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Biomedical subjects

M K Lewis

Publications and source records attributed to M K Lewis.

13 recordsLinked to original sources
PubMed1998

Food advertising on British children's television: a content analysis and experimental study with nine-year olds.

OBJECTIVES: The nature and significance of food advertising during children's television was examined in two studies: a content analysis of advertising (Study 1) and an investigation of the impact of food adverts on the self-perception of overweight children (Study 2). PARTICIPANTS: Study 1 monitored 91 h of children's broadcasting on four terrestrial and satellite stations in the UK. In Study 2, 103 children aged 9.75 y viewed two videotaped cartoons containing either food or non-food product advertisements. MEASURES: Study 1 used a detailed record of advertisement style and content. Study 2 included a self-report measure of current state, and measures of self-esteem, dietary restraint, body weight and height. RESULTS: Half of the 828 adverts were for food products, 60% of which were for breakfast cereals and confectionery/ snacks. Food advertisements used significantly more animation, stories, humour and the promotion of fun/happiness/mood alteration. In Study 2, significant interactions between advertisement type and overweight were observed on ratings of perceived health and appetite for sweets. CONCLUSION: While small changes are apparent, advertisements during children's television are still dominated by those for foods of questionable nutritional value, in a manner designed to engage attention and emotional response. That overweight children appeared more influenced by their personal enhancement message, suggests the value of further work identifying who is most influenced and by what features of advertising.

Advertising↗
PubMed1995

An evaluation of 99Tcm-DMSA SPET with three-dimensional reconstruction in 68 patients with varied renal pathology.

Sixty-eight patients (135 kidneys) with varied renal pathology were evaluated with 99Tcm-dimercaptosuccinic acid (DMSA) single photon emission tomography (SPET) to determine whether it is possible to detect more renal abnormalities and to reduce the number of false-positives due to anatomical variants when compared with planar imaging. The patients ranged in age from 1 to 78 years and their pathologies included urinary tract infection (n = 50), space occupying lesions (n = 5), calculi (n = 4), hypertension (n = 4) and others (n = 5). Planar scans were performed 3 h after the injection of 80 MBq of 99Tcm-DMSA and a 64 x 20 s acquisition over 360 degrees was used for SPET. High-resolution collimation was used for both. Slices were displayed as transaxial, coronal and sagittal and/or oblique sagittal in the plane of the kidney. Three-dimensional (3D) images were formed by volume rendering. Each kidney was divided into three regions and each region scored separately for the presence of an abnormality. Planar scans were reviewed alone and then in conjunction with SPET and 3D images. Planar imaging detected 95 abnormal regions compared with 103 using SPET. SPET reduced the number of equivocal regions in 8 (12%) patients. The diagnosis was altered by SPET in 17 (4%) regions in 14 (21%) patients. SPET and 3D 99Tcm-DMSA allow more abnormalities to be detected but also allow more specific definition of apparent abnormalities on planar imaging.

Adolescent↗
PubMed1994

Patient dose in dual x-ray absorptiometry.

Dual x-ray absorptiometry (DXA) provides a convenient, non-invasive method of assessing skeletal bone mineral which is widely used for clinical studies. This report describes a study to estimate the effective dose of radiation (ICRP-60 (1990)) to a typical female patient from scans performed on three DXA scanners: the Hologic QDR-1000, QDR-1000/W and QDR-2000. The scans modes studied were: total body; anteroposterior (AP) lumbar spine; lateral lumbar spine; proximal femur; distal forearm. An ionization chamber and tissue-equivalent phantom were used to determine entrance surface dose and percentage depth-dose curves for each scan mode. Anatomical data from ICRP-23 (Reference Man) and a body section atlas were used to estimate the absorbed dose to each organ in the scan fields. Effective dose was estimated using the ICRP-60 tissue weighting factors and the fraction of each organ in the scan field. Results are summarized below. Figures for the effective dose are given both excluding and (in brackets) including the ovaries to cover the cases of postmenopausal and premenopausal women respectively.

Absorptiometry, Photon↗
PubMed1994

NHS research and development: a research strategy for nuclear medicine.

