| isopycnic isolation of african trypanosomes on percoll gradients formed in situ. | | 1982 | 6131595 |
| (ca2+ +mg2+)-atpase of trypanosomes. | | 1982 | 6132582 |
| host-parasite interactions which influence the virulence of trypanosoma (trypanozoon) brucei brucei organisms. | subclones were prepared in mice from t. b. brucei iltat 1.4 parasites. subclones which did not differentiate to stumpy forms in mice were highly virulent and did not stimulate detectable antibody responses. a subclone which did give rise to stumpy forms in mice, was less virulent and did stimulate an antibody response specific for the trypanosome surface glycoprotein. clones and subclones of t.b. brucei parasites which did not give rise to stumpy forms in mice, did give rise to stumpy forms in b ... | 1983 | 6134448 |
| characterization of trypanozoon stocks by isoelectric focusing and isoenzyme analysis. | isoelectric focusing on ultrathin polyacrylamide foils, coupled with isoenzymatic analysis using five different enzymes, was used to characterize blood-forms of t.b. brucei, t.b. rhodesiense and t.b. gambiense and procyclic forms of t.b. brucei and t.b. rhodesiense. the protein concentrations in the lysates were quantified. qualitative as well as quantitative differences were found. | 1983 | 6134449 |
| african trypanosomes contain calmodulin which is distinct from host calmodulin. | studies were initiated to determine whether african trypanosomes utilize ca2+ fluxes to coordinate complex morphological and biochemical life cycle changes. we have identified the ubiquitous intracellular ca2+ receptor, calmodulin, in two developmental stages of trypanosoma brucei rhodesiense. the transition from rapidly dividing, slender bloodstream trypomastigotes to slow growing procyclics in axenic culture was accompanied by changes in specific calmodulin content (3 micrograms/mg cell protei ... | 1983 | 6135450 |
| some observations on factors associated with the development of trypanosoma brucei brucei infections in glossina morsitans morsitans. | the susceptibility of glossina morsitans morsitans to trypanosoma brucei brucei infection was shown to be age-dependent during the first 12 h: the youngest age group (1-8 h after emergence) being more susceptible than the older ones. the susceptibility was enhanced by cooling the young flies to a temperature of 0-5 degrees c for 30 min. male flies were found to be more susceptible than females. the number of trypanosomes ingested did not influence the subsequent salivary-gland infection rates ob ... | 1983 | 6136171 |
| a simple classification of different types of trypanosomiasis occurring in four camel herds in selected areas of kenya. | camels from herds in four different areas of kenya were sampled at regular intervals over periods of 9-15 months and examined for the presence of trypanosomiasis. five hundred and eight camels divided into three age categories were studied. trypanosomiasis caused by t. evansi, t. brucei and t. congolense was shown to be present in varying degrees in all the herds. camels were divided into 5 types according to mortality, the presence or absence of circulating trypanosomes and antibody, and the pr ... | 1983 | 6141655 |
| trypanosoma vivax, t. congolense or t. brucei infection rates in glossina morsitans when maintained in vitro on the blood of goat or calf. | tenerals of glossina morsitans morsitans and g. m. centralis were infected with trypanosoma vivax, t. congolense or t. brucei by feeding mainly on infected goats and then maintained either in vivo on uninfected calves, goats or rabbits, or fed in vitro upon heparinised or defibrinated blood of goats or calves for 21 days for t. vivax and t. congolense and 30 days for t. brucei and then dissected. the observed differences in the infection rates for all three trypanosome species maintained on diff ... | 1984 | 6143482 |
| increased sensitivity to a natural pyrethrum extract of trypanosoma-infected glossina morsitans. | topical application of a natural pyrethrum extract on male and pregnant female glossina morsitans morsitans resulted in higher mortality for flies infected with trypanosoma brucei brucei than for uninfected control flies. infected males showed a significantly higher mortality while infected pregnant females showed a marginally significant increase in mortality. results support the hypothesis that infected flies are less healthy than uninfected flies. results also parallel previous findings using ... | 1984 | 6143486 |
| trypanocidal action of neuroleptic phenothiazines in trypanosoma brucei. | this paper reports the effects of a series of phenothiazine derivatives on trypanosomes in vitro. our results demonstrate that trypanosomes are very sensitive to some of these compounds at micromolar concentrations. electron microscopic analysis of drug-treated cells shows that the pellicular layer of microtubules is selectively disintegrated by phenothiazine treatment, while the flagellar axoneme is entirely resistant to the drug. these observations suggest that phenothiazines might constitute ... | 1983 | 6144043 |
| a quantitative ultrastructural study on the transformation of trypanosoma brucei metacyclic to bloodstream forms in vitro. | the transformation of metacyclic to bloodstream forms of trypanosoma brucei brucei was studied in vitro using light and electron microscopy. the ultrastructural composition was investigated with stereological methods and the mean cell volume determined in a coulter channelyzer. the mitochondrion showed the most significant changes during transformation with a reduction in volume as well as in the membrane areas. the glycosomes remained unchanged whereas the lipid inclusions increased over the 24 ... | 1984 | 6147983 |
| failure of trypanosomal membrane antigens to induce protection against tsetse-transmitted trypanosoma vivax or t. brucei in goats and rabbits. | a purified protein, relative molecular weight 83 kilodalton (kd), and plasma membranes from trypanosoma brucei were tested as potential vaccines against tsetse-transmitted t. vivax and t. brucei in goats and rabbits. the 83 kd protein was found in lysates of all clones of t. brucei examined, as well as in lysates of t. vivax, t. congolense and t. rhodesiense. rabbits and goats were immunized with various amounts of antigen in freund's complete adjuvant and boosted twice with antigen in freund's ... | 1984 | 6150617 |
