Publications

isolation of a gene segment expressed by mature schizonts of plasmodium knowlesi.	fragments of plasmodium knowlesi dna, generated by mung bean nuclease digestion, were ligated into the lambda gt11 vector. this expression library was immunoscreened with a serum which inhibits invasion of erythrocytes by merozoites in vitro and whose primary specificity is directed against a mr 140 000 merozoite surface antigen. one of the isolated clones contained a 125 base pair insert which hybridized to a 1.8 kilobase species of schizont rna, indicating that this insert is part of a gene ex ...	1986	2423871
lamellar membranes associated with rhoptries in erythrocytic merozoites of plasmodium knowlesi: a clue to the mechanism of invasion.	in merozoites of plasmodium knowlesi, rhoptries have a dense substructure of fine (2.5 nm diameter) granules and short rods. these are not altered by lipid extraction, and stain with ethanolic phosphotungstate indicating a proteinaceous composition. various types of fixation also show multilamellar whorls with a periodicity of 5-7 nm in the tips of rhoptries or extruded at the merozoite apex. in merozoites fixed during invasions of red cells, membrane continuity typically occurs between the rim ...	1986	2423944
a new human duffy blood group specificity defined by a murine monoclonal antibody. immunogenetics and association with susceptibility to plasmodium vivax.	a new duffy specificity, fy6, defined by a murine monoclonal antibody of the igg1 kappa class, is related to susceptibility to malarial invasion. in humans, fy6 is present on the red cells of all persons except those of the fy(a-b-) type, a distribution resembling that of fy3. however proteolytic enzyme treatment of red cells enhances the reactivity of fy3, whereas fy6, like fya and fyb, is susceptible to degradation by this process. the number of fy6 sites on human red cells was found to be 12, ...	1987	2442291
enhanced epitopic response to a synthetic human malarial peptide by preimmunization with tetanus toxoid carrier.	successful human vaccination by synthetic malarial sporozoite peptides may depend on the choice of an appropriate carrier. tetanus toxoid (tt) has been proposed because of its safe and widespread use in humans. paradoxically, however, prior exposure to this toxoid vaccine could produce specific epitopic suppression against synthetic malarial peptides conjugated to this same protein as carrier. indeed, we have previously reported that such a phenomenon can occur in the case of a synthetic vaccine ...	1987	2444539
cloning and characterization of an abundant plasmodium knowlesi antigen which cross reacts with gambian sera.	a 110 kda plasmodium knowlesi antigen, termed pk110, has been identified on the basis of messenger rna abundance in late schizonts. most plasmodium genes previously cloned have been identified by immune sera, which have selected immunodominant antigens composed of repeating epitopes. although pk110 was not selected by immune sera, it also contains amino acid repeats, indicating that this structure may be a common feature of malarial proteins. determination of 296 codons in the pk110 gene reveale ...	1987	2444886
structural studies on a putative protective plasmodium knowlesi merozoite antigen.	two monoclonal antibodies, which prevent merozoites attaching to or invading erythrocytes, react with the same or closely apposed epitopes on a minor 66 kda plasmodium knowlesi antigen. the antigen is processed, at the time of schizont rupture and merozoite release, to 44 and 42 kda molecules which are present on the merozoite surface [deans, j. a. et al. (1984) mol. biochem. parasitol. 11, 189-204]. the monoclonal antibody-defined epitope, which is expressed only once on the 66 kda molecule, is ...	1987	2448619
isolation of three distinct parasite populations expressing different circumsporozoite proteins from the philippine strain of plasmodium knowlesi.	approximately 50% of the sporozoites of the philippine (p) strain of plasmodium knowlesi were found to react with monoclonal antibodies, produced against sporozoites of the h strain of p. knowlesi, by indirect immunofluorescence. two of these anti-h strain monoclonal antibodies were used with the p-strain sporozoites in a neutralization assay. they selectively abolished the infectivity of part of the sporozoite population, and the remainder was designated the p2 strain. monoclonal antibodies pro ...	1988	2449454
antibodies to lactate dehydrogenase of plasmodium knowlesi are specific to plasmodium species.	polyclonal immune monkey serum raised against schizonts of plasmodium knowlesi (h-strain) showed the presence of antibodies to lactate dehydrogenase (ldh) of p. knowlesi by immunodot enzyme staining method. the anti-ldh antibodies are most probably directed towards an epitope distinct from the catalytic site as shown by the specific enzyme staining of ldh after binding with antibody on nitrocellulose paper. these antibodies showed reactivity with ldh from different strains (h, p and w1 strains o ...	1988	2466780
improved isolation of plasmodium knowlesi-infected erythrocyte host-cell membrane on polycationic beads.		1989	2498870
phospholipid metabolism in plasmodium-infected erythrocytes: guidelines for further studies using radioactive precursor incorporation.	the biosynthesis of phospholipids is extensive in plasmodium knowlesi-infected simian erythrocytes due to the synthesis of membranes by this single-cell eukaryote in a host erythrocyte devoid of any pathway for lipid biosynthesis. in the present paper, we show that the incorporation of [3h]glycerol, which reflects de novo biosynthesis, is better studied at 300 microm-1 mm than at the trace doses, since this non-physiological precursor does not modify the amount of phosphatidylcholine biosynthesi ...	1989	2505213
