Mapping and characterization of a sequential epitope on the rabies virus glycoprotein which is recognized by a neutralizing monoclonal antibody, RG719

We have established a murine hybridoma cell line RG719 which produces a rabies virus-neutralizing IgM-type monoclonal antibody (referred to as MAb RG719). Immunoblot analysis indicated that the antibody recognized a sequential epitope of G protein. Among four rabies virus strains tested, the antigenicity to MAb RG719 was absent from the Nishigahara strain, while the other three strains (HEP, ERA and CVS) reacted to the MAb. Studies with deletion mutants of the G protein indicated that the epitope was located in a middle region of the primary structure of G protein, ranging from position 242 to 300. By comparing the estimated amino acid sequence of the four strains, we found in this region two amino acids (at positions 263 and 291) which are common to three of those strains but are not shared by the Nishigahara strain. The site-directed point mutagenesis revealed that replacement of phenylalanine-263 by leucine destroyed the epitope of the HEP G protein, while the epitope was generated on the Nishigahara G protein whose leucine-263 was replaced by phenylalanine. These observations suggest that phenylalanine-263 is essential for constructing the epitope for MAb RG719. The synthetic 20-mer peptide produced by mimicking the amino acid sequence (ranging from amino acid positions 249 to 268) of the presumed epitope region was shown to bind specifically to MAb RG719 and also to raise the virus-neutralizing antibodies in rabbits. Vaccination with the HEP vaccine produced in Japan induced in humans and rabbits production of significant amounts of the antibodies which reacted with the 20-mer peptide.     

Smart optical receiver with automatic decision threshold settingand retiming phase alignment

The requirements for a smart optical receiver are discussed, and a design architecture suitable for introducing ICs based on automatic decision threshold setting and retiming phase alignment using digital/analog signal processing feedback is proposed. With the proposed architecture, the decision threshold level and the retiming clock phase of received data in the decision circuit are automatically adjusted to the optimum position. This obviates the need for decision threshold level and retiming clock phase adjustments in production testing, and it reduces the power penalty (receiver sensitivity degradation) on the received optical waveform variation. The power penalty caused by temperature and supply-voltage variations and aging in installation is also reduced. The performance of the proposed architecture is estimated; the power penalty as compared with the manual optimum adjustment is less than 0.4 dB, and the robustness to avalanche photodiode multiplication factor variations and crosstalk are improved     

Polymerization of propiolic acid and its derivatives catalysed by MoCl5

The polymerization of propiolic acid by group VI and VIII transition metal catalysts was investigated. MoCl₅, which was the most active among the catalysts examined, provided poly (propiolic acid) in over 80% yields under favourable conditions. The polymer formed was a water-soluble tawny powder, and its molecular weight was low ($\text{η}{}_{\mathrm{<mtext>sp</mtext>}}\text{C}\text{0.04–0.05}\text{dl g}{}^{\mathrm{?1}}$). The polymer structure,

was confirmed by the i.r. and ¹³C n.m.r. spectra and elemental composition. Some derivatives of propiolic acid (methyl propiolate, acetylenedicarboxylic acid, and phenylpropiolic acid) also produced coloured powdery polymers in the presence of MoCl₅-based catalysts.     

Isomorphic factorization, the Kronecker product and the line digraph

In this paper, we investigate isomorphic factorizations of the Kronecker product graphs. Using these relations, it is shown that (1) the Kronecker product of the d-out-regular digraph and the complete symmetric digraph is factorized into the line digraph, (2) the Kronecker product of the Kautz digraph and the de Bruijn digraph is factorized into the Kautz digraph, (3) the Kronecker product of binary generalized de Bruijn digraphs is factorized into the binary generalized de Bruijn digraph.     

Crack Propagation and Remaining Life Assessment of Coke Drums Due to Thermal Stresses

Coke drums are subjected to cyclic thermal stresses, thus their operational life is much shorter than other pressure equipment in oil refineries. It is known through surveys that one of major typical location of failure in coke drums is the shell-to-skirt junction. The main objective is to simulate crack propagation and to develop a remaining life assessment method for shell-to-skirt junction with crack. Operational temperatures and strains on a coke drum have been measured for 100 cycles. The selected operational temperatures will be applied as thermal boundary conditions in analyses. The crack propagation is then simulated to assess the remaining life.     

