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Biomedical subjects

R Hope

Publications and source records attributed to R Hope.

At least 19 recordsLinked to original sources
PubMed2006

Efficacy of practised screening methods for detection of cephalosporin-resistant Enterobacteriaceae.

OBJECTIVES: Enterobacteriaceae with extended-spectrum beta-lactamases (ESBLs) are now widespread and simple phenotypic tests are required to detect them in diagnostic laboratories. We investigated the performance of screening methods at 16 hospitals in South-East England. METHODS: Sixteen laboratories in South-East England submitted 1195 consecutive Enterobacteriaceae isolates found to be resistant, by their routine methods, to any or all of cefpodoxime, ceftazidime and cefotaxime. These isolates were re-tested centrally with various cephalosporin/clavulanate combinations and with multiplex PCR for bla(CTX-M) and bla(AmpC) alleles. RESULTS: Screening methods among the laboratories were the following: cefpodoxime discs alone (1 site); cefpodoxime, cefotaxime and ceftazidime discs (9 sites) or agar dilution (1 site); Phoenix (2 sites), Vitek 1 (1 site) and Vitek 2 (2 sites). A total of 8% of isolates submitted based on disc tests proved fully cephalosporin-susceptible, compared with 3% sent based on tests with automated systems and none of those sent based on agar dilution tests. Among isolates submitted solely on cefpodoxime resistance 256/372 (69%) proved cephalosporin-susceptible or had only borderline resistance with no clear mechanism demonstrable; this proportion decreased to 28/160 (18%) for those submitted on the basis of resistance to ceftazidime, 18/122 (15%) for those resistant to cefotaxime and 26/496 (5%) for those resistant to both cefotaxime and ceftazidime. The inference of ESBL production by Vitek 2 had the best agreement with reference laboratory results. CONCLUSIONS: Many isolates found resistant only to cefpodoxime at the source sites proved not to have ESBLs or AmpC; screening with cefotaxime and ceftazidime allowed better specificity for identification of mechanism-based resistance, as did the automated systems. Cefpodoxime disc tests nevertheless remain a useful primary screen for laboratories prepared only to test one agent.

Cephalosporins↗
PubMed2005

Effect of medium type, age and aeration on the MICs of tigecycline and classical tetracyclines.

BACKGROUND: Tigecycline is a minocycline derivative, belonging to a chemical class prone to oxidation and to medium-related effects on susceptibility. We therefore studied the effect of medium type and age on the tigecycline MICs found in broth and on agar by the Clinical Laboratory Standards Institute and British Society for Applied Chemotherapy methods. METHODS: MICs of tigecycline, minocycline and tetracycline were determined for 96 non-fastidious bacteria and 20 streptococci using Mueller-Hinton broth (MHB), Mueller-Hinton agar (MHA), Iso-Sensitest broth (ISB) and Iso-Sensitest agar (ISA) as: (i) freshly-prepared media; (ii) fresh media but with the antibiotic added 1 day before inoculation and (iii) media stored for 7 days before antibiotic addition and use. RESULTS: MICs of tigecycline in fresh MHB were up to two doubling dilutions higher than on or in MHA, ISA or ISB. Media with tigecycline or classical tetracyclines added a day before use gave raised MICs, though rarely by more than one dilution. MICs of tigecycline (less so classical tetracyclines) were increased in 7-day-old MHB or ISB, even though the antibiotic was freshly added. This latter effect was greatest for the most susceptible strains and was absent or much reduced for organisms with MICs > or = 8 mg/L; it did not occur in the corresponding agar dilution tests. Addition of blood to MHB largely abrogated the effect, as did steaming the broth before adding the antibiotic. CONCLUSIONS: The raised MICs of tigecycline in aged broth probably reflect inactivation by dissolved oxygen. This accords with the lack of any MIC increase in newly-steamed (i.e. degassed) MHB or on aged agar (which is melted at 100 degrees C before use). Blood, which also abrogated the effect, may increase reducing capacity, protecting the tigecycline. At a practical level, broth MIC determinations for tigecycline should always employ fresh media.

Anti-Bacterial Agents↗
PubMed2005

Comparison of environmental profiles for growth and deoxynivalenol production by Fusarium culmorum and F. graminearum on wheat grain.

