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Biomedical subjects

A Evans

Publications and source records attributed to A Evans.

At least 19 recordsLinked to original sources
PubMed2006

Hippocampal volume is as variable in young as in older adults: implications for the notion of hippocampal atrophy in humans.

Previous studies in humans have shown the presence of an age-related reduction of hippocampal (HC) volume, as well as the presence of reduced HC volume in psychiatric populations suffering from schizophrenia, depression or post-traumatic stress disorder. Altogether, these data suggested that aging or psychiatric disease can have neurotoxic effects on the hippocampus, and lead to HC atrophy. However, these two sets of findings imply that HC volume in young healthy adults should present less variability than HC volume in older adults and psychiatric populations. In the present study, we assessed HC volume in 177 healthy men and women aged from 18 to 85 years of age. We show that the dispersion around the mean of HC volume is not different in young and older adults, so that 25% of young healthy adults present HC volume as small as the average participants aged 60 to 75 years. This shows that HC volume is as variable in young as in older adults and suggests that smaller HC volume attributed to the aging process in previous studies could in fact represent HC volume determined early in life. We also report that within similar age groups, the percentage of difference in HC volume between the individuals with the smallest HC volume (smallest quartile) and the group average is greater than the percentage of difference reported to exist between psychiatric populations and normal control in recent meta-analyses. Taken together, these results confront the notion of hippocampal atrophy in humans and raise the possibility that pre-determined inter-individual differences in HC volume in humans may determine the vulnerability for age-related cognitive impairments or psychopathology throughout the lifetime.

Adolescent↗
PubMed2006

Skeletal benefits from calcium supplementation are limited in children with calcium intakes near 800 mg daily.

INTRODUCTION AND HYPOTHESIS: Calcium supplementation enhances bone mass accrual during administration, with a sustained benefit observed using milk-based calcium but not calcium salts. We tested the hypothesis that calcium from milk minerals but not calcium carbonate will be sustained after supplementation was discontinued. METHODS: Ninety-nine pre-pubertal boys and girls aged 5-11 years were followed for 12 months after being randomized to receive 800 mg/day of calcium from milk minerals (MM) or calcium carbonate (CC), or a placebo (Pla) in a 10-month double blind study. Total body and regional BMC, and femoral shaft bone dimensions were measured using dual energy x-ray absorptiometry. Group differences were determined using ANCOVA. RESULTS: In the intention to treat analysis of the entire sample, no group differences were observed in increments in BMC or bone dimensions during or after supplementation. In those children who remained pre-pubertal, greater gains in pelvis BMC in the milk mineral group than controls were sustained (37.9 versus 29.3% respectively, p<0.02). CONCLUSION: In healthy children consuming about 800 mg calcium daily, calcium supplementation with milk minerals or calcium carbonate does not appear to be produce biologically meaningful benefits to skeletal health. A benefit of calcium supplementation in pre-pubertal was evident, but inconclusive, with the biological significance of the effect of calcium supplementation at the pelvis, and the longevity of this effect to be determined.

Animals↗
PubMed2006

A comparison of the use of Trachlight and Eschmann multiple-use introducer in simulated difficult intubation.

BACKGROUND AND OBJECTIVE: The Eschmann multiple-use introducer is widely used in the management of difficult intubations. Transillumination of the neck is less commonly used. We conducted a randomized crossover study comparing the Trachlight lightwand and Eschmann multiple-use introducer in simulated difficult intubation. METHODS: Sixty-four healthy patients were studied using a standard anaesthetic and full muscle relaxation assessed by train of four. A Macintosh laryngoscope was then inserted and then lowered to simulate a Grade 3 view. Tracheal placement was attempted with both Trachlight lightwand and Eschmann multiple-use introducer in a randomized order. Anaesthetists placing the devices had extensive experience with the Eschmann multiple-use introducer, but only 15 previous uses of the Trachlight. Success rates and time for tracheal placement were recorded. RESULTS: The Eschmann multiple-use introducer and Trachlight were successfully placed in 96.8% and 93.7%, respectively (n.s.). Mean (SD) time to intubation for Eschmann multiple-use introducer and Trachlight were 15(6) and *21(13), respectively (*P < 0.001). CONCLUSION: The Trachlight is a potentially useful alternative to the Eschmann multiple-use introducer in difficult intubation.

Female↗
PubMed2006

An asymmetric shock wave in the 2006 outburst of the recurrent nova RS Ophiuchi.

