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[malaria after a stay in guadeloupe]. 19902146657
[failure of chemoprevention with mefloquine in western africa]. 19902146671
[a case of plasmodium falciparum malaria contracted in guinea-bissau during chemoprophylaxis with chloroquine]. 19902147276
accumulation of chloroquine by membrane preparations from plasmodium falciparum.chloroquine susceptibility and resistance have been associated respectively with the uptake and efflux of chloroquine by plasmodium falciparum. we made membrane preparations from parasitized and unparasitized red cells in order to study chloroquine accumulation in a cell-free system. the accumulation of [3h]chloroquine by these preparations is inhibited by unlabeled chloroquine and thus is specific. only membranes from parasitized red cells demonstrate time-dependent chloroquine accumulation; me ...19902148609
[resolutive and recurrent oligohydramnios caused by plasmodium falciparum malaria]. 19902148621
increased gamma delta t cells in acute plasmodium falciparum malaria.the t cell receptor of gamma delta is normally expressed on a small percentage of peripheral lymphocytes. although the role of gamma delta t cells in the physiologic immune response is still unknown, there is accumulating evidence that gamma delta t cells may participate in the immune response to mycobacterial and other infectious organisms. in this study, we have quantitated the number of circulating gamma delta t cells during acute plasmodium falciparum malaria. the results indicate that gamma ...19902149360
in vitro cell-mediated immune responses to plasmodium falciparum schizont antigens in adults from a malaria endemic area: cd8+ t lymphocytes inhibit the response of low responder individuals.plasmodium falciparum schizont extract and purified protein derivative were used to stimulate peripheral blood mononuclear cells obtained from healthy aparasitemic gabonese individuals with lifelong exposure to malaria infection and non-gabonese control subjects who have had had no clinical malaria. in vitro lymphoproliferation was measured by uptake of tritiated thymidine, while production of interleukin-2, interferon-gamma, and soluble cd8+ were measured by immunoenzymatic assays. enumeration ...19902151024
hepatic phase of malaria: a crucial role as "go-between" with other stages.besides potential interest in itself, the hepatic stage of malaria might play a crucial role as "go-between" with other stages. when present in the parasitophorous vacuole, antibodies induced by both sporozoite and erythrocytic stages efficiently disturb hepatic development of the parasite. likewise previous and ensuing erythrocytic stages can modulate the "shielded" phase by cytokines, directly or as a result of a cascade of events, and by mhc-restricted or antibody-dependent cytotoxic mechanis ...19902151269
recommendations for the prevention of malaria among travelers.recommendations for the prevention of malaria among travelers have been developed by cdc in consultation with representatives from the offices of medical services of the department of state and the peace corps; the division of experimental therapeutics of the walter reed army institute of research; the office of the surgeon general, u.s. army; the office of the surgeon general, u.s. air force; and the bureau of medicine and surgery, u.s. navy. resistance of plasmodium falciparum to chloroquine h ...19902156146
recrudescence of entopolypoides macaci mayer, 1933 (babesiidae) infection secondary to stress in long-tailed macaques (macaca fascicularis).parasites were found in red blood cells of two long-tailed macaques (macaca fascicularis) imported from indonesia and housed in the washington regional primate research center breeding colony for 7 years or longer. both macaques developed parasitemias secondary to stress (type d retrovirus in one case and severe trauma in the other). entopolypoides macaci (babesiidae) was diagnosed on the basis of morphology from peripheral blood smears stained with wright's stain. antibodies against babesia sp. ...19902157097
phospholipid composition, cholesterol content and cholesterol exchange in plasmodium falciparum-infected red cells.the membrane lipid composition and [3h]cholesterol exchange rate were studied in both normal human erythrocytes and those infected with the human malaria plasmodium falciparum. the host cell membrane was separated from parasite membranes using the affigel (731) bead method. the purity of the membrane preparation was very high, as judged by sds-page, and in several instances was estimated to be greater than 98% as determined by the activity of the parasite membrane-specific enzyme, choline phosph ...19902157152
[malaria tropica with activation of blood coagulation and detection of tumor necrosis factor (nf-alpha) in serum].a 38-year-old patient with cerebral p. falciparum malaria was admitted 12 days after a short trip to kenya. the serum level of tumor necrosis factor (tnf-alpha) was elevated (251 pg/ml). in contrast, protein c (plasma activity 36.1%; antigen concentration 31.7%) and protein c inhibitor 1 (activity 0.55 u/ml) levels were decreased. this suggested a state of functional activation of the clotting system which was confirmed by elevated levels (4.8 ng/ml) of circulating thrombin-antithrombin-iii-comp ...19902157919
from the centers for disease control. recommendations for the prevention of malaria among travelers.recommendations for the prevention of malaria among travelers have been developed by cdc in consultation with representatives from the offices of medical services of the department of state and the peace corps; the division of experimental therapeutics of the walter reed army institute of research; the office of the surgeon general, u.s. army; the office of the surgeon general, u.s. air force; and the bureau of medicine and surgery, u.s. navy. resistance of plasmodium falciparum to chloroquine h ...19902159078
[uncommon clinical aspects of plasmodium falciparum malaria].an attack of malaria can be lethal; however, besides this classic form, clinical cases are less brutal, often with blood disorders, related to plasmodium falciparum infection resistant to chloroquine. because of the importance of chloroquinoresistance through the world, chemoprophylaxis is very difficult, and the fight against mosquitoes' bites is once again very important.19902165242
