Chain Growth Polycondensation as a Polymer Generating Reaction in the Synthesis of Oligo(p‐phenyleneethynylene)s with Low Polydispersity

Summary: The polycondensation of 1‐ethynyl‐2,5‐dihexyl‐4‐iodobenzene in the presence of 1‐ethynyl‐2,5‐dihexyl‐4‐(2‐phenylethynyl)benzene proceeds according to the mechanism of initiated chain growth polycondensation. It has allowed the synthesis of oligomers with a desired molecular weight and a narrow molecular weight distribution. The reasons for the side reaction leading to the formation of diyne compounds are revealed and the presumed mechanism is given. This opens prospects for the preparation of defectless poly(p‐phenyleneethynylene)s with required molecular weights and narrow molecular weight distributions.

     

Voronoi Polyhedra Analysis of Optimized Arterial Tree Models

Topological and metric properties of Voronoi polyhedra (VP) generated by the distal end points of terminal segments in arterial tree models grown by the method of constrained constructive optimization (CCO) are analyzed with the aim to characterize the spatial distribution of their supply sites relative to randomly distributed points as a reference model. The distributions of the number N _f of Voronoi cell faces, cell volume V, surface area S, area A of individual cell faces, and asphericity parameter of the CCO models are all significantly different from the ones of random points, whereas the distributions of V, S, and are also significantly different among CCO models optimized for minimum intravascular volume and minimum segment length (p < 0.0001). The distributions of N _f , V, and S of the CCO models are reasonably well approximated by two-parameter gamma distributions. We study scaling of intravascular blood volume and arterial cross-sectional area with the volume of supplied tissue, the latter being represented by the VP of the respective terminal segments. We observe scaling exponents from 1.20 ± 0.007 to 1.08 ± 0.005 for intravascular blood volume and 0.77 ± 0.01 for arterial cross-sectional area. Setting terminal flows proportional to the associated VP volumes during tree construction yields a relative dispersion of terminal flows of 37% and a coefficient of skewness of 1.12. © 2003 Biomedical Engineering Society. PAC2003: 8719Uv, 8710+e, 4720Ky, 0260Pn, 0230Oz     

Study of β‐casein denaturation by microparticle‐enhanced nephelometric immunoassay

Rabbit anti‐native bovine ß‐casein antiserum reacted with native ß‐casein and fragments f( 1–105/7) and f( 106–209) formed during ß‐casein proteolysis by plasmin. Agglutination of ß‐casein‐coated microparticles by anti‐native ß‐casein antiserum was weakly inhibited by ß‐casein f(1–105/7) and ß‐casein f( 106–209) (0·04 and 1·4%, respectively, compared with native ß‐casein). Immunoreactivity of these ß‐casein peptides in microparticle‐enhanced nephelometric immunoassay was more preserved in the whole ß‐casein than in its isolated fragments. The protein concentration producing 50% inhibition of the ß‐casein‐coated microparticle agglutination with anti‐native ß‐casein antiserum increased during ß‐casein denaturation. A microparticle‐enhanced nephelometric immunoassay, quantifying changes of this inhibiting protein concentration, permitted detection of alteration of the immunoreactivity of ß‐casein during its plasmin proteolysis and heat denaturation, providing an adequate test for the integrity of the whole molecule.     

Transcatheter arterial embolization of abnormal neovessels in a swine model of knee arthritis

