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Biomedical subjects

C Davenport

Publications and source records attributed to C Davenport.

At least 19 recordsLinked to original sources
PubMed2006

Variants in Apaf-1 segregating with major depression promote apoptosome function.

APAF1, encoding the protein apoptosis protease activating factor 1 (Apaf-1), has recently been established as a chromosome 12 gene conferring predisposition to major depression in humans. The molecular phenotypes of Apaf-1 variants were determined by in vitro reconstruction of the apoptosome complex in which Apaf-1 activates caspase 9 and thus initiates a cascade of proteolytic events leading to apoptotic destruction of the cell. Cellular phenotypes were measured using a yeast heterologous expression assay in which human Apaf-1 and other proteins necessary to constitute a functional apoptotic pathway were overexpressed. Apaf-1 variants encoded by APAF1 alleles that segregate with major depression in families linked to chromosome 12 shared a common gain-of-function phenotype in both assay systems. In contrast, other Apaf-1 variants showed neutral or loss-of-function phenotypes. The depression-associated alleles thus have a common phenotype that is distinct from that of non-associated variants. This result suggests an etiologic role for enhanced apoptosis in major depression.

Alleles↗
PubMed2005

The effectiveness and cost-effectiveness of parent training/education programmes for the treatment of conduct disorder, including oppositional defiant disorder, in children.

OBJECTIVES: To assess the clinical and cost-effectiveness of parent training programmes for the treatment of children with conduct disorder (CD) up to the age of 18 years. DATA SOURCES: Electronic databases. REVIEW METHODS: For the effectiveness review, relevant studies were identified and evaluated. A quantitative synthesis of behavioural outcomes across trials was also undertaken using two approaches: vote counting and meta-analysis. The economic analysis consisted of reviewing previous economic/cost evaluations of parent training/education programmes and the economic information within sponsor's submissions; carrying out a detailed exploration of costs of parent training/education programmes; and a de novo modelling assessment of the cost-effectiveness of parent training/education programmes. The potential budget impact to the health service of implementing such programmes was also considered. RESULTS: Many of the 37 randomised controlled trials that met the review inclusion and exclusion criteria were assessed as being of poor methodological quality. Studies were clinically heterogeneous in terms of the population, type of parent training/education programme and content, setting, delivery, length and child behaviour outcomes used. Both vote counting and meta-analysis revealed a consistent trend across all studies towards short-term effectiveness (up to 4 months) of parent training/education programmes (compared with control) as measured by a change in child behaviour. Pooled estimates showed a statistically significant improvement on the Eyberg Child Behaviour Inventory frequency and intensity scales, the Dyadic Parent-Child Interaction Coding System and the Child Behaviour Checklist. No studies reported a statistically significant result favouring control over parent training/education programmes. There were few statistically significant differences between different parent training/education programmes, although there was a trend towards more intensive interventions (e.g. longer contact hours, additional child involvement) being more effective. The cost of treating CD is high, with costs incurred by many agencies. A recent study suggested that by age 28, costs for individuals with CD were around 10 times higher than for those with no problems, with a mean cost of 70,019 pounds sterling. Criminality incurs the greatest cost, followed by educational provision, foster and residential care and state benefits. Only a small proportion of these costs fall on health services. Using a 'bottom-up' costing approach, the costs per family of providing parent training/education programmes range from 629 pounds sterling to 3839 pounds sterling depending on the type and style of delivery. Using the conservative assumption that there are no cost savings from treatment, a total lifetime quality of life gain of 0.1 would give a cost per quality-adjusted life-year of between 38,393 pounds sterling and 6288 pounds sterling depending on the type of programme delivery and setting. CONCLUSIONS: Parent training/education programmes appear to be an effective and potentially cost-effective therapy for children with CD. However, the relative effectiveness and cost-effectiveness of different models (such as therapy intensity and setting) require further investigation. Further research is required on the impact of parent training/education programmes on the quality of life of children with CD and their parents/carers, as well as on longer term child outcomes.

Adolescent↗
PubMed2004

Identification and assessment of ongoing trials in health technology assessment reviews.

