Adaptive Remodeling in the Elastase-induced Rabbit Aneurysms.

BACKGROUND: Rupture of brain aneurysms is associated with high fatality and morbidity rates. Through remodeling of the collagen matrix, many aneurysms can remain unruptured for decades, despite an enlarging and evolving geometry. OBJECTIVE: Our objective was to explore this adaptive remodeling for the first time in an elastase induced aneurysm model in rabbits. METHODS: Saccular aneurysms were created in 22 New Zealand white rabbits and remodeling was assessed in tissue harvested 2, 4, 8 and 12 weeks after creation. RESULTS: The intramural principal stress ratio doubled after aneurysm creation due to increased longitudinal loads, triggering a remodeling response. A distinct wall layer with multi-directional collagen fibers developed between the media and adventitia as early as 2 weeks, and in all cases by 4 weeks with an average thickness of 50.6 ± 14.3 µm. Collagen fibers in this layer were multi-directional (AI = 0.56 ± 0.15) with low tortuosity (1.08 ± 0.02) compared with adjacent circumferentially aligned medial fibers (AI = 0.78 ± 0.12) and highly tortuous adventitial fibers (1.22 ± 0.03). A second phase of remodeling replaced circumferentially aligned fibers in the inner media with longitudinal fibers. A structurally motivated constitutive model with both remodeling modes was introduced along with methodology for determining material parameters from mechanical testing and multiphoton imaging. CONCLUSIONS: A new mechanism was identified by which aneurysm walls can rapidly adapt to changes in load, ensuring the structural integrity of the aneurysm until a slower process of medial reorganization occurs. The rabbit model can be used to evaluate therapies to increase aneurysm wall stability.

Facile Synthesis and In Vitro Biological Screening of Pd@SiO2 Core-Shell Nanoparticles.

In this study, semiconductor core-shell Pd@SiO2 nanoparticles (NPs) were prepared by Stober's method. The prepared final products were characterized by XRD, FT-IR, SEM, HR-TEM and EDX techniques. Cell viability of Pd@SiO2 NPs against HeLa cell line was screened by MTT assay. The present study indicates that the core-shell Pd@SiO2 NPs are extremely stable along with very high photodynamic efficiency under LED light illumination. The antibacterial activities of core- shell Pd@SiO2 NPs were determined with Escherichia coli and Staphylococcus aureus by agar diffusion method. DNA binding affinity of the core-shell Pd@SiO2 NPs towards CT-DNA was also investigated. The observed results showed that SiO2 supported on the surface of Pd NPs not only prevented aggregation, but also proved the enhanced antimicrobial and DNA binding propensities than the free Pd NPs.

Simple Combustion Synthesis, Structural, Morphological, Optical and Catalytic Properties of ZnO Nanoparticles.

In this present study, semiconductor zinc oxide (ZnO) nanoparticles were successfully prepared by microwave irradiation (ZnO-MIM) and conventional combustion (ZnO-CCM) method, respectively using Aloe vera plant extract as reducing agent. Crystal structure, purity and surface morphology of the samples were examined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectral studies was used to analysis the optical property and band gap energy of the samples. The antibacterial activities of ZnO nanostructures (ZnO-MIM and ZnO-CCM) were tested against both gram positive (Bacillus subtilis, Staphylococcus aureus) and gram negative bacteria (Proteus mirabilis, Salmonella typhi) by modified disc diffusion method and observed enhanced activity against P. mirabilis and S. typhi. ZnO nanostructures (ZnO-MIM and ZnO-CCM) were used as the photo-catalysts for the degradation of methylene blue (MB) dye and observed enhanced efficiency of degradation of MB than that of their same bulk materials. Moreover, the synthesis method is easy with low cost and time consumable and also high yield purity products.

Enhanced Antibacterial Activity and Photo-Catalytic Properties of ZnO Nanoparticles: Pedalium Murex Plant Extract-Assisted Synthesis.

