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2.
EClinicalMedicine ; 64: 102135, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37936655

RESUMO

Background: Antipsychotics are a core treatment for psychosis, but the evidence for gradual dose reductions guided by clinicians is under-developed. The RADAR randomised controlled trial (RCT) compared antipsychotic reduction and possible discontinuation with maintenance treatment for people with recurrent psychotic disorders. The current study explored participants' experiences of antipsychotic reduction or discontinuation within this trial. Methods: This qualitative study was embedded within the RADAR RCT (April 2017-March 2022) that recruited 253 participants from specialist community mental health services in 19 public healthcare localities in England. Participants were adults with recurrent non affective psychosis who were taking antipsychotic medication. Semi-structured interviews, lasting 30-90 min, were conducted after the trial final 24-month follow-up with 26 people who reduced and/or discontinued antipsychotics within the trial, sampled purposively for diversity in sociodemographic characteristics, trial variables, and pre-trial medication and clinical factors. Data were analysed using thematic analysis and findings are reported qualitatively. Findings: Most participants reported reduced adverse effects of antipsychotics with dose reductions, primarily in mental clouding, emotional blunting and sedation, and some positive impacts on social functioning and sense of self. Over half experienced deteriorations in mental health, including psychotic symptoms and intolerable levels of emotional intensity. Nine had a psychotic relapse. The trial context in which medication reduction was explicitly part of clinical care provided various learning opportunities. Some participants were highly engaged with reduction processes, and despite difficulties including relapses, developed novel perspectives on medication, dose optimisation, and how to manage their mental health. Others were more ambivalent about reduction or experienced less overall impact. Interpretation: Experiences of antipsychotic reductions over two years were dynamic and diverse, shaped by variations in dose reduction profiles, reduction effects, personal motivation and engagement levels, and relationships with prescribers. There are relapse risks and challenges, but some people experience medication reduction done with clinical guidance as empowering. Clinicians can use findings to inform and work flexibly with service users to establish optimal antipsychotic doses. Funding: National Institute for Health Research.

3.
Lancet Psychiatry ; 10(11): 848-859, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37778356

RESUMO

BACKGROUND: Maintenance antipsychotic medication is recommended for people with schizophrenia or recurrent psychosis, but the adverse effects are burdensome, and evidence on long-term outcomes is sparse. We aimed to assess the benefits and harms of a gradual process of antipsychotic reduction compared with maintenance treatment. Our hypothesis was that antipsychotic reduction would improve social functioning with a short-term increase in relapse. METHODS: RADAR was an open, parallel-group, randomised trial done in 19 National Health Service Trusts in England. Participants were aged 18 years and older, had a diagnosis of recurrent, non-affective psychotic disorder, and were prescribed an antipsychotic. Exclusion criteria included people who had a mental health crisis or hospital admission in the past month, were considered to pose a serious risk to themselves or others by a treating clinician, or were mandated to take antipsychotic medication under the Mental Health Act. Through an independent, internet-based system, participants were randomly assigned (1:1) to gradual, flexible antipsychotic reduction, overseen by treating clinicians, or to maintenance. Participants and clinicians were aware of treatment allocations, but assessors were masked to them. Follow-up was for 2 years. Social functioning, assessed by the Social Functioning Scale, was the primary outcome. The principal secondary outcome was severe relapse, defined as requiring admission to hospital. Analysis was done blind to group identity using intention-to-treat data. The trial is completed and has been registered with ISRCTN registry (ISRCTN90298520) and with ClinicalTrials.gov (NCT03559426). FINDINGS: 4157 people were screened, of whom 253 were randomly allocated, including 168 (66%) men, 82 (32%) women, and 3 (1%) transgender people, with a mean age of 46 years (SD 12, range 22-79). 171 (67%) participants were White, 52 (21%) were Black, 16 (6%) were Asian, and 12 (5%) were of other ethnicity. The median dose reduction at any point during the trial was 67% in the reduction group and zero in the maintenance group; at 24 months it was 33% versus zero. At the 24-month follow-up, we assessed 90 of 126 people assigned to the antipsychotic dose reduction group and 94 of 127 assigned to the maintenance group, finding no difference in the Social Functioning Scale (ß 0·19, 95% CI -1·94 to 2·33; p=0·86). There were 93 serious adverse events in the reduction group affecting 49 individuals, mainly comprising admission for a mental health relapse, and 64 in the maintenance group, relating to 29 individuals. INTERPRETATION: At 2-year follow-up, a gradual, supported process of antipsychotic dose reduction had no effect on social functioning. Our data can help to inform decisions about the use of long-term antipsychotic medication. FUNDING: National Institute for Health Research.


