Charge Regulation Triggers Condensation of Short Oligopeptides to Polyelectrolytes.

Electrostatic interactions between charged macromolecules are ubiquitous in biological systems, and they are important also in materials design. Attraction between oppositely charged molecules is often interpreted as if the molecules had a fixed charge, which is not affected by their interaction. Less commonly, charge regulation is invoked to interpret such interactions, i.e., a change of the charge state in response to a change of the local environment. Although some theoretical and simulation studies suggest that charge regulation plays an important role in intermolecular interactions, experimental evidence supporting such a view is very scarce. In the current study, we used a model system, composed of a long polyanion interacting with cationic oligolysines, containing up to 8 lysine residues. We showed using both simulations and experiments that while these lysines are only weakly charged in the absence of the polyanion, they charge up and condense on the polycations if the pH is close to the pKa of the lysine side chains. We show that the lysines coexist in two distinct populations within the same solution: (1) practically nonionized and free in solution; (2) highly ionized and condensed on the polyanion. Using this model system, we demonstrate under what conditions charge regulation plays a significant role in the interactions of oppositely charged macromolecules and generalize our findings beyond the specific system used here.

Tuning polymer-blood and polymer-cytoplasm membrane interactions by manipulating the architecture of poly(2-oxazoline) triblock copolymers.

Bioactive moieties designed to bind to cell membrane receptors benefit from coupling with polymeric carriers that have enhanced affinity to the cell membrane. When bound to the cell surface, such carriers create a "2D solution" of a ligand with a significantly increased concentration near a membrane-bound receptor compared to a freely water-soluble ligand. Bifunctional polymeric carriers based on amphiphilic triblock copolymers were synthesized from 2-pent-4-ynyl oxazoline, 2-nonyl oxazoline and 2-ethyl oxazoline. Their self-assembly and interactions with plasma proteins and HEK 293 cells were studied in detail. The affinity of these triblock copolymers to HEK 293 cell membranes and organ tissues was tunable by the overall hydrophobicity of the polymer molecule, which is determined by the length of the hydrophobic and hydrophilic blocks. The circulation time and biodistribution of three representative triblock copolymers were monitored after intravenous administration to C57BL/6 albino mice. A prolonged circulation time was observed for polymers with longer hydrophobic blocks, despite their molecular weight being below the renal threshold.

Anionically Functionalized Glycogen Encapsulates Melittin by Multivalent Interaction.

We developed acid-functionalized glycogen conjugates as supramolecular carriers for efficient encapsulation and inhibition of a model cationic peptide melittin─the main component of honeybee venom. For this purpose, we synthesized and characterized a set of glycogens, functionalized to various degrees by several different acid groups. These conjugates encapsulate melittin up to a certain threshold amount, beyond which they precipitate. Computer simulations showed that sufficiently functionalized conjugates electrostatically attract melittin, resulting in its efficient encapsulation in a broad pH range around the physiological pH. Hemolytic assays confirmed in vitro that the effective inhibition of melittin's hemolytic activity occurs for highly functionalized samples, whereas no inhibition is observed when using low-functionalized conjugates. It can be concluded that functional glycogens are promising carriers for cationic molecular cargos or antidotes against animal venoms under conditions, in which suitable properties such as biodegradability and biocompatibility are crucial.

The emotional map of Prague - data on what locals think about the Czech capital?

The paper presents the data from the participatory emotional mapping in Prague, Czech Republic. It contains 98,364 points complemented with 30,941 comments from 5,973 respondents across the city of Prague (1,335,084 inhabitants according to [1]). There were eight questions/statements common for all of Prague, furthermore each Prague district (n = 27) could add up to seven questions/statements. The data were collected via our own participatory mapping platform EmotionalMaps.eu from April to September 2021.

The combination of endoluminal radiofrequency ablation and metal stent implantation for the treatment of malignant biliary stenosis - Randomized study.

