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the chemotherapy of rodent malaria, xxiii causal prophylaxis, part ii: practical experience with plasmodium yoelii nigeriensis in drug screening.data are presented on the causal prophylactic action of about 100 compounds of various types against plasmodium yoelii nigeriensis n67 in mice. examples are given to show how action against pre-erythrocytic schizonts may be differentiated from action on emerging erythrocytic stages. in a series of 35 8-aminoquinolines, all but 10 showed definite causal prophylactic activity at tolerated doses. the data permit the compounds to be ranked in order of activity, and many are shown to be more active i ...19751098590
cytology and kinetics of microgametogenesis and fertilization in plasmodium yoelii nigeriensis.the sexual development of the microgametocyte of plasmodium yoelii nigeriensis may be subdivided into microgametogenesis which includes exflagellation, dispersal of the gametes and fertilization. under our experimental conditions microgametogenesis takes about 8-15 min at 20 degrees c, the duration of this period being inversely related to temperature. exflagellation takes less than 1 min, subsequent dispersal of gametes may continue for 40 min. we find that exflagellation is totally inhibited i ...19751118188
gametogenesis and fertilization in plasmodium yoelii nigeriensis: a transmission electron microscope study. 19764810
the action of metabolic inhibitors on microgametogenesis in plasmodium yoelii nigeriensis.mature gametocytes of plasmodium yoelii nigeriensis were incubated in vitro with a variety of antibiotics whose activities were directed against dna, rna, protein and microtubule assembly. following incubation for periods between 5 and 90 min, exflagellation was induced and the degree of inhibition produced by each drug was assayed microscopically. the results obtained show that de novo synthesis of axonemes and proteins is essential to the events of microgametogenesis. the inhibitory effect of ...1977919692
biochemistry of intraerythrocytic parasites. i. identification of enzymes of parasite origin by starch-gel electrophoresis.enzymes of parasite origin were identified by starch-gel electrophoresis. the species of parasite studied were plasmodium berghei, plasmodium yoelii nigeriensis, babesia rodhaini and anthemosoma garnhami. lactate dehydrogenase, glucose phosphate isomerase and (nadp) glutamate dehydrogenase were detected in all species; phosphogluconate dehydrogenase was detected in both plasmodium species but malate dehydrogenase only in p. y. nigeriensis. glucose-6-phosphate dehydrogenase, alanine aminotransfer ...1979386967
[new data on the circadian cycle of plasmodium. preliminary note].a frozen strain of plasmodium yoelii nigeriensis is inoculated at 4 pm, midnight and 9 am onto inbred mice. in all instances young gametocytes (type 0) appear in the blood only between 10 am and 6 pm. although the erythrocytic schizogony occurs regularly during the whole circadian period, the latency increases progressively when the infective subinoculations are made at midnight, 4 pm and 9 am. possibly, the infective merozoite can only enter the red blood cell around midnight.19806784953
absence of effects of insecticides on susceptibility of anophelines to plasmodium yoelii nigeriensis. 19826810475
vaccination to prevent transmission of plasmodium yoelii malaria.it was possible to block the transmission of infection of the rodent malaria parasite plasmodium yoelii nigeriensis to anopheles stephensi mosquitoes by immunizing mice with a vaccine containing formalin-fixed gametes. both intramuscular and intravenous routes were effective, immunity was achieved with a single dose and the immunity persisted for 6 months at least. transmission-blocking immunity was found to reside in a serum factor, probably antibody, and to be directed against extracellular ga ...19827070834
studies on the role of host serum in the retention of malarial sporozoites by isolated perfused rat liver.the binding of host serum components to malarial sporozoites has been proposed as a mechanism for the specific phagocytic uptake of these parasites, and hence the specificity of host infection (schulman et al., 1981). we therefore observed the kinetics of uptake of sporozoites of plasmodium yoelii nigeriensis and p. gallinaceum by isolated perfused rat livers in the presence of homologous or heterologous sera. in the homologous system (p. y. nigeriensis sporozoites in rat serum) sporozoite uptak ...19827080155
a cage replacement experiment involving introduction of genes for refractoriness to plasmodium yoelii nigeriensis into a population of anopheles gambiae (diptera: culicidae). 19827086849
[immediate inhibition of the infectivity of gametocytes of plasmodium yoelii nigeriensis by serum from rodents infected for 5 days]. 19827181381
the role of the kupffer cell in the infection of rodents by sporozoites of plasmodium: uptake of sporozoites by perfused liver and the establishment of infection in vivo.the uptake of plasmodium yoelii nigeriensis sporozoites by isolated perfused rat liver was very rapid and efficient. 67% of the initial load was removed from the perfusion media in the first passage through the liver, and 95% after 15 min of perfusion. much of the uptake was explained by mechanical trapping in the liver. up to 75% of the sporozoite load was retained after 15 min both by heat killed liver and liver cooled to 4 degrees c, therefore at least 20% of the sporozoite uptake in perfused ...19826122359
susceptibility of anopheles gambiae to plasmodium yoelii nigeriensis and plasmodium falciparum. 19826763502
adp-ribosyltransferase in plasmodium (malaria parasites).the nuclei of plasmodium yoelii nigeriensis contain an enzyme, adp-ribosyltransferase, that will incorporate the adp-ribose moiety of nad+ into acid-insoluble product. the time, ph and temperature optima of this incorporation are 30 min, 8.5 and 25 degrees c respectively. maximum stimulation of the enzyme activity is obtained with 1.0 mm-dithiothreitol or 2.0 mm-2-mercaptoethanol. ca2+ and mg2+ ions at optimum concentrations of 5 mm and 10 mm respectively stimulated the activity of the enzyme by ...19836307262
endoprotease in plasmodium yoelii nigeriensis.1. p. yoelli nigeriensis has an acid endoprotease (cathepsin d) and an endoarylamidase. 2. the acid endoprotease is specific towards haemogloblin. it is found in 2 molecular forms, of molecular weight 100,000 and 50,000. it is inhibited by hematin and pepsatin. 3. in mouse normal red blood cells we find an acid protease having physico-chemical properties similar to those of the enzyme present in p. yoelii nigeriensis extracts, except as regards the phi. 4. in parasite extracts there exists an en ...19836340950
