Distinct changes in glycogen synthase kinase-3 (GSK-3) signalling can regulate neuronal morphogenesis including the determination and maintenance of axonal identity, and are required for neurotrophin-mediated axon elongation. In addition, we have previously shown a dependency on GSK-3 activation in the semaphorin 3A (Sema3A)-mediated growth-cone-collapse response of sensory neurons. Regulation of GSK-3 activity involves the intermediate signalling lipid phosphatidylinositol 3,4,5-trisphosphate, which can be modulated by phosphatidylinositol 3-kinase (PI3K) and the tumour suppressor PTEN. We report here the involvement of PTEN in the Sema3A-mediated growth cone collapse. Sema3A suppresses PI3K signalling concomitant with the activation of GSK-3, which depends on the phosphatase activity of PTEN. PTEN is highly enriched in the axonal compartment and the central domain of sensory growth cones during axonal extension, where it colocalises with microtubules. Following exposure to Sema3A, PTEN accumulates rapidly at the growth cone membrane suggesting a mechanism by which PTEN couples Sema3A signalling to growth cone collapse. These findings demonstrate a dependency on PTEN to regulate GSK-3 signalling in response to Sema3A and highlight the importance of subcellular distributions of PTEN to control growth cone behaviour.

The regeneration kinetics of the integral membrane protein bacteriorhodopsin have been investigated in a lipid-based refolding system. Previous studies on bacteriorhodopsin regeneration have involved detergent-based systems, and in particular mixed dimyristoylphosphatidylcholine (DMPC)/CHAPS micelles. Here, we show that the short chain lipid dihexanoylphosphatidylcholine (DHPC) can be substituted for the detergent CHAPS and that bacteriorhodopsin can be regenerated to high yield in mixed DMPC/DHPC micelles. Bacteriorhodopsin refolding kinetics are measured in the mixed DMPC/DHPC micelles. Rapid, stopped flow mixing is employed to initiate refolding of denatured bacterioopsin in SDS micelles with mixed DMPC/DHPC micelles and time-resolved fluorescence spectroscopy to follow changes in protein fluorescence during folding. Essentially identical refolding kinetics are observed for mixed DMPC/CHAPS and mixed DMPC/DHPC micelles. Only one second-order retinal/apoprotein reaction is identified, in which retinal binds to a partially folded apoprotein intermediate, and the free energy of this retinal binding reaction is found to be the same in both types of mixed micelles. Formation of the partially folded apoproptein intermediate is a rate-limiting step in protein folding and appears to be biexponential. Both apparent rate constants are found to be dependent on the relative proportion of DMPC present in the mixed DMPC/DHPC micelles as well as on the pH of the aqueous phase. Increasing the DMPC concentration should increase the bending rigidity of the amphiphilic bilayer, and this is found to slow the rate of formation of the partially folded apoprotein intermediate. Increasing the mole fraction of DMPC from 0.3 to 0.6 slows the two apparent rate constants associated with formation of this intermediate from 0.29 and 0.031 to 0.11 and 0.013 s -1, respectively. Formation of the intermediate also slows with increasing pH, from 0.11 and 0.013 s-1 at pH 6 to 0.033 and 0.0053 s-1 at pH 8. Since this pH change has no known effect on the phase behavior of lecithins, this is more likely to represent a direct effect on the protein itself. Thus, it appears to be possible to control the rate-limiting process in bacterioopsin folding through both bilayer bending rigidity and pH.

Ligand-dependent structural changes in serum albumin are suggested to underlie its role in physiological solute transport and receptor-mediated cellular selection. Evidence of ligand-induced (oleic acid) structural changes in serum albumin are shown in both time-resolved and steady-state fluorescence quenching and anisotropy measurements of tryptophan 214 (Trp214). These studies were augmented with column chromatography separations. It was found that both the steady-state and time-resolved Stern-Volmer collisional quenching studies of Trp214 with acrylamide pointed to the existence of an oleate-dependent structural transformation. The bimolecular quenching rate constant of defatted human serum albumin, 1.96 x 10(9) M-1 s-1, decreased to 0.94 x 10(9) M-1 s-1 after incubation with oleic acid (9:1). Furthermore, Stern-Volmer quenching studies following fractionation of the structural forms by hydrophobic interaction chromatography were in accordance with this interpretation. Time-resolved fluorescence anisotropy measurements of the Trp214 residue yielded information of motion within the protein together with the whole protein molecule. Characteristic changes in these motions were observed after the binding of oleate to albumin. The addition of oleate was accompanied by an increase in the rotational diffusion time of the albumin molecule from approximately 22 to 33.6 ns. Within the body of the protein, however, the rotational diffusion time for Trp214 exhibited a slight decrease from 191 to 182 ps and was accompanied by a decrease in the extent of the angular motion of Trp214, indicating a transition after oleate binding to a more spatially restricted but less viscous environment.

A recent (2016) Office for National Statistics report stated that dementia is now 'the leading cause of death' in England and Wales. Ever fixated with the syndrome (an unfailingly newsworthy topic), the British press was quick to respond to the bulletin, consistently headlining that dementia was the nation's 'biggest killer', while (re)formulating other aspects of the report in distorting and emotive metaphorical terms. In this paper we examine how the media, through use of a recurring set of linguistic and visual semiotic tropes, portrayed dementia as an agentive entity, a 'killer', which remorselessly attacks its 'victims'. Such a broadly loaded and sensationalist representation, we argue, not only construed dementia as a direful and pernicious disease, but also, crucially, obscured the personal and social contexts in which the syndrome is understood and experienced (not least by people with dementia themselves). This intensely lurid type of representation not only fails to address the ageist misinformation and common misunderstandings that all too commonly surround dementia, but is also likely to exacerbate the stress and depression frequently experienced by people with dementia and their families.

ObjectivesComprehensive geriatric assessment (CGA) may be a way to deliver optimal care for care home residents. We used realist review to develop a theory-driven account of how CGA works in care homes.DesignRealist review.SettingCare homes.MethodsThe review had three stages: first, interviews with expert stakeholders and scoping of the literature to develop programme theories for CGA; second, iterative searches with structured retrieval and extraction of the literature; third, synthesis to refine the programme theory of how CGA works in care homes.We used the following databases: Medline, CINAHL, Scopus, PsychInfo, PubMed, Google Scholar, Greylit, Cochrane Library and Joanna Briggs Institute.Results130 articles informed a programme theory which suggested CGA had three main components: structured comprehensive assessment, developing a care plan and working towards patient-centred goals. Each of these required engagement of a multidisciplinary team (MDT). Most evidence was available around assessment, with tension between structured assessment led by a single professional and less structured assessment involving multiple members of an MDT. Care planning needed to accommodate visiting clinicians and there was evidence that a core MDT often used care planning as a mechanism to seek external specialist support. Goal-setting processes were not always sufficiently patient-centred and did not always accommodate the views of care home staff. Studies reported improved outcomes from CGA affecting resident satisfaction, prescribing, healthcare resource use and objective measures of quality of care.ConclusionThe programme theory described here provides a framework for understanding how CGA could be effective in care homes. It will be of use to teams developing, implementing or auditing CGA in care homes. All three components are required to make CGA work—this may explain why attempts to implement CGA by interventions focused solely on assessment or care planning have failed in some long-term care settings.Trial registration numberCRD42017062601.