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  • 1
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 79, No. Suppl_1 ( 2022-09)
    Abstract: Recent studies revealed major concerns related to the accuracy of widely used clinical assays for aldosterone and renin, fueling the need for alternative and more robust bio-analytical solutions for assessment of the Renin-Angiotensin-Aldosterone-System (RAAS) in clinical samples. RAAS Triple-A profiling is a high-throughput mass-spectrometry based assay for quantification of Angiotensin I (Ang I), Angiotensin II (Ang II) and Aldosterone in serum samples. Quantified hormone levels are used to calculate markers for plasma-renin-activity (PRA-S), plasma angiotensin-converting-enzyme activity (ACE-S) and adrenal aldosterone secretion (AA2-Ratio), which can be used for clinical profiling in patients with uncontrolled hypertension. A RAAS Triple-A LC-MS/MS kit was recently launched as an In Vitro Diagnostic (IVD) device in Europe for hypertension profiling. In the current study, a comparative approach was used to assess analytical performance of the RAAS Triple-A assay on three different LC-MS/MS systems, Altis+ (Thermo Scientific), Xevo TQ-S (Waters), and Triple Quad 6500+ (Sciex) located in three different laboratories. RAAS Triple-A kits (96-well format) were used to analyze one set of n=50 triplicate human serum samples at each location. At each site, samples were sample preparation and LC-MS/MS analysis according to the RAAS Triple-A kit manual. Analytical validation of assay linearity, precision, and accuracy were evaluated at each site, and Bland-Altman-Analysis was used to test for quantification bias between sites. Results demonstrate the measured concentrations for each analyte, Ang I, Ang II, and aldosterone, were strongly correlated between sites (R 2 = Ang I: 0.996; Ang II: 0.991; Aldo: 0.983). Performance characteristics of all target analytes were in compliance with European Medical Agency (EMA) standards for bio-analytical assays on each instrument. Robust assay performance across laboratories and different LC-MS/MS systems allows for a broad clinical application of RAAS Triple-A profiling potentially improving treatment efficacy in hypertension by supporting treatment decisions with individual RAAS Triple-A profiles.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2022
    detail.hit.zdb_id: 2094210-2
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  • 2
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 62, No. suppl_1 ( 2013-09)
    Abstract: Angiotensin concentrations are affected by multiple molecular components including receptors and enzymes which might be either dissolved in plasma or attached to blood cells or endothelial surfaces throughout the body, giving rise to a concentration determining local enzymatic environment. This environment substantially changes during blood collection leading to a rapid and fundamental shift in angiotensin peptide levels. Therefore, a clearly defined and properly controlled sample stabilization procedure is essential for the accurate measurement of in vivo angiotensin peptide levels. Surprisingly, standard samples collected by anti-coagulation with heparin can be used for analyzing the human RAS under well-defined steady-state conditions, allowing RAS-Fingerprint based conclusions about the activities of circulating enzymes involved in angiotensin metabolism. The mass spectrometry based measurements of in vivo RAS-Fingerprints (immediate sample stabilization) or heparin plasma derived ex vivo RAS-Fingerprints in plasma or whole blood provide unique insights into the physiology of the human RAS. RAS-Fingerprinting provides an integrated view about the activity of the enzymes involved in angiotensin metabolism in a plasma sample and therefore represents a powerful tool for characterization of the patient specific “Biochemical Hardware”, which determines angiotensin peptide levels in vivo. The assay is compatible with undiluted plasma and whole blood and can be further applied to long-term stored frozen plasma samples. The utilization of RAS-Fingerprinting in clinical studies will substantially enhance our understanding of the human RAS and could lead to the development of personalized approaches for the treatment and prevention of cardiovascular diseases in the near future.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2013
    detail.hit.zdb_id: 2094210-2
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  • 3
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 60, No. suppl_1 ( 2012-09)