| cerebral trypanosomiasis in cattle with mixed trypanosoma congolense and t. brucei brucei infections. | six boran steers were infected simultaneously with trypanosoma congolense and t. brucei brucei while another group of 3 was inoculated with t. b. brucei one year after infection with t. congolense. three further steers were infected with t. b. brucei alone. whereas, the six animals which received simultaneous infections developed clinical signs of cerebral trypanosomiasis as evidenced by depression, ataxia and occasional circling, those infected with t. b. brucei alone did not. at necropsy, 4 ou ... | 1984 | 6150618 |
| the contribution of chromosomal translocations to antigenic variation in trypanosoma brucei. | genomic rearrangements influencing gene expression occur throughout nature. several of these rearrangements disrupt normal gene expression, as exemplified by the genetic alterations caused by the mobile genetic elements of maize or drosophila (see shapiro 1983). other rearrangements are part of the normal developmental programme of an organism. an understanding of the control of genomic rearrangements and their effects on gene expression should contribute to our insight into the mechanism of gen ... | 1984 | 6151678 |
| structure of the variant glycoproteins and surface coat of trypanosoma brucei. | the pathogenic african trypanosomes have a unique mechanism for antigenic variation. each cell is covered by a surface coat consisting of about seven million essentially identical glycoprotein molecules drawn from a large repertoire of variants, each encoded by an individual gene. amino acid sequence variation extends throughout the molecule but reduces from the amino terminus to the carboxy terminus, where certain features, especially the grouping of cysteine residues, are quite conserved. the ... | 1984 | 6151686 |
| analysis by flow cytometry of dna synthesis during the life cycle of african trypanosomes. | dna content, at different stages in the life cycle of the hemoprotozoan parasite trypanosoma brucei, has been analysed with a fluorescence activated cell sorter. it was observed that the long slender bloodstream form stage and procyclic culture forms (analogous to the tsetse fly midgut stage) are dividing cell populations with cells in g1, s, g2 and mitosis. short stumpy bloodstream form and metacyclic fly salivary gland form populations are composed of non-dividing parasites stabilized in g1 or ... | 1984 | 6152113 |
| the acquisition of human serum resistance by a trypanosoma brucei brucei clone during non-cyclical passage and repeated exposure to normal human serum in vivo. | | 1984 | 6152583 |
| analytical techniques for cell fractions. xxviii. dissection of complex antigenic mixtures using monoclonal antibodies and two-dimensional gel electrophoresis. | | 1980 | 6153870 |
| in vitro cloning of animal-infective bloodstream forms of trypanosoma brucei. | clones of animal-infective bloodstream forms of trypanosoma brucei (stocks s.427 and lump 227) were made by transferring a single organism from bloodstream-form cultures into each well of microtest ii tissue culture plates containing bovine fibroblast-like feeder cells. when the number of trypanosomes increased to 10(2)--10(3)/well on days 4--16, they were transferred into plastic t-25 culture flasks also containing feeder cells and fresh medium. cultures were thereafter maintained by partially ... | 1980 | 6154276 |
| characterization of trypanosoma brucei isolated from lymph nodes of rats. | forms of trypanosoma brucei isolated from lymph nodes of cyclically or intravenously infected rats, at different stages of infection, were morphologically compared with the corresponding bloodstream forms. unlike the pleomorphic bloodstream trypanosome population, the lymph node trypanosome population was essentially monomorphic and resembled the slender forms of the bloodstream. values for the morphometric parameters indicated a position between the slender and the stumpy forms. the number of t ... | 1980 | 6154277 |
| trypanosoma brucei: radioimmunoassay of variant surface glycoproteins from organisms grown in vitro and in vivo. | | 1980 | 6157559 |
| the kinetoplast dna of the hemoflagellate protozoa. | the kinetoplast dna of leishmania tarentolae and trypanosoma brucei was studied in terms of genetic organization and transcriptional activity. several minor sequence classes of minicircles from l. tarentolae were cloned in a bacterial plasmid and were compared in terms of sequence organization. the cloned minicircles were characterized by the possession of a constant region of at least 91 nucleotides and a variable region. minicircles from trypanosoma brucei strain 366d were also cloned. fragmen ... | 1980 | 6159799 |
| murine t lymphocyte specificity for african trypanosomes. i. induction of a t lymphocyte-dependent proliferative response to trypanosoma brucei. | a procedure which results in the specific activation of primed murine t lymphocytes was adapted for the study of t lymphocyte activation by the african trypanosome: trypanosoma brucei. the assay calls for the in vivo priming of lymphocytes by the subcutaneous administration of parasites, followed by the co-cultivation in vitro of cells taken from the regional draining lymph nodes and the parasite. this co-cultivation results in a marked proliferation of lymphoid cells. the proliferation was show ... | 1980 | 6160003 |
| [behaviour of the trypanosoma brucei brucei strain stib 348c in mice. 1. influence of human serum on the strain (author's transl)]. | | 1980 | 6160658 |
| antigenic analysis by immunofluorescence of in vitro-produced metacyclics of trypanosoma brucei and their infections in mice. | the antigenic types in populations of metacyclic trypanosomes of trypanosoma brucei isolated from glossina morsitans head-salivary gland trypanosome cultures and bloodstream forms in the early parasitemias produced from whole culture supernatant fluids containing metacyclic forms, were analyzed by the indirect fluorescent antibody test using clone-specific antisera. metacyclic trypanosomes in cultures initiated with cloned bloodstream forms with heterogeneous with respect to their variable antig ... | 1980 | 6161247 |
| rheumatoid factors in mice: non-specific activators of heterophile rheumatoid factor production. | although possibly the best, lps is by no means the only non-specific activator of immune responsiveness (air). plant lectins such as pha and pwm have some ability to stimulate both total igm production (reverse igm pfc) and more particularly heterophile and homophile igm rheumatoid factor (rf) responses, together with igm 'antibody' responses to target antigens such as xenogeneic red blood cells or haptens such as tnp. some parasitic infections and/or parasite antigens were shown to be powerful ... | 1980 | 6161873 |
