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At least 19 recordsLinked to original sources
PubMed1976

The relation of agglutinins to antigenic variation of Trypanosoma lewisi.

During the course of infection in the rat, Trypanosoma lewisi produces 2 antigenic variants: the 1st represents the initial, reproducing population of cells; and the 2nd the nonreproducing, ablastin-inhibited adult population. The specificities of the agglutinins elicited by the variants were studied by adsorption and agglutination methods and the newer immunoelectroadsorption technic. It was found that the reproducing variant has a surface antigen that reacts with the agglutinin specific for the adult variant, but this antigen does not become immunogenic until transformation to the adult variant occurs. It was also found, with fractions of immune sera obtained by gel filtration, that the agglutinin specific for the reproducing variant is IgG and that specific for the adult variant, IgM. The antigenic variants of pathogenic and nonpathogenic trypanosomes are compared, and the roles of trypanocidal and ablastic antibodies in the induction of antigenic variation are discussed.

Adsorption↗
PubMedDate not supplied

Effects of lysozyme on Trypanosoma lewisi.

Daily lysozyme (hen egg) injections, beginning on day 6 of Trypanosoma lewisi infections in rats, significantly reduced the number of circulating trypanosomes. The effect was dose dependent. Maximum reduction (50%) occurred 24 hours after one treatment of 80 mg was given intraperitoneally (I.P.). The same dose of lysozyme was more effective when divided equally into two injections per day. Controls consisting of appropriate buffers as well as human serum albumin had no effect on trypanosome populations. Animals receiving lysozyme exhibited a weight loss of 5% 24 hours following the first injection, but not other ill effects of the treatment were observed. In vitro experiments indicated that lysozyme did not cause lysis or immobilization alone or in combination with fibrinogen or rat antitrypanosomal serum. These results suggest that the cellular immune response of the host and lysozyme's cationic properties may be important in mediating the anti-trypanosomal response. Lysozyme may thus be an effective trypanocide against trypanosomes whose membranes resemble T. lewisi, such as T. cruzi, or as an adjunct to chemotherapy.

Animals↗
PubMed1975

Cell surface saccharides of Trypanosoma lewisi. I. Polycation-induced cell agglutination and fine-structure cytochemistry.

Trypanosoma lewisi bloodstream and culture forms were agglutinated differentially with low concentrations of the cationic compounds: ruthenium red, ruthenium violet, Alcian blue chloride, 1-hexadecylpyridinium chloride, lanthanum chloride, and cationized ferritin. The bloodstream form trypanosomes gave the highest agglutination levels with each of the compounds tested. Ruthenium red was the most effective inducer of cell agglutination among the several cations used. Trypsin-treated bloodstream forms were agglutinated less in the presence of ruthenium red than untreated controls. Ruthenium red-induced cell agglutination also was lowered with chondroitin sulphate and dextran sulphate, but not with alpha-D-glucose, alpha-D-mannose or with several methyl glycosides. Treatment of the bloodstream trypanosomes with alpha-amylase, dextranase, or neuraminidase had little effect on agglutination levels obtained with ruthenium red. Fine-structure cytochemical staining with ruthenium red, ruthenium violet, and Alcian blue-lanthanum nitrate was used to ascertain the presence and distribution of presumptive carbohydrates in the trypanosome cell surface. The extracellular surface coat of the bloodstream forms stained densely with each of the polycationic dyes. Trypsin treatment removed the surface coat from bloodstream trypanosomes; however, the surface membranes of the organisms were stained densely with the several dyes. Similar surface-membrane staining was obtained with the cationic compounds and the culture forms, which lack a cell surface coat. Cationized ferrin was used at the fine-structure level to visualize the negative surface charge present in the cell surface coat and external membrane of the several trypanosome stages. Results obrained from the agglutination and cytochemistry experiments indicate that complex polysaccharides are present in the surface membranes and cell surface coat of T. lewisi bloodstream forms. Similar conclusions also pertain to the surface membranes of the T. lewisi culture from trypanosomes. The carbohydrates probably represent glycopeptide and glycoprotein structural components of the surface membrane of this organism.

Agglutination↗
PubMed1978

Complement activating factor(s) of Trypanosoma lewisi: some physiochemical characteristics of the active components.

