523 research outputs found
Traumatic dental injuries and socioeconomic position â findings from the Children's Dental Health Survey 2013
OBJECTIVES:
The aim of this study was to assess whether traumatic dental injuries (TDI) were socially graded among children and adolescents in England, Wales and Northern Ireland, using nationally representative data from the Children's Dental Health Survey (CDHS) 2013.
METHODS:
This cross-sectional study used data from the Children's Dental Health Survey 2013 which was conducted among a nationally representative sample of schoolchildren in England, Wales and Northern Ireland. Children's family socioeconomic position (SEP) was measured through free school meal eligibility and relative area deprivation using the Indices of Multiple Deprivation. The analytical sample included 6707 schoolchildren aged 8, 12 and 15. Multiple logistic regression was used to model the associations between experience of TDI and the two markers of SEP, after adjusting for sex and age.
RESULTS:
The overall prevalence of traumatic dental injuries to permanent incisors was 9% (n = 590). There were no statistically significant associations between TDI and either SEP measure. Further subgroup analyses (n = 2650) showed also no significant associations between TDI and additional SEP markers (parental education and social class). The odds of having sustained a traumatic dental injury were higher for boys than for girls and were greater in older age groups.
CONCLUSIONS:
This study found no significant relationships between the experience of traumatic dental injuries and two markers of family socioeconomic position among children living in England, Wales and Northern Ireland. This implies that rather than specifically targeting the more deprived sectors of society, TDI prevention policies should use upstream public health strategies incorporating a whole-population approach
HIF-1 alpha-independent hypoxia-induced rapid PTK6 stabilization is associated with increased motility and invasion
© 2014 Landes Bioscience. PTK6/Brk is a non-receptor tyrosine kinase overexpressed in cancer. Here we demonstrate that cytosolic PTK6 is rapidly and robustly induced in response to hypoxic conditions in a HIF-1-independent manner. Furthermore, a proportion of hypoxic PTK6 subsequently re-localized to the cell membrane. We observed that the rapid stabilization of PTK6 is associated with a decrease in PTK6 ubiquitylation and we have identified c-Cbl as a putative PTK6 E3 ligase in normoxia. The consequences of hypoxia-induced PTK6 stabilization and subcellular re-localization to the plasma membrane include increased cell motility and invasion, suggesting PTK6 targeting as a therapeutic approach to reduce hypoxia-regulated metastatic potential. This could have particular significance for breast cancer patients with triple negative disease
Fornix deep brain stimulation enhances acetylcholine levels in the hippocampus
Deep brain stimulation (DBS) of the fornix has gained interest as a potential therapy for advanced treatment-resistant dementia, yet the mechanism of action remains widely unknown. Previously, we have reported beneficial memory effects of fornix DBS in a scopolamine induced rat model of dementia, which is dependent on various brain structures including hippocampus. To elucidate mechanisms of action of fornix DBS with regard to memory restoration, we performed c-Fos immunohistochemistry in the hippocampus. We found that fornix DBS induced a selective activation of cells in the CA1 and CA3 subfields of the dorsal hippocampus. In addition, hippocampal neurotransmitter levels were measured using microdialysis before, during and after 60 min of fornix DBS in a next experiment. We observed a substantial increase in the levels of extracellular hippocampal acetylcholine, which peaked 20 min after stimulus onset. Interestingly, hippocampal glutamate levels did not change compared to baseline. Therefore, our findings provide first experimental evidence that fornix DBS activates the hippocampus and induces the release of acetylcholine in this region.Publisher PDFPeer reviewe
Expansion of bound state energies in powers of m/M and (1-m/M)
Elaborating on a previous letter, we use a new approach to compute energy
levels of a non-relativistic bound-state of two constituents, with masses m and
M, by systematic expansions - one in powers of m/M and another in powers of
(1-m/M). Technical aspects of the calculations are described in detail.
Theoretical predictions are given for O(alpha(Z*alpha)^5) radiative recoil and
O((Z*alpha)^6) pure recoil corrections to the average energy shift and
hyperfine splitting relevant for hydrogen, muonic hydrogen, and muonium.Comment: 9 pages, revte
Measurements of the Casimir-Lifshitz force in fluids: the effect of electrostatic forces and Debye screening
In this work, we present detailed measurements of the Casimir-Lifshitz force
between two gold surfaces (a sphere and a plate) immersed in ethanol and study
the effect of residual electrostatic forces, which are dominated by static
fields within the apparatus and can be reduced with proper shielding.
