Optimising a clinical decision support tool to improve chronic kidney disease management in general practice.

BACKGROUND: Early identification and treatment of chronic disease is associated with better clinical outcomes, lower costs, and reduced hospitalisation. Primary care is ideally placed to identify patients at risk of, or in the early stages of, chronic disease and to implement prevention and early intervention measures. This paper evaluates the implementation of a technological intervention called Future Health Today that integrates with general practice EMRs to (1) identify patients at-risk of, or with undiagnosed or untreated, chronic kidney disease (CKD), and (2) provide guideline concordant recommendations for patient care. The evaluation aimed to identify the barriers and facilitators to successful implementation. METHODS: Future Health Today was implemented in 12 general practices in Victoria, Australia. Fifty-two interviews with 30 practice staff were undertaken between July 2020 and April 2021. Practice characteristics were collected directly from practices via survey. Data were analysed using inductive and deductive qualitative analysis strategies, using Clinical Performance - Feedback Intervention Theory (CP-FIT) for theoretical guidance. RESULTS: Future Health Today was acceptable, user friendly and useful to general practice staff, and supported clinical performance improvement in the identification and management of chronic kidney disease. CP-FIT variables supporting use of FHT included the simplicity of design and delivery of actionable feedback via FHT, good fit within existing workflow, strong engagement with practices and positive attitudes toward FHT. Context variables provided the main barriers to use and were largely situated in the external context of practices (including pressures arising from the COVID-19 pandemic) and technical glitches impacting installation and early use. Participants primarily utilised the point of care prompt rather than the patient management dashboard due to its continued presence, and immediacy and relevance of the recommendations on the prompt, suggesting mechanisms of compatibility, complexity, actionability and credibility influenced use. Most practices continued using FHT after the evaluation phase was complete. CONCLUSIONS: This study demonstrates that FHT is a useful and acceptable software platform that provides direct support to general practice in identifying and managing patients with CKD. Further research is underway to explore the effectiveness of FHT, and to expand the conditions on the platform.

Implementing a Sodium-Glucose Cotransporter 2 Inhibitor Module With a Software Tool (Future Health Today): Qualitative Study.

BACKGROUND: Primary care plays a key role in the management of type 2 diabetes. Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been demonstrated to reduce hospitalization and cardiac and renal complications. Tools that optimize management, including appropriate prescribing, are a priority for treating chronic diseases. Future Health Today (FHT) is software that facilitates clinical decision support and quality improvement. FHT applies algorithms to data stored in electronic medical records in general practice to identify patients who are at risk of a chronic disease or who have a chronic disease that may benefit from intensification of management. The platform continues to evolve because of rigorous evaluation, continuous improvement, and expansion of the conditions hosted on the platform. FHT currently displays recommendations for the identification and management of chronic kidney disease, cardiovascular disease, type 2 diabetes, and cancer risk. A new module will be introduced to FHT focusing on SGLT2 inhibitors in patients with type 2 diabetes who have chronic kidney diseases, cardiovascular diseases, or risk factors for cardiovascular disease. OBJECTIVE: The study aims to explore the barriers and enablers to the implementation of an SGLT2 inhibitor module within the Future Health Today software. METHODS: Clinic staff were recruited to participate in interviews on their experience in their use of a tool to improve prescribing behavior for SGLT2 inhibitors. Thematic analysis was guided by Clinical Performance Feedback Intervention Theory. RESULTS: In total, 16 interviews were completed. Identified enablers of use included workflow alignment, clinical appropriateness, and active delivery of the module. Key barriers to use were competing priorities, staff engagement, and knowledge of the clinical topic. CONCLUSIONS: There is a recognized benefit to the use of a clinical decision support tool to support type 2 diabetes management, but barriers were identified that impeded the usability and actionability of the module. Successful and effective implementation of this tool could support the optimization of patient management of type 2 diabetes in primary care.

Optimising diagnosis and management of kidney disease: an implementation trial of a clinical decision support system future health today.

