Biological reduction of TNT as part of a combined biological-chemical procedure for mineralization.

The explosive 2,4,6-trinitrotoluene (TNT), one of the most abundant and persistent contaminants at former armament factories and military sites, was cometabolically reduced by sludge (mixed culture) from a sewage plant in order to facilitate mineralization in a subsequent photochemical treatment. Under aerobic conditions, the main reduction products were aminodinitrotoluenes (ADNTs). A greater amount of the nitroaromatics (ca.

[FDG-PET for diagnosis and follow-up of inflammatory processes: initial results from the orthopedic viewpoint].

Aim: The diagnosis and the assessment of osteomyelitis and spondylodiscitis can be difficult. The aim of this study was to evaluate the usefulness of FGD-PET in the detection of inflammatory processes.

Method: 23 orthopedic patients suspected of having peripheral osteomyelitis (n = 13) or spondylodiscitis (n = 10) were examined consecutively with FDG-PET.

Glycosyl-phosphatidylinositols of Trypanosoma congolense: two common precursors but a new protein-anchor.

The parasitic protozoan Trypanosoma congolense exhibits a dense surface coat which is pivotal for immunoevasion of the parasite. This dense surface coat is made of a single protein species, the variant surface glycoprotein, which is present in a high copy number. The protein is anchored to the plasma membrane by a glycosyl-phosphatidylinositol membrane anchor.

Immunoelectron microscopic studies on the specific adhesion of Trypanosoma congolense to cultured vascular endothelial cells.

Bloodstream forms of Trypanosoma congolense were cocultivated in vitro with vascular endothelial cells. The trypanosomes adhere specifically to the endothelial surfaces of the anterior part of their flagella, as shown by scanning and transmission electron microscopy. The interaction between parasite and host cell is very tight, and frequently the accumulation of endocytotic vesicles near the contact site is observed.

[African trypanosomes: parasites with protective mechanisms].

African trypanosomes have developed protective mechanisms in order to escape from their hosts' immune attack. New cell surface antigens become sequentially expressed during a chronic infection providing the parasites continuously with immunologically altered faces. The trypanosomal genome contains a considerable repertoire of different genes coding for the surface antigens; they become separately activated and expressed by a variety of novel molecular processes.

Pathobiochemical alterations in experimental chronic and acute trypanosomal infection in mice.

During an experimental chronic infection of inbred mice with Trypanosoma congolense several physiological parameters become altered. Splenomegaly followed later by hepatomegaly are predominant. Lactate dehydrogenase and aminotransferase activities of the plasma are elevated, the number of erythrocytes and thrombocytes decreases, whereas monocytic cells are detected in higher concentrations.

Characterization of epitopes on a variant surface glycoprotein from Trypanosoma congolense by six monoclonal antibodies.

Monoclonal antibodies were isolated from mice immunized with variant surface glycoprotein of Trypanosoma congolense. Five out of the six monoclonals were able to detect epitopes at the cell surface in an indirect immunofluorescence analysis. One antibody did not react.

Morphological changes in Trypanosoma congolense after proteolytic removal of the surface coat.

Bloodstream forms of Trypanosoma congolense were exposed to proteases at various concentrations, and the consequences of this treatment were continuously examined by electron microscopy. Unexpectedly, proteolysis did not simply result in the removal of the surface coat, but in dramatic morphological changes characterized by membrane adhesions, subsequently leading to flagella/plasmamembrane and to plasmamembrane/plasmamembrane fusions. The resulting axonemal internalization and rearrangement of cell organelles were followed by profound changes in cell shape.

Isolation and immunoelectromicroscopical characterization of Theileria annulata macroschizonts.

Theileria annulata macroschizonts were isolated from bovine lymphoblastoid cells grown in cell culture. To release the parasites, the cells were homogenized under hypotonic conditions. Intact host lymphocyte nuclei were lysed and the resulting chromatin precipitate was degraded by DNase.

In vitro studies on the biosynthesis of the surface glycoprotein of Trypanosoma congolense.

Tritiated leucine, glucosamine, mannose, and galactose were incorporated into the variant specific surface glycoprotein (VSG) of Trypanosoma congolense in vitro. The uptake of the precursors is shown by SDS-polyacrylamide electrophoresis and fluorography, by assay of the radioactivity in immunoprecipitates obtained with specific antisera, and by the isolation of the labeled antigens by affinity chromatography on concanavalin A-sepharose and isoelectric focusing. The in vitro labeled VSG exhibits the same degree of microheterogeneity as that observed in the VSG isolated from trypanosomes grown in animals.

Structural studies on the major oligosaccharides in a variant surface glycoprotein of Trypanosoma congolense.

The carbohydrate moieties in the four isotypes of a variant surface glycoprotein from Trypanosoma congolense were analyzed. All variant surface glycoprotein isotypes were found to contain up to 15% by weight of D-galactose, D-mannose, and N-acetyl-D-glucosamine in molar ratios approaching 1:3.2:3.

A differentiation-dependent polyisoprenol kinase in Dictyostelium discoideum.

Crude membrane fractions of Dictyostelium discoideum show the capacity to synthesize (1--3H)dolicholphosphate from (1--3H)dolichol. Formation of dolicholphosphate increased continuously over the first 15 min. The reaction rate was nearly linear with respect to the dolichol content up to 150 microM.