experimentally derived, stable mefloquine resistance in plasmodium yoelii nigeriensis. 19836602406
histopathology and histochemistry of r.e.s. in infections with plasmodium yoelii nigeriensis. 19836631099
oxygen radical release by adherent cell populations during the initial stages of a lethal rodent malarial infection.a series of experiments was carried out to assess the levels of reactive oxygen intermediates (roi) released by macrophages and monocytes during an acute malarial infection, and to consider the importance of oxidant-induced parasite killing in host protection. adherent cell populations were removed from the peritoneum and spleen of balb/c and b10/d2/n mice between days 0-5 of a plasmodium yoelii nigeriensis infection. these cell populations were quantified, characterized and their roi-releasing ...19853000927
monoclonal anti-gamete antibodies prevent transmission of murine malaria.three monoclonal antibodies prepared using spleen cells from mice immunized with microgametes of plasmodium yoelii nigeriensis were tested for their ability to block transmission of the infection. two of them agglutinated microgametes and blocked transmission, this effect being antibody-dose dependent. the third monoclonal used alone was ineffective in both these assays although it stained gametocytes and microgametes by immunofluorescence in the same way as the protective monoclonals. however, ...19853912705
vaccination with purified microgamete antigens prevents transmission of rodent malaria.malaria vaccination with preparations of microgametes has been shown to inhibit transmission of plasmodium spp. to the mosquito vectors of avian, rodent and simian parasites. this transmission-blocking immunity results from the induction of microgamete-agglutinating antibodies in the vaccinated host which, when ingested in a mosquito blood meal, react with exflagellating microgametes in the midgut to prevent fertilization and oocyst development. here we have passively transferred the immunity wi ...19854022122
plasmodium yoelii: induction of attenuated mutants by irradiation.when erythrocytic forms of plasmodium yoelii nigeriensis, which is invariably fatal in mice, were exposed to x rays, the dose to reduce surviving parasites to one millionth was 100 gray (10 krad). a suspension of 5 x 10(6) per ml of parasitized erythrocyte was irradiated at 100 gray, and 0.2 ml aliquots were inoculated into 22 mice. eleven mice showed patent parasitemia, and in these the growth curves were less steep than that found in nonirradiated parasites. the infections of 8 mice of the 11 ...19863780926
effect of plasmodium yoelii nigeriensis infection and chloroquine on the hepatic mixed function oxidase system of mice.plasmodium yoelii nigeriensis infection in albino mice significantly altered the hepatic microsomal mixed function oxidase system. cytochrome p-450 (the terminal monooxygenase) and other monooxygenases, viz. aniline hydroxylase, aminopyrine-n-demethylase and benzo(a)pyrene hydroxylase were significantly lowered while microsomal heme showed 4-fold increase at 80% parasitaemia. noticeable impairment in the other components like nadh:cytochrome b5 reductase, nadph:cytochrome c reductase, cytochrome ...19873627173
[inhibition of the infectivity of plasmodium gametocytes by the serum of the parasite host. perfecting an experimental model].in the course of experimental malarial infections the infectivity of the gametocytes falls abruptly and at an early stage of the infection. this phenomenon is independent of the production of circulating antibodies. with plasmodium yoelii nigeriensis infecting the white mouse, the maximum infectivity of gametocytes for anopheles stephensi occurs on day 2, and on day 5 no more oocysts develop in the mosquito. the behaviour of the plasmodial strain in the mouse and particularly the "crisis" phenom ...19873662325
histidine-rich protein in rodent malaria.mouse red blood cells (rbcs) infected with the malaria parasite plasmodium yoelii nigeriensis were shown to synthesize a histidine-rich protein (his-rp) in vitro. the existence of this protein was demonstrated by comparing fluorograms of infected red blood cells (irbcs) labelled with either [14c]histidine or [14c]leucine. the molecular weight of this his-rp was estimated to be 43,500, which compares well with the values reported for the avian parasite p. lophurae (45,000) and for the human paras ...19873111551
single dose curative and prophylactic efficacy of antimalarial drugs against multi-resistant plasmodium yoelii nigeriensis. 19883256563
selection of plasmodium yoelii nigeriensis resistant to triple drug combination (sulphadoxine/pyrimethamine/mefloquine) and its response to other antimalarials. 19883266603
effect of stress conditions on the course of trophozoite-induced plasmodium yoelii nigeriensis in mice recently cured of a previous infection.the effect of stress conditions on the course of trophozoite-induced plasmodium yoelii nigeriensis in mice recently treated for a previous infection was studied. it was found that when the mice were infected with up to 5943 parasites within 6 days of treating a previous infection, no patent infection was recorded. however, an inoculum of 7924 parasites induced parasitaemia, with a long period of prepatency and a short course of infection before the parasites died out. none of the mice re-infecte ...19882843024
experimental infections of plasmodium yoelii nigeriensis in mice and rats, and hosts' reactions.in investigations into the course of infection of plasmodium yoelii nigeriensis in rats and mice, it was found that adult mice, baby mice and baby rats were susceptible to the infection, while adult rats were totally refractive. the infection was rapidly fatal in baby and adult mice but was maintained with a low parasitaemia and tolerated by baby rats until the animals were 7 weeks old, after which they eradicated the infection totally. although the adult rats did not exhibit any parasitaemia, t ...19892545080
[ultrastructural study on effect of primaquine on sporogonic stage of plasmodium yoelii nigeriensis].ultrastructural changes of oocysts and sporozoites of plasmodium yoelii nigeriensis was observed. anopheles stephensi were allowed to obtain blood meal from the mice which had been administered with primaquine diphosphate at different doses and times. mosquitoes were directed and prepared 6-13 d following infection. electron microscopy showed that the development and morphology of a number of oocysts and sporozoites in infected mosquitoes after treatment became abnormal. the cytoplasma of the oo ...19892610001
