A-Raf: A new star of the family of raf kinases

The Ras-Raf-MEK-MAPK (mitogen-activated protein kinase)-signaling pathway plays a key role in the regulation of many cellular functions, including cell proliferation, differentiation and transformation, by transmitting signals from membrane receptors to various cytoplasmic and nuclear targets. One of the key components of this pathway is the serine/threonine protein kinase, Raf. The Raf family kinases (A-Raf, B-Raf and C-Raf) have been intensively studied since being identified in the early 1980s as retroviral oncogenes, especially with respect to the discovery of activating mutations of B-Raf in a large number of tumors which led to intensified efforts to develop drugs targeting Raf kinases. This also resulted in a rapid increase in our knowledge of the biological functions of the B-Raf and C-Raf isoforms, which may in turn be contrasted with the little that is known about A-Raf. The biological functions of A-Raf remain mysterious, although it appears to share some of the basic properties of the other two isoforms. Recently, emerging evidence has begun to reveal the functions of A-Raf, of which some are kinase-independent. These include the inhibition of apoptosis by binding to MST2, acting as safeguard against oncogenic transformation by suppressing extracellular signal-regulated kinases (ERK) activation and playing a role in resistance to Raf inhibitors. In this review, we discuss the regulation of A-Raf protein expression, and the roles of A-Raf in apoptosis and cancer, with a special focus on its role in resistance to Raf inhibitors. We also describe the scaffold functions of A-Raf and summarize the unexpected complexity of Raf signaling.

Rethinking the Bloody Code in Eighteenth-Century Britain: Capital Punishment at the Centre and on the Periphery

During the long eighteenth century the capital code, and more specifically the so-called 'Bloody Code' which subjected a vast and increasing range of property crimes to the death penalty, was the centre of much popular attention and of extensive debate. The impact of the Bloody Code has also attracted much attention from historians, some of whom have argued that it played a vital role both within the criminal law and in eighteenth-century social relations more generally. However, the geography of the Bloody Code and the possibility that there were major regional differences both in the use of hanging, and in attitudes to it, has been largely ignored by historians. By systematically exploring the spatial dimensions of capital punishment in eighteenth-century Britain, this article demonstrates the refusal of many areas on the periphery to implement the Bloody Code. The reluctance in the far western and northern periphery of Britain to execute property offenders, it is argued, requires us to rethink some of our core assumptions about the key role historians have given to the Bloody Code in maintaining the hegemony of the elite, about the process by which the capital code came to be reformed, and about the reach of the state in the long eighteenth century.

Optimal Manual Exchange Transfusion Protocol for Sickle Cell Disease: A Retrospective Comparison of Two Comprehensive Care Centers in the United Kingdom and Canada

Chronic red blood cell (RBC) transfusion is employed for a wide range of sickle cell disease complications, ranging from primary and secondary stroke prophylaxis to prevention of painful vaso-occlusive episodes. Currently different methods are employed by centers for chronic transfusion that include simple, automated and partial manual RBC exchange transfusion. A retrospective cohort study of two different manual RBC exchange transfusion methods was conducted between two comprehensive care centers in Toronto, ON, Canada and London, United Kingdom in 19 and 21 sickle cell disease adults, respectively. London used a weight-based protocol, while Toronto used a unit-based method. Our results indicated that sickle cell disease patients utilizing a weight-based method are more often unable to achieve the prescribed Hb S (HBB: c.20A > T) target compared to the unit-based method (90.0 vs. 53.0% in the weight-based and unit-based methods, respectively, p = 0.0123). On multivariable logistic regression, none of the covariates examined was found to influence the ability to achieve the prescribed Hb S target after accounting for the exchange transfusion method. Mean interval of exchange sessions, session duration, total units of packed RBC, volume of blood used by body weight each year, the mean post exchange hematocrit [or packed cell volume (PCV)] and ferritin change were similar in both cohorts. In conclusion, the unit-based method was more effective at maintaining the prescribed Hb S target.

Hope, optimism and survival in a randomised trial of chemotherapy for metastatic colorectal cancer

PURPOSE

Psychological responses to cancer are widely believed to affect survival. We investigated associations between hope, optimism, anxiety, depression, health utility and survival in patients starting first-line chemotherapy for metastatic colorectal cancer.

METHODS

Four hundred twenty-nine subjects with metastatic colorectal cancer in a randomised controlled trial of chemotherapy completed baseline questionnaires assessing the following: hopefulness, optimism, anxiety and depression and health utility. Hazard ratios (HRs) and P values were calculated with Cox models for overall survival (OS) and progression-free survival (PFS) in univariable and multivariable analyses.

