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Biomedical subjects

D E Taylor

Publications and source records attributed to D E Taylor.

At least 163 records · Page 9Linked to original sources
PubMed1988

Characterization of tetracycline-resistant strains of Ureaplasma urealyticum.

Gel electrophoresis revealed no plasmids in cloned strains of Ureaplasma urealyticum for which minimal inhibitory concentration (MICs) of tetracycline were greater than 64 mg/l. However, DNA from these strains hybridized with the tetM sequence from Streptococcus agalactiae in dot blot hybridization, whilst DNA from more-susceptible strains did not do so. Our results confirm and extend previous work, in which the tetM sequence was associated with resistance to the tetracycline antibiotics in strains of U. urealyticum. The strains examined in this study were isolated primarily in western North America but included representatives from Europe and the United Kingdom. Serotyping showed an increase in strains with the serotype 9 determinant and a decrease in those with the serotype 14 determinant together with a shift to the biotype 2 cluster (P = less than 0.02). To characterize these strains and to identify alternative antibiotics for therapeutic and basic research applications, 26 tetracycline-resistant strains were tested against 25 diverse antimicrobial agents. All demonstrated in-vitro susceptibility to rosaramicin but were resistant to 2 mg/l erythromycin. Only two of the strains were resistant to 16 mg/l erythromycin. Most antibiotics were not active against these isolates, but low concentrations of filipin and unconventional agents such as flurofamide and hydroquinone inhibited the growth of some strains.

Anti-Bacterial Agents↗
PubMed1988

Comparison of methods used to separate the inner and outer membranes of cell envelopes of Campylobacter spp.

The outer membrane of Campylobacter coli, C. jejuni and C. fetus cell envelopes appeared as three fractions after sucrose gradient centrifugation. Each outer membrane fraction was contaminated with succinate dehydrogenase activity from the cytoplasmic membrane fraction. Similarly the inner membrane fraction was contaminated with 2-ketodeoxyoctonate and outer membrane proteins including the porin(s). The separation of these two membranes was not facilitated by variations in lysozyme treatment, cell age, presence or absence of flagella, or longer lipopolysaccharide chain length. Sodium lauroyl sarcosinate extraction resulted in an outer membrane fraction which contained some inner membrane contamination and produced multiple bands upon sucrose gradient centrifugation. Triton X-100 extraction removed the inner membrane from the outer membrane and Triton X-100/EDTA treatment extracted lipopolysaccharide-rich regions of the outer membrane which contained almost exclusively the Campylobacter porin(s). These data indicated that the inner and outer membranes of the Campylobacter cell envelope were very difficult to separate, possibly because of extensive fusions between these two membranes.

Bacteriological Techniques↗
PubMed1988

Characteristics of RP4 tellurite-resistance transposon Tn521.

A restriction map of the tellurite-resistance (Ter) transposon Tn521 (parent plasmid RP4Ter) was prepared. Five sites from RP4Ter, including the EcoRI origin, were found in pIN25::Tn521. Tn521 was inserted into a transferable 27.5 kb vector (pCU109) to make three different insertion mutants, in which the size of Tn521 was measured accurately at 4.5 kb. Unlike the Ter of IncHI2 plasmids, that of Tn521 in RP4Ter was non-inducible. Ter was expressed in five widely differing bacterial species to which RP4Ter was transferred from Escherichia coli. Electron micrographs of bacteria expressing the Ter of RP4Ter, H complex plasmids, and chromosomal mutants, all revealed similar tellurium metal crystallites when the bacteria were grown in potassium tellurite medium. No other Ter determinants were found amongst 54 plasmids representing most incompatibility groups (excluding the H complex).

DNA Transposable Elements↗
PubMed1988

Characterization of freshly isolated Campylobacter coli strains and suitability of selective media for their growth.

