Lionel G. Warren

Bio: Lionel G. Warren is an academic researcher. The author has contributed to research in topics: Antigen & Entamoeba histolytica. The author has an hindex of 4, co-authored 5 publications receiving 226 citations.

Metabolism of Schizotrypanum cruzi Chagas. II. Galactose Utilization.

Abstract: The utilization of galactose by Schizotrypanum cruzi and the effect of the sugar upon S. cruzi respiration are a function of the galactose concentration employed. Kinetic analysis of galactose utilization indicates that an active process and a diffusion component are involved in the utilization of this sugar by S. cruzi. Q02/Q galactose ratios at different concentrations of galactose-show that utilization of the sugar increases disproportionately to the increase in respiration. The latter is probably a consequence of galactose incorporation into polysaccharide. Methods of harvesting and washing parasites prior to experimental measurements influence the levels of endogenous respiration observed in this organism. Galactose is poorly utilized or not utilized by Trypanosomatidae (von Brand, 1952). Fulton and Joyner (1949) reported that respiration of Leishmania donovani was stimulated by galactose about one-third as much as by glucose. Zeledon (1960) reported that respiration of Schizotrypanum cruzi was stimulated by galactose. Zeledon (1960) also observed a stimulating effect by galactose upon the respiration of Endotrypanum schaudinni, L. enriettii, and S. vespertilionis. All of the aforementioned genera are considered to be distinct from the genus Trypanosoma, or in the case of Schizotrypanum, the taxonomic status is not resolved. Goncalves and Yamaha (1959) reported that the culture form of S. cruzi contains an immune polysaccharide which upon hydrolysis yields galactose as the principal monosaccharide. Von Brand et al. (1959) reported a polysaccharide from S. cruzi which on hydrolysis yields galactose. This polysaccharide may be identical with the immunopolysaccharide described by Goncalves and Yamaha (1959) (von Brand, 1962). Received for publication 16 April 1962. * This work was supported in part by a grant from the U. S. Public Health Service (E-1384) and funds from the International Atomic Energy Agency. t Present address: Dept. Tropical Medicine and Medical Parasitology, Louisiana State Univ. School of Medicine, 1542 Tulane Ave., New Orleans, Louisiana, USA. In view of the fact that utilization of galactose appears to set S. cruzi apart from other trypanosomes, and that galactose is involved in the synthesis of a major antigenic fraction of S. cruzi, further studies were initiated (in greater detail than those reported by Zeledon) on galactose utilization by culture forms of this

Induced resistance of mice to subcutaneous infection with Trichomonas gallinae (Rivolta, 1878).

Abstract: Animals used in this study were either mature female Holtzman white mice ca 35 g body weight or mature female Rockland Swiss Webster strain white mice ca 25 g body weight. Animals were always maintained on Purina laboratory chow. The inoculum used for inducing subcutaneous lesions in mice was prepared in the following manner. Using sterile technique throughout, a twice passaged 48-hour stock culture of T. gallinae was centrifuged at 1000 g for 10 minutes, and then a portion of the supernatant was removed to adjust the concentration of organisms to a level of 5 x106 per ml. Two tenths ml of the concentrate was inoculated subcutaneously into the shaven hind right

The origin of antigenic substances in Entamoeba histolytica Schaudinn, 1903, and serologic manifestations of their antibody-inducing properties.

Abstract: Chandler (1953) has emphasized the multitude of potential antigens which are introduced into an animal during a parasitic infection. Some of these are somatic and others are produced by metabolic activities of the parasite. He suggested that the latter physiologically derived antigens may be extracellular enzymes, against which the host produces antibodies. In most of the studies on nematodes these anti-

The identification by isoenzyme patterns of two distinct strain-groups of Trypanosoma cruzi, circulating independently in a rural area of Brazil

Abstract: Culture forms of 17 Trypanosoma cruzi stocks, primarily isolated from a rural area of endemic Chagas disease at Sao Felipe, Bahia, Brazil, were compared by the electrophoretic patterns of six enzymes: aspartate aminotransferase, alanine aminotransferase, glucose-6-phosphate dehydrogenase, malate dehydrogenase (decarb-oxylating) (NADP+), glucosephosphate isomerase and phosphoglucomutase. Two markedly distinct combinations of isoenzyme patterns were seen, justifying the arrangement of the 17 stocks into two strain-groups, each of which was enzymically homogeneous. One combination was characteristic of the 11 domestic stocks of T. cruzi derived from both human infections and domiciliated animals; the second was characteristic of the six sylvatic stocks derived from opossums and a sylvatic triatomine species. The enzyme patterns were independent of the original host and the type of culture medium used. Distinction of the two strain-groups accords with epidemiological evidence that the domestic and sylvatic transmission cycles in Sao Felipe do not overlap. It is suggested that the diverse enzyme characters of the two strain-groups circulating in Sao Felipe reflect diverse origins; the domestic form of T. cruzi probably invaded the area from the south of Brazil with the domestic triatomine vector, Panstrongylus megistus.

Further enzymic characters of Trypanosoma cruzi and their evaluation for strain identification.

