Connections between health research systems and decision-making spaces: lessons from the COVID-19 pandemic in the province of Québec, Canada

The coronavirus 2019 (COVID-19) pandemic allowed for exceptional decision-making power to be placed in the hands of public health departments. Data and information were widely disseminated in the media and on websites. While the improvement of pandemic management is still a learning curve, the ecosystem perspective - that is, the interconnection of academic health research systems and decision-making spaces - has received little attention. In this commentary, we look at the mechanisms in place, or not, in Canada for ensuring decision-making spheres can "speak" to academic research systems. We look at the thick walls that are still in place between health research systems and decision-making spaces. More precisely, we discuss three organizational flaws that we identified in the evidence-informed decision-making ecosystem of Québec and, more broadly, Canada. We introduce some inspiring measures that other countries have implemented to better link evidence and public health decision-making during health crises. The observed flaws and options are related to the vitality of early information sharing relays, the cross-sectional capacity to issue opinions, and the collection and integration of hard and soft data.

Equilibrium in the governance of cross-sectoral policies: how does it translate into practice?

BACKGROUND

There is growing interest from health researchers in the governance of Health in All Policies (HiAP). Furthermore, the COVID-19 pandemic has re-ignited managers' interest in HiAP governance and in health prevention activities that involve actors from outside health ministries. Since the dynamics of these multi-actor, multi-sectoral policies are complex, the use of systems theory is a promising avenue toward understanding and improving HiAP governance. We focus on the concept of equilibrium within systems theory, especially as it points to the need to strike a balance between actors that goes beyond synergies or mimicry-a balance that is essential to HiAP governance.

METHOD

We mobilized two sources of data to understand how the concept of equilibrium applies to HiAP governance. First, we reviewed the literature on existing frameworks for collaborative governance, both in general and for HiAP specifically, in order to extract equilibrium-related elements. Second, we conducted an in-depth case study over three years of an HiAP implemented in Quebec, Canada.

RESULTS

In total, we identified 12 equilibrium-related elements relevant to HiAP governance and related to knowledge, actors, learning, mindsets, sustainability, principles, coordination, funding and roles. The equilibria were both operational and conceptual in nature.

CONCLUSIONS

We conclude that policy makers and policy implementers could benefit from mobilizing these 12 equilibrium-related elements to enhance HiAP governance. Evaluators of HiAP may also want to consider and integrate them into their governance assessments.

A prospective multicentre randomized all-comers trial to assess the safety and effectiveness of the ultra-thin-strut sirolimus-eluting coronary stent Supraflex: 2-year results of the TALENT trial

Background and purpose

Supraflex is a sirolimus-eluting stent with a biodegradable polymeric coating and 60um ultra-thin struts. In the TALENT study, we found the Supraflex stent was non-inferior to the Xience stent for a device-oriented composite endpoint (DOCE, defined as cardiac death, target-vessel myocardial infarction, or clinically indicated target lesion revascularisation) at 12 months in an all-comer population. Additionally, per-protocol analysis showed a significantly lower clinically indicated target lesion revascularisation (CI-TLR) in the Supraflex group than in the Xience group. We now present the 2-year follow-up results.

Methods

The TALENT study was a prospective, randomised, single-blind, multicentre study across 23 centres in Europe. Eligible participants underwent percutaneous coronary intervention in an all-comers fashion in vessels of 2.25–4.5 mm. Patients were randomized (1:1) to implantation of either Supraflex or Xience (NCT02870140).

Results

Between October 21, 2016 and July 3, 2017, 720 patients with 1046 lesions were randomly assigned to Supraflex, and 715 patients with 1030 lesions to Xience. At 24 months, DOCE had occurred in 49 patients (6.9%) in the Supraflex group and in 56 patients (7.9%) in the Xience group (absolute difference −1.0% [95% CI: −3.7 to 1.7], Plog-rank=0.491). Per-protocol analysis at 24 months showed CI-TLR occurred in 21 and 30 patients in the Supraflex and Xience, respectively (3.3% versus 4.5%, absolute difference −1.2%, [95% CI: −3.3 to 0.9], Plog-rank=0.267).

Conclusion

In an all-comer population, at 2-year follow-up, the use of Supraflex stent was at least as safe and efficacious as Xience stent. However, the significantly lower rate of CI-TLR shown in patients treated with Supraflex at 1-year was no longer retained in the 2-year results. Whether theoretical advantage of ultra-thin strut drug eluting stents Supraflex can translate into clinical benefit or not will be further elucidated through a total of 3 years of follow-up.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): SMT

Impact of diabetes mellitus on 2-year outcomes of Absorb BVS compared to Xience EES: a pooled analysis of the COMPARE-ABSORB and AIDA trial

Background and purpose

Diabetes mellitus (DM) is associated with increased risk of cardiovascular events after percutaneous coronary intervention (PCI). To evaluate the impact of Absorb bioresorbable vascular scaffold (BVS) in patients with DM, we aimed to compare the 2-year outcomes of Absorb BVS versus 2nd generation drug eluting stents Xience (EES) by pooling diabetic patients treated with BVS or EES from two large, randomized controlled trial.

Methods

Patients with medically-treated DM and treated by Absorb BVS in the COMPARE-ABSORB and AIDA trial were pooled for analysis. The primary efficacy outcomes measure was target lesion failure (cardiac death, target-vessel myocardial infarction or target lesion revascularization), and the primary safety outcome measure was device thrombosis at 2-year follow-up.

Results

Out of a total 3515 enrolled subjects in the two trials, 913 were diabetics. Compared with the non-diabetic patients, those with DM were older, more often to have a history of hypercholesterolemia, chronic renal failure, stroke, hypertension, heart failure, peripheral vascular disease and previous PCI. At 2-years, target lesion failure occurred in 10.8% of BVS DM patients and 7.6% of EES DM patients (adjusted HR 1.43, 95% CI: 0.87–2.34, P=0.115). The 2-year rates of cardiac death (2.4% vs 1.6%, P=0.385), TV-MI (5% vs 1.6%, P=0.123) and TLR (7.8% vs 5.8%, P=0.416) showed not significant difference. The 2-year incidence of definite device thrombosis was 3.2% in Absorb BVS versus 0.7% in Xience EES (adjusted HR 4.77, 95% CI: 1.01–22.43, P=0.048).

