Zn2+ differentially influences the neutralisation of heparins by HRG, fibrinogen, and fibronectin.

Funding: This research was funded by the British Heart Foundation, grant numbers PG/15/9/31270 and FS/15/42/3155.For coagulation to be initiated, anticoagulant glycosaminoglycans (GAGs) such as heparins need to be neutralised to allow fibrin clot formation. Platelet activation triggers the release of several proteins that bind GAGs, including histidine-rich glycoprotein (HRG), fibrinogen and fibronectin. Zn2+ ions are also released and have been shown to enhance binding of HRG to heparins of a high- molecular weight (HMWH), but not to those of low-molecular weight (LMWH). The effect of Zn2+ on fibrinogen and fibronectin binding to GAGs is unknown. Here, chromogenic assays were used to measure the anti-factor Xa and anti-thrombin activities of heparins of different molecular weights and to assess the effects of HRG, fibrinogen, fibronectin and Zn2+. Surface plasmon resonance was also used to examine the influence of Zn2+-on binding of fibrinogen to heparins of different molecular weights. Zn2+ had no effect on the neutralisation of anti-factor Xa (FXa) or anti-thrombin activities of heparin by fibronectin, whereas it enhanced neutralisation of unfractionated heparin (UFH) and HMWH by both fibrinogen and HRG. Zn2+ also increased neutralisation of the anti-FXa activity of LMWH by fibrinogen but not HRG. SPR showed that Zn2+ in-creased fibrinogen binding to both UFH and LMWH in a concentration-dependent manner. The presented results reveal that an increase in Zn2+ concentration has differential effects upon anti-coagulant GAG neutralisation by HRG and fibrinogen, with implications for modulating anti-coagulant activity in plasma.Publisher PDFPeer reviewe

Plasma levels of mannan-binding lectin-associated serine proteases are increased in type 1 diabetes patients with insulin resistance.

Activation of the lectin pathway of the complement system, as demonstrated by elevated levels of mannan-binding lectin proteins (MBL), contributes to vascular pathology in type 1 diabetes (T1D). Vascular complications are greatest in T1D individuals with concomitant insulin resistance (IR), however, whether IR amplifies activiation of the lectin pathway in T1D is unknown. We pooled pre-treatment data from two RCTs and performed a cross-sectional analysis on 46 T1D individuals. We employed estimated glucose disposal rate (eGDR), a validated IR surrogate with cut-points of: 8.7 mg/kg/min to determine IR status, with lower eGDR values conferring higher degrees of IR. Plasma levels of MBL-associated proteases (MASP-1, MASP-2, MASP-3) and their regulatory protein MAp44 were compared among eGDR classifications. In a subset of 14 individuals, we assessed change in MASPs and MAp44 following improvement in IR. We found that MASP-1, MASP-2, MASP-3, and MAp44 levels increased in a stepwise fashion across eGDR thresholds with elevated MASPs and MAp44 levels conferring greater degrees of IR. In a subset of 14 patients, improvement in IR was associated with significant reductions in MASPs, but not MAp44, levels. In conclusion, IR in T1D amplifies levels of MASP-1/2/3 and their regulator MAp44, and improvement of IR normalises MASP-1/2/3 levels. Given that elevated levels of these proteins contribute to vascular pathology, amplification of the lectin pathway of the complement system may offer mechanistic insight into the relationship between IR and vascular complications in T1D

Reduced plasma magnesium levels in type-1 diabetes associate with prothrombotic changes in fibrin clotting and fibrinolysis

This research was funded by the British Heart Foundation, grant numbers PG/15/9/31270 and FS/15/42/3155. The study sponsor was not involved in the design of the study; the collection, analysis, and interpretation of data.Individuals with type-1 diabetes mellitus (T1DM) have a higher risk of thrombosis and low plasma magnesium concentrations. As magnesium is a known regulator of fibrin network formation, we investigated potential associations between fibrin clot properties and plasma magnesium concentrations in 45 individuals with T1DM and 47 age- and sex-matched controls without diabetes. Fibrin clot characteristics were assessed using a validated turbidimetric assay and associations with plasma magnesium concentration were examined. Plasma concentrations of fibrinogen, plasminogen activator inhibitor-1 (PAI-1), and lipids were measured and fibrin fiber diameters assessed using scanning electron microscopy. Fibrin clot maximum absorbance was unchanged in subjects with T1DM compared with controls, while lysis time was prolonged (p = 0.0273). No differences in fibrin fiber diameters or in lipid profile were observed between T1DM and controls. PAI-1 concentration was lower in the T1DM group compared with the controls (p = 0.0232) and positively correlated with lysis time (p = 0.0023). Plasma magnesium concentration was lower in the T1DM group compared with controls (p < 0.0001). Magnesium concentration negatively correlated with clot maximum absorbance (p = 0.0215) and lysis time (p = 0.0464). A turbidimetric fibrin clot lysis assay performed in a purified system that included PAI-1 and 0 to 3.2 mM Mg2+ showed a shortening of lysis time with increasing Mg2+ concentrations (p = 0.0004). Our findings reveal that plasma magnesium concentration is associated with changes in fibrin clot and lysis parameters.Publisher PDFPublisher PDFPeer reviewe

