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Biomedical subjects

A Brookes

Publications and source records attributed to A Brookes.

At least 19 recordsLinked to original sources
PubMed2004

Integrating decision tools for the sustainable management of land contamination.

The approach to taking decisions on the management of land contamination has changed markedly over 30 years. Change has been rapid with policy makers and regulators, practitioners and researchers having to keep pace with new technologies, assessment criteria and diagnostic methods for their measurement, techniques for risk analysis and the frameworks that support decision-makers in their efforts to regenerate historically contaminated land. Having progressed from simple hazard assessment through to 'sustainability appraisal' we might now consider piecing together the experience of decision-making for managing land contamination. Here, we critically review recent developments with a view to considering how better decisions can be made by integrating the decision tools available. We are concerned with the practicality of approach and the issues that arise for practitioners as decision criteria are broadened.

Conservation of Natural Resources↗
PubMed2004

Methods for understanding organic fouling in MBRs.

The identification and quantification of foulants in membrane bioreactors present a major challenge due to their complexity resulting from biomass heterogeneity. Fouling is normally characterised with respect to the critical flux, this being conventionally viewed as being the flux below which a reduction in membrane permeability does not take place. However, recent studies have revealed that such fouling arises even at very low fluxes. Moreover, fouling rates can differ substantially between different experiments, trials and installations even when operated under apparently similar conditions of biomass and soluble organic carbon concentrations. The methods available for quantifying and analysing fouling are reviewed with specific reference to recent data on sub-critical flux behaviour. It is concluded that HPSEC analysis of extracted biomass fractions may provide the most valuable data towards the determination of differences in fouling propensity between different biomasses, as inferred in conventional flux step analysis.

Biofilms↗
PubMed2001

Women's voices: prenatal diagnosis and care for the disabled.

The development and implementation of prenatal diagnosis has changed the experience of pregnancy for many women. How women make decisions about prenatal diagnosis PD is an important question that challenges us both individually and as a community. The question of care is central to many women's decision-making process. How much care a child will require, how much care a woman feels confident to provide, and the level of care available for children with genetic conditions and families from their communities all impact on women's decisions to undertake prenatal diagnosis as well as how to use the information available from testing. Interviews with women making these decisions explored, among other things, the role that caring and access to care played in women's ethical deliberations. Before PD can widen women's reproductive choices and counter criticisms that its use is eugenically oriented, the central role that provision of, and access to, care holds for participants in PD programmes must be acknowledged and addressed.

Abortion, Legal↗
PubMed1998

Pantoprazole-based 10-day triple therapy is effective in Helicobacter pylori eradication.

AIM: To investigate the efficacy of a short course of pantoprazole-based triple therapy in Helicobacter pylori eradication in a single-centre pilot study. METHODS: Patients with active or healed duodenal ulcer or with gastric erosions or gastritis, all of whom were H. pylori-positive, received 10 days of twice-daily open treatment with pantoprazole 40 mg, plus clarithromycin 250 mg and tinidazole 500 mg. H. pylori was assessed at entry and 28-35 days after the end of treatment by rapid urease test (at entry only), culture and antimicrobial sensitivity, histology and 13C urea breath test. The criterion for eradication was a negative result in all three tests. RESULTS: Seventy patients were treated, of whom four were excluded from analysis due to major deviations from the study protocol. Eradication of H. pylori was achieved in 57/66 patients (per protocol analysis 86% (95% CI: 78-95%)) and was higher in patients with organisms sensitive to nitroimidazole before treatment (sensitive: 47/53 (89%), insensitive: 10/13 (77%)). There was marked reduction in acute gastritis throughout the stomach while chronic gastritis decreased only in the corpus. Healing was achieved in all 24 patients with active duodenal ulcer. Treatment was complied with; only one patient missed one of the 20 doses. Adverse events were of mild or moderate intensity and did not require withdrawal from treatment. CONCLUSION: A short course of pantoprazole-based triple therapy is well tolerated and effective in eradicating H. pylori.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Cloning of a gene bearing missense mutations in early-onset familial Alzheimer's disease.

Some cases of Alzheimer's disease are inherited as an autosomal dominant trait. Genetic linkage studies have mapped a locus (AD3) associated with susceptibility to a very aggressive form of Alzheimer's disease to chromosome 14q24.3. We have defined a minimal cosegregating region containing the AD3 gene, and isolated at least 19 different transcripts encoded within this region. One of these transcripts (S182) corresponds to a novel gene whose product is predicted to contain multiple transmembrane domains and resembles an integral membrane protein. Five different missense mutations have been found that cosegregate with early-onset familial Alzheimer's disease. Because these changes occurred in conserved domains of this gene, and are not present in normal controls, they are likely to be causative of AD3.

Alzheimer Disease↗
PubMed1994

Apolipoprotein E epsilon 4 allele frequency in patients with Lewy body dementia, Alzheimer's disease and age-matched controls.

Genotypes of apolipoprotein E (ApoE) were determined by polymerase-chain reaction (PCR) amplification and restriction-sizing of brain DNA from 39 cases of Lewy body dementia (LBD), 68 senile Alzheimer's disease (AD) patients and 47 neuropathologically validated non-demented controls. There was a 3-fold increase in the epsilon 4 allele frequency in both LBD and AD groups compared with controls. These results indicate that LBD and AD share the epsilon 4 allele of ApoE as a major risk factor for the development of disease and suggest a similarity in disease aetiology.

