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Biomedical subjects

J Charlesworth

Publications and source records attributed to J Charlesworth.

16 recordsLinked to original sources
PubMed2001

CL22 - a novel cationic peptide for efficient transfection of mammalian cells.

Condensing peptide-DNA complexes have great potential as nonviral agents for gene delivery. To date, however, such complexes have given transfection activities greatly inferior to adenovirus and somewhat inferior to cationic lipid-DNA complexes, even for cell lines and primary cells in vitro. We report here the identification of a novel condensing peptide, CL22, which forms DNA complexes that efficiently transfect many cell lines, as well as primary dendritic and endothelial cells. We report studies with sequence and structure variants that define some properties of the peptide that contribute to efficient transfection. We demonstrate that the superior transfection activity of CL22 compared with other DNA condensing peptides is conferred at a step after uptake of the complexes into cells. We show that CL22-DNA complexes have transfection activity that is at least equivalent to the best available nonviral agents.

Amino Acid Sequence↗
PubMed2001

Negotiating and managing partnership in primary care.

In the UK public service organisations are increasingly working together in new partnerships, networks and alliances, largely stimulated by government legislation, which aims to encourage 'joined-up' policy-making. This is particularly prevalent in health-care where local government, health authorities and trusts, voluntary and community groups are extending existing, and developing new, forms of partnership, particularly around Health Improvement Programmes and new primary care organisations. This paper explores two main aspects of how these new interorganizational relationships are being developed and managed and is based on research conducted in one case study locality. First, the new structures of partnership in primary care are mapped out, together with discussion on why these particular patterns of relationship between statutory and voluntary sector organisations have emerged, exploring both centrally and locally determined influences. Secondly, the paper explores the tensions associated with working within new policy-making and management structures, and how the additional demands of audit, performance measurement and the sheer pace of change, pose a potential threat to the partnership process.

England↗
PubMed1999

Tenacious adhesion of Actinobacillus actinomycetemcomitans strain CU1000 to salivary-coated hydroxyapatite.

Adherence of Actinobacillus actinomycetemcomitans to hard-tissue surfaces was evaluated by comparing a phenotypically stable, well-maintained clinical isolate (strain CU1000) to Streptococcus gordonii G9B, an extensively studied oral-colonizing bacterium. Standard innocula of radiolabelled bacteria were added to saliva-coated hydroxyapatite (SHA) and the ratio of bound to unbound cells counted. Several other clinical isolates as well as laboratory strain Y4 were studied. In other experiments, cell detachment from SHA was compared in static and shaking vessels to calculate controlled desorption of cells over time. A sonic-displacement assay was used to measure avidity of binding to HA and SHA. To better define the attachment properties of CU1000, bacteria were treated with a variety of agents including detergents, salts and enzymes before or after incubation with SHA. Results indicated that CU1000 bound better than G9B (a minimum of 10-fold greater; p < or = 0.05) and did not desorb from SHA, while G9B desorbed to equilibrium in 4 h. Furthermore, Langmuir isotherm calculations indicated that, unlike G9B, CU1000 did not follow second-order adsorption kinetics and thus did not achieve saturation. In addition, of the agents tested only periodate reduced attachment and resulted in detachment of CU1000 from surfaces. These experiments suggest that clinical isolates of A. actinomycetemcomitans possess unique binding properties that promote adsorption to and impede desorption from SHA. The characteristics described for the actinobacillus in this study have been previously underestimated, appear to be mediated by glycoconjugates, and may resemble attachment described for several biofilm-forming, non-oral pathogens.

Adsorption↗
PubMed1996

Treatment with growth hormone and dexamethasone in mice transgenic for human islet amyloid polypeptide causes islet amyloidosis and beta-cell dysfunction.