Lipidomic profiling of plasma free fatty acids in type-1 diabetes highlights specific changes in lipid metabolism

This research was funded by the British Heart Foundation [grant numbers PG/15/9/31270, FS/15/42/3155].Type-1 diabetes mellitus (T1DM) is associated with metabolic changes leading to alterations in glucose and lipid handling. While T1DM- associated effects on many major plasma lipids have been characterised, such effects on plasma free fatty acids (FFA) have not been fully examined. Using gas chromatography-mass spectrometry, we measured the plasma concentrations of FFA species in individuals with T1DM (n=44) and age/sex-matched healthy controls (n=44). Relationships between FFA species and various parameters were evaluated. Plasma concentrations of myristate (14:0), palmitoleate (16:1), palmitate (16:0), linoleate (18:2), oleate (18:1c9), cis-vaccenate (18:1c11), eicosapentaenoate (20:5), arachidonate (20:4) and docosahexanoate (22:6) were reduced in the T1DM group (p<0.0001 for all, except p=0.0020 for eicosapentaenoate and p=0.0068 for arachidonate); α-linolenate (18:3) and dihomo-γ- linolenate (20:3) concentrations were unchanged. Saturated/unsaturated FFA ratio, n-3/n-6 ratio, de novo lipogenesis index (palmitate (main lipogenesis product)/linoleate (only found in diet)) and elongase index (oleate/palmitoleate) were increased in the T1DM group (p=0.0166, p=0.0089, p<0.0001 and p=0.0008 respectively). The stearoyl-CoA desaturase 1 (SCD1) index 1 (palmitoleate/palmitate) and index 2 (oleate/stearate) were reduced in T1DM (p<0.0001 for all). The delta-(5)- desaturase (D5D) index (arachidonate/dihomo-γ-linolenate) was unchanged. Age and sex had no effect on plasma FFA concentrations in T1DM, while SCD1 index 1 was positively correlated (p=0.098) and elongase index negatively correlated with age (p=0.0363). HbA1c was negatively correlated with all plasma FFAs concentrations measured except α- linolenate and dihomo-γ-linolenate. Correlations were observed between plasma FFAs and cholesterol and HDL, but not LDL or diabetes duration. Collectively, these results aid our understanding of T1DM and its effects on lipid metabolism.Publisher PDFPeer reviewe

Strategies for therapeutic amelioration of aberrant plasma Zn2+ handling in thrombotic disease: Targeting fatty acid/serum albumin-mediated effects

Funding: This research was funded by Leverhulme Trust, grant number RPG-2017-214; Bio-technology and Biological Sciences Research Council, grant number BB/J006467/1 and BB/V014684/1; British Heart Foundation, grant number FS/20/3/34956.The initiation, maintenance and regulation of blood coagulation is inexorably linked to the actions of Zn2+ in blood plasma. Zn2+ interacts with a variety of haemostatic proteins in the bloodstream including fibrinogen, histidine-rich glycoprotein (HRG) and high molecular weight kininogen (HMWK) to regulate haemostasis. The availability of Zn2+ to bind such proteins is controlled by human serum albumin (HSA), which binds 70-85% plasma Zn2+ under basal conditions. HSA also binds and transports non-esterified fatty acids (NEFAs). Upon NEFA binding, there is a change in the structure of HSA which leads to a reduction in its affinity for Zn2+. This enables other plasma proteins to better compete for binding of Zn2+. In diseases where elevated plasma NEFA con-centrations are a feature, such as obesity and diabetes, there is a concurrent increase in hyper-coagulability. Evidence indicates that NEFA-induced perturbation of Zn2+-binding by HSA may contribute to the thrombotic complications frequently observed in these pathophysiological conditions. This review highlights potential interventions - both pharmaceutical and non-pharmaceutical - that may be employed to combat this dysregulation. Lifestyle and dietary changes have been shown to reduce plasma NEFA concentrations. Furthermore, drugs that in-fluence NEFA levels such as statins and fibrates may be useful in this context. In severely obese patients more invasive therapies such as bariatric surgery may be useful. Finally, other potential treatments such as chelation therapies, use of cholesteryl transfer protein (CETP) inhibitors, lipase inhibitors, fatty acid inhibitors and other treatments are highlighted, that with additional research and appropriate clinical trials, could prove useful in the treatment and management of thrombotic disease through amelioration of plasma Zn2+ dysregulation in high-risk individuals.Publisher PDFPeer reviewe

