Qualitative Histologic Assessment vs. Geomorphometric Analysis of Nerve Fiber Shape after the Intraneural Application of Liposomal Bupivacaine / Evaluación Histológica Cualitativa Versus Análisis Geomorfométrico de la Forma de la Fibra Nerviosa Después de la Aplicación Intraneural de Bupivacaína Liposomal

SUMMARY: The preserved form of all components of the nerve fiber is a prerequisite for the proper conduction of the nerve impulse. various factors can change the shape of nerve fibers. In everyday practice, qualitative histological analysis is the gold standard for detecting changes in shape. Geometric morphometry is an innovative method that objectively enables the assessment of changes in nerve fibers' shape after local anesthetics action. A total of sixty sciatic nerves were used as material, which was intraneural injected with saline solution in the control group (n=30), and a solution of 1.33 % liposomal bupivacaine (n=30) in the test group. After the animals were sacrificed, nerve samples were taken and histological preparations were made. The preparations were first described and examined using a qualitative histological method, after which digital images were made. The images were entered into the MorphoJ program and processed using the method of geometric morphometry. Qualitative histological examination revealed no differences in nerve fibers after intraneurally applied physiological solution and liposomal bupivacaine. Using the method of geometric morphometry, a statistically significant change in the shape of axons was found after intraneurally applied saline solution and liposomal bupivacaine (p=0.0059). No significant differences in histological changes were found after the qualitative histological analysis of nerve fiber cross-section preparations. A statistically significant change in the shape of nerve fiber axons was observed after geometric morphometric analysis of digital images after intraneural application of saline and liposomal bupivacaine.

La forma conservada de todos los componentes de la fibra nerviosa es un requisito previo para la conducción correcta del impulso nervioso. Varios factores pueden cambiar la forma de las fibras nerviosas. En la práctica diaria, el análisis histológico cualitativo es el estándar de oro para detectar cambios de forma. La morfometría geométrica es un método innovador que permite evaluar objetivamente los cambios en la forma de las fibras nerviosas después de la acción de los anestésicos locales. Se utilizó como material un total de sesenta nervios ciáticos, que se inyectaron intraneuralmente con solución salina en el grupo control (n=30), y una solución de bupivacaína liposomal al 1,33 % (n=30) en el grupo de prueba. Después de sacrificados los animales, se tomaron muestras de nervios y se realizaron preparaciones histológicas. Primero se describieron y examinaron las preparaciones utilizando un método histológico cualitativo, después de lo cual se tomaron imágenes digitales. Las imágenes fueron ingresadas al programa MorphoJ y procesadas mediante el método de morfometría geométrica. El examen histológico cualitativo no reveló diferencias en las fibras nerviosas después de la aplicación intraneural de solución fisiológica y bupivacaína liposomal. Usando el método de morfometría geométrica, se encontró un cambio estadísticamente significativo en la forma de los axones después de la aplicación intraneural de solución salina y bupivacaína liposomal (p = 0,0059). No se encontraron diferencias significativas en los cambios histológicos después del análisis histológico cualitativo de las preparaciones de secciones transversales de fibras nerviosas. Se observó un cambio estadísticamente significativo en la forma de los axones de las fibras nerviosas después del análisis de morfometría geométrica de imágenes digitales después de la aplicación intraneural de solución salina y bupivacaína liposomal.

Eugenol and its liposome-based nano carrier reduce anxiety by inhibiting glyoxylase-1 expression in mice / Eugenol e seu nanocarreador à base de lipossoma reduzem a ansiedade ao inibir a expressão de glioxalase 1 em camundongos

Abstract The most common form of psycho-social dysfunction is anxiety with depression being related closely without any age bar. They are present with combined state of sadness, confusion, stress, fear etc. Glyoxalase system contains enzyme named glyoxalase 1 (GLO1).It is a metabolic pathway which detoxifies alpha-oxo-aldehydes, particularly methylglyoxal (MG). Methylglyoxal is mainly made by the breakdown of the glycolytic intermediates, glyceraldehyde-3-phosphates and dihydroxyacetone phosphate. Glyoxylase-1 expression is also related with anxiety behavior. A casual role or GLO-1 in anxiety behavior by using viral vectors for over expression in the anterior cingulate cortex was found and it was found that local GLO-1 over expression increased anxiety behavior. The present study deals with the molecular mechanism of protective activity of eugenol against anxiolytic disorder. A pre-clinical animal study was performed on 42 BALB/c mice. Animals were given stress through conventional restrain model. The mRNA expression of GLO-1 was analyzed by real time RT-PCR. Moreover, the GLO-1 protein expression was also examined by immunohistochemistry in whole brain and mean density was calculated. The mRNA and protein expressions were found to be increased in animals given anxiety as compared to the normal control. Whereas, the expressions were decreased in the animals treated with eugenol and its liposome-based nanocarriers in a dose dependent manner. However, the results were better in animals treated with nanocarriers as compared to the compound alone. It is concluded that the eugenol and its liposome-based nanocarriers exert anxiolytic activity by down-regulating GLO-1 protein expression in mice.

