81 research outputs found
Understanding the molecular mechanisms underpinning the biological activity of antibodies against the inhibitory CD32b receptor
No full textFc gamma receptor (FcγR) IIB (CD32b) is the only inhibitory FcγR in humans and regulates the action of Immunoreceptor Tyrosine-based Activation Motif (ITAM) containing receptors such as the B cell receptor and activatory FcR. The inhibitory actions of CD32b are detrimental in a cancer immunotherapy setting, yet have the potential to regulate aberrant immune responses in autoimmune conditions, making CD32b an attractive target for immunotherapy. A panel of human anti-human CD32b monoclonal antibodies (mAb) were recently developed, capable of blocking IgG immune complex binding to the receptor. Although predicted to bind within a similar region of the receptor, opposing biological responses were observed with these mAb, with some activating the receptor (agonists) and others blocking CD32b phosphorylation and consequent activation (antagonists). This project aimed to identify the molecular mechanisms that determined the agonist or antagonist activity of these anti-CD32b mAb. Microscopy studies revealed that agonist but not antagonist antibodies induced clustering of CD32b, which was necessary for CD32b activation. The ability of the anti-CD32b mAb to cluster CD32b was therefore thought to drive the opposing biological responses observed and was proposed to derive from the subtle differences in epitopes engaged by the agonist and antagonist mAb. The crystal structure of an antagonist complex was not available, therefore small angle X-ray scattering studies were conducted to explore the basis behind the opposing biological responses of the anti-CD32b mAb. In solution, both agonist and antagonist F(ab) were observed to adopt similar conformations. In contrast, when F(ab) were in complex with the extracellular domain of CD32b, antagonist F(ab) appeared to form more elongated complexes with CD32b, showing a greater radius of gyration (Rg) and maximal dimension (Dmax), compared to agonist F(ab):CD32b complexes. Current crystal structures of the agonist 6G08 F(ab):CD32b complex showed poor agreement to the solution data, therefore molecular dynamics simulations were used to determine atomic structures of agonist 6G08 and an antagonist F(ab), 6G11, that agreed with SAXS data for the proteins in solution. The simulations confirmed previous observations from SAXS studies, that these proteins adopted similar conformations in solution. These methods in VI addition to metadynamics were further applied to the crystal structure of the 6G08 F(ab):CD32b complex and a homology model of the antagonist 6G11 F(ab):CD32b complex. The structures identified from these simulations revealed a difference in binding orientation between the agonist and antagonist F(ab), with the 6G11 F(ab) binding in an orientation which resulted in a more linear complex with CD32b in comparison to the 6G08 F(ab). When predicting the interactions of an IgG anti-CD32b mAb at the cell surface, the difference in binding orientation between the 6G08 and 6G11 F(ab) were proposed to result in the CD32b receptors coming in to close proximity when bound to 6G08 IgG, whereas 6G11 IgG was predicted to hold the receptors further apart in the cell membrane. Taken together, a model for determining the biological activity of the anti-CD32b was generated. The model proposes that binding orientation of the F(ab) determines the ability of the anti-CD32b to cluster CD32b in the cell membrane, and that the lower affinity of agonist mAb facilitates clustering of CD32b. In contrast, the extended binding geometry and higher affinity of the antagonist F(ab) results in receptors being held apart in the membrane with less potential for clustering. Further studies will continue to test this model in order to design increasingly effective agonist or antagonist antibodies for the treatment of autoimmunity or cancer, respectively.<br/
Evaluating anti-CD32b F(ab) conformation using molecular dynamics and small-angle X-ray scattering
No full textComplementary strategies of small-angle x-ray scattering (SAXS) and crystallographic analysis are often used to determine atomistic three-dimensional models of macromolecules and their variability in solution. This combination of techniques is particularly valuable when applied to macromolecular complexes to detect changes within the individual binding partners. Here, we determine the x-ray crystallographic structure of a F(ab) fragment in complex with CD32b, the only inhibitory Fc-γ receptor in humans, and compare the structure of the F(ab) from the crystal complex to SAXS data for the F(ab) alone in solution. We investigate changes in F(ab) structure by predicting theoretical scattering profiles for atomistic structures extracted from molecular dynamics (MD) simulations of the F(ab) and assessing the agreement of these structures to our experimental SAXS data. Through principal component analysis, we are able to extract principal motions observed during the MD trajectory and evaluate the influence of these motions on the agreement of structures to the F(ab) SAXS data. Changes in the F(ab) elbow angle were found to be important to reach agreement with the experimental data; however, further discrepancies were apparent between our F(ab) structure from the crystal complex and SAXS data. By analyzing multiple MD structures observed in similar regions of the principal component analysis, we were able to pinpoint these discrepancies to a specific loop region in the F(ab) heavy chain. This method, therefore, not only allows determination of global changes but also allows identification of localized motions important for determining the agreement between atomistic structures and SAXS data. In this particular case, the findings allowed us to discount the hypothesis that structural changes were induced upon complex formation, a significant find informing the drug development process. The methodology described here is generally applicable to deconvolute global and local changes of macromolecular structures and is well suited to other systems