Semiconductor ZnO samples with two different morphologies such as nanoparticles (ZnO-NPs) and nano-sheets (ZnO-NSs) was successfully prepared by microwave heating (MHM) and modified sol-gel (SGM) method, respectively using Pedalium Murex plant extract as the bio-reducing agent. Structural, purity and morphology of the samples was examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. Optical property analysis and band gap calculation were carried out by UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy techniques. Kubelka-Munk method was used to measure band band gap of the samples and it shows 3.42 eV and 3.23 eV for ZnO-NPs and ZnO-NSs, respectively. The antibacterial activities of ZnO-NPs and ZnO-NSs against both gram positive (Bacillus subtilis, Staphylococcus aureus) as well as gram negative bacteria (Proteus mirabilis, Salmonella typhi) were tested by modified disc diffusion method and showed important antibacterial activity against P. mirabilis and S. typhi. The photocatalytic activity of ZnO nano-catalysts (ZnO-NPs and ZnO-NSs) for the degradation of methylene blue (MB) dye was studied under solar lighting and the results showed that the samples ZnO-NPs with smaller particle size considerable degradation of MB than ZnO-NSs.

Okra (Abelmoschus esculentus) Plant Extract-Assisted Combustion Synthesis and Characterization Studies of Spinel ZnAl2O4 Nano-Catalysts.

Spinel ZnAl2O4 nano-catalysts were synthesized by a simple, economical and eco-friendly microwave irradiation (MIM) and conventional heating methods (CHM), using metal nitrates and Okra (Abelmoschus esculentus) plant extract, which play a dual role of both oxidizing and reducing nature. Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray (EDX) and selected area electron diffraction (SAED) pattern results were confirmed that the samples have a single-phase cubic spinel structure with high crystalline nature of ZnAl2O4. Surface morphology of the samples was revealed by high resolution scanning electron microscopy (HR-SEM) and high resolution transmission electron microscopy (HR-TEM) techniques and they are confirmed particle-like structure with grain size below 50 nm. The optical band gap (Eg) was measured using Kubelka-Munk model by UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) and the Eg value is higher for MIM product than CHM, due to the smaller particle size of ZnAl2O4-MIM. The magnetic property of the samples was determined by vibrating sample magnetometer (VSM) and showed a superparamagnetic behavior. Spinel ZnAl2O4 nano-catalysts are magnetically recyclable and could be reused with no significant loss in catalytic activity. Both the samples were successfully tested as catalysts for the conversion of alcohols into respective carbonyl compounds using H2O2 (as oxidant) and acetonitrile (as a solvent) system. It was found that the ZnAl2O4-MIM nanocatalysts show best performance of conversion of alcohols into a carbonyl compounds than that of ZnAl2O4-CHM, due to the smaller particle size and higher surface area of ZnAl2O4-MIM samples.

Aloe vera Plant Extracted Green Synthesis, Structural and Opto-Magnetic Characterizations of Spinel Co(x)Zn1₋xAl2O4Nano-Catalysts.

Spinel Co(x)Zn1₋xAl2O4 (0 ≤ x ≤ 1) nano-catalysts were synthesized by a simple Aloe vera plant extracted green synthesis route. Powder XRD patterns and Rietveld analysis confirmed the formation of single phase, cubic spinel gahnite structure without other impurities. The lattice parameter increased from 8.089 to 8.125 A with increasing CO²âº content. The average crystallite sizes were estimated using Scherrer's method, and it was found to be in the range of 15.72 nm to 26.53 nm. FT-IR spectra showed vibrational stretching frequencies corresponding to the spinel structure. HR-SEM and HR-TEM images showed the features of well particle shaped crystals with nano-sized grains. The elemental compositions of Co, Zn, Al and O were quantitatively obtained from EDX analysis. The band gap energy estimated using Kubelka-Munk method by UV-Visible DRS method, and the values are decreased with increasing the Co²âº content (4.12 eV to 3.67 eV), due to the formation of sub bands in between the energy gap. PL spectra showed emission bands in UV as well as in the visible regions for ZnAl2O4 and Co-doped ZnAl2O4, due to the defect centers acting as the trap levels. VSM measurements revealed that pure ZnAl2O4 has diamagnetic, while Co doped ZnAl2O4 samples (x = 0.2 to 0.8) have superparamagnetism, whereas the sample CoAl2O4 has ferromagnetic in nature. Catalytic oxidation of benzyl alcohol to benzaldehyde was found that the sample Co0.6Zn0.4Al2O4 showed 93.25% conversion with 99.56% selectivity, whereas for pure ZnAl2O4, the conversion was only 86.31% with 92.85% selectivity.