Resumo A forma mais comum de disfunção psicossocial é a ansiedade intimamente relacionada com a depressão, sem qualquer barreira de idade. Elas estão presentes em um estado combinado de tristeza, confusão, estresse, medo etc. O sistema de glioxalase contém uma enzima chamada glioxalase 1 (GLO1). É uma via metabólica que desintoxica alfa-oxo-aldeídos, particularmente metilglioxal (MG). O metilglioxal é produzido principalmente pela quebra dos intermediários glicolíticos, gliceraldeído-3-fosfatos e fosfato de diidroxiacetona. A expressão da glioxalase 1 também está relacionada ao comportamento de ansiedade. Um papel casual ou GLO1 no comportamento de ansiedade usando vetores virais para superexpressão no córtex cingulado anterior foi encontrado e descobriu-se que a superexpressão local de GLO1 aumentava o comportamento de ansiedade. O presente estudo trata do mecanismo molecular da atividade protetora do eugenol contra o transtorno ansiolítico. Um estudo pré-clínico em animais foi realizado em 42 camundongos BALB / c. Os animais foram submetidos ao estresse por meio do modelo de contenção convencional. A expressão de mRNA de GLO1 foi analisada por RT-PCR em tempo real. Além disso, a expressão da proteína GLO1 também foi examinada por imuno-histoquímica em todo o cérebro e a densidade média foi calculada. Verificou-se que as expressões de mRNA e proteínas estavam aumentadas em animais que receberam ansiedade em comparação com o controle normal. Considerando que as expressões foram diminuídas nos animais tratados com eugenol e seus nanocarreadores baseados em lipossomas de forma dependente da dose. No entanto, os resultados foram melhores em animais tratados com nanocarreadores em comparação com o composto sozinho. Conclui-se que o eugenol e seus nanocarreadores baseados em lipossomas exercem atividade ansiolítica por regulação negativa da expressão da proteína GLO1 em camundongos.

Praziquantel-encapsulated niosomes against Schistosoma mansoni with reduced sensitivity to praziquantel / Niosomas encapsulados en prazicuantel contra Schistosoma mansoni con sensibilidad reducida al prazicuantel

Introduction: Praziquantel (PZQ) is the only commercially available drug for schistosomiasis. The current shortage of alternative effective drugs and the lack of successful preventive measures enhance its value. The increase in the prevalence of PZQ resistance under sustained drug pressure is, therefore, an upcoming issue. Objective: To overcome the tolerance to PZQ using nanotechnology after laboratory induction of a Schistosoma mansoni isolate with reduced sensitivity to the drug during the intramolluscan phase. Materials and methods: Shedding snails were treated with PZQ doses of 200 mg/kg twice/ week followed by an interval of one week and then repeated twice in the same manner. The success of inducing reduced sensitivity was confirmed in vitro via the reduction of cercarial response to PZQ regarding their swimming activity and death percentage at different examination times. Results: Oral treatment with a single PZQ dose of 500 mg/kg in mice infected with cercariae with reduced sensitivity to PZQ revealed a non-significant reduction (35.1%) of total worm burden compared to non-treated control mice. Orally inoculated PZQ- encapsulated niosomes against S. mansoni with reduced sensitivity to PZQ successfully regained the pathogen's sensitivity to PZQ as evidenced by measuring different parameters in comparison to the non-treated infected animals with parasites with reduced sensitivity to PZQ. The mean total worm load was 1.33 ± 0.52 with a statistically significant reduction of 94.09% and complete eradication of male worms. We obtained a remarkable increase in the percentage reduction of tissue egg counts in the liver and intestine (97.68% and 98.56%, respectively) associated with a massive increase in dead eggs and the complete absence of immature stages. Conclusion: PZQ-encapsulated niosomes restored the drug sensitivity against laboratory- induced S. mansoni adult worms with reduced sensitivity to PZQ.

Introducción. El prazicuantel es el único fármaco disponible comercialmente para la esquistosomiasis. La escasez actual de medicamentos alternativos y la falta de medidas preventivas eficaces aumentan su valor. La creciente prevalencia de la resistencia al prazicuantel bajo una presión prolongada del fármaco es, por tanto, un tema emergente. Objetivos. Superar la tolerancia al prazicuantel mediante nanotecnología después de la inducción en laboratorio de un aislamiento de Schistosoma mansoni con sensibilidad reducida al fármaco durante la fase intramolusco. Materiales y métodos. Los caracoles que liberaban cercarias se trataron con prazicuantel en dosis de 200 mg/kg dos veces por semana, seguidas de un intervalo de una semana, y luego se repitieron dos veces de la misma manera. La inducción exitosa de la sensibilidad reducida se confirmó in vitro mediante la reducción de la reacción de las cercarias al prazicuantel con respecto a su actividad de natación y el porcentaje de muerte en diferentes momentos de examen. El éxito en inducir una menor sensibilidad se confirmó in vitro mediante la reducción de la reacción de las cercarias al prazicuantel. Resultados. El tratamiento oral con una dosis única de prazicuantel de 500 mg/kg en ratones infectados con cercarias con sensibilidad reducida al prazicuantel, reveló una reducción no significativa (35,1 %) de la carga total de gusanos en comparación con los ratones de control no tratados. Los niosomas encapsulados en prazicuantel inoculados por vía oral contra S. mansoni con sensibilidad reducida al prazicuantel, permitieron reestablecer con éxito la sensibilidad del patógeno al medicamento, como lo demostró la medición de diferentes parámetros en comparación con los animales infectados no tratados con parásitos con sensibilidad reducida a prazicuantel. La carga media total de gusanos fue de 1,33 ± 0,52, con una reducción estadísticamente significativa del 94,09 %, y la erradicación completa de los gusanos machos adultos. Se obtuvo un aumento notable en el porcentaje de reducción del recuento de huevos en el tejido del hígado y el intestino (97,68 % y 98,56 %, respectivamente), asociado con un aumento masivo de huevos muertos y ausencia total de estadios inmaduros. Conclusión. Los niosomas encapsulados en prazicuantel restauraron la sensibilidad al fármaco contra gusanos adultos de S. mansoni con sensibilidad reducida al prazicuantel inducida en el laboratorio.

