Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| cultivation of infective forms of trypanosoma (t.) brucei evansi in a continuous culture system. | 1983 | 6837097 | |
| phagocytosis of trypanosoma brucei rhodesiense by peritoneal macrophages: a study by scanning electronmicroscopy. | phagocytosis of trypanosoma brucei rhodesiense by peritoneal macrophages takes place by seizure of the trypomastigote by either end but usually by the anterior. a lamellar sheath similar to that seen in phagocytosis of the promastigote of leishmania is observed, but it is smaller and does not proceed to envelop the living parasite. the attached trypomastigote becomes pitted and appears to have been killed and partially destroyed before it is completely engulfed. | 1983 | 6842569 |
| comparative analysis of a trypanosoma brucei gambiense antigen gene family and its potential use in epidemiology of sleeping sickness. | 1983 | 6843593 | |
| elaboration of mitochondrial function during trypanosoma brucei differentiation. | 1983 | 6843594 | |
| differential size variations between transcriptionally active and inactive telomeres of trypanosoma brucei. | we have studied the genes coding for the variant-specific surface antigen (vsa) in a series of seven trypanosome clones derived from antat 1.1: 1.1 leads to 1.3 leads to 1.6 leads to 1.16 leads to 1.1c leads to 1.3b leads to 1.18 these genes are all telomeric (1-5), and their surrounding, although sometimes similar, differs in each case. the length between these antigen genes and the corresponding dna end appears to increase at each antigenic switch, with however occasional sharp size reductions ... | 1983 | 6324074 |
| telomere conversion in trypanosomes. | activation of the gene coding for variant surface glycoprotein (vsg) 118 in trypanosoma brucei proceeds via a duplicative transposition to a telomeric expression site. the resulting active expression-linked extra copy (elc) is usually flanked by dna that lacks sites for most restriction enzymes and that is thought to interfere with the cloning of the elc as recombinant dna in escherichia coli. we have circumvented this problem by cloning an aberrant 118 elc gene, flanked at the 3'-side by at lea ... | 1983 | 6324075 |
| alternative pathway activation of complement by african trypanosomes lacking a glycoprotein coat. | an in vitro culture trypanosoma congolense cell line was established using the mammalian cell feeder layer system. one of the principle characteristics of this parasite was its ability to multiply in culture at 35 degrees c, as an uncoated trypanosome (lacking a glycoprotein surface coat) unlike the original blood stream form from which it was derived. this trypanosome was lysed when incubated in normal human serum in contrast to the parasite which possessed a surface coat. the lytic reaction as ... | 1983 | 6634218 |
| phagocytosis of antibody-sensitized trypanosoma brucei in vitro by bovine peripheral blood monocytes. | the interaction between bovine peripheral blood monocytes and trypanosoma brucei organisms in the presence of immune whole serum or specific purified igm or igg1 antibodies from infected cattle was investigated. adherence of antibody-sensitized trypanosomes to freshly isolated monocytes from non-infected animals was not observed, confirming the absence of receptors for igm and igg1 on fresh monocytes. after in-vitro cultivation of the monocytes for at least 3 hr, adherence of igm-sensitized tryp ... | 1983 | 6852873 |
| the incidence of trypanosomiasis in the cattle population situated along the peripheries of the kainji national park in nigeria. | 1983 | 6858468 | |
| size fractionation of trypanosoma brucei dna: localization of the 177-bp repeat satellite dna and a variant surface glycoprotein gene in a mini-chromosomal dna fraction. | we have size-fractionated intact dna from trypanosoma brucei into a major large dna fraction (greater than 350s) and minor middle-sized (60-250s) and small (less than 60s) dna fractions. large dna contains the rrna genes, the basic copy genes for several variant surface glycoproteins (vsgs), including one which lies near a telomer, and the expression-linked copies of the two vsg genes. the middle-sized dna contains at least one vsg gene, but the hybridization of this fraction with probes for the ... | 1983 | 6866765 |
| pathogenesis of trypanosoma brucei infection in deer mice (peromyscus maniculatus): hematologic, erythrocyte biochemical, and iron metabolic aspects. | trypanosoma brucei eatro 110 infection in deer mice (peromyscus maniculatus) produced anemia in 15 of 42 mice between postinoculation days 14 and 70. the infected anemic (ia) mice had significantly higher reticulocyte counts (p less than 0.025), spleen (p less than 0.001) and liver (p less than 0.005) weights, and higher parasitemia than did infected nonanemic (ina) mice. gamma-globulin concentrations of infected mice were markedly increased, and values for ina mice were 10% higher than values f ... | 1983 | 6869960 |
