| the ribosomes of the simian malaria plasmodium knowlesi--ii. a cell-free protein synthesizing system. | | 1976 | 4281 |
| plasmodium knowlesi in the marmoset (callithrix jacchus). | common marmosets were shown to be susceptible to plasmodium knowlesi malaria. the morphology of the parasite was indistinguishable from the observed in the natural host (macaca fascicularis) and the common laboratory model (macaca mulatta). a differential susceptibility to p. knowlesi was observed in the 8 marmosets studied. multiplication rates of parasites were variable over 24 h periods. five animals died of a fulminating infection within 12--17 days after challenge. three animals recovered s ... | 1979 | 33359 |
| the duffy blood group determinants: their role in the susceptibility of human and animal erythrocytes to plasmodium knowlesi malaria. | duffy blood group negative erythrocytes from blacks are refractory to invasion by plasmodium knowlesi merozoites in vitro, and blacks with this genotype are resistant to infection by p. vivax in vivo. in order to evaluate in a direct manner the role of duffy blood group determinants in invasion by p. knowlesi merozoites, we studied erythrocytes from three rare non-black duffy negative individuals, fy(a-b-), in whom the duffy negative phenotype probably represents a mutation and not the introduct ... | 1977 | 70210 |
| antigenic variation in african trypanosomiasis: a memorandum. | after reviewing the present knowledge on antigenic variation of the trypanosomes of the trypanosoma (trypanozoon) brucei species, this memorandum discusses the relevance of this phenomenon to the possible development of new tools for trypanosomiasis control.as antigenic variation is related to protective immunity and immunopathology, it is of crucial importance for the feasibility of vaccine development and for treatment principles. it is also of interest as a model for understanding antigenic v ... | 1977 | 74295 |
| two plasmodium knowlesi-specific antigens on the surface of schizont-infected rhesus monkey erythrocytes induce antibody production in immune hosts. | purified schizonts (6--10 nuclei) and membranes of schizont-infected erythrocytes from the malaysian and philippine strain of plasmodium knowlesi are analyzed immunochemically using immunoglobulin of rhesus monkey hyperimmune sera against schizonts and of sera from naturally immune monkeys. the anti-schizont ig identifies less than 20 immune components in triton x-100-solubilized schizonts and membranes of infected cells. of these antigens, 9 (component 1, 3, 4, 5, 6, 10, 11, 18, and 20) are com ... | 1979 | 87490 |
| synthesis of plasmodium knowlesi polypeptides in a cell-free system. | preliminary results are presented concerning the characterization of plasmodium knowlesi antigens. rna with messenger activity has been extracted from p. knowlesi and translated in a rabbit reticulocyte cell-free system. the products of this system have been analysed both before and after precipitation with specific p. knowlesi antiserum and many polypeptides ranging in molecular weight from over 100 000 to approximately 20 000 have been found. a good correlation was found between these results ... | 1979 | 94553 |
| erythrocyte entry by malarial parasites. a moving junction between erythrocyte and parasite. | invasion of erythrocytes by merozoites of the monkey malaria, plasmodium knowlesi, was investigated by electron microscopy. the apical end of the merozoite makes initial contact with the erythrocyte, creating a small depression in the erythrocyte membrane. the area of the erythrocyte membrane to which the merozoite is attached becomes thickened and forms a junction with the plasma membrane of the merozoite. as the merozoite enters the invagination in the erythrocyte surface, the junction, which ... | 1978 | 96121 |
| malaria immunization in rhesus monkeys. a vaccine effective against both the sexual and asexual stages of plasmodium knowlesi. | rhesus monkeys were immunized with a preparation of plasmodium knowlesi parasites containing principally microgametes with lesser numbers of macrogametes and asexual trophozoites. the antigen mixture was emulsified in freund's complete adjuvant (fca) and administered intramuscularly. after one or two inoculations of from 10(5) to 10(7) microgametes in fca, monkeys showed high levels of circulating anti-gamete antibodies as demonstrated by various in vitro microgamete immobilization or transmissi ... | 1978 | 102724 |
| infection of the squirrel monkey saimiri sciureus, with plasmodium knowlesi. | | 1978 | 104412 |
| interaction between cytochalasin b-treated malarial parasites and erythrocytes. attachment and junction formation. | we have previously demonstrated that invasion of erythrocytes (rbcs) by malaria merozoites follows a sequence: recognition and attachment in an apical orientation associated with widespread deformation of the rbc, junction formation, movement of the junction around the merozoite that brings the merozoite into the invaginated rbc membrane, and sealing of the membrane. in the present paper, we describe a method for blocking invasion at an early stage in the sequence. cytochalasin-treated merozoite ... | 1979 | 105074 |
| plasmodium knowlesi-induced antigens in membranes of parasitized rhesus monkey erythrocytes. | highly purified plasmodium knowlesi schizonts were used to produce a hyperimmune anti-parasite serum in a rhesus monkey. proteins of membranes from normal and p. knowlesi-infected erythrocytes, as well as purified schizonts, were solubilized in 1% triton x-100 and analyzed by bidimensional electrophoretic techniques. of seven parasite-specific antigens identified in membranes of parasitized erythrocytes by crossed immune electrophoresis against monkey anti-parasite serum, only three could be det ... | 1978 | 105359 |
| antigenic analysis of sequential erythrocytic stages of plasmodium knowlesi. | the antigenic composition of sequential erythrocytic stages of plasmodium knowlesi has been compared by crossed immuno-electrophoresis using a pool of immune rhesus monkey antiserum. eleven major parasite antigens have been identified; 9 are stage-independent, and 2 stage-dependent. differences in the relative amount of the stage-independent antigens have been demonstrated and quantified. the distribution of antigens between parasites and schizont and infected red cell membranes has been examine ... | 1978 | 107503 |