Typical and atypical Campylobacter strains were isolated from the colons of cattle and swine by techniques that enabled the selective pressures of antibiotics to be avoided. Some cephalothin-susceptible strains and a strain with an indeterminate hippurate reaction were classified as Campylobacter coli by DNA homology testing. Tetracycline-resistant isolates were obtained from animals with no recorded exposure to antibiotics. A selection of 12 C. coli and 6 C. jejuni strains was used to determine the ability of fresh isolates to grow on a range of selective media. C. coli isolates were inhibited more than C. jejuni on selective media containing antibiotics. The least inhibitory media were Skirrow medium (M. B. Skirrow, Br. Med. J. 2:9-11, 1977) and the charcoal-based media developed by Hutchinson and Bolton (D. N. Hutchinson and F. J. Bolton, J. Clin. Pathol. 37:956-957, 1984) and Karmali et al. (M. A. Karmali, A. E. Simon, M. Roscoe, P. C. Fleming, S. S. Smith, and J. Lane, J. Clin. Microbiol. 23:456-459, 1986). The plasmid contents of the isolates did not appear to be related to their sensitivity to growth on selective (antibiotic-containing) media. The study indicates that selective media used to detect Campylobacter spp. could select against the isolation of C. coli.

Animals↗
PubMed1988

Malpais spring virus: a new vesiculovirus from mosquitoes collected in New Mexico and evidence of infected indigenous and exotic ungulates.

Two virus isolates, 1 each from Aedes campestris and Psorophora signipennis mosquitoes collected in south central New Mexico in August 1985, were shown by neutralization tests to be identical to each other, but not to any of more than 250 arthropod-borne and other viruses. Electron microscopy of 1 isolate (85-488NM, chosen as the prototype) indicated that this strain shares morphologic characteristics with viruses of the family Rhabdoviridae. Indirect fluorescent antibody tests indicated that this virus is a member of the genus Vesiculovirus, but is not closely related to any of the North American or other rhabdoviruses with which it was tested, including vesicular stomatitis (Indiana) and vesicular stomatitis (New Jersey) viruses. The name Malpais Spring virus is proposed for this newly recognized vesiculovirus. A serologic survey indicated that Malpais Spring virus infects indigenous (mule deer and pronghorn) and exotic (gemsbok) ungulates at and near the sites where the mosquitoes from which the virus strains were isolated were collected. Antibody prevalence in wild animals indicates that the pronghorn and gemsbok may play roles as hosts for Malpais Spring, epizootic hemorrhagic disease (New Jersey), and bluetongue viruses in this area.

Aedes↗
PubMed1987

Effects of haemorrhage on wound strength and fibroblast function.

The impairment of healing in laparotomy wounds in rats with compensated oligaemia has been studied in two parallel investigations. Animals bled 1 ml/100 g body weight (bled) were compared with unbled animals undergoing the same operation (control). Firstly, wounds were assessed after 22 days for strength of skin and muscle layers (11 control: 9 bled). Both layers were significantly weaker in bled animals; by 36 per cent for skin (P less than 0.02) and by 22 per cent for muscle (P = 0.02). Secondly, wound fibroblast function was assessed after 10 days by quantitative histology and autoradiography (30 control: 31 bled). There were no significant differences between the two groups for fibroblast density, replication ([3H]thymidine), or general protein synthesis ([3H]leucine). Bled animals had less dense collagen packing by 21 per cent (P less than 0.01), but 33 per cent more incorporation of ([3H]proline) by fibroblasts (P less than 0.01) compared with control animals. The effect of compensated oligaemia on wound healing is more marked in skin than in muscle; it appears to be a specific increase in collagen turnover with the increase in reabsorption exceeding that in synthesis.

Animals↗
PubMed1987

Classification of Campylobacter strains using DNA probes.

DNA homology determinations were used to classify atypical strains of Campylobacter spp. and Campylobacter-like organisms. Using the slot-blot hybridization technique, atypical strains were classified as C. coli or C. jejuni. Some of the Campylobacter-like organisms isolated from animals were catalase-positive, but they did not hybridize with the DNA probes prepared from the total genomic DNA of C. coli, C. jejuni, C. laridis, C. fetus subsp. fetus and C. hyointestinalis. The taxonomic classification of these strains remains uncertain. The slot-blot hybridization technique was simplified by applying whole cells from a 24 h broth culture, instead of pure DNA to nitrocellulose membranes. The results of DNA homology from both methods were comparable, and the classification of these organisms using these methods was the same. Therefore, the dot-blot hybridization method is recommended as a more economical and time-saving method for use in the taxonomic classification of atypical Campylobacter spp.

