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Biomedical subjects

C Edwards

Publications and source records attributed to C Edwards.

At least 145 records · Page 8Linked to original sources
PubMed1993

A model of measured percussive mechanical trauma and its effects on skin.

In this study, the role of mechanical trauma to skin in industrial dermatitis is considered. The percussive component of mechanical trauma to skin is investigated by modelling it, using an oscillating device which can supply a range of percussive trauma doses. The instrument is electronically controlled, and contains sensors which monitor the force and displacement throughout each impact. From this information, a value proportional to the dose delivered to the skin is calculated and used, rather than the driving power of the percussor. The rate of dose is also controlled. In this study, doses were delivered at a frequency of 7 Hz. Eight volunteers were given regimens of percussive trauma at regular intervals over a 5-day period. Half the group received a dose of 4 mJ/cm2 per impact, the other half received double this dose. The skin response was evaluated using non-invasive measurements of transepidermal water loss, skin thickness, and erythema. The results demonstrate that erythema, skin thickness and transepidermal water loss are all increased after mechanical challenge--erythema and water loss by amounts dependent upon the trauma dose applied. The transepidermal water loss results indicate that for the subjects used in our study, there was a trauma threshold reached after a cumulative dose of greater than 250 J/cm2.

Dermatitis, Occupational↗
PubMed1993

Conversion of flosequinan to the sulphone metabolite in subcellular fractions of human liver, in-vitro.

Flosequinan was metabolized in a NADPH-dependent reaction, by S-oxidation to its principal metabolite, the sulphone. Most of the sulphone metabolite was formed within 20 min and reached a plateau by 60 min, following incubations of flosequinan (31, 61 or 122 microM) with the microsomal fraction. Flosequinan was metabolized mainly by the microsomal fraction. The S-oxidation of flosequinan in incubations containing mitochondrial and cytosolic fractions was 13 and 5%, respectively, of that detected in the microsomal fraction. The route of metabolism of flosequinan in-vitro correlates closely with that previously observed in-vivo. This model could be useful for studying the potential effects of other drugs on flosequinan metabolism in-vitro.

Adult↗
PubMed1993

Rapid, automated separation of specific bacteria from lake water and sewage by flow cytometry and cell sorting.

The use of fluorescence-activated flow cytometric cell sorting to obtain highly enriched populations of viable target bacteria was investigated. Preliminary studies employed mixtures of Staphylococcus aureus and Escherichia coli. Cells of S. aureus, when mixed in different proportions with E. coli, could be selectively recovered at a purity in excess of 90%. This was possible even when S. aureus composed only approximately 0.4% of the total cells. Cell sorting was also tested for the ability to recover E. coli from natural lake water populations and sewage. The environmental samples were challenged with fluorescently labelled antibodies specific for E. coli prior to cell sorting. Final sample purities of greater than 70% were routinely achieved, as determined by CFU. Populations of E. coli released into environmental samples were recovered at greater than 90% purity. The use of flow cytometry and cell sorting to detect and recover viable target bacteria present at levels of less than 1% within an indigenous microflora was also demonstrated.

Antibodies, Bacterial↗
PubMed1993

p53 expression in oat and non-oat small cell lung carcinomas: correlations with proliferating cell nuclear antigen.

