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Biomedical subjects

C Clayton

Publications and source records attributed to C Clayton.

At least 73 records · Page 4Linked to original sources
PubMed1992

Communication aids for children: procedures and problems.

This paper describes the organisation and procedures of the Communication Aids Centre for children at the Wolfson Centre, London, including a model for assessment and recommendation of appropriate aids, such as symbol charts, switches and speech synthesisers. Of the children seen over an 18-month period, most had cerebral palsy and two-thirds were wheelchair-dependent. Almost half were assessed before the age of five years. A detailed follow-up of nine children is presented which reveals how long children may have to wait for the provision of an aid in the UK. Possible problems in establishing use of an aid are discussed; these include inadequate training of children and their communication partners. Suggestions for future improvements of communication-aids services are explored.

Adolescent↗
PubMed1991

Anatomy of the parp gene promoter of Trypanosoma brucei.

While growing in the tsetse fly, Trypanosoma brucei expresses a major surface glycoprotein, the procyclic acidic repetitive protein (PARP). The parp genes are transcribed by an alpha-amanitin-resistant RNA polymerase. We have determined the sequence requirements for parp promoter activity. Studies of RNA produced from input DNA in transiently transfected trypanosomes indicate that the RNA is correctly processed by trans-splicing and polyadenylation. Deletion analyses show that 330 bp are sufficient for full promoter and splicing activity and that the promoter structure is complex, involving at least three elements whose mutual spacing is important. Mutagenesis pin-pointed two sequences vital for promoter activity; neither bears any resemblance to known prokaryotic or eukaryotic promoter elements.

Animals↗
PubMed1991

Recognition of a peroxisomal tripeptide entry signal by the glycosomes of Trypanosoma brucei.

Trypanosomes compartmentalise the first 9 enzymes of glycolysis and glycerol metabolism in peroxisome-like microbodies known as glycosomes. The identity of the sequences that direct proteins into the glycosome has until now been uncertain. We show here that the peroxisomal tripeptide entry signal is sufficient to cause association of a bacterial enzyme with the glycosomes of Trypanosoma brucei. However, it works less efficiently than the C-terminal 21 amino acids of trypanosome glycosomal phosphoglycerate kinase.

Amino Acid Sequence↗
PubMed1991

Detection and identification of Helicobacter pylori by the polymerase chain reaction.

A polymerase chain reaction for the specific detection of Helicobacter pylori was developed using a primer pair derived from the nucleotide sequence of the urease A gene of H pylori. Specific amplification of a 411 base pair DNA fragment from all strains of H pylori tested was achieved. Ten organisms were detected using the PCR and the technique permitted direct detection of H pylori in clinical biopsy samples. PCR will be useful for both prospective and retrospective investigation of the aetiology and epidemiology of H pylori associated disease.

Base Sequence↗
PubMed1990

Genetic analysis of a tetracycline resistance element from Clostridium difficile and its conjugal transfer to and from Bacillus subtilis.

A tetracycline resistance (Tcr) determinant from Clostridium difficile strain 630 was cloned into the Escherichia coli plasmid vector pUC13. The resulting plasmid pPPM20, containing an insert of 3.4 kbp, was mapped and a 1.1 kbp SacI-HindIII fragment wholly within the Tcr gene was identified. Dot-blot hybridization studies with the 1.1 kbp fragment showed that the Tcr gene belonged to hybridization class M. Tcr could be transferred between C. difficile strains and to Bacillus subtilis at a frequency of 10(-7) per donor cell. The element could be returned from B. subtilis to C. difficile at a frequency of 10(-8) per donor cell. This is the first demonstration of C. difficile acting as a recipient in intergeneric crosses. DNA from C. difficile transconjugants digested with EcoRV always has two hybridizing fragments of 9.5 and 11.0 kbp when probed with pPPM20. DNA from B. subtilis transconjugants digested with EcoRV produced one hybridizing band of variable size when probed with pPPM20. The behaviour of the element was reminiscent of the conjugative transposons. Therefore we compared the element to the conjugative transposon Tn916. The HincII restriction maps of the two elements differed and no hybridization was detected to oligonucleotides directed to the ends of Tn916. However, the elements do have some sequence homology, detected by hybridization analysis.

Bacillus subtilis↗
PubMed1989

Comparative costs of cataract surgery in a public and a private hospital.

A total of 119 patients undergoing cataract surgery in Wellington and Wellcare hospitals were studied for their demographic characteristics and the costs of their surgery. There were no significant age or sex differences between public and private sector patients and, although there were marital, ethnic and socioeconomic factors which were associated with a slightly longer stay in the public sector, these explain only a small proportion of the difference of 5.0 days in public as compared with 2.5 days stay in the private sector. The pattern of care adopted by the consultant and ward staff and medical profile affected the length of stay. The costs of the surgery were identical at $2560, including GST, in both public and private hospitals. Higher ward costs in public were offset by higher surgical costs in the private sector. A study of the marginal costs, on a day by day basis, indicated that a reduction in length of stay to 3.6 days, which has already occurred since the study, would lead to an 11% increase in throughout of cataract patients within a fixed budget. These costing data will be routinely provided by the RUS (resource utilisation system) now being implemented in New Zealand hospitals and will be an important tool for service management in making decisions about both quality of care and cost containment.

Aged↗
PubMed1988

Recent trends in the availability, distribution, utilisation and cost of general practitioner services.