Desenvolvimento e caracterização de lipossomas peguilados para veiculação de L-asparaginase / Development and characterization of peg-grafted liposomes for lasparaginase encapsulation

A Leucemia Linfoide Aguda (LLA) é um câncer de maior incidência em crianças, e tem a Lasparaginase (ASNase) como fármaco amplamente utilizado no tratamento dos afetados. A ASNase catalisa a hidrólise do aminoácido L-asparagina (Asn), presente na corrente sanguínea, a ausência do aminoácido no meio extracelular leva à morte células leucêmicas, que necessitam deste aminoácido para as funções celulares. Fatores envolvendo a eficiência do tratamento com ASNase como reações adversas e curta meia-vida, principalmente devido ao reconhecimento pelo sistema imune e degradação por proteases, limitam a sua eficácia. A encapsulação da enzima em lipossomas pode conferir proteção à degradação, melhorar seu perfil farmacocinético e diminuir os efeitos adversos, de forma a melhorar o tratamento da LLA sendo este o objetivo desse trabalho. Lipossomas de DOPC (1,2-dioleoil-sn-glicero-3-fosfocolina) e DMPC (1,2-dimiristoil-snglicero-3-fosfocolina) foram desenvolvidos empregando-se o método de hidratação do filme lipídico e diferentes protocolos de preparo contendo ou não diferentes concentrações de 18:0 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polietilenogicol)-2000] (DSPE-PEG). Os lipossomas produzidos foram utilizados para encapsular a ASNase e os sistemas contendo ou não ASNase encapsulada foram caracterizados por espalhamento de luz dinâmico (DLS), potencial zeta, microscopia eletrônica de transmissão (MET) e criomicroscopia de transmissão. Adicionalmente, foram avaliados a taxa de encapsulação e o perfil de permeabilidade das vesículas à L-asparagina. As análises de DLS mostraram que as nanoestruturas formadas empregando-se agitação magnética a partir de sistemas contendo 10% e 20% de DSPE-PEG possuem diâmetro hidrodinâmico menor (~ 25 nm a 60 nm) que os mesmos sistemas sem o fosfolipídio peguilado (~190 nm a 222 nm), demonstrando a relação entre a diminuição do tamanho e o aumento da quantidade de fosfolipídio peguilado e possível formação de estruturas micelares ou bicelares. O emprego de agitação em vórtex para hidratação do filme lipídico, adição do antioxidante -tocoferol e redução da concentração de DSPE-PEG (5% e 10%) levou à formação de sistemas com diâmetro hidrodinâmico maior, sendo esse protocolo e concentrações de PEG definidos como padrão. As análises de MET comprovaram a formação de lipossomas com diâmetro hidrodinâmico semelhante ao observado por DLS; com a utilização da criomicroscopia foi possível observar os lipossomas sem deformações. Os lipossomas de DMPC/DSPE-PEG 10% apresentaram maior permeabilidade à L-asparagina ao longo do tempo e, portanto, poderiam funcionar como nanoreatores, depletando o aminoácido da circulação. Estudos in vitro com células tumorais devem ser realizados e em seguida estudos in vivo, para confirmar este potencial

