PubMed Health⌕ Search

Biomedical subjects

Mark Roberts

Publications and source records attributed to Mark Roberts.

31 records · Page 2Linked to original sources
PubMed2003

New members of the Escherichia coli sigmaE regulon identified by a two-plasmid system.

A previously established method, based on a two-plasmid system, was used to identify promoters recognized by RNA polymerase containing the extracytoplasmic stress response sigma factor sigmaE in Escherichia coli. In addition to previously identified rpoE-dependent promoters, 11 new promoters potentially directing the expression of 15 genes were identified that were active only after over-expression of rpoE. The promoters were confirmed and transcriptional start points of the promoters were determined by primer extension analysis and S1-nuclease mapping. All the promoters contained sequences similar to the consensus sequence of rpoE-dependent promoters. The new rpoE-dependent promoters governed expression of genes encoding proteins involved in primary metabolism (fusA, tufA, recR), phospholipid and lipopolysaccharide biosynthesis (psd, lpxP), signal transduction (sixA), proposed inner or outer membrane proteins (bacA, sbmA, smpA, yeaY), and proteins with unknown function (ybaB, yaiW, yiiS, yiiT, yfeY).

Base Sequence↗
PubMed2003

Use of Bordetella bronchiseptica and Bordetella pertussis as live vaccines and vectors for heterologous antigens.

Bordetella pertussis and Bordetella bronchiseptica are respiratory pathogens of humans and animals respectively. Unlike many bacteria, they are able to efficiently colonise healthy ciliated respiratory mucosa. This characteristic of Bordetella spp. can potentially be exploited to develop efficient live vaccines and vectors for delivery of heterologous antigens to the respiratory tract. Here we review the progress in this area.

Animals↗
PubMed2003

Pharmacist involvement in a multidisciplinary inpatient medication education program.

The development of a multidisciplinary inpatient medication education program is described. A multidisciplinary group designed and implemented a medication education program with defined roles for both nurses and pharmacists. Nurses provided medication education to patients during each medication administration using specially designed assessment and teaching tools. The nursing staff submitted requests for pharmacist consultations for patients with complex medication regimens, who were admitted because of a drug-related problem or who required additional teaching as determined through the medication education assessment form. A complex medication regimen was defined as the administration of oral medication more than five different times per day, the start of at least 5 new medications that would be continued at discharge, or the prescribing of at least 10 medications to be taken daily that would be continued at discharge. Pharmacists provided education for 19% of admitted patients during a six-month period. As a result of pharmacists' interactions with prescribers and nurses, the number of medications was reduced in 12% of these patients, and the number of medication administrations each day was reduced in 19% of patients. In addition, for 33% of patients, pharmacists contacted the prescriber to make recommendations beyond the scope of the medication education program that optimized and simplified the patient's drug regimen. The development of a structured medication education program allowed patients to receive medication education throughout their hospitalization from both nurses and pharmacists. Pharmacists provided education for patients at highest risk for noncompliance or poor outcomes. Full implementation of a medication education program involving staff pharmacists is planned.

Administration, Oral↗
PubMed2003

Cloning and characterisation of type 4 fimbrial genes from Actinobacillus pleuropneumoniae.

Actinobacillus pleuropneumoniae is the cause of porcine pleuropneumoniae. Little is known about the mechanisms by which A. pleuropneumoniae colonises the respiratory tract. Fimbriae are common mediators of bacterial adherence to mucosal epithelia and have been observed on the surface of A. pleuropneumoniae cells. Here we report the identification and characterisation of the type 4 fimbrial structural gene (apfA) from A. pleuropneumoniae. In addition a number of open reading frames were identified in A. pleuropneumoniae that have significant homology to type 4 fimbrial biogenesis genes from other species, including a putative leader specific peptidase (apfD). A. pleuropneumoniae apfA codes for a predicted polypeptide of approximately 16kDa, removal of the leader sequence at the predicted cleavage site would yield a 14.5kDa polypeptide. The first 30 residues of the mature polypeptide are well conserved with other members of the group A type 4 fimbriae family. The signal sequence of ApfA is 13 amino acids in length and, unusually, the residue that precedes the cleavage site is alanine rather than glycine which is found in most other type 4 fimbriae. The C-terminus of ApfA possesses cysteine residues that are conserved in type 4 fimbriae of many species. In other type 4 fimbriae the distal C-terminal cysteines form a disulphide bond that produces a loop, which is important for the function of fimbriae and also comprises a major antigenic determinant. A motif within the predicted loop in ApfA was found to be highly conserved in type 4 fimbriae of other HAP organisms (Haemophilus, Actinobacillus, Pasteurella). The A. pleuropneumoniae type 4 fimbrial biogenesis genes showed the strongest homology to putative type 4 fimbrial genes of Haemophilus ducreyi. A. pleuropneumoniae apfA gene was shown to be present and highly conserved in different serotypes of A. pleuropneumoniae. Recombinant ApfA was produced and used to raise anti-ApfA antisera.

