Nanostructured Poly-l-lactide and Polyglycerol Adipate Carriers for the Encapsulation of Usnic Acid: A Promising Approach for Hepatoprotection

The present study investigates the utilization of nanoparticles based on poly-l-lactide (PLLA) and polyglycerol adipate (PGA), alone and blended, for the encapsulation of usnic acid (UA), a potent natural compound with various therapeutic properties including antimicrobial and anticancer activities. The development of these carriers offers an innovative approach to overcome the challenges associated with usnic acid’s limited aqueous solubility, bioavailability, and hepatotoxicity. The nanosystems were characterized according to their physicochemical properties (among others, size, zeta potential, thermal properties), apparent aqueous solubility, and in vitro cytotoxicity. Interestingly, the nanocarrier obtained with the PLLA-PGA 50/50 weight ratio blend showed both the lowest size and the highest UA apparent solubility as well as the ability to decrease UA cytotoxicity towards human hepatocytes (HepG2 cells). This research opens new avenues for the effective utilization of these highly degradable and biocompatible PLLA-PGA blends as nanocarriers for reducing the cytotoxicity of usnic acid

Efeitos de campo magnÃtico dependente da posiÃÃo em monocamadas e bicamadas de grafeno

Nos Ãltimos anos o grafeno tem se mostrado um interessante objeto de investigaÃÃo para cientistas ao redor do mundo, tanto pelas suas caracterÃsticas peculiares bem como suas propriedades eletrÃnicas. Muitas pesquisas jà foram realizadas com o intuito de desvendar esse ainda recÃm descoberto alÃtropo do carbono, jà tendo rendido um prÃmio Nobel em 2010. Aqui serÃo abordadas algumas dessas caracterÃsticas do grafeno focando em suas propriedades estruturais de rede e tambÃm suas propriedades eletrÃnicas. Serà estudada a interaÃÃo dos fÃrmions de Dirac, partÃculas relativÃsticas sem massa, sob a aÃÃo de um campo magnÃtico externo em uma e duas camadas de grafeno, com base na teoria de Dirac para baixas energias e no modelo de aproximaÃÃo tight-binding, comprovando equivalÃncia entre os dois modelos. Escrevendo o Hamiltoniano para uma folha de grafeno configura-se um problema de autovalor, sendo possÃvel obter a dispersÃo das bandas de energias do material e os chamados nÃveis de Landau, estes Ãltimos originados pela preseÃa de um campo magnÃtico perpendicular ao plano de interaÃÃo. Em seguida esses mesmos passos serÃo realizados para o sistema de bicamada. Em adiÃÃo, serÃo apresentados aqui os efeitos de um campo magnÃtico dependente da posiÃÃo, a fim de serem escritos os nÃveis de Landau. Este trabalho irà demonstrar assim, que um dos fatores que fazem o grafeno tÃo atrativo para pesquisa à justamente a interaÃÃo de partÃculas neste material

Formyl Peptide Receptor 2-Dependent cPLA2 and 5-LOX Activation Requires a Functional NADPH Oxidase

Phospholipases (PL) A2 catalyzes the hydrolysis of membrane phospholipids and mostly generates arachidonic acid (AA). The enzyme 5-lipoxygenase (5-LOX) can metabolize AA to obtain inflammatory leukotrienes, whose biosynthesis highly depends on cPLA2 and 5-LOX activities. Formyl Peptide Receptor 2 (FPR2) belongs to a subfamily of class A GPCRs and is considered the most versatile FPRs isoform. Signaling triggered by FPR2 includes the activation of several downstream kinases and NADPH oxidase (NOX)-dependent ROS generation. In a metabolomic analysis we observed a significant increase in AA concentration in FPR2-stimulated lung cancer cell line CaLu-6. We analyzed cPLA2 phosphorylation and observed a time-dependent increase in cPLA2 Ser505 phosphorylation in FPR2-stimulated cells, which was prevented by the MEK inhibitor (PD098059) and the p38MAPK inhibitor (SB203580) and by blocking NOX function. Similarly, we demonstrated that phosphorylation of 5-LOX at Ser271 and Ser663 residues requires FPR2-dependent p38MAPK and ERKs activation. Moreover, we showed that 5-LOX Ser271 phosphorylation depends on a functional NOX expression. Our overall data demonstrate for the first time that FPR2-induced ERK- and p38MAPK-dependent phosphorylation/activation of cPLA2 and 5-LOX requires a functional NADPH oxidase. These findings represent an important step towards future novel therapeutic possibilities aimed at resolving the inflammatory processes underlying many human diseases