Conclusion

This pooling of the diabetic patients from two large scale RCTs compared BVS versus 2nd generation DES, showed an increased rate of device thrombosis in BVS-treated patients at 2 years.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Abbott

Two-year clinical performance of Absorb BVS compared to Xience EES in ST-segment elevation myocardial infarction: a pooled analysis of AIDA and COMPARE-ABSORB trials

Introduction

Bioresorbable vascular scaffolds (BVS) use appears theoretically attractive in patients presenting with ST-segment elevation myocardial infarction (STEMI) as acute lesions are generally composed of soft plaques, in which optimal BVS deployment and expansion is easier to achieve. Furthermore, those patients are generally younger and would benefit longer from the promise of vascular restoration therapy.

Purpose

In this patient level pooled analysis of two clinical trials, we evaluated the clinical outcomes of Absorb BVS versus Xience everolimus-eluting stent (EES) in STEMI patients at 2-year follow-up.

Methods

We performed an individual patient-level pooled analysis of the AIDA and COMPARE-ABSORB trials in which 3515 patient were randomly assigned to Absorb BVS (n=1772) or Xience EES (n=1743). Clinical outcomes in STEMI patients were analyzed by randomized treatment assignment cumulative through 2 years. The primary efficacy outcomes measure was target lesion failure (cardiac death, target-vessel myocardial infarction or target lesion revascularization), and the primary safety outcome measure was device thrombosis at 2-year follow-up.

Results

350 (19.8%) STEMI patients were allocated to Absorb BVS versus 328 (18.8%) to Xience EES. The mean age of patient presenting with STEMI was 60 years old, 76.0% were males and 15.3% had diabetes mellitus. At 2-years target lesion failure occurred in 8.4% of BVS STEMI patients and 6.2% of EES STEMI patients (p=0.253). The 2-year rates of cardiac death (2.6% vs 1.6%, p=0.332), TV-MI (4.7% vs 2.5%) and TLR (6.8% vs 4.1%) were not significantly different. The 2-year incidence of definite device thrombosis was 4.7% in Absorb BVS versus 1.8% in Xience EES (p=0.045).

Conclusion

In the present patient-level pooled analysis of the AIDA and COMPARE-Absorb trials, BVS was associated with increased rates of device thrombosis in STEMI patients compared to Xience EES.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Abbott

Governance of health research funding institutions: an integrated conceptual framework and actionable functions of governance

BACKGROUND

Health research has scientific, social and political impacts. To achieve such impacts, several institutions need to participate; however, health research funding institutions are seldom nominated in the literature as essential players. The attention they have received has so far focused mainly on their role in knowledge translation, informing policy-making and the need to organise health research systems. In this article, we will focus solely on the governance of national health research funding institutions. Our objectives are to identify the main functions of governance for such institutions and actionable governance functions. This research should be useful in several ways, including in highlighting, tracking and measuring the governance trends in a given funding institution, and to forestall low-level governance.

METHODS

First, we reviewed existing frameworks in the grey literature, selecting seven relevant documents. Second, we developed an integrated framework for health research funding institution governance and management. Third, we extracted actionable information for governance by selecting a mix of North American, European and Asian institutions that had documentation available in English (e.g. annual report, legal status, strategy).

RESULTS

The framework contains 13 functions - 5 dedicated to governance (intelligence acquisition, resourcing and instrumentation, relationships management, accountability and performance, and strategy formulation), 3 dedicated to management (priority-setting, financing and knowledge transfer), and 5 dedicated to transversal logics that apply to both governance and management (ethics, transparency, capacity reinforcement, monitoring and evaluation, and public engagement).

CONCLUSIONS

Herein, we provide a conceptual contribution for scholars in the field of governance and health research as well as a practical contribution, with actionable functions for high-level managers in charge of the governance of health research funding institutions.

Implementing public policy in a non-directive manner: capacities from an intermediary organization

SETTING

We investigate the capacities of an organization responsible for bridging top-down instructions emanating from a law on public health with the bottom-up realities of health service providers working on population-based health. This article traces the implementation of this law, which requires service-provider organizations to base their actions (planning, prevention, and curative activities) upon the expressed and non-expressed needs of the local population. We investigate a case in the province of Québec that took place over more than 10 years.

INTERVENTION

The state strategy involved a key structure: an intermediary organization named IPCDC/KSCDI. We first describe how the organization emerged; the expertise involved from the academic, service, and policy domains; the support provided to service-provider organizations; and the achievements. We then highlight the critical capacities the intermediary organization had to nurture.

OUTCOMES

We identify five critical capacities of the intermediary organization: the business intelligence to read and adjust to the given environment of certain organizations, a dedication to collective means, a win-win mentality, scientific connectivity, and the animation of safe havens.

IMPLICATIONS

It may be important to focus attention on a capacity approach to intermediary organizations. These capacities can potentially enable governmental organizations to compile a stock of resources that can be mobilized and transferred to support future implementations of other reforms. They could also benefit public health partners in the community who collaborate with service providers and actors who aspire to become intermediary organizations. Finally, the performance measurement of implementing reforms in a non-directive manner could be based on indicators related to these five critical capacities.

Getting evidence to travel inside public systems: what organisational brokering capacities exist for evidence-based policy?

Background

Implementing research findings into healthcare policy is an enduring challenge made even more difficult when policies must be developed and implemented with the help and support of multiple ideas, agendas and actors taking part in determinants of health. Only looking at mechanisms to feed policy-makers with evidence or to interest researchers in the policy process will simply bring partial clues; implementing evidence-based policy also requires organisations to lead and to partner in the production and intake of scientific evidence from academics and practical evidence from one another.