PURPOSE: To analyse whether endobiliary radiofrequency ablation prior metal stent insertion in malignant biliary stenosis show improved survival or stent patency. METHODS: 76 patients with histologically proven malignant biliary stenosis have been enrolled in a prospective, randomized study. In control arm, 40 patients underwent self-expandable metal stent insertion. In experimental arm, the endoluminal ablation with a bipolar radiofrequency catheter was performed immediately before stent insertion. A subgroup analysis of cholangiocarcinoma was performed (22 vs 21 patients). The objective of the study was to determine the rate of complications, duration of the stent patency and the survival of patients (Kaplan-Meier analysis). RESULTS: No major complications related to the stent insertion and the endoluminal ablation were found. The mean primary stent patency was 5.2 (95% CI 0.7-12.8) vs 4.8 months (95% CI 0.8-18.2) months (p = 0.79) in control and experimental group, respectively, in the subgroup analysis with cholangiocarcinoma 4.5 (95% CI 0.8-10.3) and 9.6 (95% CI 5.2-11.2) months (p = 0.029). The median survival since the insertion of the stent was 6.8 (95 %CI 3.0-10.6) vs 5.2 (95 %CI 2.4-7.9) months (p = 0.495) and since the initial drainage 9.8 (95 %CI 6.9-12.7) vs 9.1 (95 %CI 5.4-12.7) months (p = 0.720) in the control and experimental arm. CONCLUSION: Endobiliary radiofrequency ablation prior metal stent insertion showed increased patency rate only in patients with cholangiocarcinoma, on the other hand, no improvement in survival was demonstrated in this randomized clinical study.

Light-Activated Carbon Monoxide Prodrugs Based on Bipyridyl Dicarbonyl Ruthenium(II) Complexes.

Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide-functionalised bipyridine scaffold (4-position) equipped with an alkyne functionality or a green-fluorescent BODIPY (boron-dipyrromethene) dye have been prepared and used to investigate their light-induced decarbonylation. UV/Vis, FTIR and 13 C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least-squares analysis (MCR-ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order to characterise the anti-proliferative and anti-apoptotic activities. The BODIPY-labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria.

In Situ In Vivo radiolabeling of polymer-coated hydroxyapatite nanoparticles to track their biodistribution in mice.

The imaging of healthy tissues and solid tumors benefits from the application of nanoparticle probes with altered pharmacokinetics, not available to low molecular weight compounds. However, the distribution and accumulation of nanoprobes in vivo typically take at least tens of hours to be efficient. For nanoprobes bearing a radioactive label, this is contradictory to the requirement of minimizing the radiation dose for patients by using as-short-as-feasible half-life radionuclides in diagnostics. Thus, we developed a two-stage diagnostic concept for monitoring long-lasting targeting effects with short-lived radioactive labels using bone-mimicking biocompatible polymer-coated and colloidally fully stabilized hydroxyapatite nanoparticles (HAP NPs) and bone-seeking radiopharmaceuticals. Within the pretargeting stage, the nonlabeled nanoparticles are allowed to circulate in the blood. Afterward, 99mTc-1-hydroxyethylidene-1.1-diphosphonate (99mTc-HEDP) is administered intravenously for in situ labeling of the nanoparticles and subsequent single-photon emission computed tomography/computed tomography (SPECT/CT) visualization. The HAP NPs, stabilized with tailored hydrophilic polymers, are not cytotoxic in vitro, as shown by several cell lines. The polymer coating prolongs the circulation of HAP NPs in the blood. The nanoparticles were successfully labeled in vivo with 99mTc-HEDP, 1 and 24 h after injection, and they were visualized by SPECT/CT over time in healthy mice.

Tungsten (VI) based "molecular puzzle" photoluminescent nanoparticles easily covered with biocompatible natural polysaccharides via direct chelation.

Multimodal probes, which can be simultaneously visualized by multiple imaging modalities, enable the cellular uptake, intracellular fate, biodistribution and elimination to be tracked in organisms. In this study, we report the synthesis of crystalline WO3 and CaWO4 doped with Eu3+ or Tb3+ nanoparticles (size range of 10-160 nm) coated with polysaccharides, and these nanoparticles constitute a versatile easy-to-construct modular toolbox for multimodal imaging. The particles adsorb significant amounts of polysaccharides from the solution, providing biocompatibility and may serve as a platform for labeling. For WO3, the sorption is reversible. However, on CaWO4, stable coating is formed. CaWO4/Tb3+ coated with chemisorbed dextrin, mannan, guar gum and sodium alginate successfully underwent endocytosis with HepG2 cells and was visualized using confocal microscopy.

Poly(2-ethyl-2-oxazoline) conjugates with doxorubicin for cancer therapy: In vitro and in vivo evaluation and direct comparison to poly[N-(2-hydroxypropyl)methacrylamide] analogues.

