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Biomedical subjects

A J Radford

Publications and source records attributed to A J Radford.

15 recordsLinked to original sources
PubMed1992

Removal of false-positive reactions from plasma in an enzyme immunoassay for bovine interferon-gamma.

A monoclonal antibody-based sandwich enzyme immunoassay (EIA) for bovine interferon-gamma (IFN-gamma) has been developed and can be used in conjunction with a whole blood culture system to diagnose tuberculosis in cattle. During its development, normal bovine plasma samples were tested to establish background levels of circulatory IFN-gamma. Of 191 samples tested, 81 (42.4%) were positive (OD > 0.1) when tested undiluted in intact monoclonal antibody (IgG1)-coated wells compared to only 8 (4.2%) in F(ab')2-coated wells, which suggested non-specific interference in the EIA rather than circulatory IFN-gamma. Reactivity of all remaining samples was removed by diluting plasmas 1/2 with 1% casein-PBS-0.05% Tween 20 supplemented with an optimum amount (5%) of normal mouse serum (NMS). Serum pools derived from BALB/c, DBA/2, C3H/HeJ, CBA/CaH and Swiss, but not C57BL/6J, mice were found to inhibit equally the reactions of five strong false-positive bovine plasma samples but had no effect on the titre of IFN-gamma in the sample. Sera from other species tested were less effective. This suggests that the interfering factors possess a high degree of specificity, since the immunoglobulin heavy chain of IgG1 produced by all these five strains of mice are allotypically identical and different to IgG1 produced by C57BL/6J mice. The use of F(ab')2 antibody fragments to coat plate wells and sample diluent containing 5% NMS has resulted in an EIA for bovine IFN-gamma that is virtually free from false-positive reactions, has a high degree of reproducibility and a sample detection limit equivalent to approximately 80 pg/ml recombinant bovine IFN-gamma.

Animals↗
PubMed1992

Characterisation of a novel repetitive DNA sequence from Mycobacterium bovis.

We report characterisation of three copies of a novel repeat sequence isolated from a Mycobacterium bovis genomic library. The repeat occurs within open reading frames, potentially encoding a conserved tandem array of a pentapeptide sequence with the consensus X-Gly-Asn-X-Gly. The tandem array is present up to five times in M. bovis and it is proposed that they may occur in a family of genes expressing functionally related proteins. We postulate that these proteins may play a role in binding of M. bovis to host cell receptors.

Amino Acid Sequence↗
PubMed1992

Rational attenuation of Corynebacterium pseudotuberculosis: potential cheesy gland vaccine and live delivery vehicle.

The phospholipase D (PLD) gene (pld) has been deleted from the Corynebacterium pseudotuberculosis chromosome by using site-specific mutagenesis. Sheep infection trials indicate that the PLD-negative C. pseudotuberculosis strain (Toxminus) is incapable of inducing caseous lymphadentis (cheesy gland) even at doses two logs higher than that at which the wild-type strain produces the disease. This clearly establishes PLD as a major C. pseudotuberculosis virulence factor. Vaccination of sheep with live Toxminus C. pseudotuberculosis elicits strong humoral and cell-mediated immune responses and protects the animals from wild-type challenge.

Animals↗
PubMed1991

Construction and characterization of a Mycobacterium-Escherichia coli shuttle vector.

We have constructed a set of novel Mycobacterium-Escherichia coli shuttle vectors using either a kanamycin- or hygromycin-resistance gene and the replication region from a Corynebacterium plasmid. Important features of these new vectors (pEP2 and pEP3) are that they are small, contain multiple cloning sites, and replicate to high copy number in various Mycobacterium species and E. coli. These vectors are unusual in that plasmid replication in gram-negative and gram-positive bacteria appears to be controlled from a single region. These plasmids will be useful for the genetic analysis of Mycobacterium and gene expression in this genus, particularly Mycobacterium bovis BCG.

Cloning, Molecular↗
PubMed1991

A randomised study of outcomes in a defined group of acutely ill elderly patients managed in a geriatric assessment unit or a general medical unit.