| macaca assamensis as a new host for experimental plasmodium knowlesi infection. | | 1978 | 108217 |
| enhancement of a simian malarial infection (plasmodium cynomolgi) in mosquitoes fed on rhesus (macaca mulatta) previously infected with an unrelated malaria (plasmodium knowlesi). | | 1979 | 111568 |
| some properties of membranes in the simian malaria parasite plasmodium knowlesi. | | 1979 | 115391 |
| glucose metabolism in the simian malaria parasite plasmodium knowlesi: activities of the glycolytic and pentose phosphate pathways during the intraerythrocytic cycle. | | 1979 | 118712 |
| plasmodium knowlesi: inhibition of invasion by pretreatment of erythrocytes with chloroquine and quinine. | | 1979 | 119458 |
| freeze fracture studies on the interaction between the malaria parasite and the host erythrocyte in plasmodium knowlesi infections. | the freeze fracture technique has been used to study the internal cyto-architecture of the surface membranes of the parasite and erythrocyte in plasmodium knowlesi infections. six fracture faces, derived from the plasma membrane and 2 pellicular membranes, have been identified at the surface of the free merozoite. the apposed leaflets of the 2 pellicular membranes show the characteristic features of e fracture faces, a result compatible with the view that the pellicular membranes line a potentia ... | 1979 | 120521 |
| fractionation of plasmodium knowlesi-induced antigens of rhesus monkey erythrocyte membranes. | in order to characterize parasite-induced host cell membrane antigens, the plasma membranes of plasmodium knowlesi-infected rhesus erythrocytes have been compared with those of normal red cells and purified schizonts by immunochemical and biochemical techniques. host cell membranes and schizonts were separated by differential centrifugation following nitrogen decompression. isolated schizonts were further fractionated into several subcellular compartments. crossed-immune electrophoresis, against ... | 1979 | 120762 |
| immunization of rhesus monkeys with blood-stage antigens of plasmodium knowlesi. | evaluation of the efficacy of 3 nonviable blood-stage antigens-schizont ag, merozoite ag, and "french press" ag-of plasmodium knowlesi, emulsified in freund's complete adjuvant (fca), was carried out in a study involving 32 rhesus monkeys. after 2 immunizations, administered 6 weeks apart, monkeys were challenged with a variant of p. knowlesi different from that used for immunization. all 8 control monkeys that received either pbs or fca developed a severe parasitaemia and died of the infection ... | 1979 | 120763 |
| preliminary studies on vaccination of rhesus monkeys with irradiated sporozoites of plasmodium knowlesi and characterization of surface antigens of these parasites. | studies were conducted to develop an effective method of inducing protection against sporozoite-induced malaria in a primate system and to obtain information regarding the surface membrane antigens of sporozoites. immunization of rhesus monkeys was performed with gamma-irradiated sporozoites of plasmodium knowlesi. levels of antisporozoite antibodies were monitored by immunofluorescence, sporozoite neutralization, and the circumsporozoite precipitate reaction, and appeared to correlate well with ... | 1979 | 120766 |
| factors affecting the in vitro culture of plasmodium falciparum and plasmodium knowlesi. | plasmodium falciparum and plasmodium knowlesi have been established in continuous culture using the basic method of trager & jensen. various parameters of the culture system have been examined, namely, the gas requirements, serum and red cell requirements, frequency of medium replacement, and a comparison of static and agitated cultures made. the most important factors affecting growth in vitro seem to be the oxygen tension, red cell concentration, the frequency with which old medium is replaced ... | 1979 | 120767 |
| localization and chemical characterization of plasmodium knowlesi schizont antigens. | the identification of malarial antigens that induce protective immunity could provide a rational basis for developing an effective antimalarial vaccine as well as specific serodiagnostic tests indicative of clinical immune status. since protective immunity is probably induced by stage-dependent rather than stage-independent antigens, the antigenic composition of different stages of plasmodium knowlesi has been compared, and a limited chemical characterization undertaken. this information should ... | 1979 | 120777 |
| blood schizontocidal activity of some antibiotics against plasmodium knowlesi infection in assamese monkey. | | 1979 | 121297 |
| tumorigenicity of epstein-barr virus (ebv)-transformed lymphoid line cells in autologous squirrel monkeys. | eight squirrel monkeys (saimiri sciureus) challenged with ebv or ebv-transformed slcl were naturally or experimentally infected with plasmodium knowlesi or pl. brasilianum. most of the animals had been splenectomized and unilaterally nephrectomized. three of these monkeys received one dose of 6 to 12 x 10(8) autologous slcl. these lines were derived from saimiri lymphoid cells permanently transformed by b-ebv in vitro. all three animals developed multiple undifferentiated malignant lymphomas and ... | 1976 | 179960 |
| nor-mdp, saponin, corynebacteria, and pertussis organisms as immunological adjuvants in experimental malaria vaccination of macaques. | vaccination of primates against malaria using antigen derived from erythrocytic parasite stages has been most successful where freund's complete adjuvant has been employed. since this adjuvant is clinically unacceptable its replacement is a matter of urgency.in the present work a muramyldipeptide derivative (nor-mdp) given in mineral oil has proved to be partially effective as an adjuvant for merozoite vaccination of macaca mulatta against plasmodium knowlesi, and saponin has proved to be effect ... | 1979 | 232428 |