resolution of enzyme bands of plasmodium knowlesi as a function of substrate concentration.	an extra band of isoenzyme lactate dehydrogenase (ldh) was obtained in case of plasmodium knowlesi free parasite as compared to normal monkey blood. this extra band could be resolved due to the decreasing amount of substrate concentration. agarose electrophoresis technique was used to separate the isoenzyme bands.	1989	2509545
brain histomorphology in protein deprived rhesus monkeys with fatal malarial infection.	healthy and protein deprived rhesus monkeys were inoculated with a virulent strain of plasmodium knowlesi, to determine the morphological changes in the brain and to establish whether this model could be utilised as an experimental model for cerebral malaria. the histomorphological changes produced in the brain did not correspond with the changes conforming to those of cerebral malaria. the changes observed in healthy controls were cerebral oedema, high percentage of parasitised rbcs in the cere ...	1989	2516010
regulation of phosphatidylcholine biosynthesis in plasmodium-infected erythrocytes.	plasmodium knowlesi-infected erythrocytes efficiently incorporated choline and metabolize it into phosphatidylcholine via the de novo kennedy pathway. no formation of either betaine or acetylcholine was detected. at physiological concentrations of external choline, isotopic equilibrium between intracellular choline and phosphocholine was reached in less than 1 h, whereas labeled phosphatidylcholine accumulated constantly, until at least 210 min. during this time, intracellular cdp-choline remain ...	1989	2536284
changes in the superoxide anion generating capacity and respiratory burst enzymes of peripheral blood monocytes of monkeys during acute plasmodium knowlesi infection.	the superoxide anion generation profile of peripheral blood monocytes of rhesus monkeys was investigated during the different stages of an acute plasmodium knowlesi infection. an initial increase in superoxide anion was followed by a significant decline (p less than 0.001), paralleled by a drop in nadph oxidase activity; there was no alteration in the activity of the hexose monophosphate shunt enzymes. this lowered activity of the nadph oxidase, with the resulting decreased o2 generation, might ...	1989	2555762
immune-complexes-mediated evasion of plasmodium knowlesi from destruction by macrophages.	the role of immune-complexes in the evasion of plasmodium knowlesi from destruction by macrophages was studied in vitro. incubation of macrophages with immune-complexes, prepared either by mixing total parasite antigens soluble in culture medium with normal or immune monkey serum, or by polyethylene glycol precipitation of serum from monkeys acutely infected with p. knowlesi, significantly reduced both the pool size of the macrophages that bound parasitized erythrocytes, and the number of parasi ...	1989	2571251
conserved group-specific epitopes of the circumsporozoite proteins revealed by antibodies to synthetic peptides.	the immunogenic properties of sporozoites are associated mainly with the circumsporozoite (cs) protein that covers the surface of mature sporozoites. this stage-specific protein has an immunodominant region with repetitive epitopes. rabbits that are repeatedly immunized with sporozoites of plasmodium knowlesi, a monkey malaria parasite, also recognize two synthetic peptides (n2 and c2) representing other polar domains of the cs protein. we show in this report that antibodies to the n2 and c2 syn ...	1985	2580025
multiple non-repeated epitopes on the circumsporozoite protein of plasmodium knowlesi.	the plasmodium knowlesi circumsporozoite (cs) protein contains a repetitive immunodominant epitope. here we show that the serum of rabbits repeatedly immunized with p. knowlesi sporozoites contains antibodies which bind to immobilized synthetic peptides ('c2', 'n2', and 'charged') representing two different polar regions of the cs polypeptide. these reactions are specific since the binding is inhibited only by the homologous peptides. antisporozoite antibodies were isolated from the rabbit serum ...	1985	2581134
enhancement of in vitro infectivity of simian malaria sporozoites to hepatocytes by centrifugation.	sporozoites of plasmodium cynomolgi, plasmodium knowlesi, and plasmodium coatneyi were deposited onto monolayers of hepatocytes from rhesus monkeys (macaca mulatta). when sporozoites were centrifuged (1,600 g for 5 min), 4-13-fold more schizonts were observed than were found in noncentrifuged control cultures. centrifugation of hepatocyte monolayers before adding sporozoites did not modify the number of parasites.	1989	2614610
blood schizontocidal activity of a new antimalarial drug, arteether (alpha/beta), against plasmodium knowlesi in rhesus monkeys.		1989	2617597
purification and characterization of an erythrocyte membrane protein complex carrying duffy blood group antigenicity. possible receptor for plasmodium vivax and plasmodium knowlesi malaria parasite.	a murine monoclonal antibody, named anti-fy6, which agglutinates all human red cells except those of fy(a-b) phenotype was used for purification and characterization of duffy antigens. duffy antigens are multimeric red cell membrane proteins composed of different subunits of which only one, designated pd protein, reacts in immunoblots with the murine monoclonal antibody anti-fy6. affinity-purified detergent-soluble antigen-antibody complex obtained from red cells, surface-labeled with 125i yield ...	1989	2668273
inhibition of malarial parasite invasion by monoclonal antibodies against glycophorin a correlates with reduction in red cell membrane deformability.	the effect of well-characterized monoclonal antibodies to red cell surface molecules on the invasion of human red cells by the malarial parasites plasmodium falciparum and plasmodium knowlesi was examined. antibodies to glycophorin a (gp alpha) inhibit invasion for both parasite species, and this is highly correlated with the degree to which they decrease red cell membrane deformability as measured by ektacytometry. this effect on rigidity and invasion was also seen with monovalent fab fragments ...	1989	2676019
