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Duchenne muscular dystrophy (DMD) is characterized by progressive muscle degeneration accompanied by dilated cardiomyopathy. Recently, abnormality of yes-associated protein (YAP) has been reported as the pathogenesis of muscle degeneration of DMD; however YAP activity remains unclear in dystrophic heart of DMD. Herein, we investigated YAP activity using disease-specific induced pluripotent stem cell (iPSC) derived cardiomyocytes (CMs) in DMD. DMD-iPSCs were generated from DMD patient with exon 48–54 deletion in DMD, and genome-edited (Ed)-DMD-iPSCs with in-frame (Ed-DMD-iPSCs) were created using CRISPR/Cas9. Nuclear translocation of YAP [nuclear (N)/cytoplasmic (C) ratio] was significantly lower in DMD-iPSC-CMs than in Ed-DMD-iPSC-CMs. In addition, Ki67 expression, indicating proliferative ability, was significantly lower in DMD-iPSC-CMs than Ed-DMD-iPSC-CMs. Therefore, immunofluorescent staining showed that actin stress fibers associated with YAP activity by mechanotransduction were disorganized in DMD-iPSC-CMs. Lysophosphatidic acid (LPA), a known lipid mediator on induction of actin polymerization, significantly increased YAP activity and actin dynamics in DMD-iPSC-CMs using live cell imaging. These results suggested that altered YAP activity due to impaired actin dynamics reduced proliferative ability in DMD-iPSC-CMs. Hence, decreased YAP activity in dystrophic heart may contribute to DMD-cardiomyopathy pathogenesis.

Arrhythmogenic cardiomyopathy (ACM) caused by TMEM43 p.S358L is a fully penetrant heart disease that results in impaired cardiac function or fatal arrhythmia. However, the molecular mechanism of ACM caused by the TMEM43 variant has not yet been fully elucidated. In this study, we generated knock-in (KI) rats harboring a Tmem43 p.S358L mutation and established induced pluripotent stem cells (iPSCs) from patients based on the identification of TMEM43 p.S358L variant from a family with ACM. The Tmem43-S358L KI rats exhibited ventricular arrhythmia and fibrotic myocardial replacement in the subepicardium, which recapitulated the human ACM phenotype. The four-transmembrane protein TMEM43 with the p.S358L variant (TMEM43S358L ) was found to be modified by N-linked glycosylation in both KI rat cardiomyocytes and patient-specific iPSC-derived cardiomyocytes. TMEM43S358L glycosylation increased under the conditions of enhanced endoplasmic reticulum (ER) stress caused by pharmacological stimulation or age-dependent decline of the ER function. Intriguingly, the specific glycosylation of TMEM43S358L resulted from the altered membrane topology of TMEM43. Moreover, unlike TMEM43WT , which is mainly localized to the ER, TMEM43S358L accumulated at the nuclear envelope of cardiomyocytes with the increase in glycosylation. Finally, our comprehensive transcriptomic analysis demonstrated that the regional differences in gene expression patterns between the inner and outer layers observed in the wild type myocardium were partially diminished in the KI myocardium prior to exhibiting histological changes indicative of ACM. Altogether, these findings suggest that the aberrant accumulation of TMEM43S358L underlies the pathogenesis of ACM caused by TMEM43 p.S358L variant by affecting the transmural gene expression within the myocardium.

Background Fabry disease is an X-linked disease caused by mutations in α-galactosidase A (GLA); these mutations result in the accumulation of its substrates, mainly globotriaosylceramide (Gb3). The accumulation of glycosphingolipids induces pathogenic changes in various organs, including the heart, and Fabry cardiomyopathy is the most frequent cause of death in patients with Fabry disease. Existing therapies to treat Fabry disease have limited efficacy, and new approaches to improve the prognosis of patients with Fabry cardiomyopathy are required. Methods and results We generated induced pluripotent stem cell (iPSC) lines from a female patient and her son. Each iPSC clone from the female patient showed either deficient or normal GLA activity, which could be used as a Fabry disease model or its isogenic control, respectively. Erosion of the inactivated X chromosome developed heterogeneously among clones, and mono-allelic expression of the GLA gene was maintained for a substantial period in a subset of iPSC clones. Gb3 accumulation was observed in iPSC-derived cardiomyocytes (iPS-CMs) from GLA activity-deficient iPSCs by mass-spectrometry and immunofluorescent staining. The expression of ANP was increased, but the cell surface area was decreased in iPS-CMs from the Fabry model, suggesting that cardiomyopathic change is ongoing at the molecular level in Fabry iPS-CMs. We also established an algorithm for selecting proper Gb3 staining that could be used for high-content analysis-based drug screening. Conclusions We generated a Fabry cardiomyopathy model and a drug screening system by using iPS-CMs from a female Fabry patient. Drug screening using our system may help discover new drugs that would improve the prognosis of patients with Fabry cardiomyopathy.

Nanocrystalline zirconia with high surface area and pure tetragonal crystalline phase was prepared using ethylene diamine (EDA), which acts as both precipitating agent and dispersant of the zirconium precursor. The yttria stabilized zirconia (Y-TZP) is a very attractive material due to its excellent biocompatibility, high fracture toughness, high strength and low wear rates. So zirconyl chloride octahydrate (ZrOCl2 · 8H2O) and yttrium chloride hexahydrate (YCl3 · 6H2O) in different molar ratios were used as starting solution. The detailed effects of various process parameters such as reaction time, concentration of the precursor solution, amount of ethylene diamine, and calcination temperature on the structural properties of the zirconia powders were investigated. The preparation conditions significantly affected the structural stability, crystal size, and crystal phase of the final material. Increases in the reaction time and amount of ethylene diamine led to a substantial increase of the crystal growth rate, the specific surface area, and the tetragonal content of the zirconia.

Organic/inorganic biocomposite materials for biodegradable fixation medical devices require osteoconductivity, biocompatibility, and adequate mechanical properties with biodegradation behavior. The objective of this study was to investigate the effect of Si ions substituted in β-tricalcium phosphate (β-TCP) on the mechanical properties of organic/inorganic biocomposites. Biodegradable composite materials were prepared with polylactic acid (PLA) as the matrix and nano Si-substituted β-TCP as the osteoconductive filler by solvent mixing and conventional molding. The nanostructured Si-substituted β-TCP powders were synthesized by co-precipitation, controlling the quantity of Si ions. The amount of nanostructured Si-substituted β-TCP powders in composites was varied in the 0-40 wt% range and the material properties were compared with those of pure β-TCP/PLA composites. The influence of Si ions on the mechanical properties of the composites was evaluated by tensile and flexural tests.

Osteoconductive, biocompatible, and resorbable organic/inorganic composites are most commonly used in fixation medical devices, such as suture anchors and interference screws, because of their unique physical and chemical properties. Generally, studies on biodegradable composites have focused on their mechanical properties based on the composition and the individual roles of organic and inorganic biomaterials. In this study, we prepared biodegradable organic/inorganic nanocomposite materials using the solvent mixing process and conventional molding. We used polylactic acid (PLA) as the matrix and nano-sized hydroxyapatite (nano-HAp) as the osteoconductive filler. The content of nano-HAp was varied in 0-30 wt% and its influence on the In-Vitro mechanical performance of PLA/HAp nanocomposites was evaluated. The In-Vitro mechanical properties of nanocomposites were evaluated using standardized tensile and flexural tests after different immersion times in simulated body fluid.