| recent advances in understanding the invasion of erythrocytes by merozoites of plasmodium knowlesi. | previous observations on the process of invasion by p. knowlesi are briefly reviewed and new findings concerning the adhesion of parasites to erythrocytes and their intracellular passage are reported. merozoites adhere to erythrocytes by means of a well-defined coat with the cytochemical characteristics of glycoprotein. this coat has receptors that engage in at least three distinct types of attachment. the ensuing invagination of the erythrocyte surface has two phases, the first consisting of an ... | 1977 | 303947 |
| evidence for differences in erythrocyte surface receptors for the malarial parasites, plasmodium falciparum and plasmodium knowlesi. | human erythrocytes lacking various blood group determinants were susceptible to invasion by plasmodium falciparum including duffy-negative erythrocytes that are refractory to invasion by plasmodium knowlesi. erythrocytes treated with trypsin or neuraminidase had reduced susceptibility of p. falciparum and normal susceptibility to p. knowlesi. chymotrypsin treatment (0.1 mg/ml) blocked invasion only by p. knowlesi. the differential effect of enzymatic cleavage of determinats from the erythrocyte ... | 1977 | 327014 |
| transport of amino acids and nucleic acid precursors in malarial parasites. | in vitro studies have shown that exogenously supplied amino acids are transferred into the malaria-infected cell, where they are incorporated into proteins. most amino acids appear to enter the cell by facilitated or simple diffusion; however, the high distribution ratios seen in plasmodium knowlesi-infected cells are difficult to explain on this basis. the changes (leakiness) observed in amino acid transport in p. lophurae infected cells are probably the result of atp depletion in the host cell ... | 1977 | 338180 |
| amino acid metabolism and protein synthesis in malarial parasites. | malaria-infected red cells and free parasites have limited capabilities for the biosynthesis of amino acids. therefore, the principal amino acid sources for parasite protein synthesis are the plasma free amino acids and host cell haemoglobin. infected cells and plasmodia incorporate exogenously supplied amino acids into protein. however, the hypothesis that amino acid utilization (from an external source) is related to availability of that amino acid in haemoglobin is without universal support: ... | 1977 | 338183 |
| sporozoites of rodent and simian malaria, purified by anion exchangers, retain their immunogenicity and infectivity. | sporozoites of rodent malaria, plasmodium berghei, and simian malaria, plasmodium knowlesi and plasmodium cynomolgi, were partially separated from mosquito debris and microbial contaminants by passage of anopheles material through a deae-cellulose column. in addition to eliminating most of the contaminants (80-90%), this simple technic has made it possible to recover rapidly large numbers of viable sporozoites (55-75% yield), which have retained their infectivity, immunogenicity, and capacity to ... | 1978 | 351177 |
| freeze-fracture study of malaria sporozoites: antibody-induced changes of the pellicular membrane. | plasmodium cynomolgi, plasmodium knowlesi, and plasmodium berghei sporozoites, before and after incubation with immune serum, were studied after freeze-fracture by electron microscopy. there were evenly distributed numerous intramembranous particles (imp) on the p face of the outer membrane. the e face of the plasma membrane had fewer imp than its p face. the e face of the intermediate membrane had few imp and also linear arrays of slightly raised ridges running the length of the parasite. the p ... | 1979 | 385856 |
| [erythrocyte blood groups and geographic pathology (author's transl)]. | blood groups are an obstacle to reproduction, transfusion and transplantation. there are immunological abortions due to the antibodies of "p" phenotype women; and rh haemolytic disease of the new-born is in direct proportion to the frequency of the "r" gene in a given population; the problem of transfusional allo-immunisation is completely parallel. certain membrane anomalies (due to exceptional erythrocyte blood groups--rh null, rh mod or mcleod, for example), can provoke hemolytic anaemias, bu ... | 1979 | 400037 |
| plasmodium knowlesi: functional immunity and antimerozoite antibodies in rhesus monkeys after repeated infection. | | 1977 | 402285 |
| long-term studies on rhesus monkeys (macaca mulatta) immunized against plasmodium knowlesi. | studies carried out on four rhesus monkeys (macaca mulatta) that had been vaccinated against plasmodium knowlesi show that the immunized animals were protected against a challenge with a heterologous strain of p. knowlesi. this protection was shown to be present even 4 years after the immunization schedule has been completed. the effect could not be attributed toprevious infections with the parasite, since four control rhesus monkeys that had recovered from one to four challenges with p. knowles ... | 1977 | 403136 |
| attempts to immunize monkeys against plasmodium knowlesi by using heat-stable, serum-soluble antigens. | thirty-six macaca mulatta monkeys were immunized with different concentrations and regimens of heat-stable, serum-soluble (s-) antigens of plasmodium knowlesi prior to challenge with the homologous parasite via sporozoite inoculation. fewer deaths and reduced maximum parasitemias occurred in those animals inoculated with 10 to 40 mg of s-antigen compared to nonimmunized monkeys or those receiving only freund's adjuvant. protection was incomplete, however, suggesting that atibodies to s-antigens ... | 1977 | 405876 |
| a freeze-dried merozoite vaccine effective against plasmodium knowlesi malaria. | | 1977 | 406111 |
| differences in the virulence of plasmodium knowlesi for macaca irus (fascicularis) of philippine and malayan origins. | this report summarizes the results of a comparative study of the virulence of the "s-m," h, and c strains of p. knowlesi for indian rhesus monkeys (macaca mulatta) and cynomolgus monkeys [m. irus (fascicularis)] of malayan (west malaysia) and philippine origins. each of the above strains produced fulminating, uniformly fatal infections in the rhesus monkey and mild, chronic infections, characterized by relatively low level parasitemias in cynomolgus monkeys of philippine origin. in striking cont ... | 1977 | 407808 |
| plasmodium knowlesi: in vitro biosynthesis of methionine and thymidylic acid. | | 1977 | 408170 |
