Oligopeptide-mediated acceleration of amyloid fibril formation of amyloid beta(Abeta) and alpha-synuclein fragment peptide (NAC).

The effects of oligopeptides on the secondary structures of Abeta and NAC, a fragment of alpha-synuclein protein, were studied by circular dichroism (CD) spectra. The effects of oligopeptides on the amyloid fibril formation were also studied by fluorescence spectra due to thioflavine-T. The oligopeptides were composed of a fragment of Abeta or NAC and were interposed by acidic or basic amino acid residues. The peptide, Ac-ELVFFAKK-NH2, which involved a fragment Leu-Val-Phe-Phe-Ala at Abeta(17-21), had no effect on the secondary structures of Abeta(1-28) in 60% or 90% trifluoroethanol (TFE) solutions at both pH 3.2 and pH 7.2. However, it showed pronounced effects on the secondary structure of Abeta(1-28) at pH 5.4. The Ac-ELVFFAKK-NH2 reduced the alpha-helical content, while it increased the beta-sheet content of Abeta(1-28). In phosphate buffer solutions at pH 7.0, Ac-ELVFFAKK-NH2 had little effect on the secondary structures of Abeta(1-28). However, it accelerated amyloid fibril formation when monitored by fluorescence spectra due to thioflavine-T. On the other hand, LPFFD, a peptide known as a beta-sheet breaker, caused neither an appreciable extent of change in the secondary structure nor amyloid fibril formation in the same buffer solution. The peptide, Ac-ETVK-NH2, which involved a fragment Thr-Val at NAC(21-22), had no effect on the secondary structure of NAC in 90% TFE and in isotonic phosphate buffer. However, Ac-ETVK-NH2 in water with small amounts of NaN3 and hexafluoroisopropanol greatly increased the beta-sheet content of NAC after standing the solution for more than 1 week. Interestingly, in this solution. Ac-ETVK-NH2, accelerated the fibril formation of NAC. It was concluded that an oligopeptide that involves a fragment of amyloidogenic proteins could be a trigger for the formation of amyloid plaques of the proteins even when it had little effect on the secondary structures of the proteins as monitored by CD spectra for a short incubation time.     

The linkage between β1 integrin and the actin cytoskeleton is differentially regulated by tyrosine and serine/threonine phosphorylation of β1 integrin in normal and cancerous human breast cells

Background  

Structural requirements for the β1 integrin functions in cell adhesion, spreading and signaling have been well documented mainly for fibroblasts. In this study, we examined the reason for the reduced surface expression of β1 integrin in human breast cancer MCF-7 cells compared to normal human breast epithelial (HBE) cells, both of which adhered to collagen type IV.     

The Golgi apparatus of goblet cells in the mouse descending colon: three-dimensional visualization using a confocal laser scanning microscope

The three-dimensional structure of the Golgi apparatus was studied in goblet cells in lectin-stained sections of the mouse descending colon by using a confocal laser scanning microscope. In the lower part of the crypt, the Golgi apparatus formed a dome- or globe-like structure in the supranuclear region. The wall of the dome had some holes, one of which usually faced toward the nucleus and others toward the apical cytoplasm. Mucous granules seemed to be initially released into the interior of the dome and transported toward the apical cytoplasm through the holes. In the upper part of the crypt, on the other hand, the Golgi apparatus formed a cup- or funnel-like structure with a larger opening toward the cell apex and a smaller opening toward the nucleus. A large mass of mucous granules occupied the inside of the cup to the apical cytoplasm. It is thought that the accumulation of mucous granules enlarges holes at the ceiling of the dome to form a large opening, which makes the configuration of the Golgi apparatus cup-shaped.     

A fatal case of fungal endocarditis of the tricuspid valve associated with long-term venous catheterization and treatment with antibiotics in a patient with a history of alcohol abuse

We report a fatal case of fungal (candidal) endocarditis of the tricuspid valve with clinico-pathologically interesting findings following and associated with candidal pneumonia during long-term central venous catheterization (CVC) for intravenous therapy and long-term treatment with antibiotics for bacterial and fungal infection in a patient with a history of alcohol abuse. We review the literature on fungal cardiac infection related to long-term catheterization and alcohol abuse, and discuss the pathogenesis. This revised version was published online in June 2006 with corrections to the Cover Date.     

