| trypanosoma brucei mitochondrial ribosomal rna synthesis, processing and developmentally regulated expression. | the steady-state levels of the mitochondrial ribosomal rnas of trypanosoma brucei are repressed in the early bloodstream developmental stage of the parasite and accumulate approximately 30-fold during differentiation to the stage found in the midgut of the insect vector. in order to determine the mechanism regulating this developmental process, we have examined the transcription and processing of the 9s and 12s mitochondrial rrnas of t. brucei. a short-lived rna was detected in pulse labeling ex ... | 1992 | 1381496 |
| identification of nuclear encoded precursor trnas within the mitochondrion of trypanosoma brucei. | rnas that function in mitochondria are typically encoded by the mitochondrial dna. however, the mitochondrial trnas of trypanosoma brucei are encoded by the nuclear dna and therefore must be imported into the mitochondrion. it is becoming evident that rna import into mitochondria is phylogenetically widespread and is essential for cellular processes, but virtually nothing is known about the mechanism of rna import. we have identified and characterized mitochondrial precursor trnas in t. brucei. ... | 1992 | 1385429 |
| nitric oxide mediates suppression of t cell responses in murine trypanosoma brucei infection. | african trypanosomes induce a generalized state of immunosuppression in their mammalian hosts. one characteristic of this is a suppression of lymphocyte responses to mitogen, which is mediated by suppressor macrophages. we investigated the involvement of nitric oxide in this phenomenon. both peritoneal and splenic cell cultures from infected mice released nitrite and this was inhibitable by ng-monomethyl l-arginine (l-nmma). the release of nitrite correlated with suppressed splenic t cell prolif ... | 1992 | 1396977 |
| immunological characterization and intracellular localization of trans-spliceosomal small nuclear ribonucleoproteins in trypanosoma brucei. | polyclonal antibodies were raised against purified protein components of the u2 small nuclear ribonucleoprotein (snrnp) from trypanosoma brucei. through immunoblot and immunoprecipitation analyses three antisera were characterized that reacted specifically with u2 snrnp proteins of molecular weights 40,000 (anti-40k) and 16,500 (anti-16.5k), and with each of four proteins of molecular weights 14,000, 12,500, 10,000, and 8,500 (anti-cp). anti-40k antibodies specifically immunoprecipitated the u2 ... | 1992 | 1400334 |
| trypanosoma brucei spliced-leader rna methylations are required for trans splicing in vivo. | the trypanosoma brucei spliced leader (sl) rna donates its 5' leader sequence to all nuclear pre-mrnas via trans rna splicing. the sl rna is a small-nuclear u rna-like molecule which is present in the cell as part of a small ribonucleoprotein particle. however, unlike the trimethylguanosine-capped small nuclear u rnas, the sl rna has a highly modified 5' terminus containing an m7g cap and methylations on the first four transcribed nucleotides. here, we show that incubation of procyclic-form t. b ... | 1992 | 1406666 |
| inhibitory effect of trypanosoma brucei brucei on glossina morsitans midgut trypsin in vitro. | the ability of trypanosoma brucei brucei to inhibit trypsin or trypsin-like enzymes in crude midgut homogenates of glossina morsitans morsitans was studied in vitro. the isolated parasites caused a concentration-dependent decrease in midgut trypsin activity. furthermore, trypanosomes lysed by repeated freeze-thawing had a similar effect on trypsin activity. in both cases, the inhibition by either intact or lysed parasites was partial as revealed by dixon plots. similarly, trypanosome membrane pr ... | 1992 | 1409526 |
| developmental regulation of nuclear gene expression in trypanosoma brucei. | | 1992 | 1410447 |
| the response of pigs experimentally infected with trypanosoma brucei to isometamidium chloride therapy and the relation to nutrition. | growing pigs were placed on feeds with high (group a), medium (b) and low (c) dietary energy and were infected with a virulent stock of t. brucei. eight weeks later, the infected pigs were treated with isometamidium chloride at 1 mg/kg live weight and all pigs were subsequently placed on a high energy diet to investigate their response to therapy. clearance of t. brucei from blood was completed 72h after treatment. there was no evidence of relapsed infection up to eight weeks after treatment. re ... | 1992 | 1413445 |
| effects of infection with trypanosoma brucei brucei on different trimesters of pregnancy in ewes. | the effects of trypanosoma brucei brucei infection during the first, second or third trimesters of pregnancy in 13 ewes were studied. all infected ewes were anaemic with the anaemia being most severe, moderate and least in ewes infected in the second, third and first trimesters, respectively. weight loss occurred in all infected ewes but was most severe in ewes infected in the third trimester. three of the four ewes infected in the first trimester died without aborting while one aborted and late ... | 1992 | 1413452 |
| mechanisms underlying trypanosome-elicited immunosuppression. | t-cell proliferative responses of lymph node cells are profoundly suppressed during experimental infections of mice with trypanosoma brucei. the active suppression of lymph node t-cell proliferative responses is attributed to the coexistence of at least two unlinked suppressive mechanisms that block different t-cell regulatory steps and operate through different effector mechanisms. the generation of prostaglandin-producing macrophages is entirely responsible for the suppression of il-2 producti ... | 1992 | 1417167 |
| the predominant calcimedins from trypanosoma brucei comprise a family of flagellar ef-hand calcium-binding proteins. | the cellular complement of calcimedins was identified in trypanosoma brucei by ca(2+)-dependent association with phenyl-sepharose. predominant calcimedins with molecular mass of 23-26 kda and 44 kda, along with minor calcimedins of 96, 120 and 230 kda, were obtained. the trypanosome calcimedins were unrelated to vertebrate annexins, based upon antibody cross-reactivity and an inability to associate in a ca(2+)-dependent way with phospholipid vesicles comprised of phosphatidylserine or phosphatid ... | 1992 | 1417772 |
| nitric oxide-mediated cytostatic activity on trypanosoma brucei gambiense and trypanosoma brucei brucei. | macrophages collected from bcg-infected mice or exposed in vitro to interferon-gamma plus lipopolysaccharide developed a cytostatic activity on trypanosoma brucei gambiense and trypanosoma brucei brucei. this trypanostatic activity of activated macrophages was inhibited by addition of n-monomethyl-l-arginine, an inhibitor of the l-arginine-nitric oxide (no) metabolic pathway, indicating a role for no as the effector molecule. contrary to trypanosomes treated with n2gas, trypanosomes treated with ... | 1992 | 1426137 |
| an enzyme-linked immunosorbent assay (elisa) for the detection of trypanosomal antigens in goat serum using a monoclonal antibody. | an igm murine monoclonal antibody (mab) tea 1/23.3.4.6 raised against circulating trypanosome antigens was used in a sandwich elisa to assay trypanosomal antigens in a trypanosome lysate preparation and in sera from goats infected with trypanosoma brucei evansi. as little as 1.25 ug/ml of trypanosomal antigen could be detected by this assay. following infection, trypanosomal antigens were first detected in goat serum 24 hours after the intravenous (i/v) or 6 days after the intramuscular (i/m) in ... | 1992 | 1430240 |