the fine structure of secretion by plasmodium knowlesi merozoites during red cell invasion.	the secretory organelles of plasmodium knowlesi were studied ultrastructurally to examine their mode of action during invasion. the formation of lamellar structures in merozoite rhoptries within late stage schizonts is prevented by the protease inhibitors chymostatin and leupeptin. under normal conditions vesicles lined by 6-nm membranes are formed in rhoptries during erythrocyte invasion. stereoscopic viewing of tilted sections shows that where the merozoite apex contacts the parasitophorous va ...	1989	2769602
release of merozoite dense granules during erythrocyte invasion by plasmodium knowlesi.	we used immunoelectron microscopy to study the fate of dense granules during the invasion of erythrocytes by plasmodium knowlesi merozoites. when merozoites entered host cells, dense granules moved to the pellicle, released their contents into the parasitophorous vacuole space, and then moved into fingerlike channels of the vacuole membrane. this is the first report showing that the content of dense granules of p. knowlesi is different from the contents of rhoptries and micronemes and is associa ...	1989	2777381
enhanced transbilayer mobility of phospholipids in malaria-infected monkey erythrocytes: a spin-label study.	using a recently described technique of electron spin resonance spectroscopy, we determined the rate of transbilayer mobility (flip) of the four major simian-erythrocyte phospholipids in the erythrocyte membrane after infection by plasmodium knowlesi. the development of the malarial parasite induces a very large increase in the flip rate of these phospholipids (mainly during the ring stage and at the beginning of trophozoite maturation). the half flip time fell from 2 and 3 hr in the case of cho ...	1988	2835380
receptor-like specificity of a plasmodium knowlesi malarial protein that binds to duffy antigen ligands on erythrocytes.	a 135-kd parasite protein, a minor component of the plasmodium knowlesi malaria radiolabeled proteins released into culture supernatant at the time of merozoite release and reinvasion, specifically bound to human erythrocytes that are invaded and carry a duffy blood group determinant (fya or fyb), but did not bind to human erythrocytes that are not invaded and do not carry a duffy determinant (fyfy). specific anti-duffy antibodies blocked the binding of the 135-kd protein to erythrocytes carryin ...	1988	2838562
in vitro activity of antimalarial compounds on the exoerythrocytic stages of plasmodium cynomolgi and p. knowlesi.	primary cultures of macaca mulatta hepatocytes infected with sporozoites of plasmodium knowlesi, p. cynomolgi (cambodian strain), and p. cynomolgi bastianellii were exposed in vitro to 7 antimalarial compounds. the number of exoerythrocytic schizonts present after 4-7 days of culture was used to assess the activity. with pyrimethamine, proguanil, cycloguanil, primaquine, and 2 of its analogues (wr242511 and wr238605), marked inhibition of schizont formation could be achieved at concentrations be ...	1989	2929849
nuclear and mitochondrial dna of the primate malarial parasite plasmodium knowlesi.	restriction analyses and dna/dna hybridisation of parasite dna isolated from monkeys infected with the malarial parasite plasmodium knowlesi has permitted unambiguous identification of the nuclear dna of this species. its (g+c) content, as determined by estimations of buoyant density as well as by direct analysis, is about 38%, essentially indistinguishable from that of its primate laboratory host, and grossly different from that of the major human malaria parasite, p. falciparum, which has a (g ...	1985	2985981
choline kinase activity in plasmodium-infected erythrocytes: characterization and utilization as a parasite-specific marker in malarial fractionation studies.	choline kinase (ec 2.7.1.32) was investigated in plasmodium falciparum-infected erythrocytes. disrupted infected erythrocytes had a choline kinase activity of 1.9 +/- 0.2 nmol phosphorylcholine/10(7) infected cells per h, whereas the activity in normal uninfected erythrocytes was less than 6 pmol/10(7) cells per h. a broad alkaline optimal ph (7.9-9.2) was observed. the km values for choline and atp were 79 +/- 20 microm, and 1.3 +/- 0.3 mm, respectively. atp concentrations higher than 12 mm inh ...	1986	3000453
synthetic peptides from the circumsporozoite proteins of plasmodium falciparum and plasmodium knowlesi recognize the human hepatoma cell line hepg2-a16 in vitro.	several lines of evidence have emphasized the importance of the malaria circumsporozoite (cs) protein as a factor in sporozoite invasion of the hepatocyte; however, the specific mechanism of cell recognition and invasion has not been explained. in this study we present evidence that a highly conserved region of the cs protein immediately adjacent to the repeat region, the n1 region, specifically recognizes receptors on the human hepatoma cell line hepg2-a16 under conditions where invasion by spo ...	1986	3023519
reevaluation, using marker enzymes, of the ability of saponin and ammonium chloride to free plasmodium from infected erythrocytes.	saponin and ammonium chloride lysis have been applied for some time to the separation of erythrocyte membranes from malarial-infected erythrocytes, allowing easy isolation of the parasites. we present a reevaluation of the use of saponin and ammonium chloride as tools for isolating plasmodium (knowlesi or falciparum) parasites. acetylcholine esterase (ec 3.1.1.7) was used as an erythrocyte membrane marker and cdp-choline: 1,2-diacylglycerol cholinephosphotransferase (ec 2.7.8.2) as a parasite me ...	1987	3040955