| hypothesis on the mechanism of erythrocyte invasion by malaria merozoites. | plasmodium knowlesi merozoites invade erythrocytes by a sequence of events: attachment, widespread deformation of the erythrocyte membrane, endocytosis, and resealing of the membrane and vesicle. the possible mechanisms by which these events occur are discussed. in particular, there is a detailed discussion of the role of the duffy blood group system in invasion. | 1977 | 412599 |
| a freeze-fracture study on the parasite-erythrocyte interrelationship in plasmodium knowlesi infections. | freeze-fracture studies were made on the parasite and the erythrocyte in p. knowlesi infections. there is a loss of transmembrane integral proteins from the plasma membrane of the schizont-infected erythrocyte and the intraerythrocytic parasite synthesizes new transmembrane proteins as development proceeds. formation of the parasitophorous vacuole includes changes in the number of integral proteins present in the vacuolar membrane, indicating that this membrane may be modified by and in part der ... | 1977 | 412600 |
| labelling of membrane glycoprotein in erythrocytes infected with plasmodium knowlesi. | normal rhesus monkey erythrocytes and erythrocytes infected by p. knowlesi were labelled with galactose oxidase (ec 1.1.3.9) and tritiated sodium borohydride. the glycoproteins of normal erythrocytes were not labelled unless the cells were pretreated with neuraminidase, when peaks of activity with apparent molecular weights of 170 000, 126 000, 90 000, 50 000, and 35 000 were observed. schizont-infected erythrocytes showed an absence of glycoprotein labelling even after neuraminidase treatment. ... | 1977 | 412601 |
| release of protein by erythrocytic stages of plasmodium knowlesi during cultivation in vitro. | erythrocytes infected with schizonts of p. knowlesi and labelled in vitro with (3)h-isoleucine were shown to release radioactivity when placed in unlabelled culture medium containing uninfected erythrocytes. release of radiolabel probably occurred during schizont rupture and invasion of new erythrocytes and was not observed to any great extent at earlier stages in the erythrocytic life cycle. approximately 55% of the released radioactivity was soluble in 10% trichloroacetic acid, the remainder b ... | 1977 | 412603 |
| preservation of intraerythrocytic forms of malarial parasites by one-step and two-step cooling procedures. | ring, trophozoite, and schizont stages of plasmodium knowlesi were cooled in dimethyl sulfoxide either by direct immersion in liquid nitrogen or by a two-step method in which the cells were held at temperatures slightly below 0 degrees c for different lengths of time before they were cooled to -196 degrees c. after the direct plunge treatment, thawed trophozoites and schizonts were found to be extensively damaged. their survival was markedly increased by holding them at -31 degrees c for 30 min ... | 1977 | 412605 |
| a review of metozoite vaccination against plasmodium knowlesi malaria. | techniques for the isolation of merozoites of plasmodium knowlesi malaria have allowed their use in experimental vaccines. rhesus monkeys were protected to a very great extent from otherwise lethal challenge with this malaria when freund's complete adjuvant was a vaccine component. | 1977 | 413214 |
| antibody mediated mechanisms of immunity to malaria induced by vaccination with plasmodium knowlesi merozoites. | rhesus monkeys vaccinated with merozoites in fca are protected against challenge with several strains and variants of plasmodium knowlesi. vaccination induces sterilizing immunity which is species specific. merozoite-blocking (inhibitory) antibody usually correlates with clinical immunity and protection can be passively transferred with immune sera provided these contain high levels of inhibitory antibody. however, vaccination using adjuvants other than fca may induce inhibitory antibody without ... | 1978 | 414993 |
| plasmodium knowlesi malaria in the rhesus monkey. | twelve rhesus monkeys were inoculated intravenously with about 500 000 malaria parasites, plasmodium knowlesi. acute hemolysis occurred 5 days later, and all animals died on the 6th or 7th day after inoculation. all organs were gray-green to gray-brown because of deposition of hemoglobin and malaria pigments. this deposition was particularly striking in the lung, brain, abdominal fat and serous surfaces. microscopic changes indicative of acute hypoxia were found in the liver (centrilobular necro ... | 1978 | 415405 |
| antigenic change in plasmodium knowlesi. | | 1977 | 605469 |
| the resistance factor to plasmodium vivax in blacks. the duffy-blood-group genotype, fyfy. | duffy-blood-group-negative human erythrocytes, fyfy, are resistant to invasion in vitro by plasmodium knowlesi. the fyfy genotype is found predominantly in african and american blacks, who are the only groups completely resistant to infection by p. vivax. to determine if the fyfy genotype is the vivax resistance factor, we performed blood typing on 11 black and six white volunteers who had been exposed to the bites of p. vivax-infected mosquitoes. only the five fyfy blacks were resistant to eryt ... | 1976 | 778616 |
| studies on the structure and invasive behaviour of merozoites of plasmodium knowlesi. | | 1975 | 807001 |
| vaccination against plasmodium knowlesi malaria. | | 1975 | 809872 |
| ribonucleic acid synthesis in plasmodium knowlesi maintained both in vivo and in vitro. | rna extracted from purified parasites of plasmodium knowlesi was fractionated using agarose gel electrophoresis. preparations from para sites grown both in vivo and in vitro contained species of rna with sedimentation coefficients of 4-0s, 5-0s, 16-6s, 24-2s, 31-4s, 38-0s and 48-3s. there was less rna present in parasites grown in vitro than the equivalent stage parasites grown in vivo but the proportional amounts of the various species of rna was similar in both cases. it is suggested that the ... | 1975 | 810760 |
| simian plasmodium knowlesi malaria: studies of coagulation and pathology. | uniformly fatal simian malaria was induced in ten rhesus monkeys by injection of plasmodium knowlesi. the results of serial studies of platelet and blood coagulation factor levels suggested the occurrence of intravascular coagulation during the last 48 hours of the disease, concurrent with a marked fall in hematocrit levels. fibrinogen survival was slightly decreased (two animals), but quantitative fibrinogen levels were elevated. pathologic studies revealed only minimal evidence of fibrin depos ... | 1975 | 811125 |