antimalarial activity of diethyldithiocarbamate. potentiation by copper.the antimalarial activity of diethyldithiocarbamate (ddc) in vitro was potentiated by subtoxic concentrations of copper. ddc was also more potent in the presence of an intracellular source of copper, such as when parasites were grown in superoxide dismutase (sod)-loaded erythrocytes. these data suggest that ddc forms a complex with copper, either intracellularly or extracellularly, which is toxic to malarial parasites. the exact cause of this toxicity is not known, but may be due to a membrane e ...19902165401
in vitro analysis of epstein-barr virus: host balance in patients with acute plasmodium falciparum malaria. i. defective t-cell control.peripheral blood lymphocytes from healthy, epstein-barr virus (eb-virus)-seropositive donors and from patients with acute plasmodium falciparum malaria were tested for their cytotoxicity towards autologous eb-virus-infected b-cells using an in vitro regression assay. of the 18 cultures from control donors, 88.8% showed the normal pattern of regression. of the 20 malaria patients in the study, 40% failed to exhibit the normal pattern observed in the control group. analysis of the lymphocyte subse ...19902166284
[in-vivo evaluation of plasmodium falciparum sensitivity to chloroquine in abidjan].in vivo tests of plasmodium falciparum chloroquine sensitivity were conducted in october and november, 1988 with 81 children aged 5 to 9 in several districts of abidjan, ivory coast. the who standard scheme covering 7 days on basis of 25 mg per kilo spread over 3 days resulted in a therapeutic failure in 29.6 per cent cases. nevertheless, a drop in overall parasitemia by over 80 per cent was noted from day-0 to day-2 in 70 per cent of visible resistance. only in vivo tests conducted at a later s ...19902170042
[prophylaxis of malaria. current need for awareness of risk]. 19902170904
effect of mitochondrial inhibitors on adenosinetriphosphate levels in plasmodium falciparum.1. the effects of mitochondrial inhibitors on the atp levels of intraerythrocytic plasmodium falciparum have been studied. 2. changes in parasite atp or adp levels with time in response to various mitochondrial inhibitors appear quite complex; atp levels may be initially depressed and then elevated above normal, but the nature of the response depends upon the stage in the intraerythrocytic cycle and in some cases upon the concentration of the inhibitor used. 3. after ca 2 hr incubation of cultur ...19902171868
possible roles of ca2+ and cgmp as mediators of the exflagellation of plasmodium berghei and plasmodium falciparum.the roles of ca2+ and cyclic nucleotides as secondary, intracellular messengers for exflagellation of plasmodium berghei and plasmodium falciparum were investigated. treatment with ca2+ antagonists such as tmb-8 (an inhibitor of intracellular ca2+ release) or w-7 (a calmodulin inhibitor) strongly inhibited exflagellation induced by alkaline medium at ph 8.0 whereas egta (a ca2+ chelator) or nicardipine and nifedipine (ca2+ channel inhibitors) had no effect. these results may indicate that mobili ...19902172816
ion metabolism in malaria-infected erythrocytes.malaria parasites of the genus plasmodium spend much of their asexual life cycle inside the erythrocytes of their vertebrate hosts. parasites presumably have to exploit metabolic and transport mechanisms to adapt themselves to the host erythrocyte's physicochemical environment. this review surveys the metabolism and transport of ca2+, alkali cations, and h+ in malaria-infected erythrocytes. the ca2+ content of plasmodium-infected erythrocytes increases as the parasite matures. an increase in the ...19902175223
activity of human volunteer sera to candidate plasmodium falciparum circumsporozoite protein vaccines in the inhibition of sporozoite invasion assay of human hepatoma cells and hepatocytes.sera from human volunteers immunized with either synthetic peptide (nanp)3-tt or recombinant protein r32tet32 plasmodium falciparum cs vaccines were tested in the inhibition of sporozoite invasion (isi) assays using human hepatoma (hepg2-a16) cells or primary human hepatocytes. sera or purified immunoglobulin (ig) from volunteers who were completely protected against p. falciparum sporozoite challenge had higher isi activity than sera from non-protected volunteers, or the highest titre endemic s ...19902175464
heterologous expression of active thymidylate synthase-dihydrofolate reductase from plasmodium falciparum.the coding sequence of the bifunctional thymidylate synthase-dihydrofolate reductase (ts-dhfr) from a moderately pyrimethamine-resistant strain (hb3) of plasmodium falciparum was assembled in a puc expression vector. the coding sequence possesses unique nco1 and xba1 sites which flank 243 bp of the dhfr gene that include all point mutations thus far linked to pyrimethamine resistance. wild-type (3d7) and highly pyrimethamine-resistant (7g8) ts-dhfrs were made from this vector by cassette mutagen ...19902176883
the circulating platelet in acute malaria infection. 19902178670
thymidylate synthase-dihydrofolate reductase in protozoa.in protozoa, thymidylate synthase (ts) and dihydrofolate reductase (dhfr) exist on the same polypeptide. the dhfr domain is on the amino terminus, ts is on the carboxy terminus, and the domains are separated by a junction peptide of varying size depending on the source. the native protein is a dimer of two such subunits and is 110-140 kda. most studies of bifunctional ts-dhfr have been performed with the protein from anti-folate resistant strains of leishmania major, which show amplification of ...19902178951
malaria and glucose 6-phosphate dehydrogenase deficiency in populations with high and low spleen rates in madang, papua new guinea.previous studies in madang have demarcated 2 groups of women, one with high spleen rates (hs group) and the other with low spleen rates (ls group). an association between glucose 6-phosphate dehydrogenase (g6pd) deficiency and low spleen rates was investigated in 196 hs and 106 ls group men. prevalence was 12.2 and 9.4%, respectively. parasite and spleen rates were lower in deficients in the hs group. differences in prevalence between hs group villages were observed which may be related to the i ...19902179119