Nova outbursts take place in binary star systems comprising a white dwarf and either a low-mass Sun-like star or, as in the case of the recurrent nova RS Ophiuchi, a red giant. Although the cause of these outbursts is known to be thermonuclear explosion of matter transferred from the companion onto the surface of the white dwarf, models of the previous (1985) outburst of RS Ophiuchi failed to adequately fit the X-ray evolution and there was controversy over a single-epoch high-resolution radio image, which suggested that the remnant was bipolar rather than spherical as modelled. Here we report the detection of spatially resolved structure in RS Ophiuchi from two weeks after its 12 February 2006 outburst. We track an expanding shock wave as it sweeps through the red giant wind, producing a remnant similar to that of a type II supernova but evolving over months rather than millennia. As in supernova remnants, the radio emission is non-thermal (synchrotron emission), but asymmetries and multiple emission components clearly demonstrate that contrary to the assumptions of spherical symmetry in models of the 1985 explosion, the ejection is jet-like, collimated by the central binary whose orientation on the sky can be determined from these observations.

Journal Article↗
PubMed2006

Homocysteine and coronary heart disease risk in the PRIME study.

INTRODUCTION: Despite recent meta-analyses suggesting that homocysteine is an independent predictor of coronary heart disease (CHD), there is debate regarding whether elevated homocysteine may be deleterious only in the presence of other risk factors, with which it acts synergistically to exert a multiplicative effect on CHD risk, emerging only as a CHD predictor in patients with pre-existing risk factors. The Prospective Epidemiological Study of Myocardial Infarction (PRIME) Study is a multicentre prospective study of 10593 men from France and Northern Ireland, investigating cardiovascular risk factors. We investigated: (1) whether higher homocysteine is associated with increased CHD risk in the PRIME case-control cohort; (2) whether homocysteine interacts synergistically with pre-existing CHD risk factors. METHODS: Homocysteine was measured in 323 participants who had developed CHD at 5-year follow-up and in 638 matched controls. RESULTS: There was no significant difference in homocysteine between cases and controls (p=0.18). Homocysteine was significantly higher in current smokers (geometric mean mumol/l (interquartile range mumol/l) 9.45 (7.43, 11.75)) compared with non-smokers (8.90 (7.32, 10.70); p=0.007). There was a significant interaction between homocysteine, smoking and CHD risk (chi2=10.29, d.f.=2, p=0.006). CONCLUSIONS: These findings suggest that elevated homocysteine is significantly associated with CHD risk in current smokers.

Biomarkers↗
PubMed2006

Wavelet-based feature extraction applied to small-angle x-ray scattering patterns from breast tissue: a tool for differentiating between tissue types.

This paper reports on the application of wavelet decomposition to small-angle x-ray scattering (SAXS) patterns from human breast tissue produced by a synchrotron source. The pixel intensities of SAXS patterns of normal, benign and malignant tissue types were transformed into wavelet coefficients. Statistical analysis found significant differences between the wavelet coefficients describing the patterns produced by different tissue types. These differences were then correlated with position in the image and have been linked to the supra-molecular structural changes that occur in breast tissue in the presence of disease. Specifically, results indicate that there are significant differences between healthy and diseased tissues in the wavelet coefficients that describe the peaks produced by the axial d-spacing of collagen. These differences suggest that a useful classification tool could be based upon the spectral information within the axial peaks.

Algorithms↗
PubMed2006

Intellectual ability and cortical development in children and adolescents.

Children who are adept at any one of the three academic 'R's (reading, writing and arithmetic) tend to be good at the others, and grow into adults who are similarly skilled at diverse intellectually demanding activities. Determining the neuroanatomical correlates of this relatively stable individual trait of general intelligence has proved difficult, particularly in the rapidly developing brains of children and adolescents. Here we demonstrate that the trajectory of change in the thickness of the cerebral cortex, rather than cortical thickness itself, is most closely related to level of intelligence. Using a longitudinal design, we find a marked developmental shift from a predominantly negative correlation between intelligence and cortical thickness in early childhood to a positive correlation in late childhood and beyond. Additionally, level of intelligence is associated with the trajectory of cortical development, primarily in frontal regions implicated in the maturation of intelligent activity. More intelligent children demonstrate a particularly plastic cortex, with an initial accelerated and prolonged phase of cortical increase, which yields to equally vigorous cortical thinning by early adolescence. This study indicates that the neuroanatomical expression of intelligence in children is dynamic.