| astrocyte activation correlates with cytokine production in central nervous system of trypanosoma brucei brucei-infected mice. | during the late-stage disease associated with human african trypanosomiasis, caused by infection with either trypanosoma gambiense or t. rhodesiense, parasites invade the central nervous system (cns), eventually leading to development of cns pathology. this can be exacerbated by subcurative chemotherapy. the mechanisms through which the inflammatory processes within the cns are controlled remain unclear. | 1992 | 1434541 |
| a procyclin-associated gene in trypanosoma brucei encodes a polypeptide related to esag 6 and 7 proteins. | the procyclin genes of trypanosoma brucei encode a family of glycoproteins expressed on the surface of procyclic forms of the parasite. these genes are present at different loci in tandem arrays of two or three copies depending on the strain. it has previously been shown that procyclin genes are transcribed from a promotor immediately upstream of the first procyclin gene in each cluster by an rna polymerase that is resistant to high levels of alpha-amanitin. here we show that additional genes, w ... | 1992 | 1435865 |
| the electrochemical proton gradient in the bloodstream form of trypanosoma brucei is dependent on the temperature. | the membrane potential and ph gradient over the plasma membrane of the protozoan parasite trypanosoma brucei were measured with radioactive indicators in combination with the silicone oil centrifugation technique over a range of temperatures. at 37 degrees c a small membrane potential and ph gradient of similar magnitude, but of opposite polarity, were measured. the resulting electrochemical proton gradient was almost zero. however, when the temperature was lowered from 37 degrees c to 22 degree ... | 1992 | 1435870 |
| the translation initiation site of recombinant trypanosoma brucei ornithine decarboxylase varies with different promoters. | expression of the trypanosoma brucei ornithine decarboxylase (odc) gene in escherichia coli behind the lambda phage pr promoter led to the production of a recombinant enzyme having the same subunit molecular weight as the native enzyme [4]. however, when the same gene is expressed behind the tac promoter or the phoa promoter, the odcs produced by the transformed e. coli have subunit molecular weights approximately 2 kda higher than that of the native enzyme. amino terminal sequencing of the reco ... | 1992 | 1435879 |
| sequence differences between histones of procyclic trypanosoma brucei brucei and higher eukaryotes. | four histones, a, b, c, d from procyclic trypanosoma brucei brucei, which show similarities with the amino acid composition of the core histones h3, h2a, h2b and h4, were isolated and cleaved with endoproteinase glu-c. the fragments were separated by fplc reversed phase chromatography and a subset of the fragments (a5, a9, b6, c8, d3, d9, d11) was subjected to sequence analysis. a 54-71% identity was found in the sequences of the fragment c8 and the c-terminal half of h2b and of three fragments ... | 1992 | 1437281 |
| histone-dna interactions in the chromatin of procyclic trypanosoma brucei brucei. | the dissociation of histone proteins a-d from the chromatin of trypanosoma brucei brucei procyclic culture forms was investigated by removing the proteins from the dna by centrifugation of soluble chromatin through isokinetic sucrose gradients in the presence of nacl. the dissociation of the t. b. brucei histones was compared with that of their higher-eukaryote counterparts h3, h2a, h2b and h4. all four histones of t. b. brucei remained bound to the dna at 500 mm nacl, were partially released at ... | 1992 | 1438135 |
| changes in atrial natriuretic factor and plasma renin activity in dogs infected with trypanosoma brucei. | when beagle dogs were infected with trypanosoma brucei, a marked reduction in the plasma concentration of atrial natriuretic factor (anf) occurred in the terminal stage of the disease during weeks 3 and 4. at the same time there was an increase in plasma renin activity (pra) after infection. ultrastructural studies of the atria of these dogs demonstrated a reduction in anf granules. the changes in anf and pra occurred in association with severe pancarditis and the development of heart failure. b ... | 1992 | 1438145 |
| glycosome assembly in trypanosomes: variations in the acceptable degeneracy of a cooh-terminal microbody targeting signal. | trypanosomes compartmentalize most of their glycolytic enzymes in a peroxisome-like microbody, the glycosome. the specificity of glycosomal targeting was examined by expression of chloramphenicol acetyltransferase fusion proteins in trypanosomes and monkey cells. compartmentalization was assessed by cell fractionation, differential detergent permeabilization, and immunofluorescence. the targeting signal of trypanosome phosphoglycerate kinase resides in the cooh-terminal hexapeptide, nrwssl; a ba ... | 1992 | 1447292 |
| molecular characterization of the trypanothione reductase gene from crithidia fasciculata and trypanosoma brucei: comparison with other flavoprotein disulphide oxidoreductases with respect to substrate specificity and catalytic mechanism. | trypanothione reductase belongs to the family of flavoprotein disulphide oxidoreductases that include glutathione reductases, dihydrolipoamide dehydrogenases and mercuric reductases. trypanothione reductase and its substrate, trypanothione disulphide, are unique to parasitic trypanosomatids responsible for several tropical diseases. the crystal structure of the enzyme from crithidia fasciculata is currently under investigation as an aid in the design of selective inhibitors with a view to produc ... | 1992 | 1453951 |
| affected paroxysmal nocturnal hemoglobinuria t lymphocytes harbor a common defect in assembly of n-acetyl-d-glucosamine inositol phospholipid corresponding to that in class a thy-1- murine lymphoma mutants. | deficient expression of glycoinositol phospholipid (gpi) anchored proteins in affected paroxysmal nocturnal hemoglobinuria (pnh) cells has been traced to a defect in gpi anchor assembly. in a previous study (schubert, j., schmidt, r. e., and medof, m. e. (1993) j. biol. chem., in press) we characterized the biosynthesis of putative man-containing gpi anchor precursors in normal peripheral blood lymphocytes and investigated assembly of these intracellular gpi intermediates in cd48- affected and c ... | 1992 | 1460030 |
| impairment of growth of leishmania donovani by trypanosoma brucei during co-culture. | cells of leishmania donovani in co-culture with trypanosoma brucei, were severely affected in their growth, resulting in swelling and subsequent lysis. similar effects were also observed when crithidia luciliae or phytomonas sp. were co-cultured with t. brucei. direct contact between the cells under investigation and t. brucei was necessary because t. brucei did not hamper the growth of the other trypanosomatids, when separated by a filter with 0.2 microns pore size. examination of this phenomen ... | 1992 | 1461680 |
| transgenic mice expressing human apolipoprotein a-i have sera with modest trypanolytic activity in vitro but remain susceptible to infection by trypanosoma brucei brucei. | although trypanosoma brucei brucei fatally infects livestock in much of sub-saharan africa, humans are innately resistant to infection, apparently because high-density lipoproteins (hdl) in human serum lyse this unicellular protozoan parasite. recently, we demonstrated that purified human apolipoprotein (apo) a-i, the major protein (m(r) 28,016) constituent of hdl, had full trypanolytic activity in vitro whereas the apoa-i of cattle and sheep was non-lytic. in the present study, we have sought t ... | 1992 | 1464747 |
