95 research outputs found
Mechanisms of failure to decontaminate the gut with polymixin E, gentamicin and amphotericin B in patients in intensive care.
The objective of the present work was to assess the possible mechanisms of the poor efficiency of selective decontamination of the digestive tract (SDD) in medical and surgical intensive care unit (ICU) patients. Sixty-four consecutive mechanically ventilated patients received gut decontamination with polymixin E, gentamicin and amphotericin B via a nasogastric tube and were assessed for oropharyngeal, gastric and fecal colonization and for the presence of each antibiotic in the stomach and feces. A decrease in fecal colonization with Escherichia coli was observed over 20 days but not with other gram-negative bacteria or gram-positive cocci. Fifteen and 26% of the fecal colonizing gram-negative bacteria were resistant to polymixin E and gentamicin, respectively, at admission. These proportions increased to up to 50% after 16 days of treatment. Although 50% of staphylococci were initially sensitive to gentamicin, all strains were resistant to this drug after four days of SDD. Both antibiotics were found in concentrations of less than 20 micrograms/g in 11 of 38 stools. Of these 38 stools, nine were not contaminated, 20 were colonized with resistant bacteria and 16 with strains sensitive to one antibiotic present in the stool. Therefore, the poor efficiency of gut decontamination observed was probably due to the great proportion of resistant strains on admission of the patients, to the selection of such resistant strains with SDD, to poor intestinal transit of the antibiotics, and to inactivation of the drugs by the feces. These results support stringent monitoring of fecal colonization in patients undergoing SDD in order to detect the fecal carriage of gram-positive and multiresistant gram-negative bacteria
Infrared skin damage thresholds from 1319-nm continous-wave laser exposures
A series of experiments were conducted in vivo using Yucatan miniature pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1319-nm continuous-wave Nd:YAG laser irradiation. Experiments employed exposure durations of 0.25, 1.0, 2.5, and 10 s and beam diameters of ā¼0.6 and 1 cm. Thermal imagery data provided a time-dependent surface temperature response from the laser. A damage endpoint of fifty percent probability of a minimally visible effect was used to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a numerical model of opticalthermal interaction. Resultant trends with respect to exposure duration and beam diameter are compared with current standardized exposure limits for laser safety. Mathematical modeling agreed well with experimental data, predicting that though laser safety standards are sufficient for exposuress, they may become less safe for very long exposures. Ā© The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.JBO.18.12.125002
Mode of onset of torsade de pointes in congenital long QT syndrome
Objectives.We sought to describe the mode of onset of spontaneous torsade de pointes in the congenital long QT syndrome.Background.Contemporary classifications of the long QT syndrome (LQTS) refer to the congenital LQTS as āadrenergic dependentā and to the acquired LQTS as āpause dependent.ā Overlap between these two categories has been recognized, and a subgroup of patients with āidiopathic pause-dependent torsadeā has been described. However, it is not known how commonly torsade is preceded by pauses in the congenital LQTS.Methods.We reviewed the electrocardiograms (ECGs) of all our patients with congenital LQTS evaluated for syncope or sudden death (30 patients). Documentation of the onset of torsade de pointes was available for 15 patients. All these patients had ādefinitive LQTSā by accepted clinical and ECG criteria.Results.Pause-dependent torsade de pointes was clearly documented in 14 of the 15 patients (95% confidence interval 68% to 100%). The cycle length of the pause leading to torsade was 1.3 Ā± 0.2 times longer than the basic cycle length, and most pauses leading to torsade were unequivocally longer than the preceding basic cycle length (80% of pauses were >80 ms longer than the preceding cycle length).Conclusions.The ālong-shortā sequence, which has been recognized as a hallmark of torsade de pointes in the acquired LQTS, plays a major role in the genesis of torsade in the congenital LQTS as well. Our findings have important therapeutic implications regarding the use of pacemakers for prevention of torsade in the congenital LQTS
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Revision of the World Meteorological Organization Global Atmosphere Watch (WMO/GAW) CO2 calibration scale
The NOAA Global Monitoring Laboratory serves as the World Meteorological Organization Global Atmosphere Watch (WMO/GAW) Central Calibration Laboratory (CCL) for CO2 and is responsible for maintaining the WMO/GAW mole fraction scale used as a reference within the WMO/GAW program. The current WMO-CO2-X2007 scale is embodied by 15 aluminum cylinders containing modified natural air, with CO2 mole fractions determined using the NOAA manometer from 1995 to 2006. We have made two minor corrections to historical manometric records: fixing an error in the applied second virial coefficient of CO2 and accounting for loss of a small amount of CO2 to materials in the manometer during the measurement process. By incorporating these corrections, extending the measurement records of the original 15 primary standards through 2015, and adding four new primary standards to the suite, we define a new scale, identified as WMO-CO2-X2019. The new scale is 0.18 µmol mol−1 (ppm) greater than the previous scale at 400 ppm CO2. While this difference is small in relative terms (0.045 %), it is significant in terms of atmospheric monitoring. All measurements of tertiary-level standards will be reprocessed to WMO-CO2-X2019. The new scale is more internally consistent than WMO-CO2-X2007 owing to revisions in propagation and should result in an overall improvement in atmospheric data records traceable to the CCL.