A new approach for the preparation of hydrophilic poly(L-lactide) porous scaffold for tissue engineering by using lamellar single crystals

The aim of the present work was to study the possibility of building a porous scaffold for tissue engineering with a new bottom-up approach, obtained by assembling two-dimensional-micro, one-dimensional-nano sized poly(L-lactide) lamellar single crystals. This choice was dictated by the fact that polymer single crystals have structural and morphological features which can be exploited for chemical surface modifications to give a system characterized by a high specific active surface area. Indeed, the outermost amorphous regions can undergo functionalization reactions easily, whereas the inner, relatively inaccessible and inert crystalline core ensures morphological and mechanical stability. The assembling method employed to give the porous structures is based on a mould pressing, salt leaching technique and was found to be facile and versatile. In the first part of this paper we report the experimental results obtained to find the best conditions to achieve a suitable frame in terms of morphology, porosity and mechanical properties. In the second part of the paper, we describe the biological tests performed by using mouse fibroblasts seeded onto scaffolds prepared from pristine and surface hydrolysed lamellae. The results show that the samples obtained are suitable for sustaining cells which can proliferate and reach the inner pores of the scaffold containing hydrolysed single crystals much better than those prepared from pristine lamellae. Copyright (c) 2012 Society of Chemical Industr

VITRIFICAÇÃO DE MÓRULAS COMPACTAS Mus musculus: EFEITO DO TEMPO DE EQUILÍBRIO E DO PRÉ-RESFRIAMENTO DA SOLUÇÃO DE VITRIFICAÇÃO.

Setecentas e quinze mórulas compactas de Mus musculus da cepa Suíço Albina foram vitrificadas, em dois experimentos, para avaliar, in vitro e in vivo, o efeito do tempo de equilíbrio e do pré-resfriamento da solução de vitrificação na sobrevivência após descongelamento. No experimento I (n =417) as mórulas foram vitrificadas em 4 tratamentos utilizando-se dois tempos de equilíbrio (5 e 10 minutos) na solução de vitrificação intracelular composta por 10% de glicerol + 20% de 1,2 propanediol (SVa) e duas temperaturas (4 e 20° C) na solução de vitrificação extracelular composta por 25% de glicerol + 25% de 1,2 propanediol (SVb). A análise estatística não demonstrou diferenças significativas entre os 4 tratamentos, após o descongelamento e cultivo in vitro aos 15 minutos (TI=97%; TII =92%; TIII=92,8%; TIV=94%), 24 horas (TI =90,2%; TII =84%; TIII =83,5%; TIV=89,2%) e 48 horas (TI =79,4%; TII =75%; TIII =73,2% e TIV=77,4%). No experimento II, 298 mórulas foram vitrificadas em 2 tratamentos. No TI foram utilizados 5 minutos de equilíbrio na SVa e SVb a 20°C e no TII 10 minutos na SVa e SVb a 4° C. Considerando apenas as receptoras prenhes, o índice de implantações foi de 54,2% (TI), 52,7% (TII) e 56,1% (frescos), não diferindo entre os tratamentos. Porém o índice de fetos obtido com o TII (45,9%) foi significativamente maior do que o índice obtido com TI (30,5%). A duração do tempo de equilíbrio e o pré-resfriamento da solução de vitrificação influenciaram o desenvolvimento in vivo das mórulas vitrificadas

Surface modification of polyester films with polyfunctional amines: Effect on bacterial biofilm formation