BACKGROUND: Chronic kidney disease affects more than 10% of the world's population and is a non-communicable disease of global concern and priority. There is a significant implementation gap between best practice guideline recommendations and current kidney disease management. Previous research has shown the need to partner with primary care to improve education, collaboration, and kidney disease awareness. This implementation trial will explore use of an innovative clinical decision support software, Future Health Today, to improve screening, diagnosis, and management of kidney disease in primary care. The program will be supported by tertiary care outreach services. The primary aim is to test the hypothesis that the Future Health Today implementation program will improve screening, diagnosis, and management of kidney disease. Secondary aims are to evaluate primary care satisfaction and broader health service impacts. METHODS: This pre-post implementation trial using an interrupted time series design will evaluate the clinical and service outcomes of Future Health Today, using a mixed methods study in twenty general practices with an estimated population size of 150,000. Deidentified patient data will be extracted from participating practices to examine the primary aims of the study. Surveys and semi-structured interviews with general practice will inform secondary hypotheses. Data linkage between primary care and tertiary care data will examine the broader health service impacts. DISCUSSION: This investigator driven trial will assess the impact of Future Health Today software coupled with education and clinical outreach support. Investigators hypothesise that there will be improvement in appropriate screening, diagnosis, and management of kidney disease. This program has the potential to be scaled more broadly. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry: ACTRN12623001096640.

Chronic disease IMPACT (chronic disease early detection and improved management in primary care project): An Australian stepped wedge cluster randomised trial.

Background: Interrelated chronic vascular diseases (chronic kidney disease (CKD), type 2 diabetes (T2D) and cardiovascular disease (CVD)) are common with high morbidity and mortality. This study aimed to assess if an electronic-technology-based quality improvement intervention in primary care could improve detection and management of people with and at risk of these diseases. Methods: Stepped-wedge trial with practices randomised to commence intervention in one of five 16-week periods. Intervention included (1) electronic-technology tool extracting data from general practice electronic medical records and generating graphs and lists for audit; (2) education regarding chronic disease and the electronic-technology tool; (3) assistance with quality improvement audit plan development, benchmarking, monitoring and support. De-identified data analysis using R 3.5.1 conducted using Bayesian generalised linear mixed model with practice and time-specific random intercepts. Results: At baseline, eight included practices had 37,946 active patients (attending practice ≥3 times within 2 years) aged ≥18 years. Intervention was associated with increased OR (95% CI) for: kidney health checks (estimated glomerular filtration rate, urine albumin:creatinine ratio (uACR) and blood pressure) in those at risk 1.34 (1.26-1.42); coded diagnosis of CKD 1.18 (1.09-1.27); T2D diagnostic testing (fasting glucose or HbA1c) in those at risk 1.15 (1.08-1.23); uACR in patients with T2D 1.78 (1.56-2.05). Documented eye checks within recommended frequency in patients with T2D decreased 0.85 (0.77-0.96). There were no significant changes in other assessed variables. Conclusions: This electronic-technology-based intervention in primary care has potential to help translate guidelines into practice but requires further refining to achieve widespread improvements across the interrelated chronic vascular diseases.

Using electronic medical record data to assess chronic kidney disease, type 2 diabetes and cardiovascular disease testing, recognition and management as documented in Australian general practice: a cross-sectional analysis.

