Effect of annealing and hydrogen on properties of electrodeposited platinum electrode and lead-zirconate-titanate films for ferroelectric random access memory applications

The selection of capacitor electrode materials for the nonvolatile ferroelectric random access memory is one of the most important issues because capacitor electrical characteristics are strongly influenced by the electrode materials. The lower Pt electrode was electrodeposited on the Ti seed/Pt seed layer. Two different thicknesses of Ti seed layer (5 and 15 nm) were adopted, and lead-zirconate-titanate (PZT) was deposited on the electrodeposited Pt. The Pt crystal orientation with a 5 nm Ti seed layer is much better than that with a 15 nm Ti seed layer, and the deposited PZT shows much better crystal orientation. Due to better crystal orientation of the PZT layer in the case of a 5 nm Ti seed layer, a Pt/PZT/Pt capacitor well-saturated D-V hysteresis loop was obtained whereas little current was observed in the large electric field. With the 15 nm Ti seed layer, numerous several-mu m-sized voids formed on the lower Pt electrode surface. With the 5 nm Ti seed layer, fewer voids formed on the lower Pt electrode surface. Glow discharge spectrometry measurement with a 15 nm Ti seed layer shows much higher H intensity than that with a 5 nm Ti seed layer, and the H peak coincides with the Ti peak. The H existing in the Ti seed layer must have transmitted into the PZT layer and deteriorated the PZT crystal orientation. (c) 2005 The Electrochemical Society. </p

Effects of Orally Administered Lactoferrin and Lactoperoxidase-Containing Tablets on Clinical and Bacteriological Profiles in Chronic Periodontitis Patients

This study was undertaken to evaluate the effect of oral administration of lactoferrin (LF) and lactoperoxidase-(LPO-)containing tablet on periodontal condition. Seventy-two individuals with chronic periodontitis were randomly assigned to take either bovine LF and LPO-containing tablets (test group, n = 37) or control tablets (control group, n = 35) every day for 12 weeks. Periodontal parameters and levels of subgingival plaque bacteria, human and bovine LF, and endotoxin in gingival crevicular fluid (GCF) were evaluated at baseline, 1 week, 4 weeks, and 12 weeks. Significant differences were observed in GCF levels of bovine LF between the test and control groups throughout the study (P < .05). However, clinical and bacteriological parameter values proved comparable between the two groups at 1 week to 12 weeks. Therefore, the effect of oral administration of LF and LPO-containing tablets might be weak on periodontal and bacteriological profile in this study

Effects of endoluminal stent-grafts on acute aortic dissection in dogs.

Acute aortic dissection is a life-threatening condition, and may be treated with aggressive hypotensive drug therapy, but emergency surgery is often necessary. We evaluated the effectiveness of stent-grafts for the treatment of acute aortic dissection. Aortic dissection was surgically created in the descending thoracic aorta in 20 adult mongrel dogs. A stent-graft was inserted in the entry position. The tested animals were divided into 4 groups based on re-entry type and blood pressure alteration rate (AR) after acute aortic dissection. After insertion of the stent, the following results were observed: a) AR improved; b) proximal descending aorta and superior mesenteric arterial flows increased; c) cardiac function improved; and d) the dissecting aortic diameter decreased in the presence of pressure gradient group. From these results, insertion of a stent-graft to treat acute aortic dissection was judged to be effective.</p

An RNA aptamer with potent affinity for a toxic dimer of amyloid β42 has potential utility for histochemical studies of Alzheimer's disease

Oligomers of β-amyloid 42 (Aβ42), rather than fibrils, drive the pathogenesis of Alzheimer's disease (AD). In particular, toxic oligomeric species called protofibrils (PFs) have attracted significant attention. Herein, we report RNA aptamers with higher affinity toward PFs derived from a toxic Aβ42 dimer than toward fibrils produced from WT Aβ42 or from a toxic, conformationally constrained Aβ42 variant, E22P–Aβ42. We obtained these RNA aptamers by using the preincubated dimer model of E22P–Aβ42, which dimerized via a linker located at Val-40, as the target of in vitro selection. This dimer formed PFs during incubation. Several physicochemical characteristics of an identified aptamer, E22P–AbD43, suggested that preferential affinity of this aptamer toward PFs is due to its higher affinity for the toxic dimer unit (KD = 20 ± 6.0 nm) of Aβ42 than for less-toxic Aβ40 aggregates. Comparison of CD data from the full-length and random regions of E22P–AbD43 suggested that the preferential binding of E22P–AbD43 toward the dimer might be related to the formation of a G-quadruplex structure. E22P–AbD43 significantly inhibited the nucleation phase of the dimer and its associated neurotoxicity in SH-SY5Y human neuroblastoma cells. Of note, E22P–AbD43 also significantly protected against the neurotoxicity of WT Aβ42 and E22P–Aβ42. Furthermore, in an AD mouse model, E22P–AbD43 preferentially recognized diffuse aggregates, which likely originated from PFs or higher-order oligomers with curvilinear structures, compared with senile plaques formed from fibrils. We conclude that the E22P–AbD43 aptamer is a promising research and diagnostic tool for further studies of AD etiology

