Quantitative analysis of the number of antigens immobilized on a glass surface by AFM

To develop force measurements using an atomic force microscope (AFM) in a quantitative manner, it is necessary to estimate the number density of target molecules on a sample surface, and for this, the sensitivity of detection should be known. In this study, the AFM was used as a mechanical detector and an antigen and its antibody were used as a model to evaluate the sensitivity of detection. Antigens were immobilized on a glass surface and number density was estimated by monitoring optical absorbance due to product formation by the reaction of crosslinkers. The concentration of antigen was controlled by mixing control peptides. A microbead was used as a probe and antibodies were immobilized on the bead. AFM force measurements were then made for a range of number densities in the order of 10–10⁶ antigen molecules per square micrometer of surface and were compared to evaluate the sensitivity of detection. Our result establishes the reliability of estimating a number of molecules like receptors on the cell surface, and indicates that the AFM is useful as a mechanical detector with high sensitivity.     

Quantitative measurement of mRNA at different loci within an individual living cell

Asymmetric localizations of cellular proteins and mRNAs are important for cell functions such as division, differentiation and development. The localization of specific mRNA generates cell polarity by controlling the translation sites of specific proteins and thereby restricting their locations to appropriate cellular regions. We have previously reported a novel method based on atomic force microscopy (AFM) for examining gene expression in a single living cell without killing or destroying it. An AFM tip was inserted into a living cell to extract mRNAs, which were analyzed after multiplication by RT-PCR and quantitative PCR. By applying this method, in this study we performed quantitative measurement of mRNA at different loci within individual living cells.     

Development of radiochromic dosimeters based on polymer films with fluoran and divinyl phthalide dyes

Journal of Materials Science: Materials in Electronics - We fabricated polyvinyl chloride (PVC) and poly(methyl methacrylate) (PMMA) films containing NIR Black78, Black100 and Black400 for use as...     

Lymphatic absorption of oxidized cholesterol in rats

The absorption of cholesterol and of cholesterol oxidation products (oxidized cholesterols) was compared in lymph-cannulated rats. We found that the lymphatic absorption of an intragastrically administered, emulsified lipid meal containing 25 mg of cholesterol or 25 mg of oxidized cholesterols, within 24 h, was approximately 67 and 30%, respectively. The absorption rate of individual oxidized cholesterols differed considerably and was approximately 30% for 7α-hydroxycholesterol, 42% for 7β-hydroxycholesterol, 32% for 5β-epoxycholesterol, 28% for 5α-epoxycholesterol, 15% for cholestanetriol and 12% for 7-ketocholesterol. Moreover, cholesterol oxidation products delayed the absorption of oleic acid as triolein. Approximately 35 and 48% of cholesterol was recovered in chylomicrons (CM) and very low density lipoprotein (VLDL), respectively. In contrast, 54 and 40% of the oxidized cholesterols was recovered in CM and VLDL, respectively, although there was a significant difference in the distribution of individual oxidized cholesterols. The results of the present study indicate that oxidized cholesterols are absorbed to a lesser extent than is cholesterol, that they disturb fat absorption and that they distribute differently between lymphatic lipoproteins.     

Insights from ab initio molecular dynamics simulations for a multicomponent oxide glass

It remains a challenge to establish structural models of multicomponent oxide glass systems. In this study, we have investigated 68.3SiO₂–16.1B₂O₃–4.2Al₂O₃–11.4Na₂O glass and melt structures by ab initio molecular dynamics (AIMD) simulations. The atomic configurations obtained from AIMD simulations were validated against ¹⁷O solid‐state NMR spectrum under 24.0 T and neutron diffraction data, and excellent agreement was achieved. The bond lengths, angles, and coordination geometries were statistically analyzed for each atomic species. Here we particularly address the role of minor atomic species such as five‐coordinate Si (Si^V) and Al (Al^V). The Si^V–O bond lengths and O–Si^V–O angle distribution in the glass indicated 1.718 Å and three peaks at 90°, 120°, and 175°, which are assigned to a coordination geometry of the trigonal bipyramidal structure. Ring statistic analysis revealed that Si^V and Al^V were found to preferentially contribute to the formation of small ring sizes.     

