H

Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of H

  • RNase h
  • ara h
  • complement factor h
  • delay-dependent h
  • endoglycosidase h
  • factor h
  • g h
  • graph h
  • group h
  • height h
  • kg h
  • l h
  • let h
  • log h
  • mixed h
  • narrow-band h
  • nmol h
  • nonlinear h
  • optimal h
  • parameter h
  • prescribed h
  • protein h
  • rnase h
  • robust h
  • space h
  • type h

  • Terms modified by H

  • h abstraction
  • h activation
  • h ambulatory blood pressure
  • h ambulatory blood pressure monitoring
  • h atom
  • h blood pressure
  • h bond
  • h bond activation
  • h bond dissociation energy
  • h bond functionalization
  • h care
  • h chain
  • h complex
  • h concentration
  • h culture
  • h cycle
  • h daily
  • h dark
  • h day
  • h decreased
  • h disease
  • h distance
  • h duration
  • h ec50
  • h exchange
  • h exposure
  • h fast
  • h fermentation
  • h film
  • h g
  • h group
  • h groups
  • h hypoxia
  • h ii regions
  • h incubation
  • h incubation period
  • h infusion
  • h insertion
  • h interaction
  • h interval
  • h intragastric ph
  • h lc50
  • h lc50 value
  • h light
  • h mortality
  • h oesophageal ph monitoring
  • h old
  • h only
  • h oxidase
  • h perfusion
  • h period
  • h ph
  • h ph monitoring
  • h photoperiod
  • h post dose
  • h post infection
  • h post injection
  • h post-infection
  • h post-treatment
  • h postmortem
  • h ratio
  • h reaction
  • h recording
  • h recovery
  • h reflex
  • h reperfusion
  • h rhythm
  • h sample
  • h shift
  • h stimulation
  • h storage
  • h study period
  • h system
  • h test
  • h time period
  • h time point
  • h treatment
  • h type
  • h urinary excretion
  • h urine
  • h urine collection
  • h urine sample
  • h v
  • h value

  • Selected Abstracts


    Effect of flow parameters of rumen digesta on effective degradability and microbial yield in sheep

    ANIMAL SCIENCE JOURNAL, Issue 4 2009
    Toshiyoshi ICHINOHE
    ABSTRACT The aim of this experiment was to examine the effect of rumen digesta flow parameters on effective degradability (EDG) and microbial nitrogen (MBN) yield in sheep fed diets of identical provision of both metabolizable energy and rumen degradable nitrogen (RDN). Ruminal degradation parameters of early-harvested perennial ryegrass hay (EH), late-harvested perennial ryegrasses hay (LH) and winter sown barley straw (BS) were determined by a nylon bag technique. Subsequently, three experimental diets (EHD, LHD and BSD) were formulated using the tested forages, sucrose and urea as supplements. An in vivo feeding study was conducted using four rumen cannulated sheep in a partial Latin square design. Digestibility, rate constants of rumen particle breakdown and passage, ruminal fermentation parameters and MBN supply to the small intestine were determined. Animals thoroughly consumed the forages fed at a restricted level. Digestion coefficients were greater for EHD than for LHD and were lowest for BSD (P < 0.05). The rate constant of large particle breakdown was 4.3, 5.9 and 6.7 %/h, respectively, and small particle passage was 5.3, 4.7 and 6.3 %/h for EHD, LHD and BSD, respectively. The estimates differed (P < 0.05) between the diets. The overall passage rate constant of total rumen particles was estimated to be higher for BSD than that for EHD or LHD (P < 0.05). Ruminal fermentation parameters were unaffected by dietary treatments (P > 0.05). Intake levels of rumen degradable organic matter (RDOM) and RDN were estimated to be greater for LHD than that for EHD or BSD (P < 0.05). Although dietary arrangements were made to give identical microbial efficiency, the estimated value was higher for EHD than that for LHD or BSD (P < 0.05); and the MBN yield for BSD was estimated to be lower than that for EHD or LHD (P < 0.05). Rumen kinetic parameters of degradation and particle flow of forage affected EDG values and MBN yield from forage-related RDN intake, although those had little effect on the efficiency of MBN yield from forage-related RDOM intake. [source]


    The SAURON project , VII.

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006
    Integral-field absorption, emission-line kinematics of 24 spiral galaxy bulges
    ABSTRACT We present observations of the stellar and gas kinematics for a representative sample of 24 Sa galaxies obtained with our custom-built integral-field spectrograph SAURON operating on the William Herschel Telescope. The data have been homogeneously reduced and analysed by means of a dedicated pipeline. All resulting data cubes were spatially binned to a minimum mean signal-to-noise ratio of 60 per spatial and spectral resolution element. Our maps typically cover the bulge-dominated region. We find a significant fraction of kinematically decoupled components (12/24), many of them displaying central velocity dispersion minima. They are mostly aligned and co-rotating with the main body of the galaxies, and are usually associated with dust discs and rings detected in unsharp-masked images. Almost all the galaxies in the sample (22/24) contain significant amounts of ionized gas which, in general, is accompanied by the presence of dust. The kinematics of the ionized gas are consistent with circular rotation in a disc co-rotating with respect to the stars. The distribution of mean misalignments between the stellar and gaseous angular momenta in the sample suggests that the gas has an internal origin. The [O iii]/H, ratio is usually very low, indicative of current star formation, and shows various morphologies (ring-like structures, alignments with dust lanes or amorphous shapes). The star formation rates (SFRs) in the sample are comparable with that of normal disc galaxies. Low gas velocity dispersion values appear to be linked to regions of intense star formation activity. We interpret this result as stars being formed from dynamically cold gas in those regions. In the case of NGC 5953, the data suggest that we are witnessing the formation of a kinematically decoupled component from cold gas being acquired during the ongoing interaction with NGC 5954. [source]


    An ATCA radio-continuum study of the Small Magellanic Cloud , IV.