| kinetoplast dna and rna of trypanosoma brucei. | kinetoplast dna (kdna) and kinetoplast rna (krna) were isolated from bloodstream and procyclic culture forms of two clonal strains of trypanosoma brucei. no differences were observed in kdna (maxicircle) restriction profiles between bloodstream or procyclic culture forms of the same strain. some differences were observed in kdna maxicircle restriction sites between the two strains. buoyant density analysis of pst i digested kdna showed the release of a minor low density band representing unit le ... | 1980 | 6162099 |
| analysis of antigenic types appearing in first relapse populations of clones of trypanosoma brucei. | variant antigenic types (vats) represented in a total of 47 first relapse populations of 6 clones of trypanosoma brucei lump 227 were identified by immunofluorescent staining of living trypanosomes, using antiserum raised against purified surface antigens. the relative growth rates of these 6 clones were measured both individually and when grown together in a mixed population, and were found to be different under these two sets of conditions. a pattern emerged in the vats represented in relapses ... | 1981 | 6163126 |
| relationship between trypanosoma "brucei" and t. "rhodesiense". | | 1980 | 6163234 |
| glycopeptides from variant surface glycoproteins of trypanosoma brucei. c-terminal location of antigenically cross-reacting carbohydrate moieties. | glycopeptides have been purified after trypsin or pronase cleavage of variant surface glycoproteins from five antigenic variants of one clone of trypanosoma brucei. each peptide has been characterised by its amino acid and sugar composition and partial or complete amino acid sequence. the peptides were assayed in an indirect precipitation radioimmunoassay for inhibition of precipitation of one variant surface glycoprotein by a heterologous antiserum raised against another variant. two classes of ... | 1981 | 6163983 |
| quantitation of genetic differences between trypanosoma brucei gambiense, rhodesiense and brucei by restriction enzyme analysis of kinetoplast dna. | we have compared a total of 44 recognition sites for 12 restriction endonucleases on the 20 kilobase pair maxi-circle of kinetoplast dna from nine trypanosoma brucei stocks, four which are known to be infective to man (tow 'gambiense' and two 'rhodesiense' variants). in addition to five polymorphic sites, these dnas differ in the size of a 5 kilo-base pair region which is cleaved only by one of the restriction enzymes tested and which varies in size over 1.5 kilo-base pairs. our analysis shows t ... | 1981 | 6166860 |
| analysis of the dna and rna changes associated with the expression of isotypic variant-specific antigens of trypanosomes. | using specific (32p) labelled cdna probes, we compared the mrnas and the genomic dna sequences coding for the synthesis of two pairs of serologically related variant-specific antigens (vsas) of trypanosomes: antat 1.1 and antat 1.1b, both from the strain 1125 of t.b.brucei and antat 1.8 and litat 1.6 from t.b.brucei and t.b. gambiense, respectively. within each pair, large similarities were observed in the coding sequence, except in the 3' region which appears to be highly variable. however, a l ... | 1981 | 6170934 |
| homologous 3'-terminal regions of mrnas for surface antigens of different antigenic variants of trypanosoma brucei. | sequences corresponding to the complete 3'-terminal regions of the messenger rnas for three different variant surface glycoproteins of trypanosoma brucei were determined on complementary dna inserts cloned in recombinant plasmids. the three sequences show 80-130 base pair long segments of strong (70-80%) homology at the 3' ends, whereas ther regions upstream from the last 130-140 base pairs contain no significant homology. the signal aauaaa, present near the 3' ends of almost all known polyadeny ... | 1981 | 6170939 |
| variant specific antigens of trypanosoma brucei exist in solution as glycoprotein dimers. | purified variant specific antigens of trypanosoma brucei were shown to exist in solution as dimers, and occasionally as higher oligomers, as judged by gel filtration and by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis after treatment with bifunctional cross-linking reagents. | 1981 | 6171253 |
| simultaneous induction of an idiotype, corresponding anti-idiotypic antibodies, and immune complexes during african trypanosomiasis in mice. | | 1982 | 6172495 |
| studies on the biosynthesis of the variant surface glycoproteins of trypanosoma brucei: sequence of glycosylation. | the variant surface glycoprotein (vsg) of several trypanosoma brucei clones has been metabolically labeled with [35s]methionine in parasites grown in the presence or in the absence of tunicamycin. pulse and chase experiments followed by immunoprecipiation with anti-vsg sera and polyacrylamide gel electrophoresis of the immunoprecipitates, have helped to elucidate two steps of the sequence of glycosylation of vsg. immediately after, or concomitantly with the synthesis of the protein, a first type ... | 1981 | 6172709 |
| bleomycin-induced life prolongation of mice infected with trypanosoma brucei brucei eatro 110. | the antitumour antibiotic bleomycin, supplied as commercial blenoxaner (a mixture of bleomycinic acids), at 7 or 14 mg/kg prolonged life greater than 30 days beyond death of controls without relapse or sign of trypanosomes in the peripheral blood of mice infected with trypanosoma b. brucei eatro 110. control mice died in three to four days. the purified a2 and b2 bleomycin congeners were also active at this dose. spermidine, spermine and hirudonine (1,8-diamidinospermidine) but not putrescine, c ... | 1981 | 6172890 |
| immune depression in trypanosoma brucei brucei infected mice. sequential histological and immunological findings. | pathological findings in various organs and tissues, t and b lymphocyte inability to proliferate towards several mitogens, and the appearance of serum interferon at progressive stages after intraperitoneal infection of balb/c mice with trypanosoma brucei brucei are reported. heavy parasitaemia is evident throughout infection and complete hyporesponsiveness is already present on day 3. a sharp interferon production peak appears after 48 hours. the anatomopathological picture makes it clear that i ... | 1981 | 6173044 |