Multiple evaluations of the removal of pollutants in road runoff by soil infiltration

Groundwater replenishment by infiltration of road runoff is expected to be a promising option for ensuring a sustainable urban water cycle. In this study, we performed a soil infiltration column test using artificial road runoff equivalent to approximately 11-12 years of rainfall to evaluate the removal of pollutants by using various chemical analyses and bioassay tests. These results indicated that soil infiltration treatment works effectively to remove most of the pollutants such as organic matter (chemical oxygen demand (CODMn) and dissolved organic carbon (DOC)), P species, polycyclic aromatic hydrocarbons (PAHs), numerous heavy metals and oestrogenic activities. Bioassay tests, including algal growth inhibition test, Microtox and mutagen formation potential (MFP) test, also revealed effective removal of toxicities by the soils. However, limited amounts of NO3, Mn, Ni, alkaline earth metals, perfluorooctane sulphonate (PFOS) and perfluorooctane sulphonamide (FOSA) were removed by the soils and they possibly reach the groundwater and cause contamination.     

重庆水晶郦城

水晶郦城环境自然、外观简洁、户型独特,是一个高层低密度的经典实例,是对高层创新性的完美演绎,代表了健康住宅的一个新方向。     

Reduced blood flow in abdominal viscera measured by Doppler ultrasound during one-legged knee extension

The redistribution of blood flow (BF) in the abdominal viscera during right-legged knee extension-flexion exercise at very low intensity [peak heart rate (HR), 76 beats/min] was examined by using Doppler ultrasound. While sitting, subjects performed a right-legged knee extension-flexion exercise every 6 s for 20 min. BF was measured in the upper abdominal aorta (Ao), right common femoral artery (RCFA), and left common femoral artery (LCFA). Visceral BF (BFVis) was determined by the equation [BFAo - (BFRCFA + BFLCFA)]. A comparison with the change in BF (DeltaBF) preexercise showed a greater increase in DeltaBFRCFA than in DeltaBFAo during exercise. This resulted in a reduction of BFVis to 56% of its preexercise value or a decrease in flow by 1,147 +/- 293 (+/-SE) ml/min at the peak workload. Oxygen consumption correlated positively with DeltaBFAo, DeltaBFRCFA, and DeltaBFLCFA but inversely with DeltaBFVis during exercise and recovery. Furthermore, BFVis (% of preexercise value) correlated inversely with both an increase in HR (r = -0.89), and percent peak oxygen consumption (r = -0.99). This study demonstrated that, even during very-low-intensity exercise (HR <90 beats/min), there was a significant shift in BF from the viscera to the exercising muscles.     

Atomic force microscopy of histological sections using a new electron beam etching method

In order to examine histological sections of the rat vomeronasal epithelium with the atomic force microscope (AFM), we developed an electron beam etching method that improves the resolution of AFM images. This method results in AFM images comparable to those obtained with the transmission electron microscope (TEM). Ultrathin tissue sections embedded in epoxy resin were observed before and after the treatment with electron beam radiation. Before electron beam treatment, epithelial structures such as the microvilli surface, dendritic processes, the supporting cell layers and the neuronal cell layers were all visible using the AFM. However, only a few subcellular structures could also be resolved. The AFM images were not as clear as those obtained with the TEM. After electron beam treatment, however, the resolution of AFM images was greatly improved. Most of the subcellular structures observed in TEM images, including the inner membrane of mitochondria, ciliary-structure precursor body, junctional complexes between the neurons and supporting cells, and individual microvilli were now visible in the AFM images. The electron beam treatment appeared to melt the embedding resin, bringing subcellular structures into high relief. The result of this study suggests that electron beam etching of histological samples may provide a new method for the study of subcellular structure using the AFM.     

Synthesis and properties of poly(phenylacetylene)s having dialkylamino groups

Summary Poly(phenylacetylene)s bearing dialkylamino groups were prepared by the polymerization of p-(N,N-dialkylamino)phenylacetylenes with [Rh(nbd)Cl]₂, and their electrochemical behavior was examined. Rh-catalyzed polymerization of p-(N,N-diethylamino)phenylacetylene (DEAPA) and p-(N,N-di-n-butylamino)phenylacetylene (DBAPA) in toluene in the presence of triethylamine gave good yields of the polymers (86 and 90%, respectively). Poly(DEAPA) was soluble in chloroform and dichloromethane, and poly(DBAPA) dissolved in various solvents such as toluene, THF, dichloromethane and chloroform. Poly(DEAPA) and poly(DBAPA) showed onset temperatures at 248 and 190°C, respectively, and absorptions around 300–400 nm. Electrochemical doping of the polymer films resulted in the shift of the absorptions to a region around 680 nm, which accompanied a color change of the polymer films from green ocher to deep blue. Received: 26 October 1998/Revised version: 6 November 1998/Accepted: 12 November 1998