| pathogenesis of trypanosoma brucei infection in deer mice (peromyscus maniculatus): light and electron microscopic studies on erythrocyte pathologic changes and phagocytosis. | light microscopic and scanning and transmission electron microscopic studies demonstrated that trypanosoma brucei eatro 110 produced several alterations in rbc structure including microspherocytes, schistocytosis, vacuolation, doughnut-cell formation, and keratocytosis. mature rbc and reticulocytes were constantly observed to adhere firmly to trypanosomes in heart blood and in blood vessels of the testes, heart, liver, and kidney, as well as in the sinuses and pulp cords of the spleen. adhesion ... | 1983 | 6869961 |
| trypanosome infection of mice depresses antibody affinity and delays affinity maturation. | infection with either a pathogenic species of trypanosome (trypanosoma brucei brucei) or a non-pathogenic trypanosome (trypanosoma musculi) had differing effects on the response of mice to a soluble protein antigen (human serum albumin, hsa) injected in either freund's incomplete adjuvant or in saline. t. brucei suppressed the response to hsa to a level undetectable by ammonium sulphate globulin precipitation, irrespective of the mode of immunization, whereas t. musculi did not suppress the amou ... | 1983 | 6872326 |
| occurrence and role of phosphoenolpyruvate carboxykinase in procyclic trypanosoma brucei brucei glycosomes. | phosphoenolpyruvate carboxykinase (ec 4.1.1.32) was detected in a particulate fraction of trypanosoma brucei brucei procyclic culture form. it requires adp rather than gdp for activity in the direction of carboxylation and is located in the glycosomes. since phosphoenolpyruvate can serve to furnish atp for glycolysis and can promote 3-phosphoglycerate or 1,3-bisphosphoglycerate formation without simultaneous alpha-glycerophosphate production, we suggest that the glycosomal phosphoenolpyruvate ca ... | 1983 | 6877281 |
| biosynthesis of trypanosoma brucei variant surface glycoproteins - analysis of carbohydrate heterogeneity and timing of post-translational modifications. | the variant surface glycoproteins from two cloned populations of trypanosoma brucei brucei which were known to migrate as multiple bands on sds gels have been studied. the heterogeneity present was located in those oligosaccharide side chains the addition of which is tunicamycin-sensitive. the time required for the trypanosome to synthesize and express a variant surface glycoprotein molecule in vitro was found, from pulse-chase and limited trypsinisation experiments, to be approximately 40 min. ... | 1983 | 6877283 |
| trypanosoma brucei brucei infection in goats. response of peripheral blood lymphocytes to mitogen stimulation. | the in vitro proliferative response of peripheral blood lymphocytes from trypanosoma b. brucei infected goats to mitogens was studied during the course of infection. an inverse correlation was observed between the number of lymphocytes and their capacity to respond to concanavalin a, phytohemagglutinin and pokeweed mitogen. lymphocyte responsiveness to mitogens was reduced during a period of increased lymphocyte counts. during this period of time only few trypanosomes were detectable in the peri ... | 1983 | 6879709 |
| the use of the 2 substituted 5-nitroimidazole, fexinidazole (hoe 239) in the treatment of chronic t. brucei infections in mice. | relapse of chronic t. brucei infections was completely prevented by treating with either diminazene aceturate (berenil) at 40 mg/kg or suramin (germanin) at 20 mg/kg followed by four doses of the 2-substituted 5-nitroimidazole (fexinidazole) (hoe 239). none of these drugs administered singly elicited 100% permanent cures although a high percentage of the mice were cured with four doses of fexinidazole at 250 mg/kg. a single dose of 20 mg/kg suramin followed by four daily doses of 30 mg/kg fexini ... | 1983 | 6636983 |
| are there two classes of vsg gene in trypanosoma brucei? | antigenic variation in the african trypanosomes involves the sequential expression of genes coding for different variant surface glycoproteins (vsgs) (reviewed in refs 1-3). when expression of some vsg genes is switched on, a newly duplicated copy of the expressed gene has been observed within the trypanosome genome, which is not found after the gene's expression is switched off again. the duplicated copy has therefore been called an expression-linked copy (elc). the expression of the gene appea ... | 1983 | 6646202 |
| bromoacetyl-l-carnitine: biochemical and antitrypanosomal actions against trypanosoma brucei brucei. | one of the causative agents of the african trypanosamiases, trypanosoma brucei brucei is able to use high intracellular carnitine concentrations and a high carnitine acetyl transferase (cat) activity to stimulate atp production. this paper reports that a carnitine analogue, bromoacetyl-l-carnitine, is an irreversible inhibitor of cat from t.brucei, non-competitively inhibits carnitine uptake by t.brucei and has a potent in vitro effect against t.brucei motility and infectivity. an in vivo action ... | 1983 | 6651867 |
