| effects of cinnamic acid derivatives on in vitro growth of plasmodium falciparum and on the permeability of the membrane of malaria-infected erythrocytes. | cinnamic acid derivatives (cads) are known inhibitors of monocarboxylate transport across plasma and mitochondrial membranes. all derivatives were found to inhibit the growth of intraerythrocytic plasmodium falciparum in culture, which is in correlation with their hydrophobic character. parasites at the ring and trophozoite stages were equally susceptible to the different derivatives. this result could be attributed to their inhibition of the transport of lactate, the major product of parasite e ... | 1992 | 1510401 |
| stereochemical evaluation of the relative activities of the cinchona alkaloids against plasmodium falciparum. | quinine and quinidine were over 100 times more active than 9-epiquinine and 9-epiquinidine against chloroquine-sensitive plasmodium falciparum and over 10 times more active against chloroquine-resistant p. falciparum. since the only structural difference between quinine, quinidine, 9-epiquinine, and 9-epiquinidine is their three-dimensional configuration, the three-dimensional structures of these four alkaloids were examined in order to explain the large difference in relative activities between ... | 1992 | 1510452 |
| anaemia of plasmodium falciparum malaria. | the pathophysiology of the anaemia of falciparum malaria is both complex and multifactorial, and results in a condition which is a major cause of mortality and morbidity in patients, especially children and pregnant women, living in malarial endemic areas. the importance of anaemia as a cause of death in malaria may well be underestimated because of difficulty in diagnosis, especially where parasitaemia may be low and the clinical picture may be confused with other causes of anaemia. two clinica ... | 1992 | 1511178 |
| identification of anti-plasmodium falciparum antibodies in human breast milk. | malarial infections are rarely observed in neonates. it has been postulated that some immunity may be passively transferred during nursing, but anti-malarial antibodies (abs) have not been detected in human milk. in this study, milk samples, collected 2-14 days after parturition from women at the central maternity hospital, yaounde, were evaluated for total igg and iga antibody levels by radial diffusion, protein composition by sds-page, anti-malarial antibodies using an isotype-specific immunof ... | 1992 | 1514035 |
| plasmodium falciparum: a simple polymerase chain reaction method for differentiating strains. | laboratory studies of the protozoan parasite plasmodium falciparum have been hampered by difficulties in defining differences between isolates. we have developed a method based on the polymerase chain reaction (pcr) that allowed us to identify quickly the various strains with which we routinely work. we also adapted methods for easily purifying enough dna to produce a pcr product from a small volume of culture: 100 microliters of an in vitro culture infected at 1% parasitemia. the primers were c ... | 1992 | 1516668 |
| plasmodium falciparum: release of circumsporozoite protein by sporozoites in the mosquito vector. | the release of circumsporozoite (cs) protein by plasmodium falciparum sporozoites was investigated to identify factors regulating this process within infected anopheles gambiae mosquitoes. the potential for sporozoites to release cs protein in vitro was not dependent upon their site-specific developmental stage (i.e., mature oocysts, hemolymph, salivary glands), their duration in the vector, or their exposure to mosquito-derived components such as salivary glands or hemolymph. the capacity of sp ... | 1992 | 1516673 |
| adherence of infected erythrocytes to venular endothelium selects for antigenic variants of plasmodium falciparum. | erythrocytes (e) infected with asexual forms of malaria parasites exhibit surface antigenic variation. in plasmodium falciparum infections, the variant ag is the p. falciparum e membrane protein 1 (pfemp1). this molecule may also mediate the adherence of infected e to host venular endothelium. we show here that parasite lines selected for increased adherence to endothelial cells have undergone antigenic variation. three adherent lines selected from the same p. falciparum clone reacted with the s ... | 1992 | 1517569 |
| binding of malarial circumsporozoite protein to sulfatides [gal(3-so4)beta 1-cer] and cholesterol-3-sulfate and its dependence on disulfide bond formation between cysteines in region ii. | region ii of the malaria circumsporozoite (cs) protein is highly conserved between the cs proteins of different species of malaria. amino acid sequences homologous to that of region ii are found in thrombospondin, properdin, von willebrand factor and a few other proteins. we show here that the native cs protein from the rodent parasite plasmodium berghei, and recombinant plasmodium vivax and plasmodium falciparum cs proteins containing region ii, but not recombinant proteins lacking region ii, s ... | 1992 | 1518521 |
| identification of a plasmodium falciparum histone 2a gene. | | 1992 | 1518525 |
| the plasmodium falciparum hypoxanthine-guanine phosphoribosyl transferase gene has a 5' upstream intron. | | 1992 | 1518526 |
| ribosomal dna sequence comparison of babesia and theileria. | previous studies on the taxonomy of babesia spp. (phylum apicomplexa) using morphological and life cycle characteristics have resulted in their classification into 3 subgenera, with the genus theileria being most closely related to them. using a strategy based on the direct sequence analysis of products derived by asymmetric pcr to determine the nucleotide sequences, we have tested the validity of this classification by sequencing the small subunit ribosomal rna genes amplified from 2 babesia sp ... | 1992 | 1518535 |
| prophylaxis for malaria. helping world travelers come home healthy. | malaria is largely preventable, so travelers should be taught general protective measures and given appropriate chemoprophylaxis before they leave on their trip. chloroquine phosphate (aralen) is still the drug of choice in locations where malaria remains chloroquine-sensitive. however, chloroquine-resistant areas infested with plasmodium falciparum are becoming more numerous. in such areas, mefloquine hydrochloride (lariam), doxycycline, or proguanil (paludrine) (obtainable outside the united s ... | 1992 | 1518752 |
| proposals for a new therapeutic strategy for simple plasmodium falciparum malaria attacks in cameroon. | from simplified in vivo tests, authors set up a cartography of the sensitivity of plasmodium falciparum to amino-4-quinolines in cameroon; they also evaluated the clinical and parasitological efficacy of different therapeutic protocols which make use of amino-4-quinolines, quinine, mefloquine and halofantrine. all these drugs are administered orally. they recommend maintaining home medication with chloroquine at the dose of 25 mg/kg over 3 days, conserving quinine for use in the case of a possib ... | 1992 | 1519023 |
