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)

Antigens that bind to erythrocytes were identified in the supernatant fluids of a cultured human malaria parasite (Plasmodium falciparum). A 175-kilodalton (175K) antigen bound only to erythrocytes susceptible to invasion. The 175K antigen from the Camp or the FCR-3 strain also bound to merozoites. However, the antigen did not bind to merozoites when merozoites and supernatant antigens were from different strains unless proteinase inhibitors were present. Moreover, erythrocytes coated with supernatant antigens from the Camp or FCR-3 strain were invaded normally by merozoites of the homologous strain but were partially resistant to invasion by merozoites of the heterologous strain. The 175K antigen may be a receptor acting as a "bridge" between erythrocytes and merozoites.
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PMID:A Plasmodium falciparum antigen that binds to host erythrocytes and merozoites. 390 Dec 57

WR 33063, a phenanthrene methanol, was studied in human volunteers for tolerance and toxicity. In normal volunteers, it was possible to give 4.6 g in four divided doses without adverse effect for 10 days. At this dose level, there was neither evidence of photosensitivity nor adverse renal or cardiac effect. At a dose level of 1.6 g in four divided doses for 6 days, WR 33063 cured 18 of 23 nonimmune volunteers infected with the Smith strain of Plasmodium falciparum from Vietnam. In addition, infections due to the Marks and Braithwaite Vietnam strains were also treated because these strains represent a major therapeutic challenge to chloroquine; six of six and two of three volunteers, respectively, were cured. With the Malayan Camp strain, 1.6 g in four divided doses for 6 days cured all of five volunteers. The African Uganda I strain of chloroquine-responsive malaria was even more responsive to WR 33063; all of six men who received 1.6 g in four divided doses for 6 days were cured, and all of three men who received this same dosage for 3 days were cured. One subject infected with a Haitian strain of P. falciparum was treated and cured. Blood-induced infections with the Chesson strain of P. vivax also responded well to WR 33063 with four of five men cured. In all, 52 men received WR 33063 in tolerance trials, and 59 men with experimental malaria and one man with clinical malaria were treated with WR 33063.
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PMID:A phenanthrene methanol (WR 33063) for treatment of acute malaria. 459 14

WR 30090 at a dose of 230 mg every 8 hr for 6 days has proven to be a safe, well-tolerated compound with photosensitivity proving to be a minor consideration. WR 30090 was found to be an effective medication for the treatment of acute malaria caused by several strains of Plasmodium falciparum. At the dose of 230 mg every 8 hr for 6 days, all of six men infected with a chloroquine-susceptible strain (Uganda I) were cured, all of 13 subjects infected with moderately chloroquine-resistant strains (Malayan Camp, Malayan Taylor, and Philippine Per) were cured, and 19 of 23 subjects infected with strains highly resistant to chloroquine (Vietnam Smith and Vietnam Crocker) were cured. All of five subjects infected with the chloroquine-resistant Vietnam Marks strain were cured with only 3 days of therapy. Blood-induced P. vivax (Chesson strain) infection showed a mixed response. Six out of seven volunteers were cured when treated for 3 days with WR 30090. The one recrudescence responded to a repeated course of therapy for 3 days. However, recrudescence occurred in one volunteer treated for 6 days. Treatment with WR 30090 failed to cure sporozoite-induced P. vivax (Chesson strain) infection in any of four subjects. In all subjects treated, there was good suppression of parasitemia and relief of symptoms. The susceptibility of the strains of malaria to WR 30090 to some degree parallels their susceptibility to chloroquine.
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PMID:A quinoline methanol (WR 30090) for treatment of acute malaria. 459 15