RESULTS

Median follow-up was 31 months. Univariable analyses showed that OS was associated negatively with depression (HR 2.04, P < 0.001) and positively with health utility (HR 0.56, P < 0.001) and hopefulness (HR 0.75, P = 0.013). In multivariable analysis, OS was also associated negatively with depression (HR 1.72, P < 0.001) and positively with health utility (HR 0.73, P = 0.014), but not with optimism, anxiety or hopefulness. PFS was not associated with hope, optimism, anxiety or depression in any analyses.

CONCLUSIONS

Depression and health utility, but not optimism, hope or anxiety, were associated with survival after controlling for known prognostic factors in patients with advanced colorectal cancer. Further research is required to understand the nature of the relationship between depression and survival. If a causal mechanism is identified, this may lead to interventional possibilities.

Evidence of what works to support and sustain care at home for people with dementia: a literature review with a systematic approach

BACKGROUND

This paper synthesises research evidence about the effectiveness of services intended to support and sustain people with dementia to live at home, including supporting carers. The review was commissioned to support an inspection regime and identifies the current state of scientific knowledge regarding appropriate and effective services in relation to a set of key outcomes derived from Scottish policy, inspection practice and standards. However, emphases on care at home and reduction in the use of institutional long term care are common to many international policy contexts and welfare regimes.

METHODS

Systematic searches of relevant electronic bibliographic databases crossing medical, psychological and social scientific literatures (CINAHL, IngentaConnect, Medline, ProQuest, PsychINFO and Web of Science) in November 2012 were followed by structured review and full-text evaluation processes, the latter using methodology-appropriate quality assessment criteria drawing on established protocols.

RESULTS

Of 131 publications evaluated, 56 were assessed to be of 'high' quality, 62 of 'medium' quality and 13 of 'low' quality. Evaluations identified weaknesses in many published accounts of research, including lack of methodological detail and failure to evidence conclusions. Thematic analysis revealed multiple gaps in the evidence base, including in relation to take-up and use of self-directed support by people with dementia, use of rapid response teams and other multidisciplinary approaches, use of technology to support community-dwelling people with dementia, and support for people without access to unpaid or informal support.

CONCLUSIONS

In many areas, policy and practice developments are proceeding on a limited evidence base. Key issues affecting substantial numbers of existing studies include: poorly designed and overly narrowly focused studies; variability and uncertainty in outcome measurement; lack of focus on the perspectives of people with dementia and supporters; and failure to understanding the complexities of living with dementia, and of the kinds of multifactorial interventions needed to provide holistic and effective support. Weaknesses in the evidence base present challenges both to practitioners looking for guidance on how best to design and deliver evidence-based services to support people living with dementia in the community and their carers and to those charged with the inspection of services.

Blood cultures in acute surgical admissions

INTRODUCTION

Obtaining blood cultures prior to the administration of antimicrobial therapy was a key recommendation of the 2012 UK Surviving Sepsis Campaign. Few studies have examined the effect blood cultures have on clinical management and there have been none on acute surgical admissions. This retrospective study sought to evaluate the effect of blood cultures on clinical management in acute surgical admissions.

METHODS

Data on acute surgical patients admitted between 1 January and 31 December 2012 were extracted from hospital records. Patients given intravenous antibiotics within 24 hours of admission were identified. Data collected included antibiotics administered, blood culture results, admission observations and white blood cell count. Case notes were reviewed for patients with positive cultures to establish whether the result led to a change in management.

RESULTS

Of 5,887 acute surgical admissions, 1,346 received intravenous antibiotics within 24 hours and 978 sets of blood cultures were taken in 690 patients. The recommended two sets of cultures were obtained in 246 patients (18%). Patients who had blood cultures taken had the same in-hospital mortality as those who had none taken (3.6% vs 3.5%, p=0.97). Blood cultures were positive in 80 cases (11.6%). The presence of systemic inflammatory response syndrome did not increase positivity rates (12.9% vs 10.3%, p=0.28). Overall, cultures altered management in two patients (0.3%).

CONCLUSIONS

Blood cultures rarely affect clinical management. In order to assess the additional value that blood cultures bring to sepsis management in acute surgical admissions, a prospective randomised trial focusing on outcome is needed.

Raf-interactome in tuning the complexity and diversity of Raf function

Raf kinases have been intensely studied subsequent to their discovery 30 years ago. The Ras-Raf-mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-extracellular signal-regulated kinase/mitogen-activated protein kinase (Ras-Raf-MEK-ERK/MAPK) signaling pathway is at the heart of the signaling networks that control many fundamental cellular processes and Raf kinases takes centre stage in the MAPK pathway, which is now appreciated to be one of the most common sources of the oncogenic mutations in cancer. The dependency of tumors on this pathway has been clearly demonstrated by targeting its key nodes; however, blockade of the central components of the MAPK pathway may have some unexpected side effects. Over recent years, the Raf-interactome or Raf-interacting proteins have emerged as promising targets for protein-directed cancer therapy. This review focuses on the diversity of Raf-interacting proteins and discusses the mechanisms by which these proteins regulate Raf function, as well as the implications of targeting Raf-interacting proteins in the treatment of human cancer.

