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Biomedical subjects

C Davies

Publications and source records attributed to C Davies.

At least 127 records · Page 7Linked to original sources
PubMed1995

Reliability of the Assessment of Communicative Effectiveness in Severe Aphasia.

The Assessment of Communicative Effectiveness in Severe Aphasia (ACESA) was developed to measure the communicative effectiveness of people with severe aphasia following a stroke. The reliability was evaluated. Ten patients with severe communication difficulties (particularly limited expression) were assessed and videoed. The videos were rated by three trained raters. Reliability was calculated to demonstrate intrarater and interrater reliability, and test-re-test reliability. Reliability was good but needed to be improved across raters. It was concluded that the ACESA has the potential to be a useful clinical and research tool.

Adult↗
PubMed1994

Crystallization and preliminary X-ray diffraction studies of bacterial ribosomal protein L14.

Based on amino-acid sequence homology, it is predicted that ribosomal protein L14 is a member of a recently identified family of structurally related RNA-binding proteins. To verify this, the gene for Bacillus stearothermophilus L14 has been cloned, and the protein has been purified and crystallized. The crystals are in space group C2 with cell dimensions a = 67.0, b = 32.7, c = 49.4 A, and beta = 101.8 degrees, and there is one molecule in the asymmetric unit (V(m) = 2.0 A(3) Da(-1)). They are of high quality, and a native data set has been collected to a resolution of 1.6 A, with an R(merge) of 5.3%.

Journal Article↗
PubMed1994

Isolation of Arabidopsis thaliana mutants hypersensitive to gamma radiation.

A screening method for mutants of Arabidopsis thaliana hypersensitive to gamma-radiation has been devised. Plants grown from ethyl methanesulfonate (EMS)-treated seeds were irradiated at the seedling stage, which is highly radiosensitive due to extensive cell division. Severe growth inhibition of mutant plants by a gamma-ray dose which only slightly affects wild-type plants was the selective criterion. Twelve true-breeding hypersensitive lines were isolated from a total of 3394 screened plants. Genetic analysis of five of the lines revealed five new genes, designated RAD1-RAD5. These Arabidopsis RAD mutants are phenotypically similar to mutants in the RAD52 epistasis group of Saccharomyces cerevisiae, which are highly sensitive to ionizing radiation but not hypersensitive to UV light. One possibility is that the Arabidopsis mutants are defective in a nonhomologous or illegitimate recombination mechanism used by plants for repair of chromosome breaks.

Arabidopsis↗
PubMed1994

Crystal structure of prokaryotic ribosomal protein L9: a bi-lobed RNA-binding protein.

The crystal structure of protein L9 from the Bacillus stearothermophilus ribosome has been determined at 2.8 A resolution using X-ray diffraction methods. This primary RNA-binding protein has a highly elongated and unusual structure consisting of two separated domains joined by a long exposed alpha-helix. Conserved, positively charged and aromatic amino acids on the surfaces of both domains probably represent the sites of specific interactions with 23S rRNA. Comparisons with other prokaryotic L9 sequences show that while the length of the connecting alpha-helix is invariant, the sequence within the exposed central region is not conserved. This suggests that the alpha-helix has an architectural role and serves to fix the relative separation and orientation of the N- and C-terminal domains within the ribosome. The N-terminal domain has structural homology to the smaller ribosomal proteins L7/L12 and L30, and the eukaryotic RNA recognition motif (RRM).

Amino Acid Sequence↗
PubMed1994

Cloning and characterization of a tomato GTPase-like gene related to yeast and Arabidopsis genes involved in vesicular transport.

The deduced translation product of a tomato cDNA derived from a gene expressed in a number of tomato tissues of different developmental stages contained sequence motifs characteristic of the GTPase superfamily of proteins. The sequence was closely related to the Sar1 protein of Saccharomyces cerevisiae, a protein essential for the formation of protein transport vesicles at the endoplasmic reticulum (ER) (A. Nakano and M. Muramatsu, Cell Biol 109 (1989): 2677-2691). From analysis of the GTPase superfamily gene sequences, including the tomato SAR-like gene, it is proposed that the SAR genes comprise a distinct GTPase subfamily, presumably with a common, essential function in vesicular transport.