L-asparaginase (ASNase) is a first-choice drug, combined with other drugs, in therapeutic schemes to treat Acute Lymphoblastic Leukemia (ALL) in children and adolescents. ASNase catalyzes the hydrolysis of L-asparagine (Asn) in the bloodstream; since ALL cells cannot synthesize this amino acid, protein synthesis is impaired leading to leukemic cells death by apoptosis. In spite of its therapeutic importance, treatment with ASNase is associated to side effects, mainly hypersensitivity and immunogenicity. Another drawback refers to degradation by plasma proteases that altogether with immunogenicity shortens the enzyme half-life. Encapsulation of ASNase in liposomes, vesicular nanostructures formed by the self-aggregation of phospholipids, is an attractive alternative that possibly will protect the enzyme from plasma proteases, resulting on better pharmacokinetics profile. In this work, we prepared by thin film hydration liposomal formulations of the phospholipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) or 1,2-dimyristoyl-sn-glycero-3- phosphocholine (DMPC) containing or not different concentrations of 18:0 1,2-distearoyl-snglycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG), and encapsulated ASNase by electroporation. The systems containing or not ASNase were analyzed by Dynamic Light Scattering, zeta potential and Electron Microscopy. The encapsulation efficiency and vesicles permeability were also evaluated. According to the DLS analysis, the nanostructures formed by film hydration under magnetic stirring employing 10% or 20% DSPE-PEG presented smaller hydrodynamic diameter (~ 25 nm to 60 nm) than the same systems without the pegylated phospholipid (~ 190 nm to 222 nm), demonstrating the relation between size and the amount of pegylated phospholipid that results in formation of micellar or bicellar structures. The protocol was stabilize by hydration of the lipid film under vortex agitation, addition of the antioxidant - tocopherol and reduction of the concentration of DSPE-PEG (5% and 10%), what altogether led to the formation of nanostructures of higher hydrodynamic diameter and monodisperse systems. TEM analyzes confirmed the formation of liposomes with hydrodynamic diameter similar to that observed by DLS; with the use of cryomicroscopy it was possible to observe the liposomes without deformations. Liposomes of DMPC/DSPE-PEG 10% showed permeability to L-asparagine over time and, therefore, could function as nanoreactors, depleting the circulating amino acid

Amplification of urea detection based on pH-sensitive liposomes

BACKGROUND: This study aimed to develop an amplification method of urea detection based on pHsensitive liposomes. RESULTS: The urease covalently immobilized on the magnetic particles and the pH-sensitive liposomes encapsulating ferricyanide were added to the cyclic-voltammeter cell solution where urea was distributed. The conversion of urea into carbonic acid seemed to induce a pH decrease that caused a reduction in the electrostatic repulsion between the headgroups of weakly acidic 1,2-dipalmitoyl-sn-glycero3-succinate. The reduction induced the liposomes to release potassium ferricyanide that was encapsulated inside. The effects of urea concentration and pH value were investigated. A specific concentration (0.5 mg/mL) of the urea solution was set to observe the response. The activity of urease was reversible with respect to the pH change between 7 and 5. The sensitivity of this detection was almost identical to the comparable techniques such as an enzyme-linked immunosorbent assay and a field-effect transistor. CONCLUSIONS: In summary, the methodology developed in this study was feasible as a portable, rapid, and sensitive method.

Preparation and characterization of liposomes loaded with silver nanoparticles obtained by green synthesis

The objective of this work was to develop and characterize liposomes loaded with silver nanoparticles (LAgNPs) to show improvement in stability characteristics. AgNPs were prepared by the green synthesis method with Aloe vera gel extract and exposure to sunlight. Liposomes were prepared by the modified reverse phase method. Particle size, polydispersity index, zeta potential, as well as the scanning electron microscopy (SEM) morphological aspects of AgNPs and LAgNPs were evaluated. In addition, was used flame atomic absorption spectroscopy to determine the amount of AgNP that was encapsulated in liposomes. The AgNPs presented as amorphous and polydisperse structures, with a mean diameter of 278.46 nm and zeta potential of -18.3 mV. LAgNPs had a mean diameter between 321 and 373 nm, the polydispersity index close to 0.2 and a zeta potential around -40 mV, which indicates greater stability to the AgNPs. The images obtained by SEM show semicircular structures for AgNPs and well-defined spherical shape for LAgNPs. The percentage of encapsulation was between 51.81 to 58.83%. These results showed that LAgNPs were obtained with adequate physicochemical characteristics as a release system.

Production of glycosylphosphatidylinositol-anchored proteins for vaccines and directed binding of immunoliposomes to specific cell types

Liposomes are highly useful carriers for delivering drugs or antigens. The association of glycosylphosphatidylinositol (GPI)-anchored proteins to liposomes potentially enhances the immunogenic effect of vaccine antigens by increasing their surface concentration. Furthermore, the introduction of a universal immunoglobulin-binding domain can make liposomes targetable to virtually any desired receptor for which antibodies exist. Methods: We developed a system for the production of recombinant proteins with GPI anchors and histidine tags and Strep-tags for simplified purification from cells. This system was applied to i) the green fluorescent protein (GFP) as a reporter, ii) the promising Plasmodium falciparum vaccine antigen PfRH5 and iii) a doubled immunoglobulin Fc-binding domain termed ZZ from protein A of Staphylococcus aureus. As the GPI-attachment domain, the C-terminus of murine CD14 was used. After the recovery of these three recombinant proteins from Chinese hamster ovary (CHO) cells and association with liposomes, their vaccine potential and ability to target the CD4 receptor on lymphocytes in ex vivo conditions were tested. Results: Upon immunization in mice, the PfRH5-GPI-loaded liposomes generated antibody titers of 103 to 104, and showed a 45% inhibitory effect on in vitro growth at an IgG concentration of 600 µg/mL in P. falciparum cultures. Using GPI-anchored ZZ to couple anti-CD4 antibodies to liposomes, we created immunoliposomes with a binding efficiency of 75% to CD4+ cells in splenocytes and minimal off-target binding. Conclusions: Proteins are very effectively associated with liposomes via a GPI-anchor to form proteoliposome particles and these are useful for a variety of applications including vaccines and antibody-mediated targeting of liposomes. Importantly, the CHO-cell and GPI-tagged produced PfRH5 elicited invasion-blocking antibodies qualitatively comparable to other approaches.(AU)

