Low-dose 2D X-ray angiography enhancement using 2-axis PCA for the preservation of blood-vessel region and noise minimization.

Enhancing 2D angiography while maintaining a low radiation dose has become an important research topic. However, it is difficult to enhance images while preserving vessel-structure details because X-ray noise and contrast blood vessels in 2D angiography have similar intensity distributions, which can lead to ambiguous images of vessel structures. In this paper, we propose a novel and fast vessel-enhancement method for 2D angiography. We apply filtering in the principal component analysis domain for vessel regions and background regions separately, using assumptions based on energy compaction. First, we identify an approximate vessel region using a Hessian-based method. Vessel and non-vessel regions are then represented sparsely by calculating their optimal bases separately. This is achieved by identifying periodic motion in the vessel region caused by the flow of the contrast medium through the blood vessels when viewed on the time axis. Finally, we obtain noise-free images by removing noise in the new coordinate domain for the optimal bases. Our method was validated for an X-ray system, using 10 low-dose sets for training and 20 low-dose sets for testing. The results were compared with those for a high-dose dataset with respect to noise-free images. The average enhancement rate was 93.11±0.71%. The average processing time for enhancing video comprising 50-70 frames was 0.80±0.35s, which is much faster than the previously proposed technique. Our method is applicable to 2D angiography procedures such as catheterization, which requires rapid and natural vessel enhancement.

Preparation of highly monodispersed hybrid silica spheres using a one-step sol-gel reaction in aqueous solution.

The successful one-step preparation method of monodisperse hybrid silica particles was studied using organosilane chemicals in aqueous solution. In general, almost all of the hybrid silica materials were made by a complex method where organic materials were coated on the surface of silica substrate via chemical reaction. However, our novel method can be applied to prepare colloidal hybrid particles without using substrate material. This method has three advantages: (i) this simple method gives the opportunity to prepare hybrid particles with high monodispersity through the self-hydrolysis of various organosilane monomers in aqueous solution, (ii) this efficient method can be applied to load lots of organic functional groups on the surface of silica particles through a one-step preparation method using only organosilane, and (iii) this effective method can be used to control the particle size of the product by changing the experimental conditions such as the concentration of the precursor or the reaction temperature. Detailed characterization of the hybrid particles by scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis (TGA) was performed to elucidate the morphologies and properties of the hybrid silica particles.

New approach to the immobilization of glucose oxidase on non-porous silica microspheres functionalized by (3-aminopropyl)trimethoxysilane (APTMS).

The immobilization and encapsulation of glucose oxidase (GOD) onto the mesoporous and the non-porous silica spheres prepared by co-condensation of tetraethylorthosilicate (TEOS) and (3-aminopropyl)trimethoxysilane (APTMS) in the water-in-oil (W/O) emulsion system were studied. The terminal amine group was used as the important functionality for GOD immobilization on the silica substrate. When only TEOS is used as a silica source, the disordered mesoporous silica microspheres are obtained. As the molar ratio of APTMS to TEOS (R(AT)) increases, the surface area and pore volume of the silica particles measured by nitrogen adsorption and desorption method and SEM decrease rapidly. Particularly, the largest change of the surface morphology is observed between R(AT)=0.20 and R(AT)=0.25. The amount and the adsorption time of immobilized enzyme were measured by UV spectroscopy. About 20wt% of GOD was immobilized into the silica substrates above R(AT)=0.60 and was completely adsorbed into the substrate of R(AT)=0.80 with lapse of 4h after addition. In the measurement of the thermal stability, GOD dissolved in buffer solution loses nearly all of its activity after 30 min at 65 degrees C. In contrast, GOD immobilized on the surface-modified silica particles still retains about 90% of its activity after the same treatment. At this temperature, the immobilized glucose oxidase retained half of its initial activity after 4h. It is shown that the suitable usage of functionalizing agent like APTMS as well as the control of surface morphology is very important on the immobilization of enzyme.

Inhibitory effect of apoptosis in human astrocytes CCF-STTG1 cells by lemon oil.

The effects of lemon pure essential oils on the heat shock-induced apoptosis in human astrocytes cell line CCF-STTG1 were examined. In previous studies, heat shock has been reported to induce the apoptosis or programmed cell death through the activation of caspase-3. Treatment of heat shock on CCF-STTG1 cells markedly induced apoptotic cell death as determined by flow cytometry. Interestingly, pre-treatment with lemon pure essential oils on CCF-STTG1 cells inhibited the heat shock-induced apoptosis. Lemon oil also inhibited the heat shock-induced apoptosis in primary cultured rat astrocytes. To determine whether lemon oil inhibits the heat shock-induced activation of the apoptotic proteases, activation of caspase-3 was assessed by Western blotting. DNA fragmentation, giemsa staining, and heat shock-induced activation of caspase-3 were blocked by lemon pure essential oil, which is consistent with flow cytometry. Poly-ADP-ribose polymerase (PARP), the cysteine protease substrate, was fragmented as a consequence of apoptosis by heat shock. Lemon oil inhibited the PARP fragmentation. These results suggest that lemon pure essential oils may modulate the apoptosis through the activation of the interleukin-1 beta -converting enzyme-like caspases.