2,238 research outputs found
Severe Lumbar Disability Is Associated With Decreased Psoas Cross-Sectional Area in Degenerative Spondylolisthesis
Study Design: Retrospective cohort. Objectives: Alterations in lumbar paraspinal muscle cross-sectional area (CSA) may correlate with lumbar pathology. The purpose of this study was to compare paraspinal CSA in patients with degenerative spondylolisthesis and severe lumbar disability to those with mild or moderate lumbar disability, as determined by the Oswestry Disability Index (ODI). Methods: We retrospectively reviewed the medical records of 101 patients undergoing lumbar fusion for degenerative spondylolisthesis. Patients were divided into ODI score ≤40 (mild/moderate disability, MMD) and ODI score \u3e40 (severe disability, SD) groups. The total CSA of the psoas and paraspinal muscles were measured on preoperative magnetic resonance imaging (MRI). Results: There were 37 patients in the SD group and 64 in the MMD group. Average age and body mass index were similar between groups. For the paraspinal muscles, we were unable to demonstrate any significant differences in total CSA between the groups. Psoas muscle CSA was significantly decreased in the SD group compared with the MMD group (1010.08 vs 1178.6 mm2, P =.041). Multivariate analysis found that psoas CSA in the upper quartile was significantly protective against severe disability (P =.013). Conclusions: We found that patients with severe lumbar disability had no significant differences in posterior lumbar paraspinal CSA when compared with those with mild/moderate disability. However, severely disabled patients had significantly decreased psoas CSA, and larger psoas CSA was strongly protective against severe disability, suggestive of a potential association with psoas atrophy and worsening severity of lumbar pathology. © The Author(s) 2018
Outcome of periacetabular osteotomy for the management of acetabular dysplasia: experience in an academic centre.
Periacetabular osteotomy (PAO) is a very effective reconstructive procedure for treatment of acetabular dysplasia. An orthopaedic paediatric surgeon and a reconstructive hip arthroplasty surgeon performed this procedure together in the early phase of their learning curve and then performed it individually. The early clinical and radiographic results of 85 consecutive PAOs performed in this academic orthopaedic unit were reviewed. The mean Merle-d\u27Aubigné score increased from 12.4 preoperatively to 16 at follow-up. Pre-operatively 73 hips were anteverted and 12 were neutral or retroverted. The mean angle of Wiberg improved from 5 degrees to 21 degrees (p \u3c 0.0001) in anteverted hips, and from 9 degrees to 30 degrees in neutral or retroverted hips. The mean angle of Lequesne and de Sèze improved from 6 degrees to 35 degrees (p \u3c 0.0001) in anteverted hips, and in neutral or retroverted hips from 9 degrees to 30 degrees (p \u3c 0.0001). The acetabular index improved from 26 degrees to 8 degrees (p \u3c 0.0001) in anteverted hips, and from 21 degrees to 7 degrees (p \u3c 0.0001) in neutral or retroverted hips. Over the 7 year period the blood loss and operative time improved from 2000 ml to 900 ml and 4 hours to 2 hours respectively. Four hips (four patients) required conversion to total hip replacement. The radiographic correction and improved clinical scores are similar to those in previous studies. This study shows a survival rate of 94% at 58 months following periacetabular osteotomy. The learning curve and the early results of this procedure performed in our academic unit are encouraging
The Natural History and Clinical Syndromes of Degenerative Cervical Spondylosis
Cervical spondylosis is a broad term which describes the age related chronic disc degeneration, which can also affect the cervical vertebrae, the facet and other joints and their associated soft tissue supports. Evidence of spondylitic change is frequently found in many asymptomatic adults. Radiculopathy is a result of intervertebral foramina narrowing. Narrowing of the spinal canal can result in spinal cord compression, ultimately resulting in cervical spondylosis myelopathy. This review article examines the current literature in relation to the cervical spondylosis and describes the three clinical syndromes of axial neck pain, cervical radiculopathy and cervical myelopath
Nonoperative Modalities to Treat Symptomatic Cervical Spondylosis
Cervical spondylosis is a common and disabling condition. It is generally felt that
the initial management should be nonoperative, and these modalities include
physiotherapy, analgesia and selective nerve root injections. Surgery should be
reserved for moderate to severe myelopathy patients who have failed a period of
conservative treatment and patients whose symptoms are not adequately controlled by
nonoperative means. A review of the literature supporting various modalities of
conservative management is presented, and it is concluded that although effective,
nonoperative treatment is labour intensive, requiring regular review and careful
selection of medications and physical therapy on a case by case basis
Mid-infrared Period-Luminosity Relations of RR Lyrae Stars Derived from the WISE Preliminary Data Release
Interstellar dust presents a significant challenge to extending
parallax-determined distances of optically observed pulsational variables to
larger volumes. Distance ladder work at mid-infrared wavebands, where dust
effects are negligible and metallicity correlations are minimized, have been
largely focused on few-epoch Cepheid studies. Here we present the first
determination of mid-infrared period-luminosity (PL) relations of RR Lyrae
stars from phase-resolved imaging using the preliminary data release of the
Wide-Field Infrared Survey Explorer (WISE). We present a novel statistical
framework to predict posterior distances of 76 well-observed RR Lyrae that uses
the optically constructed prior distance moduli while simultaneously imposing a
power-law PL relation to WISE-determined mean magnitudes. We find that the
absolute magnitude in the bluest WISE filter is M_W1 = (-0.421+-0.014) -
(1.681+-0.147)*log(P/0.50118 day), with no evidence for a correlation with
metallicity. Combining the results from the three bluest WISE filters, we find
that a typical star in our sample has a distance measurement uncertainty of
0.97% (statistical) plus 1.17% (systematic). We do not fundamentalize the
periods of RRc stars to improve their fit to the relations. Taking the
Hipparcos-derived mean V-band magnitudes, we use the distance posteriors to
determine a new optical metallicity-luminosity relation which we present in
Section 5. The results of this analysis will soon be tested by HST parallax
measurements and, eventually, with the Gaia astrometric mission.Comment: 33 pages, 12 figures, 2 tables. Accepted for publication in ApJ, June
27th, 201
Translating Hemoglobin A1c Scores across an Ethnically Diverse Population: Is the Language Consistent across All Races?
