27 research outputs found
AI-2 does not function as a quorum sensing molecule in Campylobacter jejuni during exponential growth in vitro
Get PDF<p>Abstract</p> <p>Background</p> <p><it>Campylobacter jejuni </it>contains a homologue of the <it>luxS </it>gene shown to be responsible for the production of the signalling molecule autoinducer-2 (AI-2) in <it>Vibrio harveyi </it>and <it>Vibrio cholerae</it>. The aim of this study was to determine whether AI-2 acted as a diffusible quorum sensing signal controlling <it>C. jejuni </it>gene expression when it is produced at high levels during mid exponential growth phase.</p> <p>Results</p> <p>AI-2 activity was produced by the parental strain NCTC 11168 when grown in rich Mueller-Hinton broth (MHB) as expected, but interestingly was not present in defined Modified Eagles Medium (MEM-α). Consistent with previous studies, the <it>luxS </it>mutant showed comparable growth rates to the parental strain and exhibited decreased motility halos in both MEM-α and MHB. Microarray analysis of genes differentially expressed in wild type and <it>luxS </it>mutant strains showed that many effects on mRNA transcript abundance were dependent on the growth medium and linked to metabolic functions including methionine metabolism. Addition of exogenously produced AI-2 to the wild type and the <it>luxS </it>mutant, growing exponentially in either MHB or MEM-α did not induce any transcriptional changes as analysed by microarray.</p> <p>Conclusion</p> <p>Taken together these results led us to conclude that there is no evidence for the role of AI-2 in cell-to-cell communication in <it>C. jejuni </it>strain NCTC 11168 under the growth conditions used, and that the effects of the <it>luxS </it>mutation on the transcriptome are related to the consequential loss of function in the activated methyl cycle.</p
The pre-implementation process of the continuity of midwifery care research strategy: An implementation science methodologically guided initiative
Get PDFIn 2017, the continuity of midwifery care model was introduced as the way forward in Scottish maternity and neonatal services. There is no shared research strategy aligning research needs with an agenda, setting goals and revising plans. In this paper, we outline the systematic multi-actor and integrated knowledge translation process that frames and informs our initiative to develop a continuity of midwifery care research strategy, focusing on establishing a comprehensive mission, vision, and research topics. Guided by the pre-implementation process as part of the implementation science methodology, we engaged with a Scottish group of stakeholders, including service providers, academics, managers/policymakers, service users’ advocates and midwifery students during targeted activities to contribute to a widely held perspective. We collected data using an online poll, subgroup brainstorming sessions, plenary group discussions, evaluation and video recording to frame and inform the research mission, vision and study topics. Data collection tools included word clouds, brainstorming sheets, observation notes, ranking, evaluation forms and recording transcripts. The outcomes of a stepwise analytic approach of mapping, synthesising, and using the data to develop a continuity of midwifery care research direction and focus will inform future funding applications, studies and projects. The pre-implementation process and actions described in this paper can serve as an example of structuring comprehensive research strategies in other settings, cultures, domains or contexts
Specificity determinants for the AMP-activated protein kinase and its plant homologue analysed using synthetic peptides
Get PDFAbstractInspection of sequences around sites phosphorylated by the AMP-activated protein kinase (AMP-PK), and homologous sequences from other species, indicates conserved features. There are hydrophobic residues (M, V, L, I) at P-5 and P+4, and at least one basic residue (R, K, H) at P-2, P-3 or P-4. The importance of these residues has been established for AMP-PK and its putative plant homologue using a series of synthetic peptides. These results confirm the functional similarity of the animal and plant kinases, and suggest that the required motif for recognition of substrate by either kinase is M/V/L/I-(R/K/H,X,X)-X-S/T-X-X-X-M/V/L/I
Validation of the Oxford WebQ online 24-hour dietary questionnaire using biomarkers
Get PDFThe Oxford WebQ is an online 24-hour dietary questionnaire that is appropriate for repeated administration in large-scale prospective studies, including the UK Biobank study and the Million Women Study. We compared the performance of the Oxford WebQ and a traditional interviewer-administered multiple-pass 24-hour dietary recall against biomarkers for protein, potassium, and total sugar intake and total energy expenditure estimated by accelerometry. We recruited 160 participants in London, United Kingdom, between 2014 and 2016 and measured their biomarker levels at 3 nonconsecutive time points. The measurement error model simultaneously compared all 3 methods. Attenuation factors for protein, potassium, total sugar, and total energy intakes estimated as the mean of 2 applications of the Oxford WebQ were 0.37, 0.42, 0.45, and 0.31, respectively, with performance improving incrementally for the mean of more measures. Correlation between the mean value from 2 Oxford WebQs and estimated true intakes, reflecting attenuation when intake is categorized or ranked, was 0.47, 0.39, 0.40, and 0.38, respectively, also improving with repeated administration. These correlations were similar to those of the more administratively burdensome interviewer-based recall. Using objective biomarkers as the standard, the Oxford WebQ performs well across key nutrients in comparison with more administratively burdensome interviewer-based 24-hour recalls. Attenuation improves when the average value is taken over repeated administrations, reducing measurement error bias in assessment of diet-disease associations
Adding 6 months of androgen deprivation therapy to postoperative radiotherapy for prostate cancer: a comparison of short-course versus no androgen deprivation therapy in the RADICALS-HD randomised controlled trial
Get PDFBackground
Previous evidence indicates that adjuvant, short-course androgen deprivation therapy (ADT) improves metastasis-free survival when given with primary radiotherapy for intermediate-risk and high-risk localised prostate cancer. However, the value of ADT with postoperative radiotherapy after radical prostatectomy is unclear.