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006
    A multifrequency analysis of the N 66 region
    ABSTRACT Traditional identification of supernova remnants (SNRs) include the use of radio spectral index, optical spectral studies (including strong [S ii], [N ii], [O i], [O ii] and [O iii] lines) and X-ray co-identifications. Each of these can have significant limitations within the context of a particular SNR candidate and new identification methods are continually sought. In this paper, we explore subtraction techniques by Ye, Turtle and Kennicutt to remove thermal emission estimated from H, flux from radio-continuum images. The remaining non-thermal emission allows the identification of SNRs embedded within these H ii regions. Subtraction images of the N 66 region in the Small Magellanic Cloud (SMC) using H, wide-field optical CCD images from the Curtis Schmidt Telescope and the recent Australia Telescope Compact Array (ATCA)/Parkes radio-continuum (1420, 2370, 4800 and 8640 MHz) data are presented as an example. These show three SNRs (B0057 , 724, B0056 , 724 and B0056 , 725) separated from their surrounding H ii radio emission. 2.3-m dual-beam spectrograph long-slit spectra from selected regions within N 66 suggest the presence of an additional SNR with no radio or X-ray emission. Radio spectral index, [S ii]/H, ratio and archived Chandra images of N 66 combine to give a more coherent picture of this region, confirming B0057 , 724 as an SNR. The N 66 nebula complex is divided into 10 components, composed separately of these SNRs and H ii regions. [source]


    Infrared mergers and infrared quasi-stellar objects with galactic winds , III.

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005
    Mrk 231: an exploding young quasi-stellar object with composite outflow/broad absorption lines (and multiple expanding superbubbles)
    ABSTRACT We present a study of outflow (OF) and broad absorption line (BAL) systems in Mrk 231, and in similar infrared (IR) quasi-stellar objects (QSOs). This study is based mainly on one-dimensional and two-dimensional spectroscopy (obtained at La Palma/William Herschel Telescope, Hubble Space Telescope, International Ultraviolet Explorer, European Southern Observatory/New Technology Telescope, Kitt Peak National Observatory, Apache Point Observatory and Complejo Astronomico El Leoncito observatories) plus Hubble Space Telescope images. For Mrk 231, we report evidence that the extreme nuclear OF process has at least three main components on different scales, which are probably associated with: (i) the radio jet, at parsec scale; (ii) the extreme starburst at parsec and kiloparsec scale. This OF has generated at least four concentric expanding superbubbles and the BAL systems. Specifically, inside and very close to the nucleus the two-dimensional spectra show the presence of an OF emission bump in the blend H,+[N ii], with a peak at the same velocity of the main BAL-I system (VEjection BAL-I,,4700 km s,1). This bump was more clearly detected in the area located at 0.6,1.5 arcsec (490,1220 pc), to the south-west of the nucleus core, showing a strong and broad peak. In addition, in the same direction [at position angle (PA) ,,120, i.e. close to the PA of the small-scale radio jet] at 1.7,2.5 arcsec, we also detected multiple narrow emission-line components, with ,greatly' enhanced [N ii]/H, ratio (very similar to the spectra of jets bow shocks). These results suggest that the BAL-I system is generated in OF clouds associated with the parsec-scale jet. The Hubble Space Telescope images show four (or possibly five) nuclear superbubbles or shells with radii r, 2.9, 1.5, 1.0, 0.6 and 0.2 kpc. For these bubbles, the two-dimensional H, velocity field map and two-dimensional spectra show the following. (i) At the border of the more extended bubble (S1), a clear expansion of the shell with blueshifted velocities (with circular shape and at a radius r, 5.0 arcsec). This bubble shows a rupture arc , to the south , suggesting that the bubble is in the blowout phase. The axis of this rupture or ejection (at PA , 00) is coincident with the axis of the intermediate and large-scale structures detected at radio wavelengths. (ii) In addition, in the three more external bubbles (S1, S2, S3), the two-dimensional William Herschel Telescope spectra show multiple emission-line components with OF velocities, of ,VOF Bubble, S1, S2 and S3 =[,(650 , 420) 30], [,500 30] and [,230 30] km s,1. (iii) In the whole circumnuclear region (1.8 < r < 5 arcsec), the [N ii]/H, and [S ii]/H, narrow emission-line ratios show high values (>0.8), which are consistent with low-ionization nuclear emission-line region/OF processes associated with fast velocity shocks. Therefore, we suggest that these giant bubbles are associated with the large-scale nuclear OF component, which is generated , at least in part , by the extreme nuclear starburst: giant supernova/hypernova explosions. The variability of the short-lived BAL-III Na i D system was studied, covering almost all the period in which this system appeared (between ,1984 and 2004). We have found that the BAL-III light curve is clearly asymmetric with a steep increase, a clear maximum and an exponential fall (similar to the shape of a supernova light curve). The origin of this BAL-III system is discussed, mainly in the framework of an extreme explosive event, probably associated with giant supernova/hypernova explosions. Finally, the IR colour diagram and the ultraviolet BAL systems of IR + GW/OF + Fe ii QSOs are analysed. This study shows two new BAL IR QSOs and suggests/confirms that these objects could be nearby young BAL QSOs, similar to those detected recently at z, 6.0. We propose that the phase of young QSOs is associated with accretion of a large amount of gas (by the supermassive black hole) + extreme starbursts + extreme composite OFs/BALs. [source]


    The Effect of Hyperbaric Oxygen Therapy on Erectile Function Recovery in a Rat Cavernous Nerve Injury Model