    Abstract: The Renin-Angiotensin-System (RAS) is critically involved in the regulation of important physiological functions including blood pressure and fluid balance. It is constituted by multiple enzymes giving rise to a meshwork of effector peptides, which mediate their functions through binding to specific receptor molecules. Therefore, the modification of angiotensin peptide levels represents a common strategy for the treatment of RAS-associated diseases and is frequently achieved by the pharmacologic regulation of enzymes taking part in angiotensin metabolism. We developed a highly sensitive method, which allows the simultaneous absolute quantification of up to 10 different angiotensin peptides in human plasma and whole blood (RAS-Fingerprinting). The measurement of RAS-Fingerprints provides unique insights into the physiology of the human RAS and therefore represents a powerful tool for the patient specific evaluation of this physiologically important peptide hormone system. Beside the precise quantification of angiotensin peptides in plasma and whole blood, RAS-Fingerprints analyze the biochemical hardware of the RAS at a previously unachieved level of detail and accuracy. During the development and validation of our LC-MS/MS based method, comprehensive datasets showing multiple applications for RAS-Fingerprinting have been generated. Investigation of healthy volunteers revealed that a patient specific state of the RAS exists, which is defined by a unique composition of RAS enzyme activities that might have crucial effects on the outcome of RAS targeted therapies in individual patients. RAS-Fingerprinting in healthy volunteers treated with an Angiotensin-Receptor-Blockers, ACE-Inhibitor or Renin-Inhibitor revealed that the human RAS reacts to different drugs in a very dynamic and specific way. Therefore, RAS-Fingerprinting could contribute to the development of innovative therapeutic approaches affecting the RAS. The implementation of RAS-Fingerprinting into clinical studies would substantially enhance our understanding of the human RAS and could lead to the development of personalized treatment schemes in the management of RAS-associated diseases in the near future.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2012
    detail.hit.zdb_id: 2094210-2
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  • 4
    In: Circulation Research, Ovid Technologies (Wolters Kluwer Health), Vol. 121, No. 1 ( 2017-06-23), p. 43-55
    Abstract: Neurogenic hypertension is characterized by an increase in sympathetic activity and often resistance to drug treatments. We previously reported that it is also associated with a reduction of angiotensin-converting enzyme type 2 (ACE2) and an increase in a disintegrin and metalloprotease 17 (ADAM17) activity in experimental hypertension. In addition, while multiple cells within the central nervous system have been involved in the development of neurogenic hypertension, the contribution of ADAM17 has not been investigated. Objective: To assess the clinical relevance of this ADAM17-mediated ACE2 shedding in hypertensive patients and further identify the cell types and signaling pathways involved in this process. Methods and Results: Using a mass spectrometry-based assay, we identified ACE2 as the main enzyme converting angiotensin II into angiotensin-(1–7) in human cerebrospinal fluid. We also observed an increase in ACE2 activity in the cerebrospinal fluid of hypertensive patients, which was correlated with systolic blood pressure. Moreover, the increased level of tumor necrosis factor-α in those cerebrospinal fluid samples confirmed that ADAM17 was upregulated in the brain of hypertensive patients. To further assess the interaction between brain renin–angiotensin system and ADAM17, we generated mice lacking angiotensin II type 1 receptors specifically on neurons. Our data reveal that despite expression on astrocytes and other cells types in the brain, ADAM17 upregulation during deoxycorticosterone acetate–salt hypertension occurs selectively on neurons, and neuronal angiotensin II type 1 receptors are indispensable to this process. Mechanistically, reactive oxygen species and extracellular signal-regulated kinase were found to mediate ADAM17 activation. Conclusions: Our data demonstrate that angiotensin II type 1 receptors promote ADAM17-mediated ACE2 shedding in the brain of hypertensive patients, leading to a loss in compensatory activity during neurogenic hypertension.
    Type of Medium: Online Resource
    ISSN: 0009-7330 , 1524-4571
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2017
    detail.hit.zdb_id: 1467838-X
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  • 5
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 66, No. suppl_1 ( 2015-09)
    Abstract: The concentrations of angiotensins are maintained by equal rates of formation and degradation. The resulting steady-state angiotensin levels are affected by local molecular factors including tissue, endothelium or blood cell associated angiotensin receptors and processing enzymes as well as plasma soluble RAS components. The high concentration of the pro-hormone angiotensinogen in human plasma in combination with reported ranges for plasma renin activity result in a long-lasting and stable Ang I formation rate without significantly reducing angiotensinogen levels within several hours. This phenomenon can be utilized for the generation of an ex vivo situation that is characterized by significantly higher but stable angiotensin peptide levels. These ex vivo equilibrium angiotensin levels provide an integrated picture about plasma angiotensinase activities and therefore represent a powerful diagnostic tool for analyzing the systemic RAS in clinical samples. Moreover, these ex vivo levels remain stable over hours of incubation at 37°C and show a very high correlation ( 〉 90%) with angiotensin levels obtained by a state-of-the art sample collection procedure using complex inhibitor cocktails for stabilizing angiotensin peptides during blood collection. The quantification of equilibrium angiotensin levels does not require any special sample collection procedures and can be applied to frozen serum and heparin plasma samples. It turned out that ex vivo angiotensin levels represent a measure for the consumption of angiotensin metabolites by the organism, therefore providing a powerful and versatile tool for assessing in vivo angiotensin signaling on the patient specific level enabling new diagnosis based rationales for anti-hypertensive therapies. The application of ex vivo RAS-Fingerprinting in clinical studies could substantially enhance our understanding of the regulation and physiology of the human RAS and could further lead to the development of powerful personalized approaches in the future treatment of hypertension.