6,816 research outputs found
Nutritional status of young children with inherited blood disorders in western Kenya.
To determine the association between a range of inherited blood disorders and indicators of poor nutrition, we analyzed data from a population-based, cross-sectional survey of 882 children 6–35 months of age in western Kenya. Of children with valid measurements, 71.7% were anemic (hemoglobin < 11 g/dL), 19.1% had ferritin levels < 12 μg/L, and 30.9% had retinol binding protein (RBP) levels < 0.7 μmol/L. Unadjusted analyses showed that compared with normal children, homozygous α(+)-thalassemia individuals had a higher prevalence of anemia (82.3% versus 66.8%, P = 0.001), but a lower prevalence of low RBP (20.5% versus 31.4%, P = 0.024). In multivariable analysis, homozygous α(+)-thalassemia remained associated with anemia (adjusted odds ratio [aOR] = 1.8, P = 0.004) but not with low RBP (aOR = 0.6, P = 0.065). Among young Kenyan children, α(+)-thalassemia is associated with anemia, whereas G6PD deficiency, haptoglobin 2-2, and HbS are not; none of these blood disorders are associated with iron deficiency, vitamin A deficiency, or poor growth
Quiet Eye Training in a Visuomotor Control Task
Introduction: Several researchers have reported the importance of maintaining a longer final fixation on the target (termed the quiet eye period, QE) prior to performing an aiming task. We present an innovative, perceptual training intervention intended to improve the efficiency of gaze behavior (i.e., QE) in shotgun shooting. Methods: A sample of 20 International-level, skeet shooters were assigned equally to one of two, matched-ability groups based on their pre-test shooting scores. A perceptual training group participated in a 4-step, pre-shot routine, alongside three video feedback sessions involving their own gaze behaviors and those of an expert model in an effort to influence positively QE behaviors. A control group received video feedback of performance, but without the addition of feedback on QE behaviors. Participants completed pre- and post-tests along with an 8-week training intervention. Results: The perceptual training group significantly increased its mean QE duration (397 cw 423 ms), employed an earlier onset of QE (257 cw 244 ms), and recorded higher shooting accuracy scores (62 cw 70 %) from pre- to post-test. Participants in the perceptual training group significantly reduced gun barrel displacement and absolute peak velocity on the post- compared to the pre-test, even though neither variable was overtly trained. A transfer test, based on performance during competition, indicated that perceptual training significantly improved shooting accuracy pre- to post-intervention. No pre- to post-test differences were observed for the control group on the measures reported. Conclusion: The results demonstrate the effectiveness of QE training in improving shooting accuracy and developing a more efficient visuo-motor control strategy. Findings have implications for future research on training visuo-motor behaviors, attention and gaze orientation during the performance of aiming tasks
Anxiety, Movement Kinematics, and Visual Attention in Elite-Level Performers
We tested the predictions of Attentional Control Theory (ACT) by examining the effect of anxiety on attention control and the subsequent influence on both performance effectiveness and performance efficiency within a perceptual-motor context. A sample (N = 16) of elite shotgun shooters was tested under counterbalanced low (practice) and high (competition) anxiety conditions. A head-mounted, corneal reflection system allowed point of gaze to be calculated in relation to the scene, while motion of the gun was evaluated using markers placed on the barrel which were captured by two stationary cameras and analyzed using optical tracking software. The quiet eye (QE) duration and onset were analyzed along with gun barrel displacement and variability; performance outcome scores (successful vs. unsuccessful) were also recorded. QE (Vickers, 1996) is defined as the final fixation or tracking gaze that is located on a specific location/object in the visual display for a minimum of 100 ms. Longer QE durations have been linked to successful performance in previous research involving aiming tasks. Participants demonstrated shorter quiet eye durations, and less efficient gun motion, along with a decreased performance outcome (fewer successful trials) under high compared with low anxiety conditions. The data support the predictions of ACT with anxiety disrupting control processes such that goal-directed attention was compromised, leading to a significant impairment in performance effectiveness