Aged↗
PubMed1991

Symbolic grouping versus simple cell models.

The apparent line-like structure in dot patterns derives substantially from the orientation defined by pairings of adjacent dots. Two alternative models have been proposed for making these pairings, one in which the individual dots are treated as discrete grouping tokens, and the second in which the pairing orientation derives from spatial summation by simple cell receptive fields. Contradictory evidence has been found both directly in support of, and directly against, both models. Much of the debate about these two models has hinged on the degree of linearity of summation expected in the simple cell model. Recent neurophysiological evidence changes the balance of the debate, invalidating certain earlier arguments based on linearity and providing a model way of showing that simple cells do indeed play a major, but not necessarily exclusive, role in dot groupings.

Analysis of Variance↗
PubMed1991

Combining binocular and monocular curvature features.

A study is reported of the perception of visual surfaces in wire-frame stimuli generated by combinations of monocular surface contours and binocular disparity that provide differing information about 3-D relief. Observers vary considerably in the relative contribution made by the binocular and monocular cues to the perception of overall 3-D form. Without training, many observers may entirely fail to perceive surface curvature from the binocular disparity patterns, interpreting the form of the surface only according to the monocular information. For other observers, both cues contribute to the end percept, with the monocular interpretation dominating where the disparity information indicates planarity and with disparity dominating where disparity information suggests curvature and the monocular interpretation suggests planarity. Where stereo and monocular interpretations indicate inconsistent surface curvature features at a common location, more complex resolution strategies are suggested.

Cues↗
PubMed1989

Binocular depth from surfaces versus volumes.

Subjects were asked to compare the relative depths of two binocular targets embedded in different random dot stereogram backgrounds. The disparities of the background points were either randomized, corresponding to a scattering of points within a volume, or arranged according to a sawtooth (triangle-wave) disparity profile (i.e., a set of slanted planar surfaces separated by sharp depth discontinuities). When the targets were embedded in the random volume, their depths were perceived in accordance with their relative disparities. But when the target points were embedded in the sawtooth surfaces their depths were systematically misperceived in a manner predicted by the incorrect depth interpretation of the background points. Rather than seeing a sawtooth pattern, the background points resembled a staircase in depth, and the targets, which appeared embedded in different steps, were misjudged in depth accordingly. The effect suggests a distinction between the depth processing of isolated binocular features and those associated with continuous surfaces.

Attention↗
PubMed1989

The analogy between stereo depth and brightness.

Apparent depth in stereograms exhibits various simultaneous-contrast and induction effects analogous to those reported in the luminance domain. This behavior suggests that stereo depth, like brightness, is reconstructed, ie recovered from higher-order spatial derivatives or differences of the original signal. The extent to which depth is analogous to brightness is examined. There are similarities in terms of contrast effects but dissimilarities in terms of the lateral inhibition effects traditionally attributed to underlying spatial-differentiation operators.

Color Perception↗
PubMed1988

Integrating stereopsis with monocular interpretations of planar surfaces.

Experiments are reported that involved spatial judgments of planar surfaces that had contradictory stereo and monocular information. Tasks included comparing the relative depths of two points on the depicted surface and judging the surface's apparent spatial orientation. It was found that for planar surfaces the 3D perception was dominated by the monocular interpretation, despite the strongly contradictory stereo information. We propose that stereo information is effectively integrated only where the surface exhibits curvature features or edge discontinuities, i.e. where the second spatial derivatives of disparity are nonzero. Planar surfaces induce constant gradients of disparity and are thus effectively featureless to stereopsis. Further observations are reported regarding nonplanar surfaces, where contradictory monocular information can still be effectively rivalrous with that suggested stereoscopically.

Depth Perception↗
PubMed1988

The concave cusp as a determiner of figure-ground.

The tendency to interpret as figure, relative to background, those regions that are lighter, smaller, and, especially, more convex is well known. Wherever convex opaque objects abut or partially occlude one another in an image, the points of contact between the silhouettes form concave cusps, each indicating the local assignment of figure versus ground across the contour segments. It is proposed that this local geometric feature is a preattentive determiner of figure-ground perception and that it contributes to the previously observed tendency for convexity preference. Evidence is presented that figure-ground assignment can be determined solely on the basis of the concave cusp feature, and that the salience of the cusp derives from local geometry and not from adjacent contour convexity.

Attention↗
PubMed1987

Probing depth in monocular images.

It is generally expected that depth (distance) is the internal representational primitive that corresponds to much of the perception of 3D. We tested this assumption in monocular surface stimuli that are devoid of distance information (due to orthographic projection and the chosen surface shape, with perspective projection used as a control) and yet are vividly three-dimensional. Slant judgments were found to be in close correspondence with the actual geometric slant of the stimuli; the spatial orientation of the surfaces was perceived accurately. The apparent depth in these stimuli was then tested by superimposing a stereo depth probe over the monocular surface. In both the perspective and orthographic projection the gradient of perceived depth, measured by matching the apparent depth of the stereo probe with that of the monocular surface at a series of locations, was substantial. The experiments demonstrate that in orthographic projection the visual system can compute from local surface orientation a depth quantity that is commensurate with the relative depth derived from stereo disparity. The depth data suggests that, at least in the near field, the zero value for relative depth lies at the same absolute depth as the stereo horopter (locus of zero stereo disparity). Relative to this zero value, the depth-from-slant computation seems to provide an estimate of distance information that is independent of the absolute distance to the surface.

Depth Perception↗