impairment of plasmodium falciparum-specific antibody response in severe malaria.serum antibody response to plasmodial antigens was investigated in 97 thai patients with plasmodium falciparum malaria. no difference in immunoglobulin g (igg) antibody levels was detected between groups without or with cerebral manifestations of malaria (n = 40). in patients with the most severe form of the disease, i.e., those who died despite adequate therapy (n = 12), antibody detected in the immunofluorescent-antibody test was found at lower levels than in those who recovered (geometric mea ...19902179259
splenic fc receptor function in host defense and anemia in acute plasmodium falciparum malaria.to determine splenic fc receptor function in patients with acute plasmodium falciparum malaria, the clearance of igg-coated autologous 51cr-labeled erythrocytes in 20 patients and 10 normal controls was studied. clearance half-times were directly correlated with both the absolute parasite count (r = .635, p less than .005) and hematocrit (r = .791, p less than .001). clearance half-times in patients varied from 1.0 to 96.3 h (median, 14.8 h) while those of controls ranged from 8.0 to 80.3 h (med ...19902179426
fatal plasmodium falciparum malaria after an inadequate response to quinine treatment.a 24-year-old man with severe plasmodium falciparum malaria died after 77 h of treatment with full parenteral doses of quinine. his peripheral parasitemia at death exceeded the level on admission. plasma concentrations of quinine were abnormally low throughout. this case emphasizes the importance of pharmacokinetic factors in determining the therapeutic response in severe p. falciparum malaria.19902179427
changes in plasma lipoproteins in acute malaria.plasma lipid and lipoprotein concentrations were monitored in 16 patients with acute malaria. plasma high density lipoprotein (hdl) levels decreased dramatically during the first 3 d after diagnosis to around 0.2 mmol l-1 (reference range 0.8-1.6 mmol l-1). the low hdl levels were related to parasitaemia, and rapidly recovered after successful therapy. plasma triglyceride concentrations were moderately increased and plasma low density lipoprotein (ldl) cholesterol concentrations decreased during ...19902179459
human and murine macrophages produce tnf in response to soluble antigens of plasmodium falciparum.heat-stable antigens of rodent malarial parasites induce the release of tumour necrosis factor (tnf) from mouse macrophages, in vitro and in vivo. we report here that analogous antigens of plasmodium falciparum trigger the release of tnf from human monocytes in vitro, in conditions that exclude the effects of any contaminating endotoxin. these antigens also induced tnf release from a murine monocytic cell line and from the peritoneal macrophages of several strains of mice, including the lps-hypo ...19902179828
stage-specific gametocytocidal effect in vitro of the antimalaria drug qinghaosu on plasmodium falciparum.qinghaosu, an anti-malaria drug, has been found to kill not only asexual blood stages but also the early stages of gametocytes of plasmodium falciparum. the effect of qinghaosu in vitro depends on the concentration of the drug as well as on the initial parasitemia level (ic50 = 10-20 nm with 1% initial parasitemia). resistance of p. falciparum to other anti-malaria drugs, e.g., chloroquine and pyrimethamine, did not affect susceptibility of its asexual and sexual stages to qinghaosu. gametocytoc ...19902179946
chemotherapy: principles in practice--a case study of the philippines.this paper reports on the principles that form the basis of chemotherapy and examines the operational considerations that affect their practice in a developing country like the philippines, where malaria endemicity is synonymous with difficult topography, poor public health infrastructure, and alternative means of obtaining medication. the practice of using microscopic diagnosis for radical treatment is followed routinely and uniformly. where policy dictates that all fever cases be screened, the ...19902180084
bifunctional thymidylate synthase-dihydrofolate reductase in protozoa.protozoa contain thymidylate synthase (ts) and dihydrofolate reductase (dhfr) on the same polypeptide. in the bifunctional protein, the dhfr domain is on the amino terminus, ts is on the carboxyl terminus, and the two domains are separated by a junction peptide of varying size depending on the source. the native protein is composed of a dimer of two such subunits and is 110-140 kda. most studies of the bifunctional ts-dhfr have been performed with the protein from anti-folate resistant strains o ...19902180768
immunogenicity and antigenicity in rabbits of a repeated sequence of plasmodium falciparum antigen pf155/resa fused to two immunoglobulin g-binding domains of staphylococcal protein a.a synthetic gene encoding a tetramer of the repeated subunit eenvehda of the plasmodium falciparum antigen pf155/resa was expressed in a dual-expression system. the resulting fusion proteins, designated zz-m1 and bb-m1, comprised the eenvehda repeats and either two immunoglobulin g-binding domains from staphylococcal protein a or the human serum albumin-binding domains from streptococcal protein g, respectively. the soluble fusion proteins were affinity purified to homogeneity in one-step proced ...19902180822
falciparum malaria: the current status of antimalarials in therapy and prophylaxis. 19902180891
clindamycin in malaria treatment. 19902180893
the distribution of circumsporozoite protein (cs) in anopheles stephensi mosquitoes infected with plasmodium falciparum malaria.we monitored the distribution of plasmodium falciparum circumsporozoite protein (cs) in anopheles stephensi using an immunohistochemical method. an alkaline phosphatase-labeled monoclonal antibody, specific for the cs protein of p. falciparum, was incubated with tissue sections from infected and non-infected mosquitoes. sections were stained for phosphatase activity using a new fuchsin/naphthol as-bi phosphate capture system. distribution of the cs protein in mosquitoes was dependent on the time ...19902181019
malaria in leicester 1983-1988: a review of 114 cases.we have reviewed 114 episodes of malaria in 110 patients who were admitted to the infectious diseases unit in leicester during the 5 year period from february 1983-january 1988. there were 71 episodes of vivax malaria (62%), 33 episodes of falciparum malaria (29%), four patients with mixed infection and six patients with negative blood films who were diagnosed on clinical suspicion alone. most patients presented in the summer months, 68% were aged under 40 years, 39% were born in the indian subc ...19902181023