    THE JOURNAL OF SEXUAL MEDICINE, Issue 3 2008
    Alexander Mller MD
    ABSTRACT Introduction., Cavernosal oxygenation appears to be important for preservation of erectile tissue health. Hyperbaric oxygen therapy (HBOT) has been shown to improve tissue oxygenation and has neuromodulatory effects. Aim., This study was designed to define the effects of HBOT on erectile function (EF) and cavernosal tissue in the rat cavernous nerve (CN) injury model. Methods., Four groups of Sprague-Dawley rats were studied: rats with bilateral CN crush, HBOT treated (Crush+/HBOT+); bilateral CN-crush/no HBOT (C+/H,); no crush/no HBOT (C,/H,); and no crush/HBOT (C,/H+). HBOT was delivered daily for 90 minutes at three atmospheres for 10 days commencing the day of CN crush. Main Outcome Measures., Ten days after CN injury, the animals underwent CN stimulation measuring the maximal intracavernosal pressure/mean arterial pressure (ICP/MAP) ratios. Corporal tissue was harvested pre-sacrifice, and immunohistochemically stained for nerve growth factor (NGF), endothelial nitric oxide synthase (eNOS), and cluster of differentiation molecule (CD31). Histologic analysis was performed for Masson's trichrome to assess the smooth muscle,collagen ratio. Terminal deoxynucleotidyl transferase Biotin-dUTP Nick End Labeling assay was used to define apoptotic indices (AIs). Results., The C+/H, group had significantly lower ICP/MAP ratios compared with C,/H, rats, (31% vs. 70%, P < 0.001). C+/H+ rats had significantly higher ICP/MAP ratio recovery compared with the C+/H, group (55% vs. 31%, P = 0.005). NGF and eNOS staining densities were higher in C+/H+ rats compared with C+/H, rats (P < 0.05 and P < 0.001, respectively). No difference was seen in CD31 expression. Staining density for MT displayed a trend toward higher smooth muscle preservation after HBOT. AIs were significantly increased by HBOT (P < 0.05). Conclusion., HBOT following a CN injury improved EF preservation in this model, supporting the cavernosal oxygenation concept as protective mechanism for EF. The effects appear to be mediated via preservation of neurotrophic and endothelial factor expression. Mller A, Tal R, Donohue JF, Akin-Olugbade Y, Kobylarz K, Paduch D, Cutter SC, Mehrara BJ, Scardino PT, and Mulhall JP. The effect of hyperbaric oxygen therapy on erectile function recovery in a rat cavernous nerve injury model. J Sex Med 2008;5:562,570. [source]


    Metallicity gradients: Mass dependency in dwarf elliptical galaxies,

    ASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009
    M. Koleva
    Abstract The formation and evolution of galaxies is imprinted on their stellar population radial gradients. Two recent articles present conflicting results concerning the mass dependence of the metallicity gradients for early-type dwarf galaxies. On one side, Spolaor et al. (2009) show a tight positive correlation between the total metallicity [Z /H] and the mass. On the other side, in a distinct sample, we do not find any trend involving [Fe/H] (Koleva et al. 2009). In order to investigate the origin of the discrepancy, we examine various factors that may affect the determination of the gradients: namely the sky subtraction and the signal-to-noise ratio. We conclude that our detection of gradients are well above the possible analysis biases. Then, we measured the [Mg/Fe] relative abundance profile and found moderate gradients. The derived [Z /H] gradients scatter around ,0.4 dex/re. The two samples contain the same types of objects and the reason of the disagreement is still not understood ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Observation of the second-nearest-neighbor Bloch oscillation in a GaAs/AlAs superlattice

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2008
    T. Hasegawa
    Abstract We have systematically investigated the quantum beat of the miniband excitons and the Bloch oscillation in the Wannier-Stark (WS) localization as a function of applied bias voltage in a GaAs (6.8 nm)/AlAs (0.9 nm) superlattice embedded in a p - i - n diode structure. The coherent dynamics behaviors were detected with a reflection-type pump-probe technique. We clearly observed the transformation process from the miniband-exciton quantum beat to the Bloch oscillation with an increase in applied bias voltage producing an internal electric field. The noteworthy finding is the fact that the Bloch oscillation with the frequency of vBO = 2eFD /h appears in a weak localization regime in addition to the usual Bloch oscillation with vBO = eFD /h in a strong localization regime, where F is the electric field, and D is the superlattice period. The frequency of 2eFD /h indicates that the newly observed Bloch oscillation is due to the wave-packet motion in the second-nearest-neighbor space range. The results described above are explained by the electric-field-strength dependence of the envelope-function localization, which is estimated from the envelope-function profile calculated by a transfer-matrix method and the excitonic transitions observed by electroreflectance spectroscopy. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Effect of food shortage and temperature on oxygen consumption in the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

    PHYSIOLOGICAL ENTOMOLOGY, Issue 4 2003
    D. Renault
    Abstract., Temperature and food availability are limiting factors for the establishment of tropical insects in temperate countries. In the alien pest beetle, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), starvation and temperature have a significant impact on metabolic rate with oxygen consumption ranging from 0.5 mol/g fresh mass (FM)/h at 12 C to 3.4 mol/g FM/h at 24 C. At 12 C, oxygen consumption decreased continuously during an entire period of starvation. However, at 16, 20 and 24 C, beetles display a marked hyperactivity that leads to an increase in the oxygen consumption level during the first week of starvation, followed by a steep decrease until the end of the starvation period. Oxygen consumption either does not decline in fed beetles (observed at higher temperatures) or declines at a much shallower rate than in starved beetles (observed at cooler temperatures). During the first week of refeeding, Oxygen consumption rose steeply at 16, 20 and 24 C before levelling off to the initial value (t0). At 12 C, no compensation process was observed during recovery. This study reveals that an important threshold in the biology of A. diaperinus lies between 12 and 16 C, leading to the onset of reduced locomotor activity and the promotion of survival to the detriment of reproduction. This ,sit and wait' behaviour is proposed as an adaptive strategy (i.e. inactivity and lower oxygen consumption coupled with low energetic requirements and high recovery abilities). Such behaviour and the observed hyperactivity were rarely described in insects before the present study. Together, the previous and present results suggest that A. diaperinus populations are likely maintained in temperate regions by immigration from warmer situations. [source]


    Variance scaling in shallow-cumulus-topped mixed layers

    THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 628 2007
    R. A. J. Neggers
    Abstract Scaling of thermodynamic variance in shallow-cumulus-topped mixed layers is studied using large-eddy simulation (LES). First, the performance of the top-down scaling (the turbulent flux at mixed-layer top divided by w*) is evaluated for transient shallow-cumulus convection over land. The results indicate that this scaling fails to capture all the variance in the top half of the mixed layer when shallow cumulus clouds are present. A variance-budget analysis is then performed, to derive a new scaling for the variance at mixed-layer top, which differs from the standard top-down scaling by a factor of one Richardson number. The essential new features of the proposed scaling are that the local vertical gradient is retained and that a balance is assumed between gradient production of variance and removal by transport and dissipation, using an adjustment time-scale given by w*/h. Evaluation against LES for a range of different cases, including a dry convective boundary layer as well as steady-state marine and transient continental shallow cumulus, reveals a data-collapse of the newly-scaled variance, for all hours and all cases in the top half of the mixed layer. The corresponding vertical structure is shown to resemble a power-law function. The results suggest that the structure of variance in the dry convective boundary layer is similar to that in the sub-cloud mixed layer. In transient situations, the scaling reproduces the time-development of variance at sub-cloud mixed-layer top. The new cloud-base variance scale is then further interpreted in the context of statistical cloud schemes, which depend on the variance as the second moment of the associated probability density function. The results suggest that the area fraction of the moist convective thermals uniquely depends on the ratio of cloud-base transition-layer depth to sub-cloud mixed-layer depth. This puts ,valve'- or ventilation-type closures for the cloud-base mass flux in the context of the variance budget for the sub-cloud layer. Copyright 2007 Royal Meteorological Society [source]


