Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

On a model pair Aedes aegypti--Plasmodium gallinaceum in has been shown that changes in the conditions of larvae development caused by the addition into the water medium of the live culture of Synochocystis sp. cyanobacteria or green seaweeds Chlorella vulgaris, acetone extracts from the live culture precipitate or Chlorella powder, as well as nitrogen-containing fertilizer--ammonium chloride did not lower the sensitivity of the imago flying to malaria parasites. The results of the experiments assessing the effect of biologically active compounds introduced into the larvae habitation medium on the ability to change sensitivity of the survived mosquito females to malaria agent have been summed up. The data obtained are indicative of the high level of mutual adaptation between mosquito-carriers and malaria parasites.
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PMID:[Experimental research on the effect of biologically active substances on the susceptibility of mosquitoes to the causative agent of malaria. 3. Algae, fertilizers]. 164 59

The previously described Plasmodium falciparum blood stage antigen, 5.1 (also referred to as exp-1) was expressed at a high level in Escherichia coli. Saimiri monkeys immunised with purified recombinant antigen 5.1 were partially protected from P. falciparum blood stage parasite challenge. The gene coding for 5.1 was combined with DNA coding for an (Asn-Ala-Asn-Pro)19 sequence (abbreviated (NANP)19 in the one-letter amino acid code). To facilitate purification of the recombinant protein, DNA coding for a hexahistidine (His6) sequence was introduced at the 5' end of the gene (proteins containing His6 have high affinity for Ni(2+)-chelate columns even in the presence of 6 M guanidine HCl). The recombinant protein, His6-5.1-(NANP)19 with an apparent molecular size of 40 kDa could be highly purified by a combination of 4 steps: (1) release and solubilization of the recombinant fusion protein from E. coli in the presence of 6 M guanidine-HCl; (2) precipitation of over 60% of the bacterial proteins by the addition of ammonium sulphate to 50% saturation; (3) affinity chromatography on a Ni(2+)-chelate column in the presence of 6 M guanidine-HCl; (4) adsorption onto a cation exchange resin in the presence of 6 M urea, and elution with an increasing NaCl gradient. Compared with the previously tested tetanus toxoid-(NANP)3 malaria vaccine, this protein elicits an anti-(NANP)n response which more closely resembles that evoked by native sporozoites. The recombinant vaccine also induces the production of antibodies against the blood stages of the malaria parasite.
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PMID:A Plasmodium falciparum malaria vaccine candidate which contains epitopes from the circumsporozoite protein and a blood stage antigen, 5.1. 171 16

Plasma membrane electron transport was studied in a protozoan cell, Tetrahymena pyriformis, by assaying transmembrane ferricyanide reduction and the reduction of iron compounds. The rates of ferricyanide reduction varied between 0.5 and 2.5 mumol/g dry wt. per min, with a pH optimum at 7.0-7.5. Other active non-permeable electron acceptors, with redox potentials from +360 to -125 mV, were cytochrome c, hexaammine ruthenium chloride, ferric-EDTA, ammonium ferric citrate, and indigo di-, tri- and tetrasulfonates. It was found that Tetrahymena cells can reduce external electron acceptors with redox potentials at pH 7.0 down to -125 mV. Ferricyanide stimulates ciliary action. Transmembrane ferricyanide reduction by Tetrahymena was not inhibited by such mitochondrial inhibitors as antimycin A, 2-n-heptyl-4-hydroxyquinoline N-oxide, or potassium cyanide, but it responded to inhibitors of glycolysis. Transmembrane ferricyanide reduction by Tetrahymena appears to involve a plasma membrane electron transport chain similar to those of other animal cells. As in other cells, the transmembrane electron transport is associated with proton release which may be involved in internal pH control. The transmembrane redox system differs from that of mammalian cells in a 20-fold greater sensitivity to chloroquine and quinacrine. The Tetrahymena ferricyanide reduction is also inhibited by chlorpromazine and suramin. Sensitivity to these drugs indicates that the transplasma membrane electron transport and associated proton pumping may be a target for drugs used against malaria, Trypanosomes and other protozoa.
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PMID:Chloroquine-sensitive transplasmalemma electron transport in Tetrahymena pyriformis: a hypothesis for control of parasite protozoa through transmembrane redox. 190 70