heterogeneity and expression of the plasmodium falciparum 5.8s ribosomal rna genes.the number and expression of some of the large ribosomal rna (rrna) gene classes present in the human malaria parasite plasmodium falciparum was determined. southern blot analyses, using the 5.8s rrna coding region as a marker, indicate that the p. falciparum genome contains at least 5 distinct subclasses of large rrna genes. dideoxy sequencing of the 5.8s rrna domain and northern blot analyses demonstrate that only one subclass is transcribed during the parasite's asexual erythrocytic life cycl ...19902181300
conformation and immunogenicity of engineered repeating segment of the circumsporozoite surface protein of plasmodium falciparum.peptide vaccines based on units of the immunodominant tetrapeptide repeats, asn-ala-asn-pro and asn-val-asp-pro, of the circumsporozoite surface protein of the parasite plasmodium falciparum are presently being developed as potential malaria vaccines. the n-terminal fusion of a hydrophobic protein to units of the tetrapeptide repeat affected the immunogenicity and conformational stability of the peptide, and also induced a secondary structure in the peptide. peptide antigenicity, as well as conf ...19902181302
expression, partial purification and immunogenicity of fragments of the knob protein of plasmodium falciparum.three structural domains of the histidine-rich knob protein (kp) of plasmodium falciparum were expressed in escherichia coli. a single-step purification scheme was devised to obtain great enrichment of expressed polypeptides for use in subsequent experiments. immune human sera from africa, south-east asia and south america were tested for reactivity with each of the expressed fragments. while the two fragments which represented the central and c-terminal regions of kp showed a strong reactivity ...19902181305
isolation of alpha- and beta-tubulin genes of plasmodium falciparum using a single oligonucleotide probe.an oligonucleotide probe (315) specific for the alpha- and beta-tubulin genes of plasmodium falciparum was synthesized utilizing codon usage of p. falciparum determined from published gene sequences. by screening genomic and cdna libraries with the oligonucleotide probe, alpha- and beta-tubulin clones were isolated. positive clones were identified by partial sequencing and comparing the deduced amino acid sequence with the chicken brain alpha- and beta-tubulin amino acid sequences. the beta-tubu ...19902181306
structural diversity in the 45-kilodalton merozoite surface antigen of plasmodium falciparum.an integral membrane protein associated with the merozoite surface of plasmodium falciparum termed merozoite surface antigen 2 (the 45-kda merozoite surface antigen), occurs in antigenically diverse forms. here we report the sequences of the msa 2 gene from two other isolates of p. falciparum. the 43 n-terminal residues and the 74 c-terminal residues of all three msa 2 sequences are highly conserved, but between these conserved regions there are dramatic differences among the alleles. instead of ...19902181307
detection of pyrimethamine resistance in plasmodium falciparum by mutation-specific polymerase chain reaction.the point mutation at nucleotide 323 within the dihydrofolate reductase-thymidylate synthase gene of plasmodium falciparum, which distinguishes pyrimethamine-sensitive from drug-resistant isolates, can be discriminated by the polymerase chain reaction using mutation-specific primers. the technique makes use of the principle that short oligonucleotides with a perfect match at their 3' ends, complementary to the mutation to be detected, will initiate the polymerization by taq polymerase far more e ...19902181308
apical membrane antigen of plasmodium fragile. 19902181309
consecutive determinations of seroreactivities to pf 155/resa antigen and to its different repetitive sequences in adult men from a holoendemic area of liberia.sera from 32 adult men residing in a malaria holoendemic area of liberia were investigated for seroreactivities to different asexual blood-stage malaria antigens on five consecutive occasions from 1984 to 1986. the seroreactivities to crude parasitic antigens and to pf 155/resa (emif) were determined by immunofluorescence and to repetitive sequences of pf 155/resa by enzyme-linked immunosorbent assay (elisa). all sera were highly reactive against the crude parasitic antigens with reciprocal titr ...19902181384
malaria in children.fifty-four cases of malaria in children seen during an 11-year period are described. there have been more cases seen in recent years, and the proportion of plasmodium falciparum malaria has increased. compliance with chemoprophylaxis is poor, but compliance does not guarantee protection. malaria is the primary diagnostic consideration in any child recently returning from an endemic area who presents with fever. two cases are described.19902181413
genetic diversity in plasmodium falciparum. 19902181830
antimalarial action of flavin analogues seems not be due to inhibition of glutathione reductase of host erythrocytes.a series of 10-(4'-chlorophenyl)-3-substituted flavins (1a-f) were examined with respect to their antimalarial properties. they were tested against plasmodium falciparum in vitro and plasmodium vinckei vinckei in vivo. the proposition that they might act through glutathione reductase (gr) (ec 1.6.4.2) inhibition has been studied. inhibition of p. falciparum in vitro by these compounds shows only slight variation between analogues; in contrast, inhibition of human erythrocyte gr by members of the ...19902182031
[analysis of causes of malaria outbreaks in yunnan province, 1981-1985].the incidence of malaria in yunnan province has decreased year by year in recent years. however, focal outbreaks in small scale still occurred every year. the average morbidity in villages with outbreaks was 15.22-70.82%, and the plasmodium positive rate 6.36-34.69%, in which the percentage of plasmodium falciparum 34.55-63.63%. the main cause of outbreaks was the existence of residual source of malaria infection and the concomitance of high density of anopheles. eradication of the vector and er ...19902182195
