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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
PubMed1995

The effects of glucosinolates and their hydrolysis products on microbial growth.

Rapemeal, which contains potentially toxic compounds such as glucosinolates, was assessed as a substrate for the growth of micro-organisms. The effects of glucosinolates and their degradation products were tested on a range of industrially important microbial species. Sinigrin (2-propenyl glucosinolate) was found to be relatively innocuous to all of the organisms tested but its hydrolysis to yield isothiocyanates, thiocyanates and nitriles resulted in inhibition of growth. The initial inhibitory sinigrin concentration before its hydrolysis was found to be species-dependent with Bacillus subtilis being the most resistant (80 micrograms ml-1) and Saccharomyces cerevisiae (40 micrograms ml-1) the most sensitive. Three Gram-positive organisms tested were found to be more resistant to hydrolysis products than other micro-organisms. Similar results were observed with phenylisothiocyanate for which inhibition was found to be inhibitor and cell concentration-dependent. Addition of thioglucoside glucohydrolase during active growth of Escherichia coli in a sinigrin-containing liquid medium reduced the number of viable cells. Similar effects were also observed in rapemeal media in which growth inhibition was dependent on the glucosinolate content of the rapemeal.

Bacillus↗
PubMed1995

Rapid assessment of physiological status in Escherichia coli using fluorescent probes.

Rapid and direct viability assessment of Escherichia coli in filtered, sterile lake water was possible using multiparameter flow cytometry. Fluorescent dyes were used as probes for different cellular functions (membrane potential, membrane integrity and intracellular enzyme activity), which were correlated with the ability of the cells to respond to nutrient addition while in a stressed state. Measurement of several criteria circumvented limitations imposed by other methods, and provided extensive evidence for the validity of the methods for monitoring cell viability during adoption of a viable-but-non-culturable state in starved E. coli. Macromolecular staining was concomitantly used to monitor changes in cellular protein, RNA and DNA as additional indicators of physiological status during starvation/stress.

Escherichia coli↗
PubMed1995

The effects of protective occlusive gloves on stratum corneum barrier properties.

Data suggests that protection from gloves is paradoxically reduced because of effects of occlusion on the skin. The aim of this study was to characterize these effects on physical and functional properties of stratum corneum. Volunteer trials were conducted using patches of polyvinyl chloride (PVC) glove material on the skin. Impairment of barrier function was assessed by measuring transepidermal water loss (TEWL). Hydration and water sorption-desorption was assessed using skin conductance. The major finding was a short-term impairment of barrier function, measured as an increase in TEWL of 1.7 gn-2h-1 (95% C.I. 0.4 to 2.6 gn-2h-1,p < 0.01). Temporary increases in hydration and water sorption were also observed. On this basis, the effects of wearing PVC gloves over 2 days on stratum corneum barrier properties on the dorsum of the hand were studied. TEWL measurements remained elevated by 1.5 gn-2h-1 the day after occlusive glove removal (95% C.I. 0.2 to 2.8 gn-2h-1, p < 0.01), indicating a possible cumulative effect. In conclusion, our studies demonstrate a potential hazard resulting from the repeated use of protective gloves.

Adult↗
PubMed1995

Direct measurements of natural planktonic bacterial community viability by flow cytometry.

A range of fluorescent viability dyes were used in conjunction with flow cytometry to rapidly enumerate viable bacteria from freshwater environments. Optimal labelling was achieved by using carboxyfluorescein diacetate or chemchrome B with a detergent-mediated permeabilization step. The viable bacterial count under optimal conditions was 7% in oligotrophic lake water and 75% in polluted river water.

Journal Article↗
PubMed1995

OV 632 and MOC 31 in the diagnosis of mesothelioma and adenocarcinoma: an assessment of their use in formalin fixed and paraffin wax embedded material.

AIMS: To investigate the reaction of antibodies OV 632 and MOC 31 in paraffin wax sections as opposed to frozen sections and cytological preparations; to evaluate their usefulness in the differential diagnosis of malignant mesothelioma and secondary adenocarcinoma of the pleura; and to assess the efficacy of microwave pretreatment of sections in unmasking their associated epitopes. METHODS: Immunohistochemistry, using a standard avidin-biotin technique, with microwave pretreatment and trypsinisation in a certain proportion of cases. The material comprised 43 mesotheliomas, 44 adenocarcinomas and five reactive pleuras. RESULTS: Epithelial mesotheliomas and the hyperplastic mesothelial cells reacted strongly with OV 632, the reaction with sarcomatoid and desmoplastic tumours was weak, and the reaction with adenocarcinomas was variable. An unequivocal but sometimes patchy positive reaction was obtained with MOC 31 in all but one of the adenocarcinomas; all but one of the mesotheliomas and all the reactive pleuras were negative. Review of the two apparently anomalous cases revealed that the original diagnoses had probably been incorrect. Reactions to both antibodies were abolished by microwave pretreatment, and also by prior trypsinisation in the case of OV 632. CONCLUSIONS: OV 632 is unsuitable for routine clinical use in paraffin wax embedded material. MOC 31, however, would be a useful addition to a panel of antibodies in the differential diagnosis of mesothelioma and adenocarcinoma in large biopsy and resection specimens and necropsy material. Its value in small biopsy specimens remains to be assessed. Microwave pretreatment does not enhance the reactions with either antibody.

