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Biomedical subjects

C Edwards

Publications and source records attributed to C Edwards.

At least 55 records · Page 3Linked to original sources
PubMed1996

Effect of ageing upon warfarin dose requirements: a longitudinal study.

This longitudinal study was designed to establish the rate of age-related change in warfarin dose requirements. Warfarin dosage was recorded retrospectively in 104 patients who had been stabilized on warfarin for a median period of 10 years (range 6-24 years) for prophylaxis of thromboembolic disease. There was a significant negative correlation between dosage and age at the start of therapy (p = 0.002, r = -0.30). Warfarin requirements fell over time, dosage difference being significantly correlated with age difference (p = 0.01, r = 0.25). Use of regression equation derived from these data suggests a 21% fall in warfarin requirements in this population over a 15-year period. The relationship between change in warfarin dose requirements and ageing established in this longitudinal study is in good agreement with that established by cross-sectional studies, suggesting that no major birth cohort effect is influencing requirements in our warfarin-treated population.

Adult↗
PubMed1996

Expression of Aeromonas caviae bla genes in Escherichia coli.

An isolate of Aeromonas caviae 035 carried a 55.5 kb self-transferable plasmid. Transfer of the plasmid to Escherichia coli K12 resulted in the expression of a TEM-like beta-lactamase that was not expressed in parental A. caviae. The bla gene sequence was detectable by DNA hybridization and PCR amplification of the plasmid when extracted from parental A. caviae or from E. coli K12 transconjugants. Sequence analysis of the bla genes revealed in each case an 858 bp open reading frame, differing from the TEM-1 sequence by five nucleotide substitutions. Only one of these resulted in amino acid substitution (at position 162 serine-->arginine). The sequence most closely resembles that of TEM-12.

Aeromonas↗
PubMed1996

Survival of cells and DNA of Aeromonas salmonicida released into aquatic microcosms.

The survival of the bacterial fish pathogen Aeromonas salmonicida, and persistence of its DNA, were monitored in aquatic microcosms using selective culture and most probable number PCR. Bacterial cells and naked DNA were released into natural non-sterile microcosms consisting of lake sediment overlayered with lake water. Two different types of surface sediment were used. One was sandy in character, taken from the shoreline whilst the other was a littoral loamy surface mud. Inoculated cells and naked DNA became undetectable from water overlayers within 4 weeks of release. Colony counts of Aer. salmonicida declined below detectable limits after 4 weeks in loamy sediment or 7 weeks in sandy sediment; however, naked DNA and DNA from released cells remained detectable for more than 13 weeks.

Aeromonas↗
PubMed1996

Isolation and identification of methanogen-specific DNA from blanket bog peat by PCR amplification and sequence analysis.

The presence of methanogenic bacteria was assessed in peat and soil cores taken from upland moors. The sampling area was largely covered by blanket bog peat together with small areas of red-brown limestone and peaty gley. A 30-cm-deep core of each soil type was taken, and DNA was extracted from 5-cm transverse sections. Purified DNA was subjected to PCR amplification with primers IAf and 1100Ar, which specifically amplify 1.1 kb of the archaeal 16S rRNA gene, and ME1 and ME2, which were designed to amplify a 0.75-kb region of the alpha-subunit gene for methyl coenzyme M reductase (MCR). Amplification with both primer pairs was obtained only with DNA extracted from the two deepest sections of the blanket bog peat core. This is consistent with the notion that anaerobiosis is required for activity and survival of the methanogen population. PCR products from both amplifications were cloned, and the resulting transformants were screened with specific oligonucleotide probes internal to the MCR or archaeal 16S rRNA PCR product. Plasmid DNA was extracted from probe-positive clones of both types and the insert was sequenced. The DNA sequences of 8 MCR clones were identical, as were those of 16 of the 17 16S rRNA clones. One clone showed marked variation from the remainder in specific regions of the sequence. From a comparison of these two different 16S rRNA sequences, an oligonucleotide was synthesized that was 100% homologous to a sequence region of the first 16 clones but had six mismatches with the variant. This probe was used to screen primary populations of PCR clones, and all of those that were probe negative were checked for the presence of inserts, which were then sequenced. By using this strategy, further novel methanogen 16S rRNA variants were identified and analyzed. The sequences recovered from the peat formed two clusters on the end of long branches within the methanogen radiation that are distinct from each other. These cannot be placed directly with sequences from any cultured taxa for which sequence information is available.