Ectopic foci from pulmonary veins (PVs) comprise the main trigger associated with the initiation of atrial fibrillation (AF). An abrupt anatomical narrow-to-wide transition, modeled as in vitro geometrical patterning with similar configuration in the present study, is located at the junction of PVs and the left atrium (LA). Complex cellular composition, i.e., constituent cell heterogeneity, is also observed in PVs and the PVs-LA junction. High frequency triggers accompanied with anatomical irregularity and constituent cell heterogeneity provoke impaired conduction, a prerequisite for AF genesis. However, few experiments investigating the effects of these factors on electrophysiological properties using human-based cardiomyocytes (CMs) with atrial properties have been reported. The aim of the current study was to estimate whether geometrical patterning and constituent cell heterogeneity under high frequency stimuli undergo conduction disturbance utilizing an in vitro two-dimensional (2D) monolayer preparation consisting of atrial-like CMs derived from human induced pluripotent stem cells (hiPSCs) and atrial fibroblasts (Fbs). We induced hiPSCs into atrial-like CMs using a directed cardiac differentiation protocol with the addition of all-trans retinoic acid (ATRA). The atrial-like hiPSC-derived CMs (hiPSC-CMs) and atrial Fbs were transferred in defined ratios (CMs/Fbs: 100%/0% or 70%/30%) on manually fabricated plates with or without geometrical patterning imitating the PVs-LA junction. High frequency field stimulation emulating repetitive ectopic foci originated in PVs were delivered, and the electrical propagation was assessed by optical mapping. We generated high purity CMs with or without the ATRA application. ATRA-treated hiPSC-CMs exhibited significantly higher atrial-specific properties by immunofluorescence staining, gene expression patterns, and optical action potential parameters than those of ATRA-untreated hiPSC-CMs. Electrical stimuli at a higher frequency preferentially induced impaired electrical conduction on atrial-like hiPSC-CMs monolayer preparations with an abrupt geometrical transition than on those with uniform geometry. Additionally, the application of human atrial Fbs to the geometrically patterned atrial-like hiPSC-CMs tended to further deteriorate the integrity of electrical conduction compared with those using the atrial-like hiPSC-CM alone preparations. Thus, geometrical narrow-to-wide patterning under high frequency stimuli preferentially jeopardized electrical conduction within in vitro atrial-like hiPSC-CM monolayers. Constituent cell heterogeneity represented by atrial Fbs also contributed to the further deterioration of conduction stability.

Antimicrobial peptides (AMPs) are a promising new class of antibacterial compounds. However, their applications in the treatment of intracellular pathogenic bacteria have been limited by their in vivo instability and low penetrating ability into mammalian cells. Here, we report that gold nanoparticles conjugated with DNA aptamer (AuNP-Apt) efficiently delivered AMPs into mammalian living systems with enhanced stability of the AMPs. C-terminally hexahistidine-tagged A3-APO (A3-APO His ) AMPs were loaded onto AuNPs conjugated with His-tag DNA aptamer (AuNP-Apt His ) by simple mixing and were delivered into Salmonella enterica serovar Typhimurium ( S. Typhimurium)-infected HeLa cells, resulting in the increased viability of host cells due to the elimination of intracellular S. Typhimurium cells. Furthermore, the intravenous injection of AuNP-Apt His loaded with A3-APO His into S. Typhimurium -infected mice resulted in a complete inhibition of S. Typhimurium colonization in the mice organs, leading to 100% survival of the mice. Therefore, AuNP-Apt His can serve as an innovative platform for AMP therapeutics to treat intracellular bacterial infections in mammals.

Objective To evaluate the protective effect of Ginkgo biloba extract (GBE) on gentamicin (GM)-induced morphological damage of an artificial otoconia. Materials and methods An artificial otoconia powder was placed in a 12-well culture plate containing artificial endolymph. GM (500 μL; 40 mg/mL) was added to the first four wells. GM (500 μL; 40 mg/mL) with GBE (500 μL) was added to the next four wells. PBS (500 μL) was added to the remaining four wells as a control. The levels of nitric oxide (NO) synthesis were determined in the supernatants of each group. Alteration in surface morphology and calcium content were determined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. Results NO concentration increased in the GM-treated group compared with that in the control group. When the calcite-gelatin composite was treated with GBE, GM-stimulated NO production significantly decreased. The surface of the calcite-gelatin composite exposed to GM showed erosive fissures and had a honeycomb-like appearance. GBE showed a protective effect against dissolution. EDX showed that the calcium content of the GM-treated group significantly decreased. However, the GBE-treated group demonstrated an insignificant change in the calcium concentration compared with the control. Conclusion From these results, we can conclude that GBE may have a protective effect against GM-induced NO production and superficial structural changes.

Refractory castables containing calcium aluminate cement (CAC) are widely used in a range of furnace lining applications in the iron and steel, cement, glass, ceramic, and petrochemical industries. However, magnesia-phosphate cement (MPC) based material could be a new types of cement material, with many advantages such as rapid hydration, high early strength and circumstance suitability, which has very important value and wide application. In this study, MPC was used at Chromia/Alumina castable as binder addition instead of conventional calcium aluminate cement. Meanwhile, it also explains the relationship between the micro-mechanism and performance by micro methods such as SEM. The results shows that MPC based castables have good corrosion resistance, interface adhesiveness and abrasion resistance.

Biphasic calcium phosphate bioceramics were fabricated from the recycling of bone ash which is mostly used as raw materials of bone china. Precursor calcium phosphate powders were prepared by soaking the commercial bone ash in 0.1 M of NaOH solution at 80°C for 4 h. Calcium phosphate powders was obtained by calcination at 800°C for 1 h to completely remove residual organics. Biphasic calcium phosphate bioceramics which is composed of hydroxyapatite and tricalcium phosphate was fabricated by the sintering of pressed compacts at 1200°C for 1 h under moisture protection. The bone ash derived-biphasic calcium phosphate ceramics consists of mostly HA and small amounts of α-tricalcium phosphate, magnesium oxide and calcium oxide. After polishing the HA ceramics, they were immersed in buffered water at 37°C for 3 and 7 days. The bone ash derived- biphasic calcium phosphate ceramics show high biostability in liquid environment with immersion time compared with commercial calcium phosphate ceramics.