| the ribosomes of the simian malaria, plasmodium knowlesi. i. isolation and characterization. | monomeric ribosomes, isolated from the monkey malaria plasmodium knowlesi by the combined use of low concentrations of triton x-100 and differential centrifugation, sedimented in the 80s range and could be dissociated into 60 and 40s subparticles. the base composition of the rrna was typically protozoan; that is, low in guanine and cytosine residues. | 1975 | 811791 |
| in vitro isolation of plasmodium knowlesi merozoites using polycarbonate sieves. | a culture chamber fitted with a polycarbonate sieve has been used to isolate plasmodium knowlesi merozoites as they are released from schizonts. a 3 mum pore-size sieve allows passage of normal erythrocytes and red cells containing rings and trophozoites and can be used to concentrate schizonts from a mixed cell population. a 2 mum pore-size sieve retains normal and parasitized cells and provides uncontaminated merozoites in high yield (5 x 10(10) merozoites per ml schizonts). merozoite viabilit ... | 1975 | 812040 |
| analysis of the phospholipid composition of plasmodium knowlesi and rhesus erythrocyte membranes. | | 1976 | 816224 |
| plasmodium knowlesi: morphology and course of infection in rhesus monkeys treated with clindamycin and its n-demethyl-4'-pentyl analog. | | 1976 | 820562 |
| spectroscopic evidence for the uneven distribution of adenine and uracil residues in ribosomal ribonucleic acid of drosophila melanogaster and of plasmodium knowlesi and its possible evolutionary significance. | rna was isolated from subribosomal particles of the malaria parasite plasmodium knowlesi. the nucleotide composition (mole fraction) of the principal species was obtained (s-rrna, 0.295a, 0.36u, 0.25g, 0.105c: l-rrna, 0.326a, 0.31u, 0.228g, 0.144c). ribosomal rna was also isolated from drosophila melanogaster. optical properties of these a + u-rich species were measured. in all four cases analysis of the hypochromic effect revealed that adenine and uracil residues tended to form clusters along t ... | 1976 | 821475 |
| delayed dermal hypersensitivity in rhesus monkeys (macaca mulatta) immunized against plasmodium knowlesi. | eighteen rhesus monkeys were immunized with a fresh or lyophilized antigen preparation obtained from erythrocytes infected with plasmodium knowlesi. sixteen of these monkeys showed a positive delayed hypersensitivity response when subsequently skin tested with the immunizing antigen. ten of the 16 positive reactors survived a p, knowlesi challenge, the remaining 6 showed several indications of protection. none of the 18 control monkeys gave a positive skin reaction or survived the challenging in ... | 1976 | 822621 |
| ultrastructural study of plasmodium knowlesi antigen used in vaccination of rhesus monkeys. | material from various steps obtained in the french pressure cell technic of preparing antigen from plasmodium knowlesi-infected red cells, was examined by elctron microscopy. a positively charged colloidal iron solution was used to differentiate between membranes of host red cells and parasites. red cell membranes take the stain, wheras parasite membranes do not. this antigen which has been used previously to protect monkeys against p. knowlesi appears to consist almost entirely of membrane-boun ... | 1976 | 823328 |
| the preparation of malaria haemagglutination antigen. | methods of preparing malaria antigen were compared. in one experiment a ficoll density gradient was used to obtain a purified suspension of plasmodium knowlesi schizonts from which antigen was prepared. evaluation of methods such as freeze-thawing and the use of the french press following saponin lysis of schizonts demonstrated that a single freeze-thaw was the best method for obtaining the most antigen. a second experiment was done comparing the antigen prepared from schizont infected erythrocy ... | 1976 | 823879 |
| plasmodium knowlesi: in vitro biosynthesis of methionine. | | 1976 | 824155 |
| the effect of incubation in vitro on the susceptibility of monkey erythrocytes to invasion by plasmodium knowlesi. | rhesus monkey erythrocytes when incubated in vitro under similar conditions to those used for the cultivation of plasmodium knowlesi-infected erythrocytes in vitro, exhibit an increase both in their osmotic fragility and in the activity of their acetylthiocholinesterase. no effect was observed on the catabolism of glucose through the glycolytic pathway or through the primary dehydrogenases of the pentose phosphate pathway. the atp content of normal monkey erythrocytes was also unchanged during i ... | 1976 | 824605 |
| malaria (plasmodium knowlesi) merozoites: immunity and the surface coat. | immune serum agglutinated merozoites of plasmodium knowlesi in culture. agglutinated merozoites attached to erythorcytes but were usually unable to invade. marked aggregation of merozoites was associated with reduced invasion of erythrocytes in these cultures. the agglutination and reduced invasion were immunologically specific, for the effect of serum was greatest against homologous strains of p. knowlesi. merozoite agglutination was caused by the binding of surface coats on adjacent parasites. ... | 1975 | 1117140 |
| erythrocyte receptors for (plasmodium knowlesi) malaria: duffy blood group determinants. | duffy blood group negative human erythrocytes (fyfy) are resistant to infection by plasmodium knowlesi, a simian malaria that infects duffy positive human erythrocytes. the p. knowlesi resistance factor, duffy negative erythrocytes, occurs in high frequency in west africa, where the people are resistant to vivax malaria. this suggests that duffy blood group determinants (fya or fyb) may be erythrocyte receptors for p. vivax. | 1975 | 1145213 |
| merozoite vaccination against plasmodium knowlesi malaria. | free malarial merozoites isolated from in vitro cultures of p. knowlesi and emulsified with freund's complete (fca) or incomplete (fia) adjuvant were used to vaccinate twelve rhesus monkeys against the uniformly lethal infection caused by p. knowlesi. initial challenge of six monkeys with the same parasite variant as used for vaccination produced no detectable infection in three monkeys, while three others developed low-grade parasitaemia (maximum 1.5 per cent), which terminated after 6-11 days. ... | 1975 | 1158390 |