immunogenicity of the repetitive and nonrepetitive peptide regions of the divergent cs protein of plasmodium knowlesi.	the circumsporozoite (cs) protein of the nuri strain of the simian malarial parasite plasmodium knowlesi was expressed as a fusion protein in e. coli. this fusion protein cross-reacted with the polyclonal monkey sera raised against irradiated sporozoites of another strain (h strain) of p. knowlesi. the antibody against the repeat units of the h strain cs protein was affinity purified from the polyclonal sera by using synthetic repeat peptides. the affinity-purified antibody did not cross-react w ...	1986	3086454
antibodies to the glutamate dehydrogenase of plasmodium falciparum.	polyclonal antisera raised against plasmodium knowlesi reacted with nadp-specific glutamate dehydrogenase (gldh) of p. knowlesi, gldh of p. falciparum and gldh of proteus spp. the antisera did not react with nad(p) gldh from bovine liver. polyclonal antisera raised against the gldh of proteus spp. cross-reacted with gldh from p. falciparum. monoclonal antibodies (mcabs) obtained from mice immunized with proteus gldh were either specific for the bacterial enzyme or cross-reacted with p. falciparu ...	1986	3086819
inhibition of plasmodium knowlesi isoenzyme bands using antibody produced by lymphocyte hybridoma technique.		1986	3106465
vaccination trials in rhesus monkeys with a minor, invariant, plasmodium knowlesi 66 kd merozoite antigen.	a minor plasmodium knowlesi 66 kd antigen, which plays an essential role in merozoite invasion, has been shown to be stable in distinct variants and strains of the parasite, and in the face of a specific immune response from the host. parasites were unable to produce novel molecule(s) to replace it functionally, even in the presence of specific immune pressure. rhesus monkeys immunized with the purified 66 kd antigen, with saponin as adjuvant, produced antibody which inhibited merozoite invasion ...	1988	3194149
molecular basis for mutation in a surface protein expressed by malaria parasites.	plasmodium knowlesi parasites isolated from a rhesus monkey vaccinated with a 143,000/140,000 mr merozoite surface protein no longer expressed this protein. to study the molecular basis for the mutations, a lambda gt11 cdna expression library constructed from the original parasite clone was screened with rabbit antiserum specific for the 143,000/140,000 mr protein. two cdna clones that mapped to the 5' and 3' ends of the gene hybridized to two chromosomes of 3.6 x 10(6) kilobases and 1.8 x 10(6) ...	1988	3210230
identification of plasmodium knowlesi erythrocyte binding proteins.	plasmodium knowlesi, a malaria of old world monkeys, invades all duffy blood group positive human erythrocytes and various new world monkey erythrocytes except cebus apella. we had previously identified a 135 kda parasite protein in supernatants of p. knowlesi cultures that bound to duffy positive but not to duffy negative human erythrocytes [haynes et al., j. exp. med. 167, 1873-1881 (1988)]. we now use new world monkey erythrocytes as a reagent to identify p. knowlesi proteins in culture super ...	1988	3221909
stabilization of plasmodium knowlesi antigen for seroepidemiology of malaria.		1988	3243363
fractionation of plasmodium knowlesi antigen for seroepidemiology of human malaria by iha test.		1988	3243364
acyl-coa synthetase activity in plasmodium knowlesi-infected erythrocytes displays peculiar substrate specificities.	in its blood stages the malaria parasite, plasmodium, displays very high lipid metabolism. we present evidence for an abundant long-chain acyl-coa synthetase (ec 6.2.1.3) activity in plasmodium knowlesi-infected simian erythrocytes. the activity was found to be 20-fold higher in the schizont-infected (the last parasite stage) than in control erythrocytes. the cosubstrate requirements of the enzyme were similar to those previously reported for acyl-coa synthetases from other sources. among the se ...	1988	3334857
phospholipid uptake by plasmodium knowlesi infected erythrocytes.	the uptake of phosphatidylcholine (pc), phosphatidylethanolamine (pe) and phosphatidylserine (ps) in plasmodium knowlesi infected erythrocytes has been studied. whereas uptake of phospholipids, in the absence of phospholipid transfer proteins, is negligible in control cells, the infected cells can incorporate considerable amounts of added phospholipids. the uptake is enhanced by the presence of lipid transfer proteins. doubly labeled [3h]oleate, [14c]choline) pc does not undergo any appreciable ...	1988	3378625
differential effects of chloroquine on the phospholipid metabolism of plasmodium-infected erythrocytes.	the effect of the antimalarial drug chloroquine (cq) on the phospholipid metabolism in plasmodium knowlesi-infected simian erythrocytes has been studied by incubating cells with different labeled precursors and various concentrations of cq. the drug induced considerable modifications of this metabolism but at the same time decreased nucleic acid and protein synthesis as well as the output of 14co2 from radioactive glucose. phosphatidylcholine biosynthesis was severely reduced. however, under the ...	1988	3401244
cell-mediated immune responses in drug-suppressed simian plasmodium knowlesi infection.		1986	3494639
production of low titre and non-precipitating antibodies against plasmodium knowlesi isoenzyme bands.		1987	3507445
[quantitative changes of plasma fibronectin in plasmodium knowlesi malaria].	in order to study the variation of plasma fibronectin (fn) during malaria infection, two male monkeys (macaca fascicularis) were splenectomized and infected with plasmodium knowlesi. as parasitaemia increased fn concentration decreased gradually from 260 to 140 microgram/ml and 300 to 85 micrograms/ml for monkeys 1 and 2 respectively. the significance of this finding is discussed.	1986	3517789
