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Biomedical subjects

M Ford

Publications and source records attributed to M Ford.

At least 19 recordsLinked to original sources
PubMed2000

Regulation of renin gene expression in kidneys of eNOS- and nNOS-deficient mice.

Our study aimed to assess the roles of nitric oxide derived from endothelium NO-synthase (eNOS) and macula densa neuronal NO-synthase (nNOS) in the regulation of renal renin expression. For this purpose renin mRNA levels and renin content were determined in kidneys of wild-type (wt), nNOS-deficient (nNOS-/-), and eNOS-deficient (eNOS-/-) mice, in which the renin system was suppressed by feeding a high-salt diet (NaCl 4%), or was stimulated by feeding a low-salt (NaCl 0.02%) diet together with the converting-enzyme inhibitor ramipril (10 mg kg(-1) day(-1)). In all mouse strains, renin mRNA levels were inversely related to the rate of sodium intake. In eNOS-/- mice renin mRNA levels and renal renin content were 50% lower than in wt mice at each level of salt intake, whilst in nNOS-/- mice renin expression was not different from wt controls. Administration of the general NO-synthase inhibitor nitro-L-arginine methyl ester (L-NAME, 50 mg kg(-1) day(-1)) to mice kept on the low-salt/ramipril regimen caused a decrease of renal renin mRNA levels in wt and nNOS-/- mice, but not in eNOS-/- mice. These observations suggest that neither eNOS nor nNOS is essential for up- or downregulation of renin expression. eNOS-derived NO appears to enhance renin expression, whereas nNOS-derived NO does not.

Animals↗
PubMed2000

The nitroreductase/CB1954 combination in Epstein-Barr virus-positive B-cell lines: induction of bystander killing in vitro and in vivo.

Epstein-Barr virus (EBV)-based gene delivery vectors that preferentially express toxic genes in EBV-infected cells could be used to target EBV-positive tumors for destruction. We have shown previously that the cytosine deaminase (CD) enzyme, which converts the prodrug 5-fluorocytosine (5-FC) into the toxic compound 5-fluorouracil efficiently kills EBV-positive cells in the presence of 5-FC, with a substantial bystander killing effect in vitro and in vivo. To identify the optimal enzyme/prodrug combination for treating EBV-positive lymphomas, we have compared the effectiveness of the CD/5-FC combination with the nitroreductase (NTR)/CB1954 combination for killing EBV-positive B-cell lines. NTR metabolizes CB1954 into an alkylating agent that cross-links DNA. When the CD gene or the NTR gene were transfected into two different EBV-positive B-cell lines in vitro, approximately 90% of cells were killed in a prodrug-dependent manner, although the transfection efficiency was <5%. However, severe combined immunodeficient mouse tumors containing either 30% or 100% of NTR-expressing Burkitt lymphoma (Jijoye) cells were growth inhibited, but not cured, by treatment with intraperitoneal CB1954 (20 mg/kg/day) for 10 days. These results suggest that the NTR/CB1954 combination induces efficient bystander killing of EBV-positive B-cell lines in vitro but may not be as effective as the CD/5-FC combination for treating B-cell lymphomas in vivo.

Animals↗
PubMed2000

Heat disinfection of clinical waste: microbiological assessment and monitoring of effectiveness.

Simple, rapid and reproducible protocols are described for the microbiological assessment of clinical waste treatment processes, using Bacillus subtilis spore tests and end-product sampling. The use of these protocols to commission a new heat disinfection system (HDS), based on a hot oil-filled auger, and to monitor it over the first 21 months of operation is described. It is suggested that these protocols are suitable for assessment of other non-burn heat-treatment technologies.

Bacillus subtilis↗
PubMed1999

Family 10 and 11 xylanase genes from Caldicellulosiruptor sp. strain Rt69B.1.