AIMS: Comparisons were made of the effect of water activity (a(w) 0.99-0.85), temperature (15 and 25 degrees C) and time (40 days) on growth/production of the trichothecene mycotoxin deoxynivalenol (DON) by Fusarium culmorum and Fusarium graminearum on wheat grain. METHODS AND RESULTS: Studies examined colonization of layers of wheat grain for 40 days. Fusarium culmorum grew optimally at 0.98 a(w) and minimally at 0.90 a(w) at 15 and 25 degrees C. Colonization by F. graminearum was optimum at 0.99 a(w) at 25 and 0.98 a(w) at 15 degrees C. Overall, temperature, a(w) and their interactions significantly affected growth of both species. Production of DON occurred over a much narrower range (0.995-0.96 a(w)) than that for growth. Optimum DON was produced at 0.97 and 0.99 a(w) at 15 and 25 degrees C, respectively, by F. culmorum, and at 0.99 a(w) and 15 degrees C and 0.98 a(w) at 25 degrees C for F. graminearum. Statistically, one-, two- and three-way interactions were significant for DON production by both species. CONCLUSIONS: This suggests that the ecological requirements for growth and mycotoxin production by such species differ considerably. The two-dimensional profiles on grain for DON production by these two species have not been examined in detail before. SIGNIFICANCE AND IMPACT OF THE STUDY: This type of information is essential for developing climate-based risk models for determining the potential for contamination of cereal grain with this trichothecene mycotoxin. It will also be useful information for monitoring critical control points in prevention of such toxins entering the wheat production chain.

Food Contamination↗
PubMed2005

Sequencing and mapping hemoglobin gene clusters in the Australian model dasyurid marsupial Sminthopsis macroura.

Comparing globin genes and their flanking sequences across many species has allowed globin gene evolution to be reconstructed in great detail. Marsupial globin sequences have proved to be of exceptional significance. A previous finding of a beta(beta)-like omega(omega) gene in the alpha(alpha) cluster in the tammar wallaby suggested that the alpha and beta cluster evolved via genome duplication and loss rather than tandem duplication. To confirm and extend this important finding we isolated and sequenced BACs containing the alpha and beta loci from the distantly related Australian marsupial Sminthopsis macroura. We report that the alpha gene lies in the same BAC as the beta-like omega gene, implying that the alpha-omega juxtaposition is likely to be conserved in all marsupials. The LUC7L gene was found 3' of the S. macroura alpha locus, a gene order shared with humans but not mouse, chicken or fugu. Sequencing a BAC contig that contained the S. macroura beta globin and epsilon globin loci showed that the globin cluster is flanked by olfactory genes, demonstrating a gene arrangement conserved for over 180 MY. Analysis of the region 5' to the S. macroura epsilon (epsilon) globin gene revealed a region similar to the eutherian LCR, containing sequences and potential transcription factor binding sites with homology to eutherian hypersensitive sites 1 to 5. FISH mapping of BACs containing S. macroura alpha and beta globin genes located the beta globin cluster on chromosome 3q and the alpha locus close to the centromere on 1q, resolving contradictory map locations obtained by previous radioactive in situ hybridization.

Animals↗
PubMed2003

Two-dimensional environmental profiles of growth, deoxynivalenol and nivalenol production by Fusarium culmorum on a wheat-based substrate.

AIMS: To determine the effect of interacting conditions of water activity (aw, 0.99-0.85), temperature (15, 25 degrees C) and time (40 days) on growth and production of the mycotoxins deoxynivalenol (DON) and nivalenol (NIV) by Fusarium culmorum on a wheat-based agar medium. METHODS AND RESULTS: Fusarium culmorum grew optimally at 0.995aw and minimally at 0.90 at both 15 and 25 degrees C. No growth was observed at <0.90aw. Overall, temperature, aw and their interaction had a statistically significant effect on the growth rate of F. culmorum. Production of both DON and NIV were over a much narrower range (0.995-0.95aw) than that for growth. The highest concentrations of DON and NIV levels were produced at 0.995aw and 0.981aw at 25 degrees C, respectively, after 40 days of incubation. Statistically, aw, temperature and incubation time, and aw x temperature and temperature x incubation time had a statistically significant effect on DON/NIV production. CONCLUSIONS: This is the first detailed report on the two-dimensional environmental profiles for DON/NIV production by F. culmorum in the UK. SIGNIFICANCE AND IMPACT OF THE STUDY: As part of a hazard analysis critical control point (HACCP) approach, this type of information is critical in monitoring critical control points for prevention of DON/NIV entering the wheat production chain.

Culture Media↗
PubMed2001

An orphaned mammalian beta-globin gene of ancient evolutionary origin.

Mammals possess multiple, closely linked beta-globin genes that differ in the timing of their expression during development. These genes have been thought to be derived from a single ancestral gene, by duplication events that occurred after the separation of the mammals and birds. We report the isolation and characterization of an atypical beta-like globin gene (omega-globin) in marsupials that appears to be more closely related to avian beta-globin genes than to other mammalian beta-globin genes, including those previously identified in marsupials. Phylogenetic analyses indicate that omega-globin evolved from an ancient gene duplication event that occurred before the divergence of mammals and birds. Furthermore, we show that omega-globin is unlinked to the previously characterized beta-globin gene cluster of marsupials, making this the first report of an orphaned beta-like globin gene expressed in a vertebrate.

Amino Acid Sequence↗
PubMed1999

Evolution and molecular characterization of a beta-globin gene from the Australian Echidna Tachyglossus aculeatus (Monotremata).