The development of materials with antifouling properties is crucial in many areas, including medicine and food packaging. In this study, 2D-matrices made of polylactic acid (PLA), polyhydroxybutyrate (PHB), or polyhydroxybutyrate-co-valerate (PHB-HV) were surface functionalized through aminolysis with three poly- functional amines, 1,6-hexamethylenediamine (HDA), tetraethylenepentamine (TEPA), and polyallylamine hy- drochloride (PAH). The aminolysis procedure was thoroughly studied to ensure a high amount of amine groups while preserving the structural properties of the films. Interestingly, PHB and PHB-HV were found to be more sensitive to aminolysis than PLA, and the highest amino group density was achieved in surfaces etched with PAH. A decrease in the contact angle from ca. 85◦ to ca. 70◦ was revealed for polymers functionalized with HDA and TEPA and a drastic reduction in Staphylococcus epidermidis adhesion was observed for PHB-HV functionalized with the polymeric amine PAH. Polymer antimicrobial activity was found to be related to the degree of surface functionalization. The functionalized, cationic polymer surfaces were supposed to act upon contact with bacteria, without releasing any antimicrobial agent. The developed bioactive surfaces may have potential applications as flexible films for food packaging

One-Pot Preparation of Hydrophilic Polylactide Porous Scaffolds by Using Safe Solvent and Choline Taurinate Ionic Liquid

Polylactides (PLAs) are a class of polymers that are very appealing in biomedical applications due to their degradability in nontoxic products, tunable structural, and mechanical properties. However, they have some drawbacks related to their high hydrophobicity, lack of functional groups able to graft bioactive molecules, and solubility in unsafe solvents. To circumvent these shortcomings, porous scaffolds for tissue engineering were prepared by vigorously mixing a solution of isotactic and atactic PLA in nontoxic ethyl acetate at 70 °C with a water solution of choline taurinate. The partial aminolysis of the polymer ester bonds by taurine –NH2 brought about the formation of PLA oligomers with surfactant activity that stabilized the water-in-oil emulsion. Upon drying, a negligible shrinking occurred, and mechanically stable porous scaffolds were obtained. By varying the polymer composition and choline taurinate concentration, it was possible to modulate the pore dimensions (30–50 µm) and mechanical properties (Young’s moduli: 1–6 MPa) of the samples. Furthermore, the grafted choline taurinate made the surface of the PLA films hydrophilic, as observed by contact angle measurements (advancing contact angle: 76°; receding contact angle: 40°–13°). The preparation method was very simple because it was based on a one-pot mild reaction that did not require an additional purification step, as all the employed chemicals were nontoxic

Development of polysaccharide-based nano-systems containing lactoferrin for treatment of respiratory infections

Viral respiratory infections affect people of all ages, the emergence of new viruses and the selection of drug-resistant viral strains have prompted the development of new therapeutic strategies. The advent of nanotechnology in biomedicine has opened the way to new therapies for the delivery of drugs, proteins and nucleic acids. The small size provides these systems with excellent chemical-physical and pharmacokinetic properties, making it possible for them to transit inside small capillaries and cross biological barriers [1]. Among nano-carriers, the most promising in the biomedical field are those based on polysaccharides thanks to their biodegradability, bioactivity and biocompatibility as well as the presence of many functional groups that can be used to improve drug loading. This work was aimed at developing innovative therapies for the treatment of infection by respiratory viruses, such as influenza virus and adenovirus, and of the inflammatory processes caused by them. Lactoferrin (Lf) possesses many biological functions including antimicrobial, antitumor, anti-inflammatory activities [2]. Many studies have shown protective effects of lactoferrin against common viral infections [3]. Polysaccharide-based nanocarriers were developed in order to improve the lactoferrin therapeutic index. Alginate and hyaluronic acid were used to prepare two different nano-complexes for protein delivery using the complex coacervation method. The obtained systems were characterized by DLS technique to investigate their dimensions, polydispersity and stability. Morphological analysis, performed by scanning electron microscopy (SEM), confirmed the presence of nanostructures while thermal analysis (TGA) evidenced the formation of polysaccharide-protein interactions with an improvement in thermal stability (increase in TD) of the nanocomplexes as protein concentration increased. Circular dichroism measurements displayed no conformational change of lactoferrin after sonication treatment or interaction with alginate and hyaluronic acid. By physicochemical characterization were identified the most promising complexes then subjected to cytotoxicity analysis by MTT test on two different cell lines (A549 and MDCK). Preliminary results were positive. Further tests are ongoing to evaluate the anti-inflammatory and antiviral activity of the nanocomplexes