Of the complement activating factors present in Trypanosoma lewisi, the major component, a carbohydrate containing substance was further investigated. This component was found to have a lag time of complete activation of 2 CH50 units of bovine complement of approximately 15 minutes while 1% trypsin (a known activator of complement, used as a control system) was capable of instant consumption of a similar quantity of complement. In addition, the complement activating factor of trypanosomes was observed to be stable at 100 degrees C for 15 minutes and over a pH range of 3.0 to 11.0. Thin layer chromatography studies suggested that at least part of the active component contained lipid, perhaps indicating that it may be glycolipid in nature.

Animals↗
PubMed1978

[Isolation and physico-chemical properties of a complex kinetoplast DNA associate from the cells of Trypanosoma lewisi].

An associate of kinetoplast DNA (k-DNA) was isolated from the cells of Trypanosoma lewisi and characterized in terms of its sedimentation properties, melting parameters and reassociation kinetics. Electron microscopy studies showed that k-DNA isolated is a complex associate of circular molecules. The contour length of minicircular molecules is 0.77 mkm. k-DNA contains sites enriched by AT-pairs; melting of native associate and k-DNA fragments in the presence of 6.5 M sodium perchlorate results in the appearance of six zones within the temperature range of 47-64 degrees C. Data from k-DNA reassociation studies suggest that k-DNA associate constitutent molecules differ in sizes and nucleotide sequences. k-DNA is found to consist of two components with molecular weights of 1.7 . 10(6) and 17.5 . 10(6), respectively.

Animals↗
PubMed1978

A method for the assay of ablastin in the serum of rats infected with Trypanosoma lewisi.

This paper describes a simple quantitative assay for albastin, a factor present in the serum from rats infected with Trypanosoma lewisi, which prevents the division of the parasite. The assay measures in vitro the inhibition of the incorporation of 3H-TdR into the DNA of T. lewisi in the presence of serum from infected animals. Utilising this method, one can measure the titre of albastin in a particular serum sample and the time and duration of its appearance in the circulation of infected rats.

Animals↗
PubMed1978

Evidence implicating the mononuclear phagocytic system of the rat in immunity to infections with Trypanosoma lewisi.

The present study emphasises the importance of the mononuclear phagocytic system of the rat in immunity to infections with Trypanosoma lewisi. Despite the great increase in the weight of the spleen, the liver played a major role in removing the parasites from the circulation. No evidence could be obtained that removal of the parasites was related to the lytic activity of specific antibody and complement.

Animals↗
PubMed1978

Anemia, splenomegaly, and glomerulonephritis associated with autoantibody in Trypanosoma lewisi infections.

Anemia with splenomegaly and signs of glomerulonephritis were found associated with the acute and post-acute phase of Trypanosoma lewisi infections of laboratory rats. The onset of the anemia was associated with the peak of parasitemia and the development of cold-active hemagglutinin (HA) for trypsinized rat erythrocytes. It persisted with gradual recovery for as long as the trypanosomes and HA were detected in the blood. Signs of glomerulonephritis consisted of hypercellularity of the glomerular tuft, swelling of vascular endothelium and tubular epithelium, thickening of Bowman's membrane and tubular basement membrane, and abnormal numbers of hyaline casts in the distal convoluted tubules. Residual damage to the kidneys was not evaluated.

Anemia, Hemolytic↗
PubMed1977

Iron metabolism in Trypanosoma lewisi infection: serum iron and serum iron-binding capacity.

Progressive changes in iron levels, total iron binding capacity and hematocrit values in sera of rats infected with Trypanosoma lewisi are described. The host dietary group were: (1) complete or full complement; (2) iron-deficient, and (3) pair-fed or calorically restricted. The hematocrit values of T. lewisi-infected rats given the various diets were not significantly different from those of the controls. The decrease in total iron binding capacity (TIBC) of rats inoculated with T. lewisi and fed complete and pair-fed diets ranged up to 15% over uninfected controls. TIBC levels in rats fed an iron-deficient diet and inoculated with T. lewisi ranged up to 32% over uninfected controls. TIBC levels of deficient infected rats were significantly different from the controls from day 90 to infection to the end of the observation period. Serum iron (SI) values of non-infected rats regardless of dietary regimen showed significantly higher values than T. lewisi-infected animals between days 95 and 120. The average SI value, for this period, in adequately fed control rats was 204 +/- 7 microgram/100 ml as compared to 172 +/- 5 microgram/100 for trypanosome-infected rats. SI levels of rats on a pair-fed diet and infected with T. lewisi decreased to 17% over uninfected controls. SI levels of animals on an iron-deficient diet and infected with T. lewisi decreased up to 76% over uninfected controls.

Animals↗