Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes degradation of hepatic low density lipoprotein receptors (LDLR), the major route of clearance of circulating cholesterol. Gain-of-function mutations in PCSK9 cause hypercholesterolemia and premature atherosclerosis, whereas loss-of-function mutations result in hypocholesterolemia and protection from heart disease. Recombinant human PCSK9 binds the LDLR on the surface of cultured hepatocytes and promotes degradation of the receptor after internalization. Here we localized the site of binding of PCSK9 within the extracellular domain of the LDLR and determined the fate of the receptor after PCSK9 binding. Recombinant human PCSK9 interacted in a sequence-specific manner with the first epidermal growth factor-like repeat (EGF-A) in the EGF homology domain of the human LDLR. Similar binding specificity was observed between PCSK9 and purified EGF-A. Binding to EGF-A was calcium-dependent and increased dramatically with reduction in pH from 7 to 5.2. The addition of PCSK9, but not heat-inactivated PCSK9, to the medium of cultured hepatocytes resulted in redistribution of the receptor from the plasma membrane to lysosomes. These data are consistent with a model in which PCSK9 binding to EGF-A interferes with an aciddependent conformational change required for receptor recycling. As a consequence, the LDLR is rerouted from the endosome to the lysosome where it is degraded.Genetic variation in proprotein convertase subtilisin/kexin type 9 (PCSK9) 4 contributes to differences in plasma levels of low density lipoprotein (LDL) cholesterol (1, 2), the primary cholesterol-carrying lipoprotein in humans. Selected missense mutations in PCSK9 cause dominant hypercholesterolemia and premature atherosclerosis (1, 3, 4), whereas loss-of-function mutations in PCSK9 reduce plasma LDL levels and protect against coronary heart disease (5-7). Studies in mice suggest that the major metabolic effect of PCSK9 is to reduce the amount of hepatic LDL receptor (LDLR), the primary conduit for the clearance of LDL from the circulation (8). Expression of recombinant PCSK9 in the livers of mice causes a reduction in hepatic LDLR protein (but not mRNA) and produces severe hypercholesterolemia (9 -11). Conversely, mice lacking PCSK9 manifest increased levels of LDLR protein in the liver and accelerated clearance of circulating LDL (12). PCSK9 is expressed predominantly in the liver, small intestine, kidney, and brain (13) and is present in human plasma (14,15). Introduction of PCSK9 into the circulation of mice through parabiosis reduces hepatic LDLR levels, which is consistent with PCSK9 interacting with the LDLR on the cell surface (14). In cultured cells, the addition of recombinant PCSK9 to the medium results in LDLR degradation, providing further evidence that PCSK9 can promote the degradation of the LDLR by acting at the cell surface (14, 16). Autocatalytic cleavage is required for PCSK9 maturation and secretion (10), but whether the catalytic activity of PCSK9 is required for LDLR d...

IMPORTANCE Several national initiatives have emerged to empower laypersons to act as immediate responders to reduce preventable deaths from uncontrolled bleeding. Point-of-care instructional interventions have been developed in response to the scalability challenges associated with in-person training. However, to our knowledge, their effectiveness for hemorrhage control has not been established. OBJECTIVETo evaluate the effectiveness of different instructional point-of-care interventions and in-person training for hemorrhage control compared with no intervention and assess skill retention 3 to 9 months after hemorrhage control training. DESIGN, SETTING, AND PARTICIPANTS This randomized clinical trial of 465 laypersons was conducted at a professional sports stadium in Massachusetts with capacity for 66 000 people and assessed correct tourniquet application by using different point-of-care interventions (audio kits and flashcards) and a Bleeding Control Basic (B-Con) course. Non-B-Con arms received B-Con training after initial testing (conducted from April 2017 to August 2017). Retesting for 303 participants (65%) was performed 3 to 9 months after training (October 2017 to January 2018) to evaluate B-Con retention. A logistic regression for demographic associations was performed for retention testing. INTERVENTIONS Participants were randomized into 4 arms: instructional flashcards, audio kits with embedded flashcards, B-Con, and control. All participants received B-Con training to later assess retention.MAIN OUTCOMES AND MEASURES Correct tourniquet application in a simulated scenario. RESULTSOf the 465 participants, 189 (40.7%) were women and the mean (SD) age was 46.3 (16.1) years. For correct tourniquet application, B-Con (88% correct application [n = 122]; P < .001) was superior to control (n = 104 [16%]) while instructional flashcards (n = 117 [19.6%]) and audio kit (n = 122 [23%]) groups were not. More than half of participants in point-of-care arms did not use the educational prompts as intended. Of 303 participants (65%) who were assessed 3 to 9 months after undergoing B-Con training, 165 (54.5%) could correctly apply a tourniquet. Over this period, there was no further skill decay in the adjusted model that treated time as either linear (odds ratio [OR], 0.98; 95% CI, 0.95-1.03) or quadratic (OR, 1.00; 95% CI, 1.00-1.00). The only demographic that was associated with correct application at retention was age; adults aged 18 to 35 years (n = 58; OR, 2.39; 95% CI, 1.21-4.72) and aged 35 to 55 years (n = 107; OR, 1.77; 95% CI, 1.04-3.02) were more likely to be efficacious than those older than 55 years (n = 138). CONCLUSIONS AND RELEVANCEIn-person hemorrhage control training for laypersons is currently the most efficacious means of enabling bystanders to act to control hemorrhage. Laypersons can successfully perform tourniquet application after undergoing a 1-hour course. However, only 54.5% retain this skill after 3 to 9 months, suggesting that investigating refresher training or improved point-of-care instruc...

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ObjectivesTo map the existing literature and describe interventions aimed at building the capacity of patients to participate in care during hospitalisation by: (1) describing and categorising the aspects of care targeted by these interventions and (2) identifying the behaviour change techniques (BCTs) used in these interventions. A patient representative participated in all aspects of this project.DesignScoping review.Data sourcesMEDLINE, Embase and CINAHL (Inception −2017).Study selectionStudies reporting primary research studies on building the capacity of hospitalised adult patients to participate in care which described or included one or more structured or systematic interventions and described the outcomes for at least the key stakeholder group were included.Data extractionTitle and abstract screening and full text screening were conducted by pairs of trained reviewers. One reviewer extracted data, which were verified by a second reviewer. Interventions were classified according to seven aspects of care relevant to hospital settings. BCTs identified in the articles were assigned through consensus of three reviewers.ResultsDatabase searches yielded a total 9899 articles, resulting in 87 articles that met the inclusion criteria. Interventions directed at building patient capacity to participate in care while hospitalised were categorised as those related to improving: patient safety (20.9%); care coordination (5.7%); effective treatment (5.7%) and/or patient-centred care using: bedside nursing handovers (5.7%); communication (29.1%); care planning (14%) or the care environment (19.8%). The majority of studies reported one or more positive outcomes from the defined intervention. Adding new elements (objects) to the environment and restructuring the social and/or physical environment were the most frequently identified BCTs.ConclusionsThe majority of studies to build capacity for participation in care report one or more positive outcomes, although a more comprehensive analysis is warranted.