121 research outputs found
Impaired Endothelium-dependent Vasodilation in Overweight and Obese Adult Humans is Not Limited to Muscarinic Receptor Agonists
Muscarinic receptor agonists have primarily been used to characterize endothelium-dependent vasodilator dysfunction with overweight/obesity. Reliance on a single class of agonist, however, yields limited, and potentially misleading, information regarding endothelial vasodilator capacity. The aims of this study were to determine 1) whether the overweight/obesity-related reduction in endothelium-dependent vasodilation extends beyond muscarinic receptor agonists and 2) whether the contribution of nitric oxide (NO) to endothelium-dependent vasodilation is reduced in overweight/obese adults. Eighty-six middle-aged and older adults were studied: 42 normal-weight (54 +/- 1 yr, 21 men and 21 women, body mass index = 23.4 +/- 0.3 kg/m(2)) and 44 overweight/obese (54 +/- 1 yr, 28 men and 16 women, body mass index = 30.3 +/- 0.6 kg/m(2)) subjects. Forearm blood flow (FBF) responses to intra-arterial infusions of acetylcholine in the absence and presence of the endothelial NO synthase inhibitor N(G)-monomethyl-l-arginine, methacholine, bradykinin, substance P, isoproterenol, and sodium nitroprusside were measured by strain-gauge plethysmography. FBF responses to each endothelial agonist were significantly blunted in the overweight/obese adults. Total FBF (area under the curve) to acetylcholine (50 +/- 5 vs. 79 +/- 4 ml/100 ml tissue), methacholine (55 +/- 4 vs. 86 +/- 5 ml/100 ml tissue), bradykinin (62 +/- 5 vs. 85 +/- 4 ml/100 ml tissue), substance P (37 +/- 4 vs. 57 +/- 5 ml/100 ml tissue), and isoproterenol (62 +/- 4 vs. 82 +/- 6 ml/100 ml tissue) were 30%-40% lower in the overweight/obese than normal-weight adults. N(G)-monomethyl-l-arginine significantly reduced the FBF response to acetylcholine to the same extent in both groups. There were no differences between the groups in the FBF responses to sodium nitroprusside. These results indicate that agonist-stimulated endothelium-dependent vasodilation is universally impaired with overweight/obesity. Moreover, this impairment appears to be independent of NO
A Systematic Review of Dental Disease in Patients Undergoing Cancer Therapy
Introduction: The purpose of this systematic review was to evaluate the literature and update our current understanding of the impact of present cancer therapies on the dental apparatus (teeth and periodontium) since the 1989 NIH Development Consensus Conference on the Oral Complications of Cancer Therapies.
Review Method: A systematic literature search was conducted with assistance from a research librarian in the databases MEDLINE/PubMed and EMBASE for articles published between 1 January 1990 and 31 December 2008. Each study was independently assessed by two reviewers. Taking into account predetermined quality measures, a weighted prevalence was calculated for the prevalence of dental caries, severe gingival disease, and dental infection. Data on DMFT/dmft, DMFS/dmfs, plaque, and gingival indexes were also gathered. The level of evidence, recommendation, and guideline (if possible) were given for published preventive and management strategies.
Results: Sixty-four published papers between 1990 and 2008 were reviewed. The weighted overall prevalence of dental caries was 28.1%. The overall DMFT for patients who were post-antineoplastic therapy was 9.19 (SD, 7.98; n=457). The overall plaque index for patients who were postantineoplastic therapy was 1.38 (SD, 0.25; n=189). The GI for patients who were post-chemotherapy was 1.02 (SD, 0.15; n=162). The weighted prevalence of dental infections/ abscess during chemotherapy was reported in three studies and was 5.8%.