Actinobacillus pleuropneumoniae↗
PubMed2003

Software for automatic calibration of synchrotron powder diffractometers.

An automatic procedure to calibrate angular-dispersive monochromatic diffraction instruments has been developed at the Daresbury Synchrotron Radiation Source. The procedure uses a macro Language to control the powder diffraction instruments to locate Bragg reflections and perform peak-centre refinement from a standard reference material. The information obtained is used to refine the wavelength of the radiation used and the angular offset of the detector arm. The concept and implementation of the new software are described with applications to demonstrate its viability. The results of a reliability and accuracy study are also presented.

Journal Article↗
PubMed2003

An adapted ImmunoMagnetic cell separation method for use in quantification of Escherichia coli O157:H7 from bovine faeces.

Detection of Escherichia coli O157:H7 organisms in food, clinical or environmental samples is necessary for diagnosis of infection and epidemiological investigations. However, this pathogen may be present in low numbers and difficult to identify among high numbers of other background bacteria. In order to increase the sensitivity of culture- and PCR detection, pre-enrichment of E. coli O157:H7 in broth culture combined with ImmunoMagnetic cell Separation (IMS) is routinely employed. These methods, although able to detect levels as low as 2 cfu/g (from 10 to 25 g samples), are qualitative detection strategies only. If the actual numbers of E. coli O157:H7 are to be quantified, growth enrichment must be excluded and the organisms isolated directly from the sample of interest. Such quantification is necessary, for example, to determinate contamination levels on beef carcasses and for determination of bacterial numbers in in vivo gene expression studies. In the present study, it was not possible to recover organisms from bovine faecal suspensions using the customary IMS system and so a range of alternative buffers and other paramagnetic beads was tested. Combination of a 6.2-microm diameter bead with a detergent-based buffer gave optimal recovery of E. coli O157:H7 organisms from faecal suspensions. This system was validated for recovery of E. coli O157:H7 by comparing it with that obtained with the standard Dynabeads IMS protocol, using both the traditional broth enrichment method and a quantitative detection approach. We conclude that a 6.2-microm diameter Aureon bead can be used for quantitative isolation of E. coli O157:H7 directly from bovine faeces and, for this purpose, is preferred to the 2.8-microm diameter Dynal bead.

Animals↗
PubMed2003

Role of periplasmic peptidylprolyl isomerases in Salmonella enterica serovar Typhimurium virulence.

FkpA is a peptidylprolyl isomerase whose expression is regulated by the alternative sigma factor, sigma factor E (sigma(E)). In contrast to the results of a previous report, inactivation of fkpA was found to have only a minor effect on the ability of Salmonella enterica serovar Typhimurium to invade and survive within epithelial and macrophage cell lines and cause infection in mice. However, an effect of the fkpA mutation on serovar Typhimurium virulence was seen if the mutation was combined with mutations in surA or htrA, two other sigma(E)-regulated genes, which encode proteins involved in protein folding and/or degradation in the periplasm.

Animals↗
PubMed2003

Targeted disruption of the PDZK1 gene by homologous recombination.

Proteins containing PDZ domains are involved in a large number of biological functions, including protein scaffolding, organization of ion channels, and signal transduction. We recently identified a novel PDZ domain-containing protein, PDZK1, that is selectively expressed in normal tissues, where it is associated and colocalized with MAP17, a small 17-kDa membrane-associated protein; cMOAT, an organic anion transporter implicated in multidrug resistance; and the type IIa Na/Pi cotransporter. The protein cluster formed by PDZK1, MAP17, and cMOAT is upregulated in a significant number of human carcinomas originating in the colon, breast, lung, and kidney. In order to better define the function of PDZK1 in the protein cluster and its potential role in the organization of ion channels, we generated a PDZK1 knockout mouse. While PDZK1-deficient mice developed normally, did not display any gross phenotypic abnormalities, and were fecund, lack of PDZK1 resulted in modulation of expression of selective ion channels in the kidney, as well as increased serum cholesterol levels. However, no significant redistribution of proteins known to interact with PDZK1, such as MAP17, cMOAT, and the type IIa Na/Pi cotransporter, was observed. The absence of a more significant phenotype in PDZK1-deficient mice may be due to functional compensation by other PDZ domain-containing proteins, which could be instrumental in determining the location of interacting proteins such as ion channels and other membrane-associated proteins in defined areas of the plasma membrane.