This work describes dissolution and related mechanical weakening of phase-pure and dense hydroxyapatite (HA) in distilled water of pH 7.4. Phase-pure HA powder has been synthesized by a wet precipitation method. After uniaxial and cold isostatic pressing, and sintering at 1200°C, dense HA with 98% above of the theoretical density has been obtained. The results show that HA powder has stoichiometric composition with a Ca/P ratio 1.67 ± 0.02. Even after extended exposure for 10 h, no second phases, such as tricalcium phosphate (TCP) and calcium oxide can be observed. Although the HA is supposed to be stable in liquid environment, surface dissolution appears specifically at material’s grain boundaries after immersion for 7 days. Following further immersion to 14 days, grain boundary dissolution progresses interior to the bulk following these paths. This dissolving behavior generates HA particles, disintegrates dense microstructure and at least forms micron-scale cavity. Mechanical property of the HA has been also affected. Fracture toughness (KIc) of the HA sintered body is approximately 1.0 MPa•m1/2. It drastically decreases to almost half of the initial value due to the severe surface dissolution

In situ preparation of magnesium (Mg) substituted biphasic calcium phosphate (BCP) of hydroxyapatite (HAp)/β-tricalcium phosphate (β-TCP) were carried out through aqueous co-precipitation method. The concentrations of added magnesium were varied with the calcium in order to obtain constant (Ca + Mg)/P ratios of 1.602. X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy were used to characterize the structure of synthesized magnesium substituted BCP powders. The results have shown that substitution of magnesium in the calcium deficient apatites revealed the formation of biphasic mixtures of different HAp/β-TCP ratios after heating at 1000 °C. The ratios of the formation of phase mixtures were dependent on the content of magnesium. After immersing in Hanks’ balanced salt solution (HBSS) for 1 week, 1 wt% magnesium substituted BCP powders were degraded and precipitation started to be formed with small granules consisting of number of flake-like crystal onto the surface of synthesized powders. On the other hand, in the case of pure BCP powders, the formation of new precipitates was detected after immersion in HBSS for 2 weeks. On the basis of these results, magnesium substituted BCP could be able to develop a new apatite phase on the surface in contact with physiological fluids faster than BCP does. In addition, the retention time to produce the new apatite phase in implantation operation for the BCP powder could be controlled by the amount of magnesium substitution.

Hydroxyapatite (HA) ceramics were prepared from the bone ash which is mostly used as animal feeds or raw materials. Dissolving behaviors of the HA in buffered water were investigated and compared with commercial HA for further use as biomaterials. HA ceramics were prepared by soaking the bone ash in 0.1 M of NaOH solution at 80°C for 4 h. The ash was calcined at 800°C for 1 h to completely remove organics, and then sintered at 1200°C for 1 h under moisture protection. The bone ash derived-HA consists of mostly HA and small amounts of α-tricalcium phosphate, calcium oxide phosphate, magnesium oxide and calcium oxide. After polishing the HA ceramics, they were immersed in buffered water at 37°C for 3 and 7 days. We previously found that grain boundaries of synthetic HA were intensively dissolved in buffered water. On the other hand, the bone ash derived-HA shows high stability in liquid environment with immersion time compared with commercial HA.

In situ preparation of silicon (Si) substituted biphasic calcium phosphate (BCP) of hydroxyapatite (HAp)/ β-tricalcium phosphate (β-TCP) were carried out through aqueous co-precipitation method. The concentrations of added silicon were varied with the phosphor in order to obtain constant Ca/(P+Si) ratios of 1.602. X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy were used to characterize the structure of synthesized silicon substituted BCP powders. The characterization revealed that the formation of biphasic mixtures of different HAp/ β-TCP ratios was dependent on the content of silicon. After immersing in Hanks' balanced salt solution (HBSS) for 1 week, 3 wt% silicon substituted BCP powders were degraded and precipitation started to be formed with small granules consisting of number of flake-like crystal onto the surface of synthesized powders. In the case of 1 wt% silicon substituted BCP powders, the degradation behavior was detected after immersion in HBSS for 3 weeks. On the other hand, silicon unsubtituted BCP powders were not degraded even after that duration. On the basis of these results, silicon substituted BCP is able to develop a new apatite phase on the surface in contact with physiological fluids faster than BCP does. This enhanced reactivity resulted in reduction for the stability of the β-TCP structure due to SiO 4 tetrahedral distortion and disorder at the hydroxyl site when silicon incorporates into BCP.

Bone ash-derived hydroxyapatite (HA) ceramics were prepared by pressureless sintering and hot pressing, and their dissolution behavior was examined in buffered water. HA powder was obtained by soaking bone ash in a 0.1M NaOH solution at 80 °C, followed by calcination at 1000 °C to completely remove the organic material. The crystal structure of the HA powder with a particle size of approximately 1 μm was mainly hydroxyapatite with a minimal amount of α-tricalcium phosphate. To improve densification, the powder was hot-pressed at 1000 °C for 0.5 h under a pressure of 30 MPa in an Ar atmosphere. The sintered density of the hot-pressed HA was 95 % of the theoretical density, which is much higher than the 70% obtained for the pressureless-sintered compact. In the porous HA ceramics obtained by pressureless sintering, dissolution occurred adjacent to the pores rather than in the dense part, which increased the residual porosity. On the other hand, the hot-pressed HA showed grain boundary dissolution followed by particle loosening.

Geopolymers were prepared by using the dried fly ash from industrial by-product, NaOH as alkaline activator and Na2SiO3 as liquid glass. Calcium carbonate from a clam shell was added to provide attachment and growth of environmental organisms on the geopolymers. We investigated the effects of a shell powder contents on the microstructure and bonding properties of the geopolymers to normal cement. The major chemical compositions of fly ash were Si and Al at the ratio of 2 to 1 in wt%. The shell powder with layer sheet consisted of aragonite phase. As increasing the amount of the shell powder, fly ash was not polymerized and remained spherical. The bonding between geopolymers and normal cement was obtained when 0-15 wt% of the shell powder was added. On the other hand, bonding was not achieved with higher shell contents of 20-25 wt%.

The response of human bone marrow cell to bone ash-derived hydroxyapatite (HA) and tuna bonederived HA powders was compared. HA ceramics were prepared from the commercial bone ash and waste of tuna bone. HA powders were prepared by soaking the bone ash and tuna bone in 0.1M of NaOH solution at 80 °C for 4 hours. Both powders were calcined at 800 °C for 1 hour to completely remove organic and were attritor-milled for 24 hours. The bone ash-derived HA (AHA) and tuna bone-derived HA (THA) ceramics were prepared by cold isostatically pressed and sintered 1200 °C with a dwell time of 1 hour. A human bone cell line MG-63 cells were used to test biocompatibility of AHA and THA ceramics. Cell suspensions in DMEM containing 10% FBS and 1% penicillin-streptomycin were seeded onto 24-well plate containing THA and AHA ceramics. Cell proliferation was evaluated by MTS assay, and cell morphology was observed by SEM.