Probing the structure of the mechanosensitive channel of small conductance in lipid bilayers with pulsed electron-electron double resonance

Mechanosensitive channel proteins are important safety valves against osmotic shock in bacteria, and are involved in sensing touch and sound waves in higher organisms. The mechanosensitive channel of small conductance (MscS) has been extensively studied. Pulsed electron-electron double resonance (PELDOR or DEER) of detergent-solubilized protein confirms that as seen in the crystal structure, the outer ring of transmembrane helices do not pack against the pore-forming helices, creating an apparent void. The relevance of this void to the functional form of MscS in the bilayer is the subject of debate. Here, we report PELDOR measurements of MscS reconstituted into two lipid bilayer systems: nanodiscs and bicelles. The distance measurements from multiple mutants derived from the PELDOR data are consistent with the detergent-solution arrangement of the protein. We conclude, therefore, that the relative positioning of the transmembrane helices is preserved in mimics of the cell bilayer, and that the apparent voids are not an artifact of detergent solution but a property of the protein that will have to be accounted for in any molecular mechanism of gating.

The spatial effect of protein deuteration on nitroxide spin-label relaxation: implications for EPR distance measurement

Pulsed electron-electron double resonance (PELDOR) coupled with site-directed spin labeling is a powerful technique for the elucidation of protein or nucleic acid, macromolecular structure and interactions. The intrinsic high sensitivity of electron paramagnetic resonance enables measurement on small quantities of bio-macromolecules, however short relaxation times impose a limit on the sensitivity and size of distances that can be measured using this technique. The persistence of the electron spin-echo, in the PELDOR experiment, is one of the most crucial limitations to distance measurement. At a temperature of around 50 K one of the predominant factors affecting persistence of an echo, and as such, the sensitivity and measurable distance between spin labels, is the electron spin echo dephasing time (Tm). It has become normal practice to use deuterated solvents to extend Tm and recently it has been demonstrated that deuteration of the underlying protein significantly extends Tm. Here we examine the spatial effect of segmental deuteration of the underlying protein, and also explore the concentration and temperature dependence of highly deuterated systems.

Abstract 1726: Acquired resistance to rapamycin and mTOR kinase inhibitors is mediated by non-overlapping mutations in distinct sites in the mTOR protein

The prevalence of mTOR activation in cancer has led to the development of two classes of inhibitors of the protein as therapeutics: the natural product rapamycin and its analogs as well as direct inhibitors of mTOR kinase. mTOR exists in at least two multi-protein complexes. The mTORC1 complex phosphorylates S6K and 4EBP and stimulates protein translation, metabolism as well as other processes. The mTORC2 complex phosphorylates and activates AKT. Rapamycin binds to the immunophillin FKBP12. Drug-bound FKBP12 complex binds to mTOR FRB domain and selectively inhibits the activity of mTORC1. However, rapalogs preferentially inhibit S6K phosphorylation compared to 4EBP phosphorylation. Rapalogs have undergone extensive clinical testing and have significant antitumor activity in renal cell and pancreatic neuroendocrine tumors and, in combination with aromatase inhibitors, in resistant, ER positive breast cancers. In contrast, mTOR kinase inhibitors suppress both mTORC1 and mTORC2 functions and potently inhibit S6K, 4EBP and AKT S473 phosphorylation, these drugs are in early clinical testing.

In order to better understand the mechanism of action of these drugs and potential mechanisms of tumor escape from mTOR inhibition, we selected breast tumor cells for resistance to growth inhibition in cell culture by treatment with either rapamycin or an mTOR kinase inhibitor. In rapamycin resistant cells, phosphorylation of S6K and S6 were insensitive to the drug, but remained sensitive to mTOR kinase inhibitors. Conversely, in clones resistant to mTOR kinase inhibitors, mTORC1 and mTORC2 substrates were insensitive to the drugs, but S6K and S6 phosphorylation remained sensitive to rapamycin. Deep sequencing results explained these findings: rapamycin resistant clones harbored mutations in the FRB domain of mTOR, in the sites shown to interact with the FKBP12-rapamycin complex; mTOR kinase resistant clones harbored mutations in the mTOR catalytic domain. These mutations were not observed in the parental cells. It is likely that the mutations identified in each domain prevent binding of the drug.