Study on a proteolytic enzyme from Trypanosoma congolense. Purification and some biochemical properties.

A protease has been purified from Trypanosoma congolense bloodstream forms by osmotic disruption, freeze-thawing of the cells, followed by chromatography using Thiopropyl-Sepharose and gel filtration. The enzyme is a thiolprotease. A combination of SDS-polyacrylamide gel electrophoresis and contact print zymograms using casein as substrate showed a single proteolytic band with a molecular weight of 31 000.

Sialic acids are responsible for charge heterogeneity of the variant surface glycoprotein of Trypanosoma congolense.

Intact living cells of Trypanosoma congolense can be labeled by periodate/borotritide. The procedure described introduces a radioactive label nearly exclusively into the variant surface glycoprotein (VSG). The label can be removed from the VSG by either neuraminidase treatment or by mild acid hydrolysis.

Purification of the variant antigens of Trypanosoma congolense: a new approach to the isolation of glycoproteins.

We describe a new and rapid method for the isolation and purification of the variant antigens of Trypanosoma congolense. The procedure consists of (a) partial lysis of trypanosomes with dioxane, (b) lectin-affinity-chromatography with Con A-Sepharose, (c) electrophoretic desorption and concomitant separation of Con A-Sepharose-bound glycoproteins in a granulated electrofocusing gel, (d) electrophoretic elution of focused proteins from the granulated gel particles. The efficiency of each step was followed quantitatively by affinity electrophoresis.

The dependence of glycosyltransferases in Dictyostelium discoideum on the structure of polyisoprenols.

Mannosyltransferases in plasma membranes of Dictyostelium discoideum synthesize polyisoprenylphosphomannosides from exogenous polyisoprenylphosphates and GDP-mannose. The specificity of the enzymes depends on the chain length and the saturation of the polyisoprenols. Maximum activity is reached by a alpha-saturated C-55 polyisoprenylphosphate.

Evidence for concanavalin A binding sites on the surface coat of Trypanosoma congolense.

Glycoproteins of Trypanosoma congolense have been detected on SDS-polyacrylamide gels using the Concanavalin A peroxidase technique. Using [35S]diazoniobenzenesulphonate as a marker for cell surface proteins it was possible to distinguish between internal glycoproteins and the surface coat proteins. On SDS-polyacrylamide gels Con A reacted with the surface coat proteins.

Diazoniobenzenesulfonate as marker for cell surface proteins: study of the surface coat of Trypanosoma congolense.

It is possible to label selectively the surface coat of Trypanosoma congolense with radioactive sulfanilic acid diazonium salt. As demonstrated by both sodium dodecylsulfate polyacrylamide gel electrophoresis and isoelectric focusing, radioactivity is incorporated into only one protein, which has a molecular weight of 57 000 and an isoelectric point of 6.25.

Localization of glycosyl transferases in plasma membranes from Dictyostelium discoideum.

Crude membranes from vegetative and aggregation competent cells of Dictyostelium discoideum Ax 2 were separated by a combination of differential and sucrose gradient centrifugation. A fraction mainly containing plasma membranes could be isolated. The high degree of purity was demonstrated by electron microscopy and by the presence of marker enzymes typical for the plasma membrane and the absence of enzymes characteristic for other subcellular compartments.

The biosynthesis of glycolipids during the differentiation of the slime mold Dictyostelium discoideum.

In the slime mold Dictyostelium discoideum polysioprenylphosphomannosides are substrates for membrane bound mannosyltransferases; the isolated and purified isoprenyl derivatives transfer mannose to protein in vitro in presence of membrane fractions. The biosynthesis of the mannolipids as well as the biosynthesis of a glucose containing cerebroside, which becomes synthesized in an early stage of the cell development proceeds under control of the cell differentiation. The isolation procedure and the properties of the glycolipids are described, and their functions for the cellular development are discussed.

Developmental regulation of nuclear glycosyl transfer in Cictyostelium discoideum.

Glycosyltransferases are active in isolated cell nuclei of Dictyostelium discoideum. Since the biological role of these nuclear enzymes is unknown we assayed their activity in nuclear fractions from vegetatively growing and differentiating amoebae. The nuclear N-acetylglucosaminyl transfer is highest in the vegetative stage and shortly after induction of differentiation, then declines gradually.

Cell surface mannosyl transferase activity in the liver of embryonic chick. A mannose containing glycolipid as intermediate in glycoprotein synthesis.

Trypsin dissociated intact cells of embryonic chick liver catalyze the transfer of mannose from exogenous GDP-mannose to glycoprotein in vitro. In cells of 8 day old embryos a surface bound mannosyltransferase-system forms several mannose containing isoprenoid-lipids in a primary step. One of these compounds serves as a substrate in the highly specific second step of the overall reaction, the transfer of mannose to glycoprotein.

Cell surface glycosyl transferase activities in liver cells of developing chicken embryos.

The cell surface of embryonic chick liver cells contains transferases for mannose, fucose, galactose, N-acetyl-glucosamine and N-acetyl-neuraminic acid. Liver cells obtained by trypsin-dissociation of the tissue use the corresponding exogenous sugar nucleotides as substrates. The activities of the enzymes tested do not depend neither no the dissociation procedure nor on de novo protein synthesis.