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Biomedical subjects

A M Katzin

Publications and source records attributed to A M Katzin.

At least 37 records · Page 2Linked to original sources
PubMed1991

Trypanosoma cruzi: shedding of surface antigens as membrane vesicles.

Tissue culture-derived trypomastigotes from Trypanosoma cruzi spontaneously shed surface antigens into the culture medium. The shedding is a temperature- and time-dependent phenomenon and is independent of the presence of proteins or immune serum in the medium. The analysis of this process in four strains (Y, YuYu, CA1, and RA) showed differences in the amounts of polypeptides released. However, for all strains the liberation of the entire set of surface polypeptides ranging in molecular mass from 70 to 150 kDa was observed. Biochemical and electron microscopic data strongly suggest that most of the surface antigens are released as plasma membrane vesicles, ranging from 20 to 80 nm in diameter.

Animals↗
PubMed1991

Detection of antigens in urine of patients with acute falciparum and vivax malaria infections.

Using an antigen-capture, dot-blot assay, antigens were detected in the urine of 50 patients infected with Plasmodium falciparum. Antigens were also detected in 12/15 patients who had no detectable parasitemias 1-2 weeks after chemotherapy. By Western blotting and immunoprecipitation, four predominant antigens were identified with the following molecular masses (Mr) and isoelectric points (pI): antigen 1, 200 kDa, pI 6.4-6.27; antigen 2, 180 kDa, pI 5.2-4.8; antigen 3, 150 kDa, pI 5.5; antigen 4, 96 kDa, pI 5.1-4.8. These antigens were heat stable to 100 degrees C for 5 min. Antigens were also detected in the urine of 35 patients with acute P. vivax infections by Western blotting and dot-blot analysis and 10/10 patients three weeks following chemotherapy. The antigens had Mr of 200, 170, and 130 kDa.

Acute Disease↗
PubMed1989

Rapid determination of Trypanosoma cruzi urinary antigens in human chronic Chagas disease by agglutination test.

Detection of Trypanosoma cruzi in man becomes particularly difficult during the chronic stage of Chagas disease because of the low parasitemia. We were able to develop a simple and straightforward method for determining the concentration of T. cruzi antigens in urine using nitrocellulose micellar suspension (Nitrocell-Mr, Polychaco Argentina) and for their subsequent detection through a "latex" type agglutination test. The latex used was an esferocell nitrocellulose suspension (Esferocell-Mr, Polychaco). Specific antigens for T. cruzi were detected in 54 of 58 urine samples from chronic chagasic patients. The antigens characterized by affinity chromatography and SDS-PAGE were glycoproteins with apparent molecular weights (and pIs) of 100 kDa (pI 5 to 5.5), 80 kDa (pI 6.0), and 50 kDa (pI 6.5 to 7.0). This method is practical and fulfills the requirement of large-scale epidemiological studies. It is also helpful in cases of conflictive serology.

Animals↗
PubMed1987

Sialic acid in a complex oligosaccharide chain of the Tc-85 surface glycoprotein from the trypomastigote stage of Trypanosoma cruzi.

The carbohydrate moiety of the Tc-85 surface glycoprotein from the infective trypomastigote form of Trypanosoma cruzi was analysed. Tc-85 could be metabolically labeled by incubation of the cells with D-[14C]mannose or D-[14C]glucose. Degradation techniques were performed directly on the polyacrylamide gel band containing labeled Tc-85. A mannobiose was cleaved by beta-elimination and further treatment of the remaining material under conditions which liberate N-asparaginyl linkages, released a complex oligosaccharide. The presence of sialic acid was demonstrated by: mild acid hydrolysis, neuraminidase treatment and periodate oxidation under mild conditions followed by NaB3H4 reduction, hydrolysis, and detection of NANA7 by paper electrophoresis. In addition, the chromatographic behavior of the asialooligosaccharide was significantly different from that of the original sample. Galactose, mannose and glucosamine are the other monosaccharide components of the sialooligosaccharide.

Animals↗
PubMed1987

Antigenuria in infants with acute and congenital Chagas' disease.