Background: The renin-angiotensin-aldosterone system affects cellular morphology and function in the heart under a variety of pathologic conditions. In the present study the effects of aldosterone on the expression of connexin (Cx) 43 gap junctions in cardiomyocytes were investigated. Methods and Results: Cultured rat ventricular myocytes were exposed to aldosterone for 24 h. The protein and mRNA expression of Cx43 was estimated. Propagation of excitation was visualized by a multiple electrode array system. Treatment of the myocytes with 10-8 mol/L aldosterone resulted in a significant upregulation of Cx43 (by ~1.5-fold in protein and by ~1.2-fold in mRNA). The immunoreactive signal of Cx43 was also increased. Conduction velocity (CV) was increased by ~24%. Treatment of the myocytes with aldosterone at higher concentrations (10-6-10-4 mol/L) caused a significant downregulation of Cx43 protein (by ~0.3-fold) without affecting Cx43 mRNA levels, and decreased the CV by ~23%. The Cx43 upregulation and CV acceleration at 10-8 mol/L aldosterone were prevented by pretreatment with eplerenone, but unaffected by mifepristone. Pretreatment of the myocytes with eplerenone or mifepristone did not prevent the Cx43 downregulation by aldosterone at 10-6-10-4 mol/L. Conclusions: Aldosterone may be involved in arrhythmogenic gap junction remodeling through its dual effects on the expression of Cx43. (Circ J 2009; 73: 1504 - 1512)

Hydroxyapatite (HA) has been of interest in many industrial applications, such as ion exchange, catalysis and biomaterials. Chelating agents have often been used to prepare inorganic powders in the form of sphere, rod, whisker and fiber. In this study, HA whiskers were synthesized directly from typically shaped HA powders by refluxing at 80 and 100 °C for 24 h using ethylenediamine tetraacetic acid (EDTA). 3% or 6% of hydrogen peroxide (H 2 O 2 ) was used to promote precipitation of HA crystals. The pH of the solution was adjusted at 7 or 9 by adding ammonia solution. The higher the H 2 O 2 concentration, pH value and refluxing temperature, the longer and thinner whiskers were formed. The whiskers produced at 100 °C with 6% of H 2 O 2 and pH 9 had the highest aspect ratio of about 50–60 (a length of 3 μm and a width of 0.05 μm).

The reaction-sintered zirconia-alumina and zirconia-spinel ceramics having low firing shrinkage were prepared from ZrO2(Ca-PSZ)/Al and ZrO2(Baddellyite)/MgAl powder mixtures via the attrition milling and the effect of the characteristics of used raw powders was investigated. Flaky Al powders mixed with coarse Ca-PSZ powders was not effectively comminuted due to lower hardness of zirconia powders. So by using the alumina ball media or coarse Al2O3 powders rather than Al, the milling efficiency could be much more increased. When fused Ca-PSZ powder was reaction-sintered with Al at 1550 for 3 hours, the reaction-sintering and densification were somewhat difficult because the Ca-PSZ/Al powder mixture was not effectively comminuted. And the Ca ion in Ca-PSZ grains diffused into alumina grains during sintering so that the unstabilization of Ca-PSZ body was occurred which gave the cracks in the specimens. But when MgAl alloy powder was added to monoclinic zirconia, Mg and Al became to oxide at first and subsequently converted to spinel(MgAl2O4) during heating and finally unreacted MgO seemed to stabilize the zirconia. The oxides which formed at the oxidation process would have very fine grain size so that the reaction sintering was more effective to densification and homogeneous microstructure. The mechanical properties of reaction-sintered stabilized zirconia/spinel composite were better than only MgO stabilized zirconia. Sintering behavior in reaction and mechanical properties of sintered body were examined, with emphasis on the relations between spinel formation and mechanical properties.

Dissolution of calcium phosphate powders with different compositions in simulated body fluid was investigated. Hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) powders were synthesized by a precipitation method and by controlling pH of the solution. Biphasic calcium phosphate (BCP) powders were prepared by mixing the HA and β-TCP powders with ratio of 80:20 and 60:40 in weight % in a planetary mill for 4 h. For dissolution test, 0.5g of each β-TCP, HA and BCP powders were immersed in 50 ml of SBF at 37°C for 3-28 days. HA powders with stoichiometric composition showed no significant morphological change regardless of the immersion time. β-TCP powders were not dissolved in SBF in spite of its high solubility. The surface of BCP powders became rough due to dissolution with increasing immersion time. This surface dissolution gradually extended into the core region of the particles resulting in disintegration of the dense particle into fine crystallites. It may be caused that the milling process during preparation of BCP powders may induce stress concentration or formation of dislocation on the surface of particles.

Calcium phosphate ceramics (CPC) have been attractively used in different areas of biomedical applications, such as substances of artificial hard tissue replacement implants, drug delivery system due to their biocompatibility and bioactivity. In this work, three calcium phosphate powders between Ca/P molar ratio 1.50-1.67 were synthesized by aqueous precipitation method, using the mixture of Ca(NO3)2·4H2O and H3PO4 solutions to ammonia solution. During the precipitation reaction, Ca/P molar ratio was adjusted by controlling pH of the solution between 8.0 and 10.5 by the addition of ammonium hydroxide solution. All powders were treated at 800 oC for 2 hrs. The calcined powders were immersed in pH 7.4 distilled water at 37°C for 3 and 7 days. Decomposition and related dissolution with the various Ca/P ratios were investigated by XRD, FTIR, and TEM observation.

Hydroxyapatite derived from human teeth was sintered at 1200°C for 2 h. Dissolving behavior of the biologically derived HA (BHA) in distilled water was investigated and compared with an artificial hydroxyapatite (HA) made of synthetic HA powder. All disks were immersed in 40 ml of pH 7.4 distilled water (buffered using 0.05 M Tris.) for 7 and 14 days at 37°C. All detectable peaks in the HA are identical only to HA lattice planes, whereas BHA consisted of a mixture of HA and β-tricalcium phosphate (TCP). In the case of the HA specimen, the surface dissolution was initiated at grain boundaries followed by generated many separated grains and large defect like cavities. On the other hand, biologically derived HA showed that definite grains considered as β-TCP was predominantly dissolved and the grains were separated from the matrix leaving pores. In the mean time, the rest region, mainly consisting of HA, did not show any evidence of dissolution. It seems that BHA is more stable than the artificial HA in liquid environment.

Fabrication of paste at low temperature has been developed in order to apply for various electronic devices, such as bus electrode and address electrode in PDP, especially for enlargement of a screen size. In this study, nano-sized silver particles with 10 - 30 nm were synthesized from silver nitrate (AgNO3) by a chemical reduction method. To prepare Pb-free silver paste, the silver nanoparticles were mixed with conventional silver powder with an average particle size of 1.6 and conventional Pb-free frit. Thick films were fabricated from silver paste by a screen printing on alumina substrate and the films were fried at temperatures ranging from 550 °C to 600 °C. Microstructures of the fried thick films were analyzed by FE-SEM. Sheet resistivity of fried thick films was measured and also the relationship between sinterability and conductivity of these films were investigated.

Nano-sized silver particles are considered to apply a silver paste for electrode because of its high conductivity on sintering at low temperature. In this study, silver nanoparticles as seeds were prepared by chemical reduction method with capping agent. Silver particles were prepared using SDS (Sodium dodecyl sulfate) as a surfactant and silver nanoparticles as seeds and reacted with ascorbic acid as a reduction agent. The silver seeds with 10-20 nm in size with uniform distribution were formed and the size and shape of silver particles were strongly dependent on the concentration of surfactant.