| superantigens, t cells, and microbes. | it is well recognized that toxins of staphylococcus aureus and streptococcus pyogenes are responsible for a wide range of clinical conditions, although their precise mode of action remains unclear. recently, there has been a resurgence of interest in these toxins, now grouped with superantigens, because they cause profound alterations in the immune system homeostasis. superantigens are molecules, including endogenous retroviral gene products and microbial toxins, that share a unique set of chara ... | 1992 | 1520765 |
| imported malaria in pregnancy: report of four cases and review of management. | malaria is a common infection worldwide. increased travel by pregnant women makes it likely that physicians in the united states will see cases of malaria in this population. we observed four cases of malaria during pregnancy over an 8-month period at a general hospital in the united states. these cases illustrate the association between pregnancy and severe malaria in the mother and congenital infection in the newborn. we also noted delays in diagnosis because malaria was mistaken for other com ... | 1992 | 1520785 |
| plasmodium falciparum: differential sensitivity in vitro to e-64 (cysteine protease inhibitor) and pepstatin a (aspartyl protease inhibitor). | we investigated the effect of a cysteine proteinase inhibitor (e-64) and an aspartyl proteinase inhibitor (pepstatin a) on asexual erythrocytic stages of plasmodium falciparum in culture. these two protease inhibitors showed different patterns of activity. e-64 acted preferentially against trophozoite and schizont stages. after 48 h incubation at high concentrations of e-64 (28, 140, 280 microm), growth was totally abolished and the parasites presented characteristic enlarged food vacuoles. morp ... | 1992 | 1522541 |
| continuous cultivation and drug susceptibility testing of plasmodium falciparum in a malaria endemic area. | isolates (uch-23 and om) and cloned strains of plasmodium falciparum (clones w-2 and d-6) were maintained in continuous culture for 28 to 150 days using culture media supplemented with 10% (v/v) heat inactivated semi-immune human plasma. microscopic appearance and growth rates (r) of the parasites in media supplemented with semi-immune human plasma [r = 1.13 (w-2), 0.92 (d-6), 0.75 (om) and 0.84 (uch-23)] were comparable to those of parallel cultures maintained in media supplemented with 10% (v/ ... | 1992 | 1522542 |
| codon usage in giardia lamblia. | a codon usage table for the intestinal parasite giardia lamblia was generated by analysis of the nucleotide sequences of eight genes comprising 3,135 codons. codon usage revealed a biased use of synonymous codons with a preference for nnc codons (42.1%). the codon usage of g. lamblia more closely resembles that of the prokaryote halobacterium halobium (correlation coefficient r = 0.73) rather than that of other eukaryotic protozoans, i.e. trypanosoma brucei (r = 0.434) and plasmodium falciparum ... | 1992 | 1522548 |
| thrombocytopenia in malaria. | the relationship between platelet counts and platelet bound (direct) or platelet directed (indirect) serum antibody concentrations was studied in 17 patients with plasmodium falciparum malaria and 12 patients with p. vivax malaria. platelet counts rose with recovery from infection from 196 +/- 84 x 10(9)/l (mean +/- sd) and 195 +/- 34 x 10(9)/l to 319 +/- 99 and 283 +/- 62 x 10(9)/l respectively (p less than 0.002), but there was no relationship between either absolute platelet count or changes ... | 1992 | 1523477 |
| comparative trial on the response of plasmodium falciparum to halofantrine and mefloquine in trat province, eastern thailand. | with the appearance of strains of plasmodium falciparum in the trat province, eastern thailand, reported to have developed resistance to mefloquine there is a need for an alternative drug. this comparative trial with mefloquine and halofantrine has demonstrated extremely low cure rates with both drugs (33.3% and 28.13% respectively), cross-resistance is suggested. | 1992 | 1523479 |
| malaria--the mime revisited: fifteen more years of experience at a new york city teaching hospital. | purpose and patients: a previous review of the new york hospital experience with malaria during 1968 to 1975 summarized clinical and parasitologic features in 24 travelers and highlighted deficiencies in both chemoprophylaxis and diagnosis. to extend this original study, we describe 86 patients with malaria seen at the same hospital during the subsequent 15 years. results: eighty patients were infected with a single plasmodium species, and 60% had plasmodium falciparum infection primarily acquir ... | 1992 | 1524074 |
| ovalocytosis protects against severe malaria parasitemia in the malayan aborigines. | the malaria parasite rates and densities were compared in 79 ovalocytic-normocytic pairs of malayan aborigines matched for age, sex, proximity of residence to each other, and use of bed nets when sleeping in their jungle settlement in central peninsular malaysia. malaria infection was determined from thick and thin giemsa-stained blood films collected monthly for a period of six months. blood films from ovalocytic individuals were found to be positive for malaria less often than in persons with ... | 1992 | 1524139 |
| the effectiveness of permethrin-impregnated bed nets against malaria for migrant workers in eastern thailand. | a randomized, double-blind, field trial was carried out to compare the effectiveness of permethrin-treated bed nets with that of untreated nets as a method of malaria control for migrant workers in eastern thailand. the study was conducted using 261 subjects in eastern rural areas that are known to be highly endemic for multidrug-resistant plasmodium falciparum infection. one hundred twenty-six subjects used treated nets, while 135 used untreated nets. during the 35 weeks of observation, 23 subj ... | 1992 | 1524143 |
| heightened transmission of stable malaria in an isolated population in the highlands of irian jaya, indonesia. | malaria at an elevation of 1,500 meters is uncommon and is usually unstable when it occurs. to confirm reports of a recent increase in transmission of stable malaria in the oksibil valley, which is at an elevation of 1,250-1,500 meters in the jayawijaya mountains of irian jaya, indonesia, five malariometric surveys were conducted in four villages between may 1990 and july 1991. a total of 3,380 blood smears, representative of 1,949 persons, was examined. prevalence rates over the survey period w ... | 1992 | 1524148 |