antimalarial efficacy of arteether against multiple drug resistant strain of plasmodium yoelii nigeriensis.new quick-acting blood schizontocides are needed to contain the spread of multiple drug resistant strains of p. falciparum and for the treatment of the cerebral malaria cases. a multiple drug resistant strain of p. yoelii nigeriensis resistant to mefloquine (128 mg/kg x 6 days), quinine (300 mg/kg x 7 days) and chloroquine (64 mg/kg x 8 days) was found to be completely susceptible to arteether (a 30:70 mixture of alpha and beta enantiomers) and a dose of 5 mg/kg x 3 days by i.m. route was curati ...19892771860
experimental transfer of immunity to plasmodium yoelii nigeriensis from adult rats to baby rats. 19902251247
the effects of host diet on plasmodium yoelii nigeriensis.a comparative study carried out on infected mice to investigate the effect of host diet on plasmodium yoelii nigeriensis showed that concentrations of blood protein, hemoglobin, and erythrocytes began to decrease in infected mice on day 2 after inoculation and reached the lowest levels on day 8. the greatest decrease was among mice fed on protein-rich mouse cubes, whereas the least decrease was among mice fed on cassava meal. inflammation of the spleens and livers of infected mice also was notic ...19902254825
effect of host-diet inadequacy on the course of infection of plasmodium yoelii nigeriensis.investigations were conducted into the course of infection of plasmodium yoelli nigeriensis in mice fed on an inadequate diet. it was found that mice fed on a '1/2' diet were able to withstand infection with the parasite better than mice fed on a full diet or a 1/4' diet. the haemoglobin value of mice fed on a full, '1/2' and '1/4' diets dropped by 67.5%, 66.8% and 68.8% respectively, while their packed cell volume dropped by 27.1%, 28.9% and 31.2% respectively. no mortality was recorded for uni ...19902268567
plasmodium yoelii nigeriensis circumsporozoite gene structure and its implications for the evolution of the repeat regions.the circumsporozoite (cs) gene encodes the most immunogenic component of the plasmodial sporozoites. the immunodominant epitope-encoding domain of the cs gene shows sequences that are repeated in tandem. a detailed analysis of the cs repeats of certain closely related malaria parasites (strains of plasmodium cynomolgi, plasmodium knowlesi, and plasmodium vivax) showed that they evolve rapidly yet are well conserved within the gene. we were interested in studying whether the cs repeats of plasmod ...19902290446
the effects of chloroquine on the infectivity of chloroquine-sensitive and -resistant populations of plasmodium yoelii nigeriensis to mosquitoes.subtherapeutic doses of chloroquine have been reported to enhance infectivity of drug-resistant plasmodium species to their vectors. in this investigation, plasmodium yoelii nigeriensis n67 strain showed enhanced infectivity to mosquitoes when stimulated by chloroquine. both sensitive and resistant clones were derived from the n67 strain by dilution, showing that this strain is polymorphic for the resistant trait. a resistant subline was derived by selection under drug pressure from a chloroquin ...19902362764
role of dna-binding antibodies in kidney pathology associated with murine malaria infections.we performed a series of studies to examine the sequential development of nephritis during murine malaria infections and to define the role of dna-binding antibodies in the associated pathology. serum levels of these antibodies were assessed throughout acute and chronic malaria infections. increased levels of double-stranded dna- and single-stranded dna-binding antibodies were initially detected in mice infected with plasmodium vinckei or plasmodium yoelii nigeriensis during the middle stages of ...19902365456
possible involvement of platelets in plasmodium yoelii nigeriensis malaria infection in mice.the possible involvement of platelets in the pathogenesis of malaria was examined by monitoring the changes in platelet function (bleeding time [bt] and thrombin time [tt]) concomitantly with changes in packed cell volume (pcv) and erythrocyte infection rate (eir) in plasmodium yoelii nigeriensis infection in mice. in untreated plasmodium-infected mice, there was a progressive reduction (day 1-7) in bt from 120.0 +/- 12.6 s to 77.5 +/- 5.9 s (p less than 0.005), a reduction in tt from 26.8 +/- 1 ...19911823881
status of hepatic heme and heme oxygenase during plasmodium yoelii nigeriensis infection in mice.plasmodium yoelii nigeriensis infection in albino mice caused a significant increase in hepatic heme level, the increase being concomitant with a rise in parasitemia. this elevated heme was found to be associated with all the subcellular fractions except the cytosol, where its content remained unaltered. activity of heme oxygenase, the key enzyme responsible for catabolism of heme, also increased progressively with rise in parasitemia. treatment of normal mice with cobalt chloride [60 mg (kg bod ...19911884769
penetration of the mosquito midgut wall by the ookinetes of plasmodium yoelii nigeriensis.the penetration route of ookinetes of plasmodium yoelii nigeriensis in the midgut of a mosquito, anopheles omorii, was investigated by electron microscopy. within 15-18 h after an infective blood meal, ookinetes could be seen in the midgut lumen, in the process of entering the midgut wall, or lodged between the basement membrane and the basal lamina. the morphology of the ookinetes and their transformation into early oocysts were found to be similar to those previously reported. ookinetes penetr ...19912047369
"antimalarial" medicinal plants and their impact on cell populations in various organs of mice.we have investigated the effects of leaf and bark decoctions of ocimum gratissimum, azadirachta indica, morinda lucida and enantia chlorantha on (a) the course of plasmodium yoelii nigeriensis malaria (b) reticulocyte and haematocrit values and (c) nucleated cell numbers in the spleen, bone marrow, peritoneum, liver and peripheral blood of swiss albino mice. results obtained showed that normal mice infected with the parasite (10(4)/mouse) suffered fulminant parasitaemia which resulted in death, ...19921308080
aberrations in cerebral vascular functions due to plasmodium yoelii nigeriensis infection in mice.plasmodium yoelii nigeriensis infection in mice caused an increase in uptake of 125i-labeled bovine serum albumin, 51cr-labeled erythrocytes and evans blue dye from peripheral circulation into the brain. isolated cerebral microvessels which were characterized in terms of their morphology under scanning electron microscope and enhancement of the specific activities of biochemical markers, viz. alkaline phosphatase, gamma-glutamyl transpeptidase, and monoamine oxidase, showed significant decrease ...19921356826