immune response in patients during and after plasmodium falciparum infection.the kinetics of indicators of lymphocyte activation were determined in non- and semiimmune patients with uncomplicated plasmodium falciparum infection and in control subjects in acre, brazil. delayed type hypersensitivity (dth) to seven recall antigens was weakest in nonimmune patients. both patient groups differed significantly from controls on admission (p less than .001 for both) and improved considerably after clindamycin therapy. total serum igg and igm, but not antimalarial antibodies, wer ...19902182725
malaria prophylaxis in travellers to tropical africa.this study investigated travellers to tropical africa with regard to prophylactic treatment of malaria. a total of 5703 travellers completed a questionnaire on their flights back to the federal republic of germany; 4116 passengers (73.7%) had visited east africa, while 808 (14.5%) had been to west africa. the results indicate that 90.2% took a regular chemoprophylaxis against malaria. nevertheless, 8.1% of the travellers used no antimalarials and in 9.3% chemoprophylaxis was inadequate due to in ...19902182940
purification and characterization of 37-kilodalton proteases from plasmodium falciparum and plasmodium berghei which cleave erythrocyte cytoskeletal components.cytosoluble 100,000 x g extracts from plasmodium berghei or plasmodium falciparum infected red blood cells were shown to hydrolyze erythrocyte spectrin. by fast protein liquid chromatography (fplc), these enzymes were purified and exhibited a pi of 4.5 and mr of 37,000 using sds-page under reducing conditions. an immunochemical enzyme assay using anti-spectrin antibodies was developed. the optimal activity using spectrin as substrate was at ph 5.0, and the enzymes were strongly inhibited by hgcl ...19902183048
the mature-parasite-infected erythrocyte surface antigen (mesa) of plasmodium falciparum associates with the erythrocyte membrane skeletal protein, band 4.1.several proteins synthesized by mature asexual stages of plasmodium falciparum interact with the erythrocyte membrane skeleton. one of these is the mature-parasite-infected erythrocyte surface antigen (mesa; also called pfemp2), a phosphoprotein of 250-300 kda, which is found on the internal face of the erythrocyte membrane. when mesa is precipitated with anti-mesa antibodies, another phosphoprotein of 80 kda is co-precipitated. this 80-kda phosphoprotein was identified by peptide mapping as the ...19902183050
homologous sequences in plasmodium cynomolgi and the gene of the histidine-rich knob protein of plasmodium falciparum. 19902183051
hemoglobin degradation in the malaria parasite plasmodium falciparum: an ordered process in a unique organelle.the malaria parasite plasmodium falciparum uses host erythrocyte hemoglobin as a major nutrient source. we report the purification of p. falciparum digestive vacuoles and characterization of the degradative process therein. vacuoles were isolated by a combination of differential centrifugation and density gradient separation. the pure vacuoles were capable of degrading hemoglobin to small fragments with a ph optimum of 5-5.5. proteolysis in the vacuoles appears to be an ordered process, requirin ...19902183218
use of a tuberculin purified protein derivative--asn-ala-asn-pro conjugate in bacillus calmette-guérin primed mice overcomes h-2 restriction of the antibody response and avoids the need for adjuvants.because of its immunodominancy, and because it is conserved in different geographical isolates of plasmodium falciparum, the repetitive sequence of the circumsporozoite protein, (asn-ala-asn-pro)n [(nanp)n], has been envisaged for the development of an anti-falciparum malaria subunit vaccine. however, the murine immune response to (nanp)n peptides, either carrier-free or coupled to carrier proteins, was shown to be inducible only by using strong (e.g., freund's) adjuvants. furthermore, response ...19902183219
amino acids in the dihydrofolate reductase-thymidylate synthase gene of plasmodium falciparum involved in cycloguanil resistance differ from those involved in pyrimethamine resistance.cycloguanil, the active metabolite of the antimalarial drug proguanil, is an inhibitor of dihydrofolate reductase as is another antimalarial, pyrimethamine. its use has been limited by the rapid development of resistance by parasites around the world. we have determined the cycloguanil- and pyrimethamine-sensitivity status of 10 isolates of plasmodium falciparum and have sequenced in all these isolates the dihydrofolate reductase (dhfr; 5,6,7,8-tetrahydrofolate: nadp+ oxidoreductase, ec 1.5.1.3) ...19902183221
molecular basis of differential resistance to cycloguanil and pyrimethamine in plasmodium falciparum malaria.proguanil and pyrimethamine are antifolate drugs with distinct chemical structures that are used commonly in the prophylaxis and treatment of plasmodium falciparum malaria. clinical reports and field studies have suggested that some parasites refractory to proguanil can be treated with pyrimethamine, and vice versa. analysis of the p. falciparum dihydrofolate reductase (dhfr) from different parasites reveals the structural basis for differential susceptibility to these antifolate drugs. parasite ...19902183222
increased nicotinamide adenine dinucleotide content and synthesis in plasmodium falciparum-infected human erythrocytes.plasmodium falciparum-infected red blood cells (rbcs) are characterized by increases in the activity of glycolytic enzymes. because nicotinamide adenine dinucleotide (nad) and nad phosphate (nadp) are cofactors in the reactions of glycolysis and pentose phosphate shunt, we have examined nad and nadp content in p. falciparum-infected rbcs. although nadp content was not significantly altered, nad content was increased approximately 10-fold in infected rbcs (66% parasitemia) compared with uninfecte ...19902183889
prevention of malaria.with the increased spread of chloroquine-resistant plasmodium falciparum malaria and mounting evidence of lack of efficacy and toxicity of alternative drugs, it has become extremely difficult to propose simple, widely applicable and uniformly acceptable recommendations for malaria chemoprophylaxis. with regard to specific drugs, it is clear that because of its toxicity amodiaquine should no longer be used for chemoprophylaxis, and that pyrimethamine/sulfadoxine should, for the most part, be used ...19902184005
