Lipid conjugate dissociation analysis improves the in vivo understanding of lipid-based nanomedicine.

Lipid conjugates have advanced the field of lipid-based nanomedicine by promoting active-targeting (ligand, peptide, antibody), stability (PEGylation), controlled release (lipoid prodrug), and probe-based tracking (fluorophore). Recent findings indicate lipid conjugates dissociating from nanomedicine upon encountering a biological environment. Yet, implications for (pre)clinical outcomes remain unclear. In this study, using the zebrafish model (Danio rerio), we investigated the fate of liposome-incorporated lipid fluorophore conjugates (LFCs) after intravenous (IV) administration. LFCs having a bilayer mismatch and relatively polar fluorophore revealed counter-predictive outcomes for Caelyx/Doxil (clearance vs. circulating) and AmBisome-like liposomes (scavenger endothelial cell vs. macrophage uptake). Findings on LFC (mis)match for Caelyx/Doxil-like liposomes were supported by translational intravital imaging studies in mice. Importantly, contradicting observations suggest to originate from LFC dissociation in vivo, which was investigated by Asymmetric Flow Field-Flow Fractionation (AF4) upon liposome-serum incubation in situ. Our data suggests that LFCs matching with the liposome bilayer composition - that did not dissociate upon serum incubation - revealed improved predictive outcomes for liposome biodistribution profiles. Altogether, this study highlights the critical importance of fatty acid tail length and headgroup moiety when selecting lipid conjugates for lipid-based nanomedicine.

Chatbot for communicating with university students in emergency situation.

Chatbots have arrived in higher education, and professors are trying to make the most of them. Typically, chatbots are used to help students learn academic subjects. In times of crisis, such as the COVID-19 pandemic, students who were not living with their families during the course, especially international students, were isolated and in critical situations. The student services offices were in constant contact with these students to solve problems, advise them and support them during their stay, within the constraints of confinement and the guidelines dictated by the country at the time. The student services offices were overwhelmed trying to help these students because, although the students' problems were very recurrent, the government guidelines changed from one day to the next. This article proposes the use of a chatbot to provide initial support to students during crisis situations, and facilitate communication between them and the university. The chatbot was tested by more than 160 students and student services staff. The findings support the use of chatbots as a potential tool to facilitate communication with students in emerging emergency situations, and encourage universities to adopt these types of smart tools to be prepared to respond quickly and efficiently to students in times of crisis.

Decarbonisation of calcium carbonate in sodium hydroxide solutions under ambient conditions: effect of residence time and mixing rates.

The decarbonisation of CaCO3 is essential for the production of lime (Ca(OH)2 and CaO), which is a commodity required in several large industries and the main precursor for cement production. CaCO3 is usually decarbonised at high temperatures, generating gaseous CO2 which will require post-process capture to minimise its release into the environment. We have developed a new process that can decarbonise CaCO3 under ambient conditions, while sequestering the CO2 as Na2CO3·H2O or Na2CO3 in the same stage. Here, the effects of increasing stirring rates and residence times on reaction efficiency of the key reaction occurring between CaCO3 and NaOH solution are studied. It is shown that the reaction is enhanced at lower stirring rates and longer residence times up to 300 seconds of contact between the reactants. The mass balance performed for Ca and CO2 revealed that up to the 95% of the process CO2 embodied in CaCO3 was sequestered, with maximum capture rate assessed at nn moles CO2 captured per second of reaction progress. A deeper insight into the precipitation of Na2CO3·H2O or Na2CO3 under different reaction conditions was gained, and SEM-EDX analysis enabled the observation of the reaction front by detection of Na migrating towards inner regions of partially-reacted limestone chalk particles.

The membrane transporter lactose permease increases lipid bilayer bending rigidity.

Cellular life relies on membranes, which provide a resilient and adaptive cell boundary. Many essential processes depend upon the ease with which the membrane is able to deform and bend, features that can be characterized by the bending rigidity. Quantitative investigations of such mechanical properties of biological membranes have primarily been undertaken in solely lipid bilayers and frequently in the absence of buffers. In contrast, much less is known about the influence of integral membrane proteins on bending rigidity under physiological conditions. We focus on an exemplar member of the ubiquitous major facilitator superfamily of transporters and assess the influence of lactose permease on the bending rigidity of lipid bilayers. Fluctuation analysis of giant unilamellar vesicles (GUVs) is a useful means to measure bending rigidity. We find that using a hydrogel substrate produces GUVs that are well suited to fluctuation analysis. Moreover, the hydrogel method is amenable to both physiological salt concentrations and anionic lipids, which are important to mimic key aspects of the native lactose permease membrane. Varying the fraction of the anionic lipid in the lipid mixture DOPC/DOPE/DOPG allows us to assess the dependence of membrane bending rigidity on the topology and concentration of an integral membrane protein in the lipid bilayer of GUVs. The bending rigidity gradually increases with the incorporation of lactose permease, but there is no further increase with greater amounts of the protein in the membrane.

