Continuous Positive Airway Pressure plus Mandibular Advancement Therapy (PAPMAT): study protocol for an adaptive randomised crossover trial comparing the benefits and costs of combining two established treatments for obstructive sleep apnoea.

BACKGROUND: Obstructive sleep apnoea (OSA) involves repeated breathing pauses during sleep due to upper airway obstruction. It causes excessive daytime sleepiness and has other health impacts. Continuous positive airway pressure (CPAP) therapy is effective first line treatment for moderate to severe OSA. Unfortunately, many patients have difficulty tolerating CPAP and pressure intolerance is probably an important contributing factor. Mandibular advancement devices (MAD) are an alternative to CPAP. They are worn in the mouth during sleep to reduce airway obstruction. There is some evidence that, when used in combination with CPAP, MADs improve airway anatomy enough to reduce the CPAP pressure required to treat OSA and that this combination therapy could improve CPAP adherence. METHODS: Consecutive patients starting on CPAP for moderate to severe OSA will be recruited at a regional NHS sleep service. Patients with high CPAP pressure requirements after initial titration, who satisfy all entry criteria and consent to participate, will undertake a 2-arm randomised crossover trial. The arms will be (i) standalone CPAP and (ii) CPAP + MAD therapy. Each arm will last 12 weeks, including 2 weeks acclimatisation. CPAP machines will be auto-titrating and with facility for data download, so the impact of MAD on CPAP pressure requirements and CPAP adherence can be easily measured. The primary outcome will be CPAP adherence. Secondary outcomes will include measures of OSA severity, patient-reported outcome measures including subjective daytime sleepiness, quality of life, and treatment preference at the trial exit and health service use. Cost-effectiveness analyses will be undertaken. DISCUSSION: If the intervention is shown to be effective and cost-effective in improving adherence in this standard CPAP-eligible OSA patient population it would be relatively straightforward to introduce into existing OSA treatment pathways, within the wider NHS and more widely. Both MAD and CPAP are already used by sleep services so their combination would require only minor adjustments to existing clinical pathways. It would be straightforward to disseminate the results of the study through regional, national, and international respiratory meetings. The health economics analysis would provide cost-effectiveness data to inform service planning and clinical guidelines through policy briefing papers, including those by NICE and SIGN. TRIAL REGISTRATION: PAPMAT was registered with ISRCTN prior to recruitment beginning (ISRCTN Registry 2021): https://www.isrctn.com/ISRCTN33966032 . Registered on 17th November 2021.

Comparison of mathematically arterialised venous blood gas sampling with arterial, capillary, and venous sampling in adult patients with hypercapnic respiratory failure: a single-centre longitudinal cohort study.

BACKGROUND: Accurate arterial blood gas (ABG) analysis is essential in the management of patients with hypercapnic respiratory failure, but repeated sampling requires technical expertise and is painful. Missed sampling is common and has a negative impact on patient care. A newer venous to arterial conversion method (v-TAC, Roche) uses mathematical models of acid-base chemistry, a venous blood gas sample and peripheral blood oxygen saturation to calculate arterial acid-base status. It has the potential to replace routine ABG sampling for selected patient cohorts. The aim of this study was to compare v-TAC with ABG, capillary and venous sampling in a patient cohort referred to start non-invasive ventilation (NIV). METHODS: Recruited patients underwent near simultaneous ABG, capillary blood gas (CBG) and venous blood gas (VBG) sampling at day 0, and up to two further occasions (day 1 NIV and discharge). The primary outcome was the reliability of v-TAC sampling compared with ABG, via Bland-Altman analysis, to identify respiratory failure (via PaCO2) and to detect changes in PaCO2 in response to NIV. Secondary outcomes included agreements with pH, sampling success rates and pain. RESULTS: The agreement between ABG and v-TAC/venous PaCO2 was assessed for 119 matched sampling episodes and 105 between ABG and CBG. Close agreement was shown for v-TAC (mean difference (SD) 0.01 (0.5) kPa), but not for CBG (-0.75 (0.69) kPa) or VBG (+1.00 (0.90) kPa). Longitudinal data for 32 patients started on NIV showed the closest agreement for ABG and v-TAC (R2=0.61). v-TAC sampling had the highest first-time success rate (88%) and was less painful than arterial (p<0.0001). CONCLUSION: Mathematical arterialisation of venous samples was easier to obtain and less painful than ABG sampling. Results showed close agreement for PaCO2 and pH and tracked well longitudinally such that the v-TAC method could replace routine ABG testing to recognise and monitor patients with hypercapnic respiratory failure. TRIAL REGISTRATION NUMBER: NCT04072848; www. CLINICALTRIALS: gov.