| further studies on difluoromethylornithine in african trypanosomes. | dl-alpha-difluoromethylornithine (dfmo), a specific enzyme-activated irreversible inhibitor of ornithine decarboxylase (odc) was previously shown to cure mice infected with trypanosoma brucei brucei, a parasite of game and cattle in africa and trypanosoma brucei rhodesiense, a human african sleeping sickness pathogen. our studies now indicate that dfmo blocks ornithine decarboxylase and lowers trypanosome polyamine levels in vivo. polyamine uptake in t.b. brucei also resembles that previously de ... | 1981 | 6175860 |
| [nonselective mechanism of antibody-induced stable antigenic variability of microorganisms. iii. suggested mechanism of variability of certain microorganisms]. | | 1982 | 6178238 |
| the isolation of t. brucei-like organisms from man. | | 1982 | 6178378 |
| studies on the catalytic properties of the calcium-dependent endoribonuclease of trypanosoma brucei cytoplasm. | a calcium-dependent endoribonuclease isolated from trypanosoma brucei cytoplasm has been further characterized. the products of exhaustive endonuclease digestion of poly(a), which the enzyme cleaved preferentially, were small oligonucleotides terminated by a 5'-phosphoryl group. its apparent km value was 0.8 mm using poly (a), and 3.3 mm using transfer rna. the base specificity of the endoribonuclease was further verified by using synthetic heteropolyribonucleotides as substrates. the enzymatic ... | 1982 | 6178971 |
| effects of exogenous polyamine and trypanocides on the dna polymerase activities from trypanosoma brucei brucei, mouse thymus and murine leukemia virus. | the effects of exogenously added spermine on activated (gapped) dna-directed and poly(dc) . (dg)12-18-directed dna synthesis were tested on the chromatographically separated dna polymerase activities of trypanosoma brucei brucei. activated dna-directed dna synthesis by the peak i (eluting from dna-agarose at 0.15 m kcl) and peak ii (eluting at 0.3 m kcl) polymerase was consistently inhibited or stimulated, respectively, by exogenous spermine. kinetic analysis revealed that inhibition of the peak ... | 1982 | 6178972 |
| serological cross-reactions among trypanosome variable antigen isotypes of the subgenus trypanozoon. | | 1982 | 6179482 |
| cyclical transmission of in vitro cultivated bloodstream forms and procyclic trypomastigotes of trypanosoma brucei brucei by glossina morsitans morsitans. | in vitro cultivated bloodstream and procyclic forms of trypanosoma b. brucei stib 247 were cyclically transmitted by glossina m. morsitans. the tsetse flies were infected artificially on a silicon membrane. metacyclic trypanosomes from mature salivary gland infections were used to initiate bloodstream form cultures. they transformed into slender bloodstream forms and gave rise to established cultures that proved to be infective for the vector. the metacyclic forms retained the strain-specific ba ... | 1982 | 6182705 |
| novel combination chemotherapy of experimental trypanosomiasis by using bleomycin and dl-alpha-difluoromethylornithine; reversal by polyamines. | | 1982 | 6182888 |
| cross-neutralization of two different trypanosome populations derived from a single organism. | | 1982 | 6183596 |
| immune response to deoxyribonucleic acid (dna) of african trypanosomes. | | 1982 | 6186620 |
| biochemistry of the variant surface glycoproteins of salivarian trypanosomes. | | 1982 | 6187189 |
| anti-trypanosomal factor in the haemolymph of glossina. | the motility of cultured procyclic forms of trypanosoma brucei brucei antat serodeme derived from eatro 1125 was greatly reduced when incubated in vitro with the haemolymph of glossina morsitans morsitans at dilutions as low as 1:512 after incubation periods of 1-2 h at 27 degrees c. this effect was demonstrated in the haemolymph of male and female, teneral and non-teneral g.m. morsitans but was abolished by heat inactivation. a significant reduction in the motility of cultured forms of trypanos ... | 1982 | 6187195 |
| the membrane form of variant surface glycoproteins of trypanosoma brucei. | african trypanosomes are parasitic protozoa which are enveloped by a surface coat consisting of a matrix of identical glycoprotein molecules. variations in the composition of these variant surface glycoproteins (vsgs) allow the parasite to escape the host's immune system and render effective immunoprophylaxis improbable. however, underlying the surface coat, all variant antigen types contain common membrane components, some of which can activate complement by the alternative pathway, leading to ... | 1983 | 6188057 |
| reverse transcription of trypanosome variable antigen mrnas initiated by a specific oligonucleotide primer. | african trypanosomes change their antigenicity by successively expressing different members of a group of related but highly diverse proteins, the variant surface glycoproteins (vsgs). we describe a synthetic oligonucleotide that can prime specifically reverse transcription of vsg mrna out of total trypanosome poly(a)+ rna. the specificity of this priming was verified by cdna sequence analysis of the transcription products and by the demonstration of variant-specific hybridization of the individ ... | 1983 | 6188156 |
| analysis of the variable antigen composition of trypanosoma brucei brucei metacyclic trypanosomes using monoclonal antibodies. | the metacyclic trypanosomes of a trypanosoma brucei brucei clone (iltat 2.1) were analysed with regard to their variable antigen (vat) composition using monoclonal antibodies. the metacyclic population was antigenically heterogeneous. despite the heterogeneity, however, the overall vat composition of the metacyclic population appeared to be limited in number. a similar pattern of reactivity was observed when the monoclonal antibodies were tested on metacyclics of another clone (il tat 2.2) deriv ... | 1983 | 6190388 |
| production of interferons during experimental african trypanosomiasis. | african trypanosomiasis is associated with profound changes in the function of the immune system. in this study we find that alpha/beta and gamma interferon (ifn) are released into the serum of mice infected with trypanosoma brucei. the parasite-induced rise in serum ifns is associated with a detectable parasitaemia, but the serum ifn peak precedes the peak parasitaemia in some cases. unlike other protozoan interferon inducers, no parasite-dependent ifn production was observed in the pre-patent ... | 1983 | 6190591 |