trials to infect anopheles stephensi with plasmodium yoelii nigeriensis by the membrane feeding technique.the aim of this study was to find optimal conditions for the membrane feeding technique to obtain maximum infection rates of mosquitoes with plasmodium yoelii nigeriensis. the results show that the malaria parasite plasmodium yoelii nigeriensis is most infective to anopheles stephensi mosquitoes on day 3 of the infection in the mice, 1 day before the peak of parasitaemia. the mortality rate of the mosquitoes fed on mice on day 3 after infection was the highest as compared to mosquitoes fed on ot ...19921456466
the effects of nosema algerae on the development of plasmodium yoelii nigeriensis in anopheles stephensi.experimental simultaneous infections of anopheles stephensi (diptera: culicidae) with nosema algerae (microsporida: nosematidae) and plasmodium yoelii nigeriensis under standardized laboratory conditions showed partial suppression of the malaria parasite. at 9 days after an infective bloodmeal, the oocysts in the midgut were counted; 12.1%-66.6% of the double-infected mosquitoes exhibited no oocysts, whereas only 4.5%-12% of the control group showed no oocysts. the mean reduction in oocyst numbe ...19921584748
[schizogony of plasmodium yoelii nigeriensis. role of latent merozoites].several procedures were employed to try to specify the schizogonic cycle of plasmodium yoelii nigeriensis. the percoll-glucose gradient technique for concentrating the very young stages (rings and young trophozoites), allowing a very precise follow up of the development of the parasitaemia during the first schizogonic cycles. a method for studying the prepatencies, providing an approximation of the number of merozoites inoculated. a comparison between the numbers of merozoites present in the blo ...19938154783
synchronization of plasmodium yoelii nigeriensis and p. y. killicki infection in the mouse by means of percoll-glucose gradient stage fractionation: determination of the duration of the schizogonic cycle.the youngest (rings and young trophozoites) erythrocytic stages of plasmodium yoelii nigeriensis and p. yoelii killicki, two rodent malaria subspecies developing very asynchronously in the blood, were separated from the other stages using a discontinuous percoll-glucose gradient. they were inoculated into mice and the subsequent infection remained synchronous for two generations. the duration of the asexual cycle was found to be 18 h.19948202457
plasmodium yoelii nigeriensis: biological mechanisms of resistance to chloroquine.the sensitivity to chloroquine according to the degree of synchronicity of plasmodium yoelii nigeriensis, which is considered to be the most resistant of the rodent malaria strains, was studied. the infection was synchronised by means of a percoll-glucose gradient which separates rings and young trophozoites from other stages. the mid-term trophozoite, when it predominated in the blood at the time of treatment, was shown to be as sensitive to chloroquine as plasmodium vinckei petteri. according ...19949140489
neuropathological studies on plasmodium yoelii nigeriensis-induced malaria in mice.malaria infection in mice was produced by intraperitoneal inoculation of 10(6) erythrocytes parasitized with plasmodium yoelii nigeriensis, a virulent strain of murine malaria. about one week after infection parasitaemia ranged between 60 and 80%, and 100% mortality was observed. infected animals were killed 6 days after infection to allow the examination of brain tissue. electron microscopical observations revealed marked damage to cerebral vascular vessel walls with separation of muscular laye ...19948040397
plasmodium vinckei vinckei and p. yoelii nigeriensis: pattern of gametocyte production and development.the morphological evolution and the periodicity of the gametocytes of two rodent malaria species were studied in the white mouse. experiments with plasmodium vinckei vinckei, a highly synchronous species, showed that the production of the sexual stages was periodic and was set by the specific rhythm of the asexual stages, i.e. the time of inoculation and the duration of the cycle in the blood. the duration of gametocytogenesis from merozoite to stage 0 was approximately 30 hours, and from stage ...19958532362
plasmodium yoelii nigeriensis: the effect of high and low intensity of infection upon the egg production and bloodmeal size of anopheles stephensi during three gonotrophic cycles.anopheles stephensi mosquitoes showed a reduction in fecundity over 3 successive gonotrophic cycles, after becoming infected with plasmodium yoelii nigeriensis. this effect could be observed at high oocyst burdens (> 75) or at low oocyst burdens (mean of 4.36). mean bloodmeal size of the infected mosquitoes was significantly reduced only when feeding upon a mouse with a high gametocytaemia and the conversion of the bloodmeal into eggs by the infected mosquitoes was disrupted. patterns of infecte ...19958559587
postprandial lymphatic flux and malaria.24 hours after an intra-peritoneal inoculation of frozen blood infected with plasmodium yoelii nigeriensis, the malarial infection is non detectable in most starved mice while it is patent in mice fed 2 hours before the inoculation. it is assumed that the post feeding lymphatic flow brings to the blood the latent merozoites.19958745741
immunization of albino mice using chloroquine attenuated plasmodium yoelli nigeriensis.in an attempt to induce chloroquine resistance in plasmodium yoelii nigeriensis by the method of drug pressure, it was found that the mice continued to be infected until the fourth passage when they became refractory or immune to the infection. when the immune mice were challenged at four weekly intervals, they remained refractory to the infection until week 12 when one of them became infected. however, by the sixteenth week, the rest of the mice became susceptible to the infection. four of the ...19958904069
antimalarial effects of c18 fatty acids on plasmodium falciparum in culture and on plasmodium vinckei petteri and plasmodium yoelii nigeriensis in vivo.following the demonstration of the antimalarial effect of the long chain saturated alcohol n-hentriacontanol ((ch2)29ch2oh), isolated from the bolivian endemic solanaceous plant cuatresia sp., we have tested the effect of the c18 fatty acids oleic, elaidic, linoleic, and linoleic on malaria parasites. these fatty acids inhibited the parasitemic development in mice infected with plasmodium vinckei petteri or with plasmodium yoelii nigeriensis in a 4-day suppressive test. to gain a deeper discernm ...19957628573