Poly-Epsilon-Lysine Hydrogels with Dynamic Crosslinking Facilitates Cell Proliferation.

The extracellular matrix (ECM) is a three-dimensional network within which fundamental cell processes such as cell attachment, proliferation, and differentiation occur driven by its inherent biological and structural cues. Hydrogels have been used as biomaterials as they possess many of the ECM characteristics that control cellular processes. However, the permanent crosslinking often found in hydrogels fails to recapitulate the dynamic nature of the natural ECM. This not only hinders natural cellular migration but must also limit cellular expansion and growth. Moreover, there is an increased interest in the use of new biopolymers to create biomimetic materials that can be used for biomedical applications. Here we report on the natural polymer poly-ε-lysine in forming dynamic hydrogels via reversible imine bond formation, with cell attachment promoted by arginine-glycine-aspartic acid (RGD) incorporation. Together, the mechanical properties and cell behavior of the dynamic hydrogels with low poly-ε-lysine quantities indicated good cell viability and high metabolic activity.

Controlled Peptide-Mediated Vesicle Fusion Assessed by Simultaneous Dual-Colour Time-Lapsed Fluorescence Microscopy.

We have employed a model system, inspired by SNARE proteins, to facilitate membrane fusion between Giant Unilamellar Vesicles (GUVs) and Large Unilamellar Vesicles (LUVs) under physiological conditions. In this system, two synthetic lipopeptide constructs comprising the coiled-coil heterodimer-forming peptides K4, (KIAALKE)4, or E4, (EIAALEK)4, a PEG spacer of variable length, and a cholesterol moiety to anchor the peptides into the liposome membrane replace the natural SNARE proteins. GUVs are functionalized with one of the lipopeptide constructs and the fusion process is triggered by adding LUVs bearing the complementary lipopeptide. Dual-colour time lapse fluorescence microscopy was used to visualize lipid- and content-mixing. Using conventional confocal microscopy, lipid mixing was observed on the lipid bilayer of individual GUVs. In addition to lipid-mixing, content-mixing assays showed a low efficiency due to clustering of K4-functionalized LUVs on the GUVs target membranes. We showed that, through the use of the non-ionic surfactant Tween 20, content-mixing between GUVs and LUVs could be improved, meaning this system has the potential to be employed for drug delivery in biological systems.

Delineating the Rules for Structural Adaptation of Membrane-Associated Proteins to Evolutionary Changes in Membrane Lipidome.

Membrane function is fundamental to life. Each species explores membrane lipid diversity within a genetically predefined range of possibilities. How membrane lipid composition in turn defines the functional space available for evolution of membrane-centered processes remains largely unknown. We address this fundamental question using related fission yeasts Schizosaccharomyces pombe and Schizosaccharomyces japonicus. We show that, unlike S. pombe that generates membranes where both glycerophospholipid acyl tails are predominantly 16-18 carbons long, S. japonicus synthesizes unusual "asymmetrical" glycerophospholipids where the tails differ in length by 6-8 carbons. This results in stiffer bilayers with distinct lipid packing properties. Retroengineered S. pombe synthesizing the S.-japonicus-type phospholipids exhibits unfolded protein response and downregulates secretion. Importantly, our protein sequence comparisons and domain swap experiments support the hypothesis that transmembrane helices co-evolve with membranes, suggesting that, on the evolutionary scale, changes in membrane lipid composition may necessitate extensive adaptation of the membrane-associated proteome.

Distinct roles of SNARE-mimicking lipopeptides during initial steps of membrane fusion.