Coinciding with a period in evolution when monotremes, marsupials, and eutherians diverged from a common ancestor, a proto-beta-globin gene duplicated, producing the progenitors of mammalian embryonic and adult beta-like globin genes. To determine whether monotremes contain orthologues of these genes and to further investigate the evolutionary relationships of monotremes, marsupials, and eutherians, we have determined the complete DNA sequence of an echidna (Tachyglossus aculeatus) beta-like globin gene. Conceptual translation of the gene and sequence comparisons with eutherian and marsupial beta-like globin genes and echidna adult beta-globin indicate that the gene is adult expressed. Phylogenetic analyses do not clearly resolve the branching pattern of mammalian beta-like globin gene lineages and it is therefore uncertain whether monotremes have orthologues of the embryonic beta-like globin genes of marsupials and eutherians. Four models are proposed that provide a framework for interpreting further studies on the evolution of beta-like globin genes in the context of the evolution of monotremes, marsupials, and eutherians.

Amino Acid Sequence↗
PubMed1998

Community services. The home team.

Reorganising a mental health service for elderly people to ensure most care can be given in the client's home has led to a dramatic decrease in admissions. Length of inpatient stay has not fallen, probably because those now admitted are more severely ill. The service is based on community mental health teams and places great reliance on healthcare assistants.

Aged↗
PubMed1993

Genetic variation within and between strains of outbred Swiss mice.

The aim of this survey was to measure levels of genetic variation within and between 5 different strains of outbred Swiss mice. Ten to 15 animals from each strain (NIH, Q(S), ARC, IMVS and STUD) were typed, using allozyme electrophoresis, at 10 gene loci: Mod-1, Idh-1, Gpi-I, Es-1, Es-3, Hbb, Pep-3, Gr-1, Got-2 and Pgm-1. Polymorphic variation in at least one of the 5 strains was detected at all 10 loci. The proportion of polymorphic loci ranged from 0.3 (NIH) to 0.8 (IMVS) with a mean of 0.52. Average expected heterozygosities ranged from 0.08 (NIH) to 0.37 (IMVS) with a mean of 0.21. The inbred strain SWR was, as expected, homozygous at all 10 loci. The amount of allelic substitution between pairs of strains was quantified using Nei's genetic distance, and a dendrogram based on these genetic distances showed a close overall similarity in its branching pattern to the known genealogy of the strains. This survey showed that a considerable degree of genetic variation persists in the 5 strains examined, a level of variation similar to that previously detected by Rice and O'Brien (1980) in 3 other outbred Swiss strains.

Animals↗
PubMed1992

Restriction fragment length variants in the marsupial Sminthopsis crassicaudata.

A fully pedigreed colony of the dasyurid marsupial Sminthopsis crassicaudata has provided material for establishing two panels of DNA samples: a broadbased test panel and a two-generation family panel. These have been used to search for genetic markers in the form of restriction fragment length variants. The molecular probes--pSG-2H, a region of the S. crassicaudata embryonic beta-globin gene; pB8.BS, a region of the human ubiquitin gene, and p3-21a1:1, a region of the processed pseudogene of phosphoglycerate kinase-1 of the macropodid marsupial Macropus robustus--were hybridized to Southern blots of EcoR1-digested DNA from the panels. Analysis of these blots when probed with pSG-2H provided evidence of two alleles segregating at a single EcoR1 site. Analysis of the same blots when probed with pB8.BS suggested allelic variation at two closely linked EcoR1 sites. Probing the blots with p3-21a1:1 produced a complex pattern of bands resembling DNA fingerprints. The presence of a 12.3-kb band was found to conform to a simple autosomal dominant mode of inheritance. Analysis of the family data, for each probe, revealed no significant departure from Mendelian inheritance. This work has provided additional genetic markers that will enhance the use of S. crassicaudata as a model marsupial species and has demonstrated that a high level of genetic variability has been maintained in the marsupial colony.

Animals↗
PubMed1988

Scalping injuries: new technique for stabilization of flaps to the skull.

Extensive scalping injuries offer a unique challenge for tissue coverage because of the wide expanse of bone and lack of deep soft tissue or significant perforating vessels. For smaller injuries, pedicle flaps offer ideal coverage. Larger defects can be covered by omental flaps. Coverage with a free muscle flap followed by split-thickness skin grafting offers optimal long-term coverage. Two new techniques are introduced. The wire-button technique offers stabilization, and the halo frame provides good support and protection for a new free-flap graft and may increase the success rate of flaps in patients with scalping injuries.

Humans↗
PubMed1987

Localization of MIC5 to the region between HPRT and G6PD on the human X chromosome.

The X-linked gene, MIC5, encodes a human cell-surface antigen, R1. We have assigned MIC5 to the region between HPRT and G6PD on the long arm of the X chromosome. Regional localization was based on the pattern of reactivity of the R1 monoclonal antibody with human-rodent somatic cell hybrids which contained different fragments of the human X chromosome.

Antibodies, Monoclonal↗