Main body

This Commentary argues for the need to better understand the capacities required by organisations to foster evidence-based policy in a dispersed environment. It proposes a framework of 11 brokering capacities for organisations involved in evidence-based policy. Eight of these capacities are informed by streams of research related to the roles of knowledge broker, innovation broker and policy broker. Three complementary brokering capacities are informed by our experience studying real-life evidence-based policies; these are capturing boundary knowledge, trending know-how on scientific and practical evidence-based policy, and conveying evidence outward.

Conclusions

Previous guidelines on brokering capacities focused on the individual level more than on the organisational level. Beyond the individual capacities of managers, designers and implementers of new policies, there is a need to identify and assess the brokering capacities of organisations involved in evidence-based policy. The three specific organisational brokering capacities for evidence-based policy that we present offer a means for policy-makers and policy designers to reflect upon favourable environments for evidence-based policy. These capacities could also help administrators and implementation scholars to think about and develop measurements to assess the quality and readiness of organisations involved in evidence-based policy design.

Recommendations for the use of bioresorbable vascular scaffolds in percutaneous coronary interventions : 2017 revision

BACKGROUND

To eliminate some of the potential late limitations of permanent metallic stents, the bioresorbable coronary stents or 'bioresorbable vascular scaffolds' (BVS) have been developed.

METHODS

We reviewed all currently available clinical data on BVS implantation.

RESULTS

Since the 2015 position statement on the appropriateness of BVS in percutaneous coronary interventions, several large randomised trials have been presented. These have demonstrated that achieving adequate 1 and 2 year outcomes with these first-generation BVS is not straightforward. These first adequately powered studies in non-complex lesions showed worse results if standard implantation techniques were used for these relatively thick scaffolds. Post-hoc analyses hypothesise that outcomes similar to current drug-eluting stents are still possible if aggressive lesion preparation, adequate sizing and high-pressure postdilatation are implemented rigorously. As long as this has not been confirmed in prospective studies the usage should be restricted to experienced centres with continuous outcome monitoring. For more complex lesions, results are even more disappointing and usage should be discouraged. When developed, newer generation scaffolds with thinner struts or faster resorption rates are expected to improve outcomes. In the meantime prolonged dual antiplatelet therapy (DAPT, beyond one year) is recommended in an individualised approach for patients treated with current generation BVS.

CONCLUSION

The new 2017 recommendations downgrade and limit the use of the current BVS to experienced centres within dedicated registries using the updated implantation protocol and advise the prolonged usage of DAPT. In line with these recommendations the manufacturer does not supply devices to the hospitals without such registries in place.

L'analyse de contribution pour évaluer l'impact de la démarche ÉIS sur les processus décisionnels municipaux : un choix méthodologique intéressant ?

La pertinence de l'évaluation d'impact sur la santé (ÉIS) pour promouvoir le développement de politiques publiques favorables à la santé au sein des municipalités est de plus en plus reconnue. L'appréciation des effets d'une démarche d'ÉIS sur les processus décisionnels d'acteurs municipaux peut toutefois être difficile en raison de la multitude d'influences sociales, économiques, géographiques et personnelles auxquels ils sont soumis. Dans un tel contexte, l'approche évaluative de l'analyse de contribution (AC) s'avère particulièrement intéressante puisqu'elle permet de documenter les facteurs menant à l'efficacité d'une intervention en tenant compte des éléments du contexte. Elle aide l'évaluateur à comprendre comment et pourquoi une intervention fonctionne. Le présent article utilise l'étude de cas pour explorer la faisabilité et l'efficacité de l'AC pour apprécier les effets de démarches d'ÉIS sur le processus décisionnel d'acteurs municipaux. Il décrit les stratégies de collecte et d'analyse de données utilisées auprès de trois municipalités de la Montérégie, au Québec. Cette analyse critique montre que l'AC est pertinente dans le contexte décrit. Elle permet d'établir des associations claires et transparentes entre l'intervention, soit la démarche d'ÉIS, et l'importance accordée à la santé par les acteurs municipaux. Elle assure la prise en compte des facteurs d'influence contextuels et offre la flexibilité nécessaire pour adapter la collecte de données à la réalité du terrain. Néanmoins, la lourdeur de l'approche peut en contraindre l'application et certaines limites méthodologiques ont été observées au niveau de l'analyse des données. Les stratégies mises de l'avant pour y remédier sont décrites.

Evaluation of the effects of health impact assessment practice at the local level in Monteregie

Background

In Quebec (Canada), the Monteregie Regional Public Health Department has chosen to use health impact assessment (HIA) to support municipalities through a knowledge exchange and collaborative process in order to positively influence decision-making regarding local policies and projects. The value of HIA is becoming increasingly recognized by municipalities interested in planning and managing their cities with an eco-systemic perspective. However, the knowledge and tools which support the use of the HIA at regional and local levels are still missing.

Methods

The general objective is to evaluate the impact the collaborative HIA process used in Monteregie has had on the formulation, adoption and implementation of policies and projects favourable to health. The methodology is based on Mayne’s CA design, which allows the identification of factors which contribute to a change process. It is described as one of the best approaches to reduce uncertainty regarding the observed results and the contribution of a program. All of the HIA processes realised between January 2013 and January 2016 in Monteregie will be studied following a case study strategy. Study populations include regional and local public health professionals, municipal officers and community members implicated in these HIAs. Various qualitative and quantitative methods will be used, including examination of documentation, observations on the city grounds, and individual or group interviews. A model of change will be constructed for each HIA process and will present the logical pathway which leads to the observed results, alternative explanations and hypothesises as to why these results were obtained, and contextual factors that could have influenced them. This model will allow the production of a refined contribution story for each HIA. A convergence and divergence analysis will be completed in order to identify differences or similitudes between the different HIAs studied.

Discussion

In addition to contributing to the production of knowledge in relation to the collaborative model of HIA, this research project will allow other regional and local public health actors and municipalities of Quebec or other decision-making and political bodies to understand the usefulness of this approach for the improvement of population health and well-being.