    Degradation kinetics of ptaquiloside in soil and soil solution

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2008
    Rikke Gleerup Ovesen
    Abstract Ptaquiloside (PTA) is a carcinogenic norsesquiterpene glycoside produced in bracken (Pteridium aquilinum (L.) Kuhn), a widespread, aggressive weed. Transfer of PTA to soil and soil solution eventually may contaminate groundwater and surface water. Degradation rates of PTA were quantified in soil and soil solutions in sandy and clayey soils subjected to high natural PTA loads from bracken stands. Degradation kinetics in moist soil could be fitted with the sum of a fast and a slow first-order reaction; the fast reaction contributed 20 to 50% of the total degradation of PTA. The fast reaction was similar in all horizons, with the rate constant k1F ranging between 0.23 and 1.5/h. The slow degradation, with the rate constant k1S ranging between 0.00067 and 0.029/h, was more than twice as fast in topsoils compared to subsoils, which is attributable to higher microbial activity in topsoils. Experiments with sterile controls confirmed that nonmicrobial degradation processes constituted more than 90% of the fast degradation and 50% of the slow degradation. The lower nonmicrobial degradation rate observed in the clayey compared with the sandy soil is attributed to a stabilizing effect of PTA by clay silicates. Ptaquiloside appeared to be stable in all soil solutions, in which no degradation was observed within a period of 28 d, in strong contrast to previous studies of hydrolysis rates in artificial aqueous electrolytes. The present study predicts that the risk of PTA leaching is controlled mainly by the residence time of pore water in soil, soil microbial activity, and content of organic matter and clay silicates. [source]


    Dynamic Predictive Model for Growth of Salmonella Enteritidis in Egg Yolk

    JOURNAL OF FOOD SCIENCE, Issue 7 2007
    V. Gumudavelli
    ABSTRACT:,Salmonella Enteritidis (SE) contamination of poultry eggs is a major human health concern worldwide. The risk of SE from shell eggs can be significantly reduced through rapid cooling of eggs after they are laid and their storage under safe temperature conditions. Predictive models for the growth of SE in egg yolk under varying ambient temperature conditions (dynamic) were developed. The growth of SE in egg yolk under several isothermal conditions (10, 15, 20, 25, 30, 35, 37, 39, 41, and 43 C) was determined. The Baranyi model, a primary model, was fitted with growth data for each temperature and corresponding maximum specific growth rates were estimated. Root mean squared error (RMSE) values were less than 0.44 log10 CFU/g and pseudo- R2 values were greater than 0.98 for the primary model fitting. For developing the secondary model, the estimated maximum specific growth rates were then modeled as a function of temperature using the modified Ratkowsky's equation. The RMSE and pseudo- R2 were 0.05/h and 0.99, respectively. A dynamic model was developed by integrating the primary and secondary models and solving it numerically using the 4th-order Runge,Kutta method to predict the growth of SE in egg yolk under varying temperature conditions. The integrated dynamic model was then validated with 4 temperature profiles (varying) such as linear heating, exponential heating, exponential cooling, and sinusoidal temperatures. The predicted values agreed well with the observed growth data with RMSE values less than 0.29 log10 CFU/g. The developed dynamic model can predict the growth SE in egg yolk under varying temperature profiles. [source]


    Determination of ligustilide in rat blood and tissues by capillary gas chromatography/mass spectrometry

    BIOMEDICAL CHROMATOGRAPHY, Issue 10 2006
    Yunfeng Shi
    Abstract A gas chromatography/mass spectrometry (GC/MS) method was developed to study the pharmacokinetics of ligustilide following oral administration to rats. The method was used for the analysis of samples taken from rats. Biological samples were prepared by liquid,liquid extraction (LLE) using an n -hexane,ether (2:1) solvent mixture for a sample clean-up step and analyzed by GC/MS with a quadrupole MS detector in selected ion monitoring mode (m/z 190). The calibration curves were linear over the concentration range 0.172,8.60 g/mL (r > 0.99) for blood samples and a different range (r > 0.99) for different tissue samples. The limit of detection (LOD) was 1.0 ng/mL or 1.0 ng/g (three times the signal,noise ratio). Within- and between-day precision expressed as the relative standard deviation (RSD) for the method was 1.58,3.88 and 2.99,4.91%, respectively. The recovery for all samples was >80%, except for liver samples (>70%). The main pharmacokinetic parameters obtained were: Tmax = 0.65 0.07 h, Cmax = 1.5 0.2 g/mL, AUC = 34 6 h g/mL and Ka = 3.5 0.6/h. The experimental results showed that ligustilide was easily absorbed, but its elimination was slow, from 3 to 12 h after oral administration. The concentrations of ligustilide in rat cerebellum, cerebrum, spleen and kidney were higher than those in other organs. Copyright 2006 John Wiley & Sons, Ltd. [source]


    Inhomogeneous sodium accumulation in the ischemic core in rat focal cerebral ischemia by 23Na MRI

    JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2009
    Victor E. Yushmanov PhD
    Abstract Purpose To test the hypotheses that (i) the regional heterogeneity of brain sodium concentration ([Na+]br) provides a parameter for ischemic progression not available from apparent diffusion coefficient (ADC) data, and (ii) [Na+]br increases more in ischemic cortex than in the caudate putamen (CP) with its lesser collateral circulation after middle cerebral artery occlusion in the rat. Materials and Methods 23Na twisted projection MRI was performed at 3 Tesla. [Na+]br was independently determined by flame photometry. The ischemic core was localized by ADC, by microtubule-associated protein-2 immunohistochemistry, and by changes in surface reflectivity. Results Within the ischemic core, the ADC ratio relative to the contralateral tissue was homogeneous (0.63 0.07), whereas the rate of [Na+]br increase (slope) was heterogeneous (P < 0.005): 22 4%/h in the sites of maximum slope versus 14 1%/h elsewhere (here 100% is [Na+]br in the contralateral brain). Maximum slopes in the cortex were higher than in CP (P < 0.05). In the ischemic regions, there was no slope/ADC correlation between animals and within the same brain (P > 0.1). Maximum slope was located at the periphery of ischemic core in 8/10 animals. Conclusion Unlike ADC, 23Na MRI detected within-core ischemic lesion heterogeneity. J. Magn. Reson. Imaging 2009;30:18,24. 2009 Wiley-Liss, Inc. [source]


    Degradation kinetics of ptaquiloside in soil and soil solution

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2008
    Rikke Gleerup Ovesen
    Abstract Ptaquiloside (PTA) is a carcinogenic norsesquiterpene glycoside produced in bracken (Pteridium aquilinum (L.) Kuhn), a widespread, aggressive weed. Transfer of PTA to soil and soil solution eventually may contaminate groundwater and surface water. Degradation rates of PTA were quantified in soil and soil solutions in sandy and clayey soils subjected to high natural PTA loads from bracken stands. Degradation kinetics in moist soil could be fitted with the sum of a fast and a slow first-order reaction; the fast reaction contributed 20 to 50% of the total degradation of PTA. The fast reaction was similar in all horizons, with the rate constant k1F ranging between 0.23 and 1.5/h. The slow degradation, with the rate constant k1S ranging between 0.00067 and 0.029/h, was more than twice as fast in topsoils compared to subsoils, which is attributable to higher microbial activity in topsoils. Experiments with sterile controls confirmed that nonmicrobial degradation processes constituted more than 90% of the fast degradation and 50% of the slow degradation. The lower nonmicrobial degradation rate observed in the clayey compared with the sandy soil is attributed to a stabilizing effect of PTA by clay silicates. Ptaquiloside appeared to be stable in all soil solutions, in which no degradation was observed within a period of 28 d, in strong contrast to previous studies of hydrolysis rates in artificial aqueous electrolytes. The present study predicts that the risk of PTA leaching is controlled mainly by the residence time of pore water in soil, soil microbial activity, and content of organic matter and clay silicates. [source]


    To be or not to be what you eat: regulation of stoichiometric homeostasis among autotrophs and heterotrophs

    OIKOS, Issue 5 2010
    Jonas Persson
    Homeostasis of element composition is one of the central concepts of ecological stoichiometry. In this context, homeostasis is the resistance to change of consumer body composition in response to the chemical composition of consumer's food. To simplify theoretical analysis, it has generally been assumed that autotrophs exhibit flexibility in their composition, while heterotrophs are confined to a constant (strictly homeostatic) body composition. Yet, recent studies suggest that heterotrophs are not universally strictly homeostatic. We examined the degree to which autotrophs and heterotrophs regulate stoichiometric homeostasis (P:C, N:C, N:P, or %P and %N). We conducted a quantitative review and meta-analysis using 132 datasets extracted from 57 literature sources which examined the dependence of organismal stoichiometry on resource stoichiometry. Among individual datasets, there was a wide range of responses from strictly homeostatic to non-homeostatic. Even within heterotrophic organisms, varying levels of homeostasis were observed. Comparing the degree of homeostasis between organisms based on large-scale habitat types using meta-analysis indicated some significant differences between groups. For example, aquatic macroinvertebrates were significantly more homeostatic in terms of P:C than terrestrial invertebrates. Our meta-analysis also confirmed that, with regard to N:P, heterotrophs are significantly more homeostatic than autotrophs. Furthermore, our analysis indicated that the homeostasis parameter 1/H, despite being a potentially useful predictive metric, has to be utilized with caution since it oversimplifies some important aspects of the responses of organisms to elemental imbalances. This critical evaluation of stoichiometric homeostasis contributes to a better understanding of many food-web interactions, which are commonly driven by elemental imbalances between consumers and their resources. [source]


    Formation of Biofilm on Different Particulate Media Using Modified Kitchen Waste Extract as Initial Growth Substrate for Use in PCB Degradation

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2005
    J. Auresenia
    Abstract This study describes the formation of biofilm on two different particulate media using modified kitchen waste extract as initial growth medium, and the subsequent testing of the this biofilm to biodegrade polychlorinated biphenyls (PCBs). Two parallel completely mixed fluidized bed reactors, one using cement balls and the other using sand as particulate media, were operated in order to produce the biofilm. Modified kitchen waste extract was used as a growth substrate instead of the more expensive complex substrate. The medium was inoculated with microorganisms from tannery wastes. Performance of the biofilms formed in the two reactors were compared based on BOD and COD degradation rates, biomass growth rate, biofilm thickness and ease offluidization. The results demonstrate that a stable biofilm can be formed on readily available particulate materials using cheap substrate from kitchen wastes extracts. Furthermore, cement balls proved to be more suitable as particulate media compared to sand, possessing superior biofilm-forming characteristics. The biofilm formed on cement balls was tested for the degradation of PCBs. Initial PCB batch degradation tests showed that about 70% of PCBs degraded within six hours. Kinetics of PCB degradation followed the Monod model with Km = 561.98 mg/l and m,max=0.07 1/h. [source]


    Quercetin pharmacokinetics in humans

    BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2008
    Young J. Moon
    Abstract The purpose of this study was to examine the pharmacokinetics of quercetin aglycone as well as its conjugated metabolites and to develop a population pharmacokinetic model for quercetin that incorporates enterohepatic recirculation. The stability of quercetin in different matrices at various temperatures and pH, and the quercetin content of six capsules of the herbal preparation Quercetin-500 Plus were determined by HPLC. Subjects received quercetin 500,mg three times daily and blood and urine samples were obtained. The concentration of quercetin aglycone and conjugated metabolites were assayed using a liquid chromatography-tandem mass spectrometry assay. Pharmacokinetic parameters were determined using noncompartmental analysis with WinNonlin. A population compartment model incorporating input from the gallbladder was developed to account for the enterohepatic recirculation observed with quercetin. The oral clearance (CL/F) was high (3.5,,104l/h) with an average terminal half-life of 3.5,h for quercetin. The plasma concentration versus time curves exhibited re-entry peaks. A one-compartment model that included enterohepatic recirculation best described the plasma data. This represents the first comprehensive evaluation of the pharmacokinetics and enterohepatic recirculation of quercetin in humans. Population pharmacokinetic models adapted for enterohepatic recirculation allowed an assessment of the magnitude and frequency of the enterohepatic recirculation process. Copyright 2008 John Wiley & Sons, Ltd. [source]