A model system for membrane fusion, inspired by SNARE proteins and based on two complementary lipopeptides CPnE4 and CPnK4, has been recently developed. It consists of cholesterol (C), a poly(ethylene glycol) linker (Pn) and either a cationic peptide K4 (KIAALKE)4 or an anionic peptide E4 (EIAALEK)4. In this paper, fluorescence spectroscopy is used to decipher distinct but complementary roles of these lipopeptides during early stages of membrane fusion. Molecular evidence is provided that different distances of E4 in CPnE4 and K4 in CPnK4 from the bilayer represent an important mechanism, which enables fusion. Whereas E4 is exposed to the bulk and solely promotes membrane binding of CPnK4, K4 loops back to the lipid-water interface where it fulfills two distinct roles: it initiates bilayer contact by binding to CPnE4 containing bilayers; and it initiates fusion by modulating the bilayer properties. The interaction between CPnE4 and CPnK4 is severely down-regulated by binding of K4 to the bilayer and possible only if the lipopeptides approach each other as constituents of different bilayers. When the complementary lipopeptides are localized in the same bilayer, hetero-coiling is disabled. These data provide crucial insights as to how fusion is initiated and highlight the importance of both peptides in this process.

Evaluation of dextran(ethylene glycol) hydrogel films for giant unilamellar lipid vesicle production and their application for the encapsulation of polymersomes.

Giant Unilamellar Vesicles (GUVs) prepared from phospholipids are becoming popular membrane model systems for use in biophysical studies. The quality, size and yield of GUVs depend on the preparation method used to obtain them. In this study, hydrogels consisting of dextran polymers crosslinked by poly(ethylene glycol) (DexPEG) were used as hydrophilic frameworks for the preparation of vesicle suspensions under physiological ionic strength conditions. A comparative study was conducted using hydrogels with varied physicochemical properties to evaluate their performance for GUV production. The prepared GUVs were quantified by flow cytometry using the Coulter Principle to determine the yield and size distribution. We find that hydrogels of lower mechanical strength, increased swellability and decreased lipid interaction favour GUV production, while their resulting size is determined by the surface roughness of the hydrogel film. Moreover, we embedded polymersomes into the crosslinked hydrogel network, creating a DexPEG - polymersome hybrid film. The re-hydration of lipids on those hybrid substrates led to the production of GUVs and the efficient encapsulation of polymersomes in the lumen of GUVs.

Complicaciones atípicas post - CPRE / Atypical complications post - CPRE

La colangiografía retrógrada endoscópica (CPRE) se ha convertido en un procedimiento esencial en el diagnóstico y tratamiento de las enfermedades biliopancreáticas. Las complicaciones de este procedimiento son infrecuentes, pero potencialmente graves, siendo necesario saber reconocerlas para la aplicación del tratamiento adecuado. Se presenta el siguiente caso clínico de paciente femenina de 33 años quien cursa con unión biliopancreatica anómala, posteriormente presenta enfisema subcutáneo, neumotórax bilateral, sepsis de punto de partida abdominal, pseudoretinopatía de Purtscher y por último encefalopatía de wernicke, debido a una perforación en dicho procedimiento. El diagnóstico precoz de las lesiones iatrogénicas tras la realización de CPRE determinará el correcto tratamiento de esta complicación, que debe comprender variaciones en la clínica y fisiología del paciente.

Endoscopic retrograde cholangiography (ERCP) has become an essential procedure in the diagnosis and treatment of biliopancreatic diseases. Complications of this procedure are unusuals, but potentially dangerous, being necessary to know them how to recognize for the application of appropriate treatment. The following case belongs to. A female patient aged 33 who presents with abnormal pancreatobiliar union subsequently presents subcutaneous emphysema , bilateral pneumothorax , sepsis point abdominal starting pseudoretinopatía Purtscher and finally Wernicke encephalopathy , due to a perforation in that procedure. Previous diagnosis of iatrogenic injury after ERCP determines the proper treatment of this complication, which should include variations in clinical and patient physiology.

Targeted anion transporter delivery by coiled-coil driven membrane fusion.

Synthetic anion transporters (anionophores) have potential as biomedical research tools and therapeutics. However, the efficient and specific delivery of these highly lipophilic molecules to a target cell membrane is non-trivial. Here, we investigate the delivery of a powerful anionophore to artificial and cell membranes using a coiled-coil-based delivery system inspired by SNARE membrane fusion proteins. Incorporation of complementary lipopeptides into the lipid membranes of liposomes and cell-sized giant unilamellar vesicles (GUVs) facilitated the delivery of a powerful anionophore into GUVs, where its anion transport activity was monitored in real time by fluorescence microscopy. Similar results were achieved using live cells engineered to express a halide-sensitive fluorophore. We conclude that coiled-coil driven membrane fusion is a highly efficient system to deliver anionophores to target cell membranes.