Comparative analyses of response surface methodology and artificial neural networks on incorporating tetracaine into liposomes

This study evaluated the incorporation of tetracaine into liposomes by RSM (Response Surface Methodology) and ANN (Artificial Neural Networks) based models. RCCD (rotational central composite design) and ANN were performed to optimize the sonication conditions of particles containing 100 % lipid. Laser light scattering was used to perform measure hydrodynamic radius and size distribution of vesicles. The liposomal formulations were analyzed by incorporating the drug into the hydrophilic phase or the lipophilic phase. RCCD and ANN were conducted, having the lipid/cholesterol ratio and concentration of tetracaine as variables investigated and, the encapsulation efficiency and mean diameter of the vesicles as response variables. The optimum sonication condition set at a power of 16 kHz and 3 minutes, resulting in sizes smaller than 800 nm. Maximum encapsulation efficiency (39.7 %) was obtained in the hydrophilic phase to a tetracaine concentration of 8.37 mg/mL and 79.5:20.5% lipid/cholesterol ratio. Liposomes were stable for about 30 days (at 4 ºC), and the drug encapsulation efficiency was higher in the hydrophilic phase. The experimental results of RCCD-RSM and ANN techniques show ANN obtained more refined prediction errors that RCCD-RSM technique, therefore, ANN can be considered as an efficient mathematical method to characterize the incorporation of tetracaine into liposomes.

Encapsulação de antimicrobianos naturais em nanolipossomas para inibição de bactérias causadoras de surtos alimentares / Encapsulation of natural antimicrobials in nanoliposomas for the inhibition of bacterials causing foodborne disease

Avaliou-se ação bactericida e caracterização físico-química de duas diferentes formulações de nanolipossomas preparados utilizando técnica de hidratação do filme lipídico. Nanolipossomas contendo carvacrol apresentaram diâmetro médio de 270,83 nm, PDI de 0,20 e potencial zeta de + 8,64 mV. Nanolipossomas contendo carvacrol e nisina apresentaram diâmetro médio de 205,25 nm, PDI de 0,31 e potencial zeta de - 22,48 mV. Para ambas formulações a concentração bactericida mínima foi de 3,53 mg/mL para Salmonella e 5,3 mg/mL para Escherichia coli e Staphylococcus aureus. Não ocorreu efeito sinérgico entre carvacrol e nisina, porém os nanolipossomas contendo carvacrol apresentaram ação bactericida contra os microrganismos testados, demonstrando potencial para sua utilização no desenvolvimento de um sanitizante para uso em indústrias de alimentos.

Effects of artepillin C on model membranes displaying liquid immiscibility

It has been hypothesized that the therapeutic effects of artepillin C, a natural compound derived from Brazilian green propolis, are likely related to its partition in the lipid bilayer component of biological membranes. To test this hypothesis, we investigated the effects of the major compound of green propolis, artepillin C, on model membranes (small and giant unilamelar vesicles) composed of ternary lipid mixtures containing cholesterol, which display liquid-ordered (lo) and liquid-disordered (ld) phase coexistence. Specifically, we explored potential changes in relevant membrane parameters upon addition of artepillin C presenting both neutral and deprotonated states by means of small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and confocal and multiphoton excitation fluorescence microscopy. Thermotropic analysis obtained from DSC experiments indicated a loss in the lipid cooperativity of lo phase at equilibrium conditions, while at similar conditions spontaneous formation of unilamellar vesicles from SAXS experiments showed that deprotonated artepillin C preferentially located at the surface of the membrane. Time-resolved experiments using fluorescence microscopy showed that at doses above 100 µM, artepillin C in its neutral state interacted with both liquid-ordered and liquid-disordered phases, inducing curvature stress and promoting dehydration at the membrane interface.

In vitro characterization and in vivo performance of mefenamic acid-sodium diethyldithiocarbamate based liposomes

Mefenamic acid (MFA) is a hydrophobic drug with low dissolution rate. This study aimed to develop stable and reproducible aqueous formulations of MFA using liposomes as drug carriers. The drug entrapment, particles size and drug release profiles, and stability and reproducibility of the liposomes were determined. In addition, the maximum tolerated dose (MTD) was determined in rats via the oral and intraperitoneal routes of administration. Also, the anti-inflammatory efficacy of these liposomes was evaluated using carrageenan-induced paw edema model in rats. MFA-DDC based liposomes demonstrated a drug entrapment efficacy of 93.6%, particles size of 170.9 nm, and polydispersity index of 0.24 which were not statistically affected when stored in room and refrigerated temperatures for at least 4 weeks. The MTD of the intraperitoneally administrated MFA-loaded liposomes was 20 mg MFA/kg, whereas for those of oral administrations, it was up to 80 mg MFA/kg. Intraperitoneal dose (80 mg MFA/kg) of MFA-DDC liposomes induced extrapyramidal symptoms associated with significant elevation in serum potassium and muscle enzymes. Moreover, significant inhibition of paw edema was demonstrated by the oral and intraperitoneal routes. These findings suggest that MFA-DDC based liposomes are an effective formulation of MFA and recommend the use of bioequivalence assessments with commercial formulations.

