PubMed Health⌕ Search

Biomedical subjects

P M Bennett

Publications and source records attributed to P M Bennett.

At least 73 records · Page 4Linked to original sources
PubMed1994

Sequence analysis of the L1 metallo-beta-lactamase from Xanthomonas maltophilia.

The amino acid sequence deduced from the L1 beta-lactamase gene of Xanthomonas maltophilia shows a significant variation from that of the CphA and Blm metallo-beta-lactamases of Aeromonas hydrophila and Bacillus cereus, respectively. Whilst the N-terminus of the L1 protein shows some similarity, particularly at the histidine residues previously suggested as a zinc-binding motif, the C-terminus of the protein demonstrates very little similarity. Such differences amongst this group of enzymes would argue for at least three subclasses within the Group 3 beta-lactamases. However, in order to predict their phylogenetic ancestry more sequence data are required from other possible metallo-beta-lactamases.

Amino Acid Sequence↗
PubMed1994

Mass mortality of common dolphins (Delphinus delphis) in south west England due to incidental capture in fishing gear.

In the first quarter of 1992, 118 dolphin carcases, of which 54 were positively identified as common dolphins (Delphinus delphis), were found stranded on the coast of Cornwall and Devon. To determine the cause, detailed post mortem examinations were carried out on 38 of the carcases, and the results were compared with those from 20 common dolphins that stranded on the coast of Cornwall and Devon in the previous 15 months. There was no evidence that the deaths were due to an infectious or parasitic disease, or acute intoxication by any of the algal toxins, trace metals or chlorinated hydrocarbons measured. However, 30 of the 38 dolphins showed signs associated with incidental capture in fishing gear. Skin lesions characteristic of capture in a small-meshed net and the predominance of recently ingested Atlantic mackerel (Scomber scombrus) and pilchard (Sardina pilchardus) in the stomachs of the dolphins suggested that they had been caught in the trawl or purse seine nets used for these fish. There is insufficient information to explain why this high mortality occurred in 1992 and not in other years.

Animal Diseases↗
PubMed1994

Guidelines for the interpretation of laboratory findings in birds and mammals with unknown reference ranges: plasma biochemistry.

The results of analyses of plasma samples from healthy and sick adult birds and mammals of a wide range of species were used to calculate reference ranges and clinical ranges for 11 biochemical variables (calcium, sodium, chloride, total protein, albumin, globulin, inorganic phosphate, potassium, bicarbonate, urea and creatinine concentrations) in six mammalian Orders (Primata, Carnivora, Pinnipedia, Proboscidea, Perissodactyla and Artiodactyla) and six avian Orders (Ciconiiformes, Gruiformes, Pelecaniformes, Psittaciformes, Falconiformes and Strigiformes). The patterns of variation between Orders for the different biochemical variables were then used to provide guidelines for the interpretation of plasma biochemistry results in the species in these Orders for which there are no reference data. The observed clinical ranges provide an indication of the potential diagnostic value of each variable.

Animal Diseases↗
PubMed1994

The occurrence and seasonal changes in the isolation of Listeria spp. in shop bought food stuffs, human faeces, sewage and soil from urban sources.

Eight hundred and twenty-two shop-bought food specimens, 136 soil and 692 faecal specimens were cultured for Listeria spp. in a regular, year round survey. 19.7% (162/822) of the foods, 93.9% (108/115) of the sewage, 14.7% (20/136) soils and 1% (7/692) of faeces yielded Listeria spp. with 10.5% foods, 60.0% sewage, 0.7% soils and 0.6% faeces containing L. monocytogenes. No seasonal variation was noted in isolates from either sewage or foods, with L. monocytogenes and L. innocua being the commonest species in both L. ivanovii when isolated from foods was strongly associated with mutton. Poultry was most likely to contain L. monocytogenes (65.6%, 21/32) and in the greatest numbers. A high percentage of beef (34.6%, 9/26), lamb (40%, 8/20), pork (28.1%, 9/32) and sausages (34.7%, 8/23) also contained L. monocytogenes. L. monocytogenes was rarely isolated from paté (1/40) or soft cheeses (1/251), both of which have been involved with foodborne listeriosis outbreak in the UK. Listeria spp. were commonest in faeces and soils in July to September but the predominant species isolated were different with L. monocytogenes and L. innocua the commonest from faeces and L. ivanovii and L. seeligeri the most common from soil.

Animals↗
PubMed1994

Heterogeneity at the beta-lactamase structural gene ampC amongst Citrobacter spp. assessed by polymerase chain reaction analysis: potential for typing at a molecular level.

