Knockout of syntaxin-4 in 3T3-L1 adipocytes reveals new insight into GLUT4 trafficking and adiponectin secretion.

Adipocytes are key to metabolic regulation, exhibiting insulin-stimulated glucose transport that is underpinned by the insulin-stimulated delivery of glucose transporter type 4 (SLC2A4, also known and hereafter referred to as GLUT4)-containing vesicles to the plasma membrane where they dock and fuse, and increase cell surface GLUT4 levels. Adipocytokines, such as adiponectin, are secreted via a similar mechanism. We used genome editing to knock out syntaxin-4, a protein reported to mediate fusion between GLUT4-containing vesicles and the plasma membrane in 3T3-L1 adipocytes. Syntaxin-4 knockout reduced insulin-stimulated glucose transport and adiponectin secretion by ∼50% and reduced GLUT4 levels. Ectopic expression of haemagglutinin (HA)-tagged GLUT4 conjugated to GFP showed that syntaxin-4-knockout cells retain significant GLUT4 translocation capacity, demonstrating that syntaxin-4 is dispensable for insulin-stimulated GLUT4 translocation. Analysis of recycling kinetics revealed only a modest reduction in the exocytic rate of GLUT4 in knockout cells, and little effect on endocytosis. These analyses demonstrate that syntaxin-4 is not always rate limiting for GLUT4 delivery to the cell surface. In sum, we show that syntaxin-4 knockout results in reduced insulin-stimulated glucose transport, depletion of cellular GLUT4 levels and inhibition of adiponectin secretion but has only modest effects on the translocation capacity of the cells. This article has an associated First Person interview with Hannah L. Black and Rachel Livingstone, joint first authors of the paper.

Distributed cognition: Theoretical insights and practical applications to health professions education: AMEE Guide No. 159.

Distributed cognition (DCog) is a member of the family of situativity theories that widens the lens of cognition from occurring solely inside the head to being socially, materially and temporally distributed within a dynamic system. The concept of extending the view of cognition to outside the head of a single health professional is relatively new in the healthcare system. DCog has been increasingly used by researchers to describe many ways in which health professionals perform in teams within structured clinical environments to deliver healthcare for patients. In this Guide, we expound ten central tenets of the macro (grand) theory of DCog (1. Cognition is decentralized in a system; 2. The unit of analysis is the system; 3. Cognitive processes are distributed; 4. Cognitive processes emerge from interactions; 5. Cognitive processes are interdependent; 6. Social organization is a cognitive architecture; 7. Division of labour; 8. Social organization is a system of communication; 9. Buffering and filtering; 10. Cognitive processes are encultured) to provide theoretical insights as well as practical applications to the field of health professions education.

Virtual Wards: A Rapid Adaptation to Clinical Attachments in MBChB During the COVID-19 Pandemic.

When the COVID-19 pandemic suddenly prevented medical students from attending their clinical attachments, the faculty involved in the third year of medical school (MBChB3) at the University of Glasgow created Virtual Wards. The focus of the Virtual Wards was to continue teaching of clinical reasoning remotely whilst COVID-19 restrictions were in place. Virtual Wards were mapped to the common and important presentations and conditions and provided opportunity for history-taking, clinical examination skills, requesting investigations, interpreting results, diagnosis and management. The Virtual Wards were successful, and further wards were developed the following academic year for MBChB4 students. This chapter describes the theoretical underpinnings of the Virtual Wards and the technological considerations, followed by a description of the Wards themselves. We then analyse an evaluation of the Virtual Wards and provide both a faculty and student perspective. Throughout the chapter, we provide tips for educators developing Virtual Ward environments.

Sharing the Bandwidth in Cognitively Overloaded Teams and Systems: Mechanistic Insights from a Walk on the Wild Side of Clinical Reasoning.

IssuePrevious work from the diagnostic error literature has provided indirect evidence that faulty clinical reasoning may be the most frequent cause of error when attaching a diagnostic label. The precise mechanisms underlying diagnostic error are unclear and continue to be subject to considerable theory informed debate in the clinical reasoning literature. Evidence: We take a theoretical approach to merging these two worlds of literature by first zooming out using distributed cognition as a social cognitive lens (macro theory) to develop a view of the process and outcome of clinical reasoning occurring in the wild - defined as the integrated clinical workplace - the natural habitat of clinicians working within teams. We then zoom in using the novel combination of cognitive load theory and distributed cognition to provide additional theoretical insights into the potential mechanisms of error. Implications: Through the lenses of distributed cognition and cognitive load theory, we can begin to prospectively investigate how cognitive overload is represented and shared within interprofessional teams over time and space and how this influences clinical reasoning performance and leads to error. We believe that this work will help teams manage cognitive load and prevent error.