Surgery for weight loss in adults
No full textBackground: bariatric (weight loss) surgery for obesity is considered when other treatments have failed. The effects of the available bariatric procedures compared with medical management and with each other are uncertain. This is an update of a Cochrane review first published in 2003 and most recently updated in 2009.Objectives: to assess the effects of bariatric surgery for overweight and obesity, including the control of comorbidities.Search methods: studies were obtained from searches of numerous databases, supplemented with searches of reference lists and consultation with experts in obesity research. Date of last search was November 2013.Selection criteria: randomised controlled trials (RCTs) comparing surgical interventions with non-surgical management of obesity or overweight or comparing different surgical procedures.Data collection and analysis: data were extracted by one review author and checked by a second review author. Two review authors independently assessed risk of bias and evaluated overall study quality utilising the GRADE instrument.Main results: twenty-two trials with 1798 participants were included; sample sizes ranged from 15 to 250. Most studies followed participants for 12, 24 or 36 months; the longest follow-up was 10 years. The risk of bias across all domains of most trials was uncertain; just one was judged to have adequate allocation concealment.All seven RCTs comparing surgery with non-surgical interventions found benefits of surgery on measures of weight change at one to two years follow-up. Improvements for some aspects of health-related quality of life (QoL) (two RCTs) and diabetes (five RCTs) were also found. The overall quality of the evidence was moderate. Five studies reported data on mortality, no deaths occurred. Serious adverse events (SAEs) were reported in four studies and ranged from 0% to 37% in the surgery groups and 0% to 25% in the no surgery groups. Between 2% and 13% of participants required reoperations in the five studies that reported these data.Three RCTs found that laparoscopic Roux-en-Y gastric bypass (L)(RYGB) achieved significantly greater weight loss and body mass index (BMI) reduction up to five years after surgery compared with laparoscopic adjustable gastric banding (LAGB). Mean end-of-study BMI was lower following LRYGB compared with LAGB: mean difference (MD) -5.2 kg/m² (95% confidence interval (CI) -6.4 to -4.0; P < 0.00001; 265 participants; 3 trials; moderate quality evidence). Evidence for QoL and comorbidities was very low quality. The LRGYB procedure resulted in greater duration of hospitalisation in two RCTs (4/3.1 versus 2/1.5 days) and a greater number of late major complications (26.1% versus 11.6%) in one RCT. In one RCT the LAGB required high rates of reoperation for band removal (9 patients, 40.9%).Open RYGB, LRYGB and laparoscopic sleeve gastrectomy (LSG) led to losses of weight and/or BMI but there was no consistent picture as to which procedure was better or worse in the seven included trials. MD was -0.2 kg/m² (95% CI -1.8 to 1.3); 353 participants; 6 trials; low quality evidence) in favour of LRYGB. No statistically significant differences in QoL were found (one RCT). Six RCTs reported mortality; one death occurred following LRYGB. SAEs were reported by one RCT and were higher in the LRYGB group (4.5%) than the LSG group (0.9%). Reoperations ranged from 6.7% to 24% in the LRYGB group and 3.3% to 34% in the LSG group. Effects on comorbidities, complications and additional surgical procedures were neutral, except gastro-oesophageal reflux disease improved following LRYGB (one RCT). One RCT of people with a BMI 25 to 35 and type 2 diabetes found laparoscopic mini-gastric bypass resulted in greater weight loss and improvement of diabetes compared with LSG, and had similar levels of complications.Two RCTs found that biliopancreatic diversion with duodenal switch (BDDS) resulted in greater weight loss than RYGB in morbidly obese patients. End-of-study mean BMI loss was greater following BDDS: MD -7.3 kg/m² (95% CI -9.3 to -5.4); P < 0.00001; 107 participants; 2 trials; moderate quality evidence). QoL was similar on most domains. In one study between 82% to 100% of participants with diabetes had a HbA1c of less than 5% three years after surgery. Reoperations were higher in the BDDS group (16.1% to 27.6%) than the LRYGB group (4.3% to 8.3%). One death occurred in the BDDS group.One RCT comparing laparoscopic duodenojejunal bypass with sleeve gastrectomy versus LRYGB found BMI, excess weight loss, and rates of remission of diabetes and hypertension were