expression of the plasmodium knowlesi circumsporozoite antigen in escherichia coli directed by plasmodium bacterial-like promoter sequences.	the plasmodium knowlesi circumsporozoite (cs) gene is expressed in escherichia coli directly from a parasite genomic dna fragment, using promoter and ribosome-binding site (rbs) sequences present in this fragment. transcription of the cs gene in e. coli is directed by tandem plasmodium bacterial-like promoter elements located within the 0.5-kb ecori-hindiii fragment roughly 2.5 kb 5' from the cs gene within the 11-kb ecori parasite genomic dna fragment. no readthrough from vector promoters or fo ...	1986	3519364
immunoprecipitation of malarial acid endopeptidase.	electrophoresis of extracts of schizonts of plasmodium knowlesi in non-dissociating polyacrylamide gels, separates several bands of acid endopeptidase activity. a polyclonal antiserum, produced by immunization with purified merozoites, failed to distinguish between different bands of the parasite enzyme, indicating that they are serologically related. apart from the loss of one minor peak, extraction in triton x-100 did not reduce the enzyme's electrophoretic heterogeneity. the antiserum did not ...	1986	3520446
role of muramyl peptides for the enhancement of synthetic vaccines.	adjuvants are largely used in human and veterinary medicine with conventional vaccines. vaccines of the future could be synthetic immunogens which would require the addition of more immunomodulators. muramyl peptides (mdp) are synthetic glycopeptides which can substitute mycobacteria in fca and are also adjuvant-active in saline. a derivative, murabutide, is currently undergoing clinical trials and has been found efficient in several experimental models of conventional and synthetic vaccines. fo ...	1986	3527818
comparative evaluation of plasmodium knowlesi and p. cynomolgi antigens for the detection of human malaria antibody by immunofluoresence test.		1986	3528277
vaccination-induced variation in the 140 kd merozoite surface antigen of plasmodium knowlesi malaria.	immunity to 143/140 kd schizont antigens of a monkey malaria, plasmodium knowlesi, provides partial protection to lethal malaria infection in rhesus monkeys challenged with uncloned parasites. to determine the capacity of a cloned parasite to generate variants of the 143/140 kd antigens, immunized monkeys were challenged with a clone of p. knowlesi. parasites recovered 8 d after inoculation with a cloned parasite retained the 143/140 kd antigens. parasites recovered 30 d after challenge had unde ...	1987	3546574
induction of biologically active antibodies by a polyvalent synthetic vaccine constructed without carrier.	four synthetic peptides that copy fragments of two bacterial antigens (streptococcus pyogenes m protein and diphtheria toxin), one viral antigen (hepatitis b surface antigen), and one parasitic antigen (circumsporozoite protein of plasmodium knowlesi) were covalently bound within the same construct. this totally synthetic polyvalent administered to mice with freund complete adjuvant or in saline with murabutide (an adjuvant-active muramyl peptide) elicited high levels of antibodies which, in cer ...	1987	3553005
phospholipid organization in monkey erythrocytes upon plasmodium knowlesi infection.	the phospholipid organization in monkey erythrocytes upon plasmodium knowlesi infection has been studied. parasitized and nonparasitized erythrocytes from malaria-infected blood were separated and pure erythrocyte membranes from parasitized cells were isolated using affi-gel beads. in this way, the phospholipid content and composition of the membrane of nonparasitized cells, the erythrocyte membrane of parasitized cells and the parasite could be determined. the phospholipid content and compositi ...	1987	3593720
organization and expression of the plasmodium knowlesi circumsporozoite antigen gene.	to investigate the mechanisms regulating the stage specific expression of the plasmodium knowlesi circumsporozoite (cs) antigen gene, the sporozoite genomic dna copy of the cs gene has been isolated and compared with the blood stage genomic dna and the sporozoite cdna copies. the genomic dna sequences of the two developmental stages are identical across 4 kilobase pairs of the chromosome containing the entire cs gene transcriptional unit. from restriction enzyme mapping no dna rearrangements ove ...	1987	3600698
phagocytic function of monocytes of rhesus monkeys during plasmodium knowlesi infection and the effect of treatment with chloroquine.	the effect of chloroquine on the phagocytic function of monocytes was studied in normal and plasmodium knowlesi-infected rhesus monkeys during a course of therapy. in normal animals, chloroquine inhibited phagocytic activity after three doses. the effect of the drug and concentration was greatest after six to eight days. recovery in function of monocytes was noticed after the drug had been excreted. in p. knowlesi-infected monkeys, the degree of inhibition of phagocytosis depends on the level of ...	1986	3603637
effect of chloroquine on cellular immune responses of normal and p. knowlesi-infected rhesus monkeys.	the immunopharmacokinetics of chloroquine were studied in plasmodium knowlesi-infected and uninfected rhesus monkeys. in control monkeys, chloroquine depressed the percentage of lymphocyte subpopulation and their proliferative response after the third dose of drug administration. the effect was maximum during day 6 to 10 after initiation of treatment. during this period the plasma level of chloroquine was high. the drug was slowly excreted and recovery in immune functions was noticed by the 20th ...	1987	3623607
