Rational design of magnetoliposomes for enhanced interaction with bacterial membrane models.

There is a growing need for alternatives to target and treat bacterial infection. Thus, the present work aims to develop and optimize the production of PEGylated magnetoliposomes (MLPs@PEG), by encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) within fusogenic liposomes. A Box-Behnken design was applied to modulate size distribution variables, using lipid concentration, SPIONs amount and ultrasonication time as independent variables. As a result of the optimization, it was possible to obtain MLPs@PEG with a mean size of 182 nm, with polydispersity index (PDI) of 0.19, and SPIONs encapsulation efficiency (%EE) around 76%. Cytocompatibility assays showed that no toxicity was observed in fibroblasts, for iron concentrations up to 400µg/ml. Also, for safe lipid and iron concentrations, no hemolytic effect was detected. The fusogenicity of the nanosystems was first evaluated through lipid mixing assays, based on Förster resonance energy transfer (FRET), using liposomal membrane models, mimicking bacterial cytoplasmic membrane and eukaryotic plasma membrane. It was shown that the hybrid nanosystems preferentially interact with the bacterial membrane model. Confocal microscopy and fluorescence lifetime measurements, using giant unilamellar vesicles (GUVs), validated these results. Overall, the developed hybrid nanosystem may represent an efficient drug delivery system with improved targetability for bacterial membrane.

Merkel cell carcinoma and the challenge in its approach: a review based on a clinical context of immunosuppression.

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine cancer with high rate to local relapse and metastasis. Its connection to immunosuppression is well known, with reported association to human immunodeficiency virus (HIV). The authors present an 87-year-old woman, infected by HIV type 2 at advanced stage of the disease, whom presented a painless papule on left cheek in 2011. After its total excision, the histopathology confirmed MCC "in situ," with no regional or distant metastases. Simultaneously, she revealed a viral load of 2220 copies/mL and 224 CD4/mm3. Five months later, the patient presented a local and distance relapse with an aggressive behavior and positive regional lymph node. Stage IV disease was confirmed due to presence of liver metastases. Concurrently to the relapse, it was detected low CD4 levels. In our multidisciplinary team decision meeting, it has been decided conservative treatment due to low Karnofsky status, comorbidities, and stage of disease.

A biophysical approach to daunorubicin interaction with model membranes: relevance for the drug's biological activity.

Daunorubicin is extensively used in chemotherapy for diverse types of cancer. Over the years, evidence has suggested that the mechanisms by which daunorubicin causes cytotoxic effects are also associated with interactions at the membrane level. The aim of the present work was to study the interplay between daunorubicin and mimetic membrane models composed of different ratios of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), sphingomyelin (SM) and cholesterol (Chol). Several biophysical parameters were assessed using liposomes as mimetic model membranes. Thereby, the ability of daunorubicin to partition into lipid bilayers, its apparent location within the membrane and its effect on membrane fluidity were investigated. The results showed that daunorubicin has higher affinity for lipid bilayers composed of DMPC, followed by DMPC : SM, DMPC : Chol and lastly by DMPC : SM : Chol. The addition of SM or Chol into DMPC membranes not only increases the complexity of the model membrane but also decreases its fluidity, which, in turn, reduces the amount of anticancer drug that can partition into these mimetic models. Fluorescence quenching studies suggest a broad distribution of the drug across the bilayer thickness, with a preferential location in the phospholipid tails. The gathered data support that daunorubicin permeates all types of membranes to different degrees, interacts with phospholipids through electrostatic and hydrophobic bonds and causes alterations in the biophysical properties of the bilayers, namely in membrane fluidity. In fact, a decrease in membrane fluidity can be observed in the acyl region of the phospholipids. Ultimately, such outcomes can be correlated with daunorubicin's biological action, where membrane structure and lipid composition have an important role. In fact, the results indicate that the intercalation of daunorubicin between the phospholipids can also take place in rigid domains, such as rafts that are known to be involved in different receptor processes, which are important for cellular function.

Influence of doxorubicin on model cell membrane properties: insights from in vitro and in silico studies.