We designed and synthesized a new delivery system for the anticancer drug doxorubicin based on a biocompatible hydrophilic poly(2-ethyl-2-oxazoline) (PEtOx) carrier with linear architecture and narrow molar mass distribution. The drug is connected to the polymer backbone via an acid-sensitive hydrazone linker, which allows its triggered release in the tumor. The in vitro studies demonstrate successful cellular uptake of conjugates followed by release of the cytostatic cargo. In vivo experiments in EL4 lymphoma bearing mice revealed prolonged blood circulation, increased tumor accumulation and enhanced antitumor efficacy of the PEtOx conjugate having higher molecular weight (40 kDa) compared to the lower molecular weight (20 kDa) polymer. Finally, the in vitro and in vivo anti-cancer properties of the prepared PEtOx conjugates were critically compared with those of the analogous system based on the well-established PHPMA carrier. Despite the relatively slower intracellular uptake of PEtOx conjugates, resulting also in their lower cytotoxicity, there are no substantial differences in in vivo biodistribution and anti-cancer efficacy of both classes of polymer-Dox conjugates. Considering the synthetic advantages of poly(2-alkyl-2-oxazoline)s, the presented study demonstrates their potential as a versatile alternative to well-known PEO- or PHPMA-based materials for construction of drug delivery systems.

The Crisis Map of the Czech Republic: the nationwide deployment of an Ushahidi application for disasters.

Crisis mapping is a legitimate component of both crisis informatics and disaster risk management. It has become an effective tool for humanitarian workers, especially after the earthquake in Haiti in 2010. Ushahidi is among the many mapping platforms on offer in the growing field of crisis mapping, and involves the application of crowdsourcing to create online and interactive maps of areas in turmoil. This paper presents the Crisis Map of the Czech Republic, which is the first such instrument to be deployed nationwide in Central Europe. It describes the methodologies used in the preparatory work phase and details some practices identified during the creation and actual employment of the map. In addition, the paper assesses its structure and technological architecture, as well as its potential possible development in the future. Lastly, it evaluates the utilisation of the Crisis Map during the floods in the Czech Republic in 2013.

Fluorescent boronate-based polymer nanoparticles with reactive oxygen species (ROS)-triggered cargo release for drug-delivery applications.

A new drug-delivery system of polymer nanoparticles (NPs) bearing pinacol-type boronic ester and alkyne moieties displaying triggered self-immolative polymer degradation in the presence of reactive oxygen species (ROS) with the capability of cellular imaging is presented. The NPs specifically release their drug cargo under concentrations of ROS that are commonly found in the intracellular environment of certain tumors and of inflamed tissues and exhibit significant cytotoxicity to cancer cells compared to their non-ROS-responsive counterparts.

Benign biliary strictures refractory to standard bilioplasty treated using polydoxanone biodegradable biliary stents: retrospective multicentric data analysis on 107 patients.

OBJECTIVES: To assess mid-term outcome of biodegradable biliary stents (BBSs) to treat benign biliary strictures refractory to standard bilioplasty. METHODS: Institutional review board approval was obtained and patient consent was waived. 107 patients (61 males, 46 females, mean age 59 ± 16 years), were treated. Technical success and complications were recorded. Ninety-seven patients (55 males, 42 females, aged 57 ± 17 years) were considered for follow-up analysis (mean follow-up 23 ± 12 months). Fisher's exact test and Mann-Whitney U tests were used and a Kaplan-Meier curve was calculated. RESULTS: The procedure was always feasible. In 2/107 cases (2 %), stent migration occurred (technical success 98 %). 4/107 patients (4 %) experienced mild haemobilia. No major complications occurred. In 19/97 patients (18 %), stricture recurrence occurred. In this group, higher rate of subsequent cholangitis (84.2 % vs. 12.8 %, p = 0.001) and biliary stones (26.3 % vs. 2.5 %, p = 0.003) was noted. Estimated mean time to stricture recurrence was 38 months (95 % C.I 34-42 months). Estimated stricture recurrence rate at 1, 2, and 3 years was respectively 7.2 %, 26.4 %, and 29.4 %. CONCLUSION: Percutaneous placement of a BBS is a feasible and safe strategy to treat benign biliary strictures refractory to standard bilioplasty, with promising results in the mid-term period. KEY POINTS: • Percutaneous placement of a BBS is 100 % feasible. • The procedure appears free from major complications, with few minor complications. • BBSs offer promising results in the mid-term period. • With a BBS, external catheter/drainage can be removed early. • BBSs represent a new option in treating benign biliary stenosis.

Efficient Condensation of DNA into Environmentally Responsive Polyplexes Produced from Block Catiomers Carrying Amine or Diamine Groups.