| instability of the trypanosoma brucei rhodesiense metacyclic variable antigen repertoire. | trypanosoma brucei rhodesiense undergoes antigenic variation in its mammalian host by changing the glycoprotein composing its surface coat. trypanosome clones which have the same repertoire of variable antigen types (vats) are said to belong to the same serodeme. tsetse flies infected with a particular serodeme extrude infective metacyclic trypanosomes which express only a restricted part of this repertoire. as the only known acquired immunity in african trypanosomiasis is vat-specific this limi ... | 1983 | 6656871 |
| natural agglutinins to african trypanosomes. | agglutinins to uncoated culture forms of the african trypanosomes, t. congolense and t.b. brucei were detected in sera from a variety of mammals not exposed to the parasites. the agglutinins in bovine serum were shown to be specific antibodies with opsonic properties selective for the species of trypanosome. these findings suggest a possible role for the glycoprotein coat in preventing access of cross-reacting antibodies to the plasma membrane of african trypanosomes. | 1983 | 6657292 |
| [campaign against sleeping sickness due to trypanosoma brucei gambiense]. | 1983 | 6601542 | |
| trypanosomal surface coat variant antigen causes polyclonal lymphocyte activation. | variant antigen, the primary component of the surface coat of the salivarian trypanosome, when injected i.v. into mice at dosages encountered during acute infections, produced some of the immunopathogenic phenomena associated with acute african trypanosomiasis. trypanosome-infected and variant antigen-treated mice had splenomegaly caused by proliferation of null cells, b and t lymphocytes, and macrophages. splenic b lymphocytes were nonspecifically activated to produce antibodies to sheep erythr ... | 1983 | 6604754 |
| influence of trypanosoma (t.) brucei brucei infection on delayed-type hypersensitivity to sheep red blood cells in mice. | 1983 | 6615046 | |
| trypanosome antigen-antibody complexes and immunoconglutinin interactions in african trypanosomiasis. | 1983 | 6618755 | |
| human plasma resistant strain of trypanozoon isolated from cattle in gamo gofa. | 1983 | 6628371 | |
| further evidence for the existence of a membrane potential in trypanosoma brucei brucei. | the distribution of 137cs+, in the presence of valinomycin, has been used to measure the magnitude of the membrane potential (delta psi) in bloodstream forms of trypanosoma brucei brucei. values of the delta psi falling in the range -100 mv to -160 mv were observed and the maintenance of this delta psi was sensitive to certain ionophores and protonophores. | 1983 | 6631418 |
| comparison of the expression-linked extra copy (elc) and basic copy (bc) genes of a trypanosome surface antigen. | a recombinant clone of an expression-linked extra copy (elc) gene of a trypanosome-variable surface glycoprotein was sequenced. in addition the sequences of the corresponding cdna and portions of the two basic copy genes were determined. comparison of these sequences reveals that the 5' boundary of the elc-transposed segment (2.2 kb) occurs within a repetitive sequence about 700 bp upstream from the start codon of the coding sequence. this sequence does not contain internal symmetries and is not ... | 1983 | 6327735 |
| mitochondrial dna of an african trypanosome. | the maxicircles of african trypanosome kdna are the genetic equivalent of other mitochondrial dnas, but the function of minicircles is unknown. the maxicircle of trypanosoma brucei 164 encodes conventional mitochondrial gene products and is largely but not completely transcribed. nucleotide sequence analysis of a region not found to be transcribed revealed numerous translation termination codons in all three reading frames of both strands and numerous inverted repeats, suggesting that this segme ... | 1983 | 6327737 |
| the use of 75-seleno-methionine labelled trypanosoma brucei to measure parasite replication in vivo. | the suitability of 75-se-labelled trypanosomes for the measurement of trypanosome replication rates in vivo was investigated. the principle used to estimate the doubling time of the circulating parasites was the decrease in specific activity of 10(-7) parasites and this was determined both for parasites contained in a whole blood sample and for parasites separated from the blood sample by deae-cellulose chromatography. when two stocks of t. brucei (treu 226, treu 667) were compared it was found ... | 1983 | 6636301 |
