Alterations in the Notch4 pathway in cerebral endothelial cells by the HIV aspartyl protease inhibitor,nelfinavir

Background  

Aspartyl protease inhibitors (PIs) used to treat HIV belong to an important group of drugs that influence significantly endothelial cell functioning and angiogenic capacity, although specific mechanisms are poorly understood. Recently, PIs, particularly Nelfinavir, were reported to disrupt Notch signaling in the HIV-related endothelial cell neoplasm, Kaposi's sarcoma. Given the importance of maintaining proper cerebral endothelial cell signaling at the blood brain barrier during HIV infection, we considered potential signaling pathways such as Notch, that may be vulnerable to dysregulation during exposure to PI-based anti-retroviral regimens. Notch processing by γ-secretase results in cleavage of the notch intracellular domain that travels to the nucleus to regulate expression of genes such as vascular endothelial cell growth factor and NFκB that are critical in endothelial cell functioning. Since, the effects of HIV PIs on γ-secretase substrate pathways in cerebral endothelial cell signaling have not been addressed, we sought to determine the effects of HIV PIs on Notch and amyloid precursor protein.     

Hydroxy Groups Enhance [2]Rotaxane Anion Binding Selectivity

We report the synthesis of two [2]rotaxanes containing an interlocked three dimensional binding cavity formed from a pyridinium bis(amide) axle component containing two phenol donors, and an isophthalamide based macrocycle. In the competitive solvent mixture 1 : 1 CDCl₃ : CD₃OD, one of the receptors exhibits a much higher selectivity preference for chloride than an analogous rotaxane without the hydroxy groups. X-ray crystal structures reveal the chloride anion guest encapsulated within the interlocked binding cavity, though not all of the hydrogen bond donors are utilised. Computational semi-empirical simulations indicate that secondary intermolecular interactions occur between the axle hydroxy hydrogen bond donors and the [2]rotaxane macrocycle components, contributing to a more preorganised binding pocket, which may be responsible for the observed enhanced selectivity.     

Colloidal glass transition observed in confinement

We study a colloidal suspension confined between two quasiparallel walls as a model system for glass transitions in confined geometries. The suspension is a mixture of two particle sizes to prevent wall-induced crystallization. We use confocal microscopy to directly observe the motion of colloidal particles. This motion is slower in confinement, thus producing glassy behavior in a sample which is a liquid in an unconfined geometry. For higher volume fraction samples (closer to the glass transition), the onset of confinement effects occurs at larger length scales.     

C-H amination in synthesis: an approach to the assembly of the B/C/D ring system of aconitine

A strategy for the preparation of aconitine is described that attempts to exploit chemoselective C-H amination and the electrophilic reactivity of oxathiazinane N,O-acetals for assembling the complex, polycyclic carbon framework of the natural product.     

Monitoring the formation of self-assembled monolayers of alkanedithiols using a micromechanical cantilever sensor

Using a micromechanical cantilever device, the surface stress induced during the growth of alkanedithiol (HS(CH2)nSH) monolayers on gold in solution is continuously monitored and reported. Adsorption of alkanedithiols of varying chain lengths is observed and compared to each other, as well as to the adsorption of hydroxyalkanethiols (HS(CH2)nOH) and alkanethiols (HS(CH2)nCH3). The results have revealed a significant change in surface stress on the basis of the chain length of the alkanedithiol. The long-chain (n > 10) alkanedithiol adsorption imposes a tensile stress on the gold-coated surface of the cantilever rather than the compressive stress exhibited by both alkanethiols and short-chain dithiols. Our results suggest a phenomenon in which the two thiols of the alkanedithiol adsorb onto the gold surface forming a loop inducing a tensile stress on the cantilever for long chain lengths. This study shows that micromechanical cantilever sensors can be very valuable tools in the exploration and characterization of self-assembled monolayers.     

Density functional theory analysis of molybdenum isotope fractionation

Analytical studies have found an enrichment of the lighter Mo isotopes in oxic marine sediments compared to seawater, with isotope fractionation factors of -1.7 to -2.0 per thousand for Delta97/95Mosediment-seawater. These data place constraints on the possible identities of dissolved and adsorbed species because the equilibrium isotope fractionation depends on the energy differences between the isotopomers of the adsorbed species, minor dissolved species, and the dominant solution species, MoO42-. Adsorption likely involves molybdic acid, whose structure is indicated by previous studies to be MoO3(H2O)3. Here we used DFT calculations of vibrational frequencies to determine the isotope fractionation factors versus MoO42-. The results indicate that isotope equilibration of MoO42- with MoO3(H2O)3, yielding Delta97/95Momolybdic acid-molybdate=-1.33 per thousand, is most likely responsible for the isotope fractionation of Mo between oxic sediments and seawater. The difference between the calculated value of Delta97/95Momolybdic acid-molybdate for MoO3(H2O)3 and the value observed in natural sediments and experiments is probably due to effects of solvation and adsorption onto the manganese oxyhydroxide surface.     

The synthesis,structural characterization and biocidal properties of some triorganotin(IV) esters of N-arylidene-ω-amino acids.