CASPA (CArdiac Sarcoidosis in PApworth) improving the diagnosis of cardiac involvement in patients with pulmonary sarcoidosis: protocol for a prospective observational cohort study.

INTRODUCTION: Sarcoidosis is a multisystem disease, predominantly affecting the lungs but can involve the heart, resulting in cardiac sarcoidosis (CS). Patients require MRI/Positron Emission Tomography (PET) scans for diagnosis. Echocardiography, ECG and Holter monitoring may be indicative but not diagnostic alone. Patients can present late with conduction defects, heart failure or sudden death. The CASPA (CArdiac Sarcoidosis in PApworth) study protocol aims to (1) use MRI to identify CS prevalence; (2) use speckle-tracking echocardiography, signal averaged ECG and Holter monitoring to look for diagnostic pathways; and (3) identify serum proteins which may be associated with CS. METHODS AND ANALYSIS: Participants with pulmonary sarcoidosis (and no known cardiac disease) from Royal Papworth Hospital will have the following: cardiac MRI with late gadolinium, two-dimensional transthoracic echocardiography with speckle tracking, signal averaged ECG and 24-hour Holter monitor. They will provide a serum sample for brain natriuretic peptide levels and proteomics by liquid chromatography coupled to high-resolution mass spectrometry. All data will be collected on OpenClinica platform and analysed approximately 6 months after final patient recruitment. ETHICS AND DISSEMINATION: The Camden & Kings Cross Research Ethics Committee approved the protocol (REC number: 17/LO/0667). Integrated Research Approval System (IRAS) 222 720. Dissemination of findings will be via conference presentations and submitted to peer-reviewed journals.

Amaze: a double-blind, multicentre randomised controlled trial to investigate the clinical effectiveness and cost-effectiveness of adding an ablation device-based maze procedure as an adjunct to routine cardiac surgery for patients with pre-existing atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) can be treated using a maze procedure during planned cardiac surgery, but the effect on clinical patient outcomes, and the cost-effectiveness compared with surgery alone, are uncertain. OBJECTIVES: To determine whether or not the maze procedure is safe, improves clinical and patient outcomes and is cost-effective for the NHS in patients with AF. DESIGN: Multicentre, Phase III, pragmatic, double-blind, parallel-arm randomised controlled trial. Patients were randomised on a 1 : 1 basis using random permuted blocks, stratified for surgeon and planned procedure. SETTING: Eleven acute NHS specialist cardiac surgical centres. PARTICIPANTS: Patients aged ≥ 18 years, scheduled for elective or in-house urgent cardiac surgery, with a documented history (> 3 months) of AF. INTERVENTIONS: Routine cardiac surgery with or without an adjunct maze procedure administered by an AF ablation device. MAIN OUTCOME MEASURES: The primary outcomes were return to sinus rhythm (SR) at 12 months and quality-adjusted life-years (QALYs) over 2 years after randomisation. Secondary outcomes included return to SR at 2 years, overall and stroke-free survival, drug use, quality of life (QoL), cost-effectiveness and safety. RESULTS: Between 25 February 2009 and 6 March 2014, 352 patients were randomised to the control (n = 176) or experimental (n = 176) arms. The odds ratio (OR) for return to SR at 12 months was 2.06 [95% confidence interval (CI) 1.20 to 3.54; p = 0.0091]. The mean difference (95% CI) in QALYs at 2 years between the two trial arms (maze/control) was -0.025 (95% CI 0.129 to 0.078; p = 0.6319). The OR for SR at 2 years was 3.24 (95% CI 1.76 to 5.96). The number of patients requiring anticoagulant drug use was significantly lower in the maze arm from 6 months after the procedure. There were no significant differences between the two arms in operative or overall survival, stroke-free survival, need for cardioversion or permanent pacemaker implants, New York Heart Association Functional Classification (for heart failure), EuroQol-5 Dimensions, three-level version score and Short Form questionnaire-36 items score at any time point. Sixty per cent of patients in each trial arm had a serious adverse event (p = 1.000); most events were mild, but 71 patients (42.5%) in the maze arm and 84 patients (45.5%) in the control arm had moderately severe events; 31 patients (18.6%) in the maze arm and 38 patients (20.5%) in the control arm had severe events. The mean additional cost of the maze procedure was £3533 (95% CI £1321 to £5746); the mean difference in QALYs was -0.022 (95% CI -0.1231 to 0.0791). The maze procedure was not cost-effective at £30,000 per QALY over 2 years in any analysis. In a small substudy, the active left atrial ejection fraction was smaller than that of the control patients (mean difference of -8.03, 95% CI -12.43 to -3.62), but within the predefined clinically equivalent range. LIMITATIONS: Low recruitment, early release of trial summaries and intermittent resource-use collection may have introduced bias and imprecise estimates. CONCLUSIONS: Ablation can be practised safely in routine NHS cardiac surgical settings and increases return to SR rates, but not survival or QoL up to 2 years after surgery. Lower anticoagulant drug use and recovery of left atrial function support anticoagulant drug withdrawal provided that good atrial function is confirmed. FURTHER WORK: Continued follow-up and long-term clinical effectiveness and cost-effectiveness analysis. Comparison of ablation methods. TRIAL REGISTRATION: Current Controlled Trials ISRCTN82731440. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 19. See the NIHR Journals Library website for further project information.

