Effect of percutaneous aortic valve position on stress map in ascending aorta: A fluid-structure interaction analysis.

Transcatheter aortic valve implantation (TAVI) is an increasingly widespread procedure. Although this intervention is indicated for high and low surgical risk patients, some issues still remain, such as prosthesis positioning optimization in the aortic annulus. Coaxial positioning of the percutaneous prosthesis influences directly on the aortic wall stress map. The determination of the mechanical stress that acts on the vascular endothelium resulting from blood flow can be considered an important task, since TAVI positioning can lead to unfavorable hemodynamic patterns, resulting in changes in parietal stress, such as those found in post-stenotic dilatation region. This research aims to investigate the influence of the prosthetic valve inclination angle in the mechanical stresses acting in the ascending aortic wall. Aortic compliance and blood flow during cardiac cycle were numerically obtained using fluid structure interaction. The aortic model was developed through segmentation of a computed tomography image of a specific patient submitted to TAVI. When compared to standard position (coaxiality match between the prosthesis and the aortic annulus), the inclination of 4° directed to the left main coronary artery decreased the aortic wall area with high values of wall shear stress and pressure. Coaxial positioning optimization of percutaneous aortic prosthesis may decrease the high mechanical stress area. These changes may be important to reduce the aortic remodeling process, vascular calcification or even the prosthesis half-life. Computational fluid dynamics makes room for personalized medicine, with manufactured prosthesis tailored to each patient.

Isolation of Chamigrene Sesquiterpenes and Absolute Configuration of Isoobtusadiene from the Brittle Star Ophionereis reticulata.

The chemical study of the Brazilian brittle star Ophionereis reticulata led to the isolation of three chamigrene sesquiterpenes, including the partially characterized isoobtusadiene (1), its unreported acetyl derivative (2), and the known (+)-elatol (3). The complete elucidation of the structures 1 and 2 was accomplished by 1D and 2D NMR spectroscopy. The first assignment of the absolute configuration of the isoobtusadiene skeleton is suggested as 6S,9R,10S on the basis of the NMR analysis of the Mosher's ester derivatives of 1 and the ECD study of the acetyl derivative 2. Chamigrenes are typical constituents of Laurencia red algae. O. reticulata is a predator with a preference for algae. Thus, the origin of these metabolites can be likely ascribed to diet.

Dinoflagellate-Related Amphidinolides from the Brazilian Octocoral Stragulum bicolor.

Benthic cnidarians are colonial marine animals that host a rich population of associated and symbiotic microorganisms. In a recent paper we described for the first time the isolation of amphidinolide P (1) from the Brazilian octocoral Stragulum bicolor. Amphidinolides and similar compounds had been previously reported only from dinoflagellates of the genus Amphidinium; thus the presence of 1 in the invertebrate opens intriguing questions on the role and occurrence of these molecules in marine ecosystems. Here we report the identification of four further amphidinolides from the same soft coral, including the known amphidinolide T1 (2) and the new analogues here named amphidinolides C4 (3), B8 (4), and B9 (5). The chemical structures have been elucidated mainly by extensive study of spectroscopic data. Cytotoxic activities of 3 and 4 were evaluated against the colon adenocarcinoma cell line HCT-116.

Amphidinolide P from the Brazilian octocoral Stragulum bicolor

Abstract Dinoflagellates are an important source of unique bioactive secondary metabolites. Symbiotic species, commonly named zooxanthellae, transfer most of their photosynthetically fixed carbon to their host. The mutualistic relationship provides the organic metabolites used for energy production but there are very few reports of the role of the dinoflagellates in the production of secondary metabolites in the symbiotic association. Corals and other related cnidarians are the most well-known animals containing symbiotic dinoflagellates. In the present paper we describe the isolation of amphidinolide P (1) from the octocoral Stragulum bicolor and its prey, the nudibranch Marionia limceana, collected off the coasts of Fortaleza (Ceará, Brazil). The coral extracts also contained 3-O-methyl derivative (2) of amphidinolide P, together with minor compounds still under investigation. Amphidinolides have been so far reported only in laboratory cultures of Amphidinium sp., thus compounds 1 and 2 represents the first identification of these polyketides in invertebrates. The finding proves the possibility to isolate amphidinolides from a natural symbiosis, enabling further biological and biotechnological studies.

N-acetyl cysteine and mushroom Agaricus sylvaticus supplementation decreased parasitaemia and pulmonary oxidative stress in a mice model of malaria.

BACKGROUND: Malaria infection can cause high oxidative stress, which could lead to the development of severe forms of malaria, such as pulmonary malaria. In recent years, the role of reactive oxygen species in the pathogenesis of the disease has been discussed, as well as the potential benefit of antioxidants supplementation. The aim of this study was to investigate the effects of N-acetyl cysteine (NAC) or mushroom Agaricus sylvaticus supplementation on the pulmonary oxidative changes in an experimental model of malaria caused by Plasmodium berghei strain ANKA. METHODS: Swiss male mice were infected with P. berghei and treated with NAC or AS. Samples of lung tissue and whole blood were collected after one, three, five, seven or ten days of infection for the assessment of thiobarbituric acid reactive substances (TBARS), trolox equivalent antioxidant capacity (TEAC), nitrites and nitrates (NN) and to assess the degree of parasitaemia. RESULTS: Although parasitaemia increased progressively with the evolution of the disease in all infected groups, there was a significant decrease from the seventh to the tenth day of infection in both antioxidant-supplemented groups. Results showed significant higher levels of TEAC in both supplemented groups, the highest occurring in the group supplemented with A. sylvaticus. In parallel, TBARS showed similar levels among all groups, while levels of NN were higher in animals supplemented with NAC in relation to the positive control groups and A. sylvaticus, whose levels were similar to the negative control group. CONCLUSION: Oxidative stress arising from plasmodial infection was attenuated by supplementation of both antioxidants, but A. sylvaticus proved to be more effective and has the potential to become an important tool in the adjuvant therapy of malaria.

Oxidative stress in malaria.

Malaria is a significant public health problem in more than 100 countries and causes an estimated 200 million new infections every year. Despite the significant effort to eradicate this dangerous disease, lack of complete knowledge of its physiopathology compromises the success in this enterprise. In this paper we review oxidative stress mechanisms involved in the disease and discuss the potential benefits of antioxidant supplementation as an adjuvant antimalarial strategy.

A theoretical antioxidant pharmacophore for resveratrol.

The structure-activity relationship has been used to study the determination of antioxidant pharmacophore for resveratrol using quantum chemistry calculations by the Functional of Density Theory method. According to the geometry obtained by using a B3LYP/6-31G(*), the HOMO, ionization potential, bond dissociation energies, stabilization energies, and spin density distribution, the electron or hydrogen abstraction in para position is more favored than in meta positions for resveratrol and related derivatives because of the resonance effects. Comparison with structurally related compounds revealed that the antioxidant pharmacophore of resveratrol is 4-hydroxystilbene. Spin distribution showed that the pi-type electron system determines the stability of radicals and the unpaired electrons are mainly distributed to the O-atom in para position, double bond, and B-benzene ring. The antioxidant activity of resveratrol is related to the stabilization energy of 4-hydroxystilbene in resveratrol hydroxylated derivatives. Furthermore, the results explain the activity difference between resveratrol and its hydroxylated derivatives.