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Biomedical subjects

A Layton

Publications and source records attributed to A Layton.

At least 19 recordsLinked to original sources
PubMed2003

Natural attenuation of trichloroethylene in fractured shale bedrock.

This paper describes one of the first well-documented field examples of natural attenuation of trichloroethylene (TCE) in groundwater in a fractured shale bedrock. The study was carried out adjacent to a former waste burial site in Waste Area Grouping 5 (WAG5) on the Oak Ridge Reservation, Oak Ridge, TN. A contaminant plume containing TCE and its daughter products were detected downgradient from the buried waste pits, with most of the contamination occurring in the upper 6 m of the bedrock. The monitoring well array consists of a 35-m-long transect of multilevel sampling wells, situated along a line between the waste pits and a seep which discharges into a small stream. Concentrations of volatile organic carbons (VOCs) were highest in the waste trenches and decreased with distance downgradient towards the seep. Sampling wells indicated the presence of overlapping plumes of TCE, cis-dichloroethylene (cDCE), vinyl chloride (VC), ethylene, ethane, and methane, with the daughter products extending further downgradient than the parent (TCE). This type of distribution suggests anaerobic biodegradation. Measurements of redox potential at the site indicated that iron-reduction, sulfate reduction, and potentially methanogensis were occurring and are conducive to dechlorination of TCE. Bacteria enrichment of groundwater samples revealed the presence of methanotrophs, methanogens, iron-reducing bacteria and sulfate-reducing bacteria, all of which have previously been implicated in anaerobic biodegradation of TCE. 16S rDNA sequence from DNA extracted from two wells were similar to sequences of organisms previously implicated in the anaerobic biodegradation of chlorinated solvents. The combined data strongly suggest that anaerobic biodegradation of the highly chlorinated compounds is occurring. Aerobic biodegradation may also be occurring in oxygenated zones, including near a seep where groundwater exits the site, or in the upper bedrock during seasonal fluctuations in water table elevation and oxygen levels.

Biodegradation, Environmental↗
PubMed2000

Observations on high levels of fusidic acid resistant Staphylococcus aureus in Harrogate, North Yorkshire, UK.

A retrospective study was carried out to investigate possible reasons for a marked increase in fusidic acid-resistant Staphylococcus aureus (FusR S. aureus) identified by our routine hospital microbiology service. Information was obtained on a sample of 64 consecutive patients from whom resistant S. aureus had been cultured. The source of isolates was found to be diffuse within the hospital and community. The site of sample was most frequently chronic cutaneous infections (68%). All the S. aureus isolates were resistant to both fusidic acid and penicillin and many were resistant to multiple antibiotics. Topical fusidic acid had been used by 40% of patients in the preceding 6 months and none had received oral fusidic acid (sodium fusidate). Most (80%) had received an oral antibiotic in the preceding 2 years. Information from the Prescriptions Pricing Authority revealed that the total number of prescriptions for fusidic acid-containing preparations for the period September 1997 to August 1998 was markedly higher in Harrogate than in five other local areas where increases in (FusR) S. aureus have not been observed.

Administration, Oral↗
PubMed1991

Level of knowledge and information sources used by patients with psoriasis.

One-hundred and eight patients with psoriasis completed a questionnaire concerning their knowledge about the condition. This was carried out at two departments of dermatology, at Bridgend General Hospital and Leeds General Infirmary. There were no significant differences between the two centres, and the main source of the patients' information about psoriasis was from a dermatologist, but several other sources such as newsletter were of help.

Adolescent↗
PubMed1982

Reduced acuity and its relation to blur threshold measurements in optometric tests.

Sensitivity to blue was investigated in a group of subjects having long-standing reduction of visual acuity, and in another group of subjects whose acuity was reduced for the purpose of the study. The distributions of scores was compared with those of a previous study of subjects with normal acuity. The reduction of acuity produced a shift in both distributions, the greater shift occurring in the second group.

Adolescent↗
PubMed1978

Perception of blur in optometric test.

Sensitivity to blur detection was measured for 30 optometric patients by having them match the clarity [or blur] of the target words at the test endpoint with 1 of an identical set of photographically defocused words. The group showed considerable variance in their blur scores which approached a normal distribution. Some clinical implications are discussed.

Adolescent↗
PubMed1975

A supplementary technique for balancing refraction.

The customary technique for balancing the refractive (subjective) correction lenses requires the subject to compare the clarity of two images. If there is an inequality in the best acuity attainable for each eye, this technique does not give valid results. An alternate technique is described that does not depend upon maximal acuity for each eye.

Humans↗
PubMed1975

Retinal and post-retinal components of visual illusions.

A technique is presented permitting control of input to each hemiretina and each hemisphere, of the various elements of a visual illusion. When the retinal effects and post-retinal effects are added, the result is greater than the total illusory effect. This is believed due to the mixing between hemispheres via the corpus callosum, and suggests a possible means of assessing the role of the corpus callosum.

Corpus Callosum↗