardy-Weinberg
expectations.
This study could explain the controversial results obtained by association studies
between this SNP (rs1800907) and autoimmune diseases made in the ninety and
uncorfirmed in more recent papers. Moreover it could be a starting point to search for
other autosomical DNAs diffences between the two sexes
Discovery of unexpected sphingolipids in almonds and pistachios with an innovative use of triple quadrupole tandem mass spectrometry
The densely packed storage of valuable nutrients (carbohydrates, lipids, proteins, micronutrients) in the endosperm of nuts and seeds makes the study of their complex composition a topic of great importance. Ceramides in the total lipid extract of some ground almonds and pistachios were searched with a systematic innovative discovery precursor ion scan in a triple quadrupole tandem mass spectrometry, where iso-energetic collision activated dissociation was performed. Five descriptors were used to search components with different C18 long chain bases containing different structural motifs (d18:0, d18:1, d18:2, t18:0, t18:1). The presence of hexoside unit was screened with a specific neutral loss experiment under iso-energetic collision activated dissociation conditions. The discovery scans highlighted the presence of two specific hexosyl-ceramides with a modified sphingosine component (d18:2) and C16:0 or C16:0 hydroxy-fatty acids. The hexosyl-ceramide with the non-hydroxylated fatty acid seemed specific of pistachios and was undetected in almonds. The fast and comprehensive mass spectrometric method used here can be useful to screen lipid extracts of several more seeds of nutraceutical interest, searching for unusual and/or specific sphingosides with chemically decorated long chain bases
Unambiguous Characterization of p-Cresyl Sulfate, a Protein-Bound Uremic Toxin, as Biomarker of Heart and Kidney Disease
p-Cresyl sulfate is one of the bound uremic toxins whose level increases in the sera of patients with the severity of chronic kidney disease and is therefore used as a standard for clinical investigations. Our first attempts to obtain p-cresyl sulfate led exclusively to the product of sulfonation of the aromatic ring instead of sulfation on the OH moiety. Nevertheless, this initial discouraging result allowed us to handle both p-cresyl sulfate and 2-hydroxy-5-methylbenzenesulfonic acid obtained by different synthetic pathways. Interestingly, the comparison between the two isomers pointed out that the two molecules show the same fragmentation pattern and are indistinguishable by mass spectrometry. They cannot be separated on several commercially available columns. The only difference between the two compounds is a 10-fold higher ionization yield under negative ion electrospray ionization. NMR spectral studies definitely confirmed the different molecular structures. We present here an unambiguous biomimetic synthetic route for p-cresyl sulfate and the spectroscopic characterization of both the compounds by nuclear magnetic resonance and mass spectrometry
Feedback cooling of the normal modes of a massive electromechanical system to submillikelvin temperature
We apply a feedback cooling technique to simultaneously cool the three
electromechanical normal modes of the ton-scale resonant-bar gravitational wave
detector AURIGA. The measuring system is based on a dc Superconducting Quantum
Interference Device (SQUID) amplifier, and the feedback cooling is applied
electronically to the input circuit of the SQUID. Starting from a bath
temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the
coolest normal mode. The same technique, implemented in a dedicated experiment
at subkelvin bath temperature and with a quantum limited SQUID, could allow to
approach the quantum ground state of a kilogram-scale mechanical resonator.Comment: 4 pages, 4 figure
T-cell receptor polymorphism in primary biliary cirrhosis
T-cell receptor (TCR) plays a key role in immune regulation and polymorphisms of its genes have been found in association with several autoimmune diseases. No data are available for primary biliary cirrhosis, an autoimmune liver disease the natural history of which is highly variable. We studied a TCR constant beta-2 chain polymorphism in 70 patients affected by primary biliary cirrhosis and in 70 healthy controls. The DNA chains of patients and controls were amplified by means of polymerase chain reaction using primers designed around a Bgl II polymorphic restriction site and digested for restriction fragment length polymorphism analysis. We found a slight increase of the heterozygous genotype in patients compared with controls (49 vs 40%), which became higher if only patients with early disease were considered (60 vs 40%). Heterozygous patients had less severe disease as indicated by a lower Mayo score (5.1 +/- 1.2 vs 5.7 +/- 1.2 in non-heterozygous). Our data suggest that TCR constant beta-2 polymorphism does not play a key role in modulating the multifactorial etiopathogenesis of primary biliary cirrhosis