Detection and partial characterization of Trypanosoma cruzi soluble antigens (SAg) in urine, as well as demonstration of parasite circulating antigens (CAg) in serum from pediatric patients with acute (10 patients) and congenital (10 patients) Chagas' disease, are reported. Classical techniques for parasite detection and antibody serology were also conducted in both groups. Samples collected before the onset of parasiticidal drug treatment were tested by an enzyme-linked immunosorbent assay for SAg and CAg demonstration. The control population consisted of 6 children with acute toxoplasmosis, 6 with cutaneous leishmaniasis, and 20 healthy individuals. Patients with acute cases were 100% positive for both SAg and CAg, whereas patients with congenital disease were 80% CAg positive and 100% SAg positive. Controls yielded negative results in all cases. Partial characterization of SAg from two patients with acute disease was performed by iodination, affinity chromatography, immunoprecipitation, and two-dimensional gel electrophoresis. Two different antigenic glycoproteins (80 kilodaltons, pI 6 to 6.5 and 55 kilodaltons, pI 6.5 to 7) were identified by these methods. Traditional serology and classical parasitologic tests failed, each in a different way, to provide an accurate diagnosis in the total of our patients. The enzyme-linked immunosorbent assay for SAg detection proved to be the most effective procedure for achieving early and precise proof of infection in acute and congenital cases of Chagas' disease.

Acute Disease↗
PubMed1985

Characterization of messenger RNA from epimastigotes and metacyclic trypomastigotes of Trypanosoma cruzi.

The cell-free translation products of polyribosomal and post-polyribosomal mRNAs from the non-infective epimastigotes and the infective metacyclic trypomastigotes of the parasitic protozoan Trypanosoma cruzi were compared by two-dimensional polyacrylamide gel electrophoresis. The result show that although many polypeptides are conserved, quantitative and qualitative differences are observed between both differentiation stages. The results also indicate the existence of post-polyribosomal mRNAs in equilibrium with polyribosomal counterparts. The immunoprecipitation of the in vitro synthesized polypeptides with chagasic human serum and the serum raised against an 85-kDa glycoprotein (P2-WGA), potentially involved in the process of T. cruzi penetration into mammalian cells, shows that while the chagasic serum recognizes the same 72-kDa, 68-kDa and 46-kDa polypeptides in both differentiation stages, the anti-P2-WGA serum immunoprecipitates a single 48-kDa polypeptide from in vitro translation products of metacyclic trypomastigotes.

Animals↗
PubMed1985

Correlation of tunicamycin-sensitive surface glycoproteins from Trypanosoma cruzi with parasite interiorization into mammalian cells.

Trypomastigote forms of Trypanosoma cruzi lose infectivity to cultured mammalian cells when exposed to tunicamycin. Upon reincubation into fresh medium, parasites recover their full penetration capacity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of [35S]methionine-labeled polypeptides showed that tunicamycin-treated parasites present several components with altered electrophoretic mobility when compared with controls. Immunoprecipitation with rabbit hyperimmune and human chagasic sera indicated that the surface antigens of approximate molecular masses of 175-180, 120-125, 90-95 and 85 kDa are not encountered in tunicamycin-treated trypomastigotes. By affinity chromatography on wheat germ agglutinin-Sepharose, it was observed that the trypomastigote-specific 85 kDa glycoprotein (Tc-85) is affected by the drug. The other affected components are glycoproteins with affinity for concanavalin A. The results suggest that tunicamycin-sensitive surface glycoproteins from T. cruzi are involved in the parasite interiorization into mammalian cells.

Animals↗
PubMed1984

Mapping of surface glycoproteins of Trypanosoma cruzi by two-dimensional electrophoresis. A correlation with the cell invasion capacity.

The cell-surface iodinatable proteins of Trypanosoma cruzi have been analyzed by two-dimensional polyacrylamide gel electrophoresis under equilibrium conditions. Antigenic polypeptides were characterized after immunoprecipitation and glycoproteins were identified by means of lectin-affinity chromatography. Two glycoproteins, with affinity for concanavalin A, were found to be common to both infective (trypomastigote) and non-infective (epimastigote) forms: protein 1 (90 kDa, pI 5.5-6.5) and protein 2 (80 kDa, pI 5.3-6.3). In epimastigotes a specific concanavalin-A-binding surface glycoprotein (70 kDa, pI 5.5) was identified. Trypomastigote forms, on the other hand, presented several specific iodinatable surface components: glycoproteins 3(85 kDa, pI 5.5), 4 (85 kDa, pI 5.0), 6 (100 kDa, pI 6.5), 7 (120 kDa, pI 6.3), 8 (68 kDa, pI 6.7) and several minor high-molecular-mass acid proteins, all containing glucose and/or mannose, and glycoprotein 5 (85 kDa, pI 6.3-7.5), containing N-acetyl-D-glucosamine (Tc-85). Proteins 1, 2 and 5 were the only ones which gave clear evidence of charge heterogeneity. Most of the surface proteins of trypomastigote forms, the exception being proteins 3, 4 and 8, were removed by treatment with trypsin. This proteolytic treatment results in 90% inhibition of the in vitro vertebrate-cell-invasion capacity of the parasites. Upon reincubation in culture medium for 4 h, the trypsin-removed glycoproteins are again detected, an observation that correlates well with the recovery of the cell-penetration capacity observed in the same period.