Phospholipase C Produced by Clostridium botulinum Types C and D:Comparison of Gene, Enzymatic, and Biological Activities with Those of Clostridium perfringens Alpha-toxin

Clostridium botulinum type C and D strains recently have been found to produce PLC on egg yolk agar plates. To characterize the gene, enzymatic and biological activities of C. botulinum PLCs (Cb-PLCs), the cb-plc genes from 8 strains were sequenced, and 1 representative gene was cloned and expressed as a recombinant protein. The enzymatic and hemolytic activities of the recombinant Cb-PLC were measured and compared with those of the Clostridium perfringens alpha-toxin. Each of the eight cb-plc genes encoded a 399 amino acid residue protein preceded by a 27 residue signal peptide. The protein consists of 2 domains, the N- and C-domains, and the overall amino acid sequence identity between Cb-PLC and alpha-toxin was greater than 50%, suggesting that Cb-PLC is homologous to the alpha-toxin. The key residues in the N-domain were conserved, whereas those in the C-domain which are important in membrane interaction were different than in the alpha-toxin. As expected, Cb-PLC could hydrolyze egg yolk phospholipid, p-nitrophenylphosphorylcholine, and sphingomyelin, and also exhibited hemolytic activity;however, its activities were about 4- to over 200-fold lower than those of alpha-toxin. Although Cb-PLC showed weak enzymatic and biological activities, it is speculated that Cb-PLC might play a role in the pathogenicity of botulism or for bacterial survival

Specific Egg Yolk Immunoglobulin as a New Preventive Approach for Shiga-Toxin-Mediated Diseases

Shiga toxins (Stxs) are involved in the development of severe systemic complications associated with enterohemorrhagic Escherichia coli (EHEC) infection. Various neutralizing agents against Stxs are under investigation for management of EHEC infection. In this study, we immunized chickens with formalin-inactivated Stx-1 or Stx-2, and obtained immunoglobulin Y (IgY) from the egg yolk. Anti-Stx-1 IgY and anti-Stx-2 IgY recognized the corresponding Stx A subunit and polymeric but not monomeric B subunit. Anti-Stx-1 IgY and anti-Stx-2 IgY suppressed the cytotoxicity of Stx-1 and Stx-2 to HeLa 229 cells, without cross-suppressive activity. The suppressive activity of these IgY was abrogated by pre-incubation with the corresponding recombinant B subunit, which suggests that the antibodies directed to the polymeric B subunits were predominantly involved in the suppression. In vivo, the intraperitoneal or intravenous administration of these IgY rescued mice from death caused by intraperitoneal injection of the corresponding toxin at a lethal dose. Moreover, oral administration of anti-Stx-2 IgY reduced the mortality of mice infected intestinally with EHEC O157:H7. Our results therefore suggest that anti-Stx IgY antibodies may be considered as preventive agents for Stx-mediated diseases in EHEC infection

TGF-β receptor kinase inhibitor enhances growth and integrity of embryonic stem cell–derived endothelial cells

Recent findings have shown that embryonic vascular progenitor cells are capable of differentiating into mural and endothelial cells. However, the molecular mechanisms that regulate their differentiation, proliferation, and endothelial sheet formation remain to be elucidated. Here, we show that members of the transforming growth factor (TGF)-β superfamily play important roles during differentiation of vascular progenitor cells derived from mouse embryonic stem cells (ESCs) and from 8.5–days postcoitum embryos. TGF-β and activin inhibited proliferation and sheet formation of endothelial cells. Interestingly, SB-431542, a synthetic molecule that inhibits the kinases of receptors for TGF-β and activin, facilitated proliferation and sheet formation of ESC-derived endothelial cells. Moreover, SB-431542 up-regulated the expression of claudin-5, an endothelial specific component of tight junctions. These results suggest that endogenous TGF-β/activin signals play important roles in regulating vascular growth and permeability