| stereoselective synthesis of glycobiosyl phosphatidylinositol, a part structure of the glycosyl-phosphatidylinositol (gpi) anchor of trypanosoma brucei. | o-alpha-d-mannopyranosyl-(1-->4)-o-2-amino-2-deoxy-alpha-d-glucopyranosy l- (1-->6)-1d-myo-inositol 1-(1,2-di-o-myristoyl-sn-glycer-3-yl hydrogen phosphate), a part structure of the glycosyl-phosphatidylinositol (gpi) anchor of trypanosoma brucei, was synthesised efficiently by the phosphonate approach. the glycobiosylinositol core was prepared in a stereocontrolled manner from 1d-2,3,4,5-tetra-o-benzyl-1-o-(4-methoxybenzyl)-myo-inositol, tert-butyldimethylsilyl 2-azido-3,6-di-o-benzyl-2-deoxy-a ... | 1992 | 1468082 |
| bidirectional signals between trypanosoma brucei brucei and dorsal root ganglion neurons. | the extracellular haemoflagellate trypanosoma brucei brucei releases a factor, which can induce cd8+ t-cells to produce interferon-gamma. interferon-gamma derived from these cells promotes proliferation of the trypanosomes. we now report that these trypanosomes can interact with small neurons in cultures of rat dorsal root ganglia, which contain an interferon-gamma like immunoreactive molecule. cultures of dorsal root ganglia were able to promote the proliferation and survival of the trypanosome ... | 1992 | 1469461 |
| stereoselective total synthesis of the glycosyl phosphatidylinositol (gpi) anchor of trypanosoma brucei. | the total synthesis of o-(o-[6-o-(2-aminoethylphosphono)-alpha-d-mannopyranosyl]-(1-->2)- o-alpha- d-mannopyranosyl-(1-->6)-o-[o-alpha-d-galactopyranosyl-(1-->6)-alpha-d- galactopyranosyl-(1-->3)]-o-alpha-d-mannopyranosyl-(1-->4)-2-amino-2-deo xy- alpha-d-glucopyranosyl)-(1-->6)-[1-o-(1,2-dimyristoyl-sn-glycero-3-phosp hono) - 1d-myo-inositol], the gpi anchor of trypanosoma brucei was achieved for the first time. the core structure of the gpi molecule, the glycoheptaosyl part, was constructed in ... | 1992 | 1473115 |
| glucose transport in crithidia luciliae. | the glucose analogue, 2-deoxy-d-glucose, was used to characterise the glucose transport system in crithidia luciliae choanomastigotes. uptake was temperature dependent with a q10 of 2, and saturable with a km of 0.22 mm and vmax of 5.5 nmol min-1 (mg protein)-1 at 23 degrees c. preloaded cells showed rapid exchange of intracellular 2-deoxy-d-glucose when incubated with extracellular d-glucose or 2-deoxy-d-glucose but little exchange with l-glucose. the substrate specificity of the uptake was stu ... | 1992 | 1474988 |
| transient inhibition of protein synthesis accompanies differentiation of trypanosoma brucei from bloodstream to procyclic forms. | it has been widely believed that bloodstream forms of trypanosoma brucei must be first transformed into intermediary and/or short-stumpy forms in the bloodstream of the mammalian host before differentiation to the procyclic culture form can occur. in our recent studies, the pleomorphic t. brucei strain treu667 was found to differentiate directly from the long-slender bloodstream form to the procyclic form in cunningham's medium at 26 degrees c [7]. in the present investigation, the same was foun ... | 1992 | 1474991 |
| a high molecular mass phosphoprotein defined by a novel monoclonal antibody is closely associated with the intermicrotubule cross bridges in the trypanosoma brucei cytoskeleton. | the main component of the cell body cytoskeleton of trypanosoma brucei is the highly organised array of stable, subpellicular microtubules on the cytoplasmic face of the plasma membrane. although several microtubule associated proteins (maps) have been shown to be associated with this array, the mechanisms by which individual microtubules interact with one another and with the membrane are still largely undetermined. in this study we have used the t. brucei cytoskeleton as a complex immunogen fo ... | 1992 | 1478963 |
| putrescine activated s-adenosylmethionine decarboxylase from trypanosoma brucei brucei. | trypanosoma brucei brucei contained a s-adenosyl-l-methionine decarboxylase (adometdc) strongly activated by putrescine. the enzyme was also activated to a lesser extent by cadaverine and 1,3-diaminopropane. spermidine and spermine had no effect on basal activity of the enzyme. however, they interfered with putrescine activation of trypanosomal adometdc. the trypanosomal enzyme could not be precipitated with antiserum against human adometdc. the trypanosomal adometdc enzyme subunit was labeled b ... | 1992 | 1480164 |
| the relationship of variable antigen expression and population growth rates in trypanosoma brucei. | the relationship between variable antigen type (vat) expression and trypanosome growth rates was investigated. growth rates in mice were compared between pairs of cloned trypanosome populations, each of which homogeneously expressed a different vat. all three pairwise combinations of gutats (glasgow university trypanozoon antigen types) 7.3, 7.4 and 7.5 were analysed twice and all three combinations of gutats 8.2, 8.3 and 8.4 were compared once. the lines expressing different vats were of the sa ... | 1992 | 1480602 |
| energization-dependent ca2+ accumulation in trypanosoma brucei bloodstream and procyclic trypomastigotes mitochondria. | the permeabilization of trypanosoma brucei procyclic and bloodstream trypomastigotes with digitonin permitted the quantitative estimation of a mitochondrial membrane potential of the order of 130-140 mv, in both forms, using safranine o. dependence on substrate oxidation and response of the procyclic mitochondrial membrane potential to phosphate, fccp, valinomycin, and ca2+ indicate that these mitochondria behave similarly to vertebrate mitochondria regarding the properties of their electrochemi ... | 1992 | 1484549 |
| endocytosed transferrin in african trypanosomes is delivered to lysosomes and may not be recycled. | it has been shown in mammalian systems that the passage of transferrin-colloidal gold (tf-au) through the endocytic system is influenced by the size of the gold colloid (neutra, m. r. et al., j. histochem. cytochem. 33, 1134-1144 (1985); woods, j. w. et al., eur. j. cell biol. 50, 132-143 (1989)). however, in both trypanosoma brucei brucei and trypanosoma congolense, widely varying sizes of tf-au (tf-au5 and tf-au15) have been shown to proceed to lysosomes (webster, p., eur. j. cell biol. 49, 29 ... | 1992 | 1493805 |
| identification of an acute-phase reactant in murine infections with trypanosoma brucei. | a 42-kda protein appeared at a much higher concentration in plasma from trypanosoma brucei-resistant (c57bl/6) mice after infection than in plasma from trypanosome-susceptible (c3h/he) mice. this protein was purified by sequential steps of gel filtration, protein a-sepharose affinity chromatography, isoelectric focusing, and ammonium sulfate precipitation. the purified protein was identified as a subunit of the acute-phase reactant haptoglobin. causes of elevated plasma haptoglobin and its impli ... | 1992 | 1500201 |
| characterisation of melarsen-resistant trypanosoma brucei brucei with respect to cross-resistance to other drugs and trypanothione metabolism. | an arsenical resistant cloned line of trypanosoma brucei brucei was derived from a parent sensitive clone by repeated selection in vivo with the pentavalent melaminophenyl arsenical, sodium melarsen. the melarsen-resistant line was tested in vivo in mice against a range of trypanocidal compounds and found to be cross-resistant to the trivalent arsenicals, melarsen oxide, melarsoprol and trimelarsen (33, 67 and 122-fold, respectively). a similar pattern of cross-resistance was found in vitro usin ... | 1992 | 1501641 |
