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201.
Serum and biliary lipid metabolism were examined in 13 patients with different types of hyperlipoproteinemia before and after 4 weeks of treatment with either bezafibrate or fenofibrate. In patients with heterozygous familial hypercholesterolemia (FH), bezafibrate (n = 5) and fenofibrate (n = 7) produced a similar significant reduction of total cholesterol, LDL-cholesterol, and triglycerides by 21, 23, and 32%, respectively. In patients with familial combined hyperlipidemia (CHL), only triglycerides decreased markedly. Biliary lipid secretion rates in patients with heterozygous FH were not different from those of young male volunteers, indicating that a reduction of hepatic LDL receptors did not affect hepatic elimination of cholesterol or bile acids. Biliary cholesterol secretion increased significantly from 57 to 75 mg/hr during bezafibrate therapy (n = 8) and from 62 to 71 mg/hr during fenofibrate therapy (n = 9). No consistent change in bile acid or phospholipid secretion was observed. The elevated output of biliary cholesterol increased cholesterol saturation significantly from 147 to 185% and from 152 to 173% during administration of bezafibrate and fenofibrate, respectively. The present study indicates that treatment with bezafibrate or fenofibrate is effective in lowering LDL cholesterol in patients with heterozygous FH, but both drugs increase cholesterol saturation of bile, which might enhance the risk of cholesterol gallstone formation. 相似文献
202.
A Egesten J Alumets C von Mecklenburg M Palmegren I Olsson 《The journal of histochemistry and cytochemistry》1986,34(11):1399-1403
An immunoelectron microscopic technique using protein A-gold as a specific marker was used for precise intracellular localization of eosinophil granule proteins. Eosinophils from healthy individuals were isolated in metrizamide gradients. Eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO) were clearly located in the matrix of the large crystalloid-containing granules. In addition, ECP was probably present in the small granules of eosinophils. Major basic protein (MBP) was present in the crystalloid structure of specific granules. This method can be applied in studies of eosinophil degranulation to trace the release of biological effector molecules. 相似文献
203.
Carbohydrate side chains of Rauscher leukemia virus envelope glycoproteins are not required to elicit a neutralizing antibody response. 总被引:8,自引:4,他引:4 下载免费PDF全文
Antisera raised against Rauscher leukemia virus (R-MuLV) contain a preponderance of antibodies against glycoprotein gp70 that are dependent on the presence of carbohydrate side chains for reactivity, as judged by immunoprecipitation or Western blotting. However, the majority of neutralizing antibodies were not dependent on the presence of carbohydrate, as indicated by (i) the ability of deglycosylated R-MuLV to adsorb neutralizing antibody from sera as efficiently as glycosylated R-MuLV and (ii) the ability of deglycosylated R-MuLV to induce neutralizing antibody responses when injected into rabbits. Moreover, a faster response was obtained with deglycosylated R-MuLV than with untreated control virus in the latter experiments. The results indicate that the neutralizing antibodies are a discrete subpopulation of the total antibody response. Furthermore, the carbohydrate moieties appear to afford protection to the virion during infection, rather than serve as a target for neutralization. 相似文献
204.
Summary The objectives of this investigation were to determine the effects of oxygen partial pressure (pO2) and combined nitrogen (NH
4
+
) on rates of acetylene reduction (AR) associated with roots of intact corn, sorghum, and pearl millet plants. Soil-grown plants were carefully removed from soil and incubated hydroponically with the root system enclosed in a plastic cylinder; the tops were left exposed to ambient conditions. Oxygen concentrations around the root systems were controlled by sparging the nutrient solution with known quantities of O2 in N2. Ammonium nitrogen was added to the nutrient solution following establishment of AR rates to determine its effect on rates of N2-fixation (AR). Substantial AR rates (0.1–1.5 mol C2H4 g dry wt–1 h–1) were associated with roots exposed to 0–2% O2 (v/v) (0.0–2.02 kPa) in N2 following at 12–24 h period of exposure to the reduced oxygen tension. Root systems exposed to air failed to demonstrate AR while those exposed to 100% N2 showed lower activity than those at reduced pO2 values. Addition of NH
4
+
(10–20 g N ml–1 of nutrient solution) reduced AR by 75–90% within 24 h after addition. Oxygen uptake by roots exposed to low pO2 was substantially reduced. 相似文献
205.