AIMS: To investigate the immunohistochemical expression of p53 protein in small cell lung carcinoma (SCLC), comparing it with that in non-small cell carcinoma (NSCLC); and to evaluate the correlation between p53 and proliferating cell nuclear antigen (PCNA) expression as well as between p53 and PCNA expression and survival. METHODS: Paraffin wax embedded tissues from 61 cases of primary lung carcinoma were stained for p53 protein and PCNA using the monoclonal antibodies 1801 and PC-10, respectively, in a standard avidin-biotin immunoperoxidase method. RESULTS: Of the 61 lung carcinomas 35 (57%) were positive for p53 (range 1% to 90%). Ninety percent of the non-oat SCLC contained positive cells and the labelling index (LI) was significantly higher than that of the oat SCLC (p < 0.001). SLCC also displayed a higher p53 LI than NSCLC (p < 0.01); no difference was found between squamous carcinoma, adenocarcinoma, and oat cell carcinoma. A p53 LI of greater than 1% tended to be associated with nodal metastases (p < 0.05), and p53 expression in node positive tumours as well as in oat cell carcinomas was indicative of poorer survival (p < 0.01 and p < 0.1, respectively). A p53 Li of greater than 60% was a negative prognostic factor in non-oat SCLC (p < 0.05). PCNA LI was highest in non-oat SCLC and lowest in NSCLC; oat cell carcinomas had a mean LI intermediate between NSCLC and non-oat SCLC (NSCLC v oat cell carcinoma p < 0.05 and oat cell v non-oat cell carcinomas p < 0.01). A PCNA LI was not correlated with nodal metastases or survival, but there was a significant positive correlation between PCNA LI and p53 LI (rs = 0.484, p < 0.001). CONCLUSIONS: p53 and PCNA expression differ substantially among the various types of lung carcinomas. Substantial differences were also found between oat and non-oat types of SCLC, indicating that SCLC is heterogeneous as far as proliferation rate and altered p53 expression is concerned. p53 seems to be of some prognostic value. The relation between PCNA and p53 expression indicates that the PCNA gene is slightly upregulated by p53.

Antigens, Neoplasm↗
PubMed1993

Deaths and necropsies in a thoracic unit.

BACKGROUND: There is concern about the decrease in the number of requests for necropsies, so a study was undertaken to assess current clinical practice. METHOD: A prospective study was made of all deaths occurring under the care of five chest physicians and three thoracic surgeons at East Birmingham Hospital from 1 April to 30 June 1989. RESULTS: A necropsy was sought in 34 of 58 deaths (59%) and was performed in 22 instances (38%). Major unexpected findings which would have affected clinical management were noted in three patients (14%). The mean delay in reporting results of histological examinations was 146 days (range 41-260 days). As the result of an increase in pathology technical staff levels and alteration in the practice of processing histological data, there was a substantial improvement during the corresponding period in 1990 (mean reduction 58 days, 95% confidence limits 39-77 days). Apart from patients with histologically proved carcinoma, there was no consistent pattern for requests for necropsies. CONCLUSIONS: Necropsies continue to reveal diagnoses which were not suspected while the patient was alive. Although the number of requests made by clinical staff for necropsies is reasonable, the reasons for the requests are not consistent. Guidelines are suggested to improve the number of successful requests and to maximise the information obtained from them.

Autopsy↗
PubMed1993

The long-term prevention of tobacco use among junior high school students: classroom and telephone interventions.

OBJECTIVES: The purpose of this study was to implement and evaluate the effectiveness of a long-term tobacco use prevention program for junior high school students that used college undergraduate change agents and telephone boosters. METHODS: A psychosocial intervention combining refusal skills training, contingency management, and other tobacco use prevention methodologies such as telephone and mail boosters was implemented in 11 junior high schools in San Diego County, California. Eleven other junior high schools served as controls. Of the 2668 participants, 57% were White/non-Hispanic, 24% were Hispanic, and 19% were of other racial/ethnic groups. College undergraduates served as change agents for both the classroom and booster interventions, the latter of which was delivered in the third (ninth-grade) year of the program. RESULTS: At the end of the third year, the prevalence of tobacco use within the past month was 14.2% among the intervention students and 22.5% among the controls, yielding an odds ratio of 0.71 for analysis at the school level. CONCLUSIONS: Both college undergraduate change agents and direct one-to-one telephone interventions appear to provide cost-effective tobacco-related behavior modification.

Adolescent↗
PubMed1993

Evaluation of enzyme immunoassay performance characteristics--phencyclidine example.