The methods of synthesis, elemental analysis, IR and NMR spectroscopic data and fungicidal activity against Ceratocystis ulmi are reported for a series of triorganotin esters of N-arylidene-ω-amino acids of general formula R₃SnOCO(CH₂)_nN = CHAr (R = Ph, n-Bu; Ar = 2-HOC₆H₄, 2-HOC₁₀H₆; n = 1, 2, 3 and 5). The crystal structures for two of the compounds, tributyltin N-2-hydroxynaphthalidene glycinate ( 1 ) and tributyltin N-2-hydroxynaphthalidene-β-alaninate ( 2 ), have been determined. Although both of these compounds have a trans-R₃SnO₂ structure, in compound 1 the carboxylate group is monodentate and the fifth coordination position around the tin atom is taken up by a coordinated phenolic group, whereas in 2 the carboxylate group is bridging. These two examples thus correspond to the two different structures reported for trans-R₃SnO₂ complexes. Both compounds were found to be active against Ceratocystis ulmi, but there was no significant difference in their levels of biological activity against this particular fungus. Apart from compound 1 , the other tributyltin compounds reported are believed to adopt the carboxylate bridging mode shown by compound ( 2 ). Crystal data: for 1 , crystals monoclinic, space group P 2₁/ c , a = 12.9435(11) Å, b = 13.5769(10) Å, c = 15.7715(12) Å, β = 108.919(6)°, Z = 4, R _f = 0.046 and R _w = 0.058 for 1448 significant reflections; for 2 , crystals monoclinic, space group C 2/ c , a = 24.588(14) Å, b = 9.733(3) Å, c = 27.611(12) Å, β = 113.49(4)°, Z = 8, R _f = 0.053 and R _w = 0.069 for 3822 significant reflections. © 1998 John Wiley & Sons, Ltd.     

Complexation of Anthocyanin-Bound Blackcurrant Pectin and Whey Protein: Effect of pH and Heat Treatment

A complexation study between blackcurrant pectin (BCP) and whey protein (WP) was carried out to investigate the impact of bound anthocyanins on pectin–protein interactions. The effects of pH (3.5 and 4.5), heating (85 °C, 15 min), and heating sequence (mixed-heated or heated-mixed) were studied. The pH influenced the color, turbidity, particle size, and zeta-potential of the mixtures, but its impact was mainly significant when heating was introduced. Heating increased the amount of BCP in the complexes—especially at pH 3.5, where 88% w/w of the initial pectin was found in the sedimented (insoluble) fraction. Based on phase-separation measurements, the mixed-heated system at pH 4.5 displayed greater stability than at pH 3.5. Heating sequence was essential in preventing destabilization of the systems; mixing of components before heating produced a more stable system with small complexes (<300 nm) and relatively low polydispersity. However, heating WP before mixing with BCP prompted protein aggregation—producing large complexes (>400 nm) and worsening the destabilization. Peak shifts and emergence (800–1200 cm⁻¹) in infrared spectra confirmed that BCP and WP functional groups were altered after mixing and heating via electrostatic, hydrophobic, and hydrogen bonding interactions. This study demonstrated that appropriate processing conditions can positively impact anthocyanin-bound pectin–protein interactions.     

Acute Toxicity and Anti-Inflammatory Activity of Trattinnickia rhoifolia Willd (Sucuruba) Using the Zebrafish Model

The species Trattinnickia rhoifolia Willd, (T. rhoifolia), which belongs to the Burseraceae family, is widely used in ethnopharmacological cultural practices by traditional Amazonian people for anti-inflammatory purposes, sometimes as their only therapeutic resource. Although it is used in teas, infusions, macerations and in food, the species is still unexplored in regard to its pharmacophoric potential and chemical profile. Therefore, the aim of this study was to conduct a phytochemical characterization of the hydroethanolic extract of T. rhoifolia leaves (HELTr) and to evaluate the acute toxicity and anti-inflammatory activity of this species using zebrafish (Danio rerio). The extract was analyzed by gas chromatography–mass spectrometry (GC-MS). The evaluation of the acute toxicity of the HELTr in adult zebrafish was determined using the limit test (2000 mg/kg), with behavioral and histopathological evaluations, in addition to the analysis of the anti-inflammatory potential of HELTr in carrageenan-induced abdominal edema, followed by the use of the computational method of molecular docking. The phytochemical profile of the species is chemically diverse, suggesting the presence of the fatty acids, ester, alcohol and benzoic acid classes, including propanoic acid, ethyl ester and hexadecanoic acid. In the studies of zebrafish performed according to the index of histopathological changes (IHC), the HELTr did not demonstrate toxicity in the behavioral and histopathological assessments, since the vital organs remained unchanged. Carrageenan-induced abdominal edema was significantly reduced at all HELTr doses (100, 200 and 500 mg/kg) in relation to the negative control, dimethyl sulfoxide (DMSO), while the 200 mg/kg dose showed significant anti-inflammatory activity in relation to the positive control (indomethacin). With these activities being confirmed by molecular docking studies, they showed a good profile for the inhibition of the enzyme Cyclooxygenase-2 (COX-2), as the interactions established at the sites of the receptors used in the docking study were similar to the controls (RCX, IMN and CEL). Therefore, the HELTr has an acceptable degree of safety for acute toxicity, defined in the analysis of behavioral changes, mortality and histopathology, with a significant anti-inflammatory action in zebrafish at all doses, which demonstrates the high pharmacophoric potential of the species. These results may direct future applications and drug development but still require further elucidation.