| lysis of trypanosomes by peptidyl fluoromethyl ketones. | peptidyl fluoromethyl ketones, improved reagents for inactivating cysteinyl and serine proteinases, have provided unexpected results when applied to intact trypanosomes. a lethal effect was observed but limited to the infectious phase of the parasitic growth cycle. since the inhibitors are known only to act on proteases, the result implies the existence of a protease of critical importance during the infectious phase. a labelled inhibitor, cbz-ala-[3h]phe-ch2f, indicated that the killing effect ... | 1990 | 2116800 |
| differential susceptibility to dl-alpha-difluoromethylornithine in clinical isolates of trypanosoma brucei rhodesiense. | dl-alpha-difluoromethylornithine is an enzyme-activated inhibitor of ornithine decarboxylase and an antagonist of polyamine metabolism that has been successful in clinical trials against west african sleeping sickness caused by trypanosoma brucei gambiense. its potential for use against the more virulent east african form of the disease, caused by t. brucei rhodesiense, is not certain. we examined 14 east african clinical isolates from the kenya trypanosomiasis research institute strain bank plu ... | 1990 | 2118325 |
| a survey for a trypanocidal factor in primate sera. | the sera of 21 different species of primates were surveyed for the presence of a trypanocidal factor to a monomorphic human serum-sensitive clone of trypanosoma brucei gambiense (t.b.g.); human, gorilla, baboon (2 species), and the mandrill were found to contain this factor. the factor in all the sera is in the high density lipoprotein (hdl) fraction, and has similar modes of biological action. it has been shown that the human and gorilla trypanocidal factor share cross-reactive antigenic epitop ... | 1990 | 2120433 |
| therapy and prophylaxis of systemic protozoan infections. | this article summarises current therapy and prophylaxis for pneumocystis carinii, toxoplasma gondii, leishmania species, african trypanosomes (trypanosoma brucei gambiense and t. b. rhodesiense), and american trypanosome (trypanosoma cruzi) infections. each agent and the disease it causes is briefly reviewed, and current data on the structure, mode of action, indications for treatment, dosage, administration, duration of therapy, efficacy, toxicity, and necessary monitoring during therapy are di ... | 1990 | 2121456 |
| cdna sequences encoding rabbit latent kappa 1 b5 and b6 ig l chains. | regulation of rabbit ig c kappa 1 l chain gene expression is thought to be under allelic control. four nominal allotypic variants designated b4, b5, b6, and b9 have been found to be co-dominantly expressed at the c kappa 1 gene locus. latent allotypes are nonallelic and appear as unexpected and transitory molecules in the serum as well as on b cell surfaces. to determine the mechanism of latent kappa 1 allotype expression, rabbits were initially induced to produce latent b5 and b6 allotypes by i ... | 1990 | 2121826 |
| a new u2 rna secondary structure provided by phylogenetic analysis of trypanosomatid u2 rnas. | a new model of u2 rna secondary structure has been developed by comparing u2 rna sequences from distantly related trypanosomatids, which process their rnas by trans-splicing, and u2 rnas from cis-splicing organisms. the trypanosomatid u2 rna retains structural similarity in important functional domains of cis-splicing u2 rnas yet differs from previous consensus models in that only two helices, rather than three, can form in the stem-loop ii region. this alteration eliminates the capacity for pse ... | 1990 | 2125286 |
| using transfection to study gene expression in trypanosomes. | | 1990 | 2128058 |
| organization, structure and evolutionary aspects of genes in trypanosomes. | | 1990 | 2128059 |
| [epidemiology of human trypanosomiasis in the luba focus, in equatorial guinea]. | in equatorial guinea, the human trypanosomiasis, after an intensive surveillance beginning in the 30's, seemed to be controlled by the end of the 60's. a lack of surveillance provoked a surge of different foci, confirmed in 1982 by the spontaneous presentations of sick in the hospitals of the old foci. these processes have been observed in the luba focus (ex san carlos) on the island of bioko (ex fernando poo). the situation was grave in 1985 and a survey was organized by the "centro de control ... | 1990 | 2131631 |
| haemolymph lectin and the maturation of trypanosome infections in tsetse. | the tsetse immune system has recently been shown to be involved in trypanosome maturation; lectin secreted in the midgut, normally responsible for preventing the establishment of midgut infections, induces established midgut trypanosomes to mature. we now show that a second lectin, present in tsetse haemolymph, is essential to complete the maturation process. interactions between tsetse lectins and parasite surface coats probably determine trypanosome transmissibility and may be partly responsib ... | 1990 | 2132968 |
| [identification of entamoeba histolytica chromosomes by pulsed field gradient electrophoresis]. | the use of pulsed field gradient electrophoresis (pfg) has simplified the study of chromosomic organization in protozoan parasites whose chromosomes do not condense during division. in this paper we used pcg to analyzed chromosome organization entamoeba histolytica's. in the conditions which we used (200 volts, 24 hours, 3 minute pulses and the anode at 7.5 cm. from the end of the cathode) 6 and 9 band of amebic dna were resolved. by means of a ribosomal dna probe from trypanosoma brucei amebic ... | 1990 | 2136489 |
| anti-inositolglycan antibodies selectively block some of the actions of insulin in intact bc3h1 cells. | we have studied the mechanism of generation of insulin mediators by using specific antibodies raised against the oligosaccharide anchor of membrane proteins. these antibodies (i) block the in vitro effects of purified insulin mediators and (ii) block the insulin-induced stimulation of pyruvate dehydrogenase in intact bc3h1 myocytes but not insulin-stimulated glucose uptake, generation of diacylglycerol, or generation of insulin mediators. when added to intact cells in the presence of insulin, th ... | 1990 | 2137614 |
| glycolipid precursors for the membrane anchor of trypanosoma brucei variant surface glycoproteins. i. can structure of the phosphatidylinositol-specific phospholipase c sensitive and resistant glycolipids. | a number of eukaryotic surface glycoproteins, including the variant surface glycoproteins of trypanosoma brucei, are synthesized with a carboxyl-terminal hydrophobic peptide extension that is cleaved and replaced by a complex glycosyl-phosphatidylinositol (gpi) membrane anchor within 1-5 min of the completion of polypeptide synthesis. the rapidity of this carboxyl-terminal modification suggests the existence of a prefabricated precursor glycolipid that can be transferred en bloc to the polypepti ... | 1990 | 2138614 |