| the interaction of arsenical drugs with dihydrolipoamide and dihydrolipoamide dehydrogenase from arsenical resistant and sensitive strains of trypanosoma brucei brucei. | d,l-dihydrolipoamide and d,l-dihydrolipoic acid react to form stable complexes with melarsen oxide with association constants of 5.47 x 10(9) and 4.51 x 10(9) m-1, respectively. these complexes possess 6-membered cyclic dithioarsenite rings which are 10-fold less stable than the 5-membered rings found in the trypanocidal drugs melarsoprol and trimelarsen, but 500-fold more stable than the 25-membered macrocyclic ring formed between melarsen oxide and dihydrotrypanothione. l-lipoic acid concentra ... | 1992 | 1501642 |
| purification of sn-glycerol-3-phosphate dehydrogenase from trypanosoma brucei brucei. | a protein has been purified from the membranes of bloodstream forms of trypanosoma brucei brucei. the purified material contained a single polypeptide chain of molecular mass 67 kilodaltons as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; under "native" conditions it migrated through a sephacryl s-300 column with a similar molecular mass. the purified protein catalysed electron transfer from sn-glycerol 3-phosphate to oxygen with the subsequent formation of water. electron ... | 1992 | 1510824 |
| the in vitro and in vivo effects of mefloquine on trypanosoma brucei brucei. | blood stream forms of trypanosoma brucei brucei were grown over mouse kidney (mk) cells in minimum essential medium with various concentrations of mefloquine. the drug was observed to inhibit multiplication of the parasites in vitro. groups of male albino mice were treated with mefloquine at 24, 48 and hours after t. b. brucei infection. mefloquine at 0.03 mg/kg body weight administered for 4 consecutive days cleared the infection. no trypanosomes were detected in the blood of these mice for 90 ... | 1992 | 1512455 |
| in vivo import of firefly luciferase into the glycosomes of trypanosoma brucei and mutational analysis of the c-terminal targeting signal. | the compartmentalization of glycolytic enzymes into specialized organelles, the glycosomes, allows the bloodstream form of trypanosoma brucei to rely solely on glycolysis for its energy production. the biogenesis of glycosomes in these parasites has been studied intensively as a potential target for chemotherapy. we have adapted the recently developed methods for stable transformation of t. brucei to the in vivo analysis of glycosomal protein import. firefly luciferase, a peroxisomal protein in ... | 1992 | 1515676 |
| purification and characterization of a novel sialidase found in procyclic culture forms of trypanosoma brucei. | a membrane-bound sialidase (ec 3.2.1.18) was found in procyclic trypomastigotes of trypanosoma brucei. the mammalian stage bloodstream form, however, displayed no sialidase activity. this sialidase is an integral surface protein, linked to the membrane via a glycosylphosphatidylinositol anchor. after osmotic lysis and solubilization with triton cf-54, the enzyme was purified 1900-fold by gel filtration and ion exchange chromatography. its size, as determined by conventional and high-performance ... | 1992 | 1518530 |
| chemotherapy of cns-trypanosomiasis: the combined use of diminazene aceturate or pentamidine with dl-alpha-difluoromethylornithine (dfmo). | the chemotherapy of cns-trypanosomiasis with dl-alpha-difluoromethylornithine (eflornithine, dfmo) with the diamidine, pentamidine (lomidine) or diminazene aceturate (berenil) was examined using the mouse model for cns-trypanosomiasis. although combined dfmo/pentamidine therapy can give complete cures, one or more doses of 100 mg/kg pentamidine was required with continuous administration of dfmo for 14-16 days, and even this treatment failed to cure the mice in a repeat experiment. diminazene ac ... | 1992 | 1519020 |
| pharmacomodulations on new organometallic complexes of ir, pt, rh, pd, os: in vitro and in vivo trypanocidal study against trypanosoma brucei brucei. | new organometallic complexes have been synthesized by association of an active organic molecule with a metallic element such as pt, rh, ir, pd, os. their trypanocidal activity was studied in vitro and in vivo against t. b. brucei. the more active compounds were pentamidine derivatives. the ir- cod-pentamidine complex, and iridium (i) cationic and organometallic complex showed and in vitro activity at 60 micrograms/l. moreover, all infected mice were cured by this compound subcutaneously administ ... | 1992 | 1519021 |
| decrease of testosterone level during an experimental african trypanosomiasis: involvement of a testicular lh receptor desensitization. | to investigate gonadal disorders and changes of the testicular receptors occurring during the sleeping sickness disease (african trypanosomiasis), an experimental model was developed with 10-month-old rats infested by bloodstream forms of two variants of trypanosoma brucei brucei (antat 1.1 a and antat 1.8). at the acute phase, three days after inoculation, the animals were sacrificed for estimating the serum levels of lh and testosterone and the number of testicular lh receptors. considering a ... | 1992 | 1519428 |
| trypanosoma brucei brucei: in vitro production of metacyclic forms. | an in vitro method has been established to obtain metacyclic form populations of trypanosoma brucei brucei. trypanosome populations containing more than 98% of metacyclic forms were obtained from cultures which were: 1) initiated with bloodstream forms in primary cultures in the presence of microtus montanus embryonic fibroblast-like cells (feeder cell layers); 2) maintained in glucose-free eagle's minimum essential medium supplemented with 10 mm l-proline, 2 mm l-glutamine and 20% (v/v) fetal b ... | 1992 | 1522545 |
| cystatin-like cysteine proteinase inhibitors of parasitic protozoa. | a new method has been developed for detecting cystatins and other cysteine proteinase inhibitors. the method, which involves protein separation by sds-page followed by a cysteine proteinase overlay step, is more sensitive than previously reported techniques: as little as 1 ng of recombinant human cystatin c can be detected and cysteine proteinase inhibitors could also be detected in complex protein mixtures such as bovine foetal serum. the method has been used to show, for the first time, cystei ... | 1992 | 1526466 |
| comparison of the cytolytic effects in vitro on trypanosoma brucei brucei of plasma, high density lipoproteins, and apolipoprotein a-i from hosts both susceptible (cattle and sheep) and resistant (human and baboon) to infection. | the african trypanosome, trypanosoma brucei brucei causes a fatal wasting disease in livestock but does not ordinarily infect humans, apparently because this unicellular parasite is lysed by high density lipoproteins (hdl) in human serum. to assess whether there is a specific active constituent in trypanolytic hdl, we have systematically compared the cytotoxic action on t.b.brucei in vitro of native and delipidated hdl, and of individual apolipoproteins, from nonpermissive hosts (human and baboo ... | 1992 | 1527475 |
| high-efficiency clonal growth of bloodstream- and insect-form trypanosoma brucei on agarose plates. | this report describes a method for growing both bloodstream- and procyclic-form trypanosoma brucei as colonies on agarose plates. procyclic colonies, which took 2 weeks to develop, grew with approximately 17% plating efficiency on sdm-79/0.65% agarose supplemented with 20% (vol/vol) conditioned medium. bloodstream forms were adapted to in vitro growth in liquid hmi-9 medium and then spread on hmi-9/0.65% agarose plates, where they grew to visible colonies in 3-5 days. plating efficiencies were f ... | 1992 | 1528898 |