Assuntos
Antipsicóticos , Transtornos Psicóticos , Esquizofrenia , Masculino , Feminino , Humanos , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Esquizofrenia/tratamento farmacológico , Antipsicóticos/uso terapêutico , Redução da Medicação , Medicina Estatal , Resultado do Tratamento , Transtornos Psicóticos/tratamento farmacológico , Inglaterra , Recidiva
4.
Radiat Prot Dosimetry ; 199(17): 2104-2111, 2023 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-37551012

RESUMO

This study aims to investigate if contact shielding reduces breast radiation dose during computed tomography (CT) abdomen-pelvis examinations using automatic tube current modulation to protect one of the four most radiosensitive organs during CT examinations. Dose measurements were taken with and without contact shielding across the anterior and lateral aspects of the breasts and with and without organ dose modulation (ODM) to quantify achievable dose reductions. Although there are no statistically significant findings, when comparing with and without shielding, the mean breast surface dose was reduced by 0.01 µSv without ODM (1.92-1.91 µSv, p = 0.49) and increased by 0.03 µSv with ODM (1.53-1.56 µSv, p = 0.44). Comparing with and without ODM, the mean breast surface dose was reduced by 0.35 µSv with shielding (1.91-1.56 µSv, p = 0.24) and by 0.39 µSv without shielding (1.92-1.53 µSv, p = 0.17). The addition of contact shielding does not provide significant breast surface radiation dose reduction during CT abdomen-pelvis.

5.
BMC Med Res Methodol ; 23(1): 78, 2023 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-36991350

RESUMO

OBJECTIVES: Pre-trial acceptability studies may boost recruitment, especially in trials comparing distinctly different interventions. We evaluated the impact of an acceptability study on recruitment to a randomised trial of antipsychotic reduction versus maintenance treatment and explored demographic and clinical predictors of subsequent enrolment. METHODS: Participants with a diagnosis of a schizophrenia spectrum disorder who were taking antipsychotic medication were interviewed about their views of taking part in a future trial. RESULTS: In a sample of 210 participants, 151 (71.9%) expressed an interest in taking part in the future trial, 16 (7.6%) said they might be interested, and 43 (20.5%) said they were not. Altruistic reasons were most commonly given for wanting to take part, and concern about randomisation for not wanting to. Ultimately 57 people enrolled in the trial (27.1% of the original sample). Eighty-five people who initially expressed an interest did not enrol due to declining or not being eligible (for clinical reasons). Women and people from a white ethnic background were more likely to enrol in the trial, but no illness or treatment-related characteristics were associated with enrolment. CONCLUSION: An acceptability study can be a useful tool for recruitment to challenging trials, but it may over-estimate recruitment.


Assuntos
Antipsicóticos , Esquizofrenia , Humanos , Feminino , Antipsicóticos/uso terapêutico , Esquizofrenia/tratamento farmacológico
6.
Avian Dis ; 66(2): 186-192, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35838751

RESUMO

Because of the trend of cage-free egg production, infections with the nematode Ascaridia galli are receiving increased attention. The aim of this study was to establish a timeline for the influence of A. galli on the expression of key cytokines related to a parasitic immune response, and on the composition of the jejunal microbiota. Twenty-eight male layer-type birds were challenged at 24, 25, and 26 days of age. An additional 28 birds were kept as uninfected controls. Starting on Day 31, three birds of each group were euthanized every week until 8 wk postinfection (PI). The number of larvae isolated from the intestinal wall decreased over time, until no larvae were seen at 7 and 8 wk PI. At 5 wk PI, there was a numerical upregulation of all cytokines (TGF-ß, IFN-γ, IL-4, IL-8, IL-10, IL-13) in the infected group, but this change was only statistically significant for IL-13. At this time point, larvae were expected to have developed into adults that would have shed eggs in the feces. However, no adult worms were seen and there was no egg shedding. For the microbiota analysis, there were significant differences in the alpha diversity (Faith's phylogenetic diversity) between challenge and control groups, and the beta diversity analysis showed slight differences between samples, suggesting that the age of the birds was the main reason for the separation of groups. These findings suggest that the upregulation of all cytokines evaluated in Week 5 might be the reason for resolution of the infection. Possible explanations are that a high infection dose and the fact that birds were fed with a more nutritionally dense feed might have contributed to the birds' immune system clearing the infection before the worms were able to reach maturity.