| glycolipid precursors for the membrane anchor of trypanosoma brucei variant surface glycoproteins. ii. lipid structures of phosphatidylinositol-specific phospholipase c sensitive and resistant glycolipids. | a common diagnostic feature of glycosylinositol phospholipid (gpi)-anchored proteins is their release from the membrane by a phosphatidylinositol-specific phospholipase c (pi-plc). however, some gpi-anchored proteins are resistant to this enzyme. the best characterized example of this subclass is the human erythrocyte acetylcholinesterase, where the structural basis of pi-plc resistance has been shown to be the acylation of an inositol hydroxyl group(s) (roberts, w. l., myher, j. j., kuksis, a., ... | 1990 | 2138615 |
| identification and characterization of glycosylphosphatidylinositol-linked schistosoma mansoni adult worm immunogens. | metabolic radiolabeling of adult worms of schistosoma mansoni with [3h]myristic acid has revealed that the fatty acid is incorporated into more than 15 proteins. we have shown that two of these proteins, a 200-kda glycoprotein known to be exposed on the surface of the adult worm following praziquantel treatment and a 22-kda glycoprotein that shows an enhanced immune reactivity with sera of vaccinated mice, are anchored to the adult worm membrane via a glycosylphosphatidylinositol (gpi) linkage. ... | 1990 | 2139172 |
| an extensively edited mitochondrial transcript in kinetoplastids encodes a protein homologous to atpase subunit 6. | the mitochondrial murf4 gene of t. brucei has pronounced g versus c strand bias and heterogeneously sized transcripts, characteristic of genes encoding extensively edited transcripts. we find that murf4 transcripts of t. brucei are extensively edited throughout by the addition and deletion of numerous uridines, creating potential initiation and termination codons and a continuous open reading frame. a potential guide rna sequence occurs in a minicircle between inverted repeats. the 5' region of ... | 1990 | 2140530 |
| isolation of distinct small ribonucleoprotein particles containing the spliced leader and u2 rnas of trypanosoma brucei. | messenger rna maturation in trypanosomes involves an rna trans-splicing reaction in which a 39 nucleotide 5'-spliced leader (sl), derived from an independently transcribed 139 nucleotide sl rna, is joined to pre-mrnas. trans-splicing intermediates are structurally consistent with a mechanism of sl addition which is similar to that of cis-splicing of nuclear pre-mrnas; homologous components (e.g. the u small nuclear rnas) exist in both cis- and trans-splicing systems, suggesting that these also p ... | 1990 | 2141334 |
| characterisation of small nuclear rnps in t. brucei. | | 1990 | 2141895 |
| a trypanosoma brucei small rnp particle containing the 5s rrna. | in mammalian cells, approximately 50% of the 5s rrna is found in ribosomes, and the remainder in a small particle, the 5s rrna/ribosomal protein l5 complex, which is thought to be a precursor in ribosome assembly. trypanosoma brucei, an african trypanosome, is one of the most primitive eukaryotic organisms which have been studied, and it likewise possesses a 5s rrna species, a small proportion of which is found in an apparent ribonucleoprotein-(rnp) complex. like the mammalian rnp particle, the ... | 1990 | 2143558 |
| suppressive macrophages occurring in murine trypanosoma brucei infection inhibit t-cell responses in vivo and in vitro. | intraperitoneal injection of trypanosoma brucei antat 1.1 into mice of the c3h.he, balb/c or c57bl/6 strains resulted in impaired immune responses from day 3 onwards, as measured by the reduction in dna synthesis in spleen cell populations stimulated with concanavalin a (con-a) in vitro. adherent cells from the peritoneum (pc) or from the spleen of infected mice, consisting predominantly of macrophages, caused a 60-80% reduction of the con-a response in spleen cells from syngeneic recipients 3-4 ... | 1990 | 2143570 |
| structure, biosynthesis, and function of glycosylphosphatidylinositols. | the last few years have witnessed an explosion in our knowledge of gpi membrane anchors and related glycolipids and molecules where structure details are available, as illustrated in figure 2. there is now sufficient information on a handful of these molecules to allow a detailed comparison of their chemical structures. despite a common structural theme, i.e., the presence of mannoglucosaminyl-pi, a great deal of diversity exists in both the glycan structures and the glycerol-linked aliphatic su ... | 1990 | 2143679 |
| depletion of cd8+ t cells suppresses growth of trypanosoma brucei brucei and interferon-gamma) production in infected rats. | sprague-dawley rats infected with trypanosoma brucei brucei showed a strong and rapid induction of splenocyte ifn-gamma (within 12 h post-infection) as measured by a single cell assay for ifn-gamma secretion. depletion of cd8+ cells in infected rats abrogated the ifn-gamma production, suppressed parasite growth and increased survival of the animals. induction of mhc class i antigens in the paraventricular and supra-optic hypothalamic nuclei caused by the trypanosome infection was also inhibited ... | 1990 | 2143706 |
| structure of the glycosyl-phosphatidylinositol membrane anchor of the leishmania major promastigote surface protease. | in common with many other plasma membrane glycoproteins of eukaryotic origin, the promastigote surface protease (psp) of the protozoan parasite leishmania contains a glycosyl-phosphatidylinositol (gpi) membrane anchor. the gpi anchor of leishmania major psp was purified following proteolysis of the psp and analyzed by two-dimensional 1h-1h nmr, compositional and methylation linkage analyses, chemical and enzymatic modifications, and amino acid sequencing. from these results, the structure of the ... | 1990 | 2145267 |
| biosynthesis of glycosyl-phosphatidylinositol lipids in trypanosoma brucei: involvement of mannosyl-phosphoryldolichol as the mannose donor. | trypanosome variant surface glycoproteins (vsgs) exemplify a class of eukaryotic cell-surface glycoproteins that rely on a covalently attached lipid, glycosyl-phosphatidylinositol, for membrane attachment. the glycolipid anchor is acquired soon after translation of the polypeptide, apparently by replacement of a short sequence of carboxyl-terminal amino acids with a precursor glycolipid. a candidate glycolipid precursor (p2) and a related glycolipid (p3) have been identified in polar lipid extra ... | 1990 | 2148289 |