BackgroundIn recent years, transcatheter arterial embolization (TAE) using imipenem/cilastatin (IPM/CS) has attracted attention as a treatment for relieving osteoarthritis (OA) pain. However, IPM/CS is not approved by Japanese medical insurance for use as an embolic material. Therefore, it is necessary to develop new embolic materials for TAE to relieve OA pain. The purpose of this study was to develop a swine model of knee arthritis and embolize abnormal neovessels (ANs) using two different embolic materials. We compared the embolic effects and tissue damage in knees.MethodsKnee arthritis was induced by intra-articular injection of papain into 12 knees in six female swine. The swine were divided into two groups of three swine each (six knees per group) for embolization of ANs in the knees with either IPM/CS or soluble gelatin sponge particles (SGSs). Three days after embolization, we compared the embolic effects using angiography and the tissue damage histopathologically.ResultsANs were observed in all 12 knees at 42 days after papain injection. The ANs disappeared and the patent arteries were recanalized 3 days after TAE in all 12 knees. Histopathological evaluation revealed synovitis changes, such as synovial thickening and inflammatory cell infiltration, in all 12 knees. There was no evidence of skin or muscle necrosis in either group. The appearance of ANs, recanalization of the parent arteries, and histopathological outcomes were not significantly different between the two groups.ConclusionSGSs were as safe as IPM/CS for TAE of ANs in this swine model of knee arthritis.     

人体腰椎活动节段应力分布的实验研究

本文采用三维光弹性实验方法观察了正常腰椎活动节段的应力分布。用精密浇铸,严格几何相似的光弹性环氧树脂腰椎和硅橡胶椎间盘模型进行三维光弹性实验,并观察腰椎的等应力差图和有效应力值分布。本实验观察到,腰椎椎体上下缘应力分布较均匀对称,其后缘应力大于前缘,后部结构应力较小。作者认为,三维光弹性实验方法具有直观性强,能有效和准确地确定腰椎的应力分布,对腰椎生物力学研究具有重要的实用价值。腰椎后缘应力大于前缘,使椎体后缘承载较大,将会增加腰椎间盘退变和损伤的机会,这可能是引起腰腿痛的重要因素。     

Colchicine-induced Inhibition of Fat Globule Development in Hepatocytes of Rats Injected with Ethionine

To examine the effect of colchicine on ethionine induced fatty liver, adult female rats were starved overnight and then injected i.p. with 1 g kg ethionine at 11th hour of fasting; then a half of the rats were also injected i.p. with 2.5 mg kg colchicine twice at 3 and 6 h after the single administration of ethionine. Similarly, fasted control rats were injected i.p. with vehicle alone at the above times. All of the rats were sacrificed after a 20 h fast, and the hepatocytes in periportal areas were observed ultra-structurally. In addition, total lipids in the liver tissue were extracted and determined biochemically. Although similar significant increases of triglyceride were observed in the liver tissue of all ethionine-injected rats, the hapatocytes in the group treated with both chemicals had fewer cytoplasmic fat globules (CFG) than those in the group treated with ethionine only. On the other hand, the diameters of markedly increased membrane-bound lipid particles (MLP) in the double treated group were distributed mainly in the range 0.2–0.4 μm, compared with those (0.1-0.2 μm) in the other groups. These findings indicate that colchicine inhibits the development of CFG in ethionine injured hapatocytes. Acta Pathol Jpn 39: 281∼288, 1989.     

Dendritic spines in the visual cortex of the mouse: Introduction to a mathematical model

Summary The spines of apical dendrites of the layer V pyramidal cells of the area striata in the mouse represent a sequence of post-synaptic structures receiving a variety of contacts from terminal fibers derived fundamentally from short axon cells and superficial pyramidal cells. The study of Golgi preparations of mice 180 days old shows the existence of the most complicated terminal structures over portions of apical dendrites at the levels of layers III and IV. Observations on young mice reveals the terminations of the specific afferent fibers on the dendrites of short axon cells. A mathematical model which defines the distribution of spines along the apical dendrites is introduced. The principal equation of the model has been adjusted from the data processing of microscope countings through a series of programs written for an IBM 7070. The equation defines satisfactorily the different distributions of dendritic spines in mice 10–180 days old raised in normal conditions and in complete darkness. The equation defines also the distribution of dendritic spines in the visual cortex of mice enucleated at birth on one side, and the distribution along the apical dendrites of various cortical areas of the hamster, cat and man. The number of dendritic spines increases with the age of the subject and their distribution varies significantly according to the values of the parameters of the model.     