Base Sequence↗
PubMed1996

An association between maternal diet and colonic diverticulosis in an animal model.

BACKGROUND/AIMS: Maternal diet may have an effect on the health of the offspring in middle and later life. This study used the laboratory rat as an animal model to examine whether the fibre content of the maternal diet during pregnancy affected subsequent development of colonic diverticula in the offspring fed lifelong fibre deficient or higher fibre diets. METHODS: The parents of experimental animals were fed either a diet that was known to predispose to colonic diverticulosis or a control diet for one month prior to mating. The offspring were fed one of these diets for 18 months. The incidence of colonic diverticulosis, submucosal collagen content, collagen solubility in weak acid, and the composition of intestinal contents were then measured. RESULTS: Offspring of rats fed a higher fibre diet from higher fibre diet fed parents had 0% incidence of colonic diverticulosis. When offspring (regardless of parental diet) were fed a low fibre diet for life the acid solubility was lowered compared with rats fed lifelong higher fibre diet mean (SD) (0.044 (0.0007) v 0.073 (0.0015) sigmoid colon (ratio of soluble:insoluble collagen)); 21.1% had diverticulosis and there was reduced fibre fermentation. However, when the diet of the parents of the fibre deficient diet fed rats was considered, the animals whose mothers had a fibre deficient diet had lower acid solubility (0.032 (0.0007)) and an increased incidence of colonic diverticulosis (42.1%) than the animals fed a fibre deficient diet from higher fibre diet fed parents (p < 0.01 in all instances). CONCLUSION: Maternal diet and the subsequent nutrition of the progeny seem to be of importance in the development of colonic diverticulosis in the rat.

Animals↗
PubMed1996

Melanin content and distribution in the surface corneocyte with skin phototypes.

An individual's sensitivity to sunlight is traditionally assessed by the Boston or Fitzpatrick classification of skin type. The ability to tan depends, to some degree, on the melanin content of the epidermis. In the study reported here, surface corneocytes in exposed skin and unexposed skin have been assessed using a surface stripping slide mounting technique and an Optomax V image analyser, with which the percentage of corneocyte area occupied by melanin granules has been taken as the melanin content index (MCI). There was a significantly different MCI between different skin types for both exposed (P < 0.0001) and unexposed (P < 0.0001) areas using the Kruskal-Wallis one-way ANOVA test. There was also a positive significant correlation between MCI and skin types II-VI in both exposed (r = 0.95, P < 0.001) and unexposed areas (r = 0.89, P < 0.005). Image analysis also demonstrated that the number of melanin granules in surface corneocytes was significantly higher in the exposed area compared with the unexposed area, for skin types II, III, IV, V and VI. Melanin cap-like structures were also observed in exposed corneocytes and heavily pigmented skin contained larger melanin particles than fairer skin. The results indicate that an individual's skin phototype and melanin content, assessed by image analysis, have a significant correlation.

Adult↗
PubMed1995

Flow cytometric detection of specific genes in genetically modified bacteria using in situ polymerase chain reaction.

Use of the polymerase chain reaction, coupled with flow cytometry, to detect a plasmid encoded xylE gene sequence in intact cells of Escherichia coli and Pseudomonas putida was investigated. Optimal incorporation of fluorescently labelled dUTP into a full length PCR product required substitution at a level of 2:3 dUTP:dTTP. Formaldehyde fixed cells of both species were counted before and after thermal cycling. Sufficient numbers of cells remained intact for subsequent detection using microscopy and flow cytometry but light scatter properties were altered. Intact cell suspensions of both species containing plasmid pLV1013 were subjected to thermal cycling with fluorescent dUTP in the reaction mix. Subsequent analysis by flow cytometry allowed detection of a fluorescent PCR product associated with cells. Control samples (without the plasmid) showed only background fluorescence. This method demonstrates the potential for applying DNA amplification methods for sensitive detection of specific sequences localized inside intact bacterial cells.

Catechol 2,3-Dioxygenase↗
PubMed1995

Membrane hyperpolarisation by valinomycin and its limitations for bacterial viability assessment using rhodamine 123 and flow cytometry.