| the mitochondrial atp synthase of trypanosoma brucei: isolation and characterization of the intact f1 moiety. | this report describes the first isolation and molecular characterization of the mitochondrial f1-atpase from trypanosoma brucei. the isolation procedure utilized is a modified chloroform extraction procedure. in contrast to earlier reports on the f1-atpase from other trypanosomatids, the f1-atpase we have isolated from the procyclic form of t. brucei a complex composed of five distinct subunits. apparent molecular weights of these subunits are 55,000 [alpha], 42,000 [beta], 32,000 [gamma], 22,00 ... | 1990 | 2149743 |
| biosynthesis of the glycosyl phosphatidylinositol anchor of trypanosoma brucei variant surface glycoprotein. | | 1990 | 2150651 |
| nicotinamide uptake and metabolism in the procyclic form of trypanosoma brucei. | | 1990 | 2150653 |
| slacs retrotransposon from trypanosoma brucei gambiense is similar to mammalian lines. | we have characterized a retrotransposon in trypanosoma brucei gambiense uniquely associated with the spliced-leader (sl) rna gene cluster (spliced leader associated conserved sequence, slacs). there are nine copies of slacs and dna sequence analysis of one shows the hallmarks of line-1 like elements. slacs has generated a 49 bp target dna duplication at its insertion site and its 3'-end is preceded by a poly(a) stretch. two putative open reading frames (orfs) span 75% of the element. orf1 has cy ... | 1990 | 2156231 |
| the top2 gene of trypanosoma brucei: a single-copy gene that shares extensive homology with other top2 genes encoding eukaryotic dna topoisomerase ii. | a mixed oligonucleotide probe containing sequences encoding a septapeptide found in yeast, drosophila and human dna topoisomerase ii was used to screen a genomic library of trypanosoma brucei. a positive was obtained, and nucleotide sequencing shows that the entire gene encoding dna topoisomerase ii of this organism, tbrtop2, resides within the t. brucei insert of the clone. a single open reading frame of 1221 triplet codons starting from the first atg was identified; the amino acid sequence ded ... | 1990 | 2157153 |
| a comparison of the amino acid sequences of crithidia fasciculata and trypanosoma rhodesiense cytochromes c. | apocytochrome c was isolated from procyclic trypomastigotes of trypanosoma rhodesiense eatro 1895 and purified on amberlite irc-50 ion-exchange resin. tryptic peptides were generated from the purified apoprotein and a partial amino acid sequence was determined. a comparison of the amino acid sequence of crithidia fasciculata with the partial amino acid sequence of t. rhodesiense reveals significant homology. | 1990 | 2161918 |
| specific probes for trypanosoma (trypanozoon) evansi based on kinetoplast dna minicircles. | trypanosoma evansi is difficult to distinguish from other members of subgenus trypanozoon, save for its inability to develop cyclically in the tsetse fly and its characteristic kinetoplast dna (kdna). we have used cloned kdna minicircle fragments as specific probes to distinguish t. evansi from other trypanosomes of subgenus trypanozoon. two probes were required, each specific for one of the subgroups of t. evansi previously described. probe a reacted only with the major isoenzyme group of t. ev ... | 1990 | 2163493 |
| linkage of the calmodulin and ubiquitin loci in trypanosoma cruzi. | we describe here the organization of the calmodulin genes of trypanosoma cruzi and their linkage to the ubiquitin gene family. the nucleotide sequence of the cala2 gene has been determined and is 85% homologous to the protein coding sequence of the calmodulin genes of the african trypanosome, trypanosoma brucei. the proteins encoded by cala2 and the t. brucei genes contain a single mismatch out of a total of 149 amino acids. the genome of t. cruzi contains eight calmodulin genes present at two d ... | 1990 | 2167471 |
| selective inhibition of the uptake by bloodstream form trypanosoma brucei brucei of serum lipoprotein-associated phospholipid and cholesteryl ester. | to further define how culture-adapted bloodstream form trypanosoma brucei brucei take up lipoprotein-associated 3h-labelled lipids, external effectors were included in the incubation mixtures and assessed for their ability to influence lipid uptake. serum molecules of 30-85 kda, which could be replaced by albumin, selectively inhibited the uptake by culture-adapted t. b. brucei of lipoprotein-associated phospholipid and enhanced the uptake of lipoprotein-associated cholesteryl ester and choleste ... | 1990 | 2169029 |
| the trypanosoma brucei protein phosphatase gene: polycistronic transcription with the rna polymerase ii largest subunit gene. | we have previously described the trypanosomal gene encoding the largest subunit of rna polymerase ii (rnap ii) and found that two almost identical genes are encoded within the trypanosoma brucei genome. here we show by southern analyses that the 5' breakpoint between both loci is located approximately 7.5 kb upstream of the rnap ii genes. northern analyses revealed that the 5' duplicated segment contains at least four other genes, which are transcribed in both bloodstream and procyclic trypanoso ... | 1990 | 2169604 |
| organization of minicircle genes for guide rnas in trypanosoma brucei. | we have identified four t. brucei minicircle sequences that are complementary to cytochrome oxidase iii (coiii) edited mrna sequence and have shown the existence of transcripts from three of these minicircle sequences. these minicircle transcripts potentially serve as guide rnas (grnas) for rna editing of the coiii transcript. these grnas range in size from 55 to 70 nucleotides, are heterogeneous in sequence, and have a 5' terminal triphosphate. the genes for these grnas are flanked by imperfect ... | 1990 | 2171782 |
| a retroposon in the 5' flank of a trypanosoma brucei vsg gene lacks insertional terminal repeats. | a retroposon-like repeated sequence, ingi, occurs in high copy number in the genome of trypanosoma brucei brucei. an ingi is present in the 5' flank of the 5c gene, an intrachromosomal istat 1.5 variant surface glycoprotein (vsg) gene family member. the 5' end of the ingi is located 22 bp upstream of the putative vsg start codon and the ingi open reading frame is in the opposite orientation to that of the vsg gene. the termini of the ingi are not flanked by a short repeat sequence and there are ... | 1990 | 2172817 |
| targeted insertion of the neomycin phosphotransferase gene into the tubulin gene cluster of trypanosoma brucei. | kinetoplastids are unicellular eukaryotes that include important parasites of man, such as trypanosomes and leishmanias. the study of these organisms received a recent boost from the development of transient transformation allowing the short-term expression of genes reintroduced into parasites like trypanosoma brucei, the causative agent of african trypanosomiasis. we have obtained long-term stable transformants of t. brucei that have acquired the ability to grow in medium containing the drug g4 ... | 1990 | 2172836 |