Bone marrow-derived smooth muscle-like cells are infrequent in advanced primary atherosclerotic plaques but promote atherosclerosis.

OBJECTIVE: Although vascular smooth muscle cells (VSMCs) provide the major structural integrity of atherosclerotic plaques, their origin has been questioned. In particular, although some studies identified plaque VSMCs originating from bone marrow or peripheral blood, their frequency is controversial and their function unknown. We used genetic tracking of cell fate through smooth muscle cell (SMC)-specific LacZ reporter activity and VSMC-selective apoptosis to investigate the frequency, distribution, and role of marrow-derived VSMCs in atherogenesis. METHODS AND RESULTS: Cultured mouse bone marrow-derived smooth muscle-like cells expressed SMC markers and functional SMC promoter-driven transgenes over time. Transplantation of apolipoprotein E (ApoE)(-/-) mice with smooth muscle myosin heavy chain-Cre/ROSA26R/ApoE(-/-) marrow showed that 0.7±0.14% cells expressed LacZ in atherosclerotic plaques, located superficially in early plaques, and in necrotic cores but not fibrous caps of advanced lesions. Cells expressing both progenitor and SMC markers showed a similar distribution and frequency. Apoptosis of marrow-derived SMC-like cells transplanted from SM22α-human diphtheria toxin receptor/ApoE(-/-) mice retarded atherogenesis, with reduced plaque macrophage content. Cultured marrow-derived SMC-like cells secreted proinflammatory cytokines and promoted macrophage migration, VSMC proliferation, and collagen synthesis. CONCLUSION: Bone marrow-derived SMC-like cells are infrequent in advanced primary atherosclerotic plaques and absent in fibrous caps. However, these cells secrete proinflammatory cytokines and mitogens and promote atherosclerosis.

Role of Fas/Fas-L in vascular cell apoptosis.

Apoptosis of vascular cells is observed in vivo in normal vessel development and a variety of vascular pathologies. Apoptosis occurs in all cell types within the vessel wall, the consequences of which depend on both cell type and the pathology under study. The death receptor Fas is expressed throughout the vessel wall, and increasingly Fas-Fas-L-induced killing has been recognized in the vasculature. This review outlines the current developments in understanding the role, regulation, and consequences of Fas-Fas-L-induced apoptosis in vascular cells.

Monocyte/macrophage suppression in CD11b diphtheria toxin receptor transgenic mice differentially affects atherogenesis and established plaques.