Electrostatic forces are further reduced by Debye screening through the
addition of salt ions to the liquid. Additionally, the salt leads to a
reduction of the Casimir-Lifshitz force by screening the zero-frequency
contribution to the force; however, the effect is small between gold surfaces
at the measured separations and within experimental error. An improved
calibration procedure is described and compared to previous methods. Finally,
the experimental results are compared to Lifshitz's theory and found to be
consistent for the materials used in the experiment.Comment: 11 figures. PRA in pres
Measurement of the Casimir force between parallel metallic surfaces
We report on the measurement of the Casimir force between conducting surfaces
in a parallel configuration. The force is exerted between a silicon cantilever
coated with chromium and a similar rigid surface and is detected looking at the
shifts induced in the cantilever frequency when the latter is approached. The
scaling of the force with the distance between the surfaces was tested in the
0.5 - 3.0 m range, and the related force coefficient was determined at the
15% precision level.Comment: 4 Figure
Improved Precision Measurement of the Casimir Force
We report an improved precision measurement of the Casimir force. The force
is measured between a large Al coated sphere and flat plate using an Atomic
Force Microscope. The primary experimental improvements include the use of
smoother metal coatings, reduced noise, lower systematic errors and independent
measurement of surface separations. Also the complete dielectric spectrum of
the metal is used in the theory. The average statistical precision remains at
the same 1% of the forces measured at the closest separation
Methods to create a stringent selection system for mammalian cell lines
The efficient establishment of high protein producing recombinant mammalian cell lines is facilitated by the use of a stringent selection system. Here, we describe two methods to create a stringent selection system based on the Zeocin resistance marker. First, we cloned increasingly longer stretches of DNA, encoding a range of 8â131 amino acids immediately upstream of the Zeocin selection marker gene. The DNA stretches were separated from the open reading frame of the selection marker gene by a stopcodon. The idea behind this was that the translation machinery will first translate the small peptide, stop and then restart at the AUG of the Zeocin marker. This process, however, will become less efficient with increasingly longer stretches of DNA upstream of the Zeocin marker that has to be translated first. This would result in lower levels of the Zeocin selection marker protein and thus a higher selection stringency of the system. Secondly, we performed a genetic screen to identify PCR induced mutations in the Zeocin selection protein that functionally impair the selection marker protein. Both the insertion of increasingly longer peptides and several Zeocin selection protein mutants resulted in a decreasing number of stably transfected colonies that concomitantly displayed higher protein expression levels. When the Zeocin mutants were combined with very short small peptides (8â14 amino acids long), this created a flexible, high stringency selection system. The system allows the rapid establishment of few, but high protein producing mammalian cell lines
Heritability of working memory brain activation
Although key to understanding individual variation in task-related brain activation, the genetic contribution to these individual differences remains largely unknown. Here we report voxel-by-voxel genetic model fitting in a large sample of 319 healthy, young adult, human identical and fraternal twins (mean ± SD age, 23.6 ± 1.8 years) who performed an n-back working memory task during functional magnetic resonance imaging (fMRI) at a high magnetic field (4 tesla). Patterns of task-related brain response (BOLD signal difference of 2-back minus 0-back) were significantly heritable, with the highest estimates (40â65%) in the inferior, middle, and superior frontal gyri, left supplementary motor area, precentral and postcentral gyri, middle cingulate cortex, superior medial gyrus, angular gyrus, superior parietal lobule, including precuneus, and superior occipital gyri. Furthermore, high test-retest reliability for a subsample of 40 twins indicates that nongenetic variance in the fMRI brain response is largely due to unique environmental influences rather than measurement error. Individual variations in activation of the working memory network are therefore significantly influenced by genetic factors. By establishing the heritability of cognitive brain function in a large sample that affords good statistical power, and using voxel-by-voxel analyses, this study provides the necessary evidence for task-related brain activation to be considered as an endophenotype for psychiatric or neurological disorders, and represents a substantial new contribution to the field of neuroimaging genetics. These genetic brain maps should facilitate discovery of gene variants influencing cognitive brain function through genome-wide association studies, potentially opening up new avenues in the treatment of brain disorders
Modeling of the hemodynamic responses in block design fMRI studies
The hemodynarnic response function (HRF) describes the local response of brain vasculature to functional activation. Accurate HRF modeling enables the investigation of cerebral blood flow regulation and improves our ability to interpret fMRI results. Block designs have been used extensively as fMRI paradigms because detection power is maximized; however, block designs are not optimal for HRF parameter estimation. Here we assessed the utility of block design fMRI data for HRF modeling. The trueness (relative deviation), precision (relative uncertainty), and identifiability (goodness-of-fit) of different HRF models were examined and test-retest reproducibility of HRF parameter estimates was assessed using computer simulations and fMRI data from 82 healthy young adult twins acquired on two occasions 3 to 4 months apart. The effects of systematically varying attributes of the block design paradigm were also examined. In our comparison of five HRF models, the model comprising the sum of two gamma functions with six free parameters had greatest parameter accuracy and identifiability. Hemodynamic response function height and time to peak were highly reproducible between studies and width was moderately reproducible but the reproducibility of onset time was low. This study established the feasibility and test-retest reliability of estimating HRF parameters using data from block design fMRI studies
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