| duplicative activation mechanisms of two trypanosome telomeric vsg genes with structurally simple 5' flanks. | in the mammalian bloodstream, african trypanosomes express variant surface glycoprotein (vsg) genes from a family of long and complex telomeric expression sites. vsg switching generally occurs by the duplication of different vsg genes into these sites by gene conversion involving a series of 70 base pair (70bp) repeats in the 5' flank. in contrast, when vsg is first synthesised by trypanosomes in the tsetse fly at the metacyclic stage, a separate set of telomeric expression sites is activated. t ... | 1990 | 2175429 |
| ubiquitin-ep52 fusion protein homologs from trypanosoma brucei. | | 1990 | 2175891 |
| homologous recombination and stable transfection in the parasitic protozoan trypanosoma brucei. | development of methods for the manipulation of the genomes of parasitic protozoa will lead to enhanced understanding of parasite biology and host-parasite relationships. efficient gene transfer and targeted integration by homologous recombination were achieved in the parasitic protozoan trypanosoma brucei, the causative agent of sleeping sickness. an expression vector with the neomycin phosphotransferase gene (neo), under the control of a procyclic acidic repetitive protein (parp) gene promoter, ... | 1990 | 2177225 |
| conservation of the regulatory subunit for the clp atp-dependent protease in prokaryotes and eukaryotes. | bacteria, tomatoes, and trypanosomes all contain genes for a large protein with extensive homology to the regulatory subunit, clpa, of the atp-dependent protease of escherichia coli, clp. all members of the family have between 756 and 926 amino acids and contain two large regions, of 233 and 192 amino acids, each containing consensus sequences for nucleotide binding. within these regions there is at least 85% similarity between the most distant members of the family. the high degree of similarit ... | 1990 | 2185473 |
| timing of nuclear and kinetoplast dna replication and early morphological events in the cell cycle of trypanosoma brucei. | we have used immunofluorescent detection of 5-bromo-2-deoxyuridine-substituted dna in order to determine the timing of initiation and the duration of nuclear and kinetoplast s-phases within the procyclic stage of the trypanosoma brucei cell cycle. both nuclear and kinetoplast s-phases were shown to be periodic, occupying 0.18 and 0.12 of the unit cell cycle, respectively. in addition, initiation of both of these s-phases were in approximate synchrony, differing by only 0.03 of the unit cell cycl ... | 1990 | 2190996 |
| a putative flagellar ca2(+)-binding protein of the flagellum of trypanosomatid protozoan parasites. | | 1990 | 2198539 |
| analysis of the proteinases of trypanosoma brucei. | a method comprising enzyme separation by sds-page and subsequent use of peptidyl aminomethylcoumarins as substrates has been used to study proteinases of the protozoan parasite trypanosoma brucei. the application of this method has allowed investigation of the substrate specificities of individual proteinases in cell lysates without the need for enzyme purification. the results show that t. brucei contains a group of cysteine proteinases, probably four in number, with substrate and inhibitor spe ... | 1990 | 2199606 |
| a family of glycolipid linked proteins in eimeria tenella. | a number of proteins in eimeria tenella are shown to possess a carbohydrate similar to that found on the carboxyl terminus of the variant surface glycoprotein from trypanosoma brucei. in trypanosomes, this carbohydrate is part of a glycolipid structure responsible for membrane attachment. in common with the variant surface glycoprotein and with other glycolipid linked proteins, the e. tenella proteins were shown to be hydrophobic. treatment with a crude lipase preparation from t. brucei modifies ... | 1990 | 2204829 |
| primary structure of trypanosoma cruzi small-subunit ribosomal rna coding region: comparison with other trypanosomatids. | a trypanosoma cruzi small subunit ribosomal rna gene was sequenced from genomic recombinant plasmid clones. the assigned coding region was 2319 bp, the longest ssu rrna gene described to date. on the basis of comparisons with published sequences from crithidia fasciculata, trypanosoma brucei, and leishmania donovani, we conclude that the extra nucleotides in the t. cruzi gene occur in highly variable regions of rrna genes. a phylogenetic analysis was performed with the ssu rrna sequences from th ... | 1990 | 2204830 |
| microbody phosphoglycerate kinase of trypanosoma brucei: expression and complementation in escherichia coli. | in the primitive eukaryotic parasite, trypanosoma brucei, most of the enzymes of glycolysis are located within microbody organelles called glycosomes. proteins destined for the glycosome are synthesized on free ribosomes and post-translationally translocated into the organelle. the gene, gpgk, encoding the glycosomal isozyme of phosphoglycerate kinase (gpgk), was cloned adjacent to a t7 promoter and cotransformed with a plasmid encoding t7 rna polymerase into escherichia coli pgk-cells. function ... | 1990 | 2205531 |
| study of proteolytic activities released by incubation of trypanosomes (trypanosoma brucei brucei) in ph 5.5 and ph 7.0 phosphate/glucose buffers. | proteolytic activities released by overnight incubation of antwerpeen trypanozoon antigenic type (antat) 1.1 trypanosomes at 4 degrees c in ph 5.5 and ph 7.0 phosphate/glucose buffers were analyzed in the supernatants obtained after centrifugation of the parasite suspensions. the assays used the fluorogenic substrates n-alpha-benzyloxycarbonyl-l-phenyl-alanyl-l-arginine-7-amido-4- methylcoumarin (z-phe-arg-nmec) and n-alpha-benzyloxycarbonyl-l-arginyl-l-arginine-7- amido-4-methylcoumarin (z-arg- ... | 1990 | 2207131 |
| [trypanocidal activity and plasma kinetics of cis-pt(ii) pentamidine in the parasitized sheep]. | the trypanocidal activity of cis-pt(ii) pentamidine had been demonstrated during the first phase of trypanosoma brucei brucei sheep experimental trypanosomiasis. but a subcutaneous treatment with 5 mg.kg-1 (+2 x 12 mg.kg-1) was not effective during the brain phase of trypanosomiasis. the blood pharmacokinetics of this compound had a plasmatic peak between 45 and 60 min, followed by a low decreasing phase along several days. the curve shape allowed an important interval before the following injec ... | 1990 | 2208468 |
| stage-specific adenylate cyclase activity in trypanosoma brucei. | | 1990 | 2209793 |