The intracellular delivery of nucleic acids requires a vector system as they cannot diffuse across lipid membranes. Although polymeric transfecting agents have been extensively investigated, none of the proposed gene delivery vehicles fulfill all of the requirements needed for an effective therapy, namely, the ability to bind and compact DNA into polyplexes, stability in the serum environment, endosome-disrupting capacity, efficient intracellular DNA release, and low toxicity. The challenges are mainly attributed to conflicting properties such as stability vs efficient DNA release and toxicity vs efficient endosome-disrupting capacity. Accordingly, investigations aimed at safe and efficient therapies are still essential to achieving gene therapy clinical success. Taking into account the mentioned issues, herein we have evaluated the DNA condensation ability of poly(ethylene oxide)113-b-poly[2-(diisopropylamino)ethyl methacrylate]50 (PEO113-b-PDPA50), poly(ethylene oxide)113-b-poly[2-(diethylamino)ethyl methacrylate]50 (PEO113-b-PDEA50), poly[oligo(ethylene glycol)methyl ether methacrylate]70-b-poly[oligo(ethylene glycol)methyl ether methacrylate10-co-2-(diethylamino)ethyl methacrylate47-co-2-(diisopropylamino)ethyl methacrylate47] (POEGMA70-b-P(OEGMA10-co-DEA47-co-DPA47), and poly[oligo(ethylene glycol)methyl ether methacrylate]70-b-poly{oligo(ethylene glycol)methyl ether methacrylate10-co-2-methylacrylic acid 2-[(2-(dimethylamino)ethyl)methylamino]ethyl ester44} (POEGMA70-b-P(OEGMA10-co-DAMA44). Block copolymers PEO113-b-PDEA50 and POEGMA70-b-P(OEGMA10-co-DEA47-co-DPA47) were evidenced to properly condense DNA into particles with a desirable size for cellular uptake via endocytic pathways (R(H) ≈ 65-85 nm). The structure of the polyplexes was characterized in detail by scattering techniques and atomic force microscopy. The isothermal titration calorimetric data revealed that the polymer/DNA binding is endothermic; therefore, the process in entropically driven. The combination of results supports that POEGMA70-b-P(OEGMA10-co-DEA47-co-DPA47) condenses DNA more efficiently and with higher thermodynamic outputs than does PEO113-b-PDEA50. Finally, circular dichroism spectroscopy indicated that the conformation of DNA remained the same after complexation and that the polyplexes are very stable in the serum environment.

A Novel Nanoprobe for Multimodal Imaging Is Effectively Incorporated into Human Melanoma Metastatic Cell Lines.

To facilitate efficient drug delivery to tumor tissue, several nanomaterials have been designed, with combined diagnostic and therapeutic properties. In this work, we carried out fundamental in vitro and in vivo experiments to assess the labeling efficacy of our novel theranostic nanoprobe, consisting of glycogen conjugated with a red fluorescent probe and gadolinium. Microscopy and resazurin viability assays were used to study cell labeling and cell viability in human metastatic melanoma cell lines. Fluorescence lifetime correlation spectroscopy (FLCS) was done to investigate nanoprobe stability. Magnetic resonance imaging (MRI) was performed to study T1 relaxivity in vitro, and contrast enhancement in a subcutaneous in vivo tumor model. Efficient cell labeling was demonstrated, while cell viability, cell migration, and cell growth was not affected. FLCS showed that the nanoprobe did not degrade in blood plasma. MRI demonstrated that down to 750 cells/µL of labeled cells in agar phantoms could be detected. In vivo MRI showed that contrast enhancement in tumors was comparable between Omniscan contrast agent and the nanoprobe. In conclusion, we demonstrate for the first time that a non-toxic glycogen-based nanoprobe may effectively visualize tumor cells and tissue, and, in future experiments, we will investigate its therapeutic potential by conjugating therapeutic compounds to the nanoprobe.

Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging.

Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM). In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.

Multi-responsive polymer micelles as ellipticine delivery carriers for cancer therapy.

In the present study, we describe the synthesis and physicochemical properties of a novel pH- and thermoresponsive micellar drug delivery system for an anticancer ellipticinium derivative based on the triblock copolymer poly(ethylene oxide)-block-[tert-butylacrylamide-co-6-(N-methacryloylamino)hexanoic acid hydrazide]-block-poly(ethylene oxide). The system was designed to meet the basic criteria required for drug carrier systems, namely, solubility in water (overcoming the insolubility of ellipticine), satisfactory drug loading, particle size suitable for an efficient enhanced permeability and retention effect and adequate stability in blood plasma (pH 7.4) followed by rapid drug release in tumors or tumor cell endosomes (pH<6.5). The copolymer in the form of a unimer can be eliminated by kidneys because the weight-average molecular weight of 21 kDa is sufficiently below the renal threshold. The half-life of drug release in a pH 5.0 buffer solution (pH of a late endosome) was ~45 h, but a negligible amount of the free ellipticine derivative was detected at pH 7.4 (pH of blood). Consequently, this supramolecular polymer conjugate is a good candidate for the delivery of ellipticine-based drugs and will therefore be subjected to more detailed studies.

