Evaluation of biases present in the cohort multiple randomised controlled trial design: a simulation study

Background The cohort multiple randomised controlled trial (cmRCT) design provides an opportunity to incorporate the benefits of randomisation within clinical practice; thus reducing costs, integrating electronic healthcare records, and improving external validity. This study aims to address a key concern of the cmRCT design: refusal to treatment is only present in the intervention arm, and this may lead to bias and reduce statistical power. Methods We used simulation studies to assess the effect of this refusal, both random and related to event risk, on bias of the effect estimator and statistical power. A series of simulations were undertaken that represent a cmRCT trial with time-to-event endpoint. Intention-to-treat (ITT), per protocol (PP), and instrumental variable (IV) analysis methods, two stage predictor substitution and two stage residual inclusion, were compared for various refusal scenarios. Results We found the IV methods provide a less biased estimator for the causal effect when refusal is present in the intervention arm, with the two stage residual inclusion method performing best with regards to minimum bias and sufficient power. We demonstrate that sample sizes should be adapted based on expected and actual refusal rates in order to be sufficiently powered for IV analysis. Conclusion We recommend running both an IV and ITT analyses in an individually randomised cmRCT as it is expected that the effect size of interest, or the effect we would observe in clinical practice, would lie somewhere between that estimated with ITT and IV analyses. The optimum (in terms of bias and power) instrumental variable method was the two stage residual inclusion method. We recommend using adaptive power calculations, updating them as refusal rates are collected in the trial recruitment phase in order to be sufficiently powered for IV analysis

Comparison of children's self-reports of depressive symptoms among different family interaction types in northern Taiwan

<p>Abstract</p> <p>Background</p> <p>Previous research has shown that family interactions are associated with depressive symptoms in children. However, detailed classifications of family interaction types have not been studied thoroughly. This study aims to understand the types of family interactions children experience and to identify the specific types of family interactions that are associated with a higher risk of depressive symptoms in children.</p> <p>Methods</p> <p>Data used in the study was collected as part of the Child and Adolescent Behavior in Long term Evolution (CABLE) project in 2003. CABLE is a longitudinal cohort study that commenced in 2001 and collects data annually from children in Taipei city and Hsinchu county in northern Taiwan. The data analyzed in this study was that obtained from the sixth graders (aged 11 to 12 years old) in 2003. Of the 2,449 sixth graders, 51.2% were boys and 48.8% were girls. Factor analysis and cluster analysis were used to investigate the types of family interactions. One way ANOVA was used to establish the relationship between family interaction types and children's self-reports of depressive symptoms.</p> <p>Results</p> <p>Based on the results of factor analysis, the latent factors for family interactions included supporting activities, psychological control, parental discipline, behavioral supervision, and family conflict. After conducting cluster analysis using factor scores, four types of family interactions were revealed: supervised (29.66%), disciplined (13.56%), nurtured (40.96%) and conflict (15.82%). Children from the disciplined or conflict families were more likely to report depressive symptoms. Children from the nurtured families were least likely to report depressive symptoms.</p> <p>Conclusion</p> <p>Family interactions can be classified into four different types, which are related to children's self-reports of depressive symptoms. The creation of a family interaction environment that is beneficial for children's mental health is an important issue for health education and health promotion professionals.</p

Syndecan-1 Enhances Proliferation, Migration and Metastasis of HT-1080 Cells in Cooperation with Syndecan-2

Syndecans are transmembrane heparan sulphate proteoglycans. Their role in the development of the malignant phenotype is ambiguous and depends upon the particular type of cancer. Nevertheless, syndecans are promising targets in cancer therapy, and it is important to elucidate the mechanisms controlling their various cellular effects. According to earlier studies, both syndecan-1 and syndecan-2 promote malignancy of HT-1080 human fibrosarcoma cells, by increasing the proliferation rate and the metastatic potential and migratory ability, respectively. To better understand their tumour promoter role in this cell line, syndecan expression levels were modulated in HT-1080 cells and the growth rate, chemotaxis and invasion capacity were studied. For in vivo testing, syndecan-1 overexpressing cells were also inoculated into mice. Overexpression of full length or truncated syndecan-1 lacking the entire ectodomain but containing the four juxtamembrane amino acids promoted proliferation and chemotaxis. These effects were accompanied by a marked increase in syndecan-2 protein expression. The pro-migratory and pro-proliferative effects of truncated syndecan-1 were not observable when syndecan-2 was silenced. Antisense silencing of syndecan-2, but not that of syndecan-1, inhibited cell migration. In vivo, both full length and truncated syndecan-1 increased tumour growth and metastatic rate. Based on our in vitro results, we conclude that the tumour promoter role of syndecan-1 observed in HT-1080 cells is independent of its ectodomain; however, in vivo the presence of the ectodomain further increases tumour proliferation. The enhanced migratory ability induced by syndecan-1 overexpression is mediated by syndecan-2. Overexpression of syndecan-1 also leads to activation of IGF1R and increased expression of Ets-1. These changes were not evident when syndecan-2 was overexpressed. These findings suggest the involvement of IGF1R and Ets-1 in the induction of syndecan-2 synthesis and stimulation of proliferation by syndecan-1. This is the first report demonstrating that syndecan-1 enhances malignancy of a mesenchymal tumour cell line, via induction of syndecan-2 expression