| the interaction of trypanosoma brucei with antibodies to variant surface glycoproteins. | binding to trypanosoma brucei of polyvalent igms and iggs, monoclonal iggs and fab1 fragments of monoclonal iggs specific for exposed epitopes of t. brucei variant surface glycoproteins (vsgs) was monitored by both immunofluorescence and immunocytochemistry. all antibodies and antibody fragments, were uniformly distributed over the parasite surface after incubation with the organism at 0 degrees c. upon warming to 37 degrees c bound antibodies and fragments were detected in the flagellar pocket ... | 1990 | 2211865 |
| [east african sleeping sickness (trypanosoma rhodesiense infection) in 2 swiss travelers to the tropics]. | we report on two swiss travellers who acquired african sleeping sickness (trypanosoma rhodesiense) the same day while visiting the akagera park in rwanda. the first patient developed clinical signs of sleeping sickness 8 days after being bitten by a tsetse fly. trypanosomes were demonstrated in the blood and csf. the other patient fell ill 13 days after the bite and trypanosomes were found only in blood samples. the first patient (cerebral trypanosomiasis), was treated with melarsoprol. he devel ... | 1990 | 2218457 |
| subcellular localisation of dihydrolipoamide dehydrogenase and detection of lipoic acid in bloodstream forms of trypanosoma brucei. | in the long-slender bloodstream form of trypanosoma brucei, the enzyme dihydrolipoamide dehydrogenase exists in the absence of the 2-oxo-acid dehydrogenase complexes of which it is normally a component, and appears to be associated with the plasma membrane of the organism [danson, m. j., conroy, k., mcquattie, a. & stevenson, k. j. (1987) biochem. j. 243, 661-665]. in the present paper, a complete subcellular fractionation of t. brucei has been carried out and, by comparison with marker enzymes, ... | 1990 | 2226451 |
| trypanosoma brucei: calcium-dependent endoribonuclease is associated with inhibitor protein. | t. brucei cytoplasmic calcium-dependent alkaline ribonuclease activity from deae-cellulose fractionation was separated into endoribonuclease and exoribonuclease activities by hydroxyapatite chromatography. t. brucei cytoplasmic extract markedly decreased the endoribonuclease activity, but slightly potentiated the activities of the exoribonuclease and bovine ribonuclease a. while the endoribonuclease was activated by trypsin, the exoribonuclease and bovine ribonuclease a were partially inactivate ... | 1990 | 2226704 |
| purification and characterization of a tartrate-sensitive acid phosphatase of trypanosoma brucei. | in search for invariant surface proteins in trypanosoma brucei bloodstream forms, acid phosphatase was investigated. earlier work had shown that part of the cellular phosphatase activity is associated with the flagellar pocket of the parasite. it is demonstrated that t. brucei contains at least two membrane-bound enzymes, one is sensitive to the inhibitor l-(+)-tartrate while the other is resistant. the tartrate-sensitive phosphatase was purified to homogeneity by monoclonal antibody affinity ch ... | 1990 | 2226816 |
| the mitochondrial trnas of trypanosoma brucei are nuclear encoded. | the mitochondrial dna of trypanosoma brucei is organized as a catenated network of maxicircles and minicircles. the maxicircles are equivalent to the typical mitochondrial genome except that the genes for the mitochondrial trnas have not been identified by sequence analysis of the maxicircle dna. the apparent absence of trna genes in the maxicircle dna suggests that the mitochondrial trnas are encoded by either the minicircle or the nuclear dna. in order to determine their genomic origin, we iso ... | 1990 | 2229071 |
| the kinetics of gene expression and maturation of il-1 alpha after induction with the surface coat of trypanosoma brucei rhodesiense or lipopolysaccharide. | the purpose of this study was threefold: to determine if the variant surface coat glycoprotein (vsg) of trypanosoma brucei rhodesiense induces il-1 alpha; to study the kinetics of il-1 alpha transcription, maturation and secretion; and to compare vsg to lps in its ability to induce il-1 alpha. vsg was added to cultures of the p388d1 murine macrophage cell line. rna was dotted onto nitrocellulose and hybridized with a murine il-1 alpha cdna probe. maximal production of il-1 alpha mrna occurred in ... | 1990 | 2230129 |
| phase-contrast study of the efficacy of lampit (bay 2502, nifurtimox) on experimental infection with trypanosoma rhodesiense. | lampit (bay 2502, nifurtimox) was tested in experimental wistar strain white rats with acute infection induced by trypanosoma rhodesiense strain (180 ts1a1), which normally contains cytoplasmic granules of both type (i) & (ii). lampit injected subcutaneously in low doses of 25, 50, 100, and 250 mg/kg b-w as one-time application, gave no effect. when repeated higher doses (500 mg/kg b-w) was given a reasonable effect was achieved and formation of additional granules in t. rhodesiense was noticed. ... | 1990 | 2230339 |
| 2.9 a resolution structure of the n-terminal domain of a variant surface glycoprotein from trypanosoma brucei. | the variant surface glycoprotein (vsg) of trypanosoma brucei forms a coat on the surface of the parasite; by the expression of a series of antigenically distinct vsgs in the surface coat the parasite escapes the host immune response. the 2.9 a resolution crystal structure of the n-terminal domain of one variant, mitat 1.2, has been determined. the structure was solved using data collected from two crystal forms. initially a partial model was built into an electron density map based on multiple i ... | 1990 | 2231728 |
| effects of e. coli endotoxin, some interferon-inducers, recombinant interferon- alpha 2a and trypanosoma brucei infection on feed intake in dwarf goats. | | 1990 | 2231875 |
| chromosome organization of the protozoan trypanosoma brucei. | the genome of the protozoan trypanosoma brucei is known to be diploid. karyotype analysis has, however, failed to identify homologous chromosomes. having refined the technique for separating trypanosome chromosomes (l. h. t. van der ploeg, c. l. smith, r. i. polvere, and k. gottesdiener, nucleic acids res. 17:3217-3227, 1989), we can now provide evidence for the presence of homologous chromosomes. by determining the chromosomal location of different genetic markers, most of the chromosomes (14, ... | 1990 | 2233733 |
| structure of a telomeric expression site for variant specific surface antigens in trypanosoma brucei. | we have studied the organization of the expression site, in which most chromosome-internal variant-specific surface glycoprotein (vsg) genes of trypanosoma brucei strain 427 are expressed (the dominant expression site) and compared it to the previously characterized vsg 221 expression site. with the exception of a 500 bp segment and a vsg pseudogene, which are absent from the dominant expression site, overall all major sequence elements of the two sites are organized similarly, as judged from th ... | 1990 | 2233894 |