| in vivo effects of alpha-dl-difluoromethylornithine on the metabolism and morphology of trypanosoma brucei brucei. | the eatro 110 isolate of trypanosoma brucei brucei was grown in rats for 60 h and the animals treated with the ornithine decarboxylase inhibitor alpha-dl-difluoromethylornithine 12 h or 36 h prior to sacrifice. control untreated animals died 72-80 h after infection. treated parasites were shorter and broader than the predominantly long slender forms found in untreated controls and many had two or more nuclei and kinetoplasts. trypanosomes were purified from blood and examined for disruption of p ... | 1983 | 6193423 |
| efficacy of combinations of difluoromethylornithine and bleomycin in a mouse model of central nervous system african trypanosomiasis. | dl-alpha-difluoromethylornithine, a polyamine biosynthesis inhibitor, and bleomycin, a currently used antineoplastic agent, have each previously been shown to be curative for acute short-term infections of mice with trypanosoma brucei brucei, an african trypanosome closely related to those that cause the human disease african sleeping sickness. these agents were tested singly and in combination in a previously described mouse model of sleeping sickness with demonstrable brain involvement. the or ... | 1983 | 6193522 |
| a subpopulation of trypanosome microtubules recognized by a monoclonal antibody to tubulin. | two hybridoma cell lines were selected after the fusion of the myeloma cell line x-63 ag8-653 with spleen cells from mice immunized with bovine brain microtubules. these lines, clones 3f3 and 16d3, secrete igm antibodies both staining a fibrillar network in fibroblasts. autoradiography of immunoblots of sds gels showed that the antigenic determinants defined by these antibodies are present on tubulin and also on several other polypeptides in mammalian cells. in contrast, they were found to react ... | 1983 | 6194984 |
| modifications of a trypanosoma b. brucei antigen gene repertoire by different dna recombinational mechanisms. | in the trypanosoma b. brucei antat 1.1c clone, the gene coding for the variant-specific surface antigen is telomeric and appears as a hybrid sequence, partially modified by gene conversion. this conversion is very similar to that observed in another antat 1.1-expressor clone (antat 1.1b). this sequence is not activated by duplicative transposition, although it could be activated by duplication in another clone (antat 1.10). instead activation of the antat 1.1c gene seems operated by reciprocal r ... | 1983 | 6197182 |
| [characterization of the antigenic index antar 5 of trypanosoma brucei brucei]. | | 1983 | 6197941 |
| topologic mapping of protective and nonprotective epitopes on the variant surface glycoprotein of the wratat 1 clone of trypanosoma brucei rhodesiense. | monoclonal antibodies were used in competitive antibody binding assays to define and map epitopes on the variant surface glycoprotein of the wratat 1 clone of t. b. rhodesiense. by using a panel of 30 wratat 1-specific monoclonal antibodies, 16 epitopes were defined that fall into four clusters, having 1, 1, 3, and 11 distinct epitopes respectively. all epitopes were easily classified as being 1) exposed uniformly on the surface of the trypanosome, 2) exposed only in the region of the flagellar ... | 1984 | 6199421 |
| antigenic variation in trypanosoma brucei analyzed by electrophoretic separation of chromosome-sized dna molecules. | pulsed field gradient gel electrophoresis fractionates chromosome-sized dna molecules from t. brucei. about 60% of the dna remains in or close to the gel slot (large dna). there are about three chromosomes of approximately 2 mb, at least six chromosomes of 200-700 kb, and roughly a hundred mini-chromosomes of 50-150 kb. the basic copy genes for vsgs 118 and 221 reside in large dna. their activation by duplicative transposition leads to the appearance of an additional copy in the 2 mb dna, showin ... | 1984 | 6202420 |
| antigenic variation during the developmental cycle of trypanosoma brucei. | during the complex life cycle of trypanosoma brucei, changes in the exposed surface antigens occur in both the mammalian host and the insect vector (glossina spp.). these antigenic changes are associated with alterations of the variant surface glycoprotein (vsg) composition or with the loss of the vsg. in the bloodstream of the mammalian host, trypanosomes successfully evade destruction by the host's immune response by continuously expressing alternative vsgs, at low frequency, which are not des ... | 1984 | 6204043 |
| comparison of the genes coding for the common 5' terminal sequence of messenger rnas in three trypanosome species. | messenger rnas of trypanosoma brucei share a common 5' terminal sequence of 35 nucleotides, encoded by a mini-exon located in 1.35-kb tandemly linked repeats. we show here that sequences, almost identical to the mini-exon of t. brucei, are present in mrnas from members of two other kinetoplastid subgenera: trypanosoma vivax and trypanosoma cruzi. as in t. brucei, these mini-exons are encoded by small tandemly linked repeat elements. we have determined and compared the nucleotide sequences of the ... | 1984 | 6204273 |
| expression of antigenic regions of a trypanosome variable surface glycoprotein in e. coli using bal-31 nuclease digestion. | we have used the expression of a trypanosome variable surface glycoprotein (vsg) in e. coli to produce vsg serotype-specific antisera which have none of the cross-reacting specificities characteristic of antisera prepared against purified vsgs. this was accomplished by treating restriction fragments of vsg cdnas with bal-31 nuclease to facilitate expression of their open reading frames in the e. coli expression vector, pmr100 (4). the resultant vsg-beta-galactosidase fusion proteins possess vari ... | 1984 | 6204274 |
| cytotoxicity of monoclonal antibodies to trypanosoma brucei. | monoclonal antibodies (mcabs) were raised against metacyclic variable antigen types (m-vats) of the antar 1 and etar 1 serodemes of trypanosoma brucei. two dominant m-vats, one from each serodeme, were labelled by two of the mcabs using the indirect immunofluorescence technique. these mcabs were of the igm class, and labelled exposed epitopes on living trypanosomes. they showed lytic activity in vitro towards their respective homologous vat trypanosomes, both in the presence and absence of compl ... | 1984 | 6207646 |
