The endothelium is the production site of several potent vasoactive factors that contribute to the modulation of the vascular tone. Because hemoglobin-based oxygen carriers (HBOC) have been demonstrated to cause vasoconstriction and thereby increase arterial pressure by interacting with endothelium-derived factors such as nitric oxide and endothelin-1, we hypothesized that hemoglobin could penetrate into the endothelial cells. Therefore, we investigated the presence of hemoglobin into guinea pig aortic endothelial cells by immunohistochemical staining after exchange transfusion with a hemoglobin-based oxygen carrier. Despite the large molecular size of HBOC due to chemical modifications designed to prevent hemoglobin subunit dissociation and extravascular leakage, hemoglobin was detectable by immunohistochemical staining into the endothelial cells. These findings suggest that the vascular endothelial cells could uptake hemoglobin by endocytosis mechanisms or could help hemoglobin to cross the endothelial barrier toward media by transcytosis mechanisms. These findings are very important to lead future investigations to the mechanisms by which HBOC cause vasoconstriction.

Despite the promising biological and antioxidant properties of curcumin, its medical applications are limited due to poor solubility in water and low bioavailability. Polymeric nanoparticles (NPs) adapted to oral delivery may overcome these drawbacks. Properties such as particle size, zeta potential, morphology and encapsulation efficiency were assessed. Then, the possibility of storing these NPs in a solid-state form obtained by freeze-drying, in vitro curcumin dissolution and cytocompatibility towards intestinal cells were evaluated. Curcumin-loaded Eudragit® RLPO (ERL) NPs showed smaller particle diameters (245 ± 2 nm) and better redispersibility after freeze-drying than either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) NPs. The former NPs showed lower curcumin encapsulation efficiency (62%) than either PLGA or PCL NPs (90% and 99%, respectively). Nevertheless, ERL NPs showed rapid curcumin release with 91 ± 5% released over 1 h. The three curcumin-loaded NPs proposed in this work were also compatible with intestinal cells. Overall, ERL NPs are the most promising vehicles for increasing the oral bioavailability of curcumin.

No abstract

Melarsoprol, a water-insoluble drug, is mainly used in the treatment of trypanosomiasis and has demonstrated an in vitro activity on myeloid and lymphoid leukemia derived cell lines. It is marketed as a very poorly tolerated non-aqueous solution (Arsobal). The aim of our work was to develop melarsoprol-cyclodextrin complexes in order to improve the tolerability and the bioavailability of melarsoprol. Phase-solubility analysis showed A(L)-type diagrams with beta-cyclodextrin (betaCD), randomly methylated beta-cyclodextrin (RAMEbetaCD) and hydroxypropyl-beta-cyclodextrin (HPbetaCD), which suggested the formation of 1:1 inclusion complexes. The solubility enhancement factor of melarsoprol (solubility in 250 mM of cyclodextrin/solubility in water) was about 7.2x10(3) with both beta-cyclodextrin derivatives. The 1:1 stoichiometry was confirmed in the aqueous solutions by the UV spectrophotometer using Job's plot method. The apparent stability constants K(1:1), calculated from mole-ratio titration plots, were 57 143+/-4 425M(-1) for RAMEbetaCD and 50 761+/-5 070 M(-1) for HPbetaCD. Data from 1H-NMR and ROESY experiments provided a clear evidence of inclusion complexation of melarsoprol with its dithiaarsane extremity inserted into the wide rim of the cyclodextrin torus. Moreover, RAMEbetaCD had a pronounced effect on the drug hydrolysis and the dissolution rate of melarsoprol. However, the cytotoxic properties of melarsoprol on K562 and U937 human leukemia cell lines was not modified by complexation.

No abstract

Among S-nitrosothiols showing reversible binding between NO and -SH group, S-nitrosoglutathione (GSNO) represents potential therapeutics to treat cardiovascular diseases (CVD) associated with reduced nitric oxide (NO) availability. It also induces S-nitrosation of proteins, responsible for the main endogenous storage form of NO. Although oxidative stress parallels CVD development, little is known on the ability of GSNO to restore NO supply and storage in vascular tissues under oxidative stress conditions. Aortic rat smooth muscle cells (SMC) were stressed in vitro with a free radical generator (2,2'-azobis(2-amidinopropane) dihydrochloride, AAPH). The cellular thiol redox status was reflected through levels of reduced glutathione and protein sulfhydryl (SH) groups. The ability of GSNO to deliver NO to SMC and to induce protein S-nitrosation (investigated via mass spectrometry, MS), as well as the implication of two redox enzymes involved in GSNO metabolism (activity of gamma-glutamyltransferase, GGT, and expression of protein disulfide isomerase, PDI) were evaluated. Oxidative stress decreased both intracellular glutathione and protein -SH groups (53% and 32% respectively) and caused a 3.5-fold decrease of GGT activity, while PDI expression at the plasma membrane was 1.7-fold increased without any effect on extracellular GSNO catabolism. Addition of GSNO (50 μM) increased protein -SH groups and protein S-nitrosation (50%). Mass spectrometry analysis revealed a higher number of S-nitrosated proteins under oxidative stress (83 proteins, vs 68 in basal conditions) including a higher number of cytoskeletal proteins (15, vs 9 in basal conditions) related with cell contraction, morphogenesis and movement. Furthermore, proteins belonging to additional protein classes (cell adhesion, transfer/carrier, and transporter proteins) were S-nitrosated under oxidative stress. In conclusion, higher levels of GSNO-dependent S-nitrosation of proteins from the cytoskeleton and the contractile machinery were identified under oxidative stress conditions. The findings may prompt the identification of suitable biomarkers for the appraisal of GSNO bioactivity in the CVD treatment.

No abstract

In this model of anaphylactic shock, early treatment with epinephrine followed by continuous epinephrine or vasopressin infusion resulted in an excellent survival rate, whereas vasopressin only resulted in a 100% death rate. These experimental results suggest that epinephrine must still be considered as the first-line drug to treat anaphylactic shock.