La infección por Ascaridia galli no altera significativamente la microbiota intestinal y se elimina tras cambios en la expresión de citocinas. Debido a la tendencia de la producción de huevos libres de jaulas, las infecciones con el nematodo Ascaridia galli están recibiendo una mayor atención. El objetivo de este estudio fue establecer una línea de tiempo para la influencia de A. galli en la expresión de citoquinas clave relacionadas con una respuesta inmune parasitaria y en la composición de la microbiota yeyunal. Veintiocho aves macho de tipo postura fueron desafiadas a los 24, 25 y 26 días de edad. Se mantuvieron 28 aves adicionales como controles no infectados. A partir del día 31, se practicó la eutanasia a tres aves de cada grupo cada semana hasta las 8 semanas posteriores a la infección (PI). El número de larvas aisladas de la pared intestinal disminuyó con el tiempo, hasta que no se observaron larvas a las 7 y 8 semanas después de la infección. A las cinco semanas post-infección, hubo una regulación ascendente numérica de todas las citoquinas (TGF-ß, IFN-γ, IL-4, IL-8, IL-10, IL-13) en el grupo infectado, pero este cambio solo fue estadísticamente significativo para IL-13. En ese momento, se esperaba que las larvas se hubieran convertido en adultos que eliminarían huevos en las heces. Sin embargo, no se observaron nemátodos adultos y no hubo eliminación de huevos. Para el análisis de microbiota, hubo diferencias significativas en la diversidad alfa (diversidad filogenética de Faith) entre los grupos de desafío y control y el análisis de diversidad beta mostró ligeras diferencias entre las muestras, lo que sugiere que la edad de las aves fue la razón principal de la separación de los grupos. Estos hallazgos sugieren que la regulación al alza de todas las citocinas evaluadas en la semana 5 podría ser el motivo de la resolución de la infección. Las posibles explicaciones son que una dosis alta de infección y el hecho de que las aves fueran alimentadas con un alimento más denso desde el punto de vista nutricional podrían haber contribuido a que el sistema inmunitario de las aves eliminara la infección antes de que los nemátodos pudieran alcanzar la madurez.


Assuntos
Ascaridíase , Microbioma Gastrointestinal , Doenças das Aves Domésticas , Animais , Masculino , Ascaridia , Ascaridíase/imunologia , Ascaridíase/microbiologia , Ascaridíase/parasitologia , Ascaridíase/veterinária , Galinhas , Citocinas/genética , Citocinas/imunologia , Filogenia , Doenças das Aves Domésticas/microbiologia , Doenças das Aves Domésticas/parasitologia
7.
BMC Psychiatry ; 22(1): 185, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35291964

RESUMO

BACKGROUND: Antipsychotic medication can reduce psychotic symptoms and risk of relapse in people with schizophrenia and related disorders, but it is not always effective and adverse effects can be significant. We know little of patients' views about continuing or discontinuing antipsychotic treatment. AIMS: To explore the views of people with schizophrenia and other psychotic disorders about continuing their antipsychotic medication or attempting to reduce or discontinue this medication with clinical support. METHODS: We collected quantitative and qualitative data by conducting semi-structured interviews in London, UK. Factors predicting a desire to discontinue medication were explored. Content analysis of qualitative data was undertaken. RESULTS: We interviewed 269 participants. 33% (95% CI, 27 to 39%) were content with taking long-term antipsychotic medication. Others reported they took it reluctantly (19%), accepted it on a temporary basis (24%) or actively disliked it (18%). 31% (95% CI, 25 to 37%) said they would like to try to stop medication with professional support, and 45% (95% CI, 39 to 51%) wanted the opportunity to reduce medication. People who wanted to discontinue had more negative attitudes towards the medication but were otherwise similar to other participants. Wanting to stop or reduce medication was motivated mainly by adverse effects and health concerns. Professional support was identified as potentially helpful to achieve reduction. CONCLUSIONS: This large study reveals that patients are commonly unhappy about the idea of taking antipsychotics on a continuing or life-long basis. Professional support for people who want to try to reduce or stop medication is valued.