| irreversible inhibition of s-adenosylmethionine decarboxylase of trypanosoma brucei brucei by s-adenosylmethionine analogues. | s-adenosylmethionine analogues designed as active-site directed inhibitors were tested in vitro for their effects on s-adenosylmethionine decarboxylase (adometdc) of trypanosoma brucei brucei. these analogues contained a tertiary nitrogen atom in place of the sulfonium and had a side chain of variable length ending in a reactive group (hydrazino-, aminooxy-, hydrazido- or a methylnitrosourea). the hydrazino- derivatives were the most potent inhibitors with ic50 values in the range of 40-100 nm. ... | 1992 | 1530659 |
| identification of two distinct galactosyltransferase activities acting on the variant surface glycoprotein of trypanosoma brucei. | variant surface glycoproteins (vsgs) of trypanosoma brucei contain two distinct glycosylation sites: (1) n-linked glycans within the protein portion of the molecules, and (2) the glycosyl-phosphatidylinositol (gpi) membrane anchor. since galactose residues show uncommon alpha-glycosidic linkages in the gpi membrane anchor, we were prompted to investigate galactosylation of the gpi anchor. on comparing a trypanosome clone galactosylated exclusively in n-glycans (clone mitat 1.5) with clones galac ... | 1992 | 1533512 |
| characteristics of the binding of human and bovine high-density lipoproteins by bloodstream forms of the african trypanosome, trypanosoma brucei brucei. | bloodstream forms of trypanosoma brucei brucei are unable to synthesize cholesterol but appear to bind and take up plasma low-density lipoproteins (ldl) from their host. whether cholesterol homeostasis of this unicellular parasite also requires interactions with host high-density lipoprotein (hdl) particles is unknown. equilibrium binding of radioiodinated apolipoprotein e-depleted human hdl3 (d = 1.125-1.21 g/ml) and bovine hdl (d = 1.063-1.21 g/ml) by t.b.brucei was rapid (less than 30 min) at ... | 1992 | 1536861 |
| atp-dependent saccharomyces cerevisiae phospho enol pyruvate carboxykinase: isolation and sequence of a peptide containing a highly reactive cysteine. | saccharomyces cerevisiae phospho enol pyruvate carboxykinase (ec 4.1.1.49), inactivated by n-(iodoacetyl)-n'-(5-sulfo-1-naphthyl)ethylenediamine, incorporated 0.95 mol of the fluorescent moiety per mol of enzyme subunit. reagent incorporation was completely protected by the presence of adp plus mncl2. the labeled protein was digested with trypsin after carboxymethylation. two labeled peptides were isolated by reverse-phase high-performance liquid chromatography and were sequenced by gas-phase au ... | 1992 | 1540632 |
| a phosphoglycerate kinase-related gene conserved between trypanosoma brucei and crithidia fasciculata. | trypanosoma brucei and crithidia fasciculata both contain three different phosphoglycerate kinase (pgk) genes, a, b and c, in a tandem array. the genes b and c encode the major pgks: the cytosolic and glycosomal pgks, respectively. the pgk-a genes of both trypanosomatid species encode open reading frames related to pgk, which have most active site residues conserved, but contain an insert of 80 amino acids at approximately position 80 of the 420 amino acids average pgk sequence. the deduced amin ... | 1992 | 1542317 |
| isolation of cdna clones encoding proteins of complex structures: analysis of the trypanosoma brucei cytoskeleton. | we have adapted a group of well-known procedures in order to devise a simple method that allows the isolation of specific cdnas encoding proteins located in different regions of the trypanosoma brucei cytoskeleton. cdna clones were isolated by screening a lambda gt11 expression library with a polyspecific, polyclonal antiserum against a complex immunogen, in this case the complete cytoskeleton. the fusion proteins produced by the clones were then used as an affinity immunoadsorbant to select mon ... | 1992 | 1544578 |
| a gene from the variant surface glycoprotein expression site encodes one of several transmembrane adenylate cyclases located on the flagellum of trypanosoma brucei. | the bloodstream form of trypanosoma brucei contains transcripts of at least four genes showing partial sequence homology to the genes for eucaryotic adenylate and guanylate cyclases (s. alexandre, p. paindavoine, p. tebabi, a. pays, s. halleux, m. steinert, and e. pays, mol. biochem. parasitol. 43:279-288, 1990). one of these genes, termed esag 4, belongs to the polycistronic transcription unit of the variant surface glycoprotein (vsg) gene. whereas esag 4 is transcribed only in the bloodstream ... | 1992 | 1545803 |
| characterization of different proteolytic activities in trypanosoma brucei brucei. | the variant surface glycoprotein of african trypanosomes is released after overnight incubation of parasites at 4 degrees c in ph 5.5 phosphate glucose buffer and may be purified by concanavalin a sepharose affinity chromatography. the addition of proteinase inhibitors during the parasite incubation is necessary to prevent the proteolysis of the variant surface glycoprotein by the trypanosomal released proteinases. using this procedure without the addition of proteinase inhibitors, the proteolyt ... | 1992 | 1547283 |
| kinetoplastid rna editing: in vitro formation of cytochrome b grna-mrna chimeras from synthetic substrate rnas. | rna editing in the kinetoplastid trypanosoma brucei results in the addition and deletion of uridine residues within several mitochondrial mrnas. the site and number of uridines added appears to be directed by small (approximately 70 nt) guide rnas (grnas), which can base pair to the edited sequences. we examined reactions involving synthetic cytochrome b (cyb) grna and pre-edited mrna in vitro. a major product of the in vitro reaction is a chimeric rna molecule containing both grna and mrna sequ ... | 1992 | 1547505 |
| nucleotide sequence of the gene encoding the largest subunit of the dna-dependent rna polymerase iii of giardia lamblia. | | 1992 | 1549483 |
| calcium homeostasis in procyclic and bloodstream forms of trypanosoma brucei. lack of inositol 1,4,5-trisphosphate-sensitive ca2+ release. | when trypanosoma brucei procyclic trypomastigotes were permeabilized with digitonin in a reaction medium containing mgatp, succinate, and 3.5 microm free ca2+, they lowered the medium ca2+ concentration to the submicromolar level (0.05-0.1 microm), a range that correlates favorably with that detected in the intact cells with fura-2. the carbonyl cyanide p-trifluoromethoxyphenylhydrazone-insensitive ca2+ uptake, certainly represented by the endoplasmic reticulum, was completely inhibited by 500 m ... | 1992 | 1556113 |
| isolation and characterization of a unique 15 kilodalton trypanosome subpellicular microtubule-associated protein. | a protein of 15 kda (p15) was isolated from trypanosoma brucei subpellicular microtubules by tubulin affinity chromatography. the protein bound tubulin specifically both in its native form and after sds-page in tubulin overlay experiments. p15 promoted both the in vitro polymerization of purified calf brain tubulin and the bundling of preformed mammalian microtubules. immunolabeling identified p15 at multiple sites along microtubule polymers comprising calf brain tubulin and p15 as well as on th ... | 1992 | 1559265 |
| the 7sl rna homologue of trypanosoma brucei is closely related to mammalian 7sl rna. | in eukaryotes, protein translocation across the endoplasmic reticulum is mediated by a signal recognition particle, a small ribonucleoprotein (rnp) containing 7sl rna. we have cloned and sequenced the gene coding for the trypanosoma brucei 7sl rna homologue and found that its sequence shows the highest degree of similarity to the human 7sl rna sequence. in keeping with the prototype secondary structure of eukaryotic 7sl rna, the trypanosome 7sl rna secondary structure can be folded into four dom ... | 1992 | 1565138 |
