Three-dimensional architecture of ribosomal DNA within barley nucleoli revealed with electron microscopy

To elucidate the topological positioning of ribosomal RNA genes (rDNA) and nucleolar structure in three dimensions, we examined the localization of rDNA using in situ hybridization (ISH) analysis by scanning electron microscopy (SEM). The rDNA genes within the three-dimensional architecture of nucleoli were detected on chromatin fibers that connect a thick strand-like structure and a protrusion of rDNA into the inner nuclear hole where the nucleolus is formed. This novel use of ISH together with SEM is useful for the analysis of nucleolar structure in detail. Furthermore, rDNA was detected at the periphery of the fibrillar centers (FCs) of the nucleolus using immuno-gold labeling together with transmission electron microscopy (TEM). In situ hybridization with TEM confirmed that rDNA is naked and thus active in the FCs of nucleoli; ISH with SEM confirmed that rDNA is not covered with ribonucleo proteins at the protruding point and is thus inactive. We also show that the distribution pattern of FCs differs from sample to sample. These results indicate that rDNA is transcribed dynamically in a time- and region-specific manner over the course of the cell cycle.     

Inter-laboratory validation studies of analytical method for determination of chloramphenicol in royal jelly

Inter-laboratory validation studies were conducted in 6 laboratories to validate the analytical method for determination of chloramphenicol in royal jelly. Chloramphenicol spiked at the levels of 0.1 and 0.5 ppm was analyzed. Mean recoveries were 89 and 89%, reproducibility relative standard deviations (RSD(R)) were 10.5 and 6.8%, HORRAT(R) values were 0.5 and 0.4. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 89 and 84%, RSD(R) were 9.8 and 12.3%, and HORRAT(R) values were 0.5 and 0.7. The determination limit was 0.05 ppm. These results show that this method has good performance.     

Design of transmission line filters and matching circuits using genetic algorithms

A method for designing microwave filters and impedance matching circuits using transmission lines is presented. Transmission line filters with shunt‐connected open circuit stubs and continuously varying transmission line matching circuits are described in detail. The proposed method is based on genetic algorithms and can effectively be applied to various filter and matching circuit design problems without increasing theoretical and computational complexity. Design examples are provided, and the proposed method is demonstrated to be effective in designing transmission line filters and matching circuits. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Rapid and improved determination of furan in baby foods and infant formulas by headspace GC/MS

Furan is a 5-membered ring compound with high volatility. The U.S. Food and Drug Administration (FDA) has recently published a report on the occurrence of furan in a large number of thermally processed foods. However, the FDA's analytical method, using standard curve addition, is not suitable for high-throughput routine laboratory operations. We developed a rapid and improved method for determination of furan in foods by headspace GC/MS. Quantification was achieved by using an internal standard of d4-furan and an external calibration curve of furan normalized against the internal standard. The incubation temperature for equilibration was set at 60 degrees C to avoid the formation of furan during analysis. The levels of furan in baby foods and infant formulas were determined with this method. Validation data showed good precision and accuracy. The LOD and LOQ were 0.2-0.5 ng/g and 0.5-2 ng/g for various food matrixes, respectively. The level of furan detected was in the range of 1.4 to 90 ng/g in baby foods and in the range of non-detectable to 36 ng/g in infant formulas.     

Charge-carrier injection into pentacene thin film formed on Si(111) probed by STM spectroscopy

The injection of charge carriers into a pentacene thin film formed on a Si substrate was investigated by scanning tunneling microscopy (STM). Tip height versus bias voltage (z-V) spectroscopy reveals the characteristic charge transport properties of the molecular film, i.e., the conductivity and the threshold energy of charge injection. The abrupt descent of the tip into the film owing to the transition of film conductance, which depends on the degree of charge carrier injection, was observed for crystallized pentacene thin films. The lower film conductance at around zero bias voltage is still higher than that of a vacuum. This indicates that the carrier injection barrier between the pentacene and the semiconducting substrate is extremely low. The convergence of the carrier injection endpoints into a narrow range of electric-field intensity implies that the main factor contributing to barrier formation and collapse is not the bias voltage but the electric field.     

Porphyromonas gingivalis Lipopolysaccharides Promote Proliferation and Migration of Human Vascular Smooth Muscle Cells through the MAPK/TLR4 Pathway