| mefloquine-halofantrine cross-resistance in plasmodium falciparum induced by intermittent mefloquine pressure. | the study was designed to evaluate how exposure of plasmodium falciparum to mefloquine modifies the sensitivity of the parasite to four major antimalarial drugs. a recently culture-adapted strain of p. falciparum was subjected to intermittent drug pressure at three different mefloquine concentrations (2.34, 4.68, and 9.37 ng/ml). growth was monitored by daily evaluation of parasitemia on thin smears. drug sensitivity tests were done weekly, using a radioisotope microdilution method. mefloquine w ... | 1992 | 1524151 |
| in vitro activity of the enantiomers of mefloquine, halofantrine and enpiroline against plasmodium falciparum. | the in vitro activity of the enantiomers of mefloquine, halofantrine and enpiroline was compared against chloroquine-resistant and -susceptible strains of plasmodium falciparum using a semi-micro drug susceptibility test. for each strain, the corresponding enantiomers exhibited similar activities. the enantiomers of halofantrine were the most active against both susceptible and resistant strains, followed by the enantiomers of mefloquine and enpiroline. | 1992 | 1524966 |
| assessment of chloroquine resistance of plasmodium falciparum in children of wad medani (central sudan). | the study reports on chloroquine resistance of plasmodium falciparum among sudanese children (6 month to 16 years) living at wad medani, central sudan. all ri-iii levels of resistant response were confirmed, while in vitro sensitivity test indicated that 25 per cent of p. falciparum isolates examined had exhibited maturation of schizonts at cq level greater than or equal to 1.6 pmol/microliters blood. cq was sufficiently retained for 7 days after drug administration whereas an average peak level ... | 1992 | 1527810 |
| antimalarial activities of oligodeoxynucleotide phosphorothioates in chloroquine-resistant plasmodium falciparum. | synthetic oligonucleotides and their chemical modifications have been shown to inhibit viral and cellular gene expression by sequence-specific antisense hybridization to target mrnas. we now report that oligodeoxynucleotide phosphorothioates and their nuclease-resistant modifications are effective in micromolar and submicromolar concentrations against the growth of both chloroquine-resistant and chloroquine-sensitive strains of plasmodium falciparum in vitro. parasitized human erythrocytes were ... | 1992 | 1528864 |
| energy dependence of chloroquine accumulation and chloroquine efflux in plasmodium falciparum. | chloroquine inhibits the growth of susceptible malaria parasites at low (nanomolar) concentrations because of an energy-requiring drug-concentrating mechanism in the parasite secondary lysosome (food vacuole) which is dependent on the acidification of that vesicle. chloroquine resistance results from another energy-requiring process: efflux of chloroquine from the resistant parasite with a half-time of 2 min. chloroquine efflux is inhibited reversibly by the removal of metabolizable substrate (g ... | 1992 | 1531176 |
| [severe plasmodium falciparum malaria attacks during chemoprophylaxis with chloroquine and proguanil]. | | 1992 | 1531267 |
| human peripheral blood gamma delta t cells respond to antigens of plasmodium falciparum. | peripheral blood lymphocytes from donors previously unexposed to malaria parasites proliferate in vitro when stimulated with whole parasitized red blood cells of several different strains of plasmodium falciparum. here we show that both cells enriched for both memory (cd45r0+) and naïve (cd45r0-) phenotype can respond. cells involved in these responses occur at frequencies similar to those observed for recall antigens such as tetanus toxoid but at lower frequencies than observed for the superant ... | 1992 | 1531764 |
| a specific t-cell receptor genotype preference in the immune response to a synthetic plasmodium falciparum malaria vaccine. | in recent studies with 63 and 122 volunteers vaccinated with the spf 66 synthetic malaria vaccine, specific antibody patterns were classified as high or low responders. using the polymerase chain reaction (pcr), a specific and selective preference was shown for the v beta arrangement of the t-cell receptor in the high responder group involving the v beta-8 gene. the low responder group showed the rearrangement of a different set of genes, and a particular association with v beta-10. | 1992 | 1532634 |
| preferential expansion of v gamma 9 v delta 2 t cells following stimulation of peripheral blood lymphocytes with extracts of plasmodium falciparum. | a plasmodium falciparum schizont lysate has been previously described as being a powerful inducer of proliferation for human peripheral t lymphocytes. in this report we study the phenotype of cycling t cells from unexposed donors and examine how the p. falciparum lysate compares with the conventional t cell mitogen phytohemagglutinin (pha), a known superantigen staphylococcal enterotoxin b (seb), and a classical antigen pure protein derivative (ppd). we show that for this lymphoproliferative act ... | 1992 | 1533150 |
| [resistance of plasmodium falciparum to the chloroquine-proguanil combination. a case from benin]. | | 1992 | 1534624 |
| multi-drug resistant falciparum malaria in cameroon in 1987-1988. i. stable figures of prevalence of chloroquine- and quinine-resistant isolates in the original foci. | the status of drug-resistant plasmodium falciparum in cameroon was determined in 1987-1988 in 221 children who were selected for chloroquine and quinine in vitro microtests. resistance to quinine was found in 17% of 72 isolates from the southern part of the country, and in 7% of 87 isolates from the northern part of the country. the effective concentrations of 50% and 90% (ec50 and ec90) differed little from those observed in 1986. in southern cameroon, 38 (51%) of 74 individuals harbored chloro ... | 1992 | 1536378 |
| is anopheles mascarensis a new malaria vector in madagascar? | anopheles mascarensis de meillon, 1947, a mosquito that is native to madagascar, is reported for the first time to act as a vector of plasmodium falciparum malaria. from september 1989 to march 1990, 2, 499 an. mascarensis specimens from different regions of madagascar were tested by an enzyme-linked immunosorbent assay (elisa), using monoclonal antibodies against the circumsporozoite (cs) protein of the four human species of plasmodium. the salivary glands of 237 specimens were also dissected. ... | 1992 | 1536380 |