Three family 10 xylanase genes (xynA, xynB, and xynC) and a single family 11 xylanase gene (xynD) were identified from the extreme thermophile Caldicellulosiruptor strain Rt69B.1 through the use of consensus PCR in conjunction with sequencing and polyacrylamide gel electrophoresis. These genes appear to comprise the complete endoxylanase system of Rt69B.1. The xynA gene was found to be homologous to the xynA gene of the closely related Caldicellulosiruptor strain Rt8B.4, and primers designed previously to amplify the Rt8B.4 xynA gene could amplify homologous full-length xynA gene fragments from Rt69B.1. The complete nucleotide sequences of the Rt69B.1 xynB, xynC, and xynD genes were obtained using genomic walking PCR. The full-length xynB and xynC genes are more than 5 kb in length and encode highly modular enzymes that are the largest xylanases reported to date. XynB has an architecture similar to the family 10 xylanases from Thermoanaerobacterium saccharolyticum (XynA) and Clostridium thermocellum (XynX) and may be cell wall associated, while XynC is a bifunctional enzyme with an architecture similar to the bifunctional beta-glycanases from Caldicellulosiroptor saccharolyticus. The xynD gene encodes a two-domain family 11 xylanase that is identical in architecture to the XynB family 11 xylanase from the unrelated extreme thermophile Dictyoglomus thermophilum strain Rt46B.1. The sequence similarities between the Rt69B.1 xylanases with respect to their evolution are discussed.

Bacteria, Anaerobic↗
PubMed1999

Evaluation of tube coagulase and a fluorogenic substrate for rapid detection of methicillin-resistant Staphylococcus aureus from selective enrichment broth in an outbreak of EMRSA 15.

We investigated the use of tube coagulase and a fluorescent substrate, N-t-BOC-val-pro-arg-7-amido-4-methylcoumarin for the rapid detection of MRSA in selective broth enrichment cultures during an outbreak. These methods were compared with direct plating of swabs and plating a selective broth enrichment culture using 200 screening swabs collected from forty patients during the investigation of an outbreak of E-MRSA 15. Overall 66 swabs were positive for MRSA following subculture of broth enrichment culture. Direct plating detected 25 (38%) positives, tube coagulase 37 (56%), and fluorescent substrate 49 (74%) respectively, although nine of the 49 turned out to be false reactions. When detection from individual patients was analyzed, selective broth subculture identified 28 patients colonized with MRSA. Direct plating detected only 12 (43%) of these patients. The tube coagulase and fluorescence methods detected MRSA in 17 (60%) and 19 (68%) patients respectively. The tube coagulase method was found to be 100% specific for MRSA suggesting its use as a rapid method for the detection of MRSA from selective enrichment broth.

Bacteriological Techniques↗
PubMed1999

Placebo-controlled comparison of candoxatril, an orally active neutral endopeptidase inhibitor, and captopril in patients with chronic heart failure.

AIMS: To compare the effects on exercise capacity of the neutral endopeptidase inhibitor candoxatril, and the angiotensin converting enzyme inhibitor captopril, in patients with mild to moderate heart failure. METHODS: In this multi-centre double-blind placebo controlled study, 60 patients with NYHA Class I-III heart failure were randomised to candoxatril 200 mg b.d. (n = 22), captopril 25-50 mg b.d. (n = 23) or placebo (n = 15). Treadmill exercise tests were carried out weekly during a 5-week single-blind placebo run-in phase until a stable baseline was achieved, and repeated at 4 weekly intervals during the 12-week double-blind treatment phase. RESULTS: Nine patients withdrew from the study--four candoxatril and five captopril. The placebo-adjusted increase in exercise duration after 12 weeks was 56 s (95% CI, -26 to +137 s; P = 0.12) with candoxatril and 37 s (-43 to + 117 s; P = 0.29) with captopril. CONCLUSIONS: Both candoxatril and captopril were well tolerated and treadmill exercise duration appeared to increase during 12 weeks of therapy but this did not achieve statistical significance. This study tentatively suggests that in patients with heart failure, neutral endopeptidase inhibition may provide similar symptomatic benefits to angiotensin converting enzyme inhibition.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

ABC medium, a new chromogenic agar for selective isolation of Salmonella spp.

