A mechanistic view of lipid membrane disrupting effect of PAMAM dendrimers

The effect of 5th generation polyamidoamine (PAMAM G5) dendrimers on multilamellar dipalmitoylphosphocholine (DPPC) vesicles was investigated. PAMAM was added in two different concentration to the lipids (10-3 and 10-2 dendrimer/lipid molar ratios). The thermal behavior of the evolved systems was characterized by DSC; while the structure and the morphology were investigated with small- and wide-angel X-ray scattering (SWAXS), freeze-fracture electron microscopy (FFTEM) and phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy, respectively. IR spectroscopy was used to study the molecular interactions between PAMAM and DPPC. The obtained results show that the dendrimers added in 10-3 molar ratio to the lipids generate minor perturbations in the multilamellar structure and thermal character of liposomes, while added in 10-2 molar ratio dendrimers cause major disturbance in the vesicular system. The terminal amino groups of the dendrimers are in strong interaction with the phosphate headgroups and through this binding dendrimers disrupt the regular multilamellar structure of DPPC. Besides highly swollen, fragmented bilayers, small vesicles are formed

Thermotropic and structural effects of poly(malic acid) on fully hydrated multilamellar DPPC–water systems

The thermotropic and structural effects of low molecular weight poly(malic acid) (PMLA) on fully hydrated multilamellar dipalmitoylphosphatidylcholine (DPPC)-water systems were investigated using differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and freeze-fracture transmission electron microscopy (FFTEM). Systems of 20 wt% DPPC concentration and 1 and 5 wt% PMLA to lipid ratios were studied. The PMLA derivatives changed the thermal behavior of DPPC significantly and caused a drastic loss in correlation between lamellae in the three characteristic thermotropic states (i.e., in the gel, rippled gel and liquid crystalline phases). In the presence of PBS or NaCl, the perturbation was more moderate. The structural behavior on the atomic level was revealed by FTIR spectroscopy. The molecular interactions between DPPC and PMLA were simulated via modeling its measured infrared spectra, and their peculiar spectral features were interpreted. Through this interpretation, the poly(malic acid) is inferred to attach to the headgroups of the phospholipids through hydrogen bonds between the free hydroxil groups of PMLA and the phosphodiester groups of DPPC

Structural characterization of the poly(ethylene glycol) layer of sterically stabilized liposomes by means of FTIR spectroscopy

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) combined with curve fitting procedures was used to characterize the poly(ethylene glycol) (PEG) layer of a pharmacologically relevant liposomal drug delivery system. The hydration of the polymer layer was described based on the ratio of the trans and gauche configurations of the C-O-C bond of the PEG molecules, which show a minimum at ~6 mol% PEG-lipid molar ratio. The latter corresponds to highest bilayer stability, and coincides with the transition from the mushroom to the brush configuration of the PEG structure. This preliminary study showed that the ATR-FTIR technique is capable of qualitatively describing the hydration of the PEG-layer of stealth liposomes, which is in connection with the structure of the polymer on the liposomal surface

Size Measurement of Extracellular Vesicles and Synthetic Liposomes: The Impact of the Hydration Shell and the Protein Corona

Size characterization of extracellular vesicles (EVs) and drug delivery liposomes is of great importance in their applications in diagnosis and therapy of diseases. There are many different size characterization techniques used in the field, which often report different size values. Besides technological biases, these differences originate from the fact that various methods measure different physical quantities to determine particle size. In this study, the size of synthetic liposomes with nominal diameters of 50nm and 100nm, and red blood cell-derived EVs (REVs) were measured with established optical methods, such as dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA), and with emerging non-optical methods such as microfluidic resistive pulse sensing (MRPS) and very small-angle neutron scattering (VSANS). The comparison of the hydrodynamic sizes obtained by DLS and NTA with the sizes corresponding to the excluded volume of the particles by MRPS enabled the estimation of the thickness of the hydration shell of the particles. The comparison of diameter values corresponding to the boundary of the phospholipid bilayer obtained from VSANS measurements with MRPS size values revealed the thickness of the polyethylene glycol-layer in case of synthetic liposomes, and the thickness of the protein corona in case of REVs

Laboratóriumi paraméterek kódolása a LOINC-rendszer szerint a Debreceni Egyetem Klinikai Központjában = Coding of laboratory parameters using the LOINC system at the Clinical Center of the University of Debrecen