The extent to which human antibodies involved in functional immunity react with antigenic determinants varying between different isolates or strains of the human malaria parasite Plasmodium falciparum will influence the design of vaccines against malaria. We identified nine immune sera from Cambodian refugees which blocked in vitro invasion of erythrocytes by merozoites of the Camp strain of P. falciparum and agglutinated Camp strain merozoites. However, none of these sera blocked invasion of erythrocytes by merozoites of the FCR-3 strain. We conclude that antibodies in these human sera recognized antigenic determinants present on the surface of viable merozoites of the Camp strain but not the FCR-3 strain. These parasite strains and in vitro assays can be used to analyze strain-specific functional immunity in humans.
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PMID:Plasmodium falciparum strain-specific human antibody inhibits merozoite invasion of erythrocytes. 637 1

Camp and Smith strains of the human malaria parasite Plasmodium falciparum became resistant to mefloquine after continuous cultivation in the presence of the drug. The 50% inhibitory dose (ID(50)) values for mefloquine, as assessed by [(3)H]hypoxanthine incorporation, were found to have increased 4-fold, from 3 mug/l to 12 mug/l. The ID(50) values obtained by morphological examination of the cultures increased 10-fold. Resistance was stable in both strains either when grown in a drug-free medium or when kept frozen in liquid nitrogen. The mefloquine-resistant Camp strain remained sensitive to chloroquine and amodiaquine, and became slightly more resistant to quinine; there was increased sensitivity to pyrimethamine. The mefloquine-resistant Smith strain remained sensitive to amodiaquine and resistant to pyrimethamine; there was increased resistance to quinine, and an increase in sensitivity to chloroquine.
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PMID:Plasmodium falciparum: mefloquine resistance produced in vitro. 638 Jul 85

Infections with the Uganda Palo Alto, Malayan Camp-CH/Q, Vietnam Oak Knoll, and Vietnam Smith strains of Plasmodium falciparum in owl monkeys (Aotus trivirgatus griseimembra) with concomitant microfilaremias usually, but not always, followed a more benign course than infections with the same strains in monkeys free of filarial infections. Four distinct microfilariae were identified in systematic examinations of 26 monkeys, 5 with self-limited infections with P. falciparum, 9 with normally benign self-limited infections with P. vivax, and 12 without previous malaria. The microfilariae found included: Dipetalonema (Dipetalonema) gracile, Tetrapetalonema (Tetrapetalonema) barbascalensis, T. (T.) panamensis, and an unidentified species designated "Aotus C." Among 23 monkeys studied completely, 14 were infected with a single species, 4 had double infections, and 5 had triple infections. T. barbascalensis was identified in 16 monkeys, T. panamensis in 11. Although data were very limited, there was a suggestion that infections with P. falciparum were less intense in monkeys infected with T. barbascalensis, either alone or with other filariae, than in subjects infected only with T. panamensis.
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PMID:Courses of infections with Plasmodium falciparum in own monkeys displaying a microfilaremia. 701 Oct 72

A report was made of 4 cases of chloroquine resistant Plasmodium falciparum infections. The infections, detected in Jakarta, were imported from Kotabumi, Tanjung Karang, the Island of Pidada in the Lampung Province and from Pangkalpinang on the Island Bangka in the Province of South Sumatra. Treatment with courses of 1500 mg chloroquine base and with increased dosages up to 2250 mg base failed to cure the patients. The chloroquine sensitivity test in vitro was carried out in 3 patients, which showed that the Plasmodium falciparum strains were resistant to chloroquine at the R I level. The strains appeared to be similar to the Malaya Camp strain. In vivo observations revealed that the parasites were resistant at the R I level with a delayed recrudescence. The chloroquine resistant falciparum malaria cases, acquired in South Sumatra, may therefore be regarded as the first reported cases from a focus outside the already known two foci in Indonesia, namely East Kalimantan and Irian Jaya. It may be expected that chloroquine resistant Plasmodium falciparum will be encountered in other parts of Indonesia in the near future. The use of a combination of sulfadoxine and pyrimethamine should not be recommended in Indonesia because chloroquine is still considered the drug of choice against all malaria infections in Indonesia.
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PMID:Chloroquine resistant Plasmodium falciparum infection from Lampung and South Sumatra, Indonesia. 702 96