Four reagent formulations (three provided by a manufacturer; one prepared in-house by mixing equal volumes of two commercial reagents) are used for the assay of phencyclidine (PCP) in urine samples. Performance characteristics evaluated included assay precision and sensitivity at and near the assay cutoff concentration. Data resulting from the reagent prepared in-house are better than those using then commercially available formulations, and are comparable with those obtained using the recently available new commercial formulation.

Enzyme Multiplied Immunoassay Technique↗
PubMed1992

Nitrosating activity in Escherichia coli.

Nitrosation activity was measured in Escherichia coli isolates and a range of nitrite reductase (nir) mutants. Activity was only detected in intact cells and could be inhibited by a number of treatments such as sonication and osmotic shock. Aerobically-grown cells had highest nitrosation activity compared to oxygen-limited ones. Inclusion of nitrite in growth media induced high activities of nitrite reductase and for some isolates, nitrosation. Analysis of nir mutants identified two which were unable to nitrosate. This result suggested that NADH-dependent nitrite reductase was implicated either directly or indirectly in nitrosation.

Aerobiosis↗
PubMed1992

Pharmacy beyond the dispensary: general practitioners' views.

OBJECTIVES: To ascertain general practitioners' attitudes to an extended role for community pharmacists. DESIGN: Postal questionnaire to a 1 in 6 sample of general practitioners in the Northern, West Midlands, and Oxford regions (total sample size 1087). MAIN OUTCOME MEASURES: Attitudes towards specific extended roles, pharmacist prescribing of particular drugs, the role of the pharmacist, and the relationship between the professions. RESULTS: 744 questionnaires were returned in a usable form, an overall response rate of 68.4%. Attitudes varied, from a majority in favour of pharmacists reporting adverse drug reactions to a majority against their supervising repeat prescriptions (81% and 36% in agreement respectively). A similar range of attitudes was shown to pharmacist prescribing, from 84% in agreement with their prescribing nicotine chewing gum (deregulated since the survey) to 11% agreeing to their prescribing cimetidine. About half the respondents thought general practitioners should be allowed to dispense and a third that pharmacists "should stick to dispensing." 27% agreed that pharmacists were too influenced by commercial pressures to give unbiased advice. CONCLUSIONS: Most doctors would favour an extension of the activities of community pharmacists but worry about their role in screening and counselling patients and in prescribing. Despite relationships being generally felt to be good, there may be a need for better communication and cooperation locally and for proper evaluation of initiatives to extend the role of the pharmacist.

Attitude of Health Personnel↗
PubMed1992

Rapid assessment of bacterial viability by flow cytometry.

The ability of a flow cytometer to rapidly assess microbial viability was investigated using three vital stains: rhodamine 123 (Rh123); 3,3'-dihexyloxacarbocyanine iodide [DiOC6(3)] and fluorescein diacetate (FDA). Rh123 was found to clearly differentiate viable from non-viable bacteria. The methodology for staining bacteria with this dye was optimised. Rh123 was shown to stain and discriminate several different species of viable bacteria although this was not universal. Viable cells of Bacillus subtilis were found to stain better with FDA than with Rh123. The results demonstrate the ability of flow cytometry to rapidly detect and estimate the viability of bacterial populations.

Bacterial Physiological Phenomena↗
PubMed1992

Effects of osmotic stress on mast cell vesicles of the beige mouse.

The large size of the vesicles of beige mouse peritoneal mast cells (4 microns in diameter) facilitated the direct observation of the individual osmotic behavior of vesicles. The vesicle diameter increased as much as 73% when intact cells were perfused with a 10 mM pH buffer solution; the swelling of the vesicle membranes exceeded that of the insoluble vesicle gel matrix, which resulted in the formation of a clear space between the optically dense gel matrix and the vesicle membrane. Hypertonic solutions shrank intact vesicles of lysed cells in a nonideal manner, suggesting a limit to the compressibility of the gel matrix. The nonideality at high osmotic strengths can be adequately explained as the consequence of an excluded volume and/or a three-dimensional gel-matrix spring. The observed osmotic activity of the vesicles implies that the great majority of the histamine known to be present is reversibly bound to the gel matrix. This binding allows vesicles to store a large quantity of transmitter without doing osmotic work. The large size of the vesicles also facilitated the measurement of the kinetics of release as a collection of individual fusion events. Capacitance measurements in beige mast cells revealed little difference in the kinetics of release in hypotonic, isotonic, and hypertonic solutions, thus eliminating certain classes of models based on the osmotic theory of exocytosis for mast cells.