Adenocarcinoma↗
PubMed1995

Carboplatin reinduction after taxane in patients with platinum-refractory epithelial ovarian cancer.

PURPOSE: To determine the activity of carboplatin in patients with ovarian cancer who progressed on taxane (paclitaxel or docetaxel) therapy. PATIENTS AND METHODS: Thirty-three patients with ovarian cancers refractory to platinum and taxane therapy were treated with single-agent carboplatin reinduction once the disease progressed on a taxane. The starting dose of carboplatin was 300 mg/m2 at 28-day intervals. RESULTS: Patients were a median age of 56 years (range, 31 to 80), had a median Zubrod performance status of 1 (range, 0 to 2) and had received a median of three prior chemotherapy regimens (range, two to eight) and one pretaxane platinum regimen (range, one to three). Twenty-six patients had a platinum-free interval of at least 12 months at the time of posttaxane re-treatment with carboplatin. There were seven of 33 (21%) partial responses, with a median duration of 7+ months (range, 2+ to 12+). Responses were noted only in patients with at least a 12-month platinum-free interval and an initial sensitivity to a taxane. The therapy was well tolerated and neurotoxicity was absent. CONCLUSION: A subset of patients with platinum-refractory disease that initially responded to a taxane and who eventually have a platinum-free interval of at least 1 year may respond to carboplatin reinduction. This finding may be secondary to paclitaxel or docetaxel therapy that leads to the reversal of platinum resistance, or the prolonged platinum-free interval permits the loss of resistance to platinum by the tumor. Carboplatin reinduction should be considered in the treatment of patients whose ovarian cancer progresses after an initial sensitivity to a taxane and who had a prolonged platinum-free interval.

Adult↗
PubMed1995

The influence of age, liver size and enantiomer concentrations on warfarin requirements.

1. We have tested the hypothesis that the fall in hepatic mass with age influences the age related increase in sensitivity to warfarin. In 39 otherwise healthy outpatients, aged 50-87 years, stabilised on warfarin for prophylaxis of thromboembolism, age, mean International Normalised Ratio (INR), and mean warfarin dosage were recorded. Liver volume was measured by ultrasound, and plasma was assayed for trough concentrations of (R)- and (S)-warfarin. 2. There was a negative correlation between age and liver volume (r = -0.41; P = 0.01) and age and dose (r = -0.53; P = < 0.001) and a positive correlation between liver volume and dose (r = 0.49; P = 0.002). There was no significant correlation between dosage and (R)- and (S)-warfarin concentrations, nor between dosage and INR. 3. The regression model including both age and liver volume data showed a better fit for estimation of warfarin dosage requirement than regression models based on age and liver volume data alone. Ninety-five per cent prediction intervals for warfarin dose requirements were wide, whether age alone, or age and liver volume were used in calculations. 4. Due to inter-individual variation in warfarin dosage requirements related to other influences, both explained and unexplained, routine measurement of age and liver volume would not contribute further clinically useful information to that obtained by the INR test currently used for predicting warfarin dosage requirements.

Age Distribution↗
PubMed1994

Isolation of glucosinolate degrading microorganisms and their potential for reducing the glucosinolate content of rapemeal.

A range of microorganisms were assessed for their ability to degrade glucosinolates, using sinigrin (2-propenyl glucosinolate) as a model compound. Eight different species capable of growing on sinigrin as a sole carbon source were isolated. These were predominantly Gram-positive bacteria which also degraded the natural glucosinolates within rapemeal. Growth of the majority of these organisms in a sinigrin/glucose liquid medium wass biphasic; glucose was utilised during the initial rapid phase of growth. The ability to degrade sinigrin was found to be unstable and was rapidly and irreversibly lost when organisms were cultured on sinigrin-free media.

Animal Feed↗
PubMed1994

Extraction and high-performance liquid chromatographic method for the determination of microcystins in raw and treated waters.

Increasing concern over the presence of microcystins (cyanobacterial/blue-green algal hepatotoxins) in water supplies has emphasized the need for a suitable analytical method. As many microcystins are known to exist, a method was developed that permits the determination of numerous variants by a single procedure. The method involves filtration to separate cyanobacterial cells from water, allowing intracellular and extracellular toxin levels to be assessed. The cellular components of the samples are extracted repeatedly in methanol, which was found to be the most versatile solvent tested for the extraction of microcystins. The efficiency of this extraction procedure was found to be independent of cell biomass. The filtered water was subjected to trace enrichment using a C18 solid-phase extraction cartridge, followed by identification and determination by photodiode-array high-performance liquid chromatography. The procedure was assessed using four water samples (two raw and two treated) spiked with a mixture of five microcystins and the cyanobacterial hepatotoxin nodularin. Recoveries of all but one microcystin were found to be good when spiked with concentrations as low as 250 ng l-1. The linearity and precision of the experimental procedure were assessed for five microcystins and nodularin. The proposed method permits rapid sample processing and determination of several microcystins.