similar at 12 months follow-up (very low quality evidence). QoL, SAEs and reoperation rates were not reported. No deaths occurred in either group.One RCT comparing laparoscopic isolated sleeve gastrectomy (LISG) versus LAGB found greater improvement in weight-loss outcomes following LISG at three years follow-up (very low quality evidence). QoL, mortality and SAEs were not reported. Reoperations occurred in 20% of the LAGB group and in 10% of the LISG group.One RCT (unpublished) comparing laparoscopic gastric imbrication with LSG found no statistically significant difference in weight loss between groups (very low quality evidence). QoL and comorbidities were not reported. No deaths occurred. Two participants in the gastric imbrication group required reoperation.Authors' conclusions: surgery results in greater improvement in weight loss outcomes and weight associated comorbidities compared with non-surgical interventions, regardless of the type of procedures used. When compared with each other, certain procedures resulted in greater weight loss and improvements in comorbidities than others. Outcomes were similar between RYGB and sleeve gastrectomy, and both of these procedures had better outcomes than adjustable gastric banding. For people with very high BMI, biliopancreatic diversion with duodenal switch resulted in greater weight loss than RYGB. Duodenojejunal bypass with sleeve gastrectomy and laparoscopic RYGB had similar outcomes, however this is based on one small trial. Isolated sleeve gastrectomy led to better weight-loss outcomes than adjustable gastric banding after three years follow-up. This was based on one trial only. Weight-related outcomes were similar between laparoscopic gastric imbrication and laparoscopic sleeve gastrectomy in one trial. Across all studies adverse event rates and reoperation rates were generally poorly reported. Most trials followed participants for only one or two years, therefore the long-term effects of surgery remain unclear
A sojourn in Paris 1824-25: sex and sociability in the manuscript writings of Anne Lister (1791-1840)
No full textThis thesis examines the day to day practices that constituted Anne Lister's (1791-1840) sexuality and sociability within the range of her writings, as well as her society. Anne's writings were a detailed account, spanning her lifetime, of her own love and relationships with the 'fairer sex' (Whitbread 1988, 145). Anne's sociality, seen in her correspondence and plain handwritten journal entries, has been explored by Muriel Green in Miss Lister of Shibden Hall and Jill Liddington in Female Fortune and Nature's Domain (Green 1992; Liddington 1998; 2003). As a gentlewoman of adequate means, Anne has garnered some attention from women's historians interested in her agency within an early nineteenth century social and historical context. Anne's sexual identity has been extensively analysed over the past nearly twenty years by lesbian feminists, queer theorists, women's historians and historians of sexuality concerned with the history and development of modern Western female homosexuality and gender. The source for theorising Anne's sexuality has been the edited selections of the crypted journal entries, published by Helena Whitbread in I Know My Own Heart and No Priest but Love (Whitbread 1988; 1992). However, many analyses deal either with the theorisation of Anne's sexuality or her sociality; the theoretical difficulty with reconciling these categories has troubled the analysis of her complex subjectivity. Drawing upon the archival materials, I have used an interdisciplinary feminist approach to analyse the sexual and social processes of Anne's everyday interactions in her writings. Taking the seven month period of the sojourn to Paris in 1824-25, I have focused upon Anne's textual practices within her journal volume and letters during her residence in Paris, her social practices with the other guests at the guesthouse 24 Place Vendome and her sexual practices with her lover, the widow Mrs. Maria Barlow. The journal volumes and correspondence are a valuable historical record of one gentlewoman's engagement with early nineteenth century British culture
The cost-effectiveness of left ventricular assist devices in end stage heart failure
No full textWith a limited supply of donor hearts, individuals with end-stage heart failure have been offered hope through the use of mechanical devices. Left ventricular-assist devices (LVADs) are a technology designed to work in parallel with the heart but have yet to see widespread use since uncertainty remains as to the cost–effectiveness of this evolving new technology. We have systematically reviewed evidence of cost–effectiveness for LVADs in the bridge-to-transplant and long-term chronic support indications. A total of 18 studies reporting costs were identified. Of these, only four studies reported results in cost–effectiveness terms; two in cost per life-year saved and two in cost per quality-adjusted life-year (QALY). The majority of the other studies were simple cost summations (cost per day or incremental cost) without consideration of efficacy. In the bridge-to-transplant indication, a Danish abstract reported a cost per life-year saved of DKK270k (US78,000) and a Canadian study reported a cost per life-year saved of Can86,000). Regarding the long-term chronic support indication, the same Canadian study reported a cost per life-year saved of Can56,000), whereas a US study reported a cost per QALY of 59,000) per QALY, there is arguably stronger evidence to support the cost–effectiveness of LVAD technology for the long-term chronic support indication. However, the methodological quality of the majority of studies was poor, as was their generalizability, raising concerns over the reliability of these figures. With the limited and declining availability of donor hearts for transplantation, it appears that the future of this technology is in its use as long-term chronic support. Further analyses should be undertaken, particularly alongside randomized, controlled trials and utilizing second- and third-generation devices<br/
