Fusion of Tumor-Derived Exosomes with Long-Circulating and pH-Sensitive Liposomes Loaded with Doxorubicin for the Treatment of Breast Cancer.

Doxorubicin (DOX) is a chemotherapeutic agent that has been used in the treatment of breast cancer. However, serious toxic effects have limited its use, mainly cardiotoxicity. To minimize the adverse effects, liposomal preparations containing DOX have been developed. These preparations can reach the target in the tumor region as well as bypass the resistance-related problems. An alternative to increased therapeutic efficacy may be the fusion of liposomes with exosomes released from tumor cells to facilitate membrane and fusion interactions, achieving greater cell uptake. Thus, the purpose of this study was the fusion of exosomes derived from breast tumor cells with long-circulating and pH-sensitive liposomes loading DOX (ExoSpHL-DOX) for the treatment of breast cancer. The mean diameter of ExoSpHL-DOX was 100.8 ± 7.8 nm, the polydispersity index was 0.122 ± 0.004, and the encapsulated DOX content was equal to 83.5 ± 2.5%. The fusion of exosomes with long-circulating and pH-sensitive liposomes was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, and nano-flow cytometry. The physicochemical characteristics of ExoSpHL-DOX were maintained for 60 days, at 4 °C. The study of the release of DOX from ExoSpHL-DOX in dilution media with different pH values showed the pH sensitivity characteristic of the nanosystem, since 96.6 ± 0.2% of DOX was released from ExoSpHL-DOX at pH 5.0, while at pH 7.4, the release was 70.1 ± 1.7% in the medium. The cytotoxic study against the breast cancer cell line demonstrated that ExoSpHL-DOX treatment significantly reduced the cancer cell viability.

Phenylephrine increases near-infrared spectroscopy determined muscle oxygenation in men.

Phenylephrine increases mean arterial pressure (MAP) by enhanced total peripheral resistance (TPR) but near-infrared spectroscopy (NIRS) determined muscle oxygenation (SmO2) increases. We addressed that apparent paradox during supine rest and head-up tilt (HUT). Variables were determined ± phenylephrine in males during supine rest (n = 17) and 40° HUT (n = 7). MAP, stroke volume (SV), heart rate (HR), and TPR were derived by Modelflow® and NIRS determined biceps SmO2 and (tibial) bone oxygenation (StibialO2). For ten subjects, cardiac filling and the diameter of the inferior caval vein (ICV collapsibility index: ((ICVexpiration - ICVinspiration)/ICVexpiration) × 100) were assessed by ultrasound. Pancreatic polypeptide (PP) and atrial natriuretic peptide (proANP) in plasma were determined by immunoassay. Brachial artery blood flow was assessed by ultrasound and skin oxygenation (SskinO2) monitored by white light spectroscopy. Phenylephrine increased MAP by 34% and TPR (62%; P < 0.001) during supine rest. The ICV collapsibility index decreased (24%; P < 0.001) indicating augmented cardiac preload although volume of the left atrium and ventricle did not change. SV increased (18%; P < 0.001) as HR decreased (24%; P < 0.001). ProANP increased by 9% (P = 0.002) with unaffected PP. Brachial artery blood flow tended to decrease while SskinO2 together with StibialO2 decreased by 11% (P = 0.026) and 20% (P < 0.001), respectively. Conversely, phenylephrine increased SmO2 (9%) and restored the HUT elicited decrease in SmO2 (by 19%) along with SV (P = 0.02). Phenylephrine reduces skin and bone oxygenation and tends to reduce arm blood flow, suggesting that the increase in SmO2 reflects veno-constriction with consequent centralization of the blood volume.

Remote ischemic preconditioning delays fatigue development during handgrip exercise.

Ischemic preconditioning (IPC) of one or two limbs improves performance of exercise that recruits the same limb(s). However, it is unclear whether IPC application to another limb than that in exercise is also effective and which mechanisms are involved. We investigated the effect of remote IPC (RIPC) on muscle fatigue, time to task failure, forearm hemodynamics, and deoxygenation during handgrip exercise. Thirteen men underwent RIPC in the lower limbs or a control intervention (CON), in random order, and then performed a constant load rhythmic handgrip protocol until task failure. Rates of contraction and relaxation (ΔForce/ΔTime) were used as indices of fatigue. Brachial artery blood flow and conductance, besides forearm microvascular deoxygenation, were assessed during exercise. RIPC attenuated the slowing of contraction and relaxation throughout exercise (P < 0.05 vs CON) and increased time to task failure by 11.2% (95% confidence interval: 0.7-21.7%, P <0.05 vs CON). There was no significant difference in blood flow, conductance, and deoxygenation between conditions throughout exercise (P > 0.05). In conclusion, RIPC applied to the lower limbs delayed the development of fatigue during handgrip exercise, prolonged time to task failure, but was not accompanied by changes in forearm hemodynamics and deoxygenation.

Genetic characterization of natural populations of the medicinal plant Palicourea coriacea (Rubiaceae) with molecular markers.