Although monocytes/macrophages are considered important in atherogenesis, their role in established plaques is unclear. For example, macrophage content is associated with plaque instability, but their loss through cell death is observed at sites of plaque rupture. To examine the role of monocytes/macrophages in atherosclerosis, we developed CD11b-diphtheria toxin (DT) receptor (DTR) transgenic mice, whereby administration of DT selectively kills monocytes/macrophages. DT treatment reduced peripheral blood monocytes and tissue macrophages and inhibited macrophage function in CD11b-DTR mice and apolipoprotein E-null (apoE(-/-)) mice transplanted with CD11b-DTR bone marrow. In atherogenesis experiments, DT markedly reduced plaque development and altered plaque composition, reducing collagen content and necrotic core formation. In mice with established plaques, acute DT treatment induced macrophage apoptosis and reduced macrophage content but did not induce plaque inflammation, thrombosis, or rupture. Furthermore, despite a 50% reduction in monocytes, chronic DT treatment of these mice did not alter plaque extent or composition, most likely because of ongoing recruitment/proliferation of monocytes with recovery of macrophage content. We conclude that monocytes/macrophages are critical to atherogenesis, but established plaques are more resistant to reductions in monocytes.

Endothelin-mediated vasoconstriction in early atherosclerosis is markedly increased in ApoE-/- mouse but prevented by atorvastatin.

We have discovered that endothelin-1 (ET-1) vasoconstriction is significantly enhanced in aortas of young (8-16-week-old) apolipoprotein E-deficient (ApoE-/-) mice devoid of atherosclerotic lesions (maximum response expressed as a percentage of the mean response to 100 mM KCl (E(MAX)) = 55.7% +/- 19.5% KCl, n = 5) compared to age-matched C57BL/6/J control animals (E(MAX) = 12.6% +/- 2.5% KCl, n = 8), indicating that alterations in the endothelin system may contribute to disease progression, at least in this animal model. There was no difference in the potency of ET-1 to contract aorta from the two groups (C57BL/6/J pD2 = 8.74 +/- 0.30; ApoE-/- pD2 = 8.50 +/- 0.15, P > 0.05). This increased response was specific to ET-1, as it was not observed with phenylephrine or U46619, nor was it due to a non-receptor mediated increase in contractile sensitivity, as there was no change in response to KCl between the two groups. [125I]ET-1 bound with subnanomolar affinity (K(D)) to aorta (K(D) = 0.018 +/- 0.002 nM, n = 4) and, with an order of magnitude lower affinity, to heart (K(D) = 0.47 +/- 0.05, n = 5) of C57BL/6/J mice with binding densities (B(MAX)) of 9.3 +/- 2.4 fmol mg(-1)protein and 100 +/- 14 fmol mg(-1) protein, respectively. Alterations in vascular reactivity to ET-1 could not be explained by increased endothelin receptor density or affinity, as these were not altered in aorta (K(D) = 0.011 +/- 0.003 nM; B(MAX) = 10.1 +/- 3.9 fmol mg(-1), n = 4) and heart (K(D) = 0.43 +/- 0.04 nM; B(MAX) = 115 +/- 26 fmol mg(-1), n == 6) of ApoE-/- animals. The ratio of ET(A) to ET(B) receptors in heart of control and ApoE-/- mice was similar, comprising 89% and 85% ET(A) receptors, respectively. In isolated aorta from ApoE-/- mice on the Western diet, which more closely resembled more advanced stages of the disease in man, the augmented ET-1 vasoconstrictor response was maintained (E(MAX) = 25.2% +/- 6.8% KCl, n = 9); however, it was completely prevented in animals that had received 10 weeks of oral atorvastatin (30 mg kg(-1) day(-1)) (E(MAX) = 4.0% +/- 1.5% KCl, n = 5), a concentration that was chosen because it did not affect plasma cholesterol and triglyceride levels. Therefore, this protective prevention of enhanced ET-1 vasoconstriction in ApoE-/- mice by atorvastatin was independent of its lipid-lowering properties.

Interferon-gamma induces Fas trafficking and sensitization to apoptosis in vascular smooth muscle cells via a PI3K- and Akt-dependent mechanism.