Considerable biochemical diversity and polynucleotide sequence variation have been reported amongst strains of Citrobacter spp. However, sequence heterogeneity has not been investigated at gene loci of clinical relevance. In this study, sequence heterogeneity in the beta-lactamase structural gene, ampC, amongst 91 clinical isolates of Citrobacter spp. that showed resistance to various third-generation cephalosporins was investigated. Variation was examined by high-stringency polymerase chain reactions (PCR) with primers homologous to the known ampC sequences of C. freundii strains OS60 and I113, and C. diversus NF85. If an isolate contained an ampC gene homologous to one of these three characterised ampC genes, a single PCR band of a predictable size was generated with the appropriate primer set; 50 (60%) of isolates gave a PCR product of the expected size with the OS60 primer set and nine (10%) gave a product with the I113 primer set. All these 59 isolates were identified as C. freundii by API-20E strips. Six isolates (7%) gave a product with the C. diversus NF85 primer set but only four of these were identified as C. diversus in API-20E tests; the other two isolates were identified as C. freundii. Of the 91 isolates, 28 (31%), were identified as either C. freundii or C. diversus, but gave no PCR product with any primer set tested. Five of these showed no homology to any of the reference strain ampC PCR products in hybridisation tests. Nevertheless, all showed beta-lactamase activity. Overall, this method allowed the identification of novel ampC gene loci, which may serve as a basis for the identification of Citrobacter spp. rapidly at a molecular level.

Base Sequence↗
PubMed1993

The use of a DNA probe and PCR to examine the distribution of the aac(6')-Ic gene in Serratia marcescens and other gram-negative bacteria.

A nucleotide probe for the chromosomal aminoglycoside 6' acetyltransferase gene (aac(6')-Ic) of Serratia marcescens was used in non-radioactive dot-blot hybridization experiments with 186 strains belonging to ten different species of Serratia. The gene was only detected in strains of S. marcescens (all strains tested), and positive hybridization was seen irrespective of whether or not strains were kanamycin-resistant. An additional 180 strains belonging to 28 Gram-negative bacterial species other than in the genus Serratia did not hybridize with the probe. A rapid PCR test for the aac(6')-Ic gene was developed and used to confirm that the aac(6')-Ic gene is only found in S. marcescens. Southern hybridization analysis of S. marcescens chromosomal DNA demonstrated that the gene was usually located on a PvuII fragment with a putative isoleucine tRNA-2 gene, but polymorphisms with respect to the size of this fragment were observed.

Acetyltransferases↗
PubMed1993

Typing of Listeria spp. by random amplified polymorphic DNA (RAPD) analysis.

Random amplified polymorphic DNA (RAPD) analysis, a variation of the polymerase chain reaction (PCR) in which a single primer is used, was evaluated for use as a simple and reliable method with which to type Listeria spp. Representatives of six species of Listeria were studied. Five isolates of L. innocua and four isolates of L. seeligeri were all distinguishable from one another, but the four isolates of L. ivanovii tested, although distinguishable from other Listeria spp., were not differentiated. Among L. monocytogenes serovars 1/2a (eight isolates), 1/2b (eight isolates) and 4b (10 isolates), at least six, three and six RAPD patterns were observed, respectively. Fourteen neonatal cross-infection sets of L. monocytogenes isolates, shown to be indistinguishable by serotyping and phage typing, were examined with three different primers. With one primer, three of the sets were shown to consist of closely related, but distinguishable, strains. In the other 11 cases, each set of strains was indistinguishable with all three primers. These preliminary data indicate that RAPD analysis has promise as a method for typing Listeria spp.

Amino Acid Sequence↗
PubMed1993

The survival of bacteria exposed to desiccation on surfaces associated with farm buildings.

The survival of 11 species of Gram-negative and Gram-positive bacteria was examined on different surfaces exposed to desiccation. There were large variations between species; Pseudomonas spp. and Rhizobium leguminosarum biovars survived for less than 2 d, whilst Enterococcus spp. survived for more than 11 weeks. The type of surface on to which the bacteria were deposited affected survival, but with different effects between species. In addition the survival of spontaneous nalidixic acid-resistant (Nal-r) mutants of a natural Escherichia coli isolate were compared. Overall the differences were slight, but of seven resistant mutants, five survived better than the parent whilst one survived less well. Nine transposon insertion derivatives of one of the Nal-r mutants (ECO80) which survived better than the parent were compared; all survived similarly to the parent except ECO883 which survived less well. The growth characteristics of ECO883 and ECO80 were compared; at high osmotic pressures (> 0.4 mol 1-1 NaCl) ECO883 grew more slowly and showed a longer lag time than the parent. Of the osmoregulatory functions studied, ECO883 appeared to be altered with respect to K+ transport or accumulation, although the transposon insertion had occurred in a gene distant from known K+ transport genes.