renal clearance, tubular reabsorption and urinary excretion of albumin in monkeys infected with plasmodium knowlesi.	the glomerular filtration rate (gfr) and the glomerular clearance rate of albumin were determined in 6 rhesus monkeys infected with p. knowlesi as well as in 6 control monkeys by using 51cr-edta and 125i-hsa respectively. the excreted albumin in the urine was also determined and used for calculating the renal clearance value. the amount and rate of albumin filtered in the glomeruli and reabsorbed by the tubules were then calculated from these parameters. the present study showed that the rate an ...	1987	3660069
renal plasma flow in rhesus monkeys infected with plasmodium knowlesi.	renal plasma flow was studied in six rhesus monkeys before and during infection with plasmodium knowlesi using 125i-sodium orthoiodohippurate (125i-oih) as a tracer. the mean renal plasma flow and the rate constant from the intravascular compartment to the kidneys were significantly reduced in the infected monkeys. as both intravascular and extravascular compartments were slightly but not significantly elevated, which resulted in the prolonged mean transit time of 125i-oih in monkeys infected wi ...	1987	3672179
an intracellular simian malarial parasite (plasmodium knowlesi) induces stage-dependent alterations in membrane phospholipid organization of its host erythrocyte.	the membrane phospholipid organization in monkey erythrocytes harbouring different developmental stages of the simian malarial parasite plasmodium knowlesi was studied using phospholipase a2 from two different sources and merocyanine 540 as the external-membrane probes. experiments were done to confirm that the phospholipases did not penetrate into the infected cells or hydrolyse phospholipids during membrane isolation. the parasite-free erythrocyte membrane was isolated by differential centrifu ...	1987	3675550
modification of the fatty acid composition of individual phospholipids and neutral lipids after infection of the simian erythrocyte by plasmodium knowlesi.	using capillary gas-liquid chromatography, we have analyzed the alteration in the total fatty acid, phospholipid and neutral lipid compositions of the monkey erythrocyte, after infection by the malarial parasite plasmodium knowlesi. data based on fatty acid quantitation show that the phospholipid composition is altered, with particularly large increases in phosphatidylcholine (pc) and phosphatidylethanolamine (pe), the most abundant phospholipids in normal and p. knowlesi-schizont-infected cells ...	1986	3719005
protection of rhesus monkeys against plasmodium knowlesi infection with merozoite vaccine.		1986	3733202
lipidic vacuoles in plasmodium knowlesi erythrocytic schizonts.	electron microscopy of schizont development in erythrocytic plasmodium knowlesi has revealed that spheroidal vacuoles 250 nm in diameter with semi-dense contents appear at the periphery of the parasite prior to the budding of merozoites. when treated with non-polar solvents, their contents are completely extracted, and after fixation in tannic-glutaraldehyde they contain regular lamellae with a periodicity of 5.5 nm. both of these reactions are typical of lipids. some of these structures are ass ...	1986	3735154
membrane orientation and antigenic peptides of an immunoprotective 74 kda plasmodium knowlesi glycoprotein.	vaccination trials have shown that a purified, 74 kda glycoprotein, gp74, isolated from the host cell membrane of plasmodium knowlesi-infected rhesus erythrocytes, can provide protective immunity against p. knowlesi malaria. we have extended this work by a tryptic peptide analysis of the disposition of gp74 in the host cell membrane. of the 18 peptides characterized by high-performance liquid chromatography only four were accessible to lactoperoxidase-catalyzed radioiodination of non-leaky, schi ...	1986	3736596
sialoglycoproteins and sialic acids of plasmodium knowlesi schizont-infected erythrocytes and normal rhesus monkey erythrocytes.	the effects of malaria infection on rbc sialic acids and sialoglycoproteins were studied with asexual blood-stage infections of plasmodium knowlesi in rhesus monkeys. glycoprotein radio-isotope labelling methods were used to compare the sialoglycoproteins of normal rbc and p. knowlesi schizont-infected rbc (si-rbc). tritiation of glycoproteins from si-rbc with the standard sialidase + galactose oxidase/nab3h4 method or standard periodate/nab3h4 method was significantly decreased when compared to ...	1986	3737241
structure and development of the surface coat of erythrocytic merozoites of plasmodium knowlesi.	the surface of extracellular merozoites of p. knowlesi is covered with a coat 15-20 nm thick, made up of clusters of filaments standing erect on the plasma membrane. filaments have stems 2 nm thick, the peripheral ends of which are complex, branching or ending in long trailing threads. coat filaments occur on the surface of the parasite in regular rows at an early schizont stage, and persist until well after merozoite release. they are sensitive to trypsin and papain, and bind ethanolic phosphot ...	1986	3742563
localization of protective 143/140 kda antigens of plasmodium knowlesi by the use of antibodies and ultracryomicrotomy.	immune sera from mice immunized with the 143/140 kda protein have been shown to partially block erythrocyte invasion by p. knowlesi merozoites. therefore, immunoelectron microscopy utilizing ultracryomicrotomy, antibody to 143/140 kda protein, and protein a gold particles were used to determine the precise localization of this protein in malarial parasites. gold particles were not seen associated with young trophozoites but appeared in the parasite cytoplasm as the parasites grew to multi-nuclea ...	1986	3758082
progressive changes in the liver function of monkeys following plasmodium knowlesi infection.		1986	3758439
possible basis for membrane changes in nonparasitized erythrocytes of malaria-infected animals.	previous studies (gupta et al. (1982) nature 299, 259-261) have shown that nonparasitized erythrocytes of plasmodium knowlesi-infected monkeys contain the procoagulant phospholipid phosphatidylserine (ps) in the outer-half of their membrane bilayer. a reinvestigation of this problem has now revealed that in acute p. knowlesi infection, at least 30% of the infected animals do not have this abnormality. however, ps externalization was a consistent feature in the uninfected red cells of chronically ...	1986	3768365