The ionophore, valinomycin, was investigated as a possible means of bacterial viability assessment using the fluorescent membrane potential dye rhodamine 123. Membrane hyperpolarisation in Escherichia coli, Pseudomonas fluorescens, Enterobacter aerogenes and Arthrobacter globiformis was examined during exponential growth and during stress by brief starvation in a high sodium, low potassium buffer using flow cytometric analysis of rhodamine 123 uptake. Dye uptake was variable both between species and amongst cells from the same culture. Exponential phase cells showed no increase in dye uptake due to valinomycin treatment. Stressed P. fluorescens cells responded to valinomycin treatment by increased dye uptake, while stressed E. coli and A. globiformis cells showed no response. Approximately 50% of stressed Eb. aerogenes cells responded to valinomycin. The results demonstrate the limitations of rhodamine dye for viability analysing the viability of diverse bacterial communities and underline the degree of cell heterogeneity in batch cultures.

Arthrobacter↗
PubMed1995

Evaluation of the suitability of bis-(1,3-dibutylbarbituric acid) trimethine oxonol, (diBA-C4(3)-), for the flow cytometric assessment of bacterial viability.

The usefulness of oxonol (bis-(1,3-dibutylbarbituric acid)trimethine oxonol) as a generally applicable indicator of bacterial viability was investigated using untreated and killed cultures of a variety of bacterial genera. Killing methods involved either heat or bactericidal antibiotics. For all strains tested, the fluorescent dye showed significantly more intense staining of killed than untreated cells. The sensitivity of Aeromonas salmonicida to gentamicin was assessed using oxonol. Although the bacterium was shown to be sensitive to the antibiotic, there was a delay between the time cells lost culturability, as judged by numbers of colony forming units, and that for which a dead cell population could be detected by flow cytometry.

Bacteria↗
PubMed1995

Endotoxin-mediated dendritic cell release from the intestine. Characterization of released dendritic cells and TNF dependence.

Dendritic cells (DC) acquire Ag in peripheral tissues and transport it to lymph nodes where they efficiently activate resting T cells. We have shown that i.v. endotoxin causes increased release of intestinal DC into lymph. In this paper we further characterize the release of DC and the properties of the released cells. A total of 50 micrograms of endotoxin injected i.v. causes an increase in DC output within 6 h that peaks between 12 and 24 h, with a maximum output of 8 to 15 times normal. At the same time lymphocyte output is markedly decreased. The increased output of DC is followed by a decrease to subnormal levels. The stimulated release of DC is almost totally blocked by a monoclonal anti-TNF-alpha Ab. A second injection of TNF-alpha does not result in further DC release. DC are not released from lymph nodes into efferent lymph by endotoxin. DC collected from lymph after endotoxin treatment show increased expression of the p55 IL-2 receptor and the OX48 Ag but otherwise resemble normal lymph DC. In functional assays they show no significant differences from normal in their ability to stimulate a MLR or to present Ags to sensitized T cells. Immunocytochemistry with the use of MRC OX62 suggests that the DC are released into lymph from the lamina propria of the small intestine. The stimulated release of DC mediated by TNF-alpha may be important in regulating Ag presentation in lymph nodes draining inflammatory sites.

Animals↗
PubMed1995

Isolation and characterization of microcystins from laboratory cultures and environmental samples of Microcystis aeruginosa and from an associated animal toxicosis.

Six microcystins were identified in a laboratory culture of the cyanobacterium (blue-green alga) Microcystis aeruginosa PCC 7813 using high-performance liquid chromatography coupled with diode array detection (HPLC-DAD) and mass spectrometry (LC-MS). The toxins were purified and further characterized by amino acid analysis and tandem mass spectrometry (MS-MS). The presence of the previously reported microcystin-LR and microcystin-LY was confirmed. Two further microcystins were characterized as microcystin-LW and microcystin-LF. Another two toxins were partially characterized and are believed to be an analog of microcystin-LR (molecular weight 1008) and microcystin-LM (molecular weight 969). Natural bloom material of M. aeruginosa collected from 2 reservoirs was found to have similar microcystin profiles using HPLC-DAD and LC-MS, indicating the widespread occurrence of these microcystin variants. In addition, the presence of 5 of the microcystins was confirmed in the rumen contents of a lamb by LC-MS and LC-MS-MS, providing the first report of microcystins identified in an animal suspected of being poisoned by cyanobacterial hepatotoxins.