Base Composition↗
PubMed1987

Immunoblot and enzyme-linked immunosorbent assays of Campylobacter major outer-membrane protein and application to the differentiation of Campylobacter species.

The major outer-membrane protein (MOMP) from Campylobacter jejuni NCTC 11168 was purified by solubilization in Triton X-100. Whole-cell proteins of Campylobacter species and the MOMP were subjected to electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, immunoblotting on nitrocellulose paper and enzyme-linked immunoblot assay (ELISA) analyses using polyclonal antiserum to the C. jejuni MOMP. Purified MOMP from C. jejuni NCTC 11168 contained a single major protein of 46 kDa. Whole-cell preparation of C. jejuni NCTC 11168 also showed a major band of 46 kDa which was recognized in immunoblots by the anti-MOMP serum. Other C. jejuni strains, as well as C. coli and C. laridis strains showed similar MOMP bands at 45-46 kDa. Other Campylobacter species (C. fetus ss. fetus, C. hyointestinalis and C. pylori (new nomenclature] did not react in immunoblots with antiserum to the C. jejuni MOMP. ELISAs showed that antiserum raised against the C. jejuni MOMP reacted with C. jejuni, C. coli and C. laridis strains. Other Campylobacter species displayed only a very low degree of cross-reactivity. The distinct antigenic relationship demonstrated between the MOMP of C. jejuni, C. coli and C. laridis is consistent with the close degree of relatedness of these species as determined by DNA homology studies. The anti-MOMP serum appeared to be useful in the rapid differentiation of C. jejuni, C. coli and C. laridis from other Campylobacter species.

Bacterial Outer Membrane Proteins↗
PubMed1987

Isolation and characterization of Campylobacter pyloridis from gastric biopsies.

Gastric biopsy specimens were examined microbiologically and histologically for the presence of Campylobacter pyloridis. Of 51 randomly selected patients, 22 (43%) were found to harbor C. pyloridis in the gastric mucosa. The histologic demonstration of spiral organisms observed by staining with hematoxylin and eosin correlated well with microbiologic isolation of the organisms. There was a strong association (95.5%) between C. pyloridis in the gastric mucosa and histologically defined gastritis. However, there was no obvious association between C. pyloridis and ulcers. All C. pyloridis strains isolated exhibited uniform biochemical characteristics and had almost identical protein profiles, which indicated that they belong to a relatively homogeneous group distinct from other Campylobacter species. All C. pyloridis isolates were uniformly susceptible to ampicillin, amoxicillin, cephalothin, gentamicin, kanamycin, tetracycline, coumermycin, ciprofloxacin, novobiocin, clorobiocin, and nitrofurantoin. They were moderately resistant to nalidixic acid.

Campylobacter↗
PubMed1987

Input impedance of the canine vertebral artery.

In experiments on six anaesthetized dogs it was found that the vertebral artery contributed 69.2 +/- 1.7% of cerebral and 41.5 +/- 2.5% of cephalic flow. The input characteristics were that the vertebral artery had a flow of 0.71 +/- 0.05 ml X s-1 into an input impedance of 23.7 +/- 1.9 GN X m-5 X s. This compared to external and internal carotid flows of 0.69 +/- 0.05 and 0.31 +/- 0.02 ml X s-1 into input impedances of 23.9 +/- 2.1 and 52.1 +/- 2.7 GN X m-5 X s respectively. Standardized per 100 g of tissue the impedances of the vertebral and internal carotid arteries were similar at 18.6 +/- 2.0 and 19.1 +/- 1.5 GN X m-5 X s X 100 g-1 respectively, while that for the external carotid was higher at 129.9 +/- 10.2 GN X m-5 X s X 100 g-1. The impedance spectrum for the vertebral artery was of low impedance type, settling about a characteristic impedance of 2.01 +/- 0.28 GN X m-5 X s without significant oscillation, associated with the phase only becoming slightly positive above 10 Hz and reflexion coefficients of less than 0.25 by a frequency of 6 Hz. This was similar to the spectrum for the internal carotid artery and contrasted with the high impedance spectrum with major reflexion found for the external carotid artery.