Gene for an immunoglobulin-binding protein from a group G streptococcus. 总被引:45,自引:13,他引:32 下载免费PDF全文
The gene (spg) for an immunoglobulin G (IgG)-binding protein from a Streptococcus clinical isolate of Lancefield group G was cloned and expressed in Escherichia coli. The complete nucleotide sequence of the gene and 5'-flanking sequences was determined. The DNA sequence includes an open reading frame which encodes a hypothetical protein of 448 amino acid residues (Mr = 47,595). The 5' end of this open reading frame encodes a sequence resembling a typical secretion signal sequence, and the remainder of the encoded protein has features reminiscent of staphylococcal protein A and of streptococcal M6 protein, including repeated sequences and a similar C-terminal structure. Aside from this C-terminal structure, the encoded protein has little direct amino acid sequence homology to either protein A or M6 protein. In E. coli, the cloned gene directs the synthesis of a protein which binds to immunoglobulins, including rabbit immunoglobulin, goat IgG, and human IgG3(lambda). Its binding properties are similar to those of the protein G described by Bj?rck and Kronvall (L. Bj?rck and G. Kronvall, J. Immunol. 133:969-974, 1984), a type III Fc receptor from a group G streptococcus. 相似文献
206.
Laser cross-linking of nucleic acids to proteins. Methodology and first applications to the phage T4 DNA replication system 总被引:16,自引:0,他引:16
J W Hockensmith W L Kubasek W R Vorachek P H von Hippel 《The Journal of biological chemistry》1986,261(8):3512-3518
Single-pulse (approximately 8 ns) ultraviolet laser excitation of protein-nucleic acid complexes can result in efficient and rapid covalent cross-linking of proteins to nucleic acids. The reaction produces no nucleic acid-nucleic acid or protein-protein cross-links, and no nucleic acid degradation. The efficiency of cross-linking is dependent on the wavelength of the exciting radiation, on the nucleotide composition of the nucleic acid, and on the total photon flux. The yield of cross-links/laser pulse is largest between 245 and 280 nm; cross-links are obtained with far UV photons (200-240 nm) as well, but in this range appreciable protein degradation is also observed. The method has been calibrated using the phage T4-coded gene 32 (single-stranded DNA-binding) protein interaction with oligonucleotides, for which binding constants have been measured previously by standard physical chemical methods (Kowalczykowski, S. C., Lonberg, N., Newport, J. W., and von Hippel, P. H. (1981) J. Mol. Biol. 145, 75-104). Photoactivation occurs primarily through the nucleotide residues of DNA and RNA at excitation wavelengths greater than 245 nm, with reaction through thymidine being greatly favored. The nucleotide residues may be ranked in order of decreasing photoreactivity as: dT much greater than dC greater than rU greater than rC, dA, dG. Cross-linking appears to be a single-photon process and occurs through single nucleotide (dT) residues; pyrimidine dimer formation is not involved. Preliminary studies of the individual proteins of the five-protein T4 DNA replication complex show that gene 43 protein (polymerase), gene 32 protein, and gene 44 and 45 (polymerase accessory) proteins all make contact with DNA, and can be cross-linked to it, whereas gene 62 (polymerase accessory) protein cannot. A survey of other nucleic acid-binding proteins has shown that E. coli RNA polymerase, DNA polymerase I, and rho protein can all be cross-linked to various nucleic acids by the laser technique. The potential uses of this procedure in probing protein-nucleic acid interactions are discussed. 相似文献
207.