Manometric perfusion test in biliary strictures treatment.

BACKGROUND/AIMS: To assess the biliary manometric perfusion test (BMPT) for evaluating success in treating benign biliary strictures. METHODOLOGY: During 2003 to 2010, 29 patients were subjected to BMPT after percutaneous balloon dilatation treatment. Intrabiliary pressure less than 20cm of water was considered the success threshold. Results of BMPT evaluation were retrospectively compared with a similar group where the standard clinical test was used for evaluating treatment success. The clinical test group included 21 patients treated for biliary strictures from 1994 to 2006. RESULTS: The two groups were statistically similar by age and gender. The BMPT group was tested without complications and pressure inside the biliary tree was less than 20cm of water in 27 of 29 patients. Subsequently, catheters were removed from all 27. Three patients required re-interventions 13 days, 11 months and 32 months later. Kaplan-Meier survival analysis showed that the probability of biliary patency at 3 year was 82.2%. There was no significant difference between groups by this measure (log rank test, p=0.624). CONCLUSIONS: The manometric test is an alternative for evaluating success in treating benign biliary strictures. It is simple, less time-consuming, economical, safe, effective and more comfortable for patients than the clinical test.

Covered biodegradable stent: new therapeutic option for the management of esophageal perforation or anastomotic leak.

PURPOSE: This study was designed to evaluate our experience with the treatment of postoperative anastomotic leaks and benign esophageal perforations with covered biodegradable stents. MATERIALS AND METHODS: From 2008 to 2010, we treated five men with either an anastomotic leak or benign esophageal perforation by implanting of covered biodegradable Ella-BD stents. The average age of the patients was 60 (range, 38-74) years. Postoperative anastomotic leaks were treated in four patients (1 after esophagectomy, 1 after resection of diverticulum, 2 after gastrectomy). In one patient, perforation occurred as a complication of the treatment of an esophageal rupture (which occurred during a balloon dilatation of benign stenosis) with a metallic stent. RESULTS: Seven covered biodegradable stents were implanted in five patients. Primary technical success was 100%. Clinical success (leak sealing) was achieved in four of the five patients (80%). Stent migration occurred in three patients. In two of these patients, the leak had been sealed by the time of stent migration, therefore no reintervention was necessary. In one patient an additional stent had to be implanted. CONCLUSION: The use of biodegradable covered stents for the treatment of anastomotic leaks or esophageal perforations is technically feasible and safe. The initial results are promising; however, larger number of patients will be required to evaluate the capability of these biodegradable stents in the future. The use of biodegradable material for coverage of the stent is essential.

Multimodal oncological therapy comprising stents, brachytherapy, and regional chemotherapy for cholangiocarcinoma.

BACKGROUND/AIMS: To prospectively evaluate our palliative management of unresectable cholangiocarcinoma (CC) treated with tailored multimodal oncological therapy. METHODS: Between January 2005 and January 2010, 50 consecutive patients with unresectable CC and jaundice were palliated with percutaneous drainage. Forty-three patients underwent metallic-stent implantation followed by brachytherapy. Patients were divided into two arms: the intra-arterial chemotherapy arm (IA arm, n=17) consisted of patients treated with locoregional treatment (IA admission of Cisplatin and 5-fluorouracil, or chemoembolization with Lipiodol) and/or systemic chemotherapy, while the systemic chemotherapy arm (IV arm, n=23) included all the other patients, who were treated only with systemic chemotherapy. RESULTS: In total, 78 metal self-expandable stents were placed. Hilar involvement with mass-forming and periductal infiltrating types of CC (84%) was predominant. The average number of percutaneous interventional procedures was 11.61 per patient (range, 4-35). The median overall survival from diagnosis of disease for all patients was 13.5 months (range, 11.0-18.8 months). The median overall survival times were 25.2 months (range, 15.2-31.3 months) and 11.5 months (range, 8.5-12.6 months) in the IA and IV arms, respectively (p<0.05). The 1-, 2-, and 3-year survival rates in the IA and IV arms were 88.2%, 52.9%, and 10.1% and 43.5%, 25.4, and 0%, respectively. There were no major complications (WHO III/IV) due to interventional procedures. CONCLUSIONS: We could reach acceptable prognosis in patients with unresectable CC using complex tailored oncological therapy. However, the main limitations of prolonging survival are performance status, patient compliance and the maintaining of biliary tract patency.