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1.
Plasma (P)-component of amyloid (AP or SAP), while not an integral part of the amyloid fibril, has been considered to be intimately associated with virtually every different type of amyloid. In the present study, we evaluated the distribution of AP in the organs frequently involved in two forms of human systemic amyloidosis (AA and AF) and in mouse AA amyloidosis, by use of immunohistochemistry with anti-AP. Although the amyloid deposits generally showed moderate reactions with anti-AP, they were not always clearly distinguished from the surrounding non-amyloid tissue elements which often stained as well. The basement membrane often showed even stronger reaction to anti-AP than the adjacent amyloid deposits, and liver sections demonstrated such a high overall reaction to anti-AP that the anti-AP reaction on the amyloid deposits was often obscurred. The present results suggest that the binding between AP and the amyloid fibril may not be monospecific, that AP by this technique occurs rather widely throughout the body, and therefore that anti-AP may not be considered as specific a marker for amyloid deposits in immunohistochemical and perhaps other studies as well.  相似文献   
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A novel biocatalytic reaction of transamidation of non-activated amides with amines is reported. Among 45 different lipolytic and proteolytic enzymes tested, only the lipase from Candida antarcticawas able to catalyze this reaction. The reaction proceeded with up to ca. 80% conversion in anhydrous methyl tert-butyl ether and worked with both N-substituted and unsubstituted amides. The biocatalytic transamidation is an equilibrium process and, therefore, higher conversions to the desired amide were achieved by using increased concentrations of the amine nucleophile.  相似文献   
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Oligonucleotide analogs consisting exclusively of alpha-anomeric deoxynucleoside units bridged with phosphorothioate linkages have been synthesized and tested in vitro as antiviral agents against human immunodeficiency virus (HIV) in human T cells. Two 28-mers, an homopolymer alpha-S-dC28 and an oligomer alpha-S-anti-rev complementary to the initiation site of the regulatory viral gene rev exhibited antiviral activities comparable to those reported for the corresponding beta-anomeric phosphorothioate analogs. In contrast, a nuclease-resistant homopolymer, alpha-dC28 was inactive. Their preliminary results would indicate that the origin of oligonucleotide phosphorothioate anti-HIV activity is not exclusively correlated with their higher nuclease resistance.  相似文献   
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A Monte Carlo simulation of clone growth is discussed from the point of view of clonal volume. It is shown that clone volume is a good representation of the number of cells per clone for a wide range of single cell growth equations. However, the rate at which the coefficient of variation in clonal volume approaches that of cell number per clone is strongly dependent upon the particular growth equation.  相似文献   
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A Na+/H+ exchanger is involved in the regulation of cytoplasmic pH and cellular volume in a variety of cells. Little is known about the molecular nature of this exchanger. The purpose of this study was to survey a variety of group-specific covalent reagents as potential inhibitors of the exchanger. Na+/H+ countertransport activity was assayed as the amiloride-sensitive rate of Na+-induced alkalinization in acid-loaded lymphocytes, or as the rate of swelling in cells suspended in sodium propionate medium. Activity was not affected by proteinases or by carboxyl-group and amino-group specific reagents. A significant inhibition was produced by diethylpyrocarbonate, a histidine-specific reagent and by N-ethylmaleimide, a sulfhydryl group reagent. A similarly reactive but nonpermeating sulfhydryl agent, glutathione-maleimide, failed to inhibit Na+-H+ exchange. Moreover, the reaction with N-ethylmaleimide was sensitive to changes in the cytoplasmic pH. The data suggest that the chemically reactive groups of the Na+/H+ exchanger of lymphocytes have limited exposure to the extracellular medium but that an internally located sulfhydryl group is critical for the cation-exchange activity.  相似文献   
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