initiation of translation at a uag stop codon in the aldolase gene of plasmodium falciparum.the gene coding for the key glycolytic enzyme fructose-1,6-diphosphate aldolase of the human malaria parasite plasmodium falciparum lacks a functional aug initiation codon for translation. protein sequences of natural or in vitro translated aldolase include the candidate start methionine residue at internal positions. no additional aug start codon is found in genomic dna, cdna or mrna sequences. instead, a uag chain termination codon is recognized as the start signal of protein synthesis in vivo ...19902184034
[nutritional status in children under 6 years of age and its relation to malaria and intestinal parasitism].in order to determine the prevalence of the nutritional situation in children under six years of age and to study the relation with malaria and intestinal parasitism an epidemiological study of a cross sectional was carried out in cordoba locality, buenaventura municipality in the colombian pacific coast. one hundred and twenty eight children were studied to whom a questionnaire, a thick smear examination, and a serological test through the indirect immunofluorescence reaction was practiced. cop ...19902184526
characteristics of malaria transmission in kataragama, sri lanka: a focus for immuno-epidemiological studies.parasitological and entomological parameters of malaria transmission were monitored for 17 months in 3,625 residents in a plasmodium vivax malaria endemic region in southern sri lanka; the study area consisted of 7 contiguous villages where routine national malaria control operations were being conducted. malaria was monitored in every resident; fever patients were screened and 4 periodical mass blood surveys were conducted. an annual malaria incidence rate of 23.1% was reported during the perio ...19902184688
a rapid sporozoite elisa using 3,3',5,5'-tetramethylbenzidine as the substrate chromogen.a modified version of the standard 2-site sporozoite enzyme-linked immunosorbent assay (elisa) using 3,3',5,5'-tetramethylbenzidine (tmb) as the substrate chromogen solution was adapted for rapid detection and identification of plasmodium falciparum and p. vivax circumsporozoite (cs) proteins. the tmb-elisa was evaluated using sporozoites from experimentally infected mosquitoes and laboratory colonized uninfected mosquitoes. our data indicate comparable sensitivity levels between the tmb-elisa a ...19902184690
failure of chloroquine prophylaxis for falciparum malaria in pregnant women in madang, papua new guinea.six hundred and twenty pregnant women, living under conditions of year-round transmission of malaria in a rural coastal area of madang, papua new guinea (png), were followed while attending mobile antenatal clinics and receiving chloroquine prophylaxis (300 mg base weekly). whole blood chloroquine concentrations measured by elisa from samples collected at delivery indicated a high level of drug compliance in regular attenders. susceptibility is increased in primigravidae to plasmodium falciparum ...19902184784
consequences of maternal anaemia on outcome of pregnancy in a malaria endemic area in papua new guinea.the prevalence of anaemia during pregnancy was investigated in relation to parasite and spleen rates of pregnant women living in a defined study area in rural madang, papua new guinea. the effects in pregnancy of anaemia, iron deficiency and malaria on the foetus were investigated. there is a high prevalence of anaemia in this population, with 44% of primigravidae and 29% of multigravidae having severe anaemia [haemoglobin (hb) less than 8 g dl-1] after 28 weeks gestation. the odds ratio for sev ...19902184786
infectivity of gametocytes of plasmodium falciparum and plasmodium vivax after storage in vitro. 19902184788
pulmonary edema in severe falciparum malaria. hemodynamic study and clinicophysiologic correlation.this study was performed to extend the knowledge of the pathogenesis of pe in severe falciparum malaria. sequential hemodynamic studies were conducted in 13 patients with severe falciparum malaria. seven patients developed pe, while the other six patients had npe. two patients died, one in each group. hemodynamic changes were found in both groups, including an initial reduction in svr and pvr, along with an increased ci and variable values (normal and increased) of pcwp. all abnormalities persis ...19902184996
in vitro responses of human peripheral blood mononuclear cells to plasmodium falciparum antigen.immunity to malaria involves cell-mediated and humoral responses. the cell-mediated reaction is thought to focus particularly on the activity of cells of the macrophage lineage. the ability of antigen-stimulated human peripheral blood lymphocytes to undergo proliferation and produce factors capable of causing macrophage inhibition of parasite growth has been examined. while lymphocyte proliferation, gamma-interferon production, and anti-malarial antibody levels of malaria-exposed papua new guine ...19902185169
malaria sporozoite detection by dissection and elisa to assess infectivity of afrotropical anopheles (diptera: culicidae).malaria infection rates determined by dissection and plasmodium falciparum enzyme-linked immunosorbent assay (elisa) were compared for 26,935 anopheles gambiae giles sensu lato and 17,739 anopheles funestus giles collected during 20 mo in western kenya. elisa infection rates were about 43% higher than dissection sporozoite rates. in dissection-negative anopheles, circumsporozoite (cs) protein was detected by elisa in 5.2% of 10,017 salivary gland samples and in 12.2% of 237 thorax samples. the a ...19902185363
long struggle continues to find new weapons against an old foe--the malaria parasite. 19902185370
malaria: the path of drug resistance. 19902185423
several alleles of the multidrug-resistance gene are closely linked to chloroquine resistance in plasmodium falciparum.the lethal form of human malaria caused by plasmodium falciparum is virtually uncontrollable in many areas because of the development of drug resistance, in particular chloroquine resistance (cqr). cqr is biologically similar to the multiple drug resistance phenotype (mdr) of mammalian tumour cells, as both involve expulsion of drug from the cell and both can be reversed by calcium channel antagonists. a homologue (pfmdr1) of the mammalian multidrug resistance gene has been implicated in cqr bec ...19902185424