OBJECTIVES: To evaluate the capacity of general practice (GP) electronic medical record (EMR) data to assess risk factor detection, disease diagnostic testing, diagnosis, monitoring and pharmacotherapy for the interrelated chronic vascular diseases-chronic kidney disease (CKD), type 2 diabetes (T2D) and cardiovascular disease. DESIGN: Cross-sectional analysis of data extracted on a single date for each practice between 12 April 2017 and 18 April 2017 incorporating data from any time on or before data extraction, using baseline data from the Chronic Disease early detection and Improved Management in PrimAry Care ProjecT. Deidentified data were extracted from GP EMRs using the Pen Computer Systems Clinical Audit Tool and descriptive statistics used to describe the study population. SETTING: Eight GPs in Victoria, Australia. PARTICIPANTS: Patients were ≥18 years and attended GP ≥3 times within 24 months. 37 946 patients were included. RESULTS: Risk factor and disease testing/monitoring/treatment were assessed as per Australian guidelines (or US guidelines if none available), with guidelines simplified due to limitations in data availability where required. Risk factor assessment in those requiring it: 30% of patients had body mass index and 46% blood pressure within guideline recommended timeframes. Diagnostic testing in at-risk population: 17% had diagnostic testing as per recommendations for CKD and 37% for T2D. Possible undiagnosed disease: Pathology tests indicating possible disease with no diagnosis already coded were present in 6.7% for CKD, 1.6% for T2D and 0.33% familial hypercholesterolaemia. Overall prevalence: Coded diagnoses were recorded in 3.8% for CKD, 6.6% for T2D, 4.2% for ischaemic heart disease, 1% for heart failure, 1.7% for ischaemic stroke, 0.46% for peripheral vascular disease, 0.06% for familial hypercholesterolaemia and 2% for atrial fibrillation. Pharmaceutical prescriptions: the proportion of patients prescribed guideline-recommended medications ranged from 44% (beta blockers for patients with ischaemic heart disease) to 78% (antiplatelets or anticoagulants for patients with ischaemic stroke). CONCLUSIONS: Using GP EMR data, this study identified recorded diagnoses of chronic vascular diseases generally similar to, or higher than, reported national prevalence. It suggested low levels of extractable documented risk factor assessments, diagnostic testing in those at risk and prescription of guideline-recommended pharmacotherapy for some conditions. These baseline data highlight the utility of GP EMR data for potential use in epidemiological studies and by individual practices to guide targeted quality improvement. It also highlighted some of the challenges of using GP EMR data.

Towards optimising chronic kidney disease detection and management in primary care: Underlying theory and protocol for technology development using an Integrated Knowledge Translation approach.

Worldwide, Chronic Kidney Disease (CKD), directly or indirectly, causes more than 2.4 million deaths annually with symptoms generally presenting late in the disease course. Clinical guidelines support the early identification and treatment of CKD to delay progression and improve clinical outcomes. This paper reports the protocol for the codesign, implementation and evaluation of a technological platform called Future Health Today (FHT), a software program that aims to optimise early detection and management of CKD in general practice. FHT aims to optimise clinical decision making and reduce practice variation by translating evidence into practice in real time and as a part of quality improvement activities. This protocol describes the co-design and plans for implementation and evaluation of FHT in two general practices invited to test the prototype over 12 months. Service design thinking has informed the design phase and mixed methods will evaluate outcomes following implementation of FHT. Through systematic application of co-design with service users, clinicians and digital technologists, FHT attempts to avoid the pitfalls of past studies that have failed to accommodate the complex requirements and dynamics that can arise between researchers and service users and improve chronic disease management through use of health information technology.

High intraluminal pressure promotes vascular inflammation via caveolin-1.

The aetiology and progression of hypertension involves various endogenous systems, such as the renin angiotensin system, the sympathetic nervous system, and endothelial dysfunction. Recent data suggest that vascular inflammation may also play a key role in the pathogenesis of hypertension. This study sought to determine whether high intraluminal pressure results in vascular inflammation. Leukocyte adhesion was assessed in rat carotid arteries exposed to 1 h of high intraluminal pressure. The effect of intraluminal pressure on signaling mechanisms including reactive oxygen species production (ROS), arginase expression, and NFĸB translocation was monitored. 1 h exposure to high intraluminal pressure (120 mmHg) resulted in increased leukocyte adhesion and inflammatory gene expression in rat carotid arteries. High intraluminal pressure also resulted in a downstream signaling cascade of ROS production, arginase expression, and NFĸB translocation. This process was found to be angiotensin II-independent and mediated by the mechanosensor caveolae, as caveolin-1 (Cav1)-deficient endothelial cells and mice were protected from pressure-induced vascular inflammatory signaling and leukocyte adhesion. Cav1 deficiency also resulted in a reduction in pressure-induced glomerular macrophage infiltration in vivo. These findings demonstrate Cav1 is an important mechanosensor in pressure-induced vascular and renal inflammation.

Future Health Today: codesign of an electronic chronic disease quality improvement tool for use in general practice using a service design approach.