OBJECTIVES: To assess the importance of ongoing trials in health technology assessment reviews (HTARs) for the National Institute for Clinical Excellence and to provide practical recommendations for identifying ongoing trials and assessing their possible impact. DATA SOURCES: Electronic databases. REVIEW METHODS: Ongoing trials (or trials in progress) were defined as any trials that have started but where the results are not yet available or only interim results are available for HTARs. This methodological review included: (1) an assessment of ongoing trials in HTARs completed by the end of August 2002, (2) a survey and assessment of trial registers and other sources of ongoing trials and (3) a summary and assessment of available methods for assessing the possible impacts of ongoing trials. RESULTS: The identification of ongoing trials is a common phenomenon in reviews of health technology assessment. Twenty-three of the 32 HTARs identified one or more ongoing trials and in eight of these the information on identified ongoing trials was not considered in the evidence synthesis and research recommendations. All but one HTAR that considered the potential impact of ongoing trials adopted a narrative approach. Trial registers and grey literature are important sources of information on ongoing trials. All 32 HTARs explicitly or implicitly searched for unpublished studies, and/or ongoing trials and/or grey literature and trial registers. The assessment of six commonly used trial registers suggested that most registers provided sufficient information for reviewers to decide the relevance of identified ongoing trials. However, it is sometimes extremely difficult to know whether ongoing trials identified from different sources (registers) are the same trials or belong to the same multicentre trials. The ISRCTN (the International Standard Randomised Controlled Trial Number) is the most reliable system but it has not been widely adopted. The qualitative assessment of ongoing trials compared major features of completed and ongoing trials, providing information about the possible impact of ongoing trials in terms of relevance, validity, reliability and generalisability. Quantitative methods to assess the impact of ongoing trials include cumulative meta-analysis related methods, fail-safe N, Bayesian data monitoring, and Bayesian interim predictions. The most useful method may be the Bayesian predictive probability, which estimates predictive probabilities for any possible values of treatment effect. A case study indicated that the appropriate use of quantitative methods would strengthen findings from narrative assessment of possible impact of ongoing trials. CONCLUSIONS: Identification of ongoing trials is common in HTARs. Searching for ongoing trials in effectiveness reviews should be more thorough and explicit. Conversely, primary researchers, in particular those working with in multicentre trials, should label ongoing trials more clearly, preferably by ISRCTN. Qualitative assessment of identified ongoing trials is crucial and informative. Available quantitative methods could be used to strengthen findings from narrative assessment, although further research and more empirical examples are required. Information from ongoing trials may contribute to syntheses of results, conclusions and recommendations for future research. Future research is suggested into the identification and assessment of ongoing trials in other systematic reviews of effectiveness of health care interventions; existing and new methods for incorporating information on ongoing trials; comparing estimated impacts with the actual results of ongoing trials; and to incorporate findings from the assessment of ongoing trials into decision models.

Bayes Theorem↗
PubMed2002

Distinct antigenic features of linear epitopes at the N-terminus and C-terminus of 65 kDa glutamic acid decarboxylase (GAD65): implications for autoantigen modification during pathogenesis.

Autoantibodies to 65 kDa glutamic acid decarboxylase (GAD65) are produced in many patients with autoimmune polyendocrine syndrome type II (APS-II) or stiff-man syndrome (SMS) and are heterogeneous in their epitope specificities, recognizing both conformational and linear determinants. Major linear epitopes of GAD, which are recognized by autoantibodies in a minority of these patients, occur in the N-terminal and C-terminal regions. We have investigated antibody recognition of the N- and C-termini of GAD65 in relation to their structural features as an approach to understanding what modifications to the native GAD structure may occur that facilitate the generation of antibodies specific to linear epitopes in these regions during the autoimmune pathogenesis. A monoclonal antibody specific to the N-terminus of GAD65 bound both native and denatured GAD in ELISA, whereas monoclonal and polyclonal antibodies specific to the C-terminus of GAD bound only denatured GAD. These antibodies were epitope mapped using random peptide phage-display libraries and the epitopes related to a previously proposed structural model of GAD65. This has led us to propose that the alpha-helical secondary structure of the C-terminus of GAD65 must be denatured to generate linear epitopes. In contrast, the N-terminus is both surface exposed and linear in the native structure, but may be masked by membrane interactions, which must be broken to facilitate recognition by B cells.

Amino Acid Sequence↗
PubMed2000

Randomized trial of sertraline in patients with unexplained chest pain of noncardiac origin.