Amino Acid Sequence↗
PubMed1994

UK cervical cancer screening programme: setting a research agenda.

The UK national cervical cancer screening programme aims at reducing the incidence of and mortality from carcinoma of the cervix. It is generally agreed that high grade cervical intraepithelial neoplasia should be treated aggressively, but the appropriate management strategies for women with lesser degrees of abnormality are uncertain because of the inability to distinguish lesions that are likely to progress to invasive disease from those that will regress spontaneously. The role of human papillomavirus (HPV) and the possible usefulness of HPV testing as a secondary screening tool in women with borderline or mild dyskaryosis is also unknown. This paper proposes an agenda for research into the uncertainties within the UK screening programme, suggesting that priority should be given to determining the most appropriate referral and management policies and the use of HPV DNA assay for women with borderline and mild dyskaryosis, so that those women at highest risk of developing invasive disease are treated. A randomised controlled trial is needed. The practical and methodological difficulties which would need to be considered and the need to convene a multidisciplinary research team to develop and implement the trial are highlighted.

Carcinoma↗
PubMed1994

Near patient testing in general practice: attitudes of general practitioners and practice nurses, and quality assurance procedures carried out.

BACKGROUND: The evaluation of near patient testing in British general practice has largely been confined to studies examining individual tests or comparing equipment. AIM: This study set out to determine the attitudes of practice staff to near patient testing, and the extent to which staff undertook quality assessment. METHOD: Four types of near patient testing machines were introduced into 12 general practices in two regions of England, south west Thames and west Midlands. General practitioner and practice nurse attitudes to near patient testing were assessed by semi-structured interview before and six months after the introduction of the machines. The extent to which routine quality assurance procedures were carried out within the surgery and as part of local and national schemes was examined. RESULTS: Although 80% of general practitioners anticipated changing patient management with near patient testing, only two fifths reported having done so after six months. Nurses generally were enthusiastic at the outset, although one third were unhappy about incorporating near patient testing into their work schedules. Time pressure was the most important factor restricting uptake of near patient testing. Nurses performed quality control regularly but complete local external quality assurance procedures were established in only half the practices. All the practices participated in a national scheme for cholesterol assays. CONCLUSION: General practitioners in this study did not find near patient testing a very useful addition to their resources. Pressure on nurses' time was the most frequently reported limitation.

Attitude of Health Personnel↗
PubMed1994

Effectiveness and cost of different strategies for information feedback in general practice.

AIM: The aim of this study was to determine the effectiveness and relative cost of three forms of information feedback to general practices--graphical, graphical plus a visit by a medical facilitator and tabular. METHOD: Routinely collected, centrally-held data were used where possible, analysed at practice level. Some non-routine practice data in the form of risk factor recording in medical notes, for example weight, smoking status, alcohol consumption and blood pressure, were also provided to those who requested it. The 52 participating practices were stratified and randomly allocated to one of the three feedback groups. The cost of providing each type of feedback was determined. The immediate response of practitioners to the form of feedback (acceptability), ease of understanding (intelligibility), and usefulness of regular feedback was recorded. Changes introduced as a result of feedback were assessed by questionnaire shortly after feedback, and 12 months later. Changes at the practice level in selected indicators were also assessed 12 and 24 months after initial feedback. RESULTS: The resulting cost per effect was calculated to be 46.10 pounds for both graphical and tabular feedback, 132.50 pounds for graphical feedback plus facilitator visit and 773.00 pounds for the manual audit of risk factors recorded in the practice notes. The three forms of feedback did not differ in intelligibility or usefulness, but feedback plus a medical facilitator visit was significantly less acceptable. There was a high level of self-reported organizational change following feedback, with 69% of practices reporting changes as a direct result; this was not significantly different for the three types of feedback. There were no significant changes in the selected indicators at 12 or 24 months following feedback. The practice characteristic most closely related to better indicators of preventive practice was practice size, smaller practices performing significantly better. Separate clinics were not associated with better preventive practice. CONCLUSION: It is concluded that feedback strategies using graphical and tabular comparative data are equally cost-effective in general practice with about two thirds of practices reporting organizational change as a consequence; feedback involving unsolicited medical facilitator visits is less cost-effective. The cost-effectiveness of manual risk factor audit is also called into question.

