Tissue angiotensin II: a matter of location

Whether cardiac Ang IT generation occurs in an auto-, para-, or intracrine manner as well as whether Ang II stimulation of the AT 2 receptor mediates vasodilation, has not yet been thoroughly investigated. Therefore, we performed in-vivo studies in rats and pigs and in-vitro studies in porcine isolated vessels with the following aims: 1. To study the vasoactive role of AT2 receptors under normal and pathological conditions, as well as to investigate which vasodilator compounds counterbalance Ang II -mediated vasoconstriction. 2. To determine the site oflocal Ang II formation, and the enzyme(s) (ACE and/or chymase) involved in its generation. To address issue 1, we made use of the radioactive nricrosphere method under various conditions, which allowed us to measure blood flow in all organs of one animal. In normal anesthetized rats, blood flow was measured during Ang IT infusion in the absence or presence of antagonists at AT1 or ATz receptors (chapter 2) and following inhibition of nitric oxide synthase or cyclooxygenase (chapter 3 ). Shnilar studies were performed in rats 4 weeks after coronary artery ligation, i.e, at the time when ATz receptors are upregulated (chapter 4). To address issue 2, a detailed analysis of cardiac angiotensin generation was made in myocardial infarcted pigs with and without RAS blockade (chapter 5). Interstitial Ang I and Ang II levels were measured in porcine hearts in vivo, using the microdialysis technique, (chapter 6) and in isolated porcine arteries (chapters 7). Finally, the enzyme responsible for interstitial Ang I-to-Ang ll conversion was determined using a modified version of the rat Langendorff heart, which allows separate collection of coronary effluent and interstitial fluid (chapter 8)

AT(2) receptor-mediated vasodilation in the heart: effect of myocardial infarction

To investigate the functional consequences of postinfarct cardiac angiotensin (ANG) type 2 (AT(2)) receptor upregulation, rats underwent coronary artery ligation or sham operation and were infused with ANG II 3-4 wk later, when scar formation is complete. ANG II increased mean arterial pressure (MAP) more modestly in infarcted animals than in sham animals. The AT(1) receptor antagonist ir

Angiotensin-converting enzyme inhibition and angiotensin II type 1 receptor blockade prevent cardiac remodeling in pigs after myocardial infarction: role of tissue angiotensin II

BACKGROUND: The mechanisms behind the beneficial effects of renin-angiotensin system blockade after myocardial infarction (MI) are not fully elucidated but may include interference with tissue angiotensin II (Ang II). METHODS AND RESULTS: Forty-nine pigs underwent coronary artery ligation or sham operation and were studied up to 6 weeks. To determine coronary angiotensin I (Ang I) to Ang II conversion and to distinguish plasma-derived Ang II from locally synthesized Ang II, (125)I-labeled and endogenous Ang I and II were measured in plasma and in infarcted and noninfarcted left ventricle (LV) during (125)I-Ang I infusion. Ang II type 1 (AT(1)) receptor-mediated uptake of circulating (125)I-Ang II was increased at 1 and 3 weeks in noninfarcted LV, and this uptake was the main cause of the transient elevation in Ang II levels in the noninfarcted LV at 1 week. Ang II levels and AT(1) receptor-mediated uptake of circulating Ang II were reduced in the infarct area at all time points. Coronary Ang I to Ang II conversion was unaffected by MI. Captopril and the AT(1) receptor antagonist eprosartan attenuated postinfarct remodeling, although both drugs increased cardiac Ang II production. Captopril blocked coronary conversion by >80% and normalized Ang II uptake in the noninfarcted LV. Eprosartan did not affect coronary conversion and blocked cardiac Ang II uptake by >90%. CONCLUSIONS: Both circulating and locally generated Ang II contribute to remodeling after MI. The rise in tissue Ang II production during angiotensin-converting enzyme inhibition and AT(1) receptor blockade suggests that the antihypertrophic effects of these drugs result not only from diminished AT(1) receptor stimulation but also from increased stimulation of growth-inhibitory Ang II type 2 receptors

Leidraad voor juridische auteurs. Voetnoten, bronvermeldingen, literatuurlijsten en afkortingen in Nederlandstalige publicaties

Manual on how to refer to sources in law publications written in Dutch. How to do footnotes, bibliographies, abbreviations etc.bookEffective Protection of Fundamental Rights in a pluralist worl

Leidraad voor juridische auteurs - Voetnoten, bronvermeldingen, literatuurlijsten en afkortingen in Nederlandstalige publicaties

Eighth edition of manual on how to refer to sources in law publications written in Dutch. How to do footnotes, bibliographies, abbreviations etc.bookFdR – Publicaties niet-programma gebonde

Leidraad voor juridische auteurs - Voetnoten, bronvermeldingen, literatuurlijsten en afkortingen in Nederlandstalige publicaties

Eighth edition of manual on how to refer to sources in law publications written in Dutch. How to do footnotes, bibliographies, abbreviations etc.</p