malaria-induced reduction of fecundity during the first gonotrophic cycle of anopheles stephensi mosquitoes.anopheles stephensi mosquitoes which had fed upon mice infected with plasmodium yoelii nigeriensis malaria parasites produced significantly fewer eggs than mosquitoes fed on an uninfected mouse. fecundity reduction was more pronounced when the bloodmeal contained malaria gametocytes and the mosquitoes developed oocysts. egg production and haematin excretion were correlated for uninfected bloodfed mosquitoes; the presence of p.y.nigeriensis in the blood affected this relationship. reduced fecundi ...19957787226
induction of chloroquine resistance in plasmodium yoelii nigeriensis.chloroquine resistance was induced in plasmodium yoelii nigeriensis by the method of drug pressure. twenty five albino mice were used at each passage and each of them was inoculated intra-peritoneally with approximately 10(5) erythrocytes infected with the parasite. the first fifteen mice divided into three groups of five mice each were treated with different sub-curative doses of chloroquine which usually cleared the infection for a few days before recrudescence. inocula for passages to the nex ...19968997840
efficacy of cymbopogon giganteus and enantia chrantha against chloroquine resistant plasmodium yoelii nigeriensis.the antimalarial activity of boiled water extracts of two medicinal plants (cymbopogon giganteus and enantia chlorantha) against chloroquine resistant plasmodium yoelii nigeriensis in albino mice was assessed. twenty-five mice were used for each extract. each mouse was inoculated with approximately 10(5) erythrocytes infected with chloroquine-resistant p.y. nigeriensis. at five to seven percent parasitaemia, the mice were randomly divided into five groups of five mice each. the first four groups ...19968997841
adoptive transfer of immunity induced with chloroquine attenuated plasmodium yoelii nigeriensis from immune to immunologically naive mice.immunity was induced in albino mice using chloroquine-attenuated plasmodium yoelii nigeriensis which had been maintained under drug pressure in 4 passages. attempts were made to adoptively transfer immunity from the immune to immunologically naive mice by means of serum, spleen and thoracic duct extracts. none of them conferred complete immunity on the recipients but some protection was gained. this was evident from the prolongation of both the pre-patent periods of the infection and the surviva ...19979133824
the effect of plasmodium yoelii nigeriensis infection on ovarian protein accumulation by anopheles stephensi.both anopheline and culicine mosquitoes have been shown to incur a reduction in reproductive fitness when infected with malaria parasites. the agent of rodent malaria, plasmodium yoelii nigeriensis, was used as a laboratory model to investigate changes in the accumulation of protein in the ovaries of anopheles stephensi when infected with oocysts or when feeding on mice with heavy asexual parasitaemia but no mature gametocytes. herein we report that during the early phases of the gonotrophic cyc ...19979134561
role of macrophages as possible transporters of plasmodium yoelii nigeriensis merozoites through the lymphatic system. preliminary note.vesicles containing apparently healthy merozoites from mature schizonts were observed in the spleen and lymph nodes of mice parasitized by plasmodium yoelii nigeriensis. they differed from all parasitic stages undergoing digestion by the macrophage and from mature schizonts of the blood. up to 40 merozoites from three mature schizonts may be seen in the same compartment. they are thought to be accumulations of latent merozoites.19979208034
poly iclc enhances the antimalarial activity of chloroquine against multidrug-resistant plasmodium yoelii nigeriensis in mice.swiss mice infected with multidrug-resistant plasmodium yoelii nigeriensis were treated with polyinosinic-polycytidylic acid stabilized with polylysine and carboxymethyl cellulose (poly iclc), a potent interferon (ifn) inducer and immune enhancer, in combination with chloroquine (cq), which completely eliminated the malaria parasite from these animals. the enhancement of the antimalarial activity of poly iclc was found to be completely reversed by the cytochrome p-450 inducer, phenobarbitone. no ...19979243375
the effects of infection with plasmodium yoelii nigeriensis on the reproductive fitness of anopheles stephensi.infection with the rodent malarial parasite plasmodium yoelii nigeriensis caused a significant reduction in the reproductive fitness (number of eggs produced and proportion of eggs hatched) of two different generations of anopheles stephensi. overall fertility (number of larvae produced) was reduced by 38.3% in the generation containing smaller mosquitoes (with a wing length of 3.2 +/- 0.1 mm) with relatively larger parasite burdens, and by 48.81% in the generation containing larger mosquitoes ( ...19979290843
effects of plasmodium yoelii nigeriensis infection on anopheles stephensi egg development and resorption.it has been shown previously that infection with plasmodium yoelii nigeriensis reduces the number of eggs produced by female anopheles stephensi. here we examine the mechanism underlying fecundity reduction. ovaries from infected and uninfected (control) female mosquitoes were examined 12, 24 or 36 h after blood-feeding during the first gonotrophic cycle (replicated) or the second gonotrophic cycle (unreplicated). follicular development was assessed according to christophers' stages and the prop ...19979330258
causal prophylactic activity of antihistaminic agents against plasmodium yoelii nigeriensis infection in swiss mice.the causal prophylactic activity of five tricyclic anti-histaminic agents (histamine h1-receptor antagonists) cyproheptadine, ketotifen, loratadine, azatadine and terfenadine was evaluated in an experimental murine malaria model. sporozoite induced infections with plasmodium yoelii nigeriensis (n-67), a strain innately resistant to choloroquine, were employed for the efficacy test and pyrimethamine and primaquine were used as standard reference drugs. treatment with cyproheptadine or ketotifen a ...19989638277
effect of plasmodium yoelii nigeriensis (haemosporidia: plasmodiidae) on anopheles stephensi (diptera: culicidae) vitellogenesis.our previous studies demonstrated a significant reduction in the egg production and survival of anopeles stephensi liston infected with plasmodium yoelii nigeriensis killick-kendrick. we investigated the physiological mechanism underlying the malaria-induced curtailment of reproductive fitness. polyclonal antibodies were raised against an. stephensi vitellin (vn) and used in an enzyme immunoassay to quantify ovarian vn and hemolymph vitellogenin (vg) at 8, 12, 16, 20, 24, and 48 h postblood feed ...19989835686
docetaxel (taxotere): effectiveness against plasmodium falciparum in vitro and plasmodium yoelii nigeriensis in vivo. 199810622642