| structure and invasive behaviour of plasmodium knowlesi merozoites in vitro. | the structure and invasive behaviour of extracellular erythrocytic merozoites prepared by a cell sieving method have been studied with the electron microscope. free merozoites contain organelles similar to those described in late schizonts of plasmodium knowlesi. their surface is lined by a coat of short filaments. on mixing with fresh red cells, merozoites at first adhere, then cause the red cell surface to invaginate rapidly, often with the formation of narrow membranous channels in the red ce ... | 1975 | 1202413 |
| status of oxidative stress and antioxidant defences during plasmodium knowlesi infection and chloroquine treatment in macaca mulatta. | plasmodium knowlesi (a simian malarial parasite) infection resulted in elevation of hepatic oxidative stress in monkeys. further, the antioxidant defence system of the host was also noticeably affected. the infected monkeys showed a marked increase in the levels of superoxide (o2-), lipid peroxidation (lpo), glutathione (gsh) and xanthine oxidase (xo), and decreased levels of superoxide dismutase (sod) and catalase. oral administration of chloroquine (20 mg kg body wt-1 for 3 days) to infected m ... | 1992 | 1316884 |
| stereoselective synthesis and antimalarial activity of alpha-artelinic acid from artemisinin. | alpha-artelinic acid [8], a potent, stable, and water-soluble antimalarial agent, has been synthesized from artemisinin [1], the sesquiterpene lactone endoperoxide isolated from artemisia annua. the blood schizontocidal antimalarial activity of alpha-artelinic acid evaluated against plasmodium knowlesi is also reported. | 1992 | 1431937 |
| a family of erythrocyte binding proteins of malaria parasites. | malaria erythrocyte binding proteins use the duffy blood group antigen (plasmodium vivax and plasmodium knowlesi) and sialic acid (plasmodium falciparum) on the erythrocyte surface as receptors. we had previously cloned the one p. vivax gene, the one p. falciparum gene, and part of one of the three p. knowlesi genes encoding these erythrocyte binding proteins and described the homology between the p. knowlesi and p. vivax genes. we have completed the cloning and sequencing of the three p. knowle ... | 1992 | 1496004 |
| studies on glycolytic enzymes of plasmodium knowlesi, a simian malaria parasite, and infected host erythrocytes. | almost all of the important enzymes of glycolytic sequence were studied in isolated schizonts of plasmodium knowlesi as well as in normal and p. knowlesi parasitized rhesus red blood cells. significant activities of all the glycolytic enzymes assayed were observed in cell-free schizonts and the levels of all were found to be considerably elevated in infected host erythrocytes, confirming that the consumption of glucose is dramatically increased in host red cells, consequent to malaria infection. | 1992 | 1520983 |
| alterations in host regulatory glycolytic enzymes during pathogenesis of primate malaria and following chloroquine therapy. | hexokinase, phosphofructokinase and pyruvate kinase, the regulatory enzymes of the glycolytic sequence, showed progressive increases in their activities with the rise of parasitaemia in plasmodium knowlesi-infected rhesus monkey serum and red blood cells. chloroquine therapy cleared the parasitaemia in 72 h and brought the elevated levels of these enzymes back to almost normal in about 30 days. | 1992 | 1534081 |
| malaria: from quinine to the vaccine. | | 1992 | 1541651 |
| effect of cell age on erythrocyte choline transport: implications for the increased choline permeability of malaria-infected erythrocytes. | | 1992 | 1575704 |
| nadp-specific isocitrate dehydrogenase from the simian malaria parasite plasmodium knowlesi: partial purification and characterization. | cell-free schizonts of plasmodium knowlesi, a simian malaria parasite, possess significant isocitrate dehydrogenase (idh) activity, about 90% of which is contributed by the nadp-specific enzyme that is localized in the cytosolic fraction. the enzyme has been partially purified by affinity chromatography using blue sepharose cl-6b. although unstable in nature, it is stabilized by citrate and glycerol. kinetic studies with dl-isocitrate and nadp yielded hyperbolic curves with michaelis constants o ... | 1992 | 1578409 |
| susceptibility of macaca fascicularis monkeys from mauritius to different species of plasmodium. | macaca fascicularis monkeys from mauritius were shown to be susceptible via sporozoite inoculation to 7 species of plasmodium (p. fragile, p. coatneyi, p. gonderi, p. inui, p. cynomolgi, p. knowlesi, and p. fieldi), indigenous to macaques in southeastern asia. four monkeys were sequentially infected with different species of plasmodium to determine maximum and course of parasitemia. in 2 nonsplenectomized monkeys, p. fragile developed maximum parasite counts of only 134 and 155/microliters. for ... | 1992 | 1597796 |
| a reticulocyte-binding protein complex of plasmodium vivax merozoites. | plasmodium vivax merozoites primarily invade reticulocytes. the basis of this restricted host cell preference has been debated. here we introduce two novel p. vivax proteins that comigrate on reducing sds-polyacrylamide gels, colocalize at the apical pole of merozoites, and adhere specifically to reticulocytes. the genes encoding these proteins, p. vivax reticulocyte-binding proteins 1 and 2 (pvrbp-1 and pvrbp-2), have been cloned and analyzed. homologous genes are evident in the closely related ... | 1992 | 1617731 |
| polyvalent synthetic vaccines: relationship between t epitopes and immunogenicity. | three different synthetic polyvalent vaccines have been constructed by conjugating four synthetic peptides without any carrier protein. the peptides were copy fragments of two bacterial antigens (streptococcus pyogenes m protein and diphtheria toxin), two parasitic antigens (circumsporozoite protein of plasmodium falciparum and plasmodium knowlesi), and one viral antigen (hepatitis b surface antigen). outbred guinea-pigs immunized with polyvalent vaccine containing streptococcal, diphtheric, p. ... | 1990 | 1690488 |