Methods
RADICALS-HD was an international randomised controlled trial to test the efficacy of ADT used in combination with postoperative radiotherapy for prostate cancer. Key eligibility criteria were indication for radiotherapy after radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to radiotherapy alone (no ADT) or radiotherapy with 6 months of ADT (short-course ADT), using monthly subcutaneous gonadotropin-releasing hormone analogue injections, daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as distant metastasis arising from prostate cancer or death from any cause. Standard survival analysis methods were used, accounting for randomisation stratification factors. The trial had 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 80% to 86% (hazard ratio [HR] 0·67). Analyses followed the intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov, NCT00541047.
Findings
Between Nov 22, 2007, and June 29, 2015, 1480 patients (median age 66 years [IQR 61–69]) were randomly assigned to receive no ADT (n=737) or short-course ADT (n=743) in addition to postoperative radiotherapy at 121 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 9·0 years (IQR 7·1–10·1), metastasis-free survival events were reported for 268 participants (142 in the no ADT group and 126 in the short-course ADT group; HR 0·886 [95% CI 0·688–1·140], p=0·35). 10-year metastasis-free survival was 79·2% (95% CI 75·4–82·5) in the no ADT group and 80·4% (76·6–83·6) in the short-course ADT group. Toxicity of grade 3 or higher was reported for 121 (17%) of 737 participants in the no ADT group and 100 (14%) of 743 in the short-course ADT group (p=0·15), with no treatment-related deaths.
Interpretation
Metastatic disease is uncommon following postoperative bed radiotherapy after radical prostatectomy. Adding 6 months of ADT to this radiotherapy did not improve metastasis-free survival compared with no ADT. These findings do not support the use of short-course ADT with postoperative radiotherapy in this patient population
Duration of androgen deprivation therapy with postoperative radiotherapy for prostate cancer: a comparison of long-course versus short-course androgen deprivation therapy in the RADICALS-HD randomised trial
Get PDFBackground
Previous evidence supports androgen deprivation therapy (ADT) with primary radiotherapy as initial treatment for intermediate-risk and high-risk localised prostate cancer. However, the use and optimal duration of ADT with postoperative radiotherapy after radical prostatectomy remains uncertain.
Methods
RADICALS-HD was a randomised controlled trial of ADT duration within the RADICALS protocol. Here, we report on the comparison of short-course versus long-course ADT. Key eligibility criteria were indication for radiotherapy after previous radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to add 6 months of ADT (short-course ADT) or 24 months of ADT (long-course ADT) to radiotherapy, using subcutaneous gonadotrophin-releasing hormone analogue (monthly in the short-course ADT group and 3-monthly in the long-course ADT group), daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as metastasis arising from prostate cancer or death from any cause. The comparison had more than 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 75% to 81% (hazard ratio [HR] 0·72). Standard time-to-event analyses were used. Analyses followed intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and
ClinicalTrials.gov
,
NCT00541047
.
Findings
Between Jan 30, 2008, and July 7, 2015, 1523 patients (median age 65 years, IQR 60–69) were randomly assigned to receive short-course ADT (n=761) or long-course ADT (n=762) in addition to postoperative radiotherapy at 138 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 8·9 years (7·0–10·0), 313 metastasis-free survival events were reported overall (174 in the short-course ADT group and 139 in the long-course ADT group; HR 0·773 [95% CI 0·612–0·975]; p=0·029). 10-year metastasis-free survival was 71·9% (95% CI 67·6–75·7) in the short-course ADT group and 78·1% (74·2–81·5) in the long-course ADT group. Toxicity of grade 3 or higher was reported for 105 (14%) of 753 participants in the short-course ADT group and 142 (19%) of 757 participants in the long-course ADT group (p=0·025), with no treatment-related deaths.
Interpretation
Compared with adding 6 months of ADT, adding 24 months of ADT improved metastasis-free survival in people receiving postoperative radiotherapy. For individuals who can accept the additional duration of adverse effects, long-course ADT should be offered with postoperative radiotherapy.