| isolation of human serum resistant trypanozoon from cattle in nigeria. | four trypanosome stocks of the subgenus trypanozoon were isolated from a herd of cattle in the jos plateau of nigerian during a study on the epizootiology of trypanosomiasis. one of the stocks was repeatedly highly resistant to normal human serum (blood incubation infectivity test), indicating potential human infectivity. these observations suggest that the domestic cattle might act as reservoir hosts for the causative agent of human trypanosomiasis. | 1983 | 6636302 |
| pathogenesis of trypanosoma brucei infection in deer mice (peromyscus maniculatus). v. macrophage ultrastructure and function. | macrophage numbers increased in the spleen, liver, testes, heart, and kidney of deer mice infected for seven to ten weeks with trypanosoma brucei eatro 110. the macrophages were activated as indicated by their increased size and significant increases in numbers of cell organelles including profiles of rough endoplasmic reticulum (which also increased in length), mitochondria, primary and secondary lysosomes, bundles of golgi's apparatus, and free lysosomes compared to macrophages from control mi ... | 1983 | 6636469 |
| interaction of high-density lipoprotein with trypanosoma brucei: effect of membrane stabilizers. | the specific lysis of bloodstream trypanosomes by serum from a nonpermissive mammalian host is the result of interaction between the serum trypanocidal factor (high-density lipoprotein) and the trypanosome surface. the studies described in this paper attempt to define further the mode of action of this cytotoxic lipoprotein. the binding of high-density lipoprotein to trypanosoma brucei was instantaneous at 4 degrees c and readily reversible. binding was not mediated by the surface glycoprotein a ... | 1983 | 6327740 |
| inefficacy of metronidazole in experimental infections of leishmania donovani, l. mexicana, and trypanosoma brucei brucei. | metronidazole has been claimed in several earlier reports to be active in human cases of leishmaniasis and trypanosomiasis. its efficacy against the protozoa causing these diseases was tested in hamsters infected with leishmania mexicana or l. donovani, and in mice infected with trypanosoma brucei brucei. in separate experiments, hamsters were either inoculated intradermally into the nose with 5 million amastigotes of l. mexicana or intracardially with 10-30 million amastigotes of l. donovani, a ... | 1983 | 6305218 |
| antibody levels during bovine hemoparasitic diseases: trypanosomiasis, anaplasmosis, and babesiosis. | 1983 | 6399967 | |
| the role of threonine in the metabolism of acetyl coenzyme a by trypanosoma brucei brucei. | 1983 | 6403282 | |
| locations of the six disulphide bonds in a variant surface glycoprotein (vsg 117) from trypanosoma brucei. | the locations of the six disulphide bonds and the single free cysteine residue in a variant surface glycoprotein, vsg 117, from the african trypanosome trypanosoma brucei have been determined to be cys-14--cys-140, cys-121--cys-182, cys-389--cys-404, cys-398--417, cys-447--cys-461 and cys-455--cys-468. cys-244 bears the single thiol group, which is unreactive towards 2-nitro-5-thiocyanobenzoate in the native molecule and is probably buried. biosynthetically incorporated [35s]cysteine aided the l ... | 1983 | 6405739 |
| characterisation of the cross-reacting carbohydrate groups on two variant surface glycoproteins of trypanosoma brucei. | the nature of the cross-reacting groups on two variant surface glycoproteins of trypanosoma brucei has been investigated after isolation of glycopeptides produced by extensive proteolytic digestion of the proteins. one variant yielded two glycopeptides after pronase digestion, one of which was the glycosylated c-terminal aspartic acid. in a second variant there are two carbohydrate groups close to the c-terminus. considerable heterogeneity in the size of the sugar attached to an asparagine resid ... | 1983 | 6410233 |
| micro-counterimmunoelectrophoresis: a rapid screening technique for trypanosomiasis. | a rapid and economical micro-counterimmunoelectrophoresis (mcie) test, for antibody to trypanosome antigens, has been developed which may prove useful in trypanosomiasis surveillance. mcie was more sensitive and more rapid than immunodiffusion (id). serum samples from trypanosome-infected rabbits and cattle (nigerian and gambian), from kuwaiti dogs and camels, from ivory coast sleeping sickness patients, from brazilian patients with chagas's disease, plus mouse-anti-malaria sera have been tested ... | 1983 | 6415874 |
| comparative aspects of purine metabolism in some african trypanosomes. | some enzymes of purine salvage were detected in the cell-free preparations from bloodstream forms of african trypanosomes: trypanosoma vivax; t. brucei and t. congolense. extracts of trypanosomes cleave adenosine and inosine hydrolytically except in t. congolense where adenosine cleavage was mediated by a phosphorylase. all the trypanosomes apparently lacked adenosine deaminase. adenine aminohydrolase was found only in t. vivax while adenosine monophosphate deaminase was detected in t. brucei an ... | 1983 | 6419098 |