Sesamum indicum Plant Extracted Microwave Combustion Synthesis and Opto-Magnetic Properties of Spinel MnxCo1₋xAl2O4Nano-Catalysts.

Spine Mn(x)Co1₋xAl2O4 (x = 0, 0.3 and 0.5) nanoparticles were synthesized using Sesamum indicum (S. indicum) plant extracted microwave-assisted combustion method. S. indicum plant extract simplifies the process, provides an alternative process for a simple, economical and environment friendly synthesis. The absence of surfactant/catalysts has led to a simple, cheap and fast method of synthesis of spinel nanoparticles. The as-synthesized spinel nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), Brunauer Emmett Teller (BET) surface area analysis, UV-Visible diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectroscopy, and vibrating sample magnetometer. The formation of spinel nanoparticles was confirmed by HR-SEM and HR-TEM and their possible formation mechanisms were also proposed. Powder XRD, FT-IR, SAED and EDX results confirmed the formation of pure and single cubic phase CoAl2O4 with well-defined crystalline. The optical property was determined by DRS and PL spectra. VSM measurements revealed that pure and Mn-doped CoAl2O4 samples have weak ferromagnetic behavior and the magnetization values increases with increasing the concentration of Mn²âº ions in the CoAl2O4 lattice. The sample Mn0.5Co0.5Al2O4 possessed higher surface area and smaller crystallite size than other samples, which led to enhance the performance toward the selective oxidation of benzyl alcohol into benzaldehyde.

The Role of Mn(2+)-Doping on Structural, Morphological, Optical, Magnetic and Catalytic Properties of Spinel ZnFe2O4 Nanoparticles.

Spinel Mn(x)Zn(1-x)Fe2O4 (0.0 ≤ x ≤ 1.0) nanoparticles (NPs) were successfully synthesized by a facile one-pot microwave combustion method using urea as the fuel. The formation of single phase cubic spinel structure was confirmed by powder X-ray diffraction (XRD), Rietveld analysis and Fourier transform infrared (FT-IR) spectroscopy and the calculated average crystallite size is in the range of 37.57 nm to 25.43 nm. The high resolution scanning electron microscopy (HR-SEM) and high resolution transmission electron microscopy (HR-TEM) results indicated that the as-prepared spinel Mn(x)Zn(1-x)Fe2O4 NPs showed high crystallinity and uniform size distribution with particles-like morphologies. The energy dispersive X-ray (EDX) analysis was confirmed the elemental composition and purity of the samples. The estimated band gap energy from UV-Visible diffuse reflectance spectroscopy (UV-Vis. DRS) is about 1.88 eV to 2.35 eV. The broad visible emission band is observed in the entire photoluminescence (PL) spectroscopy for all compositions. The variation of magnetization (M(s)) value of the samples was studied by vibrating sample magnetometer (VSM) and the lower compositions (x = 0.0, 0.2 and 0.4) show a superparamagnetism and the higher composition (x = 0.6, 0.8 and 1.0) show a ferromagnetic behavior with hysteresis and that the M(s) values increased with increasing Mn2+ content to reach a maximum value of 60.99 emu/g for MnFe2O4. All composition of spinel Mn(x)Zn(1-x)Fe2O4 NPs were successfully tested as catalyst for the oxidation of benzyl alcohol into benzaldehyde, which has resulted 83.29 and 96.51% conversion efficiency of ZnFe2O4 and Mn0.6Zn0.4Fe2O4 respectively.