Metformin and carotid intima-media thickness in never-smokers with type 1 diabetes: The REMOVAL trial.

AIM: To determine whether metformin's effects on carotid artery intima-media thickness (cIMT) in type 1 diabetes differ according to smoking status. METHODS: Regression model effect estimates for the effect of metformin versus placebo (double-blind) on carotid IMT were calculated as a subgroup analysis of the REMOVAL trial. RESULTS: In 428 randomized participants (227 never-smokers, 201 ever-smokers), averaged mean carotid IMT progression (per year) was reduced by metformin versus placebo in never-smokers (-0.012 mm, 95% CI -0.021 to -0.002; p = .0137) but not in ever-smokers (0.003 mm, 95% CI -0.008 to 0.014; p = .5767); and similarly in non-current smokers (-0.008 mm, 95% CI -0.015 to -0.00001; p = .0497) but not in current smokers (0.013 mm, 95% CI -0.007 to 0.032; p = .1887). Three-way interaction terms (treatment*time*smoking status) were significant for never versus ever smoking (p = .0373, prespecified) and non-current versus current smoking (p = .0496, exploratory). Averaged maximal carotid IMT progression (per year) was reduced by metformin versus placebo in never-smokers (-0.020 mm, 95% CI -0.034 to -0.006; p = .0067) but not in ever-smokers (-0.006 mm, 95% CI -0.020 to 0.008; p = .4067), although this analysis was not supported by a significant three-way interaction term. CONCLUSIONS: This subgroup analysis of the REMOVAL trial provides additional support for a potentially wider role of adjunct metformin therapy in cardiovascular risk management in type 1 diabetes, particularly for individuals who have never smoked cigarettes.

Time in Range as a Research Outcome Measure.

Time in range (TIR) is gaining ground as an outcome measure in type 1 diabetes trials. However, inclusion of TIR raises several issues for trial design. In this article, the authors begin by defining TIR and describing the current international consensus around TIR targets. They then expand on evidence for the validity of TIR as a primary clinical trial outcome before concluding with some practical, ethical, and logistical implications.

Cardiovascular benefits of GLP-1 agonists in type 2 diabetes: a comparative review.

Type 2 diabetes (T2D) carries risks of both cardiovascular (CV) (myocardial infarction, stroke, and peripheral vascular disease) and microvascular (retinopathy/nephropathy/neuropathy) complications. Glucose-lowering is an effective strategy for preventing microvascular complications, but the extent to which it can reduce CV complications is less certain. Glucagon-like peptide-1 (GLP-1) agonists are potent glucose-lowering agents but also have potentially beneficial effects on other traditional (body weight, blood pressure (BP), and LDL cholesterol) and non-traditional risk factors (low grade inflammation and endothelial dysfunction). The results of four large CV outcome trials with GLP-1 agonists are now available. These have compared lixisenatide (ELIXA), liraglutide (LEADER), semaglutide (SUSTAIN-6), and long-acting exenatide (EXSCEL) with placebo and standard of care over 2-4 years; four others (including with dulaglutide and albiglutide) are ongoing. LEADER and SUSTAIN-6 have demonstrated reductions in rates of major adverse CV events with active GLP-1 treatment but ELIXA and EXSCEL have not. In this review, we discuss the mechanisms by which GLP-1 receptor agonists act on the CV system and the design and conduct of these trials. Contrary to the assertions that (a) all GLP-1 agonists reduce CV disease in T2D but to different extents or (b) the magnitude of CV protection is predominantly related to glucose-lowering, we argue that CV benefit is specific to agents that provide longer acting agonism at the GLP-1 receptor. The mechanisms involve reduction in body weight and BP, and lowering of LDL-cholesterol and glucose, but pleiotropic effects-including suppression of low grade inflammation, vasodilation, and natriuresis-are also likely relevant.

A new perspective on metformin therapy in type 1 diabetes.

Metformin is quite frequently used off-label in type 1 diabetes to limit insulin dose requirement. Guidelines recommend that it can improve glucose control in those who are overweight and obese but evidence in support of this is limited. Recently-published findings from the REducing with MetfOrmin Vascular Adverse Lesions (REMOVAL) trial suggest that metformin therapy in type 1 diabetes can reduce atherosclerosis progression, weight and LDL-cholesterol levels. This provides a new perspective on metformin therapy in type 1 diabetes and suggests a potential role for reducing the long-term risk of cardiovascular disease.