Imaging the lipid bilayer of giant unilamellar vesicles using red-to-blue light upconversion.

Red-to-blue triplet-triplet annihilation upconversion was obtained in giant unilamellar vesicles. The upconverted light was homogeneously distributed across the membrane and could be utilized for the imaging of individual giant vesicles in three dimensions. These results show the great potential of TTA-UC for imaging applications under anoxic conditions.

Visualization and quantification of transmembrane ion transport into giant unilamellar vesicles.

Transmembrane ion transporters (ionophores) are widely investigated as supramolecular agents with potential for biological activity. Tests are usually performed in synthetic membranes that are assembled into large unilamellar vesicles (LUVs). However transport must be followed through bulk properties of the vesicle suspension, because LUVs are too small for individual study. An alternative approach is described whereby ion transport can be revealed and quantified through direct observation. The method employs giant unilamellar vesicles (GUVs), which are 20-60 µm in diameter and readily imaged by light microscopy. This allows characterization of individual GUVs containing transporter molecules, followed by studies of transport through fluorescence emission from encapsulated indicators. The method provides new levels of certainty and relevance, given that the GUVs are similar in size to living cells. It has been demonstrated using a highly active anion carrier, and should aid the development of compounds for treating channelopathies such as cystic fibrosis.

Preparation of size tunable giant vesicles from cross-linked dextran(ethylene glycol) hydrogels.

We present a novel chemically cross-linked dextran-poly(ethylene glycol) hydrogel substrate for the preparation of dense vesicle suspensions under physiological ionic strength conditions. These vesicles can be easily diluted for individual study. Modulating the degree of cross-linking within the hydrogel network results in tuning of the vesicle size distribution.

Resección mucosal endoscópica de recto: a propósito de un caso Hospital Universitario “Dr. Pedro Emilio Carrillo” Valera - Edo Trujillo / Endoscopic mucosal rectal resection: a case University Hospital

Los pólipos de colon son lesiones consideradas premalignas. El riesgo es mayor en lesiones de más de un centímetro de diámetro, con componente velloso y displasia avanzada (Pólipos avanzados). Su extracción disminuye la frecuencia de desarrollo de neoplasias malignas. Clínicamente pueden causar sangrado digestivo, pérdida de proteínas y en ocasiones constituir el motor de una invaginación. Pueden contener un carcinoma intramucoso y ser la resección endoscópica un procedimiento curativo. La resección endoscópica es una excelente alternativa a la cirugía convencional con menor morbimortalidad y menor costo. La frecuencia de neoplasia avanzada y los cambios displásicos es mayor en lesiones de 2 cm o más. Las complicaciones como sangrados se presentan con mayor frecuencia en lesiones pediculadas grandes y la perforación es mayor en las lesiones sésiles extendidas(1,2). En el último tiempo es posible abordar lesiones de gran tamaño, gracias a la inyección submucosa de sustancias que permiten elevar la lesión y su resección más segura (Mucosectomías o resección mucosa endoscópica). Se cuenta además con la posibilidad de usar endoloops, endoclips, además de la terapia local de APC (Argón Plasma Coagulator)(3, 4, 5)...

Colon polyps are considered premalignant lesions. The risk is higher in lesions larger than one centimeter in diameter, villous component and advanced dysplasia (advanced polyps).Extraction decreases the frequency of malignancies development. Clinically they can cause gastrointestinal bleeding, protein loss and, sometimes, be the engine of an intussusception. They may contain Carcinoma and endoscopic resection be a curative procedure.Endoscopic resection is an excellent alternative to conventional surgery with less morbidity and lower.cost The frequency of advanced neoplasia and dysplastic changes is greater in lesions 2 cm or more. Complications such as bleeding occur more frequently in large pedunculated lesions and perforation is higher in sessile lesions extended(1,2). In recent times it is possible to address large lesions, by submucosal injection of substances that can elevate the injury and safer resection (mucosectomy or endoscopic mucosal resection). It also has the ability to use endoloops, endoclips, in addition to local therapy of APC (Argon Plasma Coagulator)(3, 4, 5)...