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2015
    detail.hit.zdb_id: 2094210-2
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  • 6
    In: Circulation, Ovid Technologies (Wolters Kluwer Health), Vol. 144, No. Suppl_1 ( 2021-11-16)
    Abstract: Background: Understanding how sex influences the pathophysiology of cardiovascular and renal disease may enhance precision medicine approaches that account for sex specific biologic differences in these diseases. Nevertheless, characterization of preclinical models often fail to account for the role of sex on important pathophysiologic mechanisms. The renin-angiotensin-aldosterone system (RAAS) plays a central role in the development and progression of cardiovascular and renal disease. In addition to the classic RAAS pathway, an alternative RAAS pathway produces angiotensins (e.g. Ang [1-7]) that can counteract classical RAAS hormones such as Angiotensin (Ang) II. We hypothesized that RAAS profiling in a high-salt fed Dahl-S rat model would reveal significant sex differences in both classic and alternative RAAS pathways. Methods/Results: Ten week-old male and female Dahl-S rats were fed either 0.2% salt normal chow (SS-NC), or 8% high-salt diet (SS-HS) for eight weeks (n=6-8/group). Equilibrium RAAS profiling via LC-MS/MS was performed in lithium heparin plasma samples. In response to high-salt diet, both male and female SS-HS rats had significant (p 〈 0.05) reductions vs. their respective SS-NC controls in plasma aldosterone (-93% in male SS-HS, -97% in female SS-HS), Ang II (-71% in male SS-HS, -41% in female SS-HS), Ang IV (-79% in male SS-HS, -54% in female SS-HS) as well as calculated plasma renin activity (-67% in male SS-HS, -42% in female SS-HS), although the magnitude of reduction was generally greater in males vs. females. Alternatively, only male SS-HS rats had significant (p 〈 0.05 vs. SS-NC) reductions in plasma Ang I (-63%), Ang III (-66%), as well RAAS metabolites of the alternative RAS axis, Ang [1-5] (-58%) and Ang [1-7] (-70%) vs. SS-NC. Comparing female vs. male SS-HS rats, females had significantly (p 〈 0.01 vs. male) increased levels of angiotensins of the classic RAS pathway, such as Ang I (113%), Ang II (104%), Ang III (150%) and Ang IV (265%) after high-salt diet. Conclusion: High-salt diet induces significant sex-dependent differences in both classic and alternative RAAS pathways of Dahl-S rats and may provide important insight into the sex-dependent differences of cardiovascular and renal injury seen in this model.
    Type of Medium: Online Resource
    ISSN: 0009-7322 , 1524-4539
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2021
    detail.hit.zdb_id: 1466401-X
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  • 7
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 2015
    In:  Hypertension Vol. 66, No. suppl_1 ( 2015-09)
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 66, No. suppl_1 ( 2015-09)
    Abstract: Primary aldosteronism (PA) is severe form of hypertension characterized by a strongly increased aldosterone secretion mediated by adenomas or other forms of adrenal hyper-activity. Once detected, PA can be usually cured by either surgical intervention or by appropriate pharmacologic treatments. This is also reflected in clinical guidelines of Endocrine Societies in Europe and the US, suggesting extensive PA screening activities among resistant hypertensive patients. The incidence of PA among hypertensive patients varies strongly between different studies, which is in part caused by the complex state-of-the-art testing procedure that unfortunately is far away from being a versatile PA screening tool. Despite strong limitations regarding selectivity, sensitivity and the interference with multiple anti-hypertensive drugs, the aldosterone-renin-ratio (ARR) is widely used for PA case detection. However, there is still a strong demand for accurate and reliable and patient friendly PA case detection. The use of novel and more accurate technologies for quantification of aldosterone and renin activity might help to improve the power of the ARR as a diagnostic tool for PA. However, there is a big need for a versatile PA screening assay that doesn’t interfere with anti-hypertensive treatments and therefore allows the clear identification of PA patients without complex corrections and adaptions being necessary and without increasing the patient’s cardiovascular risk in the course of the diagnostic process. The Aldosterone-to-Angiotensin-II-Ratio (AA2-Ratio) is a novel mass-spectrometry based high-throughput test for PA that combines the plasma levels of aldosterone and physiologically active angiotensin II into a diagnostic ratio. The test performance is superior to the ARR in terms of the diagnostic window and method accuracy. The AA2-Ratio does not interfere with standard anti-hypertensive drugs including ACE inhibitors. First data obtained in a proof-of-concept study investigating PA positive and negative patients proved the AA2-Ratio to be a powerful and cost-effective diagnostic tool for the diagnosis of PA in clinical practice.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2015