The impact of the time of day on metabolic responses to exercise in adults: A systematic and meta-analysis review.

The aim of the current study is to investigate whether the time of day at which exercise is performed affects metabolic, glucose and insulin responses to exercise in adults. Databases were searched for randomised controlled (parallel and crossover) trials with participants aged from 18 to 65 year, an intervention of any exercise carried out at a specific time of the day and compared to any exercise carried out at a different time of the day. From 2458 screened articles, 12 studies were included in the systematic review of which 5 studies were included in the meta-analyses which compared 24 h continuous glucose monitoring (CGM) data, between morning and afternoon/evening exercise, on the day exercise was performed (SMD = 0.12 [-0.22-0.46] p = 0.76) and the day after exercise (SMD = -0.02 [-0.36-0.33] p = 0.94. Similar findings were observed in the wider systematic review with a general unclear risk of bias and a low certainty in these data. The results indicate that there is no clear effect of the time of the day on metabolic responses to exercise and exercise at any time of day should be the goal of public health strategies.

Reframing context specificity in team diagnosis using the theory of distributed cognition.

Context specificity refers to the vexing phenomenon whereby a physician can see two patients with the same presenting complaint, identical history and physical examination findings, but due to specific situational (contextual) factors arrives at two different diagnostic labels. Context specificity remains incompletely understood and undoubtedly leads to unwanted variance in diagnostic outcomes. Previous empirical work has demonstrated that a variety of contextual factors impacts clinical reasoning. These findings, however, have largely focused on the individual clinician; here we broaden this work to reframe context specificity in relation to clinical reasoning by an internal medicine rounding team through the lens of Distributed Cognition (DCog). In this model, we see how meaning is distributed amongst the different members of a rounding team in a dynamic fashion that evolves over time. We describe four different ways in which context specificity plays out differently in team-based clinical care than for a single clinician. While we use examples from internal medicine, we believe that the concepts we present apply equally to other specialties and fields in health care.

New approach to undergraduate quality improvement.

BACKGROUND: While quality improvement (QI) is an essential component to modern day clinical practice, some foundation doctors fail to engage. This is compounded by a lack of formalised undergraduate QI teaching. We trial an undergraduate active learning workshop and evaluate it using a concurrent triangulation mixed methods design. APPROACH: We constructed a 2-hour interactive QI workshop utilising near-peer educators for third year undergraduate medical students. Our workshop demonstrated an exemplary project and a template featuring evidenced-based QI tools to grasp key concepts. Informal support was provided for student QI projects, undertaken in small peer groups. Utility was assessed using linked pre-and-post event questionnaires with Likert scales, free text thematic analysis and project completion rates. EVALUATION: We recruited 74 students to attend our workshops delivered over 3 months. We achieved high event satisfaction and significant improvements on baseline confidence. Free text comments suggested students perceive QI as an important part of the undergraduate curriculum, described barriers to engagement and the value they place on project autonomy. The workshop eased student feelings of anxiety and intimidation regarding change ideas. Nine projects were completed with one winning a poster prize at a regional conference. IMPLICATIONS: We demonstrate a popular resource light model that can be scaled up to a variety of centres. Targeting QI teaching at the undergraduate level may be instrumental in developing QI culture in health care systems and address barriers to postgraduate involvement. Our study furthers the understanding of undergraduate students' perspectives of QI and demand for further sessions.

Phosphorylation of Syntaxin 4 by the Insulin Receptor Drives Exocytic SNARE Complex Formation to Deliver GLUT4 to the Cell Surface.

A major consequence of insulin binding its receptor on fat and muscle cells is the stimulation of glucose transport into these tissues. This is achieved through an increase in the exocytic trafficking rate of the facilitative glucose transporter GLUT4 from intracellular stores to the cell surface. Delivery of GLUT4 to the cell surface requires the formation of functional SNARE complexes containing Syntaxin 4, SNAP23, and VAMP2. Insulin stimulates the formation of these complexes and concomitantly causes phosphorylation of Syntaxin 4. Here, we use a combination of biochemistry and cell biological approaches to provide a mechanistic link between these observations. We present data to support the hypothesis that Tyr-115 and Tyr-251 of Syntaxin 4 are direct substrates of activated insulin receptors, and that these residues modulate the protein's conformation and thus regulate the rate at which Syntaxin 4 forms SNARE complexes that deliver GLUT4 to the cell surface. This report provides molecular details on how the cell regulates SNARE-mediated membrane traffic in response to an external stimulus.

Recent developments in adjunct therapies for type 1 diabetes.