Agriculture↗
PubMed1993

Effects of low concentrations of ampicillin in feed on the intestinal Escherichia coli of chicks.

Ampicillin in low concentrations (1.7 and 5 g t-1) was incorporated in the feed given to 1-d-old chicks for 2 weeks. This was sufficient to select, in the intestinal contents, resistant Escherichia coli strains for which the minimum inhibitory concentration of ampicillin was > 100 micrograms ml-1. Different clones of E. coli were identified by their biotype, pattern of resistance to antibacterial agents and plasmid profile (designated P-P types). The experiment was repeated twice and the average proportion of ampicillin-resistant P-P types among 72 isolates of E. coli from chicks given feed containing 0, 1.7 and 5 g ampicillin t-1 were 10%, 31% and 46% respectively.

Ampicillin↗
PubMed1993

The effect of soft X-radiation on myofibrils.

Myofibrils, the contractile organelles from striated muscles, have been examined in the X-ray microscope to determine the effect of radiation on their function and structure. Using X-rays of energy 350-385 eV in the water window we find that after an exposure to 7.5 x 10(5) photons/micron2 (calculated to give an absorbed dose of 20,000 Gy) the myofibrils will no longer contract. The use of the free radical scavenging agent, DMSO, gives some protection to the fibrils. It has also been found that after this much irradiation the fibrils lose up to 20% of their mass. Further substantial mass loss occurs on subsequent irradiation. After 25 times the loss-of-function exposure only 30% of the mass remains. Analysis of a series of images of the same myofibril covering this range of exposures shows that the mass is preferentially lost in some areas of the structure and consequently significant structural changes occur.

Animals↗
PubMed1991

Development of LYNX: a computer application for disease diagnosis and health monitoring in wild mammals, birds and reptiles.

IBM-compatible software has been developed so that quantitative and qualitative haematological and biochemical reference data for over 500 species of mammals, birds and reptiles can be made readily accessible to veterinary surgeons. The LYNX software makes it possible to retrieve these data at different taxonomic levels (species, genera, families, orders and classes) and to select data by age and sex. The data for each variable may be presented in the form of a reference range or as a frequency histogram. Notes describing the variations in blood cell morphology observed in healthy individuals of each species are included in the database. The user's own haematological and biochemical data can also be entered, stored and used.

Animals↗
PubMed1991

The future contribution of transposition to antimicrobial resistance.

Antibiotic resistance is commonplace in clinical bacterial isolates. Many of the resistance genes are transposon-borne and have the potential for rapid dispersal throughout the bacterial kingdom. Resistance genes are constantly subject to mutation and reassortment. Given appropriate selection pressure, the new resistance determinants can emerge rapidly to pose significant treatment problems. It seems likely that in the future bacterial resistance will continue to be a problem, both with respect to current antibiotics and to new ones and that transposon-borne resistance genes will continue to figure prominently.

DNA Transposable Elements↗
PubMed1991

Inhibition of K88ab-mediated haemagglutination by polymyxin B nonapeptide.

The ability of the cyclic peptide polymyxin B nonapeptide (PMBN) to inhibit haemagglutination of erythrocytes by Escherichia coli bearing K88ab, K99 or F41 fimbriae was examined. The agent strongly inhibited K88ab-mediated haemagglutination, but had little or no effect on haemagglutination mediated by K99 or F41 fimbriae. Inhibition of K88ab-mediated haemagglutination did not result from release of fimbrial adhesins from the bacterial cell surface, nor from solubilization of K88ab receptors in erythrocytes. Since PMBN also prevented haemagglutination mediated by partially-purified K88ab fimbriae, the agent may directly obstruct access of fimbriae to their mammalian receptor binding sites.

Adhesins, Escherichia coli↗
PubMed1991

Erythrocyte size, number and haemoglobin content in vertebrates.

Relationships between erythrocyte number, size and haemoglobin content were examined in 441 species (101 families) of mammals, birds and reptiles. Whereas the total number of red cells (RBC), the mean cell volume (MCV) and mean cell haemoglobin (MCH) showed much variation, the haemoglobin level (Hb), packed cell volume (PCV) and mean cell haemoglobin concentration (MCHC) were relatively constant in all adult mammals and birds but lower in reptiles. There was a strong positive correlation between MCV and MCH and a strong negative correlation between MCV and RBC across all species. Mammals had more, smaller erythrocytes per unit volume of blood than birds, which, in their turn, had more, smaller erythrocytes than reptiles. The findings confirm that the oxygen-carrying capacity of the blood is highly conserved in birds and mammals but is lower in exothermic groups such as reptiles. Although the significance of the observed species differences in RBC and MCV has yet to be explained, the findings have considerable evolutionary, physiological and diagnostic interest.

Animals↗