Cost-Benefit Analysis↗
PubMed1993

Impact of introducing near patient testing for standard investigations in general practice.

OBJECTIVE: To assess the clinical and economic impact of surgery based near patient testing in general practice for six commonly used biochemical and bacteriological tests. DESIGN: After four months' monitoring, equipment for two bacteriological and four biochemical tests was introduced without cost into 12 practices using a crossover design. Structured request forms were used to monitor laboratory investigations. SETTING: 12 general practices in west midlands and south west Thames with list sizes above 9000. MAIN OUTCOME MEASURES: Investigation rates per 1000 consultations. Changes from baseline rates. Reasons for requesting investigations and provisional diagnoses. Cost per test and sensitivity of costs to rate of use. RESULTS: Investigation rates for the six tests rose by 16.5% (from 78.6/1000 consultations to 91.6/1000) when equipment was available in the surgery and reverted to baseline rates when it was withdrawn. The average weekly number of tests when equipment was available ranged from 0.5 to 10.5 (mean 9.0). Cholesterol tests were used as an addition to laboratory testing, usually for screening. Midstream urine analysis was often done in the surgery instead of in the laboratory, although 30% of samples were tested by both methods. Doctors' reasons for investigation and conditions tested were largely unaffected by availability of surgery tests. Costs for surgery tests were higher for all tests except midstream urine. CONCLUSIONS: Availability of surgery based testing increased the number of tests performed. It was cost effective only for midstream urine analysis.

Cholesterol↗
PubMed1993

Sub-cellular localization of the 25-kDa protein encoded in the triple gene block of potato virus X.

The 25-kDa protein of potato virus X (PVX) is encoded by the 5' open reading frame of the overlapping triple gene block, has a GKS sequence motif characteristic of nucleotide binding proteins, and is thought to play a role in movement between cells. We have produced a polyclonal antibody to the 25-kDa protein to investigate its synthesis and intracellular location. On Western blots of infected tissue extracts this antibody detected a single major protein of the expected mobility, produced earlier than the viral coat protein in infected protoplasts and located predominantly in the 1000 g pellet fraction of infected cells. Immunogold labeling of thin sections of infected tissue revealed that the 25-kDa protein is associated with the cytoplasmic inclusion bodies characteristic of PVX infections, but not with the cell wall or plasmodesmata. Therefore, although mutational studies indicate a role for the 25-kDa protein in the cell to cell movement of viral infection it is unlikely to act in precisely the same manner as the other well-characterized movement proteins of tobacco mosaic and cowpea mosaic viruses.

Amino Acid Sequence↗
PubMed1993

Restriction analysis of an amplified polygalacturonase gene fragment differentiates strains of the phytopathogenic bacterium Pseudomonas solanacearum.

Amplification of a polygalacturonase gene fragment using the polymerase chain reaction (PCR) formed a rapid, sensitive and portable method for detecting and differentiating strains of Pseudomonas solanacearum, a taxonomically complex bacterial species. Primers 5'CAG CAG AAC CCG CGC CTG ATC CAG 3' and 5'ATC GGA CTT GAT GCG CAG GCC GTT 3' were used to amplify a 504 base pair polygalacturonase gene fragment from 57 Ps. solanacearum isolates. Digestion of these products with Hae III defined groups which reflected the known genetic divisions within the species.

Bacterial Typing Techniques↗
PubMed1992

Use of specific polyclonal antibodies to detect heterogeneous lipases from Geotrichum candidum.