Assuntos
Antipsicóticos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Transtornos Psicóticos , Esquizofrenia , Antipsicóticos/uso terapêutico , Humanos , Transtornos Psicóticos/tratamento farmacológico , Recidiva , Esquizofrenia/induzido quimicamente , Esquizofrenia/tratamento farmacológico , Suspensão de Tratamento
8.
Schizophr Res ; 241: 275-291, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35217356

RESUMO

Social functioning is an important part of recovery and a key treatment target in clinical research in schizophrenia. Evaluating and comparing interventions is challenged by the choice of many measures which focus on different aspects of functioning, with little to guide selection. This results in difficulties comparing outcomes of treatment where studies have used different measures. To improve the measurement of social functioning in intervention research, we aimed to provide practical information on suitability of measures. We conducted a systematic review of measures developed or psychometrically evaluated since 2007, and assessed and discussed the structure, content, quality, and the use of the measures in intervention research. Thirty-two measures of social functioning and 22 validation papers were identified. Measures included structured questionnaires, semi-structured interviews, and assessment of performance on specific tasks. The content of measures was organised into eight categories, which are in order of frequency with which they were covered by measures: activities of daily living, productive activity, relationships, leisure activities, cognition, anti-social behaviour, psychosis symptoms and self-esteem and empowerment. In terms of quality, most measures were rated as moderate, with the Personal and Social Performance Scale gaining the highest rating. However, there was little data on responsiveness of measures, or how they compare to objective or 'real-world' indicators of functioning. The Social Functioning Scale and Personal and Social Performance Scale have been most frequently used in intervention studies to date. Future research should aim to provide further data on psychometric properties relevant to intervention research.


Assuntos
Esquizofrenia , Atividades Cotidianas , Humanos , Avaliação de Resultados em Cuidados de Saúde , Esquizofrenia/diagnóstico , Esquizofrenia/terapia , Ajustamento Social , Interação Social
9.
G3 (Bethesda) ; 11(6)2021 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-33788948

RESUMO

Chromatin immunoprecipitation followed by massively parallel, high throughput sequencing (ChIP-seq) is the method of choice for genome-wide identification of DNA segments bound by specific transcription factors or in chromatin with particular histone modifications. However, the quality of ChIP-seq datasets varies widely, with a substantial fraction being of intermediate to poor quality. Thus, it is important to discern and control the factors that contribute to variation in ChIP-seq. In this study, we focused on sonication, a user-controlled variable, to produce sheared chromatin. We systematically varied the amount of shearing of fixed chromatin from a mouse erythroid cell line, carefully measuring the distribution of resultant fragment lengths prior to ChIP-seq. This systematic study was complemented with a retrospective analysis of additional experiments. We found that the level of sonication had a pronounced impact on the quality of ChIP-seq signals. Over-sonication consistently reduced quality, while the impact of under-sonication differed among transcription factors, with no impact on sites bound by CTCF but frequently leading to the loss of sites occupied by TAL1 or bound by POL2. The bound sites not observed in low-quality datasets were inferred to be a mix of both direct and indirect binding. We leveraged these findings to produce a set of CTCF ChIP-seq datasets in rare, primary hematopoietic progenitor cells. Our observation that the amount of chromatin sonication is a key variable in success of ChIP-seq experiments indicates that monitoring the level of sonication can improve ChIP-seq quality and reproducibility and facilitate ChIP-seq in rare cell types.


Assuntos
Sequenciamento de Cromatina por Imunoprecipitação , Cromatina , Camundongos , Animais , Cromatina/genética , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Análise de Sequência de DNA/métodos , Fatores de Transcrição/genética
10.
Schizophr Res ; 225: 47-54, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-31604607

RESUMO

INTRODUCTION: Avoidance of relapse is the main aim of long-term antipsychotic treatment in schizophrenia, yet how 'relapse' is defined in trials is not well-known. METHODS: We conducted a systematic review of definitions of relapse in trials of continuous antipsychotic treatment compared with discontinuation, intermittent treatment or dose reduction for people with schizophrenia spectrum disorders. Trials were identified from previous Cochrane reviews and a new search. The quality of relapse definitions was rated in terms of reliability and clinical relevance and associations between quality of definitions and trial characteristics and outcome were explored. RESULTS: We identified 82 reports of 81 trials which employed 54 different definitions of relapse. There were 33 definitions in the 35 trials published since 1990, with recent trials employing complex definitions often involving alternative criteria. Only ten primary definitions of relapse required the presence of psychotic symptoms in all cases, and only three specified this in combination with a measure of overall severity or functional decline. Only two definitions specified a duration longer than two days. Relapse definitions were rated as showing good reliability in 37 trials, but only seven showed good clinical relevance. Six trials with definitions that were both reliable and clinically relevant were slightly longer, but did not differ from remaining trials in other characteristics or overall or relative risk of relapse. CONCLUSIONS: Antipsychotic trials define relapse in numerous different ways, and few definitions consistently reflect suggested indications of a clinically significant relapse.