Contextualizing narrative theory: reading the politics of formal innovation in contemporary women's fiction
No full textTo ignore the strategies and structures through which stories are told, this thesis contends, is to neglect a vital dimension of their politics. Narratology provides productive analytical tools to illuminate the complex and varied mechanics of narrative form, yet it also bears the traces of its structuralist origins. Its value is therefore contingent upon its continuing reformulation as an expansive, pluralist and contextualized critical discipline. Participating in this expansion, this
thesis evidences the pertinence and vitality of some narratological models and the limitations of others. It opens up alternative critical possibilities by drawing upon insights within contemporary critical theory, from poststructuralist philosophy to transcultural feminism to
sociolinguistics. Above all, my interventions proceed from close readings of innovative fiction by women writers hitherto all but unrepresented in, and therefore potentially subversive of, existing models: Nicole Brossard, Daphne Marlatt, Hiromi Goto, Ali Smith, Jackie Kay, Erna Brodber, Dionne Brand, Aritha van Herk.
The first chapter formulates an in-between critical space where feminist and postmodernist theories of narrative intersect. It re-examines metafiction through the lens of auto(bio)graphical practice and feminist poststructuralist theories of self, and introduces the notions of folds and
echoes to describe specific structural innovations. Chapter Two examines unconventional uses of second-person address and reconsiders existing narratological approaches in their light, focusing on the `push and pull of narrative' that the `you' form enacts. Chapter Three addresses the insufficient attention paid to multiply narrated novels, theorizing them as `narrative communities' and introducing terms to describe different internal relations between narrators, relations that can often be read as determinedly 'democratic'. The final chapter contests the
hegemony of temporal models of narrativity by formulating a 'spatial poetics' that accounts both for how spatial structures can be agents of narrative change and for the complexity of textual constructions of space, which frequently exceed static definitions of 'setting'.
Running throughout is a reconception of narrative as located not with the figure of the narrator, but in relations of intersubjectivity. The narratological criticism formulated here works towards a situated ethics of reading responsive to the politics of writing: it is engaged, relational, and ever in process
Moderate exercise as a preventative factor for depression, anxiety, and self-deprecation
No full textIncludes bibliographical references (pages 30-35)Results from several studies have shown moderate amounts of exercise to be beneficial in reducing symptoms of depression and anxiety. However, no study to the author???s knowledge has looked at whether exercise can be successful in preventing anxiety or depression. Based on previous research, I hypothesized the following: there will be a curvilinear relationship between amount of exercise and measures of anxiety and depression. As amount of exercise increases to a moderate level, anxiety and depression will decrease. If exercise is in excess, depression and anxiety will increase. Participants were 251 undergraduate students enrolled in lower-division psychology classes at California State University Northridge instructed to fill out surveys that related to their exercise habits and well-being. Exercise habits served as the predictor, and scores on the Beck Anxiety Inventory, the Center for Epidemiological Scale-Depression, and the Self-Deprecation Scale (part of the Rosenberg Self-Esteem Scale) served as the predicted factors. A confirmatory factor analysis revealed that exercise did not significantly predict anxiety, depression, and self-deprecation. However, Spearman???s rho correlations revealed significantly strong negative correlations between exercise habits and anxiety, depression, and self-deprecation. Limitations of the current study include the use of self-report measures and self-selection. Mental health professionals may use these results and incorporate exercise into treatment plans. Future studies should consider including an experimental design and using participants with known exercise habits. In addition, future studies should explore exercise and how it relates to drug addiction.\ud
Keywords: depression, exercise, anxiety, self-deprecation, serotoni
The 'true use of reading' : Sarah Fielding and mid eighteenth-century literary strategies.