The dipeptidyl peptidase-4 inhibitor vildagliptin does not affect ex vivo cytokine response and lymphocyte function in patients with type 2 diabetes mellitus

AIMS

The enzyme dipeptidyl peptidase-4 (DPP-4) is a key player in the degradation of incretin hormones that are involved in glucose metabolism. DPP-4 is also expressed on immune cells and is associated with several immunological functions. Some studies have reported increased rates of infections in patients treated with DPP-4 inhibitors. We therefore assessed whether treatment with the DPP-4 inhibitor vildagliptin affected cytokine production and T-cell differentiation.

METHODS

Patients with type 2 diabetes were treated with vildagliptin or an active comparator, acarbose, for four weeks, in a randomized cross-over trial. Blood was sampled at the end of each treatment period and peripheral blood mononuclear cells were isolated and stimulated with a broad spectrum of pattern recognition receptor agonists.

RESULTS

Serum cytokine concentrations and ex vivo cytokine production (both monocyte and T-cell derived) did not differ during treatment with vildagliptin compared to acarbose. Similarly, ex vivo relative upregulation of mRNA transcription of T-cell lineage specific transcription factors was unaffected by vildagliptin treatment.

CONCLUSIONS

These data show that a four-week treatment with vildagliptin in patients with type 2 diabetes mellitus does not result in a significant modulation of cytokine responses. This observation suggests that inhibition of DDP-4 does not lead to an increased risk of infection by diminishing cytokine production.

No Specific Effect of Fluoxetine Treatment on Fasting Glucose, Insulin, Lipid Levels, and Blood Pressure in Healthy Men with Abdominal Obesity

In this paper we investigated the effect of fluoxetine (60 mg/d) on serum lipids, glucose and insulin concentrations and blood pressure by means of a randomized, double-blind placebo controlled trial. Thirty-eight overweight (BMI: 26-30 kg/m2), nondiabetic, nonhypertensive men with an abdominal fat distribution (waist/hip ratio: > 0.97) received dietary advice and placebo or fluoxetine for 12 weeks. The changes in serum parameters and blood pressure in the fluoxetine treated group were not different from the placebo treated group, despite a significantly larger weight loss in the fluoxetine group. In both groups serum total-cholesterol concentrations, serum LDL-cholesterol concentrations and the HDL/LDL ratio were significantly improved after treatment. Reductions in fasting glucose concentration and systolic blood pressure were only significant in the placebo group. A reduction of serum triglycerides and an increase of HDL-cholesterol were found in the fluoxetine treated group. In the total study population the changes in serum lipids seemed to be more strongly related to the change in total body fat or subcutaneous abdominal fat (assessed by MRI) compared to the change in visceral fat. The improvement of most of the serum lipids was related to the change in total body fat independent of the mechanism for attaining this fat loss. Our results indicate that fluoxetine treatment has no specific effect beyond that expected for weight loss on serum lipid, glucose and insulin concentrations, and blood pressure in overweight men.

The effect of antecedent hypoglycaemia on β₂-adrenergic sensitivity in healthy participants with the Arg16Gly polymorphism of the β₂-adrenergic receptor

AIMS/HYPOTHESIS

Homozygosity for glycine at codon 16 (GlyGly) of the β(2)-adrenergic receptor may alter receptor sensitivity upon chronic stimulation and has been implicated in the pathogenesis of hypoglycaemia unawareness. We compared the effect of antecedent hypoglycaemia on β(2)-adrenergic receptor sensitivity between GlyGly participants and those with arginine 16 homozygosity (ArgArg) for the β(2)-adrenergic receptor.

METHODS

We enrolled 16 healthy participants, who were either GlyGly (n = 8) or ArgArg (n = 8). They participated randomly in two 2 day experiments. Day 1 consisted of two 2-h hyperinsulinaemic hypoglycaemic (2.8 mmol/l) or euglycaemic (4.8 mmol/l) glucose clamps. On day 2, we measured the forearm vasodilator response to the β(2)-adrenergic receptor agonist salbutamol and the dose of isoprenaline required to increase the heart rate by 25 bpm (IC(25)).

RESULTS

The vasodilator response to salbutamol tended to be greater after antecedent hypoglycaemia than after euglycaemia (p = 0.078), consistent with increased β(2)-adrenergic receptor sensitivity. This effect was driven by a significant increase in β(2)-adrenergic receptor sensitivity following hypoglycaemia compared with euglycaemia in ArgArg participants (p = 0.019), whereas no such effect was observed in the GlyGly participants. Antecedent hypoglycaemia tended to decrease the IC(25) in ArgArg participants, whereas the reverse occurred in the GlyGly participants (GlyGly vs ArgArg group p = 0.047).

CONCLUSION/INTERPRETATION

Antecedent hypoglycaemia did not affect β(2)-adrenergic receptor sensitivity in healthy GlyGly participants, but increased it in ArgArg participants. If these results also hold for participants with type 1 diabetes, such an increase in β(2)-adrenergic receptor sensitivity may potentially reduce the risk of repeated hypoglycaemia and the subsequent development of hypoglycaemia unawareness in ArgArg diabetic participants.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00160056.

Sequence variants in four candidate genes (NIPSNAP1, GBAS, CHCHD1 and METT11D1) in patients with combined oxidative phosphorylation system deficiencies

The oxidative phosphorylation (OXPHOS) system, comprising five enzyme complexes, is located in the inner membrane of mitochondria and is the final biochemical pathway in oxidative ATP production. Defects in this energy-generating system can cause a wide range of clinical symptoms; these diseases are often progressive and multisystemic. Numerous genes have been implicated in OXPHOS deficiencies and many mutations have been described. However, in a substantial number of patients with decreased enzyme activities of two or more OXPHOS complexes, no mutations in the mitochondrial DNA or in nuclear genes known to be involved in these disorders have been found. In this study, four nuclear candidate genes--NIPSNAP1, GBAS, CHCHD1 and METT11D1--were screened for mutations in 22 patients with a combined enzymatic deficiency of primarily the OXPHOS complexes I, III and IV to determine whether a mutation in one of these genes could explain the mitochondrial disorder. For each variant not yet reported as a polymorphism, 100 control samples were screened for the presence of the variant. This way we identified 14 new polymorphisms and 2 presumably non-pathogenic mutations. No mutations were found that could explain the mitochondrial disorder in the patients investigated in this study. Therefore, the genetic defect in these patients must be located in other nuclear genes involved in mtDNA maintenance, transcription or translation, in import, processing or degradation of nuclear encoded mitochondrial proteins, or in assembly of the OXPHOS system.