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The Inflammatory Kinase MAP4K4 Promotes Reactivation of Kaposi's Sarcoma Herpesvirus and Enhances the Invasiveness of Infected Endothelial Cells
Kaposi's sarcoma (KS) is a mesenchymal tumour, which is caused by Kaposi's sarcoma herpesvirus (KSHV) and develops under inflammatory conditions. KSHV-infected endothelial spindle cells, the neoplastic cells in KS, show increased invasiveness, attributed to the elevated expression of metalloproteinases (MMPs) and cyclooxygenase-2 (COX-2). The majority of these spindle cells harbour latent KSHV genomes, while a minority undergoes lytic reactivation with subsequent production of new virions and viral or cellular chemo- and cytokines, which may promote tumour invasion and dissemination. In order to better understand KSHV pathogenesis, we investigated cellular mechanisms underlying the lytic reactivation of KSHV. Using a combination of small molecule library screening and siRNA silencing we found a STE20 kinase family member, MAP4K4, to be involved in KSHV reactivation from latency and to contribute to the invasive phenotype of KSHV-infected endothelial cells by regulating COX-2, MMP-7, and MMP-13 expression. This kinase is also highly expressed in KS spindle cells in vivo. These findings suggest that MAP4K4, a known mediator of inflammation, is involved in KS aetiology by regulating KSHV lytic reactivation, expression of MMPs and COX-2, and, thereby modulating invasiveness of KSHV-infected endothelial cells. Ā© 2013 Haas et al
Experiments with CO<sub>2</sub>-in-air reference gases in high-pressure aluminum cylinders
Long-term monitoring of carbon dioxide (CO2) in the atmosphere is key
for a better understanding of the processes involved in the carbon cycle that
have a major impact on further climate change. Keeping track of large-scale
emissions and removals (sources and sinks) of CO2 requires very
accurate measurements. They all have to be calibrated very carefully and have
to be traceable to a common scale, the World
Meteorological Organization (WMO) CO2 X2007 scale, which is
maintained by the National Oceanic and Atmospheric Administration (NOAA) Earth System
Research Laboratory (ESRL) in Boulder, CO, USA. The international WMO GAW (Global Atmosphere Watch) program sets as
compatibility goals for the required agreement between different methods and
laboratories Ā±0.1 Āµmol molā1 for the Northern Hemisphere
and Ā±0.05 Āµmol molā1 for the Southern Hemisphere. The
reference gas mixtures used to pass down and distribute the scale are stored
in high-pressure aluminum cylinders. It is crucial that the standards remain
stable during their entire time of use. In this study the tested vertically
positioned aluminum cylinders showed similar CO2 enrichment during low-flow conditions (0.3 L minā1), which are similar to flows often used
for calibration gases in practical applications. The average CO2
enrichment was 0.090Ā±0.009 Āµmol molā1 as the cylinder
was emptied from about 150 to 1 bar above atmosphere. However, it is
important to note that the enrichment is not linear but follows Langmuir's
adsorptionādesorption model, where the CO2 enrichment is almost
negligible at high pressures but much more pronounced at low pressures. When
decanted at a higher rate of 5.0 L minā1 the enrichment becomes
0.22Ā±0.05 Āµmol molā1 for the same pressure drop. The
higher enrichment is related to thermal diffusion and fractionation effects
in the cylinder, which were also dependent on the cylinder's orientation and
could even turn negative. However, the low amount of CO2 adsorbed on the
cylinder wall and the fact that the main increase happens at low
pressure lead to the conclusion that aluminum cylinders are suitable to store
ambient CO2-in-dry-air mixtures provided they are not used below 20 bar.
In cases where they are used in high-flow experiments that involve significant
cylinder temperature changes, special attention has to be paid to possible
fractionation effects.</p
A rapid and accurate method for quantitating total RNA transferred during Northern blot analysis.
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