Animals↗
PubMed1983

Lectin receptors in Trypanosoma cruzi. An N-acetyl-D-glucosamine-containing surface glycoprotein specific for the trypomastigote stage.

We have investigated the interaction of three lectins, differing in their sugar specificities, with the surface of the three differentiation stages of Trypanosoma cruzi. The Scatchard constants for each lectin and parasite stage imply that differentiation of T. cruzi is accompanied by changes in the cell surface saccharides. Trypomastigotes obtained from two different sources do not differ appreciably as to the number and affinity of binding sites for the three lectins employed, suggesting a similar cell-surface saccharide composition. These conclusions are reinforced by sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the 131I-labeled surface glycoproteins, following isolation by affinity chromatography. The surface membrane of trypomastigotes, the infective stage to T. cruzi for mammalian cells, possesses a specific glycoprotein of apparent Mr 85000 (Tc-85) which is absent from the other two stages and can be isolated by affinity chromatography on wheat germ agglutinin-Sepharose columns. This glycoprotein also binds to concanavalin A, but not to Lens culinaris lectin. The binding of Tc-85 to wheat germ agglutinin is unaffected by treatment of either the isolated glycoprotein or intact living trypomastigotes with neuraminidase. Since N-acetyl-D-glucosamine inhibits internalization of trypomastigotes by cultured mammalian cells, it is suggested that Tc-85 might be involved in adhesion and/or interiorization of T. cruzi into mammalian cells, possibly via recognition of an ubiquitous host-cell surface N-acetyl-D-glucosamine-specific receptor activity.

Acetylglucosamine↗
PubMed1982

Trypanosoma cruzi: immunobiological studies on epimastigotes of several strains.

Epimastigotes from six Trypanosoma cruzi strains showed similar growth pattern and duplication time in a biphasic culture medium as well as similar capability to differentiate into metacyclic forms when grown in the special GM-TIIH culture; interactions of epimastigotes and Concanavalin A, Soy bean agglutinin or Wheat germ agglutinin were also similar for all the strains. On the other hand, differences in the antigenic patterns were detected by double diffusion tests. At least one precipitogen, undetectable in the other strains, was shared by the Y and RA strains. In the RA a second precipitogen was shared with Tul strain. The three strains mentioned, as identified by their IEPh pattern belonged to the C group described by Nussenzweig and Goble in 1966. However, the differences between Y and Tul precipitogens proved that the C group originally described might be made up by several subgroups. As Tul strain had been previously classified twice in the A group and once in the C group, the classic A, B and C antigenic groups seem to be relatively unstable. Due to this, and because of the differences in shape, infective capability surface saccharides, etc. already established for the trypomastigote stage, which correlate making strain grouping feasible, we consider the latter might prove a better stage to search for a strain marker.

Animals↗
PubMed1981

Biochemical and ultrastructural alterations produced by miconazole and econazole in Trypanosoma cruzi.

Miconazole and econazole, two fungicide imidazole derivatives, completely inhibited growth of Trypanosoma cruzi (Tulahuen strain) at concentrations of about 20 muM. Culturing of T. cruzi in the presence of lower doses of imidazole derivatives produced: decrease of 5,7-diene sterol content in epimastigotes (including ergosterol); disappearance of the nuclear chromatin, vacuolization and decrease in the electron density of the cytoplasm; selective surface alterations as revealed by an increased response to wheat-germ- and phytohemagglutinin. At variance with the effect of miconazole on Candida (De Nollin et al. (1977) Antimicrobial. Agents Chemother. 11, 500-513), miconazole and econazole, under the experimental conditions used, did not increase the rate of hydrogen peroxide generation by T. cruzi.

Agglutination↗
PubMed1980

Antigens of subcellular fractions of Trypanosoma cruzi. III. Humoral immune response and histopathology of immunized mice.

The relation of humoral antibody response to protection was evaluated in mice immunized with whole homogenates of Trypanosoma cruzi or with its flagellar fraction by direct agglutination and indirect fluorescent antibody test as well as by lytic and neutralizing activity against blood trypomastigotes. The results indicated that lytic antibodies were not implicated directly in protection against these trypanosomes. It was evident from histopathologic examination that the higher the degree of protection achieved, the lower the tissue damage observed in the challenged mice. Serum-neutralizing activity was highest in the groups protected most effectively.

Animals↗