The aim of this study was to identify differences in the medical management and clinical outcome in a group of elderly patients admitted to a designated geriatric assessment unit (GAU) or to two general medical units (GMUs). A prospective randomised controlled trial was undertaken in 267 patients aged 70 years and over (mean age = 78.3 years). Following discharge from hospital, patients were followed up at three monthly intervals for a total of 12 months. At the time of discharge, no significant differences were found in inpatient management, length of stay, mortality rates, discharge rates to institutional care or utilisation of community services in patients admitted to the GAU and the GMUs. Similarly, no significant differences were found at three, six, nine, and 12 month follow up in case fatality, activities of daily living indices, mental health status, rates of institutional referral and the level of community service support in patients admitted to the GAU and the GMUs studied. These findings do not show any advantage for the unselected 70+ acutely ill elderly patient who is admitted to a designated geriatric assessment unit rather than to a general medical unit. Therefore, an admission policy to GAU, based solely on age 70+ is medically inappropriate and cost-inefficient. Evidence from other sources suggests that an age cohort of acutely admitted patients beyond 80 years may well have returned more optimistic findings for the GAU. In future, GAUs will require a more selective admission policy to maximise the benefits of their rehabilitative and interdisciplinary approach.

Acute Disease↗
PubMed1990

Mapping of the T and B cell epitopes of the Mycobacterium bovis protein, MPB70.

A clone coding for the entire gene for the Mycobacterium bovis protein antigen MPB70 was used to produce a series of overlapping subclones by making a series of deletions from the 3' end of the gene. The subclones expressed incomplete MPB70 proteins as fusions with glutathione-S-transferase. The insert DNA was sequenced to determine the extent of the deletion and the proteins expressed by the clones were examined for the presence of T cell and B cell epitopes. T cell epitopes were mapped by measuring the ability of recombinant antigens to stimulate gamma interferon (gamma-IFN) production in a whole blood culture system. gamma-IFN production was measured using a sandwich enzyme immunoassay specific for bovine gamma-IFN. B cell epitopes were mapped with a series of anti-MPB70 monoclonal antibodies using an indirect enzyme immunoassay.

Amino Acid Sequence↗
PubMed1990

Epitope mapping of the Mycobacterium bovis secretory protein MPB70 using overlapping peptide analysis.

The gene encoding the major Mycobacterium bovis secreted protein MPB70 was cloned and isolated from a DNA library in lambda EMBL 3, and the restriction map of the area of chromosome containing the gene ascertained. After sub-cloning, the complete DNA sequence and predicted amino acid sequence were determined, and from this information a series of overlapping octapeptides encoding all possible linear epitopes of eight or less amino acids were synthesized. These peptides were probed with monoclonal antibodies specific for M. bovis and with sera from M. bovis-infected cattle. Epitopes defined by this technique were then examined using a substitution analysis that allowed the significance of each amino acid in the putative epitope to be quantified, and the exact specificity of the antibody response for the epitope determined.

Amino Acid Sequence↗
PubMed1976

Social aspects in the changing epidemiology of malaria in the highlands of New Guinea.

The increase in movement of people both within the highlands of New Guinea and also to and fro between holo- and hyperendemic lowland areas and the highlands by policemen and semi-skilled personnel in one direction and by labourers in the other, together with a great increase in potential breeding sites, were virtually inevitable consequences of the development process as the intense communalism and geographical isolation of the highland people was broken down. Prior to the "opening up" of the highlands, evidence suggests that malaria had existed in an endemic and very unstable form in only a few lower altitude areas and in the populations of the perimeter villages who had contact with lowland areas. This paper traces the changes in the distribution and determinants of malaria that occurred pari passu with the development process in the highlands of Papua New Guinea between 1930 and 1970.

Agriculture↗
PubMed1976

Giant millipede burns in Papua New Guinea.

Three patients with superficial burns to the face and neck from benzo-quinone derivatives in the excretions of giant millipeds of the Spirobolus family are reported from the Northern District of Papua. A review is made of the clinical features and treatment of these burns.

Arthropods↗
PubMed1975

Mycobacterium ulcerans in Australia.

The epidemiology of 39 case reports of infection with Mycobacterium ulcerans published during the past 25 years in Australia is presented. A review is made of the laboratory findings of the strains found in Australia and of the contribution of Australian workers to the description, treatment and prevention of this disfiguring disease.

Adolescent↗
PubMed1975

Millipede burns in man.

A review is made of the clinical features and treatment of the lesions caused by the secretions of millipedes. The toxicology of these secretions is discussed. The geographical distribution is reviewed. The species identified as inflicting injury to man are enumerated. Lesions of soft parts of the skin can be moderately severe. Eye injuries may be serious and must receive effective treatment rapidly to prevent residual damage.

Age Factors↗