IGEC2: A 17-month search for gravitational wave bursts in 2005-2007
We present here the results of a 515 days long run of the IGEC2 observatory,
consisting of the four resonant mass detectors ALLEGRO, AURIGA, EXPLORER and
NAUTILUS. The reported results are related to the fourfold observation time
from Nov. 6 2005 until Apr. 14 2007, when Allegro ceased its operation. This
period overlapped with the first long term observations performed by the LIGO
interferometric detectors. The IGEC observations aim at the identification of
gravitational wave candidates with high confidence, keeping the false alarm
rate at the level of 1 per century, and high duty cycle, namely 57% with all
four sites and 94% with at least three sites in simultaneous observation. The
network data analysis is based on time coincidence searches over at least three
detectors: the four 3-fold searches and the 4-fold one are combined in a
logical OR. We exchanged data with the usual blind procedure, by applying a
unique confidential time offset to the events in each set of data. The
accidental background was investigated by performing sets of 10^8 coincidence
analyses per each detector configuration on off-source data, obtained by
shifting the time series of each detector. The thresholds of the five searches
were tuned so as to control the overall false alarm rate to 1/century. When the
confidential time shifts was disclosed, no gravitational wave candidate was
found in the on-source data. As an additional output of this search, we make
available to other observatories the list of triple coincidence found below
search thresholds, corresponding to a false alarm rate of 1/month.Comment: 10 pages, 8 figures Accepted for publication on Phys. Rev.
Dual detectors of gravitational waves
In a "Dual" gravitational wave (GW) detector a wide band sensitivity is obtained by measuring the differential displacement, driven by the GW, of the facing surfaces of two nested massive bodies mechanically resonating at different frequencies. A "selective readout" scheme, capable of specifically selecting the signal contributed by the vibrational modes sensitive to the gravitational waves, could then reduce the thermal noise contribution from the not sensitive modes. In a dual detector the sensitivity improvement in the displacement transduction could be pursued by means of mechanical amplification systems. This solution is innovative for the resonant GW detectors and we report about preliminary theoretical and experimental study
Nonequilibrium steady state fluctuations in actively cooled resonators
We analyze heat and work fluctuations in the gravitational wave detector
AURIGA, modeled as a macroscopic electromechanical oscillator in contact with a
thermostat and cooled by an active feedback system. The oscillator is driven to
a steady state by the feedback cooling, equivalent to a viscous force. The
experimentally measured fluctuations are in agreement with our theoretical
analysis based on a stochastically driven Langevin system. The asymmetry of the
fluctuations of the absorbed heat characterizes the oscillator's nonequilibrium
steady state and reveals the extent to which a feedback cooled system departs
from equilibrium in a statistical mechanics perspective.Comment: to be published in Phys. Rev. Let
Results of the IGEC-2 search for gravitational wave bursts during 2005
The network of resonant bar detectors of gravitational waves resumed
coordinated observations within the International Gravitational Event
Collaboration (IGEC-2). Four detectors are taking part in this collaboration:
ALLEGRO, AURIGA, EXPLORER and NAUTILUS. We present here the results of the
search for gravitational wave bursts over 6 months during 2005, when IGEC-2 was
the only gravitational wave observatory in operation. The network data analysis
implemented is based on a time coincidence search among AURIGA, EXPLORER and
NAUTILUS, keeping the data from ALLEGRO for follow-up studies. With respect to
the previous IGEC 1997-2000 observations, the amplitude sensitivity of the
detectors to bursts improved by a factor about 3 and the sensitivity bandwidths
are wider, so that the data analysis was tuned considering a larger class of
detectable waveforms. Thanks to the higher duty cycles of the single detectors,
we decided to focus the analysis on three-fold observation, so to ensure the
identification of any single candidate of gravitational waves (gw) with high
statistical confidence. The achieved false detection rate is as low as 1 per
century. No candidates were found.Comment: 10 pages, to be submitted to Phys. Rev.
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