| purification of novel calcium binding proteins from trypanosoma brucei: properties of 22-, 24- and 38-kilodalton proteins. | the present study was undertaken to systematically purify calcium binding proteins (cabps) from homogenates of trypanosoma brucei. this work is important since cabps either serve as intracellular calcium buffers or mediate cellular response to calcium signals. disruption of either process should be lethal to trypanosomes. we report that the 45ca-gel overlay assay can be used to detect cabps following fractionation on de-52, phenyl-sepharose, mono-q, and superose 12. specific cabps of 22, 24, and ... | 1992 | 1565142 |
| comparative physiology of two protozoan parasites, leishmania donovani and trypanosoma brucei, grown in chemostats. | cultures of the insect stage of the protozoan parasites leishmania donovani and trypanosoma brucei were grown in chemostats with glucose as the growth rate-limiting substrate. l. donovani has a maximum specific growth rate (mu max) of 1.96 day-1 and a ks for glucose of 0.1 mm; the mu max of t. brucei is 1.06 day-1 and the ks is 0.06 mm. at each steady state (specific growth rate, mu, equals d, the dilution rate), the following parameters were measured: external glucose concentration (glcout), ce ... | 1992 | 1569022 |
| comparison of the refined crystal structures of liganded and unliganded chicken, yeast and trypanosomal triosephosphate isomerase. | the refined crystal structures of chicken, yeast and trypanosomal triosephosphate isomerase (tim) have been compared. tim is known to exist in an "open" (unliganded) and "closed" (liganded) conformation. for chicken tim only the refined open structure is available, whereas for yeast tim and trypanosomal tim refined structures of both the open and the closed structure have been used for this study. comparison of these structures shows that the open structures of chicken tim, yeast tim and trypano ... | 1992 | 1569570 |
| structural elements of ornithine decarboxylase required for intracellular degradation and polyamine-dependent regulation. | mammalian ornithine decarboxylase (odc), a key enzyme in polyamine biosynthesis, is rapidly degraded in cells, an attribute important to the regulation of its activity. mutant and chimeric odcs were created to determine the structural requirements for two modes of proteolysis. constitutive degradation requires the carboxy terminus and is independent of intracellular polyamines. truncation of five or more carboxy-terminal amino acids prevents this mode of degradation, as do several internal delet ... | 1992 | 1569947 |
| a cloned dna probe for cowdria ruminantium hybridizes with eight heartwater strains and detects infected sheep. | the dna probe pcs20, which was cloned from the dna of the crystal springs heartwater strain from zimbabwe, cross-reacted with dnas of heartwater strains from all endemic areas, including four heartwater strains from zimbabwe, two strains from south africa, one strain from nigeria, and the gardel strain from the caribbean island of guadeloupe. by nucleic acid hybridization, the pcs20 dna probe detected cowdria ruminantium dna in all dna preparations made from plasma samples from infected sheep be ... | 1992 | 1572987 |
| pyruvate transport across the plasma membrane of the bloodstream form of trypanosoma brucei is mediated by a facilitated diffusion carrier. | the characteristics of pyruvate transport across the plasma membrane in the bloodstream form of trypanosoma brucei were studied using [14c]pyruvate in combination with the silicone-oil centrifugation technique. we present evidence for the existence of a facilitated diffusion carrier in the plasma membrane of t. brucei which specifically mediates the translocation of pyruvate. the uptake of pyruvate followed saturation kinetics (km 1.96 +/- 0.28 mm; cmax 36.61 +/- 1.15 nmol pyruvate/30 sec.mg pro ... | 1992 | 1575722 |
| expression in bacillus subtilis of the glycosomal glyceraldehyde-phosphate dehydrogenase gene from trypanosoma brucei. | the cloned t brucei gapdh gene was inserted within the b subtilis gapdh gene, carried by puc18. upon transformation of b subtilis by this plasmid, not able to replicate in this host, the whole plasmid was inserted in the resident chromosome, presumably by a single recombination event between homologous, chromosomal and plasmid-borne sequences. the heterologous gene was expressed, as revealed by immunological reaction with monoclonal antibodies, recognizing specifically t brucei gapdh. t brucei g ... | 1992 | 1581389 |
| trypanosoma brucei: the tumor promoter thapsigargin stimulates calcium release from an intracellular compartment in slender bloodstream forms. | maintenance of calcium homeostasis is a critical activity of eukaryotic cells. homeostatic pathways stabilize intracellular free calcium concentrations ([ca2+]i) at the resting level and provide the source of mobilized calcium for cellular activation. we have measured calcium release from intracellular pools within bloodstream forms of trypanosoma brucei to better understand homeostatic pathways which operate in these organisms. fura-2 and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein were use ... | 1992 | 1582486 |
| studies on tsetse midgut factors that induce differentiation of blood-stream trypanosoma brucei brucei in vitro. | an in vitro system for studying the transformation of bloodstream forms of trypanosoma brucei brucei into procylic (midgut) forms is described. in this system, transformation of the parasites was stimulated by glossina morsitans morsitans midgut homogenates at 27 degrees c but not at 4 degrees c. the transformation-stimulating capacity was irreversibly destroyed by heating the midgut homogenates at 60 degrees c for 1 h. a correlation was established between the transformation activity of the mid ... | 1992 | 1584740 |
| identification of invariant surface glycoproteins in the bloodstream stage of trypanosoma brucei. | surface proteins of the mammalian stage of the parasitic protozoan, trypanosoma brucei, were biotinylated with sulfosuccinimidyl 6-(biotinamido) hexanoate. since the predominant protein labeled by this reagent is the membrane form of the variant surface glycoprotein (mfvsg), a procedure was developed to convert mfvsg to its soluble form by the endogenous glycosylphosphatidylinositol-specific phospholipase c while retaining other biotinylated surface proteins in a membrane-bound state. from these ... | 1992 | 1587855 |
| molecular characterization of two invariant surface glycoproteins specific for the bloodstream stage of trypanosoma brucei. | in the accompanying paper (ziegelbauer, k., and overath, p. (1992) j. biol. chem. 267, 10791-10796), two invariant surface glycoproteins, isg65 and isg75, were identified in the mammalian stage of the parasitic protozoan, trypanosoma brucei. in this study, the genes coding for these proteins have been isolated. their nucleotide sequence suggests no relationship to other known genes and predicts polypeptides with nh2-terminal signal sequences, hydrophilic extracellular domains, single trans-membr ... | 1992 | 1587856 |
| uptake of the antitrypanosomal drug 5'-([(z)-4-amino-2-butenyl]methylamino)-5'-deoxyadenosine (mdl 73811) by the purine transport system of trypanosoma brucei brucei. | an irreversible inhibitor of s-adenosyl-l-methionine decarboxylase (adometdc), 5'-([(z)-4-amino-2-butenyl]methylamino)-5'-deoxyadenosine (mdl 73811), was found to cure trypanosoma brucei brucei and multidrug-resistant t. b. rhodesiense infections in mice [bitonti, byers, bush, casara, bacchi, clarkson, mccann & sjoerdsma (1990) antimicrob. agents chemother. 34, 1485-1490]. doses of this drug which resulted in a rapid clearance of parasites from t. b. brucei-infected rats resulted in plasma level ... | 1992 | 1590765 |