Self-assembled chitosan-sodium usnate drug delivery nanosystems: Synthesis, characterization, stability studies, in vitro cytotoxicity and in vivo biocompatibility against 143 B cells

Polymers are among the most studied materials as drug carriers, due to their tunable chemical structure and ability to self-assemble to give different types of nanostructures. In this study, chitosan (CS) nanoparticles (NPs) were investigated as carriers for the anticancer drug sodium usnate (NaU) for the treatment of osteosarcoma (OS), which is the most prevalent primary malignant bone sarcoma in pediatric and adolescent patients. CS nano-assembling was induced by electrostatic interactions with the drug and the anionic cross-linker tripolyphosphate, thus obtaining stable nanosystems and a high drug encapsulation efficiency. Importantly, a reduction in NaU hepatotoxicity when encapsulated in CS NPs compared to free NaU was evidenced, suggesting that CS may have a protective role against liver damage. Unfortunately, NaU encapsulation also reduced drug toxicity versus osteosarcoma 143B cells compared to free NaU. Nevertheless, NaU-loaded CS NPs (0.312 mg/mL) were found to decrease 143B cells viability after 48 h and 72 h treatment without being hepatotoxic. Interestingly, this system also stimulated in 143B cells Maspin production, an agent known for its tumor suppressor properties. Relevant synergistic activity between CS and NaU in promoting Maspin stimulation was found. That suggests the potential of the systems to reduce invasiveness of OS cancer

Esophageal Pressure Versus Gas Exchange to Set PEEP During Intraoperative Ventilation

BACKGROUND: Pneumoperitoneum and Trendelenburg position affect respiratory system mechanics and oxygenation during elective pelvic robotic surgery. The primary aim of this randomized pilot study was to compare the effects of a conventional low tidal volume ventilation with PEEP guided by gas exchange (VGas-guided) versus low tidal volume ventilation tailoring PEEP according to esophageal pressure (VPes-guided) on oxygenation and respiratory mechanics during elective pelvic robotic surgery. METHODS: This study was conducted in a single-center tertiary hospital between September 2017 and January 2019. Forty-nine adult patients scheduled for elective pelvic robotic surgery were screened; 28 subjects completed the full analysis. Exclusion criteria were American Society of Anesthesiologists physical status >= 3, contraindications to nasogastric catheter placement, and pregnancy. After dedicated naso/orogastric catheter insertion, subjects were randomly assigned to VGas-guided (F-IO2 and PEEP set to achieve S-pO2 > 94%) or VPes-guided (PEEP tailored to equalize end-expiratory transpulmonary pressure). Oxygenation (P-aO2/F-IO2) was evaluated (1) at randomization, after pneumoperitoneum and Trendelenburg application; (2) at 60 min; (3) at 120 min following randomization; and (4) at end of surgery. Respiratory mechanics were assessed during the duration of the study. RESULTS: Compared to VGas-guided, oxygenation was higher with VPes-guided at 60 min (388 +/- 90 vs 308 +/- 95 mm Hg, P = .02), at 120 min after randomization (400 +/- 90 vs 308 +/- 81 mm Hg, P = .008), and at the end of surgery (402 +/- 95 vs 312 +/- 95 mm Hg, P = .009). Respiratory system elastance was lower with VPes-guided compared to VGas-guided at 20 min (24.2 +/- 7.3 vs 33.4 +/- 10.7 cm H2O/L, P = .001) and 60 min (24.1 +/- 5.4 vs 31.9 +/- 8.5 cm H2O/L, P 5.006) from randomization. CONCLUSIONS: Oxygenation and respiratory system mechanics were improved when applying a ventilatory strategy tailoring PEEP to equalize expiratory transpulmonary pressure in subjects undergoing pelvic robotic surgery compared to a VGas-guided approach