studies on hepatic oxidative stress and antioxidant defence system during chloroquine/poly iclc treatment of plasmodium yoelii nigeriensis infected mice.reactive oxygen species are important mediators of tissue injury during malaria infection. the status of hepatic oxidative stress and antioxidant defence indices were studied during plasmodium yoelii nigeriensis (p. y. nigeriensis) infection and chloroquine/ polyinosinic-polycytidylic acid stabilized with polylysine and carboxymethylcellulose (poly iclc) treatment of infected mice. p. y. nigeriensis infection resulted in a significant increase in oxidative stress indices viz., xanthine oxidase a ...199910391138
studies on hepatic oxidative stress and antioxidant defence systems during arteether treatment of plasmodium yoelii nigeriensis infected mice.reactive oxygen species play an important role in pathology during malaria infection. the status of hepatic oxidative stress and antioxidant defence indices was studied during plasmodium yoelii nigeriensis (p. y. nigeriensis) infection in mice and arteether treatment of p. y. nigeriensis infected mice. p. y. nigeriensis infection caused a significant increase in hepatic xanthine oxidase, rate of lipid peroxidation, reduced glutathione (gsh) and glutathione reductase with progressive rise in para ...199910448917
the effect of plasmodium yoelii nigeriensis infection on the feeding persistence of anopheles stephensi liston throughout the sporogonic cycle.vector-borne parasites such as malaria have been shown to modify the feeding behaviour of their invertebrate hosts so as to increase the probability of transmission. however, evolutionary consideration of developmental changes in malaria within anopheles mosquitoes suggests that the nature of altered feeding by mosquitoes should differ depending on the developmental stage of the parasite. we present laboratory evidence that the feeding persistence of female anopheles stephensi towards a human ho ...199910518321
mice immunised with synthetic peptide from n-terminal conserved region of merozoite surface antigen-2 of human malaria parasite plasmodium falciparum can control infection induced by plasmodium yoelii yoelii 265by strain.synthetic peptides representing conserved msa-2 sequences are being considered as a possible component of a blood stage malaria vaccine. antibody response towards the entire n-terminal conserved region of msa-2 and its constituent b-epitope sntfinna following immunisation of balb/c and c57bl/6 mice with different peptide constructs was assessed by elisa and immunofluorescence antibody test (ifat). co-linear synthesis of sntfinna-epitope in tandem with the entire n-terminal conserved region pepti ...199910580206
selection of anopheles dirus for refractoriness and susceptibility to plasmodium yoelii nigeriensis.two lines of the oriental malaria vector mosquito anopheles dirus species a (diptera: culicidae), one fully refractory and one fully susceptible to plasmodium yoelii nigeriensis (an african rodent malaria parasite), were established after 17 generations of mass selection, followed by single female selection for one or two generations. prior to selection, the stock colony of an. dirus was 17% refractory. both lines of an. dirus produced abundant ookinetes that started to invade the midgut within ...199910608223
blood digestion in the mosquito, anopheles stephensi: the effects of plasmodium yoelii nigeriensis on midgut enzyme activities.midgut proteases contribute to the success or failure of plasmodium infection of the mosquito. this paper examines the reciprocal effect of plasmodium yoelii nigeriensis on midgut trypsin, chymotrypsin, aminopeptidase and carboxypeptidase in the mosquito anopheles stephensi. the total protein ingested and the rate of protein digestion were unaffected by the parasite, but more protein was ingested at the first than the second bloodmeal. all peptidases were unaffected by the presence of the parasi ...199910633914
inhibition of the development of the hepatic stages of plasmodium yoelii nigeriensis by antihistaminic agents. 199910656045
status of hepatic oxidative stress and antioxidant defense systems during chloroquine treatment of plasmodium yoelii nigeriensis infected mice.plasmodium yoelii nigeriensis (p. y. nigeriensis) produces lethal malaria infection in swiss albino mice. reactive oxygen species (ros) such as superoxide anion, hydrogen peroxide have been implicated in the pathogenesis of malaria.199910757052
plasmodium yoelii nigeriensis (mdr)-efficacy of oral pyronaridine against multidrug-resistant malaria in swiss mice.a multidrug-resistant strain of plasmodium yoelii nigeriensis (mdr) showing a wide spectrum of resistance to chloroquine, amodiaquine, mepacrine, mefloquine, halofantrine, quinine, and quinidine was used in this study for in vivo evaluation of the blood schizontocidal activity of pyronaridine, a topoisomerase ii inhibitor, in swiss mice. the parasite produces 100% lethal infection in mice. the drug was administered orally once a day from day 0 onward. the initial studies showed that low doses of ...200010831384
immune responses mediating survival of naive balb/c mice experimentally infected with lethal rodent malaria parasite, plasmodium yoelii nigeriensis.the rodent malaria parasite, plasmodium yoelii nigeriensis is known to cause fatal malaria infections in balb/c mice. however, we found that nearly 5% of inbred balb/c mice could overcome primary infections initiated with lethal inoculum of p. y. nigeriensis asexual blood-stages, without any experimental intervention. these 'survivor' mice developed peak parasitemia levels of about 5% and successfully resolved their infections in about two weeks time; infected blood collected during the descendi ...200010865192
studies on erythrocytic methemoglobin reductase systems in plasmodium yoelii nigeriensis infected mice.the methemoglobin reductase system plays a vital role in maintaining the equilibrium between hemoglobin and methemoglobin in blood. exposure of red blood cells to oxidative stress (pathological/physiological) causes an impairment in this equilibrium.200010945172
pyronaridine: an effective antimalarial against multidrug-resistant malaria.pyronaridine, administered intramuscularly (im) to swiss mice infected with the lethal multidrug-resistant plasmodium yoelii nigeriensis, was found to exert high blood schizontocidal activity. the efficacy of doses of pyronaridine ranging from 0.625 to 30 mg (base/kg) was evaluated using a 4 day treatment schedule (drug was administered at 0, 24, 48 and 72 hrs). it was found that doses of 2.5mg/ kg and higher protected animals completely from the lethal effects of the parasite. the same degree o ...200010968405