High dose ascorbic acid does not reverse central sympathetic overactivity in chronic heart failure

WHAT IS KNOWN AND OBJECTIVE

The increased central sympathetic activity typically associated with chronic heart failure (CHF) is probably mediated by formation of reactive oxygen species (ROS) in the brain. Our objective was to undertake a trial to test our hypothesis that administration of the well-known antioxidant and ROS scavenger ascorbic acid, would reverse or reduce the sympathetic overactivity in CHF patients.

METHODS

In a prospective, randomized, placebo-controlled, double-blind, cross-over trial, 11 CHF patients were treated with ascorbic acid 2 g/day or placebo for 3 days. At the end of each treatment period, sympathetic nervous system activity was measured by microneurography for direct muscle sympathetic nerve activity (MSNA) recording, analysis of heart rate variability (HRV) and measurement of plasma norepinephrine concentrations.

RESULTS

During ascorbic acid administration, plasma vitamin C levels were higher than during placebo (74·9 ± 6·0 μmol/L vs. 54·8 ± 4·6 μmol/L, P = 0·03). Ascorbic acid had no effect on sympathetic activity: MSNA (ascorbic acid: 66·8 ± 3·3 vs. placebo 66·9 ± 3·2 bursts/100 beats, P = 0·98). In addition, HRV and plasma norepinephrine levels did not differ.

WHAT IS NEW AND CONCLUSION

  Short-term administration of the antioxidant ascorbic acid in CHF patients does not reverse the increased sympathetic activity as measured by microneurography, HRV and plasma norepinephrine levels. The use of higher oral dosages seems not feasible due to accompanying side effects.

Autonomic neuropathy predisposes to rosiglitazone-induced vascular leakage in insulin-treated patients with type 2 diabetes: a randomised, controlled trial on thiazolidinedione-induced vascular leakage

AIMS/HYPOTHESIS

The mechanism of fluid-related complications caused by thiazolidinedione derivatives is unclear. One potential mechanism is thiazolidinedione-induced arterial vasodilatation, which results in vascular leakage and a fall in blood pressure, normally counterbalanced by sympathetic activation and subsequent renal fluid retention. We hypothesised that thiazolidinedione-induced vascular leakage will be particularly prominent in patients with autonomic neuropathy.

METHODS

We conducted a randomised, double-blind, placebo-controlled, parallel study in 40 patients with type 2 diabetes on insulin treatment recruited from a university medical centre. The randomisation was performed by a central office using a randomisation schedule. Both treatment groups, placebo (n = 21) and rosiglitazone (n = 19), were stratified for sex and level of autonomic neuropathy as assessed by Ewing score (<2.5 or >or=2.5). We investigated the effects of 16 weeks of treatment with rosiglitazone 4 mg twice daily on vascular leakage (transcapillary escape rate of albumin, TERalb), body weight, extracellular volume and plasma volume.

RESULTS

Thirty-nine patients were included in the analysis. In patients with high Ewing scores (n = 16), rosiglitazone increased TERalb significantly (DeltaTERalb: rosiglitazone +2.43 +/- 0.45%/h, placebo -0.11 +/- 0.15%/h, p = 0.002), while rosiglitazone had no effect in the patients with low Ewing scores (n = 23). Rosiglitazone-induced increases in TERalb and Ewing score at baseline were correlated (r = 0.65, p = 0.02). There was no correlation between Ewing score and rosiglitazone-induced changes in fluid variables. One subject was withdrawn from the study because of atrial fibrillation.

CONCLUSIONS/INTERPRETATION

Rosiglitazone may increase vascular leakage in insulin-treated patients with type 2 diabetes with autonomic neuropathy. Autonomic neuropathy did not exaggerate rosiglitazone-induced fluid retention. Therefore, autonomic neuropathy should be considered as a risk factor for thiazolidinedione-induced oedema, not for thiazolidinedione-induced fluid retention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00422955.

FUNDING

GlaxoSmithKline.

The role of the alpha-adrenergic receptor in the leg vasoconstrictor response to orthostatic stress

AIM

The prompt increase in peripheral vascular resistance, mediated by sympathetic alpha-adrenergic stimulation, is believed to be the key event in blood pressure control during postural stress. However, despite the absence of central sympathetic control of the leg vasculature, postural leg vasoconstriction is preserved in spinal cord-injured individuals (SCI). This study aimed at assessing the contribution of both central and local sympathetically induced alpha-adrenergic leg vasoconstriction to head-up tilt (HUT) by including healthy individuals and SCI, who lack central sympathetic baroreflex control over the leg vascular bed.

METHODS

In 10 controls and nine SCI the femoral artery was cannulated for drug infusion. Upper leg blood flow (LBF) was measured bilaterally using venous occlusion strain gauge plethysmography before and during 30 degrees HUT throughout intra-arterial infusion of saline or the non-selective alpha-adrenergic receptor antagonist phentolamine respectively. Additionally, in six controls the leg vascular response to the cold pressor test was assessed during continued infusion of phentolamine, in order to confirm complete alpha-adrenergic blockade by phentolamine.

RESULTS

During infusion of phentolamine HUT still caused vasoconstriction in both groups: leg vascular resistance (mean arterial pressure/LBF) increased by 10 +/- 2 AU (compared with 12 +/- 2 AU during saline infusion), and 13 +/- 3 AU (compared with 7 +/- 3 AU during saline infusion) in controls and SCI respectively.

CONCLUSION

Effective alpha-adrenergic blockade did not reduce HUT-induced vasoconstriction, regardless of intact baroreflex control of the leg vasculature. Apparently, redundant mechanisms compensate for the absence of sympathetic alpha-adrenoceptor leg vasoconstriction in response to postural stress.