Bevezetés: A Debreceni Egyetem adatvagyonának jelentős részét alkotja a Klinikai Központban zajló betegellátás során keletkezett orvosi, biokémiai és képi adat, rendszerezetlen változatban. Ezek kutatási célú alkalmazhatósága jelentősen korlátozott. Az egyetemi „Tématerületi Kiválósági Programon” belül, a „Big Data tématerület” keretében elindított K+F projekt legfontosabb célja az anonimizált adatvagyon elérhetővé tétele a felhasználók számára megfelelő transzformációs eljárások kidolgozásával. Az elemzésre kiválóan használható adatokat az in vitro rutindiagnosztikai laboratórium által szolgáltatott adatok jelentik. A rutindiagnosztikai gyakorlatban használatos adatmezőket rövidített, magyar nyelvű, nem standardizált kulcsszavak jelölik, és e kulcsszavak kódolására a nemzetközi Logikai Megfigyelési Azonosítók, Nevek és Kódok (Logical Observation Identifiers Names and Codes – LOINC) szabvány alkalmazását határoztuk el. Referencialaboratóriumok, egészségügyi szolgáltatók, kormányhivatalok, egészségügyi biztosítók, orvosi szoftverek és műszerek gyártói, kutatók, valamint az egészségügyi rendszert igénybe vevők világszerte használják a LOINC-rendszert az adatok azonosítására, valamint azok rendszerek közötti zökkenőmentes átadására. Célkitűzés: Célunk a Debreceni Egyetem Klinikai Központjának Laboratóriumi Medicina Intézete által meghatározott rutindiagnosztikai paraméterek (n = 448) megfeleltetése a LOINC kódolási rendszernek, figyelembe véve az azonos adatok hátterében az időbeli és módszertani eltéréseket. Módszerek: A laboratóriumi adatokhoz rendelt kulcsszavakat a kórházi informatikai rendszer üzemeltetőjétől kapott adatbázis alapján elemeztük. A rutindiagnosztikában használatos kulcsszavakat, megnevezéseket használtuk a LOINC-szabvány szerinti kódolásra azután, hogy a kódolás módszertanát áttanulmányoztuk, és megfelelő jártasságra tettünk szert az alkalmazásában. Eredmények: Magyarországon egyedülálló módon megfeleltettük az elvégzett rutindiagnosztikai laboratóriumi adatok és vizsgálatok elnevezéseit a LOINC-rendszer követelményeinek, és nyilvánosan hozzáférhetővé tettük őket a Debreceni Egyetem https://labmed.unideb.hu/hu/loinc-tablazatok világhálójának elérhetőségén. Következtetés: Az egységes nemzetközi LOINC-rendszer szerint kódolt adatok hatékonyabban elősegítik a Debreceni Egyetem nemzetközi integrációs törekvéseit, többek között a laboratóriumok közötti kommunikációt, valamint a nemzetközi, határokon átívelő információáramlást és a valamennyi érdekelttel való kapcsolattartást. Orv Hetil. 2023; 164(27): 1043–1051. | Introduction: The research utility of the bulk of the medical data generated at the Clinical Center of the University of Debrecen, which is constituted mainly by the clinical diagnostic laboratory results and medical images, is quite constrained in its present unstandardized form. The primary aim of the Big Data Research and Development project at the University of Debrecen is to facilitate data transformation and standardization to propagate its research utility for the potential end-users. Data generated in the in vitro diagnostic laboratory setting are an ideal candidate for the aforementioned goals. Data generated in Hungarian language in this particular setting are typically acronyms that do not particularly confirm to any standard norms and the transformation of these data using the globally acknowledged Logical Observation Identifiers Names and Codes (LOINC) was the primary goal of this research project. Globally the LOINC is used by healthcare providers, government agencies, insurance companies, software and device manufacturers, researchers and reference laboratories for identifying medical laboratory observations and promote unhindered fluency between various systems. Objective: The aim of the project was to assure compliance of the various routine diagnostic laboratory parameters (n = 448) generated at the Department of Laboratory Medicine of the University of Debrecen to the LOINC system paying particular attention to and accommodating data sensitive to timeline and methodology. Methods: Keywords allocated to individual parameters determined by the laboratory were provided by the IT service provider of the facility. The individual codes for the various parameters were manually identified using the search engine of the LOINC database available at www.loinc.org, only upon attainment of proficiency in use of the database and ample familiarity with the scientific literature on the topic. Results: All routine diagnostic laboratory parameters were LOINC coded with no exception. The list of LOINCs’ was made available on the https://labmed.unideb.hu/hu/loinc-tablazatok web link of the University of Debrecen. Conclusion: The transformation of diagnostic laboratory parameters to globally recognized LOINCs’ improves and further facilitates the international integration of data generated at the University of Debrecen, furthermore propels communications between laboratories and parties of interest beyond international boundaries and borders