Palicourea coriacea (Rubiaceae) is a herbaceous, perennial species typical of the Cerrado; it is popularly known as "douradinha", because of its yellow flowers. It is utilized in popular medicine, mainly for the treatment of renal diseases. We used RAPD markers to evaluate the genetic structure of nine natural populations of P. coriacea, totaling 168 individuals, collected in the States of Goiás and Bahia. This species showed a high level of genetic diversity, with He values varying between 0.259 and 0.338, with an overall mean of 0.296. Analysis by AMOVA revealed that 23% of the total variability was between populations and 77% was within populations. The estimate of apparent gene flow (Nm) was 0.83. Analyses of the fixation index (f ) using a Bayesian approach yielded a mean value of 0.98, suggesting that this is an autogamous species. Analyses of genetic divergence and spatial pattern of the populations utilizing theta(B) and Phi(ST) matrices, pair to pair, revealed no correlation between geographic distance and genetic distance; the nine populations grouped randomly, without relation to their geographic origin. The hypothesis that geographically close populations should be genetically close was discarded based on the Mantel test; the correlation was 0.155 (P = 0.23). The degree of interpopulational differentiation was relatively high, which allows us to recommend a strategy of sampling for the ex situ conservation of genetic variability, utilizing a larger number of populations. For in situ conservation, we suggest preservation of a larger number of areas in the Cerrado, where this species naturally occurs.

Double membrane based on lidocaine-coated polymyxin-alginate nanoparticles for wound healing: In vitro characterization and in vivo tissue repair.

The aim of this study was to develop and characterize a double layer biomembrane for dual drug delivery to be used for the treatment of wounds. The membrane was composed of chitosan, hydroxypropyl methylcellulose and lidocaine chloride (anesthetic drug) in the first layer, and of sodium alginate-polymyxin B sulphate (antibiotic) nanoparticles as the second layer. A product with excellent thickness (0.01-0.02 mm), adequate mechanical properties with respect to elasticity, stiffness, tension, and compatible pH for lesion application has been successfully obtained. The incorporation of the drugs was confirmed analysing the membrane cross-sections by scanning electron microscopy. A strong interaction between the drugs and the functional groups of respective polymers was confirmed by Fourier-Transform Infrared Spectroscopy, thermal analysis and X-ray diffraction. Microbiological assays showed a high antimicrobial activity when polymyxin B was present to act against the Staphylococcus aureus and Pseudomonas aeruginosa strains. Low cytotoxicity observed in a cell viability colorimetric assay and SEM analysis suggest biocompatibility between the developed biomembrane and the cell culture. The in vivo assay allowed visualizing the healing potential by calculating the wound retraction index and by histological analysis. Our results confirm the effectiveness of the developed innovative biomaterial for tissue repair and regeneration in an animal model.

Visceral leishmaniasis in a Brazilian child infected perinatally with human immunodeficiency virus.

This report describes a Brazilian child perinatally infected by HIV who presented visceral leishmaniasis. She showed the classic clinical features, and diagnosis was made by demonstration of amastigote forms of Leishmania in bone marrow aspirate. She responded well to traditional treatment with meglubine.

CD25+ CD4+ T cells regulate the expansion of peripheral CD4 T cells through the production of IL-10.

The mechanisms by which the immune system achieves constant T cell numbers throughout life, thereby controlling autoaggressive cell expansions, are to date not completely understood. Here, we show that the CD25(+) subpopulation of naturally activated (CD45RB(low)) CD4 T cells, but not CD25(-) CD45RB(low) CD4 T cells, inhibits the accumulation of cotransferred CD45RB(high) CD4 T cells in lymphocyte-deficient mice. However, both CD25(+) and CD25(-) CD45RB(low) CD4 T cell subpopulations contain regulatory cells, since they can prevent naive CD4 T cell-induced wasting disease. In the absence of a correlation between disease and the number of recovered CD4(+) cells, we conclude that expansion control and disease prevention are largely independent processes. CD25(+) CD45RB(low) CD4 T cells from IL-10-deficient mice do not protect from disease. They accumulate to a higher cell number and cannot prevent the expansion of CD45RB(high) CD4 T cells upon transfer compared with their wild-type counterparts. Although CD25(+) CD45RB(low) CD4 T cells are capable of expanding when transferred in vivo, they reach a homeostatic equilibrium at lower cell numbers than CD25(-) CD45RB(low) or CD45RB(high) CD4 T cells. We conclude that CD25(+) CD45RB(low) CD4 T cells from nonmanipulated mice control the number of peripheral CD4 T cells through a mechanism involving the production of IL-10 by regulatory T cells.

Flora bacteriana heterotrófica em ostras (Crassostrea rhizophorae) e águas da Baía Norte, Ilha de Santa Catarina, Brasil / Heterotrophic bacteria in oysters and waters of North Bay, Santa Catarina, Brazil

A população bacteriana das águas da Baía Norte da Ilha de Santa Catarina foi estudada utilizando-se a ostra Crassostrea rhizophorae como biondicador. Foram realizadas avaliações quali-quantitativas de bactérias heterotróphicas originárias da água do mar e de ostras de três locais da Baía. Nas ostras, analisou-se a massa digestiva e o corpo inteiro do animal. Os resultados mostram altas concentrações de bactérias na água e nos bivalves. A maior acumulação de microrganismos foi detectada no trato digestivo das ostras. Enterobactérias predominam na água enquanto as Pseudomonadaceae são mais frequentes nos bivalves.