Cometabolism of low concentrations of propachlor, alachlor, and cycloate in sewage and lake water. 总被引:4,自引:4,他引:0 下载免费PDF全文
Low concentrations of propachlor (2-chloro-N-isopropylacetanilide) and alachlor [2-chloro-2',6'-diethyl-N-(methoxymethyl)acetanilide] were not mineralized, cycloate (S-ethyl-N-ethylthiocyclohexanecarbamate) was slowly or not mineralized, and aniline and cyclohexylamine were readily mineralized in sewage and lake water. Propachlor, alachlor, and cycloate were extensively metabolized, but the products were organic. Little conversion of propachlor and alachlor was evident in sterilized sewage or lake water. The cometabolism of propachlor was essentially linear with time in lake water and was well fit by zero-order kinetics in short periods and by first-order kinetics in longer periods in sewage. The rate of cometabolism in sewage was directly proportional to propachlor concentration at levels from 63 pg/ml to more than 100 ng/ml. Glucose but not aniline increased the yield of products formed during propachlor cometabolism in sewage. No microorganism able to use propachlor as a sole source of carbon and energy was isolated, but bacteria isolated from sewage and lake water metabolized this chemical. During the metabolism of this herbicide by two of the bacteria, none of the carbon was assimilated. Our data indicate that cometabolism of these pesticides takes place at concentrations of synthetic compounds that commonly occur in natural waters. 相似文献
208.
Methanogenesis in an Upflow Anaerobic Sludge Blanket Reactor at pH 6 on an Acetate-Propionate Mixture 总被引:8,自引:4,他引:4 下载免费PDF全文
Erik ten Brummeler Look W. Hulshoff Pol Jan Dolfing Gatze Lettinga Alexander J. B. Zehnder 《Applied microbiology》1985,49(6):1472-1477
High-rate anaerobic digestion can be applied in upflow anaerobic sludge blanket reactors for the treatment of various wastewaters. In upflow anaerobic sludge blanket reactors, sludge retention time is increased by a natural immobilization mechanism (viz. the formation of a granular type of sludge). When this sludge is cultivated on acid-containing wastewater, the granules mainly consist of an acetoclastic methanogen resembling Methanothrix soehngenii. This organism grows either in rods or in long filaments. Attempts to cultivate a stable sludge consisting predominantly of Methanosarcina sp. on an acetate-propionate mixture as substrate by lowering the pH from 7.5 during the start-up to approximately 6 failed. After 140 days of continuous operation of the reactor a filamentous organism resembling Methanothrix soehngenii prevailed in the sludge. The specific methanogenic activity of this sludge on acetate-propionate was optimal at pH 6.6 to 6.8 and 7.0 to 7.2, respectively. 相似文献
209.
Evaluation of quantitative parameters of the interaction of antibody-bearing liposomes with target antigens 总被引:2,自引:0,他引:2
Alexander L. Klibanov Vladimir R. Muzykantov Nikolai N. Ivanov Vladimir P. Torchilin 《Analytical biochemistry》1985,150(2):251-257
The model system for the analysis of targeted liposomes is proposed--the layer of protein antigen adsorbed on polystyrene wells. Antibodies were treated with palmitoyl chloride and liposomes were produced by the cholate dialysis method in the presence of the modified protein (7 X 10(-4) mol protein/mol lipid). Affinity of antibody-bearing liposomes to the antigen on the surface of Multiwell plates was studied, and apparent dissociation constant value was estimated: KD was in the range 1.5 to 5 X 10(-9) M liposomes. Sequential transfers of liposomes in antigen-coated plates revealed that the high-affinity fraction of liposomes is adsorbed first. The bound fraction has 1.7-times-higher protein content. For effective in vivo targeting it would be necessary to have high-affinity liposomes and a high concentration of the target antigen. 相似文献
210.
A sodium dodecyl sulfate-gradient gel electrophoresis system that separates polypeptides in the molecular weight range of 1500 to 100,000 总被引:1,自引:0,他引:1
A sodium dodecyl sulfate-polyacrylamide gradient gel system is described. It combines a linear gradient in polyacrylamide from 10.2 to 30.2% in the separating gel and the discontinuous ammediol/glycine buffer system suggested by Bury (A. F. Bury, 1981, J. Chromatogr. 213, 491-500). This urea-free electrophoretic system provides high resolution and clean separation patterns of proteins and polypeptides with molecular weights from 1500 to 100,000. It is especially suited for studying complex mixtures of proteins and proteolytic fragments, in particular with regard to immunoelectrotransfer blot techniques. 相似文献