The objective of the National Health Service (NHS) research and development strategy is to ensure that the content and delivery of care in the NHS is based on high quality research relevant to improving the health of the nation. In 1991 Professor Michael Peckham was appointed Director of Research and Development, with a target of 1.5% of the NHS budget to be spent on research and development by 1997/98. The Standing Group on Health Technology (SGHT) was formed to advise on the need for health technology assessment in the NHS. Health technology assessment (HTA) can be defined as the assessment of the effectiveness, costs and impact of a health technology on health care. The SGHT is aided by five advisory panels, one of which is the Diagnostics and Imaging Panel, covering all areas of Laboratory Medicine and Imaging. In 1993 the panel was asked by the SGHT to identify new and existing technologies in need of assessment, to identify technologies with insufficient evidence of value and in need of assessment prior to diffusion throughout the NHS, and to identify emerging technologies which may have a major impact on the NHS in the future. Formal consultation processes at both regional and national level were used to obtain recommendations for HTA from the NHS, patient and professional organizations, including the British Nuclear Medicine Society and European Association of Nuclear Medicine (BNMS and the EANM). Of the 197 recommendations received, 16 were considered a high priority and forwarded to the SGHT in October 1993.(ABSTRACT TRUNCATED AT 250 WORDS)

National Health Programs↗
PubMed1993

A ribonuclease inhibitor expresses anti-angiogenic properties and leads to reduced tumor growth in mice.

Our experiments were designed to determine whether recombinant ribonuclease inhibitor (RNasin) could inhibit angiogenesis and reduce tumor growth in adult mice. We used the Fajardo disc angiogenesis assay as the primary means of measuring new blood vessel growth. This assay measures the penetration of cells into a polyvinyl alcohol sponge with a central core of ELVAX-coated sponge containing test substances. Cell penetration was reduced to 29.3% of control (phosphate-buffered saline; heat-inactivated RNasin) values. Endothelial cell influx was measured by lectin staining and confirmed by culturing cells isolated from sponges by collagenase treatment. RNasin also reduced the augmented reaction evoked by either basic fibroblast growth factor (bFGF) or sodium orthovanadate. To confirm the anti-angiogenic activity of RNasin, Hydron-coated polyvinyl sponges containing bFGF or bFGF plus RNasin were implanted into adult mouse corneas. bFGF induced a strong angiogenic response that was almost completely inhibited by RNasin. RNasin-containing ELVAX-coated sponges implanted subcutaneously underneath an intradermal inoculum of C755 mammary tumor cells caused significant reduction in tumor growth (P < 0.005). The antitumor effect of RNasin correlated with its effect on tumor-induced neovascularization, suggesting that the ability of RNasin to affect tumor growth was due to its ability to inhibit angiogenesis.

Adenocarcinoma↗
PubMed1990

Efficient site directed in vitro mutagenesis using ampicillin selection.

A novel plasmid vector pSELECT-1 is described which can be used for highly efficient site-directed in vitro mutagenesis. The mutagenesis method is based on the use of single-stranded DNA and two primers, one mutagenic primer and a second correction primer which corrects a defect in the ampicillin resistance gene on the vector and reverts the vector to ampicillin resistance. Using T4 DNA polymerase and T4 DNA ligase the two primers are physically linked on the template. The non-mutant DNA strand is selected against by growth in the presence of ampicillin. In tests of the vector, highly efficient (60-90%) mutagenesis was obtained.

Ampicillin Resistance↗
PubMed1987

Tissue expansion reconstruction of soft tissue avulsions of the face: report of two cases.

A technique utilized to increase the amount of skin available for repair of soft tissue defects with local flaps has been described. Indications for the use of tissue espansion and the surgical technique and possible disadvantages have been discussed. Two case reports are presented to illustrate the use of the tissue expander to repair avulsive craniofacial defects.

Adult↗
PubMed1980

Transcription of simian virus 40 DNA by wheat germ RNA polymerase II. Priming of RNA synthesis by the 3'-hydroxyl of DNA at single strand nicks.

Linear simian virus 40 DNA has been transcribed in vitro with wheat germ RNA polymerase II. Transcription products have been fractionated on polyacrylamide gels and several discrete sized RNA bands are seen. The RNA band pattern is affected dramatically by deoxyribonuclease treatment during RNA isolation. This is because most of the RNA synthesized is covalently linked to DNA. This linkage has been demonstrated by density analysis in formaldehyde-CsCl gradients and by incorporation of alkali-stable ribonucleotides into DNA. The linear DNA templates transcribed were generated by treatment of circular DNA with restriction enzymes which, in addition to cutting once at a single primary site, were found also to produce single strand nicks at specific secondary sites. The discrete sized RNA bands observed result from initiation at these nicks and terminated at DNA ends. There are two modes of nick-dependent initiation. In one mode the 3'-hydroxyl terminus of the DNA at a single strand nick serves as a primer for the extension of an RNA chain. In a second mode de novo initiation of an RNA chain is promoted at the nick. RNAs which are not primed initiate predominantly with GTP. The catalytic action of wheat germ RNA polymerase II is similar to that of Escherichia coli core RNA polymerase which has also been shown to synthesize primarily RNA which is covalently linked to DNA.

Base Sequence↗