Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in vivo and in vitro response of Plasmodium falciparum to chloroquine was conducted in Ankazobe, a village located in the high plateau area. These studies confirmed the low level of chloroquine-resistance. The in vivo data indicate the absence of increase resistance during the 2 years study. Chloroquine is still the drug of choice for the treatment of malaria attack in this area.
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PMID:[Stability and chemosensitivity of Plasmodium falciparum to chloroquine in 1990 and 1991 in Ankazobe, a village in high plateau Madagascar]. 142 72

An Australian expatriate on regular weekly antimalarial prophylaxis with chloroquine base and Maloprim developed symptomatic Plasmodium vivax infection which failed to respond adequately to 600 mg of chloroquine base. More ominously, a resident of the Highlands region of Papua New Guinea contracted vivax malaria which failed to be cleared by 2400 mg chloroquine base administered over 4 d. Both patients had achieved appropriate blood and plasma concentrations of chloroquine after treatment. Chloroquine-resistant P. vivax is now a clinical fact in Papua New Guinea.
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PMID:Chloroquine-resistant Plasmodium vivax in Papua New Guinea. 144 Jul 63

The use of the Giemsa-stained thick blood smear for the diagnosis of malaria has not been supplanted since the discovery of the parasite by A. Laveran in 1880. Recently, a new direct diagnosis technique, the Quantitative Buffy Coat (QBC)* Malaria Diagnosis System, has been developed. We compared this technique with the thick blood smear diagnosis in a study of the efficacy of chloroquine therapy in Zaire. A total of 815 subjects were screened; 71 participated in the trial. They were given chloroquine at a dose of 25 mg/kg of body weight over three days and were examined for parasitemia two and seven days after treatment. Chloroquine resistance was detected in 38% of the subjects by thick blood smear and in 45% by the QBC test. Of greater interest was the time required for each diagnosis: an average of 17 min was required to examine microscopic fields with 1,000 leukocytes by thick blood smear analysis compared with less than one min by the QBC system. In addition, we did not observe diminished attention from fatigue by microscopists using the QBC system despite the large number of tests conducted. We conclude that the QBC system is an important tool for studies of drug resistance.
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PMID:Rapid in vivo detection of chloroquine resistance by the Quantitative Buffy Coat Malaria Diagnosis System. 144 41

The in vitro activity of halofantrine was studied in chloroquine-susceptible and chloroquine-resistant African clones of Plasmodium falciparum over a period of six months. The susceptibility level remained stable in both clones. The chloroquine-susceptible clone (50% inhibitory concentration [IC50] 6.88 nM) was less susceptible to halofantrine than the chloroquine-resistant clone (IC50 2.98 nM). Using an isotopic semimicro drug susceptibility test, the in vitro activity of halofantrine was compared with the activities of chloroquine, quinine, and mefloquine to study the cross-resistance patterns against 76 African isolates of P. falciparum isolated from cases of malaria imported into France. Chloroquine-resistant isolates (n = 47) were significantly less susceptible to quinine (IC50 234 nM), but were more susceptible to both mefloquine (IC50 3.20 nM) and halofantrine (IC50 1.14 nM) compared with the chloroquine-susceptible isolates (n = 29; IC50 147 nM for quinine, 7.16 nM for mefloquine, and 2.62 nM for halofantrine). A significant positive correlation was found between the activities of chloroquine and quinine and between those of mefloquine and halofantrine, indicating cross-resistance between these drugs, while a negative correlation was observed between chloroquine and mefloquine or halofantrine. The responses to quinine and mefloquine or halofantrine showed no correlation with each other. These results reinforce the importance of a cautious use of antimalarial drugs in Africa.
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PMID:In vitro activity of halofantrine and its relationship to other standard antimalarial drugs against African isolates and clones of Plasmodium falciparum. 144 51

An audit of the management of falciparum malaria was carried out over a 12 month period in a north-west Tanzanian district hospital; 1494 patients were studied, 75% being children under 5 years. Chloroquine was effective in 1128 cases (79%), 68 patients died, of whom 64 were aged under 5 years; 30 of them died fewer than 2 d after admission; 14 had received quinine chemotherapy. Management can be improved by better diagnosis of anaemia and hypoglycaemia, changing the dose of injectable chloroquine, earlier use of quinine, and enabling doctors to see very ill patients earlier.
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PMID:An audit of the management of malaria in a Tanzanian district hospital. 836 81