Methods were developed for the production of clinical grade malaria vaccine candidates expressed in E. coli by recombinant DNA technologies. The essential features of the purification protocol consist of (1) mechanical breakage of host cells and solubilization of the recombinant proteins in 6 M guanidine hydrochloride; (2) ammonium sulfate fractionation; (3) affinity chromatography on a Ni(2+)-chelate gel in the presence of 6 M guanidine hydrochloride; and (4) ion exchange chromatograph on a Phospho Ultrogel column in the presence of 6 M urea. The use of undesirable chemicals (PMSF, DFP, TFA, acetonitrile, etc.) was avoided rather than demonstrating their complete removal after the purification steps. Testing of chromatographic fractions for host-cell proteins and the elimination of fractions with E. coli protein content was found necessary to obtain a final product that contained less than 0.01% of host derived proteins. The recombinant proteins were renatured either from 8 M urea or from 6 M guanidine hydrochloride by increasing the pH to 10.5 in the presence of glycine and EDTA, reduction with DTT, dilution to a protein concentration below 1 mg.ml-1, and dialysis against 0.9% NaCl. The method presented here can be tailor-fit, with minor modification, for the purification of almost any recombinant protein and the final product satisfies current regulations concerning the production of clinically acceptable therapeutic products.
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PMID:Preparation of clinical grade proteins produced by recombinant DNA technologies. 194 Mar 92

Chloroquine and ammonium chloride, by virtue of their basic properties, have been shown to raise endocytic and lysosomal pH and thereby interfere with normal iron metabolism in a variety of cell types, including mononuclear phagocytes. Cellular iron metabolism is of critical importance to Legionella pneumophila, an intracellular bacterial pathogen whose capacity to multiply in human mononuclear phagocytes is dependent upon the availability of intracellular iron. In view of this, we have studied the effects of chloroquine and ammonium chloride on L. pneumophila intracellular multiplication in human monocytes. Chloroquine, at a concentration of 20 microM, and ammonium chloride, at a concentration of 20 mM, inhibited L. pneumophila intracellular multiplication by 1.4 +/- 0.2 (SEM) logs and 1.5 +/- 0.2 logs, respectively. Chloroquine- and ammonium chloride-induced inhibition of L. pneumophila intracellular multiplication was completely reversed by iron nitrilotriacetate, an iron compound which is soluble in the neutral to alkaline pH range, but not by iron transferrin, which depends upon acidic intracellular conditions to release iron. Chloroquine had no major direct effect on L. pneumophila multiplication in artificial media except at extremely high concentrations (15,000-fold that which inhibited L. pneumophila multiplication in mononuclear phagocytes), and inhibition at such concentrations was not reversed by iron nitrilotriacetate. This study demonstrates that chloroquine and ammonium chloride inhibit the intracellular multiplication of L. pneumophila by limiting the availability of iron to the bacterium. It is possible that such a mechanism of action underlies chloroquine's antimicrobial effect against other intracellular pathogens, such as the agents of malaria and tuberculosis.
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PMID:Chloroquine inhibits the intracellular multiplication of Legionella pneumophila by limiting the availability of iron. A potential new mechanism for the therapeutic effect of chloroquine against intracellular pathogens. 205 29

Zygotes and ookinetes of the rodent malaria Plasmodium berghei can be enriched 50-fold, from whole blood cultures by ammonium chloride lysis. Three monoclonal antibodies (MoAbs) raised against such enriched preparations specifically bind to a determinant of Mr 21 kD as assessed by 125I-labelled goat anti-mouse IgG probed immunoblots of Western transfers of SDS-PAGE gels. Indirect immunofluorescence indicates that the 21 kD determinant bound by specific MoAbs, whilst not detectable on gametocytes or gametes, appears on the parasite surface within 2 h of exflagellation/fertilization and increases thereafter. The three MoAbs specifically binding the 21 kD determinant block oocyst development in mosquitoes by at least 90%, as assessed either by in-vitro membrane feeds or by live feeds on passively immunized mice. These MoAbs reduce ookinete formation in vitro by between 52 and 100%. Possible mechanisms of action of these MoAbs are discussed.
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PMID:Ookinete antigens of Plasmodium berghei. Appearance on the zygote surface of an Mr 21 kD determinant identified by transmission-blocking monoclonal antibodies. 245 31