| chimeric and truncated rnas in trypanosoma brucei suggest transesterifications at non-consecutive sites during rna editing. | rna editing adds and removes uridines at specific sites in several mitochondrial transcripts in kinetoplastid parasites probably as specified by guide rnas (grnas) that are complementary to the final edited sequence. editing has been postulated to involve transesterification which predicts (1) chimeric molecules with a grna covalently attached by its non-encoded oligo u tail to an internal editing site in the mrna and (2) the corresponding truncated 5' portions of the mrnas. we have characterize ... | 1992 | 1594451 |
| mouse ornithine decarboxylase is stable in trypanosoma brucei. | the cdna encoding mouse ornithine decarboxylase (odc) was incorporated into a transforming vector ptsa-neo2 carrying a procyclic acidic repetitive protein promoter and a neomycin phosphotransferase gene. the plasmid thus constructed, pmod300, was introduced into the procyclic forms of trypanosoma brucei via electroporation, and the transformants, selected under g418, expressed an odc activity 100 times above the background level. contrary to the commonly observed short half-life of mouse odc in ... | 1992 | 1597444 |
| sequence of trypanosoma brucei trna genes encoding cytosolic trnas. | | 1992 | 1598224 |
| identification of a new ef-hand superfamily member from trypanosoma brucei. | we identified several open reading frames between the regions encoding calmodulin and ubiquitin-ep52/1 in the genome of trypanosoma brucei. one of these, efh5, encodes a protein 192 amino acids long. the efh5 transcript is present in poly(a)+ mrna and is present at similar levels in the mammalian bloodstream form and the insect procyclic form. efh5 contains four ef-hand homolog domains, two of which are inferred to bind ca2+ ions. we expressed efh5 as a fusion protein in escherichia coli and dem ... | 1992 | 1603064 |
| genomic organization and context of a trypanosome variant surface glycoprotein gene family. | we have defined the genomic organization and genomic context of a trypanosoma brucei brucei gene family encoding variant surface glycoproteins (vsgs). this gene family is neither tandemly repeated nor closely linked in the genome, and is not located on small or intermediate size chromosomes. two dispersed repeated sequence elements, rime-ingi and the upstream repeat sequence, are linked to members of this gene family; however, the upstream repeat sequences are closely linked only to the basic co ... | 1992 | 1613802 |
| sequence divergence among members of a trypanosome variant surface glycoprotein gene family. | we have used analysis of dna sequence data from four members of a trypanosoma brucei variant surface glycoprotein gene family to investigate the molecular basis of the generation of antigenic diversity in african trypanosomes. among these four sequences we find the greatest similarity in the untranslated sequences immediately upstream from the coding region. a complex pattern of nucleic acid and predicted amino acid sequence divergence appears starting at the coding sequence. two related but hig ... | 1992 | 1613803 |
| identification and characterization of two repetitive non-variable antigens from african trypanosomes which are recognized early during infection. | the present paper describes two repetitive proteins representing common antigens of african trypanosomes which are non-variant and which are recognized early in infection by the host immune system. these antigens were identified by their ability to immunoreact with bovine serum taken during the early phase of a cyclic trypanosomal infection. screening of a cdna library from t. b. gambiense with such early infection serum identified a protein which contains a repetitive motif consisting of 68 ami ... | 1992 | 1614728 |
| numerical taxonomy of trypanozoon based on polymorphisms in a reduced range of enzymes. | numerical analyses of trypanozoon taxonomy are presented, based on the isoenzyme data of stevens et al. (1992). the previous study used a reduced range of enzymes compared with earlier work; the analyses indicate the value of this rationalized system. both recently isolated trypanosome stocks and previously studied populations were included, allowing detailed comparison with earlier studies. relationships between zymodemes were calculated with an improved similarity coefficient program, using ja ... | 1992 | 1614742 |
| genetic variation in trypanosoma brucei and the epidemiology of sleeping sickness in the lambwe valley, kenya. | a contingency table approach was used to explore the influence of location, host species and time on the genetic composition of a trypanosoma brucei population in lambwe valley, kenya. significant differences in zymodeme frequencies were noticed over comparatively short geographical distances suggesting that transmission of t. brucei is somewhat localized. a significant association was observed between zymodeme and the mammalian host from which t. brucei was derived. the association was consiste ... | 1992 | 1614744 |
| survival of trypanosoma brucei brucei in cerebrospinal fluid. | different compositions of artificial cerebrospinal fluid (csf) and the csf from sleeping sickness patients both with and without late-stage [i.e. central nervous system (cns)] involvement were evaluated for their abilities to support survival of trypanosoma brucei brucei. artificial csf, containing the major electrolytes, amino acids and carbohydrate components of healthy fluid, was equivalent to the csf from patients without cns involvement (survival time 20 hours). normal csf does not therefor ... | 1992 | 1616393 |
| a potential hexose transporter gene expressed predominantly in the bloodstream form of trypanosoma brucei. | a cdna cloned from trypanosoma brucei brucei codes for a putative membrane protein which is homologous to the erythrocyte glucose transporter and several other sugar transporters from escherichia coli, yeast, algae and leishmania. this cdna hybridizes to a 2.3-kb mrna that accumulates to a much higher degree in the bloodstream mammalian form than in the procyclic insect form of the parasite. the correlation between the expression of this gene and the hexose metabolism of leishmania enriettii and ... | 1992 | 1625698 |
| regulated degradation of ornithine decarboxylase requires interaction with the polyamine-inducible protein antizyme. | intracellular degradation of vertebrate ornithine decarboxylase (odc) is accelerated by polyamines, the products of the pathway controlled by odc. antizyme, a reversible, tightly binding protein inhibitor of odc activity, is believed to be involved in this process. mouse and trypanosoma brucei odcs are structurally similar, but the trypanosome enzyme, unlike that of the mouse, is not regulated by intracellular polyamines when expressed in hamster cells (l. ghoda, d. sidney, m. macrae, and p. cof ... | 1992 | 1630460 |
| inhibition of triosephosphate isomerase from trypanosoma brucei with cyclic hexapeptides. | two series of oligopeptides have been synthesized. their effects on the activity of purified triosephosphate isomerase from trypanosoma brucei and various other organisms have been studied. using detailed three-dimensional structure information, the first series consisted of both cyclic and linear hydrophilic peptides that were designed to mimic the beta turns of the subunit interface loops of the trypanosome triosephosphate isomerase dimer. none of these exerted any inhibitory effect. the secon ... | 1992 | 1633802 |
