310 research outputs found
Effects of lung volume reduction surgery for emphysema on glycolipidic hormones
BACKGROUND:
Pulmonary emphysema is associated with cachexia and disregulation of the hormones regulating the glycolipid metabolism, insulin resistance, and altered substrate utilization. This study aimed at identifying the effects of lung volume reduction surgery (LVRS) on glycolipidic hormones compared to respiratory rehabilitation (RR).
METHODS:
Thirty-three patients with moderate-to-severe emphysema who were undergoing video-assisted thoracoscopic LVRS were compared to 31 similar patients who refused the operation and followed a standardized RR program. All patients were evaluated before and 12 months after treatment for respiratory function, body composition, glycolipidic hormones, metabolic parameters, and insulin resistance, which was calculated using the homeostatic model assessment index for insulin resistance (HOMA-IR). These groups were compared to a matched healthy control population.
RESULTS:
Only after LVRS significant improvements were obtained in respiratory function (FEV1, +25.2%; p<0.0001; residual volume, -19.5%; p<0.0001), metabolic parameters (total cholesterol, +13.1%; p<0.01; high-density lipoprotein cholesterol, +11.2%; p<0.01; triglycerides, +18.4; p<0.001; nonesterified fatty acid, -19.7%; p<0.001), and body composition (fat-free mass [FFM], +6.5%; p<0.01; fat mass [FM], +11.9%; p<0.01). The leptin/FM ratio (-6.1%; p<0.01) and resistin/FM ratio (-5.6%; p<0.01) decreased, whereas the adiponectin/FM ratio (+6.9%; p<0.01) and ghrelin (+9.2%; p<0.01) increased, together with reductions in glycemia (-8.8%; p<0.01), insulin level (-20.4%; p<0.001), and HOMA-IR (-27.2%; p<0.0001). The decrement in residual volume was correlated with increment of FFM (rho=-0.49; p<0.02), FM (rho=-0.55; p<0.009), and ghrelin (rho=-0.52; p<0.01), and also with decreases in leptin corrected for FM (rho=0.50; p<0.02) and, marginally, HOMA-IR (rho=0.35; p=0.07).
CONCLUSIONS:
After LVRS, glycolipidic hormone levels and nutritional status significantly improved, along with insulin resistance reduction and more physiologic utilization of substrates. Correlations between residual volume and body composition as well as glycolipidic hormone levels suggest that postoperative recovery in respiratory dynamics may induce favorable clinical changes when compared to RR
Vortex dynamics in NbTi films at high frequency and high DC magnetic fields
We report on the characterization of NbTi films at ∼ 11 GHz and in DC magnetic fields up to 4
T, performed by means of the coplanar waveguide resonator technique, providing quantitative
information about the penetration depth, the complex impedance, and the vortex-motion-induced
complex resistivity. This kind of characterization is essential for the development of radiofrequency
cavity technology. To access the vortex-pinning parameters, the complex impedance was analyzed
within the formalism of the Campbell penetration depth. Measurements in this frequency range
allowed us to determine the complete set of vortex-pinning parameters and the flux flow resistivity,
both analyzed and discussed in the framework of high-frequency vortex dynamics models. The
analysis also benefits from the comparison with results obtained by a dielectric-loaded resonator
technique on similar samples and by other ancillary structural and electromagnetic characterization
techniques that provide us with a comprehensive picture of the material. It turns out that the
normalized flux flow resistivity follows remarkably well the trend predicted by the time dependent
Ginzburg-Landau theory, while the pinning constant exhibits a decreasing trend with the field which
points to a collective pinning regime
Early and long-term results of pectoralis muscle flap reconstruction versus sternal rewiring following failed sternal closure