Stable human hybridomas were generated that produced inhibitory anti-Plasmodium falciparum monoclonal antibodies. Peripheral blood lymphocytes, obtained from adults in Liberia, a malaria endemic area, were immortalized with Epstein-Barr virus and then fused with KR4, a human, lymphoblastoid cell line. Stable hybridomas that produced anti-P. falciparum monoclonal antibody were identified by an ELISA assay that used the trophozoite and schizont antigens of both the Honduras I and FCR3 parasite strains. Monoclonal antibodies produced by selected hybridomas derived from lymphocytes of two individuals were subsequently studied. The anti-parasite antibodies were produced at 1-3 micrograms/ml in culture supernatants. All of the monoclonal antibodies bound specifically to trophozoites and schizonts of both strains of parasite in an indirect immunofluorescence assay and inhibited production of ring stage parasites by more than 90% when added to trophozoite or schizont containing erythrocytes in culture. Western immunoblot analysis of antigens obtained from trophozoites and schizonts (parasite age span of 36 to 48 h) was performed using either affinity purified or ammonium sulfate-concentrated monoclonal antibody. Antibody from three hybridomas which bound primarily to antigens of the Honduras 1 strain had Mr of approximately 140,000, 130,000 and 123,000.
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PMID:Plasmodium falciparum-inhibitory monoclonal antibodies produced by human hybridomas. 329 24

The immunodominant repeat region of the malaria circumsporozoite protein from Plasmodium falciparum was purified from a recombinant Escherichia coli to study as a potential subunit vaccine. The recombinant protein, R32Leu-Arg, is composed of 32 tetrapeptide repeat sequences from the circumsporozoite protein (R32) linked to the dipeptide, Leu-Arg. R32Leu-Arg was purified by a series of precipitation steps including temperature, ammonium sulfate, and acid pH treatments; followed by reversed-phase high-performance liquid chromatography (RP-HPLC). An automated RP-HPLC assay was developed to measure the R32Leu-Arg concentration during both fermentation and purification. This assay was used in a variety of applications including measurement of production levels of the antigen during fermentation, evaluation of the protein purification process, quantitation of protein recovery, and as one criterion of protein purity. With minimal changes, the assay conditions were easily adapted to the semi-preparative level to produce 200 mg of purified product. The purified product was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; amino acid composition; and analytical size-exclusion and RP-HPLC.
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PMID:Assay, purification and characterization of a recombinant malaria circumsporozoite fusion protein by high-performance liquid chromatography. 332 67

The viability of erythrocyte-free malaria parasites (Plasmodium yoelii) was assessed with the cationic fluorescent dye, rhodamine 123 (R123). Parasites were freed from infected mouse erythrocytes either by saponin lysis or by Tris-ammonium chloride lysis and incubated with R123 at 37 degrees C. The parasite-associated dye was extracted with iso-butanol and measured with a fluorescent spectrophotometer. R123 accumulated intensely in free parasites prepared by saponin lysis but only weakly in those prepared by Tris-NH4Cl. Very little dye accumulated in free parasites fixed with 2% glutaraldehyde or with 3.7% formaldehyde, or in those heated at 50 degrees C for 15 min. Similar results were obtained by observations with an epifluorescent microscope. Free parasites incubated in hypotonic solutions did not accumulate the dye. Only parasites intensely accumulating R123 incorporated [3H] hypoxanthine. These results indicate that only living parasites are stained with R123, which can therefore be used to monitor the viability of erythrocyte-free malaria parasites.
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PMID:A method for monitoring the viability of malaria parasites (Plasmodium yoelii) freed from the host erythrocytes. 361 88

The molecular characteristics of a serum IL-2 inhibitor were determined by fractionating active sera from normal and malaria-infected mice, and assaying inhibitory activity in blocking production and expression of IL-2 activity. Using isoelectric focusing and ion exchange chromatography, the activity resolved in a single peak (pI = 6.2). HPLC gel filtration resolved two peaks of activity (50,000 and 25,000 MW) which are probably related. The molecule is precipitated by 50% saturated ammonium sulphate, and is destroyed by heating above 56 degrees or by acidification below pH 4.
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PMID:Serum IL-2 inhibitor in mice. II. Molecular characteristics. 387 70


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