No full textPhDThe aim of this thesis is to explore, by examining her life and
works, how Sarah Fielding (1710-68) established her identity as an author.
The definition of her role involves her notions of the functions of
writing and reading.
Sarah Fielding attempts to invite readers to form a sense of ties
by tacit understanding of her messages. As she believes that a work
of literature is produced through collaboration between the writer and
the reader, it is an important task in her view to show her attentiveness
toward reading practice. In her consideration of reading, she has two
distinct, even opposite views of her audience: on the one hand a familiar
and limited circle of readers with shared moral and cultural values and
on the other potential readers among the unknown mass of people. The
dual targets direct her to devise various strategies. She tries to
appeal to those who can endorse and appreciate her moral values as well
as her learning. Her writings and letters testify that she is sensitive
to the demands of the literary market, trying to lead the taste of readers
by inventing new forms.
The thesis opens with an overview of Sarah Fielding's career,
followed by a consideration of her critical attention to the roles of
reading. I go on to examine the narrative structures and strategies
she deploys, with a particular emphasis on her use of the epistolary
method. The following chapter deals with her attention to the reading
of the moral message tangibly embodied in her educational writing. It
is followed by an analysis of the activity which earned her a reputation
as a learned woman. Various as the forms of her works are, they invariably
reflect her attempt to balance herself between the two demands of
inventiveness and familiarity
Manuscript with author details – lessons learnt: imposters in online focus groups
No full textResearch using online platforms and recruitment via social media allows for a diverse range of participants and increased geographical reach. This, however, risks non-genuine participants, also known as ‘imposter participants,’ entering a study undetected. This commentary discusses our experiences with imposter participants in a recent focus group study. The study involved parents of young children with a speech sound disorder, looking at their experiences and perceptions of attending speech and language therapy and practising at home with their child. Ensuring participants are genuine is a complex issue that requires learning and discussion amongst researchers. It is essential that measures such as screening calls are put in place and considered in the design phase of studies to stop imposters entering. We urge those supporting research, as well as those training researchers, to make sure they have the relevant information, policies and procedures in place to prevent researchers from recruiting imposters
Sarah Fielding: Satire and Subversion in the Eighteenth-Century Novel
No full textThis study of Sarah Fielding (1710―68) is an original contribution to Fielding scholarship that has a dual purpose: to support those who are striving to re-introduce her to the modern literary landscape in an effort to restore her eighteenth-century literary standing, and to firmly establish Fielding as an early feminist writer. It is argued here that throughout her oeuvre Fielding challenged prevailing traditions that denied women a choice, particularly in education, employment and marriage. These themes are also considered in the political treatises of Mary Astell (1666―1731) and Mary Wollstonecraft (1759―97), who are now widely recognised as feminist writers.
It is further argued that Fielding’s subversion in fiction of the English patriarchal system is underscored by her unorthodox performance in the literary arena. This is fully explored alongside her use of sentimentalism as a literary tool with which she challenges her seemingly inhumane society. Fielding’s interest in ‘the Labyrinths of the Mind’ (in modern terms, human psychology) will also be addressed as will her placement in the history of feminism and her placement in the sentimental novel tradition. Fielding’s performance as a literary critic will be compared with the few female authors who, like her, dared to publish literary criticism during her writing career. Accordingly, extracts from Fielding’s novels and her two critical pamphlets will be thoroughly examined.
An updated biography of Fielding that is also included here will provide evidence for a further claim, that her fiction is autobiographical in part. A comprehensive account of Fielding’s performance as a literary critic forms the final chapter of this work. It is the first full-length examination of her contribution to the genre and includes an appraisal of her recently unearthed critical pamphlet entitled A Comparison Between the Horace of Corneille and The Roman Father of Mr. Whitehead (1750) that is yet to be formerly attributed to her. Ultimately this study of Fielding will go far beyond what has previously been written about this remarkable eighteenth-century author, particularly regarding her feminist activity
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