Funding
Cancer Research UK, UK Research and Innovation (formerly Medical Research Council), and Canadian Cancer Society
Facilitating antenatal education classes in Scotland
No full textProvision of antenatal education classes by registered midwives is viewed as pivotal in sharing information and providing health education for women and their partners during their journey into parenthood. The midwife's influence on the overall success of antenatal education classes has been identified in research but without focus on experiences of community midwives when fulfilling this aspect of their role. A study to address this gap using an interpretive/hermeneutic phenomenological approach was carried out. Semi-structured audiotaped individual interviews were transcribed and analysed by the researcher. The following themes were identified and explored: educator skills and confidence, midwife/client satisfaction and midwife perceptions. Community midwives appeared enthusiastic about their role in the provision of antenatal education classes, which facilitated the development of trusting relationships between women and the midwives. Despite expressing personal interest and motivation, some community midwives indicated that a few colleagues disliked or avoided facilitating antenatal education classes. The reluctance of some community midwives to fulfil this responsibility and meet the requirements of their professional role is of particular concern and further exploration of this issue is required
Regulation of multisite phosphorylation and 14-3-3 binding of AS160 in response to IGF-1, EGF, PMA and AICAR
No full textAS160 (Akt substrate of 160 kDa) mediates insulin-stimulated GLUT4 (glucose transporter 4) translocation, but is widely expressed in insulin-insensitive tissues lacking GLUT4. Having isolated AS160 by 14-3-3-affinity chromatography, we found that binding of AS160 to 14-3-3 isoforms in HEK (human embryonic kidney)-293 cells was induced by IGF-1 (insulin-like growth factor-1), EGF (epidermal growth factor), PMA and, to a lesser extent, AICAR (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside). AS160-14-3-3 interactions were stabilized by chemical cross-linking and abolished by dephosphorylation. Eight residues on AS160 (Ser(318), Ser(341), Thr(568), Ser(570), Ser(588), Thr(642), Ser(666) and Ser(751)) were differentially phosphorylated in response to IGF-1, EGF, PMA and AICAR. The binding of 14-3-3 proteins to HA–AS160 (where HA is haemagglutinin) was markedly decreased by mutation of Thr(642) and abolished in a Thr642Ala/Ser341Ala double mutant. The AGC (protein kinase A/protein kinase G/protein kinase C-family) kinases RSK1 (p90 ribosomal S6 kinase 1), SGK1 (serum- and glucocorticoid-induced protein kinase 1) and PKB (protein kinase B) displayed distinct signatures of AS160 phosphorylation in vitro: all three kinases phosphorylated Ser(318), Ser(588) and Thr(642); RSK1 also phosphorylated Ser(341), Ser(751) and to a lesser extent Thr(568); and SGK1 phosphorylated Thr(568) and Ser(751). AMPK (AMP-activated protein kinase) preferentially phosphorylated Ser(588), with less phosphorylation of other sites. In cells, the IGF-1-stimulated phosphorylations, and certain EGF-stimulated phosphorylations, were inhibited by PI3K (phosphoinositide 3-kinase) inhibitors, whereas the RSK inhibitor BI-D1870 inhibited the PMA-induced phosphorylations. The expression of LKB1 in HeLa cells and the use of AICAR in HEK-293 cells promoted phosphorylation of Ser(588), but only weak Ser(341) and Thr(642) phosphorylations and binding to 14-3-3s. Paradoxically however, phenformin activated AMPK without promoting AS160 phosphorylation. The IGF-1-induced phosphorylation of the novel phosphorylated Ser(666)-Pro site was suppressed by AICAR, and by combined mutation of a TOS (mTOR signalling)-like sequence (FEMDI) and rapamycin. Thus, although AS160 is a common target of insulin, IGF-1, EGF, PMA and AICAR, these stimuli induce distinctive patterns of phosphorylation and 14-3-3 binding, mediated by at least four protein kinases
Metabolism and epigenetics: a link cancer cells exploit
No full textBoth cellular nutrient metabolism and chromatin organization are remodeled in cancer cells, and these alterations play key roles in tumor development and growth. Many chromatin modifying-enzymes utilize metabolic intermediates as cofactors or substrates, and recent studies have demonstrated that the epigenome is sensitive to cellular metabolism. The contribution of metabolic alterations to epigenetic deregulation in cancer cells is just beginning to emerge, as are the roles of the metabolism-epigenetics link in tumorigenesis. Here we review the roles of acetyl-CoA and S-adenosylmethionine (SAM), donor substrates for acetylation and methylation reactions, respectively, in regulating chromatin modifications in response to nutrient metabolism. We further discuss how oncogenic signaling, cell metabolism, and histone modifications are interconnected and how their relationship might impact tumor growth