OBJECTIVE: To codesign an electronic chronic disease quality improvement tool for use in general practice. DESIGN: Service design employing codesign strategies. SETTING: General practice. PARTICIPANTS: Seventeen staff (general practitioners, nurses and practice managers) from general practice in metropolitan Melbourne and regional Victoria and five patients from metropolitan Melbourne. INTERVENTIONS: Codesign sessions with general practice staff, using a service design approach, were conducted to explore key design criteria and functionality of the audit and feedback and clinical decision support tools. Think aloud interviews were conducted in which participants articulated their thoughts of the resulting Future Health Today (FHT) prototype as they used it. One codesign session was held with patients. Using inductive and deductive coding, content and thematic analyses explored the development of a new technological platform and factors influencing implementation of the platform. RESULTS: Participants identified that the prototype needed to work within their existing workflow to facilitate automated patient recall and track patients with or at-risk of specific conditions. It needed to be simple, provide visual snapshots of information and easy access to relevant guidelines and facilitate quality improvement activities. Successful implementation may be supported by: accuracy of the algorithms in FHT and data held in the practice; the platform supporting planned and spontaneous interactions with patients; the ability to hide tools; links to Medicare Benefits Schedule; and prefilled management plans. Participating patients supported the use of the platform in general practice. They suggested that use of the platform demonstrates a high level of patient care and could increase patient confidence in health practitioners. CONCLUSION: Study participants worked together to design a platform that is clear, simple, accurate and useful and that sits within any given general practice setting. The resulting FHT platform is currently being piloted in general practices and will continue to be refined based on user feedback.

Nitroxyl (HNO) reduces endothelial and monocyte activation and promotes M2 macrophage polarization.

Nitroxyl anion (HNO) donors are currently being assessed for their therapeutic utility in several cardiovascular disorders including heart failure. Here, we examine their effect on factors that precede atherosclerosis including endothelial cell and monocyte activation, leucocyte adhesion to the endothelium and macrophage polarization. Similar to the NO donor glyceryl trinitrate (GTN), the HNO donors Angeli's salt (AS) and isopropylamine NONOate (IPA/NO) decreased leucocyte adhesion to activated human umbilical vein endothelial cells (HUVECs) and mouse isolated aorta. This reduction in adhesion was accompanied by a reduction in intercellular adhesion molecule-1 (ICAM-1) and the cytokines monocyte chemoattractant protein 1 (MCP-1) and interleukin 6 (IL-6) which was inhibitor of nuclear factor κB (NFκB) α (IκBα)- and subsequently NFκB-dependent. Intriguingly, the effects of AS on leucocyte adhesion, like those on vasodilation, were found to not be susceptible to pharmacological tolerance, unlike those observed with GTN. As well, HNO reduces monocyte activation and promotes polarization of M2 macrophages. Taken together, our data demonstrate that HNO donors can reduce factors that are associated with and which precede atherosclerosis and may thus be useful therapeutically. Furthermore, since the effects of the HNO donors were not subject to tolerance, this confers an additional advantage over NO donors.

Compound 21, a selective agonist of angiotensin AT2 receptors, prevents endothelial inflammation and leukocyte adhesion in vitro and in vivo.

BACKGROUND AND PURPOSE: Angiotensin AT2 receptors are upregulated in disease states such as atherosclerosis and blockade of the AT2 receptors exacerbates plaque formation. Direct stimulation of these receptors is anti-atherogenic but the mechanisms and pathways involved remain unknown. We examined the effect of direct AT2 receptor stimulation with Compound 21 (C21) on the leukocyte adhesion cascade in vitro, right through to plaque formation in vivo. EXPERIMENTAL APPROACH: Effects of C21 on TNFα-induced inflammation were assessed in human umbilical vein endothelial cells (HUVECs), activation of monocytes, polarisation of monocyte-derived macrophages and in intact mouse aortae. KEY RESULTS: C21 attenuated TNFα-induced: monocyte adhesion to cultured HUVECs, adhesion molecule expression and abolished TNFα-induced ROS production. TNFα-induced NFκB translocation from the cytoplasm to the nucleus, essential for cytokine production, was prevented by C21. C21 did not influence monocyte activation or macrophage polarisation but did reduce TNFα and IL-6 mRNA expression in M1 macrophages. The anti-inflammatory effects of C21 were abolished by an AT2 receptor antagonist confirming that the effects of C21 were AT2 receptor-mediated. Also, leukocyte adhesion and cytokine gene expression, induced by high-fat diet (HFD), was attenuated in ApoE(-/-) mice treated with C21. Plaque size and stability were improved with C21 treatment with increased smooth muscle cell composition and decreased lipid size, compared with HFD-saline treated mice. CONCLUSION AND IMPLICATIONS: C21 prevented TNFα-induced and HFD-induced vascular inflammation in vitro and in vivo. Our data provide strong evidence that the anti-atherosclerotic actions of C21 were due to vascular anti-inflammatory effects, mediated by AT2 receptors.