Assuntos
Antipsicóticos , Transtornos Psicóticos , Esquizofrenia , Antipsicóticos/uso terapêutico , Humanos , Transtornos Psicóticos/tratamento farmacológico , Recidiva , Reprodutibilidade dos Testes , Esquizofrenia/tratamento farmacológico
11.
BMC Geriatr ; 17(1): 72, 2017 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-28327088

RESUMO

BACKGROUND: Positive psychology research in dementia care has largely been confined to the qualitative literature because of the lack of robust outcome measures. The aim of this study was to develop positive psychology outcome measures for people with dementia. METHODS: Two measures were each developed in four stages. Firstly, literature reviews were conducted to identify and operationalise salient positive psychology themes in the qualitative literature and to examine existing measures of positive psychology. Secondly, themes were discussed within a qualitative study to add content validity for identified concepts (n = 17). Thirdly, draft measures were submitted to a panel of experts for feedback (n = 6). Finally, measures were used in a small-scale pilot study (n = 33) to establish psychometric properties. RESULTS: Salient positive psychology themes were identified as hope, resilience, a sense of independence and social engagement. Existing measures of hope and resilience were adapted to form the Positive Psychology Outcome Measure (PPOM). Due to the inter-relatedness of independence and engagement for people with dementia, 28 items were developed for a new scale of Engagement and Independence in Dementia Questionnaire (EID-Q) following extensive qualitative work. Both measures demonstrated acceptable internal consistency (α = .849 and α = .907 respectively) and convergent validity. CONCLUSIONS: Two new positive psychology outcome measures were developed using a robust four-stage procedure. Preliminary psychometric data was adequate and the measures were easy to use, and acceptable for people with dementia.


Assuntos
Demência/psicologia , Demência/terapia , Avaliação de Resultados em Cuidados de Saúde , Idoso , Feminino , Esperança , Humanos , Masculino , Projetos Piloto , Psicometria , Pesquisa Qualitativa , Reprodutibilidade dos Testes , Resiliência Psicológica , Comportamento Social , Inquéritos e Questionários
12.
Mol Cell Biol ; 36(1): 157-72, 2016 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-26503782

RESUMO

Erythroid development and differentiation from multiprogenitor cells into red blood cells requires precise transcriptional regulation. Key erythroid transcription factors, GATA1 and TAL1, cooperate, along with other proteins, to regulate many aspects of this process. How GATA1 and TAL1 are juxtaposed along the DNA and their cognate DNA binding site across the mouse genome remains unclear. We applied high-resolution ChIP-exo (chromatin immunoprecipitation followed by 5'-to-3' exonuclease treatment and then massively parallel DNA sequencing) to GATA1 and TAL1 to study their positional organization across the mouse genome during GATA1-dependent maturation. Two complementary methods, MultiGPS and peak pairing, were used to determine high-confidence binding locations by ChIP-exo. We identified ∼10,000 GATA1 and ∼15,000 TAL1 locations, which were essentially confirmed by ChIP-seq (chromatin immunoprecipitation followed by massively parallel DNA sequencing). Of these, ∼4,000 locations were bound by both GATA1 and TAL1. About three-quarters of them were tightly linked to a partial E-box located 7 or 8 bp upstream of a WGATAA motif. Both TAL1 and GATA1 generated distinct characteristic ChIP-exo peaks around WGATAA motifs that reflect their positional arrangement within a complex. We show that TAL1 and GATA1 form a precisely organized complex at a compound motif consisting of a TG 7 or 8 bp upstream of a WGATAA motif across thousands of genomic locations.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Diferenciação Celular/fisiologia , Fator de Transcrição GATA1/metabolismo , Regulação da Expressão Gênica/fisiologia , Genômica , Proteínas Proto-Oncogênicas/metabolismo , Animais , Sequência de Bases , Imunoprecipitação da Cromatina/métodos , DNA/metabolismo , Camundongos , Análise de Sequência de DNA/métodos , Proteína 1 de Leucemia Linfocítica Aguda de Células T , Fatores de Transcrição/metabolismo
13.
Artigo em Inglês | MEDLINE | ID: mdl-25984238