BACKGROUND: Between 10% and 30% of patients with symptoms similar to angina and sufficient to justify cardiac catheterization are found to have normal coronary angiograms. Treatment of patients with chest pain with no apparent cardiac cause is a major clinical problem. Our hypothesis was that sertraline would reduce the severity of pain in patients with chest pain of noncardiac origin. METHODS AND RESULTS: This was a single-site, double-blind, placebo-controlled study of the efficacy, tolerability, and safety of sertraline in the treatment of noncardiac chest pain in outpatients. Thirty patients were enrolled in the study. After 1 week of single-blind placebo washout, patients were randomly assigned in a double-blind fashion either to drug or placebo. The Beck Depression Inventory was administered at baseline and at completion of study. Daily pain diaries (visual analogue scale, rating pain on a scale of 1 to 10) were selfadministered and evaluated at baseline and at follow-up visits. Statistical measures were performed with an intention-to-treat approach. Patients who received sertraline over the course of the study showed a statistically significant reduction in pain compared with those who were receiving placebo. CONCLUSIONS: The use of sertraline in patients with noncardiac chest pain produced clinically significant reduction of daily pain. These results suggest the need for further studies of the efficacy and tolerability of sertraline and other selective serotonin reuptake inhibitors in the long-term management of noncardiac chest pain.

Adolescent↗
PubMed1999

Xenotransplantation: application of disease resistance.

1. Organ transplantation is now clinically routine for patients with end-stage organ failure. One major limitation in transplantation is chronic rejection involving the loss of the graft despite the use of immunosuppressive agents. Haematopoietic stem cell (HSC) chimerism, achieved through bone marrow transplantation (BMT), induces donor-specific tolerance to transplanted organs and prevents chronic rejection. 2. A second major limitation to organ transplantation is the donor shortage. Xenotransplantation, the transplantation of organs between different species, would have the ability to increase the availability of donor organs. 3. Current immunosuppressive therapies do not prevent the rejection of xenografts. Therefore, the only reliable method for achieving donor-specific tolerance to xenografts may require HSC chimerism. 4. In order to justify the use of BMT to induce transplantation tolerance in patients with non-life-threatening diseases, the morbidity and mortality associated with current conditioning regimens must be addressed. 5. The use of partial conditioning regimens to promote engraftment of xenogeneic HSC and the development of donor-specific tolerance may eventually make xenotransplantation in humans a clinical reality. 6. Additional advantages of xenotransplantation are the ability to genetically engineer the donor xenograft and resistance of some xenografts to infection by human viruses because of the species specificity of most viruses. 7. The clinical application of disease resistance for HIV and hepatitis B virus is the focus of the present review.

Animals↗
PubMed1999

The effect of major depression on functional status in patients with coronary artery disease.

OBJECTIVE: To examine the effect of major depression on reported functional status in a group of patients with coronary artery disease (CAD). SETTING: An inpatient cardiology service. PARTICIPANTS: Three hundred thirty-five inpatients with coronary artery disease who were free of dementia, Parkinson's disease, and other primary neurological illnesses. MEASUREMENTS: Duke Depression Evaluation Schedule, a structured psychiatric interview which included the Diagnostic Interview Schedule depression subscale, the Cumulative Illness Rating Scale, and two scales for measuring instrumental and self-maintenance activities of daily living. RESULTS: Twenty-seven subjects met DSM-IV criteria for major depression. Compared with subjects without major depression, depressed subjects were more than twice as likely to report a self-maintenance ADL deficit and were significantly more likely to report an IADL deficit than were nondepressed subjects (93 vs 71%). In regression models, female gender, older age, greater medical illness severity, and presence of major depression were significant predictors of self-maintenance ADL disability; and female gender, older age, greater medical severity, and presence of major depression significantly predicted greater IADL impairment. CONCLUSION: The presence of major depression was associated with functional disability in patients with CAD. Further research is needed to clarify whether antidepressant treatment significantly impacts both affective symptoms and functional status in patients with coronary heart disease.

Activities of Daily Living↗
PubMed1998

Heterogeneity in the occurrence of a subset of autoantibodies to glutamic acid decarboxylase in autoimmune polyendocrine patients with islet cell antibodies.