TiO2 photocatalyst has attracted much attention in recovering valuable metal ions from industrial wastewater because TiO2 shows chemical stability and good wear resistant, and a photocatalytic reaction occurs by illumination of the sun or fluorescent light. In this study, Au removal and recovery in a gilding wastewater using TiO2 photocatalyst was evaluated. Commercially obtained TiO2 powder and TiO2 film prepared by spray and screen print method were used for Au adsorption. The cyanide existed in a plating wastewater was firstly removed with peroxide or persulfate because a driving force for Au ion reduction during photocatalytic process could decrease by the existed cyanide. Compared with persulfate, peroxide shows relatively slow removal rate of cyanide but no precipitation occurs. With respect to photocatalytic reaction of TiO2 powder and film for Au removal and recovery, it was found that the addition of 10 vol% of methanol as a hole scavenger increases the rates of Au ion reduction and Au adsorption on the TiO2 powder and film, subsequently the reaction of Au photoadsorption was completed within 60 min. Au lumps on the TiO2 particles obtained by photocatalytic reduction of TiO2 was confirmed by XRD analysis and TEM observation.

Commercial hydroxyapatite (HA) powders were calcined at the temperature range of 1000-1350 °C in air and the calcined powders were immersed in simulated body fluid (SBF) at 37 °C for 3 or 7 days. At 1200°C, HA gradually releases its OH' ions and transforms into oxyhydroxyapatite (Ca 10 (PO 4 ) 6 O x (OH)2-2x, OHAP). HA initiated to decompose to a-tricalcium phosphate (a-TCP) and tetracalcium phosphate (TTCP) phase at 1350°C. The surface dissolution of HA powders was accelerated by non-stoichiometric composition such as a-TCP, TTCP and the powders with smooth surface appeared to be dissolved on the edge showing fiber-like particles, followed by separation of the large particle to small one with the immersion time. The fiber-like particles consisted of new phases such as, carbonated-apatite (CHA) and octacalcium phosphate (OCP).

In this study, it was demonstrated how second phases with small amount, which are hardly detected by XRD analysis, affect grain boundary dissolution and related mechanical properties of HA. All HA disks sintered at 1200 oC for 2 h in air with under moisture protection were phase pure and had Ca/P molar ratio of 1.67. Following certain period of exposure to the distilled water, the surface dissolution initiated at grain boundaries and particle loosening, subsequently resulting in decrease in mechanical properties of HA. In order to understand the dissolution mechanism, grain boundary structure of HA was identified by transmission electron microscopy (TEM) and high resolution TEM observation. From the analysis, it was found that the non-stoichiometric phase as α-tricalcium phosphate (TCP) transformed from β-TCP was existed at grain boundaries and caused surface dissolution of HA. From the XRD analysis, it was found that (211) and (112) planes of hydroxyapatite were susceptible to dissolution, whereas (300) plane was relatively stable.

Obesity is often associated with irregular dietary habits and reduced physical activity. Regular exercise induces a metabolic response that includes increased expression of various cytokines, signaling proteins and hormones and reduced adipocyte size. In this study, mice performed a swimming exercise for 10 min/day, 5 days/week for 3 weeks. We then investigated the effect of this exercise regimen on inflammation induced by infection with drug-resistant Staphylococcus aureus strain 3089 (DRSA). In humans, DRSA causes dermatitis and pneumonitis. Similarly, DRSA induced inflammatory pneumonitis in both no-exercise (No-EX) and swim-trained (SW-EX) ICR mice. Regular exercise increased levels of the pro-inflammatory cytokines TNF-α and IL-1β and nitric oxide in both serum and whole lung tissue in SW-EX, as compared to No-EX control mice. Moreover, levels of the antimicrobial peptide cathelicidin were significantly increased in visceral adipose tissue and whole lung tissue in the SW-EX group and this was accompanied by a reduction in the size of visceral adipocytes. In addition, levels of the inflammation marker peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) were not increased in the lung tissue of SW-EX mice. These findings suggest that in these model mice, regular exercise strengthens immune system responses, potentially preventing or mitigating infectious disease.

Nicotinamide phosphoribosyltransferase (Nampt) catalyzes the rate-limiting step in the salvage pathway for nicotinamide adenine dinucleotide (NAD+) biosynthesis and thereby regulates the deacetylase activity of sirtuins. Here we show accommodative regulation of myocardial NAD+ by monocyte-derived extracellular Nampt (eNampt), which is essential for hemodynamic compensation to pressure overload. Although intracellular Nampt (iNampt) expression was decreased in pressure-overloaded hearts, myocardial NAD+ concentration and Sirt1 activity were preserved. In contrast, iNampt was up-regulated in spleen and monocytes and circulating eNampt protein and nicotinamide mononucleotide (NMN), a key precursor of NAD+, were significantly increased. Pharmacological inhibition of Nampt by FK866 or depletion of monocytes/macrophages by clodronate liposomes disrupted the homeostatic mechanism of myocardial NAD+ levels and NAD+-dependent Sirt1 activity, leading to susceptibility to cardiomyocyte apoptosis and cardiac decompensation in pressure-overloaded mice. These biochemical and hemodynamic defects were prevented by systemic administration of NMN. Our studies uncover a crucial role of monocyte-derived eNampt in myocardial adaptation to pressure overload and highlight a potential intervention controlling myocardial NAD+ against heart failure.

CA-MA is a hybrid antimicrobial peptide (AMP) derived from two naturally occurring AMPs, cecropin A and magainin 2. CA-MA shows strong antimicrobial activity against Gram-negative and Gram-positive bacteria but also exhibits cytotoxicity toward mammalian cells. Our objective was to identify CA-MA analogues with reduced cytotoxicity by systematic replacement of amino acids with positively charged R groups (His and Lys), aliphatic R groups (Leu), or polar R groups (Glu). Among the CA-MA analogues studied (CMA1 to -6), CMA3 showed the strongest antimicrobial activity, including against drug-resistant Escherichia coli and Pseudomonas aeruginosa strains isolated from hospital patients. CMA3 appeared to act by inducing pore formation (toroidal model) in the bacterial membrane. In cytotoxicity assays, CMA3 showed little cytotoxicity toward human red blood cells (hRBCs) or HaCaT cells. Additionally, no fluorescence was released from small or giant unilamellar vesicles exposed to 60 μM CMA3 for 80 s, whereas fluorescence was released within 35 s upon exposure to CA-MA. CMA3 also exerted strong lipopolysaccharide (LPS)-neutralizing activity in RAW 264.7 cells, and BALB/c mice exposed to LPS after infection by Escherichia coli showed improved survival after administration of one 0.5-mg/kg of body weight or 1-mg/kg dose of CMA3. Finally, in a mouse model of septic shock, CMA3 reduced the levels of proinflammatory factors, including both nitric oxide and white blood cells, and correspondingly reduced lung tissue damage. This study suggests that CMA3 is an antimicrobial/antiendotoxin peptide that could serve as the basis for the development of anti-inflammatory and/or antimicrobial agents with low cytotoxicity.