Atherosclerosis is a major cause of mortality worldwide. The initial change in atherosclerosis is intimal thickening due to muscle cell proliferation and migration. A correlation has been observed between periodontal disease and atherosclerosis. Here, we investigated the proliferation and migration of human aortic smooth muscle cells (HASMCs) using Porphyromonas gingivalis-derived LPS (Pg-LPS). To elucidate intracellular signaling, toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) of HASMCs were knocked down, and the role of these molecules in Pg-LPS-stimulated proliferation and migration was examined. The role of mitogen-activated protein kinase (MAPK) in HASMC proliferation and migration was further elucidated by MAPK inhibition. Pg-LPS stimulation increased the proliferation and migration of HASMCs and activated the TLR4/MyD88 pathway. TLR4 knockdown inhibited Pg-LPS stimulated HASMCs proliferation and migration. Pg-LPS stimulation led to the phosphorylation of P38 MAPK, JNK, and ERK, and MyD88 knockdown inhibited the phosphorylation of P38 MAPK and JNK but not ERK. P38 MAPK and SAPK/JNK inhibition did not suppress the proliferation of HASMCs upon Pg-LPS stimulation, but ERK inhibition significantly inhibited proliferation. SAPK/JNK and ERK inhibition suppressed Pg-LPS-stimulated migration of HASMCs. In conclusion, our findings suggest that Pg-LPS may promote atherosclerosis via the activation of MAPK through TLR4.     

Determination of genotoxic phenylhydrazine agaritine in mushrooms using liquid chromatography-electrospray ionization tandem mass spectrometry

A new method with good sensitivity and specificity for detecting and quantifying genotoxic hydrazines, agaritine and 4-(hydroxymethyl)phenylhydrazine (HMPH), was developed using liquid chromatography-electrospray tandem mass spectrometry (MS). Synthetic agaritine and HMPH were structurally assigned by ¹H-, ¹³C- and two-dimensional nuclear magnetic resonance (NMR) analysis (HMBC and HMQC), high-resolution fast-atom bombardment (HR-FAB) MS and time of flight (TOF) MS. The polar molecule agaritine was separated on an ODS column using 0.01% AcOH-MeOH (99:1, v/v) as an eluent with a simple solid-phase extraction cleanup. There were no interference peaks for any of the mushrooms. Agaricus spp. contained 1247 and 2017 µg g^-1 agaritine. Other species of mushroom had no agaritine. Recoveries of agaritine from spiked mushroom samples were 60.3-114%. Intra-day precision values were 5.5 and 4.2%, and the inter-day precision values were acceptable (15.0 and 23.0%), as agaritine is unstable. The limit of quantification was 0.003 µg g^-1. Even a trace amount of agaritine in mushrooms can, therefore, be determined using this method. We also directly analysed HMPH, an active free hydrazine form of genotoxic agaritine, and obtained direct evidence of its absence from mushrooms. A precursor ion scan confirmed that agaritine derivatives, which could exert similar toxicity, were absent. The results indicate that this specific and sensitive analytical method for detecting and quantifying agaritine and its derivatives could help evaluate the risk of mushroom hydrazines to humans.     

The congruent melting composition of strontium barium niobate

The congruent melting composition of strontium barium niobate has been investigated over the ternary composition region by DTA, X-ray fluorescence, Curie temperature and lattice parameter measurements. The composition of congruent melt was found to be close tox=0.61,y=0.4993 for the formula (Sr _x Ba_1–x O)_1–y . (Nb₂O₅) _y . Striation-free single crystals are grown from the melt with this composition. The conceivable reasons for the discrepancy between the results of this work and the previous data are briefly discussed.     

An investigation of flow patterns and hardness distributions using different anvil alignments in high-pressure torsion

A super duplex stainless steel was selected as a model material to evaluate the origins of unusual double-swirl flow patterns that have been reported on the upper surfaces of discs processed by high-pressure torsion (HPT). The experiments were conducted by making changes in the anvil alignment prior to HPT processing. Experiments were conducted under two different conditions: using essentially a perfect anvil alignment and with an initial anvil misalignment of 100 μm. The experimental results show that no double swirls are visible on the surfaces of discs processed under conditions of perfect anvil alignment but double swirls become visible when processing with a misalignment of 100 μm. The presence of double swirls also affects the measured hardness distributions, and for a misalignment of 100 μm the hardness distribution along a diameter may be non-symmetric with respect to the centre of the disc.     

The significance of grain boundary sliding in the superplastic Zn–22 % Al alloy processed by ECAP

A Zn–22 % Al eutectoid alloy was processed by equal-channel angular pressing (ECAP) to reduce the grain size to ~0.8 μm. Tensile testing at 473 K showed superplastic characteristics with a maximum elongation of ~2230 % at a strain rate of 1.0 × 10^?2 s^?1. The significance of grain boundary sliding (GBS) was evaluated by measuring sliding offsets at adjacent grains from the displacements of surface marker lines in samples pulled to elongations of 30 % at a series of different strain rates. The highest sliding contribution was recorded under testing conditions corresponding to the maximum superplastic ductility. There were relatively large offsets at the Zn–Zn and Zn–Al interfaces, but smaller offsets at the Al–Al interfaces. Analysis shows the results are affected by the presence of agglomerates of similar grains which are present after ECAP processing and specifically by the increased fraction of Al–Al boundaries. The experimental results are in excellent agreement with the predictions of a deformation mechanism map depicting the flow behavior in the Zn–22 % Al alloy, and the results confirm the importance of GBS as the dominant mechanism of flow in superplasticity after processing by ECAP.