| construction of a genomic dna library of the toxoplasma gondii zs2 strain, screening of specific clones, and dna diagnosis of toxoplasmosis. | we have constructed a genomic dna library of the toxoplasma gondii zs2 strain and isolated a specific cloned dna sequence from this organism. the restriction map of this cloned 1.1-kb dna fragment was analyzed. southern and dot-blot analyses showed that the 32p-labeled dna fragment hybridized to parasite dna, to dnas from peripheral blood leukocytes and the thymus of baby pigs that were artificially infected with t. gondii, and to dnas of t. gondii-positive anencephalic and hydrocephalic fetuses ... | 1992 | 1536384 |
| multi-drug resistant falciparum malaria in cameroon in 1987-1988. ii. mefloquine resistance confirmed in vivo and in vitro and its correlation with quinine resistance. | to further document the phenomenon of plasmodium falciparum resistance to mefloquine formerly described in cameroon, complementary in vivo and in vitro studies were conducted. two hundred six p. falciparum isolates were studied in vitro using an isotopic microassay with mefloquine solutions prepared daily. using the cutoff limit of 30 nmol, 26 (20%) of 133 isolates from the northern part of the country were defined as being resistant to mefloquine. in contrast, only one of 73 isolates collected ... | 1992 | 1536387 |
| cross-reaction of antibodies to the nine-amino acid repeats of plasmodium falciparum antigen 11.1 with human serum albumin. | mice immunized with the recombinant antigen 11.1 beta-galactosidase, consisting of 22 repeats of the nine-amino acid unit from plasmodium falciparum antigen 11.1, produced antibodies reacting with human serum albumin. a positive reaction was observed in dot-blot assays, in enzyme-linked immunosorbent assay and on immunoblots of sodium dodecyl sulfate polyacrylamide gels as well as two-dimensional gels. binding was specific for human albumin, as no reaction could be detected on bovine serum album ... | 1992 | 1537376 |
| detection of plasmodium falciparum dna in a microtitration plate-based hybridization test. | a rapid dna-test, depending on the affinity based hybrid collection principle, was developed for the detection of plasmodium falciparum dna from clinical specimens. in this method, hybridization takes place in solution and the hybrids are collected onto a solid phase for measurement. two probes are used, one labelled with an affinity tag (biotin) and the other with a detectable label (32p). in the present test a single oligonucleotide complementary to a 21-base pair sequence which is highly repe ... | 1992 | 1537547 |
| the statistical analysis of data from immunoepidemiological studies. | immune responses encountered in human populations display a higher level of heterogeneity than is typically seen with laboratory animals, and the expected clear distinction between responders and non-responders to particular antigens may not be apparent. in such a situation, the methods of statistical analysis traditionally used in laboratory studies may no longer be appropriate, and there is no consensus among immunologists about how such data should be analysed. using data from a large study o ... | 1992 | 1538144 |
| smear-negative cerebral malaria due to mefloquine-resistant plasmodium falciparum acquired in the amazon. | | 1992 | 1538173 |
| basis of unique red cell membrane properties in hereditary ovalocytosis. | hereditary ovalocytes from a mauritian subject are extremely rigid, with a shear elastic modulus about three times that of normal cells, and have increased resistance to invasion by the malaria parasite plasmodium falciparum in vitro. the genetic anomaly resides in band 3; the protein gives rise to chymotryptic fragments with reduced mobility in sds/polyacrylamide gel electrophoresis, but this is a result of anomalous binding of sds and not a higher molecular weight. analysis of the band 3 gene ... | 1992 | 1538405 |
| intraspecific chromosomal polymorphism in the anopheles gambiae complex as a factor affecting malaria transmission in the kisumu area of kenya. | the paracentric inversion polymorphisms of anopheles gambiae and an. arabiensis populations in the kisumu area of western kenya were studied in relation to parameters of plasmodium falciparum transmission. anopheles gambiae (n = 1,387) was polymorphic for inversions b on chromosomal arm 2r and a on arm 2l, with frequencies of the inverted arrangements of 17% and 43%, respectively. anopheles arabiensis (n = 484) was polymorphic for inversion b on chromosomal arm 2r and a on 3r, with frequencies o ... | 1992 | 1539757 |
| dictyostelium discoideum as an expression host for the circumsporozoite protein of plasmodium falciparum. | we have used the cellular slime mold, dictyostelium discoideum (dd), to express the plasmodium falciparum circumsporozoite protein (cs), a potential component of a subunit vaccine against malaria. this was accomplished via an expression vector based on the discoidin i-encoding gene promoter, in which we linked a sequence coding for a dd leader peptide to the almost complete cs coding region (pedii-cs). cs production at both the mrna and protein levels is induced by starving cells in a simple pho ... | 1992 | 1541397 |
| serological relationship of tumor necrosis factor-inducing exoantigens of plasmodium falciparum and plasmodium vivax. | exoantigens of plasmodium vivax-parasitized erythrocytes stimulated macrophages to secrete tumor necrosis factor, and antisera raised against the exoantigens inhibited this secretion. the antisera also inhibited the activity of plasmodium falciparum and plasmodium yoelii exoantigens, and conversely, antisera against the latter cross-reacted with the exoantigens of p. vivax. | 1992 | 1541540 |
| antimalarial properties of n-3 and n-6 polyunsaturated fatty acids: in vitro effects on plasmodium falciparum and in vivo effects on p. berghei. | the polyunsaturated fatty acids docosahexaenoic acid (c22:6,n-3), eicosapentaenoic acid, arachidonic acid, and linoleic acid caused marked in vitro growth inhibition of plasmodium falciparum, assessed by a radiometric assay. in contrast, negligible parasite killing was seen with oleic acid or docosanoic acid. parasite killing was significantly increased when oxidized forms of polyunsaturated fatty acids were used. antioxidants greatly reduced the fatty acid-induced killing. mice infected with p. ... | 1992 | 1541684 |
| the 42-kilodalton rhoptry-associated protein of plasmodium falciparum. | the gene coding for a 42-kda rhoptry protein of plasmodium falciparum has been cloned. on the basis of prior monkey vaccination studies, this protein is regarded as an important vaccine candidate, but its identity has been the subject of considerable uncertainty. analysis of the cloned sequence shows that it is a basic, hydrophobic protein, without repetitive elements, unrelated to any of the previously postulated gene products and shows minimal sequence diversity. the availability of the corres ... | 1992 | 1542308 |