| solid-phase sequence analysis of polypeptides eluted from polyacrylamide gels. an aid to interpretation of dna sequences exemplified by the escherichia coli unc operon and bacteriophage lambda. | an approach to sequencing proteins by the solid-phase method combined with isolation of proteins and polypeptides by gel electrophoresis is described. mixtures of proteins or polypeptides resulting from digests are fractionated in the presence of dodecylsulphate in polyacrylamide gels. they are detected with coomassie blue, eluted, selectively reacted with porous glass derivatives and sequenced in their amino-terminal regions with the aid of a new microsequencer. alternatively they can be analys ... | 1982 | 6210528 |
| identification and characterisation of two n-acetylglucosaminyltransferases associated with trypanosoma brucei microsomes. | microsomes forom trypanosoma brucei contain glycosyltransferases able to incorporate n-[14c]acetylglucosamine into two different types of acceptors. a first transferase catalyzes the transfer of n-[14c]acetylglucosamine 1-phosphate from uridine diphosphate n-[14c]acetylglucosamine into dolichol monophosphate. the enzymatic activity requires mn2+, is time and temperature dependent, has an optimum ph of 7.4 and is completely inhibited by the antibiotic tunicamycin. exogenous dolichol monophosphate ... | 1982 | 6211616 |
| assessment of t lymphocyte responses induced by parasite antigens. | recently developed procedures for the isolation and continuous growth in vitro of t lymphocytes can be used to extend our knowledge of cellular immune responses elicited by parasitic infections. these procedures are adaptable to the study of both the inductive and effector phases of t cell responses. the inductive phase of t cell responses is measured by assessing the level of blastogenesis induced in antigen-primed lymphocyte populations by parasite antigens. the development of limiting dilutio ... | 1982 | 6215760 |
| trypanosoma brucei: recognition in vitro of two developmental forms by murine macrophages. | | 1982 | 6217981 |
| in vitro induction of human helper t cell activity by trypanosoma brucei. | proliferation of peripheral blood t lymphocytes from unsensitized donors in response to fractions of trypanosoma brucei was observed to be monocyte-dependent. the activated t cells displayed enhanced 'helper' activity, but no 'suppressor' activity during pokeweed mitogen (pwm)-induced immunoglobulin (igm and igg) synthesis, and were resistant to the inhibitory effects of theophylline on e rosette formation. whilst in vivo studies have failed to reveal excessive t cell proliferation in patients w ... | 1983 | 6223728 |
| arsenic and old taxa: subspeciation and drug sensitivity in trypanosoma brucei. | resistance to the trypanocidal drugs atoxyl and tryparsamide was traditionally considered to be a diagnostic feature of rhodesian sleeping sickness and, consequently, of trypanosoma rhodesiense. in examining the tryparsamide sensitivity of 13 isoenzymically defined stocks of the subgenus trypanozoon, typical west african stocks showed no greater drug sensitivity than did those of east and central africa. the greatest resistance to tryparsamide was shown by two stocks isolated in the ivory coast. ... | 1984 | 6241967 |
| novel expression-linked copies of the genes for variant surface antigens in trypanosomes. | pathogenic african trypanosomes evade the immune system of their mammalian hosts by the sequential expression of alternative cell-surface glycoproteins (reviewed in refs 1,2). variant surface glycoproteins (vsgs) purified from cloned variants of trypanosoma brucei have similar molecular weights (about 60,000), but differ in amino acid composition, n-terminal amino acid sequence and c-terminal structure. we have cloned dna complementary to the messenger rna's for four immunologically distinct vsg ... | 1980 | 6243753 |
| subcellular fractionation of trypanosoma brucei bloodstream forms with special reference to hydrolases. | bloodstream forms of trypanosoma brucei have been screened for the presence of enzymes that could serve as markers for the plasma membrane, flagellar pocket, lysosomes, endoplasmic reticulum and golgi apparatus in order to study the subcellular organization of the digestive system of the parasite. acetylesterase, acid dnase, acid phosphatase, acid phosphodiesterase, acid proteinase, acid rnase, alanine aminotransferase, galactosyl transferase, alpha-glucosidase, inosine diphosphatase and alpha-m ... | 1980 | 6245876 |
| effects of oligomycin on glucose utilization and calcium transport in african trypanosomes. | oligomycin (3 microgram ml-1) inhibited glucose utilization in trypanosoma brucei s42 as shown by measurements of oxygen uptake and pyruvate production. carbonyl cyanide 3-chlorophenylhydrazone, an uncoupler of oxidative phosphorylation, did not relieve this inhibition, although some relief was afforded by the alternative substrate glycerol. naturally dyskinetoplastic trypanosoma evansi miag 105 was less sensitive to inhibition by oligomycin although glycerol relief was still observed, relecting ... | 1980 | 6246194 |
| trypanosoma brucei: activities and subcellular distribution of glycolytic enzymes from differently disrupted cells. | | 1980 | 6248354 |
| sub-cellular fractionation of trypanosoma brucei. isolation and characterization of plasma membranes. | a procedure is described for the isolation of sub-cellular fractions from bloodstream forms of trypanosoma brucei. the method leaves intact most of the nuclei, mitochondria and microbodies. all the fractions have been chemically characterized and tested for 10 enzymatic markers. about 5% of total cell protein was isolated as a microsomal fraction containing mostly plasma membranes and endoplasmic reticulum vesicles. plasma membranes were purified by high-speed centrifugation on magnesium-contain ... | 1980 | 6248830 |
| the kinetoplast dna of trypanosoma equiperdum. | we have analyzed the kinetoplast dna for trypanosoma equiperdum (american type culture collection 30019) and two dyskinetoplastic strains derived from it. the dna networks from the kinetoplastic strain are made up of catenated mini-circles and maxi-circles, like the networks from the closely-related trypanosoma brucei. the mini-circles of t. equiperdum lack the pronounced sequence heterogeneity of t. brucei mini-circles, as shown by the fragment distribution of restriction digests and by the pre ... | 1980 | 6249368 |
| movable genes. | | 1980 | 6253793 |