Islet amyloid derived from islet amyloid polypeptide (IAPP) is a well-recognized feature of type II diabetes. However, the mechanism of islet amyloidogenesis is unknown. In vitro studies suggest that amino acid residues 20-29 in human, but not mouse, IAPP confer amyloidogenicity consistent with the absence of spontaneous islet amyloidosis in mice. Several clinical and in vitro studies suggest that increased synthetic rates of IAPP predispose to IAPP-amyloidosis. In the present study, we sought to test the hypothesis that pharmacological induction of insulin resistance in a mouse transgenic (TG) for human IAPP would induce islet amyloid and beta-cell dysfunction. TG and non-transgenic (N-TG) control mice were treated with both rat growth hormone (12 micrograms/day) and dexamethasone (0.24 mg/day) (dex/GH) or received no treatment for 4 weeks, after which animals were killed to examine islet morphology. Treatment with dex/GH caused hyperglycemia (7.3 +/- 0.4 vs. 5.2 +/- 0.1 mmol/l, TG vs. N-TG, P < 0.001) associated with a decreased plasma insulin concentration (595 +/- 51 vs. 996 +/- 100 pmol/l, TG vs. N-TG, P < 0.05) in TG versus control mice. Islet amyloid was induced in treated TG mice but not in control mice. Islet amyloid was identified in both intra- and extracellular deposits, the former being associated with evidence of beta-cell degeneration. We conclude that dex/GH treatment in mice TG for human IAPP induces IAPP-derived islet amyloid, hyperglycemia, and islet dysfunction. The present model recapitulates the islet morphology and phenotype of type II diabetes.

Amyloid↗
PubMed1995

Islet amyloid polypeptide in pancreatic tissue of children with persistent hyperinsulinemic hypoglycemia caused by primary islet hyperplasia and nesidioblastosis.

Islet amyloid is a recognized characteristic finding in insulinoma and secondary islet hyperplasia resulting from severe insulin resistance. Little information is available about the presence of islet amyloid in primary islet hyperplasia (nesidioblastosis) of childhood. Here we report that islet amyloid was not present in 12 children with primary islet hyperplasia associated with hyperinsulinemic hypoglycemia.

Amyloid↗
PubMed1988

Association of complement allotype C4B2 with anterior uveitis.

We have studied allotypes of the fourth component of complement (C4) in 44 patients with inflammatory eye disease in order to define genetic susceptibility factors further. Twenty-six patients had uveitis (18 had anterior uveitis) and 18 patients had retinal vasculitis. There was an increased incidence of the C4B2 allotype in patients with anterior uveitis (pc less than 0.002), especially in HLA B27 positive males. In contrast, there was no increased incidence of specific allotypes in patients with posterior uveitis or retinal vasculitis. This genetic association may form part of a disease susceptibility supratype in patients with anterior uveitis.

Alleles↗
PubMed1984

Significance of sequential changes in serum complement levels during acute anaphylactoid reactions.

Reduced levels of complement fractions C3 and C4 and total hemolytic complement (CH50) are usually attributed to classical complement pathway activation. However, studies in 26 patients undergoing severe anaphylactoid reactions during general anesthesia suggest that these changes may equally reflect plasma dilution and protein redistribution. Twelve patients showed a dramatic fall in complement complexes which tended to resolve after 24 h; however, this fall was not usually associated with the detection of C3 breakdown products or antigen-antibody complexes. Measurement of complement levels is not a reliable index of activation or cleavage when there are dynamic shifts in plasma volume.

Acute Disease↗
PubMed1982

Comparisons between carcinogenic potency and mutagenic potency to Salmonella in a series of derivatives of 4-dimethylaminoazobenzene (DAB).