Amino Acid Sequence↗
PubMed2002

Use of a rationally attenuated Bordetella bronchiseptica as a live mucosal vaccine and vector for heterologous antigens.

Inactivation of the aroA gene of Bordetella bronchiseptica severely impaired its ability to colonise the respiratory tract of mice. The B. bronchiseptica aroA mutant was investigated as a live vaccine and vector for heterologous antigens. The B. bronchiseptica aroA mutant expressing the non-toxic fragment C (FrgC) of tetanus toxin (strain GVB120) was used to immunise mice intranasally. Immunised mice produced a strong serum and mucosal antibody response to B. bronchiseptica and serum anti-FrgC antibodies. Upon challenge with wild type B. bronchiseptica, immunised mice rapidly reduced the numbers of B. bronchiseptica in their respiratory tract, although clearance was more pronounced in the lower than in the upper respiratory tract. Immunisation with GVB120 protected approximately 40% of mice from tetanus toxin challenge. As far as we are aware, this is the first description of a recombinant B. bronchiseptica strain being used as a live vaccine vector for heterologous antigens.

Administration, Intranasal↗
PubMed2002

The starvation-stress response of Salmonella enterica serovar Typhimurium requires sigma(E)-, but not CpxR-regulated extracytoplasmic functions.

Starvation of Salmonella enterica serovar Typhimurium (S. Typhimurium) for an exogenous source of carbon and energy (C-starvation) induces the starvation-stress response (SSR). The SSR functions to (i) maintain viability during long-term C-starvation and (ii) generate cross-resistance to other environmental stresses. The SSR is, at least partially, under the control of the alternative sigma factor, sigma(S). It is hypothesized that C-starvation causes cell envelope stresses that could induce the sigma(E) and/or Cpx regulons, both of which control extracytoplasmic functions and, thus, may play a role in the regulation of the SSR. In support of this hypothesis, Western blot analysis showed that the relative levels of sigma(E) increased during C-starvation, peaking after approximately 72 h of C-starvation; in contrast, CpxR levels remained relatively constant from exponential phase up to 72 h of C-starvation. To determine if sigma(E), and thus the regulon it controls, is an essential component of the SSR, several mutant strains were compared for their abilities to survive long-term C-starvation and to develop C-starvation-induced (CSI) cross-resistances. An rpoE mutant strain was significantly impaired in both long-term C-starvation survival (LT-CSS) and in CSI cross-resistance to challenges with 20 mM H(2)O(2) for 40 min, 55 degrees C for 16 min, pH 3.1 for 60 min and 870.2 USP U polymyxin B ml(-1) (PmB) for 60 min, to varying degrees. These results suggest that C-starvation can generate signals that induce the rpoE regulon and that one or more members of the sigma(E) regulon are required for maximal SSR function. Furthermore, evidence suggests that the sigma(E) and sigma(S) regulons function through separate mechanisms in the SSR. In contrast, C-starvation does not appear to generate signals required for Cpx regulon induction which support the findings that it is not required for LT-CSS or cross-resistance to H(2)O(2), pH 3.1 or PmB challenges. However, it was required to achieve maximal cross-resistance to 55 degrees C. Therefore, sigma(E) is a key regulatory component of the SSR and represents an additional sigma factor required for the SSR of Salmonella.

Bacterial Proteins↗
PubMedDate not supplied

The impact of community rehabilitation for acquired brain injury on carer burden: an exploratory study.

OBJECTIVES: This study evaluated the relative efficacy of a community rehabilitation service and a more traditional outpatient service for carers of people with an acquired brain injury. METHODS: Seventeen carers who had received a community intervention were retrospectively compared with 24 carers who had received an outpatient service. Dependent variables were level of met family need, a measure of family dysfunction, carer psychopathology, and carer emotional acceptance. RESULTS: The community sample fared significantly better on all measures except carer psychopathology. CONCLUSIONS: These results suggest that community-based services have efficacy for the carer and family. There is a clear need for large clinical trials using standardized instruments to establish what models of service delivery benefit carers.

Adult↗