| purification and properties of plasmodium falciparum malate dehydrogenase. | asexual intraerythrocytic plasmodium falciparum were shown to have a single isoenzyme of malate dehydrogenase. this malate dehydrogenase was purified to apparent homogeneity using a three-step purification protocol. the parasite malate dehydrogenase had an apparent subunit molecular weight of 32 kda, a ph optimum of 7.0 for the reduction of oxaloacetate, and a sharp thermal transition between 40 degrees c and 45 degrees c. these characteristics distinguish p. falciparum malate dehydrogenase from ... | 1992 | 1542310 |
| single amino acid variation in the ookinete vaccine antigen from field isolates of plasmodium falciparum. | | 1992 | 1542311 |
| two novel alleles within subfamilies of the merozoite surface antigen 2 (msa-2) of plasmodium falciparum. | | 1992 | 1542312 |
| two types of sequence polymorphism in the circumsporozoite gene of plasmodium falciparum. | here we demonstrate two characteristically different classes or types of gene sequence variation in the circumsporozoite protein from plasmodium falciparum. some patterns of sequence variation suggest, or are at least consistent with, mendelian inheritance. we show here that patterns of sequence variation at specific positions, however, introduce homoplasy (similarity or identity not directly attributable to common ancestry) into the relationship between parasites. the demonstration of extensive ... | 1992 | 1542315 |
| homologies between the contiguous and fragmented rrnas of the two plasmodium falciparum extrachromosomal dnas are limited to core sequences. | plasmodium falciparum contains two extrachromosomal dnas, a 6 kb linear element and a 35 kb circular dna; both encode rdna sequences. the 6 kb element rdnas comprise fragments of both large and small subunit rrnas. comparison of these with corresponding rdna sequences from the 35 kb dna and e. coli show that sequences conserved between the three are largely confined to highly conserved core regions; in fact, most of the 6 kb rdna sequences correspond to core regions. both the 6 kb element and 35 ... | 1992 | 1542578 |
| the pf332 gene of plasmodium falciparum codes for a giant protein that is translocated from the parasite to the membrane of infected erythrocytes. | we studied the gene structure of the plasmodium falciparum antigen 332 (ag332). the gene size was estimated to be approx. 20 kb based on the large size of both the transcript found in mature asexual blood stage parasites and mung bean nuclease fragment generated from genomic dna. sequence analysis of genomic and cdna clones representing different regions of the pf332 locus showed that the gene product contains a large number of highly degenerated glutamic acid (glu)-rich repeats (32% glu). the g ... | 1992 | 1544579 |
| treatment of chloroquine-resistant malaria in african children: a cost-effectiveness analysis. | because chloroquine (cq)-resistant plasmodium falciparum (crpf) has now spread throughout most of africa, the efficacy and practicability of other drugs such as amodiaquine (aq), and pyrimethamine-sulfadoxine (ps), for the treatment of fever needs to be assessed. we used a decision-analysis model to compare the cost and effectiveness of cq, aq, and ps. the variables considered were the probability of p. falciparum infection, drug compliance, minor and lethal side effects of the drug, the level o ... | 1992 | 1544746 |
| antiparasitic agents. | in recent years, introduction of new and more effective agents has improved the overall therapy for parasitic infections. this field, however, is still plagued by numerous problems, including the development of resistance to antimicrobial agents (especially with malaria), unavailability of agents in the united states or lack of approval by the food and drug administration, and major toxicities or lack of experience in pregnant women and children, which limits use in these groups of patients. wid ... | 1992 | 1545596 |
| malaria vaccine on trial at last? | | 1992 | 1546305 |
| transcription of the gene for the merozoite surface antigen msa2 of the human malaria parasite plasmodium falciparum during the asexual cycle. | the transcription of the plasmodium falciparum gene for the msa2 antigen has been studied throughout the parasite's asexual growth cycle. for this purpose poly(a)+ rna from different times of the cycle was tested for the presence of the mrna encoding msa2 by in vitro translation and subsequent analysis of the translation products by immunoprecipitation with an antibody against msa2. the results revealed that this mrna is present in trophozoites, reaches the highest concentration during the trans ... | 1992 | 1547892 |
| roles of conserved and allelic regions of the major merozoite surface protein (gp195) in immunity against plasmodium falciparum. | the plasmodium falciparum major merozoite surface protein gp195 is a candidate antigen for a vaccine against human malaria. the significance of allelism and polymorphism in vaccine-induced immunity to gp195 was investigated in this study. rabbits were immunized with each of two allelic forms of gp195 that were affinity purified from the fup and fvo parasite isolates. gp195-specific antibodies raised against one allelic form of gp195 cross-reacted extensively with the gp195 of the heterologous al ... | 1992 | 1548068 |
| plasmodium falciparum malaria: evidence for an isotype imbalance which may be responsible for delayed acquisition of protective immunity. | in view of the recent demonstration that antibodies that are protective against plasmodium falciparum malaria may act in collaboration with blood monocytes, we investigated the isotype content of sera from individuals with defined clinical states of resistance or susceptibility to malaria. profound differences in the distribution of each immunoglobulin subclass were found. immunoglobulin g1 (igg1) and igg3, two cytophilic isotypes, predominated in protected subjects. in nonprotected subjects, i. ... | 1992 | 1548071 |
| the disposition of oral and intramuscular pyrimethamine/sulphadoxine in kenyan children with high parasitaemia but clinically non-severe falciparum malaria. | 1. h.p.l.c. methods are described for the measurement of pyrimethamine and sulphadoxine in small volumes of plasma dried on filter paper strips. 2. pyrimethamine/sulphadoxine (fansidar, hoffman laroche) was given by mouth and by intramuscular injection to children with uncomplicated falciparum malaria but with high parasitaemia (n = 8 for both routes; pyrimethamine 1.25 mg kg-1, sulphadoxine 25 mg kg-1). 3. plasma concentrations of pyrimethamine and sulphadoxine associated with synergistic effec ... | 1992 | 1550695 |
| plasmodium falciparum malaria in pregnancy: a review. | | 1992 | 1554661 |