Intravenous AICAR administration reduces hepatic glucose output and inhibits whole body lipolysis in type 2 diabetic patients

AIMS/HYPOTHESIS

The 5'-AMP-activated protein kinase (AMPK) pathway is intact in type 2 diabetic patients and is seen as a target for diabetes treatment. In this study, we aimed to assess the impact of the AMPK activator 5-aminoimidazole-4-carboxamide riboside (AICAR) on both glucose and fatty acid metabolism in vivo in type 2 diabetic patients.

METHODS

Stable isotope methodology and blood and muscle biopsy sampling were applied to assess blood glucose and fatty acid kinetics following continuous i.v. infusion of AICAR (0.75 mg kg(-1) min(-1)) and/or NaCl (0.9%) in ten male type 2 diabetic patients (age 64 +/- 2 years; BMI 28 +/- 1 kg/m(2)).

RESULTS

Plasma glucose rate of appearance (R (a)) was reduced following AICAR administration, while plasma glucose rate of disappearance (R (d)) was similar in the AICAR and control test. Consequently, blood glucose disposal (R (d) expressed as a percentage of R (a)) was increased following AICAR infusion (p < 0.001). Accordingly, a greater decline in plasma glucose concentration was observed following AICAR infusion (p < 0.001). Plasma NEFA R (a) and R (d) were both significantly reduced in response to AICAR infusion, and were accompanied by a significant decline in plasma NEFA concentration. Although AMPK phosphorylation in skeletal muscle was not increased, we observed a significant increase in acetyl-CoA carboxylase phosphorylation (p < 0.001).

CONCLUSIONS/INTERPRETATION

The i.v. administration of AICAR reduces hepatic glucose output, thereby lowering blood glucose concentrations in vivo in type 2 diabetic patients. Furthermore, AICAR administration stimulates hepatic fatty acid oxidation and/or inhibits whole body lipolysis, thereby reducing plasma NEFA concentration.

Endothelium-dependent and -independent vasodilation of the superficial femoral artery in spinal cord-injured subjects

Extreme inactivity of the legs in spinal cord-injured (SCI) individuals does not result in an impairment of the superficial femoral artery flow-mediated dilation (FMD). To gain insight into the underlying mechanism, the present study examined nitric oxide (NO) responsiveness of vascular smooth muscles in controls and SCI subjects. In eight healthy men (34 +/- 13 yr) and six SCI subjects (37 +/- 10 yr), superficial femoral artery FMD response was assessed by echo Doppler. Subsequently, infusion of incremental dosages of sodium nitroprusside (SNP) was used to assess NO responsiveness. Peak diameter was examined on a second day after 13 min of arterial occlusion in combination with sublingual administration of nitroglycerine. Resting and peak superficial femoral artery diameter in SCI subjects were smaller than in controls (P < 0.001). The FMD response in controls (4.2 +/- 0.9%) was lower than in SCI subjects (8.2 +/- 0.9%, P < 0.001), but not after correcting for area under the curve for shear rate (P = 0.35). When expressed as relative change from baseline, SCI subjects demonstrate a significantly larger diameter increase compared with controls at each dose of SNP. However, when expressed as a relative increase within the range of diameter changes [baseline (0%) - peak diameter (100%)], both groups demonstrate similar changes in response to SNP. Changes in diameter during SNP infusion and FMD response are larger in SCI subjects compared with controls. When these results are corrected, superficial femoral artery FMD and NO sensitivity in SCI subjects are not different from those in controls. This illustrates the importance of appropriate data presentation and suggests that, subsequent to structural inward remodeling of conduit arteries as a consequence of extreme physical inactivity, arterial function is normalized.

Flow-mediated dilatation in the superficial femoral artery is nitric oxide mediated in humans

Flow-mediated dilatation (FMD) of the brachial and radial arteries is an important research tool for assessment of endothelial function in vivo, and is nitric oxide (NO) dependent. The leg skeletal muscle vascular bed is an important territory for studies in exercise physiology. However, the role of endothelial NO in the FMD response of lower limb arteries has never been investigated. The purpose of this study was to examine the contribution of NO to FMD in the superficial femoral artery in healthy subjects. Since physical inactivity may affect endothelial function, and therefore NO availability, spinal cord-injured (SCI) individuals were included as a model of extreme deconditioning. In eight healthy men (34 +/- 13 years) and six SCI individuals (37 +/- 10 years), the 5 min FMD response in the superficial femoral artery was assessed by echo-Doppler, both during infusion of saline and during infusion of the NO synthase blocker N(G)-monomethyl-L-arginine (L-NMMA). In a subset of the controls (n = 6), the 10 min FMD response was also examined using the same procedure. The 5 min FMD response in controls (4.2 +/- 0.3%) was significantly diminished during L-NMMA infusion (1.0 +/- 0.2%, P < 0.001). In SCI, L-NMMA also significantly decreased the FMD response (from 8.2 +/- 0.4% during saline to 2.4 +/- 0.5% during L-NMMA infusion). The hyperaemic flow response during the first 45 s after cuff deflation was lower in both groups during infusion of L-NMMA, but the effect of L-NMMA on FMD persisted in both groups after correction for the shear stress stimulus. The 10 min FMD was not affected by L-NMMA (saline: 5.4 +/- 1.6%, L-NMMA: 5.6 +/- 1.5%). Superficial femoral artery FMD in response to distal arterial occlusion for a period of 5 min is predominantly mediated by NO in healthy men and in the extremely deconditioned legs of SCI individuals.