Preparation and evaluation of 2-methoxyestradiol-loaded pH-sensitive liposomes

The development and clinical application of 2-methoxyestradiol (2-ME) as a new type of antitumor drug are limited due to its poor solubility, rapid metabolism in vivo, and large oral dosage. 2-ME-loaded pH-sensitive liposomes (2-ME-PSLs) was prepared containing the lipids, Lipoid E-80 (E-80), cholesteryl hemisuccinate (CHEMS), and cholesterol (CHOL) via thin-film ultrasonic dispersion. First, preparation conditions of 2-ME-PSLs were optimized by orthogonal test. Then 2-ME-PSL was characterized, and the release behavior and stability of 2-ME-PSL in vitro were evaluated. The optimal preparation conditions for 2-ME-PSLs were as follows: 2-ME : E-80+CHEMS 1:15; CHOL : E-80+CHEMS 1:5; ultrasonication time 20 minutes. The mean particle size, PDI, zeta potential, and entrapment efficiency (EE) of 2-ME-PSLs were 116 ± 9 nm, 0.161 ± 0.025, −22.4 ± 1.7 mV, and 98.6 ± 0.5%, respectively. As viewed under a transmission electron microscope, 2-ME-PSLs were well dispersed and almost spherical. They exhibited significant pH-sensitive properties and were fairly stable when diluted with a physiological solution. In conclusion, 2-ME-PSLs were successfully prepared and possessed a favorable pH sensitivity and good dissolution stability with a normal solution

Preparation of Zoledronate liposome and its impact on apoptosis of Kupffer cells in rat liver

Abstract Purpose: To establish a method for the preparation of zoledronate liposome and to observe its effect on inducing the apoptosis of rat liver Kupffer cells. Methods: Zoledronate was encapsulated in liposomes, and then the entrapment rate was detected on a spectrophotometer. The prepared Zoledronate liposome (0.01 mg/mL) was injected into the tail vein of SD rats. Three days later, the number of Kupffer cells (CD68 positive) in rat liver tissue was detected by immunohistochemistry. Flow cytometry was used to detect the apoptosis rate of the isolated liver Kupffer cell cultured in vitro. Results: The entrapment rate of Zoledronate was 43.4±7.8%. Immunohistochemistry revealed that the number of Kupffer cells was 19.3±2.1 in PBS group and 5.5±1.7 in Zoledronate liposome group, with a significant difference (P<0.05). The apoptosis rate of Kupffer cells was 4.1±0.8% in PBS group, while it was 9±2.2% and 23.3±5.9% in Zoledronate liposomes groups with different concentrations of Zoledronate liposome (P<0.05). Conclusions: Zoledronate liposomes can effectively induce the apoptosis of Kupffer cells in vivo and in vitro, and the apoptosis rate is related to the concentration of Zoledronate liposome. To establish a rat liver Kupffer cell apoptosis model can provide a new means for further study on Kupffer cell function.

Ocular delivery of moxifloxacin-loaded liposomes / Perfil de liberação ocular de lipossomas contendo moxifloxacino

ABSTRACT Purpose: To determine the release profile of moxifloxacin encapsulated in liposomes in the aqueous humor as a controlled release system for intracameral application. Methods: Liposomes containing moxifloxacin were obtained using the lipid film hydration method and were characterized by particle size and encapsulation efficiency. Female rabbits were used for the in vivo profile release study. Liposomes containing moxifloxacin was injected into the anterior chamber of the right eye of each animal. The rabbits were divided into five groups, and a sample of aqueous humor was collected 2, 4, 8, 24, and 48 h after administration of liposomes containing moxifloxacin administration. Moxifloxacin concentrations in the aqueous humor were analyzed using high-performance liquid chromatography. Results: The average size of the liposomes containing moxifloxacin was 60.5 ± 0.72 nm with a particle size distribution of 0.307. The encapsulation efficiency of moxifloxacin in liposomes was 92.24 ± 0.24%. The results of an in vivo release study of liposomes containing moxifloxacin, showed that the maximum moxifloxacin concentration was achieved within the first 2 h after administration (5.27 ± 1.09 mg/mL) and was followed by a decrease in intracameral concentration (0.35 ± 0.05 mg/mL) until the 24 h mark. Conclusions: The in vivo experiments resulted in liposomes containing moxifloxacin that were homogenous in size and exhibited high drug encapsulation efficiency. The results indicate that liposomes containing moxifloxacin offers a satisfactory aqueous humor release profile after intracameral application.