increased plasma lipid peroxidation in riboflavin-deficient, malaria-infected children.plasma lipid peroxides were measured as malonyldialdehyde (mda) by the thiobarbituric acid (tba) method in 75 children suffering from plasmodium falciparum malaria. their riboflavin status was assessed by measuring erythrocyte glutathione reductase activation coefficients (egracs), and values greater than 1.40 were regarded as indicating biochemical deficiency. plasma mda was higher (p less than 0.001) in patients than in control subjects; the concentrations were 3.65 +/- 0.70 and 1.77 +/- 0.45 ...19902185624
antimalarial activity of substituted anthraquinones. 19902186725
multiple-dose kinetics in healthy volunteers and in vitro antimalarial activity of proguanil plus dapsone.the multiple-dose kinetics of a daily dose of proguanil (200 mg) coadministered with dapsone (10 mg) was investigated in 6 healthy adult male volunteers. the kinetics of dapsone (dds), monoacetyldapsone (madds), proguanil (prog) and its active metabolite cycloguanil (cyclo) were derived from plasma drug concentrations after the last maintenance dose. the following kinetic parameters (mean values) were estimated for dds and prog, respectively: maximum concentration (cmax) = 285 and 151 ng/ml, min ...19902186899
antimalarial activity of the ethanol/alcohol oxidase system in vitro.among other macrophage secretory products, h2o2 plays an important role in the host's defense against malaria (wozencraft et al., infect. immun., 43, 664, (1984]. in our in vitro studies on the human malaria parasite plasmodium falciparum, hydrogen peroxide was produced by the alcohol oxidase-catalyzed reaction ethanol + o2----acetaldehyde + h2o2 (ec 1.1.3.13). at concentrations of 8.7 mm (= 0.5%) ethanol and 0.1 u alcohol oxidase per ml culture, more than 95% of the parasites were irreversibly ...19902186976
[antimalarial chemoprophylaxis in pregnancy].the drugs available for malaria chemoprophylaxis in pregnancy and their posology, side-effect in pregnant women and foetus are analyzed particularly for areas of high multidrug resistance. chloroquine and proguanil are the most used with few side-effects, while pyrimethamine is recommended only for chloroquine-resistant plasmodium falciparum spp.19902187165
immunization of aotus monkeys with plasmodium falciparum blood-stage recombinant proteins.the current spread of multidrug-resistant malaria demands rapid vaccine development against the major pathogen plasmodium falciparum. the high quantities of protein required for a worldwide vaccination campaign select recombinant dna technology as a practical approach for large-scale antigen production. we describe the vaccination of aotus monkeys with two recombinant blood-stage antigens (recombinant p41 and 190n) that were considered as vaccine candidates because parasite-derived antigen prepa ...19902187200
genetic diversity of plasmodium falciparum shows geographical variation.sixty plasmodium falciparum isolates, 20 each from thailand, zimbabwe, and brazil, were characterized for 20 variant genetic markers, including the enzymes glucose phosphate isomerase, adenosine deaminase and peptidase, 11 other proteins detected by 2-dimensional electrophoresis (2d-page), 2 merozoite surface antigens (msa-1 and msa-2), one exported antigen (exp-1), and sensitivity to the drugs chloroquine, pyrimethamine, and mefloquine. the study examines the extent of diversity between individ ...19902187364
a and t homopolymeric stretches mediate a dna inversion in plasmodium falciparum which results in loss of gene expression.ring-infected erythrocyte surface antigen-negative isolates of plasmodium falciparum demonstrate a complex dna rearrangement with inversion of 5' coding sequences, deletion of upstream and flanking sequences, and healing of the truncated chromosome by telomere addition. an inversion intermediate that results in the telomeric gene structure for resa has been identified in the pathway. this inversion creates a mitotically stable substrate for the sequence-specific addition of telomere repeats at t ...19902188111
papain and related proteins. 19902188140
continuation of chloroquine-susceptible plasmodium falciparum parasitemia in volunteers receiving chloroquine therapy.volunteers infected with a chloroquine-susceptible line of plasmodium falciparum were administered standard oral chloroquine therapy at the first detection of parasites in the blood. parasitemias progressed in the face of therapy for up to 5 days and to levels up to 100-fold greater than those at the initiation of treatment. thereafter, infections cleared without a requirement for additional chemotherapy. this course of infection and response to treatment has not been previously reported and may ...19902188591
pathophysiology of severe forms of falciparum malaria.we studied 26 patients with severe falciparum malaria who were admitted to an icu in namibia. the pathophysiologic effects on various organ systems are documented and the mortality associated with organ failure is reported. patients with three or more organ failures showed a high mortality, especially when pulmonary or renal failure occurred. predicted mortality based on the acute physiology and chronic health evaluation ii scoring system was 34% compared to an actual mortality of 38%.19902188791
immunopathological changes in kidney in plasmodium falciparum malaria.fifteen (34.8%) of 43 patients of falciparum malaria screened for urinary abnormalities showed significant proteinuria (greater than 150 mg/24 h), haematuria (greater than 1/hpf) and casts, with or without azotaemia. light microscopic examination of renal biopsy tissue from 12 patients revealed mesangial and endothelial proliferative change in 8, and acute tubular necrosis in one patient. immunofluorescence showed igm alone, or igg and igm along with c3, in 7 patients within the mesangium or alo ...19902188904
detection of early dividing forms of plasmodium falciparum in peripheral blood.p. falciparum schizonts were found in peripheral blood of six malaria patients including two infants who were moderately ill, with parasitaemia ranging from 33920 to 410800 per cubic mm. the patients lived in villages located at an altitude of 680 m and the phenomenon was observed during the cold season when transmission was high. appearance of these forms was independent of host age.19902188908
