Cold-induced dishabituation in rodents exposed to recurrent hypoglycaemia.

AIMS/HYPOTHESIS: Recurrent hypoglycaemia in people with diabetes leads to progressive suppression of counterregulatory hormonal responses to subsequent hypoglycaemia. Recently it has been proposed that the mechanism underpinning this is a form of adaptive memory referred to as habituation. To test this hypothesis, we use two different durations of cold exposure to examine whether rodents exposed to recurrent hypoglycaemia exhibit two characteristic features of habituation, namely stimulus generalisation and dishabituation. METHODS: In the first study (stimulus generalisation study), hyperinsulinaemic-hypoglycaemic (2.8 mmol/l) glucose clamps were performed in non-diabetic rodents exposed to prior moderate-duration cold (4°C for 3 h) or control conditions. In the second study (dishabituation study), rodents exposed to prior recurrent hypoglycaemia or saline (154 mmol/l NaCl) injections over 4 weeks underwent a longer-duration cold (4°C for 4.5 h) exposure followed 24 h later by a hyperinsulinaemic-hypoglycaemic (2.8 mmol/l) glucose clamp. Output measures were counterregulatory hormone responses during experimental hypoglycaemia. RESULTS: Moderate-duration cold exposure blunted the adrenaline (epinephrine) response (15,266 ± 1920 vs 7981 ± 1258 pmol/l, Control vs Cold; p < 0.05) to next day hypoglycaemia in healthy non-diabetic rodents. In contrast, the suppressed adrenaline response (Control 5912 ± 1417 vs recurrent hypoglycaemia 1836 ± 736 pmol/l; p < 0.05) that is associated with recurrent hypoglycaemia was restored following longer-duration cold exposure (recurrent hypoglycaemia + Cold 4756 ± 826 pmol/l; not significant vs Control). CONCLUSIONS/INTERPRETATION: Non-diabetic rodents exhibit two cardinal features of habituation, namely stimulus generalisation and dishabituation. These findings provide further support for the hypothesis that suppressed counterregulatory responses following exposure to recurrent hypoglycaemia in diabetes result from habituation.

SGLT2-inhibitors; more than just glycosuria and diuresis.

Heart failure (HF) continues to be a serious public health challenge despite significant advancements in therapeutics and is often complicated by multiple other comorbidities. Of particular concern is type 2 diabetes mellitus (T2DM) which not only amplifies the risk, but also limits the treatment options available to patients. The sodium-glucose linked cotransporter subtype 2 (SGLT2)-inhibitor class, which was initially developed as a treatment for T2DM, has shown great promise in reducing cardiovascular risk, particularly around HF outcomes - regardless of diabetes status.There are ongoing efforts to elucidate the true mechanism of action of this novel drug class. Its primary mechanism of inducing glycosuria and diuresis from receptor blockade in the renal nephron seems unlikely to be responsible for the rapid and striking benefits seen in clinical trials. Early mechanistic work around conventional therapeutic targets seem to be inconclusive. There are some emerging theories around its effect on myocardial energetics and calcium balance as well as on renal physiology. In this review, we discuss some of the cutting-edge hypotheses and concepts currently being explored around this drug class in an attempt better understand the molecular mechanics of this novel agent.

Xanthine Oxidoreductase Inhibitors.

Xanthine oxidase inhibitors are primarily used in the clinical prevention and treatment of gout associated with hyperuricemia. The archetypal xanthine oxidase inhibitor, Allopurinol has been shown to have other beneficial effects such as a reduction in vascular reactive oxygen species and mechano-energetic uncoupling. This chapter discusses these properties and their relevance to human pathophysiology with a focus on Allopurinol as well as newer xanthine oxidase inhibitors such as Febuxostat and Topiroxostat. Xanthine oxidase (XO) and xanthine dehydrogenase (XDH) are collectively referred to as xanthine oxidoreductase (XOR). XDH is initially synthesised as a 150-kDa protein from which XO is derived, e.g. under conditions of ischemia/hypoxia either reversibly by conformational changes (calcium or SH oxidation) or irreversibly by proteolysis, the latter leading to formation of a 130-kDa form of XO. Both, XO and XDH, catalyse the conversion of hypoxanthine via xanthine to uric acid, the former by using oxygen forming superoxide and hydrogen peroxide and the latter NAD+. However, XDH is in principle also able to generate ROS.

Research into the effect Of SGLT2 inhibition on left ventricular remodelling in patients with heart failure and diabetes mellitus (REFORM) trial rationale and design.