    Determination of iodide using flow injection with acidic potassium permanganate chemiluminescence detection

    LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4 2006
    Mohammad Yaqoob
    Abstract A simple and rapid flow-injection method is described for the determination of iodide, based on potassium permanganate chemiluminescence detection via oxidation of formaldehyde in aqueous hydrochloric acid. The calibration graph was linear over the range 1.0,12 10,6 mol/L (r2 = 0.9955) with relative standard deviations (n = 4) in the range 1.0,3.5%. The detection limit (3,) was 1.0 10,7 mol/L, with sample throughput of 120/h. The effect of interfering cations [Ca(II), Mg(II), Ni(II), Fe(II), Fe(III) and Pb(II)] and anions (Cl,, SO42,, PO43,, NO3,, NO2,, F, and SO32,) were studied. The method was applied to iodized salt samples and the results obtained in the range 0.03 0.005,0.10 0.006 mg I/g were in reasonable agreement with the amount labelled. The method was statistically compared with the results obtained by titration; no significant disagreement at 95% confidence was observed. Copyright 2006 John Wiley & Sons, Ltd. [source]


    Determination of iron in blood serum using ,ow injection with luminol chemiluminescence detection

    LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2004
    A. Waseem
    Abstract A simple and rapid ,ow injection method is reported for the determination of iron in blood serum after acid digestion with HNO3 and HClO4, based on luminol CL detection in the absence of added oxidant. The detection limit (3 s) was 1.0 nmol/L with a sample throughput of 120/h. The calibration graph was linear over the range 0.001,1.0 mol/L (r2 = 0.9974), with relative standard deviations (RSD) (n = 4) in the range 3.2,5%. The effect of interfering cations (Ca(II), Mg(II), Cu(II), Cd(II), Pb(II), Mn(II), Zn(II), Ni(II), Co(II) and Fe(III)) and anions (Cl,, SO42,, HCO3,, NO3,, NO2,) were studied using a luminol CL system for Fe(II) determination. The method was applied to normal blood serum and the results (1.32 0.08,1.74 0.05 mg/L) were compared with those from a spectrophotometric reference method (1.34 0.06,1.80 0.10 mg/L), which agree fairly well with the overall reference range in blood. Copyright 2004 John Wiley & Sons, Ltd. [source]


    Fc, receptor polymorphisms and periodontal status: a prospective follow-up study

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2006
    D. L. Wolf
    Abstract Aims: The aims of this study were to assess: (i) the distribution of Fc, receptor polymorphisms among patients with chronic periodontitis ("cases") and control subjects with no/minimal loss of periodontal tissue support in a Caucasian population; (ii) whether these polymorphisms can serve as severity markers for periodontitis; and (iii) whether they have any bearing on the response to periodontal therapy. Methods: The study sample consisted of 132 cases and 73 controls of comparable age and gender. Full-mouth periodontal status was assessed. Subgingival plaque (PL) samples and blood samples were obtained and analysed with respect to 19 bacterial species and homologous serum immunoglobulin G titres. Polymorphisms in the Fc, receptor IIa (131R/H) and IIIb (NA1/NA2) were assessed by polymerase chain reaction. Patients underwent periodontal therapy and were followed up at 4 and 30 months. Results: Neither polymorphism showed a skewed distribution among cases and controls. At baseline, periodontitis patients with Fc, RIIa-H/H131 genotype had more PL and deeper pockets than patients in other genotype groups (p<0.05). Both bacterial levels and antibody titres were unrelated to genotype. The longitudinal analysis failed to detect an association between genotype and response to periodontal therapy. Conclusions: The present data failed to demonstrate a clinically relevant relationship between the Fc, receptor IIa (131R/H) or IIIb (NA1/NA2) polymorphism and periodontal status. [source]


    MINERALOGY OF MEDIEVAL SLAGS FROM LEAD AND SILVER SMELTING (BOHUTN, P,BRAM DISTRICT, CZECH REPUBLIC): TOWARDS ESTIMATION OF HISTORICAL SMELTING CONDITIONS*

    ARCHAEOMETRY, Issue 6 2009
    V. ETTLER
    Slags from the Pb/Ag medieval (14th century) smelting plant located at Bohutn, P,bram district, Czech Republic, were studied from the mineralogical and geochemical points of view. Two types of slags were distinguished: (i) quenched slags formed mainly by Pb-rich glass and unmelted residual grains of SiO2 and feldspars, and (ii) crystallized slags mainly composed of Fe-rich olivine (fayalite) and glass. The mean log viscosity value of the slags calculated for 1200C was 2.119 Pa s. The morphology of olivine crystals was used to estimate the cooling rates of the melt, for some slags indicating rates > 1450C/h. The projection of the bulk composition of slags onto the SiO2,PbO,FeO ternary system was used for rough temperature estimates of slag formation, lying probably between 800 and 1200C. [source]


    Restless legs symptoms without periodic limb movements in sleep and without response to dopaminergic agents: a restless legs-like syndrome?