INTRODUCTION: There have been many recent advances in the treatment of type 1 diabetes (T1D) including in insulin formulations, continuous glucose monitoring (CGM) technology and automated insulin delivery. However, long-term optimal glycemic control is still only achieved in a minority. AREAS COVERED: Adjunct therapy - the use of therapeutic agents other than insulin - is one strategy aimed at improving outcomes. An ideal adjunct agent would improve glycemic control, reduce weight (or weight gain), reduce insulin requirement and prevent complications (e.g. cardiorenal) without increasing hypoglycemia. The amylin analogue pramlintide has been licensed in the USA, while the sodium glucose co-transporter-2 inhibitor (SGLT2i) dapagliflozin, was briefly (2019 - 2021) licensed for type 1 diabetes in Europe and the UK. However, other agents from the type 2 diabetes (T2D) arena including metformin, other SGLT2is, glucagon-like peptide-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-IV (DPP-4) inhibitors have been investigated. EXPERT OPINION: As evidence emerges for cardiorenal protection by SGLT2is and GLP-1RAs in T2D, it has become increasingly important to know whether people with T1D can also benefit. Here, we review recent trials of adjunct agents in T1D and discuss the efficacy and safety of these agents (alone and in combination) in an era in which continuous glucose monitoring is becoming standard of care.

Diabetes is accompanied by changes in the levels of proteins involved in endosomal GLUT4 trafficking in obese human skeletal muscle.

INTRODUCTION: The regulated delivery of the glucose transporter GLUT4 from intracellular stores to the plasma membrane underpins insulin-stimulated glucose transport. Insulin-stimulated glucose transport is impaired in skeletal muscle of patients with type-2 diabetes, and this may arise because of impaired intracellular trafficking of GLUT4. However, molecular details of any such impairment have not been described. We hypothesized that GLUT4 and/or levels of proteins involved in intracellular GLUT4 trafficking may be impaired in skeletal muscle in type-2 diabetes and tested this in obese individuals without and without type-2 diabetes. METHODS: We recruited 12 participants with type-2 diabetes and 12 control participants. All were overweight or obese with BMI of 25-45 kg/m2 . Insulin sensitivity was measured using an insulin suppression test (IST), and vastus lateralis biopsies were taken in the fasted state. Cell extracts were immunoblotted to quantify levels of a range of proteins known to be involved in intracellular GLUT4 trafficking. RESULTS: Obese participants with type-2 diabetes exhibited elevated fasting blood glucose and increased steady state glucose infusion rates in the IST compared with controls. Consistent with this, skeletal muscle from those with type-2 diabetes expressed lower levels of GLUT4 (30%, p = .014). Levels of Syntaxin4, a key protein involved in GLUT4 vesicle fusion with the plasma membrane, were similar between groups. By contrast, we observed reductions in levels of Syntaxin16 (33.7%, p = 0.05), Sortilin (44%, p = .006) and Sorting Nexin-1 (21.5%, p = .039) and -27 (60%, p = .001), key proteins involved in the intracellular sorting of GLUT4, in participants with type-2 diabetes. CONCLUSIONS: We report significant reductions of proteins involved in the endosomal trafficking of GLUT4 in skeletal muscle in obese people with type 2 diabetes compared with age- and weight-matched controls. These abnormalities of intracellular GLUT4 trafficking may contribute to reduced whole body insulin sensitivity.

Increasing Collaborative Discussion in Case-Based Learning Improves Student Engagement and Knowledge Acquisition.

Background: In the transition from academic to clinical learning, the development of clinical reasoning skills and teamwork is essential, but not easily achieved by didactic teaching only. Case-based learning (CBL) was designed to stimulate discussions of genuine clinical cases and diagnoses but in our initial format (CBL'10) remained predominantly tutor-driven rather than student-directed. However, interactive teaching methods stimulate deep learning and consolidate taught material, and we therefore introduced a more collaborative CBL (cCBL), featuring a structured format with discussions in small breakout groups. This aimed to increase student participation and improve learning outcomes. Method: A survey with open and closed questions was distributed among 149 students and 36 tutors that had participated in sessions of both CBL formats. A statistical analysis compared exam scores of topics taught via CBL'10 and cCBL. Results: Students and tutors both evaluated the switch to cCBL positively, reporting that it increased student participation and enhanced consolidation and integration of the wider subject area. They also reported that the cCBL sessions increased constructive discussion and stimulated deep learning. Moreover, tutors found the more structured cCBL sessions easier to facilitate. Analysis of exam results showed that summative assessment scores of subjects switched to cCBL significantly increased compared to previous years, whereas scores of subjects that remained taught as CBL'10 did not change. Conclusions: Compared to our initial, tutor-led CBL format, cCBL resulted in improved educational outcomes, leading to increased participation, confidence, discussion and higher exam scores.