| vaccination of rhesus monkeys against plasmodium knowlesi with aqueous suspension of mdp as an adjuvant. | in these investigations two types of antigen preparations were used: (i) whole antigen (wag), and (ii) soluble antigen (sag). for immunization, muramyl dipeptide (mdp) was employed as an adjuvant. highest reciprocal antibody titre values were recorded in elisa and iha tests from animals immunized by wag-mdp. skin reactions in animals sensitized with wag-mdp combination showed a well developed zone of erythema with induration after 24 hours of intradermal injection. animals immunized with wag-mdp ... | 1991 | 1810753 |
| the adhesion of malaria merozoite proteins to erythrocytes: a reflection of function? | | 1991 | 1817296 |
| selection of genetic variants from plasmodium clones. | clones of plasmodium alter their antigenic profile or invasion phenotype when presented with specific challenges. two examples are reviewed which may represent different genetic mechanisms of adaptation to selection pressures. in one series of experiments, rhesus monkeys were vaccinated with a 143,000/140,000 mr p. knowlesi merozoite surface protein and then infected with a parasite clone expressing this protein. primary parasitemia was controlled, but subsequent waves of parasitemia developed f ... | 1991 | 1820719 |
| evaluation of ayush-64 for blood schizontocidal activity against rodent and simian malaria parasites. | ayush-64, a new herbal antimalarial drug developed by the central council for ayurveda and siddha, was evaluated for direct parasiticidal action against p. berghei and p. yoelii nigeriensis in swiss mice and p. cynomolgi b and p. knowlesi in rhesus monkeys. no blood schizontocidal activity could be demonstrated against any of the four malaria parasites. | 1991 | 1824361 |
| oxidative metabolic response of peripheral blood monocytes of monkeys during primary and chronic plasmodium knowlesi infection. | the oxygen free radical generation (as determined by cytochrome c reduction) and respiratory burst enzyme activities were measured in the peripheral blood monocytes before infecting normal animals, during primary plasmodium knowlesi infection, after treatment of primary infection with chloroquine, after administration of various subcurative doses following reinfection and after establishment of chronicity. for all the parameters of the oxidative response, no significant difference was observed d ... | 1991 | 1847062 |
| cloning of the plasmodium vivax duffy receptor. | plasmodium vivax and plasmodium knowlesi merozoites invade only duffy blood group-positive human erythrocytes. soluble p. vivax and p. knowlesi merozoite proteins of 135 kda bind specifically to duffy blood group determinants. the gene encoding a member of the duffy receptor gene family of p. knowlesi has been cloned. we report here the molecular cloning of the presumptive duffy receptor gene of p. vivax, using the p. knowlesi gene as a probe. there is a single gene in p. vivax which codes for a ... | 1991 | 1849231 |
| pathogenesis of cerebral malaria. | plasmodium knowlesi infected rhesus monkeys were employed for investigating brain tissue damage in experimentally induced cerebral malaria. light microscopic studies revealed parasitic infiltration of virtually all the regions of cns. electron microscopic observations confirmed the light microscopic findings. these studies further revealed the presence of macrophages in the blood vessels of infected monkeys. in conclusion, the pathogenesis of cerebral malaria seems to be an outcome of a typical ... | 1991 | 1874541 |
| human cerebral malaria: characterization of malarial antibodies in cerebrospinal fluid. | anti-malarial antibodies were quantified in cerebrospinal fluid (csf) of 17 cases of cerebral malaria, 16 presumptive cases (no demonstrable parasitaemia in peripheral blood but responding to i.v. quinine therapy) of cerebral malaria, and 15 controls. a schizont-enriched plasmodium knowlesi antigen was used in an elisa. anti-malarial antibodies of iga and igm isotypes were not detectable in most of the csf samples analysed, although serum antibody titres were high. however, 88% of csf from cereb ... | 1991 | 1914232 |
| [preliminary studies on the diagnosis of plasmodium falciparum malaria by monoclonal antibody sandwich dot-immunogold silver staining assay]. | in this report, the blood samples from 30 falciparum malaria patients with parasitemia 0.015-0.58% and the blood samples from 30 healthy persons were examined by monoclonal antibody (mcab) sandwich dot-immunogold silver staining assay (dot-igssa). when the mcab 11g5, 13a2 and 13a1 were used for sandwich dot-igssa with mcab 14d9 labeled with colloidal gold respectively, the 0.0001% of parasitemia could be detected and the mcab 11g5, 13a1 and 14d9 labeled with colloidal gold could also be used to ... | 1991 | 1959167 |
| increased permeability to choline in simian erythrocytes after plasmodium knowlesi infection. | the permeability of simian erythrocytes to choline was found to be considerably increased after infection by the malaria parasite, plasmodium knowlesi. choline entry occurs by a facilitated-diffusion system involving a carrier, which displays temperature-dependence, saturability with choline (km = 8.5 +/- 0.7 microm) and specificity. this carrier can also be inhibited by a thiol reagent, n-ethylmaleimide, at an inactivation rate which is, in the absence of choline, the same as in normal erythroc ... | 1991 | 1996967 |
| blocking of the receptor-mediated invasion of erythrocytes by plasmodium knowlesi malaria with sulfated polysaccharides and glycosaminoglycans. | invasion of human erythrocytes by plasmodium knowlesi requires the duffy blood group antigen. p. knowlesi merozoites synthesize a 135-kda polypeptide which binds to the duffy antigen with receptor-like specificity. in this study, we show that the sulfated polysaccharide fucoidan and the glycosaminoglycan dextran sulfate inhibit the binding of the 135-kda polypeptide to human duffy-positive and rhesus erythrocytes while the chondroitin sulfates do not. fucoidan and dextran sulphate also blocked t ... | 1991 | 1999196 |