Chromatography, High Pressure Liquid↗
PubMed1994

Effects of health facilitator performance and attendance at training sessions on the acquisition of tobacco refusal skills among multi-ethnic, high-risk adolescents.

The study examined the effectiveness of a psycho-social tobacco use prevention intervention with a refusal skills training component on the refusal skills of high-risk adolescents, and investigated skill acquisition as related to subject demographics, performance of health facilitators and attendance at skills training sessions. Tobacco refusal skills were assessed for a group (n = 389) of high-risk, seventh-grade students participating as intervention and control subjects in Project SHOUT, a large tobacco use prevention program in the San Diego area. In addition, subject demographics, ratings of health facilitator performance and information about subjects' attendance at skills training sessions were collected. Subjects' responses to audiotaped peer offers of cigarettes and smokeless tobacco were coded for content and quality. Greater tobacco refusal skills among intervention subjects was hypothesized. Further health facilitator performance, attendance at training sessions and subject demographics were thought to be related to skill acquisition. High-risk intervention subjects gave significantly higher quality tobacco-refusal responses than did controls, although the differences between means were small. Results suggested that Hispanic adolescents were particularly receptive to the refusal skills training. The association between health facilitator performance and skill acquisition varied by subject ethnicity, as did the relationship between attendance at training sessions and skill acquisition.

Adolescent↗
PubMed1994

Survival of Staphylococcus aureus in lakewater monitored by flow cytometry.

The ability of flow cytometry to detect and enumerate viable bacteria during survival in a lakewater microcosm was assessed using Staphylococcus aureus as a model organism. Counts of colony-forming units (c.f.u.) on nutrient agar were not significantly different from those obtained by flow cytometric detection of rhodamine 123 stained bacteria and there was no evidence for a viable but nonculturable state using these methods. However c.f.u. were significantly lower when estimated using mannitol salts agar compared with nutrient agar. S. aureus was also enumerated immunofluorescently after staining with FITC-IgG. There was no significant difference between the population estimated immunofluorescently and by acridine orange direct counting, and unlike estimations of viability, only slight reductions in total cell numbers were observed. Changes in the protein and nucleic acid content of S. aureus during survival were also measured by flow cytometry to investigate any potential heterogeneity arising within the starved population. Flow cytometric determinations were found to correlate significantly with their respective chemical determinations. These results demonstrate the ability of flow cytometry to detect viable bacteria during starvation and to study changes in macromolecular content. They also illustrate the importance of using appropriate methods for the detection of viable bacteria in environmental samples.

Bacterial Proteins↗
PubMed1994

Continuous culture studies on the synthesis of capsular polysaccharide by Klebsiella pneumoniae K1.

The synthesis of capsular polysaccharide by Klebsiella pneumoniae K1 was investigated in a minimal salts medium by continuous culture. The organism produced larger amounts of polysaccharide under nitrogen-limited conditions than under carbon-limited conditions. The synthesis of polysaccharide was dependent not only on the availability of excess carbon, but also on growth rate. The rate of polysaccharide synthesis was greatest at low dilutions, low temperature (30 degrees C) and at neutral pH. Prolonged growth in nitrogen-limited culture resulted in the development of non-mucoid variants, possibly due to a selective growth advantage over mucoid cells. The non-mucoid isolate was more susceptible to some bacteriophages, possibly due to the reduction nor absence of capsular polysaccharide.

Bacteriological Techniques↗
PubMed1994

Protease production by Streptomyces thermovulgaris grown on rapemeal-derived media.

A range of actinomycete species was tested for their ability to grow on particulate and particle-free rapeseed meal-derived media. Streptomycetes grew on both types of medium and produced a number of extracellular enzymes. Highest activities of protease were produced by Streptomyces thermovulgaris and reflected the high available protein content of rapemeal. Enzyme production and growth were analysed in fermentor-grown batch cultures of S. thermovulgaris using the particle-free rapemeal broth termed medium B. Growth was biphasic and the majority of the protease was produced during the second slower phase. Analysis of the protease as azocaseinase activity revealed a high degree of thermostability in the presence of calcium such that approximately 20% of the activity remained after incubation at 70 degrees C for 24 h. Gel filtration suggested that S. thermovulgaris synthesized more than one kind of protease and this was confirmed by using specific peptide substrates and inhibitors which revealed the presence of distinct serine and metallo-type enzymes.

Brassica↗
PubMed1994

The influence of ciprofloxacin on the pharmacokinetics and pharmacodynamics of a single dose of temazepam in the young and elderly.

The effect of pretreatment with a 4-day course of ciprofloxacin (500 mg twice daily) on the pharmacokinetics and pharmacodynamics of a single oral dose of temazepam (10 mg) was investigated in 12 healthy young and nine elderly patient volunteers in a crossover design study. Temazepam clearance was lower in the elderly than in the young, but this difference was not statistically significant. Ciprofloxacin had no significant effect on temazepam pharmacokinetics or pharmacodynamics in either age group.

Administration, Oral↗