Pulse Wave Calibration and Implications for Blood Pressure Measurement: Systematic Review and Meta-Analysis
Central aortic systolic pressure (CASP) can be estimated via filtering of the peripheral pulse wave (PPW) following calibration to brachial blood pressure. Recent studies suggest PPW calibration to mean arterial pressure (MAP) and diastolic BP (DBP) provides more accurate CASP estimates (CASPMD) versus conventional calibration to systolic BP (SBP) and DBP (CASPSD). However, the peak of the MAP-DBP calibrated PPW, that is, SBPMD, is rarely reported or used for BP amplification calculations, despite CASPMD being derived from it. We aimed to calculate the unreported SBPMD from studies using MAP-DBP calibration for estimation of CASPMD and compared it with oscillometric brachial SBP (brSBP). Medline database was searched to March 18, 2020. Meta-analysis includes studies reporting noninvasive CASPSD, CASPMD, brSBP, and brachial DBP. SBPMD was calculated using linear function equations. Data from 21 studies used 8 different BP monitors (13 460 participants, mean age: 54±10 years, 57% female, brachial blood pressure: 130±14/79±9 mm Hg). Weighted mean difference between SBPMD and brSBP was 10 mm Hg (range, -2 to 17 mm Hg) and appeared device specific. Calibration of brachial versus radial PPWs to brachial blood pressure showed a greater disparity between SBPMD and brSBP (14 versus 2 mm Hg). BP amplification was similar comparing SBP-DBP versus MAP-DBP calibrations (brSBP-CASPSD versus SBPMD-CASPMD: 9 versus 11 mm Hg), with no instances of reverse BP amplification. PPWs calibrated to MAP-DBP to derive CASPMD generates SBPMD that differs markedly from brSBP with some oscillometric BP monitors. These findings have important implications for BP monitor accuracy, BP amplification, PPW calibration recommendations, and studies of associations between CASP versus SBP and outcomes
Identifying and treating high blood pressure in men under 55 years with grade 1 hypertension: the TREAT CASP study and RCT
Background:
There is uncertainty regarding whether or not younger (i.e. aged < 55 years), low-risk patients with grade 1 hypertension (i.e. a clinic blood pressure of 140–159/90–99 mmHg) should be treated with blood pressure-lowering medication. This is a heterogeneous group of patients because of variation in systolic/pulse pressure amplification from the central aorta to the brachial artery. It is hypothesised that within grade 1 hypertension, patients can be divided into those with high central aortic systolic pressure and those with low central aortic systolic pressure.
Objectives:
The aims of this study were to (1) evaluate whether or not non-invasive central aortic systolic pressure measurement can better identify younger patients with grade 1 hypertension, who are more likely to have an increased left ventricular mass index; and (2) determine whether or not blood pressure lowering regresses early cardiac structural change in patients with high central aortic systolic pressure.
Setting:
A university hospital with satellite primary care recruitment sites.
Participants:
A total of 726 men (aged 18 to < 55 years) were screened to identify 162 men with grade 1 hypertension and low or high central aortic systolic pressure. Blood pressure status was classified according to seated clinic blood pressure, central aortic systolic pressure and 24-hour ambulatory blood pressure.
Design:
(1) Evaluating the strength of the correlation between central aortic systolic pressure, clinic blood pressure and 24-hour ambulatory blood pressure with left ventricular mass index in 162 patients; (2) a 12-month randomised controlled trial in patients with grade 1 hypertension and high central aortic systolic pressure (i.e. a central aortic systolic pressure of ≥ 125 mmHg) (n = 105), using a prospective, open, blinded, end-point design; and (3) a 12-month observational study in 57 patients with grade 1 hypertension and low central aortic systolic pressure (i.e. a central aortic systolic pressure of < 125 mmHg).
Interventions:
Randomised controlled trial – patients with high central aortic systolic pressure randomised to blood pressure lowering medication (50–100 mg of losartan ± 5–10 mg of amlodipine once daily) versus usual care (no treatment) for 12 months.