| in human malaria protective antibodies are directed mainly against the lys-glu ion pair within the lys-glu-lys motif of the synthetic vaccine spf 66. | the kek (lysine-glutamic acid-lysine) motif is frequently found in the primary structure of certain malaria proteins involved in invasion, and plays an important role in the interaction of these proteins with the erythrocyte. this motif is contained in a peptide which forms part of the polymeric synthetic malaria vaccine spf 66, currently undergoing extensive human trials. analysis of the antibody titres against the subunit peptides that comprise this vaccine has shown that protection is associa ... | 1992 | 1557226 |
| anti-circumsporozoite protein antibodies measure age related exposure to malaria in kataragama, sri lanka. | antibodies to two peptides ddaad and (nanp)40 representing the repetitive sequence of circumsporozoite antigens (cs protein) of p. vivax and p. falciparum respectively were measured in a cohort of 149 and 107 individuals respectively at four, 6 monthly blood surveys performed on residents of kataragama, a p. vivax malaria endemic region in southern sri lanka. the prevalence of antibodies to the cs protein of both species was relatively low being less than 20% to either peptide in the population ... | 1992 | 1557232 |
| determination of the immunization schedule for field trials with the synthetic malaria vaccine spf 66. | the synthetic malaria vaccine spf 66 has been shown to be safe, immunogenic and effective in trials performed with controlled groups naturally and experimentally exposed to the disease. in order to continue the trials in open populations, it was necessary to standardize the vaccination characteristics. we have performed four field trials with soldier volunteers with the aim, among others, of defining the number of doses required, the intervals between applications, the protein concentration, and ... | 1992 | 1557233 |
| the effect of nosematosis on the development of plasmodium falciparum in anopheles stephensi. | to quantify the effect of nosema algerae (microsporidia, nosematidae) on the development of plasmodium falciparum in anopheles stephensi (diptera, culicidae), we carried out infection experiments under standardized laboratory conditions. apart from a mean reduction of 69% in oocyst development, smaller numbers of oocysts and fewer sporozoites were found in the nosema-infected mosquitoes. in addition, nosematosis resulted in higher mortality. the potential role of nosema algerae as a biological c ... | 1992 | 1557330 |
| study of the safety and immunogenicity of the synthetic malaria spf66 vaccine in children aged 1-14 years. | safety and immunogenicity tests of the spf66 malaria vaccine have been carried out on a population of children, aged 1 to 14 years, in the town of tumaco, colombia. adverse reactions measured after each vaccination were local and minimal, and observed in only a small percentage of the vaccinated children. one year later, no delayed reaction was evident. the majority of the child population developed high antibody titres against spf66 and the degree of response did not vary with age. these induce ... | 1992 | 1557933 |
| the first field trials of the chemically synthesized malaria vaccine spf66: safety, immunogenicity and protectivity. | this paper reports the results of the first field study performed to assess the safety, immunogenicity and protectivity of the synthetic malaria vaccine spf66 directed against the asexual blood stages of plasmodium falciparum. clinical and laboratory tests were performed on all volunteers prior to and after each immunization, demonstrating that no detectable alteration was induced by the immunization process. the vaccines were grouped as high, intermediate or low responders according to their an ... | 1992 | 1557934 |
| antibodies to a recombinant glutamate-rich plasmodium falciparum protein: evidence for protection of individuals living in a holoendemic area of liberia. | a plasmodium falciparum antigen gene coding for a 220-kd glutamate-rich protein (glurp) has been cloned, and the 783 c-terminal amino acids of this protein (glurp489-1271) have been expressed as a beta-galactosidase fusion protein in escherichia coli. the encoded 783 amino acid residues contain two areas of repeated amino acid sequences. antibodies against recombinant glurp489-1271, as well as against a synthetic peptide corresponding to glurp899-916, and against a synthetic peptide representing ... | 1992 | 1558270 |
| immunoenzymatic labeling of multiple plasmodial salivary gland sporozoites in a single test. | a direct, double- and triple-staining immunoenzymatic method detected and differentiated sporozoites by color in anopheles stephensi salivary glands and in mixed sporozoite slide preparations. a double-staining method used beta-galactosidase- and alkaline phosphatase-labeled monoclonal antibodies to the circumsporozoite (cs) proteins of plasmodium berghei and p. falciparum in mosquito salivary glands. the cs proteins were distinguished clearly by the blue-green and red substrate products of beta ... | 1992 | 1558271 |
| susceptibility of owl monkeys to plasmodium falciparum in relation to hemoglobin and karyotype. | humans with inherited abnormalities of hemoglobin (hb) synthesis have less frequent and less severe infections of malaria. this study sought to determine if karyotypic variation in the owl monkey was expressed as differences in hb moieties and if it offered a selective advantage in susceptibility to malaria. five karyotypes of owl monkey were evaluated on the basis of the electrophoretic mobility of their major and minor hb components. the results of 40 owl monkeys of different karyotypes demons ... | 1992 | 1558276 |
| molecular factors responsible for host cell recognition and invasion in plasmodium falciparum. | in plasmodium falciparum, the rhoptries involved in the invasion process are a pair of flask-shaped organelles located at the apical tip of invading stages. they, along with the more numerous micronemes and dense granules, constitute the apical complex in plasmodium and other members of the phylum apicomplexa. several proteins of varying molecular weight have been identified in p. falciparum rhoptries. these include the 225-, 140/130/110-, 80/60/40-, rap-1 80-, ama-1 80-, qf3 80-, and 55-kda pro ... | 1992 | 1560416 |
| changing patterns of malaria in south-east scotland: implications for practitioner awareness and prophylactic advice. | the medical records of all 229 patients with malaria admitted to the edinburgh city hospital between 1969 and 1988 were studied retrospectively. a total of 137 were from africa, 44 from the indian subcontinent, 19 from the far east, 18 from new guinea, 5 from the middle east and 3 from south america. the number of yearly admissions rose markedly after 1983, mainly due to an increase in plasmodium falciparum cases. ninety-four cases (15 with severe parasitaemia) mainly from kenya and nigeria were ... | 1992 | 1561183 |