Nitroxyl: a vasodilator of human vessels that is not susceptible to tolerance.

Pre-clinical studies have identified nitroxyl (HNO), the reduced congener of nitric oxide (NO•), as a potent vasodilator which is resistant to tolerance development. The present study explores the efficacy of HNO in human blood vessels and describes, for the first time, a vasodilator for humans that is not susceptible to tolerance. Human radial arteries and saphenous veins were obtained from patients undergoing coronary artery graft surgery and mounted in organ baths. Repeated vasodilator responses to the HNO donor Angeli's salt (AS) and NO• donor glyceryl trinitrate (GTN) were determined. AS- and GTN-induced concentration-dependent vasorelaxation of both human radial arteries (AS pEC50: 6.5 ± 0.2; -log M) and saphenous veins (pEC50: 6.7 ± 0.1) with similar potency. In human radial arteries, GTN-induced relaxation was reduced by the NO• scavenger hydroxocobalamin (HXC; P<0.05) but was unaffected by the HNO scavenger L-cysteine. Alternately, AS was unaffected by HXC but was reduced by L-cysteine (5-fold shift, P<0.05). The sGC (soluble guanylate cyclase) inhibitor ODQ abolished responses to both AS and GTN in arteries and veins (P<0.05). Inhibition of voltage-dependent potassium channels (Kv channels) with 4-AP also significantly reduced responses to AS (pEC50: 5.5) and GTN, suggesting that the relaxation to both redox congeners is cGMP- and Kv channel-dependent. Critically, a concentration-dependent development of tolerance to GTN (1 and 10 µM; P<0.05), but not to AS, was observed in both saphenous veins and radial arteries. Like GTN, the HNO donor AS causes vasorelaxation of human blood vessels via activation of a cGMP-dependent pathway. Unlike GTN, however, it does not develop tolerance in human blood vessels.

Endothelial C-type natriuretic peptide maintains vascular homeostasis.

The endothelium plays a fundamental role in maintaining vascular homeostasis by releasing factors that regulate local blood flow, systemic blood pressure, and the reactivity of leukocytes and platelets. Accordingly, endothelial dysfunction underpins many cardiovascular diseases, including hypertension, myocardial infarction, and stroke. Herein, we evaluated mice with endothelial-specific deletion of Nppc, which encodes C-type natriuretic peptide (CNP), and determined that this mediator is essential for multiple aspects of vascular regulation. Specifically, disruption of CNP leads to endothelial dysfunction, hypertension, atherogenesis, and aneurysm. Moreover, we identified natriuretic peptide receptor-C (NPR-C) as the cognate receptor that primarily underlies CNP-dependent vasoprotective functions and developed small-molecule NPR-C agonists to target this pathway. Administration of NPR-C agonists promotes a vasorelaxation of isolated resistance arteries and a reduction in blood pressure in wild-type animals that is diminished in mice lacking NPR-C. This work provides a mechanistic explanation for genome-wide association studies that have linked the NPR-C (Npr3) locus with hypertension by demonstrating the importance of CNP/NPR-C signaling in preserving vascular homoeostasis. Furthermore, these results suggest that the CNP/NPR-C pathway has potential as a disease-modifying therapeutic target for cardiovascular disorders.

Raised soluble P-selectin moderately accelerates atherosclerotic plaque progression.