modulation of halofantrine resistance after coadministration of halofantrine with diverse pharmacological agents in a rodent malaria model.the declining efficacy of antimalarial drugs against plasmodium falciparum strains has been reported from several endemic regions of the world. strategic evaluation of several pharmacological agents in combination with chloroquine to enhance the sensitivity of the latter against resistant parasites has been documented in several studies. however no attempts have been directed to monitor the efficacy of such biological response modifiers for reversing the resistance to halofantrine. in the presen ...200010972203
effect of tumor necrosis factor on hepatic oxidative stress and antioxidant defense indices in normal and plasmodium yeolii nigeriensis infected mice.plasmodium yoelii nigeriensis (p. y. nigeriensis) produces lethal malaria infection in swiss albino mice. reactive oxygen species (ros) such as superoxide anion, hydrogen peroxide along with endogenously produced tumor necrosis factor (tnf) have been implicated in the pathogenesis of malaria.200011071400
interaction between chloroquine and diverse pharmacological agents in chloroquine resistant plasmodium yoelii nigeriensis.the effect of a number of pharmacological agents on the enhancement of antimalarial activity of chloroquine was evaluated against chloroquine resistant line of plasmodium yoelii nigeriensis (n-67). the response after combination therapy was monitored on the basis of alteration in the course of parasitaemia, the extension of mean survival time and the percent cure rate in different groups. the study was designed to compare the in vivo efficacy of a number of resistance modulating agents found eff ...200011080509
glucose transport in cerebral microvessels during plasmodium yoelii nigeriensis infection in mice.plasmodium yoelii infected cerebral micro vessels of mice registered a significant increase in d-[u-14c] glucose transport as compared to normal microvessels which was found to be time, temperature and concentration dependent. metabolic inhibitors galactose, manose, 2-deoxy glucose and d-glucose showed noticeable inhibition of the same.200011198395
azithromycin: antimalarial profile against blood- and sporozoite-induced infections in mice and monkeys.the spectrum of antimalarial activity of the new macrolide antibiotic azithromycin was evaluated against blood- and sporozoite-induced infections with a chloroquine-resistant strain of plasmodium yoelii nigeriensis (n-67) in swiss mice and with simian parasite plasmodium cynomolgi b in rhesus monkeys. against experimental rodent malaria, a 70 mg/kg/day dose showed curative blood-schizontocidal activity in a four-dose regimen administered orally from day 0 to day 3 or from day 2 to day 5 to mice ...200010631075
effect of poly iclc treatment on hepatic oxidative stress and antioxidant defense indices in plasmodium yoelii nigeriensis infected mice.plasmodium yoelii nigeriensis (p. y. nigeriensis) produces lethal malaria infection in swiss albino mice. reactive oxygen species (ros) are important mediators of tissue injury during malaria infection.200111286134
effect of beta-arteether treatment on erythrocytic methemoglobin reductase system in plasmodium yoelii nigeriensis infected mice.the methemoglobin reductase system plays a vital role in maintaining the equilibrium between hemoglobin (hb) and methemoglobin (methb) in blood. exposure of red blood cells to an oxidative stress (pathological/physiological) may cause impairment in this equilibrium.200111360434
the influence of host haematocrit on the blood feeding success of anopheles stephensi: implications for enhanced malaria transmission.two studies were carried out to determine the effect of the rodent malaria plasmodium yoelii nigeriensis on the blood feeding success of anopheles stephensi. initially, pairs of mice with similar packed cell volume (pcv) (measured by haematocrit) were selected. following infection of one of the pair its pcv gradually fell. at various times post-infection, a comparison was made of the bloodmeal size (haemoglobin content) of mosquitoes feeding on these mice. the bloodmeal sizes increased with para ...200111393821
changes in rodent-erythrocyte methemoglobin reductase system produced by two malaria parasites, viz. plasmodium yoelii nigeriensis and plasmodium berghei.the methemoglobin reductase system plays a vital role in maintaining the equilibrium between hemoglobin and methemoglobin in blood. exposure of red blood cells to oxidative stress (pathological/physiological) may cause impairment to this equilibrium. we studied the status of erythrocytic methemoglobin and the related reductase system during plasmodium yoelii nigeriensis infection in mice and p. berghei infection in mastomys. malaria infection was induced by intraperitoneal inoculation with 10(6) ...200111435127
effects of malaria infection on vitellogenesis in anopheles gambiae during two gonotrophic cycles.we report changes in the abundance of vitellogenin (vg) mrna, and concentration of haemolymph vg and ovarian vitellin (vn) in anopheles gambiae following infection with plasmodium yoelii nigeriensis. a parasite-induced reduction in vg mrna abundance was first detected 24 h after feeding on an infective blood meal, when ookinetes were invading the midgut. during a second gonotrophic cycle post-infection, developing oocysts reduced vg mrna abundance by up to 33% and the effect was detected from 2 ...200111520358
malaria-induced apoptosis in mosquito ovaries: a mechanism to control vector egg production.many insects are able to adjust their egg production according to physiological conditions such as nutrient supply and mating success. one way in which this is achieved is by resorption of some, or all, of the ovarian follicles at some stage during oogenesis. we have shown that the mosquito anopheles stephensi responds in this manner when ookinetes of the malaria parasite plasmodium yoelii nigeriensis first begin to invade the midgut. little is known about the initiation and regulation of follic ...200111683433
antagonist effect of chloroquine and tumor necrosis factor on hepatic oxidative stress and antioxidant defense in normal and plasmodium yoelii nigeriensis-infected mice.plasmodium yoelii nigeriensis (p. y. nigeriensis) produces lethal malaria infection in swiss albino mice. tumor necrosis factor (tnf) has been implicated in the pathogenesis of malaria by production of reactive oxygen species. chloroquine is a traditionally used antimalarial and has been postulated to inhibit tnf secretion during malaria infection.200211980364
haem polymerase as a novel target of antimalarial action of cyproheptadine.an antihistaminic drug, cyproheptadine (20-25mg/kg x 4 days), showed significant schizontocidal activity in the blood against a lethal multidrug-resistant (mdr) strain of plasmodium yoelii nigeriensis (highly resistant to chloroquine, mefloquine, and quinine); the protection of mice ranged between 75 and 100%. a combination of cyproheptadine (15 mg/kg) and chloroquine improved antimalarial activity compared to treatment with either drug alone, whereas a combination of cyproheptadine with quinine ...200212392821