Main outcomes:
Randomised controlled trial primary end point – change in left ventricular mass index as measured by cardiac magnetic resonance imaging, comparing treatment with no treatment.
Results:
(1) At baseline, left ventricular mass index was higher in men with high central aortic systolic pressure than in those with low central aortic systolic pressure (mean ± standard deviation 67.9 ± 8.8 g/m2 vs. 64.0 ± 8.5 g/m2; difference 4.0 g/m2, 95% confidence interval 1.1 to 6.9 g/m2; p < 0.01). Central aortic systolic pressure was not superior to clinic blood pressure as a determinant of left ventricular mass index. Univariate analysis, regression coefficients and slopes for left ventricular mass index were similar for clinic systolic blood pressure, ambulatory systolic blood pressure and central aortic systolic pressure. (2) In the randomised controlled trial, blood pressure-lowering treatment reduced central aortic systolic pressure (–21.1 mmHg, 95% confidence interval – 24.4 to –17.9 mmHg; p < 0.001) and clinic systolic blood pressure (–20.0 mmHg, 95% confidence interval – 23.3 to –16.6 mmHg; p < 0.001) versus no treatment. Treatment was well tolerated and associated with a greater change (i.e. from baseline to study closeout) in left ventricular mass index versus no treatment [–3.3 g/m2 (95% confidence interval –4.5 to –2.2 g/m2) vs. –0.9 g/m2 (95% confidence interval –1.7 to –0.2 g/m2); p < 0.01], with a medium-to-large effect size (Cohen’s d statistic –0.74). (3) Patients with low central aortic systolic pressure had no significant change in left ventricular mass index after 12 months (mean change –0.5 g/m2, 95% confidence interval –1.2 to 0.2 g/m2; p = 0.18).
Conclusions:
Men with grade 1 hypertension and high central aortic systolic pressure tended to have higher clinic blood pressure and more hypertension-mediated cardiac structural change than those with low central aortic systolic pressure. Central aortic systolic pressure was not superior to clinic blood pressure or ambulatory blood pressure at stratifying risk of increased left ventricular mass index. Blood pressure-lowering treatment led to a regression of left ventricular mass index in men with grade 1 hypertension and high central aortic systolic pressure compared with no treatment.
Limitations:
The study was limited to a moderate sample of men and there was a low prevalence of very high amplification
Resolution requirements for numerical simulations of transition
The resolution requirements for direct numerical simulations of transition to turbulence are investigated. A reliable resolution criterion is determined from the results of several detailed simulations of channel and boundary-layer transition
Vacuum phototriodes for the CMS electromagnetic calorimeter endcap
The measurement of scintillation light from the lead tungstate crystals of the Compact Muon Solenoid (CMS) electromagnetic calorimeter (ECAL) poses a substantial technical challenge, particularly in the endcap regions, where the radiation levels are highest. The photodetectors must be fast, sensitive, radiationhard, and operate with significant internal gain in a magnetic field of 4 Tesla. The measured performance characteristics of the first batches of series production vacuum phototriodes (VPT), developed to satisfy the needs of CMS, will be described
Thermo-mechanical analysis of dental silicone polymers
Soft lining materials are used to replace the inner surface of a conventional complete denture, especially for weak elderly patients, with delicate health who cannot tolerate the hard acrylic denture base. Most of these patients have fragile supporting mucosa, excessive residual ridge resorption, particularly on the mandibular arch. The application of a soft liner to the mandibular denture allows absorbing impact forces during mastication and relieving oral mucosa. Actually, the silicone rubbers constitute the main family of commercialised soft lining materials. This study was conducted to understand the relationships between the mechanical properties and the physical structure of polysiloxanes. For this purpose, a series of polysiloxanes of various chemical compositions have been investigated. The evolution of their physical structure as a function of temperature has been followed by differential scanning calorimetry (DSC). In order to facilitate comparisons, the mechanical modulus has been analysed upon the same heating rate using dynamic mechanical analysis (DMA). Polysiloxanes actually commercialised as soft denture liners are three-dimensional networks: the flexibility of chains allows a crystalline organisation in an amorphous phase leading to the low value of the shear modulus. The dynamic mechanical analysis shows that they are used in the rubbery state. So, polysiloxanes have steady mechanical properties during physiological utilisation