Conclusions: Patients who were post-radiotherapy had the highest DMFT. The use of fluoride products and chlorhexidine rinses are beneficial in patients who are post-radiotherapy. There continues to be lack of clinical studies on the extent and severity of dental disease that are associated with infectious complications during cancer therapy
Basal Endothelial Nitric Oxide Release is Preserved in Overweight and Obese Adults
OBJECTIVE: Impaired basal nitric oxide release is associated with a number of cardiovascular disorders including hypertension, arterial spasm, and myocardial infarction. We determined whether basal endothelial nitric oxide release is reduced in otherwise healthy overweight and obese adult humans.RESEARCH METHODS AND PROCEDURES: Seventy sedentary adults were studied: 32 normal weight (BMI/m(2)), 24 overweight (BMI \u3e or = 25 \u3c 30 kg/m(2)), and 14 obese (BMI \u3e or = 30 kg/m(2)). Forearm blood flow (FBF) responses to intra-arterial infusions of N(g)-monomethyl-L-arginine (5 mg/min), a nitric oxide synthase inhibitor, were used as an index of basal nitric oxide release.RESULTS: N(g)-monomethyl-L-arginine elicited significant reductions in FBF in the normal weight (from 4.1 +/- 0.2 to 2.7 +/- 0.2 mL/100 mL tissue/min), overweight (4.1 +/- 0.1 to 2.8 +/- 0.2 mL/100 mL tissue/min), and obese (3.9 +/- 0.3 to 2.7 +/- 0.2 mL/100 mL tissue/min) subjects. Importantly, the magnitude of reduction in FBF (approximately 30%) was similar among the groups.DISCUSSION: These results indicate that the capacity of the endothelium to release nitric oxide under basal conditions is not compromised in overweight and obese adults
Aging and Endothelial Progenitor Cell Telomere Length in Healthy Men
BACKGROUND: Telomere length declines with age in mature endothelial cells and is thought to contribute to endothelial dysfunction and atherogenesis. Bone marrow-derived circulating endothelial progenitor cells (EPCs) are critical to vascular health as they contribute to both reendothelialization and neovascularization. We tested the hypothesis that EPC telomere length decreases with age in healthy adult humans.METHODS: Peripheral blood samples were collected from 40 healthy, non-obese, sedentary men: 12 young (age 21-34 years), 12 middle-aged (43-55 years) and 16 older (57-68 years). Putative EPCs were isolated from peripheral blood mononuclear cells and telomere length was determined using genomic DNA preparation and Southern hybridization techniques.RESULTS: EPC telomere length (base pairs) was approximately 20% (p=0.01) lower in the older (8492+523 bp) compared to the middle-aged (10,565+572 bp) and young (10,205+501 bp) men. Of note, there was no difference in EPC telomere length between the middle-aged and young men.CONCLUSIONS: These results demonstrate that EPC telomere length declines with age in healthy, sedentary men. Interestingly, telomere length was well preserved in the middle-aged compared to young men, suggesting that EPC telomere shortening occurs after the age of 55 years
Aging and Endothelial Progenitor Cell Telomere Length in Healthy Men
BACKGROUND: Telomere length declines with age in mature endothelial cells and is thought to contribute to endothelial dysfunction and atherogenesis. Bone marrow-derived circulating endothelial progenitor cells (EPCs) are critical to vascular health as they contribute to both reendothelialization and neovascularization. We tested the hypothesis that EPC telomere length decreases with age in healthy adult humans.
METHODS: Peripheral blood samples were collected from 40 healthy, non-obese, sedentary men: 12 young (age 21-34 years), 12 middle-aged (43-55 years) and 16 older (57-68 years). Putative EPCs were isolated from peripheral blood mononuclear cells and telomere length was determined using genomic DNA preparation and Southern hybridization techniques.
RESULTS: EPC telomere length (base pairs) was approximately 20% (p=0.01) lower in the older (8492+523 bp) compared to the middle-aged (10,565+572 bp) and young (10,205+501 bp) men. Of note, there was no difference in EPC telomere length between the middle-aged and young men.
CONCLUSIONS: These results demonstrate that EPC telomere length declines with age in healthy, sedentary men. Interestingly, telomere length was well preserved in the middle-aged compared to young men, suggesting that EPC telomere shortening occurs after the age of 55 years
NMR multiple quantum coherences in quasi-one-dimensional spin systems: Comparison with ideal spin-chain dynamics
The 19F spins in a crystal of fluorapatite have often been used to
experimentally approximate a one-dimensional spin system. Under suitable
multi-pulse control, the nuclear spin dynamics may be modeled to first
approximation by a double-quantum one-dimensional Hamiltonian, which is
analytically solvable for nearest-neighbor couplings. Here, we use solid-state
nuclear magnetic resonance techniques to investigate the multiple quantum
coherence dynamics of fluorapatite, with an emphasis on understanding the
region of validity for such a simplified picture. Using experimental,
numerical, and analytical methods, we explore the effects of long-range
intra-chain couplings, cross-chain couplings, as well as couplings to a spin
environment, all of which tend to damp the oscillations of the multiple quantum
coherence signal at sufficiently long times. Our analysis characterizes the
extent to which fluorapatite can faithfully simulate a one-dimensional quantum
wire.Comment: 14 pages, 11 eps color figure
Near and Mid-IR Photometry of the Pleiades, and a New List of Substellar Candidate Members
We make use of new near and mid-IR photometry of the Pleiades cluster in
order to help identify proposed cluster members. We also use the new photometry
with previously published photometry to define the single-star main sequence
locus at the age of the Pleiades in a variety of color-magnitude planes.
The new near and mid-IR photometry extend effectively two magnitudes deeper
than the 2MASS All-Sky Point Source catalog, and hence allow us to select a new
set of candidate very low mass and sub-stellar mass members of the Pleiades in
the central square degree of the cluster. We identify 42 new candidate members
fainter than Ks =14 (corresponding to 0.1 Mo). These candidate members should
eventually allow a better estimate of the cluster mass function to be made down
to of order 0.04 solar masses.