Adolescent↗
PubMed2006

Adenoviral gene transfer into osteoarthritis synovial cells using the endogenous inhibitor IkappaBalpha reveals that most, but not all, inflammatory and destructive mediators are NFkappaB dependent.

OBJECTIVES: Despite recent major advances in the understanding of the pathogenesis of rheumatoid arthritis, with tumour necrosis factor-alpha (TNFalpha) established as a major therapeutic target, comparatively little is known about the mediators involved in the destructive and inflammatory pathways in osteoarthritis (OA). Recently, it has become appreciated that an inflammatory synovitis contributes not only to the signs and symptoms of osteoarthritis, but also to disease progression. Here, we use high-efficiency adenoviral gene transfer to investigate the role of the transcription factor nuclear factor-kappaB (NFkappaB) in regulating inflammatory and destructive mediators in the late stage OA synovium. METHODS: Infection with reporter adenoviruses transferring the beta-galactosidase or green fluorescent protein genes verified that OA synovial cells could be infected (>95%). Adenovirus transferring the inhibitory subunit IkappaBalpha inhibited NFkappaB. The production of a whole array of pro- and anti-inflammatory cytokines and mediators, and several matrix metalloproteinases and their main inhibitor, was measured by enzyme-linked immunosorbent assay. RESULTS: The spontaneous production of macrophage-produced pro-inflammatory cytokines varied: TNFalpha was modestly inhibited by IkappaBalpha overexpression, but interleukin (IL)-1 was unaffected. Both IL-6 and IL-8 were potently inhibited, as were granulocyte-macrophage colony stimulating factor and oncostatin M. Anti-inflammatory mediators like IL-10, the IL-1 receptor antagonist and the p55 soluble TNF receptor were unaffected. Matrix metalloproteinases 1, 3, 9 and 13 were potently inhibited by IkappaBalpha overexpression, but not their main inhibitor tissue inhibitor of metalloproteinase-1. CONCLUSIONS: The OA synovium is a highly inflammatory environment, with spontaneous production of many cytokines and matrix metalloproteinases. Inhibition of NFkappaB may have a beneficial effect on the balance between pro-inflammatory cytokines and anti-inflammatory mediators, and between destructive metalloproteinases and their main inhibitor.

Adenoviridae↗
PubMed2006

A comparison of the Seeing Optical Stylet and the gum elastic bougie in simulated difficult tracheal intubation: a manikin study.

Management of the difficult airway is one of the major challenges that anaesthetists face. The flexible fibreoptic scope is widely available but its use requires a level of skill, training and continued practice that is not universally found in all anaesthetists, particularly trainees. The Seeing Optical Stylet is a new, semirigid fibreoptic stylet 'scope. We compared the Seeing Optical Stylet with a gum elastic bougie in a simulated Cormack and Lehane Grade 3 laryngoscopy in a manikin. Forty-four anaesthetists were timed while intubating the manikin's trachea with both devices. The mean (SD) time taken with the Seeing Optical Stylet was 20.8 (9.3) s and with the bougie 30 (19.8) s (p = 0.001). Oesophageal intubation occurred six times with the bougie but did not occur with the Seeing Optical Stylet (p = 0.011). We conclude that the Seeing Optical Stylet may be superior to the bougie in difficult tracheal intubation. We feel that the results of this manikin trial are sufficiently encouraging to proceed to a clinical trial in patients.

Clinical Competence↗
PubMed2006

Short birth intervals and the risk of school unreadiness among a Medicaid population in South Carolina.

BACKGROUND: Communities across the United States have become more involved in enhancing school readiness. Many of the predictors of school readiness relate to conditions prior to and following the birth of the child, including a child's birthweight. Shortened birth intervals are related to a variety of health and social consequences that affect child development, yet no formal research has examined the association between birth intervals and school readiness. METHODS: This study was a secondary data analysis of de-identified pregnancy-related vital record information, matched to selected items from the Department of Health and Human Services Medicaid records on mothers and children and to the Cognitive Skills Assessment Battery score in South Carolina for the year 2000 for the child of interest (N = 6915). Analysis of covariance and logistic regression were used to determine if there was a statistically significant relationship between birth interval and school readiness. RESULTS: Results showed that birth interval is a significant predictor of school readiness with a P-value <0.001 even after controlling for various socio-demographic factors. Children born with inadequate birth intervals (less than 24 months) are more likely to fail the Cognitive Skills Assessment Battery compared with those with adequate birth intervals. Potential implications of this research include promoting optimal birth spacing to improve the likelihood that future first graders will come to school ready to learn.

