Quantification of lipid and peptide content in antigenic peptide-loaded liposome formulations by reversed-phase UPLC using UV absorbance and evaporative light scattering detection

Antigenic peptide-loaded cationic liposomes have shown promise as cancer vaccines. Quantification of both peptides and lipids is critical for quality control of such vaccines for clinical translation. In this work we describe a reversed phase ultra-performance liquid chromatography (RP-UPLC) method that separates lipids (DOTAP, DOPC and their degradation products) and two physicochemically different peptides within 12 min. Samples were prepared by dilution in a 1:1 (v/v) mixture of methanol and water. Peptide quantifi-cation was done via UV detection and lipids were quantified by an evaporative light scattering detector (ELSD), both coupled to the RP-UPLC system, with high precision (RSD < 3.5%). We showed that the presence of lipids and peptides did not mutually influence their quantification. Limit of detection (LOD) and limit of quantification (LOQ), as determined in the ICH guidelines, were 6 and 20 ng for DOTAP, 12 ng and 40 ng for DOPC, 3.0 ng and 8.0 ng for peptide A and 2.4 ng and 7.2 ng for the more hydrophobic peptide B. Finally, lipid degradation of DOTAP and DOPC was monitored in peptide loaded DOTAP:DOPC liposomes upon storage at 4 degrees C and 40 degrees C.(c) 2022 The Authors. Published by Elsevier Inc. on behalf of American Pharmacists Association. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)Drug Delivery Technolog

Determining the optimal interval for imaging surveillance of ascending aortic aneurysms

Background Cardiovascular guidelines recommend (bi-)annual computed tomography (CT) or magnetic resonance imaging (MRI) for surveillance of the diameter of thoracic aortic aneurysms (TAAs). However, no previous study has demonstrated the necessity for this approach. The current study aims to provide patient-specific intervals for imaging follow-up of non-syndromic TAAs. Methods A total of 332 patients with non-syndromic ascending aortic aneurysms were followed over a median period of 6.7 years. Diameters were assessed using all available imaging techniques (echocardiography, CT and MRI). Growth rates were calculated from the differences between the first and last examinations. The diagnostic accuracy of follow-up protocols was calculated as the percentage of subjects requiring pre-emptive surgery in whom timely identification would have occurred. Results The mean growth rate in our population was 0.2 +/- 0.4 mm/year. The highest recorded growth rate was 2.0 mm/year, while 40.6% of patients showed no diameter expansion during follow-up. Females exhibited significantly higher growth rates than men (0.3 +/- 0.5 vs 0.2 +/- 0.4 mm/year, p = 0.007). Conversely, a bicuspid aortic valve was not associated with more rapid aortic growth. The optimal imaging protocol comprises triennial imaging of aneurysms 40-49 mm in diameter and yearly imaging of those measuring 50-54 mm. This strategy is as accurate as annual follow-up, but reduces the number of imaging examinations by 29.9%. Conclusions In our population of patients with non-syndromic TAAs, we found aneurysm growth rates to be lower than those previously reported. Yearly imaging does not lead to changes in the management of small aneurysms. Thus, lower imaging frequencies might be a good alternative approach.Cardiovascular Aspects of Radiolog