| kinetoplast dna minicircles are inherited from both parents in genetic hybrids of trypanosoma brucei. | we have examined the inheritance of kinetoplast dna (kdna) in gentic crosses of trypanosomes. in 2 independent crosses of trypanosoma brucei spp. trypanosomes, the kdna maxicircles which carry the genes for mitochondrial biogenesis, were inherited from one parent only, as already found by other workers. however, the other component of kdna, the minicircles, were inherited from both parents. this was demonstrated by southern analysis using cloned minicircle probes. the inheritance of kdna is ther ... | 1990 | 2233899 |
| gene targeting. how efficient can you get? | | 1990 | 2234072 |
| genetic exchange and evolutionary relationships in protozoan and helminth parasites. | the study of genetic exchange systems and the use of genetic analysis has been relatively limited in parasites leading to considerable gaps in our basic knowledge. this lack of knowledge makes it difficult to draw firm conclusions as to how these systems evolved. an additional problem is also raised by the difficulties in defining evolutionary distances particularly with the unicellular protozoa, using classical ultrastructural and cytological criteria. while these difficulties have by no means ... | 1990 | 2235065 |
| a comparison of multiplication rates in primary and challenge infections of trypanosoma brucei bloodstream forms. | the hypothesis that division of trypanosoma brucei slender bloodstream forms is dependent upon the availability of a host-derived growth factor has been tested by superimposing challenge doses of slender-form trypanosomes onto preexisting infections at a time during the primary infection when stumpy forms predominated. the challenge populations grew in the doubly-infected mice indicating that depletion of a putative growth factor by the expanding population of the primary infection had not preve ... | 1990 | 2235074 |
| cloning and sequencing of the cysteine protease cdna from trypanosoma brucei rhodesiense. | | 1990 | 2235508 |
| the trypanosome leucine repeat gene in the variant surface glycoprotein expression site encodes a putative metal-binding domain and a region resembling protein-binding domains of yeast, drosophila, and mammalian proteins. | we have identified a new variant surface glycoprotein expression site-associated gene (esag) in trypanosoma brucei, the trypanosome leucine repeat (t-lr) gene. like most other esags, it is expressed in a life cycle stage-specific manner. the n-terminal 20% of the predicted t-lr protein resembles the metal-binding domains of nucleic acid-binding proteins. the remainder is composed of leucine-rich repeats that are characteristic of protein-binding domains found in a variety of other eucaryote prot ... | 1990 | 2247064 |
| stability and reconstitution of the soluble variant surface glycoprotein (svsg) from trypanosoma brucei. | soluble variant surface glycoprotein (svsg) is the form of the coat protein of trypanosoma brucei released by cleavage of its lipid anchor. as shown by ultracentrifugal analysis, the protein of the variant clone mitat 1.2 is a stable dimer of (117 +/- 6)-kda molecular mass. its quaternary structure remains unaltered in the concentration range from 0.01 to approximately 50 mg/ml. further extrapolation to the in situ concentration on the cell surface points to no significant protein association be ... | 1990 | 2252884 |
| trypanocidal potentials of african woody plants: in vitro trial of khaya grandifoliola seed extracts against trypanosoma brucei brucei. | | 1990 | 2255214 |
| effects of morinda lucida leaf extract on trypanosoma brucei brucei infection in mice. | the dried leaves of morinda lucida were extracted with 50% methanol and the extract was recovered in a 9.7% w/w yield. acute toxicity tests were performed in mice and the intraperitoneal ld50 of the extract was 2000 mg/kg. the extract induced purgation in mice from the first hour after oral administration and reached its peak between the third and fourth hour. the purgation was not dose-dependent. m. lucida leaf extract i.p. significantly suppressed the level of parasitemia after trypanosoma bru ... | 1990 | 2259218 |
| a gene from the vsg expression site of trypanosoma brucei encodes a protein with both leucine-rich repeats and a putative zinc finger. | the transcription unit of the gene for the variant specific glycoprotein (vsg) antat 1.3a of trypanosoma brucei contains several associated genes (esags, for expression site-associated genes), 7 of which have already been described. we report here the characterization of a further esag, which we term esag 8, present 1 kb downstream from the putative adenylate cyclase gene esag 4. esag 8 encodes a 70 kd protein whose sequence indicates that it is probably not exposed at the cell surface. with the ... | 1990 | 2259625 |
| [antisense oligonucleotides: tools of molecular genetics and therapeutic agents]. | the binding of an oligodeoxynucleotide, so-called anti-sense, to the complementary sequence of a messenger rna can prevent the synthesis of the encoded protein. this approach constitutes a very efficient and specific means to artificially regulate gene expression. numerous chemical modifications have been introduced into synthetic oligos in order to provide them with properties that unmodified molecules do not display. for instance, oligos built up with methylphosphonate, phosphorothioate and al ... | 1990 | 2264671 |
| sexual stages in trypanosomes and implications. | the basis for concluding that a system of genetic exchange exists in african trypanosomes of the trypanosoma brucei group is outlined by the accumulated data from variation in natural parasite populations and from laboratory crossing experiments. the results indicate that these parasites can complete their life cycle either with or without genetic exchange. this sexual event involves meiosis and syngamy, but the order of these processes and the sexual stages involved are not yet known. | 1990 | 2264676 |
| [antigenic variation of african trypanosomes]. | although several hundred of different antigen genes exist in the trypanosome genome, only one is usually expressed at a time. this expression occurs in one of several possible telomeric expression sites. besides being exclusively telomeric, transcription of the antigen gene exhibits other particular characteristics: the rna polymerase is highly resistant to alpha-amanitin, and the transcription unit comprises several other genes, one of which may encode an adenylate cyclase. post-transcriptional ... | 1990 | 2264683 |