To improve the mechanical properties of Al2O3/ZrO2 composites, the homogeneous dispersion of ultra low size ZrO2 particles in Al2O3 ceramics have been controlled by partial dispersion of ZrO2 by chemical processes such as coprecipitation or polymeric precursor method(Pechini process). So nanosized Zr/Y hydroxide were coprecipitated or polymerized directly to the surfaces of commercial sub-micron size α-alumina powder(Sumitomo: AES-11(0.4 μm)) using ZrOCl2 /Y(NO3)3 solution. By the partial coprecipitation method, dispersion of relatively small sized ZrO2 in Al2O3/ZrO2 composites could be achieved at 1500~1600° C of sintering temperature. In case of the polyesterization of Zr/Y(NO3)3-citric acid solution in ethylene glycol directly to the commercial sub-micron size α-alumina powder, more homogeneous dispersion of relatively low sized ZrO2 in Al2O3/ZrO2 composites could be obtained at 1450~1600°C of sintering temperature range and their mechanical strength was more enhanced.

Polymer/layered silicate nanocomposities were prepared by in situ polymerization with microwave process. The influence of the amount of clay on the structure and thermal properties for the synthesized nanocomposites were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). It was found that the structure of nanocomposites, an intercalated/exfoliated structure, depended on the clay content.

For the homogeneous dispersion of particles in ceramics, Zr-precusors were mixed with oxide powders by chemical routes such as partial precipitation or partial polymerization of Zr-nitrate solutions. In case of the mechanical mixing of ultrafine and oxide powders, relatively homogeneous dispersion was difficult to achieve so that the particle size and distributions of were relatively inhomogeneous after sintering at high temperature. But when the Zr-Y-hydroxide were co-precipitated to ultrafine oxide powders followed by calcinations, homogeneous dispersion of nano-sized particles in composite ceramics were obtained. But because of the coalescence of dispersed particles, dispersed was grown up to more than 0.2 (200 nm) when sintered at the temperature of higher than But when the sintering temperature was kept to lower than by using nano-sized , the particle size of dispersed could be sustained below 0.1 . But the coalescence of dispersed between particles could not be avoided so that the mechanical properties were not enhanced contrary to the expectations. So Zr-polyester precursors were precipitated and coated to the surface of ultrafine powders by the polymerization of Ethylene Glycol with Citric Acid and Zirconium Nitrate. By this dispersion much more uniform dispersion of was achieved at of sintering temperature ranges. And due to especially discrete dispersion of between particles, their mechanical strength was more enhanced than mechanical mixing or hydroxide precipitation methods.

Background Parasympathetic drive is attenuated in heart failure, and resulting autonomic imbalance may increase the risk of sudden cardiac death. The anatomic site(s) and molecular mechanisms underlying this parasympathetic withdrawal are unknown. Methods and Results We examined the effects of pre- and post-ganglionic vagal nerve stimulation (VS) and acetylcholine (ACh) application on the heart rate of rats with right-sided congestive heart failure (CHF) induced by monocrotaline. Heart rate reduction in response to pre-ganglionic VS in CHF rats in vivo was significantly less than in controls. The suppression of spontaneous beating of isolated right atria including the whole sinoatrial (SA) node in response to post-ganglionic VS was significantly attenuated in CHF rats as well. In contrast, ACh application to the right atria resulted in a significantly larger suppression of spontaneous beating in CHF rats than controls. Proteins of neuronal nitric oxide synthase (nNOS) in the right atria were significantly decreased, whereas muscarinic (M2) receptor was significantly increased in CHF rats compared with controls. Conclusions Both pre-and post-ganglionic vagal nerve functions are diminished in CHF rats, whereas M2 receptor-mediated regulation of the SA node is upregulated. Downregulation of nNOS may be involved in this parasympathetic withdrawal. (Circ J 2005; 69: 493 - 499)

Refractory castable specimens were prepared using industrial white fused alumina as aggregates, chromium oxide green and ultrafine alumina powder as matrix materials, solid aluminum dihydrogen phosphate (Al(H2PO4)3) or liquid AlPO4 as binder materials. Effect of different binder additions on the propertiSubscript textes of high chromium oxide IGCC refractory castables, such as bulk density, apparent porosity, strength was evaluated and their microstructures were observed by SEM and mercury porosimetry.

The effect of starting phase of raw material on the microstructure and the fracture toughness of silicon carbide was investigated. The starting phase was adjusted by varying the mixed ratio of α-SiC and β-SiC powders, and they were hot pressed with sintering aids. From the microstructure, some elongated grains were found among equiaxial grains. The anisotropic grain growth was resulted from phase transformation of the β-SiC to the α-SiC with 4H polytype during sintering or heat treatment. Volume fraction, maximum length, and aspect ratio of elongated grains were the highest at 50 vol.% β-SiC in the starting SiC powder, which showed the highest fracture toughness about 6.0 MPa m 1/2.

Transplant of immature cardiomyocytes is recently attracting a great deal of interest as a new experimental strategy for the treatment of failing hearts. Full understanding of normal cardiomyogenesis is essential to make this regenerative therapy feasible. We analyzed the molecular and functional changes of Ca(2+) handling proteins during development of the mouse heart from early embryo at 9.5 days postcoitum (dpc) through adulthood. From the early to the late (18 dpc) embryonic stage, mRNAs estimated by the real time PCR for ryanodine receptor (type 2, RyR2), sarcoplasmic reticulum (SR) Ca(2+) pump (type 2, SERCA2) and phospholamban (PLB) increased by 3-15 fold in the values normalized to GAPDH mRNA, although Na(+)/Ca(2+) exchanger (type 1, NCX1) mRNA was unchanged. After birth, there was a further increase in the mRNAs for RyR2, SERCA2 and PLB by 18-33 fold, but a 50% decrease in NCX1 mRNA. The protein levels of RyR2, SERCA2, PLB and NCX1, which were normalized to total protein, showed qualitatively parallel developmental changes. L-type Ca(2+) channel currents (I(Ca-L)) were increased during the development (1.3-fold at 18 dpc, 2.2-fold at adult stage, vs. 9.5 dpc). At 9.5 dpc, the Ca(2+) transient was, unlike adulthood, unaffected by the SR blockers, ryanodine (5 microM) and thapsigargin (2 microM), and also by a blocker of the Ca(2+) entry via Na(+)/Ca(2+) exchanger, KB-R 7943 (1 microM). The Ca(2+) transient was abolished after application of nisoldipine (5 microM). These results indicate that activator Ca(2+) for contraction in the early embryonic stage depends almost entirely on I(Ca-L).

TiB 2 powders with submicrometer size were synthesized by mechanical alloying (MA) the mixture of elemental Ti and B powders in argon atmosphere using a steel jar. The effect of heat of formation and the atomic size factor on MA as well as the phase change during MA were investigated. The amorphization reaction, a common process during MA, had not been observed and the starting raw materials directly converted into final stable phase. When Zr of which atomic radius was larger than that of Ti was substituted for Ti, the alloying time was greatly reduced. On the contrary, substitution of Ta for Ti prolonged the alloying time because of the less negative heat of formation of TaB 2 than that of TiB 2 .