BACKGROUND: Heart failure (HF) and diabetes (DM) are a lethal combination. The current armamentarium of anti-diabetic agents has been shown to be less efficacious and sometimes even harmful in diabetic patients with concomitant cardiovascular disease, especially HF. Sodium glucose linked co-transporter type 2 (SGLT2) inhibitors are a new class of anti-diabetic agent that has shown potentially beneficial cardiovascular effects such as pre-load and after load reduction through osmotic diuresis, blood pressure reduction, reduced arterial stiffness and weight loss. This has been supported by the recently published EMPA-REG trial which showed a striking 38 and 35 % reduction in cardiovascular death and HF hospitalisation respectively. METHODS: The REFORM trial is a novel, phase IV randomised, double blind, placebo controlled clinical trial that has been ongoing since March 2015. It is designed specifically to test the safety and efficacy of the SLGT2 inhibitor, dapagliflozin, on diabetic patients with known HF. We utilise cardiac-MRI, cardio-pulmonary exercise testing, body composition analysis and other tests to quantify the cardiovascular and systemic effects of dapagliflozin 10 mg once daily against standard of care over a 1 year observation period. The primary outcome is to detect the change in left ventricular (LV) end systolic and LV end diastolic volumes. The secondary outcome measures include LV ejection fraction, LV mass index, exercise tolerance, fluid status, quality of life measures and others. CONCLUSIONS: This trial will be able to determine if SGLT2 inhibitor therapy produces potentially beneficial effects in patients with DM and HF, thereby replacing current medications as the drug of choice when treating patients with both DM and HF. Trial registration Clinical Trials.gov: NCT02397421. Registered 12th March 2015.

State of the art paper: Cardiac computed tomography of the left atrium in atrial fibrillation.

The clinical spectrum of atrial fibrillation means that a patient-individualized approach is required to ensure optimal treatment. Cardiac computed tomography can accurately delineate atrial structure and function and could contribute to a personalized care pathway for atrial fibrillation patients. The imaging modality offers excellent spatial resolution and has been utilised in pre-, peri- and post-procedural care for patients with atrial fibrillation. Advances in temporal resolution, acquisition times and analysis techniques suggest potential expanding roles for cardiac computed tomography in the future management of patients with atrial fibrillation. The aim of the current review is to discuss the use of cardiac computed tomography in atrial fibrillation in pre-, peri- and post-procedural settings. Potential future applications of cardiac computed tomography including atrial wall thickness assessment and epicardial fat volume quantification are discussed together with emerging analysis techniques including computational modelling and machine learning with attention paid to how these developments may contribute to a personalized approach to atrial fibrillation management.

Hospital readmissions for patients with prostate cancer are higher after radiotherapy than after prostatectomy.

PURPOSE: To compare hospital readmissions, biochemical recurrence rates, incidence of metastasis, and cancer-specific and overall mortality for prostate cancer patients undergoing radiotherapy vs. radical prostatectomy. The secondary outcome was to identify patient and disease characteristics affecting physician's choice of either therapy. MATERIALS AND METHODS: A total of 297 patients diagnosed with prostate cancer between 2008 and 2014 were identified from a single academic center's cancer database. Clinical information including age, ethnicity, comorbidities, prostate-specific antigen, Gleason score, stage, National Comprehensive Cancer Network (NCCN) risk group, biochemical recurrence, hospital readmissions, and survival outcomes were gathered and analyzed from ambulatory medical records until 2018. RESULTS: Patients selected for radiotherapy were older and had more comorbidities and NCCN high-risk disease. Biochemical recurrence was higher after radical prostatectomy for locally advanced disease, 59.3% vs. 20.0% (p<0.001), favoring radiotherapy. Hospital readmission was higher for patients with locally advanced disease undergoing radiotherapy, 48.6% vs. 18.5% (p=0.002), and 35.2% vs. 19.7% (p=0.044) for those with localized disease, with most of these readmissions occurring 24 months after the initial therapy. Radiation proctitis and colitis were the most common complications after radiotherapy and accounted for 46.3% of readmissions. CONCLUSIONS: Selection of patients for radiotherapy instead of surgery was influenced by age, significant comorbidities, and NCCN high-risk disease. The incidence of treatment- or cancer-related hospital readmissions was significantly higher for patients undergoing radiotherapy compared with radical prostatectomy, especially for those with locally advanced prostate cancer. This information may be useful in guiding a patient's choice of therapy.

Factors influencing participation and long-term commitment to self-monitoring of blood pressure in a large remote clinical trial: The treatment in morning versus evening (TIME) study.

This study investigates factors associated with active participation, and long-term commitment, to home blood pressure monitoring (HBPM) in the TIME study, a remote clinical trial assessing the effectiveness of morning vs. evening dosing of antihypertensive medications on cardiovascular outcomes in adults with hypertension. Participants reporting HBPM ownership were invited to submit blood pressure (BP) measurements three-monthly. Factors associated with active participation (submitting at least one set of BP measurements), and longer-term commitment (at least six sets of BP measurements), were analysed using multivariable logistic regression. 11,059 participants agreed to provide BP measurements, of whom 7646 submitted. Active participation was associated with age (adjusted odds ratio (AOR) per decade, 1.29; 95% CI 1.23-1.36), positive family history of hypertension (AOR 1.11; 95% CI 1.01-1.21), number of antihypertensive medications (AOR, 1.10; 95% CI 1.04-1.16), and lower deprivation (AOR per decile, 1.03; 95% CI 1.01-1.05). People with higher body mass index (BMI) and smokers were less likely to participate (AOR, 0.91 (per increase of 5.0 kg/m2) and 0.63 respectively; all p < 0.001). 3,655 participants (47.8%) submitted measurements beyond one year. Non-modifiable risk factors - age (AOR per decade, 1.29; 95% CI 1.21-1.37) and positive family history of hypertension (AOR, 1.15; 95% CI 1.03-1.27) - were positively associated with longer-term commitment. Higher BMI (AOR per 5.0 kg/m2, 0.89; 95% CI 0.85-0.93), smoking (AOR 0.60, 95% CI 0.44-0.82) and higher baseline systolic blood pressure (AOR per mmHg, 0.99; 95% CI 0.98-0.99) were negatively associated. This study provides insight into factors that influence HBPM use.