| phagocyte meets "desperado". | | 1992 | 1561422 |
| vacuolar acidification and chloroquine sensitivity in plasmodium falciparum. | the antimalarial chloroquine concentrates in the acid vesicles of plasmodium falciparum partially as a result of its properties as a weak base. chloroquine-resistant parasites accumulate less drug than sensitive parasites. a simple hypothesis is that the intravacuolar ph of resistant strains is higher than that for sensitive strains, as a consequence of a weakened proton pump in the vacuoles of resistant strains, thereby explaining the resistance mechanism. we have attempted to test this hypothe ... | 1992 | 1562274 |
| modulation of the cellular immune response during plasmodium falciparum infections in sickle cell trait individuals. | plasma and peripheral blood mononuclear cells (pbmc) were obtained from p. falciparum-infected individuals with and without the sickle cell trait at diagnosis and 7 days after treatment. hbaa and hbas patients were compared for levels of plasma soluble il-2 receptors (il-2r) and the in vitro cellular reactivity to affinity-purified soluble p. falciparum antigens (spag), ppd and phytohaemagglutinin (pha). at diagnosis, hbas patients with clinical disease had lower plasma-soluble il-2r levels and ... | 1992 | 1563096 |
| defence mechanisms and immune evasion in the interplay between the humane immune system and plasmodium falciparum. | immunity to p. falciparum malaria is developed as a result of long term exposure to the parasite and depends on immunological memory. the key directors in immune recognition and regulation of the immunological responses are the t-cells. it seems reasonable to propose that immunity is acquired when a critical mass of t-cells, recognizing relevant malaria antigens, has been developed. these t-cells mediate immunity by regulating macrophage and b-cell activity, but they may also act directly as cyt ... | 1992 | 1563295 |
| safety, immunogenicity, and efficacy of a plasmodium falciparum vaccine comprising a circumsporozoite protein repeat region peptide conjugated to pseudomonas aeruginosa toxin a. | twenty-one malaria-naive volunteers were immunized with a vaccine consisting of a 22-kda recombinant peptide (r32lr), derived from the repeat region of plasmodium falciparum circumsporozoite (cs) protein, covalently coupled to detoxified pseudomonas aeruginosa toxin a. nineteen volunteers received a second dose of vaccine at 8 weeks, and eighteen received a third dose at 8 to 12 months. the vaccine was well tolerated, with only one volunteer developing local discomfort and induration at the site ... | 1992 | 1563771 |
| detoxified exoantigens and phosphatidylinositol derivatives inhibit tumor necrosis factor induction by malarial exoantigens. | we have previously shown that malaria parasites liberate exoantigens which, through a phospholipid component, stimulate mouse macrophages to secrete tumor necrosis factor (tnf), which are toxic to d-galactosamine-sensitized mice, and which therefore might be involved in pathology. plasmodium yoelii exoantigens detoxified by dephosphorylation or digestion with lipases do not induce tnf production. however, these partial structures inhibited its production in response to the exoantigens, although ... | 1992 | 1563780 |
| isolation and characterization of a cysteine proteinase gene of plasmodium falciparum. | we have previously identified a 28-kda cysteine proteinase of plasmodium falciparum trophozoites that appears to be an essential malarial hemoglobinase and a potential target for antimalarial chemotherapy. the trophozoite cysteine proteinase (tcp) shares a number of biochemical properties with the lysosomal cysteine proteinase cathepsin l. to isolate the gene encoding tcp, we synthesized degenerate oligonucleotides based on two amino acid sequences of cathepsin l that are well conserved among pa ... | 1992 | 1565129 |
| localization of the 175-kilodalton erythrocyte binding antigen in micronemes of plasmodium falciparum merozoites. | | 1992 | 1565131 |
| binding of plasmodium falciparum 175-kilodalton erythrocyte binding antigen and invasion of murine erythrocytes requires n-acetylneuraminic acid but not its o-acetylated form. | sialic acid on human erythrocytes is involved in invasion by the human malaria parasite, plasmodium falciparum. mouse erythrocytes were used as a reagent to explore the question of whether erythrocyte sialic acid functions as a nonspecific negative charge or whether the sialic acid is a necessary structural part of the receptor for merozoites. human erythrocytes contain n-acetylneuraminic acid (neu5ac), whereas mouse erythrocytes, which are also invaded by p. falciparum merozoites, contain 9-o-a ... | 1992 | 1565137 |
| activity of chloroquine and desferrioxamine in vitro against newly isolated plasmodium falciparum and their antagonism in combination. | | 1992 | 1566289 |
| antimalarial activity in vitro of the n-desbutyl derivative of halofantrine. | | 1992 | 1566290 |
| seasonal changes in cell mediated immune responses to soluble plasmodium falciparum antigens in children with haemoglobin aa and haemoglobin as. | in this longitudinal study peripheral blood mononuclear cells (pbmc) were obtained before and during the malaria season from healthy hbaa and hbas children. cells were compared for proliferation in response to stimulation by soluble plasmodium falciparum antigens (spag) or purified derivative of tuberculin (ppd). the lymphoproliferative responses to spag of the paired pbmc samples showed 2 distinct seasonal changes in relation to the haemoglobin phenotype. in hbaa children, the lymphoproliferati ... | 1992 | 1566293 |
| rapid detection of pfmdr1 mutations in chloroquine-resistant plasmodium falciparum malaria by polymerase chain reaction analysis of blood spots. | | 1992 | 1566295 |
| studies on a new antimalarial compound: pyronaridine. | pyronaridine, a hydroxyanilino-benzonaphthyridine derivative synthesized in 1970, is a new antimalarial compound which has been in use in china for more than 10 years. the drug is highly effective against plasmodium falciparum and p. vivax. furthermore, it is efficacious in combatting chloroquine-resistant strains of falciparum malaria both in vitro and in vivo, in human patients. extensive field studies involving several thousand cases have shown that pyronaridine has promising therapeutic valu ... | 1992 | 1566313 |
| norfloxacin is inferior to chloroquine for falciparum malaria in northwestern zambia: a comparative clinical trial. | fluoroquinolones are active against plasmodium falciparum in vitro. in a prospective, randomized, comparative trial, norfloxacin, 400 mg twice a day for 3 days, was compared with a standard course of chloroquine in semiimmune adults with symptomatic falciparum malaria in northwestern zambia, where chloroquine resistance is uncommon. patients were followed for 28 days. the trial was terminated after 38 patients were studied because chloroquine was markedly more effective, curing all 18 patients ( ... | 1992 | 1569341 |