Hemoglobin A1c testing is an accepted measure of how well the blood glucose level has been controlled in the recent past (six to eight weeks) among individuals with diabetes. The purpose of this study was to evaluate the relationship between hemoglobin A1c (HbA1c) and blood glucose in an ethnically diverse population in a clinical setting. A cross-sectional research design was employed to explore associations between these two diabetes control measures in a sample of African American, White and Hispanic patients receiving diabetes treatment and follow-up in an outpatient clinic in Tallahassee, Florida. Data collection included a questionnaire, medical examinations, and lab results. Although we found a significant association between the glucose level and the HbA1c levels, the A1c value did not predict the mean glucose value as closely as previously found in less diverse groups. These findings suggest there is need for further study of these two variables among minority groups
A Bayesian Approach to Calibrating Period-Luminosity Relations of RR Lyrae Stars in the Mid-Infrared
A Bayesian approach to calibrating period-luminosity (PL) relations has
substantial benefits over generic least-squares fits. In particular, the
Bayesian approach takes into account the full prior distribution of the model
parameters, such as the a priori distances, and refits these parameters as part
of the process of settling on the most highly-constrained final fit.
Additionally, the Bayesian approach can naturally ingest data from multiple
wavebands and simultaneously fit the parameters of PL relations for each
waveband in a procedure that constrains the parameter posterior distributions
so as to minimize the scatter of the final fits appropriately in all wavebands.
Here we describe the generalized approach to Bayesian model fitting and then
specialize to a detailed description of applying Bayesian linear model fitting
to the mid-infrared PL relations of RR Lyrae variable stars. For this example
application we quantify the improvement afforded by using a Bayesian model fit.
We also compare distances previously predicted in our example application to
recently published parallax distances measured with the Hubble Space Telescope
and find their agreement to be a vindication of our methodology. Our intent
with this article is to spread awareness of the benefits and applicability of
this Bayesian approach and encourage future PL relation investigations to
consider employing this powerful analysis method.Comment: 6 pages, 1 figure. Accepted for publication in Astrophysics & Space
Science. Following a presentation at the conference The Fundamental Cosmic
Distance Scale: State of the Art and the Gaia Perspective, Naples, May 201
Polymorphisms in Methionine Synthase, Methionine Synthase Reductase and Serine Hydroxymethyltransferase, Folate and Alcohol Intake, and Colon Cancer Risk
Background/Aims - We examined associations among folate and alcohol intake, SNPs in genes involved in one-carbon metabolism and colon cancer risk.
Methods - Colon cancer cases (294 African Americans and 349 whites) were frequency matched to population controls (437 African Americans and 611 whites) by age, race and sex from 33 North Carolina counties from 1996 to 2000. Folate and alcohol intakes were collected by dietary interview. Five SNPs were genotyped using DNA from whole blood: SHMT C1420T; MTRR A66G; MTR A2756G, and the previously-reported MTHFR C677T and MTHFR A1298C. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression.
Results - An inverse association was observed for SHMT TT genotype as compared to CC genotype in whites (OR=0.6, 95%CI=0.4, 1.0), but not in African Americans. Inverse associations were observed for high folate intake in individuals carrying 0 or 1 variant allele [OR 0.2 (95%CI 0.06-0.8) for African Americans; OR 0.2 (95%CI 0.1-0.6) for whites] compared to low folate intake. Modest interactions between these SNPs and alcohol or folate intakes were observed.
Conclusions - Our results are consistent with other findings and provide needed data on these associations among African Americans
A New 24 micron Phase Curve for upsilon Andromedae b
We report the detection of 24 micron variations from the planet-hosting
upsilon Andromedae system consistent with the orbital periodicity of the
system's innermost planet, upsilon And b. We find a peak-to-valley phase curve
amplitude of 0.00130 times the mean system flux. Using a simple model with two
hemispheres of constant surface brightness and assuming a planetary radius of
1.3 Jupiter radii gives a planetary temperature contrast of >900 K and an
orbital inclination of >28 degrees. We further report the largest phase offset
yet observed for an extrasolar planet: the flux maximum occurs ~80 degrees
before phase 0.5. Such a large phase offset is difficult to reconcile with most
current atmospheric circulation models. We improve on earlier observations of
this system in several important ways: (1) observations of a flux calibrator
star demonstrate the MIPS detector is stable to 10^-4 on long timescales, (2)
we note that the background light varies systematically due to spacecraft
operations, precluding use of this background as a flux calibrator (stellar
flux measured above the background is not similarly affected), and (3) we
calibrate for flux variability correlated with motion of the star on the MIPS
detector. A reanalysis of our earlier observations of this system is consistent
with our new result.Comment: Submitted to ApJ. 15 pages, 6 figures, 4 table
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