Enzymatic proteolysis by calpains, Ca(2+)-dependent intracellular cysteine proteases, has been implicated in pathological processes such as cellular degeneration or death. Here, we investigated the role of calpain activation in the hearts subjected to myocardial infarction. We produced myocardial infarction in Cast(-/-) mice deficient for calpastatin, the specific endogenous inhibitory protein for calpains, and Cast(+/+) mice. The activity of cardiac calpains in Cast(+/+) mice was not elevated within 1 day but showed a gradual elevation after 7 days following myocardial infarction, which was further pronounced in Cast(-/-) mice. Although the prevalence of cardiomyocyte death was indistinguishable between Cast(-/-) and Cast(+/+) mice, Cast(-/-) mice exhibited profound contractile dysfunction and chamber dilatation and showed a significant reduction in survival rate after myocardial infarction as compared with Cast(+/+) mice. Notably, immunofluorescence revealed that at 28 days after myocardial infarction, calpains were activated in cardiomyocytes exclusively at the border zone and that Cast(-/-) mice showed higher intensity and a broader extent of calpain activation at the border zone than Cast(+/+) mice. In the border zone of Cast(-/-) mice, pronounced activation of calpains was associated with a decrease in N-cadherin expression and up-regulation of molecular markers for cardiac hypertrophy and fibrosis. In cultured rat neonatal cardiomyocytes, calpain activation by treatment with ionomycin induced cleavage of N-cadherin and decreased expression levels of β-catenin and connexin 43, which was attenuated by calpain inhibitor. These results thus demonstrate that activation of calpains disassembles cell-cell adhesion at intercalated discs by degrading N-cadherin and thereby promotes left ventricular remodeling after myocardial infarction.

Silicon carbide ceramics with a powder mixture of sialon composition as a densification aid were prepared by hot pressing through a transient liquid phase, and the effects of sintering atmosphere and starting phases on the microstructural characteristics were investigated. The sintered SiC with the additive of a Y–α-sialon composition in argon showed high sintered density and grains with large aspect ratio. But sintered specimens in nitrogen yielded grains with low aspect ratio and small grain size, because of the retardation of phase transformation and grain growth. The SiC specimen prepared from the starting β–SiC powder with Y–α-sialon composition showed the highest fracture toughness of approximately 6.0 MPa m1/2.

Current interest in ferroelectric thin films stems from the numerous potential device applications for thin films of ferroelectric materials that utilize their unique dielectric, pyroelectric, electro-optic, acousto-optic, and piezo-electric properties. One of the major driving forces in this field is the potential application of ferroelectric thin films for both dynamic random access memory (DRAM) and non-volatile ferroelectric random access memory (FRAM). Ferroelectric lead zirconate titanate (PZT) thin films have gathered considerable attention because of their excellent ferroelectric properties, characterized by high remanent polarization (Pr) and low coercive field (Ec) [1, 2]. Patterning of PZT and electrode materials is one of the key process issues in the integration of these films into silicon devices because they do not easily react with etching gases, and do not form volatile species at low temperature [3, 4]. The ferroelectric film is exposed to high energy photon radiation and energetic ion bombardment during sputtering and reactive ion etching (RIE) of the top electrode for fabrication of integrated ferroelectric capacitors. The radiation and bombardment of the PZT film surface may be enough to modify the top surface layer and thus deform the hysteresis loop [5–7]. PZT films with lower Zr/Ti ratios are considered more attractive, because Ti-rich compositions tend to have lower crystallization temperatures and better squareness of the hysteresis loops [8]. Studies on the deformation in the hystersis loop of PZT films with various Zr/Ti ratios are important for the understanding of ferroelectric properties and the application of ferroelectric thin films. In this letter, we describe the deformation in the hysteresis loop of Pt/PZT/Pt thin film capacitors as a function of Zr/Ti ratios ranging from 60/40 to 20/80. We also explain the effect of top electrode annealing after patterning the Pt top electrode on the ferroelectric properties of Pt/PZT/Pt capacitors. The precursor materials used were lead acetate-3hydrate, zirconium propoxide, and titanium isopropoxide. The precursors with 16% excess lead were synthesized by distilling and reflux in butoxyethanol. The PZT films, 200 nm thick, were prepared using a sol-gel method on the substrate of Pt/Ti/SiO2/Si layers. The thicknesses of the Pt and Ti were 100 and 10 nm, respectively. Prior to spin coating the PZT film, the Pt electrode was annealed at 700 ◦C for 10 min to enhance the adhesion of Pt to SiO2 and the nucleation of the perovskite phase. Sequential spin coating and dry steps were followed by a crystallization for 30 min at 600 ◦C in air. A Pt top electrode with thickness of 80 nm was deposited by d.c. magnetron sputtering without heating the substrate and patterned by RIE using Ar gas for 50 min with resist as a mask. Plasma ashing was done using SF6/O2 gas for 5 min, therefore damage due to the ashing process was negligibly small compared to the RIE process. Details of sputtering and RIE conditions for the Pt electrode have been reported earlier [9]. The Pt/PZT/Pt capacitors were annealed up to 700 ◦C for 10 min after patterning. The polarization-electric field (P-E) hysteresis loop was measured using a modified Sawyer-Tower circuit using a 1 kHz sinusoidal voltage. The small signal capacitance-voltage (C-V ) curves were measured using an HP 4192A low frequency impedance analyzer with an electrode area of 2× 10−4 cm2. The C-V curves were obtained at a frequency of 20 kHz and 50 mV rms signal by sweeping from −5 to +5 V and back again. The structure of the PZT film was measured using X-ray diffraction pattern. All the PZT films were entirely perovskite phase with no detectable pyrochlore or amorphous scattering and had preferential (111) orientation. Subsequent processes such as Pt-sputtering, RIE and annealing did not change the X-ray diffraction pattern. Fig. 1 shows P-E hysteresis loops of PZT (20/80) films for different top electrode annealing temperatures. A large shift of the hysteresis loop along the electrical

Background Methanesulfonanilide derivatives, selective inhibitors of the rapidly activating component ( I Kr ) of the delayed rectifier potassium current ( I K ), prolong action potential duration (APD) of cardiac muscles with reverse frequency dependence, which limits their clinical use because of proarrhythmia. Vesnarinone, a quinolinone derivative developed as a cardiotonic agent, has complex pharmacological properties, but its clinical efficacy is explained in part by I K reduction. Therefore, we investigated the mode of I K block by vesnarinone. Methods and Results I K of the rabbit ventricular myocyte was activated by voltage-clamp steps applied from a holding potential to various depolarizing levels. The development of I K block at depolarization (+10 mV) and its recovery process at hyperpolarization (−75 mV) were compared between vesnarinone and E-4031. The I K block by vesnarinone (3 μmol/L) developed and recovered monoexponentially, with time constants of 361 ms (n=5) and 1.87 seconds (n=4), respectively. I K block by E-4031 (0.3 μmol/L) developed instantaneously, with no recovery from the block at hyperpolarization. The I K block by vesnarinone, estimated by I K tail after a train of depolarizing pulses (for 30 seconds at 0.2 to 2 Hz), was increased with increasing frequency (twofold at 2 from 0.2 Hz), but that by E-4031 was unchanged. In rabbit papillary muscles, vesnarinone (10 μmol/L) prolonged APD at stimulation frequencies >0.2 Hz, whereas E-4031 (0.3 μmol/L) prolonged that in a reverse frequency-dependent manner. Conclusions Vesnarinone may prolong the repolarization of human cardiac muscle without reverse frequency dependence, because I Kr is expressed in humans as well as in the rabbit. Thus, this drug may be a model for an ideal class III drug without the risk of proarrhythmia.