production and characterization of monoclonal antibodies against asexual stages of plasmodium yoelii nigeriensis.swiss mice vaccinated with plasmodium yoelii nigeriensis-soluble antigen and saponin, following a homologous 100% lethal challenge, showed 60% protection (6 out of 10 mice survived). monoclonal antibodies (mabs), generated by hybridizing the sp2/0 myeloma cells with the splenocytes of each of these ten mice, separately, were screened using enzyme-linked immunosorbent assay (elisa), and were characterized by using merozoite (mz) invasion inhibition assay in vitro, immunofluorescence assay (ifa), ...200212573112
prophylactic effect of multi-herbal extract 'agbo-iba' on malaria induced in mice.to determine the efficacy of a multi-herbal preparation extract of 'agbo-iba' on rodent malaria induced in mice.200212638827
trypsin and aminopeptidase activities in blood-fed females anopheles dirus (diptera: culicidae) of differing susceptibility to plasmodium yoelii nigeriensis.midgut proteolytic enzymes contribute to the success or failure of plasmodium infection of the mosquito. the present study investigated trypsin and aminopeptidase activities in the midgut of two strains of anopheles dirus selected for susceptibility and refractoriness to plasmodium yoelii nigeriensis. at intervals of 6 hours following a bloodmeal, the midguts of fully engorged female mosquitos were dissected, homogenized, and assayed for enzyme activity. no differences trypsin activity (nmole/mi ...200212757211
nitric oxide protects against chloroquine resistant plasmodium yoelii nigeriensis parasites in vitro.malaria is a life-threatening disease of global concern. the role of nitric oxide in the clearance of malarial parasites is still under debate. several reports suggest a possible role for nitric oxide in the protection during initial stages of malarial infection. in the present study, we demonstrate that the nitric oxide in combination with low concentrations of chloroquine controls the parasitaemia in vitro. activated peritoneal macrophages co-cultured with lipopolysaccharide+interferon-gamma o ...200314990311
effects of autacoid inhibitors and of an antagonist on malaria infection in mice.the effects of p-chlorophenylalanine, an inhibitor of serotonin synthesis, indomethacin, an inhibitor of prostaglandin synthesis, cyproheptadine, a serotonin, bradykinin and histamine antagonist, were assessed separately and in combination with chloroquine (cq) in vom strains of swiss albino mice (18-22 g) of either sex infected intraperitoneally with 1 x 10(7) plasmodium yoelii nigeriensis-induced malaria. as prophylactic, these agents reduced from 31.9 +/- 4.5 to 16.1 +/- 8.1% the level of par ...200415273821
resistance reversal action of ketoconazole against mefloquine resistance of plasmodium yoelii nigeriensis.ketoconazole at 200 mg/kg dose has been found to exert marginal antimalarial action against multidrug resistant (mdr) plasmodium yoelii nigeriensis (p. yoelii nigeriensis) in swiss mice with 25% protection (2/8 mice) while at lower ketoconazole dose i.e., 75-100 mg/kg, 14.28% mice were protected. mefloquine (mfq) (at 8 and 16 mg/kg) exerted suppressive action against mdr p. yoelii nigeriensis resulting in 25 and 14.28% protection of mice respectively. combined treatment with ketoconazole and mef ...200415363936
merozoite surface protein 4/5 provides protection against lethal challenge with a heterologous malaria parasite strain.immunization with merozoite surface protein 4/5 (msp4/5), the murine malaria homologue of plasmodium falciparum msp4 and msp5, has been shown to protect mice against challenge by parasites expressing the homologous form of the protein. the gene encoding msp4/5 was sequenced from a number of plasmodium yoelii isolates in order to assess the level of polymorphism in the protein. the gene was found to be highly conserved among the 13 p. yoelii isolates sequenced, even though many of the same isolat ...200415385485
malaria parasite developmental analyses by the nested polymerase chain reaction method: an implication for the evaluation of mosquito infection rates in epidemiological studies.a malaria mosquito vector, anopheles saperoi, and a non-vector, aedes albopictus, were allowed to feed on mice infected with murine malaria, plasmodium yoelii nigeriensis, and were subsequently monitored for the development of parasites by the nested polymerase chain reaction (pcr) method, using plasmodium genus-specific primer pairs. the mosquitos were divided into two parts, head/thorax and abdomen, for dna analyses. the parasite dna and murine dna for each mosquito were examined in parallel. ...200415916075
8-quinolinamines conjugated with amino acids are exhibiting potent blood-schizontocidal antimalarial activities.alanine, lysine, ornithine and valine conjugated to primaquine and other 8-quinolinamine antimalarials were prepared for blood-schizontocidal antimalarial activity evaluation. the analogues were examined in vivo against plasmodium berghei (drug-sensitive strain) and plasmodium yoelii nigeriensis (highly virulent multi-drug-resistant strain) infected mice models. n(1)-[4-(5-butoxy-4-ethyl-6-methoxy-8-quinolylamino)pentyl]-(2s)-2,6-diaminohexanamide (20) which showed curative activity at 5mg/kg in ...200414697789
evaluating the costs of mosquito resistance to malaria parasites.costly resistance mechanisms have been cited as an explanation for the widespread occurrence of parasitic infections, yet few studies have examined these costs in detail. a malaria-mosquito model has been used to test this concept by making a comparison of the fitness of highly susceptible lines of mosquitoes with lines that are resistant to infection. malaria infection is known to cause a decrease in fecundity and fertility of mosquitoes; resistant mosquitoes were thus predicted to be fitter th ...200516526504
studies on drug metabolizing enzymes during arteether treatment of plasmodium yoelii nigeriensis infected mice cerebral microvessels.human cerebral malaria is caused by a protozoan parasitic with no cure till date. the isolation of brain capillaries i.e. microvessels has permitted the in vitro study related to cerebral function. microvessels were isolated from normal and p. yoelii infected mice brain cortex and subjected to biochemical characterization by the following enzyme markers viz alkaline phosphatase, gamma-glutamyi transpeptidase and monoamine oxidase and electron microscopically. limited studies have been carried ou ...200516637400
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