| evidence of tyrosine kinase activity in the protozoan parasite trypanosoma brucei. | phosphorylation of proteins at tyrosine is an important mechanism for regulating cell growth and proliferation in metazoan organisms. in this report, we have demonstrated that trypanosoma brucei, a protozoan parasite, possesses a tyrosine kinase that plays a role in regulation of proliferation of this protozoan. genistein, a tyrosine kinase inhibitor, prevented multiplication of the parasite. an in vitro kinase assay demonstrated the presence of a kinase capable of phosphorylating an exogenous s ... | 1992 | 1640387 |
| the significance of human serum sensitivity in the context of t.b. rhodesiense sleeping sickness epidemiology and control. | earlier this century the postulate that trypanosoma brucei brucei and t.b. rhodesiense had a common identity and that human infectability was linked with resistance to normal human serum (nhs) in vitro, were both finally refuted in the classical tinde experiment. interest in serum sensitivity was reawakened with the advent of the biit in 1970 and the studies that followed demonstrated the presence of both human-serum-resistant (hsr) and sensitive (hss) variant antigen types, within the surface a ... | 1992 | 1644047 |
| mitochondrial development in trypanosoma brucei brucei transitional bloodstream forms. | intermediate and short stumpy bloodstream forms of trypanosoma brucei brucei are transitional stages in the differentiation of mammal-infective long slender bloodstream forms into the procyclic forms found in the midgut of the tsetse vector. although the mitochondria of the proliferative long slender forms do not accumulate rhodamine 123, the mitochondria of the transitional forms attain this ability thus revealing the development of an electromotive force (emf) across the inner mitochondrial me ... | 1991 | 1645458 |
| glycosylphosphatidylinositol-specific phospholipase d. | | 1991 | 1646941 |
| vascular smooth muscle sensitivity to noradrenaline is reduced during an infection with trypanosoma brucei in rats and rabbits. | alpha 1-adrenoceptor sensitivity to noradrenaline has been studied in some arterial smooth muscles of rats and rabbits infected with t. brucei. in rabbits, a decrease in sensitivity of the arterial smooth muscles to noradrenaline was observed in the thoracic aorta, central ear but not renal arteries. no change in the sensitivity of the smooth muscles to histamine was observed. in rats, noradrenaline potency was reduced in the aorta, renal but not tail arteries. in both species, affinity of norad ... | 1991 | 1652187 |
| trypanosoma cruzi but not trypanosoma brucei fails to induce a chemiluminescent signal in a macrophage hybridoma cell line. | macrophage-trypanosoma cruzi interactions were studied by using a newly generated macrophage hybridoma cell line (2c11-12) that was selected for its capacity to produce high levels of reactive oxygen intermediates. this cell line was found to be a suitable host cell for t. cruzi, and intracellular parasitic development could be inhibited by activation with gamma interferon. when exposed to opsonized trypanosoma brucei, micrococcus lysodeikticus, or legionella pneumophila, the activated macrophag ... | 1991 | 1652563 |
| chemotherapy of trypanosomiasis: the potentiation of antimonial compounds by difluoromethylornithine (dfmo). | the currently available anti-leishmanial antimonial drugs, together with other antimony compounds were individually tested, in combination with difluoromethylornithine (dfmo), against experimental murine trypanosomiasis with central nervous system involvement. satisfactory cure rates could be achieved using a combination treatment of dfmo with most of these anti-leishmanial drugs, but in general, only when they were administered at least twice daily. of the compounds tested, the most effective w ... | 1991 | 1654590 |
| a glycosylphosphatidylinositol protein anchor from procyclic stage trypanosoma brucei: lipid structure and biosynthesis. | cells of the insect (procyclic) stage of the life cycle of the african trypanosome, trypanosoma brucei, express an abundant stage-specific glycosylated phosphatidylinositol (gpi) anchored glycoprotein, the procyclic acidic repetitive protein (parp). the anchor is insensitive to the action of bacterial phosphatidylinositol-specific phospholipase c (pi-plc), suggesting that it contains an acyl-inositol. we have recently described the structure of a pi-plc resistant glycosylphosphatidylinositol, pp ... | 1991 | 1655402 |
| in vivo uv cross-linking of u snrnas that participate in trypanosome trans-splicing. | the maturation of mrnas in trypanosoma brucei involves a trans-splicing reaction whereby the 5' 39 nucleotides of a small rna, called the spliced leader (sl) rna, are joined with a pre-mrna transcript. the trans-splicing reaction appears mechanistically similar to cis-splicing of nuclear pre-mrnas, and homologs of the u2, u4, and u6 snrnas are required for the process. in the work presented here, potential rna-rna interactions between the sl rna and the u snrnas of trypanosomes were examined by ... | 1991 | 1655571 |
| analysis of small nuclear ribonucleoproteins (rnps) in trypanosoma brucei: structural organization and protein components of the spliced leader rnp. | trans splicing in trypanosoma brucei involves the ligation of the 40-nucleotide spliced leader (sl) to each of the exons of large, polycistronic pre-mrnas and requires the function of small nuclear ribonucleoproteins (snrnps). we have identified and characterized snrnp complexes of sl, u2, u4, and u6 rnas in t. brucei extracts by a combination of glycerol gradient sedimentation, cscl density centrifugation, and anti-m3g immunoprecipitation. both the sl rnp and the u4/u6 snrnp contain salt-stable ... | 1991 | 1656232 |
| the hygromycin b-resistance-encoding gene as a selectable marker for stable transformation of trypanosoma brucei. | the hygromycin b (hy) phosphotransferase-encoding gene (hph), was tested as a selectable marker in the protozoan, trypanosoma brucei. the hph gene was placed under the control of the promoter of a procyclic acidic repetitive protein-encoding gene, and was integrated by homologous recombination into an intergenic region of the alpha beta-tubulin-encoding gene tandem array of t. brucei. in contrast to many other selectable markers tested, spontaneous hy resistance was not observed, making hy a sec ... | 1991 | 1657720 |
| efficient production of functional mrna mediated by rna polymerase i in trypanosoma brucei. | the unicellular eukaryote trypanosoma brucei evades the immune defence of its mammalian host by antigenic variation. the genes for variant-specific surface glycoproteins (vsgs) are expressed within large multicistronic transcription units. mature messenger rnas are produced by trans-splicing and polyadenylation. a remarkable feature of the transcription of vsg genes is its insensitivity to the rna polymerase ii inhibitor alpha-amanitin. this has led to the speculation that rna polymerase i, norm ... | 1991 | 1658658 |
| identification of negative-strand complements to cytochrome oxidase subunit iii rna in trypanosoma brucei. | a substantial amount of cytochrome oxidase subunit iii (coiii) mrna continues to be synthesized de novo in trypanosoma brucei in the presence of actinomycin d, presumably by a dna-independent transcription process. we describe the identification of negative-strand coiii rna molecules, characterization of their termini, and the detection of rna-dependent rna polymerase activity. three lines of evidence for the existence of negative-strand coiii rna are presented: (i) hybridization with oligonucle ... | 1991 | 1660145 |