Toward routine detection of extracellular vesicles in clinical samples.

The majority, if not all, of human cell types secrete extracellular vesicles (EVs) into their environment, at least partly as a means of intercellular communication. These secreted vesicles can be detected in most bodily fluids including blood, urine, and saliva. The number of secreted vesicles and their composition is altered in various pathological conditions, raising opportunities to exploit EVs as diagnostic and/or prognostic biomarkers. For this to become a reality, it is important to reach consensus regarding the standardization of protocols for sample collection, EV isolation, handling, and storage for valid comparison and interpretation of measurements. Depending on the information required, there are several detection options including EV number and size distribution, molecular surface markers, procoagulation activity, and RNA content. For these purposes, different techniques are currently utilized or under development. This review discusses the techniques that have the potential to become standard EV detection methods in a clinical diagnostic setting. In addition to the accuracy of the detection technique, other factors such as high-throughput, cost-effectiveness, time consumption, and required operator skill are important to consider. A combination of increasing fundamental knowledge, technological progress, standardization of sample collection, and processing protocols is required for EVs to become reliable predictors of altered physiology or development of disease suitable for routine clinical diagnostics. Cancer and (cardio)vascular disorders are examples of pathologies where EV detection may be applied in the near future for diagnosis and/or prognosis.

Hemodynamics and anatomy of elastase-induced rabbit aneurysm models: similarity to human cerebral aneurysms?

BACKGROUND AND PURPOSE: Animal models provide a mechanism for fundamental studies of the coupling between hemodynamics and pathophysiology in diseases such as saccular aneurysms. In this work, we evaluated the capability of an elastase-induced saccular aneurysm model in rabbits to reproduce the anatomic and hemodynamic features typical for human intracranial aneurysms. MATERIALS AND METHODS: Saccular aneurysms were created in 51 rabbits at the origin of the RCCA. Twelve weeks' postcreation, the lumen geometry of the aneurysm and surrounding vasculature was acquired by using 3DRA. Geometric features of these models were measured. Pulsatile 3D CFD studies were performed with rabbit-specific inlet profiles. RESULTS: Geometric features, including aneurysm height, width, neck diameter, aspect ratio, and NSI of all 51 rabbit aneurysm models fell within the range reported for human IAs. The distribution and range in values of pressure, WSS, and OSI were also typical for human IAs. A single recirculation region was observed in 33 (65%) of 51 cases, whereas a second transient recirculation zone was observed in 18 (35%) cases. Both of these flow types are commonly observed in human IAs. CONCLUSIONS: Most hemodynamic and geometric features in a commonly used elastase-induced rabbit saccular aneurysm model are qualitatively and quantitatively similar to those seen in large numbers of human cerebral aneurysms.

Synthesis of 2'-C-methyl-beta-D-ribofuranosylimidazo [4,5-d]-pyridazine derivatives (2-aza-3-deazapurine nucleoside analogues).

In order to evaluate their antiviral properties, two imidazo[4,5-d]pyridazine 2'-C-methyl-beta-D-ribofuranonucleoside derivatives have been synthesized.

Synthesis of 5-aza-7-deazaguanine nucleoside derivatives as potential anti-flavivirus agents.

Coupling suitable sugars (D- or L-ribofuranose, 2' or 3-deoxysugar, branched sugars) with 2-aminoimidazo[1,2-a]-s-triazin-4-one was carried out using the different reaction conditions: 1) condensation in the presence of sodium hydride; or 2) condensation using Vorbrüggen's methods. The 5-aza- 7-deazaguanine nucleoside analogues obtained were evaluated in cell culture experiments for the inhibition of the replication of a number of RNA viruses, including BVDV, YFV, and WNV.