Vascular smooth muscle cell (VSMC) apoptosis occurs in advanced atherosclerotic plaques where it may contribute to plaque instability. VSMCs express the death receptor Fas but are relatively resistant to Fas-induced apoptosis due in part to the intracellular sequestration of Fas. Although inflammatory cytokines such as interferon (IFN)-gamma present in plaques can prime VSMCs to FasL-induced death, the mechanism of this effect is unclear. We examined Fas expression and FasL-induced apoptosis in human VSMCs in response to IFN-gamma. IFN-gamma induced Fas trafficking to the cell surface within 24 hours, an effect that required Jak2/Stat1 activity. IFN-gamma also stimulated Akt activity, and both Fas trafficking and Stat1 activation were inhibited by blocking PI3K, Akt, or Jak-2. IFN-gamma increased Fas-induced apoptosis in vitro by 46 +/- 8% (mean +/- SEM, P = 0.04), an event that could be abrogated by inhibition of PI3K, Akt, or Jak-2. IFN-gamma also increased Fas-induced apoptosis in vivo 7.5- to 15-fold (P < 0.05) in human arteries transplanted into immunodeficient mice, accompanied by increased Fas and phospho-Ser727-Stat1. We conclude that IFN-gamma primes VSMCs to Fas-induced apoptosis, in part by relocation of Fas to the cell surface, a process that involves PI3K, Akt, and Jak-2/Stat1. IFN-gamma present in plaques may co-operate with FasL to induce VSMC apoptosis in atherosclerosis.

Isolation of genes controlling apoptosis through their effects on cell survival.

The identification of the most suitable molecular targets for gene and drug therapy is the crucial first step in the development of new disease treatments. The rational identification of such targets depends on a detailed understanding of the pathological changes occuring at the molecular level. We have applied forward genetics approaches to the identification of the critical genes involved in the control of apoptosis in mammalian cells, since defective control of apoptosis underlies many diseases, including cancer and neurodegenerative diseases. We have identified two groups of genes by their effects on cell survival using retroviral cDNA functional expression cloning and retroviral insertional mutagenesis. The identification of these novel genes opens up new areas for apoptosis research and subsequently for the development of new gene and drug therapies.

Endogenous p53 protects vascular smooth muscle cells from apoptosis and reduces atherosclerosis in ApoE knockout mice.

Recent studies have indicated that the tumor suppressor gene p53 limits atherosclerosis in animal models; p53 expression is also increased in advanced human plaques compared with normal vessels, where it may induce growth arrest and apoptosis. However, controversy exists as to the role of endogenous levels of p53 in different cell types that comprise plaques. We examined atherosclerotic plaque development and composition in brachiocephalic arteries and aortas of p53-/-/ApoE-/- mice versus wild type p53 controls. p53-/- mice demonstrated increased aortic plaque formation, with increased rates of cell proliferation and reduced rates of apoptosis in brachiocephalic arteries. Although most proliferating cells were monocyte/macrophages, apoptotic cells were both vascular smooth muscle cells (VSMCs) and macrophages. Transplant of p53 bone marrow to p53-/-/ApoE-/- mice reduced aortic plaque formation and cell proliferation in brachiocephalic plaques, but also markedly reduced apoptosis. To examine p53 regulation of these processes, we studied proliferation and apoptosis in macrophages, bone marrow stromal cells and VSMCs cultured from these mice. Although endogenous p53 promoted apoptosis in macrophages, it protected VSMCs and stromal cells from death, a hitherto unknown function in these cells, in part by inhibiting DNA damage response enzymes. p53 also inhibited stromal cell expression of VSMC markers. We conclude that endogenous levels of p53 protect VSMCs and stromal cells against apoptosis, while promoting apoptosis in macrophages, and protect against atherosclerosis development.

Role of apoptosis in atherosclerosis and its therapeutic implications.

Atherosclerotic plaques develop as a consequence of the accumulation of circulating lipid and the subsequent migration of inflammatory cells (macrophages and T-lymphocytes) and VSMCs (vascular smooth muscle cells). Advanced plaques consist of a lipid-rich core, separated from the lumen by a fibrous cap composed of VSMCs, collagen and extracellular matrix. Plaque enlargement ultimately narrows the lumen (stenosis) causing angina. However, recent studies have emphasized that acute coronary syndromes (unstable angina/myocardial infarction) are caused by lesion erosion/rupture with superimposed thrombus formation on often small non-stenotic plaques. Thus current therapies work predominantly on stabilization of plaques rather than plaque regression. Apoptosis (programmed cell death) is increasingly observed as plaques develop, although the exact mechanisms and consequences of apoptosis in the development and progression of atherosclerosis are still controversial. Increased endothelial cell apoptosis may initiate atherosclerosis, whereas apoptosis of VSMCs and macrophages localizes in 'vulnerable' lesions, i.e. those most likely to rupture, and at sites of rupture. This review will focus on the regulation of apoptosis of cells within the vasculature, concentrating on the relevance of apoptosis to plaque progression and clinical consequences of vascular cell apoptosis.