| a comparative study of the proteolytic enzymes of trypanosoma brucei, t. equiperdum, t. evansi, t. vivax, leishmania tarentolae and crithidia fasciculata. | four types of proteolytic activity were detected in the bloodstream form of each of the four trypanosoma species: (i) hpaase, active on hide powder azure and detected on polyacrylamide gels containing denatured haemoglobin; (ii) azcase, active on azocasein; (iii) type 1, active on the chromogenic peptide n-benzoyl-l-prolyl-l-phenylalanyl-l-arginine p-nitroanilide in the presence of dithiothreitol, and (iv) type 2, active against several nitroanilide derivatives in the absence of dithiothreitol. ... | 1983 | 6366547 |
| 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 |
| 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 |
| 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 |
| iron-containing superoxide dismutase from crithidia fasciculata. purification, characterization, and similarity to leishmanial and trypanosomal enzymes. | leishmania tropica, trypanosoma brucei, trypanosoma cruzi, and crithidia fasciculata have superoxide dismutases which are insensitive to cyanide and sensitive to peroxide and azide, properties characteristic of iron-containing superoxide dismutase. studies on the superoxide dismutase of c. fasciculata have revealed that: 1) the enzyme is located in the cytosol; 2) isozymes exist; 3) the major superoxide dismutase isozyme (superoxide dismutase 2) has mr approximately equal to 43,000 and consists ... | 1983 | 6336744 |
| an em study on cerebral trypanosomiasis in rodents and primates. | 1983 | 6337775 | |
| a physiological mechanism to explain pathogenesis in african trypanosomiasis. | 1983 | 6337778 | |
| extravascular and vascular distribution of trypanosoma b. gambiense in microtus montanus after cyclical transmission. | 1983 | 6337779 | |
| characterization of satellite dna in trypanosoma brucei and trypanosoma cruzi. | we have determined the properties of the simple-sequence satellite dnas from two protozoa, trypanosoma brucei and trypanosoma cruzi. the t. brucei satellite dna contains 29 mol% guanine plus cytosine and is made up of long tandem arrays of a 177 base-pair repeat. sequence heterogeneity in these repeats is limited and restricted to certain positions as shown by sequence analysis, restriction enzyme digestion and two-dimensional analysis of nucleotides bordering the alui and hhai recognition sites ... | 1983 | 6345792 |
| sexual processes in the kinetoplastida. | the commonly held view that the kinetoplastida, and in particular trypanosomes, are asexual is largely derived from the principle that an organism is asexual until proved sexual. if the basis for this view is examined in detail, it largely arises from the lack of morphologically distinguishable gametes, the difficulties encountered in visualizing chromosomes and a few experiments, using drug-resistant stocks, in which no recombination between stocks could be demonstrated. while it is clear that ... | 1983 | 6346233 |
| the polypeptide profiles of strains of the trypanosoma subgenera schizotrypanum and trypanozoon: peptideme characterization. | examination, by sds-page, of the polypeptide profiles of 36 brazilian strains of trypanosoma (schizotrypanum) cruzi has revealed five peptidemes (subpopulations having similar polypeptide profiles) recognizing differences not apparent from zymodeme analysis. t. cruzi zymodeme (z)1 has been subdivided into peptidemes 3, 4 and 5 (one example of z2 was included in peptideme 5). peptideme 1 consisted mostly of z2 strains except for one example each of z1 and z3. one strain of z2 (tc 003) was suffici ... | 1983 | 6353688 |
| [antigenic variation of trypanosoma brucei with reference to the serodiagnosis of sleeping sickness]. | 1983 | 6364615 | |
| 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 |
| 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 |
| sequences homologous to the variant antigen mrna spliced leader are located in tandem repeats and variable orphons in trypanosoma brucei. | we have examined the organization of genomic sequences homologous to the spliced leader of trypanosoma brucei variant surface glycoprotein (vsg) mrna, using a synthetic oligodeoxynucleotide probe. these sequences are highly reiterated in the trypanosome genome and most are located in 1.4 kb units arranged in a direct tandem repeat. however, some of the 1.4 kb sequences are dispersed from the cluster(s) of tandem repeats and are flanked by non-repeat dna. the number and arrangement of these leade ... | 1983 | 6313213 |
| purification and properties of dihydroorotate oxidase from crithidia fasciculata and trypanosoma brucei. | dihydroorotate oxidases have been highly purified from the parasitic protozoa crithidia fasciculata and trypanosoma brucei. the crithidia enzyme was purified 4200-fold from a crude soluble protein extract in four steps. the protein is a dimer as judged from the native (mr 60 000) and subunit (mr 32 700) molecular weights. the purified enzyme exhibits a characteristic flavin electronic spectrum, and each mole of native dimer contains 1.0 mol of tightly bound flavin mononucleotide. under anaerobic ... | 1983 | 6299333 |