The effects of chloroquine diphosphate on body temperature have been investigated in chicks. Chloroquine reduced both central and peripheral temperatures. The hypothermic action of chloroquine depended on the dose administered. The hypothermic action of chloroquine was maximal in chicks less than 6 days post-hatching; this effect decreased with increasing age. It is suggested that the hypothermic effect of chloroquine might contribute to its antipyretic activity in malaria fever.
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PMID:The effects of peripherally administered chloroquine on body temperature. 152 47

Chloroquine inhibits the growth of susceptible malaria parasites at low (nanomolar) concentrations because of an energy-requiring drug-concentrating mechanism in the parasite secondary lysosome (food vacuole) which is dependent on the acidification of that vesicle. Chloroquine resistance results from another energy-requiring process: efflux of chloroquine from the resistant parasite with a half-time of 2 min. Chloroquine efflux is inhibited reversibly by the removal of metabolizable substrate (glucose); it is also reduced by the ATPase inhibitor vanadate. These results suggest that chloroquine efflux is an energy-requiring process dependent on the generation and hydrolysis of ATP. Chloroquine efflux cannot be explained by differences in drug accumulation between chloroquine-susceptible and -resistant parasites because the 40-50-fold difference in initial efflux rates between -susceptible and -resistant parasites is unchanged when both parasites contain the same amount of chloroquine. Although chloroquine efflux is phenotypically similar to the efflux of anticancer drugs from multidrug-resistant (mdr) mammalian cells, it is not linked to either of the mdr-like genes of the parasite.
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PMID:Energy dependence of chloroquine accumulation and chloroquine efflux in Plasmodium falciparum. 153 Nov 76

The resurgence of malaria in recent decades has been accompanied by the worldwide spread of resistance to chloroquine, a drug once uncontested as the first-line antimalarial agent because of its efficacy and low toxicity. Chloroquine-resistant strains of Plasmodium falciparum counter the drug by expelling it rapidly via an unknown mechanism. In the absence of explicit biochemical knowledge of this efflux mechanism, reverse genetics provides a powerful approach to the molecular basis of chloroquine resistance. Here we report genetic linkage analysis in which 85 restriction fragment length polymorphism markers were used to examine inheritance of the 14 P. falciparum chromosomes in a laboratory cross between a chloroquine-resistant and a chloroquine-sensitive parasite. Inheritance data from 16 independent recombinant progeny show that the rapid efflux, chloroquine-resistant phenotype is governed by a single locus within an approximately 400-kilobase region of chromosome 7. Identification and characterization of genes within this region should lead to an understanding of the chloroquine-resistance mechanism.
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PMID:Genetic mapping of the chloroquine-resistance locus on Plasmodium falciparum chromosome 7. 167 31

Chloroquine has been reported to antagonise the anti-parasitic action of quinine against Plasmodium falciparum in vitro. We looked for evidence of any such antagonism in vivo. In 123 Malawian children with cerebral malaria treated with parenteral quinine, the likelihood of survival and the rate of recovery were much the same in patients who had taken chloroquine and those who had not. In these circumstances we found no evidence of chloroquine/quinine antagonism.
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PMID:Efficacy of quinine for falciparum malaria according to previous chloroquine exposure. 167 66

Since chloroquine-resistant Plasmodium falciparum (CRPF) has emerged in Nigeria, we monitored the susceptibility of the parasite strain to a standard chloroquine (C25) dose in our Children's Emergency Unit. Chloroquine (CQ) is the drug of choice for malaria chemotherapy in Nigeria. The WHO 7-day in vivo evaluation and Rieckmann's microtitre technique (in vitro test) were used. 33 children of mean age 4.9 years were enrolled in the study. 27 (81.8%) of the in vitro cultures were successful. 16 (59.3%) of the successful isolates still showed schizogony at CQ concentration of 5.7 pmol/well and above. 28 (84.8%) of the children completed the in vivo study. 15 (53.6%) were parasitaemic on day 7 and/or day 14 and were regarded as parasitologic failures. The isolates from 14 of these children showed corresponding in vitro resistance of CQ concentrations equal to or above 5.7 pmol/well. The proportion of RIII (= 13.3%) appears to have increased as compared to 5.9% recorded in 1987. We conclude that there appears to be a good correlation between in vivo evaluation of parasitologic failures (53.6%) and in vitro resistance (59.3%). It thus appears that CRPF is definitely increasing in South-Eastern Nigeria. This can be expected not only to complicate malaria chemotherapy in the Children's Emergency Unit of the University of Calabar Teaching Hospital, but will contribute immensely to the deterioration of malaria therapy and control in Nigeria.
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PMID:Correlation between in vivo and in vitro response of chloroquine-resistant Plasmodium falciparum in Calabar, south-eastern Nigeria. 168 Feb 78


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