Physical (in)activity and endothelium-derived constricting factors: overlooked adaptations

The inner surrounding of arterial vessels, the endothelium, is optimally located to detect changes in blood characteristics or blood flow that may result from changes in physical activity or from diseases. In response to physical stimuli, the endothelium varies its release of circulating vasoactive substances and serves as a source of local and systemic endothelium-derived dilator and vasoconstrictor factors. Endothelial dysfunction is one of the earliest markers of vascular abnormalities observed in cardiovascular disease and ageing. Exercise training is an efficient therapeutic strategy to improve endothelial function. Traditionally, studies on endothelial dysfunction and physical (in)activity-related effects on vascular adaptations are primarily focused on vasodilator substances (i.e. nitric oxide). One may suggest that augmentation of vasoconstrictor pathways (such as endothelin-1 and angiotensin II) contributes to the endothelial dysfunction observed after physical inactivity. Moreover, these pathways may also explain the exercise-induced beneficial cardiovascular adaptations. This review summarizes the current knowledge on the effects of physical (in)activity on several endothelium-derived vasoconstrictor substances.

Local vasoconstriction in spinal cord-injured and able-bodied individuals

Local vasoconstriction plays an important role in maintaining blood pressure in spinal cord-injured individuals (SCI). We aimed to unravel the mechanisms of local vasoconstriction [venoarteriolar reflex (VAR) and myogenic response] using both limb dependency and cuff inflation in SCI and compare these with control subjects. Limb blood flow was measured in 11 male SCI (age: 24–55 yr old) and 9 male controls (age: 23–56 yr old) using venous occlusion plethysmography in forearm and calf during three levels of 1) limb dependency, and 2) cuff inflation. During limb dependency, vasoconstriction relies on both the VAR and the myogenic response. During cuff inflation, the decrease in blood flow is caused by the VAR and by a decrease in arteriovenous pressure difference, whereas the myogenic response does not play a role. At the highest level of leg dependency, the percent increase in calf vascular resistance (mean arterial pressure/calf blood flow) was more pronounced in SCI than in controls (SCI 186 ± 53%; controls 51 ± 17%; P = 0.032). In contrast, during cuff inflation, no differences were found between SCI and controls (SCI 17 ± 17%; controls 14 ± 10%). Percent changes in forearm vascular resistance in response to either forearm dependency or forearm cuff inflation were equal in both groups. Thus local vasoconstriction during dependency of the paralyzed leg in SCI is enhanced. The contribution of the VAR to local vasoconstriction does not differ between the groups, since no differences between groups existed for cuff inflation. Therefore, the augmented local vasoconstriction in SCI during leg dependency relies, most likely, on the myogenic response.

Vascular adaptations to 8-week cycling training in older men

AIM

Because age-related changes in the large conduit arteries (increased wall thickness, and attenuated arterial compliance and endothelial function) are associated with cardiovascular pathology, prevention is of paramount importance. The effects of endurance training (i.e. walking or cycling) in older humans are assessed in cross-sectional studies, examining the brachial and carotid arteries (supplying non-trained areas). The purpose of this study was to assess the effects of 8-week endurance training in older men on conduit artery characteristics in the trained and non-trained vascular beds.

METHODS

In eight healthy sedentary older men (70 +/- 3 years), characteristics of the large conduit arteries [common femoral (CFA), superficial femoral (SFA), carotid (CA), and brachial artery (BA)] were measured before and after 8-week cycling training. Functional [arterial compliance and flow-mediated dilation (FMD)] and structural (diameter and intima-media thickness) conduit artery properties were measured using echo-Doppler. Peak blood flow, representing structural peripheral adaptations, was measured using venous occlusion plethysmography.

RESULTS

After training, peak leg blood flow was increased (P < 0.01) and baseline diameter and flow were increased in the CFA (P < 0.05). Cycling training enhanced arterial compliance of the SFA (P = 0.03), but did not affect the FMD (P = 0.32) or the intima-media thickness of the SFA. Exercise training did not alter characteristics of the BA or CA.

CONCLUSION

Eight weeks of endurance training in older men altered functional and structural characteristics of the lower extremity vasculature, whereas no changes are reported for the conduit arteries in the non-trained areas (BA or in the CA).

Effects of allopregnanolone on sedation in men, and in women on oral contraceptives

Allopregnanolone is a known GABA(A) receptor agonist not previously given to men, or to women using oral contraceptives (OC). The effects of metabolites of sex hormones on the GABA(A) receptor are different between men and women. OC are known to change GABA(A) receptor subunit composition. These factors might play a role in the differential effect of allopregnanolone in men and women, and in women with or without OC. To study the sedative effect of and sensitivity to allopregnanolone in men and in women with OC, nine healthy men (mean age 24.6 years) and nine healthy women on OC (mean age 21.8 years) were given three, increasing, intravenous dosages (0.015, 0.03, and 0.045 mg/kg) of allopregnanolone. Saccadic eye velocity (SEV), subjective ratings, and electroencephalography (EEG) were used to evaluate the response to allopregnanolone. Repeated blood samples for analyses of serum allopregnanolone levels were drawn throughout the study day. Allopregnanolone decreased SEV more in women than in men, and increased subjective ratings of 'sedation'. The results in women on OC are similar to earlier results in women without OC. Subjective ratings of 'contentedness' decreased in men but increased in women. Serum levels of allopregnanolone were more highly increased in men compared to women. Other pharmacokinetic parameters were not different between sexes. On the EEG, beta power increased in men. In conclusion, men and women on OC reacted differently to allopregnanolone.

Forearm vasoconstrictor response in uncomplicated type 1 diabetes mellitus

BACKGROUND

According to the 'haemodynamic hypothesis', increased tissue perfusion predisposes to microangiopathy in diabetic patients. We hypothesized that the typical haemodynamic changes underlying the increased tissue perfusion can be explained by a decreased sympathetic nerve activity caused by chronic hyperglycaemia. In this study we investigated sympathetic activity in patients with uncomplicated type 1 diabetes mellitus (DM).

MATERIALS AND METHODS

In 15 DM patients (DM duration 6.3 +/- 3.8 year; HbA1c 7.9 +/- 1.3%) and 16 age- and sex-matched healthy volunteers (Control), sympathetic nervous system activity was measured at rest (baseline) and during sympathoneural stimulation (lower body negative pressure (LBNP)) by means of interstitial and plasma noradrenaline (NA) sampling and power spectral analysis. Muscle sympathetic nerve activity (MSNA) was measured before (baseline) and during a cold pressure test. Forearm blood flow was measured during forearm vascular alpha- and beta-adrenergic receptor blockade.