GMS data for the 1983-4 and 1986-7 years were analysed to determine the availability, distribution and utilisation of general practitioners in New Zealand. In 1986-7 there were 1724 full time equivalents (FTE) general practitioners, one per 1923 population, an annual increase in availability of 2.8% over the three years studied. The rate of availability appears to be increasing rapidly and, from Medical Council data, was around 6% for the 1986-7 year. Wide variation exists in availability, the highest being in central Auckland with one general practitioner per 1351 population, the lowest being in Invercargill with one per 2500. Utilisation increased by just over 1% annually to 3.9 services per person. The median workload in 1986-7 was 7184 services per general practitioner equivalent to a GMS income of $31,454. Each general practitioner was associated with government expenditure of about $359,000 but received only about $33,670 of this, less than one seventh of that paid by government for pharmaceuticals. Radical changes are proposed to redress inefficiencies, inequities and the perverse incentives which continue to increase in this almost totally unmanaged but fundamentally important area of health care.

Costs and Cost Analysis↗
PubMed1988

Molecular cloning and genetic analysis of a chloramphenicol acetyltransferase determinant from Clostridium difficile.

A gene bank from a clinical isolate of Clostridium difficile expressing high chloramphenicol acetyltransferase activity was constructed by cloning Sau3A-cleaved clostridial DNA fragments into the plasmid vector pUC13. Among 1,020 clones tested, 11 were resistant to chloramphenicol; 1 of these, with an insert size of 1.9 kilobases (pPPM9), was studied further. The clone pPPM9 was mapped using a variety of restriction enzymes, and a 0.27-kilobase EcoRV-TaqI restriction fragment was shown to be within the chloramphenicol resistance (Cmr) gene by using transposon (Tn1000) mutagenesis. The 0.27-kilobase fragment and the 1.9-kilobase insert were radiolabeled and used as DNA probes in hybridization studies. Southern blot analysis with the gene probes against chromosomal DNA from Cmr strains of C. difficile obtained from five distinct geographical locations revealed that at least two copies of the same chloramphenicol acetyltransferase gene were present for each strain. Hybridization of the gene probes against Cmr strains of Staphylococcus epidermidis, Staphylococcus aureus, Klebsiella edwardsii, Escherichia coli, and to four other clostridial species revealed no homology even under conditions of low stringency.

Blotting, Southern↗
PubMed1985

Variations in the organization of repetitive DNA sequences in the genomes of Plasmodium falciparum clones.

Repetitive DNA in cultured Plasmodium falciparum was examined by restriction digestion and transfer hybridization, using cloned repetitive DNA probes. The arrangement of repetitive DNA was unstable: after 6 months culture of a cloned population, variations could be detected. Significant differences can be seen between clones derived from a single isolate, and are even more marked between isolates of diverse geographical origin. No cross-species conservation was seen for the sequences examined, and no relationship was observed between their representation in the P. falciparum genome and the potential for sexual differentiation.

Animals↗
PubMed1982

Hierarchically organized migration fields: the application of higher order factor analysis to population migration tables.

"The structure of human geographical systems is often of a hierarchical nature. Population migration systems can usefully be conceptualized as a series of hierarchically related levels of migration fields: the fields at one level nesting within the fields at the next higher level. Such migration fields and the relationships between different levels can be extracted from large population migration origin-destination matrices with the aid of higher order factor analysis." A case study of the western United States illustrating the application of higher order factor analysis to large interaction matrices is presented.

Americas↗
PubMed1980

A microstereotactic approach to small CNS lesions. Part II; Adjuvant therapy. Clinical potential and toxicity of intraventricular lymph infusion.

A technique is described for adjuvant therapy of small central nervous system tumors after their removal. The feasibility of direct application of lymphocytes from the thoracic duct to the ventricular system of cats has been explored. Reduction of the antigenic mass by techniques described in part I of this paper is probably crucial. Patients with gliomas are known to have circulating tumor-specific lymphocytes which may not have direct access to the CNS. This study demonstrated no toxicity from the chronic intraventricular infusion of thoracic duct lymph in cats.

Animals↗
PubMed1977

Suppressor cells and loss of B-cell potential in mice infected with Trypanosoma brucei.

The functional changes in splenic lymphoid populations from mice infected with T. brucei strain S42 were studied throughout the 3 weeks of infection. Within a week of infection, proliferation of B and T cells profoundly increased as shown by 3H-labelled thymidine incorporation and fluorescent staining of surface Ig; the spleen cells secreted high levels of both IgM and IgG immediately cells were put into culture; but with progressing infection this Ig production declined. The early effect on T cells was reflected by lack of responsiveness to PHA. B-cell potential was studied in low-density cultures treated with lipopolysaccharide (E. coli). Normal spleen cells proliferate extensively in these cultures with subsequent secretion of IgG as well as IgM. The ability to proliferate and produce Ig in response to LPS was severely depressed by day 7 and almost totally absent by day 12 of infection. Removal of T cells from the spleen cells obtained early in infection partly restored the response to LPS but as the infection neared its fatal end, B-cell potential appeared to become exhausted. Macrophages obtained from infected mice even early in infection profoundly depressed the ability of normal spleen cells to proliferate and secrete immunoglobulin in LPS cultures. The general immunodepressing effect of trypanosomes can be attributed to clonal exhaustion of B-cell potential caused by an undefined blastogenic stimulus from the parasites which may operate at least in part by the generation of suppressive T cells and macrophages.

Animals↗