Atomic Motion in Low-Coverage Helium Films Adsorbed in FSM Nanochannels

⁴He and ³He films adsorbed in nanoporous silicates have shown similar heat capacities until the quantum-fluid layer appears at coverages over the first-layer completion n ₁. To obtain information on dynamics of adatoms at low coverages below the quantum fluid region, we have done pulsed-NMR experiment at 3.3 MHz for ³He films adsorbed in straight 2.4 nm nanochannels of FSM silicates. The spin-lattice and spin-spin relaxation times T ₁ and T ₂ observed at 0.54–7 K were well described by the two-dimensional version of the Bloembergen-Purcell-Pound model. At coverages 0.4–1.7n ₁, minima of T ₁, indicating the spin correlation time τ _c of 4.8×10^?8 sec, were observed at temperatures between 6 and 3 K. With decreasing temperature, changes in T ₁ and T ₂ become small below about 1.5 K, suggesting crossover from thermally-activated motion to quantum tunneling. In contrast to large variations below n ₁, both relaxation times above n ₁ are almost independent of coverage, which is likely to indicate that τ _c is determined by interlayer exchange of adatoms. Below n ₁, onsets for localization of adatoms were suggested by a decrease in T ₂.     

Osteoconduction of porous Ti metal enhanced by acid and heat treatments

Bone ingrowth into porous Ti metal is important for stable fixation of Ti metal implants to surrounding bone. However, without surface treatment this is limited to only a thin region of the outer surface of the Ti metal. In the present study, a porous Ti metal with a porosity of ~60 % and interpore connections of 70–200 micrometers in diameter was investigated in terms of its chemical and heat treatments, by implanting it into rabbit femur for periods varying from 3 to 12 weeks. The porous Ti metal subjected to heat treatment at 600 °C after H₂SO₄/HCl mixed acid treatment showed the largest bone ingrowth in comparison with those subjected to no treatment, only acid treatment, and only heat treatment even at an early stage after implantation, and remained as such even 12 weeks after implantation. Their bone ingrowths were well interpreted in terms of apatite-forming abilities of the Ti metals in body environment. Their apatite-forming abilities did not depend upon their surface roughness nor type of crystalline phase, but upon the positive surface charge.     

Encapsulation of hemoglobin in mesoporous silica (FSM)-enhanced thermal stability and resistance to denaturants

Hemoblogin (Hb), which is a typical oligomeric protein, was introduced into the pores of mesoporous silica (FSM: folded-sheet mesoporous material) that had a diameter of 7.5 nm. Soret CD spectra of Hb-FSM-7.5 conjugates showed a peak that was identical to that of free Hb. This suggests that Hb retained its highly ordered structure in the mesoporous silica. In addition, the UV-visible absorption spectrum showed that Hb had an increased resistance to heat denaturation in the silica. Even after heat treatment at 85 degrees C, Hb-FSM-7.5 retained its ligand-binding activity. The stability of Hb-FSM-7.5 was examined further by measuring its peroxidase-like activity. Encapsulation of Hb resulted in the retention of activity in the presence of high NaCl or Gdn-HCl levels. This suggests that encapsulation prevented dissociation and denaturing. Thus, it seems that the mesopores created a favorable environment for the oligomeric protein to perform its function, even under harsh conditions.     

Silica and titanium dioxide nanoparticles cause pregnancy complications in mice

The increasing use of nanomaterials has raised concerns about their potential risks to human health. Recent studies have shown that nanoparticles can cross the placenta barrier in pregnant mice and cause neurotoxicity in their offspring, but a more detailed understanding of the effects of nanoparticles on pregnant animals remains elusive. Here, we show that silica and titanium dioxide nanoparticles with diameters of 70 nm and 35 nm, respectively, can cause pregnancy complications when injected intravenously into pregnant mice. The silica and titanium dioxide nanoparticles were found in the placenta, fetal liver and fetal brain. Mice treated with these nanoparticles had smaller uteri and smaller fetuses than untreated controls. Fullerene molecules and larger (300 and 1,000 nm) silica particles did not induce these complications. These detrimental effects are linked to structural and functional abnormalities in the placenta on the maternal side, and are abolished when the surfaces of the silica nanoparticles are modified with carboxyl and amine groups.