| mouse model for exoerythrocytic stages of plasmodium falciparum malaria parasite. | research on the exoerythrocytic (ee) stages of human malaria parasites has been hindered because of the lack of an easily available suitable animal model. we report here an approach to produce mature ee-stage plasmodium falciparum parasites by using severe combined immunodeficient (scid) mice with transplanted human hepatocytes. transplantation of human hepatocytes into scid mice (scid hu-hep), their subsequent intravenous infection with p. falciparum sporozoites, and the development of mature l ... | 1992 | 1570289 |
| [the diagnostic and treatment characteristics of tropical malaria]. | | 1992 | 1570700 |
| reduced deformability of thalassemic erythrocytes and erythrocytes with abnormal hemoglobins and relation with susceptibility to plasmodium falciparum invasion. | a number of genetically variant erythrocytes showed decreased deformability of both intact cells and membranes prepared therefrom as measured by laser diffractometry. erythrocytes associated with minor or no clinical symptoms (eg, alpha-thalassemia traits, hemoglobin [hb] e trait, hb constant spring trait), which showed only a minimal decrease in deformability, were, in general, invaded efficiently by the malarial parasite plasmodium falciparum. other variant erythrocytes (beta-thalassemia/hb e, ... | 1992 | 1571557 |
| the role of interleukin-6 in vitamin a deficiency during plasmodium falciparum malaria and possible consequences for vitamin a supplementation. | kinetics of serum levels of interleukin-6 (il-6) were studied in patients with acute plasmodium falciparum malaria in relation to vitamin a and its binding proteins, retinol binding protein (rbp) and pre-albumin. it was found that il-6 levels followed the rise and decrease of parasitaemia by 12 hr and correlated inversely with levels of vitamin a and its binding proteins. these data suggest that vitamin a supplementation alone might still be insufficient to restore a malaria-induced vitamin a de ... | 1992 | 1572702 |
| [malaria and pregnancy. therapeutic problems, a case report]. | malaria is an old but still current parasitosis. transmitted by the bite of the female anopheles, it can be revealed by more or less serious symptoms according to the species of plasmodium. plasmodium falciparum is responsible for the serious forms. it is the most frequent species, resistant to 4 amino-quinolein and sulfamides in some areas. p. vivax and p. ovale, usually harmless, are not so widely geographically spread as p. falciparum; and apparently are not drug resistant but they expose pat ... | 1992 | 1573223 |
| efficacy, safety and acceptability of halofantrine in the treatment of acute plasmodium falciparum malaria in african children (gabon). | halofantrine chlorhydrate 2 per cent suspension was given to 50 children (mean age 6.2 years in a dose of 8 mg/kg three times a day as a single day treatment. the children were born and lived in gabon, where malaria transmission is continuous. they all had acute plasmodium falciparum malaria. the children were kept in hospital for 5 days, and regularly followed over a 15-day period. the 50 children were cured and efficacy was evaluated as good in 44 cases, and excellent in six cases, as judged b ... | 1992 | 1573696 |
| an examination of the mitomycin c induction of chromosome polymorphisms in cultures of plasmodium falciparum. | cloned parasites of the fcr3 strain of plasmodium falciparum that survived treatment with either mitomycin c or ethidium bromide were grown and subcloned. the chromosomes of 10 cloned isolates from each population were analysed by contour-clamped homogenous electric field gel electrophoresis. eight of 10 isolates from the mitomycin c-treated population contained a detectable polymorphic chromosome change while none of the isolates from the ethidium bromide-treated population did. one of the poly ... | 1992 | 1574078 |
| mapping of the region predominantly recognized by antibodies to the plasmodium falciparum merozoite surface antigen msa 1. | the locations of the epitopes of a panel of mouse monoclonal antibodies directed against the plasmodium falciparum merozoite surface antigen msa 1 were mapped by using naturally occurring processed fragments, by chemical cleavage of the protein and by comparison of the isolate-specificity of binding with known sequence variation. by these criteria, the most antigenic region occurs in the cysteine-rich, invariant 19-kda carboxyl terminal domain with 12/19 monoclonal antibodies (mabs) binding to t ... | 1992 | 1574088 |
| the sequence of the p82 rhoptry protein is highly conserved between two plasmodium falciparum isolates. | | 1992 | 1574089 |
| purification and in vitro selection of rosette-positive (r+) and rosette-negative (r-) phenotypes of knob-positive plasmodium falciparum parasites. | we have developed methods for in vitro selection of plasmodium falciparum parasites that bear knob protrusions (k+) and are either of the rosette-positive (k+r+) or rosette-negative (k+r-) phenotypes. cryopreserved parasites from spleen-intact aotus monkeys that were k+, c32 cell adherence-positive (c+), cd36 adherence-positive, and r- with aotus erythrocytes were adapted to continuous growth in human erythrocytes, and selected initially for adherence to c32 melanoma cells. in the absence of ind ... | 1992 | 1575284 |
| a simple method to detect plasmodium falciparum directly from blood samples using the polymerase chain reaction. | we have developed a simple method for treating blood samples permitting direct detection of plasmodium falciparum parasites using the p. falciparum-specific dna probe ppf14 after polymerase chain reaction (pcr) amplification of target dna sequences, and have compared this method with microscopic examination of thick blood smears. for pcr amplification, blood samples were lysed, then filtered onto filter paper. after drying, a piece of the filter paper was added directly to the pcr mixture for am ... | 1992 | 1575288 |
| antimalarial activity of new dihydroartemisinin derivatives. 5. sugar analogues. | a series of dihydroartemisinin derivatives containing a sugar moiety was prepared in the search for analogues with good water solubility and high antimalarial activity. the preparation of the new compounds was achieved by treatment of dihydroartemisinin (2) with chlorotrimethylsilane in pyridine solution at -10 degrees c to give a nearly quantitative yield of 10-o-(trimethylsilyl)dihydroartemisinin (3), which was then condensed with 1-hydroxypolyacetylated sugars 5 to give dihydroartemisinin der ... | 1992 | 1578492 |