We describe a new chromogenic agar medium, ABC medium (alphabeta-chromogenic medium), which includes two substrates, 3, 4-cyclohexenoesculetin-beta-D-galactoside and 5-bromo-4-chloro-3-indolyl-alpha-D-galactopyranoside, to facilitate the selective isolation of Salmonella spp. This medium exploits the fact that Salmonella spp. may be distinguished from other members of the family Enterobacteriaceae by the presence of alpha-galactosidase activity in the absence of beta-galactosidase activity. A total of 1, 022 strains of Salmonella spp. and 300 other gram-negative strains were inoculated onto this medium. Of these, 1,019 (99.7%) strains of Salmonella spp. produced a characteristic green colony, whereas only 1 strain (0.33%) of non-Salmonella produced a green colony. A total of 283 stool samples were cultured onto desoxycholate citrate (DC) agar and ABC medium by direct inoculation and after selective enrichment in selenite broth. Overall, the sensitivity and specificity were superior for ABC medium (100 and 90.5%, respectively) than for DC agar (88 and 26.9%, respectively). We conclude that ABC medium offers a high degree of specificity for the detection of Salmonella spp. in stool samples.

Agar↗
PubMed1999

Rapid identification of Staphylococcus aureus by using fluorescent staphylocoagulase assays.

Two rapid (1-h) assays for the detection of Staphylococcus aureus staphylocoagulase were developed by using the fluorogenic thrombin substrates N-t-boc-Val-Pro-Arg-7-amido-4-methylcoumarin (VPA) and N-t-boc-beta-benzyl-Asp-Pro-Arg-7-amido-4-methylocoumarin (BB). The assays were compared to the tube coagulase test and latex agglutination (LA) (Sanofi Diagnostics Pasteur, Guildford, Surrey, United Kingdom) by using 406 clinical isolates of staphylococci, and they produced positive and negative predictive values of 99.2 and 99. 1% for LA, 98.9 and 92.7% for VPA, and 98.9 and 99.1% for BB. Fluorescent assays used colonies from solid media, thereby eliminating the need for broth cultures, and were performed in microtiter trays, thus making them suitable for large-scale screening.

Bacteriological Techniques↗
PubMed1998

Fluid replacement needs of well-trained male and female athletes during indoor and outdoor steady state running.

Twelve male and six female well-trained middle distance athletes performed a series of six one hour runs at 75% VO2 peak pace under similar environmental states indoors (treadmill) and outdoors (track). Running was undertaken in control (C, no fluid), followed by water (W) and sports drink (SD) treatments, with each run separated by a one week interval. Both fluid treatments were supplied in volumes equivalent to individual body mass (fluid) losses incurred in the respective indoor and outdoor C treatments. Haemodynamic (plasma volume), physiological (heart rate and body temperature) and blood chemistry (blood lactate and glucose) measures were analysed as pre to post run changes (delta values). During the respective indoor and outdoor C treatments, males demonstrated approximately a twofold change in body mass (fluid) losses (delta 1.81 +/- 0.10 kg and 2.06 +/- 0.13 kg) compared with females (delta 0.93 +/- 0.11 kg and 1.32 +/- 0.12 kg) (all p<0.05). These losses resulted in almost a twofold fluid replacement need relative to body mass during the running phases of respective indoor and outdoor W and SD treatments in males compared with females (all p<0.05). Both W and SD treatments were effective in minimising the pre to post run disturbances in plasma volume, heart rate, body temperature and blood lactate, while SD treatment resulted in enhanced blood glucose changes. The results suggest gender specific differences in fluid replacement needs during steady state running, which need to be incorporated into fluid replacement strategies to compensate for the demands of training and competition in middle distance athletic events.

Adult↗
PubMed1998

Tumor immunogenicity is determined by the mechanism of cell death via induction of heat shock protein expression.