Adult↗
PubMed2006

Rheometrical and computational studies of blood viscoelasticity during coagulation.

The rheological behaviour of coagulating human blood has been measured using multiple strain wave frequencies. The results indicate that coagulating blood, prior to the point of incipient clot formation, can be modelled by a modified form of the Gross-Marvin 'ladder' model, and the benefits of such modeling for blood coagulation are discussed.

Blood Coagulation↗
PubMed2005

Removal and environmental exposure of alcohol ethoxylates in US sewage treatment.

Alcohol ethoxylates (AE) are a common nonionic surfactant employed in consumer and industrial detergents worldwide. Commercial AE are typically complex mixtures composed of > 100 homologous compounds with varying alkyl chain lengths and varying numbers of ethylene oxide (EO) units. Recent improvements in analytical methodology have enabled accurate measurement of the entire AE mixture in sewage treatment plant (STP) influents and effluents, including alkyl chain lengths from 12 to 18 carbons with a range of ethoxylation from 0 to 18 EO units. These improved analytical methods were used to measure AE concentrations at nine sites representative of sewage treatment processes and geographical locations. These new data will make possible a more accurate assessment of environmental risk for AE in the United States. The results indicate that all AE homologues are effectively removed (> 99%) in the most common treatment types. Individual STP total AE effluent concentrations ranged from a low of 0.92 microg/L for activated sludge to a high of 15.6 microg/L for a trickling filter process. For the purpose of representing a national average distribution, an average-flow-weighted wastewater treatment plant effluent concentration was determined for each AE component. The total-flow-weighted average AE effluent concentration was 3.64 microg/L.

Alcohols↗
PubMed2005

Contributions of depressive mood and circulating inflammatory markers to coronary heart disease in healthy European men: the Prospective Epidemiological Study of Myocardial Infarction (PRIME).

BACKGROUND: Data on the possible association between depressive disorders and inflammatory markers are scarce and inconsistent. We investigated whether subjects with depressive mood had higher levels of a wide range of inflammatory markers involved in coronary heart disease (CHD) incidence and examined the contribution of these inflammatory markers and depressive mood to CHD outcome. METHODS AND RESULTS: We built a nested case-referent study within the Prospective Epidemiological Study of Myocardial Infarction (PRIME) study of healthy middle-aged men from Belfast and France. We considered the baseline plasma sample from 335 future cases (angina pectoris, nonfatal myocardial infarction, coronary death) and 670 matched controls (2 controls per case). Depressive mood characterized men whose baseline depression score (13-item modification of the Welsh depression subscale) was in the fourth quartile (mean score, 5.75; range, 4 to 12). On average, men with depressive mood had 46%, 16%, and 10% higher C-reactive protein, interleukin-6, and intercellular adhesion molecule-1 levels, respectively, independently of case-control status, social characteristics, and classic cardiovascular risk factors; no statistical difference was found for fibrinogen. The odds ratios of depressive mood for CHD were 1.35 (95% CI, 1.05 to 1.73) in univariate analysis and 1.50 (95% CI, 1.04 to 2.15) after adjustment for social characteristics and classic cardiovascular risk factors. The latter odds ratio remained unchanged when each inflammatory marker was added separately, and in this analysis, each inflammatory marker contributed significantly to CHD event risk. CONCLUSIONS: These data support an association of depressive mood with inflammatory markers and suggest that depressive mood is related to CHD even after adjustment for these inflammatory markers.

Biomarkers↗
PubMed2005

Randomised controlled trial of mammographic screening in women from age 40: results of screening in the first 10 years.

Debate continues over the effectiveness of screening by mammography in women below age 50. We report here on results of screening in the first 10 years of a randomised trial to study the effect on breast cancer mortality of invitation to annual mammography from age 40 to 41 compared to first invitation to the 3-yearly UK national programme at age 50-52. The trial is taking place in 23 NHS breast screening centres. Between 1991 and 1997, 160 921 women were randomised in the ratio 1 : 2 to intervention and control arms. Screening is by two views at first screen and single view subsequently; data on screening up to and including round five are now complete. Uptake of invitation to screening is between 68 and 70% at all but the latest screening rounds. Rates of referral for assessment are 4.6% at first screen and 3.4% at subsequent screens. Invasive cancer detection rates are 0.09% at first screen, and similar at rescreens until the sixth and later screens. There is little evidence of regular mammography in the trial control arm. The setting of this trial within the NHS breast screening programme should ensure applicability of results to a national programme.

Adult↗