| relationship between multiple copies of a t. brucei variable surface glycoprotein gene whose expression is not controlled by duplication. | unlike many other t. brucei variable surface glycoprotein (vsg) genes, the iitat 1.3 gene is not duplicated when it is expressed. analysis of the multiple copies of this gene present in all iitar 1 trypanosome clones by restriction enzyme mapping and sequencing shows that the expressed copy may have arisen by duplication and transposition to a telomeric site, as is observed for those vsg genes whose expression is linked to duplication. the existence of a mechanism selecting between a number of c ... | 1983 | 6301682 |
| macrophage activation in murine african trypanosomiasis. | african trypanosomiasis is accompanied by a profound general immunosuppression in which both suppressive t cells and macrophages (m phi) have been implicated. the present studies define changes in the m phi surface, endocytic and secretory properties, during the infection of mice by trypanosoma brucei. peritoneal m phi obtained after the control of the first wave of parasitemia displayed characteristics similar to those activated by intracellular pathogens, such as mycobacterium bovis bacillus c ... | 1983 | 6301989 |
| 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 |
| the major transcripts of the kinetoplast dna of trypanosoma brucei are very small ribosomal rnas. | the nucleotide sequence has been determined of a 2.2 kb segment of kinetoplast dna, which encodes the major mitochondrial transcripts (12s and 9s) of trypanosoma brucei. the sequence shows that the 12s rna is a large subunit rrna, although sufficiently unusual for resistance to chloramphenicol to be predicted. the 9s rna has little homology with other rrnas, but a possible secondary structure is not unlike that of the 2.5-fold larger e. coli 16s rrna. we conclude that the 12s rna (about 1230 nuc ... | 1983 | 6306559 |
| comparison of maxicircle dnas of leishmania tarentolae and trypanosoma brucei. | the conserved portions of the maxicircle dnas of leishmania tarentolae and trypanosoma brucei are organized in a basically colinear manner over a 15- to 17-kilobase region that is interrupted by two small less-homologous sequences. the most highly conserved regions are those encoding the 9s and 12s genes. an approximately 12-kilobase region directly upstream of the 12s gene in the l. tarentolae maxicircle showed no sequence homology with the t. brucei maxicircle and also was not transcribed. an ... | 1983 | 6306661 |
| tubulin genes of trypanosoma brucei: a tightly clustered family of alternating genes. | african trypanosomes are the causative agents of many medically and economically important diseases of man and domestic animals. the cell body of these blood-dwelling protozoa is enveloped with a dense layer of pellicular microtubules, which confer both motility and mechanical stability on these cells; microtubules are also important components of the flagellum. the major structural components of the microtubuli are two related proteins, alpha- and beta-tubulin. we have analyzed the genomic orga ... | 1983 | 6308633 |
| generation of overlapping labeled dna fragments for dna sequencing: a mercury-thiol affinity system. | 1983 | 6312253 | |
| tandem repetition of the 5' mini-exon of variant surface glycoprotein genes: a multiple promoter for vsg gene transcription? | activation of some variant surface glycoprotein (vsg) genes involves a duplicative transposition to an expression site, which completes the gene by addition of a mini-exon coding for the 5' 35 nucleotides of vsg mrnas. using a 22 nucleotide probe we have found some 200 copies of the mini-exon on a tandemly arranged 1.35 kb repetitive element. this repeat is highly conserved in three trypanosome species. the mini-exon on the repeat is flanked by a 5' splice site that resembles the consensus seque ... | 1983 | 6313212 |
| activation of the genes for variant surface glycoproteins 117 and 118 in trypanosoma brucei. | we have studied the activation of genes for vsgs (variant surface glycoproteins) in trypanosoma brucei (strain 427) in six independently isolated trypanosome clones; four expressing the gene for vsg 118 and two the gene for vsg 117. in all cases, gene activation is brought about by a duplicative transposition of the gene to an expression site located close to the end of a chromosome. the dna segments flanking the expression-linked extra gene copy are nearly devoid of restriction enzyme recogniti ... | 1983 | 6306248 |