RESUMO Objetivo: Determinar o perfil de liberação, no humor aquoso, de moxifloxacino encapsulado em lipossomas como um sistema de liberação controlada para aplicação intracameral. Métodos: Lipossomas contendo moxifloxacino foram obtidos através do método de hidratação do filme lipídico e caracterizados por tamanho da partícula e eficiência de encapsulação. Utilizaram-se coelhos fêmeas foram para o estudo do perfil de liberação in vivo. Lipossomas contendo moxifloxacino foram injetados na câmara anterior do olho direito de cada animal. Os coelhos foram divididos em cinco grupos, e uma amostra de humor aquoso foi coletada 2, 4, 8, 24 e 48 h após a administração de lipossomas contendo moxifloxacino. As concentrações de moxifloxacino no humor aquoso foram analisadas usando cromatografia líquida de alta eficiência. Resultados: O tamanho médio dos lipossomas contendo moxifloxacino foi de 60,5 ± 0,72 nm com uma distribuição de tamanho de partícula de 0,307. A eficiência de encapsulação de moxifloxacino nos lipossomas foi de 92,24 ± 0,24. Os resultados de um estudo de liberação in vivo de lipossomas contendo moxifloxacino, mostraram que a concentração máxima de moxifloxacino foi atingida dentro das primeiras 2 h após sua administração (5,27 ± 1,09 mg/mL) e foi seguida de um decréscimo na concentração intracameral (0,35 ± 0,05 mg/mL) até a marca de 24 h. Conclusão: Os experimentos in vivo resultaram em lipossomas contendo moxifloxacino que eram homogêneos em tamanho e exibiam alta eficiência de encapsulação do fármaco. Os resultados indicam que lipossomas contendo moxifloxacino oferecem um perfil de liberação de humor aquoso satisfatório após a aplicação intracameral.

Interaction study between vancomycin and liposomes containing natural compounds against methicillin-resistant Staphylococcus aureus clinical isolates

ABSTRACT The treatment of infections caused by resistant microorganisms is limited, and vancomycin (VAN) treatment failures for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia are not uncommon, even when MRSA clinical isolates are susceptible to VAN. Thus, this study proposed the association of VAN with usnic acid and ß-lapachone encapsulated into liposomes as a novel therapeutic option for infections caused by MRSA. Liposomes containing ß-lap (ß-lap-lipo) or usnic acid (UA-lipo) were prepared by the thin lipid film hydration method followed by sonication. Antimicrobial activity against MRSA clinical isolates was investigated by the microdilution method according to the Clinical and Laboratory Standards Institute (CLSI). The interaction studies were carried out using the checkerboard method and epsilometer test (Etest). The interaction between VAN and ß-lap or ß-lap-lipo was synergistic (FICI = 0.453 and FICI = 0.358, respectively). An additive interaction between VAN and UA (FICI = 0.515) was found. UA-lipo resulted in synergism with VAN (FICI = 0.276). The Etest reproduced the results obtained by the checkerboard method for approximately 82% of the analysis. Thus, the present study demonstrated that VAN in combination with UA-lipo, ß-lap or ß-lap-lipo synergistically enhanced antibacterial activity against MRSA

Vascular sclerosing effects of bleomycin on cutaneous veins: a pharmacopathologic study on experimental animals

Abstract: Background: Varicose veins and the complications of venous disease are common disorders in humans. Objective: To study the effects of bleomycin as a potential new sclerosing agent and its adverse events in treating varicose veins. Methods: Bleomycin-loaded liposomes 0.1ml was injected in the dorsal ear veins of white New Zealand rabbits. Sodium tetradecyl sulfate was used as a positive control. Normal saline was used as negative control. The blood vessels of the treated ears were photographed before and at one hour and two, eight and 45 days after treatment. Biopsies from the treated areas were obtained for histological examination. Blood samples were collected to determine any possible toxicity. Results: Bleomycin by itself was ineffective; therefore, liposomes were used as a vector to deliver bleomycin to the vein lumen. Subsequently, bleomycin started showing its sclerosing effects. Toxicity monitoring showed no apparent hematologic, pulmonary, hepatic or renal toxicities. This study revealed that bleomycin induced vasculitis, which led to vascular occlusion, which was observed on day 1 and day 8. No bleomycin-related injury was noted by histopathological examination of lung sections. The calculation of the lung/body weight coefficient indicated that edema was present in the experimental groups compared with the negative and positive controls. Study limitations: Relatively small number of experimental animals used. Conclusions: This study showed that bleomycin-loaded liposomes were able to induce vasculitis and vascular occlusion without any toxicity or complications. It might be useful, hence, to treat patients suffering from Varicose veins and other ectatic vascular diseases with this agent.

Liposomes as potential carriers for ketorolac ophthalmic delivery: formulation and stability issues / Liposomes as potential carriers for ketorolac ophthalmic delivery: formulation and stability issues

ABSTRACT Drug delivery to treat ocular disorders locally is a challenging endeavor. Traditional ocular dosage form - eye drops - exhibits poor availability, consequently inefficient therapeutic response. The objective of the study was to formulate and characterize a ketorolac tromethamine ocular system with a prolonged release pattern based on liposomes as a vesicular carrier and to design once daily liquid preparation realizing the thermal in situ gelation principle. Liposomes were prepared by film hydration method. The influence of cholesterol concentration, pH and volume of hydration medium, and type and concentration of charging imparting agents were studied. Liposomes were characterized via, morphological examination, vesicular size, and encapsulation efficiency, and in vitro release performance, moreover its stability was assessed. The results obtained highlighted that liposomes showed a closed vesicular multi-lamellar structure. Ketorolac was successfully encapsulated within the liposomal structure in a cholesterol and charge inducing agent concentration-dependent behaviour. The dispersion of liposomes within thermosensitive Poloxamer in situ gel was able to retard the release of the drug by diffusion providing a controlled prolonged delivery. The liposomal formulations were physically stable for six months. Ketorolac tromethamine in situ liposomal gel representing an efficient alternative in terms of ocular retention and patient compliance when compared with conventional eye drops.