| intra-generic conservation and limited inter-strain variation in a protective minor surface antigen of plasmodium knowlesi merozoites. | | 1991 | 2011149 |
| hypersensitive mung bean nuclease cleavage sites in plasmodium knowlesi dna. | nucleotide sequences of plasmodium knowlesi dna that are cleaved by mung bean nuclease (mbn) at low enzyme concentration (0.2 units enzyme per micrograms dna) are listed. they are tandemly repeated purine/pyrimidine (rpy) stretches of dna with (apt) dimers predominating. most cut sites are within almost 100% rpy tracts. the enzyme cleaves at many points within the rpy stretch and usually hydrolyzes the 5'-apt-3' linkage. these alternating rpy target sites are flanked by homopurine and homopyrimi ... | 1990 | 2140809 |
| the duffy receptor family of plasmodium knowlesi is located within the micronemes of invasive malaria merozoites. | plasmodium vivax and plasmodium knowlesi merozoites invade human erythrocytes that express duffy blood group surface determinants. a soluble parasite protein of 135 kd binds specifically to a human duffy antigen. using antisera affinity purified on the 135 kd protein, we cloned a gene that encodes a member of a p. knowlesi family of erythrocyte binding proteins. the gene is a member of a family that includes three homologous genes located on separate chromosomes. two genes are expressed as major ... | 1990 | 2170017 |
| sixty-six kilodalton-related antigens of plasmodium knowlesi are merozoite surface antigens associated with the apical prominence. | we have previously reported that fab fragments of a monoclonal antibody to the 66 kd-related antigens of plasmodium knowlesi inhibit merozoite invasion of erythrocytes, strongly suggesting a role for these antigens as merozoite receptors for red cells. in this paper we have examined the distribution of these antigens on the surface of free merozoites. rapid immunofluorescence microscopy on free, unfixed cells demonstrated a preferential association of antigen with a polar region of merozoites. t ... | 1990 | 2181383 |
| a merozoite receptor protein from plasmodium knowlesi is highly conserved and distributed throughout plasmodium. | the 66-kda merozoite surface antigen (pk66) of plasmodium knowlesi, a simian malaria, possesses vaccine-related properties that are thought to originate from a receptor-like role in parasite invasion of erythrocytes. we report the complete sequence of pk66 which allowed the demonstration that highly conserved analogues exist throughout plasmodium including a recently reported gene from p. falciparum (peterson, m. g., marshall, v. m., smythe, j. a., crewther, p. e., lew, a., silva, a., anders, r. ... | 1990 | 2211675 |
| in vitro maturation of the exoerythrocytic stage of plasmodium knowlesi observed under phase contrast microscopy. | exoerythrocytic stages of plasmodium knowlesi were obtained in primary culture of rhesus monkey hepatocytes. the development of a single parasite was followed with phase contrast microscopy until release of merozoites in slightly less than 5 days. this direct observation may offer opportunities to determine visually factors that may influence specific steps of schizont development. | 1990 | 2254828 |
| pulmonary pathology in severe malaria infection in health and protein deprivation. | histopathological changes in the lung resulting from infection with a virulent strain of the malarial parasite, plasmodium knowlesi, in healthy and protein-deprived rhesus monkeys were studied. pertinent changes noted were a high degree of parasitized red cells in septal capillaries, microinfarcts, alveolar and interstitial oedema, interstitial pneumonitis, bronchopneumonia, and injury to septal capillary wall which may be secondary to the production of tumour necrosis factor. these changes were ... | 1990 | 2270000 |
| plasmodium yoelii nigeriensis circumsporozoite gene structure and its implications for the evolution of the repeat regions. | the circumsporozoite (cs) gene encodes the most immunogenic component of the plasmodial sporozoites. the immunodominant epitope-encoding domain of the cs gene shows sequences that are repeated in tandem. a detailed analysis of the cs repeats of certain closely related malaria parasites (strains of plasmodium cynomolgi, plasmodium knowlesi, and plasmodium vivax) showed that they evolve rapidly yet are well conserved within the gene. we were interested in studying whether the cs repeats of plasmod ... | 1990 | 2290446 |
| plasmodium knowlesi induces alterations in phosphatidylcholine and phosphatidylethanolamine molecular species composition of parasitized monkey erythrocytes. | using high performance liquid chromatography and gas-liquid chromatography, we have characterized the phosphatidylcholine and phosphatidylethanolamine molecular species composition of trophozoite and schizont forms of plasmodium knowlesi parasitized erythrocytes. similarly, we determined these parameters in the erythrocyte membranes of trophozoite parasitized cells, unparasitized erythrocytes from infected monkeys before and after a chloroquine treatment and erythrocytes from monkeys that had ne ... | 1990 | 2306451 |
| phospholipid asymmetry in the plasma membrane of malaria infected erythrocytes. | the transbilayer distribution of glycerophospholipids in the plasma membrane of plasmodium knowlesi infected erythrocytes was studied by using lysine-116-epsilon-n-palmitoyl amidinated pancreatic phospholipase a2. as a consequence of its superior membrane penetrating capacities, this modified enzyme rapidly degrades its substrates in the outer membrane leaflet of intact erythrocytes, a property that makes the enzyme an excellent tool to study the malaria parasitized red cell. the modified phosph ... | 1990 | 2344403 |
| circumsporozoite protein of plasmodium vivax: gene cloning and characterization of the immunodominant epitope. | the gene encoding the circumsporozoite (cs) protein of the human malaria parasite plasmodium vivax has been cloned. the deduced sequence of the protein consists of 373 amino acids with a central region of 19 tandem repeats of the nonapeptide asp-arg-ala-asp/ala-gly-gln-pro-ala-gly. a synthetic 18-amino acid peptide containing two tandem repeats binds to a monoclonal antibody directed to the cs protein of plasmodium vivax and inhibits the interaction of this antibody with the native protein in sp ... | 1985 | 2414847 |