Localization of class i histocompatibility molecule assembly by subfractionation of the early secretory pathway

Class I molecules of the major histocompatibility complex bind peptides derived from cytosolic proteins and display them on the cell surface. This function alerts cytotoxic T cells to the presence of intracellular pathogens. Class I molecule assembly requires the association of the heavy chain with β₂-microglobulin, accompanied by peptide loading via specific transporters. This study localizes where these assembly steps take place, using monoclonal antibodies recognizing class I molecules in different assembly states to analyze subcellular fractions of the early secretory pathway. The distribution of peptide-loaded class I molecules was more localized than the distribution of the total pool of class I molecules in the early secretory pathway. Loaded molecules colocalized with the peptide transporter, free heavy chains, and the chaperone calnexin in high density rough endoplasmic reticulum (RER) membranes. These data suggest that subunit assembly and peptide acquisition occur at the same intracellular site. Class I molecules also localized to less dense subfractions of the early secretory pathway, which contained comparatively less peptide-loaded molecules than the high density RER fractions, at steady state. Following a 15 °C temperature block, class I molecules accumulated in these less dense membrane fractions, indicating that these fractions represent the intermediate compartment where empty class I molecules are trapped in mutant cells. In the presence of cycloheximide, a pool of class I molecules recycling to the RER was detected, suggesting empty molecules recycle to acquire peptide.     

Distribution of genotypes and antibiotic resistance genes among invasive Streptococcus agalactiae (group B streptococcus) isolates from Australasian patients belonging to different age groups.

Serotype distribution and antibiotic resistance (AR) among group B streptococci (GBS) affect GBS disease prevention strategies, but vary among patient groups. A multiplex PCR-based reverse line blot (mPCR/RLB) hybridisation assay was used to compare the distributions of GBS serotypes, serotype III subtypes and AR-associated genes among 666 invasive isolates from 663 patients, divided into five age groups: infants, early-onset (EO; 0-6 days) and late-onset (LO; 7-90 days); children (aged 3 months to 14 years); women of childbearing age (WCBA; aged 15-45 years); and other adults (males aged >15 years; females aged >45 years). Serotypes Ia and V and serosubtype III-1 accounted for 60% of infections. Serosubtype III-2, which corresponds to a virulent clone belonging to sequence type (ST)17, was relatively uncommon overall (7%), but was associated strongly with LO infant infections, in which it was significantly more common than in adult infections (25/104 (24%) vs. 9/392 (2%), p <0.0001) or in EO infections (25/104 (24%) vs. 14/155 (9%), p <0.005). Erythromycin resistance genes were found in 8% of all isolates (ermB 3%, ermA 2.5% and mefA/E 2%), in 11-15% of isolates of serotypes II and V and subtype III-1, but in none of the isolates of serosubtype III-2 (III-2, 0/49 vs. all others, 54/618 (9%), p <0.04). In summary, the virulent serosubtype III-2 was associated strongly with LO infant GBS infection, but was less likely than other serotypes or serosubtype III-1 to carry AR genes.     

Propylene Polymerization Behavior of Fluorinated Bis(phenoxy‐imine) Ti Complexes with an MgCl2‐Based Compound (MgCl2‐Supported Ti‐Based Catalysts)

Summary: Fluorinated bis(phenoxy‐imine)Ti complexes 1 – 3 combined with MgCl₂/i‐Bu_nAl(OR)_3−n (MgCl₂‐supported catalysts) were able to polymerize propylene in a living fashion at room temperature to provide slightly to highly syndiotactic poly(propylenes) (PPs) with extremely narrow distributions of molecular weight. These represent the first examples of MAO‐ and borate‐free group 4 metal‐based living catalysts. The supported complexes 2 and 3 formed PPs with higher syndiotacticity and T_m's than the corresponding homogeneous MAO‐activation systems (e.g., 3 : rr 97%, T_m 155 °C; MAO activation: rr 93%, T_m 152 °C). The measured T_m of 155 °C represents the highest known T_m for syndiotactic PPs synthesized at room temperature.

Polymerization of propylene to poly(propylene) with supported Ti‐based catalysts.