Soluble P-selectin (sP-selectin), a biomarker of inflammatory related pathologies including cardiovascular and peripheral vascular diseases, also has pro-atherosclerotic effects including the ability to increase leukocyte recruitment and modulate thrombotic responses in vivo. The current study explores its role in progressing atherosclerotic plaque disease. Apoe-/- mice placed on a high fat diet (HFD) were given daily injections of recombinant dimeric murine P-selectin (22.5 µg/kg/day) for 8 or 16 weeks. Saline or sE-selectin injections were used as negative controls. In order to assess the role of sP-selectin on atherothrombosis an experimental plaque remodelling murine model, with sm22α-hDTR Apoe-/- mice on a HFD in conjunction with delivery of diphtheria toxin to induce targeted vascular smooth muscle apoptosis, was used. These mice were similarly given daily injections of sP-selectin for 8 or 16 weeks. While plaque mass and aortic lipid content did not change with sP-selectin treatment in Apoe-/- or SM22α-hDTR Apoe-/- mice on HFD, increased plasma MCP-1 and a higher plaque CD45 content in Apoe-/- HFD mice was observed. As well, a significant shift towards a more unstable plaque phenotype in the SM22α-hDTR Apoe-/- HFD mice, with increased macrophage accumulation and lower collagen content, leading to a lower plaque stability index, was observed. These results demonstrate that chronically raised sP-selectin favours progression of an unstable atherosclerotic plaque phenotype.

Near-infrared spectroscopy of the thenar eminence to estimate forearm blood flow.

BACKGROUND: Near-infrared spectroscopy of the thenar eminence (NIRSth) can be used at the bedside to assess tissue oxygenation (StO2), the reperfusion response to ischaemia and the tissue haemoglobin index (THI). Its ability to estimate forearm blood flow (FBF) has not previously been assessed. OBJECTIVES: We aimed to test whether short-lived venous occlusion-induced changes in NIRSth-derived THI (ΔTHI/ minute) correlate with strain gauge plethysmography (SGP) measurements. METHODS: We measured FBF in nine volunteers with SGP by venous occlusion, while estimating ΔTHI. Measurements were obtained in two forearm positions (elevated and horizontal) at baseline and during induced hyperaemia. RESULTS: We performed 246 paired measurements at rest and after occlusion-induced hyperaemia. At rest, mean SGP-estimated FBF was 3.5-3.6 mL/dL/minute at baseline, compared with 12.9-13.6 mL/dL/minute during hyperaemia. At rest, ΔTHI was 6.1-8.2/minute, compared with 29.7-32.5/minute during hyperaemia. ΔTHI was a significant predictor of SGP FBF (P < 0.01), with stronger correlation during hyperaemia (P < 0.01). An equation was developed to convert ΔTHI/minute into FBF at mL/dL/minute (FBF = 0.362 ΔTHI/minute + 0.864). CONCLUSIONS: NIRSth can be used to estimate FBF. Given its portability and its ability to also measure StO2 and vascular reactivity, NIRSth can assist in providing a comprehensive bedside assessment of the forearm circulation in critically ill patients.

Endothelial dysfunction in patients with type 2 diabetes post acute coronary syndrome.

UNLABELLED: This single visit study examined whether endothelial function, in addition to cardiovascular (CV) risk factors and plasma microparticle content, was normalised in 15 patients with type 2 diabetes + acute coronary syndrome (ACS) (6 weeks-6 months post cardiac event) undergoing standard clinical care compared to 16 sex- and age-matched healthy controls. RESULTS: While total and low-density lipoprotein (LDL) cholesterol levels were well controlled in the patients with type 2 diabetes + ACS, residual CV risk profiles such as increased body mass index (BMI), systolic blood pressure, glucose levels and triglycerides and lower high-density lipoprotein (HDL) levels were still apparent. Endothelium-dependent responses to acetylcholine (ACh) were significantly lower in type 2 diabetes + ACS patients compared to controls. Correspondingly, the reactive hyperaemic index (RHI) was lower in the patient cohort. Endothelial microparticle (EMP) levels (CD31(+), CD41(-)) were 40% lower in the patient cohort. Simultaneous analysis of platelet microparticle (PMP) levels (CD41(+)) showed no difference between cohorts. CONCLUSIONS: Patients with type 2 diabetes suffering from recent ACS exhibit residual CV risk factors despite being on standard clinical care. In addition, these patients continue to present with endothelial dysfunction despite having lower levels of EMPs.

C-type natriuretic peptide (CNP): cardiovascular roles and potential as a therapeutic target.