Shared decision-making for nonoperative management versus operative management of hip fractures in selected frail older adults with a limited life expectancy:a protocol for a nationwide implementation study

Background and purpose Recent research has highlighted non-operative management (NOM) as a viable alternative for frail older adults with hip fractures in the final phase of life. This study aims to guide Dutch physicians and hospitals nationwide in a standardised implementation of shared decision-making regarding surgery or NOM in selected frail older adults with a hip fracture. Methods and analysis The patient population for implementation includes frail older adults aged ≥70 years with an acute proximal femoral fracture, nursing home care or a similar level of care elsewhere and at least one additional criterion (ie, malnutrition, severe mobility impairment or ASA≥4). The 2-year implementation study will be conducted in four phases. In phases 1 and 2, barriers and facilitators for implementation will be identified and an implementation protocol, educational materials and patient information will be developed. Phase 3 will involve an implementation pilot in 14 hospitals across the Netherlands. The protocol and educational material will be improved based on healthcare provider and patient experiences gathered through interviews. Phase 4 will focus on upscaling to nationwide implementation and the effect of the implementation on NOM rate will be measured using data from the Dutch Hip Fracture Audit. Ethics and dissemination The study was exempted by the local Medical Research Ethics Committee (MEC-2023-0270, 10 May 2023) and Medical Ethics Committee United (W23.083, 26 April 2023). The study’s results will be submitted to an open access international peer-reviewed journal. Its protocols, tools and results will be presented at several national and international academic conferences of relevant orthogeriatric (scientific) associations.</p

Longitudinal respiratory subphenotypes in patients with COVID-19-related acute respiratory distress syndrome: results from three observational cohorts

Background: Patients with COVID-19-related acute respiratory distress syndrome (ARDS) have been postulated to present with distinct respiratory subphenotypes. However, most phenotyping schema have been limited by sample size, disregard for temporal dynamics, and insufficient validation. We aimed to identify respiratory subphenotypes of COVID-19-related ARDS using unbiased data-driven approaches. Methods: PRoVENT–COVID was an investigator-initiated, national, multicentre, prospective, observational cohort study at 22 intensive care units (ICUs) in the Netherlands. Consecutive patients who had received invasive mechanical ventilation for COVID-19 (aged 18 years or older) served as the derivation cohort, and similar patients from two ICUs in the USA served as the replication cohorts. COVID-19 was confirmed by positive RT-PCR. We used latent class analysis to identify subphenotypes using clinically available respiratory data cross-sectionally at baseline, and longitudinally using 8-hourly data from the first 4 days of invasive ventilation. We used group-based trajectory modelling to evaluate trajectories of individual variables and to facilitate potential clinical translation. The PRoVENT-COVID study is registered with ClinicalTrials.gov, NCT04346342. Findings: Between March 1, 2020, and May 15, 2020, 1007 patients were admitted to participating ICUs in the Netherlands, and included in the derivation cohort. Data for 288 patients were included in replication cohort 1 and 326 in replication cohort 2. Cross-sectional latent class analysis did not identify any underlying subphenotypes. Longitudinal latent class analysis identified two distinct subphenotypes. Subphenotype 2 was characterised by higher mechanical power, minute ventilation, and ventilatory ratio over the first 4 days of invasive mechanical ventilation than subphenotype 1, but PaO2/FiO2, pH, and compliance of the respiratory system did not differ between the two subphenotypes. 185 (28%) of 671 patients with subphenotype 1 and 109 (32%) of 336 patients with subphenotype 2 had died at day 28 (p=0·10). However, patients with subphenotype 2 had fewer ventilator-free days at day 28 (median 0, IQR 0–15 vs 5, 0–17; p=0·016) and more frequent venous thrombotic events (109 [32%] of 336 patients vs 176 [26%] of 671 patients; p=0·048) compared with subphenotype 1. Group-based trajectory modelling revealed trajectories of ventilatory ratio and mechanical power with similar dynamics to those observed in latent class analysis-derived trajectory subphenotypes. The two trajectories were: a stable value for ventilatory ratio or mechanical power over the first 4 days of invasive mechanical ventilation (trajectory A) or an upward trajectory (trajectory B). However, upward trajectories were better independent prognosticators for 28-day mortality (OR 1·64, 95% CI 1·17–2·29 for ventilatory ratio; 1·82, 1·24–2·66 for mechanical power). The association between upward ventilatory ratio trajectories (trajectory B) and 28-day mortality was confirmed in the replication cohorts (OR 4·65, 95% CI 1·87–11·6 for ventilatory ratio in replication cohort 1; 1·89, 1·05–3·37 for ventilatory ratio in replication cohort 2). Interpretation: At baseline, COVID-19-related ARDS has no consistent respiratory subphenotype. Patients diverged from a fairly homogenous to a more heterogeneous population, with trajectories of ventilatory ratio and mechanical power being the most discriminatory. Modelling these parameters alone provided prognostic value for duration of mechanical ventilation and mortality. Funding: Amsterdam UMC