| [the slow progress in the control of sleeping sickness]. | the century-old controls methods of t. gambiense infection foci have not been changed significantly in the past decennias. the technical improvements are restricted to (1) the introduction of serological diagnosis bringing a marked gain in sensitivity as compared to lymph node palpation, (2) new parasite concentration methods for corroborating the diagnosis and (3) the design of cheap and efficient traps for glossina. none of these methods however, although smooth to perform and plain in design, ... | 1990 | 2264691 |
| active transport of 2-deoxy-d-glucose in trypanosoma brucei procyclic forms. | the characteristics of glucose transport by procyclic forms of trypanosoma brucei were examined in a rapid transport assay using the glucose analogue 2-deoxyglucose. in contrast to bloodforms where the km for 2-deoxyglucose transport is about 1 mm, procyclic forms have a km of about 38 microm. procyclic forms show temperature-dependent, saturable import, and import of 2-deoxyglucose is competitive with glucose and mannose. unlike the bloodforms which employ facilitated diffusion, the procyclic f ... | 1990 | 2270102 |
| an allele of trypanosoma brucei cytoplasmic phosphoglycerate kinase is a mosaic of other alleles and genes. | | 1990 | 2270112 |
| future prospects for the chemotherapy of human trypanosomiasis. 2. combination chemotherapy and african trypanosomiasis. | this paper reviews the progress which has been achieved with combination chemotherapy of experimental murine central nervous system trypanosomiasis. successful treatments have been achieved with suramin followed by 5-nitroimidazoles; difluoromethylornithine in combination with bleomycin, 9-deazainosine, suramin, arsenicals, antimonials and diamidines; and also the arsenicals in combination with the 5-nitroimidazoles or nifurtimox. pretreatment with prednisolone and azathioprine, to minimize reac ... | 1990 | 2278054 |
| a comparative study of the infectivity of t.b. rhodesiense isolates from man to 3 species of small laboratory rodents. | to confirm an earlier observation, that some t.b. rhodesiense isolates from sleeping sickness cases had failed to infect normally susceptible wistar rats, blood samples, freshly drawn from 21 patently parasitaemic ss patients, were each inoculated simultaneously into 3 swiss t.o. white mice, 3 young wistar rats and 3 mastomys natalensis. with the sole exception of one mastomys, which failed to become infected, the 21 stocks infected all the inoculated rodents. levels and durations of parasitaemi ... | 1990 | 2279470 |
| genetic exchange in african trypanosomes. | african trypanosomes are important pathogens of humans and domestic animals, but little was known, until recently, of the genetic system of these parasites. recent results demonstrate the existence of nonobligatory genetic exchange between different stocks of t. brucei. a number of models have been put forward for the mechanism of genetic exchange, including a fusion model with subsequent random loss of chromosomes and a more conventional mendelian system. | 1990 | 2281527 |
| an expression-site-associated gene family of trypanosomes is expressed in vivo and shows homology to a variant surface glycoprotein gene. | utilizing first-strand cdna from different stages, a gene family was identified that is expressed in bloodstream form trypanosomes but not in cultured procyclic forms. this family of 50-100 genes, termed bloodstream-specific 1 (bs1), shares a chromosomal distribution pattern similar to the variant surface glycoprotein (vsg) genes and the expression-site-associated genes (esags). the bs1 genes are expressed in several variants of trypanosoma brucei brucei and in trypanosoma brucei gambiense. sequ ... | 1990 | 2290439 |
| characterisation of protein kinase c like activities in trypanosoma brucei. | protein kinase activities in bloodstream and procyclic forms of trypanosoma brucei have been partially purified and characterised. cytosolic extracts were separated on deae-cellulose and assayed for the ability to phosphorylate histone in the presence of ca2+ and diacylglycerol. five peaks of activity were identified in bloodstream t. brucei and only three in procyclic lysates. one of the kinases present in bloodstream t. brucei shares may characteristics with mammalian protein kinase c. further ... | 1990 | 2290440 |
| purification and characterization of glycerol kinase from trypanosoma brucei. | glycerol kinase (ec 2.7.1.30)(gk) from the glycosomes of trypanosoma brucei has been purified and its kinetic properties have been examined. it has a molecular weight of approximately 53,000 and exists in solution as a monomer. this gk has a broad ph optimum, with equal activity between ph 7 and 9.5. its catalytic mechanism appears to be random bi bi, with some cooperativity in substrate binding at high ph. the apparent michaelis constants are: kglycerol = 0.26 +/- 0.02 mm and katp = 0.19 +/- 0. ... | 1990 | 2290444 |
| synergistic activity of 5-substituted 2-nitroimidazoles (ro 15-0216 and benznidazole) and dl-alpha-difluoromethylornithine on trypanosoma brucei brucei. | the antitrypanosomal activity of two 5-substituted 2-nitro-imidazoles (ro 15-0216 and benznidazole) and alpha-dl-difluoro-methylornithine (dfmo) was tested in four stocks of trypanosoma brucei brucei in vitro. the ic50 (drug concentration which inhibits growth of trypanosome populations by 50%) values ranged from 0.27-1.0 for ro 15-0216, 84-265 for benznidazole, and 147-691 microm for dfmo. potentiation of antitrypanosomal activity of the combination of ro 15-0216 and dfmo was demonstrated in a ... | 1990 | 2291692 |
| cationic antiprotozoal drugs. trypanocidal activity of 2-(4'-formylphenyl)imidazo[1,2-a]pyridinium guanylhydrazones and related derivatives of quaternary heteroaromatic compounds. | a series of quaternary 2-phenylimidazo[1,2-a]pyridinum salts has been prepared and evaluated for antiparasitic activity. primary attention was focused on derivatives with amido, substituted hydrazone, and heterocyclic functionality at the para position of the phenyl substituent. guanylhydrazones and n-substituted guanylhydrazones of the 4'-formyl-substituted compounds are very active against the blood state trypanosoma rhodesiense in mice by subcutaneous or oral administration. the most potent c ... | 1990 | 2296025 |