Despite doxorubicin being commonly used in chemotherapy there still remain significant holes in our knowledge regarding its delivery efficacy and an observed resistance mechanism that is postulated to involve the cell membrane. One possible mechanism is the efflux by protein P-gp, which is found predominantly in cholesterol enriched domains. Thereby, a hypothesis for the vulnerability of doxorubicin to efflux through P-gp is its enhanced affinity for the ordered cholesterol rich regions of the plasma membrane. Thus, we have studied doxorubicin's interaction with model membranes in a cholesterol rich, ordered environment and in liquid-disordered cholesterol poor environment. We have combined three separate experimental protocols: UV-Vis spectrophotometry, fluorescence quenching and steady-state anisotropy and computational molecular dynamics modeling. Our results show that the presence of cholesterol induces a change in membrane structure and doesn't impair doxorubicin's membrane partitioning, but reduces drug's influence on membrane fluidity without directly interacting with it. It is thus possible that the resistance mechanism that lowers the efficacy of doxorubicin, results from an increased density in membrane regions where the efflux proteins are present. This work represents a successful approach, combining experimental and computational studies of membrane based systems to unveil the behavior of drugs and candidate drug molecules.

The daunorubicin interplay with mimetic model membranes of cancer cells: A biophysical interpretation.

The present work aimed to study the interactions between the anticancer drug daunorubicin and lipid membrane mimetic models of cancer cells composed by their most representative classes of phospholipids, with different degrees of complexity. Regarding these anticancer drug-membrane interactions, several biophysical parameters were assessed using liposomes (LUVs) composed of different molar ratios of DMPC, DOPC, DPPS, DOPE and Chol. In this context, daunorubicin's membrane concentration was determined by calculating its partition coefficient (Kp) between liposomes and water using derivative UV/vis spectrophotometry at 37°C and pH6.3, a typical tumoral microenvironment. Characterization of the zeta potential of such model membranes, in both the absence and presence of the compound, was accomplished through Electrophoretic Light Scattering (ELS). Fluorescence quenching studies, which determine the location of the drug within the bilayer, were carried out using liposomes labelled with DPH and TMA-DPH, fluorescent probes with known membrane position. Temperature dependent steady-state anisotropy assays were also performed to measure the daunorubicin effect on the membranes' microviscosity. The overall results support that daunorubicin permeation depends on the phospholipid membrane composition and causes alterations in the biophysical properties of the bilayers, namely in the membrane fluidity. The interaction of daunorubicin with the studied phospholipids is mainly driven by electrostatic and hydrophobic interactions. These insights demonstrated that not only membranes can affect daunorubicin accumulation in cells but the compound can alter the properties of membranes. The changes produced by daunorubicin on the lipid structure may constitute an additional mechanism of action, which might lead to modifications in the location and, consequently, the activity of membrane signaling proteins.

Nasolabial flap - alternative uses for a classic but versatile technique.

The nasolabial flap is one of the most ancient techniques used in orofacial surgery. The authors report two cases of patients with skin cancer treated surgically with variations of the classic nasolabial flap by transposition (bilateral and folded) that highlight the broad applicability of this technique.

Primary vulvar Paget disease - the importance of clinical suspicion.

Extramammary Paget disease of the vulva is a rare condition that accounts for only 1-2% of vulvar malignancies and represents a frequent cause of misdiagnosis. It is most commonly seen in postmenopausal women. Clinically it is similar to Paget disease of the breast, appearing as red, well-demarcated eczematoid lesions, with slightly raised edges. A high degree of clinical suspicion is very important when evaluating these lesions in order to avoid misdiagnosis and delay of effective treatment. We present a case of vulvar Paget disease treated with vulvectomy.

Syndrome in question.

Neurofibromatosis is extremely variable in its presentation. Segmental neurofibromatosis (SNF), which corresponds to NF-type 5 in the Riccardi classification, is a rare disorder. It may go unrecognized if few lesions are observed. We present a case of segmental neurofibromatosis in a 28 year-old patient who presented with multiple papules and nodules distributed in dermatomal fashion on the trunk. The histopathological examination of the lesions revealed a non-encapsulated, well-circumscribed spindle cell neoplasm, which was consistent with neurofibromas.