Mapping Peptidergic Cells in Drosophila: Where DIMM Fits In

The bHLH transcription factor DIMMED has been associated with the differentiation of peptidergic cells in Drosophila. However, whether all Drosophila peptidergic cells express DIMM, and the extent to which all DIMM cells are peptidergic, have not been determined. To address these issues, we have mapped DIMM expression in the central nervous system (CNS) and periphery in the late larval stage Drosophila. At 100 hr after egg-laying, DIMM immunosignals are largely congruent with a dimm-promoter reporter (c929-GAL4) and they present a stereotyped pattern of 306 CNS cells and 52 peripheral cells. We assigned positional values for all DIMM CNS cells with respect to reference gene expression patterns, or to patterns of secondary neuroblast lineages. We could assign provisional peptide identities to 68% of DIMM-expressing CNS cells (207/306) and to 73% of DIMM-expressing peripheral cells (38/52) using a panel of 24 markers for Drosophila neuropeptide genes. Furthermore, we found that DIMM co-expression was a prevalent feature within single neuropeptide marker expression patterns. Of the 24 CNS neuropeptide gene patterns we studied, six patterns are >90% DIMM-positive, while 16 of 22 patterns are >40% DIMM-positive. Thus most or all DIMM cells in Drosophila appear to be peptidergic, and many but not all peptidergic cells express DIMM. The co-incidence of DIMM-expression among peptidergic cells is best explained by a hypothesis that DIMM promotes a specific neurosecretory phenotype we term LEAP. LEAP denotes Large cells that display Episodic release of Amidated Peptides

T Cells Specifically Targeted to Amyloid Plaques Enhance Plaque Clearance in a Mouse Model of Alzheimer's Disease

Patients with Alzheimer's disease (AD) exhibit substantial accumulation of amyloid-β (Aβ) plaques in the brain. Here, we examine whether Aβ vaccination can facilitate the migration of T lymphocytes to specifically target Aβ plaques and consequently enhance their removal. Using a new mouse model of AD, we show that immunization with Aβ, but not with the encephalitogenic proteolipid protein (PLP), results in the accumulation of T cells at Aβ plaques in the brain. Although both Aβ-reactive and PLP-reactive T cells have a similar phenotype of Th1 cells secreting primarily IFN-γ, the encephalitogenic T cells penetrated the spinal cord and caused experimental autoimmune encephalomyelitis (EAE), whereas Aβ T cells accumulated primarily at Aβ plaques in the brain but not the spinal cord and induced almost complete clearance of Aβ. Furthermore, while a single vaccination with Aβ resulted in upregulation of the phagocytic markers triggering receptors expressed on myeloid cells-2 (TREM2) and signal regulatory protein-β1 (SIRPβ1) in the brain, it caused downregulation of the proinflammatory cytokines TNF-α and IL-6. We thus suggest that Aβ deposits in the hippocampus area prioritize the targeting of Aβ-reactive but not PLP-reactive T cells upon vaccination. The stimulation of Aβ-reactive T cells at sites of Aβ plaques resulted in IFN-γ-induced chemotaxis of leukocytes and therapeutic clearance of Aβ

Specific Syndecan-1 Domains Regulate Mesenchymal Tumor Cell Adhesion, Motility and Migration

Malignant mesothelioma is an asbestos induced cancer that is difficult to diagnose. Several studies have combined biomarkers to improve mesothelioma diagnosis, but with moderate success, and there is a need for new mesothelioma biomarkers. The tumour is often resistant to treatment and most patients will survive less than a year. An indicator of patient survival is the tumours growth pattern, which in turn is influenced by expressed proteoglycans. In this thesis work, we aim to improve the possibilities to diagnose malignant mesothelioma by combining biomarkers and by identifying new ones. We also investigate tumour driving mechanisms with focus on one of these suggested biomarkers, the cell-bound proteoglycan syndecan-1. We were able to construct a diagnostic two-step model based on biomarkers in patient material. By implementing a cut-off level and thereafter focusing on unresolved patients we combined hyaluronan and N-ERC/mesothelin (paper I), which significantly increased the diagnostic accuracy for malignant mesothelioma. To further improve diagnosis, we used mass spectrometry to find new biomarkers. We identified and validated galectin-1, which was excellent in discriminating mesotheliomas from adenocarcinomas (paper II). In the same study, we were also the first to describe aldo-keto reductase 1B10 as a novel prognostic mesothelioma biomarker. Syndecan-1 has been indicated as a marker for carcinomas. In paper I we describe how higher levels of syndecan-1 indicate the presence of a carcinoma over a mesothelioma. This was verified in paper II when syndecan-1 was identified as downregulated in fluids from mesothelioma patients compared to lung cancer patients. Paper III and paper IV focus on this proteoglycan. Malignant cell lines transfected with syndecan-1 and various truncated forms of syndecan-1 affected adhesion and migration, which are key features of cancer invasion (paper III). The results showed a domain- and cell type specific effect on the cells’ motility. Regulating syndecan-1 levels and analysing the global gene expression of mesothelioma cells made it evident that this proteoglycan has a strong influence on transforming growth factor β signalling and several growth factor pathways (paper IV). Links to cell migration and proliferation were furthermore identified, along with glycosaminoglycan modifying enzymes. These results can shed light on the complex role of syndecan-1 in invasion and growth of malignant mesenchymal cells. Taken together, this thesis work describes a complement to conventional mesothelioma diagnosis and identifies novel biomarkers. Furthermore, the potential biomarker syndecan-1 was shown to have an effect on cell motility and proliferation. These results increase our understanding of this aggressive malignancy