8 derivatives of the rodent liver carcinogen 4-dimethylaminoazobenzene (DAB), all of known carcinogenicity in rodents, have been evaluated in the 3 major variants of the Salmonella mutation assay; the standard plate test of Ames et al., the pre-incubation assay of Yahagi et al. and the fluctuation assay of Gatehouse. Although 4 of these chemicals were reported to be non-carcinogenic, and 4 to be of greater carcinogenic potency than DAB, each was mutagenic in a least 2 of the assays. Further, no quantitative correlation between carcinogenic and mutagenic potency was evident in any of the assay employed. The parent carcinogen DAB, 5-dimethylaminophenylazoindazole (a non-carcinogenic bacterial mutagen) and 6-dimethylaminophenylazobenzthiazole (a carcinogenic bacterial mutagen) were administered to rats via intraperitoneal injection, followed, 26 h later, by a sub-acute dose of [14C] dimethylnitrosamine. The histopathological condition of the livers of the treated animals was assessed together with a determination of the extent and nature of methylation by DMN of the DNA in the livers according to the method of O'Connor. Disturbances in both the pathological and DNA-related parameters were observed for the 2 carcinogens while control levels were seen for the non-carcinogen. Within this context the value of short-term assays conducted in vivo is discussed, especially their potential to identify potent mammalian carcinogens from among a collection of structurally related bacterial mutagens.

Animals↗
PubMed1981

Role of estrogen and androgen in maintaining the preovulatory follicle.

The effects of nitromifene citrate (CI 628), an antiestrogen, and Flutamide, an antiandrogen, on the ultrastructure and viability of the preovulatory follicle and granulosa cells were examined both in vivo and in vitro. In vivo administration of either antihormone induced degeneration within the granulosa cells. In some of the affected granulosa cells, the nuclear material was condensed while the cytoplasm and associated organelles were unaltered. In others, the density of the cytoplasm was reduced, the smooth endoplasmic reticulum was dilated but the nucleus remained unaltered. In vitro, either antihormone reduced granulosa-cell viability but the granulosa cells were twenty times more sensitive to CI 628 than to Flutamide. In addition, exposure to CI 628 induced nuclear condensation without affecting the cytoplasm, while Flutamide induced the deterioration of the cytoplasm without altering the nucleus. These observations suggest that: (1) both estrogen and androgens control the viability of the granulosa cells and thereby the follicle, (2) the action of estrogen and androgen is mediated through receptors within the granulosa cells since these antihormones prevent the nuclear uptake of their respective hormone, (3) the granulosa cells of preovulatory follicles appears to be more dependent on estrogen than on androgen, and (4) each steroid appears to have a specific role in maintaining the granulosa cell; estrogens control the integrity of the nucleus while androgens preserve the cytoplasmic organization of the granulosa cell.

Androgens↗
PubMed1981

Clinical significance of immune complexes in rheumatoid disease.

Circulating immune complexes were measured by the Clq binding assay in 49 cases of rheumatoid disease. Raised levels showed a positive correlation with activity of the arthritis, the number of involved joints and the erythrocyte sedimentation rate. No correlation was found with age, sex, duration of disease, rheumatoid nodules, presented of radiographic joint erosions or other haematological and serological parameters. In 12 patients the arthritis subsequently remitted and this remission in disease activity correlated with reduced levels of immune complexes.

Antigen-Antibody Complex↗
PubMedDate not supplied

HLA-DR and -DQ genotyping in anti-GBM disease.

Anti-GBM disease has been associated with the HLA genes of the major histocompatibility complex (MHC) in previous serological studies, with an increased incidence of HLA-DR2 in patients. In this study, 36 patients with anti-GBM disease were genotyped by restriction fragment length polymorphism (RFLP) analysis using cDNA probes for DRB, DQA, and DQB. The frequency of HLA-DRw15(Dw2), a split of DR2, was significantly increased in the patients compared with the controls (63.9 per cent versus 23.3 per cent, chi 2 = 22.4, p(corr) less than 0.0001), and all but one of the patients were positive for either DRw15(Dw2) or DR4 (p less than 0.0001). The frequencies of the remaining DR antigens were not decreased randomly, with a significant decrease in DR7 in the patient group (chi 2 = 8.6, p(corr) less than 0.05). The closely linked gene HLA-DQw6 was found to be significantly increased in frequency in the patients compared with the controls (p(corr) less than 0.0001). No correlations could be made between the genetic data and clinical features of the disease.

Adolescent↗