Improving the quality of weekend medical handover on non-receiving medical hospital wards.

INTRODUCTION: Handover is the system by which the responsibility for immediate and ongoing care is transferred between healthcare professionals and can be an area of risk. The Royal College of Physicians (RCP) has recommended improvement and standardisation of handover. Locally, national training surveys have reported poor feedback regarding handover at Glasgow Royal Infirmary. AIM: To improve and standardise handover from weekday to weekend teams. METHODS: The Plan-Do-Study-Act (PDSA) quality improvement framework was used. Interventions were derived from a driver diagram after consultation with relevant stakeholders. Four PDSA cycles were completed over a 4-month period:PDSA cycle 1-Introduction of standardised paper form on three wards.PDSA cycle 2-Introduction of electronic handover system on three wards.PDSA cycle 3-Expansion of electronic handover to seven wards.PDSA cycle 4-Expansion of electronic handover to all non-receiving medical wards.The outcome of interest was the percentage of patients with full information handed over based on a six-point scale derived from the RCP. Data were collected weekly throughout the study period. RESULTS: 18 data collection exercises were performed including 525 patients. During the initial phase there was an improvement in handover quality with 0/28 (0%) at baseline having all six points completed compared with 13/48 (27%) with standardised paper form and 21/42 (50%) with the electronic system (p<0.001). When the electronic handover form was expanded to all wards, the increased quality was maintained, however, to a lesser extent compared with the initial wards. CONCLUSION: A standardised electronic handover system was successfully introduced to downstream medical wards over a short time period. This led to an in improvement in the quality of handover in the initial wards involved. When expanded to a greater number of wards there was still an improvement in quality but to a lesser degree.

Cancer has overtaken cardiovascular disease as the commonest cause of death in Scottish type 2 diabetes patients: A population-based study (The Ayrshire Diabetes Follow-up Cohort study).

AIMS/INTRODUCTION: The increased mortality risk associated with diabetes is well established. The aim of the present study was to determine the causes of death of people with type 2 diabetes in Ayrshire and Arran, Scotland, between 2009 and 2014, and compare them with the national mortality rates. MATERIALS AND METHODS: The primary causes of death were collated. The causes of death were clustered into nine categories: heart disease, stroke, infection, renal failure, respiratory disorders, cancer, mental health, decompensated diabetes and other. The total rates were compared with national rates using the standardized mortality ratio (SMR), and then individually with heart disease, cerebrovascular disease and cancer. RESULTS: There were 2116 deaths with the SMR, and 145 of those were caused by type 2 diabetes (n = 16,643; 95% confidence interval 139-152; P < 0.01). The SMR was >100 in all age bands, particularly in the younger age bands (P < 0.01). The SMR was consistently higher for women (P < 0.01). The SMR for heart disease was significantly >100 for both sexes in all age bands <65 years (P < 0.05). There was no difference in mortality causes related to the duration of diabetes. The most common cause of death was cancer (27.8%), followed by heart disease (24.1%). The SMR for cancer deaths was significantly elevated in women (120, 95% CI 104-137; P < 0.05). CONCLUSIONS: This study confirmed increased mortality risk in type 2 diabetes patients, and suggests that where cardiovascular risk factors are being treated aggressively, cancer takes on a greater importance in the cause of death. Should greater consideration now be given for cancer as a complication of diabetes?

Health screening, cardiometabolic disease and adverse health outcomes in individuals with severe mental illness.

BACKGROUND: Poor physical health in severe mental illness (SMI) remains a major issue for clinical practice. AIMS: To use electronic health records of routinely collected clinical data to determine levels of screening for cardiometabolic disease and adverse health outcomes in a large sample (n = 7718) of patients with SMI, predominantly schizophrenia and bipolar disorder. METHOD: We linked data from the Glasgow Psychosis Clinical Information System (PsyCIS) to morbidity records, routine blood results and prescribing data. RESULTS: There was no record of routine blood monitoring during the preceding 2 years for 16.9% of the cohort. However, monitoring was poorer for male patients, younger patients aged 16-44, those with schizophrenia, and for tests of cholesterol, triglyceride and glycosylated haemoglobin. We estimated that 8.0% of participants had diabetes and that lipids levels, and use of lipid-lowering medication, was generally high. CONCLUSIONS: Electronic record linkage identified poor health screening and adverse health outcomes in this vulnerable patient group. This approach can inform the design of future interventions and health policy.