In situ killing of tumor cells using suicide gene transfer to generate death by a non-apoptotic pathway was associated with high immunogenicity and induction of heat shock protein (hsp) expression. In contrast, a syngeneic colorectal tumor line, CMT93, killed predominantly by apoptosis, showed low levels of hsp expression and less immunogenicity. When apoptosis was inhibited in CMT93 cells by overexpression of bcl-2, hsp was also induced. Furthermore, when cDNA encoding hsp70 was stably transfected into B16 and CMT93 cells, its expression significantly enhanced the immunogenicity of both tumors. Increased levels of hsp, induced by non-apoptotic cell killing, may provide an immunostimulatory signal in vivo which helps break tolerance to tumor antigens. These findings have important implications for the development of novel anti-cancer therapies aimed at promoting patients' immune responses to their own tumors.

Animals↗
PubMed1998

Gene-directed enzyme prodrug therapy: quantitative bystander cytotoxicity and DNA damage induced by CB1954 in cells expressing bacterial nitroreductase.

Clones of human colon carcinoma (WiDr), ovarian carcinoma (SK-OV-3), and Chinese hamster V79 cells expressing the nitroreductase enzyme (NR) from E. coli B were 52-, 225- and 177-fold respectively more sensitive to a 24-h incubation with the prodrug 5-(aziridin-1-yl)-2,4-dinitrobenzamide (CB1954) than the parent lines. The IC50s of non-NR-expressing bystander cells were measured in the presence of differing proportions of NR-expressing cells. The shift in IC50 was used to calculate a value for the bystander effect, termed the transmission efficiency (TE), which is the decrease in IC50 due to bystander effect as a percentage of the maximum decrease possible. The percentage of NR-expressing cells for which the TE was 50%, (the TE50) is a single datum of bystander efficacy. WiDr and V79 cell lines, had a similar TE50 of approximately 2%. SK-OV-3 gave a lower value of 0.3%. These TE50 correlate with concentrations of cytosolic NR activity, which is distinguished from endogenous DT diaphorase activity by kinetic differences. A novel method is described which enables both DNA crosslinks and drug-induced single-strand breaks to be simultaneously quantified in a sedimentation assay. Using this technique, bystander DNA damage was demonstrated in V79 cells, of approximately 50% of that in activator cells.

Aziridines↗
PubMed1998

Detection of carboxypeptidases as taxonomic markers for gram-negative bacteria.

The use of seven benzoyl-L-amino acids for the detection of carboxypeptidase activities in strains of Gram-negative aerobic and facultatively anaerobic bacteria is reported. A simple overnight assay was designed using ninhydrin for the demonstration of the amino acid released by hydrolysis. Detection of carboxypeptidase activity was shown to have some taxonomic relevance within the Enterobacteriaceae; it was also useful for differentiation within the genus Acinetobacter and for distinction between Pseudomonas aeruginosa and Pseudomonas fluorescens.

Amino Acids↗
PubMed1998

Influence of gestation on uterine endometrial steroid receptor concentrations in the African elephant, Loxodonta africana.

The modulatory effects of gestational age and circulating concentrations of progesterone, 5alpha-pregnane-3,20-dione, and estradiol-17beta on the uterine sex steroid hormone receptor levels of the African elephant were investigated. Uterine tissue biopsies and blood samples were obtained from animals culled in the Kruger National Park. Estrogen and progesterone receptor concentrations were determined in uterine biopsies from subadult, lactating, early-, mid-, and late-pregnant elephants, by equilibrium binding assays. Circulating estradiol-17beta and progesterone concentrations were measured by means of RIAs, while plasma concentrations of 5alpha-pregnane-3,20-dione were determined with an amplified ELISA. Significant inverse correlations of the concentrations of estrogen and progesterone receptors with the gestational stage of the elephants were observed. Pregnant uterine horns of individual animals contained lower levels of estrogen and progesterone receptors than the nonpregnant horns of the same animals. A strong positive correlation existed between uterine estrogen and progesterone receptors levels. Circulating concentrations of 5alpha-pregnane-3,20-dione and progesterone decreased with an increase in the concentrations of progesterone receptors as well as with fetal age. We conclude that the progesterone receptor concentrations are down-regulated with progressing gestation in the African elephant. This down-regulation appears to be linked to an increase in circulatory 5alpha-pregnane-3,20-dione concentration in the plasma of pregnant animals.