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Disrupted iron regulation in the brain and periphery in cocaine addiction
Stimulant drugs acutely increase dopamine neurotransmission in the brain, and chronic use leads to neuroadaptive changes in the mesolimbic dopamine system and morphological changes in basal ganglia structures. Little is known about the mechanisms underlying these changes but preclinical evidence suggests that iron, a coenzyme in dopamine synthesis and storage, may be a candidate mediator. Iron is present in high concentrations in the basal ganglia and stimulant drugs may interfere with iron homeostasis. We hypothesised that morphological brain changes in cocaine addiction relate to abnormal iron regulation in the brain and periphery. We determined iron concentration in the brain, using quantitative susceptibility mapping, and in the periphery, using iron markers in circulating blood, in 44 patients with cocaine addiction and 44 healthy controls. Cocaine-addicted individuals showed excess iron accumulation in the globus pallidus, which strongly correlated with duration of cocaine use, and mild iron deficiency in the periphery, which was associated with low iron levels in the red nucleus. Our findings show that iron dysregulation occurs in cocaine addiction and suggest that it arises consequent to chronic cocaine use. Putamen enlargement in these individuals was unrelated to iron concentrations, suggesting that these are co-occurring morphological changes that may respectively reflect predisposition to, and consequences of cocaine addiction. Understanding the mechanisms by which cocaine affects iron metabolism may reveal novel therapeutic targets, and determine the value of iron levels in the brain and periphery as biomarkers of vulnerability to, as well as progression and response to treatment of cocaine addiction.This work was supported by the NIHR Cambridge Biomedical Research Centre and the Behavioural and Clinical Neuroscience Institute (which was supported by a joint award from the Medical Research Council and the Wellcome Trust). The Food Frequency Questionnaire and related analysis software were used in the study. These instruments were initially developed as part of the EPIC-Norfolk Study, which was supported by Cancer Research UK programme grant (C864/A8257)
In the face of threat: neural and endocrine correlates of impaired facial emotion recognition in cocaine dependence.
The ability to recognize facial expressions of emotion in others is a cornerstone of human interaction. Selective impairments in the recognition of facial expressions of fear have frequently been reported in chronic cocaine users, but the nature of these impairments remains poorly understood. We used the multivariate method of partial least squares and structural magnetic resonance imaging to identify gray matter brain networks that underlie facial affect processing in both cocaine-dependent (n = 29) and healthy male volunteers (n = 29). We hypothesized that disruptions in neuroendocrine function in cocaine-dependent individuals would explain their impairments in fear recognition by modulating the relationship with the underlying gray matter networks. We found that cocaine-dependent individuals not only exhibited significant impairments in the recognition of fear, but also for facial expressions of anger. Although recognition accuracy of threatening expressions co-varied in all participants with distinctive gray matter networks implicated in fear and anger processing, in cocaine users it was less well predicted by these networks than in controls. The weaker brain-behavior relationships for threat processing were also mediated by distinctly different factors. Fear recognition impairments were influenced by variations in intelligence levels, whereas anger recognition impairments were associated with comorbid opiate dependence and related reduction in testosterone levels. We also observed an inverse relationship between testosterone levels and the duration of crack and opiate use. Our data provide novel insight into the neurobiological basis of abnormal threat processing in cocaine dependence, which may shed light on new opportunities facilitating the psychosocial integration of these patients.This work was funded by a research grant from the Medical Research Council (G0701497) and supported by the infrastructure of the Behavioural and Clinical Neuroscience Institute (which is supported by a joint award from the Medical Research Council and the Wellcome Trust).
This study was jointly sponsored by the Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge. KD Ersche, CC Hagan, and PS Jones are supported by the Medical Research Council, and DG Smith by the Cambridge Overseas Trust.This is the final version of the article. It first appeared from NPG via http://dx.doi.org/10.1038/tp.2015.5
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