Abstract: Starch-gel electrophoresis of 38 enzymes was attempted with extracts of Trypanosoma cruzi culture forms. 18 of the enzymes that gave discrete electrophoretic bands were selected for routine characterization of T. cruzi stocks; the enzymes were: aspartate aminotransferase (E.C. 2.6.1.1, ASAT); alanine aminotransferase (E.C.2.6.1.2, ALAT); phosphoglucomutase (E.C.2.7.5.1, PGM); glucosephosphate isomerase (E.C.5.3.1.9, GPI); malate dehydrogenase (oxaloacetate decarboxylating) (NADP+) (E.C.1.1.1.40, ME); glucose 6-phosphate dehydrogenase (E.C.1. 1.1.49, G6PD); malate dehydrogenase (E.C.1.1.1.37, MDH); aconitate hydratase (E.C.4.2.1.3, ACON); isocitrate dehydrogenase (NADP+) (E.C.1.1.1.42, ICD); alcohol dehydrogenase (NADP+) (E.C.1.1.1.2, ADH); lactate dehydrogenase (E.C.1.1.1.27, LDH); aminopeptidase (cytosol) (E.C.3.4.11.1, PEP); pyruvate kinase (E.C.2.7.1.40, PK); phosphoglycerate kinase (E.C.2.7.2.3, PGK); enolase (E.C.4.2.1.11, ENO); hexokinase (E.C.2.7.1.1, HK); mannosephosphate isomerase (E.C.5.3.1.8, MPI); and glutamate dehydrogenase (E.C. 1.4.1.2, GD). ADH (NADP+) in the genus Trypanosoma, and PGK, MPI and ENO, in T. cruzi, were apparently demonstrated for the first time. Between six and 18 enzymes were used to characterize more than 250 T. cruzi stocks, newly isolated from a wide range of sources in northern and central Brazil. All stocks were identified as belonging to T. cruzi zymodemes 1, 2 or 3, as originally defined—that is, by combination of electrophoretic patterns of ASAT, ALAT, PGM, GPI, ME and G6PD. The composite range of results with all enzymes confirmed the presence of three principal T. cruzi zymodemes, but some enzymic characters overlapped between zymodemes and others suggested subgroups within individual zymodemes. Seven (MDH, ACON, LDH, PK, PGK, ENO, HK) of the 18 enzymes did not distinguish the three zymodemes; five (ASAT, PGM, GPI, ICD, PEP) distinguished all three zymodemes; 10 (ASAT, ALAT, PGM, GPI, ME, G6PD, ICD, ADH, PEP, GD) distinguished zymodemes 1 and 2, of which seven plus MPI and eight plus MPI separated zymodemes 1 from 3 and 2 from 3 respectively. T. cruzi stocks were taken from a small area of the natural species distribution; the full range of enzymic characters within the species T. cruzi is expected to be far more complex. The epidemiological distribution of the zymodemes continued to accord with local transmission cycles and supported the hypothesis that distinct T. cruzi strains might be responsible for the enigmatic distribution of chronic Chagas's disease. Some of the difficulties in the empirical selection of new electrophoretic methods and the interpretation of results were presented, and the present and prospective significance of T. cruzi enzymic characters was discussed. Until the stability and genetic basis of T. cruzi enzymic characters are better understood it is recommended that isoenzymic profiles be confirmed routinely, both before and after stocks are used experimentally, as representative of a given zymodeme. A multiple biochemical approach to T. cruzi strain identification is recommended, using characters suitable for a numerical taxonomy.

A monoclonal antibody defining antigenic determinants on subpopulations of mammalian neurones and Trypanosoma cruzi parasites.

Abstract: A monoclonal antibody defining antigenic determinants on subpopulations of mammalian neurones and Trypanosoma cruzi parasites

Deficient metabolic utilization of hydrogen peroxide in Trypanosoma cruzi.

Abstract: The glutathione peroxidase-glutathione reductase system, an alternative pathway for metabolic utilization of H2O2 [Chance, Sies & Boveris (1979) Physiol. Rev. 59, 527-605], was investigated in Trypanosoma cruzi, an organism lacking catalase and deficient in peroxidase [Boveris & Stoppani (1977) Experientia 33, 1306-1308]. The presence of glutathione (4.9 +/- 0.7 nmol of reduced glutathione/10(8) cells) and NADPH-dependent glutathione reductase (5.3 +/- 0.4 munit/10(8) cells) was demonstrated in the cytosolic fraction of the parasite, but with H2O2 as substrate glutathione peroxidase activity could not be demonstrated in the same extracts. With t-butyl hydroperoxide or cumene hydroperoxide as substrate, a very low NADPH-dependent glutathione peroxidase activity was detected (equivalent to 0.3-0.5 munit of peroxidase/10(8) cells, or about 10% of glutathione reductase activity). Blank reactions of the glutathione peroxidase assay (non-enzymic oxidation of glutathione by hydroperoxides and enzymic oxidation of NADPH) hampered accurate measurement of peroxidase activity. The presence of superoxide dismutase and ascorbate peroxidase activity in, as well as the absence of catalase from, epimastigote extracts was confirmed. Ascorbate peroxidase activity was cyanide-sensitive and heat-labile, but no activity could be demonstrated with diaminobenzidine, pyrogallol or guaiacol as electron donor. The summarized results support the view that T. cruzi epimastigotes lack an adequate enzyme defence against H2O2 and H2O2-related free radicals.

Trichomonas vaginalis and trichomoniasis.

Abstract: Publisher Summary This chapter deals with more recent knowledge of the morphology and biology, pathology and laboratory diagnosis of T. vuginalis, with clinical aspects of trichomoniasis in women, men and children, and with the epidemiology and treatment of this infection. Trichomonas vaginalis is known as a ‘harmless commensal of the human vagina. “Trichomonadenkolpitis = trichomoniasis” of women whose vaginae contained many of these flagellates. The concept of T. raginalis as a primary pathogenic parasite was only gradually accepted. Without a doubt, T. iuginalis is the commonest of the human trichomonads and “Trichomonadenkolpitis” does exist despite the sceptical adverse views of some prominent older gynaecologists. Serological and immunobiological investigations have been only of theoretical interest until the present, because the finding of T. vaginalis by cultivation or direct microscopical examination is easier and more reliable. In mostly symptomless trichomoniasis of man, however, such investigations could be important. It seems that the divergences reported by different authors, may be due to the antigenic structure of the individual T. vaginalis strains.