Microstructural changes in liquid-phase sintered α-silicon carbide due to the formation of a liquid reaction-layer and segregation of components of the liquid-phase near the surface were investigated. The outside surface layer was created by reaction of the packing powder and an eutectic oxide liquid-phase, and the liquid-phase components were segregated in the surface region of the specimen during sintering. The microstructural changes from the surface to the interior were a result of the changes in volume of the liquid-phase available for sintering as a function of depth from the specimen surface.

1. The effects of intracellular pH (pHi) were investigated in inside-out giant patches from Xenopus oocytes expressing the inward rectifier K+ channel IRK1. 2. After excising patches into Mg2(+)- and polyamine-free solution, a residual time-dependent inactivation of outward current during depolarizing voltage-clamp pulses persisted, reaching an apparent steady-state by 5 min. Raising pHi from 7.2 to 9.0 increased the inactivation rate of the outward current. 3. In the presence of intracellular Mg2+ or polyamines, however, pHi 9.0 either decreased or did not change the inactivation rate of outward current. 4. These results suggest that the inactivation of outward current remaining after > 5 min in Mg2(+)- and polyamine-free solution is not due to slow washout of these substances, but represents a third and probably intrinsic gating mechanism contributing to the inward rectifying property of IRK1. 5. The voltage dependence and kinetics of this gating mechanism were well described by a sequential two open- and one closed-state model in which the rate constants for transitions between the open states were voltage dependent, and those between the open and closed state were pH dependent. 6. In the absence of intracellular Mg2+ and polyamines, reduced pHi blocked inward and outward current through IRK1 channels in a voltage-independent manner without appreciably altering the kinetics. Half-maximal block occurred at pH 6.2-6.4 (Hill coefficient, 1.6). Block of IRK1 by intracellular protons may contribute to membrane depolarization in ischaemic tissue.

In a previous study, we synthesized a series of peptides containing simple sequence repeats, (KW)n–NH2 (n = 2,3,4 and 5) and determined their antimicrobial and hemolytic activities, as well as their mechanism of antimicrobial action. However, (KW)5 showed undesirable cytotoxicity against RBC cells. In order to identify the mechanisms behind the hemolytic and cytotoxic activities of (KW)5, we measured the ability of these peptides to induce aggregation of liposomes. In addition, their binding and permeation activities were assessed by Trp fluorescence, calcein leakage and circular dichrorism using artificial phospholipids that mimic eukaryotic liposomes, including phosphatidylcholine (PC), PC/sphingomyelin (SM) (2:1, w/w) and PC/cholesterol (CH) (2:1, w/w). Experiments confirmed that only (KW)5 induced aggregation of all liposomes, it formed much larger aggregates with PC:CH (2:1, w/w) than with PC or PC:SM (2:1, w/w). Longer peptide (KW)5, but not (KW)3 or (KW)4, strongly bound and partially inserted into PC:CH compared to PC or PC:SM (2:1, w/w). Calcein release experiments showed that (KW)5 induced calcein leakage from the eukaryotic membrane. Greater calcein leakage was induced by (KW)5 from PC:CH than from PC:SM (2:1, w/w) or PC, whereas (KW)4 did not induce calcein leakage from any of the liposomes. Circular dichroism measurements indicated that (KW)5 showed higher conformational transition compared to (KW)4 due to peptide-liposome interactions. Taken together, our results suggest that (KW)5 reasonably mediates the aggregation and permeabilization of eukaryotic membranes, which could in turn explain why (KW)5 displays efficient hemolytic activity.

HP (2-20) is a 19-aa, amphipathic, α-helical peptide with antimicrobial properties that was derived from the N-terminus of Helicobacter pylori ribosomal protein L1. We previously showed that increasing the net hydrophobicity of HP (2-20) by substituting Trp for Gln(17) and Asp(19) (Anal 3) increased the peptide's antimicrobial activity. In hydrophobic medium, Anal 3 forms an amphipathic structure consisting of an N-terminal random coil region (residues 2-5) and an extended helical region (residues 6-20). To investigate the structure-activity relationship of Anal 3, we substituted Pro for Glu(9) (Anal 3-Pro) and then examined the new peptide's three-dimensional structure, antimicrobial activity and mechanism of action. Anal 3-Pro had an α-helical structure in the presence of trifluoroethanol (TFE) and sodium dodecyl sulfate (SDS). NMR spectroscopic analysis of Anal 3-Pro's tertiary structure in SDS micelles confirmed that the kink potential introduced by Pro(10) was responsible for the helix distortion. We also found that Anal 3-Pro exhibited about 4 times greater antimicrobial activity than Anal 3. Fluorescence activated flow cytometry and confocal fluorescence microscopy showed that incorporating a Pro-hinge into Anal 3 markedly reduced its membrane permeability so that it accumulated in the cytoplasm without remaining in the cell membrane. To investigate the translocation mechanism, we assessed its ability to release of FITC-dextran. The result showed Anal 3-Pro created a pore

Microstructural variation between the surface and the inside of SiC ceramics sintered with an additive of yttrium aluminum garnet (YAG) was investigated. The variation was caused by a difference in the concentration of the oxide liquid phase during sintering. The gradual change in grain size and shape was found on the surface of which thickness was about 250μm. The grain growth and transformation of β- to α-SiC proceeded at a slower rate on the surface than inside the SiC ceramics. Grains on the surface were small and spherical, but those inside were large and platelike.

Hydroxyapatite has achieved significant application in orthopedic and dental implants due to its excellent biocompatibility. Sintered hydroxyapatites showed significant dissolution, however, after their immersion in water or simulated body fluid (SBF). This grain boundary dissolution, even in pure hydroxyapatites, resulted in grain separation at the surfaces, and finally, in fracture. In this study, hydroxyapatite ceramics containing apatite-wollastonite (AW) or calcium silicate (SG) glass ceramics as additives were prepared to prevent the dissolution. AW and SG glass ceramics were added at 0-7 wt% and powder-compacted uniaxially followed by firing at moisture conditions. The glass phase was incorporated into the hydroxyapatite to act as a sintering aid, followed by crystallization, to improve the mechanical properties without reducing the biocompatibility. As seen in the results of the dissolution test, a significant amount of damage was reduced even after more than 14 days. TEM and SEM showed no decomposition of HA to the secondary phase, and the fracture toughness increased, becoming even higher than that of the commercial hydroxyapatite.