Plasmodium falciparum-infected human erythrocytes evade host immunity by expression of a cell-surface variant antigen and receptors for adherence to endothelial cells. These properties have been ascribed to P. falciparum erythrocyte membrane protein 1 (PfEMP1), an antigenically diverse malarial protein of 200-350 kDa on the surface of parasitized erythrocytes (PEs). We describe the cloning of two related PfEMP1 genes from the Malayan Camp (MC) parasite strain. Antibodies generated against recombinant protein fragments of the genes were specific for MC strain PfEMP1 protein. These antibodies reacted only with the surface of MC strain PEs and blocked adherence of these cells to CD36 but without effect on adherence to thrombospondin. Multiple forms of the PfEMP1 gene are apparent in MC parasites. The molecular basis for antigenic variation in malaria and adherence of infected erythrocytes to host cells can now be pursued.
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PMID:Cloning the P. falciparum gene encoding PfEMP1, a malarial variant antigen and adherence receptor on the surface of parasitized human erythrocytes. 760 74

Plasmodium falciparum malaria merozoites invade human erythrocytes bearing sialic acid in a multistage process involving the sialic acid-dependent binding of a malaria molecule, the 175-kD erythrocyte binding antigen (EBA-175). We show here that after the initial interaction of EBA-175 with its sialic acid-containing erythrocyte determinant, endogenous proteases can cleave EBA-175 to 65-kD fragment(s), whose binding to erythrocytes is sialic acid independent. A 65-kD fragment was immunoprecipitated by antibodies against peptides between residues 354 and 1061 but not beyond residue 1062. Binding experiments utilizing combinations of native protein, expression-PCR-synthesized EBA-175 polypeptides, peptide synthesis, and antibodies, demonstrated that sialic acid-independent binding could be further mapped to a small (about 40-amino acid) homologous part of the dimorphic allelic region of EBA-175, residues 898-938 (Camp strain numbering). These data support a two-step binding hypothesis and are discussed in relation to the formation of a junction between the merozoite and the erythrocyte, and the finding that after the interaction of some viruses with specific cellular receptors, they undergo conformational changes or cleavage permitting membrane fusion with the host cell.
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PMID:Evidence for two-stage binding by the 175-kD erythrocyte binding antigen of Plasmodium falciparum. 822 3

The erythrocyte binding antigen EBA-175 is a 175-kDa Plasmodium falciparum protein which mediates merozoite invasion of erythrocytes in a sialic acid-dependent manner. The purpose of this study was to produce recombinant EBA-175 polypeptide domains which have previously been identified as being involved in the interaction of EBA-175 with erythrocytes and to determine whether these polypeptides are recognized by malaria-specific antibodies. The eba-175 gene was cloned by PCR from genomic DNA isolated from the 3D7 strain of P. falciparum. The predicted protein sequence was highly conserved with that predicted from the published eba-175 gene sequences from the Camp and FCR-3 strains of P. falciparum and contained the F segment divergent region. Purified recombinant EBA-175 polypeptide fragments, expressed as glutathione S-transferase fusion proteins in insect cells by using the baculovirus system, were recognized by antibodies present in serum from a drug-cured, malaria-immune Aotus nancymai monkey. The fusion proteins were also recognized by antibodies present in sera from individuals residing in areas where malaria is endemic. In both cases the antibodies specifically recognized the EBA-175 polypeptide portion of the fusion proteins. Antibodies raised in rabbits immunized with the recombinant fusion proteins recognized parasite proteins present in schizont-infected erythrocytes. Our results suggest that these regions of the EBA-175 protein are targets for the immune response against malaria and support their further study as possible vaccine components.
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PMID:Baculovirus-mediated expression of Plasmodium falciparum erythrocyte binding antigen 175 polypeptides and their recognition by human antibodies. 928 29


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