Animals↗
PubMed1987

DNA probes for identification of tetracycline resistance genes in Campylobacter species isolated from swine and cattle.

Tetracycline-resistant strains of Campylobacter jejuni and Campylobacter coli from swine and cattle colons were isolated and characterized by hybridization with DNA probes. A probe consisting of the 1.8-kilobase (kb) HincII fragment from pUA466 was highly specific for the detection of tetracycline resistance (Tcr) in C. jejuni and C. coli. The 5-kb tetM DNA probe from Streptococcus agalactiae plasmid pJI3 which has homology with the 1.8-kb HincII fragment from pUA466 could also be used to detect Tcr Campylobacter strains. However, the tetM probe had a much lower sensitivity and required a lower stringency of hybridization. Therefore, the 1.8-kb HincII fragment appeared to be more appropriate for the classification of Tcr in Campylobacter spp. No homology was detected between the Tcr determinant from Campylobacter spp. and the tetL and tetN probes from Streptococcus spp. DNA homology was demonstrated between pUA649, a derivative of plasmid pUA466 which had lost most of the Tcr region, and Tcr plasmids from C. jejuni and C. coli isolated from animal and human sources. There was also homology between pUA649 and the chromosomes of C. jejuni and C. coli strains. In this study, all but one of the tetracycline-resistant C. coli and C. jejuni strains contained plasmids of approximately 50 kb which hybridized with the 1.8-kb HincII probe. In one C. coli strain (UA703), Tcr appeared to be chromosomally mediated.

Animals↗
PubMed1987

Characterization of transfer regions within the HII incompatibility group plasmid pHH1508a.

A circular map of the 208-kilobase IncHII plasmid pHH1508a was constructed by using the restriction endonucleases XbaI, XhoI, and NotI. Tn5 insertion mutagenesis showed that transfer genes were distributed widely over the plasmid map. Analysis of the deletion mutant pDT1178 indicated that genes required for conjugative pilus production are located in a 96.0-kilobase region of the plasmid.

Chromosome Mapping↗
PubMed1987

Characterization and expression of a cloned tetracycline resistance determinant from Campylobacter jejuni plasmid pUA466.

A tetracycline resistance (Tcr) determinant previously cloned from the Campylobacter jejuni plasmid pUA466 (D. E. Taylor, J. Bacteriol. 165:1037-1039, 1986) was localized by restriction endonuclease mapping, subcloning, and Tn1000 insertion mutagenesis to a 2-kilobase region consisting of 1.8- and 0.2-kilobase HincII fragments. Tcr encoded by the cloned fragment (pUOA1) was expressed constitutively in Escherichia coli. A protein with an apparent molecular weight of 68,000 encoded by pUOA1 was produced in an in vitro transcription-translation system and in minicells. Tn1000 insertions which resulted in inactivation of Tcr expression also resulted in an alteration in the 68,000-molecular-weight protein. Some mutants specified a truncated protein, whereas others completely lost the ability to specify the protein. The protein which appears to be involved in the expression of Tcr specified by C. jejuni plasmids is of approximately the same molecular weight as the protein specified by the streptococcal class M determinant. This finding is consistent with our previous results which indicate that homology exists between the Tcr determinant from C. jejuni and a 5-kilobase HincII probe derived from the streptococcal class M determinant.

Bacterial Proteins↗
PubMed1987

Aneurysm jig for anastomosis technique.

A new jig is described which enables the technique for abdominal aortic aneurysm to be taught and practiced as it is performed by arterial surgeons at the present time. The aneurysm jig enables a plastic simulated aortic aneurysm to be opened as at operation to allow the inlaying of a Dacron tube sutured into place with continuous sutures.

Anastomosis, Surgical↗