| gene activation and re-expression of a trypanosoma brucei variant surface glycoprotein. | the expression of the trypanosoma brucei variant surface glycoprotein antat 1.1 proceeds by a mechanism that transfers a duplicated gene copy into a new genomic environment, the so-called expression site, where it will be expressed. we have isolated a genomic fragment containing the region spanning the expression site-transposon junction, and the 5' half of the coding sequence. comparing this dna segment with its template copy (basic copy) allowed us to identify the exact breaking point and indi ... | 1983 | 6313354 |
| the nucleotide sequence of a segment of trypanosoma brucei mitochondrial maxi-circle dna that contains the gene for apocytochrome b and some unusual unassigned reading frames. | the nucleotide sequence of a 2.5-kb segment of the maxi-circle of trypanosoma brucei mtdna has been determined. the segment contains the gene for apocytochrome b, which displays about 25% homology at the amino acid level to the apocytochrome b gene from fungal and mammalian mtdnas. northern blot and s1 nuclease analyses have yielded accurate map positions of an rna species in an area that coincides with the reading frame. the segment also contains two pairs of overlapping unassigned reading fram ... | 1983 | 6314266 |
| the enzymes of purine salvage in trypanosoma cruzi, trypanosoma brucei and leishmania mexicana. | we have previously shown the presence of various purine salvage enzymes in trypanosoma cruzi, including phosphoribosyltransferase, aminohydrolase, kinase, phosphorylase and hydrolase activities. we now report that a similar situation occurs in leishmania mexicana amazonensis and trypanosoma brucei brucei. in all three organisms we found higher levels of activity for the phosphoribosyltransferase enzymes than for the nucleoside kinases, suggesting a preference for the salvage of purine bases rath ... | 1983 | 6316234 |
| the transposition unit of variant surface glycoprotein gene 118 of trypanosoma brucei. presence of repeated elements at its border and absence of promoter-associated sequences. | at the dna level, antigenic variation in trypanosomes is brought about by the replacement of one variant surface glycoprotein (vsg) gene by another in an expression site with a strong promoter. in several cases studied, mobilization of a vsg gene for expression involves a duplication-transposition. we have determined the dna sequence of most of the transposed segment of one such vsg, the vsg 118. at the 3' side, the transposed segment ends within the end of the gene; at the 5' side, the transpos ... | 1983 | 6306255 |
| 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 |
| 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 |
| 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 |
| 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 |
| [characterization of the antigenic index antar 5 of trypanosoma brucei brucei]. | 1983 | 6197941 | |
| 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 |
| antitrypanosomal activity of sinefungin. | sinefungin, a naturally occurring antifungal antibiotic nucleoside containing an ornithine residue, linked by a c-c bond to c-5' of adenosine, cures mice infected with trypanosoma brucei brucei, t. congolense, or t. vivax; the effect of the drug is more pronounced towards t. congolense. anti-trypanosomal activity of sinefungin could be the result of the inhibition of transmethylation reactions or of polyamine biosynthesis--or both--in parasites. | 1983 | 6130709 |
| 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 |
| 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 |
| 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 | |
| topological analysis of antigenic determinants on a variant surface glycoprotein of trypanosoma brucei. | nine monoclonal antibodies specific for the variant surface glycoprotein (vsg) of trypanosoma brucei mitat 1.6 have been produced and characterised as part of a coordinated project to define the three dimensional structure and immunological profile of this and other vsg molecules. competition radioimmunoassays using all combinations of these antibodies identified five distinct antigenic determinants, showing varying degrees of overlap, on the mitat 1.6 vsg molecule. a map has been constructed of ... | 1984 | 6083452 |
| 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 |
| 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 |
| the inactivation and reactivation of an expression-linked gene copy for a variant surface glycoprotein in trypanosoma brucei. | we have previously shown that the gene for variant surface glycoprotein 118 of trypanosoma brucei (strain 427) is activated by a duplicative transposition to a telomeric expression site. in chronically-infected animals, this expression-linked copy is lost when the 118 gene is replaced at the expression site by another variant surface glycoprotein gene. we show here that expression of the 118 gene can also be switched off without loss of the extra expression-linked copy. in two variants, called 1 ... | 1984 | 6086319 |