RESULTS

At baseline, forearm vascular resistance (FVR), plasma NA concentrations, MSNA and heart rate variability were similar in both groups. LBNP-induced vasoconstriction was significantly attenuated in the DM group compared with the Control group (DeltaFVR: 12 +/- 4 vs. 19 +/- 3 arbitrary units, P < 0.05). The responses of plasma NA and heart rate variability did not differ.

CONCLUSIONS

Baseline FVR and sympathetic nerve activity are normal in patients with uncomplicated type 1 diabetes. However, the forearm vasoconstrictor response to sympathetic stimulation is attenuated, which cannot be attributed to an impaired sympathetic responsiveness.

Pathophysiology and management of recurrent hypoglycaemia and hypoglycaemia unawareness in diabetes

Iatrogenic hypoglycaemia is a well-known complication of insulin therapy in patients with diabetes mellitus and a limiting factor for glycaemic control. In a setting of endogenous insulin deficiency (type 1 and advanced type 2 diabetes), one episode of hypoglycaemia reduces both counterregulatory hormone responses to and subjective awareness of subsequent hypoglycaemia, thus impairing physiological defences against hypoglycaemia. This phenomenon may lead to a vicious cycle of recurrent hypoglycaemia and glucose counterregulatory failure, of which hypoglycaemia unawareness (i.e. the inability to perceive symptoms of hypoglycaemia) is the clinical representative. The underlying mechanism of hypoglycaemia-induced counterregulatory failure has not yet been disclosed. Patients with clinical hypoglycaemia unawareness are at high risk of severe hypoglycaemia that requires third-party assistance. Management options include avoidance of hypoglycaemic events and optimisation of insulin therapy to limit deterioration of glycaemic control associated with hypoglycaemia avoidance. Several counterregulatory-stimulating agents have been found to improve hypoglycaemic awareness in small clinical trials, but none have been tested in sufficiently large randomised studies to justify their use in daily practice. More research is required to elucidate the pathogenesis of counterregulatory failure and to develop adequate treatment strategies.

Forearm vascular response to nitric oxide and calcitonin gene-related peptide: comparison between migraine patients and control subjects

The forearm vascular response to nitric oxide (NO) and calcitonin gene-related peptide (CGRP) was investigated in 10 migraine patients and 10 matched control subjects. Changes in forearm blood flow (FBF) during intrabrachial infusion of: (i) serotonin (releasing endogenous NO), (ii) sodium nitroprusside (SNP, exogenous NO-donor), and (iii) CGRP were measured using venous occlusion plethysmography. Flow-mediated dilation (FMD) of the brachial artery, a measure for the endogenous release of NO reactive to occlusion, was measured using ultrasound and expressed as percentage change vs. baseline diameter. FBF ratio (i.e. FBF in the infused over the control arm) at baseline (1.1 +/- 0.1) did not differ between both populations. Serotonin, SNP and CGRP induced a dose-dependent increase (P < 0.001) in FBF ratio in controls (to 2.8 +/- 0.3, 6.7 +/- 1.4 and 6.9 +/- 1.2 at the highest dose, respectively) and migraineurs (2.5 +/- 0.4, 5.6 +/- 0.8 and 6.5 +/- 1.3, respectively); these ratios did not differ between both groups. FMD was comparable in control subjects (5.8 +/- 1%) and migraine patients (5.2 +/- 1%). Based on the forearm vascular response to NO and CGRP, migraine patients do not display generalized changes in vascular function.

Thiazolidinedione derivatives in type 2 diabetes mellitus

In Europe, the thiazolidinedione derivatives pioglitazone and rosiglitazone have been approved for the treatment of type 2 diabetes mellitus either as monotherapy for patients with intolerance or contraindications to metformin or in combination therapy. This class of drugs seems particularly suited for obese patients, but is currently not considered as a first choice for monotherapy. The efficacy with respect to blood glucose lowering is comparable with sulphonylurea (SU) derivatives and with metformin. Long-term data with respect to efficacy and side effects are still limited.

Methotrexate modulates the kinetics of adenosine in humans in vivo

BACKGROUND

Animal studies suggest that the anti-inflammatory effect of methotrexate (MTX) is mediated by increased adenosine concentrations.

OBJECTIVE

To assess the effect of MTX on the vasodilator effects of adenosine and the nucleoside uptake inhibitor, dipyridamole, in humans in vivo as a marker for changes in adenosine kinetics.

METHODS

Ten patients with active arthritis were treated with MTX (15 mg/week). Measurements were performed before and after 12 weeks of treatment. At these time points, the activity of adenosine deaminase was measured in isolated lymphocytes, and forearm blood flow (FBF) was determined by venous occlusion plethysmography during administration of adenosine and dipyridamole into the brachial artery.

RESULTS

The Vmax of adenosine deaminase in lymphocytes was reduced by MTX treatment (p<0.05). MTX significantly enhanced vasodilator response to adenosine (0.5 and 1.5 microg/min/dl of forearm tissue; mean (SE) FBF ratio increased from 1.2 (0.2) to 1.4 (0.2) and 2.2 (0.2) ml/dl/min, respectively, before and from 1.3 (0.1) to 1.8 (0.2) and 3.2 (0.5) ml/dl/min during MTX treatment; p<0.05). Also, dipyridamole-induced vasodilatation (30 and 100 microg/min/dl) was enhanced by MTX (FBF ratio increased from 1.2 (0.2) to 1.5 (0.3) and 1.8 (0.2), respectively, before and from 1.3 (0.1) to 1.8 (0.2) and 2.4 (0.4) during MTX treatment; p<0.05).

CONCLUSIONS

MTX treatment inhibits deamination of adenosine and potentiates adenosine-induced vasodilatation. Also dipyridamole-induced vasodilatation is enhanced by MTX treatment, suggesting an increased extracellular formation of adenosine. These effects on the adenosine kinetics in humans may contribute to the therapeutic efficacy of MTX.