Manejo paliativo endoscópico de tumor de páncreas con compromiso biliar y duodenal: reporte de un caso / Palliative endoscopic management of pancreatic tumor with biliary and duodenal involvement: a case report

Las neoplasias de la región periampular engloban una serie de lesiones que por su cercanía se comportan de manera similar. Entre ellas encontramos a las neoplasias malignas de la ampolla de váter, del duodeno, del colédoco y del páncreas, de éstas el 95% son adenocarcinomas. El síndrome ictérico obstructivo es la forma de presentación más frecuente. Otras de las formas de presentación es la obstrucción de tracto de salida gástrico debido a infiltración del duodeno en cerca del cinco 5% de los pacientes. En la actualidad, la única opción curativa para esta enfermedad es la resección quirúrgica: la pancreatoduodenectomía. El tratamiento paliativo de elección, desde la descripción realizada por Soehendra para el manejo de la obstrucción biliar, en la actualidad es el drenaje endoscópico...

Periampullary region neoplasm`s encompasses a series of injuries, because of its proximity they behave similarly. Among them we find malignant neoplasm of the ampulla of Vater, duodenum, bile duct and pancreas; 95% of these are adenocarcinomas. Pancreatic cancer is the most common of these tumors, constituting the fifth leading cause of cancer deaths. The obstructive jaundice syndrome is the most common presentation. Other presentation is the obstruction of gastric outflow due to infiltration of the duodenum in about 5% of patients. Currently, the only curative option for this disease is surgical resection (pancreaticoduodenectomy), the palliative treatment of choice...

Proteliposome-derived Cochleate as an immunomodulator for nasal vaccine.

Proteoliposome (PL) has been recently used as a protective intramuscular (i.m.) anti-meningococcal BC vaccine. It induces a preferential Th 1 type of immune response. Nevertheless, mucosal protection is mainly mediated by IgA antibody response, which is not usually induced by i.m. vaccination route. IgA antibody production needs the stimulation of Th3 subpopulation, which is also related to the induction of small dose tolerance. We hypothesized that PL-derived Cochleate can induce a specific mucosal IgA and systemic IgG antibody responses. We could show that mice immunized with two or three intranasal doses of PL-derived Cochleate developed significantly increased levels of local anti PL IgA and systemic IgG antibody responses. Thus, our results suggest that PL-derived Cochleate can be used as a promising immunomodulator and delivery system for the development of mucosal, particularly nasal vaccines.

Novel adjuvant based on a proteoliposome-derived cochleate structure containing native lipopolysaccharide as a pathogen-associated molecular pattern.

Proteoliposomes (PL) from Neisseria meningitidis B have been widely used as a core antigen for antimeningococcal vaccination. PL contain major outer membrane proteins, LPS and phospholipids, and they induce a strong Th1 immune response, but they have low stability in solution. Attending to the need for new vaccine adjuvants, we developed a highly stable cochleate structure (CS) from PL using a technology that allows easy incorporation of new antigens. We explored the ability of PLCS to activate the immune system and its possible application as an adjuvant for parenteral and mucosal routes. Our results showed that PLCS were able to upregulate the expression of MHC class II and costimulatory molecules on human dendritic cells, as well as being able to stimulate the production of soluble mediators of a Th1 response, such as IL-12 and nitric oxide. High levels of anti-PL IgG were detected in serum after i.m. or mucosal (oral and nasal) administration, but also anti-PL secretory IgA was produced in saliva following nasal delivery. The immune response polarization to a Th1 pattern was confirmed by the induction of IgG2a antibodies, positive delayed type hypersensitivity reactions, and IFN-gamma production by splenocytes from immunized mice. The adjuvant potential was explored using PLCS containing ovalbumin (Ova). PLCS-Ova was able to elicit a substantial increase in anti-Ova IgG compared with Ova alone. In addition, a significant reduction in lesion size was observed in mice immunized with Leishmania major antigens in PLCS after challenge with virulent protozoa, suggesting at least partial modulation of the Th2 environment induced by this parasite. In conclusion, our results support the use of PLCS as a potent Th1 adjuvant for parenteral and mucosal vaccines.

Tratamientos cosméticos integrales, nueva experiencia / Integral cosmetics treatments, a new experience

La salud cutánea constituye un verdadero desafío para los especialistas: el tema estético cobra en la actualidad una fuerza impresionante, por el aumento creciente de la esperanza de vida, lo cual motiva a los profesionales de esta rama, a buscar nuevas soluciones a estos problemas. Estudios realizados han comprobodo que las expresiones clínicas del envejecimiento cutáneo esta entre las primeras causas referdas por los pacientes que acuden a consulta de Cosmetología (AU)