RESUMO

BACKGROUND: Regulated gene expression controls organismal development, and variation in regulatory patterns has been implicated in complex traits. Thus accurate prediction of enhancers is important for further understanding of these processes. Genome-wide measurement of epigenetic features, such as histone modifications and occupancy by transcription factors, is improving enhancer predictions, but the contribution of these features to prediction accuracy is not known. Given the importance of the hematopoietic transcription factor TAL1 for erythroid gene activation, we predicted candidate enhancers based on genomic occupancy by TAL1 and measured their activity. Contributions of multiple features to enhancer prediction were evaluated based on the results of these and other studies. RESULTS: TAL1-bound DNA segments were active enhancers at a high rate both in transient transfections of cultured cells (39 of 79, or 56%) and transgenic mice (43 of 66, or 65%). The level of binding signal for TAL1 or GATA1 did not help distinguish TAL1-bound DNA segments as active versus inactive enhancers, nor did the density of regulation-related histone modifications. A meta-analysis of results from this and other studies (273 tested predicted enhancers) showed that the presence of TAL1, GATA1, EP300, SMAD1, H3K4 methylation, H3K27ac, and CAGE tags at DNase hypersensitive sites gave the most accurate predictors of enhancer activity, with a success rate over 80% and a median threefold increase in activity. Chromatin accessibility assays and the histone modifications H3K4me1 and H3K27ac were sensitive for finding enhancers, but they have high false positive rates unless transcription factor occupancy is also included. CONCLUSIONS: Occupancy by key transcription factors such as TAL1, GATA1, SMAD1, and EP300, along with evidence of transcription, improves the accuracy of enhancer predictions based on epigenetic features.

14.
Genom Data ; 4: 1-7, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25729644

RESUMO

During the maturation phase of mammalian erythroid differentiation, highly proliferative cells committed to the erythroid lineage undergo dramatic changes in morphology and function to produce circulating, enucleated erythrocytes. These changes are caused by equally dramatic alterations in gene expression, which in turn are driven by changes in the abundance and binding patterns of transcription factors such as GATA1. We have studied the dynamics of GATA1 binding by ChIP-seq and the global expression responses by RNA-seq in a GATA1-dependent mouse cell line model for erythroid maturation, in both cases examining seven progressive stages during differentiation. Analyses of these data should provide insights both into mechanisms of regulation (early versus late targets) and the consequences in cell physiology (e.g. distinctive categories of genes regulated at progressive stages of differentiation). The data are deposited in the Gene Expression Omnibus, series GSE36029, GSE40522, GSE49847, and GSE51338.

15.
Mol Microbiol ; 76(2): 409-27, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20233308

RESUMO

Caulobacter crescentus attachment is mediated by the holdfast, a complex of polysaccharide anchored to the cell by HfaA, HfaB and HfaD. We show that all three proteins are surface exposed outer membrane (OM) proteins. HfaA is similar to fimbrial proteins and assembles into a high molecular weight (HMW) form requiring HfaD, but not holdfast polysaccharide. The HfaD HMW form is dependent on HfaA but not on holdfast polysaccharide. We show that HfaA and HfaD form homomultimers and that they require HfaB for stability and OM translocation. All three proteins localize to the late pre-divisional flagellar pole, remain at this pole in swarmer cells, and localize at the stalk tip after the stalk is synthesized at the same pole. Hfa protein localization requires the holdfast polysaccharide secretion proteins and the polar localization factor PodJ. An hfaB mutant is much more severely deficient in adherence and holdfast attachment than hfaA and hfaD mutants. An hfaA, hfaD double mutant phenocopies either single mutant, suggesting that HfaB is involved in holdfast attachment beyond secretion of HfaA and HfaD. We hypothesize that HfaB secretes HfaA and HfaD across the outer membrane, and the three proteins form a complex anchoring the holdfast to the stalk.


Assuntos
Aderência Bacteriana , Proteínas da Membrana Bacteriana Externa/metabolismo , Caulobacter crescentus/fisiologia , Interações Hospedeiro-Patógeno , Fatores de Virulência/metabolismo , Adesinas Bacterianas/metabolismo , Proteínas de Bactérias/metabolismo , Caulobacter crescentus/patogenicidade , Flagelos/química , Substâncias Macromoleculares/metabolismo , Proteínas de Membrana/metabolismo , Polissacarídeos/metabolismo , Ligação Proteica , Multimerização Proteica
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