    detail.hit.zdb_id: 2094210-2
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  • 8
    In: Journal of the American College of Cardiology, Elsevier BV, Vol. 77, No. 14 ( 2021-04), p. 1731-1743
    Type of Medium: Online Resource
    ISSN: 0735-1097
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 1468327-1
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  • 9
    In: Frontiers in Veterinary Science, Frontiers Media SA, Vol. 10 ( 2023-8-31)
    Abstract: Chronic diarrhea is a hallmark sign of canine chronic inflammatory enteropathy (CIE), leading to fluid and electrolyte losses. Electrolyte homeostasis is regulated by the renin-angiotensin-aldosterone-system (RAAS), which might be involved in (counter-)regulating electrolyte losses in canine CIE. Whether and which electrolyte transporters are affected or if RAAS is activated in canine CIE is unknown. Thus, intestinal electrolyte transporters and components of the RAAS were investigated in dogs with CIE. Serum RAAS fingerprint analysis by mass spectrometry was performed in 5 CIE dogs and 5 healthy controls, and mRNA levels of intestinal electrolyte transporters and local RAAS pathway components were quantified by RT-qPCR in tissue biopsies from the ileum (7 CIE, 10 controls) and colon (6 CIE, 12 controls). Concentrations of RAAS components and mRNA expression of electrolyte transporters were compared between both groups of dogs and were tested for associations among each other. In dogs with CIE, associations with clinical variables were also tested. Components of traditional and alternative RAAS pathways were higher in dogs with CIE than in healthy controls, with statistical significance for Ang I, Ang II, and Ang 1–7 (all p   & lt; 0.05). Expression of ileal, but not colonic electrolyte transporters, such as Na + /K + -ATPase, Na + /H + -exchanger 3, Cl − channel 2, down-regulated in adenoma, and Na + -glucose-cotransporter (all p   & lt; 0.05) was increased in CIE. Our results suggest that the dys- or counter-regulation of intestinal electrolyte transporters in canine CIE might be associated with a local influence of RAAS. Activating colonic absorptive reserve capacities may be a promising therapeutic target in canine CIE.
    Type of Medium: Online Resource
    ISSN: 2297-1769
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2834243-4
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  • 10
    In: Clinical Science, Portland Press Ltd., Vol. 135, No. 2 ( 2021-01-29), p. 259-274
    Abstract: Brain renin–angiotensin system (RAS) activation is thought to mediate deoxycorticosterone acetate (DOCA)-salt hypertension, an animal model for human primary hyperaldosteronism. Here, we determined whether brainstem angiotensin II is generated from locally synthesized angiotensinogen and mediates DOCA-salt hypertension. To this end, chronic DOCA-salt-hypertensive rats were treated with liver-directed siRNA targeted to angiotensinogen, the angiotensin II type 1 receptor antagonist valsartan, or the mineralocorticoid receptor antagonist spironolactone (n = 6–8/group). We quantified circulating angiotensinogen and renin by enzyme-kinetic assay, tissue angiotensinogen by Western blotting, and angiotensin metabolites by LC-MS/MS. In rats without DOCA-salt, circulating angiotensin II was detected in all rats, whereas brainstem angiotensin II was detected in 5 out of 7 rats. DOCA-salt increased mean arterial pressure by 19 ± 1 mmHg and suppressed circulating renin and angiotensin II by & gt;90%, while brainstem angiotensin II became undetectable in 5 out of 7 rats ( & lt;6 fmol/g). Gene silencing of liver angiotensinogen using siRNA lowered circulating angiotensinogen by 97 ± 0.3%, and made brainstem angiotensin II undetectable in all rats (P & lt;0.05 vs. non-DOCA-salt), although brainstem angiotensinogen remained intact. As expected for this model, neither siRNA nor valsartan attenuated the hypertensive response to DOCA-salt, whereas spironolactone normalized blood pressure and restored brain angiotensin II together with circulating renin and angiotensin II. In conclusion, despite local synthesis of angiotensinogen in the brain, brain angiotensin II depended on circulating angiotensinogen. That DOCA-salt suppressed circulating and brain angiotensin II in parallel, while spironolactone simultaneously increased brain angiotensin II and lowered blood pressure, indicates that DOCA-salt hypertension is not mediated by brain RAS activation.
    Type of Medium: Online Resource
    ISSN: 0143-5221 , 1470-8736
    Language: English
    Publisher: Portland Press Ltd.
    Publication Date: 2021
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