Cognitive and Socio-Emotional Deficits in Platelet-Derived Growth Factor Receptor-β Gene Knockout Mice

Platelet-derived growth factor (PDGF) is a potent mitogen. Extensive in vivo studies of PDGF and its receptor (PDGFR) genes have reported that PDGF plays an important role in embryogenesis and development of the central nervous system (CNS). Furthermore, PDGF and the β subunit of the PDGF receptor (PDGFR-β) have been reported to be associated with schizophrenia and autism. However, no study has reported on the effects of PDGF deletion on mice behavior. Here we generated novel mutant mice (PDGFR-β KO) in which PDGFR-β was conditionally deleted in CNS neurons using the Cre/loxP system. Mice without the Cre transgene but with floxed PDGFR-β were used as controls. Both groups of mice reached adulthood without any apparent anatomical defects. These mice were further examined by conducting several behavioral tests for spatial memory, social interaction, conditioning, prepulse inhibition, and forced swimming. The test results indicated that the PDGFR-β KO mice show deficits in all of these areas. Furthermore, an immunohistochemical study of the PDGFR-β KO mice brain indicated that the number of parvalbumin (calcium-binding protein)-positive (i.e., putatively γ-aminobutyric acid-ergic) neurons was low in the amygdala, hippocampus, and medial prefrontal cortex. Neurophysiological studies indicated that sensory-evoked gamma oscillation was low in the PDGFR-β KO mice, consistent with the observed reduction in the number of parvalbumin-positive neurons. These results suggest that PDGFR-β plays an important role in cognitive and socioemotional functions, and that deficits in this receptor may partly underlie the cognitive and socioemotional deficits observed in schizophrenic and autistic patients

Dystropathology increases energy expenditure and protein turnover in the mdx mouse model of Duchenne muscular dystrophy

The skeletal muscles in Duchenne muscular dystrophy and the mdx mouse model lack functional dystrophin and undergo repeated bouts of necrosis, regeneration, and growth. These processes have a high metabolic cost. However, the consequences for whole body energy and protein metabolism, and on the dietary requirements for these macronutrients at different stages of the disease, are not well-understood. This study used juvenile (4- to 5- wk-old) and adult (12- to 14-wk-old) male dystrophic C57BL/10ScSn-mdx/J and age-matched C57BL/10ScSn/J control male mice to measure total and resting energy expenditure, food intake, spontaneous activity, body composition, whole body protein turnover, and muscle protein synthesis rates. In juvenile mdx mice that have extensive muscle damage, energy expenditure, muscle protein synthesis, and whole body protein turnover rates were higher than in age-matched controls. Adaptations in food intake and decreased activity were insufficient to meet the increased energy and protein needs of juvenile mdx mice and resulted in stunted growth. In (non-growing) adult mdx mice with less severe dystropathology, energy expenditure, muscle protein synthesis, and whole body protein turnover rates were also higher than in age-matched controls. Food intake was sufficient to meet their protein and energy needs, but insufficient to result in fat deposition. These data show that dystropathology impacts the protein and energy needs of mdx mice and that tailored dietary interventions are necessary to redress this imbalance. If not met, the resultant imbalance blunts growth, and may limit the benefits of therapies designed to protect and repair dystrophic muscles

Mechanisms of T cell organotropism

F.M.M.-B. is supported by the British Heart Foundation, the Medical Research Council of the UK and the Gates Foundation

Influenza vaccination for immunocompromised patients: systematic review and meta-analysis from a public health policy perspective.

Immunocompromised patients are vulnerable to severe or complicated influenza infection. Vaccination is widely recommended for this group. This systematic review and meta-analysis assesses influenza vaccination for immunocompromised patients in terms of preventing influenza-like illness and laboratory confirmed influenza, serological response and adverse events