| possible dna modification in gc dinucleotides of trypanosoma brucei telomeric sequences; relationship with antigen gene transcription. | polymorphism in restriction site cleavage (psti, sphi, pvuii, hindiii) has been noticed in several occasions in the telomeric sequences harbouring trypanosome variant-specific antigen genes (1, 2, 3). this polymorphism has been further investigated and seems best interpreted as due to partial dna modification in gc dinucleotides. the actively transcribed telomeric genes do not exhibit such a polymorphism; furthermore, in at least three independent cases, gene inactivation is linked to the appear ... | 1984 | 6087278 |
| trypanosome mrnas share a common 5' spliced leader sequence. | a 5'-terminal leader sequence of 35 nucleotides was found to be present on multiple trypanosome rnas. based on its representation in cdna libraries, we estimate that many, if not all, trypanosome mrnas contain this leader. this same leader was originally identified on mrnas encoding the molecules responsible for antigenic variation, variant surface glycoproteins. studies of selected cdnas containing this leader sequence revealed that leader-containing transcripts can be stage-specific, stage-reg ... | 1984 | 6088073 |
| apparent discontinuous transcription of trypanosoma brucei variant surface antigen genes. | the repeated mini-exon sequence that encodes the first 35 base pairs of all variant surface antigen mrnas of trypanosoma brucei directs the synthesis of a discrete 137-nucleotide transcript. it thus seems that variant surface antigen mrnas are transcribed discontinuously, and we present two alternative models for how this might occur. | 1984 | 6090933 |
| identification of a small rna containing the trypanosome spliced leader: a donor of shared 5' sequences of trypanosomatid mrnas? | the 35 nucleotide spliced leader (sl) sequence is found on the 5' end of numerous trypanosome mrnas, yet the tandemly organized reiteration units encoding this leader are not detectably linked to any of these structural genes. here we report the presence of a class of discrete small sl rna molecules that are derived from the genomic sl reiteration units of trypanosoma brucei, trypanosoma cruzi, and leptomonas collosoma. these small sl rnas are 135, 105, and 95 nucleotides, respectively, and cont ... | 1984 | 6091897 |
| translocation alters the activation rate of a trypanosome surface antigen gene. | we report here the characterization of the gene coding for antat 1.13, a very late variable antigen type (vat) from trypanosoma b. brucei. this gene is chromosome-internal and it is activated by the duplicative mechanism. like in another case of late vat expression (1), its expression-linked copy (elc) is flanked by "companion" sequences. it was possible to convert the late expression of this vat into an early one, by changing the location of the gene in the genome. this has been achieved by sel ... | 1984 | 6095196 |
| responsiveness of the rat vas deferens to catecholamines and electrical stimulation during an infection with trypanosoma brucei. | the effect of an acute infection with trypanosoma brucei on the reactivity of the rat vas deferens to noradrenaline, tyramine and field stimulation was studied. the vas deferens isolated from infected animals was more responsive to field stimulation than control rat vas deferens. the effect was more noticeable at lower frequencies of stimulation suggesting an increased sympathetic discharge from presynaptic nerve endings. also both noradrenaline and tyramine were more effective on the infected v ... | 1984 | 6099973 |
| the istat 1.3 vsg multigene family in trypanosoma brucei: retention of the expression linked copy through multiple antigenic switches. | in the istar 1 serodeme of t. brucei the 3 variant surface glycoprotein (vsg) gene family contains about 10 members, one of which has a telomeric location on a minichromosome. the expression linked copy (elc) of the 3 vsg gene which occurs in an antigenic variant expressing the 3 vsg, also has a telomeric location but unlike the minichromosomal 3 vsg gene has restriction sites upstream from the 5' barren region. this elc is retained on the same telomere in a subsequent variant that expresses a t ... | 1984 | 6083548 |
| mapping of antigenic determinants within peptides of a variant surface glycoprotein of trypanosoma brucei. | the location of antigenic determinants in the primary amino acid sequence of the variant surface glycoprotein of trypanosoma brucei mitat 1.6 was investigated using monoclonal antibodies in conjunction with the known cyanogen bromide and tryptic cleavage patterns of this antigen. the cyanogen bromide digestion fragments of the antigen were purified and used to raise polyclonal antisera, which were specific for the appropriate cyanogen bromide fragment and partial digestion products, as well as r ... | 1984 | 6084814 |