We also use new IRAC data, in particular the images obtained at 8 um, in
order to comment briefly on interstellar dust in and near the Pleiades. We
confirm, as expected, that -- with one exception -- a sample of low mass stars
recently identified as having 24 um excesses due to debris disks do not have
significant excesses at IRAC wavelengths. However, evidence is also presented
that several of the Pleiades high mass stars are found to be impacting with
local condensations of the molecular cloud that is passing through the Pleiades
at the current epoch.Comment: Accepted to ApJS; data tables and embedded-figure version available
at http://spider.ipac.caltech.edu/staff/stauffer/pleiades07
Spitzer/IRAC Photometry of M, L, and T Dwarfs
We present the results of a program to acquire photometry for eighty-six
late-M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer
Space Telescope. We examine the behavior of these cool dwarfs in various
color-color and color-magnitude diagrams composed of near-IR and IRAC data. The
T dwarfs exhibit the most distinctive positions in these diagrams. In M_5.8
versus [5.8]-[8.0], the IRAC data for T dwarfs are not monotonic in either
magnitude or color, giving the clearest indication yet that the T dwarfs are
not a one parameter family in Teff. Because metallicity does not vary enough in
the solar neighborhood to act as the second parameter, the most likely
candidate then is gravity, which in turn translates to mass. Among objects with
similar spectral type, the range of mass suggested by our sample is about a
factor of five (~70 M_Jup to ~15 M_Jup), with the less massive objects making
up the younger members of the sample. We also find the IRAC 4.5 micron fluxes
to be lower than expected, from which we infer a stronger CO fundamental band
at ~4.67 microns. This suggests that equilibrium CH_4/CO chemistry
underestimates the abundance of CO in T dwarf atmospheres, confirming earlier
results based on M-band observations from the ground. In combining IRAC
photometry with near-IR JHK photometry and parallax data, we find the
combination of Ks, IRAC 3.6 micron, and 4.5 micron bands to provide the best
color-color discrimination for a wide range of M, L, and T dwarfs. Also
noteworthy is the M_Ks versus Ks-[4.5] relation, which shows a smooth
progression over spectral type and splits the M, L, and T types cleanly.Comment: 32 pages, 18 figures, accepted for publication to ApJ: revised to
adjust acknowledgments, add a few more references, and the correct
typographical errors in text and tables 1 and 3 (note as binaries
sds0926+5847 and 2ma1553+1532
Recommended from our members
Numerical Prediction of Submesoscale Flow in the Nocturnal Stable Boundary Layer over Complex Terrain
Numerical weather prediction models often perform poorly for weakly forced, highly variable winds in nocturnal stable boundary layers (SBLs). When used as input to air-quality and dispersion models, these wind errors can lead to large errors in subsequent plume forecasts. Finer grid resolution and improved model numerics and physics can help reduce these errors. The Advanced Research Weather Research and Forecasting model (ARW-WRF) has higher-order numerics that may improve predictions of finescale winds (scales <~20 km) in nocturnal SBLs. However, better understanding of the physics controlling SBL flow is needed to take optimal advantage of advanced modeling capabilities.
To facilitate ARW-WRF evaluations, a small network of instrumented towers was deployed in the ridge-and-valley topography of central Pennsylvania (PA). Time series of local observations and model forecasts on 1.333- and 0.444-km grids were filtered to isolate deterministic lower-frequency wind components. The time-filtered SBL winds have substantially reduced root-mean-square errors and biases, compared to raw data. Subkilometer horizontal and very fine vertical resolutions are found to be important for reducing model speed and direction errors. Nonturbulent fluctuations in unfiltered, very finescale winds, parts of which may be resolvable by ARW-WRF, are shown to generate horizontal meandering in stable weakly forced conditions. These submesoscale motions include gravity waves, primarily horizontal 2D motions, and other complex signatures. Vertical structure and low-level biases of SBL variables are shown to be sensitive to parameter settings defining minimum “background” mixing in very stable conditions in two representative turbulence schemes.Keywords: Numerical weather prediction/forecasting, Boundary laye
Accretion of Planetary Material onto Host Stars
Accretion of planetary material onto host stars may occur throughout a star's
life. Especially prone to accretion, extrasolar planets in short-period orbits,
while relatively rare, constitute a significant fraction of the known
population, and these planets are subject to dynamical and atmospheric
influences that can drive significant mass loss. Theoretical models frame
expectations regarding the rates and extent of this planetary accretion. For
instance, tidal interactions between planets and stars may drive complete
orbital decay during the main sequence. Many planets that survive their stars'
main sequence lifetime will still be engulfed when the host stars become red
giant stars. There is some observational evidence supporting these predictions,
such as a dearth of close-in planets around fast stellar rotators, which is
consistent with tidal spin-up and planet accretion. There remains no clear
chemical evidence for pollution of the atmospheres of main sequence or red
giant stars by planetary materials, but a wealth of evidence points to active
accretion by white dwarfs. In this article, we review the current understanding
of accretion of planetary material, from the pre- to the post-main sequence and
beyond. The review begins with the astrophysical framework for that process and
then considers accretion during various phases of a host star's life, during
which the details of accretion vary, and the observational evidence for
accretion during these phases.Comment: 18 pages, 5 figures (with some redacted), invited revie
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