Geotrichum candidum CMICC 335426 was previously shown to produce two lipases termed lipase A and lipase B, lipase B being highly specific for hydrolysis of esters of cis-delta 9 fatty acids. We now describe the isolation of polyclonal antibodies specific for lipase A and lipase B. These antibodies were used in Western blotting techniques to detect the appearance of the lipases during the course of the fermentation of G. candidum CMICC 335426. A and B were found to be produced simultaneously in the extracellular medium at the start of the growth phase. The two lipases were always present at similar levels in the medium. The specific antibodies were then used to detect the presence of A- and B-like lipases in crude lipase samples from other strains of G. candidum. The lipases were found at different levels in all these samples, and the specificities of the crude lipases varied significantly from one strain to another. Differences in specificity could therefore be explained by different levels of specific (B-type) and non-specific (A-type) lipases in the medium. This was verified by purifying A- and B-type lipases from the G. candidum strain ATCC 34614.

Antibodies↗
PubMed1992

Experimental and clinical evaluation of a noninvasive reflectance pulse oximeter sensor.

The objective of this study was to evaluate a new reflectance pulse oximeter sensor. The prototype sensor consists of 8 light-emitting diode (LED) chips (4 at 665 nm and 4 at 820 nm) and a photodiode chip mounted on a single substrate. The 4 LED chips for each wavelength are spaced at 90-degree intervals around the substrate and at an equal radial distance from the photodiode chip. An optical barrier between the photodiode and LED chips prevents a direct coupling effect between them. Near-infrared LEDs (940 nm) in the sensor warm the tissue. The microthermocouple mounted on the sensor surface measures the temperature of the skin-sensor interface and maintains it at a present level by servoregulating the current in the 940-nm LEDs. An animal study and a clinical study were performed. In the animal study, 5 mongrel dogs (weight, 10-20 kg) were anesthetized, mechanically ventilated, and cannulated. In each animal, arterial oxygen saturation (SaO2) was measured continuously by a standard transmission oximeter probe placed on the dog's earlobe and a reflectance oximeter sensor placed on the dog's tongue. In the first phase of the experiment, signals from the reflectance sensor were recorded while the dog was immersed in ice water until its body temperature decreased to 30 degrees C. In the second phase, the animal's body temperature was normal, and the oxygen content of the ventilator was varied to alter the SaO2. In the clinical study, 18 critically ill patients were monitored perioperatively with the prototype reflectance sensor. The first phase of the study investigated the relationship between local skin temperature and the accuracy of oximeter readings with the reflectance sensor. Each measurement was taken at a high saturation level as a function of local skin temperature. The second phase of the study compared measurements of oxygen saturation by a reflectance oximeter (SpO2[r]) with those made by a co-oximeter (SaO2[IL]) and a standard transmission oximeter (SpO2[t]). Linear regression analysis was used to determine the degree of correlation between (1) the pulse amplitude and skin temperature; (2) SpO2(r) and SaO2(IL); and (3) SpO2(t) and SaO2(IL). Student's t test was used to determine the significance of each correlation. The mean and standard deviation of the differences were also computed. In the animal study, pulse amplitude levels increased concomitantly with skin temperature (at 665 nm, r = 0.9424; at 820 nm, r = 0.9834; p < 0.001) and SpO2(r) correlated well with SaO2(IL) (r = 0.982; SEE = 2.54%; p < 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Smoking prevalence and attitudes of Gwynedd Health Authority staff towards passive smoking and the Authority's non-smoking policy.

In 1989, a postal survey was undertaken to investigate the smoking prevalence and attitudes of Gwynedd Health Authority employees towards the Authority's non-smoking policy, passive smoking and other related issues. The results show a smoking prevalence rate of 22% for those participating in the survey, with over half of all smokers expressing a wish to stop. Although the rate was similar for males and females, it was marginally higher amongst nursing staff and young employees. Smoking prevalence was highest among the ancillary staff, and lowest among the medical and dental professions. Most employees were in broad agreement with the Authority's non-smoking policy, and a majority thought it about right or favoured extending it. Most non-smokers and ex-smokers believed passive smoking to be a health hazard, with an increased number rating it anti-social. Attitudes towards these issues were similar for males and females, with marked differences between the groups employed in different areas of the service. Younger employees were more aware of the dangers of passive smoking, but less sympathetic towards the policy than the older ones. The findings of this study highlight the differences between smokers and non-smokers on all smoking issues. The implications for health education and the Authority's non-smoking policies are discussed.

Attitude of Health Personnel↗