| evidence for a branched electron transport chain in trypanosoma brucei. | the flow of electrons the terminal oxidases present in the bloodstream and procyclic trypomastigotes of trypanosoma brucei lump 1026 has been investigated by the use of salicylhydroxamic acid (sham) and cyanide. respiration in bloodstream trypomastigotes was completely inhibited by 0.5 mm sham with a ki below 10 microm. the ki for sham in procyclic trypomastigotes was 70 microm. in procyclic trypomastigotes there are at least three terminal oxidases of which the two major ones are cytochrome aa3 ... | 1980 | 6255326 |
| 'swell dialysis' demonstrates that adenylate cyclase in trypanosoma brucei is regulated by calcium ions. | a new technique, 'swell dialysis', is described that allows the study of cellular enzymes in situ if they are located in the cytoplasm or on the cytoplasmic face of any membrane. the technique is potentially applicable to any population of individual eukaryotic cells that lack a cell wall. in this study swell dialysis has been applied to an examination of the regulation of adenylate cyclase in blood-stream forms of trypanosoma brucei (427-12/ici-060). adenylate cyclase in this protozoon is shown ... | 1980 | 6257514 |
| studies on glycerol kinase and its role in atp synthesis in trypanosoma brucei. | glycerol kinase of trypanosoma brucei has been shown to be capable of catalysing sn-glycerol-3-phosphate dependent adp phosphorylation for atp generation. the rate of this reaction (vr) is sufficient to account for the observed rate of glycerol production from anaerobic glucose metabolism by intact cells and to account for net atp synthesis. glycerol kinase has been purified by preparing a post-nuclear, particulate fraction and solubilizing the enzyme with 0.5% (w/v) triton x-100. this treatment ... | 1980 | 6258071 |
| cloning and characterization of dna sequences complementary to messenger ribonucleic acids coding for the synthesis of two surface antigens of trypanosoma brucei. | full length double-stranded complementary dnas (ds cdnas) could be synthesized on mrnas enriched in sequences coding for the synthesis of the variant specific antigens (vsas) antat 1.1 and antat 1.8 from trypanosoma brucei brucei. the size of these ds cdnas is about 1700 and 1850 base pairs for antat 1.1 and antat 1.8 respectively. the ds cdnas were cloned in the plasmid pbr322; two clones harboring a copy of each coding sequence were selected. both the hybrid-arrested translation and the positi ... | 1980 | 6258157 |
| variations in maxi-circle and mini-circle sequences in kinetoplast dnas from different trypanosoma brucei strains. | we have compared a total of 30 recognition sites for eight restriction endonucleases on the 20-kilobase-pair maxi-circle of kinetoplast dnas from five different trypanosoma brucei strains. in addition to three polymorphic sites were have found a 5 kilobase-pair region that is not cleaved by any of the eight enzymes and that varies in size over 1 kilobase pair in the strains analysed. mini-circles from these five strains, digested with endonuclease taqi or mboii, yield very complex fragment patte ... | 1980 | 6260147 |
| cyclic 3',5'-adenosine monophosphate levels during the developmental cycle of trypanosoma brucei brucei in the rat. | intracellular content of cyclic 3',5'-adenosine monophosphate was determined in several strains of trypanosoma brucei brucei during their growth in rats. in non-relapsing infections with the cloned monomorphic strain 110m and with the cloned pleomorphic strain ytatl, the amount of cyclic amp per 10(9) trypanosomes increased from 30 to over 90 pmol as the parasitemia increased from patency to over 10(9) organisms per ml. this increase was not observed during non-relapsing infections with strain 4 ... | 1981 | 6265773 |
| a rapid method for the isolation of intact glycosomes from trypanosoma brucei by percoll -gradient centrifugation in a vertical rotor. | a rapid method for the isolation of intact glycosomes from trypanosoma brucei is described. a post large-granule extract is subjected to density-gradient centrifugation on isotonic percoll in a vertical rotor. this results in a good separation of the glycosomes, which equilibrated at 1.09 g/cm3, from other cellular components. glycosomes isolated from such a gradient are 9-fold purified relative to the starting homogenate with a yield of 25%. their glycolytic enzymes exhibit a high latency indic ... | 1981 | 6265776 |
| gene duplication and transposition linked to antigenic variation in trypanosoma brucei. | dna sequence complementary to trypanosoma brucei mrnas coding for the synthesis of the variant-specific antigens antat 1.1 and antat 1.8 have been cloned and characterized. these sequences have been used as probes to analyze the corresponding genes in the nuclear dna. the two genes seem to be represented in several (three to six) copies, some of which are incomplete. transcription of one or the other of these two genes is linked to a genetic rearrangement implying duplication and transposition o ... | 1981 | 6265900 |
| transcription of kinetoplast dna in trypanosoma brucei bloodstream and culture forms. | | 1981 | 6267635 |
| variant surface glycoproteins of trypanosoma brucei are synthesised with cleavable hydrophobic sequences at the carboxy and amino termini. | cdnas coding for the amino and carboxy termini of two trypanosome variant surface glycoproteins (vsgs) have been sequenced. the results indicate that vsgs are synthesised with hydrophobic amino-terminal leader and carboxy-terminal tail sequences which are absent from purified mature vsgs. | 1981 | 6272213 |
| field diagnosis of sleeping sickness in the ivory coast. i. comparison of the miniature anion-exchange/centrifugation technique with other protozoological methods. | | 1981 | 6272458 |
| absence of detectable alteration in the kinetoplast dna of a trypanosoma brucei clone following loss of ability to infect the insect vector (glossina morsitans). | a monomorphic bloodstream population of trypanosoma brucei eatro 1244 was derived from a cloned pleomorphic parental population by 77 rapid passages through mice. loss of pleomorphism was accompanied by increased virulence of trypanosomes towards the mammal, by loss of ability to infect the tsetse fly, glossina morsitans, loss of ability to transform to the procyclic stage in vitro at 26 degrees c, and by loss of oligomycin-sensitive atpase activity in trypanosome homogenates. no differences in ... | 1981 | 6275264 |