Objectives: The aim of the study was to compare early and long-term results of pectoralis muscle flap reconstruction with those of sternal rewiring following failed sternal closure. Primary outcomes of the study were survival and failure rate. Respiratory function, chronic pain and quality of life were also evaluated. Methods: In a propensity-score matching analysis, of 94 patients who underwent sternal reconstruction, 40 were selected; 20 underwent sternal reconstruction with bilateral pectoralis muscle flaps (Group 1) and 20 underwent sternal rewiring (Group 2). Survival and failure rates were evaluated by in-hospital records and at follow-up. Respiratory function measures, including vital capacity (VC), were evaluated both by spirometry and computed tomography (CT) volumetry. Chronic pain was evaluated by the visual analogue pain scale. Results: At 85 ± 24 months of follow-up, survival and procedure failure were 95 and 90% in Group 1 and 60 and 55% in Group 2, respectively (P < 0.01, for both comparisons). Based on CT-scan volumetry, in Group 1, severe non-union and hemisternal paradoxical movement occurred less frequently (2 vs 7, P = 0.01). At spirometry assessment, postoperative VC was greater in Group 1 (3220 ± 290 vs 3070 ± 290 ml, P = 0.04). The same trend was detected by CT-scan in-expiratory measures (4034 ± 1800 vs 3182 ± 862 mm3, P < 0.05). Correspondingly, in Group 1, less patients presented in NYHA Class III (P < 0.05), and both chronic persistent pain score and physical health quality-of-life score were significantly better in the same group. Conclusions: In our study, muscle flap reconstruction guaranteed better early and late-term results as shown by lower rates of mortality, procedure failure and hemisternum stability. Moreover, Group 1 patients had greater postoperative VC, lower NYHA class and better quality of life. These results suggest that, in patients with multiple bone fracture, the rewiring approach does not promote physiological bone consolidation, whereas the muscle flap reconstruction can assure more physiological ventilatory dynamics.© The Author 2013. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved
Early and long-term results of pectoralis muscle flap reconstruction vs sternal rewiring following failed sternal closure.
OBJECTIVES:
The aim of the study was to compare early and long-term results of pectoralis muscle flap reconstruction with those of sternal rewiring following failed sternal closure. Primary outcomes of the study were survival and failure rate. Respiratory function, chronic pain and quality of life were also evaluated.
METHODS:
In a propensity-score matching analysis, of 94 patients who underwent sternal reconstruction, 40 were selected; 20 underwent sternal reconstruction with bilateral pectoralis muscle flaps (Group 1) and 20 underwent sternal rewiring (Group 2). Survival and failure rates were evaluated by in-hospital records and at follow-up. Respiratory function measures, including vital capacity (VC), were evaluated both by spirometry and computed tomography (CT) volumetry. Chronic pain was evaluated by the visual analogue pain scale.
RESULTS:
At 85 ± 24 months of follow-up, survival and procedure failure were 95 and 90% in Group 1 and 60 and 55% in Group 2, respectively (P < 0.01, for both comparisons). Based on CT-scan volumetry, in Group 1, severe non-union and hemisternal paradoxical movement occurred less frequently (2 vs 7, P = 0.01). At spirometry assessment, postoperative VC was greater in Group 1 (3220 ± 290 vs 3070 ± 290 ml, P = 0.04). The same trend was detected by CT-scan in-expiratory measures (4034 ± 1800 vs 3182 ± 862 mm3, P < 0.05). Correspondingly, in Group 1, less patients presented in NYHA Class III (P < 0.05), and both chronic persistent pain score and physical health quality-of-life score were significantly better in the same group.
CONCLUSIONS:
In our study, muscle flap reconstruction guaranteed better early and late-term results as shown by lower rates of mortality, procedure failure and hemisternum stability. Moreover, Group 1 patients had greater postoperative VC, lower NYHA class and better quality of life. These results suggest that, in patients with multiple bone fracture, the rewiring approach does not promote physiological bone consolidation, whereas the muscle flap reconstruction can assure more physiological ventilatory dynamics
Demonstration and Comparison of Operation of Photomultiplier Tubes at Liquid Argon Temperature
Liquified noble gases are widely used as a target in direct Dark Matter
searches. Signals from scintillation in the liquid, following energy deposition
from the recoil nuclei scattered by Dark Matter particles (e.g. WIMPs), should
be recorded down to very low energies by photosensors suitably designed to
operate at cryogenic temperatures. Liquid Argon based detectors for Dark Matter
searches currently implement photo multiplier tubes for signal read-out. In the
last few years PMTs with photocathodes operating down to liquid Argon
temperatures (87 K) have been specially developed with increasing Quantum
Efficiency characteristics. The most recent of these, Hamamatsu Photonics Mod.