Glutamic acid decarboxylase-65 (GAD-65) is a major target for autoantibodies and autoreactive T cells in patients with insulin-dependent diabetes mellitus (IDDM). Autoantibodies to GAD are also found in patients with stiff man syndrome (SMS) or polyendocrine autoimmunity (PE). The epitope specificities of autoantibodies to GAD in IDDM and SMS have been well documented, but the locations of autoantibody epitopes of GAD in PE patients have not been mapped. Thus, the properties of anti-GAD antibodies in PE patients (with or without diabetes) were investigated. The ability of PE serum antibodies to inhibit the binding of the mouse monoclonal antibody, GAD-6, to native GAD in ELISA was determined. For PE patients without diabetes, levels of inhibition of GAD-6 binding ranged from 0% to almost 70% and were unrelated to the level of binding of serum antibodies to GAD (P = 0.351) or to the functional affinities of these antibodies. This suggests differences in the epitope specificities of anti-GAD antibodies in different patients. Levels of inhibition were also unrelated to clinical condition. SMS antibodies showed similar levels of inhibition of GAD-6 binding. Similar analysis was applied to PE patients with diabetes and levels of inhibition of GAD-6 binding to GAD were determined. These ranged from 0% to 80%, and levels of inhibition were similar in samples taken before or after diabetes onset. There was no significant difference between anti-GAD antibodies from PE patients with or without diabetes in the range of abilities to inhibit GAD-6 binding to GAD, although the highest levels of inhibition were given by sera from non-diabetic patients. This raises the possibility of differential expression of subsets of anti-GAD antibodies in progressive versus slow or non-progressive anti-islet autoimmune responses. Serum antibodies of PE and SMS patients did not inhibit the binding of antibodies specific for the extreme C-terminus of GAD, indicating that this is not the site of the epitopes for the patients' antibodies or for GAD-6.

Adolescent↗
PubMed1997

Allorecognition by murine natural killer cells: lysis of T-lymphoblasts and rejection of bone-marrow grafts.

Natural killer (NK) cells of inbred mice reject allogeneic bone-marrow cells, and NK cells of F1 hybrid mice can reject parental bone-marrow cells (hybrid resistance). In some cases these patterns of rejection can be mimicked in vitro by utilizing IL-2 cultured NK effector cells and allogeneic or parental T-lymphoblasts as target cells. Lysis of allogeneic and parental targets in vitro can be explained on the basis of the missing self hypothesis. Subsets of NK cells that bear non-overlapping MHC class I inhibitory receptors belonging to the Ly49 family lyse allogeneic targets because they do not express self class I molecules of the NK cell donor. Parental strain targets are lysed because they do not express all of the self class I antigens of the F1 hybrid, and hence fail to deliver inhibitory signals to all subsets of F1 NK cells. The expression of Ly49 receptors on NK cells is regulated by host MHC to ensure maximal sensitivity to alterations in self class I molecules and to prevent autoreactivity. In many instances, however, the rejection of allogeneic bone marrow cells in vivo cannot be readily explained by the missing self hypothesis. In these instances, it appears that rejection is initiated by class I MHC receptors on NK cells that recognize allogeneic class I molecules as non-self, and activate rather than inhibit NK cell function.

Animals↗
PubMed1997

Effects of insulin and insulin-like growth factors I and II on the growth of equine fetal and neonatal chondrocytes.

The effects of insulin and insulin-like growth factors (IGFs) I and II on fetal and foal chondrocytes were investigated in vitro. Chondrocytes from the lateral trochlear ridge of the distal femur were obtained from 2 fetuses (280 and 320 days gestation) and one 4-day-old foal and cultured. Membrane proteins consistent with type 1 and type 2 IGF receptors were demonstrated by radioligand cross linking and equilibrium binding analysis. It was demonstrated that both IGF-I and IGF-II acted as mitogens for isolated equine chondrocytes when present as the sole mitogenic factor in monolayer culture. It was further shown that whereas insulin was able to promote the survival and expansion of cell populations of chondrocytes in culture there was significantly reduced mitogenic stimulation compared to the IGFs. These results suggest that the role of insulin in growth cartilage may be to promote chondrocyte survival, or to suppress differentiation/apoptosis. This supports the hypothesis that relative hyperinsulinaemia may be a contributory factor to equine dyschondroplasia (osteochondrosis). Understanding of contributory, and possibly triggering factors such as this may allow the development of modified methods of husbandry which minimise the risk of disease in populations with a known predisposition.

Animals↗
PubMed1997

Antibodies to 125I-glutamic acid decarboxylase in patients with stiff man syndrome.

Antibodies to glutamic acid decarboxylase (GAD) are found in about 40% of patients with stiff man syndrome. A new assay involving immunoprecipitation of (125)I-glutamic acid decarboxylase was used to measure anti-GAD antibodies in 18 patients with stiff man syndrome. Of the eight serum samples from patients with stiff man syndrome, that had previously been found positive by immunoprecipitation of (35)S-GAD, seven were strongly positive with (125)I-GAD and one gave an equivocal result. Other serum samples from patients with stiff man syndrome and from controls were negative except one from a patient who had a thymoma, acquired neuromyotonia, and myasthenia gravis. Nine of 35 serum samples referred for testing were positive; in two of these the serum titre was 20-50 times higher than that in the CSF. This assay should prove useful in the diagnosis, management, and investigation of stiff man syndrome.

Antibodies↗