Consistent with these data, growth of rapamycin resistant cells retain sensitivity to mTOR kinase inhibitors and mTOR kinase resistant cells retain sensitivity to rapalogs, both in tissue culture and in vivo. The results suggest that tumor cells with acquired resistance to mTOR inhibitors retain a requirement for mTOR signaling for proliferation. Furthermore, tumors resistant to either class of drug may not be cross-resistant to the other and combined therapy with both might delay the onset of resistance. Further studies on the genetics of human tumors with acquired resistance to these agents will determine the clinical importance of these findings.

Citation Format: Vanessa S. Rodrik-Outmezguine, Zhan Yao, Radha Mukherjee, Liqun Cai, Derek Barratt, Richard Ward, Teresa Klinowska, Elisa De Stanchina, Michael Berger, Jose Baselga, Neal Rosen. Acquired resistance to rapamycin and mTOR kinase inhibitors is mediated by non-overlapping mutations in distinct sites in the mTOR protein. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1726. doi:10.1158/1538-7445.AM2014-1726

A double-blind, placebo-controlled phase II study of the efficacy and safety of 2,2-dimethylbutyrate (HQK-1001), an oral fetal globin inducer, in sickle cell disease

This placebo-controlled phase II study evaluated the pharmacodynamics, efficacy and safety of 2,2-dimethylbutyrate (HQK-1001), a fetal globin gene-inducing short-chain fatty acid derivative, administered orally at 15 mg/kg twice daily for 48 weeks in 76 subjects with sickle cell disease (SCD). The median age was 26 years (range: 12-55 years) and 37 subjects (49%) were treated previously with hydroxycarbamide. Sixty subjects (79%) had Hb SS and 16 (21%) had S/β(0) thalassemia. The study was terminated after a planned interim analysis showed no significant increase in fetal hemoglobin (Hb F) and a trend for more pain crises in the HQK-1001 group. For 54 subjects with Week 24 data, the mean absolute increase in Hb F was 0.9% (95% confidence interval (CI): 0.1-1.6%) with HQK-1001 and 0.2% (95% CI: -0.7-1.1%) with placebo. Absolute increases in Hb F greater than 3% were noted in 9 of 38 subjects (24%) administered HQK-1001 and 1 of 38 subjects (3%) administered placebo. The mean changes in hemoglobin at Week 24 were comparable between the two groups. The mean annualized rate of pain crises was 3.5 with HQK-1001 and 1.7 with placebo. The most common adverse events in the HQK-1001 group, usually graded as mild or moderate, consisted of nausea, headache, vomiting, abdominal pain, and fatigue. Additional studies of HQK-1001 at this dose and schedule are not recommended in SCD. Intermittent HQK-1001 administration, rather than a daily regimen, may be better tolerated and more effective, as shown previously with arginine butyrate, and warrants further evaluation.

'Once I had money in my pocket, I was every colour under the sun': using 'appearance biographies' to explore the meanings of appearance for people with dementia

Appearance and the work invested in it by and for people with dementia are a neglected issue within dementia studies. In policy and practice there exists an assumption that the role of supporting a person to manage their appearance is easily assumed by another within caring encounters, only to be subsumed within the daily task-oriented provision of care. This paper reports on interviews conducted as part of the Hair and Care project, which explored questions of appearance and the meanings it holds with people with dementia. The research used 'appearance biographies', a method which allows for a range of topics to be considered about appearance throughout the life course, acting as a conduit for reminiscence and life story work. The paper reports on the key themes and findings from these interviews, discussing them in the context of a wider debate on dementia, self-expression and agency. A key question posed by the authors is whether appearance and the work invested in it are legitimate considerations for dementia care policy and practice. And if so, how should we make sense of this work and what significance should we attach to it? In seeking to answer these questions the authors position the perspectives and experiences of people with dementia as central to their analysis. A narrative framework is suggested as a useful basis on which to understand the work of managing appearance over the life course. The implications for policy and practice are outlined.

The histone chaperones Vps75 and Nap1 form ring-like, tetrameric structures in solution

NAP-1 fold histone chaperones play an important role in escorting histones to and from sites of nucleosome assembly and disassembly. The two NAP-1 fold histone chaperones in budding yeast, Vps75 and Nap1, have previously been crystalized in a characteristic homodimeric conformation. In this study, a combination of small angle X-ray scattering, multi angle light scattering and pulsed electron–electron double resonance approaches were used to show that both Vps75 and Nap1 adopt ring-shaped tetrameric conformations in solution. This suggests that the formation of homotetramers is a common feature of NAP-1 fold histone chaperones. The tetramerisation of NAP-1 fold histone chaperones may act to shield acidic surfaces in the absence of histone cargo thus providing a ‘self-chaperoning’ type mechanism.