5-alpha-Dihydroprogesterone↗
PubMed1998

Oxidative stress increases A1 adenosine receptor expression by activating nuclear factor kappa B.

The A1 adenosine receptor (A1AR) contributes to the cytoprotective action of adenosine under conditions known to generate reactive oxygen species (ROS). Pharmacological manipulation of A1AR expression has been shown to modulate this cytoprotective role. In this study, we provide evidence that ROS generated could increase the expression of the A1AR and thereby offset the detrimental effects of ROS. Incubation of DDT1MF-2 smooth muscle cells with ROS-generating chemotherapeutic agents, such as cisplatin (2.5 microM) or H2O2 (10 microM), elicited an increase in A1AR expression within 24 hr. The induction by H2O2 was reduced by the ROS scavenger catalase but not superoxide dismutase. Inhibition of nuclear factor kappa B (NF kappa B) by pyrrolidine dithiocarbamate (200 microM), dexamethasone (100 nM), or genistein (1 microM) abrogated the cisplatin-mediated increase in A1AR. Cisplatin promoted rapid translocation of NF kappa B (but not AP-1) to the nucleus, as detected by electrophoretic mobility shift assays and by Western blotting. A putative NF kappa B sequence in the A1AR promoter effectively competed with labeled kappa B probe for binding in nuclear preparations derived from DDT1MF-2 cells. Transient transfection of DDT1MF-2 cells with the A1AR promoter coupled to firefly luciferase reporter gene led to cisplatin-inducible and pyrrolidine dithiocarbamate-sensitive luciferase activity, suggesting the presence of functional NF kappa B binding site(s) in the A1AR promoter sequence. Treatment of cells with (R)-phenylisopropyladenosine (1 microM), an agonist of the A1AR, reduced cisplatin-mediated lipid peroxidation, which was reversed after blockade of the A1AR. These data suggest that ROS can increase the expression of the A1AR by activating NF kappa B regulatory site(s) on this gene and thereby enhance the cytoprotective role of adenosine.

Animals↗
PubMed1997

Outbreak of gram-negative septicaemia caused by contaminated continuous infusions prepared in a non-clinical area.

An outbreak of Gram-negative septicaemia due to cross infection on an acute cardiology ward is reported. This outbreak was facilitated by two factors: first, an area originally designed for non-clinical purposes was converted into a clean utility area without consulting the infection control team, and second, changes in staff had taken place at the same time. This outbreak emphasizes the importance of continuous staff training in infection control, the involvement of the infection control team in all building alterations and the need to improve recommendations by the Department of Health in the design of clean utility areas.

Cardiology↗
PubMed1997

Note: cyclohexenoesculetin-beta-D-glucoside: a new substrate for the detection of bacterial beta-D-glucosidase.

A new substrate for the detection of bacterial beta-D-glucosidase was evaluated as an alternative to aesculin. This substrate, 3,4-cyclohexenoesculetin-7-beta-D-glucoside, was compared with aesculin for the detection of beta-D-glucosidase in 150 enterococci, 40 streptococci, 12 Listeria sp. and 250 strains of Enterobacteriaceae. In the Gram-positive strains tested, aesculin hydrolysis correlated with hydrolysis of 3,4-cyclohexenoesculetin-7-beta-D-glucoside. In the Gram-negative strains the new substrate was hydrolysed by all aesculin-positive strains and also by four strains (10%) of Escherichia coli which gave a negative aesculin reaction. 3,4-Cyclohexenoesculetin-7-beta-D-glucoside was shown to be a reliable alternative to aesculin and was shown to have significant advantages over aesculin when incorporated into solid media. This was due to the non-diffusible end product produced by hydrolysis of 3,4-cyclohexenoesculetin-7-beta-D-glucoside in the presence of iron.

Bacteria↗