Molecular and crystal structure of hexaaquamanganese(II) bis{bis(N-salicylideneglycinato)manganate(III)} dihydrate, [MnII(H2O)6][MnIII(Sal = Gly)2]2·2H2O

The crystal structure of hexaaquamanganese(II) bis{bis(N-salicylideneglycinato)manganate(III)} dihydrate has been determined by X-ray analysis. The complex crystallizes in the monoclinic space group I2|a, with unit-cell dimensions a = 37.431(5), b = 12.100(1), c = 9.448(1) Å, β = 92.31(1)°. The structure was deduced by the direct method and refined by the block-diagonal least-squares technique to a final R value of 0.062 for 3904 observed reflections. The Mn(II) is octahedrally ligated by six water molecules, while Mn(III) is octahedrally chelated by two salicylideneglycinate ligands, of which one is nearly planar and the other considerably bent.It was discovered that the crystal is, as a whole, of a ‘sandwich’ structure made of one central sheet containing hexaaquamanganese(II)'s and the water molecules of crystallization, and two outside sheets containing bis(N-salicylideneglycinato)manganate(III)'s.     

Highly efficient supramolecular photocatalysts for CO2 reduction using visible light.

We report the most efficient homogeneous photocatalyst yet for CO(2) reduction using a wide range of visible-light wavelength. We synthesized new Ru(II)-Re(I) binuclear complexes with 1,3-bis(4'-methyl-[2,2']bipyridinyl-4-yl)-propan-2-ol (bpyC3bpy) as a bridge ligand, specifically [Ru-ReP(OEt)(3)](3+) and [Ru-Repy](3+) where a P(OEt)(3) or pyridine ligand coordinates on the Re site. Their photocatalytic activities were compared with [Ru-ReCl](2+), which has a Cl(-) ligand on the Re site and has recently been reported as a much better photocatalyst (Phi = 0.12, TN(CO) = 160) than a 1:1 mixed system of the corresponding Ru(II) and Re(I) mononuclear complexes. The best photocatalyst was [Ru-ReP(OEt)(3)](3+), for which Phi = 0.21 and TN(CO) = 232. A mechanistic study clearly showed that [Ru-ReP(OEt)(3)](3+) is rapidly converted into the solvento complex [Ru-ReSol](3+), (Sol = DMF or TEOA) which is the actual photocatalyst. Although similar rapid ligand substitution occurs with other supramolecules, the pyridine and Cl(-) anions accelerate the decomposition of the supramolecular photocatalysts.     

Ultrastructural characterization of interstitial cells of Cajal in the rat small intestine using control and Ws/Ws mutant rats

Interstitial cells in the myenteric plexus and the deep muscular plexus of the small intestine of the c-kit mutant rats (Ws/Ws) and their normal siblings (+/+) were studied. c-Kit immunoreactivity was detected in two regions corresponding to the myenteric plexus and the deep muscular plexus in the jejunum of +/+ rats, while no immunoreactivity was detected in Ws/Ws rats. Using electron microscopy, two types of gap junction-forming interstitial cells were found in association with the myenteric plexus in +/+ rats: one type characterized by a typical fibroblastic ultrastructure, and the other characterized by numerous mitochondria and less electron-dense cytoplasm. Since the latter were greatly reduced in Ws/Ws rats, it was suggested that these cells correspond to c-kit-expressing cells, i.e. interstitial cells of Cajal in the myenteric plexus region. In contrast, two types of interstitial cells in the region of the deep muscular plexus were observed with no difference between +/+ and Ws/Ws rats. Probable interstitial cells of Cajal in this region were characterized by a basal lamina and numerous caveolae as well as large gap junctions that interconnect with each other and with the smooth muscle cells. We concluded that interstitial cells of Cajal in the rat intestine are heterogeneous in ultrastructure, c-kit dependency in the cell maturation, and functional role.     

Homogeneity of Borrelia japonica and heterogeneity of Borrelia afzelii and 'Borrelia tanukii' isolated in Japan, determined from ospC gene sequences

Borrelia afzelii, B. japonica, and `B. tanukii' isolated from various sources and geographical origins in Japan were characterized by restriction fragment length polymorphism (RFLP) analysis and sequencing analysis of the outer surface protein C (OspC) amplicon. B. afzelii and `B. tanukii' generated variable RFLP patterns and differences in ospC gene sequence were confirmed. In contrast, 26 isolates of B. japonica generated one OspC RFLP type, and sequence similarity between B. japonica ranged from 96.4 to 99.7%. These finding suggests that B. japonica is unique in comparison with other members of B. burgdorferi sensu lato species with respect to homogeneity of the ospC gene.