    EUROPEAN JOURNAL OF NEUROLOGY, Issue 12 2007
    C. R. Baumann
    Patients fulfilling the essential criteria for restless legs syndrome (RLS), but in whom the response to conventional dopaminergic treatment and the presence of periodic limb movements in sleep (PLMS) are lacking, are occasionally encountered. The aim of this study was to systematically characterize this population. In a consecutive series of 117 patients fulfilling the essential criteria for RLS, we assessed the presence of the following supportive criteria: PLMS >15/h on polysomnography, and favourable response to dopaminergic treatment. We differentiated patients with ,classical RLS' (RLS-C; fulfilling at least one of the selected supportive criteria) from those with ,RLS-like syndrome' (RLS-L) in whom supportive criteria were not fulfilled. There were 103 RLS-C and 14 RLS-L patients. Compared with RLS-C patients, RLS-L patients were significantly younger, more severely affected by RSL symptoms, and were more probably to suffer from psychiatric comorbidities, than RLS-C patients. This study proves the existence of patients with severe RLS symptoms, but without PLMS and without response to dopaminergic treatment, who are clinically distinct from patients with ,classical RLS'. [source]


    Sleep-Disordered Breathing in Recipients of Implantable Defibrillators

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009
    WOLFRAM GRIMM M.D.
    Study Objectives: To examine the prevalence and clinical significance of sleep-disordered breathing in patients with implantable cardioverter defibrillators (ICD). Methods and Results: Overnight sleep studies were performed in 129 ICD recipients who had no history of sleep apnea. The mean left ventricular ejection fraction (LVEF) was 29 11%. Mild, moderate, and severe sleep apnea was diagnosed in the presence of an apnea/hypopnea index (AHI) of 5,15/h, 15.1,30/h, and >30/h, respectively. No sleep apnea was present in 49 patients (38%), 57 (44%) had central sleep apnea (CSA), and 23 patients (18%) had obstructive sleep apnea (OSA). Mild, moderate, and severe sleep apnea were present in 25%, 31%, and 44% of patients with CSA, compared with 52%, 22%, and 26% of patients with OSA (P < 0.05). LVEF was similar in patients with versus without OSA or CSA. Patients with CSA were significantly older and had a higher prevalence of ischemic cardiomyopathy than patients without sleep apnea. Conclusions: Previously undiagnosed CSA is common in ICD recipients. Severely disordered breathing during sleep was more prevalent among patients with CSA than patients with OSA. This prospective, observational study will examine the long-term clinical significance of sleep-disordered breathing in ICD recipients. [source]


    Array antenna assisted doppler spread compensator for OFDM

    EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2002
    Minoru Okada
    This paper proposes a novel array-antenna-assisted Doppler spread compensator for orthogonal frequency division multiplexing (OFDM), which is sensitive to fast time-variation of the radio propagation channel. In the proposed compensator, a linear array antenna is installed on top of the vehicle. The compensator estimates the received signal at a certain point on the linear array antenna by using space domain interpolation. Because the relative position of the estimated receiving point with respect to the ground does not change during the effective symbol duration of an OFDM signal, the time variation due to the movement of the vehicle can be compensated for. Computer simulation shows that the compensator can compensate for the bit error rate performance degradation due to time-variation of the channel when the velocity of the vehicle is up to 180km/h and a two-element array antenna is used at the carrier frequency of 600 MHz. The bit error rate performance can be further improved by using a four-element array antenna. [source]


    Does propofol and alfentanil-induced sedation cause periodic apnoea in chronic renal failure patients?

    INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 1 2010
    S. M. Lee
    Summary Aims:, There is evidence suggesting that the respiratory response to sedation is different in patients with sleep apnoea, which is common in patients with chronic renal failure (CRF). This study examined the respiratory response of sedation with propofol and alfentanil, whose pharmacokinetics are not affected by the renal function, in CRF patients. Methods:, Chronic renal failure patients who underwent arteriovenous-fistular surgery (CRF group) and patients who underwent chemoport insertion (control group) were enrolled in this study. Sedation was induced by infusing propofol 1.5 ,/ml and alfentanil 0.2 ,/kg/min continuously in both groups. In the desaturation study, the respiratory rate and peripheral oxygen saturation in room air were checked. In the apnoea,hypopnoea study, the patient's sedation (Observer's Assessment of Alertness/Sedation) score, apnoea,hypopnoea index (AHI) was recorded using a portable ventilation effort recorder (microMesam) while applying 5 l/min of oxygen through a facial mask. Results:, The desaturation event was more common (21.5/h vs. 2/h, p = 0.001) in the CRF patients. Apnoea and hypopnoea (AHI: 13.0 vs. 1.6, p = 0.012, per cent of patients with an AHI > 5: 53.3% vs. 7.1%, p = 0.014) occurred more frequently in the CRF patients but the sedation score was not different. Conclusion:, Chronic renal failure patients have a higher risk of developing apnoea and hypopnoea during sedation, which highlights the need for careful monitoring and management in these patients. [source]


    Does nasal decongestion improve obstructive sleep apnea?

    JOURNAL OF SLEEP RESEARCH, Issue 4 2008
    CHRISTIAN F. CLARENBACH
    Summary Whether nasal congestion promotes obstructive sleep apnea is controversial. Therefore, we performed a randomized placebo-controlled cross-over trial on the effects of topical nasal decongestion in patients with obstructive sleep apnea syndrome (OSA) and nasal congestion. Twelve OSA patients with chronic nasal congestion (mean SD age 49.1 11.1 years, apnea/hypopnea index 32.6 24.5/h) were treated with nasal xylometazoline or placebo for 1 week each. At the end of treatment periods, polysomnography including monitoring of nasal conductance by an unobtrusive technique, vigilance by the OSLER test, and symptom scores were assessed. Data from xylometazoline and placebo treatments were compared. Mean nocturnal nasal conductance on xylometazoline was significantly higher than on placebo (8.6 5.3 versus 6.3 5.8 mL s,1Pa,1, P < 0.05) but the apnea/hypopnea index was similar (29.3 32.5/h versus 33.2 32.8/h, P = NS). However, 30,210 min after application of xylometazoline, at the time of the maximal pharmacologic effect, the apnea/hypopnea index was slightly reduced (27.3 30.5/h versus 33.2 33.9/h, P < 0.05). Xylometazoline did not alter sleep quality, sleep resistance time (33.6 8.8 versus 33.4 10.1 min, P = NS) and subjective sleepiness (Epworth score 10.5 3.8 versus 11.8 4.4, P = NS). The reduced apnea/hypopnea index during maximal nasal decongestion by xylometazoline suggests a pathophysiologic link but the efficacy of nasal decongestion was not sufficient to provide a clinically substantial improvement of OSA. ClinicalTrials.gov Identifier is NTC006030474. [source]


    Multielement (H, C, N, O, S) stable isotope characteristics of lamb meat from different Italian regions,