Syndrome in question

Abstract Neurofibromatosis is extremely variable in its presentation. Segmental neurofibromatosis (SNF), which corresponds to NF-type 5 in the Riccardi classification, is a rare disorder. It may go unrecognized if few lesions are observed. We present a case of segmental neurofibromatosis in a 28 year-old patient who presented with multiple papules and nodules distributed in dermatomal fashion on the trunk. The histopathological examination of the lesions revealed a non-encapsulated, well-circumscribed spindle cell neoplasm, which was consistent with neurofibromas.

Efeito da demonstração distribuída na aprendizagem do saque do voleibol / The effect of distributed demonstrations in the volleyball serve learning

O presente estudo investigou o efeito da distribuição das demonstrações na aprendizagem do saque japonês do voleibol. Dezoito sujeitos foram distribuídos em três grupos: G1 (oito demonstrações anteriores à prática), G2 (quatro demonstrações anteriores e quatro na 40º tentativa) e G4 (duas anteriores, duas na 20º, 2 na 40º, duas na 60º tentativas). A execução de uma pessoa habilidosa na tarefa foi filmada e utilizada como forma de demonstração para todos os grupos. O experimento consistiu de pré-teste com 10 tentativas, fase de aquisição com 80 tentativas e teste de retenção após 24 horas com 10 tentativas. Os resultados mostraram que as demonstrações anteriores à sessão de prática levaram a melhoras no escore e a demonstração distribuída levou a melhoras no padrão de movimento

The present study investigated the effect of the distribution of the demonstration on the learning of the Japanese volleyball serve. Eighteen subjects were divided into 3 groups: G1 (8 demonstrations prior the practice), G2 (4 prior and 4 on 40th trial) and G4 (2 prior, 2 on 20th, 2 on 40th and 2 on 60th trial). The execution of a skilled person in the task was recorded and adopted as a demonstration to all groups. The experiment had pretest with 10 trials, acquisition phase with 80 trials and the retention test after 24 hours, with 10 trials. The results showed that demonstrations prior to the practice sessions conducted to score improvement and the distributed demonstration conducted to improvement in motor pattern

Efeitos do estabelecimento de metas para a aquisição de uma habilidade motora / Effects of goal setting for the acquisition of motor skills / Efectos de la fijación de metas para la adquisición de habilidades motoras

O presente estudo investigou os efeitos do estabelecimento de metas de curto e de longo prazo na aprendizagem do arremesso de dardo de salão. O experimento foi conduzido em três etapas: pré-teste (10 tentativas); aquisição (60 tentativas), com manipulação da temporalidade da meta; e pós-teste (10 tentativas). Os 33 universitários destros foram divididos em três grupos: meta específica de curto prazo (GEC), meta específica de longo prazo (GEL) e o não meta (GNM). Na análise da precisão e da consistência, a ANOVA two way identificou diferença entre pré-teste e pós-teste e entre os blocos da aquisição. Apesar de todos os grupos terem aprendido a tarefa, não houve diferença entre eles. Sugere-se a realização de novos estudos sobre o tema.

The present study investigated the effects of short and long-term goal setting in the learning of saloon dart throwing. The experiment was conducted in three stages: pretest (10 trials), acquisition (60 trials), with manipulation of the temporality of the goal, and post-test (10 trials). The 33 right-handed university students were divided into three groups: specific short-term goal (GEC), specific long-term goal (GEL) and no-goal (GNM). In the analysis of accuracy and consistency the two way ANOVA identified significant effect between pretest and post-test and between acquisition blocks as well. Although all the groups have learned the task, there was no difference between them. It is suggested further researches on the subject.

El presente estudio investigó los efectos de la meta a corto y largo plazo de puesta enel aprendizaje del salón de lanzar dardos. El experimento se llevó a cabo en tres etapas: pre-test (10 ensayos), la adquisición (60 ensayos), con la manipulación de la temporalidad de la meta, y después de la prueba (10 ensayos). Los 33 estudiantes universitarios de la mano derecha se dividieron en tres grupos: objetivo concreto a corto plazo (GEC), el objetivo específico a largo plazo (GEL) y no se meta (GNM). En el análisis de la exactitud y la consistencia de dos vías ANOVA identificó un efecto significativo entre la pre y post-test y entre bloques de adquisición así. A pesar de todos los grupos han aprendido la tarea, no hubo diferencias entre ellos.