| synthesis, structure, and antiparasitic activity of sulfamoyl derivatives of ribavirin. | the triazole nucleoside derivatives 1-(5'-o-sulfamoyl-beta-d-ribofuranosyl) [1,2,4]triazole-3-carboxamide (2), 1-(5'-o-sulfamoyl-beta-d-ribofuranosyl) [1,2,4]triazole-3-thiocarboxamide (3), and 1-(5'-o-sulfamoyl-beta-d-ribofuranosyl)-[1,2,4]triazole-3- carbonitrile (4) were synthesized. suitably protected triazole nucleosides were converted to their corresponding 5'-sulfamoyl derivatives, which on subsequent deprotection gave the desired compounds in good yields. the structures of compounds 2-4 ... | 1990 | 2296034 |
| cyclical differentiation of trypanosoma brucei involves changes in the cellular complement of calmodulin-binding proteins. | the present study was undertaken to evaluate changes in the complement of calmodulin-binding proteins which accompany cyclical differentiation in trypanosoma brucei. an [125i]trypanosome calmodulin overlay procedure was used to detect calmodulin-binding proteins with mr of 126,000 and 106,000 that were present in homogenates of slender bloodstream froms but were absent in procyclic culture forms. competition assays with unlabeled bovine brain or trypanosome calmodulins indicated that the develop ... | 1990 | 2298276 |
| methylating agents as trypanocides. | methylating agents, such as streptozotocin, procarbazine, n-methyl-n-nitrosourea, dimethyl sulfate, 1,2-dimethylhydrazine, and a series of 1,2-bis(sulfonyl)-1-methylhydrazines synthesized in this laboratory, were evaluated and shown to be therapeutically active against murine models of african trypanosomiasis. at high dose levels, methylating agents halted trypanosome proliferation and transformed cells into bizarre forms containing multiple nuclei and kinetoplasts. these cells disappeared from ... | 1990 | 2299638 |
| trypanosome variant surface glycoprotein transfer to target membranes: a model for the pathogenesis of trypanosomiasis. | the variant surface glycoprotein (vsg) of trypanosomes is attached to the cell surface by means of a phosphatidylinositol-containing glycolipid membrane anchor. the studies presented in this paper support the hypothesis that the transfer of vsg from trypanosomes to erythrocytes could lead to one of the pathological features associated with trypanosome infection--i.e., anemia. migration of trypanosome vsg from live trypanosomes to target cells (sheep erythrocytes) could be shown by preincubating ... | 1990 | 2300563 |
| purification and assembly in vitro of tubulin from trypanosoma brucei brucei. | trypanosome tubulin was purified to near homogeneity by chromatography on deae-sephadex, amicon filtration and assembly-disassembly in vitro. polymerization of the tubulin in vitro yielded long, structurally normal, microtubules and some sheet structures on addition of gtp and incubation at 37 degrees c, in either the presence or the absence of mg2+. tubulin assembly was disrupted by glycerol and a selection of microtubule-reactive drugs. immunological analysis of the purified tubulin revealed t ... | 1990 | 2302174 |
| characterisation of the asparagine-linked oligosaccharides from trypanosoma brucei type-i variant surface glycoproteins. | the complete primary structures of the asn-linked oligosaccharides from the conserved glycosylation site of the type-i variant surface glycoproteins of trypanosoma brucei mitat 1.4 and mitat 1.6 were determined using a combination of exoglycosidase digestions, permethylation analysis, acetolysis and 1h nmr. both variants contained almost exclusively oligomannose-type oligosaccharides, identical in structure to those of mammalian glycoproteins. the oligosaccharides ranged in size from (man)9(glcn ... | 1990 | 2303059 |
| freeze-fracture study of the bloodstream form of trypanosoma brucei gambiense. | the ultrastructure of trypanosoma brucei gambiense was investigated by the freeze-fracture method. three different regions of the continuous plasma membrane; cell body proper, flagellar pocket, and flagellum were compared in density and distribution of the intramembranous particles (imp's). the imp-density was highest in the flagellar pocket membrane and lowest in flagellum. intra membranous particles of the cell body membrane were distributed uniformly on both the protoplasmic (p) and exoplasmi ... | 1990 | 2304029 |
| rna editing. sometimes an editor makes sense. | | 1990 | 2304546 |
| trypanosoma brucei: two-dimensional gel analysis of the major glycosomal proteins during the life cycle. | kinetoplastid organisms possess a unique organelle, the glycosome, which compartmentalizes the embden-meyerhof segment of glycolysis and several other metabolic pathways. in trypanosoma brucei many of the enzyme activities localized to the glycosome are stage regulated. two-dimensional gel analysis was used to examine the characteristics, expression, and biosynthesis of the major glycosomal proteins. two-dimensional gel maps of glycosomes from slender bloodforms and late intermediate-stumpy bloo ... | 1990 | 2311710 |
| a drug incubation infectivity test (diit) for assessing resistance in trypanosomes. | blood stream forms of drug-resistant and sensitive trypanosoma brucei brucei, trypanosoma brucei evansi and trypanosoma vivax were incubated in a liquid medium for 24 h at 37 degrees c in the presence of various concentrations of diminazene aceturate (berenil) or isometamidium chloride (samorin), and assayed for infectivity in mice. whereas the infectivity to mice of all samorin-sensitive trypanosomes was decreased after incubation with 1 ng samorin ml-1, the samorin-resistant stocks remained in ... | 1990 | 2316178 |
| telomere interactions may condition the programming of antigen expression in trypanosoma brucei. | the antat 1.1 antigen type typically occurs late in a chronic infection by the eatro 1125 stock of trypanosoma brucei. the antat 1.1 gene, which is located 24 kb from a chromosome end, seems exclusively expressed by acting as a donor in gene conversion events targeted to the telomeric expression site. we report that this gene is sufficiently provided with the homology blocks required for recombination with the expression site, and is not interrupted by stop codons up to the 3' block of homology. ... | 1990 | 2323332 |
| solubilization and partial purification of glycerol-3-phosphate oxidase from mitochondria of trypanosoma brucei. | | 1990 | 2323400 |
| the 5s ribosomal rna genes of crithidia fasciculata. | | 1990 | 2325709 |
| identification and sequence analysis of the ribosomal dna promoter region of crithidia fasciculata. | we have identified the promoter region of the large ribosomal dna repeat unit of crithidia fasciculata by northern blotting and nuclear run-on analyses. these data show that transcription starts approximately 1 kb upstream of the 18s rrna gene. s1 protection experiments and sequence analysis of this area resulted in a precise localization of the start site. we have been unable to identify conserved sequence element(s) by a direct comparison of the crithidial rna polymerase i promoter region and ... | 1990 | 2326181 |