R11065 with peak QE up to about 35%, has been extensively tested within the R&D
program of the WArP Collaboration. During these testes the Hamamatsu PMTs
showed superb performance and allowed obtaining a light yield around 7
phel/keVee in a Liquid Argon detector with a photocathodic coverage in the 12%
range, sufficient for detection of events down to few keVee of energy
deposition. This shows that this new type of PMT is suited for experimental
applications, in particular for new direct Dark Matter searches with LAr-based
experiments
Discovery of underground argon with low level of radioactive 39Ar and possible applications to WIMP dark matter detectors
We report on the first measurement of 39Ar in argon from underground natural
gas reservoirs. The gas stored in the US National Helium Reserve was found to
contain a low level of 39Ar. The ratio of 39Ar to stable argon was found to be
<=4x10-17 (84% C.L.), less than 5% the value in atmospheric argon
(39Ar/Ar=8x10-16). The total quantity of argon currently stored in the National
Helium Reserve is estimated at 1000 tons. 39Ar represents one of the most
important backgrounds in argon detectors for WIMP dark matter searches. The
findings reported demonstrate the possibility of constructing large multi-ton
argon detectors with low radioactivity suitable for WIMP dark matter searches.Comment: 6 pages, 2 figures, 2 table
First results from a Dark Matter search with liquid Argon at 87 K in the Gran Sasso Underground Laboratory
A new method of searching for dark matter in the form of weakly interacting
massive particles (WIMP) has been developed with the direct detection of the
low energy nuclear recoils observed in a massive target (ultimately many tons)
of ultra pure Liquid Argon at 87 K. A high selectivity for Argon recoils is
achieved by the simultaneous observation of both the VUV scintillation
luminescence and of the electron signal surviving columnar recombination,
extracted through the liquid-gas boundary by an electric field. First physics
results from this method are reported, based on a small 2.3 litre test chamber
filled with natural Argon and an accumulated fiducial exposure of about 100 kg
x day, supporting the future validity of this method with isotopically purified
40Ar and for a much larger unit presently under construction with
correspondingly increased sensitivities.Comment: 26 pages, 8 figures, submitted to astroparticle physic
Measurement of the specific activity of Ar-39 in natural argon
We report on the measurement of the specific activity of Ar-39 in natural
argon. The measurement was performed with a 2.3-liter two-phase (liquid and
gas) argon drift chamber. The detector was developed by the WARP Collaboration
as a prototype detector for WIMP Dark Matter searches with argon as a target.
The detector was operated for more than two years at Laboratori Nazionali del
Gran Sasso, Italy, at a depth of 3,400 m w.e. The specific activity measured
for Ar-39 is 1.01 +/- 0.02(stat) +/- 0.08(syst) Bq per kg of natural Ar.Comment: 11 pages, 6 figures, to be submitted to Nucl. Instrum. Methods
Oxygen contamination in liquid Argon: combined effects on ionization electron charge and scintillation light
A dedicated test of the effects of Oxygen contamination in liquid Argon has
been performed at the INFN-Gran Sasso Laboratory (LNGS, Italy) within the WArP
R&D program. Two detectors have been used: the WArP 2.3 lt prototype and a
small (0.7 lt) dedicated detector, coupled with a system for the injection of
controlled amounts of gaseous Oxygen. Purpose of the test with the 0.7 lt
detector is to detect the reduction of the long-lived component lifetime of the
Argon scintillation light emission at increasing O2 concentration. Data from
the WArP prototype are used for determining the behavior of both the ionization
electron lifetime and the scintillation long-lived component lifetime during
the O2-purification process activated in closed loop during the acquisition
run. The electron lifetime measurements allow to infer the O2 content of the
Argon and correlate it with the long-lived scintillation lifetime data. The
effect of Oxygen contamination on the scintillation light has been thus
measured over a wide range of O2 concentration, spanning from about 10^-3 ppm
up to about 10 ppm. The rate constant of the light quenching process induced by
Oxygen in LAr has been found to be k'(O2)=0.54+-0.03 micros^-1 ppm^-1
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