studies on the transcapillary escape rate of albumin and capillary permeability in rhesus monkeys infected with plasmodium knowlesi.	the transcapillary escape rate and plasma clearance rate of albumin were studied in five rhesus monkeys infected with plasmodium knowlesi in comparison with six control monkeys by using 125i-hsa as a tracer. the plasma disappearance curve of the radioactivity was followed during the first 60 minutes after injection of this labelled protein. plasma volume was found to be significantly higher while plasma albumin concentration was significantly lower, which resulted in the non-significantly increa ...	1986	3789843
characterization of lactate dehydrogenase of plasmodium knowlesi.	some properties of purified lactate dehydrogenase, (ec. 1.1.1.27) from schizonts of plasmodium knowlesi are described. the plasmodial enzyme migrated as single entity on polyacrylamide gel, and resembled rabbit muscle (m4) lactate dehydrogenase in its electrophoretic mobility. the p. knowlesi enzyme consisted of four identical subunits of 31 kda. purified lactate dehydrogenase was inhibited almost completely when incubated with 100 microm p-chloromercuribenzoate, ag+ or hg+ and such inhibition c ...	1986	3807941
levels of fdp-aldolase enzyme activity in plasmodium knowlesi parasitized monkey erythrocytes.		1986	3817889
expression of the major surface antigen of plasmodium knowlesi sporozoites in yeast.	the circumsporozite protein, a surface antigen of the sporozoite stage of the monkey malarial parasite plasmodium knowlesi, was expressed in the yeast saccharomyces cerevisiae by using an expression vector containing the 5' regulatory region of the yeast alcohol dehydrogenase i gene. it was necessary to eliminate the entire 5' upstream region of the parasite dna to obtain the expression of this protein. only the circumsporozoite precursor was produced by the yeast transformants, as detected by i ...	1985	3890178
immunochemical analysis of surface membrane antigens on erythrocytes infected with non-cloned sica[+] or cloned sica[-] plasmodium knowlesi.	the sica[-] or non-agglutinable phenotype of plasmodium knowlesi schizont-infected erythrocytes has been defined serologically but not biochemically. similarly, non-cloned sica[+] or agglutinable parasites have been shown serologically to express sica or variant antigen(s) but the number and nature of such antigens have not been defined. here we describe the immunochemical analysis of surface antigen expression on [125i]lactoperoxidase-labelled erythrocytes infected either with a sica[-] clone o ...	1985	3906520
guanosine triphosphate cyclohydrolase in plasmodium falciparum and other plasmodium species.	gtp cyclohydrolase (ec 3.5.4.16), the first enzyme in the pteridine pathway leading to the de novo formation of folic acid, has been identified and isolated from the human malaria parasite, plasmodium falciparum. the enzyme was purified 200-fold by high performance size-exclusion chromatography on a tsk-g-3000 sw protein column. the molecular weight was estimated at 300 000. optimal enzyme activity was observed at ph 8.0 and 42 degrees c. the km for gtp was 54.6 microm. products of the enzyme re ...	1985	3908934
purification and properties of lactate dehydrogenase from plasmodium knowlesi and erythrocytes of the rhesus monkey.	lactate dehydrogenase, e.c.1.1.1.27 (ldh) from the simian malarial parasite, plasmodium knowlesi, and from normal rhesus monkey erythrocytes has been purified using blue sepharose affinity chromatography, and the properties of the purified enzyme from these two sources have been compared. the enzyme from the host and parasite were different in their kinetic properties, viz., substrate and ph optima, thermostability and isoenzymic behaviour. partially purified ldh of the erythrocytes resolved int ...	1986	3964137
immunization of monkeys with a 140 kilodalton merozoite surface protein of plasmodium knowlesi malaria: appearance of alternate forms of this protein.	the merozoite is the invasive stage of the malaria parasite which is released by rupture of the schizont-infected erythrocyte. a monoclonal antibody against a 140 kilodalton (kda) merozoite surface antigen of plasmodium knowlesi was used to characterize and to purify this antigen. it was shown by pulse-chase metabolic labeling of mature schizonts that the 140 kda merozoite antigen was the processed product of a 143 kda schizont component, and that processing occurred at the time of erythrocyte r ...	1985	3989306
carbohydrate metabolism of malarial parasites--i. metabolism of lactate in plasmodium knowlesi infected monkey erythrocytes.	lactate metabolism by plasmodium knowlesi infected erythrocytes was examined after careful removal of leucocytes from cell preparations. infected cells were able to metabolize glucose, pyruvate and lactate. respiration of infected erythrocytes was maximally stimulated by lactate and to a lesser degree by pyruvate and glucose. respiration of infected cells was insensitive to stimulation by succinate or glutamate or inhibition by malonate. mepacrine was found to be a potent respiratory inhibitor. ...	1985	3995917
biologically active antibodies elicited by a synthetic circumsporozoite peptide of plasmodium knowlesi administered in saline with a muramyl dipeptide derivative.	a synthetic peptide whose sequence was derived from the circumsporozoite protein of plasmodium knowlesi coupled to bovine gamma globulin has been shown to be immunogenic when administered with freund complete adjuvant. the present experiments were designed to test the immunogenicity of the peptide when attached to a tetanus toxoid carrier and administered with alum or murabutide, both acceptable clinical adjuvants. in both cases, the use of an adjuvant increased the levels of circulating anti-pe ...	1985	3997250