malaria vaccines.malaria continues to be a major worldwide problem. recent advances in our understanding of the parasite and the immune response to malarial infections has resulted in major advances in the progress toward an effective malaria vaccine. owing to the complexity of the parasite's life cycle, an effective vaccine will most assuredly contain components selected to stimulate potent immune mechanisms directed at various points in the parasite's life cycle. considering the increasing incidence of drug re ...19902189001
a safe and effective consecutive-infusion regimen for rapid quinine loading in severe falciparum malaria.recommended initial treatment of severe chloroquine-resistant falciparum malaria consists of a 4-h loading infusion of 20 mg of quinine dihydrochloride (salt)/kg of body weight. to achieve and maintain therapeutic blood quinine concentrations (10 mg/l) safely and rapidly, a consecutive-infusion regimen (7 mg of salt/kg of body weight over 30 min followed by 10 mg of salt/kg of body weight over 4 h) based on pharmacokinetic parameters in cerebral malaria has been suggested. this regimen was evalu ...19902189012
expression of hybrid malaria antigens in insect cells and their engineering for correct folding and secretion.hybrid proteins containing selected regions of the major surface antigens of the sporozoite and merozoite stages of plasmodium falciparum were expressed in insect cells using baculovirus vectors. a recombinant protein containing the signal peptide from the precursor to the major merozoite surface antigens (pmmsa) fused to a fragment from the carboxy (c) terminus of the same gene was recognized by monoclonal antibodies specific for reduction-sensitive conformational epitopes within the c-terminal ...19902189112
the effect of plasmodium falciparum exo-antigens on the morphology of uninfected erythrocytes.it was observed that uninfected red cells resuspended in supernatant from plasmodium falciparum cultures, then examined between a glass slide and cover-slip, assumed varying morphologies. a series of experiments suggested that p. falciparum releases molecules which cause red cells to become stomatocytic (cupped). these molecules, some of which are heat-stable have an apparent molecular weight greater than 12 kda, are released at or about schizogony, and do not bind tightly to erythrocytes.19902189113
commitment of the malaria parasite plasmodium falciparum to sexual and asexual development.blood-stage malaria parasites in the vertebrate host can develop either into the asexual, multiplying forms, called schizonts, or into gametocytes, the sexual stages of the parasite. in the present work we studied the differentiation into asexual parasites or gametocytes of the progeny of single, isolated schizonts of the clone 3d7a of plasmodium falciparum, using monoclonal antibodies specific for the sexual or asexual stages of the parasite. we observed that schizonts obtained from a continuou ...19902189114
a stable, oligosymptomatic malaria focus in thailand.blood from most of the 250 residents of a non-migratory farming village in south-eastern thailand was visually examined for malaria parasites monthly for 2 years. nearly 97% of the population had at least one (median = 5) patent plasmodium falciparum infection per year; 72% had one due to p. vivax (median = 1). this contrasted with a slide positivity rate of 17% calculated from 12 months of passive case detection before the study began. children 1-9 years old had the highest mean monthly prevale ...19902189235
highly efficient dry season transmission of malaria in thailand.man-biting collections were made for 7 consecutive nights per month for 24 months at 2 sites in a thai village regularly treated with ddt and fenitrothion yet hyperendemic for plasmodium falciparum and p. vivax. only anopheles dirus was incriminated as a vector: 1.6% were infective and 2.4% were infected (median numbers of oocysts = 3.5). transmission occurred within the village, which was located in groves of rubber and fruit trees, during the dry months of november to may only, when rates of p ...19902189240
seasonal fluctuation of plasmodium falciparum gametocytaemia.two numerically minor components of plasmodium falciparum prevalence--gametocytaemia and trophozoite densities greater than 99/500 white blood cells--displayed an annual cycle that reflected the seasonal abundance of infective anopheles dirus at a hyperendemic focus in thailand, even though the gross monthly prevalence for combined ages remained stable. gametocyte prevalence rose more than 300% within 30 d after the capture of the dry season's first infective mosquito, remained at about 8% until ...19902189241
malaria infection during pregnancy. 19902189243
the relationship between splenomegaly and antibody to the circumsporozoite protein of plasmodium falciparum in two groups of women with high and low enlarged spleen rates in madang, papua new guinea.the objective of this study was to determine the prevalence of antibodies recognizing the circumsporozoite (cs) protein of plasmodium by an enzyme-linked immunosorbent assay, in 2 subpopulations of women with significantly different enlarged spleen rates but similar exposure to malaria, on the north coast of papua new guinea. antibody levels of immunoglobulin g (igg) antibody to cs protein in the high and low spleen rate groups were similar (56.2% and 55.1%) but there was a significant differenc ...19902189244
sensitivity to chloroquine in vivo and in vitro of plasmodium falciparum in sokoto, nigeria. 19902189245
double-blind studies with mefloquine alone and in combination with sulfadoxine-pyrimethamine in 120 adults and 120 children with falciparum malaria in vietnam.in 120 adult vietnamese patients with uncomplicated falciparum malaria the efficacy of, and tolerance to, mefloquine (m) vs the combination of mefloquine + sulfadoxine + pyrimethamine (msp) was studied in a double-blind, randomized comparative trial with chloroquine. also, a double-blind dose finding study of msp was performed in 120 vietnamese children with uncomplicated falciparum malaria. in the adults the mean parasite clearance time with m was 3.8 d and with msp 3.6 d. defervescence occurre ...19902189246
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