Effects of the encapsulation of usnic acid into liposomes and interactions with antituberculous agents against multidrug-resistant tuberculosis clinical isolates

Mycobacterium tuberculosis (Mtb) has acquired resistance and consequently the antibiotic therapeutic options available against this microorganism are limited. In this scenario, the use of usnic acid (UA), a natural compound, encapsulated into liposomes is proposed as a new approach in multidrug-resistant tuberculosis (MDR-TB) therapy. Thus the aim of this study was to evaluate the effect of the encapsulation of UA into liposomes, as well as its combination with antituberculous agents such as rifampicin (RIF) and isoniazid (INH) against MDR-TB clinical isolates. The in vitro antimycobacterial activity of UA-loaded liposomes (UA-Lipo) against MDR-TB was assessed by the microdilution method. The in vitro interaction of UA with antituberculous agents was carried out using checkerboard method. Minimal inhibitory concentration values were 31.25 and 0.98 µg/mL for UA and UA-Lipo, respectively. The results exhibited a synergistic interaction between RIF and UA [fractional inhibitory concentration index (FICI) = 0.31] or UA-Lipo (FICI = 0.28). Regarding INH, the combination of UA or UA-Lipo revealed no marked effect (FICI = 1.30-2.50). The UA-Lipo may be used as a dosage form to improve the antimycobacterial activity of RIF, a first-line drug for the treatment of infections caused by Mtb.

Antimonial drugs entrapped into phosphatidylserine liposomes: physicochemical evaluation and antileishmanial activity

Abstract: INTRODUCTION: Leishmaniasis is a disease caused by the protozoan Leishmania that resides mainly in mononuclear phagocytic system tissues. Pentavalent antimonials are the main treatment option, although these drugs have toxic side effects and high resistance rates. A potentially alternative and more effective therapeutic strategy is to use liposomes as carriers of the antileishmanial agents. The aims of this study were to develop antimonial drugs entrapped into phosphatidylserine liposomes and to analyze their biological and physicochemical characteristics. METHODS: Liposomes containing meglumine antimoniate (MA) or pentavalent antimony salt (Sb) were obtained through filter extrusion (FEL) and characterized by transmission electron microscopy. Promastigotes of Leishmania infantum were incubated with the drugs and the viability was determined with a tetrazolium dye (MTT assay). The effects of these drugs against intracellular amastigotes were also evaluated by optical microscopy, and mammalian cytotoxicity was determined by an MTT assay. RESULTS: Liposomes had an average diameter of 162nm. MA-FEL showed inhibitory activity against intracellular L. infantum amastigotes, with a 50% inhibitory concentration (IC50) of 0.9μg/mL, whereas that of MA was 60μg/mL. Sb-FEL showed an IC50 value of 0.2μg/mL, whereas that of free Sb was 9μg/mL. MA-FEL and Sb-FEL had strong in vitro activity that was 63-fold and 39-fold more effective than their respective free drugs. MA-FEL tested at a ten-times higher concentration than Sb-FEL did not show cytotoxicity to mammalian cells, resulting in a higher selectivity index. CONCLUSIONS: Antimonial drug-containing liposomes are more effective against Leishmania-infected macrophages than the non-liposomal drugs.

Effects and molecular mechanism of chitosan-coated levodopa nanoliposomes on behavior of dyskinesia rats

BACKGROUND: Chitosan, the N-deacetylated derivative of chitin, is a cationic polyelectrolyte due to the presence of amino groups, one of the few occurring in nature. The use of chitosan in protein and drug delivery systems is being actively researched and reported in the literature RESULTS: In this study, we used chitosan-coated levodopa liposomes to investigate the behavioral character and the expression of phosphorylated extracellular signal-regulated kinase (ERK1/2), dopamine- and cAMP-regulated phos-phoprotein of 32 kDa (DARPP-32) and FosB/AFosB in striatum of rat model of levodopa-induced dyskinesia (LID). We found that scores of abnormal involuntary movement (AIM) decreased significantly in liposome group (P < 0.05), compared with levodopa group. Levels of phospho-ERK1/2, phospho-Thr34 DARPP-32 and FosB/AFosB in striatum decreased significantly in liposome group lesion side compared with levodopa group (P < 0.05). However, both of two groups above have significantly differences compared with the control group (P < 0.05). CONCLUSION: Chitosan-coated levodopa liposomes may be useful in reducing dyskinesias inducing for Parkinson disease. The mechanism might be involved the pathway of signaling molecular phospho-ERK1/2, phospho-Thr34 DARPP-32 and AFosB in striatum