| conservation of a variant-specific surface antigen gene in different trypanosome species and sub-species. | in trypanosoma brucie brucie, t. b. rhodesiense, t. b. gambiense and t. evansi, the variant-specific antigen (vsa) genes are organized in families of related sequences, one of which is duplicated when expressed. some of these vsa sequences appear to be conserved in the different species and sub-species: restriction mapping of isotypic genes of antat 1.8 vsa (from t. b. brucei) reveals extensive homology in t. b. rhodesiense, t. b. gambiense and t. evansi, although the genetic surrounding differs ... | 1981 | 6278302 |
| characterization of the dna duplication-transposition that controls the expression of two genes for variant surface glycoproteins in trypanosoma brucei. | the genome of trypanosoma brucei carries over a hundred genes coding for different variants of the major surface glycoprotein. activation of some of these genes is accompanied by a duplication and transposition of the gene (the basic copy) to another region in the genome where it is transcribed. we present here physical maps of the basic and transposition-activated genes for two surface glycoproteins of trypanosoma brucei, stock 427. in both cases the transposed segment starts 1-2 kb in front of ... | 1982 | 6278423 |
| analysis of genomic rearrangements associated with two variable antigen genes of trypanosoma brucei. | some variable surface glycoprotein (vsg) genes of trypanosoma brucei undergo duplication and transposition when they are expressed. we report here the cloning of cdnas coding for two vsgs from the iltar 1 repertoire. analysis of the genomes of trypanosomes expressing these and other antigens shows that there is no additional copy of the sequences coding for eight vsg in expressing clones of trypanosomes, and reveals rearrangements analogous to those previously described for the gene for another ... | 1982 | 6278436 |
| local anaesthetics including benzyl alcohol activate the adenylate cyclase in trypanosoma brucei by a calcium-dependent mechanism. | 1. the adenylate cyclase of trypanosoma brucei is activated by local anaesthetics. 2. activation of adenylate cyclase by the local anaesthetic, benzyl alcohol, requires ca2+. 3. the kinetics of the presteady state reveal that the activation step occurs prior to and is separate from the catalytic step. 4. the activation step in the presence of ca2+ can be stimulated some 200-fold and is highly co-operative with respect to benzyl alcohol concentration. 5. the mechanism by which local anaesthetics ... | 1982 | 6281006 |
| cloning and characterization of a genomic dna fragment carrying the basic copy of the gene coding for variant surface antigen 118 of trypanosoma brucei. | it has been proposed (hoeijmakers et al., 1980b) that variant surface antigen (vsa) gene expression in trypanosoma brucei is accomplished by a gene re-arrangement involving the basic copy of the vsa gene to give the so-called expression-linked copy (which is present only in the strain expressing that particular antigen). in this publication, the basic and expression-linked copies of the gene have been visualized by southern blot analysis of nuclear dna and shown to be located on hindiii fragment ... | 1982 | 6281130 |
| immunization of cattle with a variant-specific surface antigen of trypanosoma brucei: influence of different adjuvants. | nine different adjuvants were examined for their ability to potentiate the humoral and cell-mediated immune responses of cattle to a soluble glycoprotein antigen prepared from trypanosoma brucei. serological responses as measured by the farr assay were best augmented by the oil-based adjuvants and saponin. cell-mediated immunity, as assessed by specific lymphocyte transformation in vitro, was enhanced by all oil-based adjuvants at different intervals after immunization. results from a challenge ... | 1982 | 6281183 |
| incubation of trypanosome-derived mitogenic and immunosuppressive products with peritoneal macrophages allows recovery of biological activities from soluble parasite fractions. | this report describes further attempts to define the nature of the parasite product(s) responsible for the extensive changes in lymphoid tissue in mice during infection with trypanosoma brucei. as previously described, potent mitogenic and immunosuppressive effects are induced by a trypanosome-derived crude membrane fraction in vivo. there was no enrichment in these activities when purified parasite surface membranes were used. mitogenic activity can be recovered from soluble trypanosome materia ... | 1982 | 6281187 |
| characterization of the expression-linked gene copies of variant surface glycoprotein 118 in two independently isolated clones of trypanosoma brucei. | we have analysed the gene for variant surface glycoprotein 118 in eight independent clones of trypanosoma brucei, two of which express the 118 gene. expression of this gene is strictly coupled to the presence of an extra copy of the gene. in both clones the expression-linked copy is transposed to the same (or a very similar) expression site elsewhere in the genome, but the length of the sequences flanking the transposed segment in the expression site differs markedly. by means of s1 nuclease pro ... | 1982 | 6283477 |
| structure and expression of a trypanosoma brucei gambiense variant specific antigen gene. | the expression-linked copy of the t. b. gambiense variant specific antigen gene litat 1.6 is transposed in a 20 kb dna region devoid of restriction sites, located near a chromosome end. this expression site is very similar to that of t. b. brucei variants 117, 118 (1) and antat 1.8. in the basic copy, the transposable element (te) is flanked by repetitive sequences; it includes the gene copy as well as a sequence of 0.9 to 2.1 kb (probably around 1.1 kb) long, upstream from the gene. probes deri ... | 1982 | 6285289 |
| identification and partial characterization of plasma membrane polypeptides of trypanosoma brucei. | a plasma membrane-enriched vesicle fraction has been prepared from trypanosoma brucei by sonication and differential centrifugation on sucrose gradients. this fraction is enriched 5-fold in the plasma membrane marker enzymes adenyl cyclase (ec 4.6.1.1) and ouabain-inhibitable, (na+ +k+)-dependent adenosine triphosphatase (ec 3.6.1.3). it is also enriched up to 14-fold in iodinated surface proteins, and up to 4-fold in (3h-mannose-labeled glycoproteins, of which the major variable surface coat gl ... | 1982 | 6285966 |