diversity of circumsporozoite antigen genes from two strains of the malarial parasite plasmodium knowlesi.	the complete nucleotide sequence of the coding region of the circumsporozoite antigen gene (cs gene) of the nuri strain of the malarial parasite plasmodium knowlesi is presented. the gene from the nuri strain exhibits a novel form of sequence diversity when compared to the cs gene from the h strain. instead of the 12 tandem repeating 36-base pair units of the h strain, the nuri strain contains 16 tandem repeating 27-base pair units of a different nucleotide sequence that encodes a different repe ...	1985	4023712
inability of plasmodium knowlesi sporozoites to invade anopheles freeborni salivary glands.	oocysts of plasmodium knowlesi developed normally on the gut of the mosquito anopheles freeborni, rupturing and releasing sporozoites at 10-14 days post-infection. subsequently, however, sporozoites were never found in this mosquito's salivary glands. heterologous transplants of whole salivary glands from uninfected an. freeborni and an. dirus, a completely susceptible mosquito, into the abdomens of insects heavily infected with mature oocysts were done. sporozoites failed to infect an. freeborn ...	1985	4025683
production of anti-sporozoite antibodies in absence of response to carrier by coupling an mdp derivative to a malaria peptide-tetanus toxoid conjugate.	a synthetic peptide (pep) representing a portion of the plasmodium knowlesi circumsporozoite protein attached to a tetanus toxoid (tt) carrier, has been shown to be immunogenic when delivered in saline with derivatives of the synthetic adjuvant, muramyl dipeptide (mdp). the present study was designed to determine if the degree of substitution of pep and of mdp derivatives on the tetanus toxoid (tt) carrier, as well as the choice of mdp derivative used play a role in determining anti-pep and anti ...	1985	4038309
extracellular development of plasmodium knowlesi erythrocytic stages in an artificial intracellular medium.	the development of erythrocytic stages of plasmodium knowlesi separated from their host cells has been determined in terms of the capacity of the isolated organisms to carry out the synthesis and secretion of proteins. p. knowlesi trophozoites and schizonts were released from host cells by nitrogen decompression and cultivated in a medium consisting of 20 mm na+; 120 mm k+; 1 mm mg2+; no ca2+; 100 mm cl-; 20 mm hco3-; 5 mm hepes [ph 6.73], glucose, vitamins, amino acids and 10% fetal calf serum. ...	1985	4069157
alterations in capillary permeability in rhesus monkeys with plasmodium knowlesi infection.	the transcapillary escape rate and capillary permeability to albumin were studied in 3 rhesus monkeys throughout the whole course of p. knowlesi infection. the transcapillary escape rates started to increase on the first week after infection and were significantly higher than the control values during infection. plasma volume was found to be increased while plasma albumin concentration decreased which resulted in the increased intravascular mass, outflux and clearance of albumin from the intrava ...	1985	4071202
periodicity of nuclear dna synthesis in the intraerythrocytic cycle of plasmodium knowlesi.		1972	4113359
immunization against plasmodium knowlesi malaria.		1972	4116050
heparin therapy in simian plasmodium knowlesi malaria.		1972	4116148
studies on antibody levels during vaccination of rhesus monkeys against plasmodium knowlesi.		1965	4158313
immunization of rhesus monkeys against plasmodium knowlesi malaria.		1965	4158356
coagulation and fibrinolysis in simian plasmodium knowlesi malaria.		1973	4198003
isolation of blood-stage merozoites from plasmodium knowlesi malaria.		1973	4200011
fibrinogen catabolism in plasmodium knowlesi malaria.		1973	4201356
dna and rna syntheses by intraerythrocytic stages of plasmodium knowlesi.		1973	4202833
vaccination of rhesus monkeys (macaca mulatta) against plasmodium knowlesi by the use of nonviable antigen.	this study was part of a long-term project with the ultimate goal of developing a malaria vaccine for use in man. rhesus monkeys that had been vaccinated with a nonviable antigen given in combination with freund's adjuvant were protected against a normally lethal challenge of plasmodium knowlesi. use of the antigen alone or in combination with other adjuvants was not successful. the fact that monkeys were protected against an infection that is normally lethal suggests that a similarly prepared a ...	1973	4204492
vaccination of rhesus monkeys against malaria by use of sucrose density gradient fractions of plasmodium knowlesi antigens.		1974	4206477
alteration of the liver blood flow and phagocytic activity of the reticuloendothelial system in monkeys infected with plasmodium knowlesi.		1973	4207079
studies on the erythrophagocytosis in rhesus monkeys infected with plasmodium knowlesi.		1973	4207081
letter: atp content in erythrocytes of plasmodium knowlesi-infected monkeys.		1974	4216616
susceptibility of a new world monkey (aotus trivirgatus) to an old world simian malarial parasite (plasmodium knowlesi).		1974	4218385
the movement of radioactive albumin (i131 r.h.s.a.) from blood into c.s.f. and vice versa by dilution method in normal and plasmodium knowlesi infected macaca mulatta.		1968	4234388
factor affecting on the movement of protein across the blood: brain: c.s.f. barriers in plasmodium knowlesi infected macaca mulatta.		1968	4234389
the movement of fluorescent isothiocyanate (f.i.t.c.) labelled human albumin from blood into brain tissue examined by fluorescent technique in normal and plasmodium knowlesi infected macaca mulatta.		1968	4234390
cytochrome oxidase activity in platelet-free preparations of plasmodium knowlesi.		1969	4309811