Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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A standardized method to determine the concentration of extracellular vesicles using tunable resistive pulse sensing

BACKGROUND: Understanding the pathogenic role of extracellular vesicles (EVs) in disease and their potential diagnostic and therapeutic utility is extremely reliant on in-depth quantification, measurement and identification of EV sub-populations. Quantification of EVs has presented several challenges, predominantly due to the small size of vesicles such as exosomes and the availability of various technologies to measure nanosized particles, each technology having its own limitations. MATERIALS AND METHODS: A standardized methodology to measure the concentration of extracellular vesicles (EVs) has been developed and tested. The method is based on measuring the EV concentration as a function of a defined size range. Blood plasma EVs are isolated and purified using size exclusion columns (qEV) and consecutively measured with tunable resistive pulse sensing (TRPS). Six independent research groups measured liposome and EV samples with the aim to evaluate the developed methodology. Each group measured identical samples using up to 5 nanopores with 3 repeat measurements per pore. Descriptive statistics and unsupervised multivariate data analysis with principal component analysis (PCA) were used to evaluate reproducibility across the groups and to explore and visualise possible patterns and outliers in EV and liposome data sets. RESULTS: PCA revealed good reproducibility within and between laboratories, with few minor outlying samples. Measured mean liposome (not filtered with qEV) and EV (filtered with qEV) concentrations had coefficients of variance of 23.9% and 52.5%, respectively. The increased variance of the EV concentration measurements could be attributed to the use of qEVs and the polydisperse nature of EVs. CONCLUSION: The results of this study demonstrate the feasibility of this standardized methodology to facilitate comparable and reproducible EV concentration measurements

Razvoj hidroksiapatit-ciprofloksacin implantata za kosti “dizajniranjem kvalitete”

The present study deals with the development of hydroxyapatite (HAp)-ciprofloxacin bone- -implants using the “Quality by design” approach. The effect of various synthetic parameters like drug amount added in the process, stirring speed and addition rate of orthophosphoric acid on drug concentration in the HAp-ciprofloxacin system synthesized by the precipitation technique using 23 factorial design was analyzed. Optimization methodology utilizing the first-order polynomial equation was used to search for optimal drug concentration in the HAp-ciprofloxacin implant system. The observed responses coincided well with the predicted values from the optimization technique. New implants were manufactured using various HAp-ciprofloxacin composites and 1.5 % (m/V) guar gum as a binder. Characterization of the delivery system was done by XRPD, FTIR spectroscopy and SEM. Even at highest drug concentration (76.6 ± 0.5 %, m/m), ciprofloxacin was present in noncrystalline state. The in vitro ciprofloxacin release from various bone-implants was sustained for several weeks and the drug release pattern correlated well with the Korsmeyer-Peppas model.U radu je opisan razvoj hidroksiapatit (HAp)-ciprofloksacin implantata za kosti “dizajniranjem kvalitete”. Učinak nezavisnih varijabli poput količine dodanog lijeka, brzine miješanja i udjela ortofosforne kiseline na koncentraciju lijeka u HAp-sustavu dobivenom precipitacijom optimiran je koristeći 23 faktorijalno dizajniranje. Pomoću polinomske jednadžbe prvog reda određena je optimalna koncentracija lijeka u implantatima na bazi HAp. Dobiveni odgovori podudaraju se s predviđenim vrijednostima iz optimiranih formulacija. Novi implantati pripravljeni su koristeći različite omjere HAp i ciprofloksacina te 1,5 % (m/V) guar gumu kao vezivo. Karakterizacija sustava za isporuku provedena je pomoću XRPD, FTIR spektroskopije i SEM. Ciprofloksacin je prisutan u amorfnom stanju čak pri najvišim koncentracijama (76,6 ± 0,5 %, m/m). In vitro oslobađanje ciprofloksacina iz različitih implantata bilo je polagano tijekom nekoliko tjedana i dobro je koreliralo s Korsmeyer-Peppasovim modelom

A standardized method to determine the concentration of extracellular vesicles using tunable resistive pulse sensing

Background: Understanding the pathogenic role of extracellular vesicles (EVs) in disease and their potential diagnostic and therapeutic utility is extremely reliant on in-depth quantification, measurement and identification of EV sub-populations. Quantification of EVs has presented several challenges, predominantly due to the small size of vesicles such as exosomes and the availability of various technologies to measure nanosized particles, each technology having its own limitations. Materials and Methods: A standardized methodology to measure the concentration of extracellular vesicles (EVs) has been developed and tested. The method is based on measuring the EVconcentration as a function of a defined size range. Blood plasma EVs are isolated and purified using size exclusion columns (qEV) and consecutively measured with tunable resistive pulse sensing (TRPS). Six independent research groups measured liposome and EV samples with the aim to evaluate the developed methodology. Each group measured identical samples using up to 5 nanopores with 3 repeat measurements per pore. Descriptive statistics and unsupervised multivariate data analysis with principal component analysis (PCA) were used to evaluate reproducibility across the groups and to explore and visualise possible patterns and outliers in EV and liposome data sets. Results: PCA revealed good reproducibility within and between laboratories, with few minor outlying samples. Measured mean liposome (not filtered with qEV) and EV (filtered with qEV) concentrations had coefficients of variance of 23.9% and 52.5%, respectively. The increased variance of the EV concentration measurements could be attributed to the use of qEVs and the polydisperse nature of EVs. Conclusion: The results of this study demonstrate the feasibility of this standardized methodology to facilitate comparable and reproducible EV concentration measurements