Acceptability and feasibility of continuous glucose monitoring in people with diabetes : protocol for a mixed-methods systematic review of quantitative and qualitative evidence

BACKGROUND: Good glycaemic control is a crucial part of diabetes management. Traditional assessment methods, including HbA1c checks and self-monitoring of blood glucose, can be unreliable and inaccurate. Continuous glucose monitoring (CGM) offers a non-invasive and more detailed alternative. Availability of this technology is increasing worldwide. However, there is no current comprehensive evidence on the acceptability and feasibility of these devices. This is a protocol for a mixed-methods systematic review of qualitative and quantitative evidence about acceptability and feasibility of CGM in people with diabetes. METHODS: We will search MEDLINE, Embase, CINAHL, and CENTRAL for qualitative and quantitative evidence about the feasibility and acceptability of CGM in all populations with diabetes (any type) using search terms for "continuous glucose monitoring" and "diabetes". We will not apply any study-type filters. Searches will be restricted to studies conducted in humans and those published from 2011 onwards. We will not restrict the search by language. Study selection and data extraction will be carried out by two reviewers independently using Rayyan and Eppi-Reviewer, respectively, with disagreements resolved by discussion. Data extraction will include key information about each study, as well as qualitative evidence in the form of participant quotes from primary studies and themes and subthemes based on the authors' analysis. Quantitative data relating to acceptability and feasibility including data loss, adherence, and quantitative ratings of acceptability will be extracted as means and standard deviations or n/N as appropriate. Qualitative evidence will be analysed using framework analysis informed by the Theoretical Framework of Acceptability. Where possible, quantitative evidence will be combined using random-effects meta-analysis; otherwise, a narrative synthesis will be performed. The most appropriate method for integrating qualitative and quantitative findings will be selected based on the data available. DISCUSSION: Ongoing assessment of the acceptability of interventions has been identified as crucially important to scale-up and implementation. This review will provide new knowledge with the potential to inform a programme theory of CGM as well as future roll-out to potentially vulnerable populations, including those with severe mental illness. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021255141

Changes in fibrin clot properties in patients after Roux en-Y gastric bypass surgery

Background: Obesity is a complex condition associated with prothrombotic fibrin networks that are resistant to fibrinolysis. Altered fibrin clot properties enhance cardiovascular risk and associate with a poorer prognosis following acute ischemic events. Bariatric surgery is commonly employed to improve cardiometabolic outcomes in obese individuals. However, the effects of this surgical intervention on fibrin clot properties have not been comprehensively studied. Methods: The fibrin clot properties of 32 obese individuals before and 9-months after Roux en-Y gastric bypass (RYGB) surgery were determined using turbidimetric analysis. Correlation and regression analyses were used to identify relationships between clot properties and anthropomorphic and clinical measures. Results: RYGB surgery resulted in a significant reduction in adiposity-associated anthropometric measures as well as improvements in glycaemia and lipid profile. Clot maximum absorbance was reduced from 0.43 ± 0.11 at baseline to 0.29 ± 0.10 at 9 months post-surgery (p < 0.0001), while fibrin clot lysis time failed to show a difference. The change in maximum absorbance was not caused by alterations in fibrinogen levels, while PAI-1 concentration was significantly increased after surgery from 10,560 ± 6,681 pg/ml to 15,290 ± 6,559 pg/ml (p = 0.0093). Correlation and regression analysis indicated that maximum absorbance was influenced by markers of adiposity as well as HbA1c and hs-CRP concentrations. Conclusions: RYGB surgery led to a decrease in the maximum absorbance of the fibrin clot. Values of maximum absorbance were associated with measures of glycaemic control and inflammation. In contrast to previous reports, fibrin clot lysis time was not affected after surgery.Peer reviewe

Changes in plasma free fatty acids in obese patients before and after bariatric surgery highlight alterations in lipid metabolism