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2009
    Matteo Perini
    The study focuses on the 2H/H, 13C/12C, 15N/14N, 18O/16O and 34S/32S values of defatted dry matter (DFDM) and on the 2H/H, 13C/12C and 18O/16O values of the fat fraction of meat samples from various lamb types reared in seven Italian regions, following different feeding regimes (forage, concentrate, milk). The 13C/12C (r,=,0.922), 2H/H (r,=,0.577) and 18O/16O (r,=,0.449) values of fat and DFDM are significantly correlated, the fat values being significantly lower for C and H and higher for O than for DFDM values and the differences between the two fractions not being constant for different lamb types. The feeding regime significantly affected the 13C/12C, 15N/14N, 18O/16O and 2H/H of fat. The DFDM 2H/H, and 18O/16O values, excluding an outlier, are significantly correlated with the corresponding values in meteoric waters, thus allowing us to trace the variability of geoclimatic factors. 15N/14N is influenced by pedoclimatic conditions, whereas 34S/32S is influenced by the sea spray effect and the surface geology of the provenance area. By applying stepwise linear discriminant analysis only the 2H/H of fat was found not to be significant and 97.7% of the samples were correctly assigned to the lamb type and more than 90% cross-validated. With the feeding regime, 97.7% of the samples were both correctly assigned and cross-validated using a predictive model including 13C/12C, 15N/14N, 18O/16O, 34S/32S of DFDM and 18O/16O of fat. Copyright 2009 John Wiley & Sons, Ltd. [source]


    [2H/H] Isotope ratio analyses of [2H5]cholesterol using high-temperature conversion elemental analyser isotope-ratio mass spectrometry: determination of cholesterol absorption in normocholesterolemic volunteers

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2004
    Jean-Philippe Godin
    This paper validates the use of high-temperature conversion elemental analyser isotope-ratio mass spectrometry (TC-EA/IRMS) for measuring the [2H/H] enrichment of plasma [2H5]cholesterol. From a molecular point of view, the free cholesterol is initially separated from plasma by thin-layer chromatography (TLC) and then injected onto the TC-EA reactor which converts cholesterol molecules into CO and H2 gases. The slope of the curve of the experimental mole percent excess (MPE(exp.)) versus MPE(theor.) was very close to 1, demonstrating that no significant isotopic fractionation was observed during all processing of the samples (i.e., isolation of plasma free cholesterol by TLC and pyrolysis in the TC-EA reactor). Excellent linearity (r2,=,0.9994, n,=,4) of , (,) of [2H/H] isotopic measurements versus mole percent (MP) was assessed over the range 0 to 0.1 MP. The precision of the [2H/H] measurement, evaluated with two calibration points processed with TLC, was ,2HV-SMOW,=,,192.5,,3.4, and ,2HV-SMOW,=,,136.9,,2.9,. The standard deviations of the within-assay and between-assay repeatabilities of the analytical process, evaluated using the quality control (QC) of plasma samples, were 4.6 and 6.1,, respectively. Plant sterols are known to reduce cholesterol absorption and therefore were used as a positive control in a clinical study performed with normocholesterolemic volunteers. This present method produces biological results consistent with those already reported in the literature. Copyright 2004 John Wiley & Sons, Ltd. [source]


    Does nasal decongestion improve obstructive sleep apnea?

    JOURNAL OF SLEEP RESEARCH, Issue 4 2008
    CHRISTIAN F. CLARENBACH
    Summary Whether nasal congestion promotes obstructive sleep apnea is controversial. Therefore, we performed a randomized placebo-controlled cross-over trial on the effects of topical nasal decongestion in patients with obstructive sleep apnea syndrome (OSA) and nasal congestion. Twelve OSA patients with chronic nasal congestion (mean SD age 49.1 11.1 years, apnea/hypopnea index 32.6 24.5/h) were treated with nasal xylometazoline or placebo for 1 week each. At the end of treatment periods, polysomnography including monitoring of nasal conductance by an unobtrusive technique, vigilance by the OSLER test, and symptom scores were assessed. Data from xylometazoline and placebo treatments were compared. Mean nocturnal nasal conductance on xylometazoline was significantly higher than on placebo (8.6 5.3 versus 6.3 5.8 mL s,1Pa,1, P < 0.05) but the apnea/hypopnea index was similar (29.3 32.5/h versus 33.2 32.8/h, P = NS). However, 30,210 min after application of xylometazoline, at the time of the maximal pharmacologic effect, the apnea/hypopnea index was slightly reduced (27.3 30.5/h versus 33.2 33.9/h, P < 0.05). Xylometazoline did not alter sleep quality, sleep resistance time (33.6 8.8 versus 33.4 10.1 min, P = NS) and subjective sleepiness (Epworth score 10.5 3.8 versus 11.8 4.4, P = NS). The reduced apnea/hypopnea index during maximal nasal decongestion by xylometazoline suggests a pathophysiologic link but the efficacy of nasal decongestion was not sufficient to provide a clinically substantial improvement of OSA. ClinicalTrials.gov Identifier is NTC006030474. [source]


    Sleep-Disordered Breathing in Recipients of Implantable Defibrillators

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009
    WOLFRAM GRIMM M.D.
    Study Objectives: To examine the prevalence and clinical significance of sleep-disordered breathing in patients with implantable cardioverter defibrillators (ICD). Methods and Results: Overnight sleep studies were performed in 129 ICD recipients who had no history of sleep apnea. The mean left ventricular ejection fraction (LVEF) was 29 11%. Mild, moderate, and severe sleep apnea was diagnosed in the presence of an apnea/hypopnea index (AHI) of 5,15/h, 15.1,30/h, and >30/h, respectively. No sleep apnea was present in 49 patients (38%), 57 (44%) had central sleep apnea (CSA), and 23 patients (18%) had obstructive sleep apnea (OSA). Mild, moderate, and severe sleep apnea were present in 25%, 31%, and 44% of patients with CSA, compared with 52%, 22%, and 26% of patients with OSA (P < 0.05). LVEF was similar in patients with versus without OSA or CSA. Patients with CSA were significantly older and had a higher prevalence of ischemic cardiomyopathy than patients without sleep apnea. Conclusions: Previously undiagnosed CSA is common in ICD recipients. Severely disordered breathing during sleep was more prevalent among patients with CSA than patients with OSA. This prospective, observational study will examine the long-term clinical significance of sleep-disordered breathing in ICD recipients. [source]