Role of Vascular Smooth Muscle Cell Plasticity and Interactions in Vessel Wall Inflammation.

The pathobiology of atherosclerotic disease requires further elucidation to discover new approaches to address its high morbidity and mortality. To date, over 17 million cardiovascular-related deaths have been reported annually, despite a multitude of surgical and nonsurgical interventions and advances in medical therapy. Existing strategies to prevent disease progression mainly focus on management of risk factors, such as hypercholesterolemia. Even with optimum current medical therapy, recurrent cardiovascular events are not uncommon in patients with atherosclerosis, and their incidence can reach 10-15% per year. Although treatments targeting inflammation are under investigation and continue to evolve, clinical breakthroughs are possible only if we deepen our understanding of vessel wall pathobiology. Vascular smooth muscle cells (VSMCs) are one of the most abundant cells in vessel walls and have emerged as key players in disease progression. New technologies, including in situ hybridization proximity ligation assays, in vivo cell fate tracing with the CreERT2-loxP system and single-cell sequencing technology with spatial resolution, broaden our understanding of the complex biology of these intriguing cells. Our knowledge of contractile and synthetic VSMC phenotype switching has expanded to include macrophage-like and even osteoblast-like VSMC phenotypes. An increasing body of data suggests that VSMCs have remarkable plasticity and play a key role in cell-to-cell crosstalk with endothelial cells and immune cells during the complex process of inflammation. These are cells that sense, interact with and influence the behavior of other cellular components of the vessel wall. It is now more obvious that VSMC plasticity and the ability to perform nonprofessional phagocytic functions are key phenomena maintaining the inflammatory state and senescent condition and actively interacting with different immune competent cells.

Dapagliflozin Versus Placebo on Left Ventricular Remodeling in Patients With Diabetes and Heart Failure: The REFORM Trial.

OBJECTIVE: To determine the effects of dapagliflozin in patients with heart failure (HF) and type 2 diabetes mellitus (T2DM) on left ventricular (LV) remodeling using cardiac MRI. RESEARCH DESIGN AND METHODS: We randomized 56 patients with T2DM and HF with LV systolic dysfunction to dapagliflozin 10 mg daily or placebo for 1 year, on top of usual therapy. The primary end point was difference in LV end-systolic volume (LVESV) using cardiac MRI. Key secondary end points included other measures of LV remodeling and clinical and biochemical parameters. RESULTS: In our cohort, dapagliflozin had no effect on LVESV or any other parameter of LV remodeling. However, it reduced diastolic blood pressure and loop diuretic requirements while increasing hemoglobin, hematocrit, and ketone bodies. There was a trend toward lower weight. CONCLUSIONS: We were unable to determine with certainty whether dapagliflozin in patients with T2DM and HF had any effect on LV remodeling. Whether the benefits of dapagliflozin in HF are due to remodeling or other mechanisms remains unknown.

Coronary artery bypass grafting in patients with low ejection fraction: what are the risk factors?

BACKGROUND: Left ventricular (LV) dysfunction alone is insufficient as an independent predictor of postoperative complications and mortality in coronary artery bypass graft (CABG) surgery. Our objective was to identify additional independent risk factors in patients with low left ventricle ejection fraction (EF) who underwent CABG. METHODS: We retrospectively analyzed CABG results of 346 consecutive patients with low EF (≤30%) in a single institution between 2009 and 2015. The primary study endpoint was 30-day all-cause mortality. The secondary endpoints were the development of major adverse cardiac events (MACE) and renal complications after operation. A subgroup of patients underwent additional analyses of the interaction between extents of viable myocardium and postoperative endpoints. RESULTS: The analysis showed that preoperative hemodynamic instability (AOR=4.57; 95% CI: 1.53-13.7, P=0.007) and serum creatinine >166 µmol/L (AOR=3.46; 95% CI: 1.12-10.7, P=0.031) were independent predictors of 30-day death. Both urgent and emergency operations were predictors for MACE (P=0.038; P=0.005) and renal complications (P=0.004; P=0.007). Pre-existing diabetes mellitus increased the likelihood of renal complications (P=0.020). In the sub-analysis of patients with viable myocardium, the mortality was significantly lower with predicted mortality (P=0.014). CONCLUSIONS: Patients with significant LV dysfunction undergoing isolated CABG have fair short-term survival even with EF less than 30%. Hemodynamic instability prior to operation and preoperative kidney dysfunction are strong predictors of mortality in patients with low EF. Favorable coronary targets, meticulous operative techniques, and optimal surgical timing before hemodynamic deterioration occurs are essential to minimize the risk of revascularization complications and early postoperative mortality.