This work was supported by the British Heart Foundation (grant ref: FS/20/3/34956).Obesity is a complex disease that increases an individual’s risk of developing other diseases and health-related problems. A common feature is dyslipidemia characterized by increased levels of plasma lipids, which include non-esterified fatty acids (NEFAs). The role of NEFAs in obesity-related morbidity is interesting as NEFAs constitute a reservoir of metabolic energy, are principal components of cell membranes and are precursors for signalling molecules. Bariatric surgery promotes sustained weight loss in severely obese patients, reducing the incidence and severity of co-morbidities. In this study we measure changes in circulating NEFA species in plasma samples taken from 25 obese individuals before and 9 months after Roux-en-Y gastric bypass surgery. The mean weight of the cohort reduced by 29.2% from 149.0±25.1 kg pre-surgery to 105.5±19.8 kg post-surgery and the BMI by 28.2% from 51.8±6.3 kg/m2 pre-surgery to 37.2±5.4 kg/m2. Mean glycated haemoglobin (HbA1c) reduced from 6.5±1.3% to 5.5±0.5%, consistent with the intervention leading to improved glycaemic control, particularly in those who were dysglycemic prior to surgery. Total and LDL cholesterol concentrations were markedly reduced following surgery. Concentrations of seven NEFAs were found to decrease 9 months after surgery compared to pre-surgery levels: myristate, palmitoleate, palmitate, linoleate, oleate, stearate and arachidonate. Bariatric surgery led to increased lipogenesis and elongase activity and decreased stearoyl-CoA desaturase 1 activity. This study thus highlights metabolic changes that take place following gastric bypass surgery in severely obese patients.Publisher PDFPeer reviewe

Glucose, cholesterol and blood pressure in type II diabetes : a longitudinal observational study comparing patients with and without severe mental illness

INTRODUCTION: Patients with both severe mental illness (SMI) and type II diabetes (T2DM) have lower life expectancy than patients with T2DM alone, partly due to poor control of cardiovascular risk factors in comorbid patients. AIM: To compare levels of cholesterol, HbA1c and blood pressure in T2DM patients with and without SMI. METHOD: We analysed longitudinal clinical records of 30,353 people with T2DM (657 with SMI;29,696 controls without SMI) between 2001 and 2013 using the Clinical Practice Research Datalink (CPRD). We used mixed effects regression models to compare cardiovascular risk factors between SMI and controls. RESULTS: Patients with SMI had lower mean systolic blood pressure (SBP) (β -2.49; SE=0.45 P=<0.01) and were more likely to have extreme (high and low) values of HbA1c and SBP (OR 1.38, 95%CI: 1.16,1.64 and 1.76:1.40,2.21 respectively). DISCUSSION: People with T2DM and SMI have similar average values of cardiovascular risk factors to people with T2DM alone but are more likely to have values of HbA1c and SBP indicating increased risk of adverse clinical outcomes. IMPLICATIONS FOR PRACTICE: Improved management of cardiovascular risk factors in general, glycaemic control in particular, is central to addressing the increased risk of adverse outcomes in people with both SMI and T2DM. This article is protected by copyright. All rights reserved

Total plasma magnesium, zinc, copper and selenium concentrations in obese patients before and after bariatric surgery

Funding: This work was supported by the British Heart Foundation (grant code: FS/20/3/34956).Obesity enhances the risk of type-2 diabetes, cardiovascular disease and inflammatory conditions and often leads to metal dyshomeostasis, which contributes to the negative health aspects associated with the disease. In severe cases, bariatric surgery can be recommended to achieve sustained weight loss and improvement in health. Here, magnesium, zinc, copper and selenium concentrations were examined in 24 obese patients (7 males; 17 females) before and 9 months after undergoing Roux-en-Y gastric bypass surgery. All patients lost weight over this period, with the mean BMI reducing from 51.2±7.1 kg/m2 to 37.2±5.5 kg/m2. Moreover, whole-blood glycated haemoglobin (HbA1c), as a marker of average glycaemia, was also measured and a correlative analysis of this parameter with metal concentrations performed. Significant alterations in the plasma concentrations of magnesium, zinc (both increased by 13.2% and 25.2% respectively) and copper (decreased by 7.9%) were observed over this period (plasma selenium concentration was unchanged), with BMI values correlating with plasma magnesium (p=0.004) and zinc (p=0.022) concentrations. At 9 months post-surgery, an increase in mean zinc/copper ratio was observed (0.86±0.29 compared to 0.63±0.14 pre-surgery). Comparison of whole-blood HbA1c concentrations pre- and post-surgery revealed a reduction from 6.50±1.28% pre-surgery to 5.51±0.49% post-surgery. Differences in plasma HbA1c and magnesium at either pre- and post-surgery correlated significantly, as did HbA1c and magnesium levels when pre- and post-surgery values were analysed together. Collectively, this work reveals that bariatric surgery, in conjunction with lifestyle/dietary changes, lead to improvements in the nutritional status of magnesium, zinc and copper. Furthermore, the observed improvements in magnesium and zinc were associated with weight loss and in the case of magnesium, to better glycaemic control.Publisher PDFPeer reviewe