Ioanni Veras

• Veras, Ioanni; Eken, Olav Søvik; Levy, Finn Olav; Melleby, Arne Olav & Aronsen, Jan Magnus (2026). Protocol for isolation of nuclei from murine cardiac tissue for single-nucleus multiomic sequencing. STAR Protocols. 7(2). doi: 10.1016/j.xpro.2026.104615. Full text in Research Archive
• Nordén, Einar Sjaastad; Veras, Ioanni; Yadav, Prakash; Løken, Kari Gulbrandsen; Dishington, Hilde & Thorstensen, Christian [Show all 8 contributors for this article] (2023). Clinical efficacy of buprenorphine after oral dosing in rats undergoing major surgery. Laboratory Animals. ISSN 0023-6772. doi: 10.1177/00236772231178417. Full text in Research Archive Show summary

  Serum corticosterone, serum buprenorphine, body weight change, consumption of food and water and behaviour-based pain assessment were measured in catheterised and non-catheterised male Wistar rats undergoing myocardial infarct (MI) surgery under general anaesthesia following buprenorphine dosing by subcutaneous (Bup-SC, 0.05 mg/kg) and oral (Bup-O, 0.4 mg/kg) routes. Buprenorphine was dosed subcutaneously at half an hour before and 8, 16 and 24 hours after surgery (Bup-SC), orally at one hour before surgery (Bup-O1) or at one hour before and 12 hours after surgery (Bup-O2) in catheterised rats and at one hour before and 24 hours after surgery (Bup-O24) in non-catheterised rats. Serum corticosterone, body weight changes and food and water consumption were not significantly different between treatments in catheterised rats. Bup-SC resulted in rapidly decreasing serum concentrations below the clinically effective concentrations (1 ng/mL) already at two hours after the first dose. Bup-O provided significantly higher and slowly decreasing serum concentrations, at or above clinically effective concentrations, for 24 hours (Bup-O1) and 42 hours (Bup-O2) after surgery. In non-catheterised rats, body weight development and food consumption were significantly higher in Bup-O24 rats compared to Bup-SC rats. The results indicate that a SC buprenorphine dose of 0.05 mg/kg every eight hours provides long periods of serum concentrations below clinically effective levels, and that a higher dose and/or more frequent dosage are required to provide stable serum concentrations at or above clinically effective levels. A single oral buprenorphine dose of 0.4 mg/kg provides clinically effective and stable serum concentrations for 24 hours in rats after MI surgery.

• Skogestad, Jonas; Albert, Ingrid; Hougen, Karina; Lothe, Gustav B; Lunde, Marianne & Eken, Olav Søvik [Show all 25 contributors for this article] (2023). Disruption of Phosphodiesterase 3A Binding to SERCA2 Increases SERCA2 Activity and Reduces Mortality in Mice with Chronic Heart Failure. Circulation. ISSN 0009-7322. 147(16), p. 1221–1236. doi: 10.1161/CIRCULATIONAHA.121.054168. Full text in Research Archive
• Norden, Einar Sjaastad; Bendiksen, Bård Andre; Andresen, Henriette; Bergo, Kaja Knudsen; Espe, Emil Knut Stenersen & Hasic, Almira [Show all 12 contributors for this article] (2021). Sacubitril/valsartan ameliorates cardiac hypertrophy and preserves diastolic function in cardiac pressure overload. ESC Heart Failure. 8(2), p. 918–927. doi: 10.1002/ehf2.13177. Full text in Research Archive
• Melleby, Arne Olav; Romaine, Andreas; Aronsen, Jan Magnus; Veras, Ioanni; Zhang, Lili & Sjaastad, Ivar [Show all 8 contributors for this article] (2018). A novel method for high precision aortic constriction that allows for generation of specific cardiac phenotypes in mice. Cardiovascular Research (CVR). ISSN 0008-6363. doi: 10.1093/cvr/cvy141. Full text in Research Archive Show summary

  Aims Generation of reproducible cardiac disease phenotypes in mice is instrumental for investigating mechanisms leading to heart failure (HF). For decades, suture-based thoracic aortic constriction has been the preferred method for increasing left ventricular (LV) afterload in rodents, but the degree of stenosis resulting from this method is variable. In an effort to improve this methodology, we subjected mice to constriction of the ascending aorta using o-rings with fixed inner diameters (IDs). Methods and results Mice of C57BL/6J and FVB/N background were subjected to constriction of the ascending aorta using o-rings with fixed IDs of 0.71, 0.66, and 0.61 mm. O-ring aortic banding resulted in 98.7% survival 2 weeks post-surgery, with very low intra- and inter-surgeon variation. When using the narrowest o-ring (0.61 mm), mice developed hypertrophy within 1 week. Over 20 weeks, the mice gradually developed reduced LV ejection fraction (LVEF) and dilatation with increased left atrial dimensions and lung weight, indicating congestion. When using o-rings with IDs of 0.66 mm and 0.71 mm, the mice developed hypertrophy, but maintained a compensated state with stabilized LVEF 8–20 weeks post-surgery. The up-regulation of signature genes associated with HF, hypertrophy, fibrosis, and the level of activation of MAPK and NFAT signalling pathways corresponded to the degree of stenosis. Conclusion Here, we introduce a novel method for high precision aortic constriction in mice with high intra- and inter-surgeon reproducibility and low post-operative mortality that allows generation of specific cardiac disease phenotypes.

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