Amino Acid Sequence↗
PubMed1995

Ion selectivity of the channels formed by pardaxin, an ionophore, in bilayer membranes.

Using the method of bilayer membranes at the tip of a patch pipette, the properties of the ionic channels produced by the ionophore toxin pardaxin were investigated. At low toxin concentrations, voltage-dependent, single-channel events were measured. The current-voltage curves were non-linear when determined in Tris-Cl solution, but were linear in K(+)-HEPES solution. Using asymmetric ion solutions, the ionic selectivity of pardaxin channels was estimated from the reversal potentials obtained. The sequence of the relative permeabilities for monovalent cations was Tl+ > Rb+ > Cs+ > K+,NH4+ > methylamine+ > Li+ > dimethylamine+ > Na+. Except for Li+, the selectivity sequence fitted the cations relative hydrated size. For bivalent ions the permeability of Ba2+, Sr2+, and Mn2+ relative to Mg2+ changed according to the relative hydrated size. For anions the selectivity sequence was I- > NO3- > Br- > Cl- > ClO4- > SCN- > BF- > HCOO- > F- > CH3COO-. The selectivity sequence for the small anions (I-, NO3-, Br-, Cl-) was different from their hydrated size. Pardaxin channel showed a modest ion selectivity between small anions and cations (PK:PCl:PNa = 1.28:1.00:0.56). Pardaxin is proposed as a biophysical model to study ionic channel selectivity.

Cell Membrane Permeability↗
PubMed1995

Chorioamnionitis caused by Capnocytophaga: case report.

Intraamniotic infection is a significant cause of perinatal morbidity. Capnocytophaga, a gram-negative anaerobe found in the oral cavity, has been implicated as an unusual cause of neonatal sepsis. We report a patient in whom this unusual organism was identified and describe the postpartum and neonatal courses.

Adult↗
PubMed1995

Lack of correlation of soluble E-selectin level with renal transplant rejection.

E-Selectin is a 115-kDa cell surface glycoprotein transiently expressed on vascular endothelium in response to interleukin-1 and tumour necrosis factor-alpha with a peak in expression at four hours. Its distribution in transplant biopsies has been associated with inflammatory events such as allograft rejection. Recently, a soluble isoform of E-selectin has been detected in the culture medium of cytokine activated endothelial cells by an ELISA method. In this study soluble E-selectin levels in renal allograft recipients were compared with the incidence of rejection, acute tubular necrosis (ATN), cyclosporin A (CyA) toxicity, and use of orthoclone OKT3 (muromonab-CD3) to establish whether early endothelial activation and inflammatory damage could be detected. The mean soluble E-selectin level in normal volunteers was 89 ng/ml serum compared to 120 ng/ml for a group of chronic renal failure patients. Soluble E-selectin levels declined upon transplantation but this was not significant, nor was the difference in samples from patients experiencing rejection, ATN or CyA toxicity. A dramatic and sustained rise in soluble E-selectin levels was found within 24 hours of the first dose of OKT3 treatment. This study shows that soluble E-selectin does not provide early unequivocal indication of pathological sequelae in renal transplantation, although extensive endothelial activation can be demonstrated with OKT3 treatment.

Biomarkers↗
PubMed1995

Monoclonal antibodies against human collagenase and stromelysin.

Mouse monoclonal antibodies against recombinant human fibroblast procollagenase and prostromelysin have been generated and characterized. The epitope-containing domains for the antibodies have been assigned based on their immunoreactivities against recombinant proenzymes, mature enzymes, truncated collagenases, proteolytic fragments of stromelysin, and chimeric molecules constructed from different domains of the two enzymes. These antibodies can be divided into four groups: (1) antibodies that recognize the truncated 19-kDa NH2-terminal collagenase, (2) antibodies that recognize the C-terminal domain of collagenase and stromelysin, (3) antibodies that recognize a 31-kDa NH2-terminal collagenase fragment, and (4) antibodies that recognize the 19-kDa NH2-fragment of stromelysin. The prostromelysin-specific antibody 11N13 is of particular interest; it neutralizes stromelysin activity in a stromelysin peptide substrate assay, with an IC50 value of 75 nM. MAb 11N13 may be useful for in vivo and in vitro studies to validate the roles of stromelysin in tumor cell invasion, metastasis, and connective tissue disorders.

Amino Acid Sequence↗
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↗