Natriuretic peptides play a fundamental role in cardiovascular homeostasis by modulation of fluid and electrolyte balance and vascular tone. C-type natriuretic peptide (CNP) represents the paracrine element of the natriuretic peptide axis which complements the endocrine actions of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). CNP is produced by the endothelium and the heart and appears to play a prominent role in vascular and cardiac function, both physiologically and pathologically. This provides a rationale for the therapeutic potential of pharmacological interventions targeted to CNP signalling. This article provides an overview of the biology and pharmacology of CNP, with emphasis on the cardiovascular system, and discusses pathologies in which drugs designed to manipulate CNP signalling maybe of clinical benefit.

Omega-conotoxin GVIA mimetics based on an anthranilamide core: effect of variation in ammonium side chain lengths and incorporation of fluorine.

A number of omega-conotoxin GVIA mimetics based on an anthranilamide core were prepared and tested for their affinity for rat brain Ca(v)2.2 channels. Features such as the presence of hydroxyl and fluoro substituents on the tyrosine side chain mimic, the length of the chains on the lysine/arginine side chain mimics and the use of diguanidino and diamino substituents rather than mono-guanidine/mono-amine substitution were examined. The diguanidinylated compounds proved to be the most active and deletion of the hydroxyl substituent had a limited influence on activity. The SAR associated with variation in the lysine/arginine side chain mimics was not strong. The introduction of a fluoro substituent into the tyrosine mimic produced the most active compound prepared in this study (2g), with an EC(50) at rat brain Ca(v)2.2 channels of 6 microM.

Low molecular weight non-peptide mimics of omega-conotoxin GVIA.

We report the synthesis and biological activity of a low molecular weight non-peptidic mimic of the analgesic peptide omega-conotoxin GVIA. The molecular weight of this compound presents a reduction by 193g/mol compared to a previously reported lead. This compound exhibits an EC(50) of 5.8microM and is accessible in only six synthetic steps compared to the original lead (13 steps). We also report several improvements to the original synthetic route.

Conopressin-T from Conus tulipa reveals an antagonist switch in vasopressin-like peptides.

We report the discovery of conopressin-T, a novel bioactive peptide isolated from Conus tulipa venom. Conopressin-T belongs to the vasopressin-like peptide family and displays high sequence homology to the mammalian hormone oxytocin (OT) and to vasotocin, the endogenous vasopressin analogue found in teleost fish, the cone snail's prey. Conopressin-T was found to act as a selective antagonist at the human V 1a receptor. All peptides in this family contain two conserved amino acids within the exocyclic tripeptide (Pro7 and Gly9), which are replaced with Leu7 and Val9 in conopressin-T. Whereas conopressin-T binds only to OT and V 1a receptors, an L7P analogue had increased affinity for the V 1a receptor and weak V2 receptor binding. Surprisingly, replacing Gly9 with Val9 in OT and vasopressin revealed that this position can function as an agonist/antagonist switch at the V 1a receptor. NMR structures of both conopressin-T and L7P analogue revealed a marked difference in the orientation of the exocyclic tripeptide that may serve as templates for the design of novel ligands with enhanced affinity for the V 1a receptor.

Isolation and characterization of rufoxin, a novel protein exhibiting neurotoxicity from venom of the psammophiine, Rhamphiophis oxyrhynchus (Rufous beaked snake).

Colubrid snake venoms potentially represent a vast source of novel biological actives and structural motifs owing to their diverse phylogeny. The present study describes the identification of rufoxin, a neurotoxin from the venom of Rhamphiophis oxyrhynchus (Rufous beaked snake) which is a member of the African colubrid lineage, the psammophiines. Rufoxin (1 microM) displayed reversible post-synaptic neurotoxic activity as evidenced by significant inhibition of indirect twitches and responses to exogenous nicotinic agonists in the chick biventer cervicis nerve-muscle preparation. Rufoxin (0.1-1.0 microM) also caused a rightward parallel shift of cumulative concentration-response curves to carbachol (CCh; 0.6-80 microM) without a significant depression of the maximum response, suggestive of classical competitive antagonism at the skeletal muscle nicotinic receptor. Rufoxin lacks NH(2)-terminal sequence homology to previously identified snake venom toxins. This work indicates a wider distribution of neurotoxins across the advanced snake superfamily than previously described.