Animals↗
PubMed1992

Identification of anatoxin-A in benthic cyanobacteria (blue-green algae) and in associated dog poisonings at Loch Insh, Scotland.

Dog deaths occurred in 1990 and 1991 after the animals drank water containing blooms of benthic cyanobacteria along the shoreline of Loch Insh, Scotland. Signs of poisoning in the affected animals and the high neurotoxicity of bloom extracts in laboratory bioassays indicated acute poisoning due to cyanobacterial neurotoxin(s). The neurotoxic blooms consisted largely of benthic Oscillatoria species which were also observed in the stomach contents of the poisoned dogs. Stomach contents were also neurotoxic in bioassays with the same signs of poisoning as the Oscillatoria blooms. The cyanobacterial alkaloid neurotoxin anatoxin-a was identified in bloom extracts and poisoned dog stomach contents by high-performance liquid chromatography and gas chromatography-mass spectrometry. A species of benthic Oscillatoria has been isolated from the neurotoxic bloom material and shown to produce anatoxin-a in laboratory culture. These findings are the first to associate anatoxin-a toxicoses with benthic, rather than planktonic, cyanobacteria. Procedures for anatoxin-a extraction and identification from the blooms and animal material are also detailed.

Animals↗
PubMed1992

Sumatriptan injection is superior to placebo in the acute treatment of migraine--with regard to both efficacy and general well-being.

The efficacy of subcutaneous injection of sumatriptan in the acute treatment of migraine was assessed in a double-blind, randomized, placebo-controlled cross-over study of 27 migraine patients. In addition, the patients were asked to give information about their well-being and subjective symptoms by means of a self-administered standardized questionnaire. A total of 22 migraine sufferers received a subcutaneous (sc) injection of 8 mg of sumatriptan and 24 received placebo. Of these patients, 19 received both treatments and thus completed the study. The primary efficacy end-point was a reduction in headache severity from severe or moderate to mild or no headache at 30, 60, 90 and 120 min. An effective response to treatment was achieved within 30 min in 63% and within 60 min in 84% of patients when treated with 8 mg sumatriptan sc, compared with 11% for placebo (p less than 0.001). Sumatriptan also provided significant relief from nausea and photophobia as compared with placebo. The proportion of patients that needed rescue medication after 120 min was significantly lower (p less than 0.001) with active treatment when compared with placebo. Sumatriptan was well tolerated and the majority of adverse events were mild and transient. The most frequent symptoms were those of malaise/fatigue or numbness. No changes in blood pressure or ECG readings were observed during the treatment. Compared with placebo, subcutaneous 8 mg sumatriptan also caused a substantial improvement in general well-being as revealed by the Minor Symptoms Evaluation Profile-acute (MSEP-acute) questionnaire.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1992

Sampling time for serum gentamicin levels.

A survey in 53 UK hospitals showed that 44% of clinical microbiologists recommended post-dose serum gentamicin concentrations to be measured at less than 40 min after an iv bolus dose. Serum gentamicin concentrations were measured in ten patients following bolus iv and im injections. Distribution of the drug occurred for up to 45 min following iv doses and maximum serum concentrations occurred at 45 to 60 min after im injection. The data validate current guidelines to sample at 60 min post bolus